EP0662738A1 - Process and device for economical production of brushes with prescribed anisotropy - Google Patents

Process and device for economical production of brushes with prescribed anisotropy Download PDF

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Publication number
EP0662738A1
EP0662738A1 EP94420362A EP94420362A EP0662738A1 EP 0662738 A1 EP0662738 A1 EP 0662738A1 EP 94420362 A EP94420362 A EP 94420362A EP 94420362 A EP94420362 A EP 94420362A EP 0662738 A1 EP0662738 A1 EP 0662738A1
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EP
European Patent Office
Prior art keywords
compression
sheath
brush
horizontal
vertical
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Granted
Application number
EP94420362A
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German (de)
French (fr)
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EP0662738B1 (en
Inventor
Horst Siegemund
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Deutsche Carbone AG
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Deutsche Carbone AG
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
    • H01R43/12—Manufacture of brushes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R39/00—Rotary current collectors, distributors or interrupters
    • H01R39/02—Details for dynamo electric machines
    • H01R39/18—Contacts for co-operation with commutator or slip-ring, e.g. contact brush
    • H01R39/20—Contacts for co-operation with commutator or slip-ring, e.g. contact brush characterised by the material thereof

Definitions

  • the invention relates to the manufacture of brushes for electric motors, and more particularly to a device and a method for economical manufacture of brushes with predetermined anisotropy using this device.
  • the invention relates to a direct manufacture of brushes, that is to say a shaping by compression of conductive powders requiring no final machining of the brush, neither to put it at the desired dimensions nor to fix the electrical connection conductor, manufacturing which makes it possible to obtain brushes with predetermined anisotropy.
  • the anisotropy of a broom is known to constitute an essential parameter which conditions its performance of use. It finds its source in the fact that the brushes are generally obtained by compression of powders some of which can have very high form factors (ratio "largest dimension / small dimension"), for example graphite in particles of thin thickness e (5-20 ⁇ m) and very long or wide (100-200 ⁇ m). This results in a certain orientation of the particles with form factor significantly different from one, and therefore, in fine, an anisotropy of both electrical and tribological properties, the particles with high form factor orienting themselves during the compression step. so that the compression axis is on average parallel to the most small dimension e of these particles (or perpendicular to the plane formed by the largest dimensions).
  • the brush is oriented relative to the manifold so that the compression direction of the brush is the tangential direction "t" of the motor manifold.
  • the tangential direction "t" like the other axial directions "a” and radial “r”, are relative to the collector - see figure 8f.
  • the foot of the brush has at least the curvature of the collector, if not other complementary means, to facilitate the running in of the motor.
  • the head of the broom is provided with a means, typically a nipple, a notch or rib, so that the spring pressing on the head remains well centered and does not risk slipping laterally - hence machining of the head in the processes of the prior art.
  • the device for manufacturing brushes comprises a matrix provided with a cavity intended to receive at least one conductive powder to be compressed and at least one punch for compressing said powder, and is characterized in that said matrix is provided with two concurrent sheaths forming said cavity, and oriented at 90 ° relative to each other, one being oriented vertically, and the other horizontally, and in that each of these sheaths is provided with compression means, comprising at least one compression punch, so as to obtain a biaxial compression of said powder.
  • the devices used industrially according to the prior art typically consist of a vertical sheath provided with two punches, a low punch forming with the vertical sheath a cavity, cavity which is then charged, by the free upper orifice, with at least one conductive powder.
  • the uniaxial compression between punches leads, as already indicated, to the formation of an anisotropic brush, with a so-called “laminated” structure, which is used to improve the switching.
  • this device it is impossible to obtain, by compression, a raw broom with, at its head and / or at its foot, a desired geometrical configuration (centering pin for the head, curvature for the foot, etc. ..), and further having a favorable orientation of its laminated structure.
  • the biaxial compression device makes it possible to obtain both the laminated structure favorably oriented and any geometrical configuration whatsoever desired for the head and the foot of the broom, a typical configuration of the foot being a curvature adapted to that of the collector.
  • the biaxial compression device makes it possible to obtain, directly by pressing conductive powder, a raw broom, the head and / or the foot of which has a desired geometric configuration, while retaining the desired orientation of its laminated structure.
  • the desired laminated structure is obtained during the first compression, while the desired geometric configuration is obtained during the second compression.
  • FIG. 1 shows a schematic perspective view of a biaxial compression device (1) according to the invention.
  • This device (1) comprises a matrix (2) in which two concurrent sheaths, a vertical sheath (3) of section Sv (oblique hatching) and a horizontal sheath (4) of section Sh (vertical hatching) intersect at 90 ° in forming a common intersection space (5) of parallelepiped shape.
  • the vertical sheath is provided with two punches: a high punch (6), and a low punch (6 ').
  • the horizontal sheath is provided with two punches: a left punch (7), and a right punch (7 ').
  • the means known in themselves are not shown for actuating the various punches (6, 6 ', 7 and 7').
  • FIGS. 2a to 2d illustrate, in different stages, the operation of the device (1) and represent a section in the vertical plane along the axis A-B of FIG. 1.
  • the top punch (6) has been moved aside, the other punches being positioned to form a cavity which has been loaded with conductive powder to be compressed (9), and of volume Vo.
  • the left punch (7) has a curved profile.
  • Figure 2b shows the first compression step, in the vertical direction using the top (6) and bottom (6 ') punches.
  • FIG. 2c represents the second compression step, in the horizontal direction using the left (7) and right (7 ') punches, which leads to the final shaping of a raw broom (11) of volume Vf .
  • FIG. 2d shows the next step, during which the horizontal punches (7) and (7 ') are separated, so as to allow the recovery of the raw brush (11) - after the vertical punches (6) have been raised and (6 ') and spacing of the top punch (6), (not shown in Figure 2d).
  • FIG. 3 represents a schematic perspective view of a first variant (1a) of the device (1) according to the invention.
  • FIGS. 4a and 4b are sections in the vertical plane along the axis A-B in FIG. 4.
  • FIG. 4b similar to FIG. 2b, shows the first stage of compression, in the vertical direction using the bottom punch (6 '), after a plate (8) has been placed on the upper plane (20 ) of the matrix (2a) and maintained in this position by means not shown.
  • Figure 4c shows a section of the final raw broom (11).
  • Figure 5a is a top view of the device of Figure 3 which illustrates the fact that the horizontal sheath (4) is formed by precision machining so as to ensure a width 1 with high precision ( ⁇ 1 less than 0.02 mm , and preferably less than 0.01 mm).
  • Figure 6 similar to Figures 1 and 3 shows a second modality (1b) of the device (1).
  • the vertical sheath (3) and the horizontal sheath (4) have the shape of an "L".
  • the bottom vertical punch (6 ') has been provided locally with a transverse allowance (16).
  • Figures 7a to 7c similar to Figures 4a to 4c, are sections in a vertical plane along the axis A-B of Figure 6.
  • FIG. 7a similar to Figure 4a, the horizontal punch (7 ') which includes a hollow portion (14), and the bottom vertical punch (6') are positioned to form a cavity which has been loaded with conductive powder to compress (9), and of useful volume Vo. Both the bottom vertical punch (6 ') and the top plate (8) are provided with a transverse allowance (16).
  • Figure 7b shows the device (1b) at the end of the first vertical compression.
  • FIG. 7c represents the raw brush (11) obtained with two lateral grooves (16a) and a stud (14a).
  • Figures 8a to 8f show variants of raw brushes (11), in section along the plane "r-t", obtained according to the invention. These variants, self-explanatory in themselves, relate to the geometrical configuration (Fig 8a, 8b, 8c and 8d).
  • FIG. 8e end of the foot (18) in "wide” cross hatching - end of the head (19) in "tight” cross hatching
  • FIG. 8f represents the directions "a", "r” and "t" relative to the collector (22).
  • FIG. 10a represents on the one hand a biaxial compression device (1a) according to the invention used in monoaxial compression (horizontal punches 7 and 7 ′) in the initial state, to obtain a raw brush according to the prior art, the powder charge (9) of volume Vo which has not yet started to be compressed, the vertical punch (6 ') being kept raised during all of the compression, and on the other hand it represents, in section along the plane "rt" , the raw broom obtained on which the orientation of the particles after compression has been shown diagrammatically.
  • Figures 10b and 10c similar to Figure 10a, correspond to tests lb and lc respectively.
  • the two rough brushes obtained have a "core” made up of particles oriented favorably along the plane "ar” (orientation obtained during the first vertical compression with the punch 6 '), and two ends with the desired geometric shape, at the head (19 ) and at the foot (18), constituted by a layer of thickness E where the particles are oriented in the plane "a-t" (geometric shape obtained during the second horizontal compression, with the punches 7 and 7 ').
  • FIGS. 11a and 11b relate to the brushes of Example 2. They represent sections of brushes according to the "rt" plane, FIG. 11a being relative to a brush according to the prior art with homogeneous anisotropy, and FIG. 11b to a broom according to the invention.
  • the "heart” of the brush is formed of particles contained in the plane "a-t", while, on a thickness E of two opposite faces of the brush, the particles are oriented according to the plane " ra ".
  • FIG. 12 represents, in section along the plane "rt", a brush of example 3 according to the invention, the initial powder charge (9) being different for the head (19) (represented by crosses) and for the rest of the broom.
  • Figures 13a to 13c and 14a to 14b show devices intended to form brushes with trapezoidal section.
  • the horizontal punches (7,7 ') are of trapezoidal section, the parallel sides of this trapezoidal section being located in the horizontal plane. Compression in the vertical direction is ensured by the bottom vertical punch (6 '), with rectangular section, and the upper plate (8).
  • Figure 13a is a schematic perspective view, similar to Figures 1, 3 and 6, of a device (1c) comprising a matrix (2c) whose horizontal sheath (4) is of trapezoidal section.
  • FIG. 13b represents the so-called common volume (5) which has the shape of a right prism with a trapezoidal base.
  • Figure 13c is a section of the device (1c) of Figure 13a, along a vertical plane passing through AB.
  • Figure 14a is similar to Figure 13a, except that the horizontal sheath (4) has a trapezoidal section whose parallel sides are in the vertical plane. Consequently, the bottom vertical punch (6 ') and the plate upper (8) are provided with inclined parts intended to cooperate with the concurrent sides of said trapezoidal section, as shown in FIG. 14b, which is a section of the device (1d) of FIG. 14a, along a vertical plane and along the direction AB of FIG. 14a.
  • said vertical (3) and horizontal (4) sheaths preferably have respective rectangular, square, or trapezoidal sections S v and S h , which are connected in a common volume (5) preferably resulting , of the orthogonal projection of sections S v and S h - see Figures 1, 3, 6, 14a - Figure 13a illustrating the case where the common volume (5) is not, strictly speaking, the result of the orthogonal projection S v and S h sections insofar as the vertical sheath (3) has a constant section S v in the lower part of the die (2c) used to guide the punch (6 '), section which then widens at level of said common volume (5).
  • the common volume (5) is a rectangular parallelepiped when the sections S v and S h are rectangular or square ( Figure 1).
  • This volume (5) is a right prism with a trapezoidal base when one of the sections S v or S h is a trapezoid ( Figure 13b).
  • the means of compression in the vertical direction is formed by said vertical sheath (3 ) provided at its lower part with a compression punch (6 ') and at its upper part of a removable plate (8) with a surface greater than the section S v of the vertical sheath.
  • This plate (8) is moved during the loading phase of the cavity with said powder to be compressed (9) occupying a useful volume Vo of the "T" shaped cavity, then, after loading of said powder, it is placed on the upper surface (20) of the matrix and kept pressed against it using means known in themselves and not shown (typically one or more hydraulic cylinders exerting a pressure greater than that exerted by the bottom vertical punch (6 ')).
  • the compression means in the vertical direction is formed by said vertical sheath (3) provided at its lower part with a punch compression (6 ') and at its upper part of another compression punch (6), so as to be able to perform along the vertical axis a double effect compression.
  • the invention also provides two methods.
  • a first modality relating to horizontal compression as shown in FIGS. 1, 2a to 2d, 3, 4a to 4b, 5a and 5b, said horizontal sheath (4) is provided with two compression punches, a left punch (7) , and a straight punch (7 '), so that double-effect compression can be effected along the horizontal axis.
  • double-effect compression is very useful for giving the head and foot of the broom a particular geometric configuration, for example that of the brooms in FIGS. 8c and 8d.
  • said horizontal sheath (4) is, at one end, provided with a single punch (7 '), the other end being formed by a portion of one of the walls of the vertical sheath (3).
  • the useful volume cavity Vo containing the powder to be compressed (9) has the shape of an "L” and the device shown in Figures 6, 7a to 7b comprises only two punches. According to the invention, one could also replace the upper plate (8) with a punch (6), and thus obtain a useful volume cavity Vo containing the powder to be compressed (9) in the shape of an inverted "T".
  • said removable upper plate (8) not only serves to close the upper part of the vertical sheath (3), but also forms at the same time the upper wall of said horizontal sheath (4).
  • the advantage of this modality thus appears very clearly, since it suffices for a simple machining to form a horizontal sheath (4) open at its upper part, and having precise dimensions - in particular a precise width 1. See Figures 3 and 5a.
  • the devices according to the invention should advantageously include a differentiated control of the compression means in each direction: said means for compressing a sheath (3 or 4) are used under displacement control, while said means for compressing the other sheath (4 or 3) are used under control of the pressure exerted, the compression means under displacement control or under pressure control being known per se.
  • said two control means are represented symbolically in FIG. 5b.
  • said means for compressing said vertical sheath (3) are placed in works under displacement control, while said means for compressing said horizontal sheath (4) are implemented under control of the pressure exerted.
  • compression under displacement control freezes the section of the brush and creates the desired anisotropy
  • compression under pressure control forms on the one hand the geometric configuration of the head and foot of the brush, but also constitutes the additional pressure necessary for the cohesion and mechanical strength of the brush.
  • the compression means of the vertical sheath (3) are used, under displacement control, and, under pressure control, the compression means of the horizontal sheath (4).
  • displacement control is meant that, after setting in motion of the means for compressing the vertical sheath, these stop as soon as the punch (s) has (have) reached a certain dimension z ( alignment in particular of the punch 6 'with the edges of the horizontal sheath 4 - see figure 5b).
  • pressure control is meant that, after setting in motion of the means for compressing the horizontal sheath, they stop as soon as a certain predetermined pressure is reached.
  • (V o -V i ) / (V o -V f ) deviates from 1.
  • T i / T t is close to 1 or that T c / T t is greater than 0.5 to obtain the desired anisotropy.
  • T i / T t close to 1 (typically between 0.7 and 0.95), so as to simultaneously obtain the laminated structure and the appropriate section of the brush sought, the compression under control pressure (T c / T t between 0.05 and 0.3) used to obtain the desired geometric configuration of the head and foot of the brush.
  • T c / T t between 0.05 and 0.3
  • the means of compression of the horizontal sheath (4) are therefore generally used, as illustrated in FIGS. 8c and 8d, to obtain the desired shape of the head (stud (14a), hole (15) ...) and / or foot of the brush (curvature adapted to that of the collector, striated contact face).
  • any compression means according to the invention can be used to incorporate the electrical connection conductor, or for that matter any other object which must be at least partly embedded in the powder to be compressed.
  • the invention also makes it possible to obtain brushes with differential local density. It is particularly advantageous to have brushes whose head has a "high" density, because this is favorable to the solidity of the assembly of said conductor and the block of compressed powder, and brushes whose foot can have a density " low "so as to facilitate and accelerate the running-in phase of the engine.
  • high or low density is meant not an absolute density value, but a deviation from the average density d m of the brush.
  • a “high” density typically corresponds to a density between 1.05.d m and 1.08.d m .
  • a “low” density typically corresponds to a density between 0.85.d m and 0.95.d m .
  • Such a brush can be obtained with a method using the device (1b) of FIG. 6 in which said horizontal sheath (4) is, at one end, provided with a single punch (7 '), the other end being formed by a portion of one of the walls of the vertical sheath (3).
  • said initial initial compression ratio T i is chosen at least equal to 2, and less than 0, 9 T t .
  • the Applicant has observed that with a relatively high rate of first compression under displacement control, the second compression, which, as already mentioned, allows the geometric configuration of the head and the foot of the broom, also allows, thanks to a compression with a single punch (7 ') of the compressed powder block (10), to obtain a raw brush (11) more dense on the side of the second compression punch than on the opposite side, as shown diagrammatically in FIG. 8e (hatching tighter at the "head" end (19) than at the other "foot” end (18)).
  • a third object according to the invention consists of the brushes produced using the devices and methods according to the invention.
  • the brushes obtained using the devices and according to the methods of the invention are characterized by the heterogeneity of their anisotropy, between the "heart" of the brush and two of the 6 faces of the brush (on a thickness E, of the order of a few millimeters at most): the orientation of the particles in the "core" of the broom is 90 ° from the orientation of the particles in two of the 6 faces of the broom.
  • the particles of the "heart” are oriented in the "ar” plane
  • the particles of the head (19) and the foot (18) are oriented in the "a-t” plane. See Figures 10b and 10c for example.
  • the head (19) and the foot (18) are provided with geometric means (curvature, nipples, holes, etc.) adapted to the use of these brushes, and obtained, according to the invention, directly during the biaxial compression stage.
  • Brushes for auxiliary electric motors of cars have been manufactured - typically for window regulator motor using the biaxial compression device according to the invention (la) shown in FIGS. 3, 4a to 4c, from conventional powders comprising particles of graphite in the form of flakes, particles of large dimensions (from 30 to 300 ⁇ m), but of small thickness (less than 20 ⁇ m). These brushes have the following dimensions: 5mm x 5 mm x 11 mm Figure 9 shows different views of these brushes.
  • the foot (18) of these brushes has a curvature and the curved contact surface (13) has oblique grooves (23).
  • the head (19) of these brushes has a hole (15) intended for centering the spring of the brush (not shown). This foot (18) and this head (19) are obtained thanks to the corresponding geometric shape of the left (7) and right (7 ') horizontal punches of the biaxial compression device (1a).
  • FIGS. 10a to 10c Three series of comparative tests were carried out, denoted 1a, 1b and 1c. There is shown, respectively in FIGS. 10a to 10c, the configuration of the same volume Vo of the powder charge (9) to be compressed, in order to obtain a raw brush (11) of the same final volume Vf.
  • the brush (11) of test la corresponding to the prior art and comprising only a compression along the horizontal axis, is homogeneous and anisotropic, the particles being oriented in the plane "a-t "perpendicular to the direction of compression Tc along the horizontal axis.
  • the brush (11) of test lb is homogeneous and anisotropic, the particles being oriented in the plane "ar" perpendicular to the direction of compression Ti (according to l 'vertical axis), except over a thickness E of about 2 mm at the ends of the brush, at the head (19) and at the foot (18) where the particles are oriented along the plane "a-t", perpendicular to the direction compression Tc (along the horizontal axis).
  • the results obtained are similar to those of test 1b, except that the thickness E is approximately 1 mm, instead of 2 mm for test 1b.
  • the relative resistivity R has been measured, in the direction "r" (Rr), and in the perpendicular direction "t", for the brushes (2a) and (2b): broom 2a broom 2b Rr / Rt neighbor of 3 neighbor of 1
  • the head (19) which comprises a stud (14a) for centering the spring, is relatively isotropic (represented by crosses in FIG. 12).
  • the wear block (25) of the brush (11) consists essentially of an anisotropic material (particles oriented along the plane "ra"), except at the end (foot (18)) where, on a thickness E of material, the orientation of the particles is in the plane "a-t".
  • this brush is advantageous because it ensures very good electrical contact (low ohmic drop) between the cable (12) and the head of the brush (19).
  • the invention is if not revolution, at least an essential step towards simultaneous control the desired orientation of the particles of the broom, the geometric configuration, in particular of the head and the foot of the broom, and the costs.
  • the multiple figures and examples are there to illustrate, by way of examples, the great richness of the invention.
  • the invention makes it possible to economically manufacture a wide variety of brushes, with the most diverse geometric shapes and anisotropies, so that it constitutes the perfect tool for the brush manufacturer who must constantly improve his products and adapt them to new demands.

Abstract

The device forms the brush by using presses (1) acting in two planes at right angles to each other. The compression matrix (2) compresses a conducting powder (5). There are two outer sections (3,4), the first oriented vertically and the second horizontally. Two compression presses (7,7') operate in the horizontal plane and two (6,6') in the vertical plane. Thus compression is obtained simultaneously in two axes, providing the optimum two axes crystal formation.

Description

DOMAINE DE L'INVENTIONFIELD OF THE INVENTION

L'invention concerne la fabrication de balais pour moteurs électriques, et plus particulièrement un dispositif et un procédé de fabrication économique de balais à anisotropie prédéterminée utilisant ce dispositif.The invention relates to the manufacture of brushes for electric motors, and more particularly to a device and a method for economical manufacture of brushes with predetermined anisotropy using this device.

Plus spécifiquement, l'invention est relative à une fabrication directe de balais, c'est à dire à une mise en forme par compression de poudres conductrices ne nécessitant pas d'usinage final du balai, ni pour le mettre aux cotes souhaitées ni pour fixer le conducteur de connexion électrique, fabrication qui permet d'obtenir des balais à anisotropie prédéterminée.More specifically, the invention relates to a direct manufacture of brushes, that is to say a shaping by compression of conductive powders requiring no final machining of the brush, neither to put it at the desired dimensions nor to fix the electrical connection conductor, manufacturing which makes it possible to obtain brushes with predetermined anisotropy.

ETAT DE LA TECHNIQUESTATE OF THE ART

L'anisotropie d'un balai est connue pour constituer un paramètre essentiel qui conditionne sa performance d'usage. Elle trouve sa source dans le fait que les balais sont généralement obtenus par compression de poudres dont certaines peuvent avoir des facteurs de forme très élevés (rapport "plus grande dimension / plus petite dimension"), par exemple du graphite en particules de faible épaisseur e (5-20 µm) et de grande longueur ou largeur (100-200 µm).
Il en résulte une certaine orientation des particules à facteur de forme significativement différent de un, et donc, in fine, une anisotropie des propriétés à la fois électriques et tribologiques, les particules à facteur de forme élevé s'orientant durant l'étape de compression de manière à ce que l'axe de compression soit en moyenne parallèle à la plus petite dimension e de ces particules (ou perpendiculaire au plan formé par les plus grandes dimensions).The anisotropy of a broom is known to constitute an essential parameter which conditions its performance of use. It finds its source in the fact that the brushes are generally obtained by compression of powders some of which can have very high form factors (ratio "largest dimension / small dimension"), for example graphite in particles of thin thickness e (5-20 µm) and very long or wide (100-200 µm).
This results in a certain orientation of the particles with form factor significantly different from one, and therefore, in fine, an anisotropy of both electrical and tribological properties, the particles with high form factor orienting themselves during the compression step. so that the compression axis is on average parallel to the most small dimension e of these particles (or perpendicular to the plane formed by the largest dimensions).

Généralement, mais cela n'est pas vrai dans tous les cas, le balai est orienté par rapport au collecteur de manière à ce que la direction de compression du balai soit la direction tangentielle "t" du collecteur du moteur. Ainsi, on obtient à la fois une usure minimum et une bonne commutation du balai. La direction tangentielle "t", comme les autres directions axiale "a" et radiale "r", sont relatives au collecteur - voir figure 8f.Generally, but this is not true in all cases, the brush is oriented relative to the manifold so that the compression direction of the brush is the tangential direction "t" of the motor manifold. Thus, both minimum wear and good commutation of the brush are obtained. The tangential direction "t", like the other axial directions "a" and radial "r", are relative to the collector - see figure 8f.

Dans sa demande de brevet français n° 93-10881, la demanderesse a déjà recherché des moyens pour obtenir des balais multicouches aptes à assurer plusieurs fonctions, notamment une commutation de qualité. Dans cette demande, on introduit dans le moule de compression, simultanément au moins deux poudres différentes.In its French patent application No. 93-10881, the applicant has already sought means for obtaining multilayer brushes capable of performing several functions, in particular quality switching. In this application, at least two different powders are introduced into the compression mold.

Par ailleurs, dans sa demande de brevet français n° 93-06962, la demanderesse a aussi recherché des moyens pour obtenir des balais directement aux cotes finales à l'issue de l'étape de compression des poudres conductrices. Le procédé décrit dans cette demande faisait appel à une sélection de poudres de graphite.Furthermore, in its French patent application No. 93-06962, the applicant also sought means for obtaining brushes directly at the final dimensions at the end of the step of compressing the conductive powders. The process described in this application used a selection of graphite powders.

Dans ces demandes de brevet, comme dans la plupart des documents relatifs à la fabrication de balais, et à titre d'exemple dans le brevet français n° 2.009.196, la compression des poudres conductrices est une compression uniaxiale de deux poudres introduites successivement dans une matrice formant moule de compression.In these patent applications, as in most of the documents relating to the manufacture of brushes, and by way of example in French Patent No. 2,009,196, the compression of the conductive powders is a uniaxial compression of two powders introduced successively into a matrix forming a compression mold.

PROBLEME POSEPROBLEM

La demanderesse a poursuivi ses recherches pour obtenir simultanément :

  • d'une part, des balais directement aux cotes finales à l'issue d'une seule étape de compression, mais sans être limité dans un choix des matières premières comme dans la demande française n° 93-06962.
    On entend par cotes finales les dimensions critiques du balai, celles selon les directions "a" et selon "t", c'est à dire les dimensions qui constituent la section du balai considéré comme un objet devant glisser dans son porte-balais à section fixe prédéterminée, par opposition à la direction "r" qui ne nécessite pas une aussi grande précision dimensionnelle.
  • d'autre part, des balais présentant l'anisotropie souhaitée, compte tenu de leur positionnement sur le collecteur, et compte tenu du type de moteurs et d'applications, sans avoir à faire appel à la technologie des balais multicouches, comme décrit dans la demande française n° 93-10881,
  • enfin, des balais dont la tête et pied ont une forme adaptée à l'usage choisi, sans usinage postérieur à la compression. On appelle "tête" l'extrémité du balai portant le conducteur de connexion électrique (une tresse de cuivre en général), et on appelle "pied" l'extrémité du balai en contact avec le collecteur.
The plaintiff continued its research to obtain simultaneously :
  • on the one hand, brushes directly to the final dimensions after a single compression step, but without being limited in a choice of raw materials as in French application n ° 93-06962.
    The term “final dimensions” is understood to mean the critical dimensions of the brush, those along the directions “a” and according to “t”, that is to say the dimensions which constitute the section of the brush considered as an object having to slide in its brush holder with section fixed predetermined, as opposed to the direction "r" which does not require such high dimensional accuracy.
  • on the other hand, brushes having the desired anisotropy, taking into account their positioning on the collector, and taking into account the type of motors and applications, without having to use the technology of multilayer brushes, as described in the French application n ° 93-10881,
  • finally, brushes whose head and foot have a shape adapted to the chosen use, without machining after compression. The end of the brush carrying the electrical connection conductor (a copper braid in general) is called "head", and the end of the brush in contact with the collector is called "foot".

Typiquement, il est préférable que le pied du balai ait au moins la courbure du collecteur, si ce n'est d'autres moyens complémentaires, pour faciliter le rodage du moteur. Par ailleurs, il est souvent nécessaire que la tête du balai soit munie d'un moyen, typiquement un téton, une encoche ou nervure, pour que le ressort appuyant sur la tête reste bien centré et ne risque pas de déraper latéralement - d'où un usinage de la tête dans les procédés de l'art antérieur.Typically, it is preferable that the foot of the brush has at least the curvature of the collector, if not other complementary means, to facilitate the running in of the motor. In addition, it is often necessary that the head of the broom is provided with a means, typically a nipple, a notch or rib, so that the spring pressing on the head remains well centered and does not risk slipping laterally - hence machining of the head in the processes of the prior art.

DESCRIPTION DE L'INVENTIONDESCRIPTION OF THE INVENTION

Selon un premier objet de l'invention, le dispositif de fabrication de balais comprend une matrice munie d'une cavité destinée à recevoir au moins une poudre conductrice à comprimer et au moins un poinçon de compression de ladite poudre, et est caractérisé en ce que ladite matrice est munie de deux gaines concourantes formant ladite cavité, et orientées à 90° l'une par rapport à l'autre, l'une étant orientée selon la verticale, et l'autre selon l'horizontale, et en ce que chacune de ces gaines est dotée de moyens de compression, comprenant au moins un poinçon de compression, de manière à obtenir une compression biaxiale de ladite poudre.According to a first object of the invention, the device for manufacturing brushes comprises a matrix provided with a cavity intended to receive at least one conductive powder to be compressed and at least one punch for compressing said powder, and is characterized in that said matrix is provided with two concurrent sheaths forming said cavity, and oriented at 90 ° relative to each other, one being oriented vertically, and the other horizontally, and in that each of these sheaths is provided with compression means, comprising at least one compression punch, so as to obtain a biaxial compression of said powder.

Les dispositifs utilisés industriellement selon l'art antérieur sont constitués typiquement par un gaine verticale dotée de deux poinçons, un poinçon bas formant avec la gaine verticale une cavité, cavité qui est ensuite chargée, par l'orifice supérieur libre, d'au moins une poudre conductrice. La compression uniaxiale entre poinçons conduit, comme déjà indiqué, à la formation d'un balai anisotrope, à structure dite "feuilletée", qui est mise à profit pour améliorer la commutation.
Avec ce dispositif, il est impossible d'obtenir, par compression, un balai cru doté, à sa tête et/ou à son pied, d'une configuration géométrique souhaitée (téton de centrage pour la tête, courbure pour le pied, etc...), et présentant en outre une orientation favorable de sa structure feuilletée. En effet, la compression, avec des poinçons permettant d'imprimer à ladite poudre conductrice la configuration géométrique souhaitée, implique une direction de compression parallèle à la direction "r" - et non à la direction "t" qu'il faut pour avoir une commutation améliorée.
En conséquence, dans l'art antérieur, ladite configuration géométrique de la tête et du pied était obtenue par une opération d'usinage complémentaire.
Comme cela va apparaître clairement dans ce qui suit, le dispositif de compression biaxiale selon l'invention, par contre, permet d'obtenir à la fois la structure feuilletée orientée favorablement et toute configuration géométrique quelconque souhaitée pour la tête et le pied du balai, une configuration typique du pied étant une courbure adaptée à celle du collecteur.The devices used industrially according to the prior art typically consist of a vertical sheath provided with two punches, a low punch forming with the vertical sheath a cavity, cavity which is then charged, by the free upper orifice, with at least one conductive powder. The uniaxial compression between punches leads, as already indicated, to the formation of an anisotropic brush, with a so-called "laminated" structure, which is used to improve the switching.
With this device, it is impossible to obtain, by compression, a raw broom with, at its head and / or at its foot, a desired geometrical configuration (centering pin for the head, curvature for the foot, etc. ..), and further having a favorable orientation of its laminated structure. Indeed, compression, with punches making it possible to print said conductive powder with the desired geometric configuration, implies a direction of compression parallel to the direction "r" - and not to the direction "t" which is necessary to have a improved switching.
Consequently, in the prior art, said geometric configuration of the head and of the foot was obtained by a complementary machining operation.
As will become clear in what follows, the biaxial compression device according to the invention, on the other hand, makes it possible to obtain both the laminated structure favorably oriented and any geometrical configuration whatsoever desired for the head and the foot of the broom, a typical configuration of the foot being a curvature adapted to that of the collector.

En effet, les nombreux essais de la demanderesse ont montré qu'il est possible d'obtenir, avec une compression biaxiale à l'aide du dispositif de l'invention, un balai à forte anisotropie et à structure feuilletée très marquée, à condition que :

  • a) d'une part, les moyens de compression soient mis en oeuvre séquentiellement (mise en oeuvre des moyens de compression selon une direction - d'abord, par convention, par une première compression selon la direction verticale, puis par une seconde compression selon l'autre direction - la direction horizontale),
  • b) et d'autre part, le taux Ti de première compression (appelé aussi taux de compression initial) selon une direction et le taux Tc de deuxième compression (appelé aussi taux de compression complémentaire) selon l'autre direction soient relativement différents (typiquement Ti/Tc > 2, ou Tc/Ti > 2).
Indeed, the numerous tests by the applicant have shown that it is possible to obtain, with biaxial compression using the device of the invention, a broom with strong anisotropy and with a very marked laminated structure, provided that :
  • a) on the one hand, the compression means are implemented sequentially (implementation of the compression means in a direction - first, by convention, by a first compression in the vertical direction, then by a second compression according to the other direction - the horizontal direction),
  • b) and on the other hand, the rate Ti of first compression (also called initial compression rate) in one direction and the rate Tc of second compression (also called complementary compression rate) in the other direction are relatively different (typically Ti / Tc> 2, or Tc / Ti> 2).

Dans ces conditions, la demanderesse a observé, dans le cas de Ti/Tc > 2, un phénomène particulièrement intéressant en pratique, à savoir que la structure feuilletée de la poudre comprimée obtenue après la première compression (verticale - par convention) n'est que peu perturbée par la seconde compression selon l'autre direction (horizontale), si ce n'est aux extrémités du balai, c'est à dire les seules parties en contact avec les poinçons de compression lors de la seconde compression, parties qui voient leur structure feuilletée totalement modifiée (réorientation locale des particules compte tenu de la direction de la seconde compression - à 90° par rapport à la première compression).Under these conditions, the applicant observed, in the case of Ti / Tc> 2, a particularly interesting phenomenon in practice, namely that the laminated structure of the compressed powder obtained after the first compression (vertical - by convention) is not only slightly disturbed by the second compression in the other direction (horizontal), if not at the ends of the brush, that is to say the only parts in contact with the compression punches during the second compression, parts which see their completely modified laminated structure (local reorientation of the particles taking into account the direction of the second compression - at 90 ° relative to the first compression).

Ainsi, moyennant ces deux conditions, une seconde compression ne détruit pas, pour l'essentiel, les effets d'orientation obtenus avec une première compression.
Quant'à l'altération de l'anisotropie aux extrémités du balai lors de la seconde compression, non seulement elle n'a pas d'effet néfaste, mais elle serait même plutôt avantageuse :

  • pour la tête, qui, comme cela sera indiqué ensuite, se densifie et se renforce,
  • et pour le pied, qui, du fait du changement d'orientation des particules plates, présente un coefficient de frottement légèrement plus faible favorable au rodage du couple balai-collecteur.

Par ailleurs, à l'issue de cette phase de rodage, et suite à l'usure du balai durant cette phase, la surface active du balai en contact avec le collecteur présente une structure feuilletée déjà très proche de celle, optimale pour la commutation, de la partie centrale du balai.Thus, with these two conditions, a second compression does not essentially destroy the orientation effects obtained with a first compression.
As for the alteration of the anisotropy at the ends of the broom during the second compression, not only does it have no harmful effect, but it would even be rather advantageous:
  • for the head, which, as will be indicated later, densifies and strengthens,
  • and for the foot, which, due to the change in orientation of the flat particles, has a slightly lower coefficient of friction favorable for running in the brush-collector couple.

Furthermore, at the end of this running-in phase, and following the wear of the brush during this phase, the active surface of the brush in contact with the collector has a laminated structure already very close to that, optimal for switching, of the central part of the broom.

Il va de soi que, selon les cas particuliers rencontrés, et par le jeu des compressions relatives selon l'une et l'autre direction, une anisotropie plus ou moins grande ou plus ou moins régulière peut être obtenue, en particulier si les deux conditions définies précédemment ne sont pas remplies.It goes without saying that, depending on the particular cases encountered, and by the play of relative compressions in either direction, a more or less large or more or less regular anisotropy can be obtained, in particular if the two conditions defined above are not met.

En résumé, le dispositif de compression biaxiale selon l'invention permet d'obtenir, directement par pressage de poudre conductrice, un balai cru, dont la tête et/ou le pied présente une configuration géométrique souhaitée, tout en conservant l'orientation souhaitée de sa structure feuilletée. Typiquement, la structure feuilletée souhaitée est obtenue lors de la première compression, tandis que, la configuration géométrique souhaitée est obtenue lors de la seconde compression.
De nombreuses autres possibilités du dispositif selon l'invention apparaîtront dans la suite de la description du dispositif, dans la description du procédé utilisant ledit dispositif, ainsi que dans les figures et leur description.In summary, the biaxial compression device according to the invention makes it possible to obtain, directly by pressing conductive powder, a raw broom, the head and / or the foot of which has a desired geometric configuration, while retaining the desired orientation of its laminated structure. Typically, the desired laminated structure is obtained during the first compression, while the desired geometric configuration is obtained during the second compression.
Many other possibilities of the device according to the invention will appear in the following description of the device, in the description of the process using said device, as well as in the figures and their description.

DESCRIPTION DES FIGURESDESCRIPTION OF THE FIGURES

La figure 1 représente une vue schématique, en perspective, d'un dispositif (1) de compression biaxiale selon l'invention. Ce dispositif (1) comprend une matrice (2) dans laquelle deux gaines concourantes, une gaine verticale (3) de section Sv (hachures obliques) et une gaine horizontale (4) de section Sh (hachures verticales) se croisent à 90° en formant une espace d'intersection commun (5) de forme parallélépipédique.
La gaine verticale est munie de deux poinçons : un poinçon haut (6), et un poinçon bas (6').
La gaine horizontale est munie de deux poinçons : un poinçon gauche (7), et un poinçon droit (7').
Sur ce schéma, comme sur les suivants, ne sont pas représentés les moyens connus en eux-mêmes pour actionner les différents poinçons (6, 6', 7 et 7').Figure 1 shows a schematic perspective view of a biaxial compression device (1) according to the invention. This device (1) comprises a matrix (2) in which two concurrent sheaths, a vertical sheath (3) of section Sv (oblique hatching) and a horizontal sheath (4) of section Sh (vertical hatching) intersect at 90 ° in forming a common intersection space (5) of parallelepiped shape.
The vertical sheath is provided with two punches: a high punch (6), and a low punch (6 ').
The horizontal sheath is provided with two punches: a left punch (7), and a right punch (7 ').
In this diagram, as in the following, the means known in themselves are not shown for actuating the various punches (6, 6 ', 7 and 7').

Les figures 2a à 2d illustrent, en différentes étapes, le fonctionnement du dispositif (1) et représentent une coupe dans le plan vertical selon l'axe A-B de la figure 1.FIGS. 2a to 2d illustrate, in different stages, the operation of the device (1) and represent a section in the vertical plane along the axis A-B of FIG. 1.

Sur la figure 2a, le poinçon haut (6) a été écarté, les autres poinçons étant positionnés pour former une cavité qui a été chargée en poudre conductrice à comprimer (9), et de volume Vo.
A noter que le poinçon gauche (7) présente un profil courbe.In FIG. 2a, the top punch (6) has been moved aside, the other punches being positioned to form a cavity which has been loaded with conductive powder to be compressed (9), and of volume Vo.
Note that the left punch (7) has a curved profile.

La figure 2b représente la première étape de compression, selon la direction verticale à l'aide des poinçons haut (6) et bas (6').Figure 2b shows the first compression step, in the vertical direction using the top (6) and bottom (6 ') punches.

Il importe de noter qu'à l'issue de cette première compression, qui a transformé un volume Vo de poudre conductrice (9) en un volume Vi de poudre comprimée (10), la poudre comprimée (10) occupe le seul espace de la gaine horizontale (4) et forme un bloc de section Sh.It is important to note that at the end of this first compression, which transformed a volume Vo of conductive powder (9) into a volume Vi of compressed powder (10), the compressed powder (10) occupies the only space of the horizontal sheath (4) and forms a block of section Sh.

On peut noter aussi la présence, sur le poinçon haut (6) d'un conducteur (12) dont l'extrémité, après compression verticale, pénètre dans la poudre comprimée (10).One can also note the presence, on the high punch (6) of a conductor (12) whose end, after vertical compression, penetrates into the compressed powder (10).

La figure 2c représente la seconde étape de compression, selon la direction horizontale à l'aide des poinçons gauche (7) et droit (7'), qui conduit à la mise en forme finale d'un balai cru (11) de volume Vf.FIG. 2c represents the second compression step, in the horizontal direction using the left (7) and right (7 ') punches, which leads to the final shaping of a raw broom (11) of volume Vf .

La figure 2d repésente l'étape suivante, au cours de la quelle les poinçons horizontaux (7) et (7') sont écartés, de manière à permettre la récupération du balai cru (11) - après remontée des poinçons verticaux (6) et (6') et écartement du poinçon haut (6), (non représenté sur la figure 2d).FIG. 2d shows the next step, during which the horizontal punches (7) and (7 ') are separated, so as to allow the recovery of the raw brush (11) - after the vertical punches (6) have been raised and (6 ') and spacing of the top punch (6), (not shown in Figure 2d).

La figure 3 représente une vue schématique, en perspective, d'une première variante (1a) de dispositif (1) selon l'invention. Dans ce dispositif (1a) à 3 poinçons, représenté en position "ouverte" - prêt à recevoir une charge de poudre conductrice - la gaine verticale (3) de section Sv et la gaine horizontale (4) de section Sh se croisent à 90° en formant un "T", au lieu de former une croix comme à la figure 1.FIG. 3 represents a schematic perspective view of a first variant (1a) of the device (1) according to the invention. In this device (1a) with 3 punches, shown in the "open" position - ready to receive a charge of conductive powder - the vertical sheath (3) of section Sv and the horizontal sheath (4) of section Sh intersect at 90 ° by forming a "T", instead of forming a cross as in Figure 1.

Les figures 4a et 4b sont des coupes dans le plan vertical selon l'axe A-B de la figure 4.FIGS. 4a and 4b are sections in the vertical plane along the axis A-B in FIG. 4.

Sur la figure 4a, analogue à la figure 2a, les poinçons horizontaux (7) et (7'), et le poinçon vertical bas (6') sont positionnés pour former une cavité qui a été chargée en poudre conductrice à comprimer (9), et de volume Vo.In Figure 4a, similar to Figure 2a, the horizontal punches (7) and (7 '), and the bottom vertical punch (6') are positioned to form a cavity which has been loaded with conductive powder to be compressed (9) , and of volume Vo.

La figure 4b, analogue à la figure 2b, représente la première étape de compression, selon la direction verticale à l'aide du poinçon bas (6'), après qu'une plaque (8) ait été placée sur le plan supérieur (20) de la matrice (2a) et maintenu dans cette position par des moyens non représentés.FIG. 4b, similar to FIG. 2b, shows the first stage of compression, in the vertical direction using the bottom punch (6 '), after a plate (8) has been placed on the upper plane (20 ) of the matrix (2a) and maintained in this position by means not shown.

Comme dans le cas de la figure 2b, on obtient, à la fin de la première compression verticale, un bloc de poudre comprimée (10) ayant la section Sh de la gaine horizontale (4). A noter que le conducteur (12) a été introduit dans la poudre à comprimer (9), en dotant la plaque (8) d'un orifice dans lequel passe une extrémité du conducteur (12).As in the case of FIG. 2b, one obtains, at the end of the first vertical compression, a block of compressed powder (10) having the section Sh of the horizontal sheath (4). Note that the conductor (12) has been introduced into the powder to be compressed (9), providing the plate (8) with an orifice through which one end of the conductor (12) passes.

La figure 4c représente une coupe du balai cru (11) final.Figure 4c shows a section of the final raw broom (11).

La figure 5a est une vue de dessus du dispositif de la figure 3 qui illustre le fait que la gaine horizontale (4) est formée par usinage de précision de manière à assurer une largeur 1 avec une grande précision (Δ1 inférieur à 0,02 mm, et de préférence inférieur à 0,01 mm).Figure 5a is a top view of the device of Figure 3 which illustrates the fact that the horizontal sheath (4) is formed by precision machining so as to ensure a width 1 with high precision (Δ1 less than 0.02 mm , and preferably less than 0.01 mm).

La figure 5b, qui complète la figure 5a, illustre une modalité préférée de l'invention dans laquelle :

  • a) le dispositif (1a) à 3 poinçons est utilisé, avec la plaque (8) calée et maintenue appliquée contre la surface supérieure (20) de la matrice (2a),
  • b) lors de la première compression, le poinçon vertical bas (6') arrête sa course quand il arrive exactement au niveau de la gaine horizontale (4) - ce qui a été représenté, à titre symbolique, par une butée (21), de sorte que ce dispositif garantit pour le balai cru (11) une hauteur h précise et reproductible (Δh inférieur à 0,02 mm, et de préférence inférieur à 0,01 mm).
  • c) par contre, la seconde compression est contrôlée par la pression (arrêt des poinçons pour une pression égale à une pression donnée). Dans ces conditions, la précision sur la longueur (ΔL/L) est bonne mais inférieure à la précision sur la section (lxh) du balai cru (11).

Cette précision sur L est néanmoins suffisante dans la pratique compte tenu du fait que cette dimension est aussi la longueur du balai, les exigences dimensionnelles étant bien moindres sur la longueur du balai que sur sa section.FIG. 5b, which supplements FIG. 5a, illustrates a preferred method of the invention in which:
  • a) the device (1a) with 3 punches is used, with the plate (8) wedged and kept applied against the upper surface (20) of the matrix (2a),
  • b) during the first compression, the bottom vertical punch (6 ') stops its course when it arrives exactly at the level of the horizontal sheath (4) - which has been represented, symbolically, by a stop (21), so that this device guarantees for the raw brush (11) a precise and reproducible height h (Δh less than 0.02 mm, and preferably less than 0.01 mm).
  • c) on the other hand, the second compression is controlled by the pressure (stop of the punches for a pressure equal to a given pressure). Under these conditions, the precision over the length (ΔL / L) is good but less than the precision over the section (wxh) of the raw brush (11).

This precision on L is nevertheless sufficient in practice given that this dimension is also the length of the brush, the dimensional requirements being much less on the length of the brush than on its section.

La figure 6, analogue aux figures 1 et 3 représente une seconde modalité (1b) de dispositif (1).
Dans ce dispositif (1b) à deux poinçons, la gaine verticale (3) et la gaine horizontale (4) ont la forme d'un "L".
En vue de former une rainure sur le balai cru, le poinçon vertical bas (6') a été doté localement d'un surépaisseur transversale (16).Figure 6, similar to Figures 1 and 3 shows a second modality (1b) of the device (1).
In this device (1b) with two punches, the vertical sheath (3) and the horizontal sheath (4) have the shape of an "L".
In order to form a groove on the raw broom, the bottom vertical punch (6 ') has been provided locally with a transverse allowance (16).

Les figures 7a à 7c, analogues aux figures 4a à 4c, sont des coupes dans un plan vertical selon l'axe A-B de la figure 6.Figures 7a to 7c, similar to Figures 4a to 4c, are sections in a vertical plane along the axis A-B of Figure 6.

Sur la figure 7a, analogue à la figure 4a, le poinçon horizontal (7') qui comprend une partie creuse (14), et le poinçon vertical bas (6') sont positionnés pour former une cavité qui a été chargée en poudre conductrice à comprimer (9), et de volume utile Vo.
A la fois le poinçon vertical bas (6') et la plaque supérieure (8) sont dotées d'une surépaisseur transversale (16).
La figure 7b représente le dispositif (1b) à la fin de la première compression verticale.
La figure 7c représente le balai cru (11) obtenu avec deux rainures latérales (16a) et un téton (14a).In Figure 7a, similar to Figure 4a, the horizontal punch (7 ') which includes a hollow portion (14), and the bottom vertical punch (6') are positioned to form a cavity which has been loaded with conductive powder to compress (9), and of useful volume Vo.
Both the bottom vertical punch (6 ') and the top plate (8) are provided with a transverse allowance (16).
Figure 7b shows the device (1b) at the end of the first vertical compression.
FIG. 7c represents the raw brush (11) obtained with two lateral grooves (16a) and a stud (14a).

Les figures 8a à 8f représentent des variantes de balais crus (11), en coupe selon le plan "r-t", obtenus selon l'invention. Ces variantes, explicites en elles-mêmes sont relatives à la configuration géométrique (Fig 8a, 8b, 8c et 8d).Figures 8a to 8f show variants of raw brushes (11), in section along the plane "r-t", obtained according to the invention. These variants, self-explanatory in themselves, relate to the geometrical configuration (Fig 8a, 8b, 8c and 8d).

Sur tous ces balais, les hachures horizontales représentent la structure feuilletée. La structure des extrémités n'a pas été représentée explicitement, sauf à la figure 8e (extrémité du pied (18) en hachures croisées "larges" - extrémité de la tête (19) en hachures croisées "serrées") où les extrémités (18) et (19) ont une structure feuilletée plutôt orientée selon la seconde compression.
Il va de soi que, dans la réalité, le changement de structure feuilletée entre les extrémités et la partie centrale du balai n'est pas aussi brusque que ce qui est représenté à la figure 8e.
La figure 8f représente les directions "a", "r" et "t" relatives au collecteur (22).On all these brooms, the horizontal hatching represents the laminated structure. The structure of the ends has not been shown explicitly, except in FIG. 8e (end of the foot (18) in "wide" cross hatching - end of the head (19) in "tight" cross hatching) where the ends (18 ) and (19) have a laminated structure rather oriented according to the second compression.
It goes without saying that, in reality, the change in structure laminated between the ends and the central part of the broom is not as abrupt as that which is represented in FIG. 8e.
FIG. 8f represents the directions "a", "r" and "t" relative to the collector (22).

Les figures 9 et 10a à 10c sont relatives aux balais de l'exemple 1.
La figure 9 représentes différentes vues des balais de l'exemple 1:

  • en (a), est représentée une vue en coupe dans le plan "r-t",
  • en (b), est représentée une vue de dessus, dans le plan "a-r",
  • en (c), est représenté une vue de la surface de contact (13) formant le pied (18), dotée de stries (23) obliques.
  • en (d), est représenté le relief de la surface (13), selon l'axe A-B de la figure (c).
Figures 9 and 10a to 10c relate to the brushes of Example 1.
FIG. 9 shows different views of the brushes of Example 1:
  • in (a), a sectional view is shown in the "rt" plane,
  • in (b), a top view is shown, in the plane "ar",
  • in (c) is shown a view of the contact surface (13) forming the foot (18), provided with oblique grooves (23).
  • in (d), the relief of the surface (13) is represented, along the axis AB of FIG. (c).

La figure 10a représente d'une part un dispositif de compression biaxiale (1a) selon l'invention utilisé en compression monoaxiale (poinçons horizontaux 7 et 7') à l'état initial, pour obtenir un balai cru selon l'art antérieur, la charge de poudre (9) de volume Vo n'ayant pas encore commencée à être comprimée, le poinçon vertical (6') étant maintenu relevé durant toute la compression, et d'autre part elle représente, en coupe selon le plan "r-t", le balai cru obtenu sur lequel on a schématisé par des traits l'orientation des particules après compression.
Les figures 10b et 10c, analogues à la figure 10a, correspondent respectivement aux essais lb et lc. Les deux balais bruts obtenus ont un "coeur" constitué de particules orientées favorablement selon le plan "a-r" (orientation obtenue lors de la première compression verticale avec le poinçon 6'), et deux extrémités à forme géométrique souhaitée, à la tête (19) et au pied (18), constituées par une couche d'épaisseur E où les particules sont orientées dans le plan "a-t" (forme géométrique obtenue lors de la seconde compression horizontale, avec les poinçons 7 et 7').FIG. 10a represents on the one hand a biaxial compression device (1a) according to the invention used in monoaxial compression (horizontal punches 7 and 7 ′) in the initial state, to obtain a raw brush according to the prior art, the powder charge (9) of volume Vo which has not yet started to be compressed, the vertical punch (6 ') being kept raised during all of the compression, and on the other hand it represents, in section along the plane "rt" , the raw broom obtained on which the orientation of the particles after compression has been shown diagrammatically.
Figures 10b and 10c, similar to Figure 10a, correspond to tests lb and lc respectively. The two rough brushes obtained have a "core" made up of particles oriented favorably along the plane "ar" (orientation obtained during the first vertical compression with the punch 6 '), and two ends with the desired geometric shape, at the head (19 ) and at the foot (18), constituted by a layer of thickness E where the particles are oriented in the plane "a-t" (geometric shape obtained during the second horizontal compression, with the punches 7 and 7 ').

Les figures 11a et 11b sont relatives aux balais de l'exemple 2. Elles représentent des coupes de balais selon le plan "r-t", la figure 11a étant relative à un balai selon l'art antérieur à anisotropie homogène, et la figure 11b à un balai selon l'invention.
Dans ce balai selon l'invention, le "coeur" du balai est formé de particules contenues dans le plan "a-t", alors que, sur une épaisseur E de deux faces opposées du balai, les particules sont orientées selon le plan "r-a".FIGS. 11a and 11b relate to the brushes of Example 2. They represent sections of brushes according to the "rt" plane, FIG. 11a being relative to a brush according to the prior art with homogeneous anisotropy, and FIG. 11b to a broom according to the invention.
In this brush according to the invention, the "heart" of the brush is formed of particles contained in the plane "a-t", while, on a thickness E of two opposite faces of the brush, the particles are oriented according to the plane " ra ".

La figure 12 représente, en coupe selon le plan "r-t", un balai de l'exemple 3 selon l'invention, la charge de poudre initiale (9) étant différente pour la tête (19) (représentée par des croix) et pour le reste du balai.FIG. 12 represents, in section along the plane "rt", a brush of example 3 according to the invention, the initial powder charge (9) being different for the head (19) (represented by crosses) and for the rest of the broom.

Les figures 13a à 13c et 14a à 14b représentent des dispositifs destinés à former des balais à section trapézoïdale.
Dans le cas des figures 13a à 13c, les poinçons horizontaux (7,7') sont de section trapézoïdale, les côtés parallèles de cette section trapézoïdale étant situés dans le plan horizontal. La compression dans le sens vertical est assurée par le poinçon vertical bas (6'), à section rectangulaire, et la plaque supérieure (8).
La figure 13a est une vue schématique, en perspective, analogue aux figures 1, 3 et 6, d'un dispositif (1c) comprenant une matrice (2c) dont la gaine horizontale (4) est de section trapézoïdale.
La figure 13b représente le volume dit commun (5) qui a la forme d'un prisme droit à base trapézoïdale.
La figure 13c est une coupe du dispositif (1c) de la figure 13a, selon un plan vertical passant par A-B.
La figure 14a est analogue à la figure 13a, sauf en ce que la gaine horizontale (4) présente une section trapézoïdale dont les côtés parallèles sont dans le plan vertical. En conséquence, le poinçon vertical bas (6') et la plaque supérieure (8) sont dotées de parties inclinées destinées à coopérer avec les côtés concourants de ladite section trapézoïdale, comme cela est représenté sur la figure 14b, qui est une coupe du dispositif (1d) de la figure 14a, selon un plan vertical et selon la direction A-B de la figure 14a.Figures 13a to 13c and 14a to 14b show devices intended to form brushes with trapezoidal section.
In the case of FIGS. 13a to 13c, the horizontal punches (7,7 ') are of trapezoidal section, the parallel sides of this trapezoidal section being located in the horizontal plane. Compression in the vertical direction is ensured by the bottom vertical punch (6 '), with rectangular section, and the upper plate (8).
Figure 13a is a schematic perspective view, similar to Figures 1, 3 and 6, of a device (1c) comprising a matrix (2c) whose horizontal sheath (4) is of trapezoidal section.
FIG. 13b represents the so-called common volume (5) which has the shape of a right prism with a trapezoidal base.
Figure 13c is a section of the device (1c) of Figure 13a, along a vertical plane passing through AB.
Figure 14a is similar to Figure 13a, except that the horizontal sheath (4) has a trapezoidal section whose parallel sides are in the vertical plane. Consequently, the bottom vertical punch (6 ') and the plate upper (8) are provided with inclined parts intended to cooperate with the concurrent sides of said trapezoidal section, as shown in FIG. 14b, which is a section of the device (1d) of FIG. 14a, along a vertical plane and along the direction AB of FIG. 14a.

DESCRIPTION DETAILLEE DE L'INVENTIONDETAILED DESCRIPTION OF THE INVENTION

Selon l'invention, lesdites gaines verticale (3) et horizontale (4) ont, de préférence, des sections respectives Sv et Sh rectangulaires, carrées, ou trapézoïdales, qui se raccordent en un volume commun (5) résultant, de préférence, de la projection orthogonale des sections Sv et Sh - voir figures 1, 3, 6, 14a - la figure 13a illustrant le cas où le volume commun (5) n'est pas, stricto sensu, le résultat de la projection orthogonale des sections Sv et Sh dans la mesure où la gaine verticale (3) présente une section constante Sv dans la partie inférieure de la matrice (2c) servant au guidage du poinçon (6'), section qui s'élargit ensuite au niveau dudit volume commun (5).
Le volume commun (5) est un parallélépipède rectangle lorsque les sections Sv et Sh sont rectangulaires ou carrées (figure 1). Ce volume (5) est un prisme droit à base trapézoïdale quand une des sections Sv ou Sh est un trapèze (figure 13b).According to the invention, said vertical (3) and horizontal (4) sheaths preferably have respective rectangular, square, or trapezoidal sections S v and S h , which are connected in a common volume (5) preferably resulting , of the orthogonal projection of sections S v and S h - see Figures 1, 3, 6, 14a - Figure 13a illustrating the case where the common volume (5) is not, strictly speaking, the result of the orthogonal projection S v and S h sections insofar as the vertical sheath (3) has a constant section S v in the lower part of the die (2c) used to guide the punch (6 '), section which then widens at level of said common volume (5).
The common volume (5) is a rectangular parallelepiped when the sections S v and S h are rectangular or square (Figure 1). This volume (5) is a right prism with a trapezoidal base when one of the sections S v or S h is a trapezoid (Figure 13b).

Cependant, dans le cas par exemple d'une fabrication de balai comprenant une encoche (15), comme représenté sur le balai de la figure 8c, on peut utiliser un dispositif de fabrication muni d'un poinçon horizontal droit (7') ayant seulement la section de l'encoche (15) à obtenir.However, in the case for example of a manufacture of a broom comprising a notch (15), as shown on the broom of FIG. 8c, one can use a manufacturing device provided with a straight horizontal punch (7 ') having only the section of the notch (15) to be obtained.

Selon une première modalité préférée de l'invention relative à la compression verticale, illustrée aux figures 3, 4a à 4c, 5a et 5b, 6, 7a à 7c, le moyen de compression selon la direction verticale est formé par ladite gaine verticale (3) munie à sa partie inférieure d'un poinçon de compression (6') et à sa partie supérieure d'une plaque amovible (8) de surface supérieure à la section Sv de la gaine verticale.
Cette plaque (8) est déplacée lors de la phase de chargement de la cavité avec ladite poudre à comprimer (9) occupant un volume utile Vo de la cavité en forme de "T", puis, après chargement de ladite poudre, elle est placée sur la surface supérieure (20) de la matrice et maintenue plaquée contre elle à l'aide de moyens connus en eux-mêmes et non représentés (typiquement un ou plusieurs vérins hydrauliques exerçant une pression supérieure à celle exercée par le poinçon vertical bas (6')).According to a first preferred embodiment of the invention relating to vertical compression, illustrated in FIGS. 3, 4a to 4c, 5a and 5b, 6, 7a to 7c, the means of compression in the vertical direction is formed by said vertical sheath (3 ) provided at its lower part with a compression punch (6 ') and at its upper part of a removable plate (8) with a surface greater than the section S v of the vertical sheath.
This plate (8) is moved during the loading phase of the cavity with said powder to be compressed (9) occupying a useful volume Vo of the "T" shaped cavity, then, after loading of said powder, it is placed on the upper surface (20) of the matrix and kept pressed against it using means known in themselves and not shown (typically one or more hydraulic cylinders exerting a pressure greater than that exerted by the bottom vertical punch (6 ')).

Selon une deuxième modalité de l'invention relative à la compression verticale, illustrée aux figures 1, 2a à 2d, le moyen de compression selon la direction verticale est formé par ladite gaine verticale (3) munie à sa partie inférieure d'un poinçon de compression (6') et à sa partie supérieure d'un autre poinçon de compression (6), de manière à pouvoir effectuer selon l'axe vertical une compression à double effet.According to a second embodiment of the invention relating to vertical compression, illustrated in FIGS. 1, 2a to 2d, the compression means in the vertical direction is formed by said vertical sheath (3) provided at its lower part with a punch compression (6 ') and at its upper part of another compression punch (6), so as to be able to perform along the vertical axis a double effect compression.

En ce qui concerne la compression selon l'axe horizontal, l'invention prévoit aussi deux modalités.
Selon une première modalité relative à la compression horizontale, comme représenté aux figures 1, 2a à 2d, 3, 4a à 4b, 5a et 5b, ladite gaine horizontale (4) est munie de deux poinçons de compression, un poinçon gauche (7), et un poinçon droit (7'), de manière à pouvoir effectuer selon l'axe horizontal une compression à double effet.
Comme on l'a déjà indiqué, une telle compression à double effet est très utile pour donner à la tête et au pied du balai une configuration géométrique particulière, par exemple celle des balais des figures 8c et 8d.With regard to compression along the horizontal axis, the invention also provides two methods.
According to a first modality relating to horizontal compression, as shown in FIGS. 1, 2a to 2d, 3, 4a to 4b, 5a and 5b, said horizontal sheath (4) is provided with two compression punches, a left punch (7) , and a straight punch (7 '), so that double-effect compression can be effected along the horizontal axis.
As already indicated, such double-effect compression is very useful for giving the head and foot of the broom a particular geometric configuration, for example that of the brooms in FIGS. 8c and 8d.

Selon une seconde modalité relative à la compression horizontale, comme représenté aux figures 6, 7a à 7b, ladite gaine horizontale (4) est, à une extrémité, munie d'un seul poinçon (7'), l'autre extrémité étant formée par une portion d'une des parois de la gaine verticale (3).
Sur ces figures, la cavité de volume utile Vo contenant la poudre à comprimer (9) a la forme d'un "L" et le dispositif réprésenté aux figures 6, 7a à 7b comprend deux poinçons seulement.
Selon l'invention, on pourrait aussi remplacer la plaque supérieure (8) par un poinçon (6), et obtenir ainsi une cavité de volume utile Vo contenant la poudre à comprimer (9) en forme de "T" renversé.According to a second modality relating to horizontal compression, as shown in FIGS. 6, 7a to 7b, said horizontal sheath (4) is, at one end, provided with a single punch (7 '), the other end being formed by a portion of one of the walls of the vertical sheath (3).
In these figures, the useful volume cavity Vo containing the powder to be compressed (9) has the shape of an "L" and the device shown in Figures 6, 7a to 7b comprises only two punches.
According to the invention, one could also replace the upper plate (8) with a punch (6), and thus obtain a useful volume cavity Vo containing the powder to be compressed (9) in the shape of an inverted "T".

Il est avantageux selon l'invention que ladite plaque supérieure amovible (8) ne serve pas seulement à fermer la partie supérieure de la gaine verticale (3), mais forme aussi en même temps la paroi supérieure de ladite gaine horizontale (4).
L'intérêt de cette modalité apparaît ainsi très clairement, puisqu'il suffit d'un simple usinage pour former une gaine horizontale (4) ouverte à sa partie supérieure, et ayant des cotes précises - notamment une largeur 1 précise. Voir figures 3 et 5a.It is advantageous according to the invention that said removable upper plate (8) not only serves to close the upper part of the vertical sheath (3), but also forms at the same time the upper wall of said horizontal sheath (4).
The advantage of this modality thus appears very clearly, since it suffices for a simple machining to form a horizontal sheath (4) open at its upper part, and having precise dimensions - in particular a precise width 1. See Figures 3 and 5a.

La demanderesse a trouvé que les dispositifs selon l'invention devaient comprendre, avantageusement, un contrôle différencié des moyens de compression selon chaque direction :
lesdits moyens de compression d'une gaine (3 ou 4) sont mis en oeuvre sous contrôle de déplacement, tandis que lesdits moyens de compression de l'autre gaine (4 ou 3) sont mis en oeuvre sous contrôle de la pression exercée, les moyens de compression sous contrôle de déplacement ou sous contrôle de pression étant en eux-mêmes connus.
On a représenté symboliquement sur la figure 5b ces deux moyens de contrôle.The Applicant has found that the devices according to the invention should advantageously include a differentiated control of the compression means in each direction:
said means for compressing a sheath (3 or 4) are used under displacement control, while said means for compressing the other sheath (4 or 3) are used under control of the pressure exerted, the compression means under displacement control or under pressure control being known per se.
These two control means are represented symbolically in FIG. 5b.

De préférence, comme représenté à la figure 5b, lesdits moyens de compression de ladite gaine verticale (3) sont mis en oeuvre sous contrôle de déplacement, tandis que lesdits moyens de compression de ladite gaine horizontale (4) sont mis en oeuvre sous contrôle de la pression exercée.Preferably, as shown in FIG. 5b, said means for compressing said vertical sheath (3) are placed in works under displacement control, while said means for compressing said horizontal sheath (4) are implemented under control of the pressure exerted.

Il s'agit là d'un moyen préféré de l'invention qui permet d'atteindre simultanément tous les objectifs de l'invention :

  • * obtenir un balai aux cotes définitives, ayant en tout cas une section constante avec des dimensions prédéterminées,
  • * obtenir une balai comprimé selon la direction "t",
  • * obtenir un balai dont la tête et le pied ont une configuration géométrique souhaitée.
This is a preferred means of the invention which allows all the objectives of the invention to be achieved simultaneously:
  • * obtain a broom with final dimensions, having in any case a constant section with predetermined dimensions,
  • * obtain a compressed broom in the direction "t",
  • * obtain a broom whose head and foot have a desired geometric configuration.

En effet, la compression sous contrôle de déplacement fige la section du balai et crée l'anisotropie souhaitée, tandis que la compression sous contrôle de pression forme d'une part la configuration géométrique de la tête et du pied du balai, mais aussi constitue le complément de pression nécessaire à la cohésion et à la tenue mécanique du balai.Indeed, compression under displacement control freezes the section of the brush and creates the desired anisotropy, while compression under pressure control forms on the one hand the geometric configuration of the head and foot of the brush, but also constitutes the additional pressure necessary for the cohesion and mechanical strength of the brush.

Un deuxième objet de l'invention concerne un procédé de fabrication de balais à l'aide d'un dispositif (1, 1a, 1b, 1c, 1d) décrit précédemment et comprenant une matrice à deux gaines, l'une verticale (3) et l'autre horizontale (4), munies chacune d'au moins un poinçon (respectivement 6' et 7') formant une cavité de compression de volume utile Vo, dans lequel, de manière à former un balai cru (11) à dimensions prédéterminées et à anisotropie orientée favorablement,

  • a) les moyens de compressions étant en position écartée, on introduit dans ladite cavité une charge (9), de volume Vo, d'au moins une poudre conductrice,
  • b) on réalise une première compression, sous contrôle de déplacement, à l'aide des moyens de compression d'une des deux gaines (3 ou 4), de manière à obtenir une cavité intermédiaire tubulaire, de volume Vi, ayant la section de l'autre gaine (respectivement (4) ou (3)), et à conserver constante cette section durant toute l'étape c) de seconde compression du balai, de manière à obtenir un balai cru à section bien calibrée après l'étape c),
  • c) on réalise une seconde compression, sous contrôle de pression, à l'aide des moyens de compression de l'autre gaine (respectivement (4) ou (3)), de manière à obtenir un balai cru (11) de volume final Vf avec le taux de compression final souhaité,
  • d) on écarte les moyens de compression de chacune des gaines, d'abord ceux sous contrôle de pression, puis ceux sous contrôle de déplacement, et on éjecte le balai cru (11).
A second object of the invention relates to a method of manufacturing brushes using a device (1, 1a, 1b, 1c, 1d) described above and comprising a matrix with two sheaths, one vertical (3) and the other horizontal (4), each provided with at least one punch (respectively 6 'and 7') forming a compression cavity of useful volume Vo, in which, so as to form a raw brush (11) with dimensions predetermined and favorably oriented anisotropy,
  • a) the compression means being in the separated position, a charge (9), of volume Vo, of at least one conductive powder is introduced into said cavity,
  • b) a first compression is carried out, under displacement control, using the compression means of one of the two sheaths (3 or 4), so as to obtain a tubular intermediate cavity, of volume V i , having the section of the other sheath (respectively (4) or (3)), and to keep this section constant throughout the step c) of second compression of the broom, so as to obtain a raw broom with a well calibrated section after step c),
  • c) a second compression is carried out, under pressure control, using the compression means of the other sheath (respectively (4) or (3)), so as to obtain a raw brush (11) of final volume V f with the desired final compression ratio,
  • d) the compression means of each of the sheaths are removed, first those under pressure control, then those under displacement control, and the raw brush (11) is ejected.

De préférence, on met en oeuvre, sous contrôle de déplacement, les moyens de compression de la gaine verticale (3), et sous contrôle de pression, les moyens de compression de la gaine horizontale (4).
Il s'agit là d'une simple préférence d'ordre pratique, et on peut concevoir selon l'invention un procédé inversant le rôle de chaque gaine.
Par "contrôle de déplacement", on entend que, après mise en mouveemnt des moyens de compression de la gaine verticale, ceux-ci s'arrêtent dès que le (les) poinçon(s) a (ont) atteint une certaine cote z (alignement en particulier du poinçon 6' avec les bords de la gaine horizontale 4 - voir figure 5b).
Par "contrôle de pression", on entend que, après mise en mouvement des moyens de compression de la gaine horizontale, ceux-ci s'arrêtent dès qu'une certaine pression prédéterminée est atteinte.Preferably, the compression means of the vertical sheath (3) are used, under displacement control, and, under pressure control, the compression means of the horizontal sheath (4).
This is a simple practical preference, and one can conceive according to the invention a process reversing the role of each sheath.
By "displacement control" is meant that, after setting in motion of the means for compressing the vertical sheath, these stop as soon as the punch (s) has (have) reached a certain dimension z ( alignment in particular of the punch 6 'with the edges of the horizontal sheath 4 - see figure 5b).
By "pressure control" is meant that, after setting in motion of the means for compressing the horizontal sheath, they stop as soon as a certain predetermined pressure is reached.

Pour les raisons déjà indiquées, il est souhaitable de réaliser successivement les deux compressions, et de comprimer de manière différenciée la poudre conductrice pour chaque compression. Ainsi, le taux de compression Ti de la première compression (Ti = Vo/Vi), réalisée par la mise en oeuvre des moyens de compression sous contrôle de déplacement est, de préférence, compris entre 1,5 et 3,5. Par contre, le taux de compression Tc de la seconde compression (Tc = Vi/Vf) réalisé sous contrôle de pression est, de préférence, compris entre 1,1 et 2, le taux de compression total Tt (Tt= TixTc) étant généralement, de préférence, compris entre 2,5 et 4 selon la nature des poudres de départ.For the reasons already indicated, it is desirable to carry out the two compressions successively, and to compress the conductive powder in a differentiated manner for each compression. Thus, the compression ratio Ti of the first compression (T i = V o / V i ), carried out by the use of the compression means under displacement control is preferably between 1.5 and 3.5 . However, the rate of compression Tc of the second compression (T c = V i / V f ) carried out under pressure control is preferably between 1.1 and 2, the total compression ratio T t (T t = T i xT c ) generally being preferably between 2.5 and 4 depending on the nature of the starting powders.

Selon l'invention, on peut choisir l'anisotropie d'un balai en jouant sur la part relative de Ti et de Tc pour obtenir le taux de compression total Tt, l'anisotropie du balai étant d'autant plus élevée que le rapport 2.(Vo-Vi)/(Vo-Vf) s'écarte de 1. En pratique, il suffit que Ti/Tt soit proche de 1 ou que Tc/Tt soit supérieur à 0,5 pour obtenir l'anisotropie souhaitée.According to the invention, one can choose the anisotropy of a brush by playing on the relative share of T i and T c to obtain the total compression ratio T t , the anisotropy of the brush being all the higher as the ratio 2. (V o -V i ) / (V o -V f ) deviates from 1. In practice, it suffices that T i / T t is close to 1 or that T c / T t is greater than 0.5 to obtain the desired anisotropy.

Dans le cas le plus fréquent, on choisit Ti/Tt proche de 1 (typiquement compris entre 0,7 et 0,95), de manière à obtenir simultanément la structure feuilletée et la section adéquate du balai recherchées, la compression sous contrôle de pression (Tc/Tt compris entre 0,05 et 0,3) servant à obtenir la configuration géométrique souhaitée de la tête et du pied du balai.
Ainsi, avec le choix (par convention) d'une compression horizontale sous contrôle de pression, les moyens de compression de la gaine horizontale (4) sont donc généralement utilisés, comme illustré aux figures 8c et 8d, pour obtenir la forme souhaitée de la tête (téton (14a), trou (15)...) et/ou du pied du balai (courbure adaptée à celle du collecteur, face de contact striée).In the most frequent case, we choose T i / T t close to 1 (typically between 0.7 and 0.95), so as to simultaneously obtain the laminated structure and the appropriate section of the brush sought, the compression under control pressure (T c / T t between 0.05 and 0.3) used to obtain the desired geometric configuration of the head and foot of the brush.
Thus, with the choice (by convention) of horizontal compression under pressure control, the means of compression of the horizontal sheath (4) are therefore generally used, as illustrated in FIGS. 8c and 8d, to obtain the desired shape of the head (stud (14a), hole (15) ...) and / or foot of the brush (curvature adapted to that of the collector, striated contact face).

On peut aussi utiliser les moyens de compression de la gaine verticale (3) pour munir les parois latérales du balai cru de rainures / nervures (16a), comme représenté aux figures 6, 7a et 7b où l'on voit que la plaque supérieure (8), tout comme le poinçon vertical bas (6') présentent localement une surépaisseur (16) - mais un creux au lieu d'un relief serait également possible - transversale, de manière à obtenir un balai cru (8b) ayant des rainures latérales (16a).One can also use the means of compression of the vertical sheath (3) to provide the side walls of the raw brush with grooves / ribs (16a), as shown in FIGS. 6, 7a and 7b where it can be seen that the upper plate ( 8), just like the bottom vertical punch (6 ') locally has an extra thickness (16) - but a hollow instead of a relief would also be possible - transverse, so as to obtain a raw broom (8b) having lateral grooves (16a).

Comme cela est connu, il est avantageux d'assembler le conducteur (12) à la poudre conductrice durant la première compression.
Ainsi, tout moyen de compression selon l'invention, mais, de préférence, le moyen de compression mis en oeuvre sous contrôle de déplacement, peut être utilisé pour incorporer le conducteur de connexion électrique, ou d'ailleurs tout autre objet devant être au moins en partie noyé dans la poudre à comprimer.
L'invention permet en outre d'obtenir des balais à densité locale différentielle. Il est particulièrement avantageux d'avoir des balais dont la tête présente une densitée "élevée", car cela est favorable à la solidité de l'assemblage dudit conducteur et du bloc de poudre comprimée, et des balais dont le pied peut présenter une densité "faible" de manière à faciliter et accélérer la phase de rodage du moteur.
Par densité "élevée" ou "faible", on entend non pas une valeur absolue de densité, mais un écart par rapport à la densité moyenne dm du balai. Une densité "élevée" correspond typiquement à une densité comprise entre 1,05.dm et 1,08.dm. Par contre, une densité "faible" correspond typiquement à une densité comprise entre 0,85.dm et 0,95.dm.As is known, it is advantageous to assemble the conductor (12) with the conductive powder during the first compression.
Thus, any compression means according to the invention, but preferably the compression means used under displacement control, can be used to incorporate the electrical connection conductor, or for that matter any other object which must be at least partly embedded in the powder to be compressed.
The invention also makes it possible to obtain brushes with differential local density. It is particularly advantageous to have brushes whose head has a "high" density, because this is favorable to the solidity of the assembly of said conductor and the block of compressed powder, and brushes whose foot can have a density " low "so as to facilitate and accelerate the running-in phase of the engine.
By "high" or "low" density is meant not an absolute density value, but a deviation from the average density d m of the brush. A "high" density typically corresponds to a density between 1.05.d m and 1.08.d m . On the other hand, a "low" density typically corresponds to a density between 0.85.d m and 0.95.d m .

Un tel balai peut être obtenu avec un procédé utilisant le dispositif (1b) de la figure 6 dans lequel ladite gaine horizontale (4) est, à une extrémité, munie d'un seul poinçon (7'), l'autre extrémité étant formée par une portion d'une des parois de la gaine verticale (3).Such a brush can be obtained with a method using the device (1b) of FIG. 6 in which said horizontal sheath (4) is, at one end, provided with a single punch (7 '), the other end being formed by a portion of one of the walls of the vertical sheath (3).

Dans ce procédé, lors de la compression sous contrôle de déplacement de ladite charge (9) d'au moins une poudre conductrice de volume Vo, ledit taux moyen de compression initiale Ti est choisi au moins égal à 2, et inférieur à 0,9 Tt.In this method, during compression under displacement control of said charge (9) of at least one conductive powder of volume Vo, said initial initial compression ratio T i is chosen at least equal to 2, and less than 0, 9 T t .

Ainsi, la demanderesse a observé qu'avec un taux relativement élevé de première compression sous contrôle de déplacement, la deuxième compression, qui, comme déjà signalé, permet la configuration géométrique de la tête et du pied du balai, permet aussi, grâce à une compression par un seul poinçon (7') du bloc de poudre comprimé (10), d'obtenir un balai cru (11) plus dense du côté du poinçon de seconde compression que du côté opposé, tel que schématisé à la figure 8e (hachures plus serrées à l'extrémité "tête" (19) qu'à l'autre extrémité "pied" (18)).
La demanderesse a interprété ces résultats en supposant que, bien que le bloc de poudre comprimé contienne généralement des poudres de graphite à faible coefficient de frottement, au-delà d'un certain taux de compression initiale Ti, la compression complémentaire Tc agit "localement" et ne se répercute donc pas de manière homogène sur l'ensemble dudit bloc de poudre comprimé (10).Thus, the Applicant has observed that with a relatively high rate of first compression under displacement control, the second compression, which, as already mentioned, allows the geometric configuration of the head and the foot of the broom, also allows, thanks to a compression with a single punch (7 ') of the compressed powder block (10), to obtain a raw brush (11) more dense on the side of the second compression punch than on the opposite side, as shown diagrammatically in FIG. 8e (hatching tighter at the "head" end (19) than at the other "foot" end (18)).
The Applicant interpreted these results by supposing that, although the block of compressed powder generally contains powders of graphite with low coefficient of friction, beyond a certain rate of initial compression Ti, the complementary compression Tc acts "locally" and therefore does not have a uniform effect on the whole of said block of compressed powder (10).

Un troisième objet selon l'invention est constitué par les balais fabriqués à l'aide des dispositifs et procédés selon l'invention.
Les balais obtenus à l'aide des dispositifs et selon les procédés de l'invention se caractérisent par l'hétérogénéité de leur anisotropie, entre le "coeur" du balai et deux des 6 faces du balai (sur une épaisseur E, de l'ordre de quelques millimètres au plus) : l'orientation des particules du "coeur" du balai est à 90° de l'orientation des particules de deux des 6 faces du balai.
Typiquement, les particules du "coeur" sont orientées dans le plan "a-r", et les particules de la tête (19) et du pied (18) sont orientées dans le plan "a-t". Voir figures 10b et 10c par exemple.
Mais on peut aussi avoir le cas inverse, avec un "coeur" ayant des particules orientées selon le plan "a-t" et avec deux faces du balai ayant, sur une épaisseur E, des particules orientées selon le plan "a-r" (ou "t-r"), comme illustré à la figure 11b.A third object according to the invention consists of the brushes produced using the devices and methods according to the invention.
The brushes obtained using the devices and according to the methods of the invention are characterized by the heterogeneity of their anisotropy, between the "heart" of the brush and two of the 6 faces of the brush (on a thickness E, of the order of a few millimeters at most): the orientation of the particles in the "core" of the broom is 90 ° from the orientation of the particles in two of the 6 faces of the broom.
Typically, the particles of the "heart" are oriented in the "ar" plane, and the particles of the head (19) and the foot (18) are oriented in the "a-t" plane. See Figures 10b and 10c for example.
But we can also have the opposite case, with a "core" having particles oriented along the plane "a-t" and with two faces of the brush having, over a thickness E, particles oriented along the plane "ar" (or "tr"), as shown in Figure 11b.

Le plus souvent, la tête (19) et le pied (18) sont dotés de moyens géométriques (courbure, tétons, trous, etc...) adaptés à l'usage de ces balais, et obtenus, selon l'invention, directement au cours de l'étape de compression biaxiale.Most often, the head (19) and the foot (18) are provided with geometric means (curvature, nipples, holes, etc.) adapted to the use of these brushes, and obtained, according to the invention, directly during the biaxial compression stage.

EXEMPLESEXAMPLES

Tous ces exemples ne décrivent que la formation de balais crus (11), les autres étapes de fabrication de balais, notamment la cuisson des balais crus étant connue en elle-même et non spécifique à l'invention.All these examples only describe the formation of raw brushes (11), the other stages in the manufacture of brushes, in particular the cooking of raw brushes being known in itself and not specific to the invention.

Exemple 1Example 1

On a fabriqué des balais pour moteurs électriques auxiliaires de voitures - typiquement pour moteur de lève-vitres à l'aide du dispositif de compression biaxiale selon l'invention (la) représenté aux figures 3, 4a à 4c, à partir de poudres usuelles comprenant des particules de graphite en forme de flocons, particules de grande dimensions (de 30 à 300 µm), mais de faible épaisseur (inférieure à 20 µm).
Ces balais ont pour dimensions : 5mm x 5 mm x 11 mm
La figure 9 représente différentes vues de ces balais.
Le pied (18) de ces balais présente une courbure et la surface de contact incurvée (13) présente des stries obliques (23).
La tête (19) de ces balais présente un trou (15) destiné au centrage du ressort du balai (non représenté).
Ce pied (18) et cette tête (19) sont obtenus grâce à la forme géométrique correspondante des poinçons horizontaux gauche (7) et droit (7') du dispositif de compression biaxiale (1a).Brushes for auxiliary electric motors of cars have been manufactured - typically for window regulator motor using the biaxial compression device according to the invention (la) shown in FIGS. 3, 4a to 4c, from conventional powders comprising particles of graphite in the form of flakes, particles of large dimensions (from 30 to 300 μm), but of small thickness (less than 20 μm).
These brushes have the following dimensions: 5mm x 5 mm x 11 mm
Figure 9 shows different views of these brushes.
The foot (18) of these brushes has a curvature and the curved contact surface (13) has oblique grooves (23).
The head (19) of these brushes has a hole (15) intended for centering the spring of the brush (not shown).
This foot (18) and this head (19) are obtained thanks to the corresponding geometric shape of the left (7) and right (7 ') horizontal punches of the biaxial compression device (1a).

On a réalisé trois séries d'essais comparatifs, notés 1a, 1b et 1c. On a représenté, respectivement aux figures 10a à 10c, la configuration du même volume Vo de la charge de poudre (9) à comprimer, en vue d'obtenir un balai cru (11) de même volume final Vf.Three series of comparative tests were carried out, denoted 1a, 1b and 1c. There is shown, respectively in FIGS. 10a to 10c, the configuration of the same volume Vo of the powder charge (9) to be compressed, in order to obtain a raw brush (11) of the same final volume Vf.

Sur le tableau qui suit, sont indiqués les taux de compression successifs : selon l'axe vertical (Ti =Vo/Vi), puis selon l'axe horizontal (Tc = Vi/Vf), le taux de compression global (TixTc) étant le même dans chacun des cas et égal à 3. Essai Ti Tc Ti/Tc TixTc Remarque 1a - 3 - 3 art antérieur 1b 1,5 2 0,75 3 selon invention 1c 2,5 1,2 2,08 3 selon invention The following table shows the successive compression rates: along the vertical axis (Ti = Vo / Vi), then along the horizontal axis (Tc = Vi / Vf), the overall compression rate (TixTc) being the same in each case and equal to 3. Test Ti Tc Ti / Tc TixTc Note 1a - 3 - 3 prior art 1b 1.5 2 0.75 3 according to invention 1 C 2.5 1.2 2.08 3 according to invention

Résultats obtenus :Results obtained:

On a d'abord examiné la texture des balais obtenus.
Pour cela, on a représenté, sur chacune des figures 10a à 10c, l'orientation des particules du balai cru final (11), relevée par examen de coupes micrographiques.We first examined the texture of the brushes obtained.
For this, there is shown, in each of Figures 10a to 10c, the orientation of the particles of the final raw brush (11), noted by examination of micrographic sections.

On a observé que le balai (11) de l'essai la, correspondant à l'art antérieur et ne comprenant qu'une compression selon l'axe horizontal, est homogène et anisotrope, les particules étant orientées dans le plan "a-t" perpendiculaire à la direction de compression Tc selon l'axe horizontal.It was observed that the brush (11) of test la, corresponding to the prior art and comprising only a compression along the horizontal axis, is homogeneous and anisotropic, the particles being oriented in the plane "a-t "perpendicular to the direction of compression Tc along the horizontal axis.

Dans le cas du balai (11) de l'essai lb, selon l'invention, on a observé que le balai est homogène et anisotrope, les particules étant orientées dans le plan "a-r" perpendiculaire à la direction de compression Ti (selon l'axe vertical), sauf sur une épaisseur E d'environ 2 mm aux extrémités du balai, à la tête (19) et au pied (18) où les particules sont orientées selon le plan "a-t", perpendiculaire à la direction de compression Tc (selon l'axe horizontal).
Dans le cas de l'essai 1c, les résultats obtenus sont analogues à ceux de l'essai 1b, sauf que l'épaisseur E est d'environ 1 mm, au lieu de 2 mm pour l'essai 1b.In the case of the brush (11) of test lb, according to the invention, it was observed that the brush is homogeneous and anisotropic, the particles being oriented in the plane "ar" perpendicular to the direction of compression Ti (according to l 'vertical axis), except over a thickness E of about 2 mm at the ends of the brush, at the head (19) and at the foot (18) where the particles are oriented along the plane "a-t", perpendicular to the direction compression Tc (along the horizontal axis).
In the case of test 1c, the results obtained are similar to those of test 1b, except that the thickness E is approximately 1 mm, instead of 2 mm for test 1b.

Par ailleurs, les balais ont été testés au banc d'essai. On a ainsi pu vérifier la supériorité de commutation des balais selon l'invention (1b et 1c) par rapport au balais selon l'art antérieur (1a).In addition, the brushes have been tested on the test bench. It was thus possible to check the switching superiority of the brushes according to the invention (1b and 1c) relative to the brushes according to the prior art (1a).

Exemple 2Example 2

On a fabriqué des balais (11) dont le cable (12) est fixé selon l'axe "r" du balai. Voir figures 11a et 11b.
On a utilisé pour cela le même dispositif de compression biaxiale (1a) que celui utilisé pour l'exemple 1. Le mélange de poudres à comprimer comprend, outre de la poudre de graphite, de la poudre de cuivre (40% en volume). Essai Ti Tc Ti/Tc TixTc Remarque 2a 3 - - 3 art antérieur 2b 1,5 2 0,75 3 selon invention We made brushes (11) whose cable (12) is fixed along the axis "r" of the brush. See Figures 11a and 11b.
The same biaxial compression device (1a) was used for this as that used for Example 1. The mixture of powders to be compressed comprises, in addition to the graphite powder, copper powder (40% by volume). Test Ti Tc Ti / Tc TixTc Note 2a 3 - - 3 prior art 2b 1.5 2 0.75 3 according to invention

Comme dans le cas de l'exemple 1, on a observé et représenté sur les figures 11a et 11b l'orientation des particules à la fin de la compression.
On a observé que, dans le cas de l'essai témoin 2a selon l'art antérieur (voir figure 11a), les particules sont orientées de manière uniforme dans le plan perpendiculaire à la direction de compression (compression verticale - Ti = 3). Par contre, dans le cas de l'essai 2b selon l'invention (voir figure 11b), on observe que le "coeur" du balai présente une orientation des particules dans le plan perpendiculaire à la première compression (compression verticale - Ti = 1,5), tandis que "la peau" du balai présente, sur une épaisseur E de 2 mm environ, une orientation des particules dans un plan perpendiculaire à "t" et à la direction de la compression complémentaire (compression horizontale - Tc = 2).As in the case of Example 1, the orientation of the particles at the end of the compression has been observed and shown in FIGS. 11a and 11b.
It was observed that, in the case of the control test 2a according to the prior art (see FIG. 11a), the particles are oriented uniformly in the plane perpendicular to the direction of compression (vertical compression - Ti = 3). On the other hand, in the case of test 2b according to the invention (see FIG. 11b), it is observed that the "core" of the brush has an orientation of the particles in the plane perpendicular to the first compression (vertical compression - Ti = 1 , 5), while "the skin" of the brush has, over a thickness E of about 2 mm, an orientation of the particles in a plane perpendicular to "t" and to the direction of the complementary compression (horizontal compression - Tc = 2 ).

On a mesuré les résitivités relatives R, dans la direction "r" (Rr), et dans la direction perpendiculaire "t", pour les balais (2a) et (2b) : balai 2a balai 2b Rr/Rt voisin de 3 voisin de 1 The relative resistivity R has been measured, in the direction "r" (Rr), and in the perpendicular direction "t", for the brushes (2a) and (2b): broom 2a broom 2b Rr / Rt neighbor of 3 neighbor of 1

Les essais de ces balais, au banc d'essai, ont montré la supériorité de commutation des balais (2b) selon l'invention.The tests of these brushes, on the test bench, showed the superiority of switching of the brushes (2b) according to the invention.

Exemple 3Example 3

On a fabriqué des balais pour moteurs destinés à l'outillage portatif.
Pour cela, on a utilisé le dispositif de compression biaxiale (1a) utilisé pour les exemples 1 et 2.
On a introduit une charge de poudre de départ (9), de volume Vo, formée par l'introduction simultanée de deux charges de poudres, de nature différente - comme décrit dans la demande de brevet français n° 93-06962. En particulier, on a introduit une charge destinée à former la tête (19) du balai, riche en poudre de cuivre (plus de 50% en volume), et une charge destinée à former le bloc d'usure (25) du balai, riche en poudre de graphite, les compositions de ces charges étant connues en elle-mêmes.
Pour cet essai 3a, on a choisi Ti égal à 2,5 et Tc égal à 1,2. On a obtenu le balai représenté à la figure 12 :
la tête (19), qui comprend un téton (14a) de centrage du ressort, est relativement isotrope (représenté par des croix sur la figure 12).
Le bloc d'usure (25) du balai (11) est constitué pour l'essentiel d'un matériau anisotrope (particules orientées selon le plan "r-a"), sauf à l'extrémité (pied (18)) où, sur une épaisseur E de matériau, l'orientation des particules est dans le plan "a-t".
Par rapport aux balais des exemples précédents, ce balai est avantageux car il assure un très bon contact électrique (faible chute ohmique) entre le cable (12) et la tête du balai (19).We have made brushes for motors for portable tools.
For this, the biaxial compression device (1a) used for Examples 1 and 2 was used.
A charge of starting powder (9), of volume Vo, was introduced, formed by the simultaneous introduction of two charges of powders, of different nature - as described in French patent application No. 93-06962. In particular, a filler intended to form the head (19) of the brush, rich in copper powder (more than 50% by volume) was introduced, and a filler intended to form the wear block (25) of the brush, rich in graphite powder, the compositions of these fillers being known in themselves.
For this test 3a, we chose Ti equal to 2.5 and Tc equal to 1.2. We obtained the broom shown in Figure 12:
the head (19), which comprises a stud (14a) for centering the spring, is relatively isotropic (represented by crosses in FIG. 12).
The wear block (25) of the brush (11) consists essentially of an anisotropic material (particles oriented along the plane "ra"), except at the end (foot (18)) where, on a thickness E of material, the orientation of the particles is in the plane "a-t".
Compared to the brushes of the previous examples, this brush is advantageous because it ensures very good electrical contact (low ohmic drop) between the cable (12) and the head of the brush (19).

AVANTAGES DE L'INVENTIONADVANTAGES OF THE INVENTION

Pour l'homme du métier des balais, habitué soit à subir les conséquences de la compression uniaxiale en matière d'anisotropie et d'orientation des particules, soit à mettre en oeuvre des étapes complémentaires d'usinage pour obtenir des balais ayant des moyens géométriques souhaités, l'invention fait figure sinon de révolution, du moins d'étape essentielle vers la maîtrise simultanée de l'orientation souhaitée des particules du balai, de la configuration géométrique, notamment de la tête et du pied du balai, et des coûts.
Les multiples figures et exemples sont là pour illustrer, à titre d'exemples, la grande richesse de l'invention.
L'invention rend possible la fabrication économique d'une grande variété de balais, aux formes géométriques et anisotropies les plus diverses, de sorte qu'elle constitue l'outil révé du fabricant de balais qui doit constamment améliorer ses produits et les adapter à des demandes nouvelles.For the person skilled in the art of brushes, accustomed either to undergo the consequences of uniaxial compression in matter of anisotropy and orientation of the particles, or to implement additional machining steps to obtain brushes having desired geometric means, the invention is if not revolution, at least an essential step towards simultaneous control the desired orientation of the particles of the broom, the geometric configuration, in particular of the head and the foot of the broom, and the costs.
The multiple figures and examples are there to illustrate, by way of examples, the great richness of the invention.
The invention makes it possible to economically manufacture a wide variety of brushes, with the most diverse geometric shapes and anisotropies, so that it constitutes the perfect tool for the brush manufacturer who must constantly improve his products and adapt them to new demands.

Claims (21)

1 - Dispositif (1) de fabrication de balais (11) comprenant une matrice (2) munie d'une cavité destinée à recevoir au moins une poudre conductrice à comprimer et d'au moins un poinçon de compression, caractérisé en ce que ladite matrice (2) est munie de deux gaines concourantes (3,4) formant ladite cavité, et orientées à 90° l'une par rapport à l'autre, l'une (3) étant orientée selon la verticale, et l'autre (4) selon l'horizontale, et en ce que chacune de ces gaines est dotée de moyens de compression, comprenant au moins un poinçon de compression (6,6',7,7'), de manière à obtenir la compression biaxiale de ladite poudre. 1 - Device (1) for manufacturing brushes (11) comprising a matrix (2) provided with a cavity intended to receive at least one conductive powder to be compressed and at least one compression punch, characterized in that said matrix (2) is provided with two concurrent sheaths (3,4) forming said cavity, and oriented at 90 ° relative to one another, one (3) being oriented vertically, and the other ( 4) according to the horizontal, and in that each of these sheaths is provided with compression means, comprising at least one compression punch (6.6 ', 7.7'), so as to obtain the biaxial compression of said powder. 2 - Dispositif selon la revendication 1 dans lequel lesdites gaines (3) et (4) sont de sections respectives Sv et Sh rectangulaires, carrées ou trapézoïdales, et se raccordent en un volume commun (5) résultant, de préférence, de la projection orthogonale des sections Sv et Sh. 2 - Device according to claim 1 wherein said sheaths (3) and (4) are of respective sections S v and S h rectangular, square or trapezoidal, and are connected in a common volume (5) resulting, preferably, from the orthogonal projection of sections S v and S h . 3 - Dispositif selon la revenication 2 dans lequel ladite gaine verticale (3) est munie à sa partie inférieure d'un poinçon de compression (6') et à sa partie supérieure d'une plaque amovible (8) de surface supérieure à la section Sv. 3 - Device according to claim 2 in which said vertical sheath (3) is provided at its lower part with a compression punch (6 ') and at its upper part with a removable plate (8) with a surface greater than the section S v . 4 - Dispositif selon la revendication 2 dans lequel ladite gaine verticale (3) est munie à sa partie inférieure d'un poinçon de compression (6') et à sa partie supérieure d'un autre poinçon de compression (6), de manière à pouvoir effectuer selon l'axe vertical une compression à double effet. 4 - Device according to claim 2 wherein said vertical sheath (3) is provided at its lower part with a compression punch (6 ') and at its upper part with another compression punch (6), so as to ability to perform double-acting compression along the vertical axis. 5 - Dispositif selon une quelconque des revendications 3 et 4 dans lequel ladite gaine horizontale (4) est munie de deux poinçons de compression (7) et (7'), de manière à pouvoir effectuer selon l'axe horizontal une compression à double effet. 5 - Device according to any one of claims 3 and 4 wherein said horizontal sheath (4) is provided with two compression punches (7) and (7 '), so as to be able to perform along the horizontal axis a double effect compression . 6 - Dispositif selon une quelconque des revendications 3 et 4 dans lequel ladite gaine horizontale (4) est, à une extrémité, munie d'un seul poinçon (7'), l'autre extrémité étant formée par une portion d'une des parois de la gaine verticale (3). 6 - Device according to any one of claims 3 and 4 wherein said horizontal sheath (4) is, at one end, provided with a single punch (7 '), the other end being formed by a portion of one of the walls of the vertical sheath (3). 7 - Dispositif selon la revendication 3 et une quelconque des revendication 5 ou 6 dans lequel ladite plaque amovible (8) forme aussi la paroi supérieure de ladite gaine horizontale (4). 7 - Device according to claim 3 and any one of claims 5 or 6 wherein said removable plate (8) also forms the upper wall of said horizontal sheath (4). 8 - Dispositif selon une quelconque des revendications 1 à 7 dans lequel lesdits moyens de compression d'une gaine (3,4) sont mis en oeuvre sous contrôle de déplacement, et dans lequel lesdits moyens de compression de l'autre gaine (4,3) sont mis en oeuvre sous contrôle de la pression exercée. 8 - Device according to any one of claims 1 to 7 wherein said means for compressing a sheath (3,4) are implemented under displacement control, and wherein said means for compressing the other sheath (4, 3) are implemented under control of the pressure exerted. 9 - Dispositif selon la revendication 8 dans lequel lesdits moyens de compression de ladite gaine verticale (3) sont mis en oeuvre sous contrôle de déplacement, tandis que lesdits moyens de compression de ladite gaine horizontale (4) sont mis en oeuvre sous contrôle de la pression exercée. 9 - Device according to claim 8 wherein said means for compressing said vertical sheath (3) are implemented under displacement control, while said means for compressing said horizontal sheath (4) are implemented under control of pressure exerted. 10 - Procédé de fabrication de balais à l'aide du dispositif, selon une quelconque des revendications 1 à 9 dans lequel, comprenant une matrice (2,2a,2b) à deux gaines concourantes à 90° l'une de l'autre, l'une verticale (3), l'autre horizontale (4), munies chacune d'au moins un poinçon (respectivement (6') et (7')), formant une cavité de compression de volume utile Vo, dans lequel, de manière à former un balai cru (11) à dimensions prédéterminées et à anisotropie orientée favorablement, a) les moyens de compressions étant en position écartée, on introduit dans ladite cavité une charge (9), de volume Vo, d'au moins une poudre conductrice, b) on réalise une première compression, sous contrôle de déplacement, à l'aide des moyens de compression d'une des deux gaines (3 ou 4), de manière à obtenir une cavité intermédiaire tubulaire, de volume Vi, ayant la section de l'autre gaine (respectivement 4 ou 3), et à conserver constante cette section durant toute l'étape c) de seconde compression du balai, de manière à obtenir un balai cru (12) à section bien calibrée après l'étape c), c) on réalise une seconde compression, sous contrôle de pression, à l'aide des moyens de compression de l'autre gaine (respectivement 4 ou 3), de manière à obtenir un balai cru (11) de volume final Vf avec le taux de compression final souhaité, d) on écarte les moyens de compression de chacune des gaines, d'abord ceux sous contrôle de pression, puis ceux sous contrôle de déplacement, et on éjecte le balai cru (11). 10 - A method of manufacturing brushes using the device according to any one of claims 1 to 9 in which, comprising a matrix (2,2a, 2b) with two concentric sheaths at 90 ° from one another, one vertical (3), the other horizontal (4), each provided with at least one punch (respectively (6 ') and (7')), forming a compression cavity of useful volume Vo, in which, so as to form a raw broom (11) with predetermined dimensions and with an anisotropy oriented favorably, a) the compression means being in the separated position, a charge (9), of volume V o , of at least one conductive powder is introduced into said cavity, b) a first compression is carried out, under displacement control, using the compression means of one of the two sheaths (3 or 4), so as to obtain a tubular intermediate cavity, of volume V i , having the section of the other sheath (respectively 4 or 3), and to keep this section constant throughout step c) of second compression of the brush, so as to obtain a raw brush (12) with a well calibrated section after step c), c) a second compression is carried out, under pressure control, using the compression means of the other sheath (respectively 4 or 3), so as to obtain a raw brush (11) of final volume V f with the desired final compression ratio, d) the compression means of each of the sheaths are removed, first those under pressure control, then those under displacement control, and the raw brush (11) is ejected. 11 - Procédé selon la revendication 10 dans lequel, de préférence, on met en oeuvre, sous contrôle de déplacement, les moyens de compression de la gaine verticale (3), et sous contrôle de pression, les moyens de compression de la gaine horizontale (4). 11 - The method of claim 10 wherein, preferably, it implements, under displacement control, the compression means of the vertical sheath (3), and under pressure control, the compression means of the horizontal sheath ( 4). 12 - Procédé selon une quelconque des revendications 10 et 11 dans lequel le taux moyen de compression initiale (Ti = Vo/Vi) réalisé par la mise en oeuvre des moyens de compression sous contrôle de déplacement est compris entre 1,5 et 3,5, le taux de compression complémentaire (Tc = Vi/Vf) réalisé sous contrôle de pression étant compris entre 1,1 et 2, le taux de compression total Tt (Tt= TixTc) étant généralement compris entre 2,5 et 4 selon la nature des poudres de départ. 12 - Method according to any one of claims 10 and 11 wherein the average initial compression ratio (T i = V o / V i ) achieved by the implementation of the compression means under displacement control is between 1.5 and 3.5, the additional compression ratio (T c = V i / V f ) produced under pressure control being between 1.1 and 2, the total compression ratio T t (T t = T i xT c ) being generally between 2.5 and 4 depending on the nature of the starting powders. 13 - Procédé selon la revendication 12 dans lequel on choisit l'anisotropie d'un balai en jouant sur la part relative de Ti et de Tc pour obtenir le taux de compression total Tt, l'anisotropie du balai étant d'autant plus élevée que le rapport 2.(Vo-Vi)/(Vo-Vf) s'écarte de 1, parce que, soit Ti/Tt, soit Tc/Tt sont proches de 1. 13 - The method of claim 12 wherein one chooses the anisotropy of a brush by playing on the relative share of T i and T c to obtain the total compression ratio T t , the anisotropy of the brush being all the more higher than the ratio 2. (V o -V i ) / (V o -V f ) deviates from 1, because either T i / T t or T c / T t are close to 1. 14 - Procédé selon une quelconque des revendications 11 à 13 dans lequel on utilise les moyens de compression de la gaine horizontale (4) pour obtenir la forme souhaitée de la tête (téton (14a), trou(15)...) et/ou du pied du balai (courbure adaptée à celle du collecteur, face de contact striée). 14 - Process according to any one of claims 11 to 13 in which the compression means of the horizontal sheath (4) are used to obtain the desired shape of the head (stud (14a), hole (15) ...) and / or of the broom foot (curvature adapted to that of the collector, striated contact face). 15 - Procédé selon une quelconque des revendications 11 à 14 dans lequel on utilise les moyens de compression de la gaine verticale (3) pour munir les parois latérales du balai cru de rainures / nervures (16a). 15 - Method according to any one of claims 11 to 14 wherein the compression means of the vertical sheath (3) are used to provide the side walls of the raw brush with grooves / ribs (16a). 16 - Procédé selon une quelconque des revendications 10 à 15 dans lequel tout moyen de compression, mais de préférence le moyen de compression mis en oeuvre sous contrôle de déplacement, peut être utilisé pour incorporer une extrémité du conducteur de connexion électrique (12), ou tout autre objet devant être au moins en partie noyé dans la poudre à comprimer. 16 - Method according to any one of claims 10 to 15 wherein any compression means, but preferably the compression means implemented under displacement control, can be used to incorporate one end of the electrical connection conductor (12), or any other object that must be at least partially embedded in the powder to be compressed. 17 - Procédé selon une quelconque des revendications 11 à 16 dans lequel, de manière à obtenir un balai cru ayant une extrémité plus dense que l'autre, a) on utilise un dispositif, selon la revendication 6, dans lequel ladite gaine horizontale (4) est, à une extrémité, munie d'un seul poinçon (7'), l'autre extrémité étant formée par une portion d'une des parois de la gaine verticale (3), b) lors de la compression, sous contrôle de déplacement, dudit mélange de poudres, ledit taux moyen de compression initiale Ti est choisi au moins égal à 2, et inférieur à 0,9 Tt. 17 - Method according to any one of claims 11 to 16 wherein, so as to obtain a raw brush having one end more dense than the other, a) using a device according to claim 6, wherein said horizontal sheath (4) is, at one end, provided with a single punch (7 '), the other end being formed by a portion of one of walls of the vertical sheath (3), b) during compression, under displacement control, of said mixture of powders, said initial initial compression ratio T i is chosen at least equal to 2, and less than 0.9 T t . 18 - Balai, obtenu à l'aide du dispositif selon une quelconque des revendications 1 à 9, caractérisé par l'hétérogénéité de son anisotropie, entre le "coeur" du balai et deux des 6 faces du balai (sur une épaisseur E, de l'ordre de quelques millimètres au plus) : l'orientation des particules du "coeur" du balai est à 90° de l'orientation des particules de deux des 6 faces du balai. 18 - Broom, obtained using the device according to any one of claims 1 to 9, characterized by the heterogeneity of its anisotropy, between the "heart" of the broom and two of the 6 faces of the broom (over a thickness E, of on the order of a few millimeters at most): the orientation of the particles in the "core" of the brush is 90 ° from the orientation of the particles on two of the 6 faces of the brush. 19 - Balai selon la revendication 19 dans lequel les particules du "coeur" sont orientées dans le plan "a-r", et les particules de la tête (19) et du pied (18) sont orientées dans le plan "a-t" ou "t-r". 19 - Broom according to claim 19 wherein the particles of the "heart" are oriented in the plane "ar", and the particles of the head (19) and the foot (18) are oriented in the plane "a-t" or "tr". 20 - Balai selon la revendication 19 dans lequel le "coeur" a des particules orientées selon le plan "a-t", deux faces du balai ayant, sur une épaisseur E, des particules orientées selon le plan "a-r". 20 - Broom according to claim 19 wherein the "heart" has particles oriented along the plane "a-t", two faces of the brush having, over a thickness E, particles oriented along the plane "ar". 21 - Balai selon une quelconque des revendications 18 à 20 dont la tête (19) et le pied (18) sont dotés de moyens géométriques (courbure, tétons, trous, etc...) adaptés à l'usage de ces balais, moyens obtenus directement au cours de l'étape de compression biaxiale. 21 - Broom according to any one of claims 18 to 20, the head (19) and the foot (18) of which are provided with geometric means (curvature, pins, holes, etc.) suitable for the use of these brooms, means obtained directly during the biaxial compression stage.
EP94420362A 1993-12-23 1994-12-19 Process and device for economical production of brushes with prescribed anisotropy Expired - Lifetime EP0662738B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9315769A FR2714542B1 (en) 1993-12-23 1993-12-23 Device for economical manufacture of brushes with predetermined anisotropy and corresponding method.
FR9315769 1993-12-23

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EP0662738A1 true EP0662738A1 (en) 1995-07-12
EP0662738B1 EP0662738B1 (en) 1997-09-17

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US (1) US5626803A (en)
EP (1) EP0662738B1 (en)
JP (1) JPH07211428A (en)
AT (1) ATE158444T1 (en)
DE (1) DE69405700T2 (en)
ES (1) ES2107160T3 (en)
FR (1) FR2714542B1 (en)

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FR2911728A1 (en) * 2007-01-24 2008-07-25 Valeo Equip Electr Moteur Brush for electrical rotating machine, has end face covered with buffer layer realized in material to reduce electrical contact resistance with material constituting external surface of slip ring

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DE10209199A1 (en) * 2002-03-04 2003-10-02 Schunk Kohlenstofftechnik Gmbh Process for producing a multi-layer carbon brush
DE202007003159U1 (en) 2007-03-01 2007-05-10 Schunk Kohlenstofftechnik Gmbh Brush contact picking up current from conductive guide rail, comprises sliding contact, carrier and contact pin, all forming parts of a single molded unit
DE102012010481A1 (en) * 2012-05-26 2013-11-28 Brose Fahrzeugteile GmbH & Co. Kommanditgesellschaft, Würzburg Method for producing a brush of a commutator motor
JP7438614B2 (en) * 2020-12-28 2024-02-27 クアーズテック合同会社 Sliding brush for electrical machinery and its manufacturing method

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US3906624A (en) * 1973-03-07 1975-09-23 Fuji Carbon Manufacturing Co L Electrical machine brush and method and apparatus for manufacturing the same
FR2445045A1 (en) * 1978-12-23 1980-07-18 Bosch Gmbh Robert ELECTRIC MACHINE, PARTICULARLY AN ELECTRIC MOTOR COMPRISING A MANIFOLD AND AT LEAST ONE MOP BROOM APPLIED AGAINST IT AND METHOD FOR MANUFACTURING THE MOP BROOM
DE9306573U1 (en) * 1992-05-04 1993-06-24 Le Carbone Lorraine, Courbevoie, Hauts-De-Seine, Fr

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Publication number Priority date Publication date Assignee Title
FR2911728A1 (en) * 2007-01-24 2008-07-25 Valeo Equip Electr Moteur Brush for electrical rotating machine, has end face covered with buffer layer realized in material to reduce electrical contact resistance with material constituting external surface of slip ring

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JPH07211428A (en) 1995-08-11
DE69405700D1 (en) 1997-10-23
FR2714542A1 (en) 1995-06-30
US5626803A (en) 1997-05-06
DE69405700T2 (en) 1998-02-19
ATE158444T1 (en) 1997-10-15
FR2714542B1 (en) 1996-02-02
EP0662738B1 (en) 1997-09-17
ES2107160T3 (en) 1997-11-16

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