WO1995021026A1 - Method and device for dispensing a mixture of compressed air and powder - Google Patents

Method and device for dispensing a mixture of compressed air and powder Download PDF

Info

Publication number
WO1995021026A1
WO1995021026A1 PCT/FR1995/000124 FR9500124W WO9521026A1 WO 1995021026 A1 WO1995021026 A1 WO 1995021026A1 FR 9500124 W FR9500124 W FR 9500124W WO 9521026 A1 WO9521026 A1 WO 9521026A1
Authority
WO
WIPO (PCT)
Prior art keywords
compressed air
powder
duct
mixing chamber
valve
Prior art date
Application number
PCT/FR1995/000124
Other languages
French (fr)
Inventor
Christian Diat
Alfred Hubschen
Original Assignee
Christian Diat
Alfred Hubschen
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from FR9401316A external-priority patent/FR2720662B1/en
Application filed by Christian Diat, Alfred Hubschen filed Critical Christian Diat
Publication of WO1995021026A1 publication Critical patent/WO1995021026A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/14—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas designed for spraying particulate materials
    • B05B7/1404—Arrangements for supplying particulate material
    • B05B7/144—Arrangements for supplying particulate material the means for supplying particulate material comprising moving mechanical means
    • B05B7/1445—Arrangements for supplying particulate material the means for supplying particulate material comprising moving mechanical means involving vibrations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B12/00—Arrangements for controlling delivery; Arrangements for controlling the spray area
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B15/00—Details of spraying plant or spraying apparatus not otherwise provided for; Accessories
    • B05B15/50—Arrangements for cleaning; Arrangements for preventing deposits, drying-out or blockage; Arrangements for detecting improper discharge caused by the presence of foreign matter
    • B05B15/55—Arrangements for cleaning; Arrangements for preventing deposits, drying-out or blockage; Arrangements for detecting improper discharge caused by the presence of foreign matter using cleaning fluids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C7/00—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts
    • B24C7/0046—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier
    • B24C7/0069—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed in a gaseous carrier with means for preventing clogging of the equipment or for preventing abrasive entering the airway
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B3/00—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements
    • B05B3/02—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements

Definitions

  • the present invention relates to a method and a device for dispensing a mixture of compressed air and powder, and more precisely a powder with very fine particle size.
  • the particle size of the abrasive particles is less than 200 micrometers.
  • a sandblaster comprising a powder storage tank which is connected to a source of compressed air, generally a compressor. ; passing through the tank, the compressed air is charged with particles, which are then transferred via a flexible hose to the projection device.
  • a sandblaster comprising a powder storage tank which is connected to a source of compressed air, generally a compressor. ; passing through the tank, the compressed air is charged with particles, which are then transferred via a flexible hose to the projection device.
  • US-A-2 938 305 describes an example of such a pickling device by spraying a mixture of compressed air and an abrasive comprising: - a source of compressed air,
  • a powder storage tank a spray head for projecting the mixture of compressed air and powder towards a surface to be treated
  • a compressed air pipe connecting the source of compressed air to the spray head, this pipe comprising , from upstream to downstream, a compressed air supply pipe, a mixing chamber and an evacuation pipe, a powder supply pipe with converging walls, having a narrow outlet orifice and a wider inlet which communicates with the powder storage tank, the outlet orifice communicating with the mixing chamber via a powder control valve capable of selectively occupying a closed position, where it closes said orifice outlet, and an open position, and control means operable from the vicinity of the spray head to control the powder control valve.
  • the particle flow is irregular and does not allow to obtain a homogeneous flow. This is particularly the case when the arrival of the air / powder mixture is frequently stopped, when the operation is restarted.
  • the object of the present invention is to overcome the above-mentioned drawbacks by proposing a device which makes it possible to obtain a very weak flow. loaded with abrasive and regular, allowing to use the abrasive temporarily and selectively, without problem of clogging of the nozzles, despite the very fine fineness of their passage section.
  • Another objective of the invention is to propose a device of simple design.
  • a device for spraying a mixture of compressed air and abrasive of the kind in question is essentially characterized in that the very fine sections of passage of the nozzles (106 a) of the disc projection (106) are constantly released by compressed air pressure.
  • This compressed air pressure takes place via the compressed air duct (204, 6, 7, 70, 71, 206) independently of the actuation of the control means (104, 104 a) and independently of the position of the abrasive control valve (4).
  • the head is continuously traversed by a flow of compressed air which guarantees that the nozzles of the projector head are not blocked, despite the very fine section of these nozzles, which section is of the order of a millimeter.
  • the compressed air supply duct comprises a first pressure adjustment means
  • the powder storage tank communicates with the source of compressed air by means of a conduit which has a second adjustment means for separate pressure from the first, the compressed air thus having pressures adjustable independently of each other, respectively in the mixing chamber and in the powder storage tank: thus, it is possible to very finely regulate the flow of sprayed powder, adjusting the compressed air pressure in the powder storage tank relative to the compressed air pressure in the mixing chamber.
  • the powder control valve communicates with the mixing chamber via a transfer duct inclined downstream relative to the mixing chamber: this creates a suction in the transfer duct, which s 'is shown to participate effectively in obtaining a fine adjustment and a great regularity of the flow rate of sprayed powder, in particular by facilitating an arrival of the powder towards the mixing chamber,
  • the transfer duct has, at least in the vicinity of the mixing chamber, a section smaller than the section of said mixing chamber: this arrangement also facilitates the regularity of the flow rate of sprayed powder, in particular by preventing the flow of powder towards the mixing chamber is disturbed by turbulence of compressed air, the powder control valve communicates with the mixing chamber via a transfer duct, this transfer duct and the mixing chamber being shaped so that a flow of compressed air in the mixing chamber, from the compressed air source, creates suction in the transfer duct,
  • the powder control valve is controlled by a pneumatic actuator supplied with compressed air from the compressed air source
  • the control means comprise a single trigger arranged in the vicinity of the spray head to actuate a pilot valve which controls the compressed air supply to 1 pneumatic actuator of the powder control valve
  • the spray head is rotated by a pneumatic motor supplied with compressed air from the compressed air source
  • the pilot valve also controls the supply in compressed air from the pneumatic motor
  • a pneumatic vibrator is mounted on the powder supply pipe to communicate vibrations to it, this vibrator being supplied with compressed air from the compressed air source
  • the pilot valve also controls the '' compressed air supply to the pneumatic vibrator
  • the evacuation duct has a diffusion chamber which is closed by a filter grid having a relatively large surface and provided with a multitude of passage holes which have a small section, slightly less than a section corresponding to the diameter of passage of the nozzles of the projecting head and slightly greater than a section corresponding to the particle size of the powder, the discharge duct having an average section less than the surface of the filtering grid: this arrangement makes it possible to filter the particles or clusters of particles which would risk to plug the head nozzles headlamp, without creating too great a pressure drop in the compressed air duct,
  • the through holes of the filtering grid have a diameter of between 300 micrometers and 2 millimeters for nozzles of the projector head having a through diameter between 400 micrometers and 4 millimeters,
  • the diffusion chamber is composed of two coaxial parts, with frustoconical walls, namely a divergent part, upstream of the grid, and a convergent part downstream of the grid,
  • the divergent part of the diffusion chamber has a substantially vertical axis and diverges from a purge orifice forming a lower portion of said divergent chamber, this purge orifice being equipped with a shutter: it is thus possible to evacuate time to another the particles or mass of particles stopped by the filtering grid,
  • a shutter is also mounted downstream of the converging part of the diffusion chamber, for closing the exhaust duct: by closing the shutter which is mounted downstream from the converging part of the diffusion chamber and opening the shutter from the orifice of the purge of this same chamber while the flow of compressed air is maintained, it is thus " possible to very effectively evacuate the particles or clumps of particles stopped by the filtering grid,
  • the powder supply duct, the mixing chamber and the diffusion chamber are formed in a casing made of synthetic material
  • the synthetic material is a polyamide: this material has both the advantage of resisting abrasion well and of avoiding condensation phenomena,
  • the powder supply conduit is substantially vertical, with its outlet orifice directed downwards, and is provided with deflectors limiting the packing of the powder
  • the outlet orifice for the powder supply conduit has a diameter between 4 and 20 millimeters, advantageously between 8 and 12 millimeters
  • the powder control valve is a butterfly valve provided with a pivoting shutter blade: this type of valve is particularly advantageous in the device of the invention, insofar as it is little subject to blockages
  • the powder storage tank communicates with the source of compressed air and the supply duct and the powder supply duct, in the vicinity of its outlet orifice, a venting passage equipped with a shutter: in the event of blockage of the outlet orifice of the powder supply duct, it is thus possible to unblock this outlet orifice by opening the shutter of the air passage, which causes a purge of the powder supply duct under the effect of the compressed air pressure prevailing in the powder storage tank, - the powder supply duct has a substantially frustoconical wall, the powder control valve communicates with the mixing chamber via a transfer duct, and the discharge duct comprises a diffusion chamber arranged upstream of an outlet duct, this diffusion chamber being closed by a filtering grid provided with a multitude of small cross-section holes , slightly greater than the section corresponding to the particle size of the powder, - the diameter of passage of the nozzles of the projector head is between 400 micrometers and 2 millimeters.
  • the invention also relates to a method of pickling by spraying a mixture of compressed air and abrasive powder by means of a device as defined above, in which the powder storage tank communicates with the source.
  • compressed air and in which the compressed air pressures respectively in the mixing chamber and in the compressed air tank are regulated independently of each other this method comprising a step of regulating a flow rate of powder to the mixing chamber by regulating the pressure of compressed air which prevails in the powder storage tank, in a pressure range between PI- (0.5. 10 Pa) and P1 + (0.5. 10 Pa) where PI is the pressure of compressed air in the mixing chamber .
  • the pressure of compressed air in the powder storage tank is adjusted in a range between PI- (0.2. 10 Pa) and Pl + (0.2. 10 Pa).
  • FIG. 1 is a partial sectional view of an example of a device according to the invention
  • FIG. 2 is a diagram of a device for projecting abrasive particles according to the invention
  • FIG. 1 designates a housing made of synthetic material, composed of two parts 1A and 1B fixed to each other, the assembly constituting a compact block.
  • This material in fact, has both good qualities of resistance to abrasion and avoids the phenomena of condensation which occur on metal walls.
  • the device 1 comprises a connector 10 on which a nozzle 11 is fitted which is integral with a powder storage tank C, which is symbolized by a line interrupted loudly.
  • This tank C is generally subjected to compressed air pressure, as will be seen below.
  • the connector 10 is tubular and opens into a coaxial conduit 3, called the supply conduit. It is a chamber with a frustoconical wall, of vertical axis, the outlet opening 30 of which faces downwards. At the inlet of the conduit 3 is mounted a shutter 2 manually controlled by means of a lever 20. As an indication, the frustoconical wall of the conduit 3 has an angle at the top u of the order of 20 °.
  • deflecting vanes 31 Inside the duct 3 are mounted deflecting vanes 31 arranged in staggered rows and slightly inclined in the direction of flow, by gravity, of the powder from top to bottom, towards the outlet orifice 30. Their function is to absorb part of the weight of the powder mass, avoiding settling, and promote the flow of particles.
  • a vibrator 9 with pneumatic control, the function of which - well known per se - is also to encourage the passage of particles in the outlet zone 30, of the smallest diameter.
  • This lower part of the duct 3 is occupied by a frustoconical end piece 32 which can optionally be removable and interchangeable, in which case a series of end pieces can be provided with more or less fine outlet orifices 30.
  • the outlet orifice 30 has a large diameter opposite the very low flow of projected abrasive, this diameter being between 4 and 20 millimeters, and advantageously between 8 and 12 millimeters, for example equal to 8 millimeters.
  • the outlet orifice 30 is selectively closable by means of a butterfly-type valve 4, having a pivoting obturator pallet 40 in the form of a disc.
  • Valve 4 is pneumatically operated. It is normally closed, and opens when it is supplied with compressed air.
  • the device 1 is provided with a conduit 6 called the mixing chamber. It is a horizontal cylindrical duct having a tapped end zone 60, for the adaptation of a hose connector for supplying compressed air into the duct 6.
  • This duct is located below and directly above the outlet orifice 30, with which it communicates by a transfer duct 5, inclined downward and downstream if we consider the direction of movement of the flow d compressed air in line 6.
  • This transfer duct can have a generally frustoconical shape, with a decreasing section in the direction of the mixing chamber, as shown, or it can have a cylindrical shape.
  • the transfer duct 5 has, at least in the vicinity of the mixing chamber, a section smaller than the section of said mixing chamber.
  • the lower part, and upstream 7 diverges towards the grid, while the upper part, and downstream 70, converges from the grid.
  • the filter grid is a disc made of a material very resistant to abrasion, for example tungsten carbide, pierced with a plurality of cylindrical holes 80 of very small diameter, nevertheless greater than the largest dimensions of the powder particles.
  • the particle size of the powder is from 0 to 200 micrometers, and the holes 80 have a dameter of between 300 and 800 micrometers for nozzles having a passage diameter of the order of a millimeter.
  • the arrows G and H respectively symbolize the entry of the air / powder mixture into part 7 of the diffusion chamber, and its evacuation from part 70, via an outlet conduit 71.
  • connection sleeve provided with a manually operated shutter
  • a shutter 22 intended to purge the diffusion chamber, through a
  • the shutter devices 2, 21 and 22 are of the plug type. In operation, the shutters 2 and 21 are open while the shutter 22 is closed.
  • the conduit 6 is permanently connected to a source of compressed air supplying pressurized air according to F2.
  • the air / powder mixture is then diffused in the divergent chamber part 7.
  • this part 7 is a mass of suspended particles, part of which passes through the holes 80, while the rest abuts against the grid 8 to be taken up by the air flow, until the particles arrive at go through one of the holes 80 in the grid.
  • the deflectors limit the packing of the powder in the converging conduit 3, while the vibrator 9 promotes the flow of the particles in the narrowed part 30.
  • FIG. 2 there is shown an installation using the device 1 which has just been described, symbolically represented by a rectangular outline in broken lines. It is an installation for stripping a surface, for example of a building facade, by projection of abrasive particles by means of a projecting head 106. The latter is rotated by a pneumatic motor 105 , via a motion transmission mechanism 300.
  • the projecting head 106 comprises a multitude of nozzles 106a of small diameter, as can be seen in FIG. 3. These nozzles preferably have a diameter between 400 micrometers and 4 millimeters and preferably, between 400 micrometers and 2 millimeters, for example between 400 micrometers and one millimeter.
  • the number of nozzles included by the spray head 106 can be from ten to several tens, for example from 10 to 500 nozzles, and advantageously from 20 to 80 nozzles, for example from 24 nozzles.
  • the compressor 100 and the device 1 are normally stationary, while the device 106 is mobile. Its supply of compressed air is therefore through flexible conduits.
  • the rotary head 106 is supplied with an air / powder mixture by the device 1 by means of a flexible pipe 206 connected to the connector 72.
  • the device 1 receives compressed air from a compressor 100 via a pipe 204 connected to the threaded portion 60 of the mixing duct 6.
  • a closing valve 107 On the line 204 is mounted a closing valve 107, which is opened during work.
  • a pressure regulator 400 for pressure adjustment associated with a pressure gauge 401 to control the pressure of compressed air downstream of the regulator 400.
  • the powder storage tank C is connected to the source 100 of compressed air through a duct 402 which also has a pressure regulator 403 associated with a pressure gauge 404 which makes it possible to control the pressure downstream of the regulator 403. It is thus possible to regulate the pressure of compressed air in the tank C of powder storage, as is known from document FR-A-2 577 457, in a different context.
  • the conduit 402 may also include a shut-off valve 405, open during work.
  • the pneumatic motor 105 is supplied from the compressor 100 by successive flexible pipes 200, 201, 203.
  • On the part 200 is a closing valve 101 and a flow divider 102.
  • a valve control 103 which is actuated by a small pilot valve 104; the latter is actuated by a trigger 104a carried by a non-rotating part of an apparatus which comprises the rotary head 106, this trigger being maneuverable by the operator.
  • the actuation of the control valve 103 is done by a compressed air supply duct 202 coming from the divider 102, via the pilot valve 104.
  • the valve 103 is a pneumatically actuated valve normally closed; it changes to the open state when the pilot valve 104 is open.
  • conduits 207 and 208 are connected respectively by conduits 207 and 208 respectively to the vibrator 9 and to the shut-off valve 4.
  • the conduits 207 and 203 carry valves with variable throttle respectively 109 and 110, allowing adjustment of the flow rates.
  • valves 101 and 107 are open and the compressor is started.
  • compressed air constantly arrives in the device, via the line 204, the device 1, and the flexible pipe 206.
  • the pilot valve 104 is closed, and does not actuate the control valve 103, which is also consequently closed (positions of FIG. 2).
  • the narrowed passage section 30 has a diameter of the order of 8 millimeters
  • the transfer duct 5 has a diameter of the order of at least 8 millimeters at its downstream end
  • the mixing duct 6 and the outlet conduit 71 have a diameter of 12 millimeters
  • the disc 8 has a diameter of 50 millimeters.
  • the pressure of the compressed air supplied by the compressor 100 is for example between 2 and 10 bars (i.e. 2. 10 and 10 Pa), in particular between 5 and 10 bars.
  • the adjustable pressure regulator 400 is adjusted to a determined value of the pressure of compressed air PI prevailing downstream, this pressure being measured by means of a pressure gauge 401. This measured pressure is close to the compressed air pressure prevailing in the mixing chamber 6, owing to the fact that there is little pressure drop between the pressure reducer 400 and the mixing chamber 6.
  • This pressure PI is adjusted in particular as a function of the force of the set of compressed air which it is desired to obtain at the outlet of the projecting head 106.
  • the pressure PI could for example be of the order of 4 bars, ie 4. 10 Pa.
  • the permanent flow of compressed air can then be approximately 1500 to 2500 l / minute, depending on the size and the number of nozzles 106a.
  • the pressure P2 could be adjusted in a range which extends between Pl-0.5 bars to Pl + 0.5 bars, that is to say between PI- (0.5. 10 Pa) and Pl + (0.5. 10 Pa), or advantageously between Pl-0.2 bars and Pl + 0.2 bars, ie Pl- (0.2. 10 Pa) and Pl + (0.2. 10 Pa).
  • the pressure P2 can thus be adjusted between, for example 3.8 and 4.2 bars, ie 3.8. 10 Pa to 4.2. 10 Pa. It is thus possible to regulate the powder flow rate in a range from approximately 120 to 140 g / minute for a pressure P2 of the order of 3.8 bars, up to 500 to 700 g / minute for a pressure P2 of the order of 4.2 bars, with a diameter of 8 millimeters for the outlet opening 30.
  • the device which has just been described therefore allows a regular and precise metering of the powder in the continuous flow of compressed air, and this, without resorting to a screw needle or to other means of throttling the outlet orifice 30 of the powder supply duct, which are subject to rapid wear and do not allow an equivalent metering precision and regularity to be obtained.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Nozzles (AREA)

Abstract

The invention relates to a blasting device by projecting a mixture of compressed air and abrasive powder, comprising a compressed air source (100), a powder storage container (C), a projecting head (106), a compressed air conduit (204, 6, 7, 70, 71, 206) connecting the compressed air source to the projecting head, a powder supply conduit (3) having a converging wall and making the powder storage container communicate with the compressed air conduit through a valve (4) and a control trigger (104a) which can be actuated from the vicinity of the projecting head in order to control the valve. The projecting head comprises a plurality of small diameter nozzles and is permanently supplied with compressed air, independently of the actuation of the control trigger and of the position of the powder control valve.

Description

PROCEDE ET DISPOSITIF DE DISTRIBUTION D'UN MELANGE D'AIR COMPRIME ET DE POUDRE METHOD AND DEVICE FOR DISTRIBUTING A MIXTURE OF COMPRESSED AIR AND POWDER
La présente invention concerne un procédé et un dispositif de distribution d'un mélange d'air comprimé et de poudre, et plus précisément d'une poudre à granulométrie très fine. Dans plusieurs domaines de la technique, il est nécessaire de distribuer un mélange d'air comprimé et de poudre à un appareil utilisateur.The present invention relates to a method and a device for dispensing a mixture of compressed air and powder, and more precisely a powder with very fine particle size. In several areas of the art, it is necessary to deliver a mixture of compressed air and powder to a user device.
C'est notamment le cas dans le domaine du nettotage d'un support souillé, par exemple, la façade d'un bâtiment, à l'aide de fines particules abrasives.This is particularly the case in the field of cleaning a soiled support, for example, the facade of a building, using fine abrasive particles.
Dans sa demande de brevet internationale WO- 93/11908, le demandeur a proposé une installation de micro-nettoyage d'un support qui utilise une tête de projection rotative du mélange air/poudre. La projection se fait au travers d'une multitude de bguses ayant une section de passage faible, dont le diamètre, à titre indicatif, est compris entre 400 micromètres et 4 millimètres.In its international patent application WO-93/11908, the applicant has proposed a micro-cleaning installation for a support which uses a rotary spray head of the air / powder mixture. The projection is done through a multitude of nozzles having a small passage section, the diameter, for information, is between 400 micrometers and 4 millimeters.
La granulométrie des particules abrasives est inférieure à 200 micromètres.The particle size of the abrasive particles is less than 200 micrometers.
Traditionnellement, l'amenée des particules abrasives à l'appareil se fait au moyen d'un matériel de sablage, communément appelée sableuse, comprenant une cuve de stockage de la poudre qui est branchée sur une source d'air comprimé, en général un compresseur; en passant dans la cuve, l'air comprimé se charge de particules, qui sont ensuite transférées par l'intermédiaire d'un tuyau flexible à l'appareil de projection. Le document US-A-2 938 305 décrit un exemple d'un tel dispositif de décapage par projection d'un mélange d'air comprimé et d'un abrasif comprenant : - une source d'air comprimé,Traditionally, the supply of abrasive particles to the device is done by means of sandblasting equipment, commonly called a sandblaster, comprising a powder storage tank which is connected to a source of compressed air, generally a compressor. ; passing through the tank, the compressed air is charged with particles, which are then transferred via a flexible hose to the projection device. The document US-A-2 938 305 describes an example of such a pickling device by spraying a mixture of compressed air and an abrasive comprising: - a source of compressed air,
- une cuve de stockage de poudre, une tête projectrice pour projeter le mélange d'air comprimé et de poudre vers une surface à traiter, - un conduit d'air comprimé reliant la source d'air comprimé à la tête projectrice, ce conduit comprenant, d'amont en aval, un conduit d'amenée d'air comprimé, une chambre de mélangeage et un conduit d'évacuation, un conduit d'amenée de poudre à parois convergentes, présentant un orifice de sortie étroit et un orifice d'entrée plus large qui communique avec la cuve de stockage de poudre, l'orifice de sortie communiquant avec la chambre de mélangeage par l'intermédiaire d'une vanne de contrôle de poudre susceptible d'occuper sélectivement une position fermée, où elle obture ledit orifice de sortie, et une position ouverte, et des moyens de commande actionnables depuis le voisinage de la tête projectrice pour commander la vanne de contrôle de poudre. Si un tel matériel donne satisfaction avec des particules relativement grandes, et des buses projectrices de grand diamètre, on observe avec des buses de très faible section, destinées à fonctionner avec des particules abrasives très fines, des problèmes de colmatage, qui conduisent à un dysfonctionnement rapide de l'installation, ces problèmes sont particulièrement marqués avec des buses dont le diamètre de passage--est très fin et compris entre 400 micromètres et 4 millimètres, ce qui est indispensable pour décaper une surface sans l'abimer, comme indiqué dans le document P.C.T. WO 93/11908.- a powder storage tank, a spray head for projecting the mixture of compressed air and powder towards a surface to be treated, - a compressed air pipe connecting the source of compressed air to the spray head, this pipe comprising , from upstream to downstream, a compressed air supply pipe, a mixing chamber and an evacuation pipe, a powder supply pipe with converging walls, having a narrow outlet orifice and a wider inlet which communicates with the powder storage tank, the outlet orifice communicating with the mixing chamber via a powder control valve capable of selectively occupying a closed position, where it closes said orifice outlet, and an open position, and control means operable from the vicinity of the spray head to control the powder control valve. If such equipment is satisfactory with relatively large particles, and large diameter projecting nozzles, there are problems with very small section nozzles, intended to operate with very fine abrasive particles, clogging problems, which lead to a malfunction. rapid installation, these problems are particularly marked with nozzles whose passage diameter - is very fine and between 400 micrometers and 4 millimeters, which is essential for scouring a surface without damaging it, as indicated in the PCT document WO 93/11908.
De plus, le débit des particules est irrégulier et ne permet pas d'obtenir un flux homogène. C'est notamment le cas lorsqu'on arrête fréquemment l'arrivée du mélange air/poudre, lors du redémarrage de l'opération.In addition, the particle flow is irregular and does not allow to obtain a homogeneous flow. This is particularly the case when the arrival of the air / powder mixture is frequently stopped, when the operation is restarted.
La présente invention a pour objet de pallier les inconvénients ci-dessus mentionnés en proposant un dispositif qui permette d'obtenir un flux très faiblement chargé en abrasif et régulier, permettant d'utiliser l'abrasif de façon temporaire et sélective, sans problème de colmatage des buses, malgré la très grande finesse de leur section de passage. Un autre objectif de l'invention est de proposer un dispositif de conception simple.The object of the present invention is to overcome the above-mentioned drawbacks by proposing a device which makes it possible to obtain a very weak flow. loaded with abrasive and regular, allowing to use the abrasive temporarily and selectively, without problem of clogging of the nozzles, despite the very fine fineness of their passage section. Another objective of the invention is to propose a device of simple design.
A cet effet, selon l'invention, un dispositif de projection d'un mélange d'air comprimé et d'abrasif du genre en question est essentiellement caractérisé en ce que les très fines sections de passage des buses (106 a) du disque de projection (106) sont sans cesse dégagées par pression d'air comprimé. Cette pression d'air comprimé se faisant par l'intermédiaire du conduit d'air comprimé (204, 6, 7, 70, 71, 206) indépendamment de 1'actionnement des moyens de commande (104, 104 a) et indépendamment de la position de la vanne (4) du contrôle d'abrasif.To this end, according to the invention, a device for spraying a mixture of compressed air and abrasive of the kind in question is essentially characterized in that the very fine sections of passage of the nozzles (106 a) of the disc projection (106) are constantly released by compressed air pressure. This compressed air pressure takes place via the compressed air duct (204, 6, 7, 70, 71, 206) independently of the actuation of the control means (104, 104 a) and independently of the position of the abrasive control valve (4).
Ainsi, à chaque fois que l'opérateur qui manipule la tête de projection arrête de projeter le mélange d'air comprimé et de poudre, par exemple pour vérifier l'état d'une surface qu'il est en train de nettoyer, la tête projectrice est parcourue en permanence par un flux d'air comprimé qui garantit l'absence de bouchage des buses de la tête projectrice, malgré la très grande finesse de section de ces buses, section qui est de l'ordre du millimètre.Thus, each time that the operator who manipulates the projection head stops projecting the mixture of compressed air and powder, for example to check the state of a surface that he is cleaning, the head The projector is continuously traversed by a flow of compressed air which guarantees that the nozzles of the projector head are not blocked, despite the very fine section of these nozzles, which section is of the order of a millimeter.
Du fait --de la finesse des buses de la tête projectrice, ce flux permanent d'air comprimé correspond à un débit relativement modéré d'air comprimé, donc ne consomme pas trop d'énergie.Due to the fineness of the projector's head nozzles, this permanent flow of compressed air corresponds to a relatively moderate flow of compressed air, therefore does not consume too much energy.
De plus, à chaque fois que l'opérateur déclenche à nouveau la projection de poudre, l'écoulement de poudre provenant de la cuve de stockage de poudre arrive dans un flux d'air comprimé qui s'écoule déjà en régime permanent, de sorte qu'on évite ainsi les surdosages de poudre qui peuvent se produire au redémarrage des dispositifs classiques, du fait notamment d'un débit d'air comprimé insuffisant au début de l'arrivée de poudre, ou d'autres phénomènes transitoires lors de l'établissement du débit d'air comprimé dans le conduit d'air comprimé : on évite le colmatage des buses de la tête projectrice lors du déclenchement de la projection de poudre, colmatage qui se produirait inévitablement en l'absence d'air comprimé, de par la très grande finesse de section des buses du disque de projection.In addition, each time the operator triggers the spraying of powder again, the flow of powder from the powder storage tank arrives in a compressed air stream which is already flowing in steady state, so that this avoids the powder overdoses that can occur when restarting conventional devices, in particular due to an insufficient compressed air flow at the start of the arrival of powder, or other transient phenomena during the establishment of the compressed air flow in the compressed air duct: the clogging of the nozzles of the spray head when the projection of powder is triggered, clogging which would occur inevitably in the absence of compressed air, due to the very fine section of the nozzles of the projection disc.
Dans des modes de réalisation préférés de l'invention, on a recours en outre à l'une et/ou à l'autre des dispositions suivantes :In preferred embodiments of the invention, use is also made of one and / or the other of the following arrangements:
- le conduit d'amenée d'air comprimé comporte un premier moyen de réglage de pression, et la cuve de stockage de poudre communique avec la source d'air comprimé par l'intermédiaire d'un conduit qui présente un deuxième moyen de réglage de pression distinct du premier, l'air comprimé présentant ainsi des pressions réglables indépendamment l'une de l'autre, respectivement dans la chambre de mélangeage et dans la cuve de stockage de poudre : ainsi, il est possible de régler très finement le débit de poudre projetée, en réglant la pression d'air comprimé dans la cuve de stockage de poudre par rapport à la pression d'air comprimé dans la chambre de mélangeage.- the compressed air supply duct comprises a first pressure adjustment means, and the powder storage tank communicates with the source of compressed air by means of a conduit which has a second adjustment means for separate pressure from the first, the compressed air thus having pressures adjustable independently of each other, respectively in the mixing chamber and in the powder storage tank: thus, it is possible to very finely regulate the flow of sprayed powder, adjusting the compressed air pressure in the powder storage tank relative to the compressed air pressure in the mixing chamber.
- la vanne de contrôle de poudre communique avec la chambre de mélangeage par l'intermédiaire d'un conduit de transfert incliné vers l'aval par rapport à la chambre de mélangeage : on crée ainsi une aspiration dans le conduit de transfert, ce qui s'est révélé participer efficacement à l'obtention d'un réglage fin et d'une grande régularité du débit de poudre projetée, notamment en facilitant une arrivée de la poudre vers la chambre de mélangeage,- the powder control valve communicates with the mixing chamber via a transfer duct inclined downstream relative to the mixing chamber: this creates a suction in the transfer duct, which s 'is shown to participate effectively in obtaining a fine adjustment and a great regularity of the flow rate of sprayed powder, in particular by facilitating an arrival of the powder towards the mixing chamber,
- le conduit de transfert présente, au moins au voisinage de la chambre de mélangeage, une section inférieure à la section de ladite chambre de mélangeage : cette disposition facilite également la régularité du débit de poudre projetée, notamment en évitant que l'écoulement de poudre vers la chambre de mélangeage soit perturbé par des turbulences d'air comprimé, - la vanne de contrôle de poudre communique avec la chambre de mélangeage par l'intermédiaire d'un conduit de transfert, ce conduit de transfert et la chambre de mélangeage étant conformés pour qu'un flux d'air comprimé dans la chambre de mélangeage, en provenance de la source d'air comprimé, crée une aspiration dans le conduit de transfert,- The transfer duct has, at least in the vicinity of the mixing chamber, a section smaller than the section of said mixing chamber: this arrangement also facilitates the regularity of the flow rate of sprayed powder, in particular by preventing the flow of powder towards the mixing chamber is disturbed by turbulence of compressed air, the powder control valve communicates with the mixing chamber via a transfer duct, this transfer duct and the mixing chamber being shaped so that a flow of compressed air in the mixing chamber, from the compressed air source, creates suction in the transfer duct,
- la vanne de contrôle de poudre est commandée par un actionneur pneumatique alimenté en air comprimé depuis la source d'air comprimé, et les moyens de commande comportent une gâchette unique disposée au voisinage de la tête projectrice pour actionner une vanne pilote qui commande l'alimentation en air comprimé de l1actionneur pneumatique de la vanne de contrôle de poudre, - la tête projectrice est entraînée en rotation par un moteur pneumatique alimenté en air comprimé depuis la source d'air comprimé, et la vanne pilote commande également l'alimentation en air comprimé du moteur pneumatique, - un vibreur pneumatique est monté sur le conduit d'amenée de la poudre pour lui communiquer des vibrations, ce vibreur étant alimenté en air comprimé depuis la source d'air comprimé, et la vanne pilote commande également l'alimentation en air comprimé du vibreur pneumatique,- the powder control valve is controlled by a pneumatic actuator supplied with compressed air from the compressed air source, and the control means comprise a single trigger arranged in the vicinity of the spray head to actuate a pilot valve which controls the compressed air supply to 1 pneumatic actuator of the powder control valve, - the spray head is rotated by a pneumatic motor supplied with compressed air from the compressed air source, and the pilot valve also controls the supply in compressed air from the pneumatic motor, - a pneumatic vibrator is mounted on the powder supply pipe to communicate vibrations to it, this vibrator being supplied with compressed air from the compressed air source, and the pilot valve also controls the '' compressed air supply to the pneumatic vibrator,
- le conduit d'évacuation comporte une chambre de diffusion qui est obturée par une grille filtrante présentant une surface relativement grande et pourvue d'une multitude de trous de passage qui présentent une faible section, légèrement inférieure à une section correspondant au diamètre de passage des buses de la tête projectrice et légèrement supérieure à une section correspondant à la granulométrie de la poudre, le conduit d'évacuation présentant une section moyenne inférieure à la surface de la grille filtrante : cette disposition permet de filtrer les particules ou amas de particules qui risqueraient de boucher les buses de la tête projectrice, et ce, sans pour autant créer une perte de charge trop importante dans le conduit d'air comprimé,- The evacuation duct has a diffusion chamber which is closed by a filter grid having a relatively large surface and provided with a multitude of passage holes which have a small section, slightly less than a section corresponding to the diameter of passage of the nozzles of the projecting head and slightly greater than a section corresponding to the particle size of the powder, the discharge duct having an average section less than the surface of the filtering grid: this arrangement makes it possible to filter the particles or clusters of particles which would risk to plug the head nozzles headlamp, without creating too great a pressure drop in the compressed air duct,
- les trous de passage de la grille filtrante présentent un diamètre compris entre 300 micromètres et 2 millimètres pour des buses de la tête projectrice ayant un diamètre de passage entre 400 micromètres et 4 millimètres,the through holes of the filtering grid have a diameter of between 300 micrometers and 2 millimeters for nozzles of the projector head having a through diameter between 400 micrometers and 4 millimeters,
- la chambre de diffusion est composée de deux parties coaxiales, à parois tronconiques, savoir une partie divergente, en amont de la grille, et une partie convergente en aval de la grille,the diffusion chamber is composed of two coaxial parts, with frustoconical walls, namely a divergent part, upstream of the grid, and a convergent part downstream of the grid,
- la partie divergente de la chambre de diffusion présente un axe sensiblement vertical et diverge à partir d'un orifice de purge formant une portion inférieure de ladite chambre divergente, cet orifice de purge étant équipé d'un obturateur : on peut ainsi évacuer de temps à autre les particules ou amas de particules arrêtées par la grille filtrante,- the divergent part of the diffusion chamber has a substantially vertical axis and diverges from a purge orifice forming a lower portion of said divergent chamber, this purge orifice being equipped with a shutter: it is thus possible to evacuate time to another the particles or mass of particles stopped by the filtering grid,
- un obturateur est également monté en aval de la partie convergente de la chambre de diffusion, pour obturer le conduit d'évacuation : en fermant l'obturateur qui est monté en aval de la partie convergente de la chambre de diffusion et ouvrant l'obturateur de l'orifice du purge de cette même chambre pendant que le flux d'air comprimé est maintenu, il est ainsi «possible d'évacuer très efficacement les particules ou amas de particules arrêtés par la grille filtrante,- a shutter is also mounted downstream of the converging part of the diffusion chamber, for closing the exhaust duct: by closing the shutter which is mounted downstream from the converging part of the diffusion chamber and opening the shutter from the orifice of the purge of this same chamber while the flow of compressed air is maintained, it is thus " possible to very effectively evacuate the particles or clumps of particles stopped by the filtering grid,
- le conduit d'amenée de poudre, la chambre de mélangeage et la chambre de diffusion sont formés dans un boitier en matériau synthétique,- the powder supply duct, the mixing chamber and the diffusion chamber are formed in a casing made of synthetic material,
- le matériau synthétique est un polyamide : ce matériau présente à la fois l'avantage de bien résister à l'abrasion et d'éviter les phénomènes de condensation,the synthetic material is a polyamide: this material has both the advantage of resisting abrasion well and of avoiding condensation phenomena,
- le conduit d'amenée de poudre est sensiblement vertical, avec son orifice de sortie dirigé vers le bas, et est muni de déflecteurs limitant le tassement de la poudre, - l'orifice de sortie du conduit d'amenée de poudre présente un diamètre compris entre 4 et 20 millimètres, avantageusement compris entre 8 et 12 millimètres, la vanne de contrôle de poudre est une vanne papillon dotée d'une palette pivotante obturatrice : ce type de vanne est particulièrement avantageux dans le dispositif de l'invention, dans la mesure où il est peu sujet aux blocages,the powder supply conduit is substantially vertical, with its outlet orifice directed downwards, and is provided with deflectors limiting the packing of the powder, the outlet orifice for the powder supply conduit has a diameter between 4 and 20 millimeters, advantageously between 8 and 12 millimeters, the powder control valve is a butterfly valve provided with a pivoting shutter blade: this type of valve is particularly advantageous in the device of the invention, insofar as it is little subject to blockages,
- la cuve de stockage de poudre communique avec la source d'air comprimé et le conduit d'amenée et le conduit d'amenée de poudre, au voisinage de son orifice de sortie, un passage de mise à l'air libre équipé d'un obturateur : en cas de bouchage de l'orifice de sortie du conduit d'amenée de poudre, il est ainsi possible de débloquer cet orifice de sortie en ouvrant l'obturateur du passage de mise en l'air, ce qui provoque une purge du conduit d'amenée de poudre sous l'effet de la pression d'air comprimé régnant dans la cuve de stockage de poudre, - le conduit d'amenée de poudre présente une paroi sensiblement tronconique, la vanne de contrôle de poudre communique avec la chambre de mélangeage par l'intermédiaire d'un conduit de transfert, et le conduit d'évacuation comporte une chambre de diffusion disposée en amont d'un conduit de sortie, 'cette chambre de diffusion étant obturée par une grille filtrante pourvue d'une multitude de trous de passage de faible section, légèrement supérieure à la section correspondant à la granulométrie de la poudre, - le diamètre de passage des buses de la tête projectrice est compris entre 400 micromètres et 2 millimètres.- the powder storage tank communicates with the source of compressed air and the supply duct and the powder supply duct, in the vicinity of its outlet orifice, a venting passage equipped with a shutter: in the event of blockage of the outlet orifice of the powder supply duct, it is thus possible to unblock this outlet orifice by opening the shutter of the air passage, which causes a purge of the powder supply duct under the effect of the compressed air pressure prevailing in the powder storage tank, - the powder supply duct has a substantially frustoconical wall, the powder control valve communicates with the mixing chamber via a transfer duct, and the discharge duct comprises a diffusion chamber arranged upstream of an outlet duct, this diffusion chamber being closed by a filtering grid provided with a multitude of small cross-section holes , slightly greater than the section corresponding to the particle size of the powder, - the diameter of passage of the nozzles of the projector head is between 400 micrometers and 2 millimeters.
L'invention a également pour objet un procédé de décapage par projection d'un mélange d'air comprimé et de poudre abrasive au moyen d'un dispositif tel que défini ci-dessus, dans lequel la cuve de stockage de poudre communique avec la source d'air comprimé et dans lequel les pressions d'air comprimé respectivement dans la chambre de mélangeage et dans la cuve d'air comprimé sont réglées indépendamment l'une de l'autre, ce procédé comportant une étape de régler un débit d'écoulement de poudre vers la chambre de mélangeage en réglant la pression d'air comprimé qui règne dans la cuve de stockage de poudre, dans une plage de pression comprise entre PI- (0,5 . 10 Pa) et P1+ (0,5 . 10 Pa) où PI est la pression d'air comprimé dans la chambre de mélangeage.The invention also relates to a method of pickling by spraying a mixture of compressed air and abrasive powder by means of a device as defined above, in which the powder storage tank communicates with the source. compressed air and in which the compressed air pressures respectively in the mixing chamber and in the compressed air tank are regulated independently of each other, this method comprising a step of regulating a flow rate of powder to the mixing chamber by regulating the pressure of compressed air which prevails in the powder storage tank, in a pressure range between PI- (0.5. 10 Pa) and P1 + (0.5. 10 Pa) where PI is the pressure of compressed air in the mixing chamber .
Dans un mode de réalisation particulier, la pression d'air comprimé dans la cuve de stockage de poudre est réglée dans une plage comprise entre PI- (0,2 . 10 Pa) et Pl+(0,2 . 10 Pa) .In a particular embodiment, the pressure of compressed air in the powder storage tank is adjusted in a range between PI- (0.2. 10 Pa) and Pl + (0.2. 10 Pa).
D'autres caractéristiques et avantages de l'invention apparaîtront de la description et des dessins annexés qui en représentent un mode de réalisation préférentiel.Other characteristics and advantages of the invention will appear from the description and the appended drawings which represent a preferred embodiment.
Sur ces dessins :In these drawings:
- la figure 1 est une vue partielle en coupe d'un exemple de dispositif selon l'invention, - la figure 2 est un schéma d'un dipositif de projection de particules abrasives conforme à l'invention, et- Figure 1 is a partial sectional view of an example of a device according to the invention, - Figure 2 is a diagram of a device for projecting abrasive particles according to the invention, and
- la figure 3 est un exemple de tête projectrice utilisable dans le dispositif selon l'invention. A la figure 1 on a désigné par *la référence 1 un boitier en matériau synthétique, composé de deux parties 1A et 1B fixées l'une de l'autre, l'ensemble constituant un bloc compact.- Figure 3 is an example of a projecting head usable in the device according to the invention. In FIG. 1, the reference 1 designates a housing made of synthetic material, composed of two parts 1A and 1B fixed to each other, the assembly constituting a compact block.
Comme matériau, il est possible d'utiliser un polyamide tel que celui couramment désigné par la marque déposée "NYLON".As a material, it is possible to use a polyamide such as that commonly designated by the registered trademark "NYLON".
Ce matériau, en effet, possède à la fois de bonnes qualités de résistance à l'abrasion et évite les phénomènes de condensation qui se produisent sur des parois métalliques.This material, in fact, has both good qualities of resistance to abrasion and avoids the phenomena of condensation which occur on metal walls.
Le dispositif 1 comprend un raccord 10 sur lequel s'adapte un embout 11 solidaire d'une cuve de stockage C de la poudre, laquelle est symbolisée par un trait interrompu fort. Cette cuve C est en général soumise à une pression d'air comprimé, comme il sera vu ci-après.The device 1 comprises a connector 10 on which a nozzle 11 is fitted which is integral with a powder storage tank C, which is symbolized by a line interrupted loudly. This tank C is generally subjected to compressed air pressure, as will be seen below.
Le raccord 10 est tubulaire et débouche dans un conduit coaxial 3, appelé conduit d'amenée. II s'agit d'une chambre à paroi tronconique, d'axe vertical, dont l'ouverture de sortie 30 est tournée vers le bas. A l'entrée du conduit 3 est monté un obturateur 2 à commande manuelle au moyen d'un levier 20. A titre indicatif, la paroi tronconique de conduit 3 a un angle au sommet u de l'ordre de 20°.The connector 10 is tubular and opens into a coaxial conduit 3, called the supply conduit. It is a chamber with a frustoconical wall, of vertical axis, the outlet opening 30 of which faces downwards. At the inlet of the conduit 3 is mounted a shutter 2 manually controlled by means of a lever 20. As an indication, the frustoconical wall of the conduit 3 has an angle at the top u of the order of 20 °.
A l'intérieur du conduit 3 sont montées des palettes déflectrices 31 disposées en quinconce et légèrement inclinées dans le sens d'écoulement, par gravité, de la poudre de haut en bas, vers l'orifice de sortie 30. Leur fonction est d'absorber une partie du poids de la masse de poudre en évitant les tassements, et de favoriser l'écoulement des particules.Inside the duct 3 are mounted deflecting vanes 31 arranged in staggered rows and slightly inclined in the direction of flow, by gravity, of the powder from top to bottom, towards the outlet orifice 30. Their function is to absorb part of the weight of the powder mass, avoiding settling, and promote the flow of particles.
A la partie basse du conduit 3 est monté un vibreur 9 à commande pneumatique, dont la fonction - bien connue en soi - est également de favoriser le passage des particules dans la zone de sortie 30, de diamètre le plus petit.At the lower part of the duct 3 is mounted a vibrator 9 with pneumatic control, the function of which - well known per se - is also to encourage the passage of particles in the outlet zone 30, of the smallest diameter.
Cette partie basse du conduit 3 est occupée par un embout tronconique 32 qui peut éventuellement être amovible et interchangeable, auquel cas on peut prévoir une série d'embouts ayant des orifices de sortie 30 plus ou moins fins.This lower part of the duct 3 is occupied by a frustoconical end piece 32 which can optionally be removable and interchangeable, in which case a series of end pieces can be provided with more or less fine outlet orifices 30.
L'orifice de sortie 30 présente un diamètre important en regard du très faible débit d'abrasif projeté, ce diamètre étant compris entre 4 et 20 millimètres, et avantageusement compris entre 8 et 12 millimètres, par exemple égal à 8 millimètres.The outlet orifice 30 has a large diameter opposite the very low flow of projected abrasive, this diameter being between 4 and 20 millimeters, and advantageously between 8 and 12 millimeters, for example equal to 8 millimeters.
A ce niveau débouche un canal 12, 12' destiné à permettre la purge de tout bouchon de poudre susceptible de colmater l'orifice 30. Pour cela, il suffit de mettre ce canal à l'air libre en ouvrant un obturateur 406, ce qui a pour effet de chasser par soufflage le bouchon de poudre, sous l'effet de la pression d'air régnant dans la cuve de stockage C.At this level opens a channel 12, 12 ′ intended to allow the purging of any powder plug capable of clogging the orifice 30. For this, it is sufficient to put this channel in the open air by opening a shutter 406, which has the effect of blowing out the plug powder, under the effect of the air pressure prevailing in the storage tank C.
L'orifice de sortie 30 est sélectivement obturable au moyen d'une vanne 4 du genre papillon, possédant une palette pivotante obturatrice 40 en forme de disque. La vanne 4 est à commande pneumatique. Elle est normalement fermée, et s'ouvre lorsqu'elle est alimentée en air comprimé.The outlet orifice 30 is selectively closable by means of a butterfly-type valve 4, having a pivoting obturator pallet 40 in the form of a disc. Valve 4 is pneumatically operated. It is normally closed, and opens when it is supplied with compressed air.
Le dispositif 1 est pourvu d'un conduit 6 appelé chambre de mélangeage. Il s'agit d'un conduit cylindrique horizontal présentant une zone d'extrémité taraudée 60, pour l'adaptation d'un embout de flexible d'amenée d'air comprimé dans le conduit 6.The device 1 is provided with a conduit 6 called the mixing chamber. It is a horizontal cylindrical duct having a tapped end zone 60, for the adaptation of a hose connector for supplying compressed air into the duct 6.
Ce conduit est situé en-dessous et à l'aplomb de l'orifice de sortie 30, avec lequel il communique par un conduit de transfert 5, incliné vers le bas et vers l'aval si on considère le sens de déplacement du flux d'air comprimé dans le conduit 6.This duct is located below and directly above the outlet orifice 30, with which it communicates by a transfer duct 5, inclined downward and downstream if we consider the direction of movement of the flow d compressed air in line 6.
Ce conduit de transfert peut avoir une forme générale tronconique, avec une section décroissante en direction de la chambre de mélangeage, comme représenté, ou encore il peut avoir une forme cylindrique. De préférence, le conduit de transfert 5 présente, au moins au voisinage de la chambre de mélangeage, une section inférieure à la section de ladite chambre de mélangeage.This transfer duct can have a generally frustoconical shape, with a decreasing section in the direction of the mixing chamber, as shown, or it can have a cylindrical shape. Preferably, the transfer duct 5 has, at least in the vicinity of the mixing chamber, a section smaller than the section of said mixing chamber.
Ces dispositions permettent d'une part de créer uen aspiration dans le conduit de transfert 5 du fait de son inclinaison, et d'autre part, de limiter les turbulences perturbatrices dans ce conduit du fait de sa faible section.These provisions allow on the one hand to create a suction in the transfer duct 5 due to its inclination, and on the other hand, to limit disturbing turbulence in this duct due to its small section.
A la figure 1 on a symbolisé par les flèches FI et F2 respectivement, le déplacement d'une part de la poudre dans le conduit de transfert 5 et d'autre part de l'air comprimé dans le conduit 6. II s'opère donc dans le conduit 6 un mélangeage de la poudre et de l'air. Le conduit 6 débouche par son extrémité aval dans un espace appelé chambre de diffusion.In FIG. 1, the arrows FI and F2 have been symbolized respectively, the movement of the powder on the one hand in the transfer duct 5 and on the other hand the compressed air in the duct 6. It therefore takes place in line 6 a mixture of powder and air. The conduit 6 opens at its downstream end into a space called the diffusion chamber.
Il s'agit d'une chambre composée de deux parties tronconiques 7, 70 coaxiales, d'axe vertical, entre lesquelles est intercalée une grille filtrante 8.It is a chamber made up of two frustoconical parts 7, 70 coaxial, of vertical axis, between which is inserted a filtering grid 8.
La partie basse, et amont 7, diverge vers la grille, tandis que la partie haute, et aval 70, converge à partir de la grille.The lower part, and upstream 7, diverges towards the grid, while the upper part, and downstream 70, converges from the grid.
La grille filtrante est un disque en matériau très résistant à l'abrasion, par exemple en carbure de tungstène, percé d'une pluralité de trous cylindriques 80 de très petit diamètre, néanmoins supérieur aux plus grandes dimensions des particules de poudre.The filter grid is a disc made of a material very resistant to abrasion, for example tungsten carbide, pierced with a plurality of cylindrical holes 80 of very small diameter, nevertheless greater than the largest dimensions of the powder particles.
A titre indicatif, la granulométrie de la poudre est de 0 à 200 micromètres, et les trous 80 ont un damètre compris entre 300 et 800 micromètres pour des buses ayant un diamètre de passage de l'ordre du millimètre.As an indication, the particle size of the powder is from 0 to 200 micrometers, and the holes 80 have a dameter of between 300 and 800 micrometers for nozzles having a passage diameter of the order of a millimeter.
Les flèches G et H symbolisent respectivement l'entrée du mélange air/poudre dans la partie 7 de la chambre de diffusion, et son évacuation hors de la partie 70, via un conduit de sortie 71.The arrows G and H respectively symbolize the entry of the air / powder mixture into part 7 of the diffusion chamber, and its evacuation from part 70, via an outlet conduit 71.
A la sortie du dispositif est monté un manchon de raccordement pourvu d'un obturateur à commande manuelleAt the outlet of the device is mounted a connection sleeve provided with a manually operated shutter
21 et d'un embout 72 de branchement sur un flexible. A la base de la partie 7 est monté un obturateur 22 destiné à purger la chambre de diffusion, à travers un21 and a nozzle 72 for connection to a hose. At the base of the part 7 is mounted a shutter 22 intended to purge the diffusion chamber, through a
"manchon d'évacuation des résidus 73."residue evacuation sleeve 73.
Les dispositifs obturateurs 2, 21 et 22 sont du type boisseau. En fonctionnement, les obturateurs 2 et 21 sont ouverts tandis que l'obturateur 22 est fermé.The shutter devices 2, 21 and 22 are of the plug type. In operation, the shutters 2 and 21 are open while the shutter 22 is closed.
Le conduit 6 est branché en permanence à une source d'air comprimé amenant de l'air sous pression selon F2.The conduit 6 is permanently connected to a source of compressed air supplying pressurized air according to F2.
Lorsqu'on ouvre la vanne 4, la poudre contenue dans la cuve et dans la chambre d'amenée 3 descend dans cette dernière pour tomber dans le conduit de transfert 5, sous l'effet combiné de la gravité, de la pression d'air comprimé dans la chambre de mélangeage 6 et de l'aspiration créée dans le conduit de transfert 5. C'est donc un flux continu de particules qui se mélange au courant d'ait qui passe dans le conduit 6.When the valve 4 is opened, the powder contained in the tank and in the supply chamber 3 descends into the latter to fall into the transfer duct 5, under the combined effect of gravity, of the air pressure compressed in mixing chamber 6 and the suction created in the transfer duct 5. It is therefore a continuous flow of particles which mixes with the current of ai which passes in the duct 6.
Le mélange air/poudre se trouve ensuite diffusé dans la partie de chambre divergente 7.The air / powder mixture is then diffused in the divergent chamber part 7.
Dans cette partie 7 se trouve une masse de particules en suspension, dont une partie traverse les trous 80, tandis que le reste vient buter contre la grille 8 pour être reprise par le flux d'air, jusqu'à ce que les particules arrivent à passer par l'un des trous 80 de la grille.In this part 7 is a mass of suspended particles, part of which passes through the holes 80, while the rest abuts against the grid 8 to be taken up by the air flow, until the particles arrive at go through one of the holes 80 in the grid.
A la sortie de la grille on a donc une répartition spatiale homogène des particules dans le flux d'air, et c'est un flux régulier et tamisé qui sort par le conduit de sortie 71, le tamisage empêchant le colmatage des buses très fines de la tête projectrice 106.At the outlet of the grid, there is therefore a homogeneous spatial distribution of the particles in the air flow, and it is a regular and screened flow which leaves through the outlet duct 71, the screening preventing clogging of the very fine nozzles of the head 106.
Comme déjà dit, les déflecteurs limitent le tassement de la poudre dans le conduit convergent 3, tandis que le vibreur 9 favorise l'écoulement des particules dans la partie rétrécie 30.As already said, the deflectors limit the packing of the powder in the converging conduit 3, while the vibrator 9 promotes the flow of the particles in the narrowed part 30.
Il est possible d'arrêter l'arrivée des particules de poudre en pilotant la vanne 4 dans sa position de fermeture. Dans ce cas, l'air continue à circuler dans le conduit 6 et dans la chambre 7, 70, ce qui permet d'éliminer les particules restantes,* et de purger les conduits, y compris dans l'appareil utilisateur, lequel est alors alimenté en air comprimé uniquement.It is possible to stop the arrival of the powder particles by controlling the valve 4 in its closed position. In this case, the air continues to circulate in the duct 6 and in the chamber 7, 70, which makes it possible to eliminate the remaining particles, * and to purge the ducts, including in the user apparatus, which is then supplied with compressed air only.
Le canal 12, 12* permet de purger la base du conduit d'amenée 3 après l'utilisation. Enfin, par ouverture de l'obturateur 22, et fermeture de l'obturateur 21 tout en maintenant l'arrivée d'air comprimé dans la chambre de mélangeage 6, on peut purger la chambre de diffusion de l'ensemble de ses résidus, normalement des grosses particules, incapables de franchir la grille filtrante 8 et on décolle également de la grille les particules qui s'y seraient agglomérées en bouchant certains des trous 80. A la figure 2 on a représenté une installation utilisant le dispositif 1 qui vient d'être décrit, représenté symboliquement par un contour rectangulaire en traits interrompus. II s'agit d'une installation de décapage d'une surface, par exemple d'une façade de bâtiment, par projection de particules abrasives au moyen d'une tête projectrice 106. Celle-ci est entrainée en rotation par un moteur pneumatique 105, par l'intermédiaire d'un mécanisme de transmission de mouvement 300.The channel 12, 12 * makes it possible to purge the base of the supply duct 3 after use. Finally, by opening the shutter 22, and closing the shutter 21 while maintaining the arrival of compressed air in the mixing chamber 6, it is possible to purge the diffusion chamber of all of its residues, normally large particles, incapable of crossing the filtering grid 8 and the particles which would have agglomerated therein are also detached from the grid by blocking some of the holes 80. In Figure 2 there is shown an installation using the device 1 which has just been described, symbolically represented by a rectangular outline in broken lines. It is an installation for stripping a surface, for example of a building facade, by projection of abrasive particles by means of a projecting head 106. The latter is rotated by a pneumatic motor 105 , via a motion transmission mechanism 300.
Cette installation de nettoyage peut avantageusement être du type de celle décrite dans le document WO- 93/11908, dont le contenu est incorporé ici par référence. La tête projectrice 106 comporte une multitude de buses 106a de faible diamètre, comme on peut le voir sur la figure 3. Ces buses ont de préférence un diamètre compris entre 400 micromètres et 4 millimètres et de préférence, compris entre 400 micromètres et 2 millimètres, par exemple compris entre 400 micromètres et un millimètre.This cleaning installation can advantageously be of the type described in document WO-93/11908, the content of which is incorporated here by reference. The projecting head 106 comprises a multitude of nozzles 106a of small diameter, as can be seen in FIG. 3. These nozzles preferably have a diameter between 400 micrometers and 4 millimeters and preferably, between 400 micrometers and 2 millimeters, for example between 400 micrometers and one millimeter.
Le nombre de buses compris par la tête projectrice 106 peut être d'une dizaine à plusieurs dizaines, par exemple de 10 à 500 buses, et avantageusement, de 20 à 80 buses, par exemple de 24 buses.The number of nozzles included by the spray head 106 can be from ten to several tens, for example from 10 to 500 nozzles, and advantageously from 20 to 80 nozzles, for example from 24 nozzles.
Le compresseur 100 et le dispositif 1 sont normalement à poste fixe, tandis que l'appareil 106 est mobile. Son alimentation en air comprimé se fait donc par des conduits souples. Ainsi, la tête rotative 106 est alimentée en mélange air/poudre par le dispositif 1 au moyen d'un tuyau flexible 206 branché sur le raccord 72.The compressor 100 and the device 1 are normally stationary, while the device 106 is mobile. Its supply of compressed air is therefore through flexible conduits. Thus, the rotary head 106 is supplied with an air / powder mixture by the device 1 by means of a flexible pipe 206 connected to the connector 72.
Le dispositif 1 reçoit de l'air comprimé d'un compresseur 100 par l'intermédiaire d'une canalisation 204 branchée sur la portion filetée 60 du conduit de mélangeage 6.The device 1 receives compressed air from a compressor 100 via a pipe 204 connected to the threaded portion 60 of the mixing duct 6.
Sur la canalisation 204 est montée une vanne de fermeture 107, laquelle est ouverte en cours de travail. Sur la canalisation 204 est également monté un détendeur 400 de réglage de pression associé à un manomètre 401 pour contrôler la pression d'air comprimé à l'aval du détendeur 400. La cuve C de stockage de poudre est reliée à la source 100 d'air comprimé par un conduit 402 qui présente également un détendeur 403 de réglage de pression associé à un manomètre 404 qui permet de contrôler la pression à l'aval du détendeur 403. On peut ainsi régler la pression d'air comprimé dans la cuve C de stockage de poudre, comme cela est connu du document FR-A-2 577 457, dans un contexte différent.On the line 204 is mounted a closing valve 107, which is opened during work. On the line 204 is also mounted a pressure regulator 400 for pressure adjustment associated with a pressure gauge 401 to control the pressure of compressed air downstream of the regulator 400. The powder storage tank C is connected to the source 100 of compressed air through a duct 402 which also has a pressure regulator 403 associated with a pressure gauge 404 which makes it possible to control the pressure downstream of the regulator 403. It is thus possible to regulate the pressure of compressed air in the tank C of powder storage, as is known from document FR-A-2 577 457, in a different context.
Le conduit 402 peut en outre comporter une vanne de fermeture 405, ouverte en cours de travail. Le moteur pneumatique 105 est alimenté à partir du compresseur 100 par des canalisations flexibles successives 200, 201, 203. Sur la partie 200 se trouve une vanne de fermeture 101 et un diviseur de débit 102. Entre les parties 201 et 203 se trouve une vanne de commande 103 qui est actionnée par une petite vanne de pilotage 104; cette dernière est actionnée par une gâchette 104a portée par une partie non rotative d'un appareil qui comprend la tête rotative 106, cette gâchette étant manoeuvrable par l'opérateur.The conduit 402 may also include a shut-off valve 405, open during work. The pneumatic motor 105 is supplied from the compressor 100 by successive flexible pipes 200, 201, 203. On the part 200 is a closing valve 101 and a flow divider 102. Between the parts 201 and 203 is a valve control 103 which is actuated by a small pilot valve 104; the latter is actuated by a trigger 104a carried by a non-rotating part of an apparatus which comprises the rotary head 106, this trigger being maneuverable by the operator.
L'actionnement de la vanne de commande 103 se fait par un conduit d'amenée d'air comprimé 202 provenant du diviseur 102, via la vanne de pilotage 104. La vanne 103 est une vanne à actionnement pneumatique normalement fermée; elle passe à l'état ouvert lorque la vanne pilote 104 est ouverte.The actuation of the control valve 103 is done by a compressed air supply duct 202 coming from the divider 102, via the pilot valve 104. The valve 103 is a pneumatically actuated valve normally closed; it changes to the open state when the pilot valve 104 is open.
Enfin la partie 203, située en aval de la vanne de commande 103, est branchée respectivement par des conduits 207 et 208 respectivement au vibreur 9 et à la vanne d'obturation 4. Les conduits 207 et 203 portent des vannes à étranglement variable respectivement 109 et 110, permettant un réglage des débits.Finally the part 203, located downstream of the control valve 103, is connected respectively by conduits 207 and 208 respectively to the vibrator 9 and to the shut-off valve 4. The conduits 207 and 203 carry valves with variable throttle respectively 109 and 110, allowing adjustment of the flow rates.
En vue d'une opération de nettoyage, les vannes 101 et 107 sont ouvertes et le compresseur est mis en marche. Ainsi, de l'air comprimé arrive en permanence dans l'appareil, via la canalisation 204, le dispositif 1, et le flexible 206.For a cleaning operation, the valves 101 and 107 are open and the compressor is started. Thus, compressed air constantly arrives in the device, via the line 204, the device 1, and the flexible pipe 206.
Tant que l'opérateur n'actionne pas la gâchette 104a, la vanne pilote 104 est fermée, et n'actionne pas la vanne de commande 103, laquelle est aussi par conséquent fermée (positions de la figure 2) .As long as the operator does not actuate the trigger 104a, the pilot valve 104 is closed, and does not actuate the control valve 103, which is also consequently closed (positions of FIG. 2).
Lorsque l'opérateur actionne la gâchette 104a, il fait basculer la vanne pilote 104 en position ouverte, et de l'air comprimé arrive via la canalisation 202, à la vanne 103. Celle-ci s'ouvre et de l'air comprimé arrive du compresseur via les canalisations 200 et 201 dans le conduit 203.When the operator actuates the trigger 104a, he switches the pilot valve 104 to the open position, and compressed air arrives via the pipe 202, at the valve 103. The latter opens and compressed air arrives of the compressor via pipes 200 and 201 in duct 203.
On a alors une alimentation en air comprimé du vibreur 9, qui se met en mouvement, de la vanne 4 qui passe à l'état ouvert et du moteur 105, qui fait tourner la tête rotative 106.There is then a supply of compressed air to the vibrator 9, which starts to move, to the valve 4 which passes to the open state and to the motor 105, which rotates the rotary head 106.
On obtient alors une distribution de mélange air/poudre par le dispositif 1, et l'opérateur procède au nettoyage de la façade, en déplaçant l'appareil de projection le long de celle-ci.An air / powder mixture distribution is then obtained by the device 1, and the operator cleans the facade, by moving the projection apparatus along the latter.
Lorsque l'opérateur souhaite arrêter ce travail, il lui suffit de relâcher la gâchette 104a pour automatiquement arrêter 1'entraînement en rotation de la tête, arrêter le vibreur, et arrêter l'arrivée de poudre (par fermeture de la vanne 4) . L'air comprimé continue à être fourni, ce qui permet de purger les canalisations et les buses.When the operator wishes to stop this work, he only has to release the trigger 104a to automatically stop the drive in rotation of the head, stop the vibrator, and stop the powder supply (by closing the valve 4). Compressed air continues to be supplied, allowing the pipes and nozzles to be purged.
A titre indicatif, la section de passage rétrécie 30 a un diamètre de l'ordre de 8 millimètres, le conduit de transfert 5 à un diamètre de l'ordre de 8 millimètres au moins à son extrémité d'aval, le conduit de mélangeage 6 et le conduit de sortie 71 ont un diamètre de 12 millimètre, tandis que le disque 8 a un diamètre de 50 millimètres.As an indication, the narrowed passage section 30 has a diameter of the order of 8 millimeters, the transfer duct 5 has a diameter of the order of at least 8 millimeters at its downstream end, the mixing duct 6 and the outlet conduit 71 have a diameter of 12 millimeters, while the disc 8 has a diameter of 50 millimeters.
La pression de l'air comprimé fourni par le compresseur 100 est comprise par exemple entre 2 et 10 bars (soit 2 . 10 et 10 Pa) , notamment entre 5 et 10 bars.The pressure of the compressed air supplied by the compressor 100 is for example between 2 and 10 bars (i.e. 2. 10 and 10 Pa), in particular between 5 and 10 bars.
Le détendeur réglable 400 est réglé sur une valeur déterminée de la pression PI d'air comprimé régnant à son aval, cette pression étant mesurée au moyen d'un manomètre 401. Cette pression mesurée est voisine de la pression d'air comprimé qui règne dans la chambre mélangeage 6, du fait qu'il existe peu de pertes de charge entre le détendeur 400 et la chambre de mélangeage 6.The adjustable pressure regulator 400 is adjusted to a determined value of the pressure of compressed air PI prevailing downstream, this pressure being measured by means of a pressure gauge 401. This measured pressure is close to the compressed air pressure prevailing in the mixing chamber 6, owing to the fact that there is little pressure drop between the pressure reducer 400 and the mixing chamber 6.
Cette pression PI est réglée en particulier en fonction de la force du jeu d'air comprimé que l'on souhaite obtenir en sortie de la tête projectrice 106. La pression PI pourrait être par exemple de l'ordre de 4 bars, soit 4 . 10 Pa. Le débit permanent d'air comprimé peut être alors d'environ 1500 à 2500 1 /minute, suivant la taille et le nombre des buses 106a. On peut avoir par exemple un débit de 1500 1/minute pour 24 buses ayant chacune un diamètre de passage de 1 millimètre, et de 2300 1/minute pour 24 buses de 1,2 millimètres.This pressure PI is adjusted in particular as a function of the force of the set of compressed air which it is desired to obtain at the outlet of the projecting head 106. The pressure PI could for example be of the order of 4 bars, ie 4. 10 Pa. The permanent flow of compressed air can then be approximately 1500 to 2500 l / minute, depending on the size and the number of nozzles 106a. One can have for example a flow rate of 1500 l / minute for 24 nozzles each having a passage diameter of 1 millimeter, and 2300 l / minute for 24 nozzles of 1.2 mm.
Une fois la pression PI réglée, il est possible, malgré l'absence de vis-pointeau de réglage de la section de l'orifice de sortie 30 et malgré le diamètre important de cet orifice, d'ajuster très finement le débit de poudre qui arrive dans la chambre dé* mélangeage 6 en réglant la pression P2 d'air comprimé qui règne dans la cuve C de stockage, au moyen du détendeur réglable 403, en créant un différentiel de pression de quelques dizaines ou centaines de grammes (hectopascals) entre PI et P2.Once the pressure PI has been adjusted, it is possible, despite the absence of a needle-screw for adjusting the section of the outlet orifice 30 and despite the large diameter of this orifice, to very finely adjust the powder flow which enters the mixing chamber * 6 by adjusting the pressure P2 of compressed air prevailing in the vessel C storage by means of the adjustable pressure regulator 403, by creating a pressure differential some tens or hundreds of grams (hectopascals) between PI and P2.
Par exemple, la pression P2 pourrait être réglée dans une plage qui s'étend entre Pl-0,5 bars à Pl+0,5 bars, soit entre PI- (0,5 . 10 Pa) et Pl+(0,5 . 10 Pa) , ou avantageusement entre Pl-0,2 bars et Pl+0,2 bars, soit Pl-(0,2 . 10 Pa) et Pl+(0,2 . 10 Pa) .For example, the pressure P2 could be adjusted in a range which extends between Pl-0.5 bars to Pl + 0.5 bars, that is to say between PI- (0.5. 10 Pa) and Pl + (0.5. 10 Pa), or advantageously between Pl-0.2 bars and Pl + 0.2 bars, ie Pl- (0.2. 10 Pa) and Pl + (0.2. 10 Pa).
Lorsque la pression PI est de l'ordre de 4 bars, soit 4 . 10 Pa, la pression P2 peut ainsi être réglée entre par exemple 3,8 et 4,2 bars, soit 3,8 . 10 Pa à 4,2 . 10 Pa. On parvient ainsi à régler le débit de poudre dans une plage allant d'environ 120 à 140 g/minute pour une pression P2 de l'ordre de 3,8 bars, jusqu'à 500 à 700 g/minute pour une pression P2 de l'ordre de 4,2 bars et ce, avec un diamètre de 8 millimètres pour l'ouverture de sortie 30.When the pressure PI is of the order of 4 bars, i.e. 4. 10 Pa, the pressure P2 can thus be adjusted between, for example 3.8 and 4.2 bars, ie 3.8. 10 Pa to 4.2. 10 Pa. It is thus possible to regulate the powder flow rate in a range from approximately 120 to 140 g / minute for a pressure P2 of the order of 3.8 bars, up to 500 to 700 g / minute for a pressure P2 of the order of 4.2 bars, with a diameter of 8 millimeters for the outlet opening 30.
Grâce au réglage du différentiel de pression entre la cuve C de stockage de poudre et la chambre de mélangeage 6, en combinaison avec la conformation particulière du conduit de transfert 5 qui engendre une aspiration dans ce conduit de transfert lorsque la chambre de mélangeage 6 est parcourue par un flux d'air comprimé, le dispositif qui vient d'être décrit permet donc un dosage régulier et précis de la poudre dans le flux continu d'air comprimé, et ce, sans avoir recours à un pointeau à vis ou à d'autres moyens d'étranglement de l'orifice de sortie 30 du conduit d'amenée de poudre, qui sont sujets à une usure rapide et ne permettent pas d'obtenir une précision et une régularité de dosage équivalentes. Thanks to the adjustment of the pressure differential between the powder storage tank C and the mixing chamber 6, in combination with the particular configuration of the transfer duct 5 which generates suction in this transfer duct when the mixing chamber 6 is traversed by a flow of compressed air, the device which has just been described therefore allows a regular and precise metering of the powder in the continuous flow of compressed air, and this, without resorting to a screw needle or to other means of throttling the outlet orifice 30 of the powder supply duct, which are subject to rapid wear and do not allow an equivalent metering precision and regularity to be obtained.

Claims

R E V E N D I C A T I O N S
1. Dispositif de décapage par projection d'un mélange d'air comprimé et de poudre abrasive, comprenant1. Stripping device by spraying a mixture of compressed air and abrasive powder, comprising
- une source (100) d'air comprimé,- a source (100) of compressed air,
- une cuve (C) de stockage de poudre, - une tête projectrice (106) pour projeter le mélange d'air comprimé et de poudre abrasive de très fine granulométrie (0 à 200 micromètres) vers une surface à décaper,- a powder storage tank (C), - a projecting head (106) for projecting the mixture of compressed air and abrasive powder of very fine particle size (0 to 200 micrometers) towards a surface to be stripped,
- un conduit d'air comprimé (204, 6, 7, 70, 71, 206) reliant la source (100) d'air comprimé) à la tête projectrice (106), ce conduit comprenant, d'amont en aval, un conduit d'amenée (204) d'air comprimé, une chambre de mélangeage (6) et un conduit d'évacuation (7, 70, 71, 206), - un conduit (3) d'amenée de poudre à parois convergentes, présentant un orifice de sortie (30) étroit et un orifice d'entrée plus large qui communique avec la cuve (C) de stockage de poudre, l'orifice de sortie communiquant avec la chambre de mélangeage (6) par l'intermédiaire d'une vanne (4) de contrôle de poudre susceptible d'occuper sélectivement une position fermée, où elle obture ledit orifice de sortie, et une position ouverte,- a compressed air duct (204, 6, 7, 70, 71, 206) connecting the source (100) of compressed air) to the spray head (106), this duct comprising, from upstream to downstream, a compressed air supply pipe (204), a mixing chamber (6) and a discharge pipe (7, 70, 71, 206), - a powder supply pipe (3) with converging walls, having a narrow outlet (30) and a wider inlet which communicates with the powder storage tank (C), the outlet communicates with the mixing chamber (6) via a powder control valve (4) capable of selectively occupying a closed position, where it closes said outlet orifice, and an open position,
- et des moyens de commande (104, 104a) actionnables depuis le voisinage de la tête projectrice (106) pour commander la vanne (4) de contrôle de poudre,- and control means (104, 104a) actuable from the vicinity of the spray head (106) to control the powder control valve (4),
- un disque de projection pourvu d'un ensemble de buses (106a) de très fins diamètres ayant une section comprise entre 400 micromètres et 4 millimètres, caractérisé en ce que les très fines sections de passage des buses (106a) du disque de projection (106) sont sans cesse dégagées par pression d'air comprimé. Cette pression constante d'air comprimé se faisant par l'intermédiaire du conduit d'air comprimé (204, 6, 7, 70, 71, 206) indépendamment de 1 'actionnement des moyens de commande (104, 104a) et indépendamment de la position de la vanne (4) de contrôle d'abrasif.- a projection disc provided with a set of nozzles (106a) of very fine diameters having a section of between 400 micrometers and 4 millimeters, characterized in that the very fine passage sections of the nozzles (106a) of the projection disc ( 106) are constantly released by compressed air pressure. This constant pressure of compressed air taking place via the compressed air duct (204, 6, 7, 70, 71, 206) independently of the actuation of the control means (104, 104a) and independently of the position of the abrasive control valve (4).
2. Dispositif selon la revendication 1, dans lequel le conduit d'amenée d'air comprimé (204) comporte un premier moyen de réglage de pression (400) et dans lequel la cuve (C) de stockage de poudre communique avec la source (100) d'air comprimé par l'intermédiaire d'un conduit (402) qui présente un deuxième moyen de réglage de pression (403) distinct du premier, l'air comprimé présentant ainsi des pressions (PI, P2) réglables indépendamment l'une de l'autre respectivement dans la chambre de mélangeage (6) et dans la cuve (C) de stockage de poudre. 2. Device according to claim 1, in which the compressed air supply duct (204) comprises a first pressure adjustment means (400) and in which the powder storage tank (C) communicates with the source ( 100) of compressed air via a conduit (402) which has a second pressure adjustment means (403) distinct from the first, the compressed air thus having pressures (PI, P2) independently adjustable one from the other respectively in the mixing chamber (6) and in the powder storage tank (C).
3. Dispositif selon la revendication 2, dans lequel la vanne (4) de contrôle de poudre communique avec la chambre de mélangeage (6) par l'intermédiaire d'un conduit de transfert (5) incliné vers l'aval par rapport à la chambre de mélangeage (6) . 3. Device according to claim 2, in which the powder control valve (4) communicates with the mixing chamber (6) via a transfer duct (5) inclined downstream relative to the mixing chamber (6).
4. Dispositif selon la revendication 3, dans lequel le conduit de transfert (5) présente, au moins au voisinage de la chambre de mélangeage (6), une section inférieure à la section de ladite chambre de mélangeage.4. Device according to claim 3, wherein the transfer duct (5) has, at least in the vicinity of the mixing chamber (6), a section smaller than the section of said mixing chamber.
5. Dispositif selon la revendication, dans lequel la vanne (4) de contrôle de poudre communique avec la chambre de mélangeage (6) par l'intermédiaire d'un conduit de transfert (5) , ce conduit de transfert et la chambre de mélangeage étant conformés pour qu'un flux d'air comprimé dans la chambre de mélangeage, en provenance de la source d'air comprimé, créé une aspiration dans le conduit de transfert (5) .5. Device according to claim, in which the valve (4) for controlling powder communicates with the mixing chamber (6) via a transfer duct (5), this transfer duct and the mixing chamber being shaped so that a flow of compressed air in the mixing chamber, coming from the source of compressed air, creates a suction in the transfer duct (5).
6. Dispositif selon l'une quelconque des revendications précédentes, dans lequel la vanne (4) de contrôle de poudre est commandée par un actionneur pneumatique alimenté en air comprimé depuis la source (100) d'air comprimé, et dans lequel les moyens de commande (104, 104a) comportent une gâchette unique (104a) disposée au voisinage de la tête projectrice (106) pour actionner une vanne pilote (104) qui commande l'alimentation en air comprimé de l'actionneur pneumatique de la vanne (4) de contrôle de poudre.6. Device according to any one of the preceding claims, in which the powder control valve (4) is controlled by a pneumatic actuator supplied with compressed air from the source (100) of compressed air, and in which the means for control (104, 104a) comprise a single trigger (104a) arranged in the vicinity of the projecting head (106) to actuate a pilot valve (104) which controls the supply of compressed air to the pneumatic actuator of the powder control valve (4).
7. Dispositif selon la revendication 6, dans lequel la tête projectrice (106) est entrainée en rotation par un moteur pneumatique (105) alimenté en air comprimé depuis la source (100) d'air comprimé, et dans lequel la vanne pilote (104) commande également l'alimentation en air comprimé du moteur pneumatique (105) . 7. Device according to claim 6, in which the projecting head (106) is rotated by a pneumatic motor (105) supplied with compressed air from the source (100) of compressed air, and in which the pilot valve (104 ) also controls the supply of compressed air to the pneumatic motor (105).
8. Dispositif selon l'une quelconque des revendications 6 et 7, dans lequel un vibreur pneumatique8. Device according to any one of claims 6 and 7, wherein a pneumatic vibrator
(9) est monté sur le conduit d'amenée de la poudre (3) pour lui communiquer des vibrations, ce vibreur étant alimenté en air comprimé depuis la source (100) d'air comprimé, et dans lequel la vanne pilote (104) commande également l'alimentation en air comprimé du vibreur pneumatique (9) .(9) is mounted on the powder supply pipe (3) to communicate vibrations to it, this vibrator being supplied with compressed air from the source (100) of compressed air, and in which the pilot valve (104) also controls the supply of compressed air to the pneumatic vibrator (9).
9. Dispositif selon l'une quelconque des revendications précédentes, dans lequel le conduit d'évacuation (7, 70, 71, 206) comporte une chambre de diffusion (7, 70) qui est obturée par une grille filtrante (8) présentant une surface relativement grande et pourvue d'une multitude de trous de passage (80) qui présentent une faible section, légèrement inférieure à une section correspondant au diamètre de passage des buses de la tête projectrice et légèrement supérieure à une section correspondant, à la granulométrie de la poudre, le conduit d'évacuation (7, 70, 71, 206) présentant une section moyenne inférieure à la surface de la grille filtrante (8) .9. Device according to any one of the preceding claims, in which the discharge duct (7, 70, 71, 206) comprises a diffusion chamber (7, 70) which is closed by a filtering grid (8) having a relatively large surface and provided with a multitude of passage holes (80) which have a small section, slightly less than a section corresponding to the diameter of passage of the nozzles of the projector head and slightly greater than a section corresponding to the particle size of the powder, the discharge conduit (7, 70, 71, 206) having an average section smaller than the surface of the filtering grid (8).
10. Dispositif selon la revendication 9, dans lequel les trous de passage (80) de la grille filtrante présentent un diamètre compris entre 300 micromètres et 2 millimètres pour des buses (106a) de la tête projectrice ayant un diamètre de passage compris entre 400 micromètres et 4 millimètres.10. Device according to claim 9, in which the passage holes (80) of the filter grid have a diameter between 300 micrometers and 2 millimeters for nozzles (106a) of the projecting head having a passage diameter between 400 micrometers and 4 millimeters.
11. Dispositif selon l'une quelconque des revendications 9 et 10, dans lequel la chambre de diffusion est composée de deux parties (7, 70) coaxiales, à parois tronconiques, savoir une partie divergente (7) en amont de la grille, et une partie convergente (70) en aval de la grille. 11. Device according to any one of claims 9 and 10, in which the diffusion is composed of two coaxial parts (7, 70), with frustoconical walls, namely a divergent part (7) upstream of the grid, and a convergent part (70) downstream of the grid.
12. Dispositif selon la revendication 11, dans lequel la partie divergente (7) de la chambre de diffusion (7, 70) présente un axe sensiblement vertical et diverge à partir d'un orifice de purge (73) formant une portion inférieure de ladite chambre divergente, cet orifice de purge étant équipé d'un obturateur (22) .12. Device according to claim 11, wherein the divergent part (7) of the diffusion chamber (7, 70) has a substantially vertical axis and diverges from a purge orifice (73) forming a lower portion of said divergent chamber, this drain orifice being equipped with a shutter (22).
13. Dispositif selon la revendication 12, dans lequel un obturateur (21) est également monté en aval de la partie convergente (70) de la chambre de diffusion (7, 70), pour obturer le conduit d'évacuation. 13. Device according to claim 12, in which a shutter (21) is also mounted downstream of the converging part (70) of the diffusion chamber (7, 70), for closing the evacuation duct.
14. Dispositif selon l'une quelconque des revendications précédentes, dans lequel le conduit (3) d'amenée de poudre, la chambre de mélangeage (6) et la chambre de diffusion (7, 70) sont formés dans un boitier14. Device according to any one of the preceding claims, in which the conduit (3) for supplying powder, the mixing chamber (6) and the diffusion chamber (7, 70) are formed in a housing.
(1) en matériau synthétique. (1) made of synthetic material.
15. Dispositif selon la revendication 14, dans lequel le matériau synthétique est un polyamide.15. Device according to claim 14, in which the synthetic material is a polyamide.
16. Dispositif selon l'une quelconque des revendications précédentes, dans lequel le conduit d'amenée de poudre (3) est sensiblement vertical, avec son orifice de sortie (30) dirigé vers le bas, et est muni de déflecteurs (31) limitant le tassement de la poudre.16. Device according to any one of the preceding claims, in which the powder supply duct (3) is substantially vertical, with its outlet orifice (30) directed downwards, and is provided with deflectors (31) limiting the packing of the powder.
17. Dispositif selon l'une quelconque des revendications précédentes, dans lequel l'orifice de sortie (30) du conduit (3) d'amenée de poudre présente un diamètre compris entre 4 et 20 millimètres.17. Device according to any one of the preceding claims, in which the outlet orifice (30) of the conduit (3) for supplying powder has a diameter of between 4 and 20 millimeters.
18. Dispositif selon l'une quelconque des revendications précédentes, dans lequel la vanne (4) de contrôle de poudre est une vanne papillon dotée d'une palette pivotante obturatrice (40) .18. Device according to any one of the preceding claims, in which the valve (4) for controlling the powder is a butterfly valve provided with a pivoting shutter blade (40).
19. Dispositif selon l'une quelconque des revendications précédentes, dans lequel la cuve (C) de stockage de poudre communique avec la source (100) d'air comprimé et dans lequel le conduit (3) d'amenée de poudre présente, au voisinage de son orifice de sortie (30), un passage (12, 12') de mise à l'air libre équipé d'un obturateur (406) . 19. Device according to any one of the preceding claims, in which the powder storage tank (C) communicates with the air source (100) compressed and in which the powder supply conduit (3) has, in the vicinity of its outlet orifice (30), a passage (12, 12 ') for venting equipped with a shutter (406) .
20. Dispositif selon l'une quelconque des revendications précédentes, dans lequel :20. Device according to any one of the preceding claims, in which:
- le conP it" (3) d'amenée de poudre présente une paroi sensiblement tronconique,the conP it " (3) for supplying powder has a substantially frustoconical wall,
- la vanne (4) de conduit de contrôle de poudre communique avec la chambre de mélangeage (6) par l'intermédiaire d'un conduit de transfert (5),- the powder control pipe valve (4) communicates with the mixing chamber (6) via a transfer pipe (5),
- et le conduit d'évacuation (7, 70, 71, 206) comporte une chambre de diffusion (7, 70) disposée en amont d'un conduit de sortie (71, 206), cette chambre de diffusion étant obturée par une grille filtrante (8) pourvue d'une multitude de trous (80) de passage de faible section, légèrement supérieure à la section correspondant à la granulométrie de la poudre.- And the evacuation duct (7, 70, 71, 206) comprises a diffusion chamber (7, 70) disposed upstream of an outlet duct (71, 206), this diffusion chamber being closed by a grid filter (8) provided with a multitude of holes (80) for passage of small section, slightly greater than the section corresponding to the particle size of the powder.
21. Dispositif selon l'une quelconque des revendications précédentes, dans lequel le diamètre de passage des buses (106a) de la tête projectrice est compris entre 400 micromètres et 2 millimètres.21. Device according to any one of the preceding claims, in which the diameter of passage of the nozzles (106a) of the projecting head is between 400 micrometers and 2 millimeters.
22. Procédé de décapage par projection d'un mélange d'air comprimé et de poudre abrasive au moyen d'un dispositif selon la revendication 2, cdmprenant une étape de régler un débit d'écoulement de poudre vers la chambre de mélangeage (6) en réglant la pression P2) d'air comprimé qui règne dans la cuve (C) de stockage de poudre, dans une plage de pression comprise entre PI- (0,5 • 10 Pa) et Pl+(0,5 . 10 Pa) où PI est la pression d'air comprimé dans la chambre de mélangeage (6) .22. Method of etching by spraying a mixture of compressed air and abrasive powder by means of a device according to claim 2, including a step of regulating a flow rate of powder towards the mixing chamber (6) by adjusting the pressure P2) of compressed air prevailing in the powder storage tank (C), in a pressure range between PI- (0.5 • 10 Pa) and Pl + (0.5. 10 Pa) where PI is the pressure of compressed air in the mixing chamber (6).
23. Procédé selon la revendication 22, dans lequel la pression (P2) d'air comprimé dans la cuve (C) de stockage de poudre est réglée dans une plage comprise entre Pl-(0,2 . 10 Pa) et Pl+(0,2 . 10 Pa) . 23. The method of claim 22, wherein the pressure (P2) of compressed air in the powder storage tank (C) is adjusted within a range between Pl- (0.2. 10 Pa) and Pl + (0 , 2.10 Pa).
PCT/FR1995/000124 1994-02-01 1995-02-01 Method and device for dispensing a mixture of compressed air and powder WO1995021026A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
FR94/01316 1994-02-01
FR9401316A FR2720662B1 (en) 1994-02-01 1994-02-01 Device for dispensing a mixture of compressed air and powder.
FR94/05750 1994-05-10
FR9405750A FR2720663B1 (en) 1994-02-01 1994-05-10 Method and device for dispensing a mixture of compressed air and powder.

Publications (1)

Publication Number Publication Date
WO1995021026A1 true WO1995021026A1 (en) 1995-08-10

Family

ID=26230935

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FR1995/000124 WO1995021026A1 (en) 1994-02-01 1995-02-01 Method and device for dispensing a mixture of compressed air and powder

Country Status (2)

Country Link
FR (1) FR2720663B1 (en)
WO (1) WO1995021026A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008059334A1 (en) * 2008-11-27 2010-06-02 Cgt Cold Gas Technology Gmbh Device for generating and conveying a gas-powder mixture

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI981716A0 (en) * 1998-08-07 1998-08-07 Urho Anttonen Method and apparatus for treating surfaces
EP1762302A3 (en) * 2005-09-09 2009-07-08 Sulzer Metco AG (Switzerland) Powder supply device
US7891315B2 (en) 2005-09-09 2011-02-22 Sulzer Metco Ag Powder supply system

Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR44550E (en) * 1933-01-10 1935-02-19 Improvements in apparatus and process for spraying molten and pulverized bodies and new industrial products resulting therefrom
US2105275A (en) * 1934-02-21 1938-01-11 Spray Engineering Co Flock applying apparatus
US2549033A (en) * 1946-09-11 1951-04-17 Air Reduction Apparatus for feeding powdered material
GB812601A (en) * 1956-01-05 1959-04-29 Frederick William Durden Improvements in or relating to flame spraying apparatus
US3129889A (en) * 1960-09-15 1964-04-21 Powder Melting Corp Apparatus for depositing powdered metals
US3863808A (en) * 1974-01-16 1975-02-04 Volstatic Canada Particulate material conveying apparatus
US3896998A (en) * 1972-09-25 1975-07-29 Volstatic Canada Apparatus for spraying particulate material
US3976332A (en) * 1969-05-26 1976-08-24 Metco, Inc. Powder feed device for flame spray guns
DE2707361A1 (en) * 1977-02-21 1978-08-24 Bischl Johann Powder proportioner with pitot tube extractor unit - is for powder and gas mixt. and has powder and carrier gas mixt. control
DE2949060A1 (en) * 1978-12-27 1980-07-17 Adamovske Strojirny Np Dusting powder metering mechanism - has compressed air inlet and outlet connected by passage through powder hopper
FR2577457A1 (en) * 1985-02-21 1986-08-22 Thomann Michel Device for spraying powder
EP0297463A1 (en) * 1987-07-01 1989-01-04 The Perkin-Elmer Corporation Powder feeding system with a closed loop powder flow regulator and the corresponding method
US4799831A (en) * 1987-06-29 1989-01-24 Dan Ariaz Flowable solid product applicator
DE9107845U1 (en) * 1990-11-15 1992-02-06 Fastje, Ines, 7250 Leonberg Blasting device
EP0533417A1 (en) * 1991-09-16 1993-03-24 Plastic Flamecoat Systems, Inc. Spray coating system and method
WO1993011908A1 (en) * 1991-12-11 1993-06-24 Christian Diat Method for micro-cleaning a support and apparatus for implementing same

Patent Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR44550E (en) * 1933-01-10 1935-02-19 Improvements in apparatus and process for spraying molten and pulverized bodies and new industrial products resulting therefrom
US2105275A (en) * 1934-02-21 1938-01-11 Spray Engineering Co Flock applying apparatus
US2549033A (en) * 1946-09-11 1951-04-17 Air Reduction Apparatus for feeding powdered material
GB812601A (en) * 1956-01-05 1959-04-29 Frederick William Durden Improvements in or relating to flame spraying apparatus
US3129889A (en) * 1960-09-15 1964-04-21 Powder Melting Corp Apparatus for depositing powdered metals
US3976332B1 (en) * 1969-05-26 1986-04-22
US3976332A (en) * 1969-05-26 1976-08-24 Metco, Inc. Powder feed device for flame spray guns
US3896998A (en) * 1972-09-25 1975-07-29 Volstatic Canada Apparatus for spraying particulate material
US3863808A (en) * 1974-01-16 1975-02-04 Volstatic Canada Particulate material conveying apparatus
DE2707361A1 (en) * 1977-02-21 1978-08-24 Bischl Johann Powder proportioner with pitot tube extractor unit - is for powder and gas mixt. and has powder and carrier gas mixt. control
DE2949060A1 (en) * 1978-12-27 1980-07-17 Adamovske Strojirny Np Dusting powder metering mechanism - has compressed air inlet and outlet connected by passage through powder hopper
FR2577457A1 (en) * 1985-02-21 1986-08-22 Thomann Michel Device for spraying powder
US4799831A (en) * 1987-06-29 1989-01-24 Dan Ariaz Flowable solid product applicator
EP0297463A1 (en) * 1987-07-01 1989-01-04 The Perkin-Elmer Corporation Powder feeding system with a closed loop powder flow regulator and the corresponding method
DE9107845U1 (en) * 1990-11-15 1992-02-06 Fastje, Ines, 7250 Leonberg Blasting device
EP0533417A1 (en) * 1991-09-16 1993-03-24 Plastic Flamecoat Systems, Inc. Spray coating system and method
WO1993011908A1 (en) * 1991-12-11 1993-06-24 Christian Diat Method for micro-cleaning a support and apparatus for implementing same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008059334A1 (en) * 2008-11-27 2010-06-02 Cgt Cold Gas Technology Gmbh Device for generating and conveying a gas-powder mixture
US8973523B2 (en) 2008-11-27 2015-03-10 Oerlikon Metco Ag Device for creating and conveying a gas-powder mixture

Also Published As

Publication number Publication date
FR2720663A1 (en) 1995-12-08
FR2720663B1 (en) 1997-08-14

Similar Documents

Publication Publication Date Title
EP0215015B1 (en) Plant for projecting particles of carbon dioxide ice
EP0818245B1 (en) Triboelectric spray gun, installation for spraying coating products and method for controlling such a gun
EP2046504B1 (en) Powder pump with vacuum filling
CA1040238A (en) Apparatus for forming a layer of a pondery substance on the surface of an object
US5421767A (en) Media control valve
CH663964A5 (en) POWDER FEEDING APPARATUS FOR THERMAL SPRAYING DEVICE.
CA2692486A1 (en) Method and device for spraying a pulverulent material into a carrier gas
WO1995021026A1 (en) Method and device for dispensing a mixture of compressed air and powder
CA2175301C (en) Improved pressurization system for abrasive supply pot
US5401205A (en) Media control valve
US5431594A (en) Pressurization system for abrasive supply pot
FR2627709A1 (en) INSTALLATION FOR THERMAL SPRAYING OF POWDER MATERIALS
US4829724A (en) Cutting abrasive feeder, demand type
EP0006073B1 (en) Dose-extractor for pulverized material
FR2720662A1 (en) Cleaner using abrasive particles delivered by compressed air
FR2550957A1 (en) PARTICLE FEEDING DEVICE HAVING RESERVE FEEDING
FR2565877A1 (en) Improvements to Venturi devices, in particular to sandblasting guns
EP2248576B1 (en) Device for mixing powder with a liquid including a dispersal tube
US2125251A (en) Powder blower
FR2522991A1 (en) Pneumatic liquid atomising spray - discharges pulviersation air round discharge orifice to form mixture of liquid and air
FR2483265A1 (en) Internal painting of pipe - uses high speed spiral air current containing drops of paint
EP0719590B1 (en) Apparatus for spraying a mixture of air and liquid
WO2023209308A1 (en) Petroleum coke filling unit and filling method
EP0094307A2 (en) Jet mills
EP0091353B1 (en) Method and apparatus for increasing and realizing heat exchanges on a pulverulent material having a large granulometric distribution

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CA JP US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: CA