GB2505304A

GB2505304A - A drafting mechanism

Info

Publication number: GB2505304A
Application number: GB1312110.8A
Authority: GB
Inventors: Jorg Schmitz; Thomas Schmitz
Original assignee: Truetzschler GmbH and Co KG
Current assignee: Truetzschler GmbH and Co KG
Priority date: 2012-07-18
Filing date: 2013-07-05
Publication date: 2014-02-26
Also published as: GB201312110D0; BR102013018071B8; CH706775B1; BR102013018071B1; DE102012014152A1; CN103572429A; BR102013018071A2; CH706775A2; ITMI20131150A1

Abstract

A drafting mechanism for at least one textile fibre sliver, comprises upper rolls 27 which are loaded onto and arranged into pairs with, lower rolls III, arranged one after another. The upper roll has a resilient roll covering (27.5 , figure 5) which is mounted circumferentially on a basic roll body and which has a nipping region 53 where a fibre sliver or a plurality of fibre slivers are arranged to be nipped between rolls 27 and III. The upper and lower rolls are mounted asymmetrically relative to one another. A roll shaft of the upper or lower roll may be reversibly mounted so that when the covering 27 becomes worn, a roll may be turned so that a different, unworn, portion of the cover 27 defines the nip region. In this way an extended period between upper roll refurbish polishing cycles may be achieved.

Description

Device on a spinning room machine, especially a carding machine, draw frame, combing machine, lap winder or the like, having a drafting mechanism The invention relates to a device on a spinning room machine, especially a carding machine, draw frame, combing machine, lap winder or the like, having a drafting mechanism for at least one textile fibre sliver.

It is known, in a drafting mechanism, to have loading of the upper rolls of the drafting mechanism, the latter comprising roll pairs, arranged one after another, consisting of an upper roll and lower roll, wherein the upper roll has a resilient roll covering which is mounted ciroumferentially on a roll core (basic roll body) . The upper roll further has a nipping region where a fibre sliver or a plurality of fibre slivers are arranged to be nipped in co-operation with the roll nipping body of a lower roll.

In the drafting of fibre slivers in drafting mechanisms, the nipping action of the roll pairs plays a crucial role in the transfer of the drafting forces to the fibre sliver combination. The drafting mechanism roll pairs therefore consist of a fluted steel cylinder, the so-called lower cylinder, and a pressure roller, the so-called upper roll, which is pressed onto the steel cylinder by loading means.

This pressure roller usually has a resilient covering so that there is formed, not a line of nipping, but rather, as a result of the deformation of the resilient covering, an area of nipping, which brings about substantially better fibre retention. Good nipping action is exerted on the fibre sliver combination without damaging the fibres. As shown by experience, soft roll coverings therefore produce better drafting results because the softer the covering, the larger the nipping area. Soft roll coverings have the drawback, however, that they wear very rapidly and, especially in the region where the fibres run through, grooves are formed. This so-called "shrinkage" j eliminated by polishing over the entire covering surface.

This modifies the geometry of the drafting mechanism roll and also, consequently, the properties of the covering, which in turn has a disadvantageous effect on the drafting conditions and, conseguently, the values of the yarn. In addition, re-polishing the roll coverings is a highly onerous procedure.

In practice, upper rolls in drafting mechanisms of spinning room machines (EP 1 870 500 A) are always arranged symmetrically relative to the lower rolls. Following wear on the covering, the upper roll is re-polished. Customary polishing intervals for high-performance draw frames are about 500 hours.

It is an aim of the invention to provide a device of the kind described at the beginning which avoids or mitigates the mentioned disadvantages, which especially makes possible an increased service life for the roll covering and allows an extended period between two polishing cycles.

The invention provides a device on a spinning room machine having a drafting mechanism for at least one textile fibre sliver, the drafting mechanism having a plurality of roll pairs, arranged one after another, comprising an upper roll and lower roll, wherein the upper roll has a resilient roll covering and the lower roll has a roller nipping body, the resilient roll covering of said upper roll having a nipping region where a fibre sliver or a plurality of fibre slivers is arranged to be nipped in co-operation with the roller nipping body of said lower roll, wherein the upper rolls and the lower rolls are arranged asymmetrically relative to one another.

The asymmetrical arrangement of the upper rolls relative to the lower rolls in drafting mechanisms makes it possible to utilise the upper roll covering in two work regions.

This doubles the service life of the covering and also, consequently, the period between two polishing cycles. The invention can be used preferably in those drafting mechanisms which process just one fibre sliver. The invention can also be used advantageously in a drafting mechanism which processes a plurality of fibre slivers.

Advantageously, the upper rolls and the lower rolls of some, but not all, of the drafting roll pairs are arranged at least partly asymmetrically relative to one another.

Instead, the upper rolls and the lower rolls of all the drafting roll pairs may be arranged asymmetrically relative to one another. Advantageously, the upper rolls and the lower rolls are arranged asymmetrically relative to one another in relation to a centre line through the roll nipping body of the lower roll. Advantageously, the roil covering of the upper roll and the roll nipping body of the lower roll are arranged asymmetrically relative to one another. Advantageously, the roll covering and the roll nipping body are arranged offset relative to one another in an axial direction. Advantageously, the roll covering and the roll nipping body are arranged offset relative to one another in an axial direction in relation to a centre line through the roll nipping body. Advantageously, the length of the roll covering of the upper roll that of the roll nipping body of the lower roll are different.

Preferably, the length of the roll covering of the upper roll is greater than the length of the roll nipping body of the lower roll. Advantageously, the shaft (roll neck) carrying the upper roll is reversibly mountable.

Advantageously, the shaft (roll neck) carrying the lower roll is reversibly mountable. Advantageously, at least one roll of a roll pair is so repositionable locally in relation to the respective other roll that the nipping region (path of the at least one fibre sliver) can be changed. Advantageously, the end faces of the roll covering have a spacing of different magnitude from the nipping region before and after mounting in reverse.

Advantageously, the nipping region of the roll covering is formed asymmetrically relative to a plane perpendicular through the roller core. Advantageously, the nipping region is part of a roll covering arranged around the roll core.

Advantageously, the roll covering is made from an elastomer (for example, polyurethane) . Advantageously, the roll covering is mounted on top of an intermediate layer on the roll core. Advantageously, the roll core is of cylindrical construction, preferably of hollow cylindrical construction. Advantageously, the roll body of the upper roll is made of a metallic material, for example steel.

Advantageously, the roll body of the lower roll is made of a metallic material, for example steel. Advantageously, the end faces of the roll covering and of the roll core have spacings of different magnitude from the roll bearings arranged in alignment relative to one another.

In one embodiment, the loading device, for example pneumatic cylinder, of the upper roll is arranged symmetrically relative to the lower rolls and conseguently relative to the nipping region (work region) . PreferabiLy the loading devioe comprises first and second opposed pneumatic cylinders arranged on opposite sides of and equidistantly from the nipping region. Advantageously, the loading force is set the same.

In another embodiment, the loading device, for example pneumatic cylinder, of the upper roll is arranged asymmetrically relative to the lower rolls, but symmetrically relative to the upper rolls and with different loading forces on each cylinder side.

Advantageously, the loading of the bearings is different but is centred between the bearings (ball tracks) In a further embodiment, the loading device is arranged asymmetrically relative to the lower rolls, it being possible to use two different bearing constructions. In that case, the loading force may be set the same.

Advantageously, on turning the rolls, the bearings are arranged to be changed between the roll ends. It is preferred that the position of the upper roll may be reversed whilst the bearings remain in a fixed position, each end of the roll thus being removed from one bearing and connected to the other bearing.

Arrangements in which the loading force is arranged to be set the same are preferred.

Advantageously, the drafting arrangement is a part of a spinning preparation machine that has sliver guiding elements for guiding just one single presented fibre silver and the drafting mechanism being suitable for processing that single fibre sliver.

In some embodiments, the spinning preparation machine has a horizontally arranged drafting mechanism. In other embodiments, the spinning preparation machine has a vertically arranged drafting mechanism. In yet further embodiments, the spinning preparation machine has a drafting mechanism that is inclined at an angle between horizontal and vertical.

The spinning room machine may advantageously be in rhe form of a carding machine/draw frame combination, wherein the fibre sliver produced in the carding machine is supplied directly to the drafting mechanism.

The invention also provides a device on a spinning room machine, especially a carding machine, draw frame, combing machine, lap winder or the like, having a drafting mechanism for at least one textile fibre sliver, having loading of the upper rolls of the drafting mechanism, the latter comprising roll pairs, arranged one after another, consisting of an upper roll and lower roll, wherein the upper roll has a resilient roll covering which is mounted circumferentially on a roll core (basic roll body) and which has a nipping region where a fibre silver or a plurality of fibre slivers are arranged to be nipped in co-operation with the roll nipping body of a lower roll, wherein the upper rolls and the lower rolls are arranged asymmetrically relative to one another.

Certain illustrative embodiments of the invention will be described hereinafter in greater detail with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic side view of a carding machine with a can coiler and a carding machine drafting mechanism, in which a device according to the invention may be used; Fig. 2 is a diagrammatic side view of a detail of the carding machine drafting mechanism according to Fig. 1; Fig. 3 is a diagrammatic side view of the drafting mechanism of a draw frame that may incorporate a device according to the invention; Fig. 4 is a sectional view of a pressure arm coyresponding to section I -I according to Fig. 3 in the unlocked and opened (pivoted-up) position; Fig. 5 is a cross-section through a first embodiment of the invention having an upper roll which rolls on a lower roll, and associated upper roll and lower roll mountings and also loading devices for the upper roll mountings; Fig. 5a shows in cross-section a broken-away end region of the upper roll of Fig. 5, with a roll core, roll neck and roll covering and also a mounting; Fig. 5b is a plan view of the lower roll of Fig. 5, having fluting on the roll nipping body; Figs. 6a, 6b is a front view of the dvice of the fiyst embodiment of the invention, before repositioning (Fig. 6a) and after repositioning (Fig. 6b) Figs. 7a, 7b show a second embodiment of the device according to the invention, having a work region, before repositioning (Fig. 7a) and after repositioning (Fig. 7b); Figs. 8a, Sb show a third embodiment of the device according to the invention, having a (Fig. 8a) and after repositioning (Fig. 8b) Figs. 9a, Sb are schematic views of asymmetrically arranged rolls in a device according to the invention, with used and unused portions of the roll covering, before repositioning (Fig. 9a) and after repositioning (Fig. Sb) Fig. 10 is a diagrammatic view of an asymmetrical arrangement of a shorter upper roll relative to a longer lower roll; Fig. 11 is a diagrammatic view of an asymmetrical arrangement of an upper roll offset axially relative to a lower roll; and Fig. 12 shows, in diagrammatic form, the known, completely symmetrical arrangement of an upper roll relative to a lower roll.

With reference to Fig. 1, a carding machine K, for example a TC 11 carding machine made by Trützschler GmbEi & Co.KG of Nbrichengladbach, Germany has a feed roll 1, feed table 2, lickers-in 3a, 3b, 3c, cylinder 4, doffer 5, stripper roll 6, nip rolls 7, 8, web-guiding element 9, web funnel 10, delivery rolls 11, 12, revolving card top 13 having card top guide rollers and card flats 14, can 15 and can coiler 16. The directions of rotation of the rolls are indicated by curved arrows. Reference letter M denotes the centre (axis) of the cylinder 4. Reference numeral 4a denotes the clothing and reference numeral 4b denotes the direction in which the cylinder 4 rotates. Arrow A denotes the working direction. Located upstream of the carding machine is a flock feeder device 17. The coiling plate 19 is rotatably mounted in the coiling plate panel 18. The coiling plate 19 includes a sliver channel 20 having an inlet 20a and outlet 20b (see Fig. 2) for a fibre sliver and a turntable 21. Arranged between the carding machine K and the coiling plate 19, above the coiling plate 19, is a carding machine drafting mechanism 22, for example a Trhtzschler IDF integrated draw frame. Reference numeral 23 denotes the fibre sliver (carded sliver) to be drafted and reference numeral 23' denotes the drafted fibre sliver.

Referring to Fig. 2, the carding machine drafting mechanism 22 may, by way of illustration, be configured as a 3-over-3 drafting mechanism, that is to say it consists of three lower rolls I, II, III (I output lower roll, II middle lower roll, III input lower roll) and three upper rolls 25, 26, 27. An input measuring funnel 28 is arranged at the inlet to the drafting mechanism 22 and an output measuring funnel 29 is arranged at the outlet from the drafting mechanism 22. Downstream of the output funnel 29 there are arranged two draw-off rolls 30, 31, which rotate in the direction of the curved arrows and draw off the drafted fibre sliver 23' from the output funnel 29. The output lower roll I, the draw-off rolls 30, 31 and the coiling plate 19 are driven by a main motor 32; the input and middle lower rolls III and II are driven by a regulating motor 33. The motors 32 and 33 are connected to an electronic control and regulation device (not shown) The carding machine drafting mechanism 22 shown in Fig. 2 substantially corresponds in construction and function to -10 -the draw frame drafting mechanism S according to Fig. 3.

The carding machine drafting mechanism 22 processes just one carded sliver 23. The pressure arm ha according to Fig. 4 is described below with reference to the drafting mechanism of a draw frame but may also be used in analogous manner in the case of the carding machine drafting mechanism 22 for loading each upper roll 25, 26, 27. Arrow B denotes the working direction of the carding machine drafting mechanism 22.

With reference to Fig. 3, there is provided a drafting mechanism 5, for example that of a ID 08 draw frame made by Trhtzsohler c3mbH & Co.KG. The drafting mechanism S is configured as a 4-over-3 drafting mechanism, that is to say it consists of three lower rolls I, II, III (I output lower roll, II middle lower roll, III input lower roll) and four upper rolls 24, 25, 26, 27. The drafting of the fibre bundle 35, which consists of a plurality of fibre slivers, for example carded slivers 35', is carried out in the drafting mechanism S. The drafting operation is composed of the preliminary drafting operation and the main drafting operation. The roll pairs 27/111 and 26/Il form the preliminary drafting zone and the roll pairs 26/IT and 24,25/I form the main drafting zone. The output lower roll I is driven by the main motor (not shown) and thus determines the delivery speed. The input and middle lower rolls III and II are driven by a regulating motor (not shown) . The upper rolls 24 to 27 are pressed against the lower rolls I, II, III by pressing elements 36a to 36d (loading device) in presser arms 37a to 37d (see Fig. 4), which are pivotable about pivot mountings and are thus driven by frictional engagement. The directions of rotation of the rolls I, IT, III; 24, 25, 26, 27 are indicated by -11 -curved arrows. The fibre sliver combination 35 consisting of a plurality of fibre slivers runs in direction C. The lower rolls I, II, III are mounted in supports 38a, 38b (see Fig. 4), which are arranged on the machine frame 39.

Each of the pressing elements 36a to 36d includes a pneumatic cylinder 47a to 47d (see Fig. 5) , which in each case has a pressure piston 48a to 48d with a pressure rod 49a to 49d which in each case pushes on an upper roll bearing 43 (see Fig. 4) . There is provided a central compressed air line 45, to which there are connected four branch lines 45a to 45d, which lead to the pneumatic cylinders 47a to 47d of the pressing elements 36a to 36d.

The compressed air line 45 is connected to a compressed air source 46. Reference letter pi denotes compressed air.

In the device and shown in Fig. 4, there is asscciaued with the upper roll 27 the gantry-shaped presser arm 37a, which consists of two lateral pressing elements 36d and 36d2, a common carrying element 40, two holding elements 41a, 41b and two intermediate elements 42a, 42b. The presser arm 37a is pivoted up, together with the upper roll 27, about a pivot mounting 44, which is mounted on the support 38b. The holding elements 4la, 41b are -seen in side view -of angled (right-angled) construction, one angled arm of the holding element 41b being rotatably mounted in each case in the region of its free end on the rotary mounting 44. The other angled arm of the holding element 41a has in the region of its free end a part of a locking device. The presser arm 37a is shown in the unlocked and opened position. Reference numerals 43a, 43b denote the roll bearings of the upper roll 27. The presser arm 37a has been explained using the example of loading of the upper roll 27. With each upper roll 24 to 27 there is -12 -associated a corresponding presser arm 37 having pressing elements 36a to 36d (see Fig. 3) In the embodiment shown in Fig. 5 there is a lower roll III and an upper roll 27 which rolls on top of it. The upper roll 27, for example made of steel, consists of a roll oore 27.1, on whioh there is arranged a resilient roll covering 27.5, and of two roll neoks 27.2, 27.3. The roll core 27.1 and roll necks 27.2, 27.3 are of one-piece construotion. The lower roll III is made of steel and has a central cylindrical roll nipping body 50.1. The roll covering 27.5 of the upper roll 27 lies on top of the surface of the roll nipping body 50.1 (the loaded state is shown) . The lower roll III is rotatably mounted in the two lower roll mountings 38a, 38b.

With reference to Fig. 5a, the roll bearing 43a for mounting of the upper roll 27 (pressure roll) is in the form of an anti-friction bearing. The stationary bearing housing 43.1 forms the outer race and the rotary body 43.2 forms the inner race of the anti-friction bearing. In the cylindrical inner envelope surface of the bearing housing 43.1 and in the cylindrical outer envelope surface of the rotary body 43.2 there have been machined, for example ground, two circumferential annular grooves (tracks) in each case, in which balls 51.1, 51.2, for example made of 100 Cr 6, run. In this way there are formed two deep-groove ball bearings. Located opposite the outsides of the balls there are arranged two circumferential seals, which seal off the space between the bearing element 43a and rolls and which are sealed with a lubricant, for example grease. The rotary body 43.2 is of one-piece construction and consists of a hollow cylindrical part and a part in the shape of a truncated cone having an -13 -envelope surface in the shape of a truncated cone. The hollow cylindrioal part is located inside the cylindrioal internal hollow space of the bearing housing 43a, whilst the part in the shape of a truncated cone projects out beyond an end face of the bearing housing. The upper roll 27, for example made of steel, consists of a roll core 27.1 and two roll necks 27.2 and 27.3 (only 27.2 shown) located to the outside. On the roll core 27.1, on top of an intermediate layer 27.4 (holding layer), there is arranged the resilient roll covering 27.5. The roll necks 27.2 and 27.3 (only 27.2 shown) have a recess open to one side, in the shape of a truncated cone, having an envelope surface in the shape of a truncated cone. In operation, the part in the shape of a truncated cone and the recess 4.21 in the shape of a truncated cone are in contact with one another by way of the truncated cone-shaped envelope surfaces in the shape of truncated cones and are in engagement with one another in a force-based connection. Fig. 5 shows the coupled state. In this way there is formed a coupling. The part of the rotary body 43.2 which is in the shape of a truncated cone engages in the recess open to one side, in the shape of a truncated cone, outside the bearing housIng 43.1. The rotary body 43.2 has an axial cylindrical hole, through which there passes a fixing screw 52a which secures the parts in the coupled state. In addition, a circlip is associated with the head of the screw. In this way, an upper roll mounting is produced by means of deep-groove ball bearings. The mounting is in the form of a double-row special bearing. The mounting is greased for life and especially sealed. The connection to the upper roll core 27.1 is made by way of a steeply tapering connection. This transfers high torgues with low axial -14 -forces and has very low concentricity tolerances. The axial forces that occur are taken up by the deep-grooved ball bearing arrangement. Using the fixing screw, the bearing unit is forced off over the circlip when the connection is released; as a result, jamming is not possible.

Referring to Fig. Sb, the one-piece lower roll III has a central cylindrical roll nipping body 50.1, which has the largest diameter of the lower roll III. The roll nipping body 50.1 has, on its circumferential surface, continuous fluting 50.8, which is shown only incompletely. The roll covering 27.5 of the upper roll 27 lies on top of this fluted surface of the roll nipping body 50.1. Adjacent to the roll nipping body 50.1, on either side in the direction of the end regions of the lower roll III, are two cylindrical roll regions 50.2 and 50.3, which have a smaller diameter than the roll nipping body 50.1, two roll portions 50.4 and 50.5 in the shape of truncated cones which have diameters which decrease towards the outsides and two cylindrical roll necks 50.6 and 50.7, which are rotatably mounted in the two roll mountings 38a and SOb respectively (see Fig. 5) The roll body of the upper roll 27 consists of a central roll core 27.1 (basic roll body) and two outer roll necks 27.2 and 27.3 (the upper rolls 24, 25, 26 each correspondingly have a central roll core and two roll necks) . The roll body of the lower roll III consists of at least one central roll nipping body 50.1 and two outer roll necks 50.6 and 50.7 (the lower rolls I, IT each correspondingly consist at least of a central roll nipping body and two outer roll necks) Figures 6a, 6b to Ba, 8b show, by way of example, three embodiments of the device according to the invention, -15 -wherein the same references are assigned to like mentioned items (components, dimensions and the like) and different references are assigned to dissimilar mentioned items. In the three embodiments there is shown, by way of example, a roll pair 27/ITT of a drafting mechanism 22 (Fig. 1) or of a drafting mechanism S (Fig. 3); the statements and explanations apply likewise to the other roll pairs of the drafting mechanism 22 and S. In all three embodiments, the work region (nipping region) on the roll covering is changed by mounting the upper roll 27 (and/or 24, 25, 26) in reverse, the used part (nipping region) of the roll covering 27.5 being repositioned outside, and an unused part of the roll covering 27.5 being repositioned in, the nipping region (work region) . A fibre sliver 23 (see Fig. 1) is, in the nipped state, arranged between the nipping region 53 of the roll covering 27.5 of the upper roll 27 and the circumference of the roll nipping body 50.1 of the lower roll III. Tn Figures 6 to 8, there is shown, for the sake of clarity, only the repositioning of the nipping region, with the intact nipping region being shown by reference numeral 53 (in the working position) in Figures 6a, 7a, 8a and the worn nipping region being shown by reference numeral 53' (in the repositioned position) in Figures 6b, 7b, 8b. Figures 9a, 9b show the nipping of the fibre sliver 23 between the upper roll 27 and the lower roll III, with Fig. 9a showing the intact nipping region 53 and an unused region 54 before repositioning and Fig. 9b showing the worn-down nipping region 531 and the region 54' being used as the new nipping region after repositioning.

For repositioning worn-down/unused regions of the roll covering 27.5, the upper roll 27 is rotated out from the -16 -upper roll bearings 43a, 43b through 1800 about an axis perpendicular to its axis of rotation X and is fitted baok in the upper roll bearings 43a, 43b.

In the case of a mounting according to Fig. 5a, the fixing screw 52a (and also the fixing screw 52b which is not shown) is removed, the roll neck 27.2 is pulled off (decoupled from) the rotary body 43.2, the upper roll 27 is rotated through 180°, and then the roll necks and rotary bodies are pushed onto one another again, and the fixing screws 52a, 52b are tightened.

In Figures 6 to 8, a centre line Z (mirror axis) passes through the central roll nipping body 50.1 of the lower roll III. The centre line Z is perpendicular to the axis of rotation X of the upper roll 27 and to the axis of rotation Y of the lower roll III.

The loading device (two pressing elements 36d1, 36d2 according to Fig. 5) of an upper roll 27 can take the following forms in the case of the embodiments shown in Figs. 6, 7 and 8: 1. Figures 6a, 6b Arrangement of the loading device symmetrically relative to the lower roll III and, conseguently, to the nipping region 53 (work region) . The spacings a1, a2 of the pressing elements 36d-, 36d2 to the centre line Z are the same. Different loadings of the upper roll bearings 43a, 43b, which are taken up by the bearing structure, are provided. The loading force can be set the same. In Fig. 6b, reference letter c denotes the average spacing of the repositioned nipping region 53' to the non-repositioned nipping -17 -region 53 (see Fig. Oa) and can be, for example, mm.

The upper roll 27 and the lower roll III are arranged asymmetrically relative to one another. The roll oovering 27.5 is longer than the roll nipping body 50.1; both are arranged asymmetrically in relation to the centre line Z. The pressing elements 36d1, 36d2 (loading cylinders) are arranged symmetrically. Two standard-production upper roll bearings 43a, 43b of identical construction are used.

2. Figs. 7a, 7b Arrangement of the loading device symmetrically relative to the lower roll III and use of two different upper roll bearings 43a and 43b (different bearing construction) . The rotary body 43.2 in the upper roll bearing 43a corresponds to the arrangement shown in Fig. 5a., namely the length projecting out from the upper roll bearing 43a. The rotary body 43.3 in the upper roll bearing 43b projects out a greater length c from the upper roll bearing 43b compared to the rotary body 43.2 corresponding to Fig. 5a. The smaller spacing of the roll neck 27.2 from the upper roll bearing 43a is denoted by reference letter b1, compared to the larger spacing c of the roll neck 27.3 from the upper roll bearing 43b.

On turning around the upper roll 27, the upper roll bearings 43a, 43b have to be changed from one roll end to the other. The loading force can in this case be set the same.

-18 -The upper roll 27 and the lower roll III are arranged asymmetrically relative to one another. The pressing elements 36*, 36d2 (loading cylinders) are arranged symmetrically. Two different upper roll bearings are used: one standard-production upper roll bearing 43a and one special upper roll bearing 43b.

3. Figs. Sa, Sb Arrangement of the loading device asymmetrically relative to the lower roll III, but symmetrically relative to the upper roll 27. The spacings a2, d from the pressing elements 36d, 36d2 (centre line through the pressing cylinders) to the centre line Z are different. The spacings b1, b2 from the roll necks 27.2, 27.3 to the upper roll bearings 43a, 43b are the same.

The loading forces used in operation on each cylinder side (each pressing element 36d1, 36d2) are different. The loadings of the upper roll bearings 43a, 43b are different, but centred between the tracks of the balls 51.1, 51.2 (see Fig. 5a) . The upper roll 27 and the lower roll III are arranged asymmetrically relative to one another. Two standard-production upper roll bearings 43a, 43b of identical construction are used.

By way of example, Figs. 9a and 9b show the repositioning of the worn region of the upper roller in one illustrative embodiment. According to Fig. 9a, upper roll 27 is positioned asymmetrically relative to lower roll III.

By way of illustration a sliver 23 is shown in a nipping -19 -region 53, which over time becomes worn with formation of grooves in the region where the fibre runs through.

Referenoe numeral 54 in Fig. 9a indicates a region of the roll covering that is intact because it is not currentiy in contact with the fibre material. Through rotation of the upper roller 27 about the vertical axis indicated by a broken line in Figs. 9a and 9b, the new, intact region 54 of the roller covering of the roller 27 is positioned at the nipping region, indicated in Fig. 9b by reference numeral 54', whilst the worn region is repositioned at the position indicated by reference numeral 53' Figs. 10 and II show schematically further embodiments of the invention. In the embodiment of Fig. 10, the upper roll 27 is shorter than working length of the lower roil ITT (e.g. nipping portion 50.1). The roller 27 is asymmetrically positioned with regard to a centre line Z. In the embodiment of Fig. 11, the upper roller 27 and the lower roller ITT have respective working areas that are equal in length. The upper roll 27 is displaced axially relative to the lower roll III. By way of comparison, Fig. 12 shows a conventional drafting roll pair in which the upper roll 27 and lower roll III are of equal length and are arranged symmetrically around the centre line Z.

Claims

-20 -Claims 1. A device cn a spinning rcom machine having a drafting mechanism for at least one textile fibre sliver, the drafting mechanism having a plurality of roll pairs, arranged one after another, ccmprising an upper roll and lower roll, wherein the upper roll has a resilient roll covering and the lower roll has a roller nipping body, the resilient roll covering of said upper roll having a nipping region where a fibre sliver or a plurality of fibre slivers is arranged to be nipped in co-operation with the roller nipping body of said lower roll, wherein the upper rolls and the lower rolls are arranged asymmetrically relative to one another.
2. A device according to claim 1, wherein the drafting mechanism comprises at least three roll pairs and the upper roll and the lower roll of at least one roll pair are arranged asymmetrically relative to one another.
3. A device according to claim 1 or claim 2, wherein the upper roll and the lower roll of each of the drafting roll pairs are arranged asymmetrically relative to one another.
4. A device according to any one of claims 1 to 3, wherein the upper rolls and the lower rolls are arranged asymmetrically relative to one another in relation to a centre line through the roll nipping body of the lower roll.
5. A device according to any one of claims 1 to 4, wherein the roll covering of the upper roll and the roll nipping body of the lower roll are arranged asymmetrically relative to one another.
6. A device according to any one of claims 1 to 5, wherein the roll covering and the roll nipping body are -21 -arranged offset relative to one another in an axial direction.
7. A device according to any one of claims 1 to 6, wherein the roll covering and the roll nipping body are arranged offset relative to one another in an axial direction in relation to a centre line through the roll nipping body.
8. A device according to any one of claims 1 to 7, wherein the length of the roll covering of the upper roll and the length of the roll nipping body of the lower roll are different.
9. A device according to claim 8, wherein the length of the roll covering of the upper roll is greater than the length of the roll nipping body of the lower roll.
10. A device according to any one of claims 1 to 9, wherein the upper roll has a roll shaft that is reversiblymountable.
11. A device according to any one of claims 1 to 10, wherein the lower roll as a shaft that is reversiblymountable.
12. A device according to any one of claims 1 to 11, wherein at least one roll of a roll pair is so repositionable locally in relation to the respective other roll that the portion of the resilient roll covering located at the nipping region can be changed.
13. A device according to any one of claims 1 to 12, wherein the spacing of each end face of the resilient roll covering from the nipping region is of different magnitude before and after, respectively, reversing the mounting of the roll.
14. A device according to any one of claims 1 to 13, wherein the nipping region of the resilient roll covering -22 -is located asymmetrically relative to a plane perpendicular to the roller oore.
15. A devioe acoording to any one of claims 1 to 14, wherein the nipping region is part of a roll covering that extends ciroumferentially around the roll core.
16. A device according to claim 15, wherein the resilient roll covering is of an elastomeric material.
17. A device according to claim 15 or claim 16, wherein the roll covering is mounted on top of an intermediate layer on the roll core.
18. A device according to any one of claims 1 to 17, wherein the roll core is of cylindrical construction.
19. A device according to claim 18, wherein the roll covering is of hollow cylindrical construction.
20. A device according to any one of claims 1 to 19, wherein the roll body of the upper roll is made of a metallic material.
21. A device according to any one of claims 1 to 20, wherein the roll body of the lower roll is made of a metallic material.
22. A device according to any one of claims 1 to 21, which further comprises a respective roll bearing assembly associated with each end of the upper roller, the spacing between the end face of the roll covering or of the roll core and the associated roll bearing at a first end of the roll being of different magnitude from the spacing between the end face of the roll covering or of the roll core and the associated roll bearing at a second end of the roll.
23. A device according to any one of claims 1 to 22, wherein the upper roll is loaded by loading means which applies a force to the upper roll.

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24. A device according to claim 23, wherein the loading means is arranged symmetrically relative to the lower roll and consequently relative to the nipping region.
25. A device according to claim 24, wherein the loading means comprises a pair of loading cylinders, the loading cylinders being arranged to apply a load symmetrically relative to the lower roll.
26. A device according to claim 24 or claim 25, wherein the loading force is set the same for each loading cylinder.
27. A device according to any one of claims 23 to 26, wherein the loading means of the upper roll is arranged asymmetrically relative to the lower roll, but symmetrically relative to the upper roll
28. A device according to claim 27, wherein the loading means comprises a pair of loading cylinders, the loading cylinders being arranged to apply a load symmetrically relative to the upper roll and with different loading pressures on each cylinder side.
29. A device according to claim 28, wherein the loading of the bearings is different but is centred between the bearings of each roll bearing.
30. A device according to any one of claims 27 to 29, wherein the loading means is arranged asymmetrically relative to the lower rolls, and two different bearing constructions are used.
31. A device according to claim 30, wherein the loading force is set the same.
32. A device according to claim 31, wherein, on reversing the position of the upper roll, the bearings are arranged to be changeable between the roll ends.-24 -
33. A device according to claim 32, wherein the loading force is arranged to be set the same.
34. A device on a spinning room machine, especially a carding machine, draw frame, combing machine, lap winder or the like, having a drafting mechanism for at least one textile fibre sliver, having loading of the upper rolls of the drafting mechanism, the latter comprising roll pairs, arranged one after another, consisting of an upper roll and lower roll, wherein the upper roll has a resilient roll covering which is mounted circumferentially on a roll core (basic roll body) and which has a nipping region where a fibre silver or a plurality of fibre slivers are arranged to be nipped in co-operaticn with the roll nipping body of a lower roll, wherein the upper rolls and the lower rolls are arranged asymmetrically relative to one another.
35. A drafting mechanism comprising a drafting roller pair substantially as described herein with reference to and as illustrated by any of Figs. 1 to 5, Se, Sb, Ea and 6b, 7a and 7b, 8a and 8b, 9a and 9b, 10 and 11.
36. A spinning room machine comprising a device according to at least one of the preceding claims.
37. A spinning room machine according to claim 36, having sliver guiding elements for guiding a single presented fibre sliver and a drafting mechanism for that single fibre sliver.
38. A spinning room machine according to claim 36, comprising sliver guiding elements for guiding a plurality of presented fibre slivers and a drafting mechanism for said plurality of fibre slivers.
39. A spinning room machine according to at least one of claims 36 to 38, wherein the drafting mechanism is horizontally arranged.-25 -
40. A spinning room machine according to any one of ctaims 36 to 38, comprising a vertically arranged drafting mechanism.
41. A spinning room machine according to any one of ctaims 36 to 38, wherein it has a drafting mechanism that is inclined relative to horizontal and vertical.
42. A spinning room machine according to any one of otaims 36 to 41, which is in the form of a carding machine/draw frame combination, wherein the fibre sliver produced in the carding machine is supplied directly to the drafting mechanism.