GB2479057A - Pre-stressing of a working or functional element carrier for a card - Google Patents

Abstract

A flat card or roller card comprises at least one working and/or functional element 23 having between two end regions, for fixing to the card, an elongate carrier element 24 which has an inward facing region located opposite cylinder clothing at a spacing. At least one stressing element 40 is associated with the carrier element 24 for axial pre-stressing. The stressing element may induce concave curvature of the carrier 24 and an adjusting arrangement may be included for the degree of pre-stressing and/or the radius or curvature. The stressing element may comprise a rod 40 extending through a channel in the lower part of the carrier. The adjusting arrangement may comprise nuts on the ends of the rod which may be of sleeve form to receive part of an engaging element (47, Figure 8) of a card top drive belt. The carder may be made of aluminium and the stressing element may also be made of aluminium or a material with a different coefficient of expansion such as steel or fibre-reinforced plastics such that temperature dependant curvature of the carrier is achieved which compensates for changes in the spacing from the cylinder due to heat generated in use.

Description

Apparatus at a flat card or roller card, wherein at least one working and/or functional element is present The invention relates to an apparatus at a flat card or roller card, wherein at least one working and/or functional element is present, for example a fixed carding element, revolving card top flat.

Working and/or functional elements may have between two end regions, for support on the card, an elongate carrier element which has an inward (that is, in towards the working region of the card) facing region located opposite the cylinder clothing at a spacing.

In cards of current mode of construction, in addition to the card top having flexible clothings, fixed carding elements having all-steel clothings are also used for the carding process, the actual clothings being borne on high-precision carrier components, which are then mounted on the machine. Extruded aluminium profiled parts are now usually used as carrier components. Besides having numerous advantages such as, for example, low weight, high rigidity etc., these do have the disadvantage, however, that when heated on one side, which does happen in the case of carding, they undergo deformation to the heated side. The taller the component, the greater is the rigidity but also the deformation under the influence of heat. This deformation results in a carding nip which is not constant, which in turn has the consequence of a technical carding result which is not optimal.

The fixed carding elements increasingly being used in flat cards and roller cards generally consist of a carrier profiled part and, fixed thereto, clothing strips (1 to 3 per carrier profiled part) . The carrier profiled parts for fixed carding elements are now constructed as extruded aluminium profiled parts that are closed on all sides. The heat arising during the carding process is to a large extent given off to the outside by way of the fixed carding elements. The temperature gradient necessary therefor within the cross-section of the profiled part results in deformation of the fixed carding element. The greater that gradient, the greater is the deformation.

The heating gives rise, however, not only to thermal expansion over the entire working width of the card but also to heat gradients over the arrangements of the various components of the card. For example, a temperature of 45°C may come about at the cylinder surface. A fixed carding segment arranged adjacent to the cylinder will also approximately reach this temperature on the cylinder clothing side. In contrast, on that side of the carding segment which is remote from the cylinder, which side for constructional reasons (owing to the working width and the accuracy of the elements) has a back that is several centimetres tall, the temperature will reach a substantially lower value (for example, 28°C) . The difference in temperature over a fixed carding segment can accordingly amount to several degrees Celsius. How large that temperature difference is will be dependent on the nature of the segment (construction, material), the carding work done (speed of rotation, production), the spacing of the element from the roller and how the heat produced can be removed.

This heat gradient causes sagging of the elements over and across the width of the card. This sagging gives rise to a narrower carding nip in the middle than towards the outsides. This gives rise to an uneven carding nip which becomes wider towards the outsides. This results in reduced carding quality and/or in worse nep disentanglement. It can likewise result in!vlateral flight!v of the fibres. This means that fibres collect, and even settle, in the edge region, especially outside the working width. These effects come about in a card having a working width of 1 metre but become greater with increasing working width, for example when the working width is greater than 1 metre, for example 1.2 metres or more. The anomalies which occur as a result of the above-mentioned effects cannot be disregarded here but rather are a problem for the overall carding quality of the card. The problem of thermal sagging is added to the mechanical sagging that becomes greater with increasing working width.

As a result of the fact that fixed carding elements heat up very substantially in operation of the card, the extruded aluminium profiled parts of the fixed carding elements act, on the outside (the side facing away from the cylinder), as heat sinks which give off their heat to the surrounding air by means of free convection. This results in a slight temperature gradient within the extruded profiled part. The side facing the cylinder is warmer and therefore expands more than the outwards facing side, as a result of which the fixed carding element bends towards the cylinder. This bending (and also the expansion of the cylinder) results in the carding nip becoming narrower in the middle of the machine and, as a result, the web becomes less uniform and the quality poorer. In addition, lateral flight may occur.

From WO 2004/106602 A there is known an element for a card, which element can come into contact with the fibre material on at least one side, the element having on that side a concave bend over the working width of the card. For that purpose, the working side is machined or set with a hollow. The element can be a covering or casing element, a carding segment, a blade, optionally having a suction extraction device, a guiding element or a working element.

A disadvantage lies in the fact that, when the machine is in the cold state, a concave bend is produced which is predetermined to be the same in all operating states.

Adaptation to the differing heat generation in the case of processing different fibre materials, for example cotton and/or synthetic fibres, is not possible.

It is an aim of the invention to provide an apparatus of the kind described at the beginning that avoids or mitigates the mentioned disadvantages and that especially makes it possible to match the working and/or functional element to different fibre materials and manufacturing processes.

The invention provides an apparatus at a flat card or roller card having a clothed cylinder, wherein at least one working and/or functional element is present positioned opposed to the cylinder clothing, said at least one working and/or functional element comprising two end regions, for support on the card, and extending between the end regions an elongate carrier element which has an inward face located opposite the cylinder clothing at a spacing, wherein at least one stressing element is associated with the carrier element for axial pre-stressing.

In one embodiment, there is provided an adjusting arrangement by means of which the degree of pre-stressing and/or the radius (curvature radius) of a concave bend in the carrier element is adjustable.

As a result of the fact that at least one stressing element is associated with the carrier element for axial pre-stressing and, preferably, that there is provided an adjusting arrangement by means of which the degree of pre-stressing and/or the radius (curvature radius) of a concave bend in the carrier element is adjustable, it is made possible, even when the machine is in the cold state, to adjust the pre-stressing/bending in the profiled part to a different value by varying the tightening torque, for example, of the nuts on the end of a threaded rod. The tighter the nuts are tightened, the greater is the bending of the profiled part. As a result it is even possible for dimensional inaccuracies in the profiled part when the machine is in the cold state to be corrected.

As a result of the fact that, according to a preferred embodiment, the carrier element (for example, aluminium) and the stressing element (for example, steel) are made of materials having different thermal expansion coefficients, an effect analogous or equivalent to a bimetallic effect occurs, which brings about the curving or bending-back of the carrier element. A particular advantage lies in the fact that the change in the curve of the carrier element on introducing and removing heat comes about after just a short time. The nature and degree of the change in temperature have an effect on the nature and degree of the curving. it is advantageously made possible for due regard to be given to a card's speeding-up or slowing-down behaviour so that changes in the spacing of the working and/or functional element, for example the carding spacing, that occur owing to thermal expansion or contraction are automatically cancelled out. As a result of these measures, the working and/or functional element follows the convex bulging-out of the cylinder on heating (warming-up phase) and bends away from the cylinder. In analogous manner, the carding element bends back towards the cylinder when heat is removed (cooling-down phase) . As a result, a uniform carding nip is always present -both when the machine is cold and hot and also in the course of the warming-up and cooling-down phases.

Advantageously, a threaded elongate member, for example, a threaded rod, a threaded bolt or the like is passed through the carrier element in an axial direction.

Preferably, a nut a screwed onto the threaded rod at at least one end. In a further embodiment, in the carrier element there is provided a channel extending continuously through it in an axial direction. Advantageously, the stressing element is permanently associated with the carrier element. In one embodiment, the carrier element and the stressing element are made of materials having different thermal expansion coefficients. In another embodiment, the carrier element and the stressing element are made of materials having the same thermal expansion coefficient. Advantageously, at least one stressing element is an integral component part of the carrier element. Preferably, the stressing element and the carrier element are constructed in the form of a bimetallic element.

Preferably, the carrier element consists of at least two different components (carrier body and stressing element) Advantageously, the component having the lower thermal expansion coefficient is associated with the side facing the cylinder and/or the component having the higher thermal expansion coefficient is associated with the side remote from the cylinder. Advantageously, the carrier body is made of a flexurally resilient material, for example aluminium or an aluminium alloy. Advantageously, at least one stressing element is made of a resilient material, for example of steel or aluminium.

Advantageously, the at least one stressing element extends over the working width (longitudinal direction of the carrier body) . Advantageously, the at least one stressing element is arranged in the lower half of the aluminium carrier body. Advantageously, the stressing element is a screw clamp or the like.

In another embodiment, the spacing (carding nip) remains the same in the event of heating or cooling affecting the carrier element. Advantageously, the carrier element bends away from the cylinder over the working width on heating. Preferably, the heating takes place during the speeding-up phase of the card. Advantageously, the carrier element bends back towards the cylinder over the working width on cooling. Preferably, the cooling takes place during the slowing-down phase of the card.

In another embodiment, at least one working and/or functional element is present, having between two end regions, for support on the card, an elongate carrier element which has an inward (in towards the working region) facing fixing face for at least one clothing strip which is located opposite the cylinder clothing at a spacing (carding spacing), there being at least one bending element forming a permanently associated component part of the carrier element, and the carrier element and bending element being made of materials having different thermal expansion coefficients.

Advantageously, a stressing element is made of fibre- reinforced plastics material. Preferably, the fibre-reinforced plastics material is a carbon-fibre-reinforced plastics material or a glass-fibre-reinforced plastics material. Preferably, the working width is greater than 1200 mm, preferably greater than 1290 mm.

Advantageously, a rod, bolt or the like is arranged to be passed through the carrier element in an axial direction. Preferably, the stressing element is connected to the carrier element by adhesive bonding or the like.

The present invention also provides an apparatus at a flat card or roller card, wherein at least one working and/or functional element, for example a fixed carding element or revolving card top flat, is present, having between two end regions, for support on the card, an elongate carrier element which has an inward (in towards the working region of the card) facing region located opposite the cylinder clothing at a spacing, wherein at least one stressing element is associated with the carrier element for axial pre-stressing.

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 flat card having an apparatus according to the invention; Fig. 2 shows a stationary carding element, a portion of a side screen, with spacing between the carding segment clothing and the cylinder clothing; Fig. 2a shows the carding element according to Fig. 2 in detail; Fig. 3 shows, in a side view, a fixed carding element according to the invention, with a carrier body, clothing strip and clothing, with a threaded rod having been passed through the carrier element; Fig. 3a shows, in an exploded view, part of a carrier body of a fixed carding element, the clothing backing and the clothing; Fig. 4 is a side view of a part of a carding machine showing a side screen with a setting bend (flexible bend) for revolving card top flats and two setting bends (extension bends) for stationary functional elements with the apparatus according to the invention; Fig. 5 shows, in diagrammatic form, a section I-I through the carding machine of Fig.4 having a setting bend (extension bend) with a fixed carding element on a side screen on one side and a corresponding view on the other side; Fig. 5a shows, in an exploded view (side view), part of a carrier body with a groove and bending element; Fig. Sb shows, in a front view, in section, part of the carrier body with a channel extending continuously through it and an end region of a threaded rod with nut; Figs. 6a, 6b show, in front views, the carrier element with a stressing element in the unstressed state (Fig. 6a) with a flat working surface and in the pre-stressed state (Fig. 6b) with a concave bend; -10 -Figs. 7a, 7b show, in front views, the carrier element with a stressing element and the cylinder in the cold state (Fig. 7a) and in the warm state (Fig. 7b); and Fig. 8 shows, in a front view, a section through an end region of a revolving card top flat according to the invention.

With reference to Figure 1, a carding machine, for example a flat card IC made by TrOtzschler GmbH & Co.KG of Monchengladbach, Germany, has a feed roller 1, feed table 2, lickers-in 3a, 3b, 3c, cylinder 4, doffer 5, stripper roller 6, nip rollers 7, 8, web guide element 9, sliver funnel 10, delivery rollers 11, 12, revolving card top 13 with card top guide rollers 13a, 13b and flats 14, can 15 and coiler 16. Reference letter M denotes the centre point (axis) of the cylinder 4. Reference numeral 4a denotes the clothing and reference numeral 4b the direction of rotation of the cylinder 4. The arrow A indicates the working direction. The directions of rotation of the rollers are indicated by the curved arrows drawn inside the rollers.

In the pre-carding zone (between the licker-in 3c and the rearward card top guide roller 13a) a plurality of fixed carding elements 23' are located opposite the cylinder 4, and in the post-carding zone (between the forward card top guide roller 13b and the doffer 5) a plurality of fixed carding elements 23' are located opposite the cylinder 4, which are each located next to one another, seen in the circumferential direction of the cylinder 4. One or more, and preferably all, of the fixed carding elements 23' and one or more, preferably all, of -11 -the fixed carding elements 23'' may be in accordance with the invention.

Fig. 2 shows an illustrative embodiment of the invention, in the form of a fixed carding element. An approximately semi-circular rigid side screen 18 is fixed laterally to the machine frame (not shown) on each side of a card, on the outside of which side screen 18 there is concentrically mounted, in the region of the periphery, an arcuate rigid support element 19, which has a convex outer face 19' as the bearing face and also an underside 19''.

The apparatus according to the invention comprises in each case at least one fixed carding element 23, which has at both its ends support faces, which are supported on the convex outer face 19' of the support element 19 (for example, an extension bend) (see Fig. 4) . On the underside of the carrier 24 (carrier body) of the fixed carding element 23 there are mounted clothing backings 252, 252 each having clothings 261, 262 (carding clothings) Reference numeral 21 denotes the circle of tips of the clothings 262, 262. The cylinder 4 has on its circumference a cylinder clothing 4a, for example a sawtooth clothing.

Reference numeral 22 denotes the circle of the tips of the cylinder clothing 4a. The spacing between the circle of tips 21 and the circle of tips 22 is denoted by reference letter a and is, for example, 0.20 mm. The spacing between the convex outer face 19' and the circle of tips 22 is denoted by reference letter b. The radius of the convex outer face 19' is denoted by reference letter r5 and the radius of the circle of tips 22 is denoted by reference letter r2. The radii r5 and r2 intersect at the centre point M of the cylinder 4. The carding segment 23 according to Figure 2 consists of a carrier 24 and two clothing -12 -strips 27k, 272, each of which comprises a clothing backing and 252, respectively, each having clothings 26 and 262, respectively. The clothing strips 27, 272 (carding elements) are arranged one after the other in the direction of rotation (arrow 4b) of the cylinder 4, with the clothings 26, 262 (sawtooth wire portions) and the clothing 4a of the cylinder 4 being located opposite one another. The carrier 24 is made of an aluminium alloy and is extruded. The clothing backings 25, 252 are fixed to the carrier 24 by means of screws 31a and 31b, respectively. The mass of the carrier 24 is arranged tangentially to the cylinder 4, seen in the width direction.

The surface of the clothing tips can, when seen in a side view, be concavely curved. The circle of tips 21 of the clothings 26, 262 is in that case concentrically or eccentrically arranged relative to the circle of tips 22 of the cylinder clothing 4a. In other arrangements, the surface of the clothing tips can, when seen in a side view, be formed straight. In this arrangement, the tips of the clottiings 26k, 262 can form an approximation to a circle, by virtue of a slight inclination of the clothings 26, 262 towards one another.

Reference numeral 42a denotes a nut which is screwed onto the thread at one end of a threaded rod (see Fig. 5a) In accordance with Fig. 3, a fixed carding element 23 according to the invention has a carrier 24; on the fixing face 24b thereof, which in operation faces inwards (in the direction of the cylinder 4), there is mounted a clothing strip 27 (carding element) . The clothing strip 27 consists of a clothing backing 25, to which two clothings 26 and 262 are fixed. The clothing backing 25 is fixed to the -13 -carrier 24 by screws 31a, 31b in the manner shown in Fig. 2. The carrier 24 is constructed as a hollow profiled member, which has a height h1, a width b and a length 1 (corresponding to the longitudinal direction L in Fig. 5) Reference h2 denotes the height of the carrier 24 and clothing backing 25, and reference h3 denotes the height of the carrier 24, the clothing backing 25 and the clothing 26. In accordance with the exploded view in Fig. 3a, a carrier 24 has an upper face 24a and a lower face 24b, and the clothing backing 25 has an upper face 25a and a lower face 25b. The carrier 24 has, for example, the following dimensions: h = 58 mm, b = 72 mm, 1 = 1300 mm.

In the foot plate 24' of the aluminium carrier body 24, that is to say in the lower half relative to the cylinder clothing 4a, there are provided four bending elements 28a to 28d made of steel which form, in accordance with the intended purpose, a permanently associated component part of the carrier element 23 (see Fig. 5a) . In the lower region of the longitudinally extending outer surface 24c, 24d of the carrier body 24, two further bending elements 29a and 29b are permanently fixed in a recess over the length L of the carrier body 24, for example by adhesive bonding. As Fig. 3a shows, a bending element 31a is provided, in a shape-based connection, in a recess in the region of the lower surface 24b of the carrier body 24, for example being adhesively bonded in place so that it lies flat. Further bending elements 31b to 3m (not shown) can be provided in this region. The bending elements 28a to 28d, 29a, 29b and 31a to 3m can advantageously be made of flat steel (bar steel) and can be a permanent component part of the carrier body 24 as a result of a shape-based or force-based connection. Permanent fixing can be carried -14 -out, for example, by means of pressing into place, adhesive bonding, welding, riveting, screwing or the like. The bending elements can be of strip-shaped or like construction.

In the region of the foot plate 24' of the aluminium carrier body 24, that is to say in the lower half facing the cylinder clothing 4a, there is shown a nut 42a, which is screwed onto the thread at one end of a threaded rod 40 (see Fig. 5b) . The threaded rod 40 extends continuously over the length L of the carrier body 24.

Fig. 4 shows a part of a flat card, including a side screen 18a enclosing the carding cylinder (the side screen 18b on the other side is shown in Fig. 5) is shown with a setting bend 17a (flexible bend) for the revolving card top flats 14 and two setting bends 19'a, 19' a (extension bends) for stationary functional elements (fixed carding elements, extraction hoods) . The setting bend 17a is provided in the region of the upper periphery of the side screen 18a. Two setting bends 19'a, 19' a are provided in the two lateral peripheral regions of the side screen 18a. As positioning devices, positioning spindles 36' to 361V and 37' to 37 are associated with each of the setting bends 19'a and 19''a, respectively. The positioning spindles 36' to 361V are supported by their one end on a flange 18'' of the side screen 18a and by their other end on the setting bend 19'a. The positioning spindles 37' to 371V are supported by their one end on a flange 18''' of the side screen 18a and by their other end on the setting bend 19' a. The setting bend 19'a is arranged between the licker-in 3c and the card top guide roller 13a, that is to say in the pre-carding region. On the setting bend 19'a there are mounted stationary -15 -functional elements, which in the example of Figure 4 are non-clothed cover elements 32a to 32c, three fixed carding elements 23' to 23'3 according to the invention and three extraction hoods 33a, 33b, 33c. The setting bend 19' a is arranged between the card top guide roller 13b and the doffer 5, that is to say in the post-carding region. On the setting bend 19' a there are mounted stationary functional elements, which in the example of Fig. 4 are six fixed carding elements 23' to 23' 6 according to the invention and three extraction hoods 34a to 34c. Reference 35a denotes a part of the machine frame, and reference 38a denotes a lower carding bend.

Fig. 5 shows part of the cylinder 4 together with a cylindrical surface 4f of its wall 4e and the cylinder ends 4c, 4d (radial supporting elements) . The surface 4f is provided with a clothing 4a, which in this example is provided in the form of wire with sawteeth. The sawtooth wire is drawn onto the cylinder 4, that is to say is wound around the cylinder 4 in tightly adjacent turns between side flanges (not shown), in order to form a cylindrical work surface provided with tips. Fibres should be processed as evenly as possible on the work surface (clothing) . The carding work is performed between the clothings 261, 262 (see Fig. 2) and 4a located opposite one another (see Fig. 2) and is substantially influenced by the position of one clothing with respect to the other and by the clothing spacing a between the tips of the teeth of the two clothings 266, 262 and 4a. The working width of the cylinder 4 is the determining factor for the working width L of all other work elements of the card, especially for the revolving card top flats 14 (Fig. 1) or fixed card flats 23', which together with the cylinder 4 card the -16 -fibres evenly over the entire working width. In order to be able to perform even carding work over the entire working width L, the settings of the work elements (including those of additional elements) must be maintained over that working width L. The working width L is, for example, 1300 mm. The cylinder 4 itself can, however, be deformed as a result of the drawing-on of the clothing wire, as a result of centrifugal force or as a result of heat produced by the carding process. The shaft ends of the cylinder 4 are mounted in bearings located on the stationary machine frame (not shown) . The diameter, for example 1250 mm, of the cylindrical surface 4f, that is to say twice the radius r, is an important dimension of the machine. The side screens 18a, 18b are fixed to the two machine frames 35a, 35b (cf. Fig. 4) . The extension bends 19a and 19b are fixed to the side screens 18a, 18b. The circumferential speed of the cylinder 4 is, for example, 35 rn/sec. The fixed carding elements 23' according to the invention are fixed to the extension bends 19a, 19b using screws 20a, 20b. References Si and S2 denote the end faces of the fixed carding element 23'.

In that region of the carrier body 24 which faces the cylinder clothing 4a there is provided a channel 41 (see Fig. Sb), incorporated in the aluminium carrier body 24 in the course of extrusion, extending continuously through it.

Passing through the channel 41 in an axial direction is a stressing element in the form of a threaded rod 40 onto each end of which there is screwed a nut 42a (see Fig. Sb) and 42b. The tighter the nuts 42a, 42b are tightened, the greater is the pre-stressing, and the concave bending, of the carrier body 24 (profiled part) -17 -With reference to Fig. 5a, in the foot region of the aluminium carrier body 24 shown in part there is provided in the longitudinal direction L a groove 30a which is open to one side and in which a bending element 28a in the form of a flat steel member is pressed and/or adhesively bonded in place, edgewise, in a shape-based connection. In the inserted state (see Fig. 3), the end face 28' of the bending element 28a and the bottom 24'' of the groove form an interface with one another. The method illustrated in Fig.5a is suitable for incorporation of the bending elements of any of Figs. 2, 3, 3a, 4 or 5.

In an embodiment shown in Fig. Sb, the foot region of the aluminium carrier body shown in part has a channel 41 extending continuously through it, through which channel 41 the threaded rod 40 is passed, the end. regions of the latter projecting out from the channel 41. In each of its two end regions, the threaded rod 40 has a thread 43a (and 43b) onto which a nut 42a and 42b, respectively, is tightly screwed. Between the nuts 42a, 42b and the respectively associated end face Si and S2 of the carrier body 24 there can be arranged a disc washer 44a and 44b, respectively.

Between the outer envelope surface of the threaded rod 40 and the inner wall surface of the channel 41 -both circular in cross-section -there is a spacing d. The carding elements shown in any of Figs. 2, 3, 4 or 5 may include as stressing element a threaded rod arrangement as shown in Fig. Sb.

The mode of operation of the invention is illustrated schematically in Figs. 6a and 6b. Figs. 6a and 6b show the carrier element 23 with the threaded rod 40, including the nuts 42a, 42b, in the cold state. Whereas, in accordance with Fig. 6a, no pre-stressing is applied to the carrier -18 - body 24, the carrier body 24 according to Fig. 6b is pre-stressed (compressed) by tightly tightened nuts 42a, 42b, whereupon a concave bend of height x is produced over the length L in the carrier body 24.

Fig. 7a shows the carrier element 23 (that is to say, the carrier body 24 with the threaded rod 40, including the clothing 26 which is not shown), in accordance with the situation shown in Fig. 6b but mounted on the card in a position opposite the cylinder 4 at a spacing therefrom (see Fig. 5), but in the cold state or, that is, at room temperature. Fig. 7b shows the situation after the warming-up phase, in which the carding nip a is uniform. The two end faces Si, S2 of the carrier body 24 abut the two tightly tightened nuts 42a, 42b (see Figs. 5 and Sb) so that, when the temperature of the carrier body 24 increases, the latter cannot expand in terms of length L, but rather the radial bulging-out increases. As a result, an effect "equivalent to a bimetallic effect" is produced.

As a result of the warming, over the width of the carrier element 24 has a concave bend of height y and the envelope surface of the cylinder 4 a convex bend, the spacing between the concave bend and the convex bend being the same in all locations. Accordingly, only the carrier element 23 reacts passively to the thermal expansion, and contraction, of the cylinder 4. Passive equalisation of the bending on heating and cooling is achieved.

Because equalising thermal expansion effects usually requires the carrier element 23 to move radially in the outwards and inwards directions, it has to be ensured that movements in both directions are possible (this point applies to all embodiments) . This means that heating and cooling have to be taken into account. As can be seen from -19 -the figures in the drawings having bending elements 28; 28a to 28d; 29a to 29b; 31a to 3m; 43, two elements comprising metals with different thermal expansion are -as is customary in the case of a bimetallic strip -connected to one another in combinational manner to form a bimetallic element. The two ends of the bimetallic element (carrier body 24 plus bending element 28) abut respective end stops (see screws 20a, 20b on support elements 19a and 19b, respectively, in Fig. 5) sO that when the temperature of the bimetallic element increases the length L thereof cannot increase but rather the radial bending increases.

As can be seen from the figures of the drawings with a stressing element (threaded rod 40, nuts 42a, 42b), two elements comprising metals with different thermal expansion (carrier body 24, threaded rod 40) are connected to one another in combinational manner. The two ends Si, S2 of the carrier body 24 made of aluminium abut the two nuts 42a, 42b tightened on the threaded rod 40 so that when the temperature of the carrier body 24 increases the length L thereof cannot increase but rather the radial bending increases. As a result, the spacing of the carrier element 23 to the cylinder 4 changes radially, more specifically in a radial direction away from the cylinder clothing 4a in the case of an increase in temperature and in a radial direction in towards the cylinder clothing 4a in the case of a reduction in temperature.

Fig. 8 shows one end region of a revolving card top flat 14 (see Fig. 1) in which there is provided a carrier body 14' (extruded aluminium profiled part) having at both its two ends card top heads in the form of steel pins 46a (and 46b) with which there is associated an engaging element 47 (plastics material) for a card top drive belt -20 - (not shown) . A threaded rod 40 is passed through a channel 41 (see Fig. 5b) provided in the carrier body 14' (profiled part) of the revolving card top flat 14, and on each end thereof there is screwed a sleeve nut 49a (49b not shown) The threaded rod 40 can be made of a material having a different expansion coefficient to aluminium, preferably steel or fibre-reinforced plastics material (CFRP, GFRP) The threaded rod 40 can also be made of aluminium. When the card top flat 14 then warms up in operation of the card, the differing expansion behaviour of the two component parts (carrier body 14', threaded rod 40) results in curving of the card top flat 14. This curving of the card top flat 14 compensates for the convex bulging-out of the cylinder 4 and a uniform carding nip is produced.

The stressing rod 40 can be made, for example, of steel, a fibre-reinforced plastics material or aluminium. The corresponding thermal expansion coefficients are: Steel (alloy steel) : = 1.61 x 10 Steel (non-alloy steel) : = 1.19 x 10 Glass-fibre reinforced plastics material: = 2.5 x 10 -

K

Carbon-fibre reinforced plastics material: = 0.02 x 10 -

K

Aluminium: = 2.38 x 10 -

K

The carrier body 24 and 14' is made preferably of aluminium. The corresponding thermal expansion coefficient for the carrier body 24 and 14' is: Aluminium: = 2.38 x 10 i-

K

-21 -The invention can be put into practice in an embodiment having at least one bending element 28 on its own and also in an embodiment having at least one bending element 28 and at least one stressing element 40.

The invention can be put into practice in an embodiment having at least one stressing element 40 on its own and also in an embodiment having at least one stressing element 40 and at least one bending element 28.

The invention has been illustrated and explained especially using the example of a fixed carding element and a revolving card top flat. It likewise encompasses further working and functional elements, for example extraction hoods, guide elements and the like, which undergo deformation as a result of the introduction and removal of heat so that the spacing relative to the cylinder is changed.