GB2486312A

GB2486312A - Carding machine carrier element with tensioning element

Info

Publication number: GB2486312A
Application number: GB1120566.3A
Authority: GB
Inventors: Britta Jacobs
Original assignee: Truetzschler GmbH and Co KG
Current assignee: Truetzschler GmbH and Co KG
Priority date: 2010-12-03
Filing date: 2011-11-30
Publication date: 2012-06-13
Also published as: GB201120566D0; CN102560751A; BRPI1105716B1; BRPI1105716A2; BRPI1105716B8; DE102010053178A1; CH704218A2; CN102560751B; CH704218B1; ITMI20111758A1

Abstract

A flat or roller card comprises is at least one working element and/or functional element, for example a fixed carding element or revolving flat bar with an elongate carrier element 24. A tensioning element 51 associated with the carrier element allows adjustment of the working element to enable the carding nip to be constant. A clamping device 50 is provided with which the position of the tensioning element 51 is fixable with respect to the carrier element 24. The clamping device may be used to pre-tension the working element such that an operational temperature differential causes the working element to bow in a complimentary manner to the associated working cylinder. Alternatively the clamping element may be activated in use by an increasing temperature differential. Preferably a steel rod 51 is located inside an aluminium tube 52 which is in-turn located within a recess of the carrier element with insulation between the tube and carrier element. The clamping device preferably comprises a sleeve nut threaded onto the aluminium tube and has claws with chamfered surfaces such that screwing the nut onto the tube or relative thermal expansion of the tube and carrier element causes the claws to clamp onto the rod 51.

Description

Apparatus on a flat card or roller card in which there is at least one working element and/or functional element, for example a fixed carding element, revolving flat The invention relates to an apparatus on a flat card or roller card in which there is at least one working element and/or functional element, for example a fixed carding element, revolving flat bar. Working elements and/or functional elements of a card typically have an elongate carrier element between two end regions for support on the carding machine, which element has an inwardly directed (into the working region of the carding machine) region which is located opposite and spaced apart from the cylinder clothing.

In carding machines of current design there are utilisod as carding elomonts for the carding process flats having flexible clothings (revolving flats) and/or fixed carding elements having all-steel ciothings, the actual clothings being held by high-precision carrier components.

It is customary nowadays to use extruded aluminium profiles as carrier components. Such profiles have numer-ous advantages, such as, for example, low weight, high rigidity, etc., but additionally have the disadvantage that when heated on one side, as is the case during carding, they become deformed towards the heated side. The taller the component, the greater its rigidity but also its deformation under the action of heat. Such deformation resuits in a non-constant carding nip, which in turn leads to a non-optimum technological carding result.

Nowadays the carrier profiles for carding elements are in the form of extruded aluminium profiles closed on all sides. The heat arising during the carding process is to a great extent dissipated to the outside by way of the fixed carding elements. The temperature gradient within the profile cross-section necessary for that purpose results in deformation of the fixed carding element. The greater that gradient, the greater also the deformation.

The heating, however, not only leads to thermal expansion over the entire working width of the carding machine but also has the result that temperature gradients develop over the various forms of the different components of the carding machine. For example, the surface of the cylinder can reach a temperature of 45C. A carding element located opposite the cylinder will also reach approximately that temperature on the cylinder clothing side, whereas on the side of the carding element facing away from the cylinder, which on account of its construct-ion (as a result of the working width and the precision of the elements) has a back several centimetres in height, the temperature can reach a significantly lower value (for example 28CC) . The difference in temperature over a card-ing element can accordingly amount to several degrees Celsius. The size of that temperature difference is dependent upon the nature of the element (structure, material), the carding work performed (rotational speed, production rate), the spacing of the element from the roll and how the heat produced can be dissipated.

That temperature gradient causes the elements to sag over the width of the carding machine. As a result of such sagging, the carding nip in the centre becomes narrower than at the outside, resulting in a non-uniform carding nip which widens towards the outside. This leads to a reduction in carding guality and/or inferior untangling of neps. This can also lead to "lateral fly" of the fibres, that is to say fibres collect and even become deposited in the edge region, especially outside the working width.

Those effects are seen in a carding machine having a working width of 1 metre, but increase as the working width increases, for example when the working width is greater than 1 metre, for example 1.2 metres and more. The variations that result from the above-mentioned effect cannot be disregarded here, but are rather a problem for the overall carding guality of the carding machine. The problem of thermal sagging comes in addition to the mechanical sagging which increases as the working width increases.

Because fixed carding elements and revolving flat bars become very hot during operation of the carding machine, the extruded aluminium profiles of the fixed carding elements or revolving flat bars act, on their outer sides (the sides facing away from the cylinder), as cooling bodies which dissipate their heat by free convection to the surrounding air. As a result, a small temperature gradient develops within the extruded profile.

The side facing towards the cylinder is warmer and therefore expands to a greater extent than does the side facing towards the outside, so that the fixed carding element or the revolving flat bar bends towards the cylinder. That bending (and also the expansion of the cylinder) has the result that the carding nip in the centre of the machine becomes narrower and accordingly the web becomes more uneven and the guality deteriorates. In addition, lateral fly can be generated.

Wa 2004/106602 A discloses an element for a carding machine, at least one side of which element can come into contact with the fibre material, the element having on that side a concave curve over the working width of the carding machine. For that purpose, the working side is machined or aligned so as to produce a concave shape. The element can be a cover element or casing element, a carding segment, a flat, a blade possibly with an extraction device, a guide element or a working element. A disadvantage is that when the machine is in the cold state a concave curve is produced which is preset to be the same for all operating states. Adjustment to the different amounts of heat generated during the processing of 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 which avoids or mitigates the mentioned disadvantages, which especially allows adjustment of the working element and/or functional element to different fibre materials and operating circumstances or conditions and which enables the carding nip to be constant.

The invention provides an apparatus on a carding machine in which there is at least one working element and/or functional element having an elongate carrier element between two end regions for support on the carding machine, which element has an inwardly directed region which is located opposite and spaced apart from the cylinder clothing, wherein at least one tensioning element is associated with the carrier element, and a clamping device is provided with which the position of the tensioning element is fixable with respect to the carrier element.

Because at least one tensioning element is associated with the carrier element for axial pre-tensioning, and a clamping device is provided for fixing the position of the tensioning element with respect to the carrier element, a constant or substantially constant carding nip is made possible during operation. It is important to the invention that a clamped connection between the tensioning rod and the carding element is not made until the machine is in operation, when the flat bar is being heated on one side from below by the carding work. As long as the flat bar is not in operation, the rod is able to move freely in the channel of the extruded aluminium profile. If the ambient temperature rises, the rod and the carding element can expand unaffected by one another. No curvature is produced. It is only when the flat bar is being heated on one side by the carding work that a clamping mechanism effects a firm connection between the rod and the flat bar, allowing adjustment to different temperatures or changes in temperature.

A particular advantage is that the tensioning element adjusts automatically to different temperatures caused by a change in climatic conditions. A flat bar having a tensioning element can in that way be pre-mounted in a country of manufacture that has a temperate climate. In a country of use having high temperatures, despite the different expansion behaviours of the tensioning element and the carrier element it is possible to fix the desired position of the tensioning element and, as a result, to compensate for the convex bulging of the cylinder and produce a uniform carding nip.

Because, in accordance with a preferred arrangement, the carrier element (for example aluminium) and the tensioning element (for example steel, fibre-reinforced plastics) are made of materials having different thermal expansion coefficients, a bimetal-analogous or bimetal-equivalent effect occurs, resulting in curvature or bending-back of the carrier element. A particular advantage is that when heat is supplied or withdrawn the change in the curvature of the carrier element takes place after only a short time. The nature and degree of the change in temperature have an effect on the nature and degree of the curvature. Advantageously it is made possible to take account of the run-up/run-down behaviour of a carding machine in such a way that any changes in the spacing between working elements and/or functional elements, for example the carding nip, caused by thermal expansion or contraction are corrected automatically. As a result of these measures, on heating (warm-up phase) the working element and/or functional element follow(s) the convex bulging of tho cylinder and bend(s) away from the cylinder. Analogously, on withdrawal of heat (cool-down phase) the carding element bends back towards the cylinder. As a result the carding nip is always uniform -both when the machine is cold and when the machine is warm and also during both the warm-up and cool-down phases.

Advantageously the arrangement is such that a clamped connection between the tensioning element and the carrier element is not made until the machine is in operation. In certain embodiments, the tensioning element is used for setting the degree of pre-tension and/or the radius (radius of curvature) of a concave curve of the carrier element. Advantageously, a rod, a bolt or the like passes through the carrier element in the axial direction.

Preferably, the rod is loose at at least one end.

Advantageously, a continuous channel is present in the carrier element in the axial direction. Advantageously, the tensioning element is permanently associated with the carrier element. In certain embodiments, the carrier element and the tensioning element are made of materials having different thermal expansion coefficients.

Advantageously, at least one tensioning element forms an integral component of the carrier element. In certain embodiments, the tensioning element and the carrier element are in the form of a bimetallic element. In some embodiments, the carrier element consists of at least two different components (carrier member and tensioning element) . Preferably, the component having the lower thermal expansion coefficient is associated with the side facing towards the cylinder. Preferably, the component having the higher thermal expansion coefficient is associated with the side facing away from the cylinder.

Advantageously, the carrier member is made of a resiliently flexible material. In certain advantageous embodiments, the carrier member is made of aluminium or an aluminium alloy. Advantageously, at least one tensioning element is made of a resilient material. By way of illustration, the at least one tensioning element may be made of steel, or of fibre-reinforced plastics, for example, carbon-fibre-reinforced plastics or glass-fibre-reinforced plastics. Advantageously, the at least one tensioning element extends over the working width (longitudinal direction of the carrier member) Advantageously, the working width is greater than 1200mm, preferably greater than 1290mm. Advantageously, the at least one tensioning element is arranged in the lower half of the aluminium carrier member.

The arrangement is preferably such that the spacing (carding nip) remains the same in the event of heating or cooling acting on the carrier element. In some embodiments, on heating, the carrier element bends away from the cylinder over the working width. The heating may take place during the run-up phase of the carding machine.

Advantageously, on cooling, the carrier element bends back towards the cylinder over the working width. The cooling may take place during the run-down phase of the carding machine.

Advantageously, a tubular element is present between the tensioning element and the carrier element.

Preferably, a rod passes through the tubular element.

Advantageously, the thermal expansion coefficients of the carrier element and the tubular element are the same or substantially the same. Advantageously, there is a heat-insulating element, a layer or the like between the curved outer surface of the tubular element and the curved inner surface of the carrier member. Advantageously, the rod is at at least one end fixable with respect to the carrier member by clamping. Advantageously, there is a clamping device at at least one end of the rod. Preferably, there is a clamping device at each of the two ends of the rod.

In certain embodiments, a sleeve having at least two flexible claws or the like is provided as clamping device.

Advantageously, the sleeve is attached to an end region of the rod by screwing, adhesive bonding or the like. In some embodiments, the clamping device or the like has at least one sloping surface. Advantageously, the carrier member has a sloping chamfer at at least one end region.

Preferably, the sloping surface of the clamping device or the like is in engagement with the sloping surface of the chamfered end region. In one embodiment, the clamping device has at least one rotatable lever arm which is used for clamped fixation.

Advantageously, clamping of the tensioning element is induced by a temperature difference between the tensioning element and the carrier member. Advantageously the temperature difference is a temperature difference that arises in operation of the flat card or roller card. In certain embodiments the at least one working element and/or functional element comprises at least one fixed carding element. In other embodiments, as well or instead, the at least one working element and/or functional element may comprise at least one revolving flat bar.

The invention also provides an apparatus on a flat card or roller card in which there is at least one working element and/or functional element, for example a fixed carding element, revolving flat bar, having an elongate carrier element between two end regions for support on the carding machine, which element has an inwardly directed (into the working region of the carding machine) region which is located opposite and spaced apart from the cylinder clothing, wherein at least one tensioning element is associated with the carrier element for axial pre-tensioning, and a clamping device is provided with which the position of the tensioning element is fixable with respect to the carrier element.

Certain illustrative embodiments of the invention are described in greater detail below with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic side view of a carding machine having one or more apparatus according to the invention; -10 -Fig. 2 shows a fixed carding element according to the invention and a detail of a side screen, showing the spacing between the carding segment clothing and the cylinder clothing; Fig. 2a shows a part of the carding element according to Fig. 2 in detail; Fig. 3 is a side view of a fixed carding element according to the invention with a carrier member, clothing strip and clothing, wherein a rod (tensioning rod) passes through the carrier element; Fig. 3a is an exploded view of part of the carrier member, the clothing back and the clothing; Fig. 4 is a side view of a side screen having a setting bend (flexible bend) for revolving flat bars and two setting bends (flexible bends) for fixed functional elements with an apparatus according to the invention; Fig. 5 is a diagrammatic view of section I -I of Fig.4 through a setting bend (extension bend) with a fixed carding element on a side screen on one side and a corresponding view on the other -11 -side; Fig. 5a is a perspective view of a sleeve nut with four claws (clamping element); Fig. Sb is a front view in section of part of a carrier member for a fixed carding element with a continuous channel and an end region of a rod (tensioning rod) with the sleeve nut (clamping element); Fig. 6a, 6b show a front view of a carrier member with the clamping element in the untensioned state (Fig. 6a) with a flat working surfaco and in the pro-tensioned state (Fig. 6b) with a concave curve; Fig. 7a, 7b show a front view of a carrier member with the clamping element and the cylinder in the cold state (Fig. 7a) and in the heated state (Fig. 7b); Fig. 8 is a diagrammatic view in section of an end region of a revolving flat bar with an embodiment of the apparatus according to the invention; Fig. 8a is a diagrammatic view of section II -II through a sub-region of the revolving flat bar according to -12 -Fig. 8; Fig. 9 is a diagrammatic view of a further embodiment of the apparatus according to the invention, and Fig. 10 is a diagrammatic view of a third embodiment of the apparatus according to the invention.

With reference to Fig. 1, a carding machine, for example a flat card TO made by Trützschler GmbH & Co.KG of Mönchengladbach, 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 guide element 9, web funnel 10, delivery rolls 11, 12, revolving flat top 13 with flat guide rollers l3a, 13b and flat bars 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 denotes the direction of rotation of the cylinder 4. The arrow A denotes the working direction. The curved arrows shown inside the rolls indicate the directions of rotation of the rolls.

In the pre-carding zone (between the licker-in 3c and the rear flat guide roller l3a) there are located, opposite the cylinder 4, a plurality of fixed carding elements 23' according to the invention and in the post-carding zone (between the front flat guide roller l3b and the doffer 5) there are located, opposite the cylinder 4, a plurality of fixed carding elements 23'' according to the invention, which are in each case arranged one next to -13 -the other -seen in the circumferential direction of the cylinder 4.

In the embodiment of Figure 2, on each side of the carding machine there is mounted, laterally on the machine frame (not shown), an approximately semi-circular rigid side screen 18, on the outer side of which, in the region of the periphery, there is concentrically mounted an arcuate rigid bearing element 19 having a convex outer surface 19' as supporting surface and an underside 19''.

The apparatus according to the invention comprises at least one fixed carding element 23 which has at its two ends bearing surfaces which lie on the convex outer surface 19' of the bearing element 19 (for example extension bend) (see Fig. 4) . At the lower face of the carrier 24 (carrier member) of the fixed carding element 23 thoro aro mounted clothing backs 25k, 252 each having respective clothings 261, 262 (carding clothings) Reference numeral 21 denotes the circle of tips of the clothings 261, 262. The cylinder 4 has a cylinder clothing 4a, for example saw-tooth clothing, around its circumference. Reference numeral 22 denotes the circle of tips of the cylinder clothing 4a. The spacing between the circle of tips 21 and the circle of tips 22 is indicated by reference letter a and is, for example, 0.20 mm. The spacing between the convex outer surface 19' and the circle of tips 22 is indicated by reference letter b. The radius of the convex outer surface 19' is indicated by reference letter r5 and the radius of the circle of tips 22 is indicated by reference letter r2. The radii r5 and r2 intersect at the centre point M of the cylinder 4. The carding element 23 according to Figure 2 consists of a carrier 24 and two clothing strips 272, 272 each of which -14 -comprises a clothing back 25k, 252 with respective clothings 26k, 262. The clothing strips 27k, 272 (carding elements) are arranged one after the other in the direction of rotation (arrow 4b) of the cylinder 4, the clothings 261, 262 (lengths of sawtooth wire) 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 backs 251, 252 are attached to the carrier 24 by means of screws 31a, 31b, respectively.

The bulk of the carrier 24 -seen in the direction of the width b -is mounted tangentially with respect to the cylinder 4.

The surface of the clothing tips -seen in side view -can be concavely curved. The circle of tips 21 of the clothings 261, 262 is in this case arranged concentrically or eccentrically with respect to the circle of tips 22 of the cylinder clothing 4a. The surface of the clothing tips -seen in side view -can be straight. In such an arrangement the tips of the clothings 262, 262 form only an approximate circle.

Reference numeral 50 indicates a clamping element which is arranged for exerting a clamping action at one end of a tensioning rod 51.

In the embodiment of Fig. 3, a fixed carding element 23 according to the invention has a carrier 24 having an attachment surface 24b, which surface is directed inwards (towards the cylinder 4) during operation. On the attachment surface 24b, there is mounted a clothing strip 27 (carding element) . The clothing strip 27 consists of a clothing back 25, to which two clothings 262 and 262 are attached. The clothing back 25 is attached to the carrier 24 by means of screws 31a, 31b, as shown in Fig. 2. The -15 -carrier 24 is in the form of a hollow profile of height h, width b and length 1 (which corresponds to the longitudinal direction L in Fig. 5) . The height of the carrier 24 and of the clothing back 25 is indicated by reference letter h2 and the height of the carrier 24, of the clothing back 25 and the clothing 26 is indicated by reference letter h3. In accordance with the exploded view in Fig. 3a, the carrier 24 has an upper surface 24a and a lower surface 24b and the clothing back 25 has an upper surface 25a and a lower surface 25b. The upper surface 25a of clothing back 25 is attached to the lower surface 24b of carrier 24. 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 member 24, that is to say in the lower half relative to the cylinder clothing 4a, there are four steel bending elements 28a to 28d which, in accordance with require-ments, form a permanently associated component of the carrier element 23. In the lower region of the longi-tudinally aligned outer surface 24c, 24d of the carrier member 24, two further bending elements 29a, 29b are permanently mounted, for example by adhesive bonding, in a recess over the length L of the carrier member 24. As shown in Fig. 3a, in the region of the lower surface 24b of the carrier member 24 a bending element 31a is inter-lockingly provided, for example adhesively bonded in a flat position, in a recess. Further bending elements 31b to 31n (not shown) may be present in this region. The bending elements 28a to 28d, 29a, 29b and 31a to 3m can advantageously be made of flat steel (steel bar) . They can be a permanent component of the carrier member 24 as a result of an interlocking or force-based connection. The -16 -permanent fixing can be effected by pressing-in, adhesive bonding, welding, riveting, screwing or the like. They can be of strip-like or similar construction.

In the region of the foot plate 24' of the aluminium carrier member 24, that is to say in the lower half viewed towards the cylinder clothing 4a, there is a sleeve nut 50a which is arranged at one end of a rod 51 (see Fig. Sb) . The rod extends continuously over the length L of the carrier member 24.

Fig. 4 shows a part of a flat card, including the main cylinder region, with which is associated a revolving flat top. A side screen 18a (the side screen lOb on the other side is shown in Fig. 5) is shown with a setting bend l7a (flexible bend) for the revolving flat bars 14 and two setting bends 19'a, l9''a (extension bends) for fixed functional elemonts (fixed carding elements, extraction hoods) . The setting bend 17a is arranged in the region of the upper periphery of the side screen 18a. In the two lateral peripheral regions of the side screen l8a there are two setting bends 19'a, 19''a. As positioning devices, positioning spindles 36' to 36 and 37' to are associated with the setting bends 19'a, 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 l8a and by their other end on the setting bend l9''a. The setting bend 19'a is arranged between licker-in 3c and flat guide roller 13a, that is to say in the pre-carding zone. On the setting bend 19'a there are mounted fixed functional elements, which in the example of Figure 4 are non-clothed -17 -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 flat guide roller 13b and doffer 5, that is to say in the post-carding zone. On the setting bend 19''a there are mounted fixed 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 numeral 35a denotes a portion of the machine frame and reference numeral 38a denotes a lower card bend.

Fig. 5 shows a portion of the cylinder 4 with a cylindrical surface 4f of its wall 4e and 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 sawtooth. 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 working surface provided with points. Fibres should be processed as evenly as possible on the working surface (clothing) . The carding work is performed between the oppositely located clothings 26k, 262 (see Fig. 2) and 4a (see Fig. 2) . It is substantially influenced by the position of one clothing with respect to the other clothing and by the clothing spacing a between the tips of the teeth of the two clothings 261, 262 and 4a. The working width of the cylinder 4 is a determining factor for the working width L of all other working elements of the carding machine, especially for the revolving flats 14 (Fig. 1) or fixed cards 23', which together with the cylinder 4 card the fibres evenly over the entire working -18 -width. In order to be able to perform even carding work over the entire working width 11, the settings of the working elements (including those of additional elements) must be maintained over that working width 11. The working S width L is, for example, 1300 mm. The cylinder 4 itself can, however, become deformed as a result of the drawing-on of the clothing wire, as a result of centrifugal force or as a result of heating caused by the carding process.

The journals of the cylinder 4 are mounted in bearings which are mounted on the fixed machine frame (not shown) The diameter, for example 1250 mm, of the cylindrical surface 4f, that is to say twice the radius r1, is an important dimension of the machine. The side screens 18a, 18b are attached to the two machine frames 35a, 35b, respectively (see Fig. 4) . The extension bends 19a, 19b are mounted on the side screens iSa, 18b, respectively.

The circumferential speed of the cylinder 4 is, for example, 35 m/sec. The fixed carding elements 23' according to the invention are attached to the extension bends 19a, 19b by screws 20a, 20b. Reference letters Si and S2 denote the end faces of the fixed carding element *)Q, L3 In the region of the carrier member 24 facing towards the cylinder clothing 4a there is a continuous channel 41 (see Fig. Sb) which is introduced into the aluminium carrier member 24 during extrusion. A rod 51 passes through the channel 41 in the axial direction as clamping element, which rod has a sleeve nut SOa, SOb at each of its two ends. Using the sleeve nuts SOa, SOb as a clamping device it is possible to fix the position of the rod Si with respect to the carrier member 24 and accordingly the pre-tensioning or concave bending of the carrier member 24 -19 -(profile) An illustrative sleeve nut 50 according to Fig. 5a has a head 50' having approximately the shape of a truncated cone, which is adjoined by a hollow cylinder 50'' having an internal thread 505. The head 50' has four resiliently deformable claws 50 to 504, which are separated from one another by through-slots. The claws S0 to 504 each have a sloping surface 5Q* which slopes in the direction of the hollow cylinder 50''.

Referring to Fig. Sb, the foot region of the aluminium carrier member 24 (a detail of which is shown) has a continuous channel 41 through which the rod 51 passes, the end regions of the rod 51 projecting out of the channel 41. Between the curved outer surface of the rod 51 and the inner wall surface of the channel 41 -each of which is circular in cross-section -there is a spacing d. In the resulting hollow-cylindrical space there is an aluminium tube 52 which has in each of its two end regions an external thread 53a (and 53b) (not shown) onto which a respective sleeve nut SOa, SOb has been screwed by means of its internal thread S0. The conically tapering sloping surfaces 50* of the sleeve nut are in contact with conically tapering sloping surfaces 24* (chamfers) of the carrier member 24. Air is present as insulator between the curved outer surface of the aluminium tube 52 and the inner wall surface of the channel 41. It is also possible for an insulating material, for example foam rubber or the like, to be provided.

Fig. 6a and 6b show an illustrative arrangement of a carrier element 23 with the rod 51 including the sleeve nuts SOa, SOb in the cold state. While according to Fig. Ga no pre-tension has been applied to the carrier member -20 - 24, the carrier member 24 in accordance with Fig. 6b has been pre-tensioned (compressed) by the tensioning rod 51, a concave curve of height x having been produced in the carrier member 24 over its length L, with the clamping sleeve nuts 50a, SOb fixing the position of the tensioning rod 51 with respect to the carrier body 24.

Fig. 7a shows an embodiment in which a carrier element 23 (that is to say the carrier member 24 with the rod and including the clothing 26 (not shown)) is mounted on the carding machine in accordance with the situation shown in Fig. 6b so as to be located opposite and spaced apart from the cylinder 4 (see Fig. 5) but in the cold state and at room temperature. Fig. 7b shows the situation after the warm-up phase, in which the carding nip a is uniform. The carrier member 24 rests with its sloping surfaces in contact with the sloping surfaces of the sleeve nuts, so that when the temperature of the carrier member 24 rises the carrier member is unable to increase in length L but instead its radial outward bending increases. As a result, a "bimetal-equivalent" effect is produced. As a result of the heating, the carrier element 24 has a concave curve of height y and the casing of the cylinder 4 has a convex curve, the spacing between the concave curve and the convex curve being the same at all locations. Accordingly, only the carrier element 23 reacts passively to the thermal expansion and contraction of the cylinder 4. Passive compensation for the sagging that occurs on heating or cooling is effected.

Because compensation for thermal expansion usually requires movement of the carrier element 23 in the radially outward or radially inward direction, it should be ensured that movements in both directions are possible -21 - (this consideration applies to all embodiments) . That is to say, heating and cooling must be taken into account.

In the embodiment of Fig. 8, in a flat bar 14 for a revolving flat top 13 (see Fig. 1), a steel rod 51 is located freely in an aluminium tube 52. The aluminium tube 52 has in turn been provided with insulation on its outer diameter and has been pushed into a channel 41 in the carrier member 14' of the flat bar 14. The openings of the channel (see Fig. Sb) on the left-hand and right-hand sides each have a chamfer. A slotted clamping sleeve 50a is then screwed onto the external thread of the aluminium tube 52 until the chamfers are in contact with one another, it being necessary to ensure that the sleeve 50a is screwed in only to the extent that there is still very slight play between the rod 51 and the sleeve SOa. The sleevos SOa are firmly adhosively bondod to the aluminium tube 52.

When the machine is not in operation, the overall temperature of the flat bar 14 changes uniformly, that is to say the aluminium flat bar 14 and the aluminium tube 52 expand by the same amount. No pressure is exerted on the clamping sleeve 50a at the chamfer. If, however, the temperature of the flat bar 14 then increases as a result of its being heated on one side, a difference in temp-erature between the aluminium flat bar 14 and the aluminium tube 52 is to be expected. The tube 52 will be cooler than the heated flat bar 14. This can be explained by the fact that the only thermal bridge to the aluminium tube 52 is the clamping sleeve 50. The four "claws 50 to 504" of the sleeve head 50' are compressed and exert pressure on the tensioning rod 51. Clamping is effected and as the heating increases the flat bar 14 bends and -22 -compensates for the deformation of the cylinder 4.

The apparatus according to the invention provides targeted clamping in the event of a difference in temperature within the flat bar 14 and/or the fixed carding element 23. An important concept is that a clamped connection between tensioning rod and carding element is not made until the machine is in operation, when the flat bar is being heated on one side from below by the carding work. As long as the flat bar is not in operation, the rod is able to move freely in the channel of the extruded aluminium profile. If the ambient temperature rises, the rod and the carding element can expand unaffected by one another. No curvature is produced. It is only when the flat bar is being heated on one side by the carding work that a clamping mechanism effects a firm connection between rod and flat bar. On heating, the aluminium carrier member exerts a tensile force on the tensioning rod 51 by way of the clamping nuts. The aluminium carrier member expands, exerting pressure by way of its sloping surfaces on the sloping surfaces of the clamping nuts. The clamping nuts are clamped on the tensioning rod 51 and pull the latter outwards. On cooling, the process takes place in reverse.

The clamping rod 51 can be made, for example, of steel or a fibre-reinforced plastics. The corresponding thermal expansion coefficients are: steel (alloyed) : a = 1.61 x l0 1 steel (unalloyed): a = 1.19 x 10 -23 -glass-fibre-reinforced plastics: a = 2.5 x io-4 carbon-fibre-reinforced plastics: a = 0 x io-4 The carrier member 24 or 14' is preferably made of aluminium. The corresponding thermal expansion coefficient for the carrier member 24 or 14' and the aluminium tube 52 is: aluminium: a = 2.38 x l0 In accordance with an embodiment shown in Fig. 9, a slotted clamping sleeve 53a, 53b is provided as clamping element at each end of the steel rod 51.

In the embodiment of Fig. 10, a clamping sleeve 54a, 54b having a clamping lever is provided as clamping element at each end of the steel rod. The clamping lever is inherently pre-tensioned. When heated on one side, the tension is relieved, so that the clamping lever exerts pressure on the steel rod 51.

As can be seen from the drawings in the Figures show-ing the tensioning element (rod 51, sleeve nuts), two elements made of metals exhibiting different thermal expansion (carrier member 24, rod 51) are joined to one another in combination. The aluminium carrier member 24 rests with one of its two chamfers (sloping surfaces) against the two sloping surfaces of the sleeve nuts, so that when the temperature of the carrier member 24 rises the latter is unable to increase in length L but instead its radial outward bending increases. As a result, the spacing of the carrier element 23 from the cylinder 4 is -24 -adjusted radially: in the direction radially away from the cylinder clothing 4a in the event of an increase in temperature and in the direction radially inwards towards the cylinder clothing 4a in the event of a decrease in temperature.

The invention can be implemented both in a form having at least one tensioning element 40 alone and in a form having at least one tensioning element 40 and at least one bending element 28.

The invention has been described and explained using the particular examples of a fixed carding element and a revolving flat bar. It will be appreciated that clamping devices described herein with reference to a fixed carding element may if appropriate be used in a revolving flat bar and vice versa. The invention equally includes other working elements and functional elements, for example suction hoods, guide elements and the like, which become deformed as a result of the supply and withdrawal of heat, with their spacing from the cylinder being altered.

Claims

-25 -Claims 1. An apparatus on a oarding maohine in which there is at least one working element and/or functional element having an elongate carrier element between two end regions for support on the carding machine, which element has an inwardly directed region which is located opposite and spaced apart from the cylinder clothing, wherein at least one tensioning element is associated with the carrier element, and a clamping device is provided with which the position of the tensioning element is fixable with respect to the carrier element.
2. An apparatus according to claim 1, wherein a clamped connection between the tensioning element and the carrier element is not made until the machine is in operation.
3. An apparatus according to claim 1 or claim 2, wherein clamping of the tensioning element is induced by a temperature difference between the tensioning element and the carrier member.
4. An apparatus according to claim 3, wherein the temperature difference is a temperature difference that arises in operation of the carding machine.
5. An apparatus according to any one of claims 1 to 4, wherein the tensioning element is used for setting the degree of pre-tension and/or the radius of a concavely curved surface of the carrier element.
6. An apparatus according to any one of claims 1 to 5, wherein the tensioning element comprises a rod or bolt that extends through the carrier element in the axial direction.
7. An apparatus according to claim 5 or claim 6, wherein the rod or bolt is loose at at least one end.

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8. An apparatus according to any one of claims 1 to 7, wherein a continuous channel is present within, and extending axially through, the carrier element.
9. An apparatus according to any one of claims 1 to 8, wherein the tensioning element is permanently associated with the carrier element.
10. An apparatus according to any one of claims 1 to 9, wherein the carrier element and the tensioning element are made of materials having different thermal expansion coefficients.
11. An apparatus according to any one of claims 1 to 10, wherein at least one tensioning element forms an integral component of the carrier element.
12. An apparatus according to any one of claims 1 to 11, wherein the tensioning element and the carrier element are in the form of a bimetallic clement.
13. An apparatus according to any one of claims 1 to 12, wherein the carrier element consists of at least two different components comprising said carrier member and tensioning element.
14. An apparatus according to claim 13, wherein the component having the lower thermal expansion coefficient is associated with the side facing towards the cylinder.
15. An apparatus according to claim 13 or claim 14, wherein the component having the higher thermal expansion coefficient is associated with the side facing away from the cylinder.
16. An apparatus according to any one of claims 1 to 15, wherein the carrier member is made of a resiliently flexible material.
17. An apparatus according to any one of claims 1 to 16, wherein the carrier member is made of aluminium or an -27 -aluminium alloy.
18. An apparatus according to any one of claims 1 to 17, wherein the at least one tensioning element is made of a resilient material.
19. An apparatus according to any one of claims 1 to 18, wherein the at least one tensioning element is made of steel.
20. An apparatus according to any one of claims 1 to 18, wherein the at least one tensioning element is made of fibre-reinforced plastics.
21. An apparatus according to claim 20, wherein the fibre-reinforced plastics is a carbon-fibre-reinforced plastics.
22. Apparatus according to claim 20, wherein the fibre-reinforced plastics is a glass-fibre-reinforced plastics.
23. An apparatus according to any one of claims 1 to 22, wherein the at least one tensioning element extends over the working width of the carding machine.
24. An apparatus according to any one of claims 1 to 23, wherein the working width of the carding machine is greater than 1200 mm.
25. An apparatus according to any one of claims 1 to 24, wherein the at least one tensioning element is arranged in the lower half of the aluminium carrier member.
26. An apparatus according to any one of claims 1 to 25, wherein the spacing between working element or functional element and the cylinder clothing remains the same in the event of heating or cooling acting on the carrier element.
27. An apparatus according to any one of claims 1 to 26, wherein, on heating, the carrier element bends away from the cylinder over the working width of the carding machine.

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28 - 28. An apparatus according to claim 27, wherein the heating takes place during the run-up phase of the carding machine.
29. An apparatus according to any one of claims 1 to 26, wherein, on cooling, the carrier element bends back towards the cylinder over the working width.
30. An apparatus according to claim 29, wherein the cooling takes place during the run-down phase of the carding machine.
31. An apparatus according to any one of claims 1 to 30, wherein a tubular element is present between the tensioning element and the carrier element.
32. An apparatus according to claim 31, wherein the tensioning element comprises a rod that passes through the tubuiar element.
33. An apparatus according to claim 31 or claim 32, wherein the thermal expansion coefficients of the carrier element and the tubular element are the same or substantially the same.
34. An apparatus according to any one of claims 31 to 33, wherein there is a heat-insulating element or layer between the curved outer surface of the tubular element and the curved inner surface of the carrier member.
35. An apparatus according to any one of claims 1 to 34, wherein the tensioning element comprises a rod which, at at least one end, is fixable with respect to the carrier member by clamping.
36. An apparatus according to claim 35, wherein there is a clamping device at at least one end of the rod.
37. An apparatus according to claim 36, wherein there is a clamping device at each of the two ends of the rod.
38. An apparatus according to any one of claims 1 to 37, -29 -wherein the clamping device comprises a sleeve having at least two flexible claws.
39. An apparatus according to claim 38, wherein the sleeve is attached to an end region of the rod.
40. An apparatus according to any one of claims 1 to 39, wherein the clamping device has at least one sloping surface.
41. An apparatus according to claim 40, wherein the carrier member has a sloping chamfer at at least one end region.
42. An apparatus according to claim 41, wherein the sloping surface of the clamping device is in engagement with the sloping chamfer of the carrier member.
43. An apparatus according to any one of claims 1 to 42, wherein the clamping device has at least one rotatable lever arm which is used for clamped fixation.
44. An apparatus according to any one of claims 1 to 43, wherein the at least one working element and/or functional element comprises at least one fixed carding element.
45. An apparatus according to any one of claims 1 to 44, wherein the at least one working element and/or functional element comprises at least one revolving flat bar.
46. A fixed carding element or revolving card flat having a tensioning arrangement, substantially as described herein with reference to, and as illustrated by, any of Figs 1; 2 and 2a; 3 and 3a; 4; 5; 5a and Sb; 6a and 6b; 7a and 7b; 8 and 8a; 9; and 10.