GB2501353A

GB2501353A - Flat card or roller card working element with heat conducting webs

Info

Publication number: GB2501353A
Application number: GB201302460A
Authority: GB
Inventors: Christoph Leinders
Original assignee: Truetzschler GmbH and Co KG
Current assignee: Truetzschler GmbH and Co KG
Priority date: 2012-02-16
Filing date: 2013-02-12
Publication date: 2013-10-23
Also published as: CH706155B1; BR102013003627A2; ITMI20130067A1; CN103255507B; CH706155A2; GB201302460D0; CN103255507A; DE102012002957A1

Abstract

A working element and/or cover element 14 is arranged opposite and spaced apart from a clothed roll and extends over the entire width of the roll. The element has an elongate carrier member comprising a foot part 14b and a back part 14a having two side walls and the back part is in the form of a hollow body in cross-section. The foot part faces towards the roll absorbs operating heat and the back part faces away from the roll and is in contact with ambient air. In the interior of the hollow carrier member there are provided between the side walls 144, 145 at least one wall-like foot web (partition wall) 141 and at least two adjoining wall-like head webs142, 143, the flat foot being joined to the flat back by the foot web and the head webs. This provides an element cross-section which is optimum in terms of heat conduction.

Description

Device on a flat card or roller card in which there is arranged at least one working element and/or cover element The invention relates to a device on a flat card or roller card in which at least one working element and/or cover element is arranged cppcsite and spaced apart from a clothed roll and extends over the entire width of the roll.

In certain cases, such elements have an elongate carrier member comprising a foot part and a back part having two side walls and the baok part is in the form of a hollow body in cross-section, wherein the foot part facing towards the roll absorbs operating heat and the back part facing away from the roll is in contact with the ambient air.

In modern high performance carding machines, heating of the components and the associated change in the spacing of the components plays an increasingly important role.

The same is also true of the spacing between cylinder and flat bar. In order to be able to achieve good guality at a maximum production rate, that spacing must be kept as constant as possible. The continual increase in the production rates of new generations of carding machine also results, however, in more significant differences between the carding nip set when the machine is cold and the carding nip in the warm state. Furthermore, in the case of an individual flat bar a special situation applies in that the flat bar is not permanently involved in the carding process and accordingly continually cycles between heating and cooling. As a result, in turn, a temperature gradient develops between the clothing side of the flat bar (warm) and its back (cold) . It is precisely this temperature gradient that is responsible for the bar's becoming deformed (towards the cylinder) Modern flat bars (WO 2006/039829 A) are configured so as to produce in their interior one or more horizontally separated hollow chambers which are "filled" with air (good insulator) . On the foot part there are mounted two vertically arranged outer walls of the back part. The foot part, the two outer walls (webs) and a horizontally arranged partition wall enclose an internal cavity. The heat flows from the foot part into the two outer walls and from there is dissipated to the ambient air. As a result, the flow of heat is confined to the outer webs of the flat bar, which are in turn involved in heat exchange with the environment. This results in relatively large differences in temperature between the clothing side and the back of the flat bar.

In carding machines of current design there are utilised as carding elements for the carding process flats having flexible clothings (revolving flats) and/or fixed carding elements having all-steel clothings, 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 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 deforma-tion under the action of heat. Such deformation results 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 dissipated to the outside to a great extent by way of the carding elements. The temperature gradient within the profile cross-section necessary for that purpose results in deformation of the 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 across the various forms of the different comp-onents 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 construction (as a result of the working width and the precision of the elements) has a back several centimetres in height, the temperature will reach a significantly lower value (for example 28C) . The differenoe in temp-erature over a carding 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) and the spacing of the element from the roll.

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 quality 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 quality 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 temp-erature 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 resuit that the carding nip in the centre of the machine becomes narrower and accordingly the web becomes more uneven and the gualiny deteriorates. In addition, lateral fly can be generated.

WO 2004/106602 A discloses an element for a carding machine which can come into contact with the fibre material at least on one side, 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 revolving flat bar, 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 a device 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 cr conditions, and which enables the carding nip to be constant.

The invention provides a working element or cover element arranged to be positioned opposite and spaced apart from a clothed roll for extending over the entire axial length of the roll, having an elongate carrier member comprising a foot part and a back part, the back part having two side walls and cooperating with the foot part to form a hollow body in cross-section, the foot part in use facing towards the roll and absorbing operating heat and the back part in use facing away from the roll and being in oontact with the ambient air, wherein in the interior of the hollow carrier member there are provided between the side walls at least one foot web and at least two adjoining head webs, the flat foot being joined to the flat back by way of the foot web and the head webs.

As a result of the measure taken according to the invention, the temperature gradient of the flat is miniinised by a cross-section that is configured so as to be optimum in terms of heat conduction. This is achieved by ribs arranged substantially vertically in the flat bar, which ribs are decoupled from heat exchange with the environment by the neighbouring hollow chambers ("filled" with air) and accordingly greatly accelerate the heating of the flat back. The heat is conducted from the at least one foot web, by way of the branching head webs, prefer-ably into the upper region of the side walls. From there, the heat is released out into the ambient air. In this way, by way of the partition wall (foot web) and the branching webs, the heat is kept initially in the region of the internal cavity, conducted to the inner surface of the side walls and from there, through the side walls, released to the outside by way of the outer faces of the side walls.

Advantageously, at least one wall-like foot web (partition wall) is provided which joins the flat foot to the flat back by way of at least two adjoining wall-like head webs. Advantageously, the flat foot is joined to the flat back in such a way as to provide a substantially homogeneous temperature distribution having a very small temperature gradient or no temperature gradient in the carrier member. Advantageously, the at least one foot web and the at least two head webs run in the longitudinal direction of the carrier member. Advantageously, the head webs branch off from the at least one foot web.

Advantageously, the at least one foot web and the at least two head webs are of one-piece construction. In one advantageous embodiment, the foot web and the head webs are substantially Y-shaped in cross-section. In some embodiments three longitudinal channels are defined by said foot and head webs within the interior of the carrier member.

In a further embodiment, the carrier member has two foot webs. In yet another embodiment the carrier member has at least three head webs, which may be provided in combination with one foot web, or in combination with two foot webs as desired. The carrier member may thus enclose four or more longitudinally extending channels.

Advantageously, the foot web and the head webs are arranged parallel to the longitudinal axis of the working element. Advantageously, the head webs are joined to the foot web by one end region. Advantageously, the head webs are each joined by their other end region to an inner surface of a side wall. Advantageously, the head webs are each joined to the upper region of the side walls.

Advantageously, at least three longitudinal channels extend from one end to the other end in the interior of the back part, for example the flat back. Advantageously, at least three longitudinal channels are closed on all sides in their wall regions. Advantageously, the foot web is a rib or the like. Advantageously, the foot web and the head webs are decoupled from heat exchange with the environment by the neighbouring longitudinal channels (hollow chambers) Advantageously, the longitudinal channels (hollow charrhers) are filled with air.

In one advantageous embodiment, the foot web and the head webs are integrated integrally into the carrier member. Advantageously, at least one foot web is joined integrally to the flat foot and the head webs.

Advantageously, the at least two head webs are joined integrally to the foot web and the side walls.

Advantageously, the at least two head webs are joined to the upper regions of the side walls.

Advantageously, the width (cross-section) of the foot web decreases in the direction from the flat foot to the flat back. Advantageously, the wall thickness of the foot web is greater than the wall thicknesses of the side walls (outer walls) of the flat back. Advantageously, the wall thickness of the branching webs is greater than the wall thickness of the side walls (outer walls) of the flat back. Advantageously, the width (cross-section) of the foot web is substantially constant. Advantageously, the width (cross-section) of the head webs is substantially constant. Advantageously, the width of the foot web and the head webs is identical. Advantageously, the carrier member is an extruded aluminium hollow profile.

Advantageously, the width of the foot web is such that an optimum (large) amount of heat flows from the flat foot to the flat back.

In one embodiment, the foot web and the head webs are made of a material having higher thermal conductivity than the material for the side walls (outer walls) of the flat back. Advantageously, the foot web is fixedly joined to the foot part and the head webs.

Advantageously, the at least one foot web is arranged vertically with respect to the flat foot.

Advantageously, the working width of the carding machine is more than 1000 mm, for example more than 1200 mm.

Advantageously, a carding clothing, which co-operates with the cylinder of the carding machine, is mounted on the flat foot.

The invention also provides a revolving flat bar for a carding machine comprising the device of the invention and further provides a revolving flat top assembly for a carding machine comprising at least one said revolving flat bar.

The invention further provides a fixed carding element for a carding machine comprising a device of the invention.

The invention also provides a device on a flat card or roller card in which at least one working element and/or cover element is arranged cppcsite and spaced apart from a clothed roll and extends over the entire width of the roll, which element has an elongate carrier member comprising a foot part and a back part having two side walls and the back part is in the form of a hollow body in cross-section, wherein the foot part facing towards the roll absorbs operating heat and the back part facing away from the roll is in contact with the ambient air, wherein the interior of the hollow carrier member there are provided between the side walls at least one wall-like foot web (partition wall) and at least two adjoining wall-like head webs, the flat foot being joined to the flat back by way of the foot web and the head webs.

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 device according to the invention; Fig. 2 shows flat bars of the revolving flat top of Fig.l and a detail of a slideway, of a setting bend (flexible bend) having a side screen and of the cylinder, and also shows the carding nip between the clothings of the flat bars and the cylinder clothing; Fig. 3 is a cross-section through a revolving flat bar (foot part and back part) according to a first embodiment of the invention; Fig. 3a is a broken-away view of the foot web and the two branching head webs in accordance with Fig. 3; Fig. 4 to 7 show further embodiments of the device according to the invention; Fig. Ba is a diagrammatic side view of a revolving flat top assembly with revolving flat bars according to the invention; Fig. Sb is a diagrammatic partial section through the revolving flat top and the cylinder in accordance with Fig. Ba and Fig. 9 is a broken-away view of a carrier member having a foot web, and also the flat clothing, driver element and toothed belt.

With reference to Fig. 1, a carding machine, for example a IC flat card made by Trützschler GmbH & 00. KG of MSnchengladbach, 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 13a, 13b and flat bars 14, can 15 and coiler -10 - 16. The directions of rotation cf the rolls are indicated by curved arrows. Reference letter M denotes the centre point (axis) of the cylinder 4. Reference numeral 4a denctes the clcthing and reference numeral 4b denotes the direction of rotation of the cylinder 4. Reference letter B denotes the direction of rotation of the revolving flat top 13 in the carding positicn and reference letter C denctes the return transport directicn of the flat bars 14, with reference numerals 30', 30' r denoting functional elements and reference numerals 13a and 13b denoting flat guide rollers. The arrow A denotes the working direction.

Referring to Fig. 2, on each side of the carding machine there is provided a setting bend 17 (flexible bend) which is integrated integrally in the associated side screen 19. The setting bend 17 has a convex outer surface 17a and an underside 17b. On top of the setting bend 17 there is a slideway 20, for example made of low-friction plastics material, which has a convex outer surface 20a and a concave inner surface 20b. The concave inner surface 20b rests on top of the convex outer surface l7a and is able to slide thereon in the direction of arrows D, E. Each flat bar 14 consists of a back part 14a and a flat foot 14b. Each flat bar 14 has, at each of its two ends, a flat head, each of which comprises two steel pins 14', 14''. Those portions of the steel pins 14', 14'' that project beyond the end faces of the flat foot 14b slide on the convex outer surface 20a of the slideway 20 in the direction of the arrow B. A clothing 18 is attached to the lower face of the flat foot 14b.

Reference numeral 21 denotes the circle of tips of the flat clothings 18. The cylinder 4 has on its circumference a cylinder clothing 4a, for example a sawtooth clothing.

The tooth height of the sawteeth is, for example, h = 2 mm. Reference numeral 22 denotes the circle of tips of the cylinder clothing 4a. The spacing (carding nip) between the circle of tips 21 and the circle of tips 22 is denoted by reference letter a and is, for example, -11 - 3/1000". The spacing between the convex outer surface 20a and the circle cf tips 22 is denoted by reference letter b. The spacing between the convex outer surface 20a and the circle of tips 21 of the flat clothing 18 is denoted by reference letter c. The radius cf the convex outer surface 20a is denoted by reference letter r3 and the radius of the circle of tips 22 is denoted by reference letter r1. The radii r-and r intersect at the centre point M of the cylinder 4. Reference numeral 19 denotes the side screen. The flat bars 14 are extruded hollow profiles 14c made of aluminium having an internal cavity.

Reference numeral 23 denotes a driver element which is in engagement with the toothed belt (not shown) In the embodiment of Fig. 3, the carrier member 14c of the flat bar 14 consists of a flat back 14a and a flat foot 14b and is in the form of an extruded hollow profile.

In the interior 14d of the hollow body there is a foot web 143 in the form of a vertically arranged partition wall which, by way of two branching head webs 142 and 143 (see Fig. 3a), joins the flat foot 14b to the side walls 144 and 145, respectively, of the flat back 14a. The partition wall 14-and the branching webs 142, 143 are substantially Y-shaped in cross-section. The partition wall l4 and the branching webs 143, l4 are arranged parallel to the longitudinal axis of the flat bar 14 -which is, for example, 1290 mm long and extends across the entire working width (see Fig. Sb) . The branching webs 142, 14 are each joined by one end region to the partition wall 143. The branching webs 142, 143 are each joined by their other end region to an inner surface of a side wall 14, and 14, respectively. Tn accordance with the exemplary embodiment in Fig. 3, the branching webs are each joined to the upper region of the side walls 14, 14. In that way, three longitudinal channels 144, 14 and 145 extend from one end to the other end (end faces) in the interior 14d of the flat back 14a. The three longitudinal channels l4, 147, 14 are closed on all sides in their wall -12 -regions. The partition wall 14, and the branching webs 142, 14. are decoupled from heat exchange with the environment by the neighbouring longitudinal channels 14, 147, 148 (hollow chambers) . The longitudinal channels 14, 14,, 148 (hollow chambers) are filled with air. The partition wall 141 and the branching webs 142, l4c. are integrated integrally into the flat back Ha. The partition wall 14 is joined integrally with the foot part l4b and the branching webs 142, 14. The branching webs 14), 147 are joined integrally with the partition wall 14-and the side walls 144, 145. The two branching webs 142, 147 are joined to respective upper regions of the side walls 144, 14. The wall thickness of the partition wall 142 is greater than the wall thicknesses of the side walls 144, 14, (outer walls) of the flat back 14a (back part) The width of the partition wall 14 and the width of the branching webs 142, 143 are substantially constant. The carrier member 14c is an extruded aluminium hollow profile.

In the embodiment of Fig. 4 there are provided two foot webs 14, 1410 which are adjoined by two head webs 142, 14,. The foot webs 14), 1420 each form an acute angle with respect to the plane of the flat foot 14b. The foot webs 14), 14]) and the head webs 142, 14, are approximately X-shaped in cross-section.

In another illustrative embodiment shown in Fig. 5 there is provided a foot web 141 which is directed vertically upwards and perpendicular to the plane of the flat foot l4b and which has at its upper end a horizontal head web l4-, the two end regions of which adjoin the upper regions of the side walls 14, and 14,.

In the embodiment of Fig. 6, two foot webs 14-), 14,, are formed which grow vertically out of the flat foot 14b and in their other end regions adjoin the obliquely upwardly extending head webs 142 and 143. The foot webs 1422, 14-3 enclose a wide longitudinal channel 1424.

Fig. 7 shows another illustrative embodiment in which -13 -a foot web 14-and three adjoining head webs 142, 14, 14]5 are provided. The structure of the foot webs and head webs arranged in the internal oavity is made of a material having higher thermal oonduotivity than the material for the carrier member 14c. The structure is attached by its free end to the inner walls of the internal cavity of the carrier member 14o. The embodiment aooording to Fig. 7 can also be of one-piece construction, that is to say made of a single material.

Fig. 8a shows a revolving flat top assembly (see Fig. 1) in which a plurality of revolving flat bars 14 are drawn in directions B and C with a toothed belt 24 (see Fig. 9) . The clothing 18 of each flat bar 14 co-operates with the clothing 4a of the cylinder 4. The flat bars 14 are constructed in accordance with the invention.

Fig. Sb shows a portion of the cylinder 4 with a cylindrical face 4f of the wall 4e and cylinder ends 4c, 4d. The cylinder 4 is almost entirely encased (enclosed) on all sides: in the radial direction by the elements 25', 25'', 26 (see Fig. 1) and to the two sides of the carding machine by the elements 171, 172, 19a, 19b. As a result, scarcely any heat is radiated from the cylinder 4 to the outside (to the atmosphere) Nevertheless, the heat of the cylinder ends 4c, 4d of large surface area is especially conveyed by means of radiation to a considerable extent to the side screens 19a, 19b of large surface area, from which the heat is radiated out to the colder atmosphere.

As a result of that radiation, the side screens iSa, 19b expand to a relatively lesser degree than do the cylinder ends 4c, 4d, which results in a reduction in the size of the carding nip a (Fig. 2a) that ranges from undesirable (in terms of the result of carding) to hazardous. The carding elements (flat bars 14) are mounted on the setting bends 172, 172 (flexible bends) which are mounted on the side screens 19a, 19b. In the event of heating, the lifting of the setting bends 17a, 17b -and, as a result, of the clothings 18 of the flat bars 14 -increases to a -14 -relatively lesser extent than does the expansion of the radius r,1 of the oylinder wall 4e -and, as a result, of the clothing 4a of the oylinder 4 -, whioh results in narrowing of the oarding nip a. The oylinder wall 4e and the cylinder ends 4c, 4d are made of steel, for example St 37, having a linear thermal expansion coefficient of a = 11.5 x 1O [l/°K] . In order then to compensate for the relative differenoes in the expansion of the cylinder ends 4c, 4d and the cylinder wall 4e, on the one hand, and the side screens 19a, i9b (as a result of impeded radiation into the atmosphere because of the encasing of the cylinder 4 and free radiation into the atmosphere from the side screens), the side screens are made, for example, of aluminium having a linear thermal expansion coefficient of a = 23.8 x 10 [1/°KJ. The radial expansion of the side screens 19a, 19b is greater than the radial expansion of the cylinder 4. By that means, even though the expansion of the cylinder 4 remains the same, the machine elements, for example flat bars and/or carding bars, are displaced outwards, or lifted, in the radial direction. As a result, the undesirable reduction in the size of the carding nip a due to thermal influences is greatly reduced or made smaller. By virtue of the construction of the flat bars 14 in accordance with the invention, the thermal gradient in the flat bar 14 and uherefore the sagging of the flat bar 14 over the length e is substantially reduced, partic-ularly when the working width of the flat bar 14 is relatively great, for example 1290 mm or more.

Fig. 9 shows a broken-away view of a carrier member l4c having a foot web 14 and of the flat clothing 18, driver element 23 (connecting element) and toothed belt 24. The flat clothing 18 is part of a clothing strip which is mounted on the underside of the flat foot 14b, for example by means of a magnetic strip and a metal support.

The foot webs and head webs are in the form of continuous impermeable walls. They extend in the internal cavity 14d over the length, for example, of the flat bar -15 - 14. Between the foot webs and head webs and the inner wall surfaces of the side walls l4,, 14 there are thus formed continuous longitudinal channels 144, 147. The carrier member 14c is open at its two outer end faces. The foot webs 142, 142, l4, 1412, 14-1 grow upwards out of the flat foot l4b into the internal cavity 14d. The head webs 142, 141, 141-, l4u adjoin the foot webs and likewise extend upwards into the internal cavity 14d. In this way, the heat is conducted out of the flat foot 14b by way of the foot webs and head webs into the upper wall regions of the side walls 144, 145 and from there is radiated out into the atmosphere.

The flat back 14a comprises the two side walls 144 and 14 and an upper covering region 1421,. According to the invention the heat is preferably conducted into the upper regions of the side walls 14,, 14n and, if need be, a portion is conducted into the upper covering region 14-4 by way of an additional head web 1415 (see Fig. 7) -16 -List of reference numerals 1 feed roll

2 feed table

3a, 3b, 30 lickers-in 4 cylinder 4a cylinder clothing 4b direction of rotation of the cylinder doffer 6 stripper roll 7, 8 squeeze rolls 9 web guide element web funnel 11, 12 delivery rolls 13 revolving flat top 13a, 13b flat guide rollers 14 flat bar 14a flat back (back part) l4b flat foot l4c carrier member l4d internal cavity 14', 14'' steel pins (flat head) l4 foot web (partition wall) 142 head web 14: head web 144 side wall 14:. side wall 14, longitudinal channel 147 longitudinal channel l4. longitudinal channel 14: foot web l4 foot web 14 head web 142 foot web l4 foot web l4 longitudinal channel l45 head web -17 - 14]5 upper covering region can 16 can coiler 17, 17-, 172 flexible bends l7a outer surface 17b underside 18 flat clothing 19, 19a, 19b side screen slideway 20a outer surface 20b inner surface 21 circle of tips of the flat clothing 22 circle of tips of the cylinder clothing 23 driver element 24 toothed belt 25', 25'' functional elements 26 casing

Claims

-18 -Claims 1. A working element or cover element arranged to be positioned opposite and spaced apart from a clothed roll for extending over the entire axial length of the roll, having an elongate carrier member comprising a foot part and a back part, the back part having two side walls and cooperating with the foot part to form a hollow body in cross-section, the foot part in use facing towards the roll and absorbing operating heat and the back part in use facing away from the roll and being in oontact with the ambient air, wherein in the interior of the hollow carrier member there are provided between the side walls at least one foot web and at least two adjoining head webs, the flat foot being joined to the flat back by way of the foot web and the head webs.
2. A working element or cover element according to claim 1, wherein at least one wall-like foot web is provided which joins the flat foot to the flat back by way of at least two adjoining wall-like head webs.
3. A working element or cover element according to claim 1 or claim 2, wherein the flat foot is joined to the flat back in such a way as to provide a largely homogeneous temperature distribution having a very small temperature gradient or no temperature gradient in the carrier member.
4. A working element or cover element according to any one of claims 1 to 3, wherein the at least one foot web and the at least two head webs extend along the longitudinal direction of the carrier member.
5. A working element or cover element according to any one of claims 1 to 4, wherein the head webs branch off from the at least one foot web.
6. A working element or cover element according to any -19 -one of claims 1 to 5, wherein the at least one foot web and the at least two head webs are of monolithic construction.
7. A working element or oover element aocording to any one of claims 1 to 6, wherein the foot web and the head webs are substantially Y-shaped in cross-section.
8. A working element or cover element according to any one of claims 1 to 7, wherein the foot web and the head webs are arranged parallel to the longitudinal axis of the working element.
9. A working element or oover element aocording to any one of claims 1 to 8, wherein the head webs comprise elongate webs having first and second opposed edges and are joined to the foot web along said first edge.
10. A working element or cover element according to claim 9, wherein the head webs are each joined along their second edge to an inner surface of a side wall.
11. A working element or cover element according to any one of claims 1 to 10, wherein the head webs are each joined to the side walls in an upper region thereof.
12. A working element or cover element according to any one of claims 1 to 11, wherein the said at least one foot web and at least two adjoining head webs cooperate with said flat foot and said flat back to define at least three longitudinally extending void regions within said carrier member.
13. A working element or cover element according to claim 13, wherein said at least three longitudinal channels extend from one end to the other end of said carrier member.
14. A working element or cover element according to claim 12 or claim 13, wherein said at least three longitudinal channels are closed on all sides in their wall regions.

-20 -
15. A working element or cover element according to any one of claims 12 to 14, wherein the foot web and the head webs are decoupled from heat exchange with the environment by the neighbouring longitudinal channels.
16. A working element or cover element according to any one of claims 12 to 15, wherein the longitudinal channels are filled with air.
17. A working element or cover element according to any one of claims 1 to 16, wherein the foot web is a rib or the like.
18. A working element or cover element according to any one of claims 1 to 17, wherein said at least one foot web is joined integrally to the flat foot and the head webs.
19. A working element or cover element according to any one of claims 1 to 18, wherein the at least two head webs are joined integrally to the foot web and the side walls.
20. A working element or cover element according to any one of claims 1 to 18, wherein the foot web and the head webs are integrated integrally into the carrier member.
21. A working element or cover element according to any one of claims 1 to 20, wherein the thickness of the foot web decreases in the direction from the flat foot towards the flat back.
22. A working element or cover element according to any one of claims 1 to 20, wherein the thickness of the foot web Is substantially uniform.
23. A working element or cover element according to any one of claims 1 to 22, wherein the wall thickness of the foot web is greater than the wall thicknesses of the side walls of the flat back.
24. A working element or cover element according to any one of claims 1 to 23, wherein the wall thickness of the head webs is greater than the wall thickness of the side -21 -walls of the flat back.
25. A working element or cover element according to any one of claims 1 to 24, wherein the thickness of the head webs is substantially constant.
26. A working element or cover element according to any one of claims 1 to 25, wherein the width of the foot web and the head webs is identical.
27. A working element or cover element according to any one of claims 1 to 26, wherein the carrier member is an extruded aluminium hollow profile.
28. A working element or cover element according to any one of claims 1 to 27, wherein the thickness of the foot web Is so selected that an optimum amount of heat flows from the flat foot to the flat back.
29. A working element or cover element according to any one of claims 1 to 28, wherein the foot web and the head webs are made of a material having higher thermal conductivity than the material for the side walls of the flat back.
30. A working element or cover element according to any one of claims 1 to 29, wherein the foot web is fixedly joined to the foot part and the head webs.
31. A working element or cover element according to any one of claims 1 to 30, wherein the at least one foot web is arranged vertically with respect to the flat foot.
32. A working element or cover element according to any one of claims 1 to 31, wherein a carding clothing is mounted on the flat foot for co-operating, in use, with an opposed cylinder of a carding machine.
33. A working element or cover element according to any one of claims 1 to 32, wherein the element is a revolving flat bar for a carding.
34. A working element or cover element according to any -22 -one of claims 1 to 32, wherein the element is a fixed carding element for a carding machine.
35. A working element or cover element substantially as described herein with reference to and as illustrated by any of Figs. 1, 2, 3, 3a, 4 to 7, 8a, 8b and 9.
36. Device on a flat card or roller card fri which at least one working element and/or cover element is arranged opposite and spaced apart from a clothed roll and extends over the entire width of the roll, which element has an elongate carrier member comprising a foot part and a back part having two side walls and the back part is in the form of a hollow body in cross-section, wherein the foot part facing towards the roll absorbs operating heat and the back part facing away from the roll is in contact with the ambient air, wherein in the interior of the hollow carrier member there are provided between the side walls at least one wall-like foot web (partition wall) and at least two adjoining wall-like head webs, the flat foot being joined to the flat back by way of the foot web and the head webs.
37. A revolving flat top assembly for a carding machine comprising one or more working elements and/or cover elements according to any one of claims 1 to 35.
38. A carding machine comprising one or more working elements and/or cover elements according to any one of claims 1 to 35.
39. A carding machine according to claim 38, wherein the working width of the carding machine is more than 1000 mm, for example more than 1200 mm.