In a conventional revolving flat-type carding machine, each fiat is provided at each end with a fiat end which, on the inside bevel surface of the flat, slides on the respective flexible bend. The flats are connected to each other in an endless arrangement by a roller and link chain at each side of the machine. At each end, each flat has a nug which is engaged by the teeth of driven sprocket wheels at the forward or rearward ends of the travel of the flats on the machine. Thus, the drive is transmitted from the sprocket wheels through the nugs of the flats in engagement with the sprocket wheels and then through the chains. In operation, the sprocket wheels cause the whole set of flats to travel around an endless path; said path having an inner run, during which the flat ends slide on the flexible bends in a path which is concentric with the carding cylinder and an outer run, which is generally parallel with the inner run but may deviate from a truly parallel path where the chains pass over tensioning idler rollers. The inner and outer runs are joined at the forward or rearward ends by short sections of the flats, where the nugs are in engagement with the driven sprocket wheels.

A problem associated with the conventional revolving flat arrangement is that of wear in the chains. Since the total weight of a set of revolving flats is substantial, a considerable load is placed on all the roller and link connections in the chain, resulting in wear at each connection. The cumulative wear has to be taken up by periodic adjustment of the idler rollers over which the chains pass, an operation which requires skilled attention and results in significant periods of "down-time", that is to say periods when the machine has to be stopped. It is a first object of the present invention to mitigate the problem of chain wear.

Another problem is that of nug wear, which is caused because the nugs are also placed under load each time they are in engagement with the

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sprocket wheels. If a nug becomes badly worn, this may necessitate changing the entire flat, or, if the flat has detachable flat ends, at least changing the flat end. A second object of the invention is to address the problem of nug wear. 5 According to a first aspect of the invention, there is provided a set of flats for a revolving flat-type carding machine, having its flats connected together at least at one side of the set by a flexible belt, the connection between a flat and the belt being effected by a releasable element secured to the flat by means extraneous to the belt but which, in the engaged position, 10 causes the belt to be nipped between part of the flat and the releasable element.

Essentially therefore, the invention comprises replacing the conventional chains with belts, which have been found to give major advantages. In the first place, the problem of wear, which is encountered with chain

15 connections, is almost entirely overcome, because the belt provided by said first aspect, does not extend due to wear.

Secondly, the belt is of very simple construction compared to a roller and link chain and the absence of moving parts within the belt makes maintenance simpler and cheaper than that necessary with a chain. 20 Preferably, each belt is nipped between part of the flat itself and a removable element such as a replaceable flat end. In a preferred construction, the belt and flat have interengaging toothed formations. This allows the belt to be used to determine the spacing between adjacent flats; in the conventional arrangement this spacing is ensured by the pitch of the chain. 25 Preferably, the belt is a toothed belt, usually referred to as a timing belt and the flat is formed with one or more longitudinally extending recesses for receiving the teeth on the belt. In the preferred construction, the flat has

three longitudinally extending recesses at each end for the acceptance of three teeth on the belt.

According to a second aspect of the invention, there is provided a flat for a revolving flat-type carding machine comprising; a flat body made as an extrusion and providing the flat flange to accept a card-clothed "top" and having at least one longitudinally extending groove in exposed faces at each end of the body on the opposite surface of the flange to that which receives the "top"; two belts each having at least one tooth on its underside engaged respectively in the exposed groove(s) at the end of the flat body; a pair of flat ends each of which includes a wearing surface for engagement on a guide roller of the carding machine and releasable securing means for securing each flat end to the flat body in a location such that it prevents disengagement of the belt at that end of the flat from the exposed groove(s).

According to a preferred feature of the second aspect of the invention, a wearing pad or clip is releasably fitted into each end of the flat body, to provide a wear resisting surface for engagement on the flexible bend at that side of the carding machine. Preferably, the flange of the flat is formed with an undercut recess at each end of its face and each of the wearing pads has a formation complimentary to the undercut recess, so that each wearing pad can be slid into the undercut recess at each end of the flat body to secure the wearing pad to the flat body. Preferably, each wearing pad has a locating pip on the part which is received in the undercut recess of the flat body and there is a corresponding dimple to receive the locating pip on the wearing pad, so that the wearing pad can be secured in the desired longitudinal location by the "snap-in" effect of the dimple and locating pip.

According to another preferred feature of the second aspect of the invention, the securing means for each flat end comprises a headed set screw engagable in a clearance hole in the flat end and a screw-threaded hole in

the flat body, the head of the set screw providing an effective nug on the end of the assembled flat.

The flat may be fitted with a "top" as described in the specification of U.K. Patent Publication Number 2 233 008. According to a third aspect of the invention a flat for a revolving flat-type carding machine comprises a flat body and two releasable flat ends each secured to its respective end of the body by a screw, the head of which is located, when the screw is tightened, into the flat end securing condition, so that it provides a nug for engagement with the driving sprocket wheels of a carding machine. Therefore, each screw is used for the dual purpose of securing its respective flat end and providing a nug.

In a preferred construction, the screw passes through an upstanding flange of the flat end into a screw-threaded hole in the end of the flat body. Preferably, the flat end is formed with a spigot located in a locating hole in the end of the flat body, and this spigot may be concentric with the hole in the flange for the securing screw, the locating hole in the flat body being concentric with the screw.

The invention will now be described by way of example only, with reference to the accompanying drawings, in which;- Figure 1 is an exploded perspective view showing one end of a flat, and

Figure 2 is a detail section showing a connection. A flat is built up from a series of components, the basic flat body comprising an extrusion made in aluminium alloy. Since the flat is subjected to significant applied loads in use and acts as a beam supported at its ends, it has been customary to make flats in cast iron, largely because of that material's good resistance to bending. However, there are attendant disadvantages, predominantly the relatively high weight of the cast iron flat.

so that the full set of revolving flats is very heavy. Besides the obvious manipulation problems, the power required to move the flats is also considerable, particularly that the flats are sliding on the flexible bends of the machine. It is to be noted that in cross-section, the flat body 10 is T-shaped, comprising a flat flange 12 (to which the card clothing "top" 14 is clipped) and a relatively deep web 16 which is formed integral with the flange 14. The web 16 gives the body 10 sufficient rigidity to enable it to stand up to the applied bending loads in use, and it is this which enables the body 10 to be made in aluminium alloy.

The body 10 is formed by extrusion and the flange 12 is formed during the extrusion process, with a series of three longitudinally extending grooves 18. Thereafter, two wide dovetail cross-section recesses 20 are machined in the end of its operative ("top" receiving) face. At each end (only one end is shown in the drawings) the body 10 is fitted with a flat end 22 and a wearing pad 24. The latter is a small pad made from phosphor bronze or plastic, impregnated with oil or carbon, having a concave undersurface 26 (shaped so as to fit on the outer periphery of one of the flexible bends of the carding machine) and a spigot 28, which is shaped so that it is a close fit in a dovetail shaped recess 20. Each pad 24 is formed with a locating pip 30, which is adapted to co-operate with a dimple (not visible in Figure 1) in the flange 12, so that when the pad 24 is slid into the end of the recess 20 and the pad arrives at the correct endwise location in the body, the locating pip engages in the dimple, so that the pad 24 is correctly located until force is applied to it for the purpose of removing the pad.

The two pads 24, one at each end of the flat, enable the flat to slide on the flexible bends in the conventional manner and the impregnated lubricant

is released as the pads wear. When the pads need replacing, this can be done on the machine without removing the entire flat, as was previously necessary with conventional cast iron flats, in which the flat ends are integral with the flat body. Each of the flat ends 22 is a cast element which may be made, for example, in cast iron or phosphor bronze, and has an upstanding web 32, from which there extends a flange 34. A short boss 36, see Figure 2, projects from the inner face of the web 32, and this boss 36 is a push- fit in a circular recess 38, formed in the end of the web 16 of the flat body. As is clear from Figure 1, the web 16 of the flat body terminates short of the end of the body, that is to say, the flange 12 projects beyond the end of the web. This is achieved by milling away the end portions of the web 16, to expose the flange 12 with its three longitudinally extending grooves 18.

A set screw 40 is provided and there is a clearance hole 42 through the web 32 of the flat end 22 for the screw 40. In addition, there is a screw-threaded hole 44 formed in the end part of the web 16 of the flat body, to receive the set screw 40. Thus, when the boss 36 is pushed into the recess 38, the set screw 40 can be inserted through the clearance hole 42 and into the screw-threaded hole 44, for the purpose of securing the flat end 22 to the end of the web 16 of the flat body. When the flat end 22 is thus secured by the set screw 40, the head 46 of the set screw, which is cylindrical, is on the outside of the web 32 of the flat end. The arrangement is such, that this cylindrical head 46 of each set screw 40 is in longitudinal alignment with the sprocket wheels of the carding machine, such that each head 46 provides a nug for engagement with the teeth of the sprocket wheels. In this way, the set screw 40 carries out the dual functions of securing the flat end 22 in position on the flat body, and also providing the necessary nug.

The flange 34 has a shallow concave formation 48 in its top surface, as seen in Figure 1 , provided for the purpose of engaging on the guide rollers at each end of the path of the revolving flats on the carding machine. This concave surface 48 is a surface which is subjected to wear in use and, with the conventional monolithic flat, when this surface becomes badly worn, it is necessary to remove the entire flat from the machine, for re-machining. However, with the construction illustrated, if the surface 48 becomes badly worn, it is only necessary to remove the screw 40, to allow the flat end 22 to be removed either for re-machining or, alternatively, to be discarded. In either case, a supply of flat ends will be kept at the mill, so that when the surface 48 becomes worn, it is possible to replace the flat end 22 without removing the flats from the machine and the "down-time" is kept to a minimum. Thus, the provision of the wearing pad 24, the flat end 22, and the nug 46 provided by the set screw 40, ensures that all the surfaces at the flat end which are subjected to wear in operation, form part of components which are easily removable and replaceable, without taking the flat off the machine.

At each side of the machine, there is an endless timing belt 50, which is used to connect all the flats together. The timing belt 50 is made from rubber, synthetic rubber impregnated woven textile materials or steel cords, so that, although it has the required degree of flexibility, it has good resistance against longitudinal extension. Being a timing belt, it is formed with teeth 52 in one face.

The longitudinally extending grooves 18 are formed so as to be complimentary in shape to the teeth 52 of the timing belt 50. Hence, three of the teeth 52 of the belt can be pressed into engagement with the three exposed grooves 18 at each end of the flat. Moreover, as shown in Figure 2, the flange 34 of the flat end 22 engages with the non-toothed surface of the

belt 50, when the latter is pressed into engagement with the exposed grooves 18, .so that the portion of the belt which crosses the exposed part of the flange 12, is nipped between the flange 34 and the exposed part of the flange, so that once the flat end 22 is secured in position on the fiat body, the belt is trapped with its teeth in engagement with the flange 12. The flange 34 of the flat end 22 is formed with a lip 54, which engages with the outer longitudinal edge of the belt 50 and the width of the latter is such that in its trapped position, the opposite, inner, longitudinal edge is in engagement with the end face of the web 16 of the flat body. The belt 50 extends around the path of the set of revolving flats and provides the necessary flexible connection between all the flats so that, as one flat is in engagement with the sprocket wheel which is turning that flat at one end of the travel, a pulling force is exerted from that flat through the belt, to all the other flats. Thus, the belt 50 carries out the connecting function of the ordinary roller and link chain used in a conventional revolving flat arrangement. It will be appreciated, however, that the belt 50 is much lighter than the revolving chain, so that again this tends to reduce the power requirement for moving the revolving flats. However, another important feature is that by using the belt 50 instead of the chain, the wear which takes place between the rollers and links of the chain is completely eliminated. Hence, it is not necessary to stop the machine periodically for the purpose of adjusting idler rollers to re-tension the chains due to accumulated wear. The card-clothed "top" 14 is provided with metal clips 56, and these are adapted to engage with wings 58 formed on an inverted channel shaped longitudinal top retaining element 60. The method of securing the "top" on the flat is the same as that which is described in the specification of Patent Publication Number 2 233 008 and the contents of that specification, so far as they relate to the securing of the "top" on the flat, are incorporated in this

specification. It is to be understood, however, that the particular method of securing the "top" to the flat does not form part of the present invention, since other "top" securing methods could be employed.