EP0295060A2

EP0295060A2 - Improvements in or relating to textile carding

Info

Publication number: EP0295060A2
Application number: EP88305193A
Authority: EP
Inventors: Keith Grimshaw; Brian Joseph Ennis
Original assignee: Carclo Engineering Group PLC
Current assignee: Carclo Engineering Group PLC
Priority date: 1987-06-12
Filing date: 1988-06-08
Publication date: 1988-12-14
Also published as: GB8713788D0; EP0295060A3; GB2205590A

Abstract

The taker-in roller (16) of a cotton type carding machine is provided with a trash separator in the form of a knife blade (70) pointing towards the periphery of the card-clothing on the roller followed by a card-clothed top (78) co-operating in point-to-point fashion with the card-clothing on the taker-in roller. A screen (90) extends below the feed plate (12) of the machine, spaced from the knife blade (70) and a second screen (98) extends down from the knife blade so that a region of "dead air" is created to the rear of that part of the taker-in roller which travels between the feed plate (12) and the knife blade (70).

Description

Part of the function of the cotton type carding machine is to remove trash and dust from the usable cotton fibres. The importance of this increases with the use of relatively low grades of cotton and the increasingly high standards of environmental control in textile factories. There is however a dilemma, in that increasing the degree of trash removal, especially at the feed end of the carding machine is accompanied by increased loss of usable fibres along with the trash.
It is an object of the present invention to provide a cotton type carding machine with a trash separator arrangement associated with the taker-in roller, which is adapted to effect a high degree of trash separation with relatively low loss of usable fibre. It is a further object of the invention to provide the trash separator with means for ensuring that the fibres on the taker-in roller are presented to the cylinder in a well opened and relatively evenly distributed arrangement.
According to a first aspect of this invention, the taker-in roller of a cotton type carding machine is provided with a trash separator comprising a knife blade pointing towards the periphery of the card-clothing on the taker-in roller and set close to that card-clothing, and at least one card-clothed top co-operating in point-to-point fashion with the card clothing on the taker-in roller, the said card-clothed top being located behind the knife blade in the direction of rotation of the taker-in roller, and in advance of any other knife, grid or other accessory co-operating with the taker-in roller between the said knife blade and the position at which the fibres are transferred from the taker-in roller to the cylinder, wherein a first screen extends below the feed plate or feed rollers which feed fibrous material to the taker-in roller behind of the said knife blade, and spaced from that blade, and a second screen extends downwards from the knife blade or a part on which that blade is mounted so that a region of "dead air" is created to the rear of that part of the taker-in roller which is travelling from the feed plate or feed rollers to the said knife blade.
The knife blade serves as a mote knife for separating trash from the fibres on the taker-in roller. The conventional taker-in and mote knife tends to draw an air-stream towards the first mote knife and this creates an air turbulence in the zone where the first mote knife co-operates with the taker-in roller. This turbulence reduces the effectiveness of the mote knife. The "dead air" space provided by the invention permits the formation of particle tracks (i.e. it allows a stream of trash particles to flow over the rear face of the blade whilst the usable cotton passes in another stream under the edge of the blade). Given the relatively laminar air flow conditions which occur with the present invention, it becomes possible to set the knife blade to control closely the amount of trash which is removed at the taker-in roller, thereby permitting the selection of the optimum trash removal/fibre loss relationship. Initial tests have shown a saving of 1% to 2% in fibre loss for a given degree of trash removal.
It is preferred that the knife blade is adjustable towards and away from the periphery of the taker-in roller. This is preferably achieved by securing the blade to a mounting beam extending across the width of the carding machine, by screws, each of which passes through a slot in the blade, the slots providing the adjustment.
The first and second screens together provide a trash chute from the zone of the taker-in roller between the feed plate or feed rollers and the knife blade and a trash collecting region below the taker-in roller.
According to a second aspect of the invention the taker-in roller of a cotton type carding machine is provided with a trash separator comprising a knife blade pointing towards the periphery of the card-clothing on the taker-in roller and set close to that card-clothing and at least one card-clothed top co-operating in point-to-point fashion with the card-clothing on the taker-in roller, and is characterised in that both the knife blade and the top are mounted on a rigid beam extending across the carding machine below the taker-in roller, the mounting of the knife blade on the beam permitting adjustment of the blade towards and away from the periphery of the taker-in roller and the mounting of the top permitting removal and replacement of the top.
When conventional mote knives are used under a taker-in roller, each knife extends across the machine and itself forms a simply supported beam; but sometimes foreign bodies such as nails are fed towards the mote knives and in striking the first mote knife, cause that knife to be bent or damaged, thereby reducing its effectiveness. The mounting of the knife blade on a rigid beam reduces the danger of the blade becoming distorted, and this is particularly the case if, in accordance with a preferred feature of the invention, the major part of the blade is supported by the beam on its rear face, leaving only the knife edge projecting from the beam.
It has been proposed - see United Kingdom Patent No. 960637 - to provide an arrangement under a taker-in roller comprising a triangular section edge plate and an assembly of card clothing, both supported on a beam extending across the machine. However, the edge plate is not separately adjustable towards and away from the card-clothing on the taker-in roller, so that it cannot be used to separately control the removal of trash and if the card-clothing on the beam becomes worn or damaged, it is necessary to replace the entire beam, whereas with the present arrangement, it is only necessary to replace the card-clothed top from the beam.
According to a preferred feature of this aspect of the invention, the beam is supported by brackets at each side of the carding machine, each bracket providing a buttress support resisting movement of the beam in the direction of motion of the taker-in at the beam location, there being also self-aligning mountings permitting selection of the setting of the beam relatively to the taker-in roller in the radial direction. The provision for adjustment of the setting of the beam permits the setting of the card-clothed top or tops relatively to the taker-in roller to obtain the best control over the fibres on the roller immediately following trash separation at the knife blade.
According to a third aspect of the invention, the taker-in roller of a cotton type carding machine is provided with a trash separator comprising a beam extending across the machine below the taker-in roller and carrying a knife blade pointing towards the periphery of the card-clothing on the taker-in roller and at least one card-clothed top co-operating in point-to-point fashion with the card-clothing on the taker-in roller, there being an underscreen co-operating with the taker-in roller in the zone between the trash separator and the position where the taker-in roller transfers fibres to the cylinder, the leading edge of this underscreen being spaced from the trailing edge of the beam and is characterised in that the trailing edge of the beam is formed into a feather edge to assist in creating a streamlined or laminar air flow at the position where the taker-in roller periphery moves under the leading edge of the underscreen.
Preferably a second knife blade is mounted for adjustment towards and away from the taker-in roller on the leading edge of the underscreen. This second knife blade is provided to remove a proportion of the finer trash and short fibres which have been liberated from the mass of fibres on the taker-in roller by the opening action of the card-clothed top(s) on the trash separator. In some instances, a further card-clothed top may be provided, co-operating with the card-clothing on the taker-in roller in point-to-point fashion and located immediately to the rear of the second knife blade and in advance of the underscreen.
It will be appreciated that any feature of one of the three aspects of the invention may be combined with any of the features of one of the other aspects, and in a preferred embodiment, all three aspects of the invention are present, that is to say, the taker-in roller of a cotton type carding machine is provided with a trash separator comprising a knife blade pointing towards the periphery of the card-clothing on the taker-in roller and set closed to that card-clothing and at least one card-clothed top co-operating in point-to-point fashion with the card-clothing on the taker-in roller, the said card clothed top being located behind the knife blade in the direction of rotation of the taker-in roller; both the knife blade and the top being mounted on a rigid beam extending across the carding machine below the taker-in roller, the mounting of the knife blade on the beam permitting adjustment of the blade towards and away from the periphery of the taker-in roller and the mounting of the top permitting removal and replacement of the top; there being a first screen extending below the feed plate or feed rollers which feed fibrous materials to the taker-in roller behind of the said knife blade, but spaced from that blade and a second screen extending downwards from the knife blade or a part on which that blade is mounted so that a region of "dead air" is created behind that part of the taker-in roller which is travelling from the feed plate or rollers to the said knife blade, there being also an underscreen co-operating with the taker-in roller in the zone between the trash separator and the position where the taker-in roller transfers fibres to the cylinder, the leading edge of this underscreen being spaced from the trailing edge of the beam and the trailing edge of the beam being formed into a feather edge to assist in creating a streamline or laminar air flow at the position where the taker-in roller periphery moves under the leading edge of the underscreen.
The construction and operation of a carding machine in accordance with the invention will now be described by way of example only, with reference to the accompanying drawings, in which :-

Figure 1 is a diagrammatic end view partly in section of the taker-in roller and associated parts of a carding machine, and
Figure 2 is a diagrammatic detail front view looking generally in the direction of II in Figure 2, but partly in section.

The machine illustrated in the drawings is a cotton type carding machine, that is to say, its basic carding action is effected by a card-clothed cylinder 10 the periphery of which is clothed with card-clothing - which in this construction may be metallic wire type card-clothing - the cylinder co-operating with a set of card-clothed revolving flats (not shown) or a series of card-clothed worker and stripper rollers (not shown) or a series of stationary card-clothed flats (not shown). The carding apparatus comprising the revolving flats, the roller and stripper arrangement or the stationary flats is disposed around the top portion of the cylinder 10 and hence is not illustrated in the drawings. In any event, it does not form part of the present invention.
The fibrous cotton is fed forwardly towards the cylinder 10, by a conventional feeding arrangement, which includes a stationary feed plate 12, a feed roller 14 and a taker-in roller 16. The fibres are fed between the feed plate 12 and the card-clothed feed roller 14 and transferred to the taker-in roller 16, which in turn transfers them to the cylinder 10. All this is quite conventional, and needs no further description.
Part of the function of the taker-in roller is to remove trash such as seeds, stalk, grit, short fibres and dust from the bulk of the usable cotton fibre which is submitted to the carding process, before the fibre reaches the cylinder 10. Various arrangements have been proposed for removing trash from the fibrous material on the taker-in roller as it is passing around the lower part of the taker-in roller between the feed plate 12 and the position of co-operation between the taker-in roller and the cylinder 10. A conventional arrangement includes a series of mote knives, that is to say knives arranged below the taker-in roller, one behind the other, with the knife edges set close to the periphery of the card-clothing on the taker-in roller. These mote knives simply bridge the carding machine side frames below the taker-in roller and are subject to damage if foreign bodies such as nails are fed forwardly at relatively high speed on the surface of the taker-in roller 16. The mote knives release trash which collects in the space between the side frames of the machine underneath the taker-in roller. Various forms of underscreen have also been proposed for co-operation with the card-clothed taker-in roller.
In Figure 1, there is illustrated a trash remover 18 which is provided by the present invention. The effective components of the trash remover which will be hereinafter described are mounted on a steel or aluminium beam 20 which is of substantial proportions as indicated in Figure 1, and which is arranged transversely of the machine, bridging the side frames, one of which is indicated at 22 in Figure 2. A mounting bracket 24 is secured on the inside face of each of the side frames 22 by a series of fastening bolts 26, and each mounting bracket 24 has a large cut-out 28 within which the end portion of the beam 20 is received. It will be observed from Figure 1, that an edge 30 of the cut-out 28 provides a buttress against which one edge of the beam 20 rests, this buttress support providing a reaction against any tendency for the beam 20 to move in the direction of motion of the taker-in roller 16. As will hereinafter appear however, the bottom face of the beam 20 is clear of the bottom edge of the cut-out 28. The top face 32 of the beam 20 is arcuate, and is substantially concentric with the taker-in roller 16, when the beam 20 is mounted in the position illustrated in Figure 1, where the face 32 is clear of the periphery of the card-clothing on the roller 16. (The outside diameter of the taker-in roller 16 illustrated in Figure 1 is in fact the diameter over the periphery of the card-clothing on that roller).
A mounting block 34 is secured on the inside face of each mounting bracket 24 by a pair of set-screws 36. Each mounting block 34 carries a pair of identical support arrangements 38, one of which will now be described in detail. An externally screw threaded short pillar 40 engages in a screw threaded hole 42 in the mounting block 34 and has a part spherical top face 44. A mating part spherical face is formed on a distance piece 46, the top surface of which engages with the bottom surface of the beam 20. A square headed bolt 48 passes through a clearance bore in the pillar 40 and extends below the mounting block 34. The head 50 of the bolt 48 is received in a T-slot 52 formed throughout the length of the beam 20. The mounting is completed by spherical seating washers 54, 55 and a nut 56 engaging on the lower extension of the bolt 48.
In order to set the position of the beam 20 relatively to the periphery of the taker-in roller 16, the pillars 40 are turned and this adjusts the projection of the pillars above the fixed mounting block 34. Any consequential tilting of the beam 20 is accommodated by the self-centering arrangement provided by the four part spherical bearing surfaces. When the beam 20 is correctly located, it can be locked in the selected position, by tightening the nut 56, which has the effect of pulling the bolt 48 downwardly, thereby nipping the part of the beam 20 which is between the head 50 of the bolt 48 and the pillar and distance piece 40 and 46.
It will be appreciated that by correct setting of the four pillars 40, two at each end of the beam, it is possible to closely control the location of the arcuate top surface 32 of the beam 20 relatively to the underside of the taker-in roller. This provision for a close adjustment of the setting of the beam is quite important, as will hereinafter appear.
A first knife blade 58 is received in a shallow recess 60 formed in the leading edge of the beam 20. As illustrated in Figure 1, the knife blade 58 is held in position by bolts 62 each of which passes through a vertical elongate slot 64 in the blade 58, there being a nut 66 engaging on each bolt 62, the nuts 66 being received in a longitudinally extending T-slot 68 formed in the beam 20. The top edge of the blade 58 which projects upwardly from the beam 20 is formed into a sharp feather edge 70, and the disposition of the recess 60 is such that this knife edge 70 points towards the periphery of the card-clothing on the taker-in roller 16. It will be appreciated that it is possible to adjust the setting of the knife edge 70 relatively to the card-clothing on the taker-in roller, by slackening the bolts 62 and then moving the plate 58 as permitted by the slots 64, before again tightening the bolts 62 to nip the blade 58. A significant feature of the arrangement is that by far the greater part of the blade 58 is firmly supported buttress fashion by the beam 20, only the edge portion projecting from the beam 20. Hence if the blade 58 is struck by foreign bodies such as nails, it is less likely to sustain serious distortion than is a conventionally mounted mote knife.
To the rear of the knife blade 58, in the direction of rotation of the taker-in roller, a large recess 72 is formed throughout the length of the beam 20, and this recess is intended to accomodate two card clothed tops, one of which is illustrated at 74, in series. The top 74 is of a known type used on the flats of a cotton type carding machine of the type which is equipped with stationery flats in place of the revolving flats around the upper part of the cylinder 10. Each such top essentially comprises an extruded aluminium body 76, and a large number of short strips of metallic-wire type card-clothing 78, assembled face to face in an array along the length of the body 76, so that substantially the entire top surface of the top is covered by metallic-wire type card-clothing. The card-clothing strips 78 may be secured to the body 76 in a number of ways, although in the present instance, the body 76 is formed with a recess in its top face, which has undercut inside edges, receiving correspondingly shaped ends on each of the strips 78.
The body of each top 74 fits on the base of the recess 72, and the body is held in the position illustrated in Figure 1, by a bolt 80 having its head 82 accomodated in the T-slot 52 of the beam 20, and a nut 84 accomodated in a T-slot extending throughout the length of the body 76 of the top 74. A number of bolts 82 is provided along the length of the beam 20 for tightly securing the top 74 in position in the recess 72, where the leading edge of the top is also located against an edge 86 of the recess 72.
It will be appreciated, that the metallic -wire type card-clothing 78 on the top 74 is actually tangential to the periphery of the card clothing on the taker-in roller 16, but the arc of that periphery in the region of the top is so large relatively to the width of the top from its leading edge to its trailing edge, that there is an adequate co-operation between all the teeth on the flat and the card clothing on the taker-in roller. It will also be appreciated, that the setting of the beam 20 effectively sets the position of the card-clothed top 74 relatively to the taker-in roller.
The second card clothed top which is not illustrated occupies the space in the beams 20 behind the top 74, and its construction is identical to that of the top 74. In some instances, it may not be necessary to utilise two card-clothed tops following each other, so that only a single card clothed top would be provided in the beam 20 behind the knife blade 58, and in that case, the beam 20 could be much smaller than that illustrated in Figure 1. Alternatively, more than two card-clothed tops could be employed one behind the other, so that a larger beam 20 would be required to accomodate them.
A significant advantage of the arrangement is that when the card-clothing on one of the tops 74 becomes worn or damaged, it is a simple matter to remove the entire beam 20. A completely fresh top 74 can then be inserted into the beam and locked in position. When the beam is then replaced there is no alteration to the setting of the top relatively to the taker-in roller. This is a distinct advantage over prior arrangements, notably that of United Kingdom patent specification 960637, in which the card clothing is secured directly to a beam or bar, whereby it is necessary to renew the entire beam if the card-clothing of the trash separator has to be renewed.
A non-foraminous sheet steel screen 90 is arranged behind of the trash separator 18, and extends across the full width of the machine between the side plates. As illustrated in Figure 1, the screen 90 is secured to the side plates by mounting brackets 92 and fixing screws 94. The upper edge of the screen 90 is bent rearwardly as indicated at 96, and this edge engages with the underside of the feed plate 12. If a pair of feed rollers were used in place of the feed plate 12 and roller 14, then the top edge of the screen 90 would fit close to the underside of the bottom feed roller. It will be observed, that by virtue of its mounting, the screen 90 is spaced to the rear of the dirt separator 18 by a distance of approximately 40 millimetres.
A front screen 98 also made of non-foraminous sheet metal extends across the full width of the machine, and its upper portion is secured to the rear face of the beam 20 by the bolts 62 which are used to secure the knife blade 58. In fact, the blade 58 is sandwiched between the beam 20 and the upper part of the front screen 98. The major portion of the screen 98 is substantially parallel with the screen 90, and it extends below the trash separator 18. There is thus provided a chute 100 bounded on the rear by the screen 90 on the front by the screen 98 and at the ends by the side frames of the machine.
The provision of the screen 90 and 98 ensures that during operation of the machine, air cannot be drawn into the space between the knife edge 70 and the card-clothing on the taker-in roller from the underside of the feed plate 12. It has been found that air which enters between the trash separator 18 and the taker-in roller from this position creates a turbulance which has a deleterious effect on that trash removing operation. However, the screens ensure that there is a "dead air" space indicated generally at 102 in the zone to the rear of that part of the taker-in roller which is travelling between the feed plate 12 and the knife blade 58. The provision of this "dead air" zone assists in the formation of particle tracks. That is to say, the usable fibrous material on the taker-in roller can pass relatively easily on the inside of the knife edge 70, whilst large pieces of trash are removed therefrom by the knife blade 58. It is of course the essential purpose of the blade 58 to separate the trash from the fibrous material, but this can only be effectively achieved because of the "dead air" space. In fact, tests have shown that it is possible by adjusting the setting of the blade 58 relatively to the card clothing on the taker-in roller, to obtain a very close control over the percentage of material which is taken off the take-in roller at the knife blade. It is of course important to control the quantity of material which is removed at this position, because on the one hand it is desirable to remove as much trash as possible, whilst on the other hand, one seeks to avoid removing usable fibrous material. If it is possible to exercise close control, then one can select the optimum trash removal for any particular batch of fibrous material which is being carded.
Trash removed by the blade 58 falls down the chute 100 into a collecting zone beneath the taker-in roller and between the side plates of the machine.
A relatively short underscreen 104 which conforms to the periphery of the taker-in roller 16 is mounted by brackets 106 on the side frames of the carding machine, and it will be observed that the underscreen 104 extends around the periphery of the taker-in roller from a leading edge 108 which is spaced about 10 millimetres behind the trailing edge 110 of the beam 20, to a position 112 close to the position at which fibrous material is transferred from the taker-in roller 16 to the cylinder 10. Hence, the underscreen 104 is designed to prevent disturbance of the fibrous material on the taker-in roller as it is approaching the position where it has to be transferred to the cylinder 10.
A second knife blade 114 is secured by bolts 116 and nuts 118 to a mounting plate 120 which extends across the width of the machine between the mounting brackets 106 for the underscreen 104. Provision may be made for adjusting the blade 114 relatively to the taker-in roller in the same manner as the blade 58 can be adjusted. Again, it will be noted that the blade 114 is supported by the plate 120 throughout its length, though this is not so important as with the blade 58, since it is much less likely that the blade 114 will be struck by foreign bodies.
A short gap, in the order of 8 millimetres exists between the trailing edge 110 of the beam 20 and the knife edge of the blade 114, and it will be noted that the trailing edge 110 is formed to a feather edge, which is slighlty rounded at its extremity, in order to ensure a relatively streamlined airflow around the periphery of the taker-in roller at the transition from the trash remover 18 to the blade 114 and the underscreen 104. The relatively short spacing between the beam 20 and the underscreen 104 has been found to be advantageous, as has the feathering of the trailing edge of the beam 20.
In use, the taker-in roller co-operates with the feed roller, the feed plate and the cylinder 10 in the conventional manner. As has previously been described, the first blade 58 removes trash from the fibrous material on the taker-in roller, and this trash is then conveyed down the chute 100 so that it does not clog the trash removal device itself.
Immediately after passing the knife 58, the fibrous material on the taker-in roller is submitted to a point-to-point carding action betgween the taker-in roller and the two card clothed tops 74 and this has the effect of bringing further trash to the surface of the card clothing, whilst at the same time assisting in the even distribution of the usable fibrous material on the taker-in roller.
A second trash removing operation then takes place at the blade 114, though of course less trash will be removed at this position than at the first blade 58.
The construction illustrated in Figures 1 and 2 may be modified by the provision of a further card-clothed top of the type shown at 74, to the rear of the second blade 114. Indeed, a second trash remover similar to that illustrated at 18, may be fitted in place of the underscreen 104 with its blade 114 or alternatively, such a second trash removal device 18 may be followed by a very short underscreen.

Claims

1. A cotton type carding machine in which the taker-in roller is provided with a trash separator comprising a knife blade (70) pointing towards the periphery of the card-clothing on the taker-in roller (16) and set close to that card-clothing, and at least one card-clothed top (78) co-operating in point-to-point fashion with the card-clothing on the taker-in roller, the said card-clothed top being located behind the knife blade in the direction of rotation of the taker-in roller, and in advance of any other knife, grid or other accessory co-operating with the taker-in roller between the said knife blade and the position at which the fibres are transferred from the taker-in roller to the cylinder, characterised in that a first screen (90) extends below the feed plate (12) or feed rollers which feed fibrous material to the taker-in roller behind of the said knife blade, and spaced from that blade, and a second screen (98) extends downwards from the knife blade (70) or a part on which that blade is mounted so that a region of "dead air" is created to the rear of that part of the taker-in roller which is travelling from the feed plate or feed rollers to the said knife blade.

2. A cotton type carding machine as claimed in Claim 1, characterised in that the knife blade (70) is adjustable towards and away from the periphery of the taker-in roller (16).

3. A cotton type carding machine as claimed in Claim 2, characterised in that the blade (70) is secured to a mounting beam (20) extending across the width of the carding machine, by screws (62, each of which passes through a slot (64) in the blade, the slots providing the adjustment.

4. A cotton type carding machine as claimed in any one of Claims 1 to 3, characterised in that the first and second screens are arranged so that they provide a trash chute from the zone of the taker-in roller between the feed plate (12) or feed rollers and the knife blade (70) and a trash collecting region below the taker-in roller.

5. A cotton type carding machine having a taker-in roller provided with a trash separator comprising a knife blade (70) pointing towards the periphery of the card-clothing on the taker-in roller (16) and set close to that card-clothing and at least one card-clothed top (78) co-operating in point-to-point fashion with the card-clothing on the taker-in roller,characterised in that both the knife blade (70) and the top (78) are mounted on a rigid beam (20) extending across the carding machine below the taker-in roller, the mounting of the knife blade on the beam permitting adjustment of the blade towards and away from the periphery of the taker-in roller and the mounting of the top permitting removal and replacement of the top.

6. A cotton type carding machine as claimed in Claim 5, characterised in that the beam (20) is supported by brackets (24) at each side of the carding machine, each bracket providing a buttress support resisting movement of the beam in the direction of motion of the taker-in (16) at the beam location, there being also self-aligning mountings (48,54) permitting selection of the setting of the mean (20) relatively to the taker-in roller (16) in the radial direction.

7. A cotton type carding machine having a taker-in roller provided with a trash separator comprising a beam (20) extending across the machine below the taker-in roller (16) and carrying a knife blade (70) pointing towards the periphery of the card-clothing on the taker-in roller (16) and at least one card-clothed top (78) co-operating in point-to-point fashion with the card-clothing on the taker-in roller, there being an underscreen (104) co-operating with the taker-in roller in the zone between the trash separator and the position where the taker-in roller transfers fibres to the cylinder (10), the leading edge of this underscreen being spaced from the trailing edge of the beam characterised in that the trailing edge of the beam (20) is formed into a feather edge (110) to assist in creating a streamlined or laminar air flow at the position where the taker-in roller periphery moves under the leading edge of the underscreen.

8. A cotton type carding machine as claimed in Claim 7, characterised in that a second knife blade (108) is mounted for adjustment towards and away from the taker-in roller on the leading edge of the underscreen.

9. A cotton type carding machine as claimed in Claim 8, characterised in that a further card-clothed top is provided, co-operating with the card-clothing on the taker-in roller (16) in point-to-point fashion and located immediately to the rear of the second knife blade (108) and in advance of the underscreen.

10. A cotton type carding machine having a taker-in roller and characterised by the combination of a trash separator comprising a knife blade (70) pointing towards the periphery of the card-clothing on the taker-in roller (16) and set closed to that card clothing and at least one card clothed top (78) co-operating in point-to-point fashion with the card-clothing on the taker-in roller, the said card-clothed top being located behind the knife blade (70) in the direction of rotation of the taker-in roller; both the knife blade and the top being mounted on a rigid beam (20) extending across the carding machine below the taker-in roller, the mounting of the knife blade (70) on the beam permitting adjustment of the blade towards and away from the periphery of the taker-in roller and the mounting of the top (78) permitting removal and replacement of the top; there being a first screen (90) extending below the feed plate (12) or feed rollers which feed fibrous materials to the taker-in roller behind of the said knife blade, but spaced from that blade and a second screen )98) extending downwards from the knife blade or a part on which that blade is mounted so that a region of "dead air" is created behind that part of the taker-in roller which is travelling from the feed plate or rollers to the said knife blade, there being also an underscreen (104) co-operating with the taker-in roller in the zone between the trash separator and the position where the taker-in roller transfers fibres to the cylinder, the leading edge of this underscreen being spaced from the trailing edge of the beam (20) and the trailing edge of the beam being formed into a feather edge (110) to assist in creating a steamline or laminar air flow at the position where the taker-in roller periphery moves under the leading edge of the underscreen.