GB2371566A

GB2371566A - Removing short fibres from carding cylinder

Info

Publication number: GB2371566A
Application number: GB0129639A
Authority: GB
Inventors: Armin Leder; Robert Toebben
Original assignee: Truetzschler GmbH and Co KG
Current assignee: Truetzschler GmbH and Co KG
Priority date: 2000-12-11
Filing date: 2001-12-11
Publication date: 2002-07-31
Anticipated expiration: 2021-12-11
Also published as: GB2371566B; FR2817877B1; CH695617A5; FR2817877A1; CN1370862A; GB0129639D0; JP2002180335A; ITMI20012585A1

Abstract

Cover elements 17 under a carding cylinder in the return region between the doffer and licker-in define at least one gap 18a associated with suction means 25 for the removal of unwanted short fibres. An upstream air inlet 21c may be provided with a controllable flap 22 responsive to air pressure between cylinder and cover. Toothed rollers with associated suction means for the removal of longer fibres may be provided upstream of the short fibre removal means, the long fibres being returned for carding while the short fibres are collected as waste.

Description

- 1 - Carding Machine The invention relates to a carding machine including

a cylinder, a doffer, a licker-in, and covering elements, 5 between which at least one opening for separation of trash and dust is present. The invention also relates to a method of operating such a machine.

In practice, upstream of the doffer, fibre material containing long and short fibres is present on the cylinder 10 clothing. Short fibres are unwanted, since they impair the strength especially of fine yarns, in particular ring-spun yarns. The bulk of the fibre material is removed from the cylinder by the doffer with the relatively long teeth of its clothing. The proportion of short fibres contained in the 15 removed fibre material is a considerable nuisance factor in that process.

The cylinder of a carding machine typically has a high circumferential speed (more than 15 m/see) and entrains a considerable amount of air with it at its surface. At the 20 cylinder there may consequently be a partial vacuum in the circumferential region (between covering and cylinder clothing). The fibres may be held and transported on the one hand by the teeth of the cylinder clothing and on the other hand may be held against the cylinder surface by the above 25 mentioned partial vacuum. The fibre web is opened down to the individual fibre. In the case of a known apparatus

- 2 - (DE-OS 39 02 202), in the covering elements between doffer and licker-in there are openings through which the heavy elements, such as trash, are separated out by centrifugal force; dust too is removed. The lighter-weight short fibres, 5 on the other hand, remain behind, in particular because of the retentive action of the clothing teeth and the partial vacuum in the cylinder clothing.

An object of the invention is to provide a carding machine that avoids or mitigates the said disadvantages, 10 which in particular allows the proportion of short fibres in the fibre material removed from the cylinder by the doffer to be substantially reduced and enables a stronger yarn to be produced. According to the invention there is provided a carding 15 machine including a carding cylinder, a licker-in for feeding fibres to the carding cylinder, a doffer for removing fibres from the carding cylinder, a covering disposed closely adjacent to the carding machine and in a region downstream of the doffer and upstream of the licker-in, and an opening in 20 the covering, a low-pressure chamber being outside and associated with the opening such that in use fibres that are carried on the rotating cylinder are arranged to be sucked through the opening by an air flow passing into the low pressure chamber.

25 According to the invention there is also provided an apparatus on a carding machine in which below the cylinder,

- 3 between doffer and licker-in, there are arranged covering elements, between which at least one opening for separation of trash and dust is present, a suction chamber being associated with the opening, characterized in that short 5 fibres that are present in the clothing of the rotating cylinder are arranged to be sucked through the opening, the separation force acting on the short fibres being greater than the retentive force of the cylinder clothing.

According to the invention there is still further 10 provided a method of operating a carding machine as defined above, in which short fibres that are carried on the rotating cylinder are sucked through the opening by an air flow passing into the low-pressure chamber.

The measures according to the invention enable the 15 proportion of short fibres in the fibre material removed from the cylinder by the doffer to be substantially reduced, and a stronger yarn to be produced. The longer fibres are preferably caught on the teeth of the doffer clothing, so that the fibre material left - not removed - in the cylinder 20 clothing downstream of the doffer has a substantially higher proportion of short fibres. The short fibres, which at this point opened down to the individual fibre lie in the cylinder clothing, are held by the teeth of the cylinder clothing.

Because the separation force acting on the short fibres is 25 greater than the retentive force of the cylinder clothing, almost all or all of the short fibres are removed by suction.

- 4 In this way, the unwanted short fibres do not pass by way of rotation of the cylinder into the fibre material fed by the licker-in to the cylinder, and hence do not pass onto the doffer. All the good fibre processed on the carding machine 5 is consequently to a considerable extent devoid of short fibres or the proportion of short fibres therein is reduced.

Where reference is made herein to "short fibres" it should be understood that the term "short" is being used simply as a relative term in comparison to "long" because it will be the 10 shorter fibres that tend to pass through the opening. Whilst the longer fibres will not in general pass through the opening, there may of course be some long fibres that also pass through the opening.

Preferably, the low-pressure chamber has a suction 15 device connected to draw air from the chamber and maintain the pressure in the chamber below the pressure between the carding cylinder and the covering in the region of the opening. Upstream of the opening, that is in a direction against 20 the direction of rotation of the cylinder, an air gap for the supply of air is advantageously arranged in the covering.

The supply of air is preferably effected in the direction onto the cylinder clothing. The amount and/or the pressure of the feed air flow are/is advantageously adjustable. The 25 size of the air gap for the feed air is preferably

- 5 - adjustable. An air guide element is advantageously present in the region of the air gap at the end of the covering -

viewed in the direction of rotation of the cylinder. The spacing of the guide element with respect to the cylinder is 5 preferably adjustable. The strength of the feed air flow is advantageously adjustable. The feed air is advantageously forcibly drawn in from the ambient air by the rotation of the clothed roller. The air gap is advantageously connected to a source of blown air. A plurality of openings to which 10 suction is applied, each with an upstream air gap, is preferably present. A pressuremeasuring element is preferably associated with the covering with which element the static air pressure between the covering and the cylinder is measured. The measured values for the static pressure are 15 used for adjustment of the air flap.

The invention includes another advantageous apparatus on a carding machine, in which below the cylinder, between doffer and licker-in, there are arranged covering elements, between which there is at least one opening for separation of 20 trash and dust, with which opening there is associated a suction chamber, in which apparatus, in the covering, at least one take-off roller for removal of long fibres is mounted upstream of the opening against the direction of rotation of the cylinder. More than one take-off roller is 25 advantageously mounted upstream of an opening to which suction is applied. A plurality of openings to which suction

6 - is applied is preferably present, at least one take-off roller being mounted upstream of each opening. The direction of rotation of the cylinder and the direction of rotation of the take-off rollers are advantageously opposite. The take 5 off rollers preferably have a sawtoothed clothing. The teeth of the saw-toothed clothing are advantageously oriented against the direction of rotation of the take-off roller.

The take-off roller preferably has a diameter of about 100 to 300 mm. The take-off roller advantageously has a 10 circumferential speed of abut 0.5 to 5 m/sec. The short fibre material removed by suction is preferably arranged to be supplied to the waste extraction. The long fibres removed by the take-off rollers are advantageously arranged to be re-

supplied to the carding machine via the feeding device.

15 It should be understood that features described with reference to one aspect of the invention, or one embodiment of the invention, may where appropriate be employed in another aspect of the invention or another embodiment of the invention. For example, the method of the invention may 20 employ apparatus of any of the kinds described herein.

By way of example certain embodiments of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic side view of a carding machine 25 embodying the invention;

- 7 Fig. 2 is a side view of part of a carding machine similar to that shown in Fig. 1 and having an adjustable feed air opening; Fig. 2a shows a detail of the adjustable feed air 5 opening shown in Fig. 2; Fig. 3 is a side view of part of another modified form of carding machine with takeoff rollers between doffer and licker-in) Fig. 4 shows one of the takeoff rollers of Fig. 3, 10 together with its clothing and part of the cylinder and cylinder clothing; Fig. 5 is a view similar to Fig. 3 and shows an embodiment similar to Fig. 3, but with additional suction chambers, and 15 Fig. 6 is a diagrammatic side view of a carding machine embodying the invention, in which longer fibres are returned to the card feeder.

Fig. 1 shows a carding machine, for example generally of (A rd.) the kind known as a Trutzschler EXACTACARD DK 803, with feed 20 roller 1, feed table 2, licker-ins 3a, 3b, 3c, cylinder 4, doffer 5, stripping roller 6, squeezing rollers 7, 8, web guide element 9, web funnel 10, delivery rollers 11, 12, revolving card top 13 with card top bars 14, can 15 and can coiler 16. The directions of rotation of the rollers are 25 indicated by curved arrows. The letter M denotes the mid-

point (axis) of the cylinder 4. The letter A denotes the

- 8 working direction. The revolving card top 13 comprises a front card top guide roller 13a and a rear card top guide roller 13b, which rotate in the direction of the curved arrows. Beneath the cylinder 4, between doffer 5 and licker-

5 in 3c, there is a covering 17, which has two exit openings 18a and 18b, each of which is associated with a respective suction chamber 19a, lab. Upstream of the exit opening 18a, viewed in the direction of rotation 4b of the cylinder 4, there is arranged an air entry gap 21a and upstream of the 10 exit opening 18b there is arranged an air entry gap 21b.

Referring to Figs. 2 and 2a, the covering 17 consists of several covering elements 17, 17, 17...17n. A first air entry opening 21a and a further air entry opening 21c are arranged upstream of the exit opening 18a, against the 15 direction of rotation 4b of the cylinder 4. Whereas an unregulated flow of air B from the atmosphere enters through the air entry opening 21a, the air flow C entering through the air entry opening 21c can be regulated. For that purpose, an air guide element 22 is provided, which with one 20 end is mounted at a pivot bearing 23 so as to be rotatable in the direction of the curved arrows E, F. the pivot bearing being fixedly arranged on the covering element 17''. The other end of the guide element 22 points in the direction of rotation 4b. In this way, the air entry opening 21c can be 25 gradually opened or closed.

- 9 - A pressure-measuring element 24 is arranged upstream of the air entry opening 21c against the direction of rotation 4b of the cylinder 4, with which the static air pressure underneath the cylinder covering 17 (i. e. in the gap between 5 the covering 17 and the cylinder clothing 4a) is measured.

For that a purpose, a continuous bore is provided in the covering 17. The measured pressure values are used to control the guide flap 22. The guide flap 22 can be manually adjusted. The position of the guide flap 22 can also be 10 adjusted automatically (in a manner not illustrated) in dependence on the measured values of the pressure-measuring element 24.

In operation, air B and C is sucked from the atmosphere through the air entry openings 21a and 21c respectively by 15 the partial vacuum into the gap between covering 17 and cylinder surface. The air flows B and C collide with the short fibres located in the clothing 4a and loosen the hold between clothing 4a and short fibres. The short fibres are subsequently sucked through the exit opening 18a into the 20 suction chamber 19, and discharged through a channel 25/ which is connected to a source of suction (not illustrated).

By virtue of the entering air flows B and C, which exert a pressure on the short fibres, and by virtue of the suction air flow D, which exerts a pull on the short fibres, the 25 separation force acting on the short fibres is greater than the retentive action of the cylinder clothing 4a. In the

process, the short fibres are detached from the cylinder clothing to a greater degree than the longer fibres still remaining thereon.

In the arrangement shown in Fig. 3, between doffer 5 and 5 licker-in 3c, three take-off rollers 26a, 26b, 26c are associated with the cylinder 4, these rollers having a diameter of 120 mm and a circumferential speed of 3.5 m/sec.

The take-off rollers 26a, 26b, 26c, which rotate in the direction of arrow 26', have a clothing 26'', as shown in 10 Fig. 4, the teeth of which are inclined against the direction of rotation 26'. The teeth of the clothing 4a of the cylinder 4 are inclined in the direction of rotation 4b of the cylinder 4. The take-off rollers 26a, 26b, 26c consequently remove longer fibres from the cylinder clothing 15 4a, which are sucked off by a suction air flow G. H and I through a respective channel 27a, 27b, 27c. In this way, the fibre material in the cylinder clothing - viewed in the direction of rotation 4b - after the take-off roller 26a, is reduced by a substantial portion of longer fibres, that is, 20 the fibre material consists at that point predominantly of short fibres. The opening 18a through which the short fibres are sucked off by the suction chamber 19 is arranged between the take-off roller 26a and the licker-in 3a. Since the fibre web has been "thinned" by the removal of the longer 25 fibres, or has been reduced to short fibres, removal of the short fibres by suction is facilitated.

- 11 Fig. 5 shows a construction in which the feed principle is combined with the removal principle. Viewed in the opposite direction to the direction of rotation 4b, a suction chamber 19a, a take-off roller 26a, a suction chamber l9b, a 5 take-off roller 26b, a suction chamber l9c, a take-off roller 26c, and a suction chamber l9d are provided beneath the cylinder 4. Upstream of each suction chamber 19a to lOd there is a respective continuous access opening in the covering 17, which extends across the width of the machine 10 and covering 17.

In the arrangement shown in Fig. 6, the suction channels 27a, 27b and 27c for the longer fibres are connected by way of a common pneumatic collector duct 28 to the suction side of a fan 29, which is integrated in a manner known per se in 15 the air circulation system of a card feeder 30 for the carding machine. The generally longer fibres are consequently supplied back to the fibre material to be processed. The generally shorter fibres extracted through the suction chamber 19a are drawn off via a waste collector 20 (not shown) for card waste.

Claims

- 12 Claims

1. A carding machine including a carding cylinder, a 5 licker-in for feeding fibres to the carding cylinder, a doffer for removing fibres from the carding cylinder, a covering disposed closely adjacent to the carding machine and in a region downstream of the doffer and upstream of the licker-in, and an opening in the covering, a low-pressure 10 chamber being outside and associated with the opening such that in use short fibres that are carried on the rotating cylinder are arranged to be sucked through the opening by an air flow passing into the low-pressure chamber.

2. A carding machine according to claim 1, in which 15 upstream of the opening an air gap for the supply of air is arranged in the covering.

3. A carding machine according to claim 2, in which the supply of air is arranged to be directed onto the cylinder clothing. 20

4. A carding machine according to any preceding claim, in which the amount and/or the pressure of the air flow are/is adjustable.

5. A carding machine according to claim 4 when dependent upon claim 2 or 3, in which the size of the air gap for the 25 supply of air is adjustable.

- 13

6. A carding machine according to claim 5, in which an air guide element is present in the region of the air gap.

7. A carding machine according to claim 6, in which the spacing of at least a part of the air guide element from the 5 cylinder is adjustable.

8. A carding machine according to any preceding claim, including a blowing device for enhancing the air flow through the opening, the blowing device being associated with the air flow upstream of the opening.

10

9. A carding machine according to any preceding claim, including a sucking device for enhancing the air flow through the opening, the sucking device being associated with the low pressure chamber.

10. A carding machine according to any preceding claim, in 15 which there are a plurality of openings in the covering, spaced apart around the circumference of the cylinder.

11. A carding machine according to claim 10, in which upstream of each opening there is a respective air gap in the covering for the supply of air.

20

12. A carding machine according to any preceding claim, in which a pressure-measuring element is provided for measuring the static air pressure between the covering and the cylinder.

13. A carding machine according to claim 12, in which 25 measured values for the static pressure are used for adjustment of the air flow.

- 14 -

14. A carding machine according to claim 12 when dependent upon claim 7, in which measured values for the static pressure are used for adjustment of the air guide element.

15. A carding machine according to any preceding claim, in 5 which the covering is disposed below the carding cylinder.

16. A carding machine according to any preceding claim, in which at least one take-off roller is mounted in a gap in the covering upstream of the opening in the covering, the take-

off roller cooperating with the carding cylinder.

10

17. A carding machine according to claim 16, in which the take-off roller is arranged to rotate in a direction opposite to the direction of rotation of the cylinder whereby the cooperating portions of the take-off roller and the carding cylinder are arranged to travel in the same direction.

15

18. A carding machine according to claim 16 or 17, in which more than one take-off roller is provided, each take-off roller being mounted in a respective gap in the covering.

19. A carding machine according to claim 18, in which downstream of each take-off roller there is a respective 20 opening and associated low pressure chamber.

20. A carding machine according to any of claims 16 to 19, in which the take-off roller has a saw-toothed clothing.

21. A carding machine according to claim 20, in which the teeth of the saw-toothed clothing are oriented against the 25 direction of rotation of the take-off roller.

- 15

22. A carding machine according to any one of claims 16 to 21, in which the take-off roller has a diameter of about 100 to 300 mm.

23. A carding machine according to any of claims 16 to 22, 5 in which the take-off roller is arranged to rotate at a circumferential speed in the range of about 0.5 to 5 miser.

24. A carding machine according to any of claims 16 to 23, in which fibres removed by the take-off roller are arranged to be re-supplied to the carding machine via a feeding device 10 for feeding fibre material to the carding machine.

25. A carding machine according to any preceding claim, in which the short fibres sucked through the opening and passing into the low-pressure chamber are arranged to be extracted to waste. 15

26. An apparatus on a carding machine, in which below the cylinder, between doffer and lickerin, there are arranged covering elements, between which at least one opening for separation of trash and dust is present, a suction chamber being associated with the opening, characterized in that 20 short fibres that are present in the clothing of the rotating cylinder are arranged to be sucked through the opening, the separation force acting on the short fibres being greater than the retentive force of the cylinder clothing.

27. An apparatus on a carding, in which below the cylinder, 25 between doffer and licker-in, there are arranged covering elements, between which at least one opening for separation

- 16 of trash and dust is present, a suction chamber being associated with the opening, characterized in that at least one take-off roller for removal of long fibres is mounted in the covering upstream of the opening against the direction of 5 rotation of the cylinder.

28. A carding machine substantially as herein described with reference to and as illustrated by Fig. 1 of the accompanying drawings.

29. A carding machine according to claim 28, modified 10 substantially as herein described with reference to and as illustrated by Figs. 2 and 2a, or by Figs. 3 and 4, or by Fig. 5, or by Fig. 6, of the accompanying drawings.

30. A method of operating a carding machine according to any preceding claim, in which short fibres that are carried on 15 the rotating cylinder are sucked through the opening by an air flow passing into the lowpressure chamber.