GB2186599A

GB2186599A - Automatically remedying a yarn breakage in the friction spinning process

Info

Publication number: GB2186599A
Application number: GB08703087A
Authority: GB
Inventors: Jaroslav Dykast; Stanislav Didek; Alois Stejskal
Original assignee: Vyzkumny Ustav Bavlnarsky AS
Current assignee: Vyzkumny Ustav Bavlnarsky AS
Priority date: 1986-02-13
Filing date: 1987-02-11
Publication date: 1987-08-19
Also published as: IT8719326A0; DE3703893C2; GB8703087D0; CH673475A5; IT1216881B; CS256277B1; GB2186599B; DE3703893A1

Abstract

In the process of automatically remedying a breakage of yarn formed in a wedge-like gap (21) between two counter-directionally rotating frictional surfaces (13, 14) of which one (14) is perforated and exposed to the effect of a suction field (37), the broken yarn is introduced into the spinning device along the wedge-like gap (21) by a stream of air from a pressurized nozzle (43) whereupon it is nipped at the end of said gap by a gripper (23), and its floating end portion is severed by blades 45. After re-starting the rotation of frictional surfaces (13, 14), the suction effect and the fibre supply, the yarn while being withdrawn from said nip, is spun-in to the fibres supplied to the wedge-like gap (21) through supply duct (36). <IMAGE>

Description

SPECIFICATION Automatically remedying a yarn breakage in the frictional spinning process The invention relates to automatically remedying a yarn breakage in the frictional spinning process.

Automatic thread breakage remedying processes are known with open-end rotor spinning machines where yarn is introduced back into the spinning rotor by reversing the rotation of take-off and take-up rollers, yarn being spun-in at its first contact with a fibrous ribbon in the collecting groove of the spinning rotor. Such a practice cannot be availed of in the frictional spinning process since yarn has to be led along the wedge-like gap between rotary frictional surfaces. This has heretofore been made manually in that the broken yarn end is found on the bobbin tilted off the takeup roller, threaded by means of hook along said wedge-like gap and nipped in a gripper.

After re-starting the drive of the frictional surfaces of which at least one is provided with a perforation and exposed to a vacuum effect of a suction field, the operator tilts the bobbin onto the take-up roller whereby the yarn is tensioned and released from the gripper nip so that, due to the vacuum effect, it is sucked onto fibres on the perforated frictional surface while simultaneously the fibre supply has been restored.

To automate the above described operation, it has been suggested to re-introduce the yarn end along the wedge-like gap between the frictional surface by means of a movable suction tube (DE-OS 33 17 369), or a suction nozzle situated adjacent said gap. While simultaneously reversing the rotation of take-off rollers, the yarn end is sucked into the nozzle and entrapped in a clamp. Due to the reverse rotation of frictional cylinders, the nipped yarn is untwisted, breaks at a point, and its remainder is sucked off. After simultaneously restarting the fibre supply and the drive of frictional cylinders, the yarn is withdrawn and its untwisted end is spun-in to the supplied fibres (DE-OS 34 16 456).Such a spinning-in device is too complicated, irrespective of the fact that the yarn untwisting does not allow the yarn breakage spot to be precisely located so that the untwisted yarn end has every time another length whereby the spinning-in result is negatively influenced.

It is an object of the present invention to provide a relatively simple method of automatically remedying yarn breakages on working units of a frictional spinning machine, and simultaneously to raise the reliability of the spinning-in process.

According to one aspect of the invention, there is provided a method of automatically remedying a yarn breakage in the frictional spinning process on a working unit of a frictional spinning machine for spinning textile fibres based upon the open-end spinning principle, wherein fibres supplied to a spinning device of the working unit are twisted to yarn in a wedge like gap between two counter-directionally rotating frictional surfaces of which at least one is perforated and exposed to the effect of a suction field, and wherein after a yarn breakage, the yarn take-off, the fibre supply, the drive of frictional surfaces and the suction field effect are interrupted, after interrupting the suction field effect, yarn is returned by means of a pressure air stream oriented along the wedge-like gap whereupon at the end of said gap it is nipped in a distance from its end portion which is then severed downstream of the nip and ejected to a vacuum waste receptacle, whereupon after restarting the drive of frictional surfaces, the suction field effect and the fibre supply, the yarn breakage is remedied by withdrawing the yarn from the nip and simultaneously spinningin its end to fibres supplied to said wedge-like gap.

During the yarn breakage remedying process, the broken yarn end, impurities and fibre waste are removed, in that before the yarn spinning-in the frictional surfaces are cleaned by the pressure air stream oriented along the wedge-like gap therebetween.

The pressure air stream enables the yarn to be quickly and reliably introduced along the wedge-like gap up to the intake pipeline of a vacuum waste receptacle into which lowgrade, partly untwisted yarn end portion is ejected so that in the region of said gap an untwisted, precisely measured length of standard yarn is arrested, the end of which is always at an optimum, predetermined distance from the wedge-like gap whereby another condition for increasing the reliability of the spinning-in process is provided.

The pressure air stream is preferably availed of also for cleaning the frictional surfaces during the run-out, stop, or re-start thereof so that impurities together with fibre and yarn waste can be ejected into the vacuum waste receptacle before the actual spinning-in process.

According to another aspect of the invention there is provided apparatus for carrying out the above method in a working unit of frictional spinning machine comprising a fibre supply device, a spinning device, a yarn takeoff device and a yarn take-up device, wherein the supply device is a feed roller driven through a fibre supply coupling controlled by a thread breakage sensor, the take-off and takeup devices are take-off and take-up rollers, respectively, and the spinning device is a pair of driven cylindrical carriers of frictional surfaces of which at least one is perforated and exposed to the effect of a suction field and which form at the place of minimum distance therebetween a longitudinal wedge-like gap at one side of which a yarn guide together with a yarn take-off tube, and at the opposite side a gripper for nipping the returned yarn is arranged at the output side of the spinning device there is arranged adjacent the take-off tube a pressure air nozzle extending in parallel to the wedge-like gap and provided with an electromagnetic element controlled by the spinning-in device, said nozzle being oriented toward the gripper situated at the opposite side of the spinning device.

The simple and cost-saving arrangement of the pressure air nozzle controlled by the elec tromagnetic element, in an optional combination with the intake pipeline of the vacuum waste receptacle which latter can be made common for all of the working units of the machine, provides conditions for both remedying yarn breakages and cleaning the frictional surfaces prior to the actual spinning-in process carried out by the spinning-in device.

Therefore is is preferably that the gripper is followed by the intake pipeline of the vacuum waste receptacle and that the pressure air nozzle is arranged in that inlet portion of the take-off tube for producing a pressure air stream in said inlet portion, and a vacuum air stream in the remaining part of the take-off tube.

As is well-known, the air stream issued by such a specifically adapted pressure air nozzle entrains the neighbouring boundary air layers which produce a vacuum. Due to the location of the air pressure nozzle in the immediate proximity of the thread guide with the take-off tube, a vacuum in said tube is simultaneously produced, enabling thus the re-introduced yarn end to be sucked in.

Instead of the process of complicatedly untwisting the yarn up to the breakage thereof by reversing the rotation of frictional cylinders, an unnecessary yarn portion is removed so that between the gripper and the intake pipeline a device is provided for severing an end portion of yarn.

The yarn severing device can be embodied by any of known means such as a rubbing disc serving simultaneously for untwisting the yarn end after severing it for easy spinning-in, or the like.

For nipping the yarn in the mouth of wedgelike gap in a suitable time and at a suitable spacing from the minimum distance between the frictional surfaces, the gripper is preferably formed by electromagnetically controlled clamping means for gripping the returned yarn in a predetermined distance downstream of the wedge-like gap.

Advantages achieved by the present invention consist particularly in that the frictional spinning machine is started and yarn breakages are remedied automatically during the spinning process with a statistically high spinning-in success. Since the operator's skill is irrelevant, the spinning productivity will rise.

A preferred embodiment of the invention will hereinafter be described, by way of example, with reference to the accompanying schematic drawing, in which a spinning unit is shown partly in section, partly in perspective view.

The spinning unit consists of a spinning device 6 comprising an outer cylinder 1 having an unperforated frictional surface 13, and an inner cylinder 2 having a perforated frictional surface 14. The cylinders which are driven by not shown means are arranged one in the other so that they form a wedge-like gap 21 therebetween. Inside the inner cylinder 2 there is provided a longitudinal suction nozzle 37 which extends along said gap 21 and communicates through a suction pipeline 35 with a vacuum source (not shown). From the exterior, a supply duct 36 is introduced into the outer cylinder 1 for conveying fibres 24 supplied by a feeding device and individualized by a separating device of the spinning unit (not shown), said duct 36 being oriented toward the wedge-like gap 21.

Downstream of the spinning device 6, ie. in the yarn take-off direction, there is arranged a take-off tube 34 in the inlet portion 33 of which a pressure air nozzle 43 is arranged.

The supply of air into the nozzle 43 is controlled by an electromagnetic element 44 which in turn is controlled by a spinning-in device (not shown). At the opposite side of the wedge-like gap 21 there is provided an electromagnetically controlled and adjustable gripper 23 which is also controlled by said spinning-in device. With the gripper 23 a severing device 45 is associated for severing an end portion of yarn 11 which is then sucked through an intake pipeline 46 into a vacuum waste receptacle 47.

In operation, yarn is withdrawn from the spinning device of the spinning unit and wound on a bobbin by take-off and take-up rollers, respectively.

The spinning unit of the frictional spinning machine is supplied with fibrous material, such as a sliver, by the feeding device and opened by the separating device into discrete fibres 24 which are supplied from said separating device to the spinning device 6 through the supply duct 36 whereupon they are sucked into the elongate wedge-like gap 21 between the two frictional surfaces 13, 14, due to the vacuum effect of the suction nozzle 37 connected to the suction pipeline 35. In said gap, fibres are twisted-in onto the open end of the yarn 11 which is then withdrawn through the take-off tube 34 by the take-off rollers of the take-off device and finally wound on a bobbin by the take-up device.

In the case of a yarn breakage, the not shown spinning-in device of the frictional spinning machine sets the supply device and the take-off or take-up device out of operation, turns off the electromagnetic valve 15 of the suction pipeline 35, and stops the drive of the cylindrical carriers 1 and 2. In the next phase of the spinning-in process, the yarn end is introduced by the spinning-in device back into the take-off tube 34, blown by a pressure air stream from the nozzle 43 by turning on the electromagnetic element 44 along the wedgelike gap 21 and further through the intake pipeline 46 into the vacuum waste receptacle 47. In this way a low-grade portion of broken yarn is ejected into waste.Simultaneously, the frictional surfaces 13, 14 are cleaned by this pressure air stream, while dust and impurities together with yarn fragments are also ejected through the intake pipeline 46 into the waste receptacle 47.

After a predetermined time interval, the electromagnetic element 44 cuts off the air supply to the pressure air nozzle 43, due to a pulse released by the spinning-in device whereupon by another pulse there are energized electromagnets of the gripper 23 which clamps the introduced yarn 11. By another pulse from the spinning-in device the severing device 45 is set in operation so that the floating yarn end is severed and ejected through the intake pipeline 46 into the vacuum waste receptacle 47.

In the next phase of the spinning-in process, the drive of the cylindrical carriers 1, 2 is started eg. by engaging the electromagnetic drive coupling, further the vacuum effect of the suction nozzle 37 is restored, and the drive of the supply device is started, eg. by engaging the electromagnetic fibre supply coupling. After the fibre supply has been started, the yarn is spun-in by the spinning-in device after the predetermined time interval, said device easing the electromagnets of the gripper 23 and setting the take-off or take-up device, respectively, of the spinning unit in operation (eg. by tilting the bobbin to the take-up cylinder). Thereby the yarn end is made loose, sucked into the wedge-like gap 21 and spunin to the supplied fibres 24.

The spinning-in device can be either associated with each of the spinning units of the frictional spinning machine, or form a part of a travelling automatic spinning-in service unit which is equipped with well-known elements for controlling the above-described organs of the spinning units.

Claims

1. A method of automatically remedying a yarn breakage in the frictional spinning process on a working unit of a frictional spinning machine for spinning textile fibres based upon the open-end spinning principle, wherein fibres supplied to a spinning device of the working unit are twisted to yarn in a wedge-like gap between two counter-directionally rotating frictional surfaces of which at least one is perforated and exposed to the effect of a suction field, and wherein after a yarn breakage, the yarn take-off, the fibre supply, the drive of frictional surfaces and the suction field effect are interrupted, after interrupting the suction field effect, yarn is returned by means of a pressure air stream oriented along the wedgelike gap whereupon at the end of said gap it is nipped in a distance from its end portion which is then severed downstream of the nip and ejected to a vacuum waste, receptacle, whereupon after re-starting the drive of frictional surfaces the suction field effect and the fibre supply, the yarn breakage is remedied by withdrawing the yarn from the nip and simultaneously spinning-in its end to fibres supplied to said wedge-like gap.

2. A method according to claim 1, wherein before the yarn spinning-in the frictional surfaces are cleaned by the pressure air stream oriented along the wedge-like gap therebetween.

3. Apparatus for carrying out the method as claimed in any one of claims 1 or 2 in a working unit of frictional spinning machine comprising a fibre supply device, a spinning device, a yarn take-off device and a yarn takeup device, wherein the supply device is a feed roller driven through a fibre supply coupling controlled by a thread breakage sensor, the take-off and take-up devices are take-off and take-up rollers, respectively, and the spinning device is a pair of driven cylindrical carriers of frictional surfaces of which at least one is perforated and exposed to the effect of a suction field and which form at the place of minimum distance therebetween a longitudinal wedgelike gap at one side of which a yarn guide together with a yarn take-off tube, and at the opposite side a gripper for nipping the returned yarn is arranged at the output side of the spinning device there is arranged adjacent the take-off tube a pressure air nozzle extending in parallel to the wedge-like gap and provided with an electromagnetic element controiled by the spinning-in device, said nozzle being oriented toward the gripper situated at the opposite side of the spinning device.

4. Apparatus according to claim 3, wherein downstream of the gripper an intake pipeline of a vacuum waste receptacle is provided.

5. Apparatus according to claim 3, wherein the pressure air nozzle is arranged in the inlet portion of the take-off tube for producing a pressure air stream in said inlet portion, and a vacuum air stream in the remaining part of the take-off tube.

6. Apparatus according ta claim 3, wherein between the gripper and the intake pipeline a device is provided for severing an end portion of yarn.

7. Apparatus according to claim 3, wherein the gripper is formed by electromagnetically controlled clamping means for gripping the returned yarn in a predetermined distance downstream of the wedge-like gap.

8. A method of automatically remedying a yarn breakage in the frictional spinning process, substantially as hereinbefore described with reference to the accompanying drawing.

9. Apparatus for automatically remedying a yarn breakage in the frictional spinning process, substantially as hereinbefore described with reference to the accompanying drawing.