Piecing method and apparatus for a spinning machine

Abstract: To provide a piecing method for a spinning machine comprising passing leading yarn Y' through a twist device T, then driving draft rollers 1, 2, which have been stopped, to remove the tip of a sliver 6 supplied from a front roller 4, and then introducing a sliver into the twist device while removing a portion of the fibers constituting it. A thin tapered portion of a sliver can be prevented from forming excessively long or frail piecing portion.

Description: Field of the Invention The present invention relates to a piecing method and apparatus for joining cut yarn for a spinning machine. Background of the Invention Known piecing methods and apparatuses draw a leading yarn out from a sliver guide entrance of a nozzle constituting a twist device before driving a draft device to resume supplying a sliver while operating the twist device to entangle fibers constituting the sliver with the leading yarn for piecing. In the conventional piecing method and apparatus, when the yarn is cut, the tip of a sliver torn between a stopped draft roller and an operating draft roller is thinned and tapered. When spinning is resumed, the cut end of the thinned and tapered sliver is drafted further, thereby increasing the length of the tapered portion. If the tapered portion is long, the piecing portion will have a long and a thin piecing portion, which is not preferable. On the contrary, if the tapered sliver is removed and a new sliver of a normal fiber density is supplied, an excessively thick piecing portion will be formed when this sliver is entangled with the leading yarn. In addition, in the conventional piecing method and apparatus, the leading yarn drawn out from the sliver guide entrance may be curled or folded by the twisting torque of the yarn or as a result of its contact with the nozzle. Under this condition, when fibers constituting a sliver are entangled with the leading yarn for piecing, a piecing portion will be thick or have an unstable form. It is an object of this invention to provide a piecing method and apparatus for a spinning machine that solves the problems of said conventional piecing method and apparatus, and that can provide a piecing portion of an appropriate strength and form. Summary of the Invention To achieve this object, this invention passes leading yarn through a twist device, then drives draft rollers which have been stopped, in order to remove the tip of a sliver supplied from a front roller, and then passes a sliver through the twist device while removing a portion of the fibers constituting the sliver. Brief Description of the Drawings Figure 1 is a side view of a sample spinning machine to which the present invention is applied, including a partial cross section. Figure 2 is a side view of the sample spinning machine to which the present invention is applied, including a partial cross section. Figure 3 is a side view of the sample spinning machine to which the present invention is applied, including a partial cross section. Figure 4 is a schematic drawing showing the tip of a sliver and the tip of leading yarn, which constitute a conventional piecing portion. Figure 5 is a timing chart for the main piecing process. Detailed Description of the preferred Embodiments Hereafter, an embodiment of this invention is will be described using Figures 1 to 5 but the present invention is not limited to that described provided that the aims of the incention are not surpassed . First, a sample spinning machine to which the piecing method and apparatus for a spinning machine according to this invention is applicable is described with reference to Figure 1. D is a draft device and a four-line draft device D is shown as an example. The draft device D is composed of a back roller 1, a third roller 2, a middle roller 3 on which an apron belt is installed, and a front roller 4. 5 is a sliver guide and the sliver 6 inserted into the sliver guide 5 and supplied to the draft device D is drawn and then supplied to a twist device, described below, in which a yarn Y is produced. A twist device T is mainly composed of a nozzle 7 that jets compressed air to generate a rotating air flow, a nozzle block 8 that supports the nozzle 7, a spindle (yarn guide tube) 9 having a insertion hole 9b and its tip 9a of which is located inside 7a of the nozzle 7, and a spindle supporting member 10 that supports the spindle 9. A plurality of air injection holes 7b for generating a rotating air flow are formed in the nozzle 7. 11 indicates an air chamber formed between the nozzle block 8 and the spindle supporting member 10, and coupled to an air suction source (not shown in the drawing) that sucks air at a low suction pressure via a suction hole 12 in order to act as a hole through which air jetted from the air injection holes 7b of the nozzle 7 escapes during spinning while sucking and removing fly fibers generated within the air chamber 11. 13 is an air blowing hole formed through the spindle 9 and the spindle supporting member 10 for generating an air flow flowing toward the tip 9a of the spindle 9. The air blowing hole 13 is connected to a source of compressed air (not shown in the drawing) via a pipe 14 coupled to the spindle supporting member 10. 15 is a cylinder wherein a lower frame 17 of the spindle supporting member 10 is attached to the tip of a piston rod 16 of the cylinder 15. Thus, the cylinder 15 can be operated to move the spindle supporting member 10 rightward and leftward in order to leave or couple the spindle supporting member 10 to or from the nozzle block 8. 18 is a suction tube and a suction port 18a of which is disposed between a sliver guide entrance 7c of the nozzle 7 and the front roller 4, and below the sliver guide entrance 7c, and which is connected to the air suction source (not shown in the drawing). 19 is an air blowing tube and its air exit port 19a is directed toward the sliver guide entrance 7c of the nozzle 7 and disposed opposite to the suction tube 18 in such a way that the sliver guide entrance 7c is located between the air blowing tube 19 and the suction tube 18, and the air blowing tube 19 is connected to the source of compressed air (not shown in the drawing) via a pipe 20. 21 is a nip roller that can contact and leave a delivery roller 22 that is constantly rotated so that the nip roller 21 comes into contact with the delivery roller 22 to transfer spinned yarn Y in the direction of the winding device (not shown in the drawing). In an operational state in which the spinning machine produces the yarn Y, the sliver 6, supplied to the draft device D from the sliver guide 5, is drawn by the draft device D and then twisted by the twist device T to produce the yarn Y. That is, fibers constituting the sliver 6 supplied to the nozzle 7 of the twist device T enter the insertion hole 9b of the spindle 9 from the tip 9a while being rotated by the rotating air flow jetted from the air injection holes 7b and are thus formed into the yarn Y. In such a normal operational state of the spinning machine, the supply of compressed air from the air blowing hole 13 is stopped and no compressed air is supplied to the air blowing tube 19. Suction air is always provided through the suction tube 18. Next, a piecing process is described with reference to Figures 2 and 3. If the yarn is cut, a detection sensor (not shown in the drawings) issues a detection signal, and the operation of the back and third rollers 1 and 2 is stopped via a clutch (not shown in the drawings) connected to the back roller 1 to halt the supply of the sliver 6. The twist device T continues to operate. The sliver 6 is torn between the third roller 2 that has been stopped and the middle roller 3 that continues rotating so that its tip is tapered. In addition, after a specified period of time, the jetting of air from the air injection holes 7b is stopped to halt the operation of the twist device T. After the operation of the twist device T has been stopped to finish the production of the yarn Y, the nip roller 21 is detached from the delivery roller 22. The cylinder 15 is then operated so as to cause the piston rod 16 to advance, thereby detaching the spindle supporting member 10 from the nozzle block 8. In addition, a head A' of a transfer arm member A, which uses a pair of drive rollers a1, a2 to grip the tip of leading yarn Y' wound in a winding package and drawn out therefrom using a publicly known suction mouse or drawn out from a separately prepared package, is disposed in proximity to a yarn exit port 9c of the spindle 9. On the other hand, a suction head S' of an air sucker member S is disposed between the detached spindle supporting member 10 and the nozzle block 8 in such a way as to place the tip 9a of the spindle 9 in close proximity to a suction hole s1 of the suction head S' or to place the tip 9a in contact with the suction hole s1. The suction head S' is subsequently operated to provide the insertion hole 9b of the spindle 9 with a suction-air flow flowing toward the tip 9a from the yarn exit port 9c while the drive rollers a1, a2 of the transfer arm member A are operated to pass the leading yarn Y' through the insertion hole 9b of the spindle 9, as shown in Figure 2. The air suction member S is then lowered and the cylinder 15 is then operated to move the piston rod 16 backward in order to couple the spindle supporting member 10 to the nozzle block 8, as shown in Figure 3. Then, compressed air is supplied to the air blowing hole 13 from the source of compressed air (not shown in the drawings) via the pipe 14 to provide through the insertion hole 9b of the spindle 9 with an air flow flowing toward the tip 9a. The air then causes the leading yarn Y' passed through the insertion hole 9b of the spindle 9 to be ejected from the sliver guide entrance 7c of the nozzle 7 and inserted into the suction tube 18 through which a suction air flow is provided. After the leading yarn Y' has passed through the insertion hole 9b of the spindle 9 and the nozzle 7, that is, through the twist device T, the transfer arm member A is returned to a specified standby position. Although the air flow flowing from the air blowing hole 13 toward the tip 9a of the spindle 9 can be continuously provided until the leading yarn Y' has been passed through the insertion hole 9b of the spindle 9 and the nozzle 7, since the leading yarn Y' may be cut due to its thickness or the length of the fibers constituting it, the air flow should be provided intermittently in several times toward the tip 9a of the spindle 9. When the leading yarn Y' is passed through the insertion hole 9b of the spindle 9 and the nozzle 7, and if a required length of leading yarn Y' has already been fed, the drive rollers a1, a2 of the transfer arm member A may be stopped in order to prevent excessive yarn Y' from being fed or may be operated to feed the yarn Y' sequentially. When air is jetted through the air blowing tube 19 toward the sliver guide entrance 7c of the nozzle 7 before or after passing the leading yarn Y' through the insertion hole 9b of the spindle 9 and the nozzle 7, that is, through the twist device T, the leading yarn Y', which has been ejected from the sliver guide entrance 7c of the nozzle 7, is sucked into and retained in the suction tube 18 in order to prevent it from being drawn, curled, or folded. Thus, a piecing portion formed by piecing the leading yarn Y' drawn in this manner has the proper thickness and has a stable form. While the operation of the twist device T is stopped, that is, the jetting of air from the air injection holes 7b is stopped, the back and third rollers 1 and 2, which have been stopped, are then restarted to transfer the sliver 6 gripped by the back and third rollers 1 and 2. At approximately the same time, compressed air is again jetted from the air blowing hole 13 for a specified period of time in order to prevent the sliver 6 from being introduced into the sliver guide entrance 7c of the nozzle 7. The sliver 6, which is prevented from being introduced into the sliver guide entrance 7c of the nozzle 7, is sucked into the suction tube 18. When the yarn is cut, the sliver 6 torn between the third roller 2 that has been stopped and the middle roller 3 that continues operation has its tip thinned and tapered. The cut end of the sliver 6 that is thinned and tapered is further drafted by the middle and front rollers 3 and 4, thereby increasing the length of a tapered portion 6a as shown in Figure 4. If the tapered portion 6a is long, the piecing portion will be long, which is not preferable, and the leading yarn Y' will even be longer. In addition, if the tip Ya' of the leading yarn Y' is located in the middle of the tapered portion 6a during piecing, a thin and weak piecing portion will be formed, thereby causing the yarn to be cut at this portion. To prevent this problem, compressed air is jetted from the air blowing hole 13 for a specified period of time to prevent the long thin tapered sliver 6 from being introduced into the nozzle 7. As described above, after the thin tapered sliver 6 has been removed, the jetting of compressed air through the air blowing hole 13 is stopped while the nip roller 21 is in contact with the delivery roller 22 that is constantly rotated in order to transfer the leading yarn Y' in the direction of the winding device. In addition, immediately after the nip roller 21 has been placed in contact with the delivery roller 22, the twist device T is reactivated, that is, air is jetted from the air injection holes 7b. A suction air flow stronger than that in the suction tube 18 is then provided near the sliver guide entrance 7c of the nozzle 7 and discharged from the front roller 4, so fibers constituting the sliver 6 with the tapered portion 6a of a reduced length are introduced into the sliver guide entrance 7c of the nozzle 7 and the fibers are entangled with the leading yarn Y' drawn out from the suction tube 18 for piecing. In addition, the supply of air jetted through the air blowing tube 19 can be continued during piecing, that is, even after the tapered portion at the tip of the sliver 6 has been removed, the jetted air continuous to be supplied in order to remove the portion of fibers constituting the sliver 6 supplied from the front roller 4 to the suction tube 18, and the amount of fibers entangled with the leading yarn Y' is adjusted to make a piecing portion nearly as thick as the leading yarn Y'. Once the piecing operation has been completed, the jetting of air from the air exit port 19a of the air blowing tube 19 is stopped. Figure 5 shows a timing chart of the piecing operation. In Figure 5, the jetting of air from the nozzle 7 of the twist device T is begun at approximately the same time at an ON signal is issued at time t0, causing the nip roller 21 to come into contact with the delivery roller 22. Once time t1 has elapsed, the air blowing hole 13 is deactivated (OFF), and once time t2 has elapsed, the nip roller 21 comes into contact with the delivery roller 22. When the nip roller 21 is activated, the leading yarn Y' starts running and the sliver 6 is supplied to the twist device T and entangled with the leading yarn Y' for piecing. Since, air is still being jetted from the air blowing tube 19, however, part of the sliver 6 is sucked into the suction tube 18 and removed. The air blowing tube 19 is deactivated (OFF) after time t3 has elapsed. Once time t4 has elapsed, the nozzle 7 provides a set air pressure. Times t1 to t4 are set so that t1 < t2 < t3 < t4. The chart for the nozzles 7, air blowing hole 13, air blowing tube 19 in Figure 5 shows the variation in air pressure. For example, in the nozzle 7, a valve is activated at time t0, but the pressure of a rotating air flow actually supplied to the twist device T reaches a set normal value after time t4 has elapsed. The above embodiment has been described in conjunction with a case wherein when the back and third rollers 1 and 2, which have been stopped, are restarted to transfer the sliver 6 gripped by the back and third rollers 1 and 2, compressed air is almost simultaneously re-jetted from the air blowing hole 13 to prevent the sliver 6 from being introduced into the sliver guide entrance 7c of the nozzle 7. Instead of the jetting of compressed air from the air blowing hole 13, the air jet from the air exit port 19a of the air blowing tube 19 can be temporarily increased to deflect, toward the suction tube 18, the thin tapered portion 6a supplied by re-driving the back and third rollers 1 and 2, thereby preventing the sliver 6 with the long tapered portion 6a from being introduced into the twist device T. After the long tapered portion 6a has been removed, the air jet from the air exit port 19a of the air blowing tube 19 is reduced to allow the sliver 6 to be introduced into the twist device T. Although, in the above embodiment, the spindle supporting member 10 and the nozzle block 8 can come into contact with and can be detached from each other, the spindle supporting member 10 and nozzle block 8 constituting the twist device T may still be mutually integrated. In this case, the head A' of the transfer arm member A gripping the leading yarn Y' is located in proximity to the yarn exit port 9c of the spindle 9, and compressed air is supplied through the air blowing hole 13 in order to provide the insertion hole 9b of the spindle 9 with an air flow flowing toward the tip 9a while providing a suction air flow through the suction tube 18. In addition, the drive rollers a1, a2 of the transfer arm member A are operated to pass the leading yarn Y' through the twist device T and then allow the leading yarn Y' to be ejected from the sliver guide entrance 7c in the twist device T. Thus, this embodiment can omit the air sucker member S. The following describes the results of experiments for the present method and apparatus that supplies an air jet through the air blowing tube 19 during piecing and the conventional piecing method and apparatus, which does not supply such air jet. When 32 piecing operations in which an air jet was supplied through the air blowing tube 19 during piecing were performed using the present method and apparatus, a piecing portion was hard to identify and given the ranked "A" in 20 piecing operations, while a piecing portion could be identified but was not defective and was thus given the rank "B" in 12 piecing operations. No piecing portion was identified as being defective or given the rank of "C". In conventional piecing operations without an air jet through the air blowing tube 19, a rank "A" piecing portion was formed in only one of 40 piecing operations, a rank "B" piecing portion was formed in 12 piecing operations, and a defective rank "C" piecing portion was formed in 27 piecing operations. Thus, when an air jet was supplied through the air blowing tube 19, all 32 piecing operations were ranked "A" or "B", successful piecing operations, whereas in conventional piecing operations, ranked "A" or "B", successful piecing operations, were only 32.5% and 67.5% were ranked "C" or unsuccessful piecing operations. The above configuration of the invention enables it to produce the following effects. Since the tip of the sliver supplied from the front roller is removed before the sliver is introduced into the twist device while removing a portion of the fibers constituting it, the thin tapered portion of the sliver can be prevented from forming excessively long or frail piecing portions. Since piecing is performed while the leading yarn drawn out from the sliver guide entrance of the nozzle remains drawn, the piecing portion is prevented from becoming excessively thick and has a stable form.

Claims: Method for a spinning machine for piecing a sliver (6) delivered by a re-operated draft device (D) and the leading yam (Y') of a winding side yarn end ejected from a sliver guide entrance (7c) of a twist device (T) in a stationary state by introducing them into the twist device (T), wherein the leading yam (Y') is held in a suction pipe (18) located between the front rollers (4) of the draft device (D) and the twist device (T) and wherein after re-operation the draft device (D) the twist device (T) is operated and fibres comprising the sliver are entangled with the leading yam (Y') pulled from the twist device (T), characterized in that air is jetted through an air blowing tube (19) toward the sliver guide entrance (7c) during at least a portion of the piecing operation. A piecing method for a spinning machine according to claim 1 characterized in that the leading yarn drawn out from a sliver guide entrance of a nozzle of the twist device is drawn and retained. A piecing apparatus for a spinning machine to carry out the method according to claim 1 characterized in that the apparatus includes a means for removing all or part of the fibers constituting a sliver supplied from the front roller during piecing operation by driving draft rollers which have been stopped, A piecing apparatus for a spinning machine according to claim 3 characterized in that said fiber removal means has a suction tube provided between the front roller and the sliver guide entrance of the twist device, and an air blowing tube facing said suction tube in such a way that said sliver guide entrance is located between the air blowing tube and said suction tube. A piecing apparatus for a spinning machine according to claim 3 characterized in that the apparatus includes means for drawing and retaining a leading yarn drawn out from the sliver guide entrance of the twist device.

Inventors: HIRAO OSAMU, NISHIMURA MASAHIKO, HIRAO, OSAMU, NISHIMURA, MASAHIKO
Applicants: MURATA MACHINERY LTD, MURATA KIKAI KABUSHIKI KAISHA
Application year: 1997
Main classification: D01H15
IPC codes: D01H15