The preset invention relates to a spinning device according to the preamble of claim 1. Such a spinning device is known from JP-A-2001 40 532 also defining the preamble of claim 1.

This known spinning device produces a truly twisted-like spun yarn and comprises a hollow guide shaft body, an air spinning nozzle that generates a rotating air current in an end part on the upstream side of the delivering yarn in the hollow guide shaft body, and a nozzle provided in a yarn passage of the hollow guide shaft body. In this spinning device the yarn on the spinning side is discharged first after the yarn is started to be spun with two rotating air currents (the beginning of the spinning is hereinafter called "yarn discharging spinning"), and the yarn is pieced with a yarn piecing device such as a knotter or a splicer. In this case, the yarn ends on the spinning and winding sides are clamped in piecing the yarns, and both yarn ends are connected after stopping the yarn traveling. Then, the yarn is produced and fed continuously while the yarn ends on the spinning side are clamped, so that the yarn is slacked on the spinning side. However, the yarn tension is maintained in piecing the yarns, as a slack tube having an opening for sucking the yarn on a yarn path, which is a means for sucking the yarn slack, sucks the yarn for absorbing the yarn slack.

In recent years, high-speed spinning machines are used for producing either the truly twisted-like spun yarn or a fasciated spun yarn. However, the yarn slack part becomes longer when the yarn delivering speed is faster, and the yarn tension cannot be maintained by sucking the yarn with the conventional slack tube. It might be possible to make the slack tube capacity larger, however it is difficult to realize because of the space for installing it. Consequently, the shape of the yarn that is spun in changing the yarn tension becomes different from the other part of the yarn that is spun when the yarn tension is maintained, and the yarn that has a different shape from the other is not dyed evenly. Moreover, the yarn slack tends to make a yarn kinked or tangled. Furthermore, stiff packages cannot be made and a yarn package quality becomes deteriorated as the yarn is wound loosely on the package when the yarn tension is reduced. Additionally, the change of the torque and a hairiness number of the yarn, caused in the truly twisted-like spun yarn, also causes the dyeing unevenness of yarn.

The problem underlying the present invention is to reduce the yarn slack occuring during yarn piecing in a high-speed spinning device for producing a truly twisted-like spun yarn.

This problem is accomplished by the features defined in the characterizing part of claim 1. Accordingly it is not only possible to reduce a yarn slack during yarn piecing but also to maintain the yarn tension and the same yarn spinning conditions.

The control unit when detecting a yarn defect signal changes the drive speed of the draft device, the yarn delivering means and the winding means between a first drive speed during normal spinning and a second drive speed during the yarn piecing operation that is lower than the first drive speed, so that the yarn tension can be maintained with shortening the yarn slack length compared with the length in conventional piecing after making the yarn delivering speed by the respective devices provided along the yarn path lower in piecing yarn. Thus, a high quality package can be produced. Moreover, as the tension applied to the yarn can be prevented from changing, yarn shape is maintained and yarn is prevented from dyeing unevenly. Furthermore, a kinked and tangled state in the yarn slack part can be prevented, which is incidental by getting the length of yarn slack longer.

In addition, the control unit reduces the pressure of the rotating air current of the air spinning nozzle correspondingly to the second drive speed during the yarn piecing operation.

By the pressure reduction the yarn slack volume can be reduced with maintaining the yarn tension and the torque and the hairiness number of the yarn can be almost the same as during the normal spinning as the energy of the jet air applied to per unit length of the spun yarn can be kept constant even if changing the yarn delivering speed, in piecing yarn. Consequently, the yarn piecing part can be prevented from dyeing unevenly.

The reduction of pressure of the rotating air current of spinning nozzles during the yarn piecing operation is known from EP-A-1 072 702 disclosing a true-twist spinning device. The reduction of the pressure is effected by turning off the spinning nozzles to safe energy.

• Figure 1 is a schematic diagram of a spinning device for producing a truly-twisted like spun yarn not within the scope of the claim.
• Figure 2 is a front view of the spinning device having a plurality of spinning units in a line.
• Figure 3 is a side sectional view showing an air spinning part.
• Figure 4 is an enlarged substantial part of Figure 3.
• Figure 5 is a sectional view taken substantially along the lines III - III of Figure 4.
• Figure 6 is a diagram showing a pattern of changing the yarn delivering speed.
• Figure 7 is a schematic diagram of the spinning device of the present invention.
• Figure 8 is a block diagram of a first switching mechanism.
• Figure 9 is a diagram showing a pattern of applying a jet air pressure from an air spinning nozzle.
• Figure 10 is a schematic diagram of the spinning device in a second embodiment.
• Figure 11 is a block diagram of another first switching mechanism.
• Figure 12 is a diagram showing a pattern of changing the jet air pressure from the air spinning nozzle.

The spinning device in Fig. 1 and 2 includes a lot of spinning units 3 for producing a spun yarn Y, which are laid in a line to the longitudinal direction of a frame 10 of the spinning device. The spinning units 3 are disposed in the frame 10 that connects a motor box 1 and a blower box 2. A draft device 4, an air spinning part 5, a nip roller 16 and a delivery roller 17 that are the yarn delivering means, and a winding means 8 of the spun yarn Y are disposed along a yarn path in each spinning unit 3. The draft device 4 draws a sliver S to produce a fiber bundle F, and delivers the fiber bundle F to the air spinning part 5. The air spinning part 5 applies the rotating air current to the fiber bundle F, and produces the truly twisted-like spun yarn Y. The nip roller 16 and the delivery roller 17 discharge the spun yarn Y produed by the air spinning part 5, and the winding means 8 winds the spun yarn Y onto a package P. Hereinafter, the side of the yarn path, where the sliver S is discharged, is considered to be the upstream side of the yarn path, and the side of the yarn path having the winding means 8 is considered to be the downstream side.

The front side of the frame 10 is open, and a yarn piecing vehicle 9 is arranged so as to travel between the respective spinning units 3, 3, ... along rails 14, 15 in an opening part on the front side. The yarn piecing vehicle 9 includes a yarn piecing device 11 such as a knotter or a splicer equipped with a clamp device (not shown), a suction nozzle 12 that sucks and grasps the spun yarn Y on the spinning side, and a suction mouth 13 that sucks and grasps the spun yarn Y on the winding side from the package P. The suction nozzle 12 and the suction mouth 13 can be turned. A blower 76 is loaded on the yarn piecing vehicle 9 as a suction source. In piecing yearns, the yarn piecing vehicle 9 is moved to the spinning unit 3 where the spun yarn Y is broken, and the suction nozzle 12 sucks the spun yarn Y that is produced from the air spinning part 5 by turning the suction nozzle 12. The suction mouth 13 is turned downward to contact the surface of the package P that is wound by the winding means 8, picks up the yarn end and sucks the spun yarn Y from the package P. The suction nozzle 12 and the suction mouth 13 suck and grasp the yarn end on the spinning side and the yarn end on the winding side respectively. Both yarn ends are introduced into the yarn piecing device 11 by turning the suction nozzle 12 and the suction mouth 13 respectively, and the yarns are pieced in the state of being clamped by the clamp device.

In this specification, the terms on yarn piecing are defined as follows: "Piecing yarn" means to connect both yarn ends that are sucked and grasped by the suction nozzle 12 and the suction mouth 13, using the yarn piecing device 11. "Yarn piecing operation" means the operation in the spinning device from the time T2 that the yarn piecing vehicle 9 arrives at the spinning unit 3 where the spun yarn Y is broken to the time T9, where normal spinning is started again (Fig. 6). Moreover, "in piecing yarn" means the time of "piecing yarn", in other words, the time of connecting both yarn ends with the yarn piecing device 11 (from a time T6 to a time T7 as described later). Likewise, "in yarn piecing operation" means the time of "yarn piecing operation", in other words, the interval between the time T2 of arrival of the yarn piecing device 11 and the time of starting normal spinning (from time T2 to time T9 as described above).

Next, each device included in the respective spinning units 3 will be described along the yarn path.

The draft device 4 comprises a back roller 21a and a third roller 21b respectively along the yarn path, and also comprises a second roller 23 on which an apron 22 is wound and a front roller 24. The back roller 21a and the third roller 21b are driven to be rotated by a motor 25, and the second roller 23 is driven to be rotated by a motor 26. Moreover, the front roller 24 that discharges the fiber bundle F from the draft device 4 to the air spinning part 5 is driven by a motor 35, and the nip roller 16, the delivery roller 17, and a friction roller 38 of the winding means 8 are also driven by the motor 35. Encoders 28, 29, 39 for a feedback control are directly connected to the respective motors 25, 26, 35, and likewise, subcontrollers 31, 32, 36, which are individually connected, increases and reduces the speed. Especially, the front roller 24, the delivery roller 17 and the friction roller 38 are controlled in phase by the speed control of the motor 35.

The air spinning part 5 will be described with reference to Figure 3 to Figure 5.

The air spinning part 5, as illustrated in Figure 3, has an air spinning nozzle 19 that applies a rotating air current to the fiber bundle F with making the fiber bundle F, which is fed from the front roller 24, passing through the air spinning part 5. The spun yarn Y is then produced by the rotating air current from the air spinning nozzle 19 and the action of a hollow guide shaft body 20. The spun yarn Y is a truly twisted-like spun yarn, which is wound onto the package P in the state of having torque, inherent to truly twisted-like spun yarn.

The air spinning nozzle 19, as illustrated in Figure 3, includes a tip part 44' and casings 65, 66, and the guide shaft body 20 having an assistant nozzle 55 is disposed on the downstream side of a needle holder 43.

The needle holder 43 has a guide hole 41 introducing the fiber bundle F that is drawn in the tip on the upstream side of the needle holder 43 and retains a needle 42 on the yarn path of the fiber bundle F discharged from the guide hole 41. The guide shaft body 20 is supported by the casing 66 in the middle part to a shaft direction, and the tip part 44' on the upstream side and the casing 65 are disposed at a predetermined interval. Moreover, the casing 65 covers the tip of the guide shaft body 20, and a spinning room 57 is formed between the tip of the guide shaft body 20 and the rear end of the needle holder 43.

A plurality of first nozzle holes 47 that open to the spinning room 57 is formed in the casing 65. As illustrated in Figure 4, a rotating air current is produced in the spinning room 57 by jetting air along the inside of the spinning room 57 to the left-hand direction R1, seen from a yarn delivering direction, in case of a Z-twist. The first nozzle holes 47 are formed so as to incline to the downstream side of the delivering direction of the fiber bundle F, for making the air to flow to the downstream side.

The guide shaft body 20, has an opening 48 in the tip part 44' opposed to the needle 42, and a spun yarn passage 49 is formed on the shaft center. The spun yarn passage 49 is formed such that its diameter broadens in multiple stages, and comprises an introduction hole 50 in the tip part 44', a first enlarged diameter hole 51, a second enlarged diameter hole 52 whose diameter is enlarged in a taper shape and which is connected to the downstream side of the first hole 51, and a third enlarged diameter hole 53 connected to the downstream side of the second hole 52. A delivery hole 54 is formed in an end part on the delivering side of the spun yarn Y in the third hole 53.

The assistant nozzle 55 is provided for introducing the fiber bundle F that is rotated by the first nozzle holes 47 into the introduction hole 50 in the middle of the guide shaft body 20. As illustrated in Figure 4 and Figure 5, the assistant nozzle 55 includes a plurality of the second nozzle holes 56 perpendicular to the passage 49 in the middle of the guide shaft body 20. In case of the Z-twist, the second nozzle holes 56 are formed so as to flow air along the inside of the passage 49 to a right handed-direction R2, seen from the yarn delivering direction. In Figure 5, for example, eight holes are formed at a predetermined interval and connected to the first hole 51. The assistant nozzle 55 generates a rotating air in the inverse direction of the air from the air spinning nozzle 19. An air passage 37, extending from the vicinity of the delivery hole 54 to the second nozzle holes 56, is formed in the guide shaft body 20. The air passage 37 is connected to a compressed air supply passage 58 on the delivery hole 54 side, and is capable of supplying air to the second nozzle holes 56.

Additionally, it is preferable that the assistant nozzle 55 is as close to the nip point of the fiber bundle F in the front roller 24 as possible. This is because the fiber bundle F discharged from the front roller 24 is drawn into the guide shaft body 20 with stronger suction power in the yarn discharging spinning and this helps to grasp the fiber by propagating twist to the fiber bundle F discharged from the front roller 24 with a rotating air current from the assistant nozzle 55.

As illustrated in Figure 1, air is supplied from a compressed air source 6 provided in the spinning device to the air spinning part 5 through a first air pressure switching means 27 and a second air pressure switching means 68 provided in every spinning unit 3. The air having a predetermined jet air pressure applied by the first air pressure switching means 27 is supplied to the first nozzle holes 47 in the air spinning nozzle 19, and the air having a predetermined jet air pressure applied by the second air pressure switching means 68 is supplied to the second nozzle holes 56 of the assistant nozzle 55.

Next, the action of piecing yarn in the spinning part 5 will be described.

The fiber bundle F delivered to the air spinning part 5 is inserted into the guide hole 41 of the needle holder 43, and the compressed air is jetted to the fiber bundle F from both the first nozzle holes 47 and the second nozzle holes 56 in the air spinning part 5. The first nozzle holes 47 are inclined to the downstream side of the yarn delivering direction of the fiber bundle F, and the compressed air jetted from the first nozzle holes 47 flows in the delivering direction of the fiber bundle F. Therefore, the fiber bundle F inserted into the guide hole 41 of the needle holder 43 is sent to the vicinity of the opening 48 of the guide shaft body 20 with making the fiber bundle F in the loose false twist state with the rotating air current.

Moreover, in piecing yarn, a rotating air current is formed after the compressed air is jetted from the second nozzle holes 56 of the assistant nozzle 55 and the compressed air flows along the internal surface in the spun yarn passage 49 formed in the guide shaft body 20. Additionally, in normal spinning other than the yarn discharging spinning (net in starting to spun yarn), compressed air is not jetted from the second nozzle holes 56, and compressed air is jetted only from the first nozzle holes 47 and the truly twisted-like spun yarn Y is produced.

As the spun yarn passage 49 broadens toward the delivering side of the spun yarn Y, the compressed air jetted into the spun yarn passage 49 through the second nozzle holes 56 flows to the delivering side, and the pressure in the introduction part 50 becomes negative. Thus, the air flows in the sucking direction (the direction into the guide shaft body 20) in the opening 48 formed in the tip of the guide shaft body 20, so that the fiber bundle F can be drawn continuously.

The fiber bundle F in the false-twist state delivered around the opening 48 of the hollow guide shaft body 20 is sucked into the spun yarn passage 49 by the suction air current from the opening 48. The fiber bundle F then comes to the first enlarged diameter hole 51 and is exposed to the rotating air current flowing in the inverse direction to the one from the air spinning nozzle 19. Therefore, the yarn discharging spinning is carried out by delivering the fiber bundle F in loosely false twist state from the guide shaft body 20 with making the fibers in the fasciated spun yarn state, using the conventional yarn spinning art for producing spun yarn Y with the nozzles that are directed opposite to each other.

Next, the yarn delivering means will be described.

The delivery roller 17 on the downstream side of the air spinning part 5 is rotated by the motor 35, and the nip roller 16 contacts the delivery roller 17. The spun yarn Y passing through the yarn path is delivered to the downstream side by being nipped between the delivery roller 17 and the nip roller 16. In piecing yarn, the yarn end on the spinning side is formed into a fasciated spun yarn U by the yarn discharging spinning as described above, and the fasciated spun yarn U is delivered from the air spinning part 5. The yarn is sucked into the suction nozzle 12, and the spun yarn Y is guided between the nip roller 16 and the delivery roller 17 by turning the suction nozzle 12. After that, the yarn follows the yarn path. When the yarn is nipped in between the nip roller 16 and the delivery roller 17 after being formed into the fasciated spun yarn U and the yarn is delivered stably, a subcontroller and the second air pressure switching means 68 stop to supply the compressed air to the second nozzle holes 56. After the yarn discharging spinning is terminated, only the air spinning nozzle 19 jets air. As described above, the delivery roller 17 is driven by the same motor 35 as the one used by the front roller 24 and the friction roller 38.

A suction pipe called a slack tube 40 is provided for absorbing yard slack in piecing yarn on the downstream side of the delivery roller 17. The traveling of the yarn end is stopped by the clamp device in the yarn piecing device 11 during the interval from the time of introducing both yarns on the spinning side and winding side, sucked and grasped by the suction nozzle 12 and the suction mouth 13, into the yarn piecing device until the time of terminating piecing the yarns, however the yarn is slacked as the yarn on the spinning side is spun continuously, but the yarn on the spinning side is sucked continuously with the slack tube 40 for keeping tension, and the yarn slack is absorbed.

A slab catcher 18 is provided on the downstream side of the slack tube 40 as a means for detecting yarn defects and the presence of the traveling yarn. If the spun yarn Y is broken or the yarn is broken naturally when the yarn defects are detected by the slab catcher 18, the spun yarn Y on the winding side is wound onto the package P, and the sliver S is stopped to be delivered on the spinning side.

The winding means 8 comprises the friction roller 38 abutting against a peripheral surface of the package P and a traverse device 7. As described above, the friction roller 38 is driven by the same motor 35 that is also used by the front roller 24 and the delivery roller 17. The traverse device 7 for winding the spun yarn Y on the package P is provided in the vicinity on the upstream side of the friction roller 38. The traverse device 7 is driven by the motor 44, and an encoder 45 for the feedback control is connected directly to the motor 44. A subcontroller 46 that increases and reduces the speed of the motor 44 is connected to the motor 44.

A host controller (control unit) 64 for controlling the subcontrollers 31, 32, 36, 46 provided in the spinning unit 3, sends timing signals to each controller in order to make the whole operation smoothly. The signal from the slab catcher 18 is also input to the host controller 64.

Next, the spinning and yarn piecing operation in the spinning device will be described with reference to Figure 1 and Figure 6. Figure 6 is a diagram showing a pattern of changing the yarn delivering speed in the respective devices. The yarn delivering speed of the spun yarn Y is determined by the rotation speed of the friction roller 24, the delivery roller 17, and the friction roller 38. In the present invention, in piecing yarn, the length of a yarn slack Ya is made to be reduced by controlling the speed of the respective rollers 24, 17, and 38 that determine the yarn delivering speed of the spun yarn Y.

Again, "piecing yarn" means to connect both yarn ends that are sucked and grasped by the nozzle 12 and the mouth 13, and "yarn piecing operation" means the operation in the spinning device from the time that the yarn piecing vehicle 9 arrives at the spinning unit 3 to the time of starting normal spinning. The time that yarn is pieced is "in piecing yarn", and the time of carrying out "yarn piecing operation" is "in yarn piecing operation". In Figure 6, Figure 9 and Figure 12 "in piecing yarn" means the times from T6 to T7, and "in yarn piecing operation" means the times from T2 to T9.

A yarn defect signal is input to the host controller 64 based on the result that no yarn is detected as the yarn Y is cut by a cutter (not shown) after the slab catcher 18 detects yarn defects such as a slab, or the fiber bundle F is choked in the air spinning part 5. The time of detecting yarn defects is shown as T0 in Figure 6. The other times as described later are also indicated in Figure 6. The motor 25 of the draft device 4 is then stopped at once as illustrated in Figure 6A after an instruction signal is output from the host controller 64 to the respective subcontrollers, and the yarn delivering speed is changed from the one in normal spinning to the one in the yarn delivering speed in piecing yarn (time T1) after giving an instruction of reducing speed to the motor 26 that drives the second roller 23, the motor 35 that drives the three rollers including the front roller 24, the delivery roller 17 and the friction roller 38, and the motor 44 that drives the traverse device 7 (time T0). Hereinafter, a first drive speed is taken for the yarn delivering speed in normal spinning, and a second drive speed is taken for the yarn delivering speed in piecing yarn. The second drive speed is lower than the first drive speed. When the motor 25 in the draft device 4 is stopped, the supply of the sliver S is then stopped and the delivery of the spun yarn Y from the air spinning part 5 is also stopped. The spun yarn Y on the downstream side of the broken part is wound into the package P.

When the yarn defect or the non-existence of yarn is detected, the yarn piecing vehicle 9 arrives at the unit 3 that needs a piecing operation (time T2). The yarn piecing operation as described above is then started by turning the suction nozzle 12 and the suction mouth 13, after the draft device 4 and the air spinning part 5 are started up as follows: An instruction is sent from the host controller 64 to the sub controller 31, and the instruction for increasing the speed is given to the motor 25 ion the time T2 of turning the suction nozzle 12 and the suction mouth 13, based on the programmed speed pattern as illustrated in Figure 6A. The instruction for increasing the speed is shown in a slat part from the time T2 to T3 in the speed pattern of Figure 6A. Additionally, the package P is seperated from the friction roller 38 just before the time T2 and is driven inversely to the package P. Therefore, the sliver S is started to be supplied again, and the compressed air is started to be supplied to the second nozzle holes 56 with the second air pressure switching means 68 and the yarn discharging spinning is started.

When the yarn delivering speed in driving the respective motors 25, 26, 35, and 44 is changed to the second drive speed respectively based on the speed instruction, the yarn delivering speed is maintained to the second drive speed (time from T3 to T7). The drive speed of the traverse device 7 is also controlled based on the yarn delivering speed. At the time of changing the speed, the sliver S is drawn continuously by the draft device 4 and delivered to the air spinning part 5, however the acceleration of the rollers 23, 24 is controlled so as to be constant in the draft device 4, and the speed ratio of the respective rollers 21a, 21b, 23, 24 is controlled so as to be the same as the one in normal spinning after the time T3, so that the suitable-sized sliver S that is properly drawn is introduced into the air spinning part 5, the nozzle is not choked, and the failure of passing yarn is reduced.

Moreover, the suction nozzle 12 sucks and grasps the yarn on the spinning side during the time from T3 to T6, in which the yarn delivering speed is retained to the second drive speed, and the yarn is nipped between the delivery roller 17 and the nip roller 16 by turning the nozzle to the original position (time T4). The delivering power to the downstream side is applied to the yarn on the spinning side on the yarn path by being nipped by both rollers.

The fasciated spun yarn U part is not needed on the spinning side for winding only the truly twisted-like spun yarn Y onto the package P. The truly twisted-like part on the upstream side in the fasciated spun yarn U part is needed. Therefore, the yarns are pieced such that the part formed in the truly twisted-like spun yarn Y in the yarn on the spinning side is introduced into the yarn piecing device 11 by sucking and grasping with the suction nozzle 12. In other words, in piecing yarn, the suction nozzle 12 applies the delivering power to the downstream side by sucking the part formed in the fasciated spun yarn U in the yarn on the spinning side and nipping the yarn between the nip roller 16 and the delivery roller 17, and introduces the yarn to the yarn piecing device 11. After that, the suction nozzle 12 sucks the yarn end on the spinning side until at least the part formed in the truly twisted-like state in the spun yarn Y that is delivered accompanied by finishing the yarn discharging spinning is supplied into the yarn piecing device 11.

When the fasciated spun yarn U part in the yarn on the spinning side is nipped (time T4), the truly twisted-like spun yarn Y is started to be produced in the air spinning part 5 (time T5). The yarn ends on the spinning side and the winding side are then respectively clamped during the time between time T6 to time T7, both yarn ends are maintained at a predetermined position, and the yarn piecing operation is started. At time T6, the produced truly twisted-like spun yarn Y is discharged from the air spinning part 5, and then the fasciated spun yarn U part in the spun yarn Y is entered into the suction nozzle 12 completely and is continued to be sucked. In the yarn piecing operation, the fasciated spun yarn Y part in the yarn on the spinning side is sucked and grasped by the suction nozzle 12. If the yarn is cut after detecting yarn defects, the yarn end part on the winding side including yarn defects is sucked and grasped by the inverse drive of the package P and the suction mouth 13 after releasing the contact with the friction roller 38 and the package P. The suction with the suction mouth 13 is continued from at least the time that the defective yarn part is entered into the suction mouth 13 completely to the time that the normal truly twisted-like spun yarn is supplied to the yarn piecing device 11. After that, the yarns are pieced by introducing the normal truly twisted-like part in both yarns into the yarn piecing device 11. Then, only the truly twisted-like spun yarn is wound after eliminating the yarn end part including the fasciated spun yarn U by the yarn discharging spinning and the yarn end part including the yarn defects.

The yarn on the spinning side and the yarn end on the winding side are maintained at a predetermined position for a predetermined time in piecing yarn from the time T6 to the time T7, so that the spun yarn that is produced during the time from T6 to T7 is sucked into the slack tube 40 in a U shape, as shown in Figure 1. Then, the yarn delivering speed is controlled for shortening the length of the yarn slack Ya sucked into the slack tube 40. To explain the speed control more precisely, the speed is controlled to be reduced first (time T0 to T1) to be a second drive speed, and the speed is maintained in the second drive speed for a predetermined time (time T3 to T7).

Time T7 that is the time of changing the yarn delivering speed into high speed (from the second to first drive speed) can be specified with the host controller 64 for example in the following way.

Considering a first method, a timer transmits a detection signal to the host controlled 64 when the time T7 has come after passing a predetermined time from the time T2 to T3 by using the timer, for specifying the time T7 with the host controller 64. Considering a second method, the yarn piecing device 11 detects that both yarn ends are connected for specifying the time T7 with the host controller 64.

In piecing yarn completely (time T7), the yarn piecing device 11 releases to clamp the yarn and the yarn is wound again on the package P after the friction roller 38 contacts the package P again, so that the yarn slack in the slack tube 40 is started to be reduced. As the yarn slack is reduced if the yarn piecing device 11 releases to clamp the yarn and the yarn is wound again, the yarn delivering speed is made to be the first drive speed again for restoring in the normal spinning state and the speed is maintained on the first drive speed after the time T9. Moreover, preferably, if the timing of contacting the package P with the friction roller 38 is set to be slight earlier than the time of starting to increase the speed of the front roller 24 and the delivery roller 17, the rotation speed of the package P itself is increased earlier and the yarn slack in the slack tube 40 can be eliminated in a short time. The speed of the package P is increased earlier so as not to delay the timing in increasing the speed of the package P by the inertia caused by the weight of the package P.

According to the invention in piecing yarn not only the speed of the respective rollers 24, 17, 38 that determine the yarn delivering speed of the spun yarn Y is controlled, but also the pressure of air jetted from the air spinning nozzle 19 in the air spinning part 5 is controlled to be high or low. This is because the air jet volume that is applied per unit length of the yarn (the fiber bundle F) is increased more than usual if the air pressure jetted from the air spinning nozzle 19 is fixed and the yarn delivering speed is reduced. More precisely, as a short staple fiber comprising the fiber bundle F is enwrapped more strongly than in normal spinning, some part of the yarn becomes strongly tightened and the other part of the produced yarn has different torque and hairiness number. Thus, the yarn is dyed unevenly in some parts. Therefore, the jet air pressure is controlled based on the control of the yarn delivering speed.

As illustrated in Figure 7, a spinning unit 103 comprising the spinning device is equipped with the subcontrollers 33, 34 connected to the air pressure switching means 27, 68. The subcontrollers 33, 34 are controlled by the host controller 64, and the air pressure switching control unit is comprised by these controllers.

In piecing yarn, the pressure of jet air from the air spinning nozzle 19 is controlled. The yarn delivering speed is controlled as described above, and the respective motors 25, 26, 35, 44 are controlled by the subcontrollers 31, 32, 36, 46 based on the speed pattern as illustrated in Figures 6A and 6B.

As illustrated.,in Figures 6A and 6B, the yarn discharging spinning from the air spinning part 5 is carried out after the time T3. Therefore, the jet air pressure is controlled to be low by the time T3 at the latest when the yarn delivering speed is changed. The pressure of jet air from the air spinning nozzle 19 is reduced to be low in phase with the change of the motors 25, 26, 35, 44 while producing the fasciated spun yarn U from the time of giving the instruction of reducing the speed of the motors 35, 44 (time T0) to the time that the yarn on the spinning side is nipped on the yarn path (time T4). Additionally, it is preferable that also the pressure of jet air from the assistant nozzle 55 is set to be lower by the subcontroller 34. The fasciated spun yarn U part formed in the tip part of the yarn on the spinning side is prevented from breaking by changing the pressure of the jet air from the air spinning nozzle 19 suitably at the time of the yarn discharging spinning, and the success ratio of the yarn discharging spinning is improved.

As illustrated in Figure 8, the first air pressure switching means 27 comprises a variable switch valve 70 and a drive means 71 in the switch valve 70. The air spinning nozzle 19 provided in the air spinning part 5 and the compressed air source 6 is connected so as to communicate through the air path 72, and the air pressure supplied to the air spinning nozzle 19 can be changed continuously. The switch valve 70 is switched by the drive of the drive means 71, and the drive means 71 is connected to the subcontroller 33. After that, the drive means 71 is controlled so as to switch the switch valve 70 with the subcontroller 33 based on the programmed pattern of changing pressure as illustrated in Figure 9. While the jet air pressure from the air spinning nozzle 19 is the same as the one in piecing yarn, the pressure of air from the assistant nozzle 55 is not needed to be changed.

In piecing yarn, the pressure of jet air from the air spinning nozzle 19 is changed continuously based on yarn delivering speed, as illustrated in Figure 6 and Figure 9. The jet air pressure is also reduced when reducing the yarn delivering speed, the pressure is kept constant when the yarn delivering speed is constant, and the pressure is increased when the yarn delivering speed is increased again. Therefore, the torque and hairiness number of the produced truly twisted-like spun yarn Y in the air spinning part 5 can be the same as the one in normal spinning in piecing yarn during the time from T6 to T7 and when restoring to the normal spinning. This is because the energy volume of the jet air applied to the yarn per unit length is also maintained almost constant as the jet air pressure is increased and reduced based on the change in the yarn delivering speed.

Additionally, as the assistant nozzle 55 is not provided for the spinning in yarn piecing operation but rather provided for the spinning of the fasciated spun yarn U, air is not jetted from the assistant nozzle 55 in the yarn piecing during the time from T6 to T7.

As described above, the spinning device includes the subcontroller 33, which is added to the configuration of Fig. 1. The subcontroller 36 changes the speed of the front roller 24 in the draft device 4, the delivery roller 17 comprising the yarn delivering means, and the friction roller 38 of the winding means, based on the result of detecting yarn defects by the slab catcher 18, and also changes the pressure of jet air from the air spinning nozzle 19. Thus, in piecing yarn, the yarn slack volume Ya can be limited with maintaining the yarn tension, and the energy of the jet air applied to per unit length of the spun yarn Y can be maintained constant even if changing yarn delivering speed, so that the torque and hairiness number of yarn can be almost the same as in normal spinning. Therefore, the yarn piecing part is prevented from dyeing unevenly.

The pressure of jet air from the air spinning nozzle 19 can be changed continuously with the variable switch valve 71, so that the pressure of jet air from the air spinning nozzle 19 can be changed correctly based on the yarn delivering speed. Thus, the energy of the jet air applied to per unit length of the spun yarn Y can be maintained in the same condition as in normal spinning. Therefore, the state of the spun yarn Y in the yarn piecing part and the part produced by the other normal spinning can be almost the same.

Next, a spinning unit 203 comprising the spinning device in another embodiment will be described with reference to Figure 6 and Figure 10 to Figure 12.

As illustrated in Figure 11, a step type switch valve 170 is provided in the spinning device instead of the variable switch valve 70 in Fig. 8. Accordingly, a drive means 171 is provided instead of the drive means 71, and the first air pressure switching means 127 is provided instead of the first air pressure switching means 27. Moreover, a subcontroller 133 is provided instead of the subcontroller 33. For example, a compressed air generation room 172b in which air pressure is changed to be middle level as illustrated in Figure 12 and a compressed air generation room 172a in which air pressure is changed to the one in normal spinning, and a path without passing through the compressed air generation rooms are connected to the switching valve 170 in parallel. The compressed air pressure in a compressed air pressure source 6 is changed to be the air pressure in piecing yarn. The air pressure applied through the compressed air generation room 172a is changed to the one in normal spinning, and the air pressure applied through the compressed air generation room 172b is changed to the one between in normal spinning and in piecing yarn. Air is supplied so as to change these air pressures step by step. The switch valve 170 is switched properly by the drive of the drive means 171, which is connected to the subcontroller 133. The drive means 171 is then controlled so as to switch the switch valve 170 by the subcontroller 133 based on the programmed pattern of changing pressure as illustrated in Figure 12. The subcontroller 133 is also controlled by the host controller 64. The number of compressed air generation rooms is not limited to the number as described above, and more compressed air generation rooms whose air pressure is respectively different can be added resulting in multiple levels.

The difference of the spinning devices of Fig 10 and 7 only exists in the configurations of the first air pressure switching means 27, 127 (switch valves 70, 170) for the air spinning nozzle 19, so that the explanation of the other parts is omitted. As the configuration of the first air pressure switching means is different, the pattern of changing the pressure of jet air from the air spinning nozzle 19 (Figure 12) is different from the first one (Figure 9). On the other hand, regarding the control of the yarn delivering speed, the respective motors 25, 26, 35, 44 are controlled by the subcontrollers 31, 32, 36, and 46 based on the speed pattern as illustrated in Figures 6A and 6B.

As illustrated in Figure 6 and Figure 12, the pressure of jet air from the air spinning nozzle 19 is reduced when reducing the yarn delivering speed, the pressure is constant when the yarn delivering speed is constant, and the pressure is increased when increasing the yarn delivering speed again. The yarn delivering speed is increased step by step based on the yarn delivering speed during the time T8 when the air pressure is changed to the one in the middle. In Figure 12, the solid line shows the jet air pressure, and the dashed line shows a compressed air pressure that is switched in the switching valve 170 of the first air pressure switching means 127. As the propagation velocity of the compressed air is same as the sound speed, time lag occurs between the time of switching in the switching valve 170 and the time that the compressed air pressure supplied from the switching valve 170 is propagated to the air spinning nozzle 19. Thus, the compressed air switched in the switching valve 170 is not completely accorded with the jet air pressure in the air spinning nozzle 19, and the jet air pressure is changed slowly. When the yarn delivering speed is increased, the jet air pressure is changed almost step by step.

As the pressure of jet air is changed step by step in increasing the speed, the shape of the produced spun yarn Y does not change so much compared with the case of not controlling the jet air pressure based on the yarn delivering speed (the case of maintaining the jet air pressure constant). In other words, the change in the energy volume of the jet air applied per unit length of the yarn is limited to be lower compared with the case of not controlling as described above in the air spinning part 5, so that the torque and hairiness number of the produced truly twisted-like spun yarn Y in the air spinning part 5 can be almost the same as the yarn condition in the normal spinning.