Spinning device and method

Abstract: The present invention provides a spinning device that can reduce errors during preparations for joining and that enables stable joining. In a true-twist spinning device S including a hollow guide shaft 15 having a spun-yarn passage 23 through which a spun yarn Y passes, and spinning nozzles 14 for generating whirling air currents near a tip of the hollow guide shaft 15, the spun-yarn passage 23 is formed to broaden toward a yarn ejection side, and yarn picking-up nozzles 29 are provided in the middle of the spun-yarn passage 23 for injecting compressed air. By injecting compressed air from the yarn picking-up nozzles 29 during joining, a suction force is generated in the spun-yarn passage 23 to allow a fiber bundle 6, which have been whirled by the spinning nozzles 14, to be introduced into the spun-yarn passage 23 for yarn picking-up spinning.

Description: Field of the Invention The present invention relates to a spinning device and a spinning method for applying a true twist to a fiber bundle for spinning. Background of the Invention As shown in Figure 14, a spinning device 350 is provided downstream of a draft device 351 for spinning a fiber bundle 352 transferred from the draft device 351. The spinning device 350 comprises a spinning nozzle 353 for passing the transferred fiber bundle 352 while blowing whirling air currents against the fiber bundle 352, and a hollow guide shaft 354 provided downstream of the spinning nozzle 353 at an interval therefrom. The hollow guide shaft 354 is formed to be substantially cylindrical and adapted to pass therethrough the fiber bundle 352 ejected from the spinning nozzle 353. In addition, a suction member 355 is provided on one side of a yarn path joining the spinning device 350 with the draft device 351, for sucking a yarn end. The suction member 355 is used to splice a yarn end on a package (not shown in the drawings) side that corresponds to a leading yarn, to a fiber bundle on a supply side which is transferred from the draft device 351. When a spinning machine is initially started or yarn breakage occurs, the package-side yarn is transferred to a neighborhood of an ejection port 357 in the hollow guide shaft 354 by means of a transfer arm member 356, and is passed through the hollow guide shaft 354 and the spinning nozzle 353 from a direction opposite to the supply-side yarn so as to be sucked into the suction member 355. The supply-side fiber bundle is then sucked into the suction member 355 and intertwined with the package-side yarn, and the intertwined yarns are drawn into the spinning nozzle 353 for piecing. However, on starting spinning for piecing or the like, the spinning device 350 must transfer the package-side yarn to the suction member 355 as a leading yarn and then pass it through the hollow guide shaft 354 and the spinning nozzle 353 from the opposite direction. Consequently, this method is disadvantageous in that errors frequently occur during preparations for piecing. This method also has the following disadvantages. Since the joining is based on piecing a leading yarn and the fiber bundle together, a joined portion (not shown in the drawings) tends to be thick. Since the yarn ends sucked and intertwined together in the suction member 355 are pieced together, it is difficult to control the length of the pieced yams to a fixed value and the piecing may sometimes fail. In US 5 088 265 A another spinning device is disclosed having the features of the preamble of claim 1, using the method steps of the preamble of claim 10. Summary of the Invention It is an object of the present invention to provide a spinning device that can prevent errors during preparations for joining and that enables stable joining. To attain this object, the present invention is a spinning device including a hollow guide shaft having a spun-yarn passage through which a spun yarn passes, and spinning nozzles for generating whirling air currents near a tip of the hollow guide shaft, characterized in that a suction force generation means is provided in the hollow guide shaft for sucking and introducing a fiber bundle whirled by the spinning nozzle, into the spun-yarn passage. According to the present invention, the spun-yarn passage is formed so as to broaden toward its yarn ejection-side and in that the suction force generation means comprises yarn picking-up nozzles for injecting compressed air into the spun-yarn passage. According to the present invention, during a yarn picking-up operation, the spinning nozzles and the yarn picking-up nozzles both inject compressed air to eject a spun yarn from the ejection side of the spun-yarn passage. In the above description, the expression "yarn picking-up" or "yarn picking-up operation" means that a spinning device starts manufacturing a spun yarn and finally elects the spun yarn therefrom. In addition, the expression "during a yarn picking-up operation" refers to a point of time immediately after the spinning device has started manufacturing the spun yarn. The present invention includes switching means for switching an injection pressure of the spinning nozzles to a high or low level. According to the present invention, the switching means switches the injection pressure to a low level before the start of yarn picking-up and maintains it for a predetermined amount of time. In the above description, the expression "the start of yarn picking-up" refers to the point of time when the spinning device starts manufacturing the spun yarn. According to the present invention, after the start of yarn picking-up, the switching means switches the injection pressure from low to high after leading tip of fibers constituting a fiber bundle have been introduced into the spun-yarn passage. According to the present invention, a distance between an injection position of the spinning nozzles and an injection position of the yarn picking-up nozzles is substantially the same as or smaller than an average fiber length of the fibers constituting the fiber bundle. According to the present invention, the hollow guide shaft has a conical tip portion and a cylindrical portion constituting a main body and integrated with each other in that the main body has an inner cylindrical member disposed therein and having the yarn picking-up nozzle formed therein. According to the present invention, the hollow guide shaft is formed from a ceramic. According to the present invention, in a normal spinning state, whirling air currents are used to spin a true-twisted yarn through spinning nozzles acting on a tip portion of a hollow guide shaft and in that during a yarn picking-up operation, in addition to the whirling air currents, suction currents are generated at an opening of a tip of the hollow guide shaft to allow a fiber bundle transferred from an upper stream side to a neighborhood of the opening to be sucked into the hollow guide shaft. According to the present invention, during a yarn picking-up operation, compressed air is injected from yarn picking-up nozzles located in the hollow guide shaft in order to form air currents in the hollow guide shaft which is directed to a yarn ejection port for picked-up spinning, and in that the air currents in the hollow guide shaft are subsequently stopped so that the picked-up spinning continued with true twist spinning using a whirling air current from the spinning nozzle. According to the present invention, after the air currents in the hollow guide shaft have been stopped, a yarn-picking-up spun yarn is removed which has been produced using whirling currents from the spinning nozzles and whirling air currents from the yarn picking-up nozzles, and in that a true-twisted yarn spun using whirling air currents from the spinning nozzles is then joined with a true-twisted yam drawn out from a winding side. According to the present invention, the injection pressure of the spinning nozzles is set to be low for a predetermined amount of time after the start of yarn picking-up and is then switched to a high level. According to the present invention, after the start of yarn picking-up, the injection pressure of the spinning nozzles is switched from low to high after leading tip of fibers constituting a fiber bundle have been introduced into the spun-yarn passage. According to the present invention, a distance between an injection position of the spinning nozzles and an injection position of the yarn picking-up nozzles is substantially the same as or smaller than an average fiber length of the fibers constituting the fiber bundle. Brief Description of the Drawing Figure 1 is a side sectional view showing a spinning device according to the present invention. Figure 2 is a side sectional view showing essential parts of Figure 1 in an enlarged view. Figure 3 is a sectional view taken along line III-III in Figure 2. Figure 4 is a front view showing the overall construction of a spinning machine. Figure 5 is a schematic side view showing a spinning unit including the spinning device in Figure 1. Figure 6 is a perspective view showing the spinning unit in Figure 5. Figure 7 is a timing chart showing on and off timings for a draft device, a spinning nozzle, and a yarn picking-up nozzle according to a first and a second embodiments. Figure 8 is a timing chart showing on and off timings for a draft device, a spinning nozzle, and a yarn picking-up nozzle according to a third embodiment. Figure 9 is a side sectional view showing another example of a spinning device according to a fourth embodiment. Figure 10 is side sectional view showing yet another example of a spinning device according to the fourth embodiment. Figure 11 is a timing chart showing on and off timings for a draft device, a spinning nozzle, and a yarn picking-up nozzle which are provided on a suction error according to a fifth embodiment. Figure 12 is a timing chart showing on and off timings for a draft device, a spinning nozzle, and a yarn picking-up nozzle which are used during a normal suction according to the fifth embodiment. Figure 13 is a timing chart showing on and off timings for the draft device, the spinning nozzle, the yarn picking-up nozzle, opening and closing operations of a hollow guide shaft, and a nozzle shower according to the fifth embodiment. Figure 14 is a schematic explanatory drawing showing a conventional piecing type spinning machine. Detailed Description of the Preferred Embodiments A first embodiment of the present invention will be described with reference to the accompanying drawings. As shown in Figure 4, a spinning machine 1 comprises a large number of spinning units 2 installed in a line, a yarn joining device (yarn joining cart) 3 provided between the spinning units 2 for free running, a blower box 4, and a prime mover box 5. As shown in Figures 5 and 6, each of the spinning units 2 is provided in a casing of a main body of the spinning machine 1 and comprises a draft device D provided near an upper end of the casing, a spinning device S provided downstream of the draft device D for spinning a fiber bundle 6 transferred from the draft device D, a yarn feeding device 7 provided downstream of the spinning device S for feeding a spun yam Y, and a winding device W provided downstream of the yarn feeding device 7 for winding the spun yarn Y. As shown in Figure 6, the draft device D draws a sliver 8 comprised of untwisted short fibers to form the fiber bundle 6 and is comprised of four pairs of rollers, namely, back rollers 9, third rollers 10, middle rollers 12 around which an apron belt 11 is installed, and front rollers 13. As shown in Figure 1, the spinning device S comprises a spinning nozzle section which includes spinning nozzles 14 for blowing whirling air currents against the fiber bundle 6 while passing therethrough the fiber bundle 6 transferred from the front rollers 13, and a hollow guide shaft (hollow spindle) 15 provided opposite to the spinning nozzles 14 for applying a true twist to the fiber bundle 6 ejected from the spinning nozzles 14. The spinning device S has a needle holder 18 having a guide hole 16 for introducing the drafted fiber bundle 6 and holding a needle 17 on a channel for the fiber bundle 6 ejected from the guide hole 16, and a whirling current generation section 20 provided in tight contact with the needle holder 18 downstream thereof in a fashion covering a tip portion 19 of the hollow guide shaft 15, which will be described below, at a predetermined interval and generating a whirling current near the tip of the hollow guide shaft 15. The whirling current generation section 20 is formed to be cylindrical so as to be assembled with the needle holder 18 concentrically therewith. The whirling current generation section 20 has a spinning chamber 21 formed inside for blowing a whirling current against the fiber bundle 6 transferred from the needle holder 18, wherein the tip portion 19 of the hollow guide shaft 15 is concentrically accommodated in the spinning chamber 21. In addition, the whirling current generation section 20 has a plurality of spinning nozzles (first whirling nozzle holes) 14 formed therein for generating a whirling current in the spinning chamber 21 (near an inlet of the hollow guide shaft 15). The spinning nozzles 14 are holes of a small diameter each extending from a radial exterior of the whirling current generation section 20 to an interior of the spinning chamber 21. The spinning nozzles 14 are each formed on a tangent of the spinning chamber 21 so as to allow air to flow along an inner periphery of the whirling current generation section 20, for example, in a left-hand direction in a top view relative to a yarn running direction (counterclockwise) A, and are inclined downstream in a direction in which the fiber bundle 6 is transferred. The direction A of whirling currents from the spinning nozzles 14 depends on the direction of twisting applied to the yarn Y. The hollow guide shaft 15 has its tip portion 19 formed into a tapered cylinder and has an opening 22 formed at a tip thereof so as to face the needle 17. In addition, a spun-yarn passage 23 formed on an axis of the hollow guide shaft 15 is formed in such a manner as to broaden toward a yam ejection side. Specifically, the spun-yarn passage 23 being formed as a hole is formed in such a manner that its diameter increases sequentially and comprises a small-diameter introduction section (hole) 24 extending from the opening 22 toward the ejection side by a predetermined length, a first extended-diameter section (hole) 25 provided downstream of the introduction section 24 and having a larger diameter than the introduction section 24 in such a way as to form a stage, a second extended-diameter section (hole) 26 smoothly connected to the first extended-diameter section 25 downstream thereof and the diameter of which gradually increases in a tapered manner, and a third extended-diameter section (hole) 27 provided downstream of the second extended-diameter section 26 and having a larger diameter than the second extended-diameter section 26 in such a way as to form a stage. The third extended-diameter section 27 has an ejection port 28 formed at an ejection-side end thereof. The hollow guide shaft 15 is preferably not rotatable but may be rotatable. The hollow guide shaft 15 has a suction force generation means for sucking and introducing the fiber bundle 6 whirled in an outer periphery of the spun-yarn passage 23 by means of the spinning nozzles 14, into the spun-yarn passage 23. As shown in Figures 2 and 3, the suction force generation means is comprised of a plurality of yarn picking-up nozzles (second whirling nozzle holes) 29 for injecting compressed air against the spun-yarn passage 23 in the middle of the hollow guide shaft 15. The yarn picking-up nozzles 29 are formed at a plurality of (eight) positions in a tangential direction of the spun-yarn passage 23 so as to allow air to flow along an inner periphery of the spun-yarn passage 23 in a right-hand direction in a top view relative to the yam running direction (clockwise) B. The yarn picking-up nozzles 29 are connected to the first extended-diameter section 25 and formed at equal intervals in a circumferential direction of the spun-yarn passage 23. In addition, the hollow guide shaft 15 has an air passage 30 formed inside and extending from a neighborhood of the ejection port 28 toward the tip, where it is in communication with each yarn picking-up nozzle 29. The air passage 30 is connected to a compressed-air supply passage 31 on the ejection port 28 side. As shown in Figures 5 and 6, the yarn feeding device 7 comprises a delivery roller 7b provided in the casing of the main body of the spinning machine 1, and a nip roller 7a provided for free approaches to the delivery rollers 7b. The spun yarn Y ejected from the spinning device S is sandwiched between the delivery roller 7b and the nip roller 7a, and the delivery roller 7b is rotatively driven to feed the spun yarn Y toward the winding device W. A dust collector 56 with a suction force constantly applied thereto is provided below the ejection port 28 of the hollow guide shaft 15 for sucking and removing fluffs accumulated at the ejection port 28. The yarn joining device 3 comprises a cart main body 3a running on a rail provided on the casing of the main body of the spinning machine 1, a yarn joining section (knotter or jet splicer) 32 provided in the cart main body 3a, a suction pipe 33 provided in the cart main body 3a for free rising and lying (for pivoting), for sucking and guiding a yarn end ejected from the spinning device S to the yarn joining section 32, and a suction mouth 35 provided in the cart main body 3a for free rising and lying, for sucking a yarn end from a winding package 34 rotatably supported in the winding device W and guiding the yarn end to the yarn joining section 32. Next, the operation of the present invention will be described. The spinning machine 1 incorporates a control device (not shown in the drawings) for comprehensively controlling the operation of each section, which will be described below. To carry out joining in order to initially start the spinning machine 1 or due to yarn breakage, the yarn joining device 3 is run to the spinning unit 2 requiring joining. A sliver 8 is drawn by the draft device D, and the fiber bundle 6 thus obtained is delivered to the spinning device S. The fiber bundle 6 delivered to the spinning device S is passed through the guide hole 16 in the needle holder 18. At this point, inside the spinning device S, both the spinning nozzles 14 and the yarn picking-up nozzles 29 are injecting compressed air. Since the spinning nozzles 14 are inclined toward a downstream side of the fiber bundle 6 transfer direction and compressed air injected from the spinning nozzles 14 flows in the fiber bundle 6 transfer direction while being whirled, the fiber bundle 6 passed through the guide hole 16 in the needle holder 18 is transferred to a neighborhood of the opening 22 in the hollow guide shaft 15 by means of whirling air currents while being lightly false-twisted thereby. In addition, compressed air injected from the yarn picking-up nozzles 29 flows along an inner peripheral surface of the spun-yarn passage 23 formed in the hollow guide shaft 15, thereby forming whirling currents. Since the spun-yarn passage 23 is formed to fan out toward the spun yarn Y ejection side, compressed air injected into the spun-yarn passage 23 via the yarn picking-up nozzles 29 flows toward the spun yarn Y ejection side, and the small-diameter introduction section 24 is subjected to a negative pressure. Thus, air currents flowing in a suction direction (toward an interior of the hollow guide shaft 15) are generated at the opening 22 formed at the tip of the hollow guide shaft 15. Accordingly, the fiber bundle 6 can be continuously withdrawn into the spun-yarn passage 23. The false-twisted fiber bundle 6 transferred to the neighborhood of the opening 22 of the hollow guide shaft 15 is sucked into the spun-yarn passage 23 inside the opening 22 by means of a suction flow from the opening 22. The fiber bundle 6 reaches the first extended-diameter section 25, where it is exposed to whirling currents flowing in a direction opposite to that of currents from the spinning nozzles 14. Consequently, based on a well-known spinning technique for manufacturing a spun yarn using whirling nozzles that provide air currents flowing in opposite directions, the lightly false-twisted fiber bundle 6 is spun into fasciated fibers and ejected from the hollow guide shaft 15 as a fasciated spun yarn. The yarn picking-up nozzles 29 are not limited to the aspect that generates whirling currents flowing in a direction opposite to that of currents from the spinning nozzles 14 but any aspect can be implemented which can generate a suction force at the opening 22 in the hollow guide shaft 15. On the other hand, once the yarn end has been ejected from the hollow guide shaft 15, the yarn joining device 3, which has previously been moved to this position, is driven to allow the suction pipe 33 to suck the fasciated spun yarn Y ejected from the hollow guide shaft 15 while guiding the yarn Y to the yarn joining section 32. While being guided through the suction pipe 33, the fasciated spun yarn Y is sandwiched between the delivery roller 7b and the nip roller 7a, which are rotating continuously, for stable feeding. Subsequently, the suction force generation means for the spun-yarn passage 23 is stopped. Then, the whirling currents in the hollow guide shaft 15 disappear to complete the fasciated fiber spinning, and a normal spinning state, that is, true-twisted spinning using whirling currents from the spinning nozzles 14 is started. When the supply-side yarn is passed from the suction pipe 33 to the yarn joining section 32, all the fasciated spun yarn Y has been sucked into the suction pipe 33, whereby the true-twisting spun yarn is passed to the yarn joining section 32. In addition, the suction mouth 35 is driven in parallel with the suction pipe 33 to also pass the yarn end from the winding package 34 to the yarn joining section 32. Once the spun yarns from the suction pipe 33 and the suction mouth 35 have been passed to the yarn joining section 32, the yarn joining section 32 can be driven to join both true-twisting spun yarns together. The true-twisted yarn is a substantially true-twisted yarn having a large number of wound fibers. In order to suck and introduce the fiber bundle 6 whirled by the spinning nozzles 14, into the spun-yarn passage 23 in the above manner, suction force generation means is provided in the hollow guide shaft 15 for operating only during joining or at the initial start of joining. Thus, the supply-side fiber bundle 6 can be easily drawn into the hollow guide shaft 15 during joining or at the initial start of joining and then transferred to the downstream side of the spinning device S. At the same time, this construction can eliminate the needs for complicated preparations for allowing the winding package 34 side yarn to flow in the backward direction to the upstream side of the spinning device S, thereby simplifying the yarn joining device 3 and enabling reliable and easy spinning. In addition, since the suction force generation means comprises the plurality of yarn picking-up nozzles 29 provided in the middle of the hollow guide shaft 15 in the tangential direction of the spun-yarn passage 23, its structure can be simplified to reduce manufacturing costs while obtaining high reliability. Further, whirling currents flowing in a direction opposite to that of currents from the spinning nozzles 14 are generated in the hollow guide shaft 15, so that spinning can be achieved inside the spinning nozzles 14 to form the fiber bundle 6 into a yarn. In addition, the spun-yarn passage 23 is formed to broaden toward the spun yarn ejection side, so that compressed air injected from the yarn picking-up nozzles 29 can be transferred toward the ejection port 28 side. As a result, the opening 22 side can be subjected to a negative pressure to enable a suction flow to be easily and reliably formed at the opening 22. Further, the hollow guide shaft 15 has the air passage 30 formed inside and extending from the neighborhood of the ejection port 28 toward the tip, where it is in communication with each yarn picking-up nozzle 29, and the air passage 30 is connected to the compressed air supply passage 31 on the ejection port 28 side. Consequently, compressed air can be supplied to the yarn picking-up nozzles 29 using a simple structure. In addition, the fiber bundle 6 is formed into a yarn by means of a whirling flow in the hollow guide shaft 15. Thus, while the yarn is being guided by means of the suction pipe 33 and after it has been sandwiched between the delivery roller 7b and the nip roller 7a, the fasciated fiber spinning can be shifted to the actual twist spinning by stopping the suction force generation means. After the shifting to the actual twist spinning, the true-twisted yarn is joined with a true-twisting spun yarn on the winding package 34 side, so that the true-twisting spun yarn alone can be wound around the winding package 34. The yarn picking-up nozzle 29 may be formed so as to be inclined in the yarn feeding direction. In addition, the suction force generation means is controlled so as to start simultaneously with the start of spinning and stop during a yarn joining operation (after the yarn has been sandwiched between the delivery roller 7b and the nip roller 7a). To do this, the suction force generation means is controlled by a control device for the yarn joining device 3. Next, a second embodiment of the present invention will be described with reference to the same drawings with the first embodiment. Those members that are common to the first embodiment carry the common reference numerals in the following description, and description thereof is partly omitted. 8 is a sliver accommodated in a can 8a, and D is a four-line draft device comprising back rollers 9, third rollers 10, and second rollers (middle rollers) 12 with apron belts 11 installed thereon, and front rollers 13, the draft device being shown as an example. S is a spinning device that will be described later, and 7 is a yarn feeding device comprising a nip roller 7a and a delivery roller 7b. 36 is a slack tube operating during a yarn joining operation to temporarily store a yarn ejected from the spinning device S, which has restarted spinning, and 37 is a yarn clearer for outputting an electric signal depending on a variation in thickness of a passing yarn Y. 34 is a winding package wound around a bobbin 39 supported by a cradle 38. The winding package 34 is constructed to be rotated by a friction roller 40 that abuts on a surface of the winding package 34. 41 is a traverse guide of a traverse device (not shown in the drawings). The bobbin 39, supported by the cradle 38, the friction roller 40, the traverse guide 41, and other components constitute a winding device W. The sliver 8 is drawn out from the can 8a and drafted by the draft device D and then enters the spinning device S, where it is formed into a yarn. Subsequently, a yarn Y is ejected from the spinning device S and then transferred toward the winding package 34 while being sandwiched between the nip roller 7a and the delivery roller 7b constituting the yarn feeding device 7. Subsequently, while being traversed by the traverse guide 41, the yarn Y abuts on the friction roller 40 and is wound around the winding package 34, which is rotating. A large number of spinning units 2 are installed in a line along a frame of a spinning machine 1, wherein each of the spinning units 2 is composed of the draft device D, spinning device S, yarn feeding device 7, slack tube 36, yarn clearer 37, and winding device W described above as well as other components. Next, the spinning device S having a spinning nozzle section and a hollow guide shaft 15 that does not rotate will be described with reference to Figures 1 to 3. The spinning nozzle section has a needle holder 18 having a guide hole 16 into which a fiber bundle 6 drafted by the draft device D are introduced and holding a needle 17 mounted on a channel for the fiber bundle 6 ejected from the guide hole 16, and also has a whirling current generation section 20 covering a truncated-cone-shaped tip portion 19 of the non-rotating hollow guide shaft 15 located downstream of the needle holder 18 at a predetermined interval, and generating a whirling air current near the tip portion 19 of the hollow guide shaft 15. The whirling current generation section 20 is formed like a cylinder so as to be integrated concentrically with the needle holder 18. The whirling air current generation section 20 has a spinning chamber 21 formed therein where a whirling air current is blown against the fiber bundle 6 transferred from the needle holder 18. The tip portion 19 of the hollow guide shaft 15 is concentrically accommodated in a spinning chamber 21. In addition, a plurality of spinning nozzles 14 are formed in the whirling current generation section 20 for generating a whirling air current in the spinning chamber 21. The spinning nozzles 14 are each formed as a hole of a small diameter which is in communication with the spinning chamber 21. Each spinning nozzle 14 is formed on a tangent of the spinning chamber 21 so as to allow air to flow along an inner periphery of the whirling current generation section 20, for example, in a left-hand direction in a top view (counterclockwise) A, and is inclined downstream in a direction in which the fiber bundle 6 is transferred as shown in Figure 2. A compressed air supply member 42 having an air passage 42a formed in a fashion surrounding the spinning nozzles 14 is disposed in the spinning nozzle section and connected to a compressed air supply source (not shown in the drawings) via a pipe. The hollow guide shaft 15 is fitted in a through-hole 45 formed in a wall section 44 opposed to a wall section 43 on the front roller 13 side to which the needle holder 18 of the spinning nozzle section is attached, and has an opening 22 formed at its tip and located so as to face the needle 17. In addition, a spun-yarn passage 23 formed on an axis of the hollow guide shaft 15 is formed to broaden toward a yarn ejection port 28. Similar to the first embodiment, the spun-yarn passage 23 is formed of a small-diameter introduction section 24 extending from the opening 22 toward the yarn ejection port 28 by a predetermined length, a first extended-diameter section 25 provided downstream of the introduction section 24 and having a larger diameter than the introduction section 24 in such a way as to form a stage, a second extended-diameter section 26 smoothly connected to the first extended-diameter section 25 downstream thereof and the diameter of which gradually increases in a tapered manner, and a third extended-diameter section 27 provided downstream of the second extended-diameter section 26 and having a larger diameter than the second extended-diameter section 26 in such a way as to form a stage. The third extended-diameter section 27 has the yarn ejection port 28 formed at the yam ejection-side end thereof. The tapered extended-diameter section can be omitted to form a simple staged shape, or the downstream side of the first extended-diameter section 25 can be formed so that the tapered extended-diameter section continues up to the yarn ejection port 28. A portion of the hollow guide shaft 15 located between its truncated-cone-shaped tip portion 19 and a large-diameter section 46 near the yam ejection port 28 is formed as a smaller-diameter section 47, and an external cylinder 48 constituting the hollow guide shaft 15 is mounted in such a manner as to surround this smaller-diameter section 47. An air passage 30 is formed between the smaller-diameter section 47 and the external cylinder 48 in a fashion surrounding the smaller-diameter section 47. The smaller-diameter section 47 of the hollow guide shaft 15 has a plurality of yam picking-up nozzles 29 formed in a tangential direction of the yarn passage 23. According to this embodiment, a plurality of (eight) yarn picking-up nozzles 29 are formed at equal intervals so as to communicate with the first extended-diameter section 25 of the spun-yarn passage 23, in order to generate a whirling air current in a right-hand direction in a top view (clockwise) B. 49 is a connecting member having a pipe section 50 attached to a through-hole 54 formed in the external cylinder 48. The connecting member 49 has a compressed air supply passage (pipe) 31 connected thereto and linked to the compressed air supply source (not shown in the drawings). When compressed air is supplied to the air passage 30 in the hollow guide shaft 15 via the compressed air supply passage 31 and the connecting member 49 connected to the compressed air supply source (not shown in the drawings), the compressed air passes through the yarn picking-up nozzles 29, enters the spun-yarn passage 23, and is then ejected from the yarn ejection port 28. When compressed air is supplied from the yarn picking-up nozzles 29 in this manner, an air current is formed in the spun-yarn passage 23 of the hollow guide shaft 15, the air current flowing toward the yarn ejection port 28 from the opening 22 formed at the tip of the spun-yarn passage 23 of the hollow guide shaft 15. Next, a process of generating the spun yarn Y by the spinning unit 2 of the spinning device S constructed as described above will be outlined. The sliver 8 is drawn out from the can 8a and supplied to the draft device D, where it is drafted and is formed to the fiber bundle 6. Then, the fiber bundle 6 is moved into the guide hole 16 by means of a suction air current generated near the guide hole 16 of the needle holder 18 due to the effect of compressed air injected from the spinning nozzles 14 of the whirling air current generation section 20. Subsequently, the fiber bundle 6 is transferred along a periphery of the needle 17 and enters the spinning chamber 21. Due to the effect of whirling air currents injected from the spinning nozzles 14 and whirling at high speeds near the tip portion 19 of the hollow guide shaft 15, fibers constituting the fiber bundle 6 sucked into the spinning chamber 21 are twisted in the direction of the whirling air currents while being separated from the fiber bundle 6. In addition, part of the twist effected by the whirling air currents attempts to propagate toward the front rollers 13, but the needle 17 inhibits the propagation to prevent the fiber bundle 6 transferred from the front rollers 13 from being twisted. The fibers false-twisted as described above are sequentially formed into a true-twisted yarn Y mostly comprising wound fibers, which passes through the spun-yarn passage 23 of the hollow guide shaft 15 and is then ejected from the yarn ejection port 28. During such a normal process of generating the yarn Y, no compressed air is supplied from the compressed air supply source through the pipe 31 and the connecting member 49 to the air passage 30 of the hollow guide shaft 15. Consequently, no compressed air is supplied from the yarn picking-up nozzles 29 to an interior of the spun-yarn passage 23. In a normal spinning state, the sequentially generated true-twisted yarn Y passes through the spun-yarn passage 23 of the hollow guide shaft 15, leaves the yarn ejection port 28, and is transferred toward the winding package 34 while being sandwiched between the nip roller 7a and the delivery roller 7b constituting the yarn feeding device 7. Subsequently while being traversed by the traverse guide 41, the yarn Y is wound around the winding package 34, which contacts with the friction roller 40 and is rotating. Next, a yarn joining operation performed to start a spinning unit 2 or when yarn breakage occurs will be explained. At initially staring the spinning unit 2 or on yarn breakage, part of the draft rollers (in this case, the back rollers 9 and the third rollers 10) is stopped and no compressed air is injected from the spinning nozzles 14 or yarn picking-up nozzles 29, that is, the spinning nozzles 14 and the yarn picking-up nozzles 29 are inoperative. By rotatively driving the back rollers 9 and the third rollers 10, the fiber bundle 6, the tip of which is gripped by the third rollers 10, which have been stopped, is transferred and supplied to the spinning device S through the second rollers 12 and the front rollers 13. The draft rollers, which have been stopped, are started to be driven, and the spinning nozzles 14 and the yarn picking-up nozzles 29 are started to inject compressed air. On restart of spinning for a yarn joining operation, in the spinning device S, compressed air is being injected from the spinning nozzles 14, while compressed air is being supplied from the compressed air supply source through the pipe 31 and the connecting member 49 to the air passage 30 of the hollow guide shaft 15. Accordingly, compressed air is also being injected into the spun-yam passage 23 from the yarn picking-up nozzles 29. Since the spinning nozzles 14 inclined toward a downstream side of the fiber bundle 6 transfer direction and compressed air injected from the spinning nozzles 14 flows in the fiber bundle 6 transfer direction while being whirled, the fiber bundle 6 passed through the guide hole 16 in the needle holder 18 is transferred, by means of whirling air currents, through the needle 17 to a neighborhood of the opening 22 formed at the tip of the hollow guide shaft 15 while being lightly false-twisted thereby. In addition, compressed air injected from the yarn picking-up nozzles 29 flows along an inner peripheral surface of the spun-yarn passage 23 formed in the hollow guide shaft 15, thereby forming whirling air currents. Since the spun-yarn passage 23 is formed to fan out toward the yarn ejection port 28, compressed air injected into the spun-yarn passage 23 via the yarn picking-up nozzles 29 flows toward the yarn ejection port 28 side, and the small-diameter introduction section 24 is subjected to a negative pressure. Thus, air currents flowing in a suction direction (toward an interior of the hollow guide shaft 15) are generated at the opening 22 formed at the tip of the hollow guide shaft 15. Accordingly, the fiber bundle 6 can be continuously withdrawn into the spun-yarn passage 23 of the hollow guide shaft 15. The false-twisted fiber bundle 6 transferred to the neighborhood of the opening 22 formed at the tip of the hollow guide shaft 15 is sucked into the spun-yarn passage 23 from the opening 22 by means of a suction flow from the opening 22. The fiber bundle 6 passes through the small-diameter introduction section 24 and reaches the first extended-diameter section 25, where it is exposed to whirling air currents flowing in a direction opposite to that of whirling air currents formed by the spinning nozzles 14 in the spinning nozzle section. Consequently, based on a well-known spinning technique for manufacturing a spun yarn using whirling air currents flowing in opposite directions, the lightly false-twisted fiber bundle 6 is spun into a yarn in the form of fasciated fibers (a fasciated yarn) and ejected from the yarn ejection port 28 of the hollow guide shaft 15. Such spinning of the yarn in the form of fasciated fibers using the spinning nozzles 14 and the yarn picking-up nozzles 29 is called "picked-up spinning". On the other hand, the yarn joining device 3, which is run to a spinning unit that requires joining and has been stopped, is driven, and the fasciated yarn ejected from the yarn ejection port 28 of the hollow guide shaft 15 is guided to a yarn joining section 32 comprising a knotter or a splicer while being sucked into a suction pipe 33 acting as yarn suction means of a spinning-side. While being guided to the yarn joining section 32 by means of the suction pipe 33, the fasciated yarn is sandwiched by the nip roller 7a and delivery roller 7b constituting the yarn feeding device 7, for stable feeding. Subsequently, the supply of compressed air from the compressed air supply source to the yarn picking-up nozzles 29 is stopped to halt the injection of compressed air into the spun-yarn passage 23 from the yarn picking-up nozzles 29. Then, the whirling air currents in the hollow guide shaft 15 disappear to complete the picked-up spinning of the fasciated yarn using whirling air currents flowing in opposite directions as described above. Then, the yarn Y is subjected to normal spinning, that is, whirling air currents from the spinning nozzles 14 in the spinning nozzle section are used to spin the true-twisted yarn. When the spinning-side yarn is passed from the suction pipe 33 of the yarn joining device 3 to the yarn joining section 32 thereof, all of the fasciated yarn is sucked into the suction pipe 33 so that the true-twisted yarn is passed to the yarn joining section 32. On the other hand, in parallel with this operation of the suction pipe 33, the suction mouth 35 (yarn suction means of a winding-side) of the yarn joining device 3 is driven to also pass a winding package 34-side yarn end to the yarn joining section 32. Once the suction pipe 33-side yarn and the suction mouth 35-side yarn have been passed to the yarn joining section 32, the yarn joining section 32 is driven to join both yarns together to complete the yarn joining operation. In this manner, when the yarn joining section 32 carries out joining, all of the fasciated yarn is sucked into the suction pipe 33 so that the true-twisted yarn is joined with the winding package 34-side yarn. As described above, to suck and guide the fiber bundle 6, which has been whirled by the spinning nozzle section, into the spun-yarn passage 23 of the hollow guide shaft 15 for a yarn joining operation after yarn breakage or at the initial start of spinning, means is provided at the opening 22 formed at the tip of the hollow guide shaft 15, for generating an air flow moving in a suction direction (toward the interior of the hollow guide shaft 15). Consequently, during a yarn joining operation, the spinning-side fiber bundle 6 can be easily withdrawn into the hollow guide shaft 15, and the fasciated yarn can be ejected from the yarn ejection port 28 of the hollow guide shaft 15, resulting in a reliable and prompt yarn joining operation. In addition, the spinning nozzles 14 formed in the spinning nozzle section are used to carry out normal yarn spinning, and the yarn picking-up nozzles 29 formed in the hollow guide shaft 15 are operated to carry out picked-up spinning only for a yarn joining operation after yarn breakage or at the initial start of spinning. This construction can simplify the structure of the spinning machine, reduce manufacturing costs of the spinning machine, and improve the reliability of the spinning machine. Further, if only the injection of compressed air from the yarn picking-up nozzles 29 formed in the hollow guide shaft 15 needs to be stopped or resumed only for a yarn joining operation after yarn breakage or at the initial start of spinning, the control system of the spinning machine can be simplified to improve the stability and reliability of the control system. In addition, since whirling air currents flowing in the direction opposite to that of whirling air currents in the spinning nozzles are generated in the hollow guide shaft 15, spinning can be carried out inside the spinning nozzle section to form the fiber bundle 6 into a yam, thereby precluding the fiber bundle 6 from being cut during a yarn joining operation. Further, since the spun-yarn passage 23 in the hollow guide shaft 15 is formed to broaden toward the yarn ejection port 28 side from the opening 22 formed at the tip of the spun-yarn passage 23, compressed air injected from the yarn picking-up nozzles 29 can be transferred toward the yam ejection port 28 side and the opening 22 side can be subjected to a negative pressure. Accordingly, a suction flow can be easily and reliably formed at the opening 22. During picked-up spinning, whirling air currents in the hollow guide shaft 15, in cooperation with whirling air currents in the spinning nozzle section, form the fiber bundle 6 into a fasciated yarn, which is sucked into the suction pipe 33 of the yarn joining device 3 and sandwiched between the nip roller 7a and delivery roller 7b constituting the yarn feeding device 7 while being moved toward the yarn joining section 32 in concert with downward rotative movement of the suction pipe 33. After the fasciated yarn has been sandwiched between the nip roller 7a and the delivery roller 7b in this manner, the supply of compressed air from the compressed air supply source to the yarn picking-up nozzles 29 is stopped so that a feeding force applied by the yarn feeding device 7 can be used to shift the spinning device S from the spinning of the fasciated yarn, that is, the picked-up spinning to the normal spinning of a true-twisted yarn. After shifting to the true-twisted yam, this true-twisted yarn and a true-twisted yarn drawn out from the winding package 34 are joined together, whereby only the true-twisted yarn is wound around the winding package 34. The above embodiment has been shown with the example in which compressed air injected from the yarn picking-up nozzles 29 formed in the hollow guide shaft 15 is used to generate whirling air currents in the hollow guide shaft 15 which flow in the direction opposite to that of whirling air currents in the spinning nozzle section. The most important point, however, is that a suction flow is formed at the opening 22 formed at the tip of the hollow guide shaft 15 and causes the false-twisted fiber bundle 6 transferred to a neighborhood of the opening 22 to be sucked into the yarn passage 23 from the opening 22, the yam then being ejected from the yarn ejection port 28. Thus, even when the yarn-like fiber bundle 6 false-twisted and generated by means of whirling air currents in the spinning nozzle section is exposed to compressed air injected from the yarn picking-up nozzles 29 of the hollow guide shaft 15, if the yarn-like fiber bundle 6 can be ejected from the yarn ejection port 28 of the hollow guide shaft 15 while maintaining its yarn-like state and can then be sucked into the suction pipe 33 and guided to the yarn joining section 32, then air currents formed in the spun-yarn passage 23 by means of compressed air injected from the yarn picking-up nozzles 29 formed in the hollow guide shaft 15 are not limited to whirling air currents but may be straight currents that do not whirl and that flow toward the yarn ejection port 28 from the opening 22 formed at the tip of the hollow guide shaft 15 or whirling air currents flowing in the same direction as whirling air currents in the spinning nozzle section. Next, drive timing for the back rollers 9, the third rollers 10, the spinning nozzles 14, and the yarn picking-up nozzles 29 will be described with reference to Figure 7. To start initial normal spinning, the draft device D is driven including the back rollers 9 and third rollers 10 that can be driven or stopped via a clutch or the like, and at the same time, the spinning nozzles 14 and the yarn picking-up nozzles 29 are both turned on to inject compressed air therefrom for picked-up spinning as described above. Subsequently, after a predetermined amount of time, the yarn picking-up nozzles 29 are turned off to stop the injection of compressed air therefrom, thereby shifting the spinning machine to the normal spinning, that is, the true-twisted spinning. When the yarn Y is cut, the clutch is released to stop the driving of the back rollers 9 and third rollers 10 in order to cut the sliver 8 (fiber bundle 6) between the third rollers 10, which have been stopped, and the second rollers 12, which are continuously rotating. A second roller 12-side fiber bundle 6 obtained by the cutting is formed into the yarn Y by means of the spinning device S and yarn feeding device 7, which are being continuously driven, and the yarn Y thus produced is sucked and removed by a yarn scrap suction means. After the yam Y produced by the second roller 12-side fiber bundle 6 obtained by the cutting has been spun out, the spinning nozzles 14 are turned off to stop the injection of compressed air therefrom. A yarn cutting device (cutter) and a slack tube 36 acting as the yarn scrap suction means are located immediately downstream of the yarn feeding device 7. To perform a yarn joining operation, the back rollers 9 and third rollers 10, which have been stopped, are re-driven, and at substantially the same time, the spinning nozzles 14 and the yarn picking-up nozzles 29 are both turned on to inject compressed air therefrom for picked-up spinning as described above. Subsequently, after a predetermined amount of time (after first fibers constituting the fiber bundle 6 have been sucked into the spun-yarn passage 23), the yarn picking-up nozzles 29 are turned off to stop the injection of compressed air therefrom, thereby shifting the spinning machine to the normal spinning, that is, the true-twisted spinning. On yarn breakage, the yarn joining device 3 reaches a spinning unit in which the yarn breakage has occurred, and this spinning unit stands by until a yarn joining operation including the above picked-up spinning is started. In the above embodiment, the object of turning off the spinning nozzles 14 on yarn breakage is to save energy, and the spinning nozzles 14 need not necessarily be turned off on yarn breakage but remain on both during normal spinning and during picked-up spinning. To initially start spinning or replace a full package with an empty bobbin, a bobbin 39 around which an amount of yarn required for a yarn joining operation has been wound is installed in the cradle 38. Next, a third embodiment of the present invention will be described. According to the third embodiment, the spinning device S has switching means for switching an injection pressure of the spinning nozzles 14 to a high or low level. Although not shown, the switching means is comprised of a solenoid controlled directional control valve provided in the middle of a compressed air passage joining the spinning nozzles 14 and a compressed air source together and the control device for electrically switching the solenoid controlled directional control valve. Description of constructions and effects common to the first and second embodiments is omitted as appropriate. Next, a yarn joining method according to this embodiment will be described. To perform a yarn joining operation to initially start the spinning machine 1 or due to yarn breakage, the yarn joining device 3 is run to a spinning unit 2 that requires yarn joining, all the rollers of the draft device D are actuated (turned on), and the spinning nozzles 14 and the yarn picking-up nozzles 29 are actuated (turned on) to inject compressed air. As shown in Figure 8, at a time T o when yarn joining is started, the spinning nozzles 14, the yarn picking-up nozzles 29, and the back rollers 9 (and the third rollers 10) of the draft device D (B/R) are turned on. At this point, the switching means has been switched to a low-pressure side, so that the spinning nozzles 14 inject compressed air at a low pressure P L . In the draft device D, the sliver 8 is drawn into the fiber bundle 6, which is delivered to the spinning device S. The fiber bundle 6 transferred to the spinning device S is inserted into the guide hole 16 in the needle holder 18. Compressed air injected from the spinning nozzles 14 flows in the fiber bundle 6 transfer direction while whirling. Thus, the fiber bundle 6 inserted into the guide hole 16 in the needle holder 18 is transferred to a neighborhood of the opening 22 in the hollow guide shaft 15 by means of whirling currents while being lightly false-twisted thereby. In addition, compressed air injected from the yarn picking-up nozzles 29 flows through the spun-yarn passage 23 formed in the hollow guide shaft 15, along its inner peripheral surface to form whirling currents. Since the spun-yarn passage 23 is formed to fan out toward the spun yarn Y ejection side, compressed air injected into the spun-yarn passage 23 from the yarn picking-up nozzles 29 flows toward the ejection port 28, and the small-diameter introduction section 24 and the opening 22 are subjected to a negative pressure. Thus, a suction force is generated at the opening 22 of the hollow guide shaft 15 and enables the first fiber bundle 6 (fibers) to be trapped and introduced into the opening 22. In addition, after the introduction, the fiber bundle 6 can be continuously withdrawn. The fiber bundle 6 reaches the first extended-diameter section 25, where it is exposed to whirling currents flowing in a direction opposite to that of currents from the spinning nozzle section. Consequently, based on a well-known spinning technique for manufacturing a spun yarn using whirling nozzles that provide air currents flowing in opposite directions, the lightly false-twisted fiber bundle 6 is spun into a fasciated spun yarn Y in the form of fasciated fibers and ejected from the ejection port 28 of the hollow guide shaft 15. At this point, the whirling currents provide a feed force toward the ejection port 28. On the other hand, before the ejection, the suction pipe 33 of the yarn joining device 3 is swiveled upward so that an inlet of the suction pipe 33 faces the ejection port 28. Then, when an end of the fasciated spun yarn Y is ejected from the ejection port 28, it is sucked and trapped by the suction pipe 33 and the fasciated spun yarn Y is drawn into the suction pipe 33. Then, when the suction pipe 33 is swiveled downward (see the solid line in Figure 5), the fasciated spun yarn Y is guided to the yarn joining section 32. As shown in Figure 8, after the suction into the suction pipe 33 has been completed, the switching means is switched to a high level side to allow the spinning nozzles 14 to inject compressed air at a high pressure P H . In this manner, the switching means switches the lower pressure to the high pressure at a time T 1 , that is, a predetermined amount of time ΔT after the time T 0 . When the injection pressure of the spinning nozzles 14 is zeroed between the time T 0 and the time T 1 , that is, the spinning nozzles 14 are stopped during this period, fibers are splashed from the ejection port 28 of the hollow guide shaft 15 with no twisting propagated because the distance between the yarn picking-up nozzles 29 and a nip point of the front rollers 13 is larger than an average fiber length. Thus, the lower pressure P L must not be zero. In addition, by setting the spinning nozzles at the low pressure P L , which is not zero, a suction force is applied to an inlet of the guide hole 16 in the spinning nozzle section to enable the reliable introduction of the fiber bundle 6 exiting the front rollers 13, thereby improving the success rate of joining. While being guided to the yarn joining section 32, the fasciated spun yarn Y is sandwiched between the delivery roller 7b and the nip roller 7a (at the time T 2 in Figure 8), which are continuously rotating, and a predetermined amount of time later, the yarn picking-up nozzles 29 are turned off. This eliminates the feed force applied by the yam picking-up nozzles 29, and the rollers 7a,7b then apply a feed force to the entire yarn located upstream of the rollers 7a,7b. That is, the feed force is converted. In this manner, fasciated fiber spinning based on cooperation between the spinning nozzles 14 and the yarn picking-up nozzles 29 shifts to normal true-twisted spinning based on cooperation of the spinning nozzles 14, the hollow guide shaft 15, the delivery roller 7b and the nip roller 7a. After a while, all of the fasciated spun yarn Y is sucked into the suction pipe 33, and the true-twisting spun yarn is passed to the yarn joining section 32. In order to produce normal true-twisting spun yarns, the spinning nozzles 14 must be switched to the high level P H before the start of true-twisted spinning following turning-off of the yarn picking-up nozzles 29, at the latest. Concurrently with this delivery to the yarn joining section 32, the winding package 34-side true-twisting spun yarn is passed to the yam joining section 32 by means of a swiveling operation of the suction mouth 35. Once both the suction pipe 33-side true-twisting spun yarn and the suction mouth 35-side true-twisting spun yarn have been passed to the yarn joining section 32, the yarn joining section 32 is driven to join both true-twisting spun yarns together. Thus, the yarn joining is completed and only the true-twisting spun yarn is wound around the winding package 34. In this manner, the present device includes the yarn picking-up nozzles 29 so that during joining, the yarn can sequentially be transferred and ejected from the ejection port 28. Thus, the ejected yarn can be sucked into the suction pipe 33, which then swivels to allow the yarn to be sandwiched between the delivery roller 7b and the nip roller 7a to convert the feed force, while the yarn is simultaneously guided to the yarn joining section 32 for joining. This eliminates complicated preparations for allowing the yarn to flow backward through the hollow guide shaft 15 as in the conventional devices, thereby enabling easy and reliable joining. The above joining includes the step of picking up the yarn from the hollow guide shaft 15 using the spinning nozzles 14 and the yam picking-up nozzles 29. During this step, the injection pressure of the spinning nozzles 14 is maintained at the low level (P L ) for the predetermined amount of time ΔT after the start of joining and is then switched to the high pressure P H . Then, the first fibers can be easily introduced into the hollow guide shaft 15. That is, by setting the injection pressure of the spinning nozzles 14 to be low (low pressure P L ), the resulting whirling currents are weakened to restrain the whirling of the fibers to facilitate propagation of twisting, thereby allowing the first fibers to be easily introduced into the opening 22 of the hollow guide shaft 15. That is, although the opening 22 is subjected to a negative pressure simultaneously with the turning-on of the yarn picking-up nozzles, the restraint of the whirling of the fibers allows the fibers to be more easily trapped using this negative pressure, thereby increasing the yarn picking-up success rate. This in turn increases the joining success rate and improves reliability. In addition, the dependency on the spinning nozzle shape decreases, that is, the effects of the spinning nozzles on the introduction of the fibers lessen, so that the joining success rate is not substantially affected by the variation of the spinning nozzle shape. This in turn makes the present invention applicable to various spinning nozzles. The injection pressure of the spinning nozzles 14 may be switched from low to high after the introduction of the first fibers into the spun-yarn passage 23 at the latest. That is, the predetermined amount of time ΔT is preferably sufficient to allow a yarn picking-up operation to be reliably completed within this amount of time. As shown by the imaginary line in Figure 8, the first fibers are difficult to introduce if the injection pressure of the spinning nozzles 14 is high (P H ) at the start of joining. The present device solves this problem. On the other hand, since the spinning nozzles 14 return to the high pressure P H , which is used for normal operations, after the introduction of the fibers into the hollow guide shaft 15, the yarn can be reliably picked up based on self spinning. In particular, once the fibers have entered the hollow guide shaft 15 and twisting has propagated, the fibers are formed into a yarn, which can then be withdrawn into the hollow guide shaft 15. Therefore, the injection pressure is advantageously high after the introduction. Various other embodiments of the present invention may be contemplated. Various constructions of the switching means may also be contemplated. A fourth embodiment of the present invention will be described. Description of constructions and effects common to the first to third embodiments is omitted as appropriate. As shown in Figure 1, a hollow guide shaft 15 is comprised of a main body 51 comprising a truncated cone-shaped tip portion 19 and a smaller-diameter section (internal cylinder) 47 formed integrally with the tip portion 19 and having a smaller outer diameter than the tip portion 19, and an external cylinder 48 fitted on a peripheral stage portion 52 formed at an internal cylinder 47-side peripheral end of the tip portion 19, the external cylinder 48 being also fitted on a bulging portion 46 formed at an end portion of the internal cylinder 47. The tip portion 19 has an introduction section 24 formed therein and passing through its axis. The introduction section 24 has a diameter smaller than the inner diameter of the internal cylinder 47. The introduction section 24 and a space section in the internal cylinder 47 constitute a spun-yarn passage 23 continuously extending from an opening 22 and an ejection port 28. As described above, during a yarn joining operation, a false-twisted fiber bundle 6 is transferred to a neighborhood of the opening 22 formed at the tip of the hollow guide shaft 15 and is then sucked into the spun-yarn passage 23 from the opening 22 by means of a suction flow from the opening 22 in the hollow guide shaft 15. The fiber bundle 6 is then simultaneously subjected to the effects of whirling air currents formed by compressed air injected from spinning nozzles 14 in a spinning nozzle section and whirling near the tip portion 19 of the hollow guide shaft 15 at a high speed and to the effects of whirling air currents formed by compressed air injected from yarn picking-up nozzles 29 in the hollow guide shaft 15, whereby the lightly false-twisted fiber bundle 6 is spun into a fasciated yarn. At this point, a needle 17 located on a yarn path between the hollow guide shaft 15 and front rollers 13 prevents propagation of false twisting to the front rollers 13, thereby enabling the fibers to be whirled by whirling air currents from the spinning nozzles 14 to generate a more robust fasciated yarn. During the process of forming the lightly false-twisted fiber bundle 6 into the fasciated yarn as described above, if the lightly false-twisted fiber bundle 6 remains as it is without being formed into the fasciated yarn, it may be cut during the yarn joining operation due to its weakness, resulting in a joining error. One reason why the lightly false-twisted fiber bundle 6 fails to be formed into the fasciated yarn is that the distance between the injection position of each spinning nozzle 14 (near a tip surface 53 of the hollow guide shaft 15) and the injection position of each yarn picking-up nozzle 29 is larger than the average fiber length of the fibers constituting the fiber bundle 6, so that most fibers fail to be simultaneously subjected to the effects of whirling air currents formed by compressed air injected from the spinning nozzles 14 in the spinning nozzle section and whirling near the tip portion 19 of the hollow guide shaft 15 and to the effects of whirling air currents formed by compressed air injected from the yarn picking-up nozzles 29 in the hollow guide shaft 15. Thus, by forming the yarn picking-up nozzles 29 as close to the tip surface 53 of the hollow guide shaft 15 as possible, the distance between the injection position of each spinning nozzle 14 and the injection position of each yarn picking-up nozzle 29 can be set substantially equal to or smaller than the above average fiber length to prevent a joining error originating from the structure of the hollow guide shaft 15 as described above. In addition, with the short tip portion 19, a bonded location between the peripheral stage portion 52 formed at the tip portion 19 and the external cylinder 48 is affected by whirling air currents formed by compressed air injected from the spinning nozzles 14 in the spinning nozzle section and whirling near the tip portion 19 of the hollow guide shaft 15, whereby the fibers constituting the fiber bundle 6 and which are whirled by the whirling air currents are caught on the bonded location, resulting in yarn breakage. Another hollow guide shaft 160 that can solve this problem will be described below with reference to Figure 9. According to this embodiment, the hollow guide shaft 160 has a main body 160c comprising a truncated cone-shaped tip portion 160a similar to the above truncated cone-shaped tip portion 19 and a cylindrical portion 160b that is contiguous to the tip portion 160a and that is formed integrally with the tip portion 160a. The main body 160c has a space section extending beyond the cylindrical portion 160b into the truncated cone-shaped tip portion 160a and toward a tip surface (a surface closer to a needle holder 18) 160d of the tip portion 160a. The space section inside the truncated cone-shaped tip portion 160a is shaped like a truncated cone, and the tip portion 160a has a substantially constant thickness in its portion in which the truncated cone-shaped space section is located. The tip portion 160a has a small-diameter introduction section 160e similar to the above small-diameter introduction port 24 formed in its portion in which the truncated cone-shaped space section is not formed. In addition, a recess 160f is formed in a side wall of the tip portion 160a which is located in the space section of the tip portion 160a. 160g is an internal cylinder member that is inserted into the space section formed inside the main body 160c and that has a projection 160h at one end which is fitted over the recess 160f formed in the side wall of the tip portion 160a of the main body 160c which is located in the space section of the tip portion 160a. The projection 160h has an internal cylinder member 160g-side introduction hole 160i formed in the tip portion 160a and having the same diameter as the introduction hole 160e. The internal cylinder member 160g, except for the internal cylinder member 160g-side introduction port 160i, has a larger inner diameter than the introduction holes 160e, 160i, and the introduction holes 160e, 160i and the space section inside the internal cylinder member 160g form a yarn passage 160j similar to the above spun-yarn passage 23. 160k is yarn picking-up nozzles that are similar to the above yarn picking-up nozzles 29 in the hollow guide shaft 15 and which are formed in the internal cylinder member 160g. The yarn picking-up nozzles 160k are formed close to the projection 160h. 160m is a bulging portion that is similar to the bulging portion 46 of the hollow guide shaft 15 and that is formed integrally with an outer periphery of the internal cylinder member 160g located opposite to the projection 160h. An end of the cylindrical portion 160b of the main body 160c is fitted on the bulging portion 160m. The hollow guide shaft 160 is formed by using an adhesive to fit the projection 160h formed on the internal cylinder member 160g, in the recess 160f formed in the side wall of the tip portion 160a of the main body 160c that is located in the space section of the tip portion 160a and also using an adhesive to fit the bulging portion 160m of the internal cylinder member 160g on the cylindrical portion 160b of the main body 160c. An air passage 160n similar to the above air passage 30 in the hollow guide shaft 15 is formed between the main body 160c and the internal cylinder member 160g disposed in the main body 160c. The cylindrical portion 160b of the main body 160c has a through-hole 160p formed in its portion located near the bulging portion 160m of the internal cylinder member 160g, and the through-hole 160p has the above pipe section 50 of the connecting member 49 connected thereto. With the above construction, the distance between the injection position of each spinning nozzle 14 (near the tip surface 160d of the hollow guide shaft 160) and the injection position of each yarn picking-up nozzle 160k can be set to be substantially equal to or smaller than the average fiber length of the fibers constituting the fiber bundle 6. Accordingly, the fiber bundle 6 can simultaneously undergo the effects of whirling air currents formed by compressed air injected from spinning nozzles 14 in the spinning nozzle section and whirling near the tip portion 160a of the hollow guide shaft 160 and the effects of whirling air currents formed by compressed air injected from the yarn picking-up nozzles 160k in the hollow guide shaft 160. As a result, a lightly false-twisted fiber bundle 6 can be formed into a strong fasciated yarn, thereby preventing a joining error arising from the structure of the hollow guide shaft 160. In addition, the main body 160c of the hollow guide shaft 160, which is contacted by the fibers constituting the fiber bundle 6 and whirled by whirling air currents formed by compressed air injected from the spinning nozzles 14 of the spinning nozzle section, is integrally formed, that is, a junction between the main body 160c including the tip portion 160a and the internal cylinder member 160g with the yarn picking-up nozzles 160k formed therein is not located on an outer periphery of the tip portion, which may be contacted by the fibers, but inside the main body 160c. Accordingly, a bonded location between the peripheral stage portion 52 formed at the tip portion 19 and the external cylinder 48 is not located on the outer periphery of the tip portion as in the above hollow guide shaft 15. Therefore, the fibers constituting the fiber bundle 6 and whirled on the outer periphery of the tip portion 160a by means of the whirling air currents are prevented from being caught on the bonded location, thereby preventing yarn breakage. Yet another hollow guide shaft 161 will be explained with reference to Figure 10. According to this embodiment, a main body 160c comprising the above truncated cone-shaped tip portion 160a and the cylindrical portion 160b formed integrally with the tip portion 160a is divided into two by separating the truncated cone-shaped tip portion 160a into two at a position near a recess 160f formed in a side wall of the tip portion 160a that is located in a space section thereof. The two pieces of the main body 160c are joined together using an appropriate adhesive. Such a main body 160c of a divided structure can reduce manufacturing costs of the hollow guide shaft compared to the integral structure. The remaining part of the construction is the same as in the hollow guide shaft 160 shown in Figure 9, and detailed description thereof is omitted. According to this embodiment, a junction 161c between a truncated cone-shaped tip portion 161a and a cylindrical portion 161b having a truncated cone-shaped tip has a bonded location formed thereon in contrast to the embodiment shown in Figure 9. Similarly to the two-piece hollow guide shaft 160 shown in Figure 9, however, the yarn picking-up nozzles 160k can be located close to a tip surface 160d of the hollow guide shaft 160, so that the fiber bundle 6 can simultaneously undergo the effects of whirling air currents formed by compressed air injected from spinning nozzles 14 in the spinning nozzle section and whirling near the tip portion 160a of the hollow guide shaft 160 and the effects of whirling air currents formed by compressed air injected from the yarn picking-up nozzles 160k in the hollow guide shaft 160. As a result, a lightly false-twisted fiber bundle 6 can be formed into a strong fasciated yam, thereby preventing a joining error. Although the members constituting the hollow guide shafts 160, 161 can be separately formed and subsequently glued together via an appropriate adhesive to form the hollow guide shafts 160, 161, these constituent members can alternatively be molded using ceramics powders and subsequently sintered in a sintering furnace to manufacture the hollow guide shafts 160, 161. The use of ceramics can preclude the formation of a projection on which the fibers constituting the fiber bundle 6 may be caught as in the above-mentioned use of adhesive, and can also prevent the yarn picking-up nozzles 160k from being blocked with the adhesive, thereby improving the yield of the hollow guide shafts 160, 161. Although the above embodiment is shown with the example in which the hollow guide shafts 160, 161 are divided into two or three, the hollow guide shafts can alternatively be divided into four or more as appropriate and subsequently assembled together via an adhesive. Next, a fifth embodiment will be described with reference to Figures 5, 11, and 12. Description of constructions and effects common to the first to fourth embodiments is omitted as appropriate. As shown in Figure 5, a suction pipe 33 has a yarn detection sensor 55 provided in the middle thereof for detecting the presence of a yarn in the pipe. In this embodiment, the yarn detection sensor 55 is comprised of an optical sensor. This spinning machine 1 incorporates a control device (not shown in the drawings) for comprehensively controlling the operation of each section described below. In particular, the control device determines whether or not a yarn is present in the suction pipe 33, based on a detection result obtained by the yarn detection sensor 55. In a draft device D, back rollers 9 are connected to a constantly rotating line shaft via a clutch (not shown in the drawings) independently of other rollers 12, 13. The clutch is engaged and released by means of a fluid cylinder (not shown in the drawings), and the operation of the fluid cylinder is controlled by the above control device. Next, the operation of the fifth embodiment will be described. During a yarn joining operation, if a fasciated spun yarn Y exiting the hollow guide shaft 15 cannot be trapped in the suction pipe 33 or a fasciated spun yarn Y that has been self-spun is cut when sucked into the suction pipe 33, due to its insufficient strength, a suction error occurs and the yarn leaving the ejection port 28 in the hollow guide shaft 15 is sucked by a relatively weak force, into a dust collector 56 located below instead of being sucked into the suction pipe 33. Then, no feed force is applied to the yarn, and when the draft device D continuously supplies fibers, some of the nozzles or the hollow guide shaft 15 may be choked. When fibers continue to be supplied, these fibers are continuously transferred to the choked nozzles (that are blocked with fluffs) to cause the front rollers 13 of the draft device D to be worn or damaged. Since the wear of the front rollers 13 seriously affects the yarn properties, appropriate action must be taken. Naturally enough, such a suction error hinders joining and the corresponding unit is stopped. Thus, this embodiment provides the yarn detection sensor 55 for detecting the presence of a yarn in the suction pipe 33 so that based on a detection result, the control device can control the operation of the draft device D, spinning nozzles 14, and yarn picking-up nozzles 29. This control will be described below. First, as shown in Figure 12, during normal joining, the suction pipe 33 normally sucks a yarn end and at a predetermined point of time T 0 , the yarn detection sensor 55 detects the presence of the yarn. The detection of the presence of a yarn carried out by the yarn detection sensor 55 is not a very short instantaneous check but a check lasting slightly longer. This enables the absence of a yarn to be reliably detected even if the yarn is cut immediately after being trapped in the suction pipe 33. At this point, the back rollers 9 (B/R) and other rollers 10, 12, 13 of the draft device D remain on, and the spinning nozzles 14 and the yarn picking-up nozzles 29 remain on. An amount of time ΔT 2 later, the yarn picking-up nozzles 29 are turned off, as described above. During the time ΔT 2 , the yarn is sandwiched between the delivery roller 7b and the nip roller 7a, and after the yarn picking-up nozzles 29 have been turned off, the joining machine shifts to normal true-twist spinning. The time T 0 is set at a point of time corresponding to the passage of a predetermined amount of time since theturning-on of the back rollers 9 and third rollers 10 carried out simultaneously with the start of joining after the suction and trapping of the fasciated spun yarn Y ejected from the ejection port 28 by the suction pipe 33 has been completed. On the other hand, on a suction error, the yarn detection sensor 55 detects the absence of a yarn, and at this moment, the back rollers 9 and the third rollers 10 are turned off to suspend the supply of fibers. The other rollers 12, 13 of the draft device D, the spinning nozzles 14, and the yarn picking-up nozzles 29 are turned on for a predetermined amount of time ΔT 1 , and this amount of time ΔT 1 later, the rollers 12, 13 and the nozzles 14 and 29 are turned off. In this manner, if a suction error occurs, the back rollers 9 and the third rollers 10 are immediately stopped, whereby the supply of fibers is aborted to prevent the nozzles and the hollow guide shaft 15 from being choked, while precluding the front roller 13 from being worn or damaged. In addition, during ΔT 1 , the spinning nozzles 14 and the yarn picking-up nozzles 29 are operated, so that the third rollers 10 can eject as a yarn, fibers remaining in a downstream side of the draft device D, also preventing choking. This prevention of choking also enables a plurality of joining (knotting n times) operations to be performed. On a suction error, after the spinning nozzles 14 and the yarn picking-up nozzles 29 have been turned off (after ΔT 1 has elapsed), all the rollers of the draft device D, the spinning nozzles 14, and the yarn picking-up nozzles 29 may be turned on again so that another attempt can be made to suck the yarn into the suction pipe 33. If a predetermined number of errors occur continuously, an alarm may be output. According to this embodiment, the yarn detection sensor 55 is provided in the middle of the suction pipe 33, that is, on the yarn joining section 32 side. This eliminates the need to provide the sensor in individual spinning units 2 to minimize the number of sensors required, thereby simplifying the machine and reducing costs. As described above, the back rollers 9 of the draft device D are actuated and stopped by controlling the fluid cylinder to engage or release the clutch. Conventionally, once driving of the back rollers 9 has been started during joining, they cannot be stopped for a fixed amount of time determined by a predetermined cam shape. This may cause some of the nozzles to be choked. According to this embodiment, the operation of the back rollers 9 is controlled using the fluid cylinder, so that based on a detection result obtained from the yarn detection sensor 55, the back rollers 9 can be actuated or stopped with arbitrary timings. Moreover, the fluid cylinder may be replaced with a solenoid or the like, that is, any device that can switch the operation of the back rollers based on an electric signal. According to this embodiment, the yarn picking-up nozzles 29 can be used as cleaning nozzles in the above manner. That is, during a spinning stoppage (while the back rollers 9 are stopped), compressed air can be injected from the yarn picking-up nozzles 29 for a predetermined amount of time. In this case, the hollow guide shaft 15 may be adapted for free opening and closing with respect to the spinning nozzle section including the spinning nozzles 14 so that during spinning, as shown in Figure 13, the hollow guide shaft 15 is closed with respect to the spinning nozzle section, whereas during a spinning stoppage, the hollow guide shaft 15 is open and compressed air is injected from the yarn picking-up nozzles 29 for a predetermined amount of time. By opening the hollow guide shaft 15, fibers joining the hollow guide shaft 15 and the spinning nozzle section can be torn off in the middle for edge cut. In addition, in recovering the open hollow guide shaft 15 to a closed state (a spinning position), compressed air may be injected from the spinning nozzles 14 for recovery. This operation enables a tip of the hollow guide shaft 15 to enter a working area of the spinning nozzles 14 to whirl and remove fibers remaining at the tip of the hollow guide shaft 15 and each having a free end. As described above, by performing a cleaning operation during a spinning stoppage based on a yarn breakage signal, even if yarn breakage occurs due to choking of any nozzles or the hollow guide shaft 15, fibers remaining in the hollow guide shaft 15 can be automatically removed. This construction prevents ends down (machine stoppage) that disables automatic joining, thereby improving the operating efficiency. The nozzle shower in Figure 13 refers to injection of compressed air against an introduction hole of the spinning nozzle section (an inlet of a guide hole 16), an injection that enables fibers remaining in the introduction hole of the spinning nozzle section to be removed. In Figure 13, the automatic cleaning operation during a spinning stoppage is divided into sections I to III, but the sections II and III may be repeated a number of times. Due to the above constructions, the present invention has the following effects. The present invention eliminates the need for piecing that requires a leading yarn to thread through the spinning device backward, thereby reducing errors during preparations for joining to enable reliable and easy joining. In addition, the yarn joining device can be simplified. A suction force generated in the hollow guide shaft can be used to reliably and promptly insert the fiber bundle into the spinning device having spinning nozzles and a hollow guide shaft, thereby improving the success rate of joining. To perform a yam joining operation on yarn breakage or to perform a yarn picking-up operation before the start of spinning, joining is carried out using the spinning nozzles used for normal spinning and the yarn picking-up nozzles that are inoperative during normal spinning. Thus, the structure of the spinning device and the control system for the spinning device can be simplified to improve the stability and reliability of the control system. In addition, simply by carrying out yarn picking-up spinning while simultaneously operating the spinning nozzles and the yarn picking-up nozzles and then switching the yarn picking-up nozzles to an inoperative state while continuously operating the spinning nozzles, yarn picking-up spinning can be shifted to true-twist spinning by means of simple control, thereby reliably preventing inconveniences stemming from disturbance of injected air currents during the shift. After air currents in the hollow guide shaft have been stopped, a true-twisted yarn spun using whirling air currents generated in the spinning nozzle section is joined with a true-twisted yarn drawn out from the winding package, thereby enabling only the true-twisted yarn to be wound around the winding package. By setting the injection pressure of the spinning nozzles to be low before the start of yarn picking-up, fibers can be easily and reliably introduced into the hollow guide shaft, thereby increasing the success rates of yarn picking-up and joining to improve reliability. In addition, by setting the injection pressure of the spinning nozzles to be low before the start of yarn picking-up, fibers can be withdrawn into the hollow guide shaft independently of the injection pressure of the spinning nozzles maintained during normal spinning (the injection pressure maintained after switching to a high level), thereby increasing the applicability of the spinning device. Since the distance between the injection position of each spinning nozzle and the injection position of each yarn picking-up nozzle is substantially the same as or smaller than the average fiber length of fibers constituting a fiber bundle, a lightly true-twisted fiber bundle can be formed, during yarn picking-up spinning, into a strong fasciated yarn. Consequently, joining errors can be prevented which arise from the structure of the hollow guide shaft. Since the truncated cone-shaped tip portion and cylindrical portion of the hollow guide shaft constituting the main body thereof are integrally formed, fibers constituting a fiber bundle and whirled by whirling air currents are precluded from being caught on the bonded location. Accordingly, the resulting yarn breakage is prevented. Since the member constituting the spinning hollow guide shaft is formed of ceramics, no projection is formed on which fibers constituting a fiber bundle may be caught as in the case where the constituent members of the spinning hollow guide shaft are joined together using an adhesive. In addition, the adhesive can prevent the yam picking-up nozzles from being blocked, thereby improving the yield of the hollow guide shaft.

Claims: A spinning device including a hollow guide shaft (15) having a spun-yarn passage (23) through which a spun yarn passes, and spinning nozzles (14) for generating whirling air currents near a tip of the hollow guide shaft, characterized in that a suction force generation means (29) is provided in the hollow guide shaft (15) for sucking and introducing a fiber bundle (6) whirled by the spinning nozzles, into the spun-yarn passage (23). A spinning device as in Claim 1, characterized in that said spun-yarn passage (23) is formed so as to broaden toward Its yarn ejection side and in that said suction force generation means comprises yarn picking-up nozzles (29) for injecting compressed air into the spun-yarn passage (23). A spinning device as in Claim 2, characterized in that during a yarn picking-up operation, said spinning nozzles (14) and said yarn picking-up nozzles (29) both inject compressed air to eject a spun yarn from the ejection side of said spun-yarn passage. A spinning device as in any one of Claims 1 to 3, characterized by including switching means for switching an injection pressure of said spinning nozzles (29) to a high or low level. A spinning device as in Claim 4, characterized in that said switching means switches said injection pressure to a low level before the start of yarn picking-up and maintains it for a predetermined amount of time. A spinning device as in Claim 5, characterized in that after the start of yarn picking-up, said switching means switches said injection pressure from low to high after leading the tip of the fibers constituting a fiber bundle (6) have been introduced into said spun-yarn passage (23). A spinning device as in any one of Claims 2 to 6, characterized in that a distance between an injection position of said spinning nozzles (14) and an injection position of said yarn picking-up nozzles (29) is substantially the same as or smaller than an average fiber length of the fibers constituting the fiber bundle. A spinning device as in Claim 7, characterized in that said hollow guide shaft (15) has a conical tip portion (19) and a cylindrical portion (48) constituting a main body and integrated with each other and in that the main body has an inner cylindrical member (47) disposed therein and having said yarn picking-up nozzles (29) formed therein. A spinning device as in Claim 7 or Claim 8, characterized in that said hollow guide shaft (15) is formed from a ceramic. A spinning method composed of a normal spinning state where whirling air currents are used to spin a true-twisted yarn through spinning nozzles (14) acting on a fibre bundle near an opening of a tip portion of a hollow guide shaft (15) and during a yarn picking-up operation, in addition to said whirling air currents, suction currents are generated at an opening of a tip of the hollow guide shaft (15) to allow a fiber bundle transferred from an upper stream side to a neighborhood of said opening to be sucked into the hollow guide shaft (15), characterized in that during a yarn picking-up operation, compressed air is injected from yarn picking-up nozzles (29) located in the hollow guide shaft (15) in order to form air currents in the hollow guide shaft (15) which are directed to a yarn ejection port for picked-up spinning, A spinning method as in Claim 10, characterized in that the air currents in the hollow guide shaft (15) are subsequently stopped so that said picked-up spinning continued with true twist spinning using whirling air currents from said spinning nozzles (14). A spinning method as in Claim 11, characterized in that after the air currents in the hollow guide shaft (15) have been stopped, a yarn-picking-up spun yarn is removed that has been produced using whirling air currents from said spinning nozzles (14) and whirling air currents from said yarn picking-up nozzles (29), and in that a true-twisted yarn spun using whirling air currents from said spinning nozzles (14) is then joined with a true-twisted yarn drawn out from a winding side. A spinning method as in any one of Claims 10 to 12, characterized in that the injection pressure of said spinning nozzles (14) is set to be low for a predetermined amount of time after the start of yarn picking-up and is then switched to a high level. A spinning method as in Claim 13, characterized in that after the start of yarn picking-up, the injection pressure of the spinning nozzles (14) is switched from low to high after leading tip of fibers constituting a fiber bundle have been introduced into the spun-yarn passage (23) in the hollow guide shaft (15). A spinning method as in any one of Claims 11 to 14, characterized in that a distance between an injection position of said spinning nozzles (14) and an injection position of said yarn picking-up nozzles (29) is substantially the same as or smaller than an average fiber length of the fibers constituting the fiber bundle.

Inventors: SAWADA HARUTOSHI, SAWADA, HARUTOSHI, Sawada, Harutoshi, c/o Murata Kikai Syataku 307gou
Applicants: MURATA MACHINERY LTD, MURATA KIKAI KABUSHIKI KAISHA
Application year: 2000
Main classification: D01H5
IPC codes: D01H4, D01H1