Patent Publication Number: US-6655122-B2

Title: Core yarn manufacturing machine and core yarn manufacturing method

Description:
FIELD OF THE INVENTION 
     The present invention relates to a core yarn manufacturing machine and a core yarn manufacturing method which manufacture the core yarn like a true twist by a hollow guide shaft member and the whirling flow which acts upon the tip section of the hollow guide shaft member, and especially to a core yarn manufacturing machine and a core yarn manufacturing method capable of carrying out automatic yarn pick-up. 
     BACKGROUND OF THE INVENTION 
     Core yarn manufactured by a hollow guide shaft member and a whirling flow which acts upon the tip section of the hollow guide shaft member, includes multifilament yarn of a synthetic fiber, such as polyester, as a core fiber, and has a fiber bundle of cotton or the like wound around the core fiber. The core fiber cannot be seen from the surface, and the core fiber is concentrated in the center. 
     The core yarn manufactured by using such whirling flow is especially characterized in that the thickness of the core fiber can be made more than 50% and the torque (the level of the yarn shrinking in the axis direction) is small, compared to core yarn manufactured by a ring spinning frame. 
     The core yarn manufactured by the ring spinning frame is formed to be a core yarn like a true twist by being twisted while whirling the yarn around the winding bobbin. However, the core fiber can be seen from the surface and the core fiber exists also in the areas around the center. 
     Therefore, there is the core yarn manufacturing machine for manufacturing core yarn like a true twist, comprising air-typed spinning unit which is fed with core fiber and the drafted fiber bundle. 
     The spinning unit is comprised of a hollow guide shaft member wherein the yarn passage is formed in the axis direction, and a whirling flow generating nozzle which generates whirling flow to the tip section of the hollow guide shaft member. 
     The core yarn manufacturing machine manufactures core yarn by winding the fiber bundle guided into the spinning unit after being drafted, around the core fiber fed to the spinning unit along with the fiber bundle at the tip section of the hollow guide shaft member. 
     However, the core yarn manufacturing machine adopting the hollow guide shaft member and the whirling flow which acts upon the tip section of the hollow guide shaft member, were not considered to carry out automatic yarn pick-up of the core yarn, including the automatic feeding of the core fiber. 
     The core yarn manufacturing machine forms a core yarn like a true twist, by the fiber bundle being sucked into the yarn passage, and the reversing fiber separated from the fiber bundle, being wound around the core fiber. Therefore, when attempting the automatic yarn pick-up under the same condition as the normal spinning operation, the force to suck in the fiber bundle into the yarn passage of the hollow guide shaft member, is not produced only by the whirling flow of the whirling flow generating nozzle. Thus, the fiber bundle cannot be exhausted from the yarn outlet of the spinning unit as a yarn. 
     The object of the present invention is to provide a core yarn manufacturing machine and a core yarn manufacturing method capable of carrying out automatic yarn pick-up of the core yarn like a true twist. 
     SUMMARY OF THE INVENTION 
     The present invention was made in consideration to the object mentioned above. The present invention is a core yarn manufacturing machine comprising a spinning unit constituting a hollow guide shaft member wherein the yarn passage is formed in the axis direction, and a whirling flow generating nozzle for applying whirling flow to the tip section of the hollow guide shaft member; wherein a core yarn is manufactured by winding the fiber bundle drafted and guided into the spinning unit, around the core fiber fed to the spinning unit, along with the fiber bundle in the tip section of the hollow guide shaft member; wherein the core yarn manufacturing machine comprises a suction force producing means for producing the suction force toward the interior of the yarn passage from the entrance of the hollow guide shaft member, a core fiber feeding apparatus for feeding the core fiber to the spinning unit, and a control device for controlling the operation and non-operation of the whirling flow generating nozzle, the operation and non-operation of a suction force producing means, and the operation and non-operation of the core fiber feeding apparatus. 
     According to the composition described above, a strong suction force is generated toward the interior of the yarn passage from the yarn entrance of the yarn passage, allowing the core fiber and the fiber bundle to be taken in to the yarn entrance. As a result, automatic yarn pick-up of the core yarn from the yarn outlet can be carried out by passing through the yarn passage. 
     The present invention is the core yarn manufacturing machine wherein the suction force producing means is a compressed air injecting nozzle which injects compressed air into the yarn passage of the hollow guide shaft member. According to this composition, a strong suction force can be produced to the entrance of the hollow guide shaft member, with simple composition. 
     The present invention is a core yarn manufacturing machine wherein the suction force producing means is a compressed air injecting nozzle which injects compressed air into the yarn passage of the hollow guide shaft member. According to this composition, a strong suction force can be produced to the entrance of the hollow guide shaft member. 
     The present invention is the core yarn manufacturing machine wherein the injection pressure of the whirling flow generating nozzle can be switched between high and low according to the signal from the control device. As a result, the success rate of the yarn pick-up is improved by minimizing the whirling force of the core fiber and the fiber bundle which are moved by the whirling flow of the whirling flow generating nozzle, in proximity to the entrance of the hollow guide shaft member. 
     According to the composition described above, the core fiber and the fiber bundle can be sucked in by generating strong suction force toward the interior of the yarn passage from the yarn entrance of the yarn passage. As a result, automatic yarn pick-up of the core yarn from the yarn outlet can be carried out by passing through the yarn passage. 
     The present invention is the core yarn manufacturing method wherein the whirling flow generating nozzle carries out low pressure injection first when carrying out yarn pick-up of the core yarn, and can switch to high pressure injection after the core yarn passes through the yarn passage of the hollow guide shaft member and is exhausted from the yarn outlet of the spinning unit. 
     According to the composition described above, the whirling force which moves the core fiber and the fiber bundle in proximity to the entrance of the hollow guide shaft member, is minimized and the suction force of the suction force producing means acts more efficiently. Therefore, the success rate of the yarn feeding of the core fiber and the fiber bundle to the yarn passage improves, and the success rate of the yarn pick-up from the yarn passage also improves. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram showing the preferred embodiment of the present invention. 
     FIG. 2 is a sectional view of the spinning unit according to the present invention. 
     FIG. 3 is a III—III line sectional view of the spinning unit shown in FIG.  2 . 
     FIG. 4 is a diagram showing one of the examples of the control timing of the yarn pick-up according to the present invention. 
     FIG. 5 is an expanded sectional view of the spinning unit shown in FIG.  2 . 
     FIG. 6 is a schematic diagram showing the entire composition of the present invention. 
     FIG. 7 is a block diagram showing the relationship of the connection between the control device and each unit according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiment of the present invention will now be described in reference to the accompanying drawings. In the following description, the core fiber is a yarn which is to be the core, and includes the spun yarn formed by the staples (short fibers) being twisted, not only the monofilament or the multifilament yarn comprised of synthetic fiber; the core yarn includes the yarn which is to be the core as mentioned above, in the center, and is formed by winding the staples as a sheath around the yarn; and the fiber bundle is formed by collecting the staples. 
     First, the entire composition will be described by referring to FIG.  6 . 
     FIG. 6 is a schematic diagram showing the entire composition of the core yarn manufacturing machine of the present invention. 
     As shown in FIG. 6, a core yarn manufacturing machine  1  is comprised of a drafting apparatus  2  which drafts a sliver S into a designated thickness, a core fiber feeding apparatus  3  for feeding a core fiber C, a spinning unit  4  which is to be fed with the core fiber C and a drafted fiber bundle F, and a winding unit  5  which winds the core yarn Y like a true twist exhausted from the spinning unit  4 , to form a package P. These are made as one manufacturing unit. The core yarn manufacturing machine  1  is constituted by providing a plurality of manufacturing units in proximity in a row arrangement. 
     For example, the core yarn Y like a true twist includes the multifilament yarn which is a synthetic fiber of polyester or the like, as a core fiber, and has a fiber bundle of cotton or the like as the covering fiber wound around the core fiber. 
     The winding unit  5  is comprised of, for example, a delivery roller  6  and a nip roller  7  for delivering the core yarn Y which is exhausted from the spinning unit  4  of the upstream side to the downstream side, a slack tube (yarn accumulating member)  8  for securing the yarn by sucking the core yarn Y when joining the yarn, and a yarn clearer  9  for cutting the core yarn Y when the core yarn Y of the desired thickness does not pass through after the thickness of the core yarn Y is detected. 
     One or a plurality of yarn joining apparatus  10  is employed capable of running along the longitudinal direction of the core yarn manufacturing machine  1 . In other words, the yarn joining apparatus  10  runs along the arrangement of the manufacturing units. The yarn joining apparatus  10  comprises an upper suction pipe  11  capable of moving in the vertical direction, a yarn joining unit  12 , and a lower suction pipe  41  capable of moving in the vertical direction. 
     When yarn breakage occurs in some manufacturing units, the yarn joining apparatus  10  stops after running to the backside of the designated unit. Then, the tip of the upper suction pipe  11  which is the yarn sucking and catching apparatus of the spinning side, moves to the yarn outlet of the spinning unit  4  and sucks in the core yarn Y which is to be exhausted from the spinning unit  4 . 
     Next, the upper suction pipe  11  is moved to guide in the core yarn Y into the yarn joining unit  12 , and then the core yarn Y drawn from the package P by a lower suction pipe  41  which is the yarn sucking and catching apparatus of the winding side, and the core yarn Y drawn by the upper suction pipe  11  is joined in the yarn joining unit  12 . 
     FIG. 1 is a schematic diagram showing the main part of the core yarn manufacturing machine which is the preferred embodiment of the present invention. 
     As shown in FIG. 1, the main part of the core yarn manufacturing machine  1  comprises a drafting apparatus  2 , a core fiber feeding apparatus  3 , and a spinning unit  4 . 
     The core yarn manufacturing machine  1  of the present invention comprises the spinning unit  4  which includes a hollow guide shaft member  14  wherein the yarn passage is formed in the axis direction, and a whirling flow generating nozzle  13  which produces whirling flow to the tip section of the hollow guide shaft member  14 . A fiber bundle F which has been drafted and guided into the spinning unit  4  is wound around the core fiber C which has been fed to the spinning unit  4  along with the fiber bundle F in the tip section of the hollow guide shaft member  14 , for the manufacturing of the core yarn. The core yarn manufacturing machine  1  comprises a suction force producing means  15  for producing suction force toward the interior of the yarn passage from the entrance of the hollow guide shaft member  14 , a core fiber feeding apparatus  3  for feeding the core fiber C to the spinning unit  4 , and a control device  70  for controlling the operation and non-operation of the whirling flow generating nozzle  13 , the suction force producing means  15  and the core fiber feeding apparatus  3 . 
     The core yarn manufacturing machine  1  of the present invention is capable of manufacturing a core yarn like a true twist, especially strong against squeezing, by the core fiber C composed of multifilament or the like, being loosened a little by the whirling flow of the whirling flow generating nozzle  13 , and the fiber of the fiber bundle F being wound around the core fiber C while being caught into the gap of the core fiber C (between the filaments composing the core fiber). 
     The drafting apparatus  2  drafts a sliver S fed via a trumpet  16 , to form the fiber bundle F of the designated thickness, via a plurality of draft rollers. A pair of back rollers  17 , a pair of third rollers  18 , a pair of second rollers  19  with apron belt hung, and a pair of front rollers  20  are the draft rollers, arranged in this order, starting from the upstream side. 
     The core fiber feeding apparatus  3  is employed diagonally above the drafting apparatus  2 . For example, the core fiber feeding apparatus  3  comprises a tensor  21  which applies a prescribed tension to the core fiber C which has been unwound from a bobbin B of the upstream side, an air sucker  22  which sucks in and delivers to the downstream side the core fiber C via the tensor  21 , and a clamp cutter  23  which cuts and holds the core fiber C. 
     According to the embodiment of the present invention, a feeler  24  for detecting the presence or the absence of the core fiber C is employed between the tensor  21  and the air sucker  22 . The feeler  24  transmits a signal to the control device  70  in the case the core fiber C is cut by some reason, and the control device  70  which has received the signal, stops the operation of the core yarn manufacturing machine  1 . 
     The core fiber feeding apparatus  3  feeds the core fiber C to the spinning unit  4 . In the core fiber feeding apparatus  3 , the core fiber C passes from the upstream side, from the tensor  21 , the feeler  24 , the air sucker  22 , a yarn guiding tube  25 , the clamp cutter  23 , a tip yarn guiding tube  26  and a funnel-shaped guide  27 , in this order. 
     In the embodiment of the present invention, for example, the funnel-shaped guide  27  is employed in the upstream side of the front roller  20 . Thus, the core fiber C is arranged to be fed to the spinning unit  4  from the upstream side of the front roller  20 , along with the fiber bundle F. 
     Next, the spinning unit  4  will be described. 
     FIG. 2 is a sectional view showing the spinning unit  4  according to the present invention. 
     As shown in FIG. 2, the spinning unit  4  is disposed with the whirling flow generating nozzle (spinning nozzle)  13 , and the hollow guide shaft member  14  of which the tip section is to be inserted into the whirling flow generating nozzle  13 . The tip (the inlet of the fiber bundle) of the whirling flow generating nozzle  13  is employed in proximity to the downstream side outlet of the front roller  20 . 
     The whirling flow generating nozzle  13  is comprised of a nozzle main body  28  of which the whole body is formed in a nearly cylindrical shape. An inlet cap  29  is attached to the tip section of the whirling flow generating nozzle  13 , projecting little. A passage way  30  which receives the core fiber C and the fiber bundle F, fed from the front roller  20 , is formed in the axis direction of the inlet cap  29 . A bush  31  which decreases the spreading of the core fiber C and the fiber bundle F, is employed in proximity to the outlet of the passage way  30 . 
     A ringed flow channel  32  for blowing air in the periphery direction, and a plurality of nozzle openings  33  for guiding air to the radial direction from the ringed flow channel  32  and for injecting air to the downstream side of the bush  31 , are formed in the upstream side of the nozzle main body  28 . Each nozzle opening  33  is formed inside the nozzle main body  28 , inclining from the upstream side to the downstream side. On the other hand, a space area  34  for blowing out the air injected from the nozzle opening  33  to the outside is formed in the downstream side of the nozzle main body  28 . 
     The air supplying apparatus is connected to the ringed flow channel  32 , and the whirling flow generating nozzle  13  is made to generate the whirling flow in proximity to the tip section of the hollow guide shaft member  14  so that the injection pressure can be switched between high and low. 
     The hollow guide shaft member  14  is formed in almost a pole form so that the tip section is to be a little thin, and the yarn passage  35  of which the cross section is in almost a circular form, is formed to pass through in the axis direction. A yarn passage  35  is comprised of an upstream side yarn passage  35   u , a midstream side yarn passage  35   m , and a downstream side yarn passage  35   d.    
     The cross sectional area is made to be enlarged gradually from the upstream side to the downstream side. 
     The tip section of the hollow guide shaft member  14  forms a little gap (g) between the nozzle main body  28 . In addition, the hollow guide shaft member  14  is inserted into the whirling flow generating nozzle  13  so that a yarn entrance  36  of the yarn passage  35  is to be near the downstream side of the outlet of the nozzle opening  33 . 
     The present invention was made to employ the suction force producing means  15  for producing the suction force toward the inside from the entrance of the tip section of the yarn passage  35  of the hollow guide shaft member  14 , for carrying out yarn pick-up automatically of the core fiber C and the fiber bundle F from the outlet of the hollow guide shaft member  14 . For example, a compressed air injecting nozzle  38  (nozzle for yarn pick-up) for injecting compressed air into the yarn passage  35  can be adopted for the suction force producing means  15 . By generating suction flow in the yarn passage  35  inside the hollow guide shaft member  14  by the compressed air injecting nozzle  38 , the core fiber C and the fiber bundle F can be sucked into the yarn passage  35 , and the yarn pick-up from a yarn outlet  40  of the yarn passage  35  can be carried out by passing the core yarn which has the strength capable of being drawn out by the upper suction pipe  11 , through the yarn passage  35 . 
     A nozzle which produces inside the yarn passage  35 , the whirling flow of which the direction is the opposite to the direction of the whirling flow generated by the spinning nozzle  13 , can be adopted for the compressed air injecting nozzle  38 . In this case, yarn pick-up can be carried out according to the fasciated spun yarn theory by the whirling flows in the clockwise direction and the counterclockwise direction. However, the nozzle is not necessarily required to produce the whirling flow. 
     In the present invention, the operation of the whirling flow generating nozzle  13 , the generation of the suction force toward the interior of the yarn passage  35  from the yarn entrance  36  of the hollow guide shaft member  14 , the feeding of the core fiber C to the spinning unit  4 , and the feeding of the fiber bundle F to the spinning unit  4 , are begun at an agreeable timing, and the yarn pick-up of the core yarn Y from the yarn outlet  40  of the spinning unit  4  is carried out by the control of the control device  70 . 
     The whirling flow generating nozzle  13  can switch the injection pressure of the air injected from the nozzle opening  33 , freely between high and low by the control of the control device  70 . When carrying out yarn pick-up of the core yarn Y, the low pressure injection is continued until the prescribed period of time elapses after the beginning of the operation, and then it is switched to the high pressure injection. More specifically stating, when carrying out yarn pick-up of the core yarn Y, the whirling flow generating nozzle  13  which carries out the low pressure injection first, is made to switch to the high pressure injection after the feeding of the core fiber C and the fiber bundle F are begun, and after the core yarn Y which has passed the yarn passage  35  of the hollow guide shaft member  14  is discharged from the yarn outlet  40 . 
     For example, a compressed air supplying apparatus  39  is connected to the back end of the hollow guide shaft member  14 . A cylindrical shaped compressed air flow channel  37  for blowing the compressed air supplied from the compressed air supplying apparatus  39  is formed inside the hollow guide shaft member  14 , along the downstream side yarn passage  35   d  and the midstream side yarn passage  35   m . The inside diameter of the compressed air flow channel  37  is larger than the yarn passage  35 , and the outside diameter thereof is smaller than the hollow guide shaft member  14 . 
     The yarn passage  35  is formed so that the cross sectional area is to be enlarged gradually from the upstream side to the downstream side. As a result, the compressed air injected to the yarn passage  35  from the compressed air injecting nozzle  38 , flows into the downstream side yarn passage  35   d  from the midstream side yarn passage  35   m  while generating whirling flow in the yarn passage  35 , and flows out from the yarn outlet  40 . On the other hand, the air injected from the nozzle opening  33  generates the whirling flow near the yarn entrance  36 , flows through the gap (g) and flows outside from the space area  34  formed between the nozzle main body  28  and the supporting unit of the hollow guide shaft member  14 . 
     In the present invention, strong suction force is generated toward the interior of the yarn passage  35  from the yarn entrance  36  of the yarn passage  35 . As a result, the core fiber C and the fiber bundle F can be sucked into the yarn passage  35  from the yarn entrance  36 , in synergy with the normal spinning movement by the whirling flow generating nozzle  13  and the hollow guide shaft member  14 , by passing the core yarn like a true twist through the yarn passage  35 , the automatic yarn pick-up from the yarn outlet  40  can be carried out in a form in which the core yarn like a true twist can be drawn out by an upper suction pipe  11 . 
     FIG. 3 is a III—III line sectional diagram of the spinning unit  4  shown in FIG.  2 . 
     As shown in FIG. 1, under the normal operation, the core fiber C is fed to the spinning unit  4  from the upstream side of the front roller  20  via the tensor  21 , and is drew drawn out by the delivery roller  6  via the yarn passage  35 . 
     Next, the relationship of the connection between the control device  70  and each unit will be described in reference to FIG.  7 . 
     FIG. 7 is a block diagram showing the relationship of the connection between the control device  70  and each unit according to the present invention. 
     As shown in FIG. 7, a high pressure supplying valve  71  and a low pressure supplying valve  72 , which are capable of opening and closing independently from one another, are connected between the control device  70  and the whirling flow generating nozzle  13 . The high pressure supplying valve  71  and the low pressure supplying valve  72  are connected to the compressed air source (not shown in the drawings) via a compressed air adjuster. The high pressure air HA or the low pressure air LA is supplied to the whirling flow generating nozzle  13  according to the high pressure supplying signal (a) or the low pressure supplying signal (b) from the control device  70 . Thus, by switching the supplying signal from the control device  70 , the injection pressure of the whirling flow generating nozzle  13  is made capable of freely switching between high pressure and low pressure. 
     A switching valve  73  is connected between the control device  70  and the compressed air injecting nozzle (nozzle for yarn pick-up)  38 . When generating suction force in the yarn passage  35  of the hollow guide shaft member  14 , the air A is supplied to the yarn pick-up nozzle  38  according to the suction force producing signal (c) from the control device  70 . 
     The switching valve  74  is connected between the control device  70  and the air sucker  22  in the same manner. When feeding the core fiber C to the drafting apparatus  2  (the upstream side of the front roller  20 ), the feeding force is applied to the core fiber C by supplying the air A to the air sucker  22  according to the core fiber feeding signal (d) from the control device  70 . 
     Moreover, the control device  70  is connected to a clutch  75  for switching the driving of the back roller  17  and the third roller  18 . When feeding the fiber bundle F which has been stopped in the drafting apparatus  2  to the spinning unit  4 , the clutch  75  is connected and the drafting roller (the back roller  17  and the third roller  18 ) which has been stopped, is re-driven, according to the fiber bundle feeding signal (e) from the control device  70 . 
     The control device  70  is also connected to the clamp cutter  23 , and when stopping the feeding of the core fiber C, the clamp cutter  23  is operated, and the core fiber C in the feeding process is cut and gripped according to the yarn cutting gripping signal (f) from the control device  70 . When feeding the core fiber C again, as mentioned above, the gripping of the clamp cutter  23  is released by canceling the yarn cutting gripping signal (f) from the control device  70  while operating the air sucker  22 . 
     Likewise, each of the signals (a) through (f) from the control device  70 , controls each operation of the nozzle for yarn pick-up  38  as a suction force producing means  15 , the air sucker  22  and the clamp cutter  23  (the core fiber feeding apparatus  3 ), the whirling flow generating nozzle  13 , the back roller  17  and the third roller  18  (the drafting apparatus  2 ), or the like. 
     Next, the effect of the present invention will be described. 
     FIG. 5 is an expanded sectional view showing the spinning unit  4  illustrated in FIG.  2 . 
     As shown in FIG. 1, under the normal operation, the core fiber C is fed to the spinning unit  4  from the upstream side of the front roller  20  via the tensor  21 , and is drew out by the delivery roller  6  via the yarn passage  35 . 
     On the other hand, the fiber bundle F which has been drafted in the drafting apparatus  2 , is guided into the passage way  30  of the spinning unit  4  by the whirling flow (in the drawing, rightward direction) of the whirling flow generating nozzle  13  (refer to FIG.  2 ). As shown in FIG. 5, the tip of the fiber of the fiber bundle F is guided from the yarn entrance  36  of the hollow guide shaft member  14  into the yarn passage  35 , by being pulled by the core fiber C. When the gripping by the front roller  20 , located near the entrance of the spinning unit  4 , is released, the end tip of the fiber of the fiber bundle F reverses from the yarn entrance  36  while the tip of the fiber of the fiber bundle F is sucked into the yarn passage  35 , as to winding around the outer surface of the tip section of the hollow guide shaft member  14  by the component force of the axis direction of the whirling flow by the whirling flow generating nozzle  13 . As a result, the core yarn Y like a true twist is formed by winding the end tip of the fiber of the fiber bundle F around the core fiber C, wherein the core fiber C is not appearing on the surface. 
     The core yarn Y like a true twist is exhausted from the yarn passage  35 , and is formed into a package P by being wound at the winding unit  5  via the yarn picking-up unit comprised of a nip roller  7  and the delivery roller  6 . Under such normal spinning operation, the compressed air is not injected from the compressed air injecting nozzle  38  as a suction force producing means  15 . 
     In the case of yarn breakage, the feeding of the sliver S is stopped by the stopping of the back roller  17  and the third roller  18 . At the same time, the clamp cutter  23  in the core fiber feeding apparatus  3  operates to cut the core fiber C, and grips the cut tip of the core fiber C. The yarn joining preparation completes with the arrival of the yarn joining apparatus  10  to each unit, and the spinning is resumed. 
     In the resuming of the spinning, the roller which has been stopped in the drafting apparatus  2 , is re-driven and the fiber bundle F is fed to the spinning unit  4 , with the suction opening of the upper suction pipe  11  of the yarn joining apparatus  10  placed in the proximity to the outlet of the spinning unit  4 . Corresponding to the re-driving of the back roller  17  and the third roller  18 , the feeding of the core fiber C from the upstream side of the front roller  20  into the drafting apparatus  2 , is started. This is the same as the start of the spinning. 
     The core fiber C and the fiber bundle F fed to the spinning unit  4  via passing through the front roller  20  of the drafting apparatus  2 , is formed into a core yarn Y like a true twist with the fiber of the fiber bundle F wound around the core fiber C, in the same manner as in the normal spinning operation. 
     In the present invention, the compressed air is injected from the compressed air injecting nozzle  38  as a suction force producing means  15  at the time being. The operation of the compressed air injection nozzle  38  is carried out at almost the same time as the operation of the whirling flow generating nozzle  13 . 
     The yarn passage  35  is formed so that the cross sectional area is enlarged gradually from the upstream side to the downstream side. Therefore, the compressed air injected into the yarn passage  35  from the compressed air injecting nozzle  38 , flows inside the yarn passage  35  toward the downstream side, and is discharged from the yarn outlet  40 . On the other hand, the air injected from the nozzle opening  33 , generates a whirling flow in proximity to the yarn entrance  36 , and is discharged to the outside from the space area  34  after flowing through the gap (g). 
     In the present invention, at the beginning of the spinning (yarn pick-up), the core fiber C and the fiber bundle F can be sucked into the yarn entrance  36  by generating a strong suction force toward the interior of the yarn passage  35  from the yarn entrance  36  of the yarn passage  35 , and the core yarn Y can be picked up automatically from the yarn outlet  40  by passing through the yarn passage  35 . 
     As described above, when the nozzle which generates whirling flow of the direction opposite to the direction of the whirling flow by the spinning nozzle  13 , is adopted for the compressed air injection nozzle  38 , the core yarn Y like a fascinated spun yarn, is exhausted from the spinning unit  4  while the compressed air injecting nozzle  38  is operating. After the upper suction pipe  11  draws out the core yarn Y, and the feeding force by the delivery roller  6  is prepared, in other words, after the extruding force of the delivery roller  6  is applied to the core yarn Y passing through the interior of the spinning unit  4 , the operation of the compressed air injecting nozzle  38  as a suction force producing means  15  is stopped and is switched to a normal spinning. When it is switched to the normal spinning wherein the influence of the compressed air injecting nozzle  38  is not applied, the core yarn Y like a true twist, not a fascinated spun yarn, is exhausted from the spinning unit  4 . In the yarn joining operation of the yarn joining apparatus  10 , all the core yarn Y like a fascinated spun yarn, sucked in by the upper suction pipe  11  is eliminated. As a result, a package P wherein only the core yarn Y like a true twist is wound, is formed by joining the yarn in the yarn joining unit  12 , the core yarn Y like a true twist which is exhausted after the operation of the compressed air injecting nozzle  38  is stopped, and the core yarn Y like a true twist extruded from the winding package P side. 
     FIG. 4 is a diagram showing one of the examples of the control timing of the yarn pick-up according to the present invention. 
     As shown in FIG. 4, at the spinning start time T o , first, the whirling flow generating nozzle  13 , the suction force producing means  15 , the back roller  17  of the drafting apparatus  2  are put on (ON) at almost the same time. As a result, the fiber bundle F is guided to the yarn passage  35  of the hollow guide shaft member  14  by the suction force, while fed to the spinning unit  4  from the drafting apparatus  2 . 
     At the time being, the injection pressure P L  of the whirling flow generating nozzle  13  is made smaller than the spinning pressure P H  of the normal spinning. The injection pressure P of the whirling flow generating nozzle  13  is switched to the spinning pressure P H  of the normal spinning at time T 1 , after the elapse of the prescribed period of time ΔT from the beginning of the feeding of the fiber bundle F. 
     The core fiber feeding apparatus  3  is began driving at the time Tc which is the time between T o  and T 1  while the whirling flow generating nozzle  13  is being operated under the injection pressure P L , and feeds the core fiber C from the upstream side of the front roller  20  so that the core fiber C overlaps with the fiber bundle F. 
     The back roller  17  can be put on (ON) between the time T o  and T 1 , and the core fiber C can be fed to the spinning unit  4  in advance of the fiber bundle F. 
     The suction force producing means  15  is put off (OFF) at the time T 3 , the time after the time T 2 , the time wherein a prescribed period of time elapsed after the time T 1  (when the core yarn Y to be exhausted from the spinning unit  4  is charged with the feeding force by the delivery roller  6 ). 
     Likewise, by making the pressure of the whirling flow generating nozzle  13  to be lower than the pressure at the normal spinning operation, at the start of the feeding of the core fiber C to the spinning unit  4 , the whirling force for swinging the core fiber C in proximity to the entrance of the hollow guide shaft member  14 , is minimized, and the suction force by the suction force producing means  15  is applied effectively. As a result, the core fiber C can be reliably fed to the yarn passage  35  of the hollow guide shaft member  14 , the success rate of the feeding of the core fiber C to the yarn passage  35  is improved, and the success rate of the yarn pick-up from the yarn passage  35  can be also be improved. The drafted fiber bundle F is processed in the same manner. 
     Moreover, when feeding the core fiber C before the fiber bundle F, even if the whirling flow generating nozzle  13  is stopped (injection pressure P=0), there are cases in which the core fiber C can be delivered into the yarn passage  35  only by the suction force producing means  15 . 
     The suction force producing means  15  according to the present invention can generate a strong suction force to the entrance of the hollow guide shaft member  14  just by a simple composition as described above. 
     According to the embodiment of the prsent invention, the core fiber C is located in the center of the fiber bundle F, and the twisting applied by the whirling flow can be prevented from spreading out to the front roller  20 . As a result, the core yarn Y like a true twist wherein a plurality of fiber composing the fiber bundle F is to be the winding fiber, can be manufactured. Therefore, the embodiment was described with the example wherein the needle opposing to the entrance of the hollow guide shaft member  14  is not employed to the tip section of the whirling flow generating nozzle  13 . In other words, since the core fiber C acts in the same manner as the needle (the effect for preventing the spreading into the upstream side, of the twisting applied to the fiber by the whirling flow, while guiding the fiber from the passage way  30  of the nozzle main body  28  into the yarn passage  35  of the hollow guide shaft member  14 ). Therefore, the core yarn Y like a true twist can be manufactured without the needle. However, the present invention is capable for adapting to both the presence and absence of the needle. 
     As it is evident from the description above, according to the present invention, the following excellent effects can be expected. 
     (1) The automatic yarn pick-up of thr core yarn like a true twist can be carried out by operating each movement at an appropriate timing according to the control from the control device. 
     (2) With the simple composition, strong suction force can be generated to the entrance of the hollow guide shaft member, if the suction force producing means is comprised of the compressed air injecting nozzle for injecting compressed air to the yarn passage of the hollow guide shaft member. 
     (3) By making the injection pressure of the whirling flow generating nozzle to be low pressure, right after the yarn pick-up spinning is started, the success rate of the yarn pick-up can be improved by minimizing the whirling force of the core fiber and the fiber bundle which are moved by the whirling flow of the whirling flow generating nozzle in proximity to the entrance of the hollow guide shaft member. 
     (4) The core fiber is loosened a little by the whirling flow of the whirling flow generating nozzle, and the fiber of the fiber bundle gets into the gap of the core fiber and is wound around the core fiber. As a result, a core yarn like true twist which is especially strong against squeezing, can be manufactured.