Abstract:
The object of the present invention is to provide a piecing method and a piecing device of a spinning machine capable of blowing off the sliver effectively during piecing and controlling the joint thickness. Accordingly, a means is provided for sucking by guiding to the suction pipe  34  disposed between the twisting device  17  and the draft device  10  by blowing pressurized air to the sliver S so as to carry out piecing of the leading yarn Y fed back to the twisting device  17  and the sliver S from the draft device  10.  The pressurized air is blown from the periphery of the spinning nozzle  22  of the twisting device  17  in opposition toward the sliver from the draft device.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a piecing method and a piecing device for piecing a severed spun yarn on the winding package side and the sliver of a spinning machine for drafting a sliver and then winding to a winding package after spinning by a twisting device of such as a pneumatic type. 
     BACKGROUND OF THE INVENTION 
     First, the structure of the relevant part of the spinning machine will be described with reference to FIG.  8 . 
     Referring to FIG. 8,  10  is a draft device, and a back roller  11 , a third roller  12 , a middle roller  13  laid across an apron belt  14 , and a front roller  15  are formed in this order from the upstream side. A sliver S from a first sliver guide  16  on the upstream side of the back roller  11  is drafted in a designated drafting ration between each roller and is supplied to a twisting device  17 . A second sliver guide  16   a  is provided between the third roller  12  and the middle roller  13 . 
     The twisting device  17  comprises a guide hole (fiber introducing hole)  20  for guiding a fiber bundle F drafted in the draft device  10  to a guide member  18  located opposing to the tip of a hollow guide shaft member  25  to be mentioned later on, a spinning nozzle  22  with a nozzle hole  21  for generating whirling air flow in the tip (spinning point) of the hollow guide shaft member  25  to be mentioned later on, a nozzle block  24  for holding the spinning nozzle  22  and forming an air room  23 , the hollow guide shaft member  25  wherein the tip is provided facing the spinning nozzle  22 , and a holding member  26  for closing the air room  23  by joining to the nozzle block  24 , and which holds on the hollow guide shaft member  25 , and separates the hollow guide shaft member  25  with respect to the spinning nozzle  22  during a yarn breakage. 
     The fiber bundle F drafted by the draft device  10  is guided along the guide member  18  from the guide hole  20 , and then enters inside the hollow guide shaft member  25 . The end of the fiber, the tip of which is released from the nip at the front roller  15  at the time being, is whirled by the whirling flow injected from the nozzle hole  21 , is wound by reversing on the tip section of the hollow guide shaft member  25 , and is sucked in while winding onto the fiber entering the hollow guide shaft member  25 , to be a spun yarn Y like a true twist of which the most part of the fiber is to be a wrapping fiber. Moreover, the spun yarn Y is wound to the winding package (not shown in the drawings) by passing between a delivery roller  28  and a nip roller  29  contacting with the delivery roller  28  which compose the yarn feeding device on the downstream side of the twisting device  17 . 
     Between the draft device  10  and the twisting device  17 , an air shower tube  32  for blowing pressurized air to the sliver S during piecing, and a suction pipe  34  for holding the spun yarn at the winding package side and sucking the fiber blown off by the pressurized air from the air shower tube  32 , are provided. 
     Next, the conventional piecing operation after the yarn breakage will be described in reference to FIG.  9  through FIG.  10 . 
     When yarn breakage occurs, the back roller  11  and the third roller  12  which are a part of the draft rollers composing the draft device  10  are stopped, and the middle roller  13  and the front roller  15 , which are on the downstream side are maintained in a driving state. At that time, the yarn feeding by the delivery roller  28  and the nip roller  29  is also maintained at a driving state for a while. As a result, as shown in FIG. 9, the sliver S is broken by the driving middle roller  13 , and the sliver S stops with the tip section Sa positioned between the third roller  12  and the middle roller  13 . At this time, the tip section Sa of the sliver S is held by the second sliver guide  16   a.    
     Following the stopping of a part of the draft rollers of the draft device  10 , the driving (compressed air injection from the nozzle hole  21 ) of the twisting device  17  is stopped while the hollow guide shaft member  25  is transferred to a state in which it is separated from the nozzle block  24 . Under such condition, preceding the piecing operation, the nip roller  29  is separated from the delivery roller  28  and the yarn feeding is stopped. Subsequently, the spun yarn Y at the winding package side is held by a yarn feeding roller  30  which comprises the yarn delivering member, and is fed back to the yarn discharging side of the twisting device  17  by being passed through the nip roller  29  and the delivery roller  28 . Then, by the rotation of the yarn feeding roller  30 , the spun yarn Y is fed toward the draft device  10 , and in cooperation with the air flow (not shown in the drawings) toward the fiber bundle inlet of the guide hole  20 , as a leading yarn Y (parent yarn), is passed through, in the opposite direction of the spinning direction inside the hollow guide shaft member  25 . 
     Furthermore, by rotating the yarn feeding roller  30 , the yarn tip of the leading yarn Y, projects from the guide hole  20  of the spinning nozzle  22  in cooperation with the air flow toward the fiber bundle inlet mentioned above, and the yarn tip of the leading yarn Y is held by being sucked by the suction pipe  34  provided between the spinning nozzle  22  and the front roller  15 . Then, as shown in FIG. 10, the holding member  26  is joined with the nozzle block  24  again. 
     Then, the draft rollers (back roller  11  and third roller  12 ), which were stopped, are redriven, the sliver S is passed through the middle roller  13  and the front roller  15  and is delivered to the downstream side. At that time, the tip section of the sliver S is blown off by the pressurized air from the air shower tube  32  and is sucked and eliminated by the suction pipe  34  so that the guide hole  20  of the spinning nozzle  22  is not blocked. 
     Under the state in which the leading yarn (spun yarn) Y is held as in the manner stated above, the yarn feeding roller  30  is released from the yarn path, and starts running in the winding direction of the leading yarn Y by the nip roller  29  and the delivery roller  28 . After redriving the injection of the whirling air flow from the nozzle hole  21 , by stopping the injection of the pressurized air from the air shower tube  32 , the fiber composing the sliver S is wound around the outer periphery of the leading yarn Y, the piecing is carried out and the spinning is recommenced. 
     However, there were problems in the piecing method and the piecing device of aforementioned conventional spinning machine as to be described in the following. 
     That is, since the distance between the air shower tube  32  and the sliver S is long, and the pressurized air hits the front roller  15  of the draft device  10 , it was inefficient and there were cases in which the joint is bunched up together without the fiber, of which the fiber length is long and unlikely to be blown off to be eliminated completely. 
     Moreover, after stopping the injection of the pressurized air from the air shower tube  32 , since the fiber amount of the sliver S, which is to enter the guide hole  20  of the spinning nozzle  22  for piecing, is the normal fiber amount; in other words, a fiber amount that is the same as the leading yarn Y, the joint thickness will be theoretically 2 times that of the leading yarn Y in cross section, and in diameter, 1.4 times. 
     These were the yarn defects, and there was a problem in that the quality of the spun yarn as a product decreases. 
     The object of the present invention is to solve the problems mentioned above, and to provide a piecing method and a piecing device of a spinning machine capable of blowing off the sliver effectively during piecing and controlling the joint thickness. 
     SUMMARY OF THE INVENTION 
     The present invention to achieve the object mentioned above, relates to a piecing method for blowing pressurized air to a sliver and sucking and guiding by a suction pipe provided between a twisting device and a draft device to carry out piecing to a leading yarn fed back to the twisting device and the sliver from the draft device, wherein the pressurized air is made to be blown in an opposing direction toward the sliver from the periphery of a spinning nozzle of the twisting device. 
     If constructed in accordance with the invention, the pressurized air can be blown from a position close to the sliver, and since there are no obstacles for the blowing, the sliver can be blown off efficiently. 
     Moreover, the pressurized air can be set to be weaker than the suction force of the spinning nozzle of the twisting device during piecing, and the joint thickness achieved by the piecing can be controlled to be a desired thickness by selecting the blowing time of the pressurized air. 
     Accordingly, the joint thickness can be controlled by blowing off and eliminating a part of the fiber of the sliver to enter the guide hole of the spinning nozzle. 
     Moreover, the present invention relates to a piecing method for blowing pressurized air to a sliver and sucking and guiding by a suction pipe provided between a twisting device and a draft device to carry out piecing of a leading yarn fed back to the twisting device and the sliver from the draft device, wherein an air nozzle for blowing pressurized air in a direction opposing the sliver delivered from the draft device is provided around a spinning nozzle of the twisting device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     ü@ü@ FIG. 1 is detailed partial sectional view showing a spinning nozzle and an air nozzle of a piecing device according to an embodiment of the present invention. 
     FIG. 2 is a front view of the spinning nozzle and the air nozzle of the piecing device according to an embodiment of the present invention. 
     FIG. 3 is a diagram showing the entire spinning machine according to an embodiment of the present invention. 
     FIG. 4 is a time chart showing the driving timing of each device during piecing. 
     FIG. 5 is a diagram showing the relationship between the stop timing of the air nozzle and the joint thickness. 
     FIG. 6 is a diagram showing the relationship between the length of the pipe from a valve to the air nozzle and the port number of the valve, and the decrease in the pressure of the air after the stopping of the air nozzle. 
     FIG. 7 is a diagram showing another embodiment of the air nozzle. 
     FIG. 8 is a diagram showing the whole structure of the conventional spinning machine. 
     FIG. 9 is a diagram showing the conventional piecing device and the method of the same. 
     FIG. 10 is a diagram showing the conventional piecing device in another condition of the method of the same. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment according to the present invention will now be described in reference to the accompanying drawings. 
     The entire structure of the spinning machine according to an embodiment of the present invention is the same as the spinning machine illustrated in FIG.  8 . Therefore, for the same members, the same reference numbers will be used and the description will be abbreviated. 
     The main point of the present invention is that an air nozzle  40  for injecting compressed air to the sliver S during piecing and for sucking the blown sliver into the suction pipe  34  is provided around the tip section of the spinning nozzle  22  of the twisting device  17 . 
     As shown in FIG.  1  and FIG. 2, the air nozzle  40  according to the embodiment of the present invention is formed in a circular form about the entire periphery of the periclinal of the spinning nozzle  22 . In addition, an air passageway  41  connected to a compressed air supplying means which is not shown in the drawings, and an air manifold unit  42  for storing the pressurized air supplied to the air passage way  41  temporarily are connected to the air nozzle  40 . The air manifold unit  42  is formed in a circular form along the entire periphery of the periclinal of the spinning nozzle  22 , in the same manner as the air nozzle  40 . 
     The pressurized air supplied into the air passage way  41  from the compressed air supplying means is stored in the air stocking unit  42  temporarily, and then injected from the air nozzle  40  toward the sliver S delivered from the front roller  15  of a draft device  10  in a direction opposed to the direction of movement of the sliver. 
     As is evident from the drawings, there are no obstacles between the air nozzle  40  and the sliver S which is delivered from the draft device  10 , and the pressurized air from the air nozzle  40  can be blown reliably to the sliver S. Moreover, compared to the conventional air shower  32  illustrated in FIG. 8, the air nozzle  40  is capable of blowing pressurized air from a position closer to the sliver S. 
     The piecing operation after the yarn breakage in the spinning machine according to the embodiment of present invention provided with such air nozzle  40  will now be described. 
     The basic piecing operation is the same as the conventional piecing operation. When a yarn breakage occurs, first, the back roller  11  and the third roller  12  which are part of the draft rollers composing the draft device  10  are stopped while the middle roller  13  and the front roller  15  which are located the downstream side are kept in a driving state. At that time, the yarn delivery by the delivery roller  28  and the nip roller  29  is also maintained in a driving state for awhile. As a result, the sliver S is pulled from the middle roller  13  which is driving, and stops under the condition in which the tip section of the sliver S is located between the third roller  12  and the middle roller  13 . At that time, the tip section of the sliver S is held by the second sliver guide  16   a.    
     The driving (compressed air injection from the nozzle hole  21 ) of the twisting device  17  is stopped following the stopping of the aforementioned draft rollers of the draft device  10 . Then, the hollow guide shaft member  25  is separated from the nozzle block  24 . Under such state, preceding the piecing operation, the nip roller  29  is separated from the delivery roller  28  and the yarn delivery is stopped. Then, the spun yarn Y on the winding package P side is held by the yarn feeding roller  30  which comprises a yarn delivering member, and is back fed to the yarn discharging side of the twisting device  17  while being passed through the nip roller  29  and the delivery roller  28 . The spun yarn Y is then fed toward the draft device  10  by the rotation of the yarn feeding roller  30 , and in cooperation with an air flow (not shown in the drawings) toward the fiber bundle inlet of the guide hole  20  as a leading yarn, is inserted in the opposite direction of the spinning direction inside the hollow guide shaft member  25 . 
     Furthermore, by rotating the yarn feeding roller  30 , the yarn end of the leading yarn projects from the guide hole  20  of the spinning nozzle  22  in cooperation with the air flow toward the fiber bundle inlet, and the yarn tip of the leading yarn is sucked by the suction pipe  34  provided between the nozzle  22  and the front roller  15  and is held thereby. Then, the holding member  26  is fit into the nozzle block  24  again and the piecing preparation is completed. 
     Then, the draft rollers (back roller  11  and third roller  12 ), which were stopped, are redriven, and the sliver S is passed through the middle roller  13  and the front roller  15  and is delivered to the downstream side. At that time, the pressurized air is blew out from the air nozzle  40  provided around the spinning nozzle  22  to oppose toward the sliver S fed from the draft device  10 , the tip section of the sliver S is blown off, sucked into and eliminated by the suction pipe  34 . As a result the fiber is prevented from getting clogged in the guide hole  20 . 
     Under such state in that the leading yarn (spun yarn) Y is held, the yarn feeding roller  30  is released from the yarn path, and the running in the winding direction of the leading yarn Y by the nip roller  29  and the delivery roller  28  are started, and after the injection of the whirling air flow from the nozzle hole  21  is redriven, by stopping the injection of the pressurized air from the air nozzle  40 , the fiber comprising the sliver S is wound around the leading yarn Y and the piecing is carried out. The spinning operation is then restarted. 
     FIG. 4 is a time chart showing the driving timing of the draft rollers (back roller  11  and third roller  12 ), the twisting device  17  (compressed air injection from the nozzle hole  21 ), the air nozzle  40  and the nip roller  29 , after the piecing preparation is completed by holding the yarn tip of the leading yarn by the suction pipe  34 . Referring to FIG. 4, the driving timing of each device will be described. 
     First, when the yarn tip of the leading yarn is held by the suction pipe  34 , the air nozzle  40  is put “ON”, and the pressurized air is blown to the sliver S and the yarn tip is blown off. As a result, the fiber is prevented from being clogged in the guide hole  20  of the spinning nozzle  22 . At that time, the draft rollers  11 , 12 , the twisting device  17  and the nip roller  29  are put “OFF”, and are stopped. 
     Then, the draft rollers  11 , 12  are put “ON” at time Ta, and the sliver S is delivered to the downstream side through the middle roller  13  and the front roller  15 . At that time, the air nozzle  40  is still put “ON”. 
     Next, at time Tb, somewhat later than time Ta, the time the draft rollers  11 , 12  are put “ON”, the nip roller  29  is put “ON” and the running of the leading yarn Y in the winding direction by the nip roller  29  and the delivery roller  28  is started. 
     Then, at time Tc, the twisting device  17  is put “ON” and the piecing is carried out. 
     Lastly, at time Td, the air nozzle  40  is put “OFF”, and the air inside the air manifold unit  42  is injected gradually from the air nozzle  40 . At time Te, the injection of the compressed air from the air nozzle  40  is stopped completely. 
     According to the embodiment of the present invention, since the pressurized air is injected to oppose the sliver S which is delivered by the draft device  10  from the periphery of the spinning nozzle  22 , there are no obstacles to air blowing and the operation efficiency is high. 
     Moreover, compared to the conventional device, since the pressurized air is injected from a position closer to the sliver S, the sliver S can be blown off efficiently, wherein the fiber of which is less prone to be blown off, such as long fiber, can also be blown off reliably. 
     Furthermore, according to the present invention, by setting the force of the pressurized air from the air nozzle  40  to be weaker than the suction force of the spinning nozzle  22  of the twisting device  17  during piecing, and selecting the blowing time of the pressurized air, the joint thickness produced by the piecing can be controlled to be a desired value. 
     In other words, by blowing pressurized air from the air nozzle  40  in a direction toward the sliver S from the draft device  10  which is to be inserted into the guide hole  20  of the spinning nozzle  22 , and blowing off and eliminating a part of the fiber composing the sliver S, the joint thickness can be controlled. The force of the pressurized air from the air nozzle  40  was set to be weaker than the suction force of the spinning nozzle  22 , because, when the force of the pressurized air is stronger than the suction force of the spinning nozzle  22 , all of the fiber of the sliver S fed from the draft device  10  is blown off without entering the guide hole  20 . 
     Next, referring to FIG. 5, the relationship between the stop timing of the air nozzle and the joint thickness will be described. 
     In the figure, the horizontal line shows the timing for stopping the air nozzle, and the stop timing slows down by going to the right, and shows that the blowing time is long. The vertical line shows the joint thickness, and  1  shows that the thickness is the same as the leading yarn Y. 
     First, from point (a) to point (b), the stop timing of the air nozzle  40  is fast, and since the blowing of the pressurized air stops before the sliver S reaches the spinning nozzle  22 , the fiber of the sliver S is not blown off at all. Therefore, the amount of fiber of the sliver S entering the spinning nozzle  22 , is to be the normal fiber amount (the same yarn amount as leading yarn Y), and the diameter of the joint thickness will be theoretically 1.4 times that of the leading yarn Y, as in the same manner as the conventional technology. 
     Then, as the stop timing of the air nozzle  40  is reduced from that of point (b), the joint thickness gradually gets thin since the fiber amount decreases by a part of the fiber of the tip section of the sliver S being blown off by the pressurized air. 
     Point (d) shows that the joint thickness gets to the ideal thickness which is almost the same as the thickness of the leading yarn Y. The stop timing of the air nozzle  40  at point (d) is the same as the timing in which the tip section of the leading yarn Y enters the guide hole  20  of the spinning nozzle  22 . 
     From point (d) to point (c), the stop timing of the air nozzle  40  is slow, and the joint thickness from the end section of the leading yarn Y to the back section will be thinner than the thickness of the leading yarn Y. 
     Furthermore, when the stop timing of the air nozzle  40  slows down and passes over point (e), the piecing cannot be carried out. 
     Considering various conditions, such as the transferring speed of the leading yarn Y and the sliver S, by setting the stop timing of the air nozzle  40  at point (d), the joint thickness can be made nearer to the thickness of the leading yarn Y, and the quality of the spun yarn as a product can be improved by preventing the generation of yarn defects. 
     By lengthening the time between the stopping of the air nozzle  40  to the complete stopping of the blowing of the pressurized air, in other words, by softening the decrease in the pressure of the air, the tendency between point (b) through point (c) of FIG. 5 can be softened. The softening in the tendency of point (b) through point (c) has an effect in that the setting of the stop timing of the air nozzle  40  is facilitated. 
     For softening the decrease in the pressure of the pressurized air, for example, the length of the pipe between the valve (not shown in the drawings) of the air compressing means and the air nozzle  40  can be lengthened, or the number of parts on the valve can be decreased. 
     Referring to FIG. 6, the relationship between the length of the pipe between the valve (not shown in the drawings) of the air compressing means and the air nozzle  40 , the number of ports in of the valve, and the decrease in the pressure of the air after the stopping of the air nozzle  40  will be described. 
     In the figure, point P indicates the stop timing of the air nozzle  40 , line  1  indicates the state in which the pipe length is 20 cm and the port number of the valve is 3, line  2  indicates the state in which the pipe length is 20 cm and the port number of the valve is 2, line  3  indicates the state in which the pipe length is 220 cm and the port number of the valve is 3, and line  4  indicates the state in which the pipe length is 220 cm and the port number of the valve is 2. 
     As is evident from the figure, when lengthening the pipe length, the decrease in the pressure of the pressurized air softens since the pipe serves as a tank and suppresses the decrease in the pressure. Moreover, by decreasing the port number of the valve, the decrease in the pressure of the pressurized air softens since when the port number of the valve is large, the pressurized air leaks from the port and the decrease in the pressure becomes intense. Thus, by decreasing the port number of the valve, the pressurized air leaking from the port can be prevented. 
     The air manifold unit  42  shown in FIG.  1  and FIG. 2 is provided to soften the decrease in the pressure of the pressurized air. Therefore, the present invention is not to be limited to the embodiments illustrated in the drawings and the air manifold unit  42  is not required to be provided. 
     Moreover, referring to FIG.  1  and FIG. 2, it was described that the air nozzle  40  is to be provided in a circular form about the entire periphery of the spinning nozzle  22 , however, the present invention is not to be limited to this configuration, and for example, as shown in FIG. 7, a plurality of air nozzles  40 ′ can be provided around the spinning nozzle  22 . 
     According to the present invention described above, the following beneficial effects can be expected. 
     Since the pressurized air can be blown toward the sliver efficiently and reliably, the sliver can be blown off completely, and the generation of yarn defects can be prevented. 
     By controlling the joint thickness, the joint thickness can be made to be closer to that of the thickness of the leading yarn. 
     Since the distance from the air nozzle to the sliver is close, the pressure control of the pressurized air blown is easy.