Abstract:
A yarn false twist texturing machine for texturing multifilament synthetic yarns ( 4 ), wherein a heating device and a false twist unit are arranged within a false twist zone. An aftertreatment zone accommodates a second heating device and a countertwist device. The countertwist device is used to remove any residual twist that is left in the yarn by the false twist unit. To be able to perform a selective treatment by the countertwist device, a first embodiment provides for a twist imparting member yarn guide means for guiding the yarn ( 4 ) and being adapted for reciprocal movement between an idle position for not treating the yarn ( 4 ) or for threading it and an operating position for treating the yarn ( 4 ). In a second embodiment, the countertwist device comprises a movable twist imparting member ( 28, 29 ), which is adapted for reciprocal movement between an idle position for not treating or for threading the yarn ( 4 ) and an operating position for treating the yarn ( 4 ) by twisting it.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This is a continuation of international application PCT/EP01/12063, filed Oct. 18, 2001, the disclosure of which is incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a false twist texturing machine for texturing a plurality of thermoplastic multifilament yarns.  
           [0003]    A false twist texturing machine of this general type is disclosed, for example, in U.S. Pat. No. 5,644,908. The false twist texturing machine as described in that patent comprises a plurality of processing stations, each of which produces a crimped yarn from a fed flat yarn. To this end, a first feed system withdraws the yarn from a feed yarn package and advances it into a false twist zone. The false twist zone includes a heating device, a cooling device, and a false twist unit mounted in series. Within the false twist zone, the yarn undergoes a drawing and setting. The false twist unit produces a twist, which extends opposite to the direction of the advancing yarn, so that within the cooling device and the heating device, in which the yarn undergoes thermal treatment, the yarn exhibits a false twist, which is removed at the outlet of the false twist unit.  
           [0004]    For a thermal aftertreatment, a second feed system advances the yarn through a second heater as well as to a takeup device, which winds the yarn to a package. Since after removing the false twist, a greater or lesser residual twist remains in the yarn as a function of the process, the known texturing machine includes a countertwist device in the form of an entanglement nozzle upstream of the takeup device. The countertwist device leads to a twist treatment, which removes the residual twist in the yarn.  
           [0005]    Whether or not, and the extent a twist treatment by the countertwist device is needed, depends both on the polymer type of the yarn and on the adjusted process parameters, for example, the yarn speed.  
           [0006]    Furthermore, for increasing the effectiveness of the twist treatment, it is known from WO99/09239 and corresponding U.S. Pat. No. 6,301,870 to arrange the countertwist device directly in the outlet region of the second heating device, so as to enable a well defined setting of the yarn in the heating device and, with that, a destruction of the residual twist. However, in so doing, one should consider that such heating devices, as disclosed, for example, in EP 0 595 086 B1 and corresponding U.S. Pat. No. 5,431,002, often cooperate with a guide tube for a thermal adjustment or for threading the yarn. Thus, for threading the yarn, the guide tube is connected to an injector, so that the yarn is taken in by suction at the inlet of the heating device, and so that it is advanced via the guide tube to a predetermined position within the machine.  
           [0007]    It is therefore an object of the invention to provide the initially described false twist texturing machine with a countertwist device, which is easy to use when a twist treatment is needed, and which does not interfere with a pneumatic threading of the yarn at the beginning of a process.  
         SUMMARY OF THE INVENTION  
         [0008]    In accordance with the invention, the above and other objects and advantages of the invention are achieved by the provision of a yarn false twist texturing machine of the described type and wherein a yarn countertwist device is positioned in the yarn path of travel between the second heating device and the winding device, with the countertwist device comprising a twist imparting member that cooperates with a yarn guide means.  
           [0009]    The invention distinguishes itself in that it permits adapting the guidance of the yarn in the countertwist device to respective needs. In this connection, the invention offers a first variant, in which the position of the yarn advance is variable, and a second variant, in which the position of the yarn advance remains unchanged. In the first variant, a twist imparting member of the countertwist device cooperates with a guide means which guides the advancing yarn, and which is adapted for reciprocating between an idle position and an operating position. In the idle position, the yarn is guided in such a manner that it is separated from the twist imparting member and undergoes no twist treatment. This position is thus also well suited for threading the yarn. Only when the guide means is in its operating position, will the twisting device treat the yarn.  
           [0010]    In the second variant, which is based on the same fundamental concept, the yarn advance within the machine remains substantially unchanged. To this end, the countertwist device includes a movable twist imparting member, which is likewise adapted for reciprocal movement between an idle position and an operating position. In the idle position, the yarn undergoes no twist treatment. Only when the twist imparting member is moved to its operating position, will it be possible to treat the yarn by twisting it.  
           [0011]    As a twist imparting member, it is possible to use, for example, rolls or guide edges, over which the yarn advances obliquely for receiving a twist treatment. It is especially preferred to realize the twist imparting member as an entanglement nozzle. In this instance, the entanglement nozzle comprises a yarn channel for guiding the yarn. In this channel, a tangentially entering air flow produces the twist on the yarn. The yarn channel communications with a continuous threading slot, which permits inserting the yarn from the outside into the yarn channel. With that, it is possible to advance the yarn both by the guide means and by the entanglement nozzle itself, inside the yarn channel in the operating position and outside the yarn channel in the idle position.  
           [0012]    In a particularly advantageous further development of the invention, the entanglement nozzle comprises a piston that is movable transversely to the yarn advance, and adjustable within a housing between the idle position and the operating position. In the transverse direction of its longitudinal axis, the piston includes both the yarn channel with the threading slot and a nozzle bore terminating in the yarn channel. The housing includes a yarn inlet, and a yarn outlet opposite thereto, as well as a compressed air connection. In the operating position of the piston, the yarn channel interconnects the yarn inlet and the yarn outlet. Likewise, the nozzle bore is coupled with the compressed air connection, so that a twist treatment on the yarn occurs within the yarn channel.  
           [0013]    To interrupt the treatment of the yarn, or to enable a threading of the yarn through the yarn inlet and yarn outlet, it is especially advantageous to construct the threading slot that connects to the yarn channel, with a V-shaped cross section at one front end of the piston. Thus, the movement of the piston between the operating position and the idle position makes it possible to guide the yarn advancing between the yarn inlet and the yarn outlet, automatically through the threading slot into or out of the yarn channel.  
           [0014]    To interrupt the supply of compressed air to the entanglement nozzle, an advantageous further development of the invention proposes to close the compressed air connection in the housing by a control surface of the piston. In so doing, the control surface of the piston is guided by the movement of the piston to the idle position in the region of the compressed air connection.  
           [0015]    Another preferred further development of the invention is especially suited for automatically threading the yarn. In this development, both the yarn inlet of the housing and the yarn outlet of the housing each mount a guide tube. For threading the yarn, it is possible to connect an injector to one of the guide tubes, so that the yarn can be pneumatically threaded in a simple manner, while the piston is in its idle position. Advantageously, the guide tube arranged at the yarn inlet of the entanglement nozzle is coupled directly with the outlet of a set heater.  
           [0016]    The movement of the guide means or the movement of the twist imparting member is preferably controlled by an actuator. The actuator may be activated directly by an operator or via a control device.  
           [0017]    In the false twist texturing machine, the false twist unit may impart to the yarn a so-called Z-twist or an S-twist. To be able to use the countertwist device arranged upstream of the takeup device both for the Z-twist and for the S-twist, it will be of particular advantage, when the twist imparting member is made exchangeable, so as to enable a twist treatment that is selectively applied against the S-twist or against the Z-twist.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    In the following, two embodiments of the yarn false twist texturing machine according to the invention are described in greater detail with reference to the attached drawings, in which:  
         [0019]    [0019]FIG. 1 is a schematic view of a yarn false twist texturing machine which embodies the invention;  
         [0020]    [0020]FIG. 2 is a longitudinally sectioned view parallel to the direction of movement of the yarn showing the countertwist device of the false twist texturing machine shown in FIG. 1 in its operating position;  
         [0021]    [0021]FIG. 3 is a sectional view transverse to the direction of movement of the yarn showing the countertwist device of the false twist texturing machine shown in FIG. 1 in its operating position;  
         [0022]    [0022]FIG. 4 is a longitudinally sectioned view parallel to the direction of movement of the yarn showing the countertwist device of the false twist machine shown in FIG. 1 in its idle position;  
         [0023]    [0023]FIG. 5 is a sectional view transverse to the direction of movement of the yarn showing the countertwist device of the false twist texturing machine shown in FIG. 1 in its idle position;  
         [0024]    [0024]FIG. 6 is a longitudinally sectioned view parallel to the yarn advance showing a further embodiment of an entanglement nozzle; and  
         [0025]    [0025]FIG. 7 is a sectional view transverse to the yarn advance showing an entanglement nozzle of FIG. 6. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    [0026]FIG. 1 schematically illustrates an embodiment of a yarn false twist texturing machine according to the invention. The yarn false twist texturing machine comprises a creel frame  2 , a processing frame  3 , and a takeup frame  1 . A service aisle  5  is formed between the processing frame  3  and the takeup frame  1 . On the side of the takeup frame  1  opposite to the service aisle  5 , the creel frame  2  extends in spaced relationship with the takeup frame  1 . Between the takeup frame  1  and the creel frame  2 , a doffing aisle  6  is formed. The takeup frame  1  accommodates three takeup devices  9 , one overlying the other, which are part of each processing station of the machine. In each processing station, a first delivery system  13  withdraws, via a yarn guide  12 , a yarn  4  from a supply yarn package  7  arranged in the creel frame  2 . From the first delivery system  13 , the yarn advances into a false twist zone, which comprises a heating device  8 , a cooling device  10 , and a false twist unit  14 . Subsequently, a second delivery system  15  withdraws the yarn  4  from the false twist zone and advances it to a second heating device  16 . In this process, the speed of the yarn is adjusted by a third delivery system  18  downstream of the second heating device  16 .  
         [0027]    A countertwist device  17  is arranged between the second heating device  16 , herein referred to as a set heater, and the third delivery system  18 . For guiding the yarn, the countertwist device  17  mounts on its inlet side and its outlet side respectively a first guide tube  25  and a second guide tube  26 . Upstream of the countertwist device  17 , the first guide tube  25  is coupled with the outlet of the set heater  16 . An injector  27  connects to the second guide tube  26 , which extends below a platform  23  of the service aisle  5 . The second guide tube  26  ends directly upstream of the third feed system  18 .  
         [0028]    The third delivery system  18  advances the yarn  4  to the takeup device  9 . The takeup device  9  comprises a friction roll  19  for driving a package  20  while being wound, a yarn traversing device  24  upstream of the friction roll  19 , a storage  21  serving to receive full packages, as well as a tube magazine  22 . In the takeup device  9 , the yarn  4  is wound to a package  20 .  
         [0029]    In the embodiment of the false twist texturing machine as shown in FIG. 1, the delivery system  13  withdraws the yarn  4  from the supply yarn package  7  and advances it into the false twist zone. The false twist is imparted to the yarn  4  by the false twist unit  14 . The thus-produced false twist returns against the direction of the advancing yarn to the first delivery system  13  or a first deflection roll  11 . 1 , which could be constructed as a twist stop roll. Thus, the yarn advances in a false twisted condition through the first heating device  8  into the cooling device  10 . In its twisted condition, the yarn is drawn and set in the heating device  8 , which leads to a setting of the twist and thus to a satisfactory crimp result in the yarn  4 .  
         [0030]    After the yarn  4  has left the false twist zone, it exhibits a greater or lesser residual twist. Such a residual twist, which causes the yarn  4  to turn about itself, however, is undesired for a subsequent further processing. Consequently, the countertwist device  17  imparts to the yarn a countertwist, which is opposite in its direction to that of the false twist. This countertwist propagates as far back as the second feed system  15 . Since the countertwist acts against the residual twist, the setting and the relaxation treatment in set heater  16  lead to a twistfree yarn  4 . In this process, the countertwist device is in an operating position, as is described in greater detail in the following.  
         [0031]    The countertwist device  17  is schematically illustrated in FIGS.  2 - 5 . While FIGS. 2 and 3 show the countertwist  17  in an operating position, FIGS. 4 and 5 show it in an idle position. The following description will apply to FIGS.  2 - 5 , unless express reference is made to one of the Figures.  
         [0032]    [0032]FIGS. 2 and 3 show the countertwist device in its operating position, with the countertwist device being shown in a longitudinally sectioned view parallel to the yarn advance (FIG. 2), and in a cross sectional view transverse to the yarn advance (FIG. 3). As a twist imparting member, the countertwist device includes an entanglement nozzle  28 . To this end, the entanglement nozzle  28  comprises a piston  29 , which extends in a cylindrical housing  30  in the transverse direction of the yarn advance. In a plane of the advancing yarn, the housing  30  has on its one side a yarn inlet  31  and on its opposite side a yarn outlet  32 . The yarn inlet  31  and yarn outlet  32  include respectively an inlet yarn guide  44 . 1  and an outlet yarn guide  44 . 2 . In concentric relationship with the yarn inlet  31 , the housing mounts on its outside the first guide tube  25 . On the opposite side, the second guide tube  26  connects to the housing  30  at the height of the yarn outlet  32 . Between the yarn inlet  31  and the yarn outlet  32 , the piston  29  extends in the housing  30 .  
         [0033]    In the transverse direction of its longitudinal axis, the piston  29  includes a continuous yarn channel  33 , which connects the yarn inlet  31  to the yarn outlet  32 . The yarn channel  33  includes a continuous threading slot  34 , which has a V-shaped opening cross section in the direction of movement of the piston  29 . To this end, the threading slot  34  is provided in the lower front end of the piston  29 . At its opposite front end, the piston  29  connects to an actuator  36 .  
         [0034]    In a transverse direction of the yarn channel  33 , the piston  29  is provided with a nozzle bore  35 , which terminates with its one end in the yarn channel  33  and connects with its other end to a pressure line  38 , which is joined to the housing  30  via a compressed-air connection  37 .  
         [0035]    In FIGS. 2 and 3, the entanglement nozzle  28  is shown in its operating position. In this situation, the piston  29  is held in its position by the actuator  36  and a spring  39 , which is operative on the lower front end of the piston  29 , and which is supported on the base of the closed housing  30 . The yarn  4  enters the yarn channel  33  via yarn inlet  31 . Inside the yarn channel  33 , compressed air enters in a substantially tangential relationship through the nozzle bore  35 , and acts upon the yarn  4  to produce a countertwist. This countertwist propagates as far back as the feed system  15 . The yarn  4  leaves the entanglement nozzle  28  via the yarn outlet  32 , and advances through the second guide tube  26  to the third feed system  18 .  
         [0036]    In cases wherein no twist treatment of the yarn  4  by the countertwist device  17  is desired, the actuator  36  is activated for moving the piston  29 . Subsequently, the piston  29  is moved in the transverse direction of the yarn advance, to its idle position within the housing  30 . This situation is shown in FIGS. 4 and 5. In this connection, FIG. 4 is a longitudinally sectioned view of the entanglement nozzle  28  parallel to the plane of the advancing yarn, and FIG. 5 is a cross sectional view thereof in the transverse direction of the yarn advance. In this situation, the piston  29  is displaced such that the yarn inlet  31  and the yarn outlet  32  are interconnected via a large opening cross section of the threading slot  34 . The yarn channel  33  is removed from the advancing yarn. At the same time, a control surface of the piston  29  closes the compressed-air connection  37 , note FIG. 5, thereby preventing additional compressed air from entering the interior of the housing  30 . In the idle position, the piston  29  is held by the actuator  36  and spring  39 .  
         [0037]    The situation of the entanglement nozzle  28  shown in FIGS. 4 and 5, is in particular also suited for enabling an automatic threading of the yarn  4 . As previously shown in FIG. 1, the outlet of set heater  16  connects to the first  25  and the second guide tube  26 . The first guide tube  25  and the second guide tube  26  surround respectively the yarn inlet  31  and the yarn outlet  32 . Connected to the second guide tube  26  is the injector  27 , which is biased with compressed air for threading the yarn  4 . In this process, a vacuum for taking in the yarn  4  by suction is generated both in the tube section upstream of the injector  27  and in the set heater  16 . This makes it possible to guide the yarn through the set heater  16 , into the first guide tube  25 , to the yarn inlet  31  of the entanglement nozzle  28 . Based on the large opening cross section within the entanglement nozzle  28 , the yarn is sucked into the second guide tube  26  directly via the yarn outlet  32 . Subsequently, it is possible to take over the yarn at the outlet of the second guide tube  26 , a short distance upstream of the third feed system  18 .  
         [0038]    After the yarn  4  has been threaded in the machine, it will be possible to guide the piston  29  by means of the actuator  36  to the operating position within the housing  30 , when a treatment by the countertwist device is needed.  
         [0039]    In this process, the yarn  4  advancing between the yarn inlet  31  and the yarn outlet  32 , automatically slides via the threading slot  34  into the yarn channel  33 . At the same time, the nozzle bore  35  is coupled with the lateral compressed-air connection  37 . Compressed air is allowed to enter, so that it is possible to perform a corresponding treatment of the yarn  4 .  
         [0040]    [0040]FIGS. 6 and 7 illustrate a further embodiment of a countertwist device, which is used in particular in false twist texturing machines, wherein a manual operation is performed.  
         [0041]    In this embodiment of the countertwist device, an entanglement nozzle  28  is provided as the twist imparting member. FIG. 6 illustrates a longitudinally sectioned view of the entanglement nozzle parallel to the yarn advance, and FIG. 7 is a cross sectional view thereof in the transverse direction of the yarn advance. The following description will apply to both Figures.  
         [0042]    The entanglement nozzle  28  includes a continuous yarn channel  33 . Toward one side, the yarn channel  33  connects without interruption to a threading slot  34 . The threading slot  34  has a V-shaped opening cross section. In the transverse direction of the yarn channel  33 , a nozzle bore  35  is provided, which connects to a pressure line  38 .  
         [0043]    A guide means  40  is associated with the entanglement nozzle  28 . The guide means  40  comprises a support  43  as well as a first yarn guide  41  in the yarn path upstream of the yarn channel  33  and a second yarn guide  42  in the yarn path downstream of the yarn channel  33 . These two yarn guides  41 ,  42  are mounted to the support  43 . The guide means  40  connects to an actuator  36 . The actuator permits adjusting the guide means  40  in its location between an operating position as shown, and an idle position not shown. In the operating position, the yarn guides  41  and  42  guide the yarn  4  through the yarn channel  33 . In this situation, the yarn  4  undergoes a twist treatment.  
         [0044]    In the case that no twist treatment is desired, the actuator  36  will be activated, so that the guide means  40  is moved such that the yarn guides  41  and  42  are guided into the region of the threading slot  34 . In so doing, the yarn  4  is automatically removed from the yarn channel  33 .  
         [0045]    In the case of the countertwist device shown in FIGS. 6 and 7, the twist imparting member could also be formed by a roll, which extends in oblique relationship with the advancing yarn. In this connection, the guide means  40  would establish a contact between the yarn  4  and the roll in the operating situation. In the case that no treatment is desired, the guide means may be moved to discontinue the contact between the yarn  4  and the roll.