Patent Publication Number: US-8973520-B2

Title: Coating machine for coating fiber yarns

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a coating machine for coating fiber yarns. 
     2. Description of the Related Art 
     Referring to  FIG. 1 , a conventional coating machine  1  includes: a yarn supply device  11  for supplying a fiber yarn  100 ; a tank  12  spaced apart from the yarn supply device  11  and having a plastisol  101  therein; a molding die  13  disposed adjacent to the tank  12 ; a drying device  14  disposed spacedly from the molding die  13 ; and a yarn pick-up device  15 . 
     When the fiber yarn  100  passes the tank  12 , it is coated with the plastisol  101 . When the fiber yarn  100  passes through the molding die  13 , the thickness of the plastisol  101  coated on the fiber yarn  100  is adjusted. Thereafter, the coated fiber yarn  100  is set in shape using the heating device  14 , and then, is collected using the yarn pick-up device  15 . 
     Taiwanese Patent No. I332042 discloses a method for coating a fiber yarn  100  (a glass fiber yarn) using a pellet extruder  16  (see  FIG. 2 ). Although coating the fiber yarn  100  by using a plastic material extruded from the pellet extruder  16  is more convenient, when the fiber yarn  100  has a relatively small diameter, it is likely to deform. Besides, it is hard to control the fiber yarn  100  to be centrally located in the coated layer, and thus, the coated layer and the fiber yarn  100  are likely to separate from each other. Furthermore, because the fiber yarn  100  is made of a plurality of filaments, the molding die  13  may be plugged by the fiber yarn  100  when the fiber yarn  100  passes therethrough. Thus, the thickness of the coated layer is hard to control, and more seriously, it may be necessary to shut down the coating machine for repair. 
     Moreover, after the coated fiber yarn  100  leaves the pellet extruder  16 , it is guided and pressed by a roller  17  to be cooled in a cooling water tank  13 . Because the coated layer on the fiber yarn  100  is not completely cured, the pressure from the roller  17  will deform the coated fiber yarn  102 , resulting in an elliptical cross-section, as shown in  FIG. 3 . This may adversely affect uniformity and surface evenness of a knitted fabric made of the coated fiber yarn  100 . 
     On the other hand, when the fiber yarn  100  passes through the molding die  13  in the conventional coating machine  1  or in the pellet extruder  16 , friction between the molding die  13  and the fiber yarn  100  may result in wear of the molding die  13 . In order to lengthen the life of the molding die  13 , the molding die  13  is usually made of platinum or diamond. Therefore, the coated fiber yarn  100  made by a conventional method or a conventional machine  1  has a relatively high cost. 
     SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a coating machine for coating fiber yarns that can overcome the aforesaid drawbacks associated with the prior art, and that has improved production efficiency and availability. 
     Accordingly, a coating machine for coating fiber yarns of this invention comprises: 
     a yarn supply device to supply at least one fiber yarn; 
     a coating device including a tank for receiving a coating material, a drum rotatably disposed in the tank, and at least one annular groove formed circumferentially in an outer surface of the drum for receiving the fiber yarn and the coating material and for coating the fiber yarn with the coating material; 
     a thickness adjuster disposed downstream of the coating device, and including an adjuster support and at least one adjusting die mounted movably to the adjuster support, the adjusting die including a through hole for passage of the coated fiber yarn, the through hole having an upstream inlet end and a downstream outlet end and being tapered from the upstream inlet end to the downstream outlet end; 
     a shape-setting device disposed downstream of the thickness adjuster for setting the shape of the coated fiber yarn, the shape-setting device having a heating unit controllable to operate at a predetermined temperature for heating the coated fiber yarn; 
     a cooling device disposed downstream of the shape-setting device for cooling the coated fiber yarn; and 
     a yarn pick-up device disposed downstream of the cooling device for collecting the coated fiber yarn. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments of the invention, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram for illustrating a conventional coating machine; 
         FIG. 2  is a schematic diagram for illustrating how a fiber yarn is coated using a coating method disclosed in Taiwanese Patent No. 1332042; 
         FIG. 3  is a cross-sectional view for illustrating a coated fiber yarn made according to the conventional machine or the conventional method; 
         FIG. 4  is a schematic diagram for illustrating the first preferred embodiment of a coating machine according to the present invention; 
         FIG. 5  is a fragmentary enlarged cross-sectional view for illustrating a coating device and a thickness adjuster of the coating machine shown in  FIG. 4 ; 
         FIG. 6  is a top view of the coating device and thickness adjuster shown in  FIG. 5 ; 
         FIG. 7  is a fragmentary enlarged view of the thickness adjuster shown in  FIG. 5 ; 
         FIG. 8  is a flow chart showing the first preferred embodiment of a method for coating fiber yarns according to the present invention; 
         FIG. 9  is a schematic diagram for illustrating the second preferred embodiment of a coating machine according to the present invention; and 
         FIG. 10  is a flow chart showing the second preferred embodiment of a method for coating fiber yarns according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Before the present invention is described in greater detail with reference to the accompanying preferred embodiments, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure. 
     Referring to  FIG. 4 , the first preferred embodiment of a coating machine  2  according to the present invention comprises, from upstream to downstream, a yarn supply device  21 , a coating device  22 , a thickness adjuster  23 , a shape-setting device  24 , a cooling device  25 , and a yarn pick-up device  26 . 
     The yarn supply device  21  supplies a plurality of fiber yarns  200 . In the preferred embodiment, the yarn supply device  21  includes forty bobbins  211  to supply forty fiber yarns  200 . 
     Referring to  FIGS. 4 to 6 , the coating device  22  includes a tank  221  for receiving a coating material, a drum  222  rotatably disposed in the tank  221 , and a plurality of annular grooves  223  formed circumferentially in an outer surface of the drum  222  for receiving the fiber yarns  200  and the coating material and for coating the fiber yarns  200  with the coating material. The coating material temporally adheres to the annular grooves  223  with the rotation of the drum  222 . The fiber yarns  200  received in the annular grooves  223  can be coated with the coating material and move in a direction away from the yarn supply device  21  through the rotation of the drum  222 . In this embodiment, the coating device  22  includes forty annular grooves  223 , and the coating material is liquid, and includes polyvinyl chloride (PVC). 
     Referring to  FIGS. 5 and 6 , the thickness adjuster  23  is disposed downstream of the coating device  22 , and includes an adjuster support  231  and a plurality of adjusting dies  232 . Each of the adjusting dies  232  is mounted movably to the adjuster support  231 , and has a through hole  234  for passage of a corresponding one of the coated fiber yarns  200 . The through hole  234  in each of the adjusting dies  232  has an upstream inlet end  236  and a downstream outlet end  237 , and is tapered from the upstream inlet end  236  to the downstream outlet end  237 . 
     As shown in  FIG. 7 , each of the adjusting dies  232  further has a surrounding wall  233  defining the through hole  234 , and a diamond-like carbon layer  235  that is coated on an inner surface of the surrounding wall  233 . A conventional coating method, such as a vapor deposition method may be used to coat the inner surface of the surrounding wall  233 . In this embodiment, the thickness adjuster  23  includes forty adjusting dies  232  aligned with the forty annular grooves  223 , respectively. 
     In each of the adjusting dies  232 , the surrounding wall  233  includes an upstream section that has the upstream inlet end  236  and that forms a first truncated conical surface  238 , and a downstream section that has the downstream outlet end  237  and that forms a second truncated conical surface  239  coaxial with the first truncated conical surface  238 . The downstream section is longer than the upstream section. An included angle defined between the first truncated conical surface  238  and an axis (X) of the surrounding wall  233  is greater than that defined between the second truncated conical surface  239  and the axis (X) of the surrounding wall  233 . 
     The shape-setting device  24  is disposed downstream of the thickness adjuster  23  for setting the shape of the coated fiber yarns  200 , and includes a heating unit  241  and a monitor  242 . The heating unit  241  is controllable to operate at a predetermined temperature for heating the coated fiber yarns  200 . The monitor  242  is used to control the heating unit  241 . 
     The shape-setting device  24  also includes a mechanism (not shown) that can be controlled to move the coated fiber yarns  200  within the shape-setting device  24  at a predetermined speed. Preferably, the mechanism moves the coated fiber yarns  200  at a speed of 3 msec. The heating unit  241  can heat the coated fiber yarns  200  to a temperature ranging from 0° C. to 300° C. to cure the coating material coated on the fiber yarns  200 . Preferably, the coated fiber yarns  200  are heated to a temperature ranging from 150° C. to 300° C. 
     Although the coating machine  2  in this embodiment is exemplified for coating forty fiber yarns  200 , it can be configured for coating a single fiber yarn  200 . 
     The cooling device  25  is disposed downstream of the shape-setting device  24  for cooling the coated fiber yarns  200 , and includes an air cooler  251 , a diameter detecting member  252  for detecting a diameter of each of the coated fiber yarns  200 , and a cooling gas ejector  253  disposed downstream of the air cooler  251 . After passing the cooling device  25 , the coated fiber yarns  200  are transported to the yarn pick-up device  26 . In this embodiment, the air cooler  251  includes a water-cooled fan, and the cooling gas ejector  253  includes a condenser. 
     The yarn pick-up device  26  is disposed downstream of the cooling device  25  for collecting the coated fiber yarns  200 , and includes a plurality of bobbins  261 , a transport roller assembly  260 , and a yarn breakage detector  264 . The bobbins  261  are spaced apart from each other, and are used for respectively collecting the coated fiber yarns  200  from the cooling device  25 . The transport roller assembly  260  is used for transporting the coated fiber yarns  200  from the cooling device  25  to the bobbins  261 , and includes a transport roller  262  having an axial flow passage  263  for permitting a coolant to flow therethrough. The yarn breakage detector  264  is disposed between the cooling device  25  and the transport roller assembly  260 . 
     Referring to  FIG. 8 , the first preferred embodiment of a method for coating the fiber yarns  200  according to this invention comprises a coating step  31 , a thickness adjusting step  32 , a shape-setting step  33 , a cooling step  34 , a diameter detecting step  35 , a yarn breakage detecting step  36 , and a yarn collecting step  37 . 
     In some embodiments, the tank ( 221 ) of the coating device ( 22 ) of the coating machine may be disposed to permit the path of the fiber yarn ( 200 ) to extend thereover in a straight line, and the outer circumferential surface of the drum ( 222 ) may be rotatable between a topmost position ( 202 ), where a tangent line ( 201 ) of an uppermost region ( 203 ) of the outer circumferential surface may be parallel to the path of the fiber yarn ( 200 ), and a bottommost position ( 204 ), where a lowermost region ( 205 ) of the outer circumferential surface may be immersed in the coating material. In some embodiments, when the outer circumferential surface is rotated to move from the bottommost position ( 204 ) to the topmost position ( 202 ), the coating material in the tank ( 221 ) is drawn up by movement of the lowermost region ( 205 ) to the topmost position ( 202 ), thereby permitting the fiber yarn to be coated with the coating material. Moreover, in some embodiments, the through hole ( 234 ) of the adjusting die ( 232 ) of the thickness adjuster ( 23 ) may be oriented to be aligned with the path of the fiber yarn ( 200 ) that extends over the tank ( 221 ) so as to permit passage of the coated fiber yarn therethrough. In some embodiments, when the fiber yarn passes through the coating device ( 22 ) and the thickness adjuster ( 23 ), it may travel along a straight yarn path. Thus, in some embodiments, the abrasion of the fiber yarn passing through the coating device and the thickness adjuster can be reduced, and the coating material can be uniformly coated over the fiber yarn. 
     In this embodiment, the method is conducted using the coating machine  2  described above. 
     Referring back to  FIGS. 4 to 6 , in the coating step  31 , the fiber yarns  200  from the yarn supply unit  21  are oriented and transported by the respective annular grooves  223  on the drum  222 . At the same time, the fiber yarns  200  are coated by the coating material adhered to the drum surface in the annular grooves  223 . With the rotation of the drum  222 , the coating material can be coated on all of the fiber yarns  200 . 
     In the step  32 , the coated fiber yarns  200  are guided to enter the respective through holes  234  of the adjusting dies  232  at the upstream inlet ends  236 . The excess coating material is removed from the coated fiber yarns  200  when the coated fiber yarns  200  exit the downstream outlet ends  237  of the respective adjusting dies  232 , thereby adjusting the thickness of the coating material on the fiber yarns  200 . 
     Referring to  FIGS. 5 to 7 , the adjuster support  231  includes a support plate  2311  that has a lower end fixed to a base  2310 , and a non-supported upper end extending upward from the base  230 . Each adjusting die  232  is fixed to the non-supported upper end of the support plate  2311  near the upstream inlet end  236  and is therefore suspended from the support plate  2311 . Since the adjusting dies  232  are mounted movably to the adjuster support  231 , the adjusting dies  232  are permitted to move relative to the adjuster support  231  when the excess coating material on the fiber yarns  200  is scraped by the adjusting dies  232 . Therefore, wear of the adjusting dies  232  can be alleviated, and the life of the adjusting dies  232  can be lengthened without coating the adjusting dies  232  with any expensive material such as platinum. Accordingly, the cost for producing the coated fiber yarns  200  can be reduced. Furthermore, in each of the adjusting dies  232 , since the inner surface of the surrounding wall  233  is coated with the diamond-like carbon layer  235 , wear-resistance of the adjusting dies  232  is further improved. In addition, since the through hole  234  is tapered from the upstream inlet end  236  to the downstream outlet end  237 , the fiber yarn  200  can be centered properly and provided with an even thickness of the coating material. 
     In the cooling step  34 , the coated fiber yarns  200  are cooled by passing through the air cooler  251  and the cooling gas ejector  253  in sequence. Thereafter, the coated fiber yarns  200  are transported to the yarn pick-up device  26 . Since the coating material on the fiber yarns  200  is hardened by the heating unit  241 , and then cooled by the air cooler  251  and the cooling gas ejector  253  through a direct contact with cooling air and gas, the present invention eliminates the problem of deformation experienced in the prior art shown in  FIG. 2  due to the use of the cooling water tank  18  and the roller  17 . Accordingly, the coated fiber yarns  200  can be provided with an even thickness of the coating material. 
     The diameter detecting step  35  is conducted by detecting the diameter of each of the coated fiber yarns  200  using the diameter detecting member  252 , and is conducted simultaneously with the cooling step  34 . In the yarn breakage detecting step  36 , whether or not each of the coated fiber yarns  200  breaks is detected using the yarn breakage detector  264 . The yarn collecting step  37  is conducted by transporting the coated fiber yarns  200  that have been treated by the cooling step  34  to the bobbins  261  through the transport roller assembly  260 , followed by collecting the coated fiber yarns  200  using the bobbins  261 . By the above steps, the method for coating the fiber yarns  200  can be conducted more smoothly to improve production efficiency and availability. 
       FIG. 9  illustrates the second embodiment of the coating machine  2  of this invention. The second embodiment differs from the first embodiment in that the coating machine  2  further comprises a returning device  27  disposed downstream of the cooling device  25  and upstream of the yarn pick-up device  26 . 
     In addition, the annular grooves  223  are divided into first and second groups. The first group of the annular grooves  223  is used to conduct a coating operation on the fiber yarns  200  initially fed by the yarn supply device  21 . The second group of the annular grooves  223  is used to repeat the coating operation on the fiber yarns  200  that have been coated in the first group of the annular grooves  223 . The returning device  27  is operative to return at least one of the fiber yarns  200 , which has been coated in one of the annular grooves  223  of the first group and which has been cooled by the cooling device  25 , to one of the annular grooves  223  of the second group to repeat the coating operation. 
       FIG. 10  illustrates a flow chart of the second preferred embodiment of a method for coating the fiber yarns  200  according to this invention, which is conducted using the coating machine  2  of the second preferred embodiment. The second embodiment differs from the first embodiment in that the method further comprises a diameter increasing step  38 . 
     In the diameter increasing step  38 , the coated fiber yarns  200  that have been treated by the steps  31 - 35  are returned to the coating device  22  using the returning device  27 . Thus, the coated fiber yarns  200  can be coated again with the coating material to have an increased diameter. 
     In particular, the coating machine  2  is operative for coating forty fiber yarns  200 . The coating device  22  includes eighty annular grooves  223  which are divided into the first group of forty annular grooves  223  and the second group of forty annular grooves  223 . Furthermore, the thickness adjuster  23  includes eighty adjusting dies  232 , each of which is aligned with one of the annular grooves  223 . 
     Therefore, the coating step  31  and the diameter increasing step  38  can be conducted simultaneously by the coating device  22  without interference therebetween. 
     Besides, since the diameter increasing step  38  is used to repeat coating of the coated fiber yarns  200 , the fiber yarns  200  can be provided with a required coating thickness as desired. With the use of the diameter increasing step  3 B, it is possible, to prevent the fiber yarns  200  from being overly coated in one time with an excessively thick coating layer, which can lead to difficulties in subsequent hardening and/or cooling of the coating material. 
     While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements.