Abstract:
The present invention relates to a striping apparatus of a circular knitting machine, comprising: a selector, a controller, a yarn-feed unit, and a drive unit. The yarn-feed unit has two portions; the first portion includes a yarn-changing plate, which feeds a yarn into a yarn-entering position, and the second portion includes a movable blade, which clips the tail of the yarn when standby and cuts off an old yarn so that the old yarn can depart from fabric when changing yarns and the operation can back to the standby state. In the preferred embodiments of the present invention, different cams respectively drive the yarn-changing plate and the movable blade, and even though a new yarn and an old yarn are farther spaced, the timings of the cams can be adjusted to release the tail of new the yarn from the movable blade before it is torn off.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a striping apparatus of a knitting machine, particularly to a striping apparatus of a circular knitting machine. 
   BACKGROUND OF THE INVENTION 
   There are striping apparatus technologies of circular knitting machines well known to people, such as U.S. Pat. No. 6,655,176 “Striping Apparatus For Circular Knitting Machines” and U.S. Pat. No. 5,070,709 “Striping System For Circular Knitting Machine”, which respectively disclose striping apparatuses feeding different yarn into the knitting needle of a knitting machine. Besides, U.S. Pat. No. 5,218,845 “Circular Knitting Machine Striper Control System” discloses a controller for a striping apparatus. 
   As shown in from  FIG. 1A  to  FIG. 1D , the striper structure of the abovementioned U.S. Pat. No. 5,218,845 comprises: yarn-changing plates  10 ; movable blades  11 ; and drive elements (not shown in the drawings), used to drive the yarn-changing plates  10  and the movable blades  11 . In normal state, the yarn-changing plate  10  is at a non-enable normal position, and the movable blade  11  also withdraws back to the main body  12 , and a hook  110  clips the yarn to position at the front edge  120  of the main body  12 . As shown in  FIG. 1B , when the machine begins to feed yarns, the drive element pushes the yarn-changing plate  10 , and then, the front end of the yarn-changing plate  10  extends outward. Simultaneously, the rear end  101  of the yarn-changing plate  10  touches a first pin  111  of the movable blade  11  to drive the movable blade  11  toward the left side of the  FIG. 1C  until the yarn-changing plate  10  reaches an external yarn-feed position, and then, the hook  110  of the movable blade  11  releases a yarn Y, as shown in  FIG. 1C . Naturally, before the hook  110  releases the yarn Y, the yarn-changing plate  10  has transferred the yarn Y to the yarn-feed position, and a knitting needle  13  hooks the yarn Y to perform knitting operation. 
   Lastly, when yarn is intended to change, the yarn-changing plate  10 , which has reached the external yarn-feed position beforehand, will be pulled by the drive element back to the normal position, as shown in  FIG. 1A . During the process that the yarn-changing plate  10  moves to the right side of  FIG. 1D , a nose  102  of the yarn-changing plate  10  will touch a second pin  112  of the movable blade  11  and actuate the movable blade  11  to move rightward and back to the normal position, and then, the hook  110  of the movable blade  11  will cut off the yarn Y and clip the tail of the yarn Y at the front edge  120  of the main body  12 . 
   In general, such a striping apparatus can provide multiple different colors of yarns; for example, the four-color striping apparatus has four sets of parallel-arranged yarn-changing plates  10  and movable blades  11  to change four kinds of yarns respectively, and it is the same for the six-color striping apparatus; the more the number of yarns, the greater the width of the striping apparatus. In the striping apparatus disclosed in the abovementioned U.S. Pat. No. 5,218,845, as the movable blade  11  is driven by the yarn-changing plate  10 , the time that the yarn-changing plate  10  touches the second pin  112  of the movable blade  11  is later than the time that the drive element begins pushing the yarn-changing plate  10  toward the normal position. Such a design that both the yarn-changing plate  10  and the movable blade  11  are driven by an identical drive element will bring about the delay of the time that the movable plate  11  cuts off the yarn Y. In such a design that both the yarn-changing plate  10  and the movable blade  11  are driven by an identical drive element, when an old yarn and a new yarn, e.g. a yarn  1  and a yarn  6 , are spaced farther, the time difference between two actions increases because of the larger spacing therebetween, and the time of releasing the yarn Y is too late so that the yarn will be torn off when the tail of the yarn is still clipped by the movable blade  11  and a yarnlet Y 1  will still remain clipped, as shown in  FIG. 1B ; then, the yarnlet Y 1  will be released and tangled with fabric; therefore, fabric quality is degraded. 
   SUMMARY OF THE INVENTION 
   The primary objective of the present invention is to provide a striping apparatus of a circular knitting machine in order to avoid the appearance of yarnlets and improve fabric quality. 
   According to one scheme of the present invention, different cams are separately used to drive the yarn-changing plate and the movable blade, and even though a new yarn and an old yarn are farther spaced, the timings of the cams can be adjusted to rapidly withdraw the old yarn and cut it off and to release the tail of the new yarn from the movable blade before it is torn off. Thereby, the present invention can prevent a yarn from being torn off lest yarnlets appear, so that fabric quality can be improved. 
   The technical contents and preferred embodiments of the present invention are to be described below in detail in cooperation with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  to  FIG. 1D  are schematic views showing the structure of a conventional striping apparatus and the operation of the yarn-changing plate and the movable blade. 
       FIG. 2  is a schematic view showing a preferred embodiment of the striping apparatus of the present invention. 
       FIG. 3  is a schematic view showing a preferred embodiment of the drive unit of the present invention. 
       FIG. 4A  is a schematic view showing the first portion of the yarn-feed unit at the normal position. 
       FIG. 4B  is a schematic view showing the second portion of the yarn-feed unit at the normal holding position. 
       FIG. 5A ,  FIG. 5C ,  FIG. 5E  and  FIG. 5G  are schematic views showing the sequential operational steps of the yarn-changing plate of the striping apparatus of the present invention. 
       FIG. 5B ,  FIG. 5D ,  FIG. 5F  and  FIG. 5H  are schematic views showing the sequential operational steps of the movable blade of the striping apparatus of the present invention. 
       FIG. 6  is a schematic view showing the relative positions of old yarn, new yarn and the yarn-entering point of the knitting needle when yarn is changed. 
       FIG. 7  is a schematic view showing a preferred embodiment of the forward cam of the second cam set of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Refer to  FIG. 2 . According to one preferred embodiment, the striping apparatus of a circular knitting machine of the present invention comprises: a controller  20 , a yarn-feed unit and a drive unit. The controller  20  is driven by a selector  30 , which rotates around the knitting portion of the circular knitting machine. The selector  30  is a kind of electronic device functioning like cams and having multiple movable elements  31 , which are normally non-enable. Under the control of a control circuit or a central computer, the movable elements  31  can move to a triggering position. When the selector  30  passes the nearby of the controller  20 , the movable elements  30  at the triggering position will actuate corresponding triggers  21  of the controller  20  to move to an enable position. 
   The controller  20  further comprises: triggers  21 , first safety levers  22  and second safety levers  23 . One end of the first safety lever  22  and one end of the second safety lever  23  are installed to a sideboard  24  with a first pivotal shaft  221 . The trigger  21  has a first end  210  and a second end  211 ; the first end  210  of the trigger  21  has a protrudent return nose  212 ; the portion between the first end  210  and the second end  211  has a second pivotal shaft  213 , and the triggers  21  are installed to the sideboard  24  with the second pivotal shaft  213 ; and the second end  211  of the triggers  21  also has a protrudent second nose  214 . Refer to  FIG. 4A  and  FIG. 4B . When in normal state, the trigger  21 , the first safety lever  22 , and the second safety lever  23  are all at a lock position; the second end  211  of the trigger  21  presses against the first safety lever  22  and the second safety lever  23 . When the first end  210  of the trigger  21  is moved by an external force, it will rotate around the second pivotal shaft  213  to the enable position, and the second end  211  of the trigger  21  will slide into a notch  220  at the top side of the first lever  22  and a notch  230  at the top side of the second lever  23 , which enables the first lever  22  and the second lever  23  swing around the first pivotal shaft  221  upward to an unlock position. The entire controller  20  comprises multiple units, and each unit is formed of one trigger  21 , one first safety lever  22 , and one second safety lever  23 ; those units are parallel arranged into the entire controller  20 . When in normal state, the relationship between the trigger  21  and the first safety lever  22  of the same unit is shown in  FIG. 4A , and the relationship between the trigger  21  and the second safety lever  22  of the same unit is shown in  FIG. 4B . 
   The yarn-feed unit is fixedly installed in the perimeter of the circular knitting machine and comprises two portions. The first portion further comprises: yarn-changing plates  40 , first connecting rods  41 , and second connecting rods  42 . The first portion functions to feed a yarn Y to a yarn-entering position. The second port further comprises: movable blades  50  and a driving link  51 . The second port functions to clip the tail of the yarn Y when standby and to cut off an old yarn, so that the old yarn can be released from fabric and the operation can restore standby state. The abovementioned controller  20  is fixedly installed above the yarn-feed unit, and the preferred embodiments of them are described below. 
   The yarn-changing plates  40 , first connecting rods  41 , and second connecting rods  42  of the first portion interconnect head to tail to form a kind of three-bar linkage. Multiple different colors of yarns Y separately pass different yarn-guiding rings  25  and then pass the through-holes  401  at the front ends of the yarn-changing plates  40 . When in normal state, the first connecting rod  41  is like a seesaw, and the tail end of the first connecting rod  41  is coupled to the head end of the second connecting end  42 ; the upper side of the central portion of the first connecting rod  41  has a protuberance  412 ; the protuberance  412  contacts the bottom side of the first safety lever  22  normally; the upper side of the head end of the first connecting rod  41  has an upward forward-stroke protuberance  410 , and the bottom side of the head end of the first connecting rod  41  has a downward backward-stroke protuberance  411 . The tail end of the second connecting rod  42  is coupled to the tail end of the yarn-changing plate  40 . The second connecting rod  42  functions to transfer the pulling force of the first connecting rod  41  to the yarn-changing plate  40  and transform the pulling motion of the first connecting rod  41  into a motion of another direction in order to actuate the yarn-changing plate  40  to reciprocate between a normal position (shown in  FIG. 4A ) and an external position (shown in  FIG. 5C ). The first portion further comprises: a first elastic element  43  and a second elastic element  44 ; one end of the first elastic element  43  is fixed to the sideboard  24 , and the other end supports the first connecting rod  41  from the bottom side of the head end of the first connecting rod  41 . As shown in  FIG. 5A , when the trigger  21  shifts to the enable position, the upward pressing force of the first elastic element  43  will push the head end of the first connecting rod  42  upward, and the first safety lever  22  will also move to the unlock position simultaneously, so that the forward-stroke protuberance  410  of the first connecting rod  41  rises above the sideboard  24  to a standby position. The second elastic element  44  supports the yarn-changing plate  40  from the bottom side of the yarn-changing plate  40  in order to complement the first elastic element  43  and provide elastic force for the yarn-changing plate  40 . 
   The tail end of the movable blade  50  is coupled to the tail end of the driving link  51 . The upper side of the central portion of the driving link  51  has a protuberance  512 , which contacts the bottom side of the second safety lever  23  normally. Both sides of the head end of the driving link  51  separately have an upward forward-stroke protuberance  510  and a downward backward-stroke protuberance  511  in order to actuate the movable blade  50  to reciprocate between a normal holding position (shown in  FIG. 4B ) and an external release position (shown in  FIG. 5D ). The second portion further comprises a third elastic element  52 ; one end of the third elastic element  52  is fixed to the sideboard  24 , and the other side supports the driving link  51  from the bottom side near the head end of the driving link  51 . When the trigger  21  shifts to the enable position (shown in  FIG. 5B ), the upward pushing force of the third elastic element  52  will push the head end of the driving link  51  upward, and the second safety lever  23  will also be moved to the unlock position simultaneously, so that the forward-stroke protuberance  510  of the driving link  51  rises above the sideboard  24  to the standby position ready for being pushed out. 
   The drive unit further comprises: a first cam set  60 , a second cam set  70 , and return cams  80 , and as shown in  FIG. 3 , all of them together with the selector  30  are installed to a mount board  90  and rotate around the knitting portion of the circular knitting machine synchronically. The first, second cam sets  60 ,  70  respectively have forward cams  61 ,  71  and backward cams  62 ,  72 . The forward cam  61  of the first cam set  60  is responsible for pushing the yarn-changing plate  40  to the external position; the forward cam  71  of the second cam set  70  is responsible for pushing the movable blade  50  to the external release position; the backward cam  62  of the first cam set  60  is responsible for pulling the yarn-changing plate  40  back to the normal non-enable position; the backward cam  72  of the second cam set  70  is responsible for pulling the movable blade  50  for clipping/cutting yarns back to the normal holding position. When in the holding position, a hook  502  at the front end of the movable blade  50  will clip the tail of the yarn Y to position it at between the hook  502  and the sideboard  24 . 
   The practical operation is to be described below in cooperation with from  FIG. 5A  to  FIG. 5H . 
   Firstly, as shown in  FIG. 5A , the control circuit or the central computer controls a movable element  31  of the selector  30  to move to a triggering position. When the selector  30  passes the nearby of the controller  20 , the movable element  31 , which has reached the triggering position, will trigger the second nose  214  of the corresponding trigger  21 . The second noses  214  of the triggers  21  are respectively at different heights; therefore, different movable elements  31  of the selector  30  can be used to trigger different second noses  214  of the corresponding triggers  21  separately, so that the corresponding triggers  21  move to the enable positions, and then, the first safety levers  22  move to the unlock positions, so that the forward-stroke protuberance  410  of the first connecting rod  41  rises above the sideboard  24  to the standby position ready for being pushed out. Simultaneously, as shown in  FIG. 5B , the forward-stroke protuberance  510  also rises above the sideboard  24  to the standby position ready for being pushed out. 
   Next, as shown in  FIG. 5C , the drive unit moves to the yarn-feed unit, and a first inclined plane  610  of the forward cam  61  of the first cam set  60  touches the forward-stroke protuberance  410  of the first connecting rod  41  to actuate the first connecting rod  41  and the second connecting rod  42  to push the yarn-changing plate  40  to the external position. Further, as shown in  FIG. 5D , a first inclined plane  710  of the forward cam  71  of the second cam set  70  touches the forward-stroke protuberance  510  of the driving link  51  to actuate the movable blade  50  to the external release position. 
   As shown in  FIG. 5E , the return cam  80  moves to the controller  20  again, and the front inclined plane  801  of the return cam  80  gradually closes to the return nose  212  of the trigger  21 , and the rear plane  802  of the return cam  80  pushes the trigger  21  to the normal lock position to actuate the backward-stroke protuberance  411  of the first connecting rod  41  to emerge from below the sideboard  24 . Simultaneously, as shown in  FIG. 5F , the backward-stroke protuberance  511  of the driving link  51  also emerges from below the sideboard  24 . 
   Lastly, as shown in  FIG. 5G , the drive unit moves to the yarn-feed unit again, and the first inclined plane  620  of the backward cam  62  of the first cam set  60  touches the backward-stroke protuberance  411  of the first connecting rod  41  to actuate the first connecting rod  41  and the second connecting rod  42  to pull the yarn-changing plate  40  back to the normal non-enable position. Further, as shown in  FIG. 5H , the first inclined plane  720  of the backward cam  72  of the second cam set  70  also touches the backward-stroke protuberance  511  of the driving link  51  to actuate the driving link  51  to pull the movable blade  50  back to the normal holding position; at this time, the hook  502  at the front end of the movable blade  50  for clipping/cutting yarns will not only clip the tail of the yarn Y to position it at between the hook  502  and the sideboard  24  but also will cut off the yarn Y. 
   The time difference between the action of the backward cam  62  of the first cam set  60  and the action of the backward cam  72  of the second cam set  70 , i.e. the time difference between that the first inclined plane  620  touches the backward-stroke protuberance  411  and that the first inclined plane  720  touches the backward-stroke protuberance  511 , can be adjusted according to demand. A practical method is installing the backward cams  62 ,  72  separately at cam seats  63 ,  64 ; such a design can make an old yarn be quickly withdrawn and cut off when striping (changing a yarn) and make the tail of a new yarn be released from the movable blade  50  before the new yarn is torn off lest the yarn be torn off and yarnlets appear; thereby, fabric quality can be improved. 
   A preferred embodiment of the forward cam  71  of the second cam set  70  show in  FIG. 3  is a two-stage cam, which further comprises: a static cam  73  and a movable cam  74 , wherein the first inclined plane  710  is positioned at the front end of the static cam  73 , and the movable cam  74  further has a second inclined plane  730 . The static cam  73  and the movable cam  74  are separately positioned at different heights. The movable cam  74  is fixed to the forward cam  71  with a screw  741 , and after the screw  741  is loosened, the relative position of the movable cam  74  and the static cam  73  can be adjusted. The abovementioned forward-stroke protuberances of the multiple driving links of the yarn-feed unit are also divided into two kinds of forward-stroke protuberances  510 ,  510   a , and the forward-stroke protuberance  510  can be pushed by the first inclined plane  710  of the static cam  73 , and the forward-stroke protuberance  510   a  can be pushed by the second inclined plane  730  of the movable cam  74 . 
   Refer to  FIG. 6 , wherein the present invention is exemplified by a six-color striping apparatus. Suppose that the old yarn is the yarn  6  and the new yarn is the yarn  1  herein; when the knitting needle moves to the yarn-entering point shown in  FIG. 6 , the movable cam  74  can be moved forward to advance the timing that the second inclined plane  730  touches the backward protuberance  511  from time t 1  to time t 2  shown in  FIG. 7  lest the old yarn be released by the movable blade  50  too late and the old yarn be torn off.