Device and method for thread drawing

Abstract

A thread drawing device includes a drive assembly which includes a drive wheel that has a working platform for supporting a thread, the thread has a fixed end fixed on an object and a movable end carried by a tool. The thread drawing device includes a pressing assembly which includes a pressing member configured to move between a first position at which the pressing member engages the working platform to clamp the thread to be pulled therebetween and a second position at which the pressing member disengages from the working platform to release the thread to be pulled. The thread drawing device includes a motor configured to rotate the drive wheel when the pressing member is at the first position so as to move a loose part of the thread at the fixed end from the fixed end to the movable end.

1 . A thread drawing device comprising:
 a drive assembly, wherein the drive assembly includes:
 a drive wheel, wherein the drive wheel includes:
 a working platform for supporting a thread, wherein the thread includes:
 a fixed end fixed on an object, and 
 a movable end carried by a tool; 
 
 
   a pressing assembly, wherein the pressing assembly includes:
 a pressing member configured to move between
 a first position at which the pressing member engages the working platform to clamp the thread to be pulled therebetween, and 
 a second position at which the pressing member disengages from the working platform to release the thread to be pulled; and 
 
   a motor configured to rotate the drive wheel when the pressing member is at the first position so as to move a loose part of the thread at the fixed end from the fixed end to the movable end.   
     
     
         2 . The device according to  claim 1 , wherein the thread is moved from the fixed end to the movable end by a static friction force generated by a pressing force exerted by the pressing member. 
     
     
         3 . The device according to  claim 1 , wherein the thread is caused to slide when a drawing force acting upon the thread exceeds a threshold indicative of that the loose part of the thread at the fixed end has been tensioned. 
     
     
         4 . The device according to  claim 1 , further comprising an actuator for moving the pressing assembly having a piston, wherein the piston is coupled to the pressing assembly and the actuator is configured to linearly move the piston so as to move the pressing assembly. 
     
     
         5 . The device according to  claim 4 , further comprising a frame for supporting the actuator, wherein the frame defines a guide rail for guiding a movement of the pressing assembly. 
     
     
         6 . The device according to  claim 1 , wherein the pressing assembly comprises:
 a base for supporting the pressing member; and   a spring arranged between the base and the piston for elastically supporting the pressing member.   
     
     
         7 . The device according to  claim 6 , wherein the pressing assembly further comprises:
 an adjustment plate coupled to the piston; and   a screw rod fixed to the base,
 wherein the spring is arranged between the base and the adjustment plate, and an elastic force of the spring is adjustable by adjusting a position of the adjustment plate along the screw rod with respect to the base so as to be able to adjust a pressure applied onto the thread. 
   
     
     
         8 . The device according to  claim 6 , wherein the pressing member is in a form of a roller which is rotatable with respect to the base. 
     
     
         9 . The device according to  claim 1 , wherein the working platform comprises a circumferential groove for receiving the thread. 
     
     
         10 . The device according to  claim 9 , wherein the circumferential groove comprises a V-shape with a first guide angle. 
     
     
         11 . The device according to  claim 10 , wherein the pressing member comprises a convex shape with a second guide angle receivable by circumferential groove, the first guide angle being equal to or larger than the second guide angle. 
     
     
         12 . The device according to  claim 11 , wherein a tip of the convex shape is rounded to define a clearance with respect to the working platform for housing the thread. 
     
     
         13 . The device according to  claim 1 , wherein a material of a surface of the pressing member is different from a material of a surface of the working platform. 
     
     
         14 . A robot system for sewing, comprising the thread drawing device of  claim 1 . 
     
     
         15 . A thread drawing method comprising:
 moving, after a thread being placed on a working platform of a thread drawing device, a pressing member to a first position at which the pressing member engages the working platform to clamp the thread to be pulled therebetween, the thread comprising a fixed end fixed on an object and a movable end carried by a tool;   rotating the working platform to move a loose part of the thread at the fixed end from the fixed end to the movable end;   causing the thread to slide when a drawing force acting upon the thread exceeds a threshold indicative of that the loose part of the thread at the fixed end has been tensioned; and   moving the pressing member to a second position at which the pressing member disengages from the working platform.   
     
     
         16 . The device according to  claim 2 , wherein the pressing assembly comprises:
 a base for supporting the pressing member; and   a spring arranged between the base and the piston for elastically supporting the pressing member.   
     
     
         17 . The device according to  claim 3 , wherein the pressing assembly comprises:
 a base for supporting the pressing member; and   a spring arranged between the base and the piston for elastically supporting the pressing member.   
     
     
         18 . The device according to  claim 4 , wherein the pressing assembly comprises:
 a base for supporting the pressing member; and   a spring arranged between the base and the piston for elastically supporting the pressing member.   
     
     
         19 . The device according to  claim 5 , wherein the pressing assembly comprises:
 a base for supporting the pressing member; and   a spring arranged between the base and the piston for elastically supporting the pressing member.   
     
     
         20 . The device according to  claim 2 , wherein the working platform comprises a circumferential groove for receiving the thread.