Chain-stitch sewing machine

Abstract

Chain-stitch sewing machine includes: a looper provided under a needle plate and having a thread lead-in port and thread lead-out port, the looper being rotationally driven in synchronism with a sewing operation; a plurality of thread feed ports connecting to different thread supply sources; and a connecting member having a thread passage, the connecting member selectively connecting any one of the plurality of thread feed ports to the thread insertion port of the looper via the thread passage. Threading mechanism passes the sewing thread, fed via the thread feed port connected by the connecting member to the thread insertion port of the looper, into the thread insertion port and causes the sewing thread to be taken out via the inserted thread lead-out port of the looper.

1 . A chain-stitch sewing machine comprising:
 a reciprocatively-driven hook needle;   a looper disposed under a needle plate and having a thread lead-in port and thread lead-out port, said looper being rotationally driven in synchronism with a sewing operation;   a plurality of thread feed ports connecting to different thread supply sources:   a connecting member having a thread passage, said connecting member selectively connecting any one of said plurality of thread feed ports to the thread insertion port of said looper via the thread passage; and   a threading mechanism for passing the sewing thread, fed via the thread feed port connected via said connecting member to the thread insertion port of said looper, into the thread insertion port and causing the inserted sewing thread to be taken out via the thread lead-out port of said looper.   
   
   
       2 . A chain-stitch sewing machine as claimed in  claim 1  wherein said connecting member is selectively movable to align an inlet of the thread passage with any one of said plurality of thread feed ports. 
   
   
       3 . A chain-stitch sewing machine as claimed in  claim 1  wherein said plurality of thread feed ports are arranged in a circular configuration, and any one of said plurality of thread feed ports is aligned with the inlet of the thread passage by pivoting movement of said connecting member along the circular configuration. 
   
   
       4 . A chain-stitch sewing machine as claimed in  claim 1  wherein said plurality of thread feed ports are arranged in a linear configuration, and any one of said plurality of thread feed ports is aligned with the inlet of the thread passage by movement of said connecting member along the linear configuration. 
   
   
       5 . A chain-stitch sewing machine as claimed in  claim 1  wherein said threading mechanism pushes the sewing thread out to the thread lead-out port by an air jet force. 
   
   
       6 . A chain-stitch sewing machine as claimed in  claim 1  wherein said plurality of thread feed ports are provided in a bracket, and which further comprises thread guide means extending from the thread supply sources, corresponding to the thread feed ports, to the bracket. 
   
   
       7 . A chain-stitch sewing machine as claimed in  claim 6  wherein said plurality of thread feed ports are densely arranged in the bracket. 
   
   
       8 . A chain-stitch sewing machine as claimed in  claim 1  wherein said looper is positioned inside a sewing workpiece. 
   
   
       9 . A chain-stitch sewing machine comprising:
 a reciprocatively-driven hook needle;   a looper disposed under a needle plate and having a thread lead-in port and thread lead-out port, said looper being rotationally driven in synchronism with a sewing operation;   a plurality of thread feed ports arranged in a circular configuration;   a selection device for selectively connecting any one of said plurality of thread feed ports to the thread insertion port of said looper; and   a threading mechanism for passing a sewing thread, fed via the thread feed port connected via said selection device to the thread insertion port of said looper, into the thread insertion port and causing the inserted sewing thread to be taken out via the thread lead-out port of said looper,   wherein the sewing thread taken out via the thread lead-out port is rotated in response to rotation of said looper so that chain-stitch sewing is performed through cooperation between said looper and said hook needle.