Thread positioner of double chain stitch and sewing machine having thread positioner

Abstract

A thread positioner provided on a needle plate of a double chain stitch sewing machine for forming a seam by a plurality of needle threads and a looper thread, wherein the thread positioner includes a needle thread holding plate provided below the needle plate 30, the needle thread holding plate extending horizontally from a front to a rear, a rear end portion of the needle thread holding plate includes: a guide portion for guiding the plurality of needle threads; and a thread positioning portion for regulating a movement of the plurality of needle threads in a right-and-left direction, and the thread positioning portion includes: a protrusion linearly protruded rearward from the guide portion; flat portions formed on left and right side surfaces of the protrusion; and an inclined portion formed on a tip of the protrusion, the inclined portion being inclined from a right to a rear left.

What is claimed is: 
     
         1 . A thread positioner provided on a needle plate of a double chain stitch sewing machine for forming a seam by a plurality of needle threads and a looper thread, wherein
 the thread positioner includes a needle thread holding plate provided below the needle plate, the needle thread holding plate extending horizontally from a front to a rear,   a rear end portion of the needle thread holding plate includes:
 a guide portion for guiding the plurality of needle threads; and 
 a thread positioning portion for regulating a movement of the plurality of needle threads in a right-and-left direction, and 
   the thread positioning portion includes:
 a protrusion linearly protruded rearward from the guide portion; 
 flat portions formed on left and right side surfaces of the protrusion; and 
 an inclined portion formed on a tip of the protrusion, the inclined portion being inclined from a right to a rear left. 
   
     
     
         2 . The thread positioner of the double chain stitch sewing machine according to  claim 1 , wherein
 a lower surface of the protrusion of the thread positioning portion is inclined downward from the tip.   
     
     
         3 . The thread positioner of the double chain stitch sewing machine according to  claim 1 , wherein
 the thread positioning portion is protruded from the needle thread holding plate while an upper surface of the protrusion is inclined upward from the tip.   
     
     
         4 . The thread positioner of the double chain stitch sewing machine according to  claim 1 , wherein
 the thread positioning portion includes:
 a fixed thread positioning portion fixed to the needle thread holding plate; and 
 a slide thread positioning portion which is retractable in a front-rear direction from a lower portion of the fixed thread positioning portion in accordance with an operation of the double chain stitch sewing machine. 
   
     
     
         5 . A double chain stitch sewing machine having the thread positioner according to  claim 1 .