A Seam Ravel Preventing Apparatus

Abstract

A looper thread hanging hook (4) for catching a looper thread near the advance end of a looper (l) when advancing to a left forward direction is arranged on the right rear side of a needle drop position, and a thread cutting hook (3) that performs an advance and retreat operation in substantially the same direction as the looper (1) is arranged on the right side of the needle drop position. The looper (1) is brought into an advance state at the end of sewing, and the looper thread hanging hook (4) is forced to advance and retreat to catch a looper thread (7) running to the rear side of the looper (1) and hold it on the rear side of the needle drop position. After performing sewing for one stitch in this state, the thread cutting hook (3) is forced to advance and retreat to catch the looper thread (7) running to the rear side of the looper (l) with a first hold section (31) at the tip and catch needle threads (6a, 6b) and the looper thread (7) held by the looper thread hanging hook (4) with a second hook section (32) in the middle, and then these threads are collectively cut by bringing them into slide-contact with a thread cutting knife (30).