MAQUINA DE COSTURA DE PONTO DE CORRENTE DUPLA

A double chain stitch sewing machine having a feeding device with a feed dog oscillatingly movable in and opposite to the feeding direction for producing a relative movement between a workpiece and the sewing machine. It has a needle reciprocatingly driven by a crank mechanism, at which the feeding mechanism also imparts synchronous jogging movements to the needle in order to generate a needle feed movement. The reciprocatingly and joggingly driven needle cooperates with a looper oscillatingly driven by a looper drive mechanism in parallel with the feeding direction. The looper drive mechanism is formed as a six-bar-linkage-mechanism provided at the input with a stationary pivot and at the output with a stationary pivot and provided with an intermediate pivot. The looper is oscillatingly swung at a relative high velocity from one extreme position to the other at an input motion with constant angular velocity and the looper is moved with a short period of dwell in that extreme position located in the feeding direction and moved with long period of dwell in that extreme position located oppositely to the feeding direction.