METHOD AND APPARATUS FOR DETECTING IMPROPER STITCHES FOR A CHAINSTITCH SEWING MACHINE

摘要

The invention is a method and apparatus for detecting an improper stitch for a Class 400 chainstitch sewing machine (30). A monitor assembly (80) determines the consumption per stitch of the looper thread during the formation of the chainstitches. A processor (84) identifies times when the monitored consumption is indicative of looper thread consumption per stitch below a predetermined threshold value. Since the consumption per stitch for looper thread is nominally a predetermined multiple of the stitch length, those indentified times correspond to times when improper stitches have occured.