| 摘要 |
In a process and device for monitoring a residual amount of hook thread in a double thread lockstitch sewing machine, a bobbin is used, which is divided into a large clamber and a small chamber due to the arrangement of a middle flange, wherein the small chamber accommodates the residual amount of thread. An abrupt reduction in the speed of rotation of the bobbin, nS, takes place dating sewing at the time of the transition from the principal to the residual amount of thread as a consequence of the abrupt change in the thread pull-off site in the bobbin. The jump (abrupt change) in the speed of rotation is measured and is processed info a display signal
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