Analysis on Tightening Tension Wave in A Lockstitch Sewing Machine

In sewing with a single-needle lockstitch sewing machine, the tightening tension wave generated in the needle thread affects evidently the tightening situation of stitches. An attempt was made to clarify the basic mechanism of generation of the tightening tension wave by a computer simulation. This study consists of two parts. This paper is the first of them. In the present paper, a method of computer simulation is proposed for the analysis of the tightening tension wave at a very low sewing speed. The outline of this method is as follows: A simulation was done by using a simplified model for sewing mechanism. The calculation of tension in the model is based on the law of elasticity, where the calculation is classified into the following two cases in terms of effect of friction of the thread take-up lever thread eyelet ; 1) the thread take-up lever thread eyelet behaves as a fixed end at which the needle thread does not move due to the friction and 2) the needle thread moves being subjected to the friction.