This paper describes the relationship between the stitch tightening and the compressional property of seamed fabrics in a lock stitch sewing machine with an experimental and theoretical investigation. The results are as follows:
(1) The following equation has been derived from the previous equation on the stitch tightening on the besis of the cross section of the fabric under the seam.
S.T. (area) (%) =P
0/Ka
0h
0×100
where,
T0: sewing thread tension at the end of boundary sectional area of fabrics,
P0: vertical component of T
0,
K: elastic constant of fabric compression,
2h0: thickness of fabric to be sewn,
2a0: length of stitch zone
(2) The following equation has been derived on the relation between the stitch tightening and the compressional strain on the fabric at the center of stitch.
S.T. (area) (%) =sinhΔ/Δ×h
0-y
0/h
0×100
where, Δ=√K/F
0×a
02y0: thickness of fabric at the center of stitch,
F0: horizontal component of
T0(3) By comparison of the experiment on some fabrics, it was found that the value of parameter Δ was 0.7-0.9 and the results agreed well the theoretical ones in regard to thick fabrics.
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