抄録
It was shown in a previous paper that the temperature of needle had a tendency to exceed the melting point of synthetic sewing thread while the sewing machine was in high speed sewing operation. It is considered that the reduction of needle temperature in sewing operation is one of the means to make a high speed sewing operation with synthetic thread possible and that the improvement of needle quality is one of the means to reduce needle temperature in high speed sewing operation.
The purpose of the present paper is to examine experimentally the effect of the improvement of needle quality. The influences of surface roughness, materials and shapes of the needle upon the needle temperature are measured. The results of experiment are as follows :
(1) Rough surface needle raises its temperature higher than smooth surface needle.
(2) In rising ratio of temperature, copper-beryllium alloy needle shows about 30% less than steel needle.
(3) Triangular point needle shows the minimum rising of needle temperature among five kinds of needle points.
(4) The needle manufactured for trial shows the minimumrising of temperature among six kinds of needle shanks.
