家庭用ミシンの上糸張力と上糸送出し量の同時測定
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概要
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A home sewing machine has been fitted with a quartz transducer and a rotary angular meter to determine the needle thread tension and feed length of the thread simultaneously during sewing operation at 50∼1 000 rpm. A quartz transducer with high reasonant frequency of 27 KHz has been placed between the needle hole and the eye of the thread take up lever. A rotary angular meter, on the other hand, has been placed between the spool pin and the thread guide on the face plate.<BR>The tension and feed length of the neele thread are, at first, transformed into electrical signals by the above two devices. The signals are then amplified and recorded by a 3-pen type recorder at low sewing speed and a 2-channel type memory oscilloscope at high sewing speed.<BR>Curves showing the relationship between the needle thread tension and needle thread supply have ravealed that a stitch is formed at the earlier period of the rising motion of the thread take up lever. Then, a stitch is tightened at the later period. The needle thread supply begins at the highest rising position of the lever.<BR>The time required for the supply of a needle thread is slightly dependent on mechanical properties of a sewing thread and a fabric feed length but the beginning time of the supply of needle thread is independent on the sewing speed. Therefore, if the revolutional speed of the shaft increases, the ratio also increases of the time required for the supply of needle thread to the time required for one' revolution of the arm shaft. Thus, the finishing time of the needle thread supply gets nearer to the beginning time of the next sewing cycle as the sewing speed increases. So, an adequate balance between tension of the thread take up spring and degree of the needle thread tension regulation is important in high speed sewing operation.
- 社団法人 日本繊維機械学会の論文