| 摘要 |
Disclosed is a bobbin for a sewing machine, in which an under thread is continuously and stably pulled out without entanglement or cut of the under thread. The bobbin comprising a winding shaft 10 which is separatably inserted onto a fixing shaft of the rotary shuttle device and on which the under thread is substantially wound, a first flange 12 which is integrally formed at one end of the winding shaft 10, a second flange 14 which is integrally formed at the other end of the winding shaft 10 and a partition flange 16 for forming a first winding portion 18 between the first flange 12 and the partition flange 16 and a second winding portion between the second flange 14 and the partition flange 16, characterized in that a plurality of trough portions 22 and ridge portions 24 are alternately formed at an entire outer circumference of the partition flange 16, each of the trough portions 22 and the ridge portions 24 has the same gradient each other, and a side portion 22a is formed at both sides of each trough portion 22 to prevent the under thread from being previously slipped.
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