| 摘要 |
PROBLEM TO BE SOLVED: To obtain a bobbin which is easily assembled and is suitable for injection molding by providing a base part, a spiral groove part along which a helical element is wound, an attaching part which is formed in the lower end of the base part and is engaged with a sleeve, and plural projecting parts formed in the upper face part of the base part. SOLUTION: With respect to a bobbin 1, a pair of projecting parts 5 and 5 are formed in the upper face part of a columnar base part 19. A spiral groove part 12 having a certain pitch is formed on the side face of the bobbin 1, and an attaching part 13 provided with a male screw 13a on the outer periphery is provided in the lower part. This spiral groove part 12 is formed on the surface of the base part 19, and the helical element is wound along it. These projecting parts 5 and 5 are formed symmetrically with respect to the center line of the upper face part of the bobbin 1. Each projecting part is a projection which is surrounded with an arc part 26 and a chord part 27 and has an arcuate section, and a groove part 10 is formed between chord parts 27. The outer periphery of the upper part of the arc part 26 of each projecting part 5 is expanded outward a little.
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