| 摘要 |
PURPOSE: To smooth fitting of an inner sleeve without damaging any function in a molten metal plated pin tale by setting a ridge angle of the pin tale smaller than a root angle of the inner sleeve in a fastening device. CONSTITUTION: A pin tail 4 in which ridges and roots are alternately formed so as to provide a dodecagon, and a pin tail material 4a is molded by drawing before molten zinc plating. In the pin tail material 4a, a ridge angleθ2 is less than 120 degrees, while a root angle is less than 150 degrees. As the ridge angle of the pin tail 4 is set smaller than the root angle of an inner sleeve, such a function of the pin tail that takes reaction force of fastening torque to the pin tail and controls fastening torque is not damaged when molten metal plating is applied on it, so that fitting of the inner sleeve to the pin tail can be smoothly carried out. Even when molten metal plating is not carried out, no function of the pin tail is damaged, and improvement in a yield, lightening in weight, and improvement of fastening workability can be accomplished.
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