| 摘要 |
PURPOSE: A method for forming a pipe-shaped fixing hole of a base plate is provided to prevent breakage or damage of the lower edge of a fixing hole by extending the bottom simultaneously in drawing of the fixing hole. CONSTITUTION: A method for forming a pipe-shaped fixing hole of a base plate comprises the steps of: placing a base plate(100) in a lower die with a drawing groove(32b), lowering an upper die with a drawing core to form pipe-shaped fixing grooves(110',110") protruding downward in the base plate, driving a piercing punch formed in the upper die into the fixing grooves to form a pipe-shaped fixing hole(110) by removing the bottom of the fixing grooves, and tapping the inner periphery of the fixing hole to form a tap for coupling of a fixing bolt. |
