| 摘要 |
PURPOSE:To prevent the generation of a chip by tapping and to improve the efficiency in working by performing a burring by forming a work with its projection to the opposite side in beveling after performing the beveling on the prepared hole periphery of the back face of a burring scheduled face as well as performing the prepared hold piercing on the work. CONSTITUTION:The punch head 13 allowing the ram of a press to strike is equipped at the apex part of a punch body 11, a punch 15 is provided at the lower end and a punch guide 17 is provided around the punch body. A die 23 is provided at the lower part of the work W opposing to the punch 15 and an annular ejector plate 23 is provided via a spring 27 at the upper part of the die 23. The die hole 29 cooperating with the punch 15 is provided by its serving as a punch residues discharging path as well at the center of the die 23 and the beveling punch 31 projecting in a truncated conical shape around the die hole 29 is provided. In case of working the work W is located on an ejector 25. When the ram of a punch press reaches a lower dead center, the ejector 25 is abutted to the outer peripheral part of the die 23, the punch 15 penetreates the work W and the work W is subjected to a beveling between the punch guide 17 and beveling punch 31.
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