| 摘要 |
PROBLEM TO BE SOLVED: To provide a press working method capable of minimizing shoulder sagging on the face side of a work piece with a burring area on its hole edge, and properly forming a circular burring area on the back side when punching out the work piece from a plate material. SOLUTION: In a first press work process, a first punch makes a hole 11 in the plate material (work W) and also forms a nearly-tapered circular seat 12 with its two faces tilted from the circumference of the hole 11 outwards in a radial direction (range A). In a second process, a second punch depresses the circular seat 12 to form a circular smooth seat face 13 on the face side of the work W as well as forming a circular burring area 15 protruding from the circumference of the hole 11 on the back side (range B). Then in a third process, the plate material is cut off along the circumference of the work piece outline to punch out the work piece from the work W, forming, for example, a flange 40 (range D). COPYRIGHT: (C)2003,JPO
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