| 摘要 |
PROBLEM TO BE SOLVED: To eliminate deburring work and to reduce cost by preventing an adverse effect due to an excess metal and performing burr-free work. SOLUTION: A method consists of a process to blank a slit hole 3 to a work 1 at the position one size larger than a product external periphery, a process to hold the work having the blanked slit hole 3 with a movable first punch 8 having an external shape larger than the external periphery of the product but being inside the slit hole 3, a first die 6 having an inside shape equal to a product external shape and a first knock out 7 movably arranged in the die 6 and to extrude the work roughly into a half of its thickness with the punch 8, and a process to subject the extruded work to return blanking.
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