To provide a manufacturing method of a core of an extruding die capable of prolonging the lifetime of the core of the extruding die formed by the electric discharge process.
A male die 4 for forming a hollow part in a flat perforated tube has a core 21 having a plurality of comb-shaped hollow forming parts 24 and a die 22 for holding the core. In the manufacturing method of the core 21 of an extruding die which is composed of the male die 4 and a female die 3 for forming an outer circumferential part of the flat perforated tube and used for extruding the flat perforated tube, the core 21 is formed by cutting an original disk for die in a predetermined shape by the electric discharge process, and removing a discharge-deteriorated layer formed on a machining surface by the grinding.
YAMAMOTO ISAO
Hisayoshi Shimizu
Ken Takada
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