JPS56130408A - Finish working method for metal-made parts - Google Patents

Abstract

PURPOSE: To improve the dimensional accuracy of metal-made parts by providing blades similar to those of the broach of cutting tools on the surface of dies for sizing thereby performing cutting and sizing in one process.

CONSTITUTION: When a sintered body 5 which is the work is pressed between upper and lower punches 2, 3, the inside surface of the body 5 contacts the projecting land parts 42 of a core rod 4 owing to plastic deformation and partly enters the inside of recesses 41. At the time when these entered parts are extruded upward of an outer die 1 by the lower punch 3, they are cut by broachlike blades 42, and the cutting swarf accumulates in the space parts of the recesses 41. In this case, the contact area with the core rod 4 where internal stress is maximum is limited to the area in contact with the land parts 42, and the parts entered to the recesses 41 are free surfaces, hence the internal stress is less and this results in decreased magnitude of the entire internal stress. Consequently, the spring back after the extrusion decreases and the cutting effect by the broach at the extruding adds to considerably improve dimensional accuracy.

COPYRIGHT: (C)1981,JPO&Japio