US 5,293,766 AGranted

Method for making slender seamless steel mold

OwnerFu-Hsing Changinventor

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Abstract

A method for making slender seamless steel mold is disclosed, wherein the outer surface of a solid slender male mold is first chased with concave and convex stripes. Then, the male mold is hardened and fitted into a hollow female mold which has not been gone through hardening process. Thereafter, a hydraulic pressure is exerted onto the outer surface of the female mold so as to impress the concave and convex of the male mold onto the inner surface of the female mold. Then the male mold is annealed and drilled with a longitudinal through hole. At least three longitudinal slits are cut on the wall of the through hole in an outward direction. Finally, the male and female molds are together heat-treated and put into water with normal temperature in order to create fissures at the slit portions of the male mold and crack the male mold into pieces. Consequently, a slender seamless steel mold having inner surface formed with concave and convex stripes is completely made.

Claims8

Dependent claims

A method for making slender seamless steel mold, comprising the following steps:

(a) chasing an outer surface of a solid slender male mold with required stripes and then heat-treating and hardening said male mold to a required hardness;
(b) fitting said male mold into a hollow slender female mold which has an outer surface and an inner surface having an inner diameter corresponding to the outer diameter of said male mold;
(c) exerting a hydraulic pressure onto the outer surface of said female mold which is fitted with said male mold so as to impress the stripes of the outer surface of said male mold onto the inner surface of said female mold;
(d) heating said fitted male and female molds to an anneal temperature and then making the same cool naturally and thereafter drilling a longitudinal through hole the length of said male mold, thus defining a wall of said male mold having an inner surface;
(e) cutting at least three longitudinal slits on the inner surface of said male mold, the depth of each of said slits being smaller than the thickness of the wall of said male mold;
and
(f) again heat-treating and hardening said male mold and making the wall sections near said slits of said male mold deform and crack into pieces, the pieces of said male mold being removed from said female mold to expose up the stripes impressed on the inner surface of said female mold by said male mold.

4 more elements

Dependencies are inferred from the claim text.