Patent ID: 7074285

Claim:
A method of manufacturing a high-speed tool steel gear cutting tool, the method comprising: rough processing a tool material comprising high-speed tool steel into a rough shape corresponding to a final shape of a gear cutting tool; heating the tool material being in said rough shape to a predetermined temperature prior to quenching; quenching the tool material, being in said rough shape and comprising high-speed tool steel, to transform a structure of said tool material into martensite; tempering said tool material being in said rough shape after quenching to transform any residual austenite dispersively distributed throughout a matrix of said martensite structure formed by the quenching, into martensite; and finishing said tool material after tempering to have the final shape of the gear cutting tool, wherein said tool material after quenching is subjected to sub-zero treatment involving cooling and holding at a temperature below âˆ’150Â° C. for a period of time within a range of more than 1 hour to 5 hours, and transforming residual austenite which is dispersively distributed throughout the matrix into martensite, to thereby transform the structure of said tool material after tempering into a structure in which residual austenite which is a starting point for chipping at the time of high-speed gear cutting does not exist in the matrix of said martensite.