PURPOSE: To enhance machining accuracy, when titanium or titanium alloy and steel are cut in a combined condition, by setting the ratio of the hardness of steel to that of titanium or titanium alloy within a prescribed percentage range in HV value, and by carrying out cutting in such a condition that built-up edges are not produced in the single cutting of steel.
CONSTITUTION: When a joined cylinder 1 made up of a titanium or titanium alloy half-cylinder 2 and a steel half-cylinder 3 is cut, the hardness of steel in HV value is set to be within ±20% of that of titanium or titanium alloy. And, the cutting is carried out in such a condition that built-up edges are not produced in the cutting of steel. Thus, the formation of stepped difference in the joined parts of both half-cylinders 2, 3 can be prevented, and roundness can be enhanced.
NAKAMURA SADAYUKI
KURATOMI HIDEAKI
HOUKIDA TAKESHI
NISSAN MOTOR