| 摘要 |
PURPOSE:To reduce working costs and material costs by using a sintered hard alloy of a composite sintered hard alloy only for the required working surface of the tool and using a steel material for the rest. CONSTITUTION:A cast iron ring 2 having a required wall thickness t1 on an outside circumferential side 21 on the basis of its inside circumference is press fitted into the inside circumference 11 of a sintered hard alloy 1 having a prescrbied effective wall thickness (t) and an outside diameter D. A steel material 3 of a circular columnar shape or a cylindrical shape having an outside circumference 31 formed to a large diameter on the basis of the inside circumference 22 of the ring 2 is immersed in a low temp. tank and is allowed to shrink by a prescribed rate; thereafter said material is fitted into the inside circumference 22 of the ring 2 and is heated up to an ordinary temp., whereby the ring 1, the ring 2 and the material 3 are made into one body. The composite sintered hard alloy A made into one body is heated in a heating furnace of a reducing or neutral atmosphere or a vacuum in order to prevent the acceleration of oxidation, whereby the cast iron is diffused mutually into the ring 1 on the outside circumferential side and the material 3 on the inside circumferential side and is firmly fixed. |
