MOVING HARDENING METHOD OF INSIDE SURFACE OF CYLINDRICAL BODY

摘要

PURPOSE:To finish a cylindrical body to the bore uniform over the entire length in the stage of hardening the inside surface of the cylindrical body by applying the circumferential restraining force decreasing gradually from the end face side where hardening begins to the end face side where hardening ends over the entire length in the longitudinal direction of the outside circumference of the cylindrical body. CONSTITUTION:Plural pieces of prescribed taper rollers 4 having the diameter decreasing toward upward are freely rotatably erected in the prescribed positions of a rotary table 2. The cylindrical body W is pushed between such rollers 4 and is imposed on the table 2. The roller groups 4 are kept rotated as well when the body W is rotated by rotating the table 2 with a driving roller 22. A heating coil C and a cooling jacket J are then moved upward and are moved successively from the lower end face side toward the upper end face side in the body W by which the cylindrical body is successively hardened. The expansion of the cylindrical wall heated in this stage is adequately controlled by the roller groups 4 on the outside circumference and therefore the hardened layer of the inside surface is finished approximately uniformly.