| 摘要 |
PURPOSE:To prevent a stepped roll from being deformed without the hardness of a hard layer being lowered, by setting the annealing temperature of a stepped roll to be plated with Ni-P composite platings to a value in a range from 250 to 500deg. C after high-frequency hardening, and by setting the hardening heat treatment temperature of the stepped roll after the plating to a value which is lower than the above- mentioned temperature by about 150deg. CONSTITUTION:A stepped roll to be plated with composite platings using an Ni-P matrix, is produced by a process comprising an angle-roughening step 11 for a roll material 10, a high frequency hardening step 12, an annealing step 23, an angle finish- polishing step 14, an Ni-P composite plating step 17 for the angle surface of the material, a hardening heat treatment step 28 and inspection and the like steps 16. In this arrangement, the annealing temperature is set to 250 to 500deg. C during the annealing step, and the hardening heat treatment temperature is set to a temperature equal to the annealing temperature or higher than that by about 150deg. C. As a result, the effect of the hardening heat treatment is not altered so that the hardness of the roll does not lower while the generation of run-out may be restrained below 20mu, and therefore, no polishing step for correction may be required, thereby it is possible to reduce the number of steps and to prolong the life of the stepped roll due to avoiding reducing the thickness of the Ni-P composite plating layer.
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