| 摘要 |
PURPOSE:To decrease the residual stress before a subzero treatment and to prevent fracture occurring in the material defect during the subzero treatment by heating inductively the inside of a hardened roll while maintaining the surface of said roll at <=50 deg.C with water. CONSTITUTION:The surface of a roll right after hardening is strongly cooled with shower water from a shower device 2. Electric current of 1,060-50Hz frequency is then impressed to an inductor 3 to heat gradually and inductively the roll. Only the part where the residual stress near 40-100mm. below the surface is tensile stress is heated while the tempering of the roll 1 surface is prevented to decrease the tensile stress. The fracture occurring in the material defect during the subzero treatment is thus prevented. |
