| 摘要 |
PURPOSE:To prevent positively the heterogeneity, quenching cracks, etc. in the various sections at the section of a shape steel that arise during the hardening process of the shape steel or after the hardening by changing the flow rate of the cooling medium to be injected toward the circumference of the material to be treated in the sectional or/and longitudinal direction of the material in accordance with the shape of the material in heat treating said material. CONSTITUTION:A shape steel which is a material to be treated is charged from a charging table 1 into a furnace body 10, and the heating pattern corresponding to the sectional shape of the material to be heated is obtained by changing the feed speed thereof. The inside of the section of the shape steel is uniformly cooled at a required cooling rate from 4 directions of upper and lower headers 4, 4 and both side headers 5, 5 disposed in a cooler 3. The distance from the material to be treated is made variable in conformity with the kinds and sizes of the materials which are transferred on rolls 6 in order to permit the change in cooling capacity in all positions in the longitudinal direction. As a result, the bending deformation, the increase in residual stress, etc. of the shape steel which is the material to be treated is positively prevented and the material to be treated is adequately heat treated. |
