| 摘要 |
PURPOSE:To prevent generation of deformation, quenching crack, etc. of a thin-walled cylindrical article by hardening the inside circumferential surface of the cylindrical article by means of a high frequency hardening coil while holding the cylindrical article by plug socket rings fitting to the inside circumferential surface of the cylindrical article. CONSTITUTION:A thin-walled cylindrical article A having a flange part D is held by lower and upper plug socket-bored rings 28, 29 provided with steps 28a, 29a forming fitting parts to the upper and lower inside circumferential edges B1, B2 of said cylindrical article and a high frequency coil 24 attached to a bracket 23 is inserted into the article A. Cooling water is injected from a cooling jacket 25 to cool the outside circumferential surface of the article A and the inside circumferential surface B is subjected to high frequency induction heating by conducting electricity to the coil 24 during said cooling. The cooling water is injected from a cooling nozzle 26 via a flow regulating plate 27 to cool quickly the inside circumferential surface B of the article A thereby hardening said surface. The surface B of the article A is restrained by the rings 28, 20 during said hardening, by which the generation of hardening deformation, etc. is obviated. |
