| 摘要 |
PURPOSE:To harden a work having various shapes to high hardness by providing a streamplined air flow passage which circulates and feeds cooling gas to the work in a vacuum vessel and providing a jacket in which a cooling fluid flows on the outside thereof. CONSTITUTION:A heat treated work A is disposed in the cooling chamber 2 in a vacuum chamber 3 and the inside thereof is evacuated with an evacuating means 9. Cooling gas is supplied therein from a surge tank 31 to maintain a prescribed pressure in the vessel 3. Solenoid valves 19, 21 are opened and a blasting means 6 is operated. Cooling water from a cooler 18 is successively supplied to a heat exchanger provided in a streamlined air flow passage 4 and the jacket 17 in the circumferential wall 15 of the vessel 3 to cool cooling gas which is then blown to the work A. When the work A is cooled to a prescribed intermediate temp., the valves 19, 21 are closed and solenoid valves 24, 25 are opened to change over the cooling water to the hot water from a tank 22; at the same time, the pressure in the vessel 3 is decreased by the means 9 to cool the work. If the work A is large sized, the hardening treatment is continued by the cooling water without changing the cooling temp. in mid-way. |
