| 摘要 |
<p>759,866. Annealing. ALUMINIUM LABORATORIES, Ltd. Feb. 23, 1955 [March 5, 1954], No. 6516/54. Class 72. [Also in Groups XI and XXXV] A method of producing metal discs having a hard centre and a soft peripheral portion comprises clamping hard discs between the poles of an alternating current electromagnet so that the portion to be annealed projects beyond the periphery of the poles and is heated by eddy currents. As shown, discs 2 are held between the poles of an alternating current electromagnet 1 by a movable support 7. The pole 9 is then moved pneumatically, hydraulically, electrically or mechanically to clamp the discs in position and the support 7 removed. Current is then switched on and the peripheral portion is softened. When softening is complete the pole 9 is retracted and the discs, which may be distorted, are dropped into a press having formers 14, 15 where they are given a dished shape. Specification 759,859 [Group XXII], is referred to.</p> |
