GB505073A - Improvements in or relating to metal induction heating - Google Patents

Abstract

505,073. Transformers; heating by electromagnetic induction. SOMES, H. E. July 30, 1937, Nos. 9194 and 9195. Convention dates, Aug. 17, 1936, and Aug. 20, 1936. [Class 38 (ii)] [Also in Group XI] The supply of high-frequency current to the heating coil of induction heating apparatus is effected through a transformer comprising a fixed primary winding 89 located within a recess in the inner face of a cylindrical core 305, and a movable secondary winding 94 located within a recess on the outer face of a cylindrical core 328, the secondary being connected to the heating coil 63 which is arranged to move with the secondary so as to enter the work 65 to he heated when the secondary moves into coupling relationship with the primary. The secondary core 328 may be provided with an Extension 310 which completes the magnetic circuit of the primary when the secondary moves to the inoperative position. Where power factor correction is effected by a condenser 72 connected across the primary terminals 90, 91, this extension may be tapered as shown so as to introduce a gradually widening air gap into the primary magnetic circuit. Where power factor correction is effected by a condenser connected across the secondary terminals, the core extension is of the same diameter throughout its length, Fig. 9 (not shown). The cores are built up from radially disposed laminations of tapered thickness and are clamped between end rings 313, 314, 325, 326, an intermediate ring being provided on the secondary structure in modifications in which the extension 310 is separate from the secondary core 328. The windings are formed from hollow conductors through which cooling liquid, which may also pass through the secondary connections to the heating coil 63, is circulated. In one form, Fig. 13 (not shown), the secondary core extension is omitted, and a switch in the primary circuit is arranged to be opened as the secondary moves into the inoperative position. The transformer is mounted by means of a ring bracket 83 on a column 20 on which the other components of the induction heating apparatus are mounted. These components and their association with the transformer are fully described in Specification 503,130, [Group XI], which is referred to. Additional Figures illustrating this subject-matter were included in the present Specification as open to inspection under Sect. 91, but do not appear in that Specification as accepted.