GB1492779A - Induction heating apparatus for mass production - Google Patents

Abstract

1492779 Induction heating ITT INDUSTRIES Inc 19 Dec 1974 [28 Dec 1973 3 Jan 1974) 54871/74 Heading H5H [Also in Division H1] An induction heater comprises a R.F. generator 10 connected to a primary coil 1 of a transformer, and an induction heating work coil 2 electrically connected to the secondary coil 3 of the transformer, the work coil 2 being movable relative to the primary coil 1. As shown, the transfer circuit comprising secondary coil 3 and work coil 2, are rotated about a vertical axis A-A<SP>1</SP> centred on the axes of the primary and secondary coils 1 and 3 so that the work coil 2 passes successively a plurality of pairs of workpieces 6, 7 &c. mounted on a fixed table 8. The coupling gap between the work coil 2 and workpieces 6, 7 which are being welded, is maintained constant by ensuring the transfer circuit rotates in a plane parallel to the table 8. The R.F. generator may be continuously energized and the transfer circuit may be rotated continuously during heat treatment of the workpieces 6, 7. In Fig. 2b which is for making glass to metal seals on workpieces 6, the workpieces 6 and a plurality of transfer circuits 21, 23 are both mounted on a circular table 8 which is rotatable to bring the secondary transformer coils 23 of the transfer circuits successively into coupled relationship with the fixed primary coil of the transformer. Supports 22 for the transfer circuits 21, 23 have two degrees of freedom to allow coupling between the work coils 21 and workpieces 6 to be adjusted prior to heating. In Fig. 4, not shown, for making vacuum or gas filled discharge tubes each work coil and vacuum tube workpiece are mounted in an individual chamber which may be evacuated or filled with gas. Each work coil is connected through a gas tight seal to an externally mounted secondary transformer coil of the transfer circuit. The chambers are movable to bring their secondary coils into successive coupling relationship with the fixed primary coil.