GB715714A - Improvements in and relating to induction heating apparatus - Google Patents

Abstract

715,714. Induction heating. DEUTSCHE EDELSTAHLWERKE AKT.-GES. June 23, 1952 [June 22, 1951; Nov. 21, 1951], No. 15793/52. Class 39 (3) Apparatus for heating a longitudinal striplike region of an elongated workpiece, e.g. the welding edges of a steel tube, includes a body 3 of high magnetic conductivity and low internal losses which, at least partially, surrounds the workpiece 1. Longitudinal conductors are disposed in slots in the body so that one half of the conductors, shown as 5, through which current flows unidirectionally, is disposed near the heated region, whilst the other half, comprising the return conductors 7 through which current flows in the opposite direction, is distributed over the remainder of the workpiece surface. The body may be constituted by laminated sheets, or it may comprise iron powder and a binder of electrically insulating material, such as a synthetic plastic. The conductors may be fluid cooled copper tubes or stranded conductors. In the latter case the slots may be hermetically sealed, and a cooling medium passed through them. The return slots need not contain equal numbers of return conductors, and the main heating slot may be sub-divided into smaller slots. The body may be in two halves and interconnected by a butt joint, and in the case of laminated sheets, the sheets may interengage. The axial length. of the heating conductors may be greater than that of the return conductors. In Fig. 5, poles 138 are provided adjacent the heated edges to increase the heating, and copper elements may be disposed in the sections 137. The main slot 103 has tapering walls, and one or more triangular section conductors, such as 139<SP>1</SP>, is or are arranged in the gap to concentrate the field. An extension 140 may be arranged on each triangular conductor, and may pass between the heated edges of the workpiece. In Fig. 5 the extension is secured to a copper cooling tube 141 surrounded by laminated sheets 142. The cooling medium from the tube may quench the welded seam.