GB1050520A - - Google Patents

Abstract

1,050,520. Heat treating saw teeth. RADYNE Ltd. April 14, 1965 [April 22, 1964], No. 16701/64. Heading C7N. A hacksaw blade is hardened by selective heating of the saw teeth achieved by connecting the blade 10 in series with the working circuit of a high frequency e. g. 450 kc. /s. induction heater (not shown) through electrical conductors 16, 17 which extend from terminal members, such as copper blocks 13, 13a and clamping blocks 14, 14a, with silver electrical contacts 11, 12 see Fig. 2, (not shown), and include an inductor or inductors, preferably two each having a chamfered edge 19, 19a, lying adjacent and parallel to the toothed edge of the blade so that the high frequency current flowing through the blade tends to concentrate along the toothed edge. A further inductor or set of inductors, may be arranged along the back edge of the blade to produce further current concentration along this edge to harden it. Alternatively, distortion may be prevented during hardening by applying a restraining pressure or tensile force to the blade. The inductors may be water cooled by tubes 22, 22a.