GB808680A - Improvements in or relating to the resistance heating of steel - Google Patents

Abstract

808,680. Heating metal bodies by passage of current. BOCHUMER VEREIN FUR GUSSSTAHLFABRIKATION A. G. Sept. 11, 1956 [Oct. 28, 1955], No. 27772/56. Class 39(3) Bodies of metal or alloys especially steel bars 15 are heated by passage of current therethrough from water-cooled contacts 12, 16 connected to a transformer 4. The contact 12 is carried at the end of a piston or rod 5, to a cylindrical part of which is clamped an internally ribbed sleeve contact member 1 in two parts clamped together and connected to the transformer by a lead 3. The piston 5 moves in a pressure cylinder 6 through the open stationary sleeve 1 'and forces the end contact 12 against the bar 15. Pressure in the cylinder 6 is controlled by a member 11. The opposite contact 16 is forced against a compression spring 17, and when the spring 17 is fully compressed pressure is retained in the cylinder 6 by the control 11; the contact sleeve 1 is then clamped on the piston 5 and current is switched on preferably automatically. When the steel bar 15 reaches 1000‹-1200‹C, the contact clamp 1 is opened and the pressure in the cylinder 6 is released by the control 11 to release pressure of the contacts on the bar 15. Means 18 raise and lower the bars 15. In order to heat bars of different lengths, the piston and cylinder are mounted on a movable carriage 7. The halves of the contact sleeve 1 are held together at the top by a clip 8 and are formed at their lower parts with projections 9 which are forced together or apart by a wedge 10 slidable over rollers to clamp the sleeve 1 on the piston or to release it. Replaceable frusto-conical contact members 14, 19 are placed on the contacts 12, 16.