GB696298A - Improved apparatus for the hot drawing of steel and other hard, ductile metals or alloys - Google Patents

Abstract

696,298. Automatic control systems. MARSHALL RICHARDS MACHINE CO., Ltd., and SOMERVILLE, T. B. Oct. 17, 1951 [Oct. 20, 1950], No. 25592/50. Class 38 (iv). [Also in Groups XXII and XXXVII] Apparatus for hot drawing wires, rods, tubes, angles, &c. comprises a drawing block and die, and heating means through which the metal passes immediately prior to its entry into the die, a substantially constant torque being applied to the block, whereby the speed of the metal through the heating means is varied automatically to maintain substantially constant the temperature at entry of the metal into the die. If the temperature of entry falls the pull required to draw increases and since the pull of the machine is constant, the speed of drawing is automatically reduced allowing the material to remain under the influence of the heating means for a longer period and its temperature to rise. If the temperature rises too high, the speed of draw is increased and the material passes through the heating zone more quickly. Wire 1, passing through a hot lead bath 2 and resistance heated by means of a transformer 4, is drawn through a die 3 by a separately excited constant torque motor 7. A manually adjustable rheostat 12 allows the torque to be adjusted, and the armature 13 is supplied from a grid controlled rectifier 14, with a current regulator 22 and phase shifter 17 in the circuit. In a modification a shunt field winding causes the torque at high speed to decrease, when a higher torque at starting and slow running is necessary. The drawing block may be driven through an electro magnetic slip coupling or an A.C. motor with an induction regulator.