Patent GB-665428-A (GB)
Title: Wire-drawing machines
IPC: B21C1/12
Filed: 1949-11-25
Abstract: 665,428. Drawing wire. TRIGGS, W. W. (Morgan Construction Co.). Nov. 25, 1949, No. 30306/49. Class 83 (iv). [Also in Group XXXVII] A wire-drawing machine comprising a series of dies, a plurality of rotatable drums and separate means associated with the respective drums to apply forward driving torques thereto at the values required to maintain predetermined back tensions and forward tensions in the wire during normal drawing at uniform speeds, is characterized in that means is provided to alter the torques applied to the respective drums during changes in the speed of the machine, to values so related to the rotary inertias of the drums and to their respective speeds as to maintain the wire tensions throughout the machine below the breaking strength of the wire. Five rotatable blocks 21 and a finishing block 22 are driven by worms 28 on a shaft 27 driven by an electric motor 26, the worm for the finishing block driving a worm wheel 29 directly secured to the block spindle 31, but the worms for the first five blocks driving wheels 29 each connected to the housing of a positive displacement rotary pump 32 of the type disclosed in Specification 533,854. The rotor of each pump is connected to the spindle of the associated block 21 and draws a stream of oil from the reservoir 20 and discharges it at controlled pressure, thereby imposing a controlled torque on the pump rotor and the block connected thereto. Associated valve mechanism, Fig. 4, regulates the pressure of the discharge oil-and hence the torque appliedto the block. Oil discharged from each pump flows through a pressure regulating valve 37 to exhaust 40, the pressure in the valve chamber 36 on the underside of a piston 45 holding the valve member 44 above its seat to permit such flow. A small stream of oil flows through an orifice 50 in the piston 45 to a relief valve 53 having an adjusting screw 60 which is set to maintain the pressure in the chamber 36 at a required substantially constant value to provide the desired driving torque for the corresponding block during normal drawing. To make the required temporary changes in the driving torques during threading, accelerating and stopping, oil is provided at suitable pressures to the upper and lower surfaces of a piston 62 in a cylindrical bore 63 in the upper portion of the valve 37, by means of a pressure reducing and regulating valve 68, a four-way valve 69 and a three-way valve 70. The valve 69 comprises two solenoids AS1 and DS1 and the valve 70 comprises a solenoid JS1. When block 1 is to be jogged for threading, solenoid JS1 is energized and oil is applied to the top of piston 62, urging it and piston 45 downwardly, closing the valve member 44 on to its seat and increasing the pump discharge pressure so that the pump may transmit ample torque for threading purposes. This process is repeated for each block until the machine is set up ready for drawing. When the block is accelerating from rest solenoid AS1 is energized and the pump pressure is again increased thereby to increase the torque on the block to compensate for the rotary inertia of the block. When decelerating to stop, solenoid DS1 is energized and the torque is reduced. During normal running at substantially constant speed all three solenoids are de-energized and the torque is controlled by the adjustment of the relief valve 53. The electrical circuit, Fig. 5 (not shown), includes the appropriate start, stop and jogging pushbuttons, contactors and time delays controlling the motor 26 and the valves. The output of a pilot generator 33 controls a switch such that when the machine has accelerated from rest to normal running speed, the accelerating solenoids AS1 for all blocks will be de-energized and the pumps 32 will transmit the normal running torques to their blocks. In a modification the torque to each of the first five blocks is transmitted through a magnetic slip clutch whose energization is varied to provide the required changes in torque during threading, accelerating and stopping. In a further modification each block is driven by a separate electric motor, all supplied from a motor generator set, the first five block motors also each having associated with them a boosting generator and a motor driven amplidyne exciter, providing a Ward-Leonard control of the block motors, the electrical circuit comprising the appropriate control of the torque variations for threading accelerating and stopping. The electrical arrangements for each of the embodiments described provide for dynamic or regenerative braking of the motor or motors during deceleration to rest.