GB616271A - Improvements in a looper for control of travelling elongated material - Google Patents

Abstract

616,271. Automatic control systems for strip loopers. CARNEGIE -ILLINOIS STEEL CORPORATION. Oct. 11, 1945, No. 26552. Convention date, June 22. [Class 38 (iv)] Tension control in elongated material.-An automatically-controlled mechanical looper for travelling elongated material (e.g. steel strip) gathers a local excess of material and pays it out under control of the tension in the outgoing material to compensate for irregularities in the supply and demand. A continuous strip passes from a coil into motor-driven rolls 12, 14, over rollers 62, 78, 66 in a series of loops and through motor-driven rolls 16, 18 into a processing line. A carriage 30 movable vertically on guide wheels and rails and carrying rollers 62 is supported by counter-weighted cables 38, 46, which pass round drums 40, 4, driven by reversible motor 54 through worm gearing. Limit switches 86, 88 break the hoist motor circuit when the carriage reaches the top or bottom of its travel. Roller 66 is yieldably mounted on rod 70 of piston 106 sliding in a top vented cylinder fixed to the carriage 30. Compressed air may be admitted to the cylinder below the piston through a reducing valve and a stop valve 110 opened by a cam 122 carried by the roller mounting, when the piston falls below the midway point in the cylinder, which is connected by airline 112 to a relief valve 114, a pressure-operated stop and reversing switch 144, and pressureoperated rheostats 116, 120. Strip is threaded through the looper when the carriage is in its lowest position, and compressed air is admitted to the cylinder after the carriage has been raised by manual control (not shown) of hoist motor 54, with piston 106 in its lowest position from which it rises against strip tension until the valve 110 is closed by the cam. The pressure falls as the piston rises until at a critical value the pressure switch starts the motor 54 to hoist the carriage to the top of its stroke, controlled by rheostat 116 so that speed increases with falling pressure. On a rise in strip tension, as by cessation of input, the piston is pulled down by the roller 66 and compresses the air in the cylinder so that the pressure switch first stops and then reverses the hoist motor, lowering the carriage under control of the rheostat 120, speed increasing with rising pressure. Strip is thus payed out until the carriage reaches its lowest position. On cessation of output, the strip tension on roller 66 slackens and the carriage is raised as before to absorb the excess input. The time of travel of the piston in its cylinder is proportioned to allow the hoist motor to run up to compensating speed before the piston reaches its limit. Strip breakage causes a rapid rise of roller 66, and the forked ends 98 of arm 92 are lifted to open switch 90 in the circuit of the motors driving the rolls 12, 14, 16, 18. In a modification (not shown), the control circuit regulates the downward carriage movement only, upward movement being manually controlled.