GB741414A - Improved method of, and means for, controlling the operation of copy machine tools or copy producing devices - Google Patents

Abstract

741,414. Fluid-pressure servomotor-control systems. FAIRBAIRN LAWSON COMBE BARBOUR, Ltd. Sept. 1, 1952 [Sept. 11, 1951], No. 21374/51. Class 135. In apparatus for accurately controlling the movements of a copy machine tool in accordance with movements of the pattern and comprising a servo control valve responsive to the movements of the pattern to control the flow of pressure liquid to and from a double-acting servomotor operating the copy machine tool, the valve includes dither means for removing or reducing the effects of sticking and/or friction in the apparatus. As shown, a stylus 8, Fig. 1, mounted in a part-spherical bearing 9, to permit of slight rocking movement as well as axial movement, is engaged by a pattern 3 mounted on a table 60 carrying the workpiece 61. The stylus engages, through a ball 10, a ported sleeve 6 slidably mounted in a casing 5, and slidably mounting a piston valve member 7 which is continuously reciprocated by a cam 52 or by a solenoid energized by an alternating current. Liquid from a tank 27 is supplied by a pump 28 to a casing port 15 and on e.g. upward movement of the pattern through movement of the table 60 from right to left, the sleeve 6 moves upwardly to connect the upperside of the piston 22 of a servomotor 21 to pressure liquid supply and its underside to exhaust to move the table downwardly and the cutting tool 62 to reproduce the pattern profile on the workpiece 61. In a modification, a sleeve 6a, Fig. 2, is continuously reciprocated through a cam 43 driven, e.g. by an electric motor, and a pivoted lever 44 and a piston valve member 7b is operable by the pattern 3 to supply and exhaust pressure liquid to and from a pair of cylinders 50, 51 housing pistons 52, 53 engageable with levers 45, 45a which control the movements of a further piston valve member 54 controlling the supply and exhaust of pressure liquid to and from the servomotor 21. The lever 45 is connected to the lever 44 so that movements of the sleeve 6a by the cam 43 are counteracted and the sleeve 6a follows the movements of the valve member 7b. Instead of the ported sleeve or valve member being continuously reciprocated either of them may be given a continuous rotary movement and have ports to cause continuous opening and closing of communication between the valve member and sleeve.