GB1317466A - Apparatus for use in forming a surface of preselectred shape on an elongate workpiece - Google Patents

Abstract

1317466 Electrical control systems GETTYS MFG CO Inc 29 June 1970 31302/70 Heading G1N In order to form a surface on a workpiece 10 by a tool 12 defined by the function x=f(Z) where Z and X represent points on the workpiece surface as measured in first and second mutually perpendicular directions an electrical signal, representing the position of the tool 12 with respect to the workpiece 10 when moved along the first direction by a first drive 20, is modified in accordance with the function and a second drive 17 moving the tool in the second direction is controlled in response to the modified signal so that the tool traces a curve as defined by the function. The position of tool 10 along the Z axis is detected by means of potentiometers 24, 26 the wipers 24b, 26b of which are gauged together and coupled to lead screw 22 which drives tool slide 16. The output from operational amplifier 80, representative of the absolute value Z of the position of the tool 12 with respect to roll 10 being crown machined, is squared by potentiometer 26 and amplifier 82. The arc length C of the crown to be machined is determined by the setting of potentiometer 86 in the feedback loop of amplifier 84 which modifies the signal Z<SP>2</SP> by factor I/C and the output signal Z<SP>2</SP>/C is further modified in accordance with the desired arc height H by potentiometer 92. The function H (Z<SP>2</SP>/C) thus computed is compared at junction 100 with a value X representative of the cross axis displacement derived from feeler 44 coupled to a differential displacement transformer transducer 60, 62, 64, 66 the a. c. output of which is demodulated to give a positive or negative voltage indicative of the value and direction of the displacement x. The difference signal from amplifier 102 is used to control the x-axis drive 17, Fig. 3B (not shown) so that the voltage at junction 100 is maintained at zero so that the system is continually solving equation X = H(Z<SP>2</SP>/C) which means that the cutting tool 12 is traversing the desired path with respect to roll 10. If the tool 12 is to machine in accordance with a linear equation potentiometer 26 and amplifier 82 are by-passed. A nulling system including a double pole triple throw switch 128 is provided to assure that the voltage from amplifier 96 is equal to zero when the longitudinal displacement is equal to zero.