Patent GB-1011077-A (GB)
Title: Automatic control system for a machine tool
IPC: G05B19/18
Filed: 1963-02-08
Abstract: 1,011,077. Programmed control of machine tools. CINCINNATI MILLING MACHINE CO. Feb. 8, 1963 [Feb. 26, 1962], No. 5182/63. Heading G3N. In an automatic control system for a machine tool whereby a tool is caused to follow a predetermined contour by signals from a single source which represent a control function in at least one dimension at spaced intervals and are fed to an interpolator the output signals from which, representing intermediate values of said spaced intervals, are selectively switched in a predetermined sequence to the control inputs of the drives for the corresponding dimensions. As shown, a tape reader 25 transmits data, on receipt of a "read" signal on line 26, to a decoder and distributor 28 which translates the data and feeds it, in a predetermined sequence or in accordance with instructions on the top, X and Y axis stores 30, 31, and to feed rate stores 34. The stored data, representing five suc - cessive points along the curve, is fed to interpolators 38, 39,wherein they are interpolated, three at a time, and the analog voltages are fed to difference circuits 42, 43. The other inputs to the difference circuits are analog position signals from potentiometers 50, 51 coupled to X and Y slides 48, 49. The differences between the inputs are applied through servo-amplifiers 44, 45 to drive servomotors 48,49. The X and Y axis interpolators are driven by a pulse generator58 which transmits shift pulses to a shift register and relay rings 60, comprising a plurality of identical flip-flops with the first stage of the register connected to the last stage so as to enable cyclic operation in response to the shift pulses. Each stage of the shift register is connected with a solenoid driver which activates reed relays in the interpolator output switching circuits, so that as the shift register is cycled, each of the final interpolator stages is sequentially connected to the corresponding difference circuit to produce the smoothy varying required to drive the slide 48, 49. The feed-rate along the path produced by the combined movements of the slides is determined by the analog output voltage of the feed rate stores 34a, 34b which are alternately filled with data relating to adjacent spans. The store output voltage is fed to an acceleration-deceleration unit 65 which ensures a change in rate is effected smoothly within the shortest upon length. The adjusted feedrate voltage is fed to a computer circuit 67 where it is divided by the rectorial rum of the sub-span lengths, derived, from the output of the X and Y interpolators 38, 39, with appropriate phaseshift 71, by a summing network 70. The resultant is used to control the pulse generator 58 so that the product of space length and shift pulse rate is maintained equal to the programmed feed rate. The number of discrete steps at the output of the interpolator for each span length input is determined by a voltage step and cycling control 75 which senses the difference between pairs of X and Y axis end-point voltages and selects the larger for controlling the number of steps. The control 75 also simultaneously and sequentially connects the stores 30, 31 to their interpolators so as to maintain synchronism and through line 26 causes the reader 25 to read the neat block of information. This data is then delivered to the decodes 28 from which it is fed to the stores 30, 31, 34. Specifications 1,011,078,1,011,079 and 1,011,080 are referred to.