GB843469A - Machine tool control apparatus - Google Patents

Abstract

843,469. Programming for machine-tools. INDUCTOSYN Ltd. May 22, 1956 [Jan. 27, 1956], No. 15787/56. Class 83 (3). [Also in Group XXXVIII] The desired contour of a workpiece is programmed in the form of a tape giving digital information of consecutive values of slope, curvature, rate-of-change of curvature, and feed-rate, the digital values being converted into analogue values and combined via integrators, selsyn units and differential gears (Figs. 6, 7, not shown), as described in Specification 807,220, to operate co-ordinate feed-shafts 80, 82, Fig. 8, whereby a cutting-tool 1 and workpiece 7 are positioned to reproduce the desired contour. The axis of the cutter 1 is positioned with respect to the work 7 in accordance with the x, y co-ordinate values of the contour, determined by the input-analogue values, modified in accordance with the radius of the cutter, the x co-ordinate being modified by R sin O and the y co-ordinate by R cos O, where R is the radius of the cutter, and O is the angle of slope of the desired contour. The modifications are derived from a computer comprising a table 16, Figs. 3 and 4, whose angular position is adjusted to 6, derived from the input information as described above, on which is located a pin 22 whose distance from the centre of the table 16 is made equal to R by rotation of a shaft 134, either manually or automatically as by signals derived from a tool-radius record 141. The rotation of shaft 134 is converted by coarse adjustment potentiometers 131, 52, and fine adjustment resolvers 132, 54, into the appropriate linear movement of shaft 24 and pin 22. The movements of the pin control the lateral movements of two yokes 36, 38, constrained to move linearly in mutually-perpendicular directions, whereby the output of selsyn-type devices attached to the yokes produce signals proportional to R cos O and R sin O respectively, in coarse stages 64<SP>1</SP>, 64, medium stages 66<SP>1</SP>, 66 and fine stages 68, 74. These signals are added to the x, y co-ordinate values of the desired contour, and used to drive the feed-shafts 80, 82. By using a cutter of larger or smaller radius than R, the work can be cut a corresponding amount smaller or larger, thereby enabling mating parts with a given clearance to be cut using the same recorded programme. The apparatus also enables an initial roughing cut to be made, followed by an accurate cut, when R is set inaccurately. By using two computers in tandem, as shown in Fig. 3, a programme for a threedimensional container can be corrected for the cutter - radius &c. Specifications 801,516, 801,517 and 807,218 also are referred to.