GB1265703A - - Google Patents

Abstract

1,265,703. Milling machines. ANDREW ENG. CO. 6 June, 1969 [17 June, 1968], No. 28825/69. Heading B3K. [Also in Division G3] Rotation and axial movement of a face, e.g. a cylindrical face, of a workpiece W is effected in response to mutually perpendicular movements of a head 17 which automatically traces a line 13 on a plane drawing 12. Light projected through the drawing is guided through flexible fibres 23 to a rotatable sensing head, in which an image of the line is reflected on to a pair of split photocells (Fig. 3, not shown). Unless they are equally illuminated the photo-cells unbalance a bridge circuit which causes rotation of the head to restore balance. The rotary motion is converted by cams into linear motion in the X and Y directions, forming the inputs to mechanical integrators (Fig. 2, not shown) whose outputs drive synchros through gearing of various ratios. Selection of the synchro having the appropriate gear determines the scale factor between drawing and work. One of the synchros in each plane controls servos which position the head 17 and its carriage 15, so as to trace the curve 13; the others are connectible in various combinations to servos producing X and Y motion of the workpiece on a milling machine, and to a servo 70 for controlling its rotation about the X axis. To provide for cutter offset the rotary motion of the sensing head is also communicated through adjustable links to further X and Y synchros whose outputs can be connected as required to the motion servos. Five modes of interconnecting the tracer synchros with the motion servos are described. In the first, a flat workpiece is machined by direct connection of X to X, Y to Y with cutter offset also directly added. In the second, the X trace and offset produces X motion while Y trace and offset produces rotation, there being no motion in Y; this would mill a groove in or a rib on a cylinder. The third is similar to the second except that the Y offset is used to produce slight Y motion, and it is explained why this is necessary for a parallel sided groove or for a rib of constant crest width in the axial and circumferential directions, using a tapered cutter (Figs. 13... 16, not shown). The fourth and fifth modes correspond to the second and third but with the X and Y axes transposed to provide greater range in one direction.