Patent GB-765873-A (GB)
Title: Improvements in and relating to feeler controls for copying machines
IPC: B23Q35/12
Filed: 1953-12-08
Abstract: 765,873. Copy - milling ; copy - turning. SCHMID, W. K. Dec. 8, 1953 [Dec. 8, 1952], No. 34185/53. Class 83 (3). [Also in Group XXXVIII] The feeler of a copying-lathe or milling-machine is associated with control apparatus such that the speed of travel of the feeler and an associated cutting-tool can be either fast or slow, depending on the direction of travel of the feeler relative to the fixed template, or changes in this direction, so that traverse along rectilinear paths is more rapid than along curved paths. A feeler 5, Fig. 1, in association with a template and cutting-tool (not shown), produces vertical movement of an insulated block 9 having projections 10-13 acting on switches 14-17, whereby relays R1-R4 are selectively energized to complete energizing-circuits for magnetic-clutches 2, 3 so that the cutting-tool is moved longitudinally or transversely or both, in either direction, in accordance with the shape of the template. The circuit of clutch 3 includes a regulating-device 4 comprising an insulating-cylinder 52 having a series of longitudinal, tapered, conducting-strips 53, rotated by the motor feeding into clutch 3, whereby the electrical input to the clutch-winding comprises a series of pulses instead of a continuous voltage supply, and the driving- speed transmitted by clutch 3 is accordingly reduced, in accordance with the position of a manually-adjustable brush 61 determining the duration of the pulses. Relays R1, R2 have additional contacts 46, 47 so that when both relays R1, R2 are energized, i.e. when the feeler 5 is moving longitudinally controlled by clutch 3 only, the regulator 4 is short-circuited, and cutting takes place at the maximum speed. In another embodiment, Fig. 4, the terminals of the regulator 4 are also connected to the seriesconnected switch contacts 75, 84, 85, 86 of four slow-acting time relays 65, 66, 67, 68 whose windings are in parallel with the four windings of the clutches 2, 3, each time-relay closing its contacts only when unenergized or fullyoperated, whereby the clutches 2, 3 transmit at full speed when the time relays are at rest, but at reduced speed for a predetermined period after the condition of a time relay has been changed, due to a change in direction of the feeler and cutting-tool. The four time relays may be replaced by a single, four-winding, slowacting relay whose windings are in parallel with those of the clutches 2, 3 which short-circuits the speed-regulator 4 when either one or two of its windings are energized, i.e. when the time relay is not, or is operated, respectively, but leaves the speed-regulator in circuit for a predetermined time after a change in direction occurs. The time delay may alternatively be produced by auxiliary relays interconnected with the windings of the clutches 2, 3 operating a pendulum-type switch at each change in direction (Fig. 10, not shown), thereby only short-circuiting the speed-regulator after a predetermined time following a change in direction. By using controllable gear-ratios on the shafts driven by the clutches 2, 3, the direction of travel of the feeler and cutting-tool when both clutches are engaging may be varied to suit the template, so that a surface at any angle to the longitudinal and transverse directions may be cut at full speed. Specification 730,677, [Group XXIV], is referred to.