Patent GB-986456-A (GB)
Title: Improvements relating to automatic positional control
Inventor: OHLSEN GEOFFREY TURNER
IPC: G05D3/12
Filed: 1962-11-26
Abstract: 986,456. Indexing; transferring blanks; drilling; machine tool details. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Nov. 19, 1963 [Nov. 26, 1962], No. 44637/62. Headings B3B, B3C and B3W. [Also in Division G4] Angular positioning control apparatus comprises a plurality of selectively excitable energizing devices (e.g. two brushes in Fig. 2) located at preselectable angular positions, three pick-up devices (e.g. conducting segments A, B, C in Fig. 2) effective over respective arcs of a circle, each energizing device being effective over an arc great enough to span two of the gaps (A-C, B-C in Fig. 2) between the pick-up devices but not the third (A-B in Fig. 2), and control means for producing relative rotation between the pick-up devices and the energizing devices in one direction (R) in response to energization of one of the pick-up devices (B in Fig. 2) by an excited energizing device and in the opposite direction (F) in response to such energization of the other two pick-up devices separately or together. Fig. 3 (not shown) shows a modification in which each brush is replaced by two brushes connected in parallel via diodes to render impossible simultaneous energization of all three segments A, B, C even if both gaps A-C, C-B are bridged by brushes simultaneously. Fig. 5 (not shown) shows a diode matrix for energizing one of 39 brushes (or brush-pairs, Fig. 3) in response to the cutting-off of one of four " tens " transistors and one of ten " units " transistors by means of selector switches or punched-tape-actuated control. The invention may be used in machine tools, for positioning a drum store for tools, or the turret of a turret press (for punching) or a turret type drilling machine. Fig. 6 (not shown) shows means in which a turret is rotated until the energized brush reaches the gap A-B when the turret is rotated further at a lower speed until a hole in the turret is brought into alignment with a spring-loaded locking plunger. The plunger slips into the hole, thus preventing further turret movement and actuating a switch to stop the drive motor. A torque-limiting clutch is provided in the turret drive. Instead of using plungers the low speed rotation could be terminated by means for stopping the motor when the energized brush contacts an additional segment positioned in the gap A-B. The gap A-B may be adjustable (Fig. 7, not shown) and the segments A, B, C could be mounted on a drum rather than a disc (Fig. 8, not shown). A further modification consists in using an electromagnet to move those brushes having the same " tens " digit as the required brush into contact with the segments from a disengaged position and energizing all brushes having the required " units " digit, so that only the required brush is both energized and in contact. Fig. 9 shows an optical arrangement using lamps L1- L6 in place of brushes and photo-cells PA, PB, PC in place of segments. Screens sh, sk1, sh2, sh3 define the effective arcs of the lamps and photo-cells. Capacitative detection of A.C.- energized plates (replacing the brushes) by segments could alternatively be used (resulting in the tuning or detuning of oscillators connected to the segments), or each segment could be replaced by an iron or ferrite core of the same dimensions having a winding to detect inductively A.C.-energized coils replacing the brushes.