Patent GB-884393-A (GB)
Title: Apparatus for moving a worktable, drill or other machine tool part to a predetermined position
Inventor: ADCOCK JOSEPH NOEL
IPC: G05B19/21
Filed: 1957-02-20
Abstract: 884,393. Drilling &c. machines. UNITED STEEL CO., Ltd. May 20, 1958 [Feb. 20, 1957], No. 5795/57. Class 83 (3). Means for moving a work-table or drill-head &c. to a predetermined position comprises power means for moving the table &c., a member 14 movable accurately relatively to the table to a predetermined position, and an electric switch to stop the power means when -the table reaches a given position relatively to member 14. As shown, hydraulically-effected movements of the table 1 and saddle 29 of a drilling-machine are controlled, but the control may be of movements of the table in one direction and of a drill-head (not shown) in a direction perpendicular to that of the table. The power means may be an electric motor with a brake. Guides 30, Fig. 5, with a brass liner 34 support the table on saddle 29, which moves, perpendicularly to the movement of the table, on guides 39 lined with non-ferrous metal. Further linedguides 44, 45 on the bed engage ribs 47 (Fig. 2, not shown), beneath the saddle. Double-acting hydraulic jacks 51, 48 traverse the table and saddle respectively and are supplied through three-position valves 9, Fig. 1, operated by solenoids 24, 25. The trip-slide 14, carrying adjustable dogs 23a- 23d for operating the roller-carrying levers of micro-switches 22a-22d on table 1, Fig. 6, is positioned along a slideway 53 by a lead-screw 15 driven by a belt 55 from a motor 16. The other end of the lead-screw drives a synchrotransmitter 19 connected electrically to a synchro-receiver 20 in a control panel 18, Fig. 1. A counter 21 connected to the receiver indicates the position of trip-slide 14, and a speed regulator 17 controls the motor. A corresponding trip-slide 56, motor 58, transmitter 60 &c. are provided for the saddle, the control system for the table only being shown in Fig. 1. The Specification describes in detail an electrical circuit (Fig. 7, not shown), controlling operation of jack 51 for positioning the table as decided by the position of tripslide 14. Switches 22a, 22d for deciding the direction of traverse, and switches 22b, 22c for slowing the rate of traverse by closing a solenoid-operated by-pass valve 27 before the table is stopped, are connected to holding circuits and safety circuits so that upon operation of a switch 28 on the control panel 18 the table is positioned automatically. Holding circuits condition the main circuit when the trip-slide releases switches 22a-22c as it is moved from the stop position, Fig. 6, so that when switch 28 is closed the table always follows the slide. Close to the new stop position, the operative switch 22b or 22c, depending on the direction of movement, closes by-pass valve 27 and reduces the rate of traverse before switch 22a or 22d de-energizes the operative solenoid 24 or 25 controlling valve 9. This isolates the jack and stops the table with the switches in the stop position of Fig. 6. The safety circuits prevent operation of the drill-head while the table is being positioned and vice versa. Cables 63 between switches 22 and the control panel pass around a pulley 64. A relief valve 12 limits the pressure in the hydraulic circuit, and a by-pass valve 13 is opened automatically to return the liquid from the pump 6 to a reservoir 5 when the table is stationary.