Patent GB-1191662-A (GB)
Title: Improvements relating to Position Control Equipment for Machine Tool Tables and the like
Inventor: JONES RICHARD FREDERICK
IPC: B23Q16/00
Filed: 1966-05-02
Abstract: 1,191,662. Machine tool details. PLESSEY CO. Ltd. 2 Aug., 1967 [2 May, 1966], No. 19292/66. Headings B3B and B3C. A co-ordinate drilling machine table comprises a base 3, Fig. 2, a member 2 slidable on the base in the Y axis direction, a member 1 slidable on member 2 in the x axis direction, each member being moved by an hydraulic piston 6, and its required position being controlled by a coarse setting device 7, a fine setting device 10, and a device 17 for varying the datum of device 10. The movements of the members 1 and 2 are programmed by a sprocket driven punched tape 38, Figs. 1A- 1E, read by a pneumatic tape reader 29, which supplies binary data to a fluid controlled binary to decimal decoder 58. The cycle of movements of members 1 and 2 is controlled by a rotary pneumatic cycle timer 67, and the members are supported by air bearings 4-5, Fig. 2. Device 7 comprises a bar 8, Fig. 2, fixed to base 3, having holes to which air is selectively supplied, and a detector shoe 9, fixed to member 2, which detects air issuing from a hole, so that. a fast approach is terminated, and control of movement is transferred to device 10. The latter comprises a bar 10 fixed to member 2 and having cutouts 11 at inch intervals, and a block 12 connected to device 17. Hydraulic fluid is supplied to holes 15, 16 in block 12, Fig. 5, and escapes at different rates from between recesses 13, 14 and bar 10 until piston 6 accurately positions member 2, so that block 12 is symmetrical relative to a shoulder between cutouts 11. Device 17 comprises two rows 18, 19 of accurately dimensioned cylinders arranged in three blocks 20-22 of eight cylinders each, Figs. 6, 7. The lengths of cylinder in one row differ from those in the other row, and the blocks provide length variations in thousandths, hundredths, and tenths of an inch respectively. Each pair of cylinders is connected by a yoke 23, Fig. 7, and the required one of each pair can be moved into row 19 by a pneumatic piston 26, so that the datum position of members 1 and 2 can be varied by thousandths of an inch. Timer 67 consists of a circumferentially slotted disc 70, Fig. 1B, driven through a slipping clutch 71, and pins 72 which engage with a latch 73 movable relative to the disc by a pneumatic piston 74. The disc 70 is interposed between an air manifold 150, and pick-up pipes 152. Decoder 58, Fig. 1D, comprises five superimposed perforated tapes 51 supplied with air from pipes 40 (tens) and pipes 41-44 (units), through high gain relays 48. In operation timer 67 is rotated until a pin 72 engages latch 73, air passes to pipes 152, an actuator 93 is operated, so that a motor 68 advances the tape by one block of information and the tape is clamped at 36. Tape 38 is read, and is converted from binary code to decimal data by decoder 58. The pipes 45-47 corresponding to thousandths, hundredths, and tenths of an inch supply air to device 17 so as to set the cylinders 18, 19. Latch 73 is pivoted, and timer 67 rotates until a further pin 72 engages the returned latch, whereupon air is supplied to decoder 58, and thence to coarse setting device 7, and air is also supplied to bearings 4 and 5. Hydraulic fluid is supplied from a source 60 to piston 6, Fig. 1E, and member 1 is moved along the X axis to the required approximate position. Hydraulic fluid is now passed to block 12, Fig. 1E, which cooperates with bar 10 to provide the fine adjustment of member 1. The air supply to bearings 4 and 5 is switched off, table locking clamps 132 associated with both members 1 and 2 are actuated, and the drill feed is set in motion. The apparatus shown in dashed outline in Fig. 1 is duplicated for use with members 1 and 2.