Patent GB-1246857-A (GB)
Title: Installation for programmed control of a machine-tool
Inventor: PRODEL JACQUES
IPC: G05B19/04
Filed: 1969-01-22
Abstract: 1,246,857. Programmed control of machine tools. J. PRODEL. Jan. 22, 1969 [Jan. 23, 1968; Jan. 7, 1969], No.3513/69. Heading G3N. A programme control installation for positioning a movable element of a machine-tool comprises a rotatable lead-screw coupled to the element a coarse positioning control for each desired position and a fine positioning control for discontinuing the drive at a desired position within a full revolution of the lead-screw. The movement of a milling machine table is effected by similar systems for each of the coordinate axes. Each system comprises an approach detector and a precise stop detector. The approach detector D1, Fig. 1, comprises a scanning head 11 in a casing 21 which is fixed to a carriage 2 by screws 13 and has a slot through which passes a tensioned perforated tape 12. The tape 12 is attached to the table by pillars 15 retained in a T-section slot 16. The scanning head incorporates a vertical bank of four photo-resistive cells which co-operate with a linear filament lamp to scan the perforations 81-85 in the four tracks of the tape. The precise stop detector D2 is coupled to the lead screw driving motor 112 and the lead-screw is provided with a vernier 111. The coupling between the motor 112 and detector D2 is effected by a pulleys 127, 128, Fig. 5, and a notched belt 126 the ratio between the pulleys being determined by the lead-screw pitch. The pulley 128 drives a shaft 124 to which is attached a slotted drum 142 enclosing a lamp 143. The drum has four slots, such as 148, 149, determining which of a annular ring of ten photo-cells such as 138-9, are illuminated and a tongue 152 determining which of a ring of ten photo-cells, such as 139-A, is occulted. The outputs of the photo-cells 139, 138 are so coded as to determine the movement of the table to 0À1 mm and 0À02 mm respectively. The operation of the lamps of the detectors is monitored by separate photo-electric cells directly illuminated. In alternative embodiments of the precise stop detector the drum 142 is replaced by a disc and a modification of the precise stop position is possible by alignment of an auxiliary disc. A system of automatic control employing the detectors D1, D2 Fig. 14, is connected as shown. The photo-cells 26-29 of detector D1 are illuminated through holes in the tape 12 by a light 42 to energize a relay R1, which stops a selector switch 172 successively supplying columns of a matrix 171 utilizing plug-in diodes. The outlets of the matrix lines determine (1)the energization of an electro-hydraulic valve for the motor 112 for longitudinal movement of the table; (2) reverse movement of motor 112; (3, 4) the supply to a motor 112A for carriage movement; (5-7) determine the speeds of motors 112, 112A through valves 182, 183, 184 and a flow regulator 188. The next lines 1-4 select the photo-cell corresponding to the desired track P1-P4 on the tape, the following lines A-3 select the appropriate photo-cells of the precise stop detector for the final incremental positioning. A final line D2 actuates a reversing relay R2. The tape is punched by hand from a drawing of the article to be machined. A panel is provided whereby manual checking of the programme can be effected.