Patent GB-950463-A (GB)
Title: Improvements relating to systems for automatically locating a member with respect toan operational head
Inventor: DRUMMOND ROBERT MAIN
IPC: B23Q35/128
Filed: 1960-07-15
Abstract: 950,463. Machine tool details; drilling; mounting components on circuit boards. FERRANTI Ltd. July 10, 1961 [July 15, 1960], No. 24668/60. Headings B3A, B3B and B3C. [Also in Division G3] In a system for automatically and sequentially locating a member in a predetermined series of positions with respect to an operational head, a hole pattern is scanned row by row and relative movement between the member and the operating head is synchronized with the movement of a hole scanning device with respect to the hole pattern. As shown, an hydraulic ram 8 mounted on a bed 1 is resiliently coupled to a plate 5 by a rod 9 and spring washers 11, 12. A similar ram 14 mounted on the plate 5 is resiliently coupled to a work-table 2 by a rod 15 and washers 16, 17. The work-table 2 is moved in the X direction by the ram 8 and in the Y direction by the ram 14. The worktable is locked in a desired position in the X direction within the range of movement of washers 11, 12 by a threaded rod 19 engaging a half-nut 23 carried by the bed. The worktable is locked in the Y direction by a half-nut 30 engaging a rod 26. The work-table 2 has an extended frame 33 carrying a template carrier containing a hole pattern to be drilled, enclosed by dotted line 37. At the end of each row of holes is a control hole, the rows of control holes forming columns 38, 39. A light source 40 is mounted below the frame 33 and a photoelectric cell, not shown, is mounted directly above the frame. When a start button is pressed the Y half-nut 30 is released and the ram 14 moves work-table and template in the Y direction until the first control hole in column 38 is reached. The output from the photo-electric cell through a relay system causes the ram 14 to stop and the halfnut 30 to engage with rod 26. The half-nut 23 is then released and the hydraulic ram 8 moves the work-table 2 in the X direction until an output from the photo-electric cell indicates the presence of the first hole. The X lock is then engaged and through the relay system a drill-head, not shown, moves downwards to drill a hole in a printed circuit board, not shown, located on the work-plate. At the limit of travel of the drill-head, a micro-switch is operated to raise the drill-head and through the relay system override the signal from the photoelectric cell to cause the X lock to be released and the ram to move the work-table in the X direction. After drilling the last hole in the firt row, the work-table is driven in the X direction until a control hole in the column 39 is sensed. A micro-switch, not shown, having been operated by relative movement outside of the dotted line, the control hole causes the X lock to be engaged, the Y lock released and the ram 14 actuated to move the work-table in the Y direction until the next control hole is reached. The X drive is then actuated in the reverse direction and the template scanned in a zig-zag fashion. The hole pattern is arranged to have an even number of rows and the last hole sensed by the photo-electric cell is the last hole in column 38. The work-table is then moved in the Y direction until a Y upper limit micro-switch is reached which through the relay system causes the ram 14 to move the work-table downwards, the holes in column 38 having no effect, until the start position is reached at which the work-table is at the bottom limit of travel in the Y direction. In a modification, the system is provided with an information storage tape, an associated tape punch and a reader. The tape punch is controlled by a manually-operated keyboard to programme the desired hole-size for each hole in the drilling sequence. In operation, the tape is advanced one step by a microswitch actuated by the rising drill-head and the reader operates the turrent of the drill-head in preparation for the next hole. It is stated that the system can be employed for inserting components in a drilled printed circuit board by replacing the drill-head by a component insertion head fed from a suitable hopper. Further, the head can be fed from a plurality of hoppers selected in accordance with the information on a tape. The photo-electric cell and associated lamp can be replaced by a gas discharge nozzle located beneath the template, the pressure in the supply line being less when the nozzle is located beneath a hole; the control signals are derived from a pressureresponsive device in the supply line.