Patent GB-819969-A (GB)
Title: Improvements in or relating to assembling electrical components upon workpieces and in or relating to apparatus adapted for use therein
IPC: H05K13/04
Filed: 1956-05-22
Abstract: 819,969. Assembling electrical components on circuit boards. BRITISH UNITED SHOE MACHINERY CO. Ltd. May 22, 1956 [May 25, 1955; June 24, 1955], No. 15726/56. Addition to 802,659. Class 83 (2). Apparatus of the kind described in the parent Specification for assembling electrical components on printed circuit boards is provided at one station with means for automatically mounting a circuit board on a pallet and at a subsequent station, after the component assembling stations, with means for automatically removing the boards from the pallets. Each pallet P has, in addition to the trigger projection 794 and positioning pins 792 shown in the parent Specification, three tapering lugs 776 adapted to be received in locating holes G of the wiring boards W. Spring clips 798 and holes 791 (not shown) to receive pins on the board dismounting head are also provided. Board mounting head.-This comprises means mounted in front of and above the conveyer belts 370 for storing and successively transferring boards W on to successive pallets P and a carrier 64, co-operating with the transferring means, to deposit and detachably fasten each board to its pallet. The carrier 64 comprises a rectangular plate 66 secured to a threaded stem 68 which is secured to the lower end of an externally splined sleeve 72 slidable through a vertical bore in a 0-frame 96, said plate being cyclically reciprocable through levers 126, 124 and a link 122 from a compressed-air motor 118. Depending vertically from each end and the rear side of the plate 66 are pairs of spring fingers 78 with board-receiving notches 80, Fig. 10, and stop pins 82 respectively and from two diagonally disposed corners depend resilient pushers 84. A bracket 130, Fig. 1, bolted to the C-frame 96 carries a base plate 138 on which are mounted two parallel vertical U-shaped plates 142 spanned by a horizontal plate 144 which overhangs the front conveyer belt 730. Guide bars 146 mounted on the plate 144 define a passageway for a slide 148 by which wiring boards are fed from a vertical stack in a hopper defined by four vertical angle bars 158. When the slide is reciprocated by an air motor 178 through a bell-crank lever 184 against a return spring 199, a latch 156 carried by resilient strips 154 secured to a bar screwed to the underside of the slide engages the bottom board of the stack and moves it into the finger notches 80 of the carrier 64. Energization of a solenoid valve 114 then operates the motor 118 to cause the carrier to move downwardly towards a pallet clamped. in operating position at station A, the pushers 84 thrusting the board on to the registering lugs 776 until the ends of the clips 798 snap over the edges of the board to hold it flat on the pallet. For controlling the operation of the head, the bell-crank lever 184 has a pin 206 arranged to co-operate with two limit switches. Operation of the machine will be arrested if a wiring board does not depress a detector member 200 as the carrier 64 is lowered. The stem of the member 200 is adapted to operate, through a spring 272, a switch 274 mounted on a hollow cylinder 224 which is periodically raised prior to the descent of the carrier and whose maximum height is controlled by a hand wheel 232 and lever 230. Board dismounting head.-A frame 584 clamped to a plate 264 by a bolt 590, has a front portion formed as a cylinder to house board detaching mechanism and a rear portion to provide bearings for a pivotal shaft 592 controlling board receiving and removing means. Both parts are actuated by an air motor 593 having a piston rod 599 with a transverse pin 604 which extends through a vertical slot 606 in a vertically slidable cylinder 607 and also through slots 612 formed in parallel bell-crank levers 613 fulcrumed on a pin 614. The cylinder 607 carries a plate 609 having stabilizer pins 610 and detaching pins 611 adapted to pass through the holes 791 of a pallet P to disengage a wiring board W from the spring clips 798. The bell-crank levers 613 are connected by a cross rod 615 and a yielding adjustable link 616 to an arm 623 adapted to rotate a shaft 592 carrying an openbottomed receptacle 625. This receptacle comprises side guideway portions 626 set at an adjustable distance apart to accommodate different sized wiring boards and supporting lever 628 urged towards each other by springs 631. Stop screws determine the limits of movement of the receptacle. In operation, the receptacle is lowered to horizontal position, pins 611 pass through the pallet holes 791, detach a wiring board and raise it until it rests on ledges formed on the levers 628 of the receptacle which is then swung upwardly so that the board will slide rearwardly and downwardly to a shoot 655. It may happen that a board will be released from the pallet in a tilted position and it is then prevented from bouncing and is urged into a horizontal position by downwardly directed air jets from nozzles 658. Specification 802,658 also is referred to.