Patent GB-883683-A (GB)
Title: Improvements in or relating to machines adapted for use in assembling electrical components upon workpieces
IPC: H05K13/04
Filed: 1958-02-12
Abstract: 883,683. Assembling electrical components on circuit boards. BRITISH UNITED SHOE MACHINERY CO. Ltd. Feb. 12, 1958 [Feb. 13, 1957], No. 4543/58. Class 83 (2). A machine for assembling electrical components on circuit boards comprises reciprocable forming means, a component support having former elements shaped to provide lead-engaging abutment surfaces and body positioning means, the forming means being arranged to co-operate with the former elements to bend the leads prior to insertion in the holes of the board and transfer means arranged to present a component to the support, to the body positioning means and also to the abutment surface of the former elements. The machine comprises a hollow C-shaped frame 34, Fig. 1, housing in a front portion of its base lead clinching means 36 and at the rear an air motor 38, while an inserting head is clamped to the overhanging portion. The lead cutting, forming and inserting means within the head are operated from the piston rod 44 of the motor 38 through a link 50 and a lever 52 fuicrumed to the frame at 54, which lever is limited in its clockwise movement by a stop nut 58 and which in turn actuates a lever 60 also fulcrumed at 54 and adjustable relatively to the lever 52 by screws 64, 62. A link 68 connects lever 60 with the component inserting bar 70. The upper part of the head comprises a sleeve 74, Fig. 2, adjustably held in the frame 34 by an arcuate clamp 76 and a latch 80, 84 and the lower part comprises a casing 88 of U-shape in cross-section, the open side being closed by a cover plate 90. Movable with the bar 70 for the first part of its downward movement by means of a ball detent 100, 102 is a holder 92, Fig. 8, for two shear bars 94 whose distance apart may be adjusted for trimming the leads of different components. The ends of the bars have lead-positioning notches 116 and in operation co-operate with adjustable shear blocks 108 having lead-supporting surfaces and being adjustably mounted on the cover plate 90. A support 122 for positioning a component in the lead cutting and forming position comprises an interchangeable spacer block 128 and inside former elements 132 mounted on a lever 124 which is pivoted at 126 to the cover plate 90 and is normally urged counterclockwise by a spring so that it engages a cam slot 278 in the rear of the inserting bar 70. Outside former elements 150 are secured to a block 148 adjustably screwed to a holder 142 slidably mounted in front of the bar 70 within the casing 88. Initially the holder 142 is moved with the bar 70 by a ball detent but after the leads have been cut and bent, the holder is arrested by stops 162. As the bar descends, the lever 124 pivots about pin 126 into the cam slot 278 so that the elements 132 swing out of the path of the bar and of the outside formers so that the components can be carried down to the wiring board, the leads being frictionally held in grooves in the elements 150. Also secured to the bar 70 is a member 152 with legs arranged to bear on the shoulders of the formed leads after the arrest of the outside former 150 and to thrust the leads through the holes in the board. The lower limit of movement of the bar 70 and the upper limit of the piston rod 44 are determined by a cross rod 168, Fig. 19, abutting a stop 170 in the frame 34. Transfer means. Components are fed to the support 122 by a transfer carriage 201 comprising a pair of split levers 200 having pins 198 mounted in pitmans 196 and being slotted to receive rods 208, 210 along which are adjustably clamped V-shaped holders 220, lead-positioning arms 232 with plates 236 adapted to straddle the inside former elements 132 and arms 240 with lead-deflecting surfaces 242. A plate 228 and centre block 224 afford rigidity to the carriage. On receiving a component, the carriage can be rocked about the pins 198 as it is moved towards the support 122, thereby positioning the component on the support. Movement of the carriage is controlled by rolls 202, Fig. 4, on levers 200 engaging in fixed cam slots 204 and is effected from a piston and cylinder assembly 178 which acts through rod 180, pivoted yoke 184, arms 188 and triangular levers 190 having rollers 192 slidably engaging in slots 194 in the pistons 196. As the carriage moves the component to the support 122, a latch lever 252 is depressed thereby allowing a spring 168 to pivot a block 264 to which is clamped a finger 250 adapted to yieldingly hold a component in position as shown in Fig. 5. A switch M3 is then closed by an arm 270 to effect admission of air to the cylinder 174 to return the carriage 201 to the Fig. 4 position. The finger 250 is subsequently restored to its inoperative position by the descent of the inserting bar 70, the lower end of which engages a re-setting lever 284. Components secured together by an adhesive tape T are fed from a reel 310 into a raceway 314 comprising two pairs of tracks 316, 318 which are adjustably supported from the casing 88 by a series of wing screws so as to be readily adapted for the feeding of components of different sizes as shown in Figs. 11, 11a and 12. The setting of the tracks is facilitated by gauge marks provided on slotted horizontal and vertical cross bars. Vertically adjustable on the cross bar 330 is an L-shaped arm 356 carrying a stripping finger 358, Fig. 4, adapted to bear on the tape T as it is drawn away from the path of the components in the raceway and around a pair of rollers 360, 362 by a reel 420 which is rotated by pawl and ratchet mechanism, the pawl being actuated by levers from the carriage 201. Pressure of components in the raceway acts on supporting feeler fingers 450 which through a pin 452, levers 451 and 455 close a normally open switch M2 and thus through a solenoid effect the disengaging of the pawl driving the reel 420 to interrupt the feed. When the fingers 450 are depressed the lowermost component in the slideway may be ejected by two pusher fingers 476, 478 on a movable carriage 480 operated by a lever 498 for the first part of the ejection stroke and then by a spring 494 until the carriage abuts the frame 410. Each ejected component is thrust downwardly from the delivery end of the raceway by a pair of spring fingers 517. If there are components missing from the tape, depression of the feeler fingers 450 is assured by a cam surface 520 engaging a pin 454 in the lever 451. As an additional safeguard against overfeeding the tape, the feed may include a self-locking device comprising a wedge-shaped arm 522 adapted to clamp the tape against a spring-backed plunger 528. Lead clinching means. An anvil device adapted to rise and support the underside of the circuit board during the insertion of the leads of a component is actuated by a toggle 544, 546, Fig. 19, which is coupled through a link 542, lever 538 and link 536 with the link 50. A spring 551 normally keeps the anvil in its lower position which is adjustable by a screw 554. The anvil comprises a carrier 548 movable on a bracket 550 and having a cylinder 556 housing a piston 558 which may be raised pneumatically against a spring 560 to lift pins 566. Each pin is vertically slidable within a bushing 568 to the upper part of which is pivoted at 574 a clinching finger 572 which when engaged by a pin 566 pivots against the action of a spring 576 so that its upper end engages and bends over the projecting end of a component lead L, Fig. 23. By adjusting the bushings 568 about their axes, the leads can be bent over in independently selected directions. The amount of bend is adjustable by a screw which limits the movement of the piston 558. Compresesd air is supplied to beneath the piston 558 from a pipe 600 through ports in the bracket 550 so positioned that the supply is effected only after the anvil carrier 548 has been raised. The machine is controlled by a parallel-type electric circuit in the manner described in Specification 819,969. Specifications 802,658 and 802,659 also are referred to.