Patent GB-918703-A (GB)
Title: Soldering apparatus for wiring boards
IPC: B23K3/06
Filed: 1960-06-29
Abstract: 918,703. Soldering wiring boards. WESTERN ELECTRIC CO. Inc. June 29, 1960 [July 1, 1959], No. 22714/60. Classes 83 (2) and 83 (4). In apparatus for soldering conductors on the underside of a wiring board, comprising a channel through which a constant stream of molten solder is maintained and a carriage for removably holding the board, means are provided to move the carriage to position the conductors in the stream of solder and for removing the board from the stream by a tilting action. A tank 10, Fig. 7, contains molten solder 11 which is pumped through a chamber 30 into a downwardly sloping channel 20 in a continuous stream, the tank being mounted below a carriage 36. The carriage has angle members 37, Fig. 4, engaged between rollers 38 on a cradle 39 so that the carriage may be moved longitudinally from the soldering position shown in solid lines in Fig. 1 to the unloading and loading position in broken lines and carries fixed holders 45 for one edge of the board and movable holders 48 operated by a lever 53 for the other edge. The cradle 39 comprises the roller carrying side members secured by a rod 61 whose outer ends extend through bearings in the ends 62 of arms 63 fixed to rocking members 72 pivoted on the main frame and rockable by an air cylinder 78 through linkages to move the cradle vertically. Blocks 64 mounted on the extreme ends of the rod 61 have guide rods 66 which extend through bushings 67 in the frame and move vertically therein during movement of the cradle. The cradle which carries counterbalance weights 70 has a shaft 90 carrying a cam follower 92 for engagement with two pairs of transversely spaced cams in a housing on the frame. One of the rear pair has a short surface to engage the follower in its up position and the other has a straight surface 98. One of the front pair has a fixed cam surface 102 while the other cam 104 is pivoted at 105 and is normally spring urged into an inoperative position by a spring 108. In operation with the carriage pulled forward to the loading position a soldered board is released by operating the lever 53 and a new board having components on one side with their leads engaging conductors on or partially embedded in the other surface, is held in place. The carriage is pushed to the soldering position where a switch 85 is engaged by the carriage to cause the cylinder 78 to lower the cradle. The cradle is lowered with the cam follower 92 engaging the surface 98 to position the board in the solder stream. When the cradle nears its lowermost position a lever 121 is actuated by a bracket 116 on the arm 63 to move the cam 104 to its operative position where it is held by a latch 107. A switch 88 is operated at the start of the soldering operation and causes after a timed period the reverse action of the cylinder 78 and the cradle is returned slowly against a dash pot with cam follower 92 engaging cam surfaces 102, 103. Initially the board is tilted to raise the front end, the solder washing the underside of the board to wipe out air pockets, and during the remainder of the upward travel the cradle is returned to its level position. Finally, the latch 107 is released and the cam 104 returns to its initial position.