GB879262A - Improvements in or relating to work tables - Google Patents

Abstract

879,262. Punching-apparatus. KOLSTERBRANDES Ltd. June 6, 1958, No. 18146/58. Class 31 (2). [Also in Groups XXXVIII and XL (b)] In control apparatus for controlling the relative positions of two devices, e.g. a printed circuit board and a punch, a photo-electric detector arrangement detects opaque marks on a transparent plate mounted on a carriage to which the circuit board is attached and either brings into operation the punch, or in cooperation with carriage movement limit switches produces a change in the direction of drive of the carriage. A punch P operates on a circuit board 14 which is attached by arms 11 to a carriage 7 which can be driven along rods 6 in the Y direction by a velodyne VY. The rods are mounted in turned-up flanges 5 of a second carriage 4 which can be driven along rods 3 in the X direction by a velodyne VX. A photo-cell 9 receives light from a source 10 via a transparent plate 8 on which are positioned opaque markings a-l. Limit switches MS1 and MS2 are operated by carriage 7 in its extreme positions MS5 is operated by carriage 4 in the extreme Xb direction and MS4 is operated when a projection 20 on carriage 4 is almost in the extreme Xa direction. In operation the velodyne VX is energized and drives the carriage in the Xa direction until the opaque mark a interrupts the light incident on the photo-cell, the increase in cell resistance balances a bridge circuit which supplies via an amplifier the velodyne field coils. At balance the bridge circuit output falls to zero whereby the motor ceases to operate and a control relay also operated by the amplifier output releases and in conjunction with the operated condition of limit switch MS2 changes over the amplifier output to velodyne VY. The bridge circuit is.then unbalanced to provide an output from the amplifier to drive the carriage in the Ya direction, the unbalance condition being removed after a period sufficient for the carriage to be moved past the opaque mark a. The carriage is halted by the opaque mark b and with no limit switches operated the punch P is brought into operation and punches a hole in the circuit board at b1, when the punch is retracted the bridge is again unbalanced to commence the drive to position c at which point the punch operates on position c1 of the circuit board. At position d the bridge is balanced and stops velodyne VY, in addition switch MS1 operates and the combined effect changes over the amplifier output to velodyne VX and the carriage is driven to e. In this manner the carriage is driven along the dotted path indicated. Before arrival at opaque mark l projection 20 operates MS4 and at l velodyne VX is energized and drives the carriage in direction Xb to the home position, the operation ceasing when switch MS5 is operated.