Patent GB-1328191-A (GB)
Title: Apparatus for the continuous formation of regular stacks of flat workpieces
IPC: B65H33/12
Filed: 1971-01-08
Abstract: 1328191 Apparatus for the continuous formation of regular stacks of flat workpieces WINDMOLLER & HOLSCHER 8 Jan 1971 [27 Jan 1970] 1000/71 Heading B8C In an apparatus for the continuous formation of regular stacks of flat workpieces W such as flattened bags, or sacks, in overlapping formation the workpieces are gently bent as they pass between two equal-speed supply conveyer sections 1, 2 which are arranged at an angle to each other so that each workpiece trailing end strikes a sensor 8 to transmit a pulse to a counter 7 which at the number, for instance twenty, of workpieces necessary to form a stack, closes the switch 18 of a time delay 61 circuit so that the trailing edge of a twentieth workpiece W20<SP>1</SP> is stopped and gripped by a suction box 11. At the same time, in order to separate the already counted set of workpieces from the rest of the following row R of overlapping workpieces a feed conveyer 3, previously moving at the same speed as the conveyer sections 1, 2 to fling the counted set of workpieces W into a stacking magazine 1, having a conveyer base 5, is speeded up so that the workpieces which have already been counted and which are located below the workpiece W20<SP>1</SP> are pulled out from beneath the workpiece W20<SP>1</SP>, are separated from those accumulating on top of the workpiece W20<SP>1</SP>, and are quickly carried forward towards the magazine 1. As soon as sufficient time has elapsed for a side 4<SP>1</SP> of the magazine 1 to be pivoted upwardly in the direction of arrow b out of the way of a stack accumulated in the magazine and the conveyer 5 to remove the stack from the open magazine the time relay 61 operates the suction box 11 to release the workpiece W20<SP>1</SP> and return the feed conveyer 3 to its lower speed which is equivalent to that of the conveyer sections 1, 2 so that the spacing cycle is repeated. In response to twenty impulses from the counter 7 a magnet 20 releases a detent 21 from a locking disc 19 fixed to a cam disc 23 so that the latter completes one revolution due to a friction clutch drive 22 driven by the supply conveyer 1, 2 drive not shown, the cam closing the switch 18 only after the time required from the supply conveyer 1, 2 to move the trailing end of a workpiece from the sensor 8 up to the retaining means 11. The time relay control circuit includes an electromagnetic valve V12 in the suction box vacuum supply 13 and a two-stage, electromagnetically operable, twospeed mechanism 60 for the drive of the feed conveyer 3. A baffle plate 15, pivotable about a shaft 14, may be provided instead of, or in addition to, the suction box 11, a magnet 16, for operating the plate 15, which is adapted to hold the leading end of a workpiece, being included in the main circuit of the time relay 61 instead of, or in addition to, the valve V12. An upper belt 10 forms part of the conveyer section 1 and has a direction-changing roll 9 which serves as a pressure drum. In an alternative impulse restorer arrangement (51), Figs. 2, 3 (not shown), an endless chain (25), driven at the same speed as the conveyer section 2, has a plurality of transversely displaceable switching pins (26) and a magnet (29) which is controlled by the counting means and which is located at a distance y, which is equal to the distance x followed by a workpiece from the sensor to the retaining box 11, from a switch (30) which corresponds to the switch 18, Fig. 1. A stationary guide rail (32) pushes displaced pins (26<SP>1</SP>) back to their initial positions. In a further modification, Fig. 4, not shown, a single section conveyer (1) carries the row of workpieces to the feed conveyer (3) and the sensor 8 comprises an inclined step (33) the end of which projects upwardly beyond the conveying plane of the conveyer.