Patent GB-1251070-A (GB)
IPC: B65G47/46
Filed: 1968-12-31
Abstract: 1,251,070. Stacking &c. workpieces; roller conveyer. WESTINGHOUSE ELECTRIC CORP. 31 Dec., 1968 [16 Jan., 1968], No. 61905/68. Headings B8A and B8C. [Also in Division G3] A depiler for distributing workpieces 82 disposed in a pile on a lift carriage 34 comprises reciprocatable means 48 for pushing workpieces across the top of the pile on to a receiving table 74, means for preventing movement of the lift carriage during operation of the means 48, motive means for the lift carriage and means for controlling the motive means for movement of the lift carriage by incremental steps upwards, whereby the workpieces are successively depiled and charged on to the receiving table from the top of the pile, and detecting means is provided disposed at a given level above and in proximity to a reference plane A of ejection of a workpiece from the pile on to the receiving table and below the plane C of operation of the means 48 on to the ejected workpiece, the detecting means being operable to detect the topmost surface B of the pile at a given level. The controlling means includes a computer having stored therein the successive values of the thicknesses of the piled workpieces from the top down, a digital displacement indicator responsive to movement of the lift carriage to provide a count representing displacement upward of the carriage, comparator means responsive to count of the digital indicator and to stored thickness count valve in the computer to derive a stop signal when compared counts are equal for stopping upward movement of the lift carriage, such upward movement being initiated by the detecting means detecting the topmost surface of the pile during initial movement of the lift carriage, the reciprocable means being actuated by the computer upon stopping of the upward movement of the lift carriage in response to the comparator means, upward movement being restarted upon completion of operation of the reciprocable means while initiating a count by the digital indicator for comparison with the associated stored thickness in the computer, whereby the pile is raised by incremental steps between successive operations of the reciprocatable means to eject a workpiece from the top in the reference plane, successively in accordance with the successive thicknesses stored in the computer. The system shown is intended for dealing with workpieces in the form of slabs and includes a slab receiving table 12 upon which a pile of the slabs is placed, the table 12 having slab lowering cradles 16 and being made up of a plurality of rollers 18 which are rotated by a drive motor 19 to convey the pile of slabs to the left on to tables 20 and 21, each made up of a plurality of rollers 22 driven by motors 24 and these convey the pile to the support table 28 which is capable of moving up and down. The table consists of rollers 30 supported upon the carriage 34 which is raised and lowered by the drive motors 38 which by gearing drive threaded shafts 36 to raise or lower the carriage so that the topmost slab is positioned at the correct height to be displaced on to the table 74 which includes a plurality of rollers 76 driven by a motor 78 and to move each slab received by the table 74 to the left, as shown, on to a table 88 made up of a plurality of rollers 90 from which it can be delivered into any of a plurality of furnaces 100. The reciprocatable means 48 consists of two pushers 50 which are driven forward and back by a motor 58 via gearing. The position of the threaded shafts 36 is sensed by a position detector 42 which detects the number of revolutions made by a shaft 39 which is driven by the motors 38. A speed detector 43 is also connected to the shaft 39 to detect its rotational velocity and hence the speed at which the table 28 is being raised or lowered. The speed detector is connected to a speed regulator which in turn is connected to a position regulator connected both to the position detector 42, to the computer and to a top of the pile detector 86 which is a photo-cell which receives a beam of radiation projected diagonally across the pile of slabs when this is not interrupted by the pile. The information fed to the position regulator enables it to move the pile of slabs so that the topmost slab is always in the correct position to be moved by the pushers on to the table 74. The pusher drive motor 58 is controlled so that it can only operate when the topmost slab is in the correct position, the motor being under the control of a pusher drive control which in turn is controlled by the computer. The pusher drive motor 58 is connected to a limit switch 72 which acts on a pusher extend detector to detect when the pushers 50 have been fully extended and the switch also acts as a pusher retract detector which indicates when the pushers are in the retracted position; the switch signals the computer when each operation is completed and it is only after the pushers have been withdrawn and the detector has provided a signal, that the lift motors 38 are activated to raise the pile. The movement of a slab 82 from the table 74 is indicated by a detector 104 which senses a beam of radiation emitted by a source 102, the member 82 breaking the beam as it leaves the table 74 and re-establishing the beam after its trailing edge has passed the beam; the detector 104 signals the computer to release the pusher drive motor 58.