Patent GB-1020972-A (GB)
Title: Improvements in automatic stacking methods and machines for flexible sheet articles
Inventor: FAREZ CLAUDE
IPC: C14B1/62
Filed: 1963-07-03
Abstract: 1,020,972. Endless conveyers; stacking machines. CHARVO S.A. July 3, 1963, No. 26426/63. Headings B8A and B8C. [Also in Divisions B6 and G1] The invention relates to a method for detecting the passage across a marking line, of the centre of gravity of sheet articles such as hides or skins 12 carried by a substantially transparent conveyer for example formed by wires 1, the marking line lying transversely across the longitudinal axis of the conveyer, more particularly for starting a mechanism which stacks the articles at the outlet end of the conveyer after a given time after the said centre of gravity has passed the said marking line, the method con-. sisting of causing the articles carried by the conveyer to pass in front of two light emitting surfaces 3 and 5 each extending across the full width of the conveyer and along a length thereof at least equal to half the length of the longest article required to be stacked, symmetrically with respect to the marking line and adjacent thereto, and of comparing the reduction caused by passage of an article in the light received from the said surfaces by photo-cells 66 and 68 through the conveyer and in determining the moment when this reduction is the same for both surfaces. In the arrangement shown in Figs. 1 and 3 the light emitting surfaces 3 and 5 are formed by ground glass plates forming the. top surfaces of boxes containing fluorescent strip lamps, and the'marking line is located on the longitudinal axis of an auxiliary light emitting surface 4 located between the surfaces 3 and 5. Light from the surfaces 3, 4 and 5 is directed to photo-cells 66, 67 and 68 respectively each being provided with a light collecting hood 9, 10 and 11 respectively. As a hide 12 passes along the conveyer 1 it successively influences the light received by the photo-cells 66, 67 and 68; when it reaches the position shown in Fig. 3 with its centre of gravity on the marking line at point X, photo-cells 66 and 68 receive substantially equal amounts of light. As shown in Fig. 4 the cells 66 and 68 are connected to an amplifier 13 whose output voltage is proportional to the difference between the output voltages of the cells 66 and 68. This resultant voltage is fed to a polarized relay 14 having a movable contact and fixed contacts 16 which are connected to a relay 17 having normally closed contacts which are used to connect a supply line 18 to a memory device 19. In the line 18 are normally closed contacts of a further relay 20 supplied by the photo-cell 67 such that the contacts are only open when the cell 67 is fully illuminated. In the absence of a hide on the conveyer 1, all the photo-cells receive light and thus the contacts of relay 20 are open and the moving contact 15 of'relay 14 is in the neutral position keeping the contacts of relay 17 closed, this condition preventing any signal from reaching the memory 19. When a hide appears over the surface 3 the resilient unbalance in the output signals from the photocells 66 and 68 causes the relay 14 to close the contacts 15, 16. When the hide reaches the position shown, photo-cells 66 and 68 receive equal amounts of light and the contact 15 returns to the neutral position thus closing the contacts of relay 17. In this position the photocell 67 receives a reduced amount of light, thus causing the contacts of relay 20 to close and allowing a signal to reach the memory 19. After passing the photo-cells 66, 67, 68 the hide drops on to a surface 22 travelling in the direction of the arrow, the surface being part of a second conveyer 21 which a predetermined time after the reception of a signal by the memory 19 and under the action of a circuit (Fig. 12, not shown) controlled by the memory moves in the direction of the arrow a predetermined distance and deposits the hide on a pallet or horse. It remains in this position until the memory has received another signal after which the conveyer moves in the opposite direction to the arrow, this reciprocating motion under the control of the memory and the direction of motion of the independently moving surface 22 causing the hides to be alternately deposited on the pallet with the grain side up and the flesh side up (Figs. 5 to 10, not shown).