Patent GB-741329-A (GB)
Title: Improvements in or relating to machines organised for stacking hides or skins
IPC: C14B1/62
Filed: 1953-04-29
Abstract: 741,329. Sheet-delivery apparatus. BRITISH UNITED SHOE MACHINERY CO.; Ltd. (United Shoe Machinery Corporation). April 28, 1954 [April 29, 1953], No. 11786/53. Class 100(1). A machine for stacking hide or skins which delivers the workpieces successively from a conveyer, a delivery end portion of which is caused to move to and fro across a work support to cause successive workpieces to be laid one upon another comprises a timing device for initiating movement of the end portion of the conveyer, the arrangement being such that one set of detector arms passes a signal to the timing device on the passage of one edge portion of a workpiece and a second set of detector arms passes a signal on the passage of the other edge of a workpiece so that movement of the end portion of the conveyer is initiated when a selected intermediate portion of a workpiece arrives at a predetermined position in the machine. As shown (Fig. 1) the machine for stacking skins is similar to that described in Specification 736,086 and comprises endless belts 10, 12 for conveying workpieces W upwardly along an inclined platform 11 to the delivery end portion B of a swinging conveyer for stacking over a support H. To trip a solenoid S to initiate movement of the end portion B when the centre of the workpieces have reached a predetermined position X a control system comprising a timing device and two detector stations is provided. The control system may be either mechanical or electronic. The detector stations are mounted on bars 16, 18 and comprise two sets of detector arms 20 adapted to operate switches 40, 42, 46, 48, the arm so associated with the switches 40, 42 serving to detect the passage of the leading edge of a workpiece and the arms 20 associated with the switches 46, 48 serving to detect the passage of the trailing edge of a workpiece (Fig. 7). In the mechanical form of control device an electric motor 58 is mounted on the bars 14 and is adapted continuously to drive a shaft 64 (Fig. 4) carrying gears 80, 82, the gear 80 meshing with a gear 78 on a shaft 74 and the gear 82 meshing with a gear 116 fast to a pin-wheel 120 rotatably mounted on a shaft 76. Pins 122 are arranged on the wheel 120, each having tapered heads. When a trailing edge is detected by the arm 20 a solenoid 52 is energized to operate a cam surface 114 to depress a pin 122. The gear 78 meshes with a gear 126 fast to the shaft 76 on which is fixed a ratchet wheel 132. Coaxial with the shaft 76 is a fixed shaft 134 to which a hub 137 is fixed. A spring 140 is coiled round the shaft 134, one end being fixed to a recess in the hub 137 and the other end being bent to engage a notch 146 formed in a bridge portion 147 of an arm 148. The arm 148 carries a bolt 160 which serves as a pivot for a ratchet lever 162 (Fig. 9) having arms 164, 166, 168. Pivoted on the bolt 160 are arms 170, 171. In order to engage the ratchet lever 164 with the ratchet wheel 132 a toggle arrangement is provided on the lever 168, adapted to be operated by one arm of a bell-crank lever 214 which is actuated by a solenoid 50 energized upon detection of the leading edge of a workpiece. In operation, in the case of a workpiece of shorter length than the distance between the two detector stations, the trailing edge of the workpiece is first detected causing a pin 122 on the wheel 120 to be depressed. When the leading edge of the workpiece is detected the ratchet lever 164 engages the ratchet wheel 132 so that the assembly on the arm 148 is rotated therewith, in the opposite direction to the pin wheel 120. The arrangement is such that when the centre of the workpiece has reached the point X (Fig. 1) the depressed pin 122 engages the arm 170 thereby rotating it to depress the plunger 194 of a switch 196 adapted to operate the solenoid S to initiate movement of the delivery conveyer B. At the same time the ratchet lever 164 will be rotated out of engagement with the ratchet wheel 132 and will return to its inoperative position under the action of the spring 142, a bumper 202 being provided. The arm 170 is provided with a bevelled edge 192 to allow passage of the depressed pin thereunder, the arm 170 being restored to its initial position by a spring 195, the movement being limited by the arm 171. The depressed pin is restored to its normal position by a bevelled face 165 on the arm 164. Bevelled faces 172, 174 on the arm 166 serve to restore into their normal position any pins which have been accidentally depressed, these faces being operative when the ratchet lever is disengaged from the ratchet-wheel. When workpieces longer than the distance between the two detector stations are being stacked the ratchet arm engages the ratchet wheel prior to the depression of one of the pins 122. In the electronic form of control device the switches 40, 42 and 46, 48 are connected in series with relays 258, 260 respectively (Fig. 18) which, when energized, serve to connect resistors 262, 264 across a charged condenser 250. When the condenser has discharged to a certain value, the time of discharge being in proportion to the time taken for the centre of the workpiece to travel a certain distance on the platform 11, the negative bias on a thyratron 276 is reduced to such a value that the tube fires, thereby energizing a relay 274, and consequently a relay 294 which forms part of a time delay device E. Energization of relay 294 allows a condenser 286 to discharge and thus remove the bias from a further thyratron 290 so that the tube 290 fires, energizes a relay 296, and consequently energizes the solenoid S. The resistors 262, 264 and 292 are adjusted so that the time taken from the beginning of the discharge of the condenser 250 to the time of energization of the solenoid S is equal to the time taken for the centre of the workpiece to arrive at the point X from its position when one of the edges of the workpiece was initially detected.