GB1002281A - Improvements in or relating to machines for progressively operating on edge portionsof workpieces along a desired path - Google Patents

Abstract

1,002,281. Photo-electric path-follow apparatus. BRITISH UNITED SHOE MACHINERY CO. Ltd. March 6, 1962 [March 9, 1961:,April 18, 1961], No. 8492/62. Heading G1A. [Also in Divisions B2 and B5] A machine for progressively operating on edge portions of a workpiece U along a desired path comprises an operative instrumentality 532 to operate on the workpiece U at an operating position; work-feeding means 534, 536 to intermittently feed the workpiece past the instrumentality 532; steering means 524 arranged to engage the workpiece U at a single locality spaced from the operating position; presser means 546 between which and the instrumentality 532 relative movement may be brought about, during intervals between feeding of the workpiece U by the means 534, 536 so that the workpiece U may be gripped therebetween whereby to provide a turning centre about which the workpiece may be steered; and curvature sensing means 586 to detect curvature of edge portions of the workpiece U and to cause the steering means 524 to exert a steering torque on the workpiece U about the turning centre, in accordance with the curvature of said edge portions. The machine is in many respects similar to that described in Specification 749,600 for folding the marginal portions of workpieces and comprises a gauge block 526 to deflect upwardly the margin to be folded, a gauge finger 528, and a folding finger 530 to fold the margin against the operative instrumentality 532, in the form of a creaser foot. A hammer 534 co-operates with an anvil 536 to press the fold after it has been formed and also to feed the work intermittently past the block 526. A snipper knife 540 to operate on sharply incurved margins of'the workpiece is also provided. The steering means 524 comprises a single, continuously operative wheel 542 adapted to be reversibly rotated and having a serrated perimeter 544 to contact the upper surface of a workpiece at a single locality. Presser means 546 is movable in a slot in a workpiece support plate 516 and comprises a presser roll 548 co-operative with the perimeter 544 and a rocker arm 550 having an upstanding portion to intermittently press the workpiece against the underside of the creaser 532 to provide the turning centre about which the workpiece may be steered. The wheel 542 is continuously driven by a servomotor 584 under the control of the curvature sensing means which comprises a photo-cell 586 removably mounted in a plate 588 level with the upper surface of the plate 516. Light is provided by a lamp 590. In the curvature sensing circuit, a D.C. voltage is generated in the cell 586 and depends of the amount of the cell covered. Changes in the voltage are effected by changes in the curvature of the edge of the workpiece as it approaches the block 526. The motor 584 has an output shaft coupled to a reduction gearing (not shown) in a housing 600 which has an output shaft 604 depending therefrom. A rotary spindle 610 is coupled to the shaft 604 by a pin 608 sliding in a slot 606 and drives, through bevel gears, a stub shaft 616 carrying the wheel 542. This wheel is held in a raised position whilst a workpiece is introduced therebeneath by the energization of a solenoid 620 which raises its core 614 and consequently the wheel 542 against the action of a return spring 630. Screws 634 extending into slots 638 hold a sleeve 615 and hence the wheel 542 against movement about a vertical axis but allow the wheel 542 to move heightwise due to variation in the thickness of the workpiece U. On presentation of the workpiece U, e.g. a shoe upper, to the machine with the edge to be folded against the gauge 526 and on closing of a motor switch 640 and a treadle switch 642 to start the motor 568 for the shaft 562, light is cut off from a second photo-cell 622 in the plate 588 to de-energize a relay K1 and close contacts K1B1, K1B2 and K1B3 and open a contact K1A1. A time delay relay K2 is energized through the contact K1B2 and, after a fixed time delay, opens a contact K2B1 to de-energize the solenoid 620 and lower the wheel 542 after the workpiece U has been introduced thereunder. Closure of the contact K1B3 energizes the solenoid 560 to open the valve 556 and cause adhesive to flow through the creaser 532. The supply of adhesive is terminated when the workpiece U passes away from the cell 622. If it is desired to run the machine continuously, in place of the treadle switch 642, a push button PB may be depressed for starting or stopping the motor 568. When a third cell 646 is at least partially covered by an incurved marginal portion of the workpiece U, a relay K3 is energized to close a contact K3A1 to energize a solenoid 650 if the contact K1B2 is also closed. The solenoid 650 comprises a plunger 652 which operates the knife 540 to cause it to cooperate with the block 526 to snip marginal portions of the work piece U on the approach to the folding region. When a fourth cell 648 becomes sufficiently covered by marginal portion of the workpiece U having a sharp outside curvature, a relay K6 is energized to close a contact K6A1 to cause a solenoid 656 to act on an arm 658 against the action of a spring to rotate a feed control shaft 660 to shorten the length of feed (and folding) increments for an interval during which the portion of relatively sharp outside, curvature is being folded. At the termination of each machine operation the shaft 562 is preferably positioned with the finger 530 in its down position. When the switch 642 is released a small reversing D.C. voltage is applied to the motor 568 so that the shaft 562 starts to reverse and a cam plate 692, Fig. 8, straddling the cam 690 is radially displaced outwardly until a projection 698 pivots a lever 700 clockwise against a spring 706 and opens a switch 688 to stop the motor and the shaft 652 in a suitable position. The circuit for this operation is shown in Fig. 10. Specifications 962,160,989,874 and 1,002,282 also are referred to.