GB1002282A - Improvements in or relating to machines for progressively performing a folding operation along marginal portions of workpieces - Google Patents

Abstract

1,002,282. Folding edges of non-metallic sheet material. BRITISH UNITED SHOE MACHINERY CO. Ltd. March 6, 1962 [April 18, 1961], No. 5914/65. Divided out of 1,002,281. Heading B5K. [Also in Division B2] A machine for folding the marginal portions of workpieces U comprises a workpiece support plate 516, operating instrumentalities including workpiece folding means 530, 532, a light source 590 arranged substantially above the plate 516, and sensing means comprising a plurality of light sensitive devices 622, 646, 648 arranged in association with the plate 516 and adapted to sense the presence of a workpiece U in the region of the operating instrumentalities and to sense the approach to said region of portions of the workpiece having appreciable edge curvature, the devices 622, 646, 648 being related to various ones of the operating instrumentalities in such manner as to initiate or bring about a change in their action on the workpiece. The operating instrumentalities are similar to those described in Specification 749,660 and comprise 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 a creaser foot 532. 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. A presser unit 546 is movable in a slot in the plate 516 and comprises a rocker arm 550 having an upstanding portion 552 to intermittently press the workpiece against the underside of the foot 532 to hold the workpiece during folding. The foot 532 is heated and adhesive is supplied from a receptacle 554 through a passage (not shown) in the foot 532 and extruded from a bevelled face therein to coat the underside of the margin immediately prior to the folding thereof. The flow is controlled by a valve 556 actuated by a Bowden wire 558 operable by a solenoid 560. The arm 550 is mounted on an outer end portion of a rock shaft 570 parallel to a main drive shaft 562 of the machine. A release arm 572 is secured to the inner end of the shaft 570 so that it can be rocked by an operator to lower the unit 546 when desired. A cam follower 574 on the arm 572 engages a cam 576 on the shaft 562 and is arranged so that rotation of the shaft 562 causes the portion 552 of the unit 546 to move into and out of engagement with the underside of the workpiece. A collar 578 integral with the cam 576 is adjustable with respect to the shaft 562 so that movements of the unit 546 may be adjusted in a cycle of operations of the machine. The light sensitive devices comprise photoelectric cells 622, 646, 648, Fig. 4, mounted in a plate 588 supported by the plate 516 and having an upper surface coplanar therewith. On presentation of the workpiece U to the machine with the edge to be folded against the gauge 526 and on closing of a treadle switch 642 to start the motor 568 for the shaft 562, light is cut off from the cell 622 to de-energize a relay K1 and close contacts K1B3, K1B2. Closure of the contact K1B3 energizes the solenoid 560 to open the valve 556 and cause adhesive to flow through the foot 532. The supply of adhesive is terminated when the workpiece U passes away from the cell 622. When the 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, Fig. 1, if the contact K1B2 is also closed. The solenoid 650 comprises a plunger 652 which operates the knife 540 to cause it to co-operate with the block 526 to snip marginal portions of the workpiece on the approach to the folding region. When the cell 648 becomes sufficiently uncovered by a 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. 7, 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. 9.