Patent GB-1238596-A (GB)
IPC: B21D11/07
Filed: 1969-06-06
Abstract: 1,238,596. Making resistors; angular bending. LA TELEMECANIQUE ELECTRIQUE. 6 June, 1969 [6 June, 1968], No. 28827/69. Headings B3A and B3E. A device for folding metal strip into serpentine form, suitable for making electrical resistors, comprises a series of linked members 7, Fig. 1, which define an upwardly opening groove 30 for supporting the strip, the members being pivotable transversely at a working station to fold the strip. The strip is fed from a coil 2, through straightening roller 5, and along a table 1 to a working station 10, 11. Each member 7, Fig. 12, comprises two metal plates held together at their thickened base portion 29 by screws 26. As a result each link has along its upper surface the groove 30 for holding the strip. The individual links 25 are hinged by passing a pin through the holes of two pairs of knuckles. The strip is folded at right angles by any suitable means so that it engages a groove provided between two plates projecting on top of cross-slide 9 so as to be level with the upper edge of the linked member 7. The initial condition is that in which the cross-slide 9 is pushed by jack 10 so that it activates contact 13 in order to displace carriage 11 towards the left as seen in Fig. 6 by an amount equal to the thickness of one link 25. Pushed by counterweight 61, Fig. 2, chain 43 follows the advance movement of the carriage so that members 7 are moved until hinged projections 38b meets contact 40. This contact stops the carriage 11 and activates jack 10 which starts pulling the cross-slide. At this moment the projection 38a has just left the gap between guides 6a, 6b so that the first link 25a, under the combined influence of the continuous thrust supplied by the counterweight 61 and the traction exercised by the jack 10, folds back against the plates defining the groove in the cross slide 9 in which the end of the strip is locked. When the cross-slide 9 has activated contact 12, the carriage 11 is displaced to the left as seen in Fig. 6. Thus carriage 11 and the member 7 move until the projection 38c actuates contact 41 which stops the carriage and activates the jack 10. The link 25b is then in a position to be folded against link 25a within the space between the wings of the cross-slide 7. When this folding operation is completed the projection 38c is touching contact 40 so that after the action of contact 13 has again set the carriage in motion, this movement will be stopped when the projection 38c meets contact 40. Thus the strip is folded to the required number of bends whereupon a powered vice compresses the container chains 25 and the folded strip is then extracted by activating pins 96. In order to make electrical resistors a folded section S1 is joined by a straight strip 100 to a folded section S 2 . The strip portion 100 is then folded to the shape shown in Fig. 18 by placing the portion 100 obliquely across a grooved die and applying a punch 109, Fig. 24. A limit switch detects the end of the operative movement of the punch 109 whereupon plates 117A and 117B are pushed by jacks 115 so as to bend the strip to form a looped shape. The formed loop is then flattened by placing it in a cavity 137, Fig. 27, and operating hammer 140 after which the hammer is pivoted away. Two flaps 132 are folded down towards one another by jacks 134 so that the sections S 1  and S 2  assume the position shown in Fig. 19.