Patent GB-1234553-A (GB)
IPC: E04C5/01
Filed: 1969-09-05
Abstract: 1,234,553. Welding by pressure. E.V.G. ENTWICKLUNGSU. VERWERTUNGS G.m.b.H. 8 Sept., 1969 [21 Oct., 1968], No. 44259/69. Heading B3R. In a wire mesh welding machine having a row of welding heads which are movable laterally to adjust the spacing of the longitudinal wires, the heads are individually movable by a conveying device which acts transversely to the direction of advance of the longitudinal wires, the heads have means by which they can be selectively coupled to the conveying device and means are provided for individually controlling the coupling means of each head. The machine comprises two electric conductor rails 1, 1a connected to one or more transformers and a number of welding heads 50 which are slidable on the tail. Contact shoes 2, 2a separated by insulation 3 engage the rails, the shoe 2 supporting a first electrode 4 beneath the wire mesh and the shoe 2a being bolted to a piece 5 passing through the mesh plane and slidably connected to a thrust device 8. The device 8 contains a spring- loaded plunger pivotally carrying a bridge 9 carrying an electrode 6 opposed to electrode 4 and electrical connection from shoe 2a to the electrode 6 is by a projection 26 from the shoe 2a and a surface on the bridge 9. A guide tube 7 for a longitudinal wire is attached to the shoe 2a and piece 5 and a transverse wire stop 24 is provided on the head. A retractable block 11 in the device 8 allows the device to be engaged and disengaged with an oscillating thrust beam 12 driven by an eccentric 15. Transverse shafts 17, 17a support guide plates 18, 18a for transverse wires 19 to form a magazine, the outlet of which is controlled by a gate 20. A sweeper arm 26 sweeps transverse wires released from the magazine against the stop 24 and reciprocating hooks 38 advance the mesh. Electrohydraulically operated clamping devices 40 are provided for clamping the heads during welding to the rails. A conveying device in the form of a screw-threaded shaft 42 extends across the machine beneath a row of coupling pins 41 attached to the heads and to engage a particular head the respective pin is advanced to engage the shaft 42. A screw-threaded lever or internally threaded gripping device may replace the pin. When the head is advanced sufficiently, the pin &c. is disengaged and the head locked in place, these operations being controlled manually or by an automatic controller. Instead of a screw, an endless chain, cable or strip may be used, each head having means for positive or frictional coupling with the conveying device. The conveying device extends beyond the limits of the mesh so that heads may be parked in inoperative positions on the sides of the machine. Two conveying devices by screws may be provided, one for direction and one for the other and each head may be selectively coupled to either. An endless belt may provide for the same movements. To provide for automatic control of the coupling devices the shaft 42 is driven by a motor and gear-box and on the shaft is a pulse emitting disc, e.g. an optical device such as a perforated disc co-operating with a photo-cell or a magnetic device acting by induction. The pulses are delivered to a sensor which feeds them to a number of AND gates, one for each head, and when a coupling pin engages with the shaft an opening voltage is supplied to the appropriate gate. A pulse counter causes the pin to be retracted when a predetermined-number of pulses and thus a distance of movement of the head is completed. The period of coupling may be determined by a computer.