Grid welding machine and method for producing wire grids

A grid welding machine operating continuously based on the electrical resistance principle having a stationary longitudinal frame, whereon a horizontal group of parallel longitudinal wires can continuously be moved in the production direction by a feeding device, and having a pulling-off device, by which the cross wires can be pulled off a coil or rings and fed transversely to the group of longitudinal wires in a transfer device extending transversely, which transfer device can pick up multiple cross wires and convey them one after the other towards the longitudinal wires and bring them into contact with said longitudinal wires in the correct orientation according to the scaling of the cross wires and drop them there, and having electrodes and counter electrodes the weld surfaces of which can be pressed against each other with the points of intersection formed between the longitudinal wires and the cross wires therebetween, wherein both the upper electrodes and the lower counter electrodes are arranged on an inner frame mounted to said stationary frame and movable back and forth periodically in the longitudinal direction relative to said frame, and the upper electrodes are mounted to said movable frame for movement from an upper position downwards onto the points of intersection placed on the lower counter electrodes, wherein said electrodes reach a first lower position of the beginning welding process in contact with the points of intersection and then, while maintaining the contact pressure, travel along by moving the frame in the longitudinal direction together with the lower counter electrodes and synchronously with the grid into a second position of the ending welding process, which is at the same height level and in the rear with respect to the direction of flow, the electrodes and counter electrodes then reaching their former position with respect to the longitudinal direction again by moving the inner frame back, while the upper electrodes can first be moved vertically upwards and then again downwards into their former first position of the beginning welding process at the following cross wires, wherein the cross wires can be brought into contact with the group of longitudinal wires in the correct orientation by gripping fingers, wherein the gripping fingers provided for each of the weld points can be moved to the transfer device which picks up the multiple cross wires coming from the pull-off device for picking up the cross wires and can then be moved together with a picked-up cross wire to the points of intersection until the cross wire contacts the points of intersection at a time directly before the upper electrodes arrive and the gripping fingers, and then, by the movable frame, first travel alone along a first section before welding begins and then together with the electrodes and counter electrodes travel along another section of the horizontal path synchronously with the longitudinal wires of the grid to be formed, whereupon the synchronous travel of the electrodes and counter electrodes can be continued until welding is completed.