Welding head for a machine for the formation of metal mesh, relative welding method and machine for the formation of metal mesh using said welding head

A welding head for the formation of a metal mesh comprising longitudinal wires and transverse wires, the head comprising at least a feed unit for feeding step-wise a plurality of said longitudinal wires, and a welding unit by which said longitudinal wires are welded to corresponding transverse wires, said welding unit comprising at least two electrodes selectively movable between a first feed position, in which at least a first electrode is distant from said transverse and longitudinal wires, and a second welding position, in which both the electrodes contact and grip said wires and apply different tensions in order to weld said wires to each other, wherein the welding head comprises at least a movement member operatively associated at least with the first electrode in order to move the first electrode between said first and said second positions, wherein the welding head further comprises a first position sensor associated with said movement member and configured to detect the position of the first electrode with respect to the two wires and to cause a reduction of the speed of movement of said first electrode when said first electrode is in a position near said wires, and a second and a third pressure sensors associated with the movement member, and configured to detect the working pressure of the first electrode when the first electrode contacts said wires and to cause the stoppage of the movement member when a pre-determined threshold of pressure is reached.

A method for the formation of a metal mesh consisting of longitudinal wires and transverse wires, by a welding head comprising at least a feed unit able to feed step-wise a plurality of said longitudinal wires, and a welding unit by which said longitudinal wires are fixed by welding to corresponding transverse wires, said welding unit comprising two electrodes selectively movable between a first feed position, in which at least a first electrode is distant from said transverse and longitudinal wires, and a second welding position, in which both the electrodes contact and grip said wires and apply different tensions in order to weld said wires to each other, wherein the method comprises at least a first step in which a movement member of the fluid-dynamic type, operatively associated at least with the first electrode, is moved between said first position to a second position near but not in contact with said wires, according to information detected by a first position sensor associated with said movement member and configured to detect the position of the first electrode with respect to the two wires, a second step in which, after having reached said position near to the wires, a reduction of speed of the movement member is determined, and a third step in which the first electrode is brought in contact with said wires with a pressure detected by second pressure sensors associated with the movement member and configured to detect the working pressure of the first electrode until a pre-determined threshold is reached.