Wire Mesh Welding Machine

Overview

A wire mesh welding machine builds flat welded mesh by resistance-welding every point where a cross wire meets a longitudinal line wire. The line wires run continuously down the length of the machine while cross wires are laid across them one at a time; at each crossing a pair of electrodes presses the wires together and passes a current that fuses them. After a row is welded the mesh steps forward by one pitch and the next cross wire is welded, so the panel grows row by row until a shear cuts it to length. The output is the welded mesh used as concrete reinforcement, fencing, cages, and grating.

The line wires come from the Line Wire Feed and the cross wires from the Cross Wire Feed. The Welding Electrode Beam welds a whole row of crossings at once, powered by the Welding Transformer Bank. The Mesh Step Advance advances the mesh by one pitch between welds, the Mesh Shear cuts finished panels, and the Control System sets the geometry and weld energy. The Electrode Cooling system keeps the rows of electrodes from overheating.

Feeding line and cross wires

The longitudinal wires define the mesh and must arrive straight and evenly spaced. The Line Wire Feed runs one Line Decoiler per line wire, and the Line Straightener Bank bank works the curl out of each with its Straightening Roller rollers. A Spacing Comb comb fixes the pitch between wires, and the Line Wire Clamp holds them still during each weld so they cannot creep.

The cross wires are made one at a time. The Cross Wire Feed pulls wire from its Cross Decoiler, straightens it through the Cross Straightener, and the Cross Wire Cutter crops it to the mesh width. The Drop Chute and Placer then lays the cut wire square across all the line wires at the next pitch position, ready for the beam to come down.

Welding a full row at once

The defining feature of a mesh welder is that it welds every crossing in a row simultaneously. The Welding Electrode Beam carries a full-width row of electrode pairs: an Upper Electrode above and a Lower Electrode below each line wire, held in cooled Electrode Holder units. Each pair has its own Electrode Cylinder so weld force is even and electrodes can be lifted out where a wire is skipped to change the pattern.

Current comes from the Welding Transformer Bank. Several Welding Transformer units each feed a group of crossings, because a single transformer cannot supply a wide mesh evenly. Each transformer has a laminated Transformer Core, a Primary Winding, and a low-turn Secondary Winding, and is switched by an SCR Contactor so the controller can phase-control the energy into each zone. The Secondary Busbar secondary connects each transformer to its electrode group.

Step advance, shearing, and cutoff

Between welds the mesh must move forward by exactly one pitch, accurately, or the mesh openings will not be square. The Mesh Step Advance does this: a Step Carriage running on a Ball Screw and Linear Guide Rail rails carries two Step Gripper jaws that grip the leading cross wire, pull the mesh one pitch, release, and return for the next bite, driven by a Servo Motor.

When the programmed number of cross wires for a panel is welded, the Mesh Shear cuts the mesh free. The Shear Cylinder drives a full-width Shear Blade through every line wire at once against the Shear Anvil, and the finished panel slides onto the Run-off Table.

Materials and construction

Line and cross wires are cold-drawn low-carbon steel, ribbed for reinforcement mesh or plain and often galvanized for fencing. Electrodes are CuCrZr alloy, which keeps conductivity and hardness at the temperature the weld zone reaches; they wear at the tip and are dressed or swapped on a schedule. The Base Weldment is a heavy steel structure because the weld beam force and step accuracy depend on a frame that does not flex. The whole work zone, where wires drop and the beam closes, sits behind interlocked Sheet Metal Panel guarding.

Variants and use

Machines are sized by mesh width and wire diameter. A reinforcement-mesh line makes wide panels of ribbed bar at standard pitches for concrete slabs, walls, and precast; a fence-mesh machine makes lighter galvanized mesh in fixed patterns at high speed. Pitch is programmable on better machines, set at the Control System, so one line can run several mesh patterns by skipping line wires through their Electrode Cylinder units and changing the step. Reinforcement mesh follows standards for bar size and spacing, and the Weld Controller logs current per zone so weld strength can be verified. The welded mesh that comes off these lines reinforces almost all modern concrete and forms a large share of industrial and security fencing.

Control and cooling

The Control System runs the line. A PLC sequences cross-wire placement, beam close, weld, step, and shear with interlocks, while the Weld Controller fires each SCR Contactor and holds weld energy per zone using feedback from Current Sensor units, since a wide mesh can need different current at the edges than the centre. Operators set wire sizes, pitch, panel length, and weld parameters at the LCD Panel. Because many electrode pairs pass high current at a steady cycle rate, the Electrode Cooling system runs continuously: the Coolant Pump feeds water to every holder and busbar and the Heat Exchanger sheds the heat, holding electrode temperature so weld quality stays even from the first row of a shift to the last.