Welding Cycle Of Resistance Welding Machine
Welding cycle of resistance welding machine
Welding cycle of spot welding and convex welding consists of four basic phases (e.g., spot welding process):
1 Pre-pressure phase-electrode down to the current phase, to ensure that the electrode pressure workpiece, so that the workpiece between the appropriate pressure.
2 Welding time-welding current through the workpiece, resistance welding machine heat generation to form a fusion core.
3 Maintenance Time-cut off the welding current, the electrode pressure continues to the molten core solidification to sufficient strength.
4 time of repose-the electrodes begin to lift up to the electrodes and start to descend again, starting the next welding cycle.
In order to improve the performance of welded joints, precise welding sometimes requires one or more of the following to be added to the basic cycle:
1 increase the pre pressure to eliminate the gap between the thick workpiece, so that the close fitting.
2 using preheating pulse to improve the plasticity of the metal, so that the workpiece is easy to fit tightly and prevent splash; resistance welding machine when convex welding, this can make multiple convex points in contact with the flat before welding, in order to ensure the consistency of heating.
3 increase forging force to compacted core, prevent crack or shrinkage.
4 The quenching microstructure of alloy steel is eliminated by tempering or slow-cooling pulse, the mechanical property of the joint is improved, and the crack and shrinkage are prevented under the condition of no increase of forging force.
Type and scope of welding current
1. AC power can be made by amplitude modulation to slow up and slow down to achieve the purpose of preheating and cooling, resistance welding machine which is very advantageous for aluminum alloy welding. Alternating current can also be used for multiple pulse spot welding, which is used to allow cooling time between two or more pulses to control the heating speed. This method is mainly used in the welding of thick steel plate.
2. DC power is mainly used in the case of large current, because the DC welder mostly three-phase power supply, to avoid single-phase power supply when the three-phase load imbalance.