Pulsed Current Arc Welding



The resistance pulsed current arc welding is a modified resistance welding process featuring high reproducibility of each welding as well as low operating costs. 

The welding is effected by a combination of mechanical pressure and electric energy, whereby both values are kept at level by control circuits. This means to possibly concentrate the weld current at welding area in order to minimize unnecessary heat loss. 

  • high welding energy
  • short welding time

How to achieve this can be explained with a simplified diagram:



Energy of pulsed current arc welding
Prinziple diagram pulsed current arc welding

The weld energy is collected in a storage condenser [C] and subsequently unloaded via high-performance thyristor [V] into welding transformer [T], which then is generating the secondary high-current pulse of multiple 100.000 A lasting just milliseconds necessary for the welding.

Suitable weld projections provide a high transition resistance and force the energy flow onto this small contact area of weld pieces. This way a current density is achieved, bringing the weld projection to melt and the mechanical pressure finally provides a uniform structure of the weld joint.

 

Advantages



  • exactly controlled welding energy via controlled condenser load
  • welding in milliseconds, hardly any tarnishings respectively thermal load of weld joint surroundings
  • release of supply nets, because of welding from condenser battery.

The weld pulse commonly looks like following:



Graphical time response of pulsed current arc welding
Schematic diagram pulsed current arc welding

Depending on capacity and type of appliance the welding time [t1- t2] takes between 4 and 12 ms. Since the energy almost exclusively effects the welding zone and this with only extremely short impact, the characteristics of the surrounding material is hardly effected. 

In case fringed areas have become brittle by the heat impact due to very high energies, a defined second pulse can reverse this effect.