Welding station for carriage walls

Przedsiębiorstwo Aparatury Spajalniczej ASPA is a leading domestic manufacturer of welders. Besides standard welders we offer stationary spot welders, suspended plier welders, butt-upset welders and projection welders as well as special equipment made to individual orders.

Many years of experience in designing and construction of such equipment is confirmed by fruitful and regular cooperation with renowned automotive, building and transport companies. A welding station for carriage walls equipped with ZP4PS DC welder is an example of a tailor-made piece of equipment.

ZP4PS enables DC resistance welding of materials which are hard to weld, such as some kinds of alloy steel, brass and aluminium.

The ZP4PS welder is a modern device which has a number of advantages over standard resistance welders, including:

  • symmetrical loading of three-phase power grid
  • 20% lower power consumption
  • power factor reduced to min. 0.85
  • improved weld quality owing to greater dynamics of the welding process
  • obtaining larger welds with no risk of cracking or chipping, and more universal process application
  • extended electrode life

The special welder for carriage wall elements enables welding different reinforcing, spacing and load-bearing brackets to flat sheet, e.g. a carriage wall with the maximum dimensions of 6000 mm x 1000 mm. An assembly with previously tacked elements intended for welding, fixed in the support with manual clamps, travels lengthwise, while the welder moves perpendicularly to the table.

The station consists of:

  • ZP4PS type three-phase DC spot welder
  • table with rollers to lay and move the welded elements
  • support for positioning, fixing and moving of an element to be welded
  • control cabinet with a system controlling the travel length of the welder and support with the welded element
  • water-cooling device (optionally)
  • system of guards and light barriers protecting the station operation

The welding process is controlled by a microprocessor control unit. The pressure force of the electrodes can be changed when the welding current flows.

The welding current is switched on and off by a thyristor switch. The welder is featured with a transformer-diode unit with three transformers and a rectifier diode assembly. The thyristor units, transformer-diode unit, secondary circuit elements and electrodes are cooled with water. Water flow through thyristor switches and transformer-diode unit are protected by water flow signalling devices, preventing current flow, if the water volume in the cooling circuits is too low.

The table support and welder lengthwise travel drive systems are featured with actuators, while absolute encoders control the speed and support of the welder arm and table.  The whole process of travelling and positioning is controlled by PLC, Simatic-S7 type. Communication with the operator is handled by software installed on the PC, playing the role of a visualising and reporting station. Inverters, PLC and computer are installed in the control cabinet, directly at the station. Programme collections, which define coordinates of different welding points and welding technologies, are loaded into the operator’s station e.g. via a disk and recorded in the database. It is possible to provide input data about welding points arrangement in a .DxF file format. The right wall to be welded is selected after entering a name (or type) under which it will be saved in the database. The PC directly controls the welding processes.

The system can operate in two modes:

  • manual – when the table and welder are controlled manually from the operator’s panel
  • automatic – when the table and welder are controlled automatically according to a set algorithm.

The equipment consists of two identical tables – a feeding and collecting one. They are both featured with rollers moving the welded elements. On one side of the table there is a moving support to position elements ready for welding and to move the elements. The support has a special construction suitable for holding the elements to be welded. The support and the welder are moved by actuators.