Special two-welding device for car subassemblies

OLYMPUS DIGITAL CAMERA

The special welding station was designed for welding screws and nuts with press-formed elements for the automotive sector. The main components of the station include:

  • body
  • welding instruments
  • control unit
  • electrical system

The whole station is divided into two sections, each supplied by its own transformer: left section – A, with six instruments, and right section – B, with five instruments.

The instruments are fixed to the station body on lightweight, paramagnetic aluminium panels resistant to moisture. Each instrument is featured with workpiece detectors which eliminate production errors (Poka Yoke). The station is cooled by 15 individual water cycles – 11 of them cool the instruments, while four separate ones cool the transformers, secondary current circuit and thyristor modules. The cooling system covers all electrodes in contact with the welded workpieces. The instruments ensure proper conditions of welded elements and positioning within the set tolerances.

The body is made of standard aluminium profiles, mainly square ones, with a 90 mm side length, which ensure a lightweight but rigid construction. The body offers a possibility of replacing the welding instruments with new ones – intended for welding of different workpieces. All elements ensuring the station operation are fixed to the body. They include: two transformers mounted under the instruments (as sources of energy), a power distribution system composed of water-cooled busbars, rotameter assembly of cooling water flow control, panels with instruments on the operator’s level, moving anti-spark guards above the actuators and 15 special welding actuators from Kolben-Seeger.

The controller unit is located in a control cabinet integrated with the station. It includes the main switch and operating panel with thyristor modules. The operation of the whole welding station is controlled by a Simatic S7 controller from Siemens. The operators communicate via the Siemens TP177B operator panel. The welding process parameters (current, time and pressure force) are controlled by a RATIA 73 IQ1 controller from Harms&Wende. Two TZSd transformers from ASPA, 160 kVA each, are the source of power. Water-cooled ASPA transformers are manufactured with a special technology and their quality has been appreciated by the domestic and foreign sector.

Station operation

The operator’s work involves arranging of workpieces and starting a welding cycle in the station section A. After pressing “Start” the anti-spark guard is closed and welding on the instruments begins. When section A is operating, workpieces should be placed in section B and welding in section B should start. In the meantime, welding in section A should be completed and a full working cycle can start again. The instruments in section A of the station perform welding in 12 cycles on 8 pressure actuators, while welding in section B of the station takes place in 11 cycles on 7 pressure actuators. Finished elements are discharged via troughs at the back of the station. The total circulation of the cooling water is controlled by a signalling device, which prevents welding if the quantity of the flowing water is not sufficient.

The paper was published in “Spajanie” magazine.

English