Flexible cable guidance of a welding head in a friction stir welding machine

Customer requirements:

Grenzebach uses friction stir welding technology for high-quality welded joints. The welding head is the central component in the machine manufacturer's automated welding systems and is developed in-house by FSW experts.

FSW process - friction stir welding:
The FSW process can be used to realise media-proof connections, for example when welding heat exchangers and coolers. Since the material is welded in the plastic area there is also no structural change as in thermal welding. Therefore, FSW is ideal for the production of battery trays for electric vehicles. The process works like this: a wear-resistant, rotating tool is immersed in the material to be joined. This generates frictional heat, which makes the metal malleable. The two workpieces are stirred and compacted by the forward movement of the tool along the seam so that a firm joint is formed.

Since the tool must dip in and out of the material for each seam, the welding process should take place with as little interruption as possible. This requires a high degree of mobility of the welding head for some components, for example when the FSW system applies meandering seal welds to a component the size of a DIN A4 sheet. The welding head must then rotate at least 360° several times within 60 seconds, plus approach and departure movements and contours within the component. Ultimately, this requires rotability of +/-720°. All this takes place in a very small installation space - a challenge for energy supply systems.

igus solution:

The direct coupling of two twisterbands HD with two R4 energy chains and chainflex cables. The up to nine chainflex cables for the energy supply as well as the other media cables (such as cooling, sensor, servo and encoder cables) all have to accompany these rotary movements and are guided by energy chain tubes of the R4.28 series and the twisterbands HD of the TBHD.30 type. The twisterband HD is a strong, yet very compact, spiral-shaped energy chain for circular movements, with which rotations of up to 20 times around its own axis are possible. The twisterband allows for rotary movements of up to 7,000° on the horizontal plane and 3,000° on the vertical plane in an extremely small space, even at speeds of up to 180° per second. The system guides media cables as well as bus signals in an easy, uninterrupted and cost-effective way. In the HD version, the individual chain links are connected to each other by a pin-hook principle. This results in a defined bend radius and simultaneously ensures greater stability. In addition, the 24/7 design of the components guarantees low-maintenance and low-wear operation. When maintenance is necessary, simple and speedy replacement is possible.

"The solution is very robust and reliable," emphasises Alexander Feineis, Development Engineer at Grenzebach. "We have already carried out several endurance tests and have not yet had a failure, so we are looking forward to using the common cable supply solution in many more gantry machines in future."

Friction stir welding machine with the FSW process

Welding head with integrated twisterband HD and chainflex cables from igus

twisterband HD, energy tube R4.1 and chainflex cables