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

Profile:

System: Friction stir welding machine
Operating time: 24 hours per day, 7 days per week
Industry: Machine tools
Customer requirement: Very small installation space, low maintenance, requires rotatability by +/-720 degrees
Our solution: twisterband HD, closed energy tube from the R4 series

The bronze vector award goes to Grenzebach Maschinenbau GmbH. The connecting structure and media supply in friction stir welding machines must be just as flexible as the welding head itself.

Problem

Grenzbach relies on friction stir welding technology for welding seams with excellent specifications. Developed in-house by FSW experts, the welding head is the central component in the machine manufacturer's automated welding systems.

FSW process - friction stir welding:
The FSW process can be used to realise media-proof connections, for example when welding heat exchangers and coolers. As the material is welded in the plastic range, there is no structural change as with thermal welding. Therefore, FSW is ideal for the production of battery trays for electric vehicles. This is how it works: 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 strong joint is formed.

As the tool has to dip in and out of the material for each seam, the welding process should take place with as little interruption as possible. For some components, this requires a high degree of flexibility of the welding head, for example when the FSW system applies meander-shaped weld seals to a component the size of a DIN A4 sheet. The welding head must then rotate at least 360° several times within 60 seconds, and carry out approach and departure movements and contours within the component. This ultimately requires a rotation of +/-720°. All this takes place in a very small installation space - a challenge for the energy supply.

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, sensors, servo and encoder cables, which must all be able to cope with these rotational movements, are guided through energy chain tubes of the R4.28 series and TBHD.30-type twisterbands HD. The twisterband HD is a strong, yet very compact, spiral-shaped energy chain for circular movements, with rotations of up to 20 times around its own axis. With the twisterband, rotational movements of up to 7,000° horizontally and 3,000° vertically are possible in the smallest of spaces, even at speeds of up to 180°/s. Media cables and bus signals can be guided in an easy, uninterrupted and cost-effective way. In the HD version, the individual chain links are connected to each other using a pin-hook principle. This results in a defined bend radius and greater stability. In addition, the 24/7 design of the components ensures low-maintenance and low-wear operation. Replacement is quick and easy when servicing is required.

"The solution is very robust and reliable," emphasises Alexander Feineis, Development Engineer at Grenzbach. "We have already carried out several endurance tests without a failure, so we are looking forward to being able to use the joint energy supply solution in many more gantry machines in future."

To twisterband HD