Adapted medium frequency spot welding machine from DALEX - Highest welding quality and performance for satellite technology

In aeronautical engineering in particular, the components are sometimes somewhat larger. Simple standard machines are often not made for such dimensions. That's why a manufacturer of rocket propulsion components for satellite technology was looking for a suitable welding machine that could not only spot weld very large cylindrical tubes, but also meet the highest quality standards typical of the industry. At DALEX, the experts in automation technology and welding applications, the company found the powerful XXL solution - the adapted medium-frequency spot welding machine PMS 38-6 MF.

The task seems quite simple at first: reinforcing rings are to be inserted into tanks by means of spot welding. The tanks are made of cylindrical pipes. Up to this point, everything sounds standard, but far from it: The first challenge is the very high quality requirements, as the tanks are used in satellite technology for the construction of rocket propulsion parts. The second hurdle is the material to be welded, because the sheets for reinforcing the cylindrical tubes are made of aluminium. And the third and, in the truest sense of the word, the biggest peculiarity are the dimensions of the cylindrical tubes: the diameters are between 2,244 mm and 3,338 mm with a maximum length of 2,500 mm. This calls for an XXL solution - in terms of performance, quality and, last but not least, size.

Spot welding machine in maxi format

At DALEX, it was quickly agreed that the perfect basis for the Maxi welding machine was the PMS series. Christoph Desch, Sales Manager at DALEX GmbH: "The PMS welding machines were designed specifically for the high demands of industrial production in terms of performance, quality and reliability. Thanks to our modular system, we can quickly and easily modify the powerful standard machines for complex welding tasks. Supplemented by the special tools tailored to the application, the prerequisites for first-class and reproducible welding results are created and this with the highest productivity and economic efficiency."

Thus, the spot welding machine type PMS 38-6 MF in XXL format was developed for welding the oversized components. The machine is 3.5 m tall, has a machine throat depth of 1,850 mm and an oversized arm spacing to ensure maximum accessibility. Despite the considerable height, the machine is additionally placed on a 1.5 m high base at the end in order to realise the welding of the oversized parts. In order for the construction to withstand the increased loads, DALEX additionally reinforced the special machine frame. "We have built the entire spot welding machine very robustly: for example, the lower electrode arm and electrode holder have been precisely adapted to the requirements and are very sturdy," adds Christoph Desch.

The PMS 38-6 MF achieves a maximum electrode force of 4,500 daN. The construction of welding cylinders and many other components has always been one of DALEX's core competencies. Thanks to this extensive know-how, the components are created entirely in knowledge. All electrode force cylinders are designed according to the tandem principle with double air chambers and two working pistons. They also have precision guides and, with the sealing elements provided, guarantee optimal resetting behaviour. An additional guide pin behind the piston rod provides a safe protection against twisting.

Medium-frequency transformers from DALEX for highest quality

"In addition, the XXL spot welding machine is equipped with a medium frequency (MF) transformer with a rated power of 1,000 kVA from our own production - perfect for welding aluminium alloys," says Christoph Desch. In addition, medium-frequency technology offers numerous advantages over AC technology.

MF transformers from DALEX produce a high-quality direct current for welding that can be regulated quickly and precisely in the millisecond range. This leads to a high weld spot quality. Due to the low connected load and reduced energy requirements, the user also saves considerable costs, so that the somewhat higher purchase price due to the technology pays for itself very quickly. Further advantages are the fast regulation, low inductive losses, a low tendency to splash and the compact and lightweight design of the transformers. Furthermore, the high-performance transformers are thermally designed for multi-shift operation. This ensures maximum productivity and economic efficiency in production.

Christoph Desch: "After building the XXL spot welding machine, we carried out various test runs. The results were then directly tested intensively. In the process, the possibility of creating a micrograph at our own site was again a very big advantage for us. This way we achieve an optimal result - and the customer is more than satisfied."

Photo 1: In order to realise the welding of the oversized parts, DALEX placed the machine on an additional 1.5 m high base, despite the considerable height of 3.5 m.

Photo 2: In order to obtain an optimal welding result, DALEX carried out various test welds.

Photos: DALEX GmbH