Production system for tubes with a wall thickness of up to 3 mm for KMH

KMH-KAMMANN METALLBAU GmbH & Co KG (KMH) in Bassum is one of Europe's leading manufacturers of tubes, components and systems made of steel and stainless steel for the transport of all types of bulk materials, exhaust air and dust extraction. The family-run, medium-sized company with 230 employees had long been looking for a fully automated system for the flexible production of high-quality tubes with material thicknesses of up to 3 mm. Working in partnership with KMH, Weil Technology designed and built the Variostar laser welding system customised to KMH's needs.

In this interview, Martina Kammann, CEO, Rainer Stöbis, Managing Director, and several KMH employees in Bassum explain their expectations of the Variostar and the advantages of production at the Bassum plant.

The Variostar is the desired compact system that produces reliably and precisely, is extremely flexible and guarantees high product quality, even for tubes with wall thicknesses of up to 3 mm. This enables KMH to produce and deliver just-in-time in a customer-orientated manner.

The fully automated production line includes a flexible roll forming station and a continuous longitudinal laser welding station. This allows sheet metal to be precisely combined into tubes in a highly efficient way in a continuous production line using roll forming and laser welding. The Variostar at KMH continuously covers a diameter range of 78 – 400 mm, tube lengths of up to 2,100 mm and material thicknesses of up to 3 mm. No tooling means quick retooling. As the seams are butt laser-welded, they are precisely and cleanly joined, highly corrosion-resistant and extremely stable. The roller bending process in the Variostar is particularly crucial for quality and efficiency. This is because the sheets are not only bent round, but also held precisely in shape during continuous welding. The seam runs under a stationary laser optic and must therefore be held absolutely evenly, butt to butt, without any twisting. This eliminates the need for time-consuming clamping before and unclamping after welding and ensures twist-free forming.

The fully automated, stepless adjustment of the diameters without tool change also contributes to the high productivity of the system. Individual data can be stored for each product variant for control purposes.