New German technique could transform cold-forming of sheet metals

Engineers have until now faced serious challenges in cold-forming steel, aluminium and other difficult materials in complex geometric forms as used in the aerospace sector, defence, wind turbines and a wide range of other industries.

It usually requires special tooling and a long, laborious process of bending in a series of steps in a press-brake or other type of machine. So far it has only been possible to bend material to preset angles or radii, and where the individual bending steps result in marks, which can damage the surface finish. 

Family firm

German company Dr. Hochstrate Maschinenbau has developed a revolutionary process using a modified version of its standard CNC bending machines. The company, based in Witten in the Ruhr area of Germany, is family owned with a tradition that goes back to the 19th century when it was founded to manufacture machines and equipment for the local coal-mining industry. In the past 40 years the head of the business Dr Gustav-Adolf Hochstrate and his son Wolfram have taken the company in a new direction with the development of radical technologies and machines for the cold-forming and shearing of sheet material. 

The new technology produces an optimum bending operation with a series of differing radii to produce cones and frustums of effectively any diameter. 

Apart from the flexibility and productivity, the process allows forming with virtually no surface marks, even in polished stainless steel, which is of major advantage in many applications.

For the bending of a conic profile, only the diameter and the height of the component need to be entered into the program. The bending process then proceeds almost completely automatically. It is only important to ensure that the initial cut dimensions of the sheet plate are exactly as required for the part to be manufactured. 

Adjustable angle 

The invention is characterised by the facility to adjust the angle of the upper beam and control the pressure from left to right or vice versa applied to the plate supported between the upper and lower beams. In this way non-parallel material, such as conic sections, can be clamped between the upper and lower beams. 

The upper beam is connected to its drives via bearings (pivot points) at the outer ends. One of these bearings is also designed to allow movement in the longitudinal axis of the upper beam to compensate for the difference in length when the upper beam is inclined.

The technology is already finding application in the defence and aerospace industries as well as in shipbuilding, and with construction, heavy vehicles and mining machine manufacturers.