NEW METHOD COULD REVOLUTIONISE VEHICLE MANUFACTURING
20 June 2006 - SSAB Tunnplåt AB

It permits the fabrication of sections with curved sides, conical shapes and variable profiles, which previously could only be achieved using much more expensive methods. In time, the new method promises substantial cost reductions in the fabrication of vehicle parts. The Monroe method has now received an honourable mention at the awards for this year's Swedish Steel Prize.

The Monroe method has been in practical use by the German company Bemo (which also took part in its development) for a couple of years. Bemo has used the variable roll-forming method on several very large and spectacular construction projects, in which custom-designed roofing and cladding sections were manufactured at high production rates by means of a mobile Monroe machine. The most recent project is the new Milan Fair with a total building area of 350,000 square metres, making it one of Europe's biggest fair complexes. Here the steel sheeting for some forty skylights of advanced design were manufactured on site by the mobile Monroe machine.

The success of the Monroe method is now opening the way to more efficient production in other industries as well. The automotive industry, for example, has used roll-forming for many years, but notwithstanding its economic advantages the method has suffered from being limited to the manufacture of straight sections.

"Generally speaking, roll-forming is an efficient and economical way of making sections at high production rates," says Lars Ingvarsson, CEO and owner of the Borlänge-based Ortic AB. "Its limitation has been that traditional roll-forming machines have fixed rollers. The difference with the Monroe machine is that we use rollers that are infinitely adjustable in various directions. This at once means we can produce parts that would have been quite unthinkable for roll-forming in the past."

Examples of vehicle parts that Lars Ingvarsson can envisage being fabricated by a Monroe roll-forming machine are the A and B pillars of vehicle cabins, which are often of curved shape. The Monroe method would also be suitable for many curved impact protection bars. The fact that these components are made of extra-high and ultra-high strength steel is not a problem, but actually an advantage according to Ingvarsson.

"Roll-forming is a near-optimal method of working high-strength steels, and the vehicle industry has a lot to gain from the Monroe method," says Lars Ingvarsson.

Notwithstanding the high production speed, the steel sheet is shaped relatively gently and gradually. The risk of cracks and other defects is therefore small, whilst tighter bending radii can be achieved than are possible with other methods. The stresses produced in the material by bending and pressing are much more severe.

Unlike the traditional roll-forming line with its fixed rollers, the Monroe machine has rollers that can be continuously and individually adjusted by means of computer-controlled electric motors.

"The concept of changing the position of the rollers during working is actually quite a simple and natural one," Lars Ingvarsson concludes. "The method is actually rather like manual forming, which can produce exactly tailored shapes. Now technology has made it possible to automate that process. For the user, the only limit to the shape of sections will be their imagination. Just about anything can be roll-formed."

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