Pressure to get in shape

One aim of carmakers is to produce cars which are lighter and safer. However, strength and lightweight design are often at odds with one another. A new process could help: Hydroformed components are exceptionally rigid and impact-resistant.

Electric windows, air-conditioning, ABS braking and airbags have become standard features in most vehicles. But while electronic components increase the safety and comfort of cars, they also make them heavier; and the greater a cars weight, the higher its fuel consumption. One solution is to shed weight. Since few motorists are nowadays willing to do without such electronic gadgets, manufacturers are endeavoring to trim down the bodywork. Light metals such as aluminum and magnesium are used to replace heavier steels. However, this relies on the behavior of lightweight bodywork being equally as safe in crash situations. In this context, a new manufacturing process can make a valuable contribution: hydroforming.
Hydroforming is a process in which metal parts are pressed into shape under hydrostatic pressure. This means that the finished components are exceptionally rigid. Workpieces made of lighter materials can therefore offer the same degree of safety as components made of heavier material machined using conventional methods. This is what makes this process so attractive for lightweight construction, says Hans Bräunlich of the Fraunhofer Institute for Machine Tools and Forming Technology IWU in Chemnitz.
Hydroforming is not an altogether recent development. It is already being used in numerous industrial applications. A typical example is the production of T-joints, states the engineer. In the past, these components were welded; today, hydroforming is increasingly being used to give pipe fittings their correct shape. In this technique, a straight tubular blank is placed in a T-shaped tool. Axial punches are positioned at both ends of the workpiece in order to seal the component. Then a fluid is pumped into the pipe. Internal pressure builds up in the component and shapes the metal. The pipe yields within the tools preformed cavity - in a similar manner to cake mixture which expands to fit the shape of a cake tin. The axial punches exert a constant force on the pipe until the component is pressed into the same shape as the T-shaped mold.
Hydroforming is not only suitable for producing simple shapes such as T-joints but also for forming complex geometries, including automotive parts such as side rails, transverse links and cross-members. The advantage over conventional processes is that hydroforming cuts out otherwise needed, additional production stages, such as welding.,For further information,Dr. Hans Braunlich,Phone: +49 3 71 / 53 97-2 10,E-mail: [e-mail]
Fraunhofer-Institut fur Werkzeugmaschinen und Umformtechnik IWU,Reichenhainer Strasse 88,09126 Chemnitz, Germany,http://www.iwu.fraunhofer.de/english/index.htm

Paesi

Germany