Systems offered for forming high-strength steels Through the hot forming process, high-strength steels gain higher rigidity and good forming characteristics can be combined with high rigidity levels. Hot forming (or hot stamping) is an innovative process for manufacturing highly rigid parts while reducing both blank thickness and weight. It plays a major role in lightweight auto manufacturing, where the aim is to reduce vehicle weight while enhancing the rigidity of safety-relevant parts.

In contrast to the cold forming of higher- and high-strength steels, the parts are hardened by the hot stamping and subsequent cooling process itself.

In this way, steels with an original strength of 500 to 800N/mm2 can achieve a rigidity of 1,300 to 1,700N/mm2 after heating, forming and cooling.

When unhardened, these steels are less rigid and display much better forming characteristics.

Through the hot forming process, however, the materials gain higher rigidity than higher- and high-strength steels.

Good forming characteristics can therefore be combined with high rigidity levels.

The blanks are rolled through continuous furnaces and heated to approx.

950 deg C.

Pre-formed parts can also be processed by transporting them through the furnace in special racks.

A robot or special transfer system - equipped with grippers rather than suction cups due to the temperature - then feeds the blanks into the press.

This feeding action must be extremely fast, in order to avoid too much cooling and any scaling on the blank.

The forming process is then undertaken by a water-cooled die with press forces of 8000kN to 12MN (800 to 1,200 tonf) and speeds of up to 300mm/sec.

In order to guarantee good part accuracy and even hardening, the part remains some eight to ten seconds under pressure in the closed and cooled die after the actual forming process.

This allows the part temperature to fall to about 150 deg to 200 deg C.

Over the last ten years, Schuler has supplied a number of hot stamping lines to the automotive industry.