June 18, 2013
Press manufacturer Schuler recently held a convention in Waghäusel, Germany, where about 80 visitors heard from industry and academic experts about the latest developments in press hardening and other lightweight construction methods.
Use of press-hardened parts has grown from about 8 million pieces in 1997 to 124 million in 2010. In the next two years, demand is expected to almost quadruple to as many as 450 million pieces. The demand comes mainly from the automotive industry for such parts as bumper supports, roof frames, sills, B-columns, and tunnels.
"Blanks or preformed parts are heated in a furnace to a temperature of 930 degrees C," explained Schuler Sales Manager Jens Aspacher. "The heated blanks then have to be fed into the press as quickly as possible to prevent rapid air cooling." The press remains closed for a few additional seconds during the forming process so that parts can cool and harden. Cycle times are from 8 to 30 sec.
Once they have cooled down, the parts have a final tensile strength of up to 1,500 megapascal. Because of their high rigidity, less material is needed per part to ensure the same level of stability, thus reducing weight. Press force can be reduced to 400 to 1,200 metric tons — as compared to 2,500 to 3,000 metric tons — and springback is reduced.