twb

Advanced Tailor Welded Blank Forming Process

Tailor welded sheet metal parts refer to stampings where multiple metal sheets are welded together prior to the deep drawing process. This joining of various sheets into a single blank enables automobile designers to tailor the location in the blank where material properties are located leading to reduced weight, improved part stiffness, and lower manufacturing costs due to elimination of process dies and reduced scrap. While tailor welded parts are currently found in a few applications in industry, their utilization is limited due to formability concerns. Therefore, an advanced manufacturing process to improve the formability of TWBs was developed which will create multiple economic and environmental benefits.

The advanced tailor weld blank forming process uses opposing hydraulic cylinders above and below the blank to clamp near the weld line during forming. This reduces the strain concentration in the weaker, thinner material and weld line movement. In essence, the clamping mechanism acts as an additional binder force location in the center of the forming area. Therefore, this method may also be shown to improve the forming of non-tailor welded blank parts as well.

Numerical simulations were conducted to verify the benefits of this proposed advanced manufacturing process. Two cases were ran, a free case, where a traditional forming process was used, and a fixed case, where the advanced TWB forming process was incorporated. Results were extremely promising thus paving the way for experiments to be conducting (Kinsey et al. 2000).

Improvement in thickness reduction for a traditional forming case (left) and the advanced forming process case (right). Magenta area indicates excessive thinning of the material and thus tearing failure.

Experimental implementation of the advanced Tailor Welded Blank forming process also provided excellent results (Kinsey et al. 2001). Again, two cases were ran, free and fixed cases.

The traditional forming case with tearing failure after draw depth of 80 mm (left) compared to advanced forming process case with no failure and draw depth of 100 mm.

A 2D analytical model was also developed to determine the weld line movement, optimal initial weld line position, and forming height for TWB applications.

Patent

Jian Cao and Brad Kinsey (1999) Adaptive Method and Apparatus for Forming Tailor Welded Blanks, U.S. Patent No. 5,941,110.