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One of the causes of rejections for part breakage on automotive sheet steels at stamping plants is insufficient pre-applied lubricant (prelube) on the blank. There are several key processes that occur after the prelube is applied at the steel facility that can affect the prelube amount and distribution before the blank is stamped. To understand the effects of these key processes, a controlled study was performed to examine the effects of prelube application level, coiling, coil storage, blanking, lift storage, and blankwashing on the amount and distribution of prelube. After mill application, the prelube migrates from the center to the edge resulting in reduced oil levels (“dry spots”) in the center of the coil or blank. It was found that coiling and coil storage had the greatest effect on prelube migration. Extended lift storage resulted in continued reduction in prelube level at the center of the blank, but at a decreased rate.

Dent resistance is one of the major requirements for automotive body panel design. It depends on material strength, thickness, panel geometry/shape and outer and inner panel assembling. Due to the complexity of the problem, the verification of dent resistance of body panels is often done after the panels are formed and assembled. In this paper, a computer simulation technique was developed for dent resistance predictions, which can potentially be used in early design stages before panels are produced. Simulation techniques are discussed using explicit finite element method (FEA) for forming simulation and implicit FEA for denting simulation. A lab stretch dome panel is used to demonstrate the feasibility of computer simulation for dent resistance prediction. The stretch dome panel, with double curvature geometry, is formed to 2% biaxial strain and then subjected to several incremental static loads until 0.2 mm dent depth is reached.

It is known that the formability of tailored welded blanks depends on the welding set-up conditions. Little information is available on the correlation between the formability of welded blanks and weld set-up conditions. In this investigation, effects of mash seam welding parameters of weld current, weld force, material overlap and planish on formability performance of welded blanks are studied. The systematic design of experiments approach is used to identify the key weld parameters influencing the formability performance of welded blanks. It is found that high weld force decreases formability of welded blanks and high weld force coupled with a small material overlap results in very low forming limit of the weld zone. Weld current has little effect on formability of welded blanks and planishing significantly reduces it. Overall, the mash seam welded blanks produced with appropriate weld set-up conditions are robust with respect to formability.

Tubular hydroforming is being used extensively for manufacturing various automotive structural parts due to its weight reduction and cost saving potentials. The use of a thin wall advanced high strength steel (AHSS) tube offers great potential to further expand hydroforming applications to upper body components. In this study, numerical and experimental investigations are conducted on a free expansion hydroforming case using various AHSS thin wall tubes. The results are also compared with tubes made from conventional steels and different tubing processes. The appropriate use of the forming limit in hydroforming is also discussed. In numerical study, a new simulation method is developed and validated to handle tube material properties input. Good correlations to the experimental data have been obtained. The new method only requires the flat sheet stress–strain curves as the basic material property. Tube and weld properties are modeled as a pre-strained tubular blank.

A design of experiments is used to study the effect of laser weld parameters on formability of welded blanks for two different material combinations of cold rolled (bare) steel to cold rolled steel and cold rolled steel to hot dipped galvanized steel. Critical weld parameters influencing the formability of welded blanks are identified and the optimum weld set-up condition is obtained based on formability performance and consistency of formability for laser welded blanks. The results are applied to an automotive body side frame. The robustness of welded blank production is also assessed and the final welded set-up condition for the body side frame is obtained based on both the formability of welded blanks and the robustness of welded blank production. The body side frame is successfully made from the welded blanks with this final weld set-up condition.