A NUMERICAL STUDY ON CHANNEL DEFORMATION AND SPRINGBACK USING TOOL ROLLERS

摘要

A sudden increase in the usage of automotive vehicles residts in sudden increases in the fuel consumption which results in an increase in air pollution. To cope up with this challenge federal government is implying the stricter environmental regulation to decrease air pollution. To save from the environmental regulation penalty vehicle industry is researching innovation which would reduce vehicle weight and decrease the fuel consumption. Thus, the innovation related to light-weighting is not only an option anymore but became a mandatory necessity to decrease fuel consumption. To achieve this target, the industry has been looking at fabricating components from high strength to ultra-high strength steels or lightweight materials. With the usage of advanced high strength steels, the lightweight was achieved by reducing a gage thickness without compromising the strength aspect. However due to their high strength property often challenges occurred are higher machine tonnage requirement, sudden fracture, geometric defect, etc. The geometric defect comes from the elastic recovery of a material, which is also known as a springbuck. Springbuck is commonly known as a manufacturing defect due to the geometric error in the part, which would not be able to fit in the assembly without secondary operation or compensation in the forming process. It is learned that the springbuck of the material increases with an increase in the material strength and/or decrease in material thickness. In advanced high strength steels, higher strength and lower gage thickness options muke the part prone to higher springbuck. Due to these many challenges with the materials and their properties which uffect the springbuck, other research routes involved are innovative forming processes which would reduce the springbuck such as applying electricity through the material after forming and before the release of the load, performing warm or hot forming, die compensation, etc. One such innovative and patented process which is studied in the paper is using rollers in the tool i.e., in die and punch during the forming process. In this paper, the 2D channel strip of the aluminum 2024 high strength and thin material will be used in the bending processes. The process will be simulated in ABAQUS finite element software. First, the conventional channel bending process will be performed and springbuck will be analyzed as compared to the desired shape. Then the tool rollers will be implied to the die and punch corner radius and then the channel bending process will be performed and springbuck will be analyzed. The roller rotations will be set constant in this study, but the motion i.e., clockwise or counterclockwise in both die and punch will be studied on the springbuck of the channel. In addition, the no rotation of the roller effect on the springbuck will be studied and results will be compared. Further the maximum stress before and after springbuck and the stress distribution all cuses will be analyzed and presented.