Forming process using optimal blank shape. Credit: Kanazawa University
Researchers in Japan have developed a new simulation technique that may improve how car doors and other automotive parts are made.
A team from Kanazawa University have simulated the industrial process for stamping features into metal sheets without causing the sheets to tear, twist or bend, while optimizing the stamping press and reducing the costs of physically trialing designs.
The new simulation technique reduces the twisting of metal sheets by optimizing the shape of the blank shape or stamping stencil, while minimizing the tearing and wrinkling of the metal sheet by using variable blank holder force (VBHF) trajectory that the blank holder force (BHF) varies through the stroke. They also simulated how much force is used to clamp the metal sheet in place in the blank holder and how it should be varied during the punching process to optimize results.
“Sequential approximate optimization using a radial basis function network allowed us to efficiently optimize the blank shape and variable blank holder force trajectory,” first author Satoshi Kitayama said in a statement.
In recent years, automotive manufacturers have attempted to make each generation of vehicles lighter in an effort to improve fuel consumption, forgoing the traditional steel parts with lighter materials. One possible alternative is high-strength steel.
However, when sheets of high-strength steel are stamped into shape, they are often bent, torn, wrinkled or become too thin in places to be effectively used for car parts. The researchers believe their simulation technique could reduce the propensity of high-strength steel parts to twist and bend out of shape after being stamped.
Automotive manufacturers often carry out simulations in advance to optimize their tools before building and testing them, so they do not waste a lot of money conducting trial and error experiments. Without simulations, this trial-and-error period may force manufacturers to alter their tools in a costly and lengthy process before they are optimized for part fabrication.
Each tool has several different components that factor into the final product. While these tools can in theory be optimized with simulations, current simulations are not comprehensive enough and rarely factor the shape of the stamping stencil that the metal sheet is punched through to form the desired shape.
“We simulated the stamping of S-shapes into sheet metal. Unlike U-shapes, the stamping of S-shapes can cause the metal parts to twist out of shape, allowing us to study ways of reducing twisting springback,” study co-author Ryoto Ishizuki said in a statement.
The study was published in The International Journal of Advanced Manufacturing Technology.
