Page 48 - MetalForming April 2016

Tool Design and Build Made SIMple
benefit in using simulation for this springback challenge.
“Very seldom do we see mild-steel parts anymore,” Mason continues. “AutoForm’s solvers recognize the hard- ening that occurs as high-strength materials are being formed, known as kinematic hardening, as well as other problems such as sidewall curl and splits in secondary operations. Even with all of the new challenges encoun- tered when working with high-strength materials, iterations are performed sev- eral times more quickly than before.
“We do all of our tryouts here, all of our quality loops where we have to recut the shape of the tool to compen- sate for material movement during forming,” he continues. “I’d say we have cut out 50 percent of the quality loops on a majority of our parts by attacking springback in simulation.”
To add even more accuracy and speed to the process, Walker tests its part material and uses the properties gleaned to generate specific stress-
hardening curves, which it imports directly into AutoForm.
“That’s a big benefit as opposed to just using a generic curve, and gives us the best results,” says Mason.
Trim-Line Optimization Adds Accuracy, Cuts Modeling Time
Trim-line optimization is another area where simulation software shines for Walker.
AutoForm-TrimPlus in combination with AutoForm-SolverPlus is used to help determine blank outlines and to ease the tryout of trimming dies by finding the optimum trim line. The trim line is optimized to ensure that the desired shape and dimensions of the part boundary are obtained at the end of those operations that follow the trim- ming operation. AutoForm-Trim- Plus automatically adjusts the trim line to remove or add sheetmetal until the desired part boundary is achieved.
“The software evolves our trim line behind the scenes so that we don’t have
to perform all of that manually,” says Mason. “That can save us upfront in modeling time.”
Optimum blank outline is impor- tant when near-net-shape manufac- turing (crash forming). The blank out- line is optimized to ensure that the desired shape and dimensions of the part boundary are obtained at the end of the crash-forming process. The advantage of incremental over an inverse one-step simulation, which also can be used to find the blank out- line, is the consideration of not only one, but several forming steps, and results in much greater accuracy, according to AutoForm officials.
Walker Tool and Die also uses Auto- Form during the quoting stage for dif- ficult parts.
“We use it to prove feasibility and to propose product changes for parts that are not formable,” Mason says. “The software is used to obtain an accurate blank as well as for estimating press tonnage.” MF
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46 MetalForming/April 2016
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