Page 47 - MetalForming June 2013

they did what is known as a one-step simulation, a relatively fast directional indicator of potential forming issues. The process serves as a compass for early feasibility to a product engineer— a mere substitute for not having an experienced die engineer review the design early in the development process.
Simply, a one-step simulation math- ematically calculates strains by taking a finished part to a flat blank in one step—sort of like dropping an anvil on a stamping to see if it splits. Hardcore finite-element-analysis (FEA) profes- sionals may have an issue with this characterization, but the point is that one-step technology is not accurate enough to determine production risk of whether a die process, die architecture and blank can stamp product from HSLA or DP steel under production conditions without splits or wrinkles.
In addition to a one-step simula- tion, shops can opt for a multi-step simulation—a series of one-step sim- ulations that enables an engineer to segregate drawn features from flanged features, such as return flanges. At the die shop, you need a map—not a com- pass—to navigate your way from quote to buyoff.
Incremental forming-simulation software is as close to standing at the tryout press as you can get. This simu- lation technology digitally replicates the actual forming process. It requires form-tool surfaces and mechanics, and blank geometry. The software uses the tools and blank to calculate formabil- ity throughout the sheet thickness dur- ing each fractional increment of press stroke.
Software Platforms
Incremental forming-simulation software platforms are built around two types of users: the FEA expert and your average everyday die guy. The FEA platforms require an expert to create what is known as a mesh; mesh size helps to determine simulation accu- racy. The software still requires engi- neered form-tool geometry and a blank. Meanwhile, software platforms designed for the average die guy auto-
mate meshing tasks.
So, how do you know which plat-
form is right for you? Those that actu- ally know what the phrase “transversal shear stress” means and can use it in a sentence should typically opt for the FEA platform. Otherwise, I recommend using software that automates the meshing procedure.
The software brand choice may already be decided for you depending
upon your customer base. Some com- panies—VW and BMW, for example— govern the software brand for their incremental forming simulations.
Keep in mind that most FEA experts can successfully use any of the soft- ware brands on the market, provided that the die processing is performed in CAD by a die guy. The converse is typ- ically not true: Most die guys struggle to use the FEA-driven simulation brands
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