Page 21 - Metalforming Magazine April 2022

tion. H13, for example, commonly used in diecasting applications, also has found a home in hot stamping. Off- shoots of H13 with higher alloy content, he reports, have made inroads as well.
“The hot stamping process is so unique: placing a heated blank into a die, shaping it at a rapid rate and trying to achieve the final needed dimensions,” Bell says. “The die mate- rial involves three considerations dur- ing hot stamping: conductivity, or time needed to heat and cool the material; hot wear, or how much wear will occur at higher temperatures; and conformal cooling, the ability to run cooling lines through the die and dis- sipate the heat.
“Conductivity doesn’t really enter the conversation in cold stamping, but in hot stamping, it’s a huge factor in how quickly a line can cycle,” Bell con- tinues. “The die must cool and recover before it can cycle again. And, from a metallurgy standing, running a die super hot can cause it to anneal and soften. As for hot wear, the big hot stampers study this and much of the data is proprietary as to how these materials wear at high temperatures.”
Additive manufacturing (AM) may provide an answer to cooling chal-
development process.”
The result: affordable and user-
friendly incremental forming-simula- tion software running inside of para- metric die-design software.
“The forming-simulation software no longer is disconnected from the die- design software,” Proeber explains. “Better yet, incremental forming sim- ulation can be run at the initial strip- layout stage of die design. This not only eliminates finding mistakes during try- out after designing and building the die, but also during die design itself, as the formability information needed is known before design begins.”
Similarly, Proeber sees integration of more tools into die-design software to automate the process and to perform mechanical debugging of a die prior to ordering die-build material.
“The die can be run in a virtual forming-simulation tryout press while still at the strip-layout stage via incre- mental forming-simulation software,” says Proeber, “and after all of the actual tooling is designed around the strip layout, the die runs in a virtual motion- simulation press to find mechanical mistakes in the die itself.”
Automation within die-design soft- ware further eliminates mistakes, according to Proeber. One example: Automatic creation of the bill of mate- rials within minutes.
“Such automation speeds die design, build and tryout by eliminating the time needed to perform such chores as well as to identify mistakes and fix them prior to build,” he says.
Previously, with strip-feeding and formability problems addressed in a tryout press, die designers would begin developing the flat blank. Always a large consumer of press time, notes
This series of same-part
tion prior to die build. A.
wrinkles appear on this part as well as jagged edges after forming in a tryout press. B. Here, incremental forming simulation within the die- design software used at the strip-layout stage shows wrinkles form- ing as the press is closing. C. A draw pad added during simulation confirms its effectiveness in preventing the part from wrinkling as the press closes. D. The first hit in a tryout press after simulating the part in the die-design software produces a part without wrinkling, and the automatic blank development produces a finished part that is accu- rate per print.
lenges, as the process allows for man- ufacturing conformal-cooling lines directly into the die.
“Imagine a hot stamping die section about half the size of desk, which is pretty large,” Bell says. “Placing con- formal-cooling lines within that die to cool the die quickly between cycles gains huge efficiencies.”
The limitation here: insert size.
“AM typically can’t produce inserts in large sizes, as AM-machine work envelopes are relatively small,” Bell offers. “But that’s changing. As soon as I say that the envelopes are too small, we’ll probably see a machine with an envelope size capable of producing a die block.”
Die Design/Sim. Automation Combats Experience Loss
As with other facets of manufactur- ing, die design, build and repair have been challenged by the loss of experi- enced tool and die professionals and fewer entrants into the trade. This has caused developers of incremental forming-simulation software to team up with developers of parametric die- design software, according to Ray Proe- ber, president of Accurate Die Design Software.
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A
B
C
D
“Customers com- monly require incre- mental forming sim- ulation on parts prior to die build,” Proeber says. “Developers of die design-and form- ing-simulation soft- ware recognize the need to perform sim- ulation more quickly and make it an inte- gral part of the die-
images illustrates the importance of simula- From a die built without using simulation,