Page 21 - MetalForming September 2012

The servo-drive press stamps these seat side brackets, of 0.156-in.-thick 80-KSI high-strength low-alloy steel, two-out from 15-in.-wide strip over 10 die stations. While stamping the brack- ets on a conventional press created excessive snapthrough, the flexibility and controllability of the servo-press has reduced snapthrough to a manage- able 55 reverse-tons. Flatness on the part’s coined sections has been improved, and press speed has increased by more than 15 percent.
who we want to do business with, rather than always having the customer positioned to select us. Having servo- drive press technology helps us accom- plish that strategic goal. We can be more selective about the products we make, and the customers we serve.”
Leading the industry by innovating is in the company’s blood. Technical expertise helped it become an original Honda supplier in the mid-1980s, which, says Fledderman, “made us a better company. We were one of the first com- panies in Indiana to bring in wire-EDM technology, we were ahead of the indus- try in implementing CAD for tool design, and we also had early expertise forming difficult deep-drawn motor cases.”
Fast-forward to mid-2011 and it’s no surprise that Fledderman, his broth- er Jay (vice president of manufacturing) and the rest of the BTD management team saw servo-drive press technology as a ticket to a brighter future.
Removing Restrikes from the Equation
Summarizing its experience with the servo-drive press after running it in production, as well as in tryout to trou- bleshoot dies running on other press- es, BTD’s management team says, in concert: “We’re getting better part qual- ity and consistency, at a faster pace.”
Describing the first production job run on the servo-drive press, Jay Fled- derman describes the productivity and quality gain realized from moving a progressive die from a conventional 1200-ton press to the servo-drive press.
“The die stamps seat side brackets,” Fledderman says, “to the tune of 36,000 parts/week, about 20 percent of press capacity.” Brackets are of 0.156-in.- thick 80-KSI high-strength low-alloy steel. They’re stamped two-out from 15-in.-wide strip over 10 die stations.
“We had run the job for years on one
of our two 1200-ton presses,” he con- tinues, “learning to live with and com- pensate for as much as 145 tons of reverse tonnage. While the addition of
hydraulic dampers on the press brought snapthrough force down to 115 tons, our press operators and diesetters found the dampers
burdensome and cumbersome.” Moving the part to the servo-drive press and redesigning the process to reduce ram speed at certain portions of the stroke, during piercing and coining, brought snapthrough down to a man-
ageable 55 reverse tons.
“We’ve found the press to be extreme-
ly adjustable in terms of how many times within each stroke we can spec- ify ram speed,” says Robert Holtel, vice president of tooling. “This capability not only helps with snapthrough, but it also improves flatness on coined sec- tions of the bracket, and has reduced the amount of adjustments we need to make within the tool for the form shape. Before, the hit at the bottom of the stroke was so brief that we had to overform to control part dimensions on springback. This proved very incon- sistent. To get servo-press-like per- formance on the 1200-ton mechani- cal press, we would have had to add a couple of restrike stations to the die.
Watch this press run by viewing a 2-min. video in our Multimedia Center: www.metalformingmagazine.com/multimedia
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MetalForming/September 2012 19
BTD moved this deep-drawing job from a standard mechanical press to its servo-drive press and enjoys more than a 20 per- cent increase in throughput as a result. The servo press runs the part, of 0.085-in. cold-rolled steel, in the pendulum mode at 52 strokes/min. Critical toler- ances are the ID/OD, formed to ±0.006 in.
“With the servo-drive press, we nearly stop at bot- tom,” Holtel continues, “while overall cycle time has decreased by more than 15 percent, with the press run- ning at 40 strokes/min. Scrap rate is down, and we have fewer, if any, broken punches.”
Drawing at
50 Strokes/Min., and Tryout as Well
The BTD team also showed us another job moved to the servo-drive press from a standard mechanical press —deep drawing a high-vol- ume (2 million/yr.) auto- motive part. Now the job runs in the pendulum mode at a 10-in. stroke (maximum