Page 35 - MetalForming August 2013

Friction Surf. 0.51 inch2 Stamp. Force 4.7 T
Friction Surf. 3.65 inch2 Stamp. Force 5.6 T
Friction Surf. 3.27 inch2 Stamp. Force 7.0 T
Friction Surf. 3.58 inch2 Stamp. Force 8.8 T
Friction Surf. 13.06 inch2 Stamp. Force 12 T
barber shop and hair
solon. To form the top
cover of the container,
Acro’s 110-ton servo
press performs a near-
ly 2-in. draw on a
4-in.-dia. blank of
0.012-in. stainless steel. The press also forms the stainless-steel strainer that sits inside the comb container. Both jobs had previously been offshored to China, and Wolfenberg is understand- ably quite proud to have reshored the work.
“We can draw the cover in one oper- ation in the servo press,” he notes, “impossible to do in a conventional mechanical press and much faster than if we were to run them in a hydraulic press.”
Acro was able to reshore the job thanks to the ability of the servo press to draw and form the prepolished stain- less steel without affecting its surface finish. Under previous production methods on a conventional press, the stamped parts required a costly and time-consuming secondary hand-fin- ishing process.
Cam-Actuated Operations, and Coining
Other additions to Acro’s resume, thanks to servo-press capabilities, include increased ability to perform in-die tapping, cam-actuated opera- tions and coining.
“When tapping, with the servo press, we can actuate the tapping operation at any point in the stroke, and control ram speed,” Wolfenberg says. “With a conventional press we only can tap during one portion of the stroke. We have much more flexibility in our process now.
“When coining,” Wolfenberg con- tinues, “we’ve been able to reduce 3⁄16- in. material to 3⁄32 in.—typically, the tool would just bounce in a conven- tional press. And, we’ve found that the ability of the servo press to slow or even pause mid-stroke allows cam- actuated forming during the stroke. We can bring a horn into the die, come down around it and retract the horn, all
“3D design with Logopress3 is the perfect complement to servo presses,” says Acro toolroom supervisor Jim Wobig. “It helps us visualize complex dies, eliminate stations and build the dies less expensively.”
in one stroke, eliminating a secondary operation.”
Acro performs this operation rou- tinely to form a J-shaped bracket. Wolfenberg explains: “The die is designed to form two 90-deg. bends, in separate planes. Typically each bend would require a separate press opera- tion. In the servo press, we form the first 90-deg. bend, and then use an air cylinder to help make the second bend. We then retract the cylinder and kick out the part—all in one stroke.”
Diminished Die Maintenance
The ability to perform more work per press stroke also has allowed Acro to simplify its tooling and eliminate stations from the complex progressive dies it designs and builds. “We’re typi- cally taking four- to five-station dies down to two or three stations,” says Acro toolroom supervisor Jim Wobig. Wobig quickly credits the firm’s move in 2010 to 3D die design (Logopress3) with helping the company leverage the flexibility of its servo presses.
“3D design with Logopress3 is the
perfect complement to servo presses,” Wobig says. “It helps us visualize com- plex dies, eliminate stations and build the dies less expensively.”
At the back end, Wobig also notes that die-maintenance costs have dropped dramatically when dies pre- viously run in the firm’s conventional mechanical presses move over to the servo presses. Some of the firm’s dies are more than 50 years old, used to stamp high volumes of electrical parts (500,000 or more) such as connectors and terminals. Says Wobig: “We’d often experience significant burr issues with these dies, and after a while we’d have trouble holding dimensional accuracy.”
Those problems caused dies to route to the toolroom for 4 to 5 hr. of main- tenance after every run. “With the added control over stroke rate and posi- tion,” says Wobig, “we’re now able to use those older dies for at least two production runs, or 1 million stamped parts, before they require maintenance. And, the maintenance required is much less intensive, requiring only about 2 hr. in the toolroom.” MF

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