Flexible Coil Processing Line Adds Versatility While Opening Doors to New Customer

Keeping presses running, that’s the issue for stampers…and it drives “profit or loss” for the business. But how do you develop stamping lines to cover every possible part currently produced and versatility for future parts without breaking the bank?

This was a problem facing a Tier 1& 2 automotive metal stamper in today’s competitive business environment. But they found a way to add flexibility to their stamping lines to keep their current customers happy while expanding their stamping capabilities to bring in new ones.

Currently, the company is experiencing extremely high growth. The company produces parts that include assemblies and general stampings.  They’ll produce parts such as brackets, individual stampings or other types of critical sub assemblies. Currently the company operates a variety of transfer and progressive die type presses at their main location and employs over 300 employees. Almost 100% of their presses are set up with automated coil feed lines.

With customers clamoring for increased output, faster deliveries, and the company needing back-up lines to some of its more vital stamping operations, this stamper decided to develop a unique line that could process both progressive and transfer-type stamping operations.  The unique solution uses a mechanical press and a servo-driven 3-axis transfer system, as well as a high-capacity coil feeding system and an oscillating shear press from Coe Press Equipment Corp.

The coil feeding portion of the system consists of an AC servo-driven digital rollfeed (Model CPRF-772) with a maximum material width of 72” and thickness capacity of 0.250”. This “primary feed” is used for the cut-to-length and cut-to-shape blanking for the transfer die applications. Another “secondary feed” (Model CPRF-772) is powered into position within the line and used for the progressive die operations. Effective material straightening is provided by a free-standing power straightener (Model CPPS-406) with a 40 HP AC variable speed drive system. The coil handling is accomplished with a coil reel (Model CPR-PO-60072) that can handle coil weights up to 60,000 lbs. and coil widths up to 72” wide. For effective coil staging and coil changes, the reel is provided with a hydraulic traveling coil car (Model CPTCC-60072).

Downstream of the coil handling and feeding equipment, a Coe oscillating hydraulic shear press is utilized to produce both square-cut and trap-cut blanks. A unique toggle-link drive mechanism provides the motion for the press ram at speeds up to 30 strokes per minute. The shear press is provided with bow-tie type “bump-die” for shearing operations. The press base is provided with a pivoting mechanism that is driven by a precision multi-turn ball screw and an AC servo package.  Trapezoidal-shaped angles up to +/- 30 degrees can be produced with this machine to provide optimum material utilization with “net-shaped” blanks. A shifting magnetic blank eject conveyor is mounted to exit side of the shear press to positively drive the blanks clear of the shear blades.

Once blanks are produced in alternating right-hand and left-hand shapes, they must be properly oriented for presentation to the in-press 3-axis transfer system. A synchronized servo-driven conveyor system is utilized to index the blanks from station to station. The conveyors are mounted on a heavy-duty structural framework and use oriented-strand type belting and magnetic traction strips to positively index the blanks.  A servo-driven rotate station is used to rotate every other part to match the required in-press orientation. A universal suction cup tooling frame with a venturi-type vacuum system is used to pick-up the blanks and perform the rotate function.

The company says that they looked at alternative methods that handled blanks, but felt that they would have issues with a destacking system. Such issues included raw material costs, inventory control/deliveries, as well as handling blanks without damaging them. Another concern was that they needed to guarantee that no double-blanks would run through the press and damage the tooling. He also mentions that a dedicated transfer-style press system alone couldn’t do enough work to support itself at current sales volumes, but one that could do both transfer and progressive work and back up other press lines would allow them to recoup their investment.

He states, “We opted for this setup to get the most bang for the buck out of the entire line. At the time that we purchased the equipment, we didn’t have enough orders to fill the capacity in a transfer only cell. We knew we also needed to run it for various progressive die jobs.

He adds, “This cut-to-length line offers some unique advantages. You never have to really worry about doubling up blanks, because you know you’re only getting one part off the shear at a time. With the programmable oscillating shear press, we can take advantage of any kind of nested blanks, not fully developed blanks, but any kind of nested blanks where there is an advantage for material savings.”
Prior to purchasing the new line, the company had limited in-press transfer work. The sales department was providing lot of quote opportunities that required in-press part transfer, and either they could not quote it, or had to quote it as a progressive die job…and that wasn’t as competitive. He says the company felt that there should be enough work available to support a new in-press transfer line, and that’s what started the wheels rolling. By mid-July 2004, the company was performing die run-offs on the press, transfer, and coil feeding system.

The coil feeding system is provided with automation and features to provide efficient changeover and production operations. A Panelview 1000 color touch screen is provided for all line set-up, troubleshooting, and diagnostic functions. All part parameters and motorized machine functions are stored within the job recipe and downloaded with each part set-up.  Some of the unique features of this line include automatic coil centering and automatic back tension control. A laser system provides feedback to the PLC controls for both functions. The automatic coil centering feature reads the leading edge of the coil as it passes the laser and a resolver mounted to the coil car measures the exact distance to the center of the mandrel. The same laser is used to monitor the OD of the coil and modulate the brake backtension as the coil OD decreases to prevent material slippage and distortion.

With a 60,000 lbs. coil capacity, this line allows the stamper to optimize their coil size capacity.  The Manufacturing Engineer for the company says, “On another line, we have jobs that run up to 52” wide, and because the reel capacity is only 45,000 lbs. we have to limit the coil’s OD to 66”. With this line, we’re able to run much closer to the full capacity of the 72” OD, because the weight isn’t an issue. It allows us to be more efficient, and we don’t have to perform as many coil changes.”

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