Page 18 - MetalForming December 2012

Transfer Press In
move it along the line, to any of three stations where we typically pull parts off, depending on the job.”
Dies are on a customer-specified preventive-maintenance schedule. “We send the transfer-line dies up to Exedy for inspection and maintenance after 60,000 hits,” says Price.
Seven Press Stations, Four Presses
Stamping the supports requires a more complex process involving seven press operations. Blanks—295-mm dia. and 2 mm thick, in lot sizes of around 9000—feed through all four presses in the transfer line for trimming, shaping, coining and flanging. Between presses one and two the transfer system spins the stampings 180 deg. and flips them over. Once the production run has completed, the plant executes a com- plete die change on the four-press line and the stampings run through three additional operations, feeding in the reverse direction along the line—left to right.
In all, between blanking, produc- tion stamping, and warehousing and shipping coils up to Exedy, Tennessee Steel processes an average of 5.7 million lb. of steel/month.
Following on the theme of “best- laid plans,” Price admits that produc- tion on its servo-transfer line, while smooth and relatively trouble-free, remains a work in progress. For starters, it had expected to receive new dies with the project. Instead, the dies it received were repurposed from press- es running in Japan.
“To get the dies to run in our line, we had to turn them 90 deg. on their base plates (compared to how they were running previously), and reengineer how we bring scrap out,” says Price
The scrap solution: Shakers pull scrap from under the dies toward the front of the line, where chutes direct the scrap down and under the press to a magnetic conveyor running along the back of the line.
A Transfer-Tooling Upgrade
Also a work in progress is maximiz-
A press operator visually inspects each sup- port as it exits the line, at a production rate of 13 parts/min. When the firm replaces magnetic transfer tooling with grippers and shovel-style tools, it expects to be able to kick throughput up by at least a few parts/min.
16 MetalForming/December 2012
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ing line speed and throughput. Cores run through the line at 15/min., while supports run at 13/min. Of note: all three jobs run through the press line completely free of stamping lubri- cant—mill oil only.
To enable a speed increase of anoth- er few parts/min., the plant is investing in new transfer tooling—grippers and shovel-style end effectors—to replace the existing magnetic tooling. The speed limiter using magnetic transfer tooling: “The blanks are never perfect- ly flat coming off the blanking press,” says Price, “particularly blanks at the leading and trailing ends of each coil. Without near-perfect flatness, we can’t dial up the speed without risking losing the grip on the work—especially the heavier support blanks. Shovels and grippers will avoid this issue.
“This tooling upgrade doesn’t come easily,” continues Price. “We have to reconfigure the dies to provide the tools access to the parts. But the
Seven press stations, over two setups, make these torque-converter support stampings. On the table sits parts as they exit stations one through four. Station one makes the hole cutouts, designed to provide just the right amount of material to allow the steel to flow properly throughout the remaining stations. Sta- tion two coins both sides of the part, and stations three and four stand up the forms. After a die change, the blanks are hand-fed back into the press line for pro- cessing at the remaining three stations.
expected increase in throughput will be well worth the investment. The goal all along has been to run the line at a 65-percent on time, and we’re closing in on 70 percent. We’ll easily surpass that when the new tooling is installed.”
MF