Page 27 - MetalForming March 2010

have been optimized, including the cylinder’s ability to flex under load should die alignment become less than perfect. Previous generations of hydraulic systems used more rigid cylin- ders that restricted motion and required precise die alignment. Not so today.”
Also, state-of-the-art hydraulic sys- tems are more self contained than their predecessors, making them more user- friendly. The packages are much simpler to retrofit to existing dies.
“Metalformers can retrofit the self- contained hydraulic system to add ton- nage to an existing die,” says Bogre. “Or, consider the case of a stamper that must move a die from a press with a locking cushion to a press lacking such a cushion. To maintain the locking capability for the die, a hydraulic-system retrofit to eliminate the need for a lock- ing press cushion offers the perfect solu- tion. Having that delay technology as part of the die, rather than the press, provides additional flexibility. Other- wise, the work might have to be out- sourced to another stamper that has time on a press with a hydraulic cush- ion. Keep the force-control technology in the die, and any press can do the job.”
Benefiting New Die Builds
More significant benefits come from using the systems in new-die construc- tion, for those applications where “stam- pers want to be able to help their cus- tomers leverage opportunities to improve their part designs but may be limited in press tonnage,” says Hyson’s general manager Hank Kelm.
“We’re seeing increased interest in the technology from stampers dealing with advanced high-strength steels,” Kelm adds, “and for complex stampings that require controllable pad delay, with higher force requirement in a smaller space. This allows metalformers to help their customers push the envelope of product design, adding unique features that might not have been possible just a couple of years ago.”
“Hydraulic systems for managing force in the die,” adds Reilly, “help stam-
When a metalformer recently pur- chased a refurbished press to stamp truck components, it opted to replace the broken air cushion with three of these 84-ton, 12-in.-stroke hydraulic units, at a substantially lower cost than that required to repair the air cushion.
pers reduce costs in die designs, add value by improving their part designs, and, in many cases, take stations out of the die or maybe even avoid having to buy a new press.
“Yet one more trend,” Reilly contin- ues, “lies with companies that operate more than one stamping facility and look to move work among their plants. Keeping the delay technology with the die gives them the flexibility to do this. We recently experienced this with an appliance OEM that took a stove-top design developed and initially stamped in Italy. When the market for this prod- uct expanded into the United States, engineers studied best practices and determined that a pad delay was required. However, the U.S. supplier lacked available press time on its cush- ion-equipped presses, so, it added a delay system to the die using an all- hydraulic setup.”
Also Popular with HVAC OEMs
In addition to automotive and appli- ance stampers, HVAC OEMs and their suppliers have taken to using in-die
hydraulic systems to manage the force profile in the die.
“The new SEER ratings (Seasonal Energy-Efficiency Rating) handed down a few years ago,” says Kelm, “led to the development of thousands of new dies, many of which required delays due to complex part features and forms. Many of these new dies incorporated hydraulic force-control systems—in one case an OEM was able to significantly reduce blank size by 20 percent, result- ing in a return on investment for the hydraulic system much quicker than anticipated.”
Summarizing the benefits of recent developments that have made all- hydraulic control in the die accepted practice in stamping shops, Bogre says: “This is technology that allows the stamper to say ‘yes’ to product design- ers looking to gain an edge on their competition, and ‘yes’ to OEMs speci- fying the use of advanced high-strength steels.”
“And we’re not stopping there,” adds Kelm, describing continued develop- ment efforts underway to help stampers become more efficient and improve productivity. One of the more recent introductions is a press custhion that removes the variability of running dies on different presses.
“For example,” explains Kelm, “con- sider the common case of a die that’s been developed and tried out in one press, then is expected to run produc- tion on another press. Production press- es likely have a lot of wear and tear, guidance issues and other mechanical variations that can require the stamper to spend a lot of time tweaking a die that ran perfectly in tryout to get it to run in production. Next-generation press cushions will take that variability out of the equation, by being able to provide the identical force-distribution pattern regardless of the press the die runs in. This will ensure that dies will run per- fectly in production immediately after moving from tryout, significantly reduc- ing time to market and providing OEMs in any industry yet another competitive edge.” MF
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