Page 29 - MetalForming April 2016

eliminating the large electrical inrush of current.
All Hail Enhanced Hydraulics
Obviously, press performance rides on the performance of the hydraulic components as well—directional and proportional valves, the hydraulic oil and the pumps. First up for discussion with Greened Press’ hydraulics engi- neer Tim Wilson: the performance of modern directional valves. These units control the start, stop and direction of the hydraulic fluid throughout the press.
“What’s new here,” says Wilson, “is a significant increase in flow from valves with the standard ISO pattern, avoiding the once-common use of added DIN cartridges to meet the needs of high- demand, high-pressure applications.
“For presses,” he continues, “this makes for a cleaner design and allows press manufacturers to streamline the assembly process as well as simplify troubleshooting during startup at the customer’s facility. And, once the press enters production, maintenance is simplified.”
Position repeatability of press com- ponents also receives a boost from newer proportional directional valves, now almost always provided with onboard electronics. With more responsive higher-frequency voice coils (to 400 Hz, vs. 10-Hz coils that were common a few years ago), valves with the electronic components onboard improve accuracy and repeatability, provide faster valve action and they’re not as prone to electrical noise inter- ference, explains Wilson. Improved control of oil flow results in smoother press operation. And, for higher-speed presses, like those developed for hot forming, high-flow quick-acting pro- portional valves are a must.
“Also,” Wilson notes, “the valves fea- ture fully closed-loop control. They adjust themselves for temperature fluc- tuation, for example. And, for special applications, we easily can fine-tune the valves by custom-programming the valve’s firmware.”
Onboard Electronics
Pump control also has seen per- formance and cost improvements, due in large part to widespread use of onboard electronics, says Wilson. Pre- viously, flow and pressure control typ- ically were accomplished with controls ancillary to the pump. Now, pumps feature internal or manifold-mounted capabilities with internal controls.
Newer pump designs also run more
quietly than ever, and are more effi- cient, Wilson adds. For example, the economics of using servo-proportion- al control solutions on pumps, as well as valves, allow manufacturers to offer advanced press-control ability at a competitive price. Other advances: pumps with lower reaction times; sim- plified hydraulics; and newer accumu- lator systems that improve speed with- out increasing installed power. MF
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