What is in this article?:
- Supermaterial Press Improves Efficiency with Variable-Speed Pump Drive
- Unique Duty Cycle Prompts Sytronix Solution
- Multiple Efficiencies in Press Operation, Equipment
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Creating supermaterials, such as synthetic diamonds and super-hard metals, requires a super-powerful press. The press must be able to apply extreme pressures and temperatures—like those produced deep within the earth—to source materials such as graphite or diamond powders to trigger a series of complex chemical and mechanical transformations.
Supermaterial press technology has been the bailiwick of Novatek Inc., Provo, Utah, for more than 60 years. In fact, the company’s current four-kiloton solid-frame presses incorporate some of the most advanced press technology in the industry. Nonetheless, Novatek still sought to achieve more energy efficiency and flexibility, and turned to Bosch Rexroth’s Sytronix DFEn variable-speed pump drive system to deliver the hydraulic power for its two newest presses.
Tremendous Pressure from Six Directions at Once
Novatek built and operates ten four-kiloton, six-axis presses, creating supermaterials for applications ranging from drill bits to medical implants. Each press consists of a large, solid, cube-shaped alloy frame, 49.5 in. on each side, weighing 7.25 tons and mounted on a custom base. Six hydraulically driven cylindrical cartridges are positioned around all sides of the cube frame; each cartridge is tipped by a tungsten-carbide anvil.
During operation, a specially created cubic workpiece called a cell is placed in the center of the press. This cell, measuring 17.25 in.3, contains raw materials embedded in a pyrophyllite shell. With the raw materials inside, the cell is then compressed, crushed, and transformed by all six cylinder cartridges at once.
All six cylinders, which weigh nearly 9,000 lb each, contain proprietary Novatek technology and are driven into the center of the press by hydraulic pressure. They’re synchronized to meet within a few thousandths of an inch of each other as they precisely crush the work piece in a controlled manner.
As the work piece is compressed, a powerful electrical current simultaneously heats the cube up to 4,100° F. The combination of heat and pressure completes in 20 minutes what nature and time take millennia to achieve.
According to Michael Hall, head of production and process engineering at Novatek, one of the most challenging aspects of these presses is the rapidly changing demands on the hydraulic pump that’s driving the press.
“With these presses, in the first part of the cycle, we’re moving six large masses—the cylinders—many inches at high speed, under no load; there is no load until all six anvils meet and begin crushing the cube,” said Hall. “As this happens, everything’s going to slow down, but the compression from the cylinders is going up to eight million pounds, and we have to hold that, with no demand for flow, for an extended period.”
New Approach to Supplying Hydraulic Power
Eight of the presses, built since 1999, use hydraulic power units featuring conventional Bosch Rexroth components, including a 250cc A4VSO axial piston pump driven by an electric motor, proportional control valves, and a DRG pressure controller. Once the duty cycle on the press is initiated, the axial piston pump operates at a constant speed of 1800 rpm.
This equipment was provided to Novatek through Bosch Rexroth distributor partner Womack Machine Supply Co., Dallas, Texas. According to Womack Account Manager Riley Baker, when Novatek began planning two new presses, Womack and Bosch Rexroth had the opportunity to consider a more innovative hydraulic power solution.
“Novatek supplied us with a lot of data about the sequence of the machine, and how the press closed up and held for long periods of time,” said Baker.
Andrew Binversie, Bosch Rexroth sales manager for series presses, said their assessment indicated significant electric-power savings was possible with the Sytronix variable-speed pump drive system.
“When the press was holding pressure for 20 to 30 minutes, the total flow that accumulated on the pump, including leakage, was less than seven gallons a minute,” he said. “With that low of a flow and for that length of time, a variable-speed pump drive made perfect engineering sense.”