An emerging challenge for the extrusion press industry is older hydraulics technology. Many presses continue using inefficient and unreliable hydraulic pumps.
Superior Extrusion recently confronted this situation. In 1996, the company purchased a used 1,650-ton Farrel press. In use since 1971, the 7-inch press has since produced over 200 million pounds of aluminum extrusions for the Michigan-based manufacturer. The press currently runs one 10-hour shift per day, with plans to move to two shifts in the future.
In an aluminum extrusion press of this size, hydraulic components are under significant and constant wear and tear. After decades producing a wide range of parts, hydraulics maintenance — especially on the hydraulic pump — had become more frequent, reducing press uptime and productivity.
As with many customers using similar model pumps, parts became nearly impossible to obtain and qualified technicians became harder to find. One major consequence of the pump’s aging condition was increases in hydraulic fluid leaks. Superior began logging 65 to 70 hours of downtime every year to repair leaks, along with the costs of repair and fabricating piping and other parts in-house.
The Drop-In Hydraulic Pump Upgrade Solution
Superior approached Bosch Rexroth to help develop the solution, since they had worked together on other hydraulic projects in the past, both for new systems and equipment upgrades. “Bosch Rexroth has been around for years, and they have a reputation for quality and service. That was important to us because in the extrusion industry, when a part goes down, you can’t just run to the hardware store to buy a new one off the shelf,” said Superior’s President and CEO Bradley Couture.
According to Michael Kramer, Press Application Engineer at Bosch Rexroth, the legacy pump sat on top of the tank, drawing oil up from the reservoir and supplying it to the system through two supply ports. Most modern pumps operate with just one supply port, so installing a new pump required system reconfiguration.
In addition, Superior and Bosch Rexroth needed to design a relatively straightforward upgrade.
Prior to working with Superior, the Bosch Rexroth team recognized that this pump style was becoming obsolete. In response, their engineering team in Bethlehem, PA, collaborated with associates in Germany to design and engineer a pump/manifold/controls replacement.
After 150 hours of testing at the Bethlehem facility and over 2,000 testing hours in production on a Rexroth customer’s 2,400-ton extrusion press, the team validated that the new drop-in solution met the company’s performance and reliability standards.
Superior’s project was the first opportunity to apply the tested drop-in concept. At the solution’s heart was a Rexroth A4VSO 500 axial piston pump. “By adding a check valve at the bottom of the suction pipe and injecting a partial filling volume into the pipe, we could ensure that the pipe inlet was full upon start-up or under minimal flow conditions,” Kramer said.
The drop-in upgrade incorporated a custom manifold circuit that replicates the older two-way function with two pressure ports in the exact same location as the legacy pump. Two-way cartridge valves direct the oil to the correct port; this design preserved much of the existing hydraulics piping and enabled easier installation.
To control flow through the pressure ports, an HACD digital electronic control was configured to take the existing analog signals that previously controlled the legacy pumps and use those outputs to control both the A4VSO pump and the control valves. This simplified the controls challenge of installing a new generation of hydraulics with the existing systems.
The result was a drop-in solution that would modernize the press without the significant downtime or cost associated with a complete upgrade or replacement.
Measurable Results Beyond Reducing Downtime
The hydraulic pump retrofit produced measurable results almost immediately, with significant increases in press speed. “Prior to the upgrade, the press ran around 2,000 pounds per hour,” Couture said. “Now it runs around 2,400 pounds per hour, about a 14 percent increase.”
The speed of the press increased so much that when one particular die ran at 2,800 pounds per hour, Superior’s oven could not keep up with the production run. Superior found the new retrofit operated so much more efficiently that they could replace 200 horsepower motors with more energy-efficient 150-horsepower motors. The oil temperature also decreased, helping reduce environmental and cooling costs.
According to Superior’s CEO, the retrofit provided an easy-to-install, smart solution to a persistent problem hampering the company’s productivity and operational efficiency. By having a predesigned Rexroth replacement for the hydraulic pump, Superior was able to extend the press’s operational lifetime with a cost-effective solution that quickly delivered measurable return on their investment.
This article was contributed by Bosch Rexroth (Bethlehem, PA). For more information, visit here .