Marginal Column

Steel giant with a delicate touch

The leveling system built by MAE Götzen straightens gigantic steel workpieces both powerfully and precisely. This system, created in a close development partnership with Bosch Rexroth, reduces energy consumption by up to 80 percent.

 

At this steel mill, great force is applied with a delicate touch. The master computer sends all the data on the workpiece to the leveling system, which then sets parameters in regard to diameter, material and the required degree of accuracy. The electric motor for the pump drive starts up with a purr before a hydraulically powered ram presses the workpiece against two anvils. This is done so carefully that the remaining deviation is less than 0.1 millimeters – and that at forces of up to 25,000 kilonewtons. The large-scale leveling unit of the MAE Götzen brand is an entirely new generation of machinery in the tough steel mill setting.

With a modern, multi-stage concept, the leveling system can be used for a multitude of products – from large steel rollers to delicate profiles. “Our development goal was to create a series of modularized units that would cover the entire range of needs for leveling long parts –from relatively low forces with manual charging to extremely powerful, fully automatic concepts,” explains Manfred Mitze, chief executive at MAE Götzen.

The large-scale leveling unit shapes workpieces by applying forces of up to 25,000 kilonewtons with tolerances of less than 0.1 millimeter.
Photo: MAE Götzen GmbH

 

Variable advantages

To achieve these goals, the engineers at the leveling and joining specialists in Erkrath, Germany, needed exactly the right drive. Mitze was searching for a highly capable co-developer for MAE’s patented drive concept. “We were looking for an experienced partner for all the automation, providing motion control and electro-mechanical components and the pneumatics; that is why we chose Bosch Rexroth.” This choice has paid off. The experts at Bosch Rexroth, working hand-in-hand with MAE, designed a complete drive system and by doing so significantly simplified the hydraulic configuration. At the heart here was the variable-speed pump drive drawn from the Sytronix family. It includes an intelligent regulator and a servomotor that drives two adjustable axial piston pumps on a shaft. Sytronix can make full use of its advantages in this application.

The drive positions the differential cylinder directly, without a control valve. Whenever the process requires only partial power, the speed drops to meet that need. In this way Sytronix can reduce energy consumption by up to 80 percent when compared with a constant-velocity unit. In addition, mean noise emissions may fall as much as 20 decibels. There are other advantages, too. The hydraulic fluid heats up hardly at all, eliminating the oil cooler unit. Over and above that, MAE was able to reduce the volume of hydraulic fluid by about half when compared with conventional designs. The pumps, driven with this degree of efficiency, move a differential cylinder in a closed control loop at great precision, following the specifications issued by the RICOS leveling measurement control, developed by MAE.

Set-up without danger

Located below the machine controls, the drive-based IndraMotion logic system, MLD, by Rexroth completes the control loop governing the cylinder position, force, and speed of the pump drive. “Bosch Rexroth built into the software its wide-ranging experience with hydraulics,” Manfred Mitze happily notes. “The drive-based motion control eases the work for our process controls. Depending on the size of the machine, we can utilize hydraulic or electric drive solutions without additional effort.” In its largest version, the MAE leveling machine may involve up to 20 servo drives. Mitze is also highly satisfied in terms of machine safety. Thanks to the Safety on Board concept integrated into the drives, the operator can, with the guard door open, set up and load the machine without any risk at all.

Bringing strengths together

The new large-scale leveling systems are already in operation in Europe, the USA and Asia. MAE chief executive feels that the course of the project is thoroughly positive: “Thanks to the development partnership, we quickly turned our concept into reality and significantly reduced the engineering effort. Bosch Rexroth brings with it experience in the interplay of hydraulics, control technology, energy efficiency, and software so that we can concentrate fully on our own process expertise.” This is a “division of labor” that both companies intend to continue in the future.