Page 34 - MetalForming April 2013

Leveled Sheet and Plate
years old, no longer could handle many of the current tasks required, Rothermel still sees its well-earned retirement with both a smile and a heavy heart.
“Many years ago I purchased the machine second-hand together with our company founder, Alois Goldhofer. The machine served us well for decades.”
To upgrade its leveling capabilities, the firm first investigated three- and four-roll bending machines, typically used to shape plate into rings for fur- naces or similar applications. With cer- tain restrictions the machines also can be used for sheetmetal leveling, and given their significantly lower purchase price compared to a roller leveler, Gold- hofer’s management considered the option.
Says Rothermel: “We thoroughly analyzed the actual costs and discov- ered a clear winner. Although more expensive to purchase, the roller level- er is significantly more efficient to oper- ate. This is primarily due to the far greater overhead and space required when operating roll-bending machines.”
“In addition,” adds Desiderato, “when using a roll-bending machine, the chamfer at the start and the end of the sheet has to be removed using an additional vertical leveling press. And, the leveling process requires consider- ably more time. We would have needed at least three roll-bending machines to accomplish the same amount of work.”
Higher Strength and Thickness Capabilities
The firm’s old leveler could process only S355 high-strength low-alloy steel (50,000-PSI yield strength) to 15 mm thick. The Arku leveler processes mate- rials ranging from 3 to 30 mm thick, and can handle the high-strength S960 steel (140,000 PSI yield strength) increasingly processed by Goldhofer. Says Desiderato: “The FlatMaster more than lives up to its name, even when working with these extremely high- strength steels. It makes them very flat.”
In addition, the ability to level small- er parts proved to be an unexpected
While Goldhofer’s old leveler required 5400 hr., or 3.2 shifts, to level 65,000 blanks, the Arku FlatMaster 120 can complete the same amount of work in only 2160 hours, or 1.3 shifts. The leveler processes materials ranging from 3 to 30 mm thick, and can handle high-strength S960 steel (140,000-PSI yield strength).
32 MetalForming/April 2013
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benefit. “Previously, the smallest part we could level measured 400 by 400 mm,” adds Desiderato. “Now we can level parts half that size.”
The firm’s newfound ability to level more of its parts pays off at its welding and assembly cells. “Before, workers in those areas would have to press the parts onto the worktable using brute force,” Desiderato says. “And often, the heat generated during manual or robotic welding would release these forces and cause the entire structure to deform. That added a significant amount of rework (flame-straighten- ing) time. “
Servo Hydraulics, and Reversing Mode
“The Flat Master’s servo-hydraulics is a great feature,” Desiderato contin- ues, “as is its ability to control the lev- eling gap. With our old system, leveling parts without cutouts required a com- pletely different setup than did leveling parts with cutouts. Now we use the same setup for both types of parts.”
The system’s reversing mode also has proven its worth. Goldhofer work- ers need only set the part length. The workpiece then runs through the machine until it reaches the stop, then the upper leveling unit lifts up and the leveled part quickly returns to the oper- ator. This delivers enormous time sav- ings, says Desiderato.
“The operators used to have to walk around the old machine and check the part on the rear side,” he notes. “They had to lift the heavy work using a crane. If the results were inadequate, the oper- ator then would run the part through the machine in the reverse direction and check it again on the other side. This process was repeated until the desired results had been achieved. Now, every part comes back out to the front side after leveling and the operator no longer needs to move from one place to the other.”
This new-found efficiency has had a direct effect on staffing requirements. Whereas 60 percent of the parts leveled at Goldhofer on its old leveler required two operators, more than 95 percent of its parts can be leveled using one operator.
Last but not least, despite the Arku special roller-leveler quick-change sys- tem, Goldhofer does not need to change the rollers for different part thicknesses. Says Andreas Hellriegel, who leads the Arku parts leveling division:
“Because we work with relatively small roll diameters, we can use the machine for the range of material thick- nesses that Goldhofer processes—3 to 30 mm. And if Goldhofer wants to level even thinner work, it would be more economical to purchase an additional, smaller roller leveler than to add a changeover cassette to its large machine.” MF