03/03/2011

Servo press supplied by Schuler Group helps automotive supplier Craemer reach new performance dimensions with high press forces

Auto part suppliers face considerable challenges at present: shorter model cycles of car manufacturers on the one hand, and increasingly complex requirements for parts and the use of high-strength materials on the other. How companies in the metalforming business are reacting to this dynamic development is illustrated by the Craemer Group in Herzebrock-Clarholz, Germany. For the production of car seat components, the company has chosen the latest 1,600-ton servo press from Schuler which marks a new dimension in stroking speed performance. With the aid of ServoDirect technology (SDT) and powerful automation components, Craemer has installed a highly dynamic turnkey solution. The system is also equipped with a new software which for the first time enables users to select the ideal process parameters for slide kinematics, transfer motion and feed, as well as specific data for the die.

“From our point of view, the new system with its numerous possibilities and technical capabilities is almost revolutionary,” states Ralf Kühn, Sales Manager for Blanking and Forming Systems at Schuler’s facility in Weingarten, Germany, as he stresses the importance of this new manufacturing solution. The Schuler Group has already sold over one hundred presses with ServoDirect technology and significantly enhanced performance. Although the number of lines installed with press forces of 1,600 metric tons or more is still relatively small, they already mark a decisive change in technology, resulting in significantly enhanced performance for customers. Can the servo presses also shine at press force ranges of 800 to 3,000 metric tons? “Yes – especially in this range! We’ve reached unprecedented dimensions in virtually all relevant performance figures,” says Ralf Kühn. He adds: “At press forces of 800 to 3,000 metric tons, you can unlock new potential with the virtually stepless stroke adjustment system.” Schuler has already received orders for over twenty SDT presses with press forces of over 1,000 metric tons.

Twice as many strokes

The line has already been in three-shift operation at Craemer’s facility since April 2010, and the performance figures speak for themselves. The four-conrod machine with a press force of 1,600 metric tons and a bed size of 6 by 2.5 meters can reach a maximum speed of 40 strokes per minute – almost twice as fast as conventionally driven forming presses of this size. What’s more: the higher stroking speeds can also be achieved during the application – in other words, with dies. A further strength of the servo drive is also illustrated at extremely low speeds: the full working range for forming processes is available from stroking speeds of 3 min-1. “This means that even highly complex dies can be set up in a precisely measured power-motion curve during the tryout process,” confirms Siegbert Geldner, Managing Director for Technology at Paul Craemer GmbH. “In the case of critical forming operations, we can also reliably produce good quality parts at lower forming speeds.”

Perfectly coordinated system

The mid-size supplier Craemer can use its new line for the flexible and highly efficient production of a wide variety of part geometries. The quality of the manufactured parts is high. Before production begins, not only the automation technology – roll feed and high-performance transfer – is configured to the performance range of the servo press. “For the development of each new die, we always considered the capabilities of the entire system,” stresses Geldner. The company uses a new software from Schuler – the “curve generator”. With the aid of the new software, users can perfectly coordinate slide kinematics and automation motions. With an additional run simulation, the results can already be checked and optimized on the CAD work station. “As a result, Craemer now has a transfer press whose entire process constantly follows the ideal line,” says Geldner.

Adjusted impact speed

The line is already being used to produce completely flat parts at high speeds on the one hand, and complex parts with deep drawing processes on the other. “Obviously, the stroking speed is lower in this case, but the line’s output rate is still excellent in comparison to conventional solutions. The slide-motion curve of the servo press is gentle on the dies during the actual drawing process, while at the same time ensuring higher speeds during the other motion phases,” explains Ralf Kühn. The stepless slide adjustment also helps to protect the dies and thus raise service life. Whereas stroke height in rotating operation is 600 millimeters, it can be between 180 and 450 millimeters in pendular mode. This mode also enables fast slide acceleration and strong braking of the slide. Despite this dynamic range, the selected impact speed on the part is similar to that of hydraulic motion profiles. This is the key to the line’s tremendous performance potential.

Older dies – full potential

In order to optimize the manufacturing process, Craemer’s production planners can also call on Schuler’s process know-how: the forming experts carefully examine existing dies and then determine the slide’s optimum motion curves for Craemer’s press. This means the new line can reach its full potential even when using existing dies.

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