Servo presses – with new kinematics to new possibilities

Servo presses are a state-of-the-art solution for improved flexibility and productivity. This is achieved by adjusting ram drive speed during the 330° crank angle before and after forming.

Adjustments of the ram drive during forming in combination with a synchronized servo cushion result in new technologies.

These technologies are Bi-Directional-Drawing (BDD) and Cushion-Ram-Pulsation (CRP). In both cases, additional pulsation movements are added during the forming process. The pulsation movements usually have amplitudes ranging from 0.1 to 2.0 mm with frequencies ranging up to 20 Hz. BDD is preferably suitable for materials with strong work-hardening properties, such as austenitic stainless steel. CRP is suitable for softer material grades (figure 1), and especially for hot stamping.

For both methods, more than 10 critical parts were examined and consistently better results were obtained.

Series production is currently not possible due to the lack of press equipment. Currently, there are no known series presses worldwide that can realize these synchronized ram and cushion movements. However, as in machining technology, fast controlled axes will also become increasingly common in forming technology in the future.

To ensure widespread use of the equipment, it is necessary to determine many parameters, such as amplitudes, frequencies and number of pulsations in a practical manner. Therefore, current research is focused on the Human Machine Interface (see figure 2) and the automatic prediction of process parameters.