New Functions and Options for Designing Modern Servo Presses

Update of design program from ebu Umformtechnik

The goal of ebu Umformtechnik GmbH is to always furnish our customers with the optimal solution for their product. Buying a system with an automated press machine ebu STA driven by a modern servo torque motor involves relatively high investment costs.

For small and medium-sized enterprises (SMEs), it is therefore particularly important that the system and the ebu STA in particular be adapted to the product and the tools used.

The design program developed and recently opitimized by ebu Umformtechnik serves this goal, allowing the configuration of optimal designs and the calculation of possible output rates under various operating modes. Based on standard designs or using existing tool and process data, the forming process can be analyzed jointly with the customer and then implemented step-by-step in a servo press system which is optimal for the application case.

This design calculation is made possible through incorporation of both the press parameters and the existing data records of our partners. Siemens servo torque motors of the 1FW3 and 1FW4 series in heavy-duty versions are currently used for ebu STAs, but servo torque motors from other manufacturers are possible and have been also used successfully in the past.

ebu Umformtechnik now disposes of sufficiently large database of parameters (speed, torque, performance) of torque motors suitable for servo presses to cover a wide spectrum of application and to enable comparisons to competitors. The database of adequate gears suit-able for single as well as for double servo equipment, could be significantly increased and covers the whole range. A time efficient configuration and dimensioning including optimization of servo press drives is thus realizable.

The design program covers the entire ebu STA series, which ranges from 400 - 10,000 kN pressing force. The existing database includes more than 100 different configurations of the possible sizes of presses. Special lifts to meet framework mechanical conditions are available in addition to the existing pressing force profiles of the existing tools, allowing direct comparison between existing presses with conventional drives and the new ebu servo STAs.

Further databases of motor and power supply modules applied as well as kinetic energy storage are now available in addition to the existing databases of capacitor banks and the aggregates necessary for cooling. The operator can connect the installation to an existing cooling system or use a cooling system specially designed for the relative plant. An even better energy efficiency can be achieved by using the waste heat.

The comparison of possible feed lengths depending on operating mode and process parameters is also new.

The tool compares and calculates among others the following parameters:

  • Complete comparison of the ram kinematics and the mass moment of inertia reduced to the eccentric shaft respectively the axle of drive and engine including connecting rod, ram and weight of the upper section of the tool.
  • Calculation of ram speed and acceleration with the most different operating modes
  • Calculation of the required motor current, of the required electrical power
  • Calculation of the operating point of the servo torque motor
  • Examination of overload of the used motor modules
  • Energy capacity and supply capacity required
  • Dimensioning of cooling circuit or cooling capacity required

Various new features and samples of evaluation of parameters

Required torques of the drive motor:

Kinetic energy storage
capacitor bank
Circulation Mode
pendulum mode

ebu Energetics

Comparison of motor module and energy supply capacity with and without the energy management system - ebu Energetics.

Without complete compensation by the ebu Energetics energy management system these power peaks are either taken directly from the supply network or fed back in without payment. Additional measures are also necessary in this case.

For large stroke dimensions, e.g. due to the use of a transfer system with a relatively slow forming speed, the "Special pendulum mode" operating mode can be selected. Here, the entire available rotational speed range of the torque motor is utilized. The stroke necessary to achieve tool impact can be moved through quickly; after the forming process is completed, it is possible to accelerate again to achieve the free space between the ram and the table necessary for the transfer. The S1 curve is indicated and the operating point is calculated in this mode of operation as well.

The movement profile diagrams above show the difference between pendulum and special pendulum mode. Due to the special pendulum mode, the output rate in the application case under consideration could be increased by 60% compared to pendulum mode, and by 25 % compared to servo cycle mode.

Summary of advantages:

  • This new tool for designing modern servo presses allows optimization of the ebu STA for the particular customer as early as the requirements declaration phase or project planning phase.
  • Long iterative cycles between supplier (of motors, gears) and press manufacturer are avoided.
  • Selecting the most effective operating mode is easy to do.
  • There is the possibility early (already in the tender phase) to work out together with client the potential for optimization and cost reduction.
  • The possible and/or necessary feed length is considered in the design.
Overload SMM
Electric power
Movement profile - special pendulum
Torque motor - special pendulum mode

ebu Double Servo

ebu DS 1000

  • innovative combination of torque motor and gear unit for automatic punching machines
  • press force 1000 t
  • peak capacity up to 3 MW