Smart injection molding drive

Thanks to the direct pump attachment with internal circulating oil lubrication, the motor-pump connection of the water-cooled DSC2 motors is maintenance-free and quick to install thanks to the single-cable solution. © Baumüller

In addition to good control behavior and easy handling, the software also offers numerous protection and monitoring functions. A hydraulic system inherently contains volumetric losses. Leakage oil can escape due to system-related leaks in the components. This leads to inaccuracies in the control of hydraulic cylinders and motors. The drive-integrated software can detect and compensate for this leakage in order to increase the precision of servo-hydraulic injection molding machines. Without leakage compensation, the travel speed would vary depending on the load due to volumetric losses. It is also possible to detect the ageing of components. Typically, increasing leakage indicates wear of the components used.

In servo-hydraulic applications, long holding times at high pressures and low flow rates can lead to thermal overload in the machine cycle. This increases wear and can lead to premature pump failure. In the injection molding machine, this critical operating range occurs in the core pulls, for example, if they have to hold the pressure in the end position for a long time. The thermal pump protection function recognizes this condition of the fixed displacement pump and reacts actively. Thanks to an intelligent calculation model, detection is based solely on pressure and speed. The servo drive activates a bypass valve, thereby bringing the fixed displacement pump into the permissible operating range. Thanks to the dynamic pressure control and intelligent pilot control of the b maXX 6500, the pressure deviation when opening and closing the bypass valve is so small that the process accuracy of the injection molding machine is maintained.

Detect faults and protect the machine

The thermal pump protection also detects faults. For example, if the throttle valve for oil preheating is set too high and does not open, the fixed displacement pump is in pressure maintenance mode during the entire oil preheating process and overheats. The intelligent pump protection function detects the overload and reports it to the machine control system. Other protective functions include cavitation and dry-running detection of the fixed displacement pump. The IoT functions described detect changes in the process and report these to the machine control system via a data pre-evaluation in the servo drive. The data is processed directly where it is generated. This makes it possible to scan the high resolution of the drive controller and react faster than would be possible via the fieldbus. Even in tricky error cases, such as EMC faults, incorrect parameterization or incorrect wiring of a pressure sensor, the Baumüller software detects reliably. In contrast to conventional line break monitoring, which only reacts to a missing signal off-set, the new patented actual pressure estimator software function can detect implausible pressure sensor signals regardless of their level. With the help of a detailed servo pump model, which is calculated in real time in the servo drive, the prevailing system pressure can be estimated based on current and speed. All of this is done directly in the b maXX 6500 servo drive, which enables faster drive responses and reduces the load on the fieldbus and machine controller.

SPS, Hall 1, Stand 560