Sheet-Fed Press Drive Control for Torsional Vibration Damping
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Solution Overview
Problem
Existing sheet-fed printing machines face complex challenges in effectively compensating for torsional vibrations, which affect print quality, due to the need for multiple drive controllers and complex modal analysis, limiting the ability to uniformly influence the overall vibration behavior across different machine areas.
Innovation Solution
Assigning each drive controller of the direct drives a device that generates an independent torsional vibration compensation variable, valid only for the respective drive control circuit, allowing for online compensation without requiring modal analysis, and using cascaded controllers for current, speed, or position control to apply compensation variables effectively across the drive system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If harmonic balancing torques are used to compensate for torsional vibrations, then vibration compensation is achieved, but complex and expensive modal analysis is required in advance
Solution Approach 1:
The patent replaces complex mechanical modal analysis with electrical signal processing. The drive controller uses the electrical current signal from the direct drive motor, which already contains vibration information, and processes it through filtering and differentiation to generate compensation torques. This substitutes the need for separate mechanical measurement systems and complex modal analysis with an integrated electrical control approach.
Solution Approach 2:
The system uses its own operational data (electrical current from the direct drive motor) to compensate for vibrations. The drive controller extracts vibration information from the motor's current consumption and generates compensation torques without requiring external measurement devices or pre-analysis, making the system self-sufficient.
2Reliability
If multiple drive controllers with centralized coordination are used, then overall vibration behavior can be influenced, but the system complexity and coordination requirements increase significantly
Solution Approach 1:
The patent divides the vibration compensation task into independent segments, with each drive controller handling its own printing unit separately. Each controller processes local vibration data from its direct drive motor and generates local compensation torques without requiring coordination with other controllers. This segmentation eliminates the need for complex centralized coordination while maintaining effective vibration control.
Solution Approach 2:
The mechanical coupling through the gear train and friction drive acts as an intermediary that naturally transmits vibration effects across the system. Each drive controller compensates for vibrations locally, and the mechanical coupling automatically distributes these compensation effects throughout the gear train, eliminating the need for explicit communication or coordination between controllers.
3Measurement precision
If incremental encoders are used to detect torsional vibrations, then vibration detection is achieved, but only angle of rotation signals are obtained requiring additional processing
Solution Approach 1:
The patent replaces mechanical vibration detection using encoders with electrical current-based detection. The drive controller monitors the electrical current consumed by the direct drive motor, which directly reflects torsional vibrations through their effect on motor torque demand. This substitution eliminates the need for mechanical sensors and complex signal processing chains.
Solution Approach 2:
The system uses its own electrical current consumption as a natural indicator of vibration. The drive controller continuously monitors current data that is already available during normal operation and extracts vibration information from it, without requiring separate measurement systems or additional sensors.
Data Source
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AI summary
The machine has a unit for detecting a rotational oscillation to be compensated of a driven cylinder from a state variable of a drive control circuit. Another unit generates a rotational oscillation compensation variable for the control circuit from the detected oscillation. A drive controller receives signals for oscillation identification in a gear train (RZ) of the machine. The controller is connected with rotary encoders, which are associated to an engaging region of direct drives (20) in printing units (10-13). The direct drives are controlled by the controller. The state variable is a current variable. An independent claim is also included for a method for operating a sheet printing machine.