Motor-Driven Tension Measuring Roll Torque Compensation
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Solution Overview
Problem
Existing methods for measuring the tension of a continuous material web are affected by error components due to the torque of the drive rotating the measuring roll, which complicates the measurement and control of web tension, especially when the roll is used to actively control the web.
Innovation Solution
A method and system where the torque of the measuring roll is adjusted using a motor drive to account for frictional and inertial forces, allowing for accurate tension measurement by subtracting the effects of the drive's torque, friction, and inertia from the measured force, enabling the roll to be used for controlling web speed without interfering with the measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the measuring roll is motor-driven to actively control the web speed, then the controllability of the material web is improved, but error components are introduced into the tension measurement due to drive torque
Solution Approach 1:
The drive torque is segmented into distinct components: frictional torque (T_friction) and inertial torque (T_inertia). Each component is calculated and compensated separately in the measurement equation, allowing the system to maintain both active control capability and measurement accuracy by addressing each torque component individually rather than treating them as a single undifferentiated error source.
Solution Approach 2:
The system implements feedback compensation by continuously calculating the frictional and inertial torque components based on measured values (wrap angle, acceleration, web speed) and subtracting them from the total measured torque. This closed-loop approach ensures that the tension measurement remains accurate even when the measuring roll is actively driving the web, as the compensation adapts to changing operating conditions.
2Measurement precision
If the measuring roll is mounted at optimal angles for measurement, then measurement accuracy is improved, but the web travel path becomes constrained
Solution Approach 1:
The system dynamically adjusts the wrap angle parameter (α) of the measuring roll based on operational requirements. By making the wrap angle a variable parameter rather than a fixed geometric constraint, the system can optimize the measuring roll's position and orientation for both accurate measurement and flexible web travel paths. The measurement equation incorporates the wrap angle to calculate the frictional torque component, allowing accurate tension determination regardless of the specific geometric configuration.
3Measurement precision
If the measuring roll drive torque is minimized to reduce measurement error, then measurement accuracy is improved, but the ability to control web speed is reduced
Solution Approach 1:
The harmful effect of drive torque on measurement accuracy is extracted and separated from the useful function of web control. By calculating and subtracting the frictional and inertial torque components from the total measured torque, the system removes the error introduced by active driving while preserving the ability to control web speed. This allows the measuring roll to exert significant drive torque for speed control without compromising measurement integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for more flexible web travel planning and improved controllability of the material web, eliminating unwanted measurement components and enabling the measuring roll to actively transport the web without affecting the tension measurement.
Implementation Method 1
A tension measuring roll (1) whose rotating speed can be adjusted with a motor drive (2)
Implementation Method 2
Before use, a frictional couple (Tμ) and moment of inertia (J) are defined for the tension measuring roll (1)
Implementation Method 3
Before use, a frictional couple (Tμ) and moment of inertia (J) are defined for the tension measuring roll (1)
Data Source
Figure 1~3
AI summary
Method and system in connection with a motor operated tension measuring roll (1) for compensating an error in tension measuring of a continuous material web, the method comprising defining the tension Tmeas of a material web (4) by a force sensor (3) provided at the tension measuring roll. The method comprises defining the frictional couple Tµ and moment of inertia J of the tension measuring roll before tension measuring during operation, defining a torque Tmot generated by the driving motor of the tension measuring roll during operation, defining a torque Twm directed to the material web by the tension measuring roll by subtracting the frictional couple Tµ and moment of inertia J from the defined torque Tmot generated by the driving motor, defining a force FT directed to the material web on the basis of the torque Twm directed to the material web by the tension measuring roll, defining, on the basis of the force FT directed to the material web, a component of force FTm of the measuring sensor in the measuring direction directed to the material web by the tension measuring roll, and subtracting from the tension Tmeas defined by the force sensor the component of force FTm of the measuring sensor in the measuring direction directed to the material web by the tension measuring roll to provide a corrected measuring signal.