Web Tension Calculation via Motor Load Analysis
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Solution Overview
Problem
Existing methods for determining web tension in material webs, such as those in paper machines, are prone to failure, expensive, and imprecise, and only allow for tension measurement at fixed points.
Innovation Solution
Calculating web tension using a control device or frequency converter, which determines the load on a motor driving a deflection roller, incorporating variables like torque, rotational speed, and web properties to eliminate the need for tension gauges, allowing for precise and flexible tension measurement at any point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tension measuring devices are used to determine web tension, then web tension can be measured, but the devices are prone to malfunctions, expensive, and too inaccurate
Solution Approach 1:
The patent replaces mechanical tension measuring devices with a computational model that calculates web tension based on motor parameters (torque, speed, power) and web properties. This substitution eliminates the need for physical tension sensors, thereby improving reliability while maintaining measurement capability through mathematical relationships derived from the drive system's operational data.
Solution Approach 2:
The patent introduces a control unit as an intermediary that processes motor parameters and web properties to compute web tension. Instead of directly measuring tension with a sensor, the control unit acts as a mediator that derives tension indirectly from readily available drive system data, avoiding the reliability issues of direct mechanical measurement devices.
2Measurement precision
If tension measuring devices are used, then web tension can be determined, but the devices are expensive
Solution Approach 1:
The patent creates a virtual model of the web tension measurement system through computational calculation rather than physical instrumentation. By copying the measurement function through software algorithms that process existing motor data, the system eliminates the need for expensive hardware tension sensors while maintaining the essential measurement capability.
Solution Approach 2:
The drive system's existing sensors and control unit serve dual purposes: controlling motor operation and providing data for web tension calculation. The system uses its own operational parameters (power, speed, torque) to determine web tension, eliminating the need for separate, expensive measurement devices and leveraging resources already present in the system.
3Measurement precision
If fixed point tension measurement is used, then tension can be measured at specific locations, but tension cannot be determined flexibly at any point along the web
Solution Approach 1:
The patent transforms the measurement system from a static, fixed-location approach to a dynamic, flexible calculation approach. By using the computational model that processes real-time motor parameters, the system can determine web tension at any point along the web based on the drive system's operational state, providing adaptability without requiring physical sensors at multiple fixed locations.
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
Enables precise and flexible web tension determination without the need for tension gauges, reducing costs and improving measurement accuracy across the web, with the calculated tension being used to control motor speed and torque for optimal web handling.
Implementation Method 1
The torque is preferably determined by measuring the motor current in the frequency converter
Implementation Method 2
The web is moved by at least one motor over a deflecting roller
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method and a device for determining the web tension (Z) of a web of goods (1). By determining the web tension (Z) using motion variables such as the load (Y) of a motor (5) which serves to drive a deflection pulley (3, 3'), a tension measuring cell (7) for determining the web tension (Z) of the web of goods 1 can advantageously be omitted.