Web Tension Profile Measurement Using Deflector Backstep
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Solution Overview
Problem
Conventional systems for measuring the cross direction (CD) profile of machine direction (MD) tension on webs are expensive, occupy significant space, and are unreliable near the web's edges, while existing methods require dedicated frames or turning rolls that are costly to manufacture and maintain.
Innovation Solution
A deflector with a backstep and a slot for airflow, combined with measurement taps and sensors, deflects the web and captures pressure or deflection distance measurements to identify the CD profile of MD tension, allowing for accurate and cost-effective tension measurement without occupying additional space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional systems are used to measure CD profile of MD tension, then measurement accuracy is achieved, but system cost and space occupation increase significantly
Solution Approach 1:
The patent extracts the essential measurement function from complex conventional systems by using a simplified deflector with backstep structure. The measurement capability is separated from the complex framing and turning roll mechanisms, achieving accurate CD profile measurement through a streamlined design that reduces both cost and space requirements.
Solution Approach 2:
The patent replaces complex mechanical measurement systems (dedicated frames, turning rolls) with a more simple mechanical deflector structure combined with sensors. This substitution maintains measurement accuracy while significantly reducing system complexity, cost, and space occupation.
2Measurement precision
If conventional measurement systems are implemented, then tension measurement capability is provided, but reliability near web edges deteriorates
Solution Approach 1:
The patent applies local quality by designing the deflector with specific geometric features (backstep) that create localized flow patterns and pressure distributions. This localized design ensures reliable measurements near web edges by optimizing the interaction between the deflector and the web at critical measurement locations.
Solution Approach 2:
The patent introduces an intermediary airflow field between the deflector and the web. This airflow acts as a mediator that transmits tension information reliably to the measurement sensors, even near web edges where direct mechanical contact would be problematic. The airflow ensures consistent measurement quality across the entire web width.
3Measurement precision
If dedicated frames or turning rolls are used for measurement, then measurement function is achieved, but manufacturing and maintenance costs increase
Solution Approach 1:
The patent segments the measurement system into discrete, simple components: a deflector with backstep, measurement taps, and sensors. This segmentation allows each component to be manufactured independently and easily replaced, significantly reducing both manufacturing complexity and maintenance costs compared to integrated dedicated frames or turning rolls.
Solution Approach 2:
The patent employs a simple, cost-effective deflector structure that can be easily manufactured and replaced. The design prioritizes low cost and ease of replacement over durability, allowing for economical maintenance strategies where components can be quickly replaced rather than repaired, reducing overall maintenance costs.
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 provides accurate CD profile measurements of MD tension with reduced costs and space requirements, enabling precise control of web tension and reducing the likelihood of web breaks, while simplifying cleaning and calibration processes.
Implementation Method 1
a backstep configured to cause the web to deflect towards the deflector
Implementation Method 2
a slot configured to deliver an airflow between the web and the deflector
Implementation Method 3
at least one measurement tap configured to allow at least one sensor to capture measurements of one or more characteristics associated with the web
Data Source
AI summary
A method includes passing a web of material over a deflector having a backstep, where the backstep causes the web to deflect towards the deflector. The method also includes capturing measurements of one or more characteristics associated with the web at one or more locations downstream of the backstep. In addition, the method includes identifying a cross direction (CD) profile of machine direction (MD) tension on the web using the measurements. The method could further include generating a Coanda airflow between the web and the deflector. The measurements could include pressure measurements identifying air pressures in a space between the web and the deflector and/or deflection distance measurements identifying distances by which the web is deflected towards the deflector.