Reference Mark Measurement Correction for Stretching Material Webs
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Solution Overview
Problem
Existing methods for determining the position of reference marks on material webs in non-positive locking tools, such as in gravure printing, result in measurement errors due to web stretching and stretching changes, particularly affecting web-cylinder measurements, leading to control instability and print image errors.
Innovation Solution
A method to correct measurement errors by calculating and deducting the error from the measurement value using parameter values of downstream tools, such as cylinder radius, rotational speed, and web length, without requiring additional sensors or actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a tool that functions in a non-positive locking manner is adjusted axially or longitudinally, then the angular positioning and register control are improved, but tensioning and stretching problems of the material web occur
Solution Approach 1:
The patent calculates and compensates for web stretching effects before they affect measurement accuracy. By predicting the stretching based on tool adjustment parameters and compensating in advance, the system maintains measurement precision without requiring additional mechanical stabilization of the web tension.
Solution Approach 2:
The patent changes the measurement approach from direct physical measurement to calculated compensation based on parameter changes. Instead of measuring web tension directly, the system uses parameters such as tool adjustment amount, web speed, and material properties to calculate and compensate for stretching effects on measurement values.
2Manufacturing precision
If a register adjustment is performed, then the precise overprinting of color separations is improved, but the measurement value is falsified leading to control instability
Solution Approach 1:
The patent implements a feedback mechanism where the calculated stretching compensation is continuously applied to measurement values based on actual tool adjustments and web conditions. This feedback loop ensures that registration precision is maintained while preventing control instability by systematically correcting measurement falsification rather than allowing it to accumulate.
Solution Approach 2:
The patent introduces a calculation-based intermediary (stretching compensation value) between the tool adjustment and the measurement value. This intermediary mediates the relationship by translating physical adjustments into their expected measurement effects, allowing the control system to distinguish between actual registration errors and those caused by web stretching.
3Stability of the object's composition
If web stretching changes propagate in adjacent web run sections, then the stretch changes affect multiple sections, but the measurement accuracy deteriorates
Solution Approach 1:
The patent segments the web into different run sections and calculates stretching compensation separately for each section based on its specific conditions (tool adjustments, web speed, material properties). This segmentation allows the system to maintain measurement precision in each section while accounting for the propagated stretch changes from adjacent sections.
Data Source
AI summary
A method for correcting a measurement value of a reference mark on a material web is disclosed. A controller, a machine, a computer program and a computer program product can perform a correction of this type. To improve determination of the position of a reference mark on a material web, a machine in which the material web is moved in a conveying direction has at least one tool that functions in a non-positive locking manner, a second tool that functions in a non-positive locking manner and is located downstream of the first tool in the conveying direction, and a sensor that is located between the two tools. A measurement error in the sensor which arises as a result of an adjustment of the second tool is determined at least approximately at least via parameter values of the second tool. The measurement value is corrected by the measurement error.