Model-Based Roller Calibration for Uniform Embossing Nip Width
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Solution Overview
Problem
Current methods for calibrating the nip between a rubber and steel roller in embossing and laminating processes are subjective, imprecise, and lack repeatability, leading to inconsistencies in the production of bathroom tissue and kitchen towels.
Innovation Solution
An automated process using a controller with a processor and memory to calibrate the nip between a rubber and steel roller by employing a modified Hertzian contact model, bending model, and kinematic actuator-interference transform, aided by optical or vision systems for precise nip width measurement and actuator positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration using feeler gauges and nip impression paper is used, then the process is simple to operate, but the measurement precision and manufacturing precision are poor due to subjective judgment
Solution Approach 1:
The patent replaces manual mechanical measurement methods (feeler gauges, nip impression paper with subjective visual judgment) with an automated optical measurement system. The optical system uses cameras or sensors to capture images of the nip region and automatically calculates nip width through image processing algorithms, eliminating human subjectivity and significantly improving measurement precision.
Solution Approach 2:
The calibration system performs self-calibration by automatically capturing images, processing the data, calculating nip width, and adjusting roller positions without requiring operator intervention. The system uses its own optical sensors and control algorithms to autonomously achieve precise calibration, reducing dependency on manual operations.
2Reliability
If automated optical measurement systems are implemented, then measurement precision and repeatability improve, but device complexity increases
Solution Approach 1:
The patent implements a closed-loop feedback system where the optical measurement system continuously monitors nip width, compares it against target values, and automatically adjusts roller positions through actuators. This feedback mechanism ensures high repeatability by constantly correcting deviations and maintaining consistent calibration across multiple operations.
Solution Approach 2:
The optical measurement system serves multiple functions: it captures images for measurement, processes data to calculate nip width, determines calibration status, and guides actuator adjustments. This multi-functionality consolidates what would otherwise require separate systems into a single integrated unit, managing complexity while enhancing reliability.
3Manufacturing precision
If subjective manual judgment is used for calibration, then the ease of operation is high, but the manufacturing precision and consistency of the embossing process deteriorate
Solution Approach 1:
The patent replaces manual mechanical calibration operations with automated optical measurement and control systems. The system automatically captures images, processes them to determine nip width, and adjusts roller positions without requiring operators to make subjective judgments, thereby ensuring consistent embossing quality while managing operational complexity through automation.
Solution Approach 2:
The patent introduces an optical measurement system as an intermediary between the manual calibration process and the embossing operation. This intermediary objectively measures nip width and provides data-driven feedback for adjustment, eliminating the need for operator subjective judgment and ensuring consistent manufacturing precision.
4Manufacturing precision
If multiple measurement points are taken across the roller width, then the manufacturing precision improves, but the time required for calibration increases
Solution Approach 1:
The patent implements continuous imaging across the entire roller width in a single capture, rather than taking discrete sequential measurements. The optical system captures the full nip region across all positions simultaneously, processes the entire image set through algorithms, and determines uniformity across the width in one continuous operation, maintaining high precision while minimizing calibration time.
Solution Approach 2:
The system performs preliminary image capture and processing across all measurement points before final calibration decisions are made. By pre-processing the entire dataset and identifying uniformity issues across the roller width in advance, the system optimizes the calibration process and reduces iterative adjustments, thereby reducing total calibration time while maintaining precision.
Data Source
AI summary
In a machine having a pressure and embossing roller, a position of an actuator operatively connected to a journal of the pressure roller is calibrated to a width of a nip formed between the pressure and the embossing rollers. The position of the actuator is changed to move the pressure roller to a position at which the nip forms between the pressure and the embossing rollers. The nip widths are measured in at least three locations along of the rollers. An interference between the pressure and the embossing rollers is calculated at each of the three locations. A deflection curvature of the pressure roller is calculated. A deflection of the journal of the pressure roller at the connection location to the actuator is calculated. The measured widths of the nip are correlated with the position of the actuator when the widths of the nip were measured.