Digital Paper Printing With Grid-Based Expansion Control
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Solution Overview
Problem
Existing digital printing systems for paper surfaces face challenges in managing paper expansion due to moisture and ink application, leading to dimensional inconsistencies that result in significant waste, particularly in applications requiring precise dimensions like laminate panels.
Innovation Solution
A method involving a screen marking that is machine-detectable but not visible to the human eye, allowing for real-time adjustment of paper dimensions through a grid spacing detection system integrated into the printing process, using sensors and electrical control to adjust primer application and drying parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If liquid primer and ink are applied to the paper web, then the visual quality and color intensity of the printed decoration are improved, but the paper undergoes wet expansion causing dimensional inconsistencies
Solution Approach 1:
The patent applies preliminary drying action by introducing a dryer between the primer application unit and the printing unit. This dryer removes excess moisture from the primer-coated paper before ink application, preventing wet expansion during the printing process and maintaining dimensional consistency of the paper web.
Solution Approach 2:
The patent implements continuous drying action through a dryer that operates continuously along the paper web path. This ensures consistent moisture removal throughout the printing process, maintaining stable paper dimensions while allowing continuous application of primer and ink without interruption.
2Manufacturing precision
If manual adjustment of guide rollers and tension is used, then the system is simple to operate, but reproducible control of paper stretching is not available leading to waste
Solution Approach 1:
The patent incorporates a feedback mechanism where sensors detect the actual position and tension of the paper web, and this information is fed back to the control system. The controller automatically adjusts guide roller positions and tension settings based on this feedback, achieving precise dimensional control without manual intervention and eliminating waste from inaccurate adjustments.
Solution Approach 2:
The patent replaces manual mechanical adjustment with an automated control system that uses sensors, controllers, and actuators. This substitution of mechanical manual operation with an automated electromechanical system provides reproducible, precise control of paper tension and positioning, eliminating the variability inherent in manual adjustment.
3Manufacturing precision
If the paper web tension is increased to prevent wrinkles, then the print quality is improved, but the paper stretching in the running direction increases
Solution Approach 1:
The patent dynamically adjusts paper web tension parameters during the printing process. By optimizing the tension level to the minimum required to prevent wrinkles rather than using high tension continuously, the system maintains print quality while minimizing paper stretching in the running direction, thus preserving dimensional accuracy.
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
Reduces waste by ensuring precise alignment of printed decorations with paper dimensions, enabling high-quality production with minimal scrap, particularly in laminate panel production.
Implementation Method 1
Such drying can take place at different times in the process. The digital printing system preferably has at least two dryers, one of which is arranged downstream of the primer application unit and one downstream of the printing unit.
Implementation Method 2
This occurs, for example, by subjecting the surface to an air stream, in particular a warm air stream, or by irradiation with heat or infrared radiation.
Implementation Method 3
Paper moisture content, which, as already explained, can be influenced by the ink or primer, also depends, at a given humidity level, on how well and how deeply the applied liquid can penetrate the paper in question.
Data Source
Figure 1~2
AI summary
The invention relates to a method for printing a paper with a decorative pattern by means of a digital printing system which comprises at least one primer application unit for applying a primer, at least one printing unit for printing the decorative pattern onto the applied primer, and at least one dryer for drying at least one part of the paper after the primer and/or the decorative pattern have/has been applied, wherein the method comprises the following steps: a) providing of an unprinted raw paper, b) applying of a primer to the surface of the unprinted raw paper, c) printing of at least one grid marking and at least one decorative pattern onto the raw paper which is provided with the primer, with the result that a printed raw paper is produced, d) detecting of a grid spacing between at least two points of the grid marking of the printed raw paper in order to determine an actual state of the printed raw paper, e) comparing of the detected grid spacing of the grid marking of the printed raw paper according to the actual state with a grid spacing, stored digitally as setpoint state, for the printed decorative pattern, f1) changing of the stored setpoint grid spacing on the basis of the comparison which is carried out, by a changed setpoint grid spacing and a decorative pattern which is changed by way thereof being produced, and/or f2) changing of at least one process parameter for controlling the application of the primer and/or the printing of the grid marking and/or the drying until a predefined criterion is met.