Non-Woven Fabric Printing with Segmented Press Roller
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Solution Overview
Problem
Current printing technologies for non-woven fabrics, such as spun-lace, face challenges in maintaining optimal print quality and high production speed due to fiber elongation and crease formation, especially when printing multicolor designs, as existing systems struggle to control tension consistently across the fabric width.
Innovation Solution
The implementation of a modified flexographic printing system with suction holes in the press roller, individually motorized rollers, hot air drying, water separators for wet printing, and a control unit to monitor and adjust angular speeds and torque, along with mechanical widening rollers to prevent creasing and maintain consistent tension, allowing for high-speed printing of both monochrome and multicolor designs on dry or wet non-woven fabrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drawing speed of non-woven-fabric is increased to improve productivity, then production speed increases, but fiber elongation and crease formation increase, degrading print quality
Solution Approach 1:
The press roller is divided into multiple independently motorized zones along its circumference, each capable of rotating at different speeds. This segmentation allows different sections of the roller to apply different stretching forces to different portions of the fabric, enabling precise control over fiber elongation while maintaining high overall production speed.
Solution Approach 2:
The system employs dynamic speed adjustment where the angular velocity of each roller zone can be independently varied during operation. This dynamic control allows the system to adapt to changing fabric tension conditions and maintain optimal printing parameters regardless of the base production speed, resolving the contradiction between speed and quality.
2Shape
If stretching effect is increased to prevent crease formation, then fabric remains flat for printing, but variable elongations occur, causing superimposing of individual colours in multicolor printing
Solution Approach 1:
The press roller is divided into multiple independently controlled zones, each applying a controlled stretching force. This segmentation ensures uniform tension distribution across the fabric width, preventing localized variable elongations that would cause color misalignment in multicolor printing.
Solution Approach 2:
The system incorporates sensors and control mechanisms that monitor fabric tension and stretching in real-time. This feedback allows the independently motorized roller zones to automatically adjust their speeds to maintain consistent fabric tension and prevent variable elongations, ensuring precise color alignment.
3Device complexity
If conventional roller printing equipment is used on non-woven-fabric, then equipment structure is simple, but fiber crushing and dragging occur, causing elongation and shrinkage
Solution Approach 1:
The press roller is segmented into multiple independently motorized zones, adding controlled complexity to the equipment structure. This segmentation enables precise control over the mechanical action on fibers, preventing crushing and dragging while maintaining a relatively simple overall equipment design.
Solution Approach 2:
The system replaces conventional uniform mechanical pressing with a controlled mechanical field generated by multiple independently controlled roller zones. This substitution allows gentle, distributed mechanical action that prevents fiber damage while maintaining dimensional stability.
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 solution enables high-speed printing of non-woven fabrics up to 400 m/min with optimal print quality, preventing creasing and fiber elongation, and ensuring consistent color alignment across the fabric width, thus overcoming the limitations of previous technologies.
Implementation Method 1
a suction system, not shown, holding the sheet of non-woven-fabric on the support roller
Implementation Method 2
The deposited dye is subsequently dried with hot air, thus fixing the print on the non-woven-fabric
Implementation Method 3
a control unit, not shown, having the function of monitoring the angular speeds and torque moments of the rotating bodies and, in the case of variations falling outside preset ratios, of correcting said angular speeds and torque moments
Data Source
AI summary
The present invention relates to a process and equipment (1) for creating prints on non-woven-fabric and, particularly, relates to a process and to equipment (1) which allows the creation of color prints on non-woven fabrics at high speed while at the same time maintaining optimal print quality on wet or dry product, either in-line with production or off-line. The NWF may be printed over only a small percentage with respect to its surface (2-3%) up to a coverage of 100% of its surface, depending on the use of the NWF itself, i.e.: personal hygiene, domestic hygiene, matting, non-woven fabric for clothing, table-cloths, handkerchiefs, curtains (furnishings), bags, containers for items.