Polyhedral Embossing Rolls for Uniform Foil Pressure
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Solution Overview
Problem
Current embossing technologies face challenges in producing fine, uniform embossing patterns on thin foils with high precision and reducing axial tension, while also achieving visually effective decorative effects, which is costly and limited by the manufacturing of specialized rolls, especially for thinner metalized paper foils.
Innovation Solution
A method and apparatus using a pair of rolls with polyhedral projections and recesses arranged in specific periodicities and orientations to ensure homogeneous pressure distribution and precise embossing, allowing for checkered-style and larger uniformly embossed areas with reduced axial contraction, and the option to produce shading effects for optical enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pin up-pin up system with steel rolls carrying small teeth is used, then embossing capability is achieved, but axial tension is high and perforation risk increases
Solution Approach 1:
The invention changes the geometric parameters of the embossing structures by using polyhedral projections with specific face orientations (first, second, third, and fourth faces at different angles) instead of simple pin-up structures. This parameter change allows for distributed pressure application that reduces axial tension while maintaining embossing capability.
Solution Approach 2:
The invention employs a composite approach by combining multiple types of projections (first type with specific orientation, second type with different orientation) on the same roll surface. This composite structure enables simultaneous achievement of embossing effect and reduced axial contraction through differentiated pressure distribution patterns.
2Manufacturing precision
If specialized embossing rolls with precise topography are manufactured, then fine embossing quality is achieved, but manufacturing cost increases prohibitively
Solution Approach 1:
The invention segments the embossing function into standardized polyhedral projection units that can be manufactured independently and then arranged in different patterns on rolls. This segmentation allows for cost-effective manufacturing of individual projection elements while achieving fine embossing through their collective arrangement.
Solution Approach 2:
The invention uses polyhedral projections that can be replicated and arranged in periodic patterns across the roll surface. This copying approach allows a single projection design to be manufactured once and then repeated in various configurations to achieve different embossing effects, reducing overall manufacturing cost while maintaining precision.
3Productivity
If conventional embossing patterns are used, then production is straightforward, but axial contraction and non-uniform pressure distribution occur
Solution Approach 1:
The invention introduces asymmetry in the polyhedral projection design with specific face orientations (first face, second face, third face, fourth face) that are not uniformly distributed. This asymmetric arrangement creates more uniform pressure distribution across the embossed area while maintaining production efficiency through periodic patterning.
Solution Approach 2:
The invention applies local quality by assigning different orientations and types of polyhedral projections to different local areas of the roll surface. This allows optimization of pressure distribution in specific zones while maintaining overall production efficiency through systematic arrangement of these localized variations.
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
Enables high-precision, cost-effective fine embossing with reduced axial contraction and improved optical properties, achieving 100% embossing coverage and maintaining the theoretical reflection intensity of metalized sheets.
Implementation Method 1
a first subset of the plurality of positive projections being disposed with a first periodicity on a first grid in axial direction and a second periodicity on the first grid in circumferential direction
Implementation Method 2
enabling a homogeneous distribution of pressure to the material
Data Source
Figure 1a~1b
Figure 1c
Figure 2a~2b
AI summary
An embossing method allowing to emboss a material on both sides comprises feeding the foil material into a roll nip between a pair of a first roll and a second roll, providing the first roll and the second roll each with a plurality of positive projections and a plurality of negative projections of identical shaped polyhedral structures, a first subset of the plurality of positive projections being disposed with a first periodicity on a first grid in axial direction and a second periodicity on the first grid in circumferential direction on the first roll, and a second subset of the plurality of negative projections being disposed with the first periodicity in axial direction and the second periodicity in circumferential direction on the first grid interwined with the positive projections, in axial and circumferential directions respectively, and projections complementary to the first grid, on the second roll, each of the positive projections and the negative projections on the first roll during operation of the rolls and in the roll nip being surrounded on all sides by positive projections and negative projections on the second roll, the positive projections of the first roll together with alternating corresponding negative projections on the second roll forming during the operation of the rolls and in the roll nip, a first straight line substantially parallel to the axial direction, and the negative projections of the first roll together with alternating corresponding positive projections on the second roll forming during the operation of the rolls and in the roll nip, a second straight line substantially parallel to the axial direction. The positive projections and the negative projections are such that in the axial direction on the first roll each positive projection shares a lateral base border with at least one negative projection adjacent to the positive projection, and during the operation of the rolls and in the roll nip, all lateral oblique surfaces of the positive and negative projections of the first roll are just above the surface in full faced view with the corresponding lateral oblique surfaces of the respective negative and positive projections of the second roll, thereby enabling a homogeneous distribution of pressure to the material.