Embossing Roller Geometry for Uniform Tissue Ply Deformation
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Solution Overview
Problem
Current embossing techniques for tissue paper impose high mechanical stress on cellulose fibers, leading to non-uniform deformation, weakening, and potential breakage, limiting the flexibility in choosing embossing patterns due to the anisotropic nature of cellulose material and the need to balance technical-functional requirements with stress constraints.
Innovation Solution
An embossing roller with protuberances of variable inclination and cross-sectional shape along their linear extension, allowing for modulation of mechanical stress by adjusting the angle and shape of the protuberances, which can be engraved with advanced techniques like laser and acid etching, to achieve uniform deformation and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional embossing techniques with fixed-geometry protuberances are used, then the embossing process is simple to implement, but the deformation of the cellulose ply is non-uniform and causes localized breakage
Solution Approach 1:
The embossing roller is equipped with protuberances that have variable cross-sectional shapes and/or variable inclinations along their linear extension. This allows different regions of the same protuberance to apply different stress distributions to the cellulose ply, achieving uniform deformation across the entire embossed area while maintaining a relatively simple overall roller structure.
2Strength
If embossing protuberances with high stress concentration are used, then the embossing effect is strong and aesthetically pleasing, but the cellulose fibers are weakened and prone to breakage
Solution Approach 1:
The invention modifies the geometric parameters of the embossing protuberances, specifically the cross-sectional shape and inclination angle, which directly affect the stress distribution. By optimizing these parameters, the design achieves both strong embossing effects and reduced fiber stress, resolving the contradiction between embossing effectiveness and fiber integrity.
Solution Approach 2:
The protuberances feature asymmetric cross-sectional shapes and variable inclinations rather than symmetric, uniform geometries. This asymmetric design allows for tailored stress distribution that concentrates embossing effect where needed while reducing stress on cellulose fibers, thereby maintaining fiber integrity during the embossing process.
3Shape
If modern laser and chemical etching techniques are used to create variegated embossing patterns, then the aesthetic appearance is greatly improved, but the ply experiences non-uniform deformation and wrinkle formation
Solution Approach 1:
The variable cross-sectional shapes and inclinations of the protuberances are specifically designed to compensate for the non-uniform stress distribution inherent in complex embossing patterns. This ensures that even aesthetically sophisticated patterns produce uniform deformation of the cellulose ply, preventing wrinkle formation while maintaining visual appeal.
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 approach enables uniform weakening of the cellulose ply, reducing the risk of breakage and allowing for more flexible design of embossing patterns, improving the aesthetic and functional properties of tissue paper products.
Implementation Method 1
The two rollers are pressed against each other so that the protuberances penetrate the lateral surface of the pressure roller as a result of the compressive deformation of the yielding coating of said pressure roller
Implementation Method 2
The cellulose material, forming the web material, which passes through the nip formed between the two rollers, is permanently deformed with the formation of embossing protrusions
Implementation Method 3
the embossing roller is provided with protuberances that penetrate an elastically yielding coating layer provided on the pressure roller
Data Source
Figure 1~2B
Figure 3
Figure 4~6
AI summary
The embossing unit comprises: at least one embossing roller (3) with a rotation axis (3A) and a substantially cylindrical surface with a plurality of embossing protuberances (P3) with linear extension; a pressure roller (5) with a yielding surface (5B); an embossing nip (Gl) defined between said pressure roller (5) and said embossing roller (3); a feed path of a web material (N) extending through said embossing nip (Gl). Along the linear extension thereof the embossing protuberances (P3) have a variable inclination with respect to the rotation axis (3 A) of the embossing roller (3) and a variable cross section along the longitudinal extension of said embossing protuberances.