Calender Rolling and Stretching for Tape Thickness Uniformity
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Solution Overview
Problem
Existing tape manufacturing processes experience rapid neck-down during stretching, leading to uneven thickness and mechanical properties across the width of the tape, causing wrinkles and inhomogeneities, which become more pronounced with increasing sheet width.
Innovation Solution
A process that combines rolling and stretching on a calender, where the sheet is rolled in the nip between two rolls and then stretched on the surface of one roll, allowing for controlled neck-down and reduced edge effects, resulting in more homogeneous thickness and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet is stretched in air between two sets of rollers, then the stretching process is simple and quick, but the neck-down is very rapid causing uneven thickness and mechanical properties across the width
Solution Approach 1:
The stretching process is divided into two distinct stages: first rolling in the nip between calender rolls to establish initial contact and control, then stretching on the surface of a convex drum. This segmentation allows each stage to optimize for its specific function, preventing rapid uncontrolled neck-down while maintaining productivity.
Solution Approach 2:
The invention transitions from planar stretching between parallel rollers to curved surface stretching on a convex drum. This dimensional change from 2D to 3D geometry provides better control over the stretching trajectory and neck-down rate, enabling uniform thickness while maintaining high productivity.
2Productivity
If the sheet width is increased to produce wider tapes, then the productivity increases, but the rapid neck-down causes more pronounced differences in stretching behaviour and thickness variations
Solution Approach 1:
The sheet undergoes preliminary rolling in the calender nip before entering the stretching phase on the convex drum. This preliminary action pre-conditions the material, establishing controlled initial deformation that prevents runaway neck-down during subsequent stretching, even for wide sheets.
Solution Approach 2:
The calender rolls act as an intermediary between the sheet and the convex drum stretching surface. They provide controlled initial rolling that mediates the transition to stretching, preventing direct rapid neck-down and ensuring uniform deformation across the width.
3Manufacturing precision
If separate rolling and stretching stages are used, then each process can be optimized independently, but the overall process complexity increases and productivity decreases
Solution Approach 1:
The invention merges rolling and stretching into a single integrated process on the calender system. The calender rolls perform rolling in their nip while simultaneously serving as the convex drum for stretching on their surface, eliminating the need for separate stages and improving productivity while maintaining precision.
Solution Approach 2:
The calender system performs multiple functions: it rolls the sheet in the nip between rolls and simultaneously stretches it on the surface of the convex drum. This multi-functionality eliminates the need for separate rolling and stretching equipment, reducing process complexity and increasing productivity.
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 process produces tapes with improved homogeneity in thickness and mechanical properties, reducing sensitivity in subsequent stretching stages and enabling the integration of multiple stretching stages, thus enhancing the stability and quality of the tape production.
Implementation Method 1
the sheet is rolled into a rolled sheet in the nip between two rolls of a calender and the rolled sheet is stretched into a tape on the surface of one of the two calender rolls
Implementation Method 2
The speed of the rolled sheet on the surface of the calender roll is higher than the speed of the calender roll
Data Source
AI summary
A process for rolling and stretching of a sheet into a tape is provided. A sheet may be rolled into a rolled sheet in the nip between two rolls of the calender and the rolled sheet is stretched immediately thereafter into a tape on the surface of one of the two calender rolls. The speed of the rolled sheet on the surface of the calender roll may be higher than the speed of the calender roll. The position of the start of the neck-down of the rolled sheet and the rate of neck-down can be easily controlled by the proposed process.