Film Guide Roller Suction and Coating for Scratch Prevention
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Solution Overview
Problem
Existing rollers for guiding film webs often cause damage due to local relative movements between the film and the roller, particularly at the leading and separation edges, leading to scratches and tension issues, even with minimal movement or air entrainment reducing the radially inward force.
Innovation Solution
The roller design incorporates a suction device at the leading edge to remove entrained air, uses Nano cross grooves and sealing elements to enhance adhesion, and applies additional forces through electrical charging, coatings, and mechanical pressing to minimize movement and increase static friction, while also considering the roller's diameter and surface treatments to reduce deflection and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If negative pressure is applied through openings in the roller to hold the film web firmly, then the film web adheres better to the roller surface, but local relative movements occur at the leading and separation edges causing scratches and damage
Solution Approach 1:
The suction device is positioned directly at the leading edge to preemptively remove entrained air before it can cause damage. This preliminary action prevents the harmful effect of air entrapment that would otherwise cause the film web to lift and create scratches during contact with the roller surface.
Solution Approach 2:
A coating layer is applied to the roller surface to act as an intermediary between the roller and the film web. This coating reduces direct contact friction and prevents scratching while maintaining the necessary adhesion through the negative pressure system.
2Object-affected harmful factors
If the roller surface is made smooth to prevent scratching, then the film web moves without damage, but the radially inwardly directed force is reduced allowing more relative movement
Solution Approach 1:
The roller surface has different properties in different regions: the areas with openings maintain smoothness to prevent scratching, while the coating applied to the surface provides localized friction control. The coating is specifically applied to areas where the film web contacts the roller, providing the necessary friction without compromising the smoothness needed to prevent scratches.
3Force
If air is allowed to enter through the openings to reduce the radially inwardly directed force, then the film web can move more freely, but the adhesion is reduced causing more relative movement and potential damage
Solution Approach 1:
The suction device extracts the entrained air from between the film web and the roller surface at the leading edge. By removing the air that would otherwise reduce adhesion, the system maintains strong radial force and prevents unwanted relative movement while still allowing controlled movement at the separation edge.
4Force
If sealing elements are added to prevent false air from being sucked in, then the radially inwardly directed force is increased, but the device complexity increases
Solution Approach 1:
Flexible sealing elements are integrated into the roller structure to prevent false air from entering through the openings. These sealing elements can be simple rubber or polymer strips that flex with the roller rotation, providing effective sealing without requiring complex mechanical sealing mechanisms.
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
The solution effectively minimizes damage to the film web by reducing relative movement and enhancing adhesion, ensuring the film web adheres better to the roller surface without sustaining damage, even with minimal movement, thereby preventing scratches and tension issues.
Implementation Method 1
The suction device comprises a suction nozzle which is directed toward the leading edge. The suction nozzle is arranged on a suction body which can be subjected to a negative pressure.
Implementation Method 2
the roller comprises openings on it peripheral surface, which openings are subjected to a negative pressure provided from a negative pressure source. This causes the film web to be suctioned to the peripheral surface.
Implementation Method 3
The roller is, in particular, surface-treated, coated or refined in some other way to avoid damage as far as possible if there is a local movement of the film web relative to the peripheral surface
Data Source
AI summary
The inventions describes a roller for guiding a film web and for subjecting the film web to an at least partially radially inwardly directed force, wherein openings are provided in the surface for applying the inwardly directed force, wherein the openings can be subjected at least partially to a negative pressure from a negative pressure source.For this purpose, at least one device for increasing the radially inwardly directed force and/or the roller are/is configured such that the film web is movable relative to the roller surface without damage being brought about on the film web.