Air Cutting Device for Rigid Board Webs Using Vacuum Friction
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Solution Overview
Problem
Existing cutting devices for fibrous webs, particularly in board machines, are complex, require significant space, and are not suitable for cutting rigid boards, as they struggle to effectively manipulate and cut the web due to the rigidity of the material.
Innovation Solution
An air cutting device utilizing a blower with a flow-preventing element and a friction element with a non-planar surface profile to create a vacuum, which increases friction and allows for efficient manipulation, cutting, and deceleration of the fibrous web by using air jets to apply a perpendicular force component, enabling cutting without mechanical knives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional mechanical cutting knives are used to cut rigid board webs, then cutting can be achieved, but the device becomes complex and requires significant space
Solution Approach 1:
The patent replaces the traditional mechanical knife cutting system with a pneumatic system. A blower directs air flow against the moving web to create a jet that lifts and positions the web, while a friction element with vacuum suction holds and manipulates the web for cutting. This substitution eliminates complex mechanical knife mechanisms while achieving effective cutting of rigid board webs.
Solution Approach 2:
The invention uses pneumatic principles throughout: a blower creates air jets to manipulate the web, and a vacuum system (via the friction element) holds and positions the web during cutting. This pneumatic approach replaces mechanical systems, reducing device complexity and space requirements while maintaining cutting effectiveness for rigid materials.
2Productivity
If air cutting devices are used for flexible paper webs, then cutting is effective, but the devices fail to manipulate rigid board webs due to insufficient friction
Solution Approach 1:
The friction element is designed with a non-planar, contoured surface profile that dynamically adapts to the web material. The surface geometry creates varying degrees of contact and friction depending on the material properties - providing sufficient friction for rigid board webs while maintaining effectiveness for flexible paper webs. This dynamic adaptation resolves the reliability issue across different material types.
Solution Approach 2:
The invention changes the physical parameters of the friction surface from a traditional planar design to a contoured, non-planar profile. This parameter change increases the friction coefficient and contact area with the web, enabling reliable manipulation of rigid board webs while preserving the cutting effectiveness previously achieved with paper webs.
3Area of stationary object
If the cutting device is positioned below the doctor knife, then space is available, but the device cannot effectively cut rigid boards due to limited access and space
Solution Approach 1:
The friction element is positioned above the doctor knife, utilizing the vertical space dimension rather than being constrained to the horizontal plane below the doctor knife. This dimensional repositioning provides adequate access and space for the pneumatic components to effectively manipulate and cut rigid board webs, overcoming the spatial limitations of traditional positioning.
4Force
If mechanical knives are used for cutting, then cutting force is sufficient, but the device requires large space and complex structure
Solution Approach 1:
The patent replaces the mechanical knife system that provides cutting force through physical contact with a pneumatic system. The blower generates high-velocity air jets that lift and position the web, while the vacuum-friction system provides the necessary holding and manipulating force. This substitution achieves sufficient cutting force for rigid boards without requiring large mechanical structures.
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 provides efficient manipulation and cutting of rigid board webs by increasing friction, allowing for precise control and safety, with the ability to be located in a smaller space, simplifying the apparatus and enabling cutting above the doctor knife, suitable for both paper and board webs.
Implementation Method 1
a friction element with a non-planar surface profile against which the fibrous web is pressed to apply a friction force resisting the motion of the web, wherein the surface profile of the friction element is shaped such that said blows cause a vacuum on the surface of the fibrous web
Implementation Method 2
a friction element against which the fibrous web is arranged to be pressed partially from the effect of said force component to apply a friction force resisting the motion of the web
Implementation Method 3
at least two blowers provided with flow-preventing elements arranged to produce blows against the motion direction of the fibrous web and in the motion direction of the fibrous web and at least mainly in the direction of the fibrous web against the plane of the fibrous web in order to apply a perpendicular force component to the fibrous web
Data Source
AI summary
The invention relates to a device and a method for manipulating a fibrous web (10). The device comprises at least one blower (21A, 21B) provided with a flow-preventing element (24A, 24B) which is arranged to produce at least one blow (26A, 26B) substantially in the direction of the fibrous web (10), and a friction element (28) against which the fibrous web (10) is arranged to be pressed at least partially from the effect of said blow (26A, 26B) and flow-preventing element (24A, 24B) to apply a friction force resisting the motion of the fibrous web (10) to the fibrous web (10). According to the invention, the blow (26A, 26B) is directed substantially away from the friction element (28) and the friction element (28) comprises a surface profile which is arranged such that, from the effect of said at least one blow (26A, 26B), a continuous vacuum is created on the surface of the fibrous web (10) on the side of the friction element (28). Due to its intensified friction effect, the device according to the invention is applicable especially for board and, by means of it, it is possible to form e.g. an air cutting device in the tail-threading section of a board machine.