Variable Nozzle Gap Profiling for Uniform Web Coating
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Solution Overview
Problem
Existing coating devices for fibrous material webs, such as paper, packaging, or board materials, struggle to uniformly apply coating mediums like starch solutions due to web width variations caused by shrinkage, leading to uneven quality and wastage.
Innovation Solution
An application device with a nozzle featuring a variable outlet gap and profiling means, such as mechanical or electromagnetic actuators, to adjust the gap width over the nozzle's width, allowing precise application of coating medium based on the web's specific needs, and optionally using a blower head for a spray curtain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a uniform coating medium quantity is applied across the entire web width, then the coating is sufficient in regions with high demand (web center), but it results in over-metering in regions with lower demand (edge regions), causing economic and ecological waste
Solution Approach 1:
The patent applies local quality by varying the outlet gap width of the application nozzle across its width. The nozzle has a smaller gap width at edge regions and a larger gap width at center regions, matching the different coating demands of different web areas. This allows the coating medium to be applied in quantities specifically adapted to local requirements, avoiding both over-metering and under-metering.
Solution Approach 2:
The patent implements dynamics by making the outlet gap width variable rather than fixed. The gap width can be adjusted along the width direction of the application nozzle, enabling dynamic adaptation of coating quantity to different web regions. This dynamic configuration allows the system to respond to varying web properties across the width without requiring multiple nozzles or complex metering systems.
2Reliability
If the coating medium quantity is increased to ensure sufficient strength in high-demand regions, then web quality is improved, but coating medium consumption increases unnecessarily in low-demand regions
Solution Approach 1:
The application nozzle is designed with locally adapted gap widths that correspond to the local coating requirements of different web regions. The center region, which has higher coating demand due to web shrinkage characteristics, receives a larger gap width and thus more coating medium. The edge regions, which have lower demand, receive a smaller gap width and thus less coating medium, ensuring each region gets exactly what it needs for optimal quality.
Solution Approach 2:
The patent changes the geometric parameter of the outlet gap width along the width direction of the application nozzle. By varying this physical dimension, the system directly controls the coating medium flow rate to different web regions, achieving optimal coating quantity distribution without needing to change other parameters such as nozzle pressure or coating medium viscosity.
3Ease of manufacture
If a fixed outlet gap width is used in the application nozzle, then the device structure is simple, but it cannot adapt to the varying coating requirements across different web width regions
Solution Approach 1:
The application nozzle incorporates a variable outlet gap width that can be configured along its width direction. This dynamic geometric feature allows a single nozzle structure to adapt to different coating requirements across web regions. The variable gap width can be implemented through various mechanisms such as adjustable baffles, flexible membranes, or precision-machined profiles, maintaining relative structural simplicity while achieving high adaptability.
Solution Approach 2:
The nozzle design incorporates local variations in gap width to match local coating demands. Different sections of the nozzle have different gap widths - narrower at the edges and wider at the center - creating a profiled coating distribution. This local quality approach allows the single nozzle to function as multiple nozzles would, adapting to web variations without increasing overall system complexity.
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 uniform coating application across the web width, reducing waste by matching coating quantities to local requirements, enhancing web quality, and minimizing mechanical wear through actuator design.
Implementation Method 1
an application nozzle having an outlet gap which is designed to produce a film of coating medium or a curtain of coating medium; said application nozzle having profiling means in order to vary the gap width of said outlet gap over the width of said application nozzle; said application nozzle further having a blower head configured to generate a linear jet of gaseous medium, and wherein an impingement line is defined along which the linear jet of gaseous medium impinges on the film or the curtain of coating medium for forming a spray curtain
Data Source
AI summary
An application device and method for coating a fibrous material web, in particular a paper, packaging or board web. The application device has an application nozzle for applying a coating medium, in particular a starch solution, to a moving surface and the application nozzle has an outlet gap which extends in the width direction of the application nozzle for producing a film of coating medium or a curtain of coating medium. The application nozzle has a gap width across its width direction that may be varied by profiling devices.