Drop-on-Demand Coating Nozzles for Uniform Layer Thickness
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Solution Overview
Problem
Existing methods for applying viscous coating materials on large surfaces, such as architectural paints and industrial coatings, are inefficient due to low productivity, non-uniform layer thicknesses, and the need for extensive preparations to prevent paint mist and splatters, especially when applying non-graphical coatings.
Innovation Solution
A portable, manually or motor-driven coating device with drop-on-demand printing nozzles that apply coating material as dots or spray dots, allowing for variable output frequency based on movement speed, ensuring uniform layer thickness and minimizing overspray by using a system of wheels or sliding elements for precise control and contactless application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manual brush or roller application is used, then ease of operation is maintained, but productivity is low and layer thickness uniformity is poor
Solution Approach 1:
The coating application is segmented into discrete droplets applied by individual nozzles arranged in rows, allowing precise control of each droplet's placement while maintaining high-speed movement. The coating device itself is segmented into multiple independent nozzles that can be controlled separately.
Solution Approach 2:
The manual mechanical application method (brush or roller) is replaced with a controlled droplet ejection system that uses pneumatic or electrostatic fields to discharge coating material precisely where needed, eliminating the need for physical contact with the surface.
2Productivity
If spray equipment is used, then productivity increases, but harmful factors increase due to overspray and paint mist
Solution Approach 1:
Instead of spraying coating material over a wide area, the system applies coating material locally only at the precise points where droplets are discharged from the nozzles. Each nozzle targets a specific location, ensuring coating material is deposited only where needed on the surface.
Solution Approach 2:
The harmful overspray component is extracted and eliminated from the system by using contactless drop-on-demand nozzles that discharge coating material directly onto the surface without creating mist or spray clouds that would contaminate the environment.
3Productivity
If drop-on-demand printing nozzles are used, then productivity and layer thickness uniformity improve, but device complexity increases
Solution Approach 1:
The drop-on-demand nozzle system serves multiple functions: it applies coating material, controls layer thickness, ensures uniform distribution, and can adapt to different coating patterns all through a single integrated device, replacing multiple separate functions that would otherwise be needed.
Solution Approach 2:
The system controls coating application by changing parameters such as droplet size, discharge frequency, and nozzle-to-surface distance dynamically, allowing precise control of layer thickness and uniformity without mechanical adjustment of the application mechanism.
4Object-generated harmful factors
If contactless drop-on-demand method is used, then harmful factors are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The system incorporates feedback mechanisms that monitor the position and state of the coating application in real-time, allowing the control system to adjust droplet discharge parameters dynamically to maintain precise placement and compensate for any deviations in nozzle position or surface geometry.
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 method enables high-speed application with precise control over layer thickness, reducing environmental contamination and eliminating the need for preparatory measures to protect against paint mist, while allowing for clean and efficient application of both graphical and non-graphical coatings.
Implementation Method 1
the discontinuous discharge of discrete drops or discrete droplet mist from a pressure nozzle 2, wherein free-flying liquid impacts on the surface to be coated, and thus produces an imprinted dot 9
Implementation Method 2
The working principle of the micro-pneumatically printing nozzles 2 according to (1) allows printing higher viscous and particle-loaded coating materials by adopting the contactless drop-on-demand (DOD)-method
Data Source
AI summary
Provided is a method of coating at least an area of a surface by a Drop-on-Demand (DOD) method, comprising the steps of providing a DOD dispensing head (1) with at least two individually controllable nozzles (2) arranged in a row, which is moved by a robotic device, applying a movement to the DOD dispensing head parallel while maintaining a distance between the nozzles (2) and the surface, wherein the movement comprises a rotation of the dispensing head around an axis perpendicular to the surface, dispensing discrete amounts of a the liquid coating material through the at least one nozzle onto the surface, wherein firing of the at least 2 nozzles is triggered non-synchronously by a control unit.