Distortion-Free Coating of Bidirectionally Curved Surfaces
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Solution Overview
Problem
Existing methods for coating complex 3-dimensional surfaces with bidirectional curvature face challenges in achieving distortion-free and uniform coatings, particularly in terms of surface geometries with varying curvatures in multiple directions, leading to issues like color differences and uneven coating due to the difficulty in adjusting print head geometry.
Innovation Solution
A method involving the division of the workpiece surface into grid areas, projection of these areas onto the print head trajectory along the normal vector, and adjustment of 2D decorative print data based on the grid projection, allowing for a 2-dimensional mode of operation that compensates for height differences and surface curvatures, ensuring homogeneous coating density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the printhead is adapted to the specific surface geometry of the product, then the coating uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent pre-calculates and stores the mapping relationship between 2D printhead coordinates and 3D workpiece surface coordinates before the coating process. This preliminary preparation allows the system to compensate for surface curvature effects without requiring real-time geometric adaptation of the printhead, thereby maintaining coating uniformity while avoiding complex device modifications.
Solution Approach 2:
The patent creates a digital model (copy) of the workpiece surface geometry and uses this virtual representation to calculate coordinate transformations. Instead of physically adapting the printhead to match the complex surface geometry, the system uses the digital copy to pre-compute the necessary coordinate mappings, simplifying the physical device while achieving accurate coating on curved surfaces.
2Ease of manufacture
If standard coating methods are used on curved surfaces, then the process simplicity is maintained, but coating distortion and color variations occur
Solution Approach 1:
The system performs preliminary calculation of the mapping relationship between 2D printhead coordinates and 3D surface coordinates before coating. This pre-computation enables standard coating equipment to achieve uniform results on curved surfaces by compensating for geometric distortions through software algorithms rather than hardware modifications.
Solution Approach 2:
The patent transforms the coating approach by changing the coordinate system parameters and mapping relationships between the printhead and workpiece surface. By adjusting the coordinate transformation parameters based on the workpiece geometry, the system maintains process simplicity while achieving uniform coating on complex surfaces.
3Area of stationary object
If the workpiece surface is divided into multiple travel paths, then the coverage area is increased, but the number of paths increases processing time
Solution Approach 1:
The patent pre-calculates the optimal travel paths and their corresponding 2D coordinate mappings before the coating process. This preliminary planning allows the system to efficiently organize the division of the workpiece surface into multiple paths, minimizing the total number of paths required while ensuring complete coverage and reducing processing time.
Data Source
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AI summary
The invention relates to a method for distortion-free coating of workpieces having bidirectionally curved surfaces. In the method according to the invention, on the basis of provided digital 2D decoration data and digital 3D surface profile data of a workpiece to be coated, the workpiece surface is divided into grid areas; the workpiece surface is divided into one or more paths of travel of a coating head; the grid areas are projected onto the printhead path of travel along the normal vector of the path of travel; for each grid area the 2D decoration print data of the decoration are adapted as a function of the results of the grid projection and the 2D decoration print data, and the workpiece surface is coated on the basis of the adapted decoration print data. The present invention further relates to a system for carrying out the method according to the invention.