Rounded Edge Coating for Turbomachine Blade Tip Durability
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Solution Overview
Problem
Existing coating methods for turbomachine components, such as blade tips, result in excessive material accumulation at sharp edges during galvanic deposition, leading to lateral projection and potential cracking under dynamic loads, which can compromise the component's strength and vibration resistance.
Innovation Solution
The method involves rounding the edges of the surface before coating to prevent excessive material accumulation, using a combination of brushing and grinding to create a smooth contour with a radius of curvature that matches or exceeds the coating thickness, thereby preventing lateral projection and reducing the risk of crack initiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If galvanic deposition is applied to a component with sharp edges, then coating coverage is improved, but excessive material accumulation occurs at the edges leading to lateral projection
Solution Approach 1:
The edge is rounded before the galvanic deposition process to prevent excessive material accumulation. This preliminary geometric modification ensures that field lines are not concentrated at sharp edges during coating, thereby avoiding lateral projection while maintaining adequate coating coverage.
Solution Approach 2:
The edge geometry parameter is changed from sharp to rounded with a specific radius of curvature (at least 0.5 times the coating thickness). This parameter change modifies the electric field distribution during galvanic deposition, preventing material accumulation while preserving coating coverage.
2Reliability
If coating is applied to sharp edges, then protective coverage is improved, but mechanical tension increases under dynamic loads leading to crack formation
Solution Approach 1:
The edge is rounded before coating to eliminate geometric stress concentrators. This preliminary action prevents the formation of high mechanical tension zones that would otherwise initiate cracks under dynamic loads, thereby maintaining both protective coverage and vibration resistance.
Solution Approach 2:
The rounding process removes the harmful sharp edge geometry that causes stress concentration, converting a potential failure point into a beneficial smooth transition zone. This eliminates crack initiation sites while preserving the protective function of the coating.
3Shape
If edge rounding is performed before coating, then lateral projection is prevented, but additional processing steps are required
Solution Approach 1:
Edge rounding is performed as a preliminary step before coating to establish the correct geometric foundation. This single preliminary action prevents lateral projection throughout the entire coating process, eliminating the need for complex post-coating corrections or additional control 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
This approach enhances the vibration resistance of coated components by minimizing mechanical tension and preventing crack formation, particularly in high oscillation environments, as demonstrated by high cycle fatigue tests.
Implementation Method 1
from a concentration of field lines on the unrounded, sharp edge during an galvanic deposition process
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a method for coating a component (10), wherein the component (10) has a first and a second surface (41, 42), and wherein the first and the second surface (41, 42) adjoin each other at an edge (35), in which method i) first rounds the edge (35) between the first and second surface (41, 42), and ii) then applies a coating (30) to the first surface (41).