Turbomachine Blade Shroud Machining for Local Thickness Control
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Solution Overview
Problem
Existing methods for machining turbomachine blades with shrouds fail to account for varying strength and weight requirements across different areas, particularly around recesses and reinforcement ribs, leading to suboptimal stress distribution and weight management.
Innovation Solution
A method involving multiple machining paths, such as grinding or milling, to customize the thickness of the shroud's outer surface, allowing for sections with uniform or different strength and weight properties by adjusting material removal based on position and path, enabling improved stress distribution and creep behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single machining path is used to machine the outer surface of the shroud, then the manufacturing process is simple and efficient, but the strength and weight requirements of different areas cannot be satisfied
Solution Approach 1:
The machining process is divided into multiple segments with different machining paths (first machining path and second machining path) to address different areas of the shroud. The first machining path machines along the circumferential direction, while the second machining path machines in a different direction, allowing each segment to optimize for specific strength requirements in different regions of the shroud.
Solution Approach 2:
Different areas of the shroud are given different local qualities through selective machining. By applying different machining paths to different regions, the shroud achieves varying thickness profiles that provide enhanced strength where needed (such as near recesses and reinforcement ribs) while maintaining lighter weight in less critical areas.
2Ease of manufacture
If material is removed uniformly from the shroud, then the manufacturing process is straightforward, but the weight cannot be optimized for different strength requirements
Solution Approach 1:
The machining process applies different material removal rates to different areas of the shroud. The first machining path removes material along the circumferential direction, while the second machining path removes material in a different pattern, creating local variations in thickness that optimize the weight-strength ratio for each specific region of the shroud.
Solution Approach 2:
The weight optimization is achieved by segmenting the material removal process into distinct phases with different machining paths. This allows the shroud to have non-uniform thickness distribution, reducing weight in areas where full strength is not required while maintaining adequate thickness in critical load-bearing regions.
3Strength
If the shroud thickness is increased to meet strength requirements, then the strength is improved, but the weight increases and stress distribution is not optimized
Solution Approach 1:
Instead of uniformly increasing shroud thickness, the invention applies localized thickness variations through different machining paths. Critical areas such as regions near recesses and reinforcement ribs receive enhanced thickness through selective machining, while non-critical areas maintain lighter thickness, optimizing the overall strength-to-weight ratio.
Solution Approach 2:
The shroud is segmented into different zones with different thickness requirements. The multi-path machining process creates this segmentation by applying different material removal patterns to different regions, allowing each zone to have the precise thickness needed for its specific structural role.
4Weight of moving object
If the shroud is machined to reduce weight, then the weight is reduced, but the stress distribution and creep behavior are not optimized
Solution Approach 1:
The machining process creates local quality variations in the shroud thickness that simultaneously address weight reduction and stress distribution optimization. By carefully controlling which areas are machined and to what extent, the process ensures that weight is reduced in non-critical areas while maintaining adequate thickness in areas subject to high stress and creep loads.
Solution Approach 2:
The shroud is segmented into weight-critical and stress-critical zones, with the multi-path machining process treating each segment differently. This segmentation allows weight reduction through material removal in appropriate areas while preserving or enhancing thickness in areas where stress distribution and creep resistance are paramount.
Data Source
AI summary
A method for machining a blade and a blade for a turbomachine comprising a shroud which is positioned on a tip side of the blade. The shroud has an outer surface with at least one circumferential fin arranged thereon, whereby at least one section of the outer surface beside the at least one fin is processed in at least two manufacturing steps. At least one first section of the outer surface is processed to have a first shape and at least one second section of the outer surface is processed to have a second shape.