Fixture Ring Stack for Uniform Polishing of Turbine Vanes
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Solution Overview
Problem
Conventional surface polishing methods, particularly for turbine vanes with TBC coatings, face issues such as mechanical strain, damage to porous surfaces, and inefficient polishing due to asymmetrical workpiece handling and indirect vibration transfer, leading to unsatisfactory surface roughness and uniformity.
Innovation Solution
A fixture system comprising radially oriented fixture rings that directly connect to the polishing container, allowing multiple substrates to be stacked and aligned radially around a central axis, with segments designed to protect and securely hold turbine vanes, ensuring even vibration transfer and minimizing contact with the container walls, and using thermoplastic polyurethane for flexibility and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing methods are used for turbine vanes with TBC coatings, then material removal and surface smoothing occur, but mechanical strain and damage to porous surfaces occur
Solution Approach 1:
The patent employs vibratory polishing where the polishing container is set into vibration, causing the workpieces to be treated by polishing elements that behave under vibration analogous to a viscid liquid. This vibratory action provides gentle surface treatment that achieves required surface roughness (Ra max. 0.3 μm for Aerospace, Ra max. 0.8 for power generation) while avoiding mechanical strain and damage to the porous TBC coatings.
Solution Approach 2:
The patent changes the physical state and motion parameters of the polishing system by introducing vibration at specific frequencies and amplitudes. The vibratory motion transforms the polishing elements' behavior from rigid mechanical contact to a fluid-like state, enabling effective material removal and surface smoothing without causing damage to the delicate porous coating structure.
2Device complexity
If turbine vanes are placed directly in the polishing container without proper fixtures, then the polishing process is simple, but the asymmetrical workpieces contact container walls causing damage and uneven polishing
Solution Approach 1:
The patent introduces guide apparatus as an intermediary between the polishing container and the turbine vane workpieces. The guide apparatus includes guide members spaced apart by spacers and a holder that positions and holds workpieces between the guide members, preventing direct contact with the container walls. This intermediary structure protects asymmetrical workpieces from damage while ensuring proper positioning for uniform polishing.
Solution Approach 2:
The guide apparatus is divided into segmented components including multiple guide members, spacers, and holders that can be independently positioned and adjusted. This segmentation allows the fixture system to adapt to different asymmetrical workpiece geometries while maintaining protection from wall contact and ensuring consistent polishing across all surfaces.
3Reliability
If workpieces are externally clamped in the polishing container, then positioning is secure, but mechanical strain and potential damage to workpieces occur
Solution Approach 1:
The patent uses vibratory motion to maintain workpiece positioning within the guide apparatus during polishing. The vibration keeps polishing elements in constant motion against the workpiece surfaces, ensuring reliable treatment without requiring strong external clamping forces that would induce mechanical strain on the workpieces.
Solution Approach 2:
The guide members and holders act as intermediaries that provide gentle yet secure positioning for the workpieces. Rather than externally clamping the workpieces with rigid fixtures, the guide apparatus uses spaced guide members that constrain workpiece movement while allowing the vibratory polishing process to proceed without inducing mechanical strain.
4Productivity
If traditional polishing apparatus are used, then the setup is simple, but vibration transfer is indirect leading to inefficient polishing and unsatisfactory surface uniformity
Solution Approach 1:
The patent directly transfers vibrations to the polishing container and workpieces through the guide apparatus, creating efficient vibratory polishing action. The vibration causes polishing elements to behave under vibration analogous to a viscid liquid, enabling uniform material removal and surface smoothing that achieves required surface roughness values (Ra max. 0.3 μm for Aerospace applications, Ra max. 0.8 for power generation turbines) with high efficiency and consistency across all workpiece surfaces.
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 solution enables efficient and uniform surface polishing of rotationally asymmetrical workpieces by directly transferring vibrations and providing comprehensive protection, reducing mechanical strain and achieving the required low surface roughness, thus improving the polishing process's efficiency and surface quality.
Implementation Method 1
a polishing container (100), which comprises a bottom ring (103), at least one fixture ring (105, 107, 109, 307, 309, 311) and a closing ring (113), the fixture rings (105, 107, 109, 307, 309, 311) being built by segments (103, 105, 107, 109, 111, 113, 115) that can be disassembled
Implementation Method 2
abrasive blasting techniques, for example with fine corundum, shot peening or cut-wire peening with hard steel bodies, with rust-free steel bodies or with ceramic blasting bodies
Data Source
AI summary
A segment of a fixture, the fixture being comprised of a number of such segments arranged to form a fixture ring, the segment comprising a carrier segment and a cap segment.