Impeller Flow Path Elongation Jig for Uniform Fluid Polishing
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Solution Overview
Problem
Impellers formed by additive manufacturing methods exhibit increased surface roughness and variation, making uniform polishing of inner flow path surfaces difficult, especially due to their complex shape and small cross-sectional areas.
Innovation Solution
An impeller manufacturing method combining additive manufacturing with hot isostatic pressing (HIP) and fluid polishing using a polishing fluid with abrasive grains, along with an impeller flow path elongation jig that extends radially outside the impeller to maintain pressure and prevent cross-sectional area increase at the outlet, ensuring uniform polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If additive manufacturing method is used to form impeller, then manufacturing complexity is reduced and welding is eliminated, but surface roughness increases and uniformity decreases
Solution Approach 1:
The patent applies preliminary action by performing HIP processing immediately after additive manufacturing to densify the metal powder structure and reduce internal voids before polishing. This preliminary densification creates a more uniform substrate that responds better to subsequent polishing operations, addressing the surface roughness issue caused by additive manufacturing's layer-by-layer construction
Solution Approach 2:
The patent replaces traditional mechanical polishing methods with fluid polishing using pressurized polishing fluid containing abrasive grains. This substitution allows the polishing medium to reach complex internal flow path surfaces that mechanical tools cannot access, while the fluid's ability to adapt to varying geometries provides more uniform surface treatment across the impeller's complex topology
2Manufacturing precision
If mechanical polishing is used for flow path, then surface roughness can be reduced, but entire inner peripheral surface cannot be polished due to complex shape
Solution Approach 1:
The patent uses hydraulic principles by circulating pressurized polishing fluid through the impeller's internal flow paths. The fluid's ability to be pumped and pressurized allows it to reach all internal surfaces including narrow passages and complex geometries, providing uniform polishing coverage throughout the entire flow path system where mechanical polishing cannot reach
Solution Approach 2:
The polishing fluid performs multiple functions simultaneously: it carries abrasive grains for material removal, provides cooling to the being-polished surfaces, and acts as a lubricant. The fluid circulation system serves itself by continuously recycling and repressurizing the polishing medium, maintaining consistent polishing action throughout the process without requiring external intervention for each zone
3Manufacturing precision
If polishing fluid flows through flow path outlet, then polishing can be performed, but pressure decreases and cross-sectional area increases rapidly
Solution Approach 1:
The elongation jig is installed beforehand to modify the flow path geometry at the outlet region before polishing begins. By pre-elongating the outlet section, the system prevents the rapid pressure drop that would otherwise occur when polishing fluid exits the impeller, maintaining sufficient pressure for effective polishing throughout the entire flow path including the outlet region
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 method allows for effective polishing of the inner peripheral surface of the flow path, improving surface roughness uniformity and impeller strength by removing internal defects and maintaining consistent pressure for uniform polishing across the flow path.
Implementation Method 1
an HIP processing step of processing the impeller, which is formed in the impeller forming step, by a hot isostatic pressing
Implementation Method 2
a flow path polishing step of causing a polishing fluid containing abrasive grains to flow through a flow path formed between the disk, the cover, and the blades in the impeller after the HIP processing step while pressurizing the polishing fluid to perform fluid polishing
Data Source
AI summary
An impeller manufacturing method includes: integrally forming an impeller by an additive manufacturing method using a metal powder, the impeller including a disk which has a disk shape about an axis, a plurality of blades which are formed on a surface facing a first side in an axial direction of the disk with gaps therebetween in a circumferential direction about the axis, and a cover which covers the plurality of blades from the first side in the axial direction; processing the integrally formed impeller by a hot isostatic pressing; and causing a polishing fluid containing abrasive grains to flow through a flow path formed between the disk, the cover, and the blades in the impeller after the processing with the hot isostatic pressing and while pressurizing the polishing fluid to perform fluid polishing.