Semi-Solid Turbine Wheel Manufacturing via Segmented Die
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Solution Overview
Problem
Current manufacturing methods for turbocharger wheels, such as casting, face challenges with oxide defects, microstructure control, and consistency, leading to reduced durability and reliability, while alternative methods like semi-solid forming have not been applied to complex shapes like turbocharger wheels.
Innovation Solution
A method using a die assembly with an outer die and inner die cartridge assembly to inject semi-solid metal alloys into blade cavities, maintaining temperature and pressure within specific ranges, and employing a pre-formed hub or forming blades on a machined hub, with careful alloy selection and tooling design to achieve high-quality, cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional casting methods are used to manufacture turbocharger wheels, then production cost is reduced and manufacturing simplicity is improved, but oxide defects and microstructure control issues arise that reduce durability and reliability
Solution Approach 1:
The invention changes the physical state parameter of the metal alloy from liquid to semi-solid before injection. By heating the alloy to a semi-solid state (between solidus and liquidus temperatures) and maintaining it in that state during injection, the process achieves both manufacturing simplicity and improved reliability. The semi-solid state allows the material to flow into complex mold cavities while eliminating oxide defects associated with liquid casting.
Solution Approach 2:
The invention utilizes the phase transition of the metal alloy between solid and liquid states. The alloy is heated to and maintained in a semi-solid phase (containing both solid and liquid portions) during the injection process. This phase transition approach allows the material to exhibit both flow characteristics (like liquid) and structural integrity (like solid), resolving the contradiction between ease of manufacture and reliability.
2Ease of manufacture
If conventional casting methods are used, then production cost is reduced, but microstructure consistency and homogeneity cannot be controlled
Solution Approach 1:
By changing the temperature parameter to maintain the alloy in a semi-solid state during injection, the invention achieves consistent microstructure formation. The controlled semi-solid state ensures uniform grain structure and homogenous material properties throughout the casting, while the injection process itself remains cost-effective compared to multiple processing stages.
3Reliability
If semi-solid forming is applied to complex shapes like turbocharger wheels, then durability and microstructure control are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention applies preliminary action by pre-heating the metal alloy to a semi-solid state before injection. This preliminary preparation of the material allows it to be injected into complex turbocharger wheel shapes while maintaining durability benefits. The semi-solid state is achieved and maintained throughout the injection process, enabling complex geometry formation without excessive process complexity.
4Ease of manufacture
If liquid metal casting is used, then manufacturing simplicity is maintained, but oxide defects reduce component durability
Solution Approach 1:
The invention changes the temperature parameter of the metal alloy from liquid state to semi-solid state during the casting process. By maintaining the alloy in a semi-solid state (between solidus and liquidus temperatures) during injection, the process eliminates oxide defects that form in liquid metal casting, while preserving manufacturing simplicity through a single-step injection process.
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 method achieves high-quality turbocharger wheels with improved durability and cost-effectiveness, comparable to components machined from forgings, by controlling microstructure and eliminating defects, while maintaining the complexity and precision required for turbocharger applications.
Implementation Method 1
a method for forming a turbine or compressor wheel using a die assembly comprising an outer die and an inner die cartridge assembly, the method comprising the steps of assembling the inner die cartridge assembly from a plurality of die segments so that the cartridge assembly defines a central hub cavity and a plurality of blade cavities extending outwardly from the hub cavity, said blade cavities being defined between adjacent die segments, inserting the cartridge assembly into the outer die, injecting a semi-solid metal alloy into the die so that it flows into the cartridge assembly and the blade cavities, maintaining temperature and pressure within the cartridge assembly within predetermined ranges during the injection stage
Data Source
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AI summary
A method for forming a turbine or compressor wheel from a semi-solid material uses a die assembly that has an inner cartridge made up from a plurality of segments and an outer die. The semi-solid material is injected under pressure and high temperature into the die so that it flows into blade cavities defined between the segments of the cartridge. The cartridge is removed from the outer die and the segments are then separated to release the wheel.