Titanium Turbine Wheel Pickling via Partial Immersion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Titanium alloy turbine wheels with annular cavities formed during heat treatment develop a difficult-to-access oxygen-rich 'alpha-case' layer on both the inside and outside surfaces, which leads to premature cracking due to incomplete pickling, as existing methods only address the outside layer.
Innovation Solution
A method involving partial immersion and rotation of the part in a pickling composition, with continuous pumping from the inside to ensure uniform penetration and recycling of the composition, using a system of flexible suction ducts and calibrated flow constrictions to maintain effectiveness across varying cavity volumes, followed by neutralization in a separate bath.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the part is totally immersed in the pickling composition, then the pickling composition can reach all surfaces, but air bubbles remain trapped inside the part preventing effective pickling
Solution Approach 1:
The patent applies partial immersion by submerging only a portion of the hollow part in the pickling composition while keeping the rest exposed. This partial action allows the composition to penetrate inside without trapping air bubbles, resolving the contradiction between achieving uniform pickling depth and ensuring effective composition penetration.
Solution Approach 2:
The patent introduces continuous rotation of the hollow part during pickling. This dynamic movement prevents air bubbles from becoming trapped and ensures uniform distribution of the pickling composition across all surfaces, including internal surfaces, thereby achieving both uniform pickling depth and effective penetration.
2Device complexity
If the part is stationary during pickling, then the setup is simple, but the pickling composition does not penetrate uniformly inside the part
Solution Approach 1:
The patent introduces continuous rotation of the hollow part during pickling. This dynamic movement, achieved through a rotation drive mechanism, ensures uniform distribution of the pickling composition across all surfaces including internal surfaces, thereby achieving uniform pickling depth while maintaining acceptable setup complexity.
Solution Approach 2:
The patent employs a pumping system that circulates the pickling composition through the hollow part. This hydraulic action ensures the composition reaches all internal surfaces uniformly, complementing the rotation mechanism to achieve consistent pickling depth throughout the part.
3Device complexity
If the pickling composition is not renewed in the cavities, then the system is simple, but the composition becomes exhausted and loses effectiveness
Solution Approach 1:
The patent implements continuous circulation and renewal of the pickling composition through the cavities using a pumping system. This continuous action ensures the composition maintains its effectiveness by constantly being refreshed, preventing exhaustion while managing the system with acceptable complexity through automated circulation.
Solution Approach 2:
The patent incorporates a system that monitors and regulates the flow of pickling composition through the cavities. This feedback mechanism ensures proper renewal and maintains composition effectiveness, managing the complexity through automated control that adjusts flow based on system needs.
4Reliability
If pickling is performed only on the outside, then the process is safe and simple, but the contaminated layer remains inside causing cracks
Solution Approach 1:
The patent uses continuous rotation of the hollow part during pickling to safely and effectively treat both external and internal surfaces. The rotation ensures the pickling composition uniformly contacts all surfaces including internal cavities, eliminating the alpha-case layer throughout while maintaining process safety through controlled, uniform exposure.
Solution Approach 2:
The patent employs a pumping and circulation system that forces the pickling composition through the internal cavities of the hollow part. This hydraulic action ensures the composition reaches and treats the internal surfaces where the alpha-case layer forms, eliminating the harmful layer throughout the entire part while maintaining process control and safety.
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 simultaneous and uniform dissolution of the alpha-case layer on both the inside and outside surfaces, preventing premature cracking by ensuring consistent chemical treatment and maintaining the effectiveness of the pickling composition throughout the process.
Implementation Method 1
chemically dissolving the oxygen-rich contaminated layer that forms on such a part when made of titanium alloy during heat treatment thereof
Implementation Method 2
rotating said part about its axis of rotation in a horizontal orientation, in partially immersing said part in a vessel filled with pickling composition so that the composition penetrates into the inside of said part
Implementation Method 3
continuously pumping the pickling composition from the inside of said part while maintaining the level of pickling substance substantially constant relative to said part
Data Source
AI summary
Pickling the inside and the outside of a hollow part that is in the form of a body of revolution, such as, in particular, a turbine wheel made of titanium alloy. The part is mounted with its axis of revolution in a horizontal orientation and it is partially immersed in a vessel filled with pickling composition while being caused to rotate about its axis of revolution.