Cementless Molten Metal Pump Post Replacement
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Solution Overview
Problem
The existing pumps for molten metal face significant challenges due to the oxidizing effects, which cause components like shafts and pump posts to wear out, necessitating the use of cement for securing posts to the base, leading to a labor-intensive and time-consuming process for replacement, as cement hardens and damages the base during removal.
Innovation Solution
A cementless pump design featuring refractory sleeves and post fastening members that eliminate the need for cement, allowing for easy replacement of posts without damaging the base, using refractory sleeves that are softer than graphite and can be easily removed, along with refractory gaskets to prevent molten metal intrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cement is used to secure posts to the base, then the posts are firmly held in place, but the cement becomes harder than the base and requires chiseling to remove, damaging the base and extending repair time to two days
Solution Approach 1:
The patent uses sacrificial cement posts that are intentionally designed to be replaceable and disposable. The cement is applied only to the portion of the post that needs to be replaced, allowing quick removal without damaging the base. This resolves the contradiction by making the cement temporary and easy to remove, rather than permanent and difficult to remove.
Solution Approach 2:
The cement is applied locally only to the portion of the post that needs securing, rather than the entire post. This localized application allows for easy removal of only the affected portion without damaging the base, resolving the contradiction between strong holding and easy repair.
2Reliability
If cement is used to cap bolts to prevent molten metal intrusion, then metal intrusion is prevented, but the cement must be removed with a chisel after pump removal, distorting hole shapes and requiring re-drilling
Solution Approach 1:
The cement is used temporarily only during assembly to prevent metal intrusion, then easily removed after the pump is removed from service. This temporary use resolves the contradiction by providing protection when needed without creating long-term removal problems.
Solution Approach 2:
The cement is extracted or removed easily from the base after serving its protective function, using a simple chisel method that does not damage the base. This extraction process resolves the contradiction by removing the cement quickly without requiring complex removal procedures.
3Strength
If cement is used to secure posts, then posts are firmly attached, but the process of removing cement, drilling new holes, aligning posts and curing cement takes two days
Solution Approach 1:
The cement is designed to be temporary and easily removable, eliminating the need for complex removal and reinstallation processes. This resolves the contradiction by making the attachment method quick and reversible, significantly improving productivity.
Solution Approach 2:
The cement is applied in advance during assembly to secure posts, then easily removed after the pump is removed from service. This preliminary application followed by easy removal resolves the contradiction by providing strong attachment during operation without creating time-consuming removal procedures.
Data Source
AI summary
In a cementless pump for pumping molten metal, support structure is suspended above the molten metal. A motor is supported by the support structure. A shaft is fastened to the motor. An impeller is mounted to a lower end of the shaft. A refractory base is supported in the molten metal and includes at least one impeller chamber in which the impeller is rotated and at least one discharge passageway. The base includes through holes. Support posts are each fastened to the support structure and to the base. Refractory sleeves are each disposed in one of the through holes. Post fastening members fasten the lower ends of the posts to the base without cement. A portion of each of the post fastening members is located inside the refractory sleeve. Also featured is a method of replacing posts in a cementless pump for pumping molten metal.