Split Core Mold Assembly for Accurate Hollow Shaft Casting
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Solution Overview
Problem
Conventional methods for producing long-length shafts with cast holes face challenges in achieving accurate peripheral wall thickness due to low processing accuracy and potential deviations during the grinding process, making it difficult to center the shaft and maintain consistent wall thickness.
Innovation Solution
A mold assembly comprising a first split core mold and a second split core mold, fixed relative to each other, is used to form the peripheral wall of the cast hole, with a sand hardening type mold providing higher dimensional accuracy, and a lathe turning process ensures accurate centering and thickness control, reducing deviations in the peripheral wall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shaft is formed by casting with a cast hole, then the hollow structure is provided in the shaft, but the processing accuracy is low and the peripheral wall thickness has unignorable deviations
Solution Approach 1:
The mold assembly is segmented into multiple components: a main mold and a core mold that is divided into first and second split core molds. Each segment forms a specific portion of the shaft or cast hole, allowing precise control of peripheral wall thickness while maintaining the overall casting process. The first split core mold forms the casting surface of the cast hole, while the second split core mold forms the peripheral wall portion.
Solution Approach 2:
The core mold containing the first and second split core molds is fitted into the main mold, creating a nested structure. This nesting arrangement allows the core mold to be precisely positioned within the main mold, ensuring accurate formation of the cast hole and peripheral wall with controlled thickness, while the entire assembly remains integrated for the casting process.
2Manufacturing precision
If a grinding step is added after casting to improve processing accuracy, then the shaft accuracy is improved, but the axial center deviates and centering becomes difficult
Solution Approach 1:
The mold assembly is designed to preliminarily form the shaft with the cast hole and peripheral wall at the correct dimensions and positions during the casting process itself. The first and second split core molds are positioned to precisely define the cast hole geometry and peripheral wall thickness before casting, eliminating the need for subsequent grinding operations that would cause axial center deviation.
3Weight of moving object
If the peripheral wall thickness is reduced to meet design requirements, then the shaft weight is reduced, but the wall thickness deviations become significant
Solution Approach 1:
The core mold is specifically designed with local quality features to precisely control the peripheral wall thickness. The first and second split core molds have specially configured surfaces and positioning features that ensure uniform and accurate peripheral wall thickness throughout the cast hole, even when the thickness is reduced to meet weight requirements. This localized precision control prevents significant deviations in the thinned peripheral wall.
Data Source
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AI summary
A mold assembly having a first split core mold configured to form a casting surface of a casting hole, a second split core mold configured to form the periphery of the casting hole, and a main mold is prepared. The first split core mold is fitted into the second split core mold. Then, the second split core mold is fitted into the main mold. A shaft (10) is cast by pouring molten metal into the mold assembly. Aperipheral wall portion (12A) of the shaft (10) is held by a main spindle stock (30A) (holding device) of a lathe (30). A predetermined portion (10A) of the shaft (10) is turned by setting an outer surface of the peripheral wall portion (12A) as a reference surface. Then, the predetermined portion (10A) is held by the main spindle stock (30A) of the lathe (30) so that a part of the shaft (10) other than the predetermined portion (10A) is turned by setting an outer surface of the predetermined portion (10A) as a reference surface.