Transmission Case Rib and Recess Layout for Casting Cavities
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Solution Overview
Problem
Existing transmission cases face issues with cavity formation during casting due to imbalances in molten metal flow, leading to reduced yield and structural integrity, particularly where ribs are not provided, such as around thick-walled sections and through-holes.
Innovation Solution
The transmission case design incorporates an annular section with radially extending first ribs and a second rib crossing the vertical line, featuring recesses in the bulging section with sloped bottom surfaces to guide molten metal flow uniformly, ensuring balanced distribution and reducing gas entrapment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ribs are provided in the wall section during casting, then molten metal flow is improved and cavity formation is reduced, but ribs cannot be provided in areas with through-holes and thick-walled sections
Solution Approach 1:
The invention introduces recesses with specific geometric characteristics (sloped bottom surfaces) in specific locations (wall sections with through-holes and thick-walled sections) to create localized flow guidance. This allows the casting structure to have different properties in different regions: ribs in areas where they can be provided, and recesses in areas where ribs cannot be provided, thereby resolving the contradiction between improving molten metal flow and maintaining structural requirements.
2Manufacturing precision
If recesses are added to guide molten metal flow, then manufacturing precision is improved by reducing cavities, but device complexity increases
Solution Approach 1:
The recesses are designed into the mold structure in advance, with predetermined shapes and positions, to guide the molten metal flow before casting occurs. The sloped bottom surfaces of the recesses pre-establish flow paths that direct molten metal away from critical areas, preventing cavity formation proactively rather than requiring post-processing or complex real-time control mechanisms.
3Stability of the object's composition
If the bottom surface of the recess is made sloped, then molten metal flow uniformity is improved, but manufacturing complexity increases
Solution Approach 1:
The recesses employ asymmetric bottom surfaces with slopes oriented at specific angles (e.g., 30-60 degrees) relative to the horizontal plane. This asymmetric geometry creates directional flow guidance that promotes uniform molten metal distribution, with the sloped surfaces directing flow away from the axial center toward peripheral regions, thereby achieving flow uniformity through deliberate geometric asymmetry.
Data Source
AI summary
A case for housing a driving force transmission device includes a wall section defining a through-hole through which a shaft is configured to pass. The wall section, as viewed from an axial direction, includes an annular section surrounding the through-hole, first ribs that extend radially outward from the annular section, a second rib that crosses a vertical line that passes through an axial center of the shaft from one side to the other side, and a recess that opens at a bottom end surface of the wall section, and recessed in a direction along the vertical line. A bottom surface of the recess has a shape such that a side farther from the vertical line is located closer to a bottom end surface side. A region of the wall section in which the recess is provided is connected to one end of the second rib.