Two-Part Steering Gearbox Plug for Burr-Free Seal Retention
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Solution Overview
Problem
Existing power steering device casings face issues with sealing quality due to misalignment and burrs in the molding process of plugs, leading to leakage and poor axial holding of sealing members, which can result in premature seal failure and loss of sealing under low-pressure conditions.
Innovation Solution
A manufacturing method for a plug with a hub and annular groove, where the hub is split into two segments assembled with a parting line secant to the central axis, ensuring a smooth and continuous surface for the sealing member, preventing misalignment and burrs, and providing effective axial retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the plug is manufactured by injection molding with a parting line parallel to the central axis, then the manufacturing process is simple and easy to unmold, but misalignment and burrs occur at the parting line causing surface irregularities that compromise sealing quality
Solution Approach 1:
The plug is divided into two separate halves (first plug half and second plug half) that are manufactured separately and then assembled together. This segmentation allows each half to be molded with a parting line that does not create surface irregularities on the sealing surfaces, while still maintaining manufacturing simplicity and ease of unmolding.
Solution Approach 2:
The parting line is repositioned from a radial orientation (parallel to central axis) to an axial orientation (perpendicular to central axis). This dimensional change moves the parting line away from the sealing surfaces, eliminating the creation of surface irregularities while preserving manufacturing advantages.
2Manufacturing precision
If material removal is performed to correct misalignment or burrs at the parting line, then sealing surface quality improves, but the pitch diameter of the hub is reduced compromising the mounting and clamping of the sealing member
Solution Approach 1:
The sealing surfaces are designed to be formed directly during the molding process without requiring subsequent material removal. The parting line configuration and molding technique are predetermined to produce smooth sealing surfaces, preventing the need for corrective machining that would compromise hub strength.
3Ease of manufacture
If the sealing member is simply pressed against a shoulder of the plug, then the manufacturing process is simple, but the axial holding of the sealing member is insufficient allowing it to slide or be sucked inside the casing cavity
Solution Approach 1:
The groove configuration is optimized locally at the sealing member location to provide enhanced axial retention. The groove includes a bottom wall and edge walls that create a pocket structure, providing strong axial holding force specifically where needed for the sealing member while maintaining overall manufacturing simplicity.
Data Source
AI summary
A plug including a hub which extends along a central axis and is defined radially by a side wall wherein an annular groove is formed, which receives a sealing member, the groove provided between a bottom wall and first annular edge wall, and a second annular edge wall, which axially define the groove, the hub being formed by the combination of a first hub section on which the first edge wall is formed, and a second hub section on which the second edge wall is formed, the first hub section and the second hub section being assembled so that they meet at a gasket face which is secant to the central axis and the bottom wall of the groove, so the line of the intersection of the gasket face with the bottom wall is contained axially between the first and second edge wall over the entire perimeter of the groove.