Plastic-Lined Rotary Seal Mold Geometry for Elastomer Containment
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Solution Overview
Problem
The manufacturing of hydrodynamic rotary seals faces challenges such as elastomer migration during molding, leading to rejection of parts and increased costs, and subsequent machining issues that result in a significant percentage of misshapen or unusable seals due to difficulty in fixturing.
Innovation Solution
A specially configured mold and machining process are used to produce a rotary seal with a plastic liner and elastomer, where the mold configuration and seal shape prevent elastomer migration during molding and allow for precise machining to a compact, functional form, ensuring the elastomer does not migrate onto critical surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional mold is used to manufacture rotary seals, then the molding process is simple, but elastomer migration occurs during molding causing part rejection and increased costs
Solution Approach 1:
The mold is designed with specific features (counterbores, relief grooves, restricted cavities) before the molding process begins. These pre-configured features prevent elastomer migration during curing by creating controlled pathways and pressure relief zones, eliminating the need for post-molding corrections and reducing part rejection.
Solution Approach 2:
The patent introduces intermediary structural elements within the mold cavity, such as relief grooves and counterbores, that act as mediators to manage elastomer flow and pressure during curing. These features intercept migrating elastomer and redirect it into controlled zones, preventing contamination of critical sealing surfaces.
2Manufacturing precision
If the seal is machined to compact form after molding, then the seal achieves precise dimensions and functional form, but a significant percentage of seals are misshapen or unusable due to difficulty in fixturing
Solution Approach 1:
The mold is designed to pre-form the seal with accurate dimensions and proper geometry during the molding process itself. Features such as precision cavity shapes, counterbores, and relief grooves are built into the mold, allowing the seal to be produced close to its final form without requiring extensive post-molding machining that would otherwise cause misshaping and low yield.
3Ease of manufacture
If the elastomer is allowed to migrate during molding, then the molding process is straightforward, but the elastomer migrates onto critical surfaces causing seal failure
Solution Approach 1:
Relief grooves and counterbores are introduced as intermediary features that intercept elastomer migration pathways. These features create controlled zones where elastomer can be contained or redirected, preventing it from reaching critical sealing surfaces while maintaining the simplicity of the molding process.
Solution Approach 2:
The patent extracts or removes the harmful effect of elastomer migration by providing dedicated zones (relief grooves, counterbores) where migrating elastomer can be isolated. This separates the elastomer from critical surfaces, allowing the molding process to remain simple while preventing seal failure.
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 effectively prevents elastomer migration and subsequent machining issues, resulting in a more reliable and cost-effective production of rotary seals with improved sealing performance and prolonged life in high differential pressure conditions.
Implementation Method 1
the geometry of the seal interacts with the first fluid during relative rotation to wedge a lubricating film into the dynamic sealing interface between the seal and a relatively rotatable surface
Implementation Method 2
A wave form incorporating an elongated dimple provides the gradual convergence, efficient impingement angle, and gradual interfacial contact pressure rise that are conducive to efficient hydrodynamic wedging of lubricant into the dynamic interface
Implementation Method 3
the interfacial contact pressure between the seal and the mating surface of a relatively rotatable surface (6) is controlled largely by the modulus of elasticity of the elastomeric energizer (32)
Implementation Method 4
The molding pressure doesn't always hold that portion of the plastic liner (30) tightly to the cavity of the mold during the molding process
Data Source
AI summary
A seal configuration, mold and manufacturing process that inhibits undesirable elastomer migration onto critical radially inwardly facing portions of a plastic-lined dynamic sealing lip, for improved high-pressure seal operation.