Plastic-Lined Rotary Seal Molding to Prevent Elastomer Migration
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Solution Overview
Problem
The existing manufacturing methods for hydrodynamic rotary seals face challenges such as elastomer migration during molding, leading to rejected parts and increased costs, and difficulties in fixturing the seals for machining, resulting in misshapen or damaged seals.
Innovation Solution
A method for producing rotary seals using a specially configured mold that inhibits elastomer migration by ensuring the plastic liner is securely held during molding, and subsequent machining operations to achieve the final seal configuration, which prevents elastomer migration onto critical surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the plastic liner is made short and stiff to control extrusion resistance, then extrusion resistance is improved, but elastomer migration occurs during molding
Solution Approach 1:
The patent applies preliminary action by extending the plastic liner beyond the cavity groove end before molding occurs. This pre-positioned extension ensures that the liner is long enough to prevent elastomer migration during the molding process, while the liner is subsequently trimmed to the final length after molding is complete. This resolves the contradiction by preparing the liner in advance to prevent migration without compromising the final extrusion resistance properties.
2Manufacturing precision
If the seal is molded to longer length to prevent elastomer migration, then elastomer migration is prevented, but machining difficulty increases
Solution Approach 1:
The patent applies segmentation by dividing the manufacturing process into distinct stages: first molding the seal with an extended plastic liner to prevent elastomer migration, then separately trimming the liner to the final length. This segmentation allows the molding operation to focus on preventing migration while the subsequent trimming operation handles the precision length adjustment, thereby resolving the contradiction between preventing migration and maintaining machining ease.
3Manufacturing precision
If the plastic liner is extended beyond cavity groove end, then elastomer migration is prevented, but material waste increases
Solution Approach 1:
The patent applies the principle of discarding and recovering by intentionally extending the plastic liner beyond the final required length during molding to prevent elastomer migration, then trimming off the excess portion after molding. While this does result in some material waste from the trimmed portion, it prevents the greater waste of rejected parts due to elastomer migration, and the trimming process allows for precise control of the final dimensions.
Data Source
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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.