Insert-Molded Resin Gear Flow Path for Fiber Alignment
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Solution Overview
Problem
Existing resin molded gear technologies face challenges in aligning fiber orientations along tooth surfaces, forming weld lines outside contact friction areas, and controlling resin flow paths to reduce manufacturing and material costs, particularly with fiber-reinforced resins.
Innovation Solution
A resin molded gear design featuring a gear-shaped insert with an annular first flow path and outlets on its outer edge, allowing molten resin to flow directly to tooth bottoms, aligning fiber orientations from tooth bottoms to tips and simplifying flow paths, while using a metallic insert to suppress resin shrinkage and reduce manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fiber-reinforced resin is used to ensure gear strength and friction wear characteristics, then the durability and friction resistance are improved, but the material cost increases significantly
Solution Approach 1:
The patent applies local quality by using fiber-reinforced resin only in critical areas where strength and wear resistance are needed (tooth surfaces and dedendum regions), while using unreinforced resin in less critical areas. This selective reinforcement reduces overall material cost while maintaining gear durability in high-stress zones.
2Reliability
If guiding paths for molten resin are provided in the insert to prevent weld lines on tooth surfaces, then the gear durability is improved, but the manufacturing cost of the insert increases
Solution Approach 1:
The patent segments the resin flow control into multiple simple outlets distributed around the insert perimeter, rather than requiring complex internal guiding paths. Each outlet independently feeds resin to specific tooth regions, achieving weld line prevention through simplified insert geometry that is easier and cheaper to manufacture.
3Manufacturing precision
If flow channels are formed to guide molten resin through the insert member to tooth portions, then the fiber orientation is improved, but the amount of molten resin used increases
Solution Approach 1:
The patent extracts the resin flow guidance function from the insert interior and relocates it to the insert perimeter through multiple outlets. This allows molten resin to be delivered directly to tooth regions without requiring the resin to travel through long internal channels, reducing the total volume of resin needed while maintaining effective fiber orientation in the tooth portions.
4Reliability
If the insert surface is pretreated and heated to suppress resin retention and cracking, then the gear reliability is improved, but the processing time increases
Solution Approach 1:
The patent applies preliminary action by providing multiple outlets positioned to deliver molten resin directly to tooth bottom portions and critical regions during the injection process itself. This eliminates the need for post-molding heating treatments to suppress resin retention and cracking, as the resin is properly positioned and distributed during molding, reducing total processing time while maintaining gear reliability.
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
The design ensures uniform fiber orientation and weld lines along tooth tips, reduces resin usage and manufacturing costs, and enhances gear precision with simplified flow paths and metal insert support.
Implementation Method 1
the flow paths of molten resin formed in the insert are simplified
Implementation Method 2
because the metal insert can suppress resin shrinkage
Data Source
AI summary
To align the orientation of resin fibers of a resin molded gear produced by insert molding and suppress the manufacturing cost of the resin molded gear.The present invention includes a resin molded gear 1 and a gear-shaped insert 2. The insert 2 includes a web portion 21 and tooth portions 22. Each tooth portion 22 has tooth bottom portions 22a that oppose the tooth bottoms 12a of the resin molded gear 1 and a tooth tip portion 22c that opposes a tooth tip 12c of the resin molded gear 1. An annular first flow path 23 is formed in the surface of the web portion 21, and outlets 23a are provided on the outer edge of the first flow path 23 to allow molten resin 31 to flow out to the tooth bottom portions 22a.