PAS Resin Worm Gear for Heat- and Humidity-Stable Accuracy
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Solution Overview
Problem
Resin gears face challenges in achieving durability and dimensional accuracy under high-temperature or high-humidity conditions, as existing techniques fail to provide adequate thermal stability, mechanical strength, and dimensional stability.
Innovation Solution
The use of a polyarylene sulfide resin (PAS resin) composition with a specific melt viscosity range (50 to 4,000 Pa·s) and the inclusion of cellulose nanofibers and a silane coupling agent to enhance mechanical properties and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional resin materials (POM or PA) are used for gear sliding portions, then weight reduction and maintenance savings are achieved, but thermal stability and dimensional stability under high-temperature or high-humidity conditions deteriorate
Solution Approach 1:
The patent uses a composite material consisting of PPS resin as the base material and cellulose nanofibers as the reinforcing filler. This composite structure combines the lightweight properties of resin with the dimensional stability provided by the nanofiber reinforcement, resolving the contradiction between weight reduction and dimensional stability under high-temperature or high-humidity conditions
2Strength
If cellulose nanofibers are added to thermoplastic resin, then mechanical strength is improved, but the nanofibers aggregate and dispersion becomes poor
Solution Approach 1:
The patent controls the degree of crystallinity of the PPS resin within a specific range (30-70%) to optimize the dispersion of cellulose nanofibers. By adjusting this critical parameter, the resin matrix provides appropriate interaction with the nanofibers, preventing aggregation while maintaining mechanical strength enhancement
3Strength
If reinforcing materials are added to resin gears, then mechanical properties are improved, but adhesion between reinforcing material and resin deteriorates
Solution Approach 1:
The patent introduces a silane coupling agent as an intermediary substance between the cellulose nanofibers and the PPS resin matrix. This coupling agent chemically bonds to both the nanofiber surface and the resin, creating strong interfacial adhesion and preventing the poor bonding that typically occurs between reinforcing materials and resin matrices
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 PAS resin composition results in a gear with a low dimensional change rate due to heat and water absorption, offering excellent durability and dimensional accuracy under high-temperature and high-humidity conditions.
Implementation Method 1
the adhesion between the reinforcing material and the thermoplastic resin is poor. As a result, a gear having durability and dimensional accuracy sufficient for practical use under high-temperature or high-humidity conditions is not provided
Data Source
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AI summary
The present disclosure aims to provide a gear, a worm gear, and a robot, which have a low dimensional change rate due to thermal expansion and water absorption and have excellent durability and dimensional accuracy under high-temperature and high-humidity conditions even when the gear is composed of a resin. The present disclosure provides a gear having a first toothed portion provided on the outer circumference thereof. The gear contains a polyarylene sulfide resin as a constituent component. The polyarylene sulfide resin has a melt viscosity (V6) of 50 to 4,000 Pa-s.