PPS Resin Worm Gear for Dimensional Stability in Heat and Humidity
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Solution Overview
Problem
Resin gears lack durability and dimensional accuracy under high-temperature and high-humidity conditions due to aggregation of cellulose nanofibers and poor adhesion between reinforcing materials and thermoplastic resins, as seen in existing technologies.
Innovation Solution
A gear system using a polyarylene sulfide resin with a melt viscosity of 50 to 4,000 Pa·s, combined with cellulose nanofibers and a silane coupling agent, to enhance durability and dimensional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cellulose nanofibers are used as reinforcing material in thermoplastic resin gears, then mechanical strength is improved, but the nanofibers aggregate and disperse poorly resulting in reduced durability
Solution Approach 1:
The patent introduces a silane coupling agent as an intermediary substance between the cellulose nanofibers and thermoplastic resin matrix. This coupling agent improves the interfacial adhesion and dispersion of nanofibers in the resin, preventing aggregation while maintaining mechanical strength enhancement. The silane coupling agent acts as a bridge that compatibilizes the hydrophilic nanofibers with the hydrophobic thermoplastic resin.
Solution Approach 2:
The patent optimizes the concentration of cellulose nanofibers and silane coupling agent to achieve optimal dispersion and adhesion. By controlling the dosage parameters and processing conditions, the patent balances the reinforcing effect with the dispersion quality, preventing fiber aggregation while maximizing mechanical strength and durability.
2Weight of moving object
If resin materials are used instead of metal for gear components, then weight is reduced and maintenance is simplified, but dimensional accuracy and durability deteriorate under high-temperature and high-humidity conditions
Solution Approach 1:
The patent creates a composite material system combining thermoplastic resin with cellulose nanofibers and silane coupling agent. This composite structure provides dimensional stability and mechanical strength comparable to metal while maintaining the weight and maintenance advantages of resin materials. The nanofiber reinforcement network restricts polymer chain movement and reduces thermal expansion.
Solution Approach 2:
The silane coupling agent serves as a mediator that enhances the interfacial bonding between nanofibers and resin matrix, creating a more rigid composite structure. This improved adhesion prevents microvoid formation and delamination under thermal and humid conditions, thereby maintaining dimensional accuracy.
3Strength
If reinforcing materials are added to thermoplastic resin for gear teeth, then mechanical properties are enhanced, but adhesion between reinforcing material and resin deteriorates due to incompatibility
Solution Approach 1:
The silane coupling agent acts as a chemical intermediary that forms strong bonds with both the cellulose nanofibers and the thermoplastic resin matrix. The coupling agent contains functional groups that interact with hydroxyl groups on nanofibers and compatible groups with the resin, creating a stable triphase interface that prevents debonding under stress.
Solution Approach 2:
The patent optimizes the chemical composition parameters of the coupling agent and the processing conditions to maximize interfacial adhesion. By adjusting the silane coupling agent concentration and curing conditions, the patent achieves optimal chemical bonding between the reinforcing nanofibers and the resin matrix.
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 gear system exhibits a low dimensional change rate, excellent durability, and improved dimensional accuracy under high-temperature and high-humidity conditions, reducing eccentricity and rattling.
Implementation Method 1
the gear further contains a silane coupling agent as the constituent component
Implementation Method 2
a dimensional change rate (%) due to a temperature change from 0° C. to 80° C. and is 0.7% or less
Data Source
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.