Strain Wave Gear Raceways With Plastic Rollers and Solid Lubrication
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Solution Overview
Problem
Existing strain wave gearings with plastic raceway parts suffer from damage such as dents, wear, and fatigue peeling, even under low loads, due to insufficient stress reduction and inadequate lubrication.
Innovation Solution
The use of super engineering plastics for raceway parts, combined with cylindrical rollers arranged at equal angular intervals, increased ellipticity of the externally toothed gear, low pressure angles, and a strong solid lubricant film made of ionic crystalline layered compounds, along with grease lubrication, to reduce stress and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If raceway parts are made of plastic components to reduce weight, then weight is reduced, but damage such as dents, wear, and fatigue peeling occurs on the raceway parts even under low load
Solution Approach 1:
The patent uses super engineering plastics (a class of high-performance plastic materials) for the raceway parts instead of conventional plastics or metals. These composite plastic materials provide both weight reduction and sufficient mechanical strength to prevent damage under operational loads, resolving the contradiction between weight reduction and damage resistance.
Solution Approach 2:
The patent changes the material parameters by selecting super engineering plastics with specific mechanical properties (higher strength, stiffness, and fatigue resistance) compared to conventional plastics. This parameter change enables the raceway parts to maintain structural integrity and resist damage while still achieving weight reduction compared to metal components.
2Stress or pressure
If cylindrical rollers are used as rolling elements, then stress is reduced, but wear and melting occur in the raceway parts
Solution Approach 1:
The patent introduces a lubricant as an intermediary substance between the cylindrical rollers and the raceway parts. This lubricant film prevents direct contact and friction between the rolling elements and raceway surfaces, thereby preventing wear and melting while allowing the cylindrical rollers to effectively reduce stress through rolling motion.
Solution Approach 2:
The patent changes the tribological parameters by introducing lubrication, which modifies the friction and wear characteristics of the contact surfaces. This parameter change prevents wear and melting of the raceway parts while maintaining the stress-reducing benefit of cylindrical rollers.
3Object-affected harmful factors
If lubricants are used to minimize wear, then wear is reduced, but fatigue peeling of the raceway parts still occurs
Solution Approach 1:
The patent uses super engineering plastics with enhanced fatigue resistance properties. These advanced plastic materials have improved structural integrity and fatigue life, enabling them to resist fatigue peeling even when lubrication is present. The material composition and structure are optimized to prevent fatigue failure while maintaining low wear characteristics.
Solution Approach 2:
The patent changes the material parameters of the raceway parts by using super engineering plastics with specific fatigue strength, toughness, and resistance to cyclic loading. These parameter changes enable the raceway parts to withstand repeated stress cycles without fatigue peeling, even in the presence of lubrication that reduces but does not eliminate wear.
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 configuration effectively prevents damage to the raceway parts, allows for weight reduction, and enables operation within a practical load torque range while maintaining gear functionality.
Implementation Method 1
a strong solid lubricant film (transfer film) made of an ionic crystalline layered compound is formed on raceway surfaces
Data Source
AI summary
A strain wave gearing includes a wave generator that creates a state in which a flexible externally toothed gear is flexed into a non-circular shape and partially meshes with a rigid internally toothed gear, and that includes a wave plug having a non-circular outer peripheral surface and a wave bearing attached to the non-circular outer peripheral surface of the wave plug. The wave bearing includes an outer ring having an inner peripheral surface and an outer-ring-side raceway surface formed on the inner peripheral surface, an inner ring having an outer peripheral surface and an inner-ring-side raceway surface formed on the outer peripheral surface, and a plurality of rolling elements rotatably inserted between the outer-ring-side raceway surface and the inner-ring-side raceway surface.