Flexible Gear Material Composition for Stronger Robot Strain Wave Gearing
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Solution Overview
Problem
Strain wave gearing in robots is prone to early failure due to insufficient mechanical strength of flexible gears, which breaks easily under mechanical stress.
Innovation Solution
A flexible gear formed from a ferrous material containing Group 4 and Group 5 elements in specific concentrations, combined with heat treatment to suppress crystal grain growth and improve mechanical strength, and a manufacturing method involving upset forging and deep drawing to create a tubular structure with optimized metal flows for enhanced strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional ferrous material is used for the flexible gear, then the manufacturing process is simple, but the mechanical strength is insufficient and the flexible gear breaks early
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the ferrous material, specifically limiting Group 4 elements to 0.01-0.1 mass% and Group 5 elements to 0.01-0.05 mass%. This compositional parameter optimization suppresses excessive crystal grain growth during heat treatment while maintaining material workability, thereby improving mechanical strength without making the material overly complex
Solution Approach 2:
The patent creates a composite material system by combining ferrous base material with specific small quantities of Group 4 (Ti, Zr, Hf) and Group 5 (V, Nb, Ta) alloying elements. This composite approach leverages the grain-refining and strengthening effects of these elements to enhance mechanical strength while maintaining the ductility needed for flexible gear operation
2Strength
If heat treatment is performed to improve strength, then mechanical strength increases, but crystal grain growth occurs reducing effectiveness
Solution Approach 1:
The patent applies preliminary action by pre-alloying the ferrous material with specific quantities of Group 4 and Group 5 elements before heat treatment. These elements act as grain refiners that suppress crystal grain growth during the subsequent heat treatment process, allowing the material to achieve high strength without excessive grain coarsening that would reduce effectiveness
3Reliability
If the flexible gear is made with higher strength material, then durability improves, but workability and manufacturing difficulty increase
Solution Approach 1:
The patent optimizes the material parameters by limiting Group 4 elements to 0.01-0.1 mass% and Group 5 elements to 0.01-0.05 mass%, which provides sufficient grain refinement and strengthening effects while maintaining the material's ductility and formability. This parameter optimization ensures the material remains workable for deep drawing and shaping operations while achieving the durability needed for reliable flexible gear operation
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 approach significantly enhances the mechanical strength and durability of flexible gears, reducing damage and improving the overall performance of the gearing system by maintaining strength consistency across the circumferential direction and enhancing toughness and tensile strength.
Implementation Method 1
even when heat treatment is performed in the manufacturing process of the flexible gear, the growth of the crystal grain of the ferrous material forming the flexible gear may be suppressed and the grain size may be made smaller
Data Source
AI summary
A robot includes a flexible gear formed by a ferrous material containing at least one or more kinds of elements of Group 4 elements and Group 5 elements in a range from 0.01 percent by mass to 0.5 percent by mass. The ferrous material contains at least one of nickel-chromium-molybdenum steel, maraging steel, and precipitation-hardened stainless steel.