Plastic Harmonic Reducer Structure for Lower-Cost Precision Motion
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Solution Overview
Problem
Current harmonic reducers have high manufacturing costs, limiting their application in certain industrial sectors, and there is a need for a more cost-effective and high-quality solution that can be integrated into various industrial systems, particularly in robotics and motion control.
Innovation Solution
The development of a new harmonic reducer with fundamental components made from injection-molded plastic materials, featuring a double circular spline configuration and a flexible spline with an externally toothed belt design, which reduces size and weight while maintaining high transmission ratios and precision, utilizing plastic materials with additives for enhanced tribological properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional metal materials are used for harmonic reducer components, then strength and durability are improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the material parameter from traditional metal to plastic, specifically using polyamide 12 produced by selective laser sintering. This material substitution maintains sufficient mechanical strength while dramatically reducing manufacturing cost and complexity, directly resolving the contradiction between strength and manufacturing cost
Solution Approach 2:
The patent replaces traditional mechanical manufacturing processes (metal cutting, machining) with additive manufacturing technology (selective laser sintering). This substitution enables complex geometries to be produced without expensive tooling and machining operations, reducing manufacturing cost while maintaining component strength
2Stability of the object's composition
If the bell height is increased to improve flexibility, then elastic deformation capability is improved, but the axial dimension increases
Solution Approach 1:
The patent uses polyamide 12, a plastic material with inherent viscoelastic properties, to replace traditional metal bell structures. This composite material approach provides the necessary flexibility and elastic deformation capability without requiring increased bell height, thus maintaining compact axial dimensions
Solution Approach 2:
The patent employs a thin-walled plastic bell structure made through selective laser sintering. The additive manufacturing process creates optimized wall thickness distributions that provide sufficient flexibility for elastic deformation while keeping the overall axial dimension compact, resolving the contradiction between flexibility and size
3Adaptability or versatility
If complex geometries are designed to improve functionality, then performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces traditional subtractive manufacturing (machining, molding) with additive manufacturing (selective laser sintering). This enables the production of complex internal geometries, hollow structures, and optimized load paths that would be difficult or expensive to manufacture using conventional methods, improving functional performance without increasing manufacturing complexity
Solution Approach 2:
The patent integrates multiple components into a single monolithic plastic part through additive manufacturing. The bell, splines, and other elements are created as one integrated structure, eliminating the need for complex assembly operations and reducing manufacturing complexity while maintaining or improving functional performance
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 approach results in a compact, reliable, and cost-effective harmonic reducer with reduced maintenance and assembly costs, capable of precise motion transmission and integration into complex systems, offering improved performance and expanded industrial applications.
Implementation Method 1
the wave generator WG, rotating coaxially to the first rigid toothed element CS, cooperates with a thin deformable annular wall of the second toothed element or flex spline FS, so as to deform the respective external toothing from a circular configuration to a slightly elliptical configuration
Data Source
AI summary
Harmonic reducer (10) including: three components or parts, housed in an outer shell (10′), consisting respectively of: —a first part or circular spline (20, CS, 20a, 20b), rigid, internally toothed (20a′, 20b′); —a second part or flex spline (30, FS), flexible, in the shape of an externally toothed belt (30′); and—a third party or wave generator (40, WG); and an electric motor (50), also housed in the outer shell (10′), able to control a rotation of the third part or wave generator (40) around an axis (X-X) of the harmonic reducer (10); wherein the circular spline (20) and the flex spline (30) and a support body (40′) of the wave generator (40) are totally made by injection moulding of a plastic material (MP); wherein the first part or circular spline (20, CS), rigid, is a double circular spline and consists of a first fixed circular spline (20a) and a second mobile or movable circular spline (20b), integral with a user (U) of the harmonic reducer (10), each having a respective internal toothing (20a′, 20b′); wherein the internal toothing (20a′) of the first fixed circular spline (20a) has a number of teeth equal to that of the external toothing of the flex spline (30) and the internal toothing (20b′) of the second movable circular spline (20b) has two teeth more than those of the internal toothing of the first fixed circular spline (20a); wherein one half of the external toothing of the flex spline (30) is meshed with the internal toothing of the first fixed circular spline (20a) and another half with the internal toothing of the second movable circular spline (20b) of the circular spline (20); and wherein the wave generator (40) has two groups (40a, 40b) of rotating bearings, arranged in diametrically opposite areas of the wave generator (40), which, when the latter rotates around the axis (X-X) of the harmonic reducer (10), cooperate with an internal surface (30″) of the flex spline (30), so as to elastically deform it and press the two halves of its external toothing (30′) respectively against the internal toothing (20a′, 20b′) of the first and second circular spline (20a, 20b), fixed and mobile, of the circular spline (20). The harmonic reducer (10), the essential parts of which (20, 30, 40) are made by injection moulding of a plastic material, has a compact structure and can be produced at a competitive industrial cost.