Oldham Nut Shrinkage Control via Fiber Reinforcement
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Solution Overview
Problem
The existing plastic Oldham nut parts made from PEEK exhibit significant shrinkage and thickness variations during injection molding, leading to shape defects and a high scrap rate due to their high melting temperature, which increases manufacturing costs and reduces mechanical strength.
Innovation Solution
A plastic Oldham nut part with uniform thickness and reinforcing ribs is designed, made from polymer materials like polyamide or polyphthalamide filled with glass or carbon fibers, reducing material thickness and the risk of air inclusions while enhancing mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the part is made from PEEK material with high melting temperature, then the mechanical properties are sufficiently close to metal, but significant shrinkage occurs during cooling leading to shape defects
Solution Approach 1:
The patent changes the material parameter from PEEK to polyamide or polyphthalamide, which have lower melting temperatures. This parameter change reduces the shrinkage during cooling while maintaining sufficient mechanical properties through glass or carbon fiber reinforcement, thereby resolving the contradiction between mechanical strength and manufacturing precision
Solution Approach 2:
The patent uses composite materials by incorporating glass fibers or carbon fibers into the polyamide or polyphthalamide matrix. This composite approach enhances the mechanical properties to compensate for the lower base material strength, while the composite structure also helps reduce anisotropic shrinkage and improve dimensional stability during molding
2Adaptability or versatility
If the thickness of plastic material varies at different points, then the part can accommodate functional requirements, but differences in shrinkage generate defects and increase scrap rate
Solution Approach 1:
The patent applies local quality by adding reinforcing ribs at specific locations where structural support is needed, rather than uniformly increasing thickness throughout. This allows the part to maintain functional adaptability while minimizing overall material thickness variations, thereby reducing shrinkage defects and improving manufacturing precision
Solution Approach 2:
The patent transitions from varying thickness in one dimension to adding structural reinforcement in another dimension through ribs. Instead of increasing material thickness to achieve structural requirements, the ribs provide structural support through geometric configuration, maintaining uniform base thickness and reducing shrinkage-related defects
3Manufacturing precision
If the thickness of plastic material is reduced, then shrinkage defects are minimized, but the mechanical strength may be compromised
Solution Approach 1:
The patent uses composite materials by incorporating glass fibers or carbon fibers into the polyamide or polyphthalamide matrix. This composite approach enhances the mechanical properties to compensate for the lower base material strength, while the composite structure also helps reduce anisotropic shrinkage and improve dimensional stability during molding
Solution Approach 2:
The patent applies local quality by adding reinforcing ribs at specific locations where structural support is needed, rather than uniformly increasing thickness throughout. This allows the part to maintain functional adaptability while minimizing overall material thickness variations, thereby reducing shrinkage defects and improving manufacturing precision
4Productivity
If the scrap rate is reduced through design modifications, then manufacturing costs decrease, but the structural integrity must be maintained
Solution Approach 1:
The patent uses composite materials by incorporating glass fibers or carbon fibers into the polyamide or polyphthalamide matrix. This composite approach enhances the mechanical properties to compensate for the lower base material strength, while the composite structure also helps reduce anisotropic shrinkage and improve dimensional stability during molding
Solution Approach 2:
The patent applies local quality by adding reinforcing ribs at specific locations where structural support is needed, rather than uniformly increasing thickness throughout. This allows the part to maintain functional adaptability while minimizing overall material thickness variations, thereby reducing shrinkage defects and improving manufacturing precision
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 reduces the scrap rate and manufacturing costs by minimizing shrinkage-related defects and improving mechanical strength, making the parts suitable for applications like power steering systems.
Implementation Method 1
the part according to the invention is made of polymer material filled with glass or carbon fibers, which makes it possible to improve the intrinsic mechanical properties of this part
Implementation Method 2
due to the very high melting temperature of PEEK, a non-negligible shrinkage occurs during the cooling of the part, after its injection molding. However, the variations in thickness of plastic material at different points of the part lead to differences in shrinkage
Data Source
AI summary
The Oldham coupling, used in motor vehicles, has two coaxial orifices (12, 13) to receive shafts, is made from a polymer material with glass or carbon fibre filling and has a thickness at any point that is less than 4 mm and preferably less than 2 mm. The two orifices are elongated in shape and lie perpendicular to one another, and the coupling is reinforced by ribs (16, 17, 18) connected to the walls (14, 15) surrounding the orifices.