Rotating Spring Clip with Incompatible Plastic Materials
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Solution Overview
Problem
Traditional spring clips with plastic rings exhibit poor resistance to wear and stress, particularly under rotational and axial forces, posing safety risks in applications like pet leashes and sports equipment where quick and secure connections are critical.
Innovation Solution
A two-step moulding process using incompatible synthetic plastic materials for the spring clip body and ring, ensuring mechanical strength and allowing for fluid rotation by preventing mutual adhesion through geometrical details and chemical incompatibility, such as using acetal resin for the ring and polybutylene terephthalate or polyamide for the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional spring clips use a pin fixed by screwing into a threaded seat, then the structure is simple and easy to manufacture, but the resistance to wear and stress is poor
Solution Approach 1:
The patent combines the pin, retaining ring, and threaded seat into a single integrated pin component made of metal. This merging eliminates the need for separate retaining rings and multiple assembly steps, while providing superior stress resistance through the metal material's inherent strength properties.
Solution Approach 2:
The patent employs composite construction by making the pin from metal material while the spring clip body remains plastic. This composite approach allows the metal pin to provide high strength and wear resistance at the critical connection point, while maintaining the overall lightweight and cost-effective plastic construction of the spring clip.
2Reliability
If the ring is fixed on a pin with simple screwing connection, then the device complexity is low, but the reliability under rotational and axial stress is poor
Solution Approach 1:
The patent merges the pin and retaining ring functions into a single integrated metal pin component with a head portion. This integration eliminates potential failure points from separate components and their connections, while the metal material provides inherent reliability under rotational and axial stresses without requiring complex retention mechanisms.
3Strength
If metal spring clips are used to achieve high strength, then the resistance to stress is improved, but the weight increases
Solution Approach 1:
The patent applies local quality by using metal material only for the pin component where high strength is critically needed, while the rest of the spring clip body remains plastic. This localized application of strong material provides sufficient traction resistance without the weight penalty of making the entire spring clip from metal.
Solution Approach 2:
The patent uses a composite material approach combining plastic for the spring clip body and metal for the pin. This composite construction achieves the necessary strength-to-weight ratio by strategically placing metal only where mechanical stress is highest, maintaining lightweight properties while ensuring adequate load-bearing capacity.
4Ease of operation
If compatible plastic materials are used for moulding, then the manufacturing process is simple, but the two parts adhere to each other preventing free rotation
Solution Approach 1:
The patent applies parameter changes by selecting specific incompatible plastic material combinations (such as POM for the ring and PA6/PA66 for the body) that have different chemical properties and melting points. This material parameter selection prevents adhesion during moulding while ensuring both parts can be manufactured through standard injection moulding processes without requiring complex process modifications.
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 solution provides spring clips with high traction resistance comparable to metal clips but at reduced costs, ensuring secure and reliable connections with free rotational movement, mitigating the risks of jamming or breakage in high-stress situations.
Implementation Method 1
making the respective synthetic plastic materials used to make the ring and the body of the spring clip incompatible with each other beforehand
Data Source
Figure 1~3
Figure 4~7
AI summary
Described is a safety spring clip (10) equipped with front coupling means (13) and a rear pin (12) with a widened head, connected to a rotating ring (11). The body of the spring clip is made of a first plastic material, whilst the body of the rotating ring (11) is made of a second plastic material. Typically, the first and second plastic material are inherently incompatible or made incompatible with each other and cannot be fused or in any way welded together.