Injection-Molded Plastic Hinge Pin for Lightweight Swivel Joint
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Solution Overview
Problem
Existing swivel joint arrangements for convertible vehicle tops are complex, costly, and require significant assembly effort, with high maintenance and wear due to metal components, and are heavy, necessitating the need for a more efficient and lightweight solution.
Innovation Solution
A swivel joint arrangement featuring a base part and pivot part with injection-molded plastic hinge pins that replace metal bolts, allowing for simplified assembly and reduced weight, with optional metal reinforcement and elastically deformable latching elements for enhanced stability and low-friction operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal bolts and multiple joint components are used, then mechanical strength is ensured, but assembly complexity and production costs increase significantly
Solution Approach 1:
The patent combines multiple separate joint components (base part, pivot part, bolt, and spacer) into a single integrated injection-molded component. The base part and pivot part are formed as one piece with an integrated hinge pin, eliminating the need for separate fasteners and spacer elements, thus simplifying assembly while maintaining structural integrity
Solution Approach 2:
The single integrated component performs multiple functions simultaneously: it provides structural support, acts as a pivot axis, serves as a fastener, and includes built-in spacer functionality. This multi-functional design replaces what previously required multiple specialized components, reducing assembly complexity without compromising mechanical strength
2Reliability
If metal components are used for joint assembly, then durability is achieved, but weight increases and corrosion resistance decreases
Solution Approach 1:
The patent changes the material parameter from metal to plastic (specifically polyoxymethylene/POM) for the joint components. This material substitution significantly reduces weight while maintaining durability through the selection of high-strength, wear-resistant plastic that exhibits excellent long-term mechanical properties and corrosion resistance
Solution Approach 2:
The invention employs composite material properties by using plastic materials with enhanced characteristics - specifically polyoxymethylene with added lubricants or dry-running additives. This creates a composite-like effect within the plastic material itself, combining structural strength with low-friction, corrosion-resistant properties that mimic or exceed metal performance
3Force
If metal joint components are used, then load-bearing capacity is sufficient, but maintenance requirements increase due to friction and wear
Solution Approach 1:
The patent changes the surface friction parameter by incorporating lubricants or dry-running additives into the plastic material composition. This modification reduces the coefficient of friction at the pivot interface, enabling smooth rotation and minimizing wear over time, thereby maintaining load-bearing capacity while eliminating maintenance needs
Solution Approach 2:
The plastic material with embedded lubricants provides self-lubricating properties, meaning the joint components automatically reduce their own friction and wear without requiring external lubrication or maintenance. The material itself serves the function of reducing friction, eliminating the need for periodic maintenance interventions
4Strength
If traditional metal assembly methods are used, then connection strength is achieved, but production costs and assembly time increase
Solution Approach 1:
The patent merges the manufacturing of multiple components into a single injection molding process. The base part, pivot part, and hinge pin are produced as one integrated component in a single manufacturing step, eliminating sequential assembly operations and significantly improving production efficiency while maintaining connection strength through integrated design
Solution Approach 2:
The injection molding process preliminarily forms the complete joint assembly with all features (including built-in spacers and pivot axes) already integrated during manufacturing. This preliminary creation of the complete functional unit eliminates the need for subsequent assembly steps, directly improving productivity while ensuring connection strength through the molding process itself
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 results in a lightweight, low-maintenance, and cost-effective swivel joint with reduced assembly complexity, eliminating the need for lubricants and minimizing corrosion, while maintaining mechanical strength and stability across various applications.
Implementation Method 1
The resulting static and sliding friction coefficients at the boundary surfaces of the hinge pin and the base part and/or swivel part allow a defined swiveling of the base part and swivel part relative to one another
Implementation Method 2
A plastic pivot pin also counteracts the negative effects of aging caused by corrosion, such as sluggishness of the swivel joint caused by rusting
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The hinge assembly has a base part (1) and a swivel part (2), which are swivel-mounted to each other. The through-openings (3',30) are arranged partially overlapping on each other. A manufactured hinge bolt (5) is arranged in the through-opening by die-casting, which is fixedly connected with the base part or the swivel part. The hinge bolt is molded at the base part or at the swivel part. An independent claim is also included for a method for manufacturing a hinge assembly.