Resin Tube Fitting With Differential Thermal Contraction Grip
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Solution Overview
Problem
Resin tube fittings experience reduced resistance to forces pulling out the tube after undergoing heat cycles, as the materials' thermal contraction properties lead to a decrease in holding force, compromising the connection's integrity.
Innovation Solution
The resin tube fitting design incorporates an inner ring and union nut made of resin with differential thermal contraction rates, where the union nut's radial contraction rate is higher than the inner ring's, enhancing the friction force between the tube and the fitting components, thereby increasing the resistance to pull-out forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the fitting components are made of resin material, then the fitting achieves chemical resistance and ease of manufacture, but the resistance to pull-out forces decreases after heat cycles
Solution Approach 1:
The patent changes the physical parameters of the resin material by selecting specific types with different thermal contraction rates. The union nut uses resin with a higher thermal contraction rate than the inner ring, allowing differential contraction behavior during heat cycles that maintains clamping force and pull-out resistance while preserving the ease of manufacture inherent to resin materials.
Solution Approach 2:
The patent employs composite material strategy by using different resin materials for different components (union nut vs. inner ring). This allows each component to have optimized properties - the union nut contracts more during cooling to maintain grip on the tube, while the inner ring provides stable structural support, together achieving both ease of manufacture and high reliability.
2Device complexity
If the union nut and inner ring have the same thermal contraction rate, then the manufacturing is simplified, but the friction force holding the tube decreases after heat cycles
Solution Approach 1:
The patent deliberately changes the thermal contraction rate parameter to create a gradient between components. The union nut is designed with a higher thermal contraction rate than the inner ring, which generates differential movement during temperature cycles that maintains or increases the clamping force and friction force on the tube, overcoming the simplification approach of using identical materials.
Solution Approach 2:
The patent applies local quality principle by giving different thermal contraction properties to different parts of the fitting system. The union nut has higher thermal contraction rate locally optimized for maintaining grip, while the inner ring has lower thermal contraction rate for structural stability. This localized differentiation maximizes the friction force without requiring complex overall design.
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 design significantly enhances the resistance to forces pulling out the tube by increasing the friction force between the tube and the fitting, maintaining a secure connection even after multiple heat cycles.
Implementation Method 1
the inner ring and the union nut are made of resin, which has a property of contracting in response to change in ambient temperature
Implementation Method 2
the fitting can increase a friction force between the tube and the sleeve of the body, which is pressed by the connector of the union nut toward the inner radius
Data Source
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AI summary
A resin tube fitting (1) has a body (11) with a sleeve (22) allowing a longitudinal end (5) of a tube (2) to be put therein, an inner ring (12) with a press-in portion (31) configured to be pressed in the longitudinal end (5) of the tube (2), and a union nut (13) with a connector (46) configured to be screwed to an outer periphery of the body to allow the longitudinal end of the tube to be put radially between the connector and the press-in portion. The inner ring and the union nut are made of resin, which has a property of contracting in response to change in ambient temperature. The radial contraction rate of the connector is higher by 0.05% or more than that of the press-in portion of the inner ring.