Resin Pipe Joint Segmented Union Nut Pulling Resistance
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Solution Overview
Problem
Conventional resin pipe joints with a two-component configuration, consisting of a joint body and a union nut, face challenges in providing both effective sealing and resistance against pulling forces, especially when handling high-temperature fluids, as they tend to be weak against pulling forces and experience seal point shifting, which compromises sealing performance.
Innovation Solution
A resin pipe joint design featuring a synthetic resin-made joint body with an inner cylinder and external thread, and a union nut with internal and external threads, a seal pressing portion, a slipping-off prevention pressing portion, and a pressing inner peripheral portion, which are configured to securely fit and seal the flared tube end, preventing slipping and maintaining sealing integrity under pulling forces without increasing the number of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-component configuration (joint body and union nut) is used to reduce component number and cost, then economical advantage is achieved, but resistance against pulling forces becomes insufficient
Solution Approach 1:
The union nut is segmented into multiple functional portions: a seal pressing portion for sealing, a slipping-off prevention pressing portion for preventing tube displacement, and a pressing inner peripheral portion for providing pulling resistance. This segmentation allows each portion to specialize in a specific function, achieving high pulling resistance without adding more components.
Solution Approach 2:
Different portions of the union nut have different structural characteristics optimized for specific functions. The seal pressing portion has a specific shape to press the seal, the slipping-off prevention pressing portion has a different shape to prevent tube displacement, and the pressing inner peripheral portion has features to resist pulling forces. This local differentiation of structure enables the single component to perform multiple specialized functions.
2Reliability
If fastening is performed strongly to achieve sealing function, then sealing property is improved, but the joint becomes weak against pulling forces
Solution Approach 1:
The union nut is divided into distinct functional zones: the seal pressing portion handles sealing by pressing the seal against the tube, while the pressing inner peripheral portion and slipping-off prevention pressing portion handle mechanical strength and pulling resistance. This functional segmentation allows sealing and strength to be optimized independently without compromising either.
Solution Approach 2:
The slipping-off prevention pressing portion acts as an intermediary between the seal pressing portion and the pressing inner peripheral portion. It prevents tube displacement that would compromise the seal, thereby protecting the sealing function while also contributing to pulling resistance.
3Strength
If a C-like split ring is added to provide pulling resistance, then resistance against pulling forces is improved, but the number of components increases to three
Solution Approach 1:
The functions of the C-like split ring (pulling resistance and slipping-off prevention) are merged into the union nut itself. The pressing inner peripheral portion and slipping-off prevention pressing portion are integrated into the single union nut component, eliminating the need for a separate split ring while maintaining all necessary functions.
Solution Approach 2:
The union nut is designed as a multi-functional component that simultaneously provides: sealing (via the seal pressing portion), pulling resistance (via the pressing inner peripheral portion), and slipping-off prevention (via the slipping-off prevention pressing portion). This universal design consolidates multiple functions into a single component, avoiding the need for additional parts.
4Reliability
If the tube is flared and firmly fitted to achieve sealing, then sealing function is achieved, but the seal point shifts under pulling movement
Solution Approach 1:
The slipping-off prevention pressing portion acts as an intermediary that prevents tube displacement before it can affect the seal point. By restraining the tube in the axial direction, it ensures the seal point remains in its correct position and the sealing function is maintained under pulling loads.
Solution Approach 2:
The slipping-off prevention pressing portion preemptively prevents tube displacement in the axial direction before the seal point can shift. This preliminary restraint action ensures that the sealing interface remains stable and prevents the harmful effect of seal point shifting from occurring in the first place.
Data Source
AI summary
A resin pipe joint has: a synthetic resin-made joint body including an inner cylinder portion and an external thread portion; and a synthetic resin-made union nut including: an internal thread portion; a seal peripheral edge which is actable on a tip-end portion of a tube flared portion; a slipping-off prevention peripheral edge which is actable on a large-diameter portion of the flaring changing region; and a pressing inner peripheral portion which is externally fittable to a flared straight portion that is fitted to a straight barrel cylinder portion.