Swage Fitting Geometry for Heatless Expanded Tube Joints
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Solution Overview
Problem
Existing tubing fittings require heat (soldering or brazing) to join expanded end tubing sections, which is undesirable in many applications and can result in incomplete joints with potential leaks.
Innovation Solution
A swage fitting with a cylindrical body having a transition region and two sections of different diameters, where the section with the expanded end is positioned against a stop wall and the straight end section is inserted into the expanded end, allowing for crimp formation to secure the joint without heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soldering or brazing is used to join expanded end tubing sections, then a joint can be formed, but heat is required which is undesirable and may result in incomplete joints with leaks
Solution Approach 1:
The patent replaces the thermal joining process (soldering/brazing) with a mechanical joining process. A swage fitting with a tapered bore is mechanically crimped onto the expanded end of the tubing, forming a secure mechanical joint without requiring heat. This substitution eliminates the temperature requirement while maintaining joint reliability through mechanical deformation and friction fit.
2Temperature
If heatless fittings are used to join tubing, then heat is avoided, but existing heatless fittings do not work well with expanded end tubing sections
Solution Approach 1:
The swage fitting features a tapered bore with specific geometric characteristics that match the expanded end geometry of the tubing. The localized tapered shape creates a friction fit and mechanical interlock specifically at the expanded end interface, while the rest of the fitting maintains a standard cylindrical shape. This local geometric adaptation enables reliable heatless joining of expanded end tubing.
Solution Approach 2:
The fitting incorporates a tapered bore with specific angle and dimensional parameters that correspond to the expanded end geometry. By changing the geometric parameters of the fitting bore to match the expanded tubing profile, the fitting achieves proper engagement and secure mechanical joining without heat, overcoming the limitation of standard cylindrical fittings.
3Device complexity
If a single diameter fitting is used, then the fitting structure is simple, but it cannot properly accommodate both expanded end and straight end tubing sections
Solution Approach 1:
The swage fitting is divided into distinct functional zones: a tapered bore section for receiving and securing the expanded end tubing, and a cylindrical section for receiving the straight end tubing. This segmentation of the fitting into different geometric zones allows each section to properly accommodate the specific geometry of the corresponding tubing type, enhancing versatility while maintaining a relatively simple overall structure.
Data Source
AI summary
A crimp fitting fluidically joins two sections of tubing, one section of tubing having a straight end and the other section of tubing having an expanded end. The fitting includes a cylindrical body having inner and outer walls, first and second sections and a transition region. The first section inner and outer diameters are greater than the second section inner and outer diameters. An inwardly oriented stop wall is between the first and second sections. First and second protuberances in the body define first and second annular recesses. The expanded end tubing section is positioned in the fitting first section with the expanded end against the stop wall and the straight end tubing section is positioned in the fitting second section with the straight end positioned in the expanded end. Crimps are formed in the fitting to secure the two sections of tubing in the fitting and to one another. A method of making the fitting and a method of using the fitting are also disclosed.