Tube Fitting Body Stepped Wall Surface Disassembly

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Solution Overview

Problem

Existing tube fittings face challenges in disassembly due to radial reaction forces that resist separation of contacting components during pull-up, leading to difficulties in efficiently disassembling the fittings.

Innovation Solution

The design incorporates recessed, tapered, or stepped surfaces on fitting components to reduce radial reaction forces and enhance axial reaction forces, facilitating the separation of components during disassembly by providing a surface for the displaced portion to contact, thus assisting in the disassembly process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If fitting components are designed with standard contacting surfaces, then the fitting provides sufficient radial containment and structural integrity, but radial reaction forces resist separation of components during disassembly

Engineering Contradiction:
Improveease of disassemblyVSAvoidradial reaction force
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The patent applies local quality by creating a recessed portion in the socket wall at a specific location where the tube contacts during disassembly. This localized modification changes the geometric properties only in the critical contact zone, allowing the tube to contact the recessed surface and convert radial reaction forces into axial separation forces, thereby reducing the radial forces that resist disassembly while maintaining structural integrity elsewhere in the fitting.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent inverts the traditional approach by designing the socket with a recessed portion that actively promotes separation rather than resistance. Instead of the socket wall providing continuous radial containment that resists separation, the recessed surface is positioned to contact the tube in a way that generates axial forces facilitating pull-apart, effectively reversing the force direction from resistive to assistive during disassembly.

Inventive Principle:
Principle #13The other way round (Inversion)

2Ease of operation

If fitting components are designed with extended contact surfaces, then radial reaction forces are increased for better containment, but disassembly becomes more difficult due to increased resistance

Engineering Contradiction:
Improveease of disassemblyVSAvoidcontact surface geometry
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

Rather than modifying the entire socket wall geometry, the patent applies a localized recessed portion only in the specific region where tube contact occurs during disassembly. This minimal geometric modification avoids increasing overall device complexity while effectively addressing the disassembly difficulty by creating a focused separation assistance zone.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If fitting components are designed with recessed surfaces to reduce radial reaction forces, then disassembly is facilitated, but manufacturing precision requirements increase

Engineering Contradiction:
Improveease of disassemblyVSAvoidrecessed surface positioning
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The recessed portion is localized to a specific axial position and radial depth, concentrating the manufacturing precision requirements to a small, well-defined feature rather than distributing them across the entire socket. This allows for controlled machining of the recessed geometry with standard tolerances, as the critical dimensions are limited to the recessed portion's position, depth, and curvature radius.

Inventive Principle:
Principle #3Local quality

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 effectively reduces radial reaction forces and increases axial forces, making it easier to disassemble tube fittings by minimizing interference and promoting the separation of components, thereby simplifying the disassembly process.

Implementation Method 1

By providing a recessed longitudinal surface in the tube socket, the radial force component between the first and second components may be reduced, thereby assisting in separation of the first and second components during disassembly of the fitting assembly

Methodology Applied
Scientific EffectRadial reaction force reduction:

Implementation Method 2

When the fitting assembly is pulled-up, additional engagement between the tube socket and the tube end portion, for example, due to radially outward deflection or bowing of the tube end resulting from axial compression of the tube end, produces axial and radial reaction force components between the tube socket and tube end portion

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

radially outward deflection or bowing of the tube end resulting from axial compression of the tube end

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2489913B1Fitting body with adapted engaging surfaces
Publication Date: 2016.03.30 SWAGELOK CO
  • EP2489913B1 patent drawingFigure 1~2
  • EP2489913B1 patent drawingFigure 1A~2B
  • EP2489913B1 patent drawingFigure 3~3A

AI summary

A fitting assembly is provided with a first fitting component having a stepped wall surface; and a second fitting component radially spaced from the first fitting component when the fitting assembly is in a finger tight condition prior to pull-up. When the second fitting component is displaced into contact with the stepped wall surface during fitting pull-up, the stepped wall surface assists in separating the first fitting component from the second fitting component upon fitting disassembly.