Liquid Phase Diffusion Bonded Pipe Joint With Tapered Press-Fit

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Solution Overview

Problem

Conventional liquid phase diffusion bonded pipe joints face issues with unstable surface pressure during operation, leading to insufficient joining strength, especially when joining metal pipes of varying diameters and thicknesses, and irregularly shaped pipes, which can result in fractures and reduced durability.

Innovation Solution

The solution involves fitting a metal pipe over a metal joint or thick-walled metal pipe with a tapered exterior surface, expanding the end face to increase the cross-sectional area, and using an insert material for liquid phase diffusion bonding, while controlling surface pressure to enhance joining strength and prevent buckling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional liquid phase diffusion bonding is used to join metal pipes, then the joining process can be completed, but the surface pressure becomes unstable during operation resulting in insufficient joining strength

Engineering Contradiction:
Improvejoining strengthVSAvoidsurface pressure stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention applies preliminary action by pre-forming tapered portions on the metal pipes before the joining process. These tapered portions are designed with specific angles (30-60 degrees) to ensure proper alignment and stable surface pressure distribution during the liquid phase diffusion bonding process, preventing the instability that occurs in conventional direct joining methods.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention applies local quality by creating localized tapered portions only at the joining ends of the metal pipes, while the rest of the pipe maintains its original cylindrical shape. This localized modification ensures that the surface pressure is concentrated and stabilized at the critical joining interface without affecting the overall pipe structure or requiring modification of the entire pipe.

Inventive Principle:
Principle #3Local quality

2Strength

If metal pipes with varying diameters and thicknesses are joined by conventional methods, then the joining process can proceed, but the actual joining surfaces are reduced resulting in deteriorated joining strength

Engineering Contradiction:
Improvejoining strengthVSAvoidjoining surface area
Core Design Contradiction:
StrengthVSArea of stationary object

Solution Approach 1:

The invention applies parameter changes by modifying the geometric parameters of the pipe ends through the formation of tapered portions. The taper angle (30-60 degrees) and length are specifically controlled to ensure that when pipes of different diameters and thicknesses are joined, the contact surfaces maintain optimal area and pressure distribution, compensating for the dimensional variations between connected pipes.

Inventive Principle:
Principle #35Parameter changes

3Strength

If tapered metal pipes are used to increase joining surface, then the joining strength can be improved, but precise machining of metal pipes, couplings, and nipples is required which increases manufacturing complexity

Engineering Contradiction:
Improvejoining strengthVSAvoidmachining precision
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The invention applies preliminary action by pre-forming the tapered portions on the metal pipes using techniques such as rolling, swaging, or extrusion before the joining process. These methods can create the required tapered geometry with adequate precision without requiring subsequent precise machining operations, thus reducing manufacturing complexity while maintaining sufficient joining strength.

Inventive Principle:
Principle #10Preliminary action

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 approach achieves improved joining strength and stability by maintaining surface pressure during heating, allowing for effective bonding of metal pipes with different dimensions and shapes without significant increases in installation costs, thereby preventing fractures and ensuring durable connections.

Implementation Method 1

heating to a temperature higher than a liquidus temperature of the insert material and a temperature lower than the melting point of the joined members, causing the joined parts to melt

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

causing the joined parts to melt, and causing isothermal solidification

Methodology Applied
Scientific EffectSolidification: Freezing

Implementation Method 3

heating to a temperature higher than a liquidus temperature of the insert material

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP2332686B1Liquid phase diffusion bonding pipe joint and manufacturing method therefor
Publication Date: 2019.08.14 NIPPON STEEL CORPORATION
  • EP2332686B1 patent drawingFigure 1~3
  • EP2332686B1 patent drawingFigure 4~5
  • EP2332686B1 patent drawingFigure 6~7

AI summary

A liquid phase diffusion bonded pipe joint comprising metal pipes or a metal pipe and a joint pipe joined by liquid phase diffusion bonding, and a method of production of the same, the liquid phase diffusion bonded pipe joint comprised of a metal joint provided with a tapered slanted part press-fit into an end of a metal pipe by a thrust in a pipe axial direction while expanding the metal pipe in inside diameter and tightly engaging with the end and a joining surface part continuing from the tapered slanted part and joined with an end face of the metal pipe by liquid phase diffusion bonding and a metal pipe tightly engaging with the tapered slanted part in the expanded state and with an end face joined with the joining surface part by liquid phase diffusion bonding.