Concentric Cylinder Assembly Using Isostatic Pressure Interference
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Solution Overview
Problem
Existing methods for achieving high pressure in cylindrical chambers, such as interference-joined cylinders and coiled chambers, face limitations in assembly complexity, temperature dependency, and structural support requirements, making it difficult to efficiently join multiple thin cylinders or maintain ultra-high pressures without extensive external support.
Innovation Solution
A method of isostatic-pressure interference joining, where two or more concentric cylinders with roughness or grooves are assembled using auxiliary cylinders and caps, allowing them to be joined by varying diameters under pressure, resulting in a pre-stressed and pre-compressed chamber that withstands higher pressures uniformly when pressurized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If temperature variation is used to eliminate interference, then the interference disappears momentarily allowing assembly, but it is difficult to maintain temperature differences and the interference effect is truly little
Solution Approach 1:
The patent replaces the thermal field (temperature variation) with a mechanical field (isostatic pressure). Instead of heating and cooling to eliminate interference, the invention applies isostatic pressure to temporarily reduce the interference fit, allowing assembly through purely mechanical means. This substitution eliminates the need for temperature control systems while achieving the same assembly facilitation effect.
Solution Approach 2:
The patent changes the physical parameter used to modify interference from temperature to pressure. By applying isostatic pressure, the interference fit is temporarily reduced to enable assembly. After assembly, the pressure is removed and the interference fit is restored, providing both ease of assembly and strong joint strength without thermal effects.
2Strength
If interference joining is used to join thin cylinders tightly, then strong joints are achieved, but temperature variation method cannot achieve sufficient interference for multiple thin cylinders
Solution Approach 1:
The patent replaces thermal expansion/contraction with mechanical pressure application. By applying isostatic pressure during assembly, multiple thin cylinders can be fitted together with sufficient interference to achieve strong joints. The mechanical pressure method provides better control and greater effectiveness than temperature variation for assembling multiple thin-walled cylinders.
3Stress or pressure
If thick-walled cylinders are used to withstand higher pressure, then pressure resistance increases, but the difference in reaction stress between inner and outer edge increases
Solution Approach 1:
The patent applies preliminary action by pre-stressing the thick-walled cylinder through interference fitting of thin-walled cylinders before the chamber is pressurized. This preliminary reinforcement creates a more favorable stress distribution, reducing the stress concentration difference between inner and outer edges during operation. The interference-fit thin cylinders act as pre-applied reinforcement that improves overall stress distribution.
4Stress or pressure
If coiled chamber is used to obtain higher pressure, then pressure up to 600 MPa is achieved, but large yokes are required for external support
Solution Approach 1:
The patent uses preliminary reinforcement through interference-fitted thin-walled cylinders on the thick-walled chamber before pressurization. This pre-stressing approach strengthens the chamber wall, allowing it to withstand ultra-high pressures without requiring external coiled chambers or large supporting yokes. The preliminary reinforcement is applied during assembly and provides ongoing structural support during operation.
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
Enables the efficient assembly of multiple cylindrical tubes of varying dimensions into ultra-high-pressure chambers with improved structural integrity and reduced assembly complexity, capable of withstanding pressures higher than traditional thick-walled cylinders without the need for extensive external support.
Implementation Method 1
both chambers are successively subjected to high pressure within an assembly chamber (301), keeping the interior of each tubular chamber between the caps without pressure; such that in the larger tubular chamber the internal diameter of the smaller cylinder increases in 81, and in the smaller tubular chamber the external diameter of the larger cylinder decreases in 82 due to the increase of pressure in the assembly chamber
Implementation Method 2
two or more concentric cylinders (101, 102) by isostatic-pressure interference, which have certain roughness or fine grooves, allowing them not to slip once assembled
Data Source
AI summary
The present invention relates to a method for interference-joining concentric cylinders, where the smaller cylinder (102) does not fit into the larger cylinder (101), involving the use of auxiliary cylinders inside an assembly chamber (301), such that the interference is momentarily eliminated by means of isostatic pressure, and one cylinder is fitted into the other, yielding an interference-joined thicker cylinder. The pressure is released, and it is removed from the assembly chamber (301) finally leaving only the two interference-joined cylinders. It is possible to assemble 3 or 10 and more cylinders in the same way, assembling a thick cylinder, pre-compressed on the inside and pre-stressed on the outside. Several interference-joined cylinders exert the same stress when the cylinder withstands the maximum pressure, such that it withstands a greater pressure than a single cylinder with the same total wall thickness, which always reduces the stress from a maximum at the inside of the wall to a lower percentage at the outer edge.