Flexible Membrane Diffusion Bonding Apparatus for Annular Cylinders
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Solution Overview
Problem
There is a need for reliable, void-free bonding methods and apparatus to join curved or flat surfaces of two parts, particularly for Stirling engine components like the exterior wall of an annular heat exchanger and the interior wall of a concentric cylinder, where existing methods often result in inefficient heat transfer due to suboptimal bond quality.
Innovation Solution
A method and apparatus utilizing a cylindrical body with a radially expansible membrane and pressurization system to ensure a void-free diffusion bond or brazed joint between the exterior and interior walls of annular cylinders, allowing for precise alignment and pressure-controlled expansion to achieve a strong, void-free bond without filler materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding methods are used to join the exterior wall of the annular heat exchanger to the interior wall of the heater head, then the bonding process can be completed, but the bond joint quality is suboptimal resulting in voids and inefficient heat transfer
Solution Approach 1:
The patent employs a flexible membrane inflated with pressurized gas to apply uniform radial pressure between the heat exchanger and heater head surfaces. This pneumatic approach ensures complete surface contact and eliminates voids in the bond joint, achieving void-free bonding that maximizes heat transfer efficiency while maintaining reliable joint quality.
2Manufacturing precision
If a rigid bonding apparatus is used to join curved surfaces, then structural stability is maintained, but the apparatus cannot adapt to the curved geometry resulting in poor surface contact
Solution Approach 1:
The patent utilizes a flexible membrane that can conform to the curved cylindrical surfaces of the heat exchanger and heater head. This flexible film adapts to the geometry of the parts being bonded, ensuring complete surface contact and precise manufacturing quality without requiring a complex rigid apparatus designed for each specific curvature.
Solution Approach 2:
The bonding apparatus transitions from a static rigid structure to a dynamic flexible system. The membrane can expand and contract as needed, allowing the apparatus to adapt its shape to match the curved surfaces being bonded. This dynamic capability enables precise surface contact while maintaining relatively simple apparatus design.
3Reliability
If high pressure is applied during bonding to ensure void-free joints, then bond quality improves, but the bonding apparatus must withstand high stresses increasing its complexity
Solution Approach 1:
The flexible membrane serves as both the bonding medium and the pressure containment structure. Its flexibility allows it to distribute high pressures uniformly across the bonding surface while conforming to the curved geometry, achieving void-free bonds without requiring a complex rigid pressure containment apparatus.
Solution Approach 2:
The flexible membrane automatically distributes the applied pressure uniformly across its surface and adapts to the geometry of the parts being bonded. This self-adjusting capability ensures void-free bonding at high pressures while the membrane itself serves as the simple containment structure, eliminating the need for complex external pressure application mechanisms.
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 enables reliable, void-free bonding of annular cylinder surfaces, enhancing heat transfer efficiency in Stirling engines and applicable to various materials, with the ability to form permanent or temporary bonds and adapt to different applications.
Implementation Method 1
pressurization means, such as intersecting radial and axial bores, are provided for conveying a pressurized fluid, e.g., air or helium, to and from the cavity for pressurization/depressurization of the cavity
Implementation Method 2
effecting a reliable, void-free diffusion bond or brazed joint between the surfaces of two parts
Implementation Method 3
effecting a reliable, void-free diffusion bond or brazed joint between the surfaces of two parts
Data Source
AI summary
Apparatus for diffusion bonding, brazing, or joining between respective surfaces of two parts, e.g., the exterior wall of a first annular cylinder and the interior wall of a concentric second annular cylinder, includes a cylindrical body having a circumferential cavity positioned between upper and lower ends thereof. A flexible annular membrane is disposed concentrically over the cavity, and respective upper and lower ends of the membrane are each sealingly hinged to the body. The body is assembled coaxially within the first cylinder, and the assembly then inserted coaxially into the second cylinder to the desired axial bonding position. The cavity is pressurized, causing the membrane, and responsively, the first cylinder, to expand radially within the second cylinder. The temperature of the parts is then raised and maintained for a selected period of time to bond the respective walls of the two cylinders to each other.