Friction Stir Welding Buffer Bead for Plate Heat Exchanger Leaks
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Solution Overview
Problem
Brazed aluminum plate heat exchangers face issues with leaks and material cracking due to welding inhomogeneities and thermal stress, particularly when welding connection devices onto the heat exchanger block, which can lead to susceptibility to cracking and leakage.
Innovation Solution
The method involves using friction stir welding to create a buffer weld bead on the heat exchanger block, allowing for a second weld to attach the connection device, reducing thermal stress and eliminating soldering inhomogeneities, thereby minimizing the risk of leaks and material cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional welding is used to attach connection devices to the heat exchanger block, then the attachment process is simple and direct, but the risk of leaks and material cracking increases due to welding inhomogeneities and thermal stress
Solution Approach 1:
The welding process is divided into two distinct stages: first, friction stir welding is used to create a homogeneous buffer weld bead that eliminates material inhomogeneities; second, conventional welding is used to attach the connection device to the prepared surface. This segmentation allows each welding stage to serve a specific function, reducing overall cracking risk while maintaining manufacturing simplicity.
Solution Approach 2:
Before attaching the connection device, a preliminary friction stir welding pass is performed to create a buffer weld bead on the heat exchanger block surface. This preliminary action eliminates soldering inhomogeneities and reduces thermal stress in advance, preparing the surface for the subsequent connection device attachment without compromising reliability.
2Reliability
If friction stir welding is used to create a buffer weld bead first, then the risk of leaks and cracking is reduced, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
A buffer weld bead created by friction stir welding serves as an intermediary layer between the heat exchanger block and the connection device. This intermediary structure eliminates material inhomogeneities and reduces thermal stress, acting as a bridge that improves reliability while allowing the subsequent welding process to proceed more reliably.
Solution Approach 2:
The conventional direct welding process is replaced with a two-stage process where friction stir welding (a mechanical solid-state welding process) is used first to create the buffer weld bead, followed by conventional welding. This substitution of welding mechanisms reduces thermal stress and material cracking while maintaining process feasibility.
3Productivity
If conventional welding is used directly on the brazed surface, then the manufacturing process is fast and simple, but welding inhomogeneities and thermal stress cause material cracking and susceptibility to leaks
Solution Approach 1:
The welding process is segmented into two functional stages: friction stir welding to create a homogeneous buffer weld bead that eliminates surface inhomogeneities, followed by conventional welding to attach the connection device. This segmentation ensures high weld quality while maintaining efficient production through automated processes.
Solution Approach 2:
The welding parameters are changed by introducing friction stir welding as a preliminary step, which fundamentally alters the thermal and mechanical parameters of the subsequent welding process. This creates a more favorable base material state for welding, improving precision without significantly impacting overall manufacturing speed.
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 enhances the durability and reliability of the plate heat exchanger by reducing the risk of leaks and material cracking, ensuring a strong and leak-proof connection while maintaining the structural integrity of the heat exchanger block.
Implementation Method 1
The surface area provided for fixing the connection device to the heat exchanger block is provided with at least one weld bead, also referred to as a buffer bead, by means of a first weld. The welding process used for the first weld is friction stir welding.
Implementation Method 2
The connection device is then welded onto the weld bead produced by the first weld by means of a second weld.
Data Source
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AI summary
The invention relates to a method for producing a plate heat exchanger and to the plate heat exchanger itself. In particular, the invention is directed to a soldered aluminium plate heat exchanger. In the claimed method for producing a plate heat exchanger: a heat exchanger block (1) is provided which comprises a plurality of partition plates (4) and edge strips (8) arranged therebetween; a connection device (7) is provided to be mounted on said heat exchanger block (1); a planar region (10), provided for the purpose of securing said connection device (7) to the heat exchanger block (1), is provided with at least one welded weld bead (12) by means of a first weld (11); and said connection device (7) is welded onto the weld bead (12) by means of a second weld (13). The welding method used for the first weld (11) is a friction stir welding method.