Laser-Welded Thin-Walled Corrugated Metal Tubes With Small Diameters
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Solution Overview
Problem
Conventional methods for producing thin-walled, corrugated tubes with small diameters face challenges such as complex joining processes, large welding seams, and difficulties in achieving uniform wall thickness and diameter reduction, particularly for nonferrous metals like copper and aluminum, which are essential for heat exchangers due to their high thermal conductivity.
Innovation Solution
A continuous process using a laser with wavelengths less than 600 nm for welding thin-walled nonferrous metal strips to form radially closed hollow profiles, allowing for selective corrugation in sections, which eliminates the need for complex after-working and reduces production steps by directly producing high-quality tubes with small diameters and low wall thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electric arc welding is used to join metal strip edges, then the edges can be welded together, but a pronounced welding bead is produced on the inside of the tube requiring additional smoothing or removal operations
Solution Approach 1:
The patent replaces electric arc welding with laser welding to join the metal strip edges. This substitution eliminates the pronounced welding bead produced by electric arc welding, as the laser welding process creates a cleaner weld with minimal protrusion into the tube interior, thereby reducing or eliminating the need for subsequent smoothing or bead removal operations.
Solution Approach 2:
The patent changes the welding parameters by using laser welding instead of electric arc welding. This parameter change affects the energy distribution, heat input, and melting characteristics, resulting in a welding seam with reduced bead formation and improved surface quality inside the tube.
2Manufacturing precision
If multiple drawing processes are used to reduce wall thickness and diameter, then thin-walled small diameter tubes can be produced, but the process becomes complex and time-consuming
Solution Approach 1:
The patent performs the welding operation before the drawing process, using laser welding to create a clean weld seam that requires minimal subsequent processing. This preliminary action with laser welding eliminates the need for multiple drawing processes and intermediate smoothing operations, as the laser-welded tube can be directly drawn to the final dimensions with the welding seam automatically smoothed during the drawing operation.
Solution Approach 2:
The patent extracts the welding operation from the sequence of operations that would otherwise require multiple drawing and smoothing steps. By using laser welding to create a clean seam that can be directly drawn, the process removes the need for intermediate smoothing operations and reduces the number of drawing passes required.
3Area of stationary object
If tube ends are corrugated, then heat exchange surface area is enlarged, but the ends cannot be directly welded to smooth-walled sections without additional forming operations
Solution Approach 1:
The patent applies corrugation to the tube ends before the welding operation. This preliminary corrugation creates the desired heat exchange surface area, and the subsequent laser welding of the corrugated ends to smooth-walled sections is made possible because the laser welding process can accommodate the corrugated geometry without requiring the ends to be re-formed smooth, thereby simplifying the joining process.
Solution Approach 2:
The patent changes the sequence of operations by corrugating the tube ends before welding, rather than welding first and then corrugating. This parameter change in the process sequence allows the corrugated ends to be directly welded using laser welding, eliminating the need for additional forming operations to prepare the corrugated ends for welding.
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 process enables the production of high-quality, thin-walled, corrugated tubes with reduced production steps, eliminating the need for subsequent drawing processes and achieving seamless connections without pronounced welding beads, allowing for efficient heat transfer and mechanical properties comparable to seamless tubes.
Implementation Method 1
welded continuously by means of a laser which radiates light having a wavelength of less than 600 nm
Implementation Method 2
welding by means of a laser which radiates light having a wavelength of less than 600 nm
Data Source
AI summary
A process for the continuous production of thin-walled, radially closed hollow profiles which are composed of nonferrous metals and have a small cross section comprises supply of a flat strip of the nonferrous metal to a forming apparatus (212) at a first supply speed, where the thickness of the strip corresponds to the wall thickness of the hollow profile. The forming apparatus (212) is configured for continuous forming of the flat strip supplied into a shape corresponding to the hollow profile. After forming, two opposite edges of the flat strip rest flush against one another in a contact region. A welding apparatus (216) continuously welds the edges which rest flush against one another by means of a laser which emits light having a wavelength of less than 600 nm. The laser heats a point in a welding region which has a diameter which is less than 20% of the cross-sectional dimension of the hollow profile. The welded hollow profile is taken off from the welding region, provided in a corrugator (225) with parallel or helical corrugation in sections and taken up in an uptake device (226).