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A method of controlling molten pool in laser welding based on Lorentz force

A laser welding and control method technology, applied in laser welding equipment, welding equipment, manufacturing tools, etc., can solve the problems of unstable welding process, easy to produce pores, humps and arc craters, etc., achieve good fluidity and increase penetration depth , the effect of enhancing the ability

Active Publication Date: 2020-09-01
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a method for controlling the movement behavior of the laser welding "small hole" and the molten pool by using the Lorentz force generated by the interaction between the current and the magnetic field in the laser welding pool, in order to solve the problems that often occur in the laser welding process. The welding process is unstable, prone to defects and deficiencies such as pores, cracks, undercuts, humps and arc craters

Method used

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  • A method of controlling molten pool in laser welding based on Lorentz force
  • A method of controlling molten pool in laser welding based on Lorentz force
  • A method of controlling molten pool in laser welding based on Lorentz force

Examples

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Embodiment 1

[0031] The specific implementation device of this embodiment is as figure 2 , image 3 shown. The welding material is 316L stainless steel, the thickness of the plate is 20mm, and the dirt is removed on the surface; the laser power is 18KW, the spot size is 0.45mm, and the welding speed is 1m / min; Material: chrome-zirconium copper, electrode form: a pair of rollers, the angle between the two electrodes is 60°, the distance between the electrodes (the distance between the electrode and the contact point on the workpiece surface) is 12mm, the current is 100A DC, the distance between the electrode and the laser beam (the electrode contact point) The distance between the connection line and the central axis of the beam) is 2mm; the strip-shaped NdFeB permanent magnet is arranged obliquely in front of the molten pool to form an angle of 30° with the surface of the workpiece, the size of the magnet is 50×9×4mm, and the magnetic field strength in the welding area is 0.1T.

Embodiment 2

[0033] In the present embodiment, the electrode of the implementation device is changed from the roller of embodiment 1 to a round rod, the electrode diameter is 5mm, the electrode material is chromium-zirconium copper, the electrode spacing (the distance between the electrode and the surface contact point of the workpiece) is 8mm, and 50A is applied between the two electrodes. Constant current; the distance between the electrode and the beam (the distance between the electrode contact line and the central axis of the beam) is 1mm, the welding material is 6061 aluminum alloy, the plate thickness is 4mm, and the surface removes dirt and oxide film; the laser power is 4.5KW, and the spot size is 0.45mm , welding speed 2m / min; front shielding gas: Ar gas, flow rate 15L / min, back 10L / min Ar gas shield; strip-shaped NdFeB permanent magnets are placed in front of the molten pool obliquely at an angle of 30° with the surface of the workpiece, the size of the magnet It is 50×9×4mm, and...

Embodiment 3

[0035] The specific implementation device of this embodiment is as Figure 4shown. The magnetic field is provided by an electromagnet coaxial with the laser, the magnetic field is a sinusoidal alternating magnetic field, the frequency is 50Hz, and the maximum magnetic field strength in the welding area is 0.2T. Welding material 2024 aluminum alloy, plate thickness 6mm, remove dirt and oxide film on the surface; laser power 5KW, spot size 0.45mm, welding speed 1.5m / min; front shielding gas: Ar gas, flow rate 15L / min, back 10L / minAr Gas protection; electrode material: chrome-zirconium copper, electrode form: a pair of rollers, the angle between the two electrodes is 60°, the electrode spacing (the distance between the electrode and the contact point on the workpiece surface) is 12mm, the current is DC 100A, the electrode and the laser beam The distance (the distance between the electrode contact line and the central axis of the beam) is 2mm.

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Abstract

The invention provides a Lorentz-force-based laser welding pool control method and belongs to the technical field of laser processing. According to the method, current and a magnetic field which are perpendicular to each other are applied to a laser welding pool to generate Lorentz force following the ampere left-hand law in the welding pool; the stress state, the flow behavior and the solidification process of a melt are actively controlled through the Lorentz force. The backward Lorentz force is applied to the welding pool to make a welded tiny hole be deepened and stretched, so that metal vapor / plume in the tiny hole escape smoothly. A solution in the welding pool flows smoothly. The effects of increasing the weld penetration depth increase, improving the welding stability and optimizing welding formation are achieved. If AC or pulse wave modulation is conducted on parameters of the applied current and the applied magnetic field, the Lorentz force can have the effects of stirring, vibrating and directionally driving the solution in the welding pool. The adjustment functions of the weld microstructure and performance can be achieved while the welding defects such as pores, cracks, undercut and poor formation are controlled.

Description

technical field [0001] The invention relates to a method for controlling a laser welding molten pool based on Lorentz force, belonging to the field of laser processing. It can be used for laser self-fusion welding, laser wire filling welding, laser narrow gap welding, etc. Background technique [0002] With its unique advantages, laser welding has been used more and more in various industrial fields such as aerospace, automobile, chemical industry, shipbuilding, etc., especially for alloys containing low boiling point alloy elements such as aluminum alloy and magnesium alloy. A large amount of evaporation, combined with the low viscosity of the melt and the small surface tension itself, are prone to defects such as pores, splashes, undercuts, and welds that are difficult to form. In addition, with the emergence of ultra-high power lasers (tens of kilowatts to hundreds of kilowatts), laser power is no longer the bottleneck that limits laser welding of large and thick plates....

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23K26/70
CPCB23K26/70
Inventor 杨武雄吴世凯吕俊霞
Owner BEIJING UNIV OF TECH
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