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Laser welding method and device additionally adopting variable-frequency magnetic fields

A technology of laser welding and laser welding head, which is applied in the direction of laser welding equipment, welding equipment, metal processing equipment, etc., can solve the problems of welding seam thermal cracks, large temperature gradient, fast cooling speed, etc., to achieve grain refinement, accelerated Escaping of air bubbles and improving welding quality

Inactive Publication Date: 2020-01-03
JIANGSU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, during the welding process, due to the large temperature gradient of the molten pool, a large number of columnar crystals are produced in the weld, and the macroscopic performance is that there is a large amount of residual tensile stress in the weld during welding, which leads to thermal cracks in the weld At the same time, due to the fast cooling rate, the bubbles in the molten pool have no time to escape, and are easy to remain in the molten pool, thus forming pores after the weld solidifies.

Method used

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  • Laser welding method and device additionally adopting variable-frequency magnetic fields
  • Laser welding method and device additionally adopting variable-frequency magnetic fields
  • Laser welding method and device additionally adopting variable-frequency magnetic fields

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Embodiment 1

[0026] The thickness of the welded plate used in this embodiment is 4mm, and the material is 316L stainless steel

[0027] Fix the workpiece on a workbench with a fixture, and use the above-mentioned laser welding process on the thin plate without any auxiliary equipment. The parameters of the laser welding are that the spot diameter is 0.3mm, the laser power is 4kW, and the welding speed is 2m. / min, laser control current 80A, pulse width 15ns, pulse frequency 6Hz. The tensile test and the metallographic observation of the welded seam section were carried out on the welded thin plate, and the tensile data and the welded seam section metallographic diagram were used as comparison group 1.

Embodiment 2

[0029] The strip welding thickness used in this embodiment is 4mm, the material is 316L stainless steel, and the melting point is 1400°C, that is, 1673.15K, T DRX =aT m (K)=0.4×1673.15K=339.26K, that is, 396.11°C. The temperature of the high pressure fluid flow is 50%T DRX =138.64°C. The current passed into the exciting coil is 13A, and the effective magnetic path length is L e is 50mm.

[0030] Technical scheme of the present invention, its concrete steps are:

[0031] (1) Treat the surface of the weldment to be welded and place it on the weldment workbench.

[0032] (2) A direct current of 13A is passed into the exciting coil, and the lower exciting coil 1, the lower exciting coil 2, and the upper exciting coil generate magnetic fields respectively, and the coil numbers of the lower exciting coil 1, the lower exciting coil 2, and the upper exciting coil are respectively 80, 80, 100; the frequency of the magnetic field excited by the lower exciting coil 1, the lower exc...

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Abstract

The invention relates to the laser welding field, in particular to a laser welding method and device additionally adopting variable-frequency magnetic fields. Excitation coils with different coil numbers are adopted to excite the variable-frequency magnetic fields with different intensities and different frequencies, the magnetic field radiation areas of welded pieces are made to be sequentially in the to-be-welded state, the molten state and the to-be-post-processed state according to the processing time sequence. Additionally arranged magnetic field devices which can excite different frequencies and different intensities and move along with a laser head are adopted to conduct pre-welding, during-welding and post-welding treatment on different areas with magnetic fields of different intensities and frequencies, the to-be-welded pieces are preheated under the action of the heating effect of the magnetic fields, so that the pool depth is lowered; during laser welding, the method of additionally exerting a high-frequency magnetic field is adopted in a weld pool area, and the weld pool area is stirred; and when laser welding is completed, post-welding heat treatment is conducted on the welded area with a low-frequency magnetic field. By the adoption of the laser welding method and device additionally adopting the variable-frequency magnetic fields, the temperature gradient of theweld pool can be effectively reduced, the temperature of the weld pool is evenly distributed, air pores and other defects are reduced, and the welding quality is improved.

Description

technical field [0001] The present invention relates to the field of laser welding, in particular to a laser welding method and device with an external frequency conversion magnetic field. The present invention can reduce the temperature gradient of the molten pool and make the temperature distribution of the molten pool uniform through the interaction of the thermal effect and the force effect of the magnetic field. At the same time, defects such as pores are reduced, and the welding quality is improved. Background technique [0002] Laser welding is an emerging welding technology in recent years. Laser welding is an efficient and precise welding method that uses a high-energy-density laser beam as a heat source. With the development of welding technology and the research and development of industrial lasers, laser welding technology has been widely used in many welding industries. In foreign countries, laser technology in many developed countries has been popularized in v...

Claims

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Application Information

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IPC IPC(8): B23K26/21B23K26/12B23K26/24B23K26/70
CPCB23K26/12B23K26/24B23K26/21B23K26/70B23K26/702
Inventor 徐刚鲁金忠罗开玉姚建华张群莉
Owner JIANGSU UNIV
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