| With the development of high-power laser technology,which made laser power get bigger and the cost get lower,high-power lasers are widely used in laser welding in ships,rail transit,aerospace,nuclear power and other fields.Due to the unique welding advantages of laser welding,it is commonly used for welding of key components in these areas.At present,thick plate laser single-channel welding process often exists surface depression,bottom hump and drip and other weld forming defects.Due to the extremely demanding quality requirements of thick plate laser welding for some major engineering projects,stable and reliable weld quality can only be obtained by in-depth study to solve the above defects.Based on the above background,this paper mainly focuses on the problem of high-power laser thick plate welding easy to produce bottom humps and dripping weld defects to carry out the development of the defect device to suppress the bottom of the weld and carry out the welding forming control process research,and the specific work is as following:(1)Through the "sandwich" welding research method,the dynamic behavior of the thick plate welding small hole melting pool is studied,and the dynamic behavior of the melting pool in the thick plate welding process is observed by the high-speed camera.The analysis found that the surface depression and bottom hump in the thick plate welding process are due to the periodic opening and closing of the small holes in the melting pool,and the opening and closing of the small holes in the melting pool are the result of the combined effect of the melting metal pressure,the gravity of the molten metal and the surface tension at the bottom of the melting pool.The periodic opening and closing of small holes in the melting pool results in periodic changes in surface depressions and bottom humps during thick plate welding,resulting in thick plate welding defects.According to the above research and analysis results,the scheme of suppressing surface depression and bottom hump is proposed by applying electromagnetic force at the root of the melting pool to rebalance the deep-melt welding of the thick plate.The magnetic field distribution of the three-dimensional space of the rectangular permanent magnet is analyzed and optimized by ANSYS software,and the orientation of the magnet is determined,and the distribution of current density inside the energized test board is analyzed,and the current density is positively correlated with the contact distance and plate width.According to the results of the analysis,an electromagnetic force size adjustable,can achieve long weld welding electromagnetic force generator.(2)Combined with the electromagnetic force generation device to build an electromagnetic auxiliary laser welding platform,this paper studies the 14 mm thick304 stainless steel welding process under the action of electromagnetic force.Because in the welding process,large currents are easy to generate a large number of heat and uneven distribution of current density,the use of strong magnetic field,small current approach to welding stability is more favorable.This device achieves the welding of about 1m long welds of 14 mm thick stainless steel plate,and verifies the stability of the experimental device. |
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