Key Technologies Of The Laser Welding In The Continuous Metal Sheets Production Line Based On Visual Information

In the iron and steel industry, the ratio of metal sheets in the whole steel products is animportant index mesauring the level of steel production. Thus, the stability, operating safety ofthe metal sheets production line have always been a key research project. Therefore, how toguarantee the quality of the laser welding seam to meet the requirements on the plate productionline continuous operation has become one of core issues. As first processing step, the high powerlaser welder post weld quality detection technology is a very valuable judgment whether thewelding quality of the high power laser welder meets the requirements of continuous operationof metal sheets production lineAt First, from the analysis of the mechanism of the laser welding, the thesis studies somefactors that influence the high laser welding quality, such as laser power, the focus of theposition, the welding speed and so on. For the electromechanical complex systems of the laserwelder, all the parts of the structure and characteristics of the high laser welder are analysizedfrom the mechanical and electrical two parts. Then the laser welding process is determined by allthe parts of the structure of the high laser welde and related electrical constraint conditions.The dissertation mainly studies the visual feature extraction method of the micro laser weldseam. A kind of region search algorithm is proposed to determine the optimal region of interest,which can keep the most information, maximize reduce calculation burden, at the sametime.Then, a weld feature point robust extraction method is presented by using the least squaremethod, the spline curve fitting method, which realizes the accurate extraction of straight part,curve part in the structure light stripe. And then some weld feature parameters, such as weldwidth, misalignment, reinforcement, can be recognized, which provides abundant datainformation, so as to further weld quality evaluation.Then, a three dimension reconstructure method for the laser weld micro and the thin seam isstudied. A structure light vision measuring methods based on microscopic visual is proposed.And the corresponding visual model, structure light measurement model is established so as toobtain the weld visual characteristics corresponding position information in Cartesian space.Furthermore, And a kind of b-spline curve fitting method based on chord long is put forward,which help to reduce the influence of measurement noise and improve the weld curve fittingaccuracy. Finally the laser welding micro weld3d reconstruction is completed by combiningvisual measurement and fitting method.On the basis of the analysis of the laser welding of weld defect types and quality level, thelaser welding seam quality monitoring technology is studied. And a kind of intelligent weldquality assessment methods based on structure light vision image is designed by using arecurrent neural network classifier. Then, the seam quality can be classed by using the weldgeometry characteristics from image processing results.Based on Labview virtual instrumenttechnology, a novel weld quality monitoring softwar that can identify the key parameters of theweld quality, realize the weld characteristic parameter calculation, data3d visualization and datastorage management is accomplished, which help to improve the laser weld quality and ensurethe safe operation of the metal sheet production line. According to the laser welding process analysis and system structure, a steel continuous production laser welder position servo trackingscheme that can weld and accurate speed and position control of the focus position and gapadjustment and provide an effective scheme to improve the quality of welding is proposed.