Laser Penetration Welding Pool Edge Detection And Digital Image Processing

Fiber laser have been increasingly widely used in the welding field of automotive,shipbuilding,aviation manufacturing industry because of its maintenance,high power,high beam equality,stability,easy to use and other advantages.However it is difficult to guarantee the weld equality in a rapid,high-automated laser welding process.The geometric features of weld pool contains important information about the quality control of the welding,Many scholars have been researching on the monitoring the weld equality by observation of the keyhole and weld pool.In this paper,an on-line coaxial monitoring system with an auxiliary illuminant was established for fiber laser welding.The wavelength range of the plasma generated during the welding process was detected using the monitoring system.The difference between the capturing system with and without the auxiliary illuminant was studied.The particular filter that can minimize the effect of plasma signal and get images of the best equality was chosen.The device for adjusting the auxiliary light source angle was designed to obtain the best shooting effect.According to the requirement of various welding speed and other welding parameters,the appropriate shooting device and data acquisition device and data processing device were designed.The coaxial monitoring system algorithm was proposed according to the efficiency of the collection system and the characteristics of the coaxially captured images.By processing the image captured during the welding process with the weld-pool auto tracking system,image enhancement method,and the Canny algorithm,the profiles of the weld pool,the heat-affect zone and the keyhole can be obtained.By calculating the weld pool features in the calibration image,the real time monitoring of the weld pool can be realized.Characteristic curve obtained by calculating the weld pool features,assisted analysis of penetration of laser welding can be achieved.Experiments were conducted applying the on-line real-time coaxial monitoring system and the equality monitoring system mechanism.The monitoring of the weld width can be realized through the weld pool width L obtained from the real-time captured images.The variation of the L means the variation of the weld width.The monitoring of the weld equality and the seam tracking can be realized simultaneously.When monitoring the penetration status,the penetration status can be divided.By calculating the distance,the seam tracking can be achieved.