Research On The Real-time Detection And Control For The Width Of Laser Cladding Bead

Laser cladding is an advanced process for forming, surfacing or repair of a part, has been widely used in automobile, metallurgy, national defense industry and etc. However, this process is very complex. Many factors affect it, moreover, the change in the environment may have a heavy impact on the quality of formed parts. It is necessary to research on the real time measurement and control for the process in order to improve the quality of laser cladded workpieces.The real-time measurement and control system with a CCD was improved, and its hardwares and softwares were described in detail.A molten pool (clad bead width) online measurement system was established using the equipments of charge-coupled device, filter, image capture card and computer. An image processing software of molten pool was developed with the combination of digital image processing algorithms based on VC++platform. The morphology of molten pool was extracted online during the laser cladding process to obtain the cladding band width.A closed-loop control system based on PID algorithm was designed to reduce the effects of external environment factors on the quality of the cladding band, which could change the laser scanning rate to adjust the clad band width during the laser cladding. Selection and integration of hardwares of the control system were discussed. PID control strategy was applied to achieve the real-time control of the scanning speed for control of the clad bead width.The experiments of measurement and control for laser cladding on ductile cast iron were carried out. A semiconductor laser unit and coaxial powder feeding system were applied. The effect of process parameters on the clad width was analyzed which could verify the feasibility and stability of the measurement and control system for the laser cladding.