Detection Of Laser Molten Pool Temperature Field Based On CCD

Laser cladding technology is a new type of forming technology that uses laser as the energy source and adopts the coaxial powder feeding method to melt the material powder layer by layer on the substrate to generate three-dimensional metal workpieces.This technology has been widely used in the aerospace,automobile shipbuilding and mechanical mold manufacturing and other fields because of the advantages of less heat input,high work-piece strength and less material consumption.During the laser cladding process,the temperature distribution of the molten pool affects the mechanical properties and the forming quality of the formed workpieces.The detection of the temperature field on the molten pool surface is the kernel task of the real-time feedback control.However,due to the high temperature,strong brightness,small size,and complex thermal processes,it is difficult to measure the temperature field on the surface of the molten pool.For the above problem and the temperature field of the molten pool obtained by CCD colorimetric measurement is not clear and accurate,two kinds of non-contact temperature measurement systems are set up in this paper,which are coaxial color CCD temperature measurement and side mounted infrared thermometer temperature measurement.By improving experimental methods,selecting CCD,lens,filter and other hardware,optimizing cladding parameters,shooting parameters,the RB gains and other experimental parameters,correcting the main experimental error,the CCD colorimetric temperature measurement system can not only obtain a clear and stable surface image of the molten pool,but also can process and calculate the photographed image of molten pool by the developed software to obtain the surface temperature field of the molten pool.Through measuring different areas of the surface of the molten pool by the infrared temperature measurement system,the surface temperature distribution of the molten pool which is consistent with the CCD temperature measurement results is obtained.This verifies the feasibility of CCD colorimetric temperature measurement,and illustrates that the coaxial temperature measurement platform constructed is practical and reliable.In this paper,we obtained the surface temperature field of the molten pool,the variations of the temperature distribution and geometrical parameters with the laser power and the number of cladding layers by the temperature measurement experiments,it provides the solid foundation for the real-time feedback control of the laser cladding forming system in the future.