Laser Micro-processing On Complex Surface

Laser Micro-Processing has been widely studied in the last half century,and has great applications in many scientific and industrial fields.Using nanosecond and femtosecond lasers,the experimental system of laser precision machining for complex curved surface parts is established.The main research results are as follows:(1)The experimental method of laser processing uniform structure color on complex surface was studied,including sample zoning planning,complex processing path design,sample attitude adjustment to ensure laser vertical incidence,focus control,etc.By using nanosecond laser with wavelength of 532 nm and pulse width of 90 ns,precise five-axis motion system and self-developed computer-aided manufacturing program,subwavelength periodic fringes were prepared on plane and complex curved surface by precise control of mechanical motion and laser irradiation parameters.The effect of laser fluence and scanning velocity on fringe formation were studied.It was found that the best fringe was formed when the energy flow density F=7.52 J/cm~2 and the scanning velocity v=7.0 mm/s.Combining with the polarization control device,a synchronous polarization control technology is developed to realize the synchronous control of the laser polarization direction,so as to realize the precise control of the ripple direction.The effect of ripple directions on the coloring effect was studied.The color pattern with bright color and clear outline was prepared on stainless steel plate.Furthermore,the color patterns on the complex surface were prepared.(2)The characteristics of femtosecond laser rotary cutting and drilling were analyzed.By using femtosecond and nanosecond laser processing method and designing a series of computer programs,the high precision machining of shaped cooling holes were realized on the nickel base alloy plate.The determination results show that the contour edges of the cooling holes are clear,the rounded corners are regular,and the errors are less than 25μm.The inner wall of shaped cooling hole is regular and smooth without obvious ablative adhesion.In the laser fabrication of 3D structures of complex surface parts,the key techniques of precise positioning of irradiation point based on iterative error compensation and nondestructive detection of micro hole on complex surface are developed.The experimental results show that the positioning errors in the three directions of XYZ of the cooling hole on the turbine blade are less than 150μm and the angle errors in the three directions are less than 0.4°.