Under the condition of limited laser energy, it is of great significance to understand and effectively control the laser distribution in the laminar flow column to solve the problem of depth capability decline caused by the taper effect of the slit in the thick plate material waterjet guided laser processing. In this paper, the distribution of laser energy in the water column is analyzed by means of simulation and experiment. In the simulation analysis, using ZEMAX software, the energy distribution of axial position and radial position (diameter section) in water column is simulated and analyzed for the different focal length and nozzle diameter. In addition, the simulation results are verified by experiments. The results show that: the laser energy in the laminar water column still presents the characteristics of Gaussian like distribution, which will make the material remove very difficult at the edge of the water column due to the insufficient power density. This is easy to produce machining taper effect. Finally, the energy distribution conditions of high efficiency material removal by water guided laser are given. This study provides a theoretical and technical basis for further understanding the law of energy transmission and distribution of water column in water guided laser.
As a new type of micro machining technology, waterjet guided laser processing technology has the advantages of small thermal damage, strong depth ability and small taper effect compared with the traditional dry laser processing technology, and it has broad development and application prospects. 7050 aluminum alloy has been widely used in aerospace manufacturing because of its high strength, high toughness and excellent stress corrosion resistance. In this paper, 7075 aluminum alloy was processed by waterjet guided laser processing technology, and they were studied that the influence of waterjet speed and workpiece feed speed on cutting depth and surface quality. The results show that the cutting depth increases with the increase of waterjet speed in single cutting, and decreases with the increase of workpiece feed speed. By adjusting the process parameters, the surface quality of cutting surface and micro hole machining is better than the results of traditional dry laser processing. In conclusion, the influence of laser processing parameters on the processing of aluminum alloy is analyzed, and the processing method of 7075 aluminum alloy is expanded.
Water-guided laser processing technology can be used for precision machining of refractory materials such as superalloy and composite materials. Compared with traditional short-pulse laser processing, it has the advantages of less thermal damage, smaller taper and greater depth, cleaner surface and so on. However, the existing technologies have two key problems of low laser coupling power and poor process reliability, which seriously affect laser processing efficiency and workpiece processing quality. Based on this situation, a water-gas shrinkage-guided high-power laser processing (WSLP) technology is proposed innovatively in this paper. Firstly, the laminar shrinkage mechanism is analyzed. secondly, the characteristics of water-gas contraction and total reflection conducting laser are investigated by simulation. The results show that water-gas compressibility effect can make water-jet compressed to within 0.1mm; and some systematic disturbance does not affect the laser coupling efficiency because of the total reflection effect at the water-gas interface, which verifies the stability and reliability of the system. In addition, water-gas shrinkage coupling experiment and total reflection conducting laser experiment are completed. The experiment result shows that the laser coupling efficiency can reach up to 93%; The feasibility of the system processing is verified by the tests.