| Compared with the traditional mechanical cutting methods,laser cutting can achieve rapid cutting of complex structures,high melting point,high hard and brittle metal and non-metallic materials.Laser cutting has been widely used in engineering machinery,automobile manufacturing,mining machinery,glass cutting,leather and plastic products and other industries.Domestic market demand for laser cutting machine tools is growing at a rate of more than 20% annually,but there is still a gap between domestic laser cutting machine tools and foreign similar products.There are still many shortcomings in the quality of laser cutting machine tools and laser cutting technology level of large workload,high stability and flexible cutting.The rapid development of manufacturing industry has put forward higher requirements for the quality and cutting technology of laser cutting machine tools.However,at present,the design of laser cutting machine tools in China still remains at the level of traditional design and experience design.Modern design methods are seldom used,such as low precision of laser cutting,unreasonable structure design,insufficient or excessive strength,large energy consumption and volume.The requirement of laser cutting range and accuracy is higher.The evaluation criteria of laser cutting quality are based on experience and outlook observation,and few researchers studied on the influence of laser cutting parameters on the width of cutting seam,slag hanging and the roughness of cutting section.It is necessary to reasonably design and systematically analyze the static and dynamic characteristics of the gantry laser cutting machine.Numerical simulation of the influence of laser cutting parameters on the cutting quality of magnesium alloys is significance for improving the quality of laser cutting magnesium alloys and promoting the application of magnesium alloys.Aiming at the problems of gantry laser cutting machine tool and cutting process parameters,the main research contents are as follows:(1)Establishment of three-dimensional model of gantry laser cutting machine tool.Based on the analysis of the structure and the working device of the machine tool,consulting the relevant information and parameters of the gantry type machine tool,creating the key parts of the gantry type laser cutting machine tool such as the bed and gantry beam in Creo.The guide way,lead screw and motor on the machine tool were checked and calculated.Finally,the assembly model of the gantry type machine tool were established.(2)Finite element analysis of gantry laser cutting machine.Study on the actual condition of gantry laser cutting machine tool and force analysis.The static analysis,dynamic analysis,modal analysis of laser cutting machine tool bed,gantry beam were carried out in ANSYS.Gantry beam was also optimized.The results of finite element analysis show that the maximum deformation of machine tool bed and gantry beam were 0.140E-4mm and 0.0107 mm respectively,which meet the design requirements.The maximum stresses of the laser cutting machine bed and the gantry beam are 10.2 MPa and 12.906 MPa respectively,which are far less than the allowable stresses of Q345 carbon steel.The modal natural frequencies of machine tool bed and gantry beam are much larger than the working frequencies,showing great stiffness and some optimization space.(3)Numerical simulation of laser cutting process parameters of magnesium alloy.The temperature field distribution of laser cutting AZ91 magnesium alloy was numerically simulated by ANSYS software.The non-linear thermal physical parameters,heat source moving body and boundary conditions were comprehensively considered.The cyclic loading of moving Gauss heat source was realized by software command flow programming.According to the calculation results of laser cutting temperature under different laser power,cutting speed and spot diameter,the influence of process parameters on the cutting temperature field of magnesium alloy was determined.When cutting power was 700 W and cutting speed was 30mm/s,the minimum cutting width and the optimal temperature field distribution were obtained.(4)The experiment of laser cutting magnesium alloy.Based on numerical simulation and theoretical analysis,Laser cutting of magnesium alloys under different laser power,cutting speed,focus position and auxiliary gas pressure was studied by experimental work.The cutting width,morphology,slag content,surface roughness and metallographic structure of laser cutting magnesium alloy were analyzed.The cutting quality wass the best at the laser power of 750 W,cutting speed of 27mm/s,focus positionof-2mm and gas pressure of 0.45 MPa.The research on laser cutting machine tools and laser cutting process parameters in this paper has good practical significance and application value for improving the quality of machine tools. |
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