| Engineering ceramics is characterized by low density,high hardness,corrosion resistance,high temperature resistance and self-lubrication.Because of its inherent excellent characteristics,it has been widely used in aerospace,automotive,petrochemical,mechanical processing and more and more industries.However,the high hardness and low fracture toughness of engineering ceramics make it difficult to process parts.Laser-assisted thermal cutting can solve this problem.The principle of laser-assisted thermal cutting is to soften ceramics by laser irradiation,and then remove the softening part by high temperature-resistant cutting tools.Laser assisted thermal cutting has many advantages,such as green and high efficiency of laser processing,large processing space and high efficiency of turning.In this paper,zirconia ceramics were selected as the research object,and the laser assisted thermal processing technology of zirconia ceramics was studied.This paper mainly completes the following research work:Firstly,the mathematical model of temperature field in laser assisted thermal cutting is established,which provides theoretical basis for the simulation of temperature field in laser assisted thermal cutting of zirconia ceramics.Finally,two methods of solving temperature field model are given.Secondly,the workpiece temperature field in laser assisted hot cutting is simulated and analyzed by Workbench,and the influence of various factors on the workpiece temperature field is explored through single factor simulation test.Among them,the increase of laser power has the most significant effect on the maximum temperature of the workpiece surface;with the increase of laser spot radius,the width of heat transfer along the axis of the workpiece surface temperature increases;with the increase of rotational speed,the influence on the heat transfer depth along the radial direction of the workpiece gradually decreases.Thirdly,a test platform for laser assisted hot cutting is built,and the components of each part are introduced.The range of processing parameters of laser assisted hot cutting is selected,and the orthogonal experiment of four factors and three levels is completed.Finally,the results of orthogonal experiment are analyzed.The results of variance and range analysis of the orthogonal test results of workpiece surface roughness show that the most significant factors affecting surface roughness are laser power and knife feed rate,and the order of influence degree on surface roughness from large to small is laser power,knife feed rate and spindle speed.The results of variance and range analysis of the orthogonal test results of tool wear show that only laser power is the most significant factor affecting tool wear,and laser power,feed speed,backbite and spindling speed are the most important factors affecting tool wear.The theoretical chip removal is 2.6 time as much as the actual chip removal,and the minimum is 1.1 time.The chips obtained by laser assisted thermal cutting are long and narrow with certain curl.The length of the long and narrow chips is between 200 and 300 um.The chips produced by nonlaser assisted thermal cutting are irregular and less than 50 um.SEM observation on the surface of the workpiece machined by laser assisted hot cutting shows that the surface is smooth and there are a large number of melting smear areas.It can be inferred that the material removal mechanism is mainly plastic removal. |
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