The Simulation And Experimental Analysis Of Laser-controlled Thermal Stress Cutting Alumina Ceramic

Laser cutting is one of the most important application technologies in laser machining industry, and the laser processing of non-metallic materials has become the study object of many scholars. The laser-controlled thermal stress cutting induces and controls the crack propagation by using the thermal stress which is caused by the surface temperature field gradient in the laser cutting. And it is an effective manner to split the glass, ceramics and other brittle materials. Compared with the traditional diamond knife cutting and laser vaporization cutting, laser-controlled thermal stress cutting has many advantages such as smooth cutting surface, no loss of materials, small micro-cracks and so on.Under the support of the project of natural science foundation, the paper discusses the present research status and development of laser-controlled thermal stress cutting, analyses the mechanism of laser cutting of alumina ceramic, establishes a three-dimensional symmetric model of laser cutting, and study the effect of various cutting parameters on temperature field and thermal stress field. The concrete research content is as follows:Firstly, the paper analysis the crack propagation mechanism of laser-controlled thermal stress cutting based on brittle fracture theory, and establishes the three-dimensional symmetrical finite element model by using Ansys software. APDL programming language is adopted, and surface effect element surf152 is introduced to simulate the moving laser heat source and heat transfer model.The laser-controlled thermal stress cutting process of alumina ceramics is studied, the law of the temperature field distribution and thermal stress distribution is analyzed, and the relationships between the temperature field and stress field with the laser power, workpiece thickness and cutting speed are revealed. The normal stressσy of nodes which are located in the laser cutting path is experienced in the cutting process of "no stress-tensile stress-compressive stress-tensile stress-no stress" until the crack propagation. The earlier the crack initiates with greater tensile stress when the laser power becomes greater. Under the same conditions, the sooner the fracture happens and the maximum temperature drops with cutting speed increased.Based on the theoretical study, alumina ceramic substrates offered by Xi'an Electronic Technology Co., Ltd are adopted to do the laser-controlled thermal stress cutting experiment. Laser cutting machine is 50W continuous carbon dioxide laser which is offered by Shanghai Institute of Laser Technology. Meanwhile, verify the theoretical relationship between the cutting quality and laser power, workpiece thickness as well as cutting speed to provide practical optimization of cutting parameters based on the cutting experiment.Finally, the paper summarizes all the done work and views the study direction in future.