Research On Asymmetry Cutting Of The Soda-lime Flat Glass Using Laser Induced Thermal-crack Propagation

With the acceleration of social digitized and the rapid development of automobile industry,a lot of flat panel displays,smart phones,LCD TVs,and the cars have entered the ordinary people's life.In the production process of these electronic products,the processing of the LCD screen,COVER LENS and the windshield wiper is an important part.Knife-wheel processing is still used in the cutting of flat glass,the processing edge quality is poorer,the yield is reduced greatly.The processing edge cutting with laser induced thermal-crack propagation(LITP)doesn't have any defects,which has the great practical significance to improve the yield of the product.The researchers pay more attention to the cutting mechanism of LITP symmetry cutting glass.However,in the actual processing,the asymmetrical cutting is more common,the control of cutting trajectory is an important indicator of the LITP asymmetrical cutting glass technology.This paper is research on the problems of the trajectory deviation with LITP asymmetrical cutting of the soda-lime flat glass and how to realize the closed curve shape cutting.According to the absorption characteristic of the soda-lime glass for 1064 nm wavelength laser,combined with Beer-Lambert's law,the truncated cone-shaped body heat source mathematical model of the laser was established.According to heat transfer theory,the finite element method was used to solve the temperature field distribution in the processing,which was verified by the infrared thermal imager to measure the temperature.According to the relationship between temperature field and stress strain in LITP cutting glass technology,combined with the thermal elastic mechanics theory,the stress field was solve by the sequential coupling heat transfer.Influences of laser processing parameters and defocus states on cutting different thickness flat glass was studied.The influence of the initial crack's size on the crack propagation was studied.These studies provided the basis for subsequent research.The mathematical model of material crack tip stress with the action of complex fracture modes was analyzed.The extended finite element method was used to added the influence of the crack into the simulated physical model,combined with the body heat source model,the stress field and state of crack propagation in asymmetrical cutting of the soda-lime flat glass were studied by simulation to show the mechanism of trajectory deviation.The temperture field simulation results and experimential research were performed with the effect on trajectory deviation about material symmetry and laser processing parameters.The reasonable parameter selection method was indicated to improve the quality of processing.For revising the trajectory deviation in the LITP asymmetric cutting of the soda-lime flat glass,the dual laser beam and low temperature gas cooled thchnologies were proposed.The influence of fixed laser and low temperature gas on the the temperature field and stress field distribution in the process of revising the trajectory deviation.The experomental system was established to obtain the optimum parameters of the trajectory revision.The simulation study of the crack propagation process with the optimum parameters was performed.The simulation and experimental results had proved that the two methods can revise the trajectory deviation successfully.For cutting of the closed curve shape with LITP,combined with the test process and test phenomenon,the model of closed curve shape with LITP had been established to find out the reason that the cutting is difficult to achieve.Through the arranged stress-release crack,the closed curve shape cutting with LITP can be realized.The acoustic emission was used to monitor the crack extension process of closed curve shape online.