The Research Of Cutting LCD-glass With Thermal Cracking Method Based On Thermal Weight Function Technology

LCD-glass substrate is the key component of the LCD flat panel display device. Now it has been widely used in monitors, LCD-TV, laptops, communication equipment, etc. The size of original LCD glass substrate is very big,but the size of them application in screen is relatively small. So LCD involves to the cutting of LCD-glass plate during the production process. It also needs the higher cutting quality and efficiency. The cutting quality directly affects the liquid crystal display work time and display quality. The traditional mechanical cutting method for cutting quality is poorer, especially in the curve cutting, processing is complicate, costly. But thermal-cracking method can avoid inadequate of mechanical cutting method, it is not only make the LCD-glass cutting section straight, but also can through numerical control programming to achieve complex curve cutting and without needing secondary processing, the cutting quality and cutting efficiency can be greatly improved. So research the thermal-cracking method of LCD-glass cutting technology has some practical engineering significance.Based on the analysis summary of domestic and foreign scholars in laser thermal-cracking method cutting technology, the paper uses thermal weight function technology(TWFT) study the thermal-cracking method of LCD glass. TWFT uses the temperature and the thermal weight function(TWF) product’s integral to calculate the crack tip’s stress intensity factor. TWF is only dependent on the model’s geometry and the boundary conditions, but it is independent of load type and time. So it avoids each instant boundary element analysis or finite element analysis, it greatly simplifies the calculation process and greatly improves the computational efficiency. This paper mainly includes the following contents:Firstly, from the basic theory of heat transfer and thermal elastic mechanics and fracture mechanics to analysis the interaction between laser and LCD-glass, crack extension mechanism and propagation conditions during CO2 laser cutting process.Secondly, the basic principle of thermal weight function method for crack tip’s stress intensity factor is introduced, which leads to thermal weight function method. Then its numerical algorithm is derived and simplified. And the steps of application development and the finite element calculating method of TWF and the partial derivative, Numerical integration calculation method in the development process are researched. the paper uses FORTRAN language develop I 、 II mixed-mode crack’s thermal weight function method of program system in the ABAQUS environment.Thirdly, this paper uses the finite element software ABAQUS simulate the laser cutting process to obtain the cutting process’ temperature field distribution. And then the influences of laser cutting parameters on the temperature field were researched, so as to provide a basis for selecting reasonable laser cutting parameters.Fourthly, research the mechanism of thermal cracking method by using TWFT to calculate the crack tip’s stress intensity factor during the laser cutting process, And then using the technology to study the influence of laser parameters, the length of the crack, the size of LCD-glass plate, the initial temperature and boundary conditions on the laser cutting.Finally, by the orthogonal experiment method, the paper studies the effect of laser parameters on cutting ability. Cracking method is verified through the experiment in the process of cutting liquid crystal glass, and the experiment also verifies the selection of laser parameters on the effect of crack propagation during the processing of laser cutting LCD-glass experiment.