Study On Glass Substrate Deformation In Air Flotation Transmission System

With the continuous upgrading of the production line of liquid crystal glass substrate,the size of the glass substrate is getting larger and larger,and the thickness becomes thinner and thinner.Starting from the 7th generation line the air bearing support transmission gradually replaced the roller support transmission and became a key technology in the optical automatic detection of the new generation of liquid crystal glass substrates.In the process of on-line detection of LCD glass substrates,there is a strict requirement on the deformation of the glass plate in the vertical direction.This paper is mainly studied in the following two aspects,first of all,theoretical analysis of deformation of liquid crystal glass plate supported by air floatation is carried out,and then the effect of parameters of air floating platform on deformation is studied.In this paper,the deformation of liquid crystal glass plate under air bearing is theoretically analyzed based on the theory of small deflection of elastic thin plate and fluid lubrication theory,and the maximum deflection formula of liquid crystal glass plate under blowing and sucking nozzles is deduced.By analyzing the glass substrate unit,it can be seen that the maximum deflection occurs at the center of the glass substrate unit and is proportional to the fourth power of the capillary arrangement spacing.The simulation of the air bearing support system of the LCD glass substrate was carried out by Fluent,and the load distribution under different nozzle hole pitches and the accurate value of the load at the maximum displacement of the glass substrate were obtained.Considering the maximum displacement requirement of the glass plate,pressure distribution on the gas film surface,and economy,the lateral spacing range of the through holes on the film unit can be obtained.On the basis of theoretical research,the nozzle arrangement parameters of the LCD glass substrate optical inspection instrument transmitted by air bearing are given.The reasonable spacing of nozzles should be between 20~25mm.The Workbench fluid-solid coupling simulation software is used to model and simulate the single glass substrate supported by the air floatation platform.The effects of air supply pressure(positive pressure and negative pressure),capillary length,and gas cavity length on the deformation of the glass substrate are studied in detail.Considering the pressure distribution and mass flow of the air film surface under different conditions,the air flotation platform is optimized.A new type of gas supply model was designed,that is,to increase the pressure of the negativepressure hole in the longitudinal center.The simulation results show that both the deformation of the glass substrate and the pressure distribution on the film surface are significantly better than the original gas supply mode.Based on the theoretical research and simulation analysis,the structure of the flotation platform is optimized,and trial prototype.Through the detection of the air bearing support system of the prototype of the LCD automatic optical detector,it can be seen that when the equipment is operating stably,the deformation of the glass substrate and the stability of the gas film pressure meet the requirements of the project.