3D曲面玻璃热压加热工艺与数值模拟
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摘要
随着信息电子技术的发展,手机、电子配件等产品需求不断增加,3D曲面玻璃屏幕凭借诸多优势一度成为手机市场的宠儿。本文简述光学玻璃屏幕热弯成型过程,针对3D热弯机加热阶段热应力产生问题进行研究。采用福尔切尔方程模拟玻璃粘滞流动随温度变化关系,再根据玻璃在各温度点显现的不同状态拟定模压温度。基于Galerkin法建立玻璃材料导热方程和热应力本构方程,模拟仿真TiC-CrMo钢结硬质合金模具和光学玻璃温升过程并导出相应热应力变化曲线。分析玻璃屏幕在加热过程中各时间段产生热应力的原因,即:玻璃内外表面温度梯度不同引起热应力从而影响玻璃屏幕使用性能。针对分析结果提出六步加热控制优化方案。最后通过热弯机和TiC-CrMo刚结硬质合金模具进行实验,验证理论模型的正确性。
With the development of information electronic technology, the demand for mobile phone, electronic accessories and other products is increasing. 3D curved glass screen has become the favorite of the mobile phone market with many advantages. In this paper, the thermal bending technology of optical glass screen is briefly described, and the thermal stress generation in the heating stage of 3D thermal bending machine is studied. The Focell equation is used to simulate the relationship between the viscosity flow and the temperature of the glass, and the heating temperature is determined according to the different states of the glass at each temperature point. The thermal conductivity equation and thermal stress constitutive equation of glass material were established by Galerkin method. The temperature rising procecess of TiC-CrMo rigid cemented carbide mould and optical glass is simulated, and the thermal stress change curve of glass screen is derived. The reason of thermal stress in each time period of glass screen is analyzed: the thermal stress caused by temperature gradient on the inside and outside surface of glass will affect the performance of glass screen. Based on the analysis results, a six-step heating control optimization scheme is proposed. Finally, the validity of the theoretical model is verified by the experiments carried out by hot bending machine and TiC-CrMo rigid cemented carbide die.
With the development of information electronic technology, the demand for mobile phone, electronic accessories and other products is increasing. 3D curved glass screen has become the favorite of the mobile phone market with many advantages. In this paper, the thermal bending technology of optical glass screen is briefly described, and the thermal stress generation in the heating stage of 3D thermal bending machine is studied. The Focell equation is used to simulate the relationship between the viscosity flow and the temperature of the glass, and the heating temperature is determined according to the different states of the glass at each temperature point. The thermal conductivity equation and thermal stress constitutive equation of glass material were established by Galerkin method. The temperature rising procecess of TiC-CrMo rigid cemented carbide mould and optical glass is simulated, and the thermal stress change curve of glass screen is derived. The reason of thermal stress in each time period of glass screen is analyzed: the thermal stress caused by temperature gradient on the inside and outside surface of glass will affect the performance of glass screen. Based on the analysis results, a six-step heating control optimization scheme is proposed. Finally, the validity of the theoretical model is verified by the experiments carried out by hot bending machine and TiC-CrMo rigid cemented carbide die.
引文
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[14]肖逸锋,周年丰,匡雯慧,等.硬质相成分对WC-TiC钢结硬质合金组织及力学性能的影响[J].材料热处理学报,2017,38(06):42-48.Xiao Yifeng,Anniversary Feng,Kuang Wenhui et al.Effect of hard Phase composition on microstructure and mechanical properties of WC-TiC steel-bonded cemented carbide[J].Transcaction of Materials and Heat Treatment,2017:38(06):42-48.
[15]卢景红.透镜阵列热压加压阶段型腔填充机理和残余应力的研究[D].复旦大学,2014.Lu Jinghong.Study on filling mechanism and residual stress of lens array during hot-pressing and compression stage[D].Fudan University,2014.
[16]李国平,罗丰华,颜练武,等.预合金粉为黏结剂的TiC钢结硬质合金组织演变与强韧性研究[J].硬质合金,2018,35(02):108-115.Li Guoping,Luo Fenghua,Yan Qianwu,et al.Microstructure evolution and strength and toughness of TiC steel-bonded cemented Carbide with prealloyed Powder as binder[J].Cemented Carbide,2018,35(02):108-115.
[2]LI G,Jinn J T,Wu W T,et al.Recent development and applications of three-dimension finite element modeling in bulk forming processes[J].Journal of Materials Processing Technology,2001,113(1):40-45.
[3]Jain A,Firestone G,Yi A Y.Viscosity measurement by cylindrical compression for numerical modeling of precision lens molding process[J].Journal of the American Ceramic Society,2005,88(9):2409-2414.
[4]Jain A.Experimental study and numerical analysis of compression molding process for manufacturing precision aspherical glass lenses[D].Columbus:The Ohio State University,2006:7-10.
[5]Huamin Zhou,Tie Geng and Dequn Li.Cooling simulation of the pressing process in TV panel production[J].Simulation Modelling Practice and Theory,2005,13(3):273-285.
[6]苏恒迪.玻壳模具温度场及变形的边界元分析[D].武汉:华中科技大学,2006.Su Hengdi.Boundary element analysis of temperature field and deformation of glass shell mould[D].Wuhan:Huazhong University of Science and Technology,2006.
[7]邵宏根.浮法玻璃成型的数值模拟与实验研究[D].燕山大学,2004.Shao Honggen.Numerical simulation and experimental study on float glass molding[D].Hebei:Yanshan University,2004.
[8]Sébastien Grégoire,JoséM.A.César de Sá,Philippe Moreau,Dominique Lochegnies.Modelling of heat transfer at glass/mould interface in press and blow forming processes[J].Computers and Structures,200685(15):2409-2414.
[9]Huamin Zhou,Dequn Li.Mold cooling simulation of the pressing process in TV panel production[J].Simulation Modelling Practice and Theory,2004,13(3):19-37.
[10]Yi A,Jain A.Compression molding of aspherical glass lenses-a combined experimental and numerical analysis[J].Journal of the American Ceramic Society,2005,88(3):579-586.
[11]曾召.硫系红外玻璃的微晶化及精密模压成型[D].陕西:西安工业大学,2011.Zeng Zhao.Crystallization and precision molding of sulphur infrared glass[D].Xi'an:Xi'an Technological University,2011.
[12]陶文铨.数值传热学[M].西安:西安交通大学出版社,2001.Tao Wenquan.Numerical heat transfer[M].Xi'an:Xi'an Jiaotong University Press,2001.
[13]朱科军.光学玻璃透镜模压成形的数值仿真和实验研究[D].长沙:湖南大学,2013.Zhu Kejun.Numerical simulation and experimental study on molding of optical glass lens[D].Changsha:Hunan University,2013.
[14]肖逸锋,周年丰,匡雯慧,等.硬质相成分对WC-TiC钢结硬质合金组织及力学性能的影响[J].材料热处理学报,2017,38(06):42-48.Xiao Yifeng,Anniversary Feng,Kuang Wenhui et al.Effect of hard Phase composition on microstructure and mechanical properties of WC-TiC steel-bonded cemented carbide[J].Transcaction of Materials and Heat Treatment,2017:38(06):42-48.
[15]卢景红.透镜阵列热压加压阶段型腔填充机理和残余应力的研究[D].复旦大学,2014.Lu Jinghong.Study on filling mechanism and residual stress of lens array during hot-pressing and compression stage[D].Fudan University,2014.
[16]李国平,罗丰华,颜练武,等.预合金粉为黏结剂的TiC钢结硬质合金组织演变与强韧性研究[J].硬质合金,2018,35(02):108-115.Li Guoping,Luo Fenghua,Yan Qianwu,et al.Microstructure evolution and strength and toughness of TiC steel-bonded cemented Carbide with prealloyed Powder as binder[J].Cemented Carbide,2018,35(02):108-115.