摘要
针对节流材料变形导致的晶圆减薄机中磨削主轴性能下降问题,研究了石墨材料变形对多孔质推力轴承静态特性的影响规律。基于Darcy定律、Navier-Stokes方程(N-S方程)、流量平衡方程建立多孔质推力轴承静特性分析模型,并耦合轴承间隙内的非均布气膜压力建立多孔质节流器的变形模型。采用数值方法求解流固耦合作用下多孔质推力轴承承载面的变形分布和气膜压力分布,分析了多孔质石墨厚度和弹性模量对无量纲气膜压力和变形量的影响规律,揭示了气膜压力与多孔质石墨变形之间的相互作用机制。研究结果表明,轴承间隙越小、供气压力和渗透系数越高,多孔质石墨的变形量越大,承载力降低的幅度和体积流量的增加量越大,材料变形对轴承静态特性的影响显著且不可忽略。多孔质石墨越薄、弹性模量越低,材料变形对轴承静态特性的影响越显著,增加多孔质石墨的厚度和弹性模量可以减小材料变形对轴承静态特性的影响。为了减小材料变形对轴承静态特性的影响,轴承间隙和供气压力宜取20μm和0.5 MPa,多孔质石墨的渗透系数和厚度宜分别取5×10^(-9)mm^(2)和4 mm,弹性模量不宜低于20 GPa。该研究为晶圆减薄质量及空气静压磨削主轴性能的提升提供一定的理论支撑。
To address the performance degradation of grinding spindles in wafer-grinding machines caused by the deformation of the restrictor material,the effect of graphite material deformation on the static characteristics of porous thrust bearings was investigated.Based on Darcy's law,the Navier-Stokes equation,and flow balance equations,a static characteristic analysis model of a porous thrust bearing was established,and a deformation model of a porous restrictor coupled with non-uniform gas-film pressure in the bearing clearance was established.Using the established numerical model,the effects of the thickness and elastic modulus of porous graphite on the dimensionless gas-film pressure and deformation on the bearing surface of a porous thrust bearing under the effect of fluid-solid interactions were investigated,which revealed the interaction mechanism between the gas-film pressure and the deformation of porous graphite.The results indicate that as the porous graphite becomes thinner,its throttling ability diminishes,thus resulting in increased gas-film pressure within the bearing clearance and greater deformation of the porous graphite.Consequently,this deformation increases the gas-film thickness,thus causing the gas-film pressure to reduce significantly.The deformation of porous materials exhibits an inverse relationship with the elastic modulus and progressively diminishes as the elastic modulus increases.Therefore,the increasing elastic modulus of the porous graphite results in a smaller increase in the thickness of the gas film caused by deformation,thus resulting in a lower reduction in the gas-film pressure and an asymptotic approach to the non-deformation solution.By calculating the load-carrying capacity and volume flow rate of bearings with different porous-graphite thicknesses and elastic moduli,the effects of the material properties of porous graphite and the bearing operating parameters on the static characteristics of porous thrust bearings under the effect of fluid-solid interactions were investigated.The results indicate that as the bearing clearance decreases and the gas supply pressure increases,the deformation of the porous graphite increases,thus causing the load-carrying capacity to decrease significantly and the volume flow rate to increase considerably.Additionally,material deformation imposes a substantial and non-negligible effect on the static characteristics of bearings.To minimize the effect of material deformation on the static characteristics of the bearing,the optimal bearing clearance and gas supply pressure should be maintained at 20μm and 0.5 MPa,respectively.The higher the permeability coefficient,the greater is the reduction in the bearing capacity and the increase in the volume flow rate caused by the deformation of porous graphite.Conversely,a reduction in the permeability coefficient corresponds to a diminished effect of material deformation on the static characteristics.Based on theoretical analysis,5×10^(-9)mm^(2) is identified as the optimal permeability coefficient.The thinner the porous graphite,the greater is the reduction in the bearing capacity and the increase in the volume flow rate of the bearing.However,an excessively thick porous graphite limits the improvement in the bearing capacity.Therefore,controlling the enhancement to the porous-graphite thickness effectively mitigates the effect of material deformation on the bearing static characteristics.A comprehensive evaluation of the static performance parameters yields an optimal thickness of 4 mm.Under a lower elastic modulus,the porous-graphite deformation significantly affects the static characteristics.As the elastic modulus of porous graphite increases,the effect of material deformation on the static characteristics of the bearings decreases.To prevent the static performance of porous thrust bearings from being degraded substantially,the elastic modulus of porous-graphite materials should be maintained at a minimum of 20 GPa.This study provides theoretical support for improving wafer-grinding quality and aerostatic grinding-spindle performance.
作者
石明辉
张国龙
杜鹏
陈江义
胡洪洋
SHI Minghui;ZHANG Guolong;DU Peng;CHEN Jiangyi;HU Hongyang(College of Mechanical and Power Engineering,Zhengzhou University,Zhengzhou 450001,China;AVIC Xinxiang Aviation Industry(Group)Co.,Ltd.,Xinxiang 453000,China)
出处
《中国表面工程》
北大核心
2025年第5期157-170,共14页
China Surface Engineering
基金
国家自然科学基金(52205222)
中国博士后科学基金(2024M751278)
河南省青年人才托举工程(2024HYTP017)。
关键词
晶圆减薄
空气静压主轴
多孔质推力轴承
流固耦合
静态特性
wafer grinding
aerostatic spindle
porous thrust bearing
fluid-solid interaction
static characteristics
