超精密机床垂直轴卸荷系统设计及其静动态特性分析
发布时间：2018-09-12 08:42
【摘要】：超精密机床垂直轴可以拓展机床的加工方式,提升机床的加工能力,是超精密多轴联动机床的重要组成部件。而现有超精密机床垂直轴的卸荷系统存在摩擦系数大的缺点,严重影响到超精密机床垂直轴的定位精度和加工稳定性。为解决上述问题,本文为现有超精密机床垂直轴设计了以气体润滑低摩擦气缸为核心部件的卸荷系统,并对其气体静压径向轴承的静态性能,以及卸荷系统的静动态特性进行了研究与分析。本文具体的研究内容有:基于低摩擦的设计原则,以气体静压润滑为理论基础,并结合典型低摩擦气缸的结构,设计了可以实现气体润滑环节与卸荷环节独立供气的全工况超精密机床垂直轴卸荷系统。通过推导Reynolds方程的一般表达式,建立了气体静压径向轴承静态特性数学模型,并由此完成了对气体静压轴承各尺寸参数的选取,计算了轴承承载力、静刚度和耗气量等静态性能参数。完成了卸荷系统配套气动回路的设计,使卸荷系统能够在气体润滑的状态下完成卸荷任务。在卸荷系统总体结构设计的基础上,通过仿真软件Fluent对卸荷系统内的气体静压径向轴承的静态性能进行了分析;研究了气体静压径向轴承上气体压强分布对轴承承载力和静刚度等静态性能的影响;研究了偏心率、轴承径向间隙和供气压力等参数对轴承静态性能的影响规律,并确定了各参数的最佳取值。基于卸荷系统的有限元模型,对活塞杆不同姿态下的卸荷系统进行了结构静力学分析,并完成了卸荷系统的弯矩敏感性分析。对活塞杆不同位置下的卸荷系统进行了模态特性分析,分析了活塞杆姿态变化对卸荷系统各阶固有频率与模态振型的影响。对卸荷系统的气体润滑低摩擦气缸进行了性能试验,得到了其静摩擦力随供气压力与负载质量变化的规律。
[Abstract]:The vertical axis of ultra-precision machine tool can expand the machining mode of machine tool and improve the machining ability of machine tool. It is an important component of ultra-precision multi-axis machine tool. However, the present unloading system of vertical axis of ultra-precision machine tool has the disadvantage of large friction coefficient, which seriously affects the positioning accuracy and machining stability of vertical axis of ultra-precision machine tool. In order to solve the above problems, a unloading system with gas lubricated low friction cylinder as the core component is designed for the vertical axis of the existing ultra-precision machine tool, and the static performance of the gas hydrostatic radial bearing is also studied. The static and dynamic characteristics of unloading system are studied and analyzed. The specific research contents of this paper are as follows: based on the design principle of low friction, based on the theory of gas hydrostatic lubrication, and combined with the structure of typical low friction cylinder, The vertical axis unloading system of ultra-precision machine tool under all working conditions is designed, which can realize the independent gas supply between gas lubrication and unloading. By deducing the general expression of Reynolds equation, the mathematical model of static characteristic of aerostatic radial bearing is established, and the parameters of each dimension of gas hydrostatic bearing are selected, and the bearing capacity is calculated. Static performance parameters such as static stiffness and air consumption. The design of the complete pneumatic loop of the unloading system is completed, which enables the unloading system to complete the unloading task under the condition of gas lubrication. Based on the overall structure design of the unloading system, the static performance of the aerostatic radial bearing in the unloading system is analyzed by the simulation software Fluent. The influence of gas pressure distribution on bearing capacity and static stiffness is studied, and the influence of eccentricity, radial clearance and air supply pressure on static performance of bearing is studied. The optimum value of each parameter is determined. Based on the finite element model of the unloading system, the structural statics analysis of the unloading system with different piston rod attitude is carried out, and the moment sensitivity analysis of the unloading system is completed. The modal characteristics of the unloading system with different piston rod positions are analyzed, and the influence of the piston rod attitude change on the natural frequencies and modal modes of the unloading system is analyzed. The static friction of the gas lubricated low friction cylinder of unloading system is tested, and the variation of static friction force with the air supply pressure and load mass is obtained.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG502.1
，
本文编号：2238493
[Abstract]:The vertical axis of ultra-precision machine tool can expand the machining mode of machine tool and improve the machining ability of machine tool. It is an important component of ultra-precision multi-axis machine tool. However, the present unloading system of vertical axis of ultra-precision machine tool has the disadvantage of large friction coefficient, which seriously affects the positioning accuracy and machining stability of vertical axis of ultra-precision machine tool. In order to solve the above problems, a unloading system with gas lubricated low friction cylinder as the core component is designed for the vertical axis of the existing ultra-precision machine tool, and the static performance of the gas hydrostatic radial bearing is also studied. The static and dynamic characteristics of unloading system are studied and analyzed. The specific research contents of this paper are as follows: based on the design principle of low friction, based on the theory of gas hydrostatic lubrication, and combined with the structure of typical low friction cylinder, The vertical axis unloading system of ultra-precision machine tool under all working conditions is designed, which can realize the independent gas supply between gas lubrication and unloading. By deducing the general expression of Reynolds equation, the mathematical model of static characteristic of aerostatic radial bearing is established, and the parameters of each dimension of gas hydrostatic bearing are selected, and the bearing capacity is calculated. Static performance parameters such as static stiffness and air consumption. The design of the complete pneumatic loop of the unloading system is completed, which enables the unloading system to complete the unloading task under the condition of gas lubrication. Based on the overall structure design of the unloading system, the static performance of the aerostatic radial bearing in the unloading system is analyzed by the simulation software Fluent. The influence of gas pressure distribution on bearing capacity and static stiffness is studied, and the influence of eccentricity, radial clearance and air supply pressure on static performance of bearing is studied. The optimum value of each parameter is determined. Based on the finite element model of the unloading system, the structural statics analysis of the unloading system with different piston rod attitude is carried out, and the moment sensitivity analysis of the unloading system is completed. The modal characteristics of the unloading system with different piston rod positions are analyzed, and the influence of the piston rod attitude change on the natural frequencies and modal modes of the unloading system is analyzed. The static friction of the gas lubricated low friction cylinder of unloading system is tested, and the variation of static friction force with the air supply pressure and load mass is obtained.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG502.1
，
本文编号：2238493
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