【作者】 张成印；

【导师】 刘赵淼；

【作者基本信息】 北京工业大学 ， 力学， 2011， 硕士

【摘要】 现代科学技术的日益进步给航空航天技术、船舶工业、汽车工业以及高精密仪器等领域带来了巨大的发展也对机床的加工能力提出了越来越高的要求。液体静压支承系统因其承载性能好、摩擦阻力小、使用寿命长、抗震性能好、精度高、稳定性好等优点,在现代高精度数控机床中得到了广泛的应用,并逐渐成为机床的核心部件。液体静压支承系统承载性能的优劣直接影响到整个机床运行的加工精度、可靠性、寿命和经济指标。本文采用CFD软件CFD-ACE+对高精度数控机床的液体静压转台系统中油腔的流场和承载特性进行了研究。具体研究内容包括:(1)研究了不同因素对中心入口油腔中流场分布的影响。在静态下,粘度增大会减少涡旋数目,增强油腔承载稳定性;入口速度、油腔深度和入口半径增加会增大涡旋数目,降低油腔承载稳定性;壁面运动会削弱入口喷射的影响,造成入口附近的涡旋逐渐减弱直至消失,而在封油边处会出现涡旋;(2)研究了偏心入口油腔的静动态承载特性。静态下,偏心入口油腔的压强小于中心入口油腔;转台转动情况下,壁面运动沿x轴正向和y轴正向运动油腔压强值高于沿x轴负向和y轴负向运动的油腔压强;在偏载的楔形油膜中,油腔压强在壁面运动方向与油膜倾斜方向相同时随着壁面速度增加而增大,反向时则随着壁面速度增加而减小,垂直时则不随壁面运动速度增加而变化;(3)利用流固耦合方法研究了变载情况下油腔的承载特性。在周期载荷情况下,油腔压强和交界面位移出现相同的周期性变化,但到达波峰的时间与载荷相比存在延迟。油腔初始压强与加载后载荷差值减小,油腔压强和交界面在加载后能更快达到稳定,交界面距离初始位置距离减小。研究结果表明,在应用于小型转台的中心入口油腔中,油腔几何尺寸变化、润滑油粘度以及壁面运动都会对油腔中的涡旋分布产生影响,而涡旋对壁面压强有很大影响,从而进一步影响油腔承载的稳定性;在应用于大型转台的偏心入口油腔中,壁面的不同运动速度会对油腔承载能力大小造成影响,而当壁面相对于油腔的运动方向不同时,其对压强造成的影响程度不同;当油膜呈楔形时,壁面在不同运动方向情况下,其运动速度变化对油腔压强造成的影响趋势不同;在周期性变化载荷作用下,油腔压强和交界面位移也呈周期性变化。更多还原

【Abstract】 The increasingly development of technological drives the development of aerospace technology, shipbuilding industry, automobile industry and highly sophisticated device. All these are taking higher manufacturing requirements to the machine tools. With great carrying performance, low frictional resistance, long service life, high aseismic behavior, high precision and well stability, hydrostatic support system has became the core component in high-precision CNC machine tools. The carrying ability of the hydrostatic support system will directly affect the reliability of operation, life and economic indicators.The flow field and the bearing capability of oil cavity in high-precision CNC machine tools’hydrostatic turntable system were studied by the CFD software CFD-ACE+. Results are in the following:(1) The influences of different factors on the flow field of center entrance oil cavity were studied. In static state, the number of vortex will reduce and the stability of the oil cavity will be enhanced with the increasing of lubricant viscosity. However, the increase of inlet speed, oil cavity’s depth and inlet radius will lead to the vortex’s effect increasing and reduce the stability of oil cavity. The increase of hydrostatic turntable’s speed would directly lead to the vortexes appearing nearby the oil sealing edge and the vortexes near the inlet gradually being weakened until disappearing.(2) The static and dynamic carrying characteristics of eccentric entrance oil cavity were studied. In static state, the pressure of centre entrance oil cavity is higher than the eccentric entrance oil cavity. With the condition of turntable rotating, the oil cavity pressure when the surface move forward x axis and y axis is higher than the pressure with surface moving backward x axis and y axis. With the condition of cuneiform film caused by the offset load, the oil cavity pressure will increase with the surface’s speed increasing when the surface’s motion direction is the same as the surface’s inclination direction, but the pressure will decrease with the surface’s speed increasing when the surface’s motion direction is contrary to the surface’s inclination direction, moreover, the surface’s speed will not have influence to the oil cavity pressure when the surface’s motion direction is vertical to the surface’s inclination direction.(3) The carrying characteristics of oil cavity with variable load were studied by fluid-solid interaction method. Under the repeated load, the changes of oil cavity pressure and the interface moving are periodic which are same as the load, but the time to reach peak is delayed to the load. When the difference between load and initial pressure of oil cavity decrease, it’s easier to achieve stability for the oil cavity pressure and the interface, and the distance from initial position of the interface decrease.In the whole, about the studying of center entrance oil cavity, the geometry, viscosity and surface moving will affect the vortexes in the oil cavity, and the vortexes can affect the surface pressure and the carrying stability. About the studying of eccentric entrance oil cavity, the surface’s motion speed and direction will affect the distribution of pressure. When the oil film is cuneiform, different motion directions of surface have different effect trends to the pressure. With the effect of repeated load, the oil cavity pressure and interface moving also show a periodic change.更多还原