Research on the Error Averaging Effect in A Rolling Guide Pair

By studying the e ects of geometric precision on kinematic accuracy, an error mapping model has been established, based on the hypothesis that a motion pair and its installation surface are rigid. However, when using this assumption,there is a significant error induced in high-precision computer numerical control(CNC) machine tools as compared with reality. One of the most important reasons for this error is failing to consider the error averaging e ect of motion pair elements. Therefore, this work examines a high-precision horizontal machining center as its research object, and analyzes the error averaging mechanism of a rolling guide pair under a deformation of the rolling elements. The carriage bearing forces caused by guideway straightness errors are obtained by constructing a geometric error model of a single carriage. The relationship between guideway straightness errors and carriage bearing forces is described by a transfer function in the spatial frequency domain, and its characteristics are analyzed. It quantifies the so-called error averaging e ect of the rolling guide system and, on this basis, a static model for four carriages is established to reflect the error averaging e ect of the rolling guide pair on the position and orientation errors of the motion pair. In addition, it is found that the wavelengths and phase di erences of guideway errors a ect this error averaging mechanism, but the amplitude and preload have little influence thereon. The experiment result shows that the kinematic straightness errors in the x-and y-directions were approximately 1/3 to 1/2 of the guideway straightness errors in the corresponding directions. The results can be used to guide the precision design and assembly of machine tools.

基于等刚度的滚动直线导轨副过渡曲线设计

滚动直线导轨副作为高精度导向进给机构,其振动的控制一直是研究的重点。通常采用增加滚动直线导轨副预载荷的方法,来改善滚动直线导轨副的减振性能,提高其刚度。然而实践表明,这种方法不但会降低整个导轨副的工作寿命,且减振效果并不佳。基于滚珠在循环过程中垂直刚度和倾斜刚度各自相等的假设情况下,提出了改善滚动直线导轨副减振性能的过渡曲线设计。利用降低滚珠进出承载区振动的基本条件,构建起设计滑块体两端部过渡曲线的数学解析模型,利用最小二乘法根据各控制点拟合出导轨副的过渡曲线。并通过试验验证了该设计方法减振效果的有效性。

罗茨泵理论输出流量无脉动的双转子副结构方案

为实现罗茨转子泵任意转速下理论输出流量的无脉动,基于摆线转子泵理论输出流量所具有的正弦函数平方特性,由4个相同的直叶摆线转子通过轴向的错位与间隔装配所形成的双转子副,构建出具有正弦函数平方特性和余弦函数平方特性的两股输出流量,及其合流为无脉动的定值理论输出流量。结果表明:圆摆线是实现定值理论输出流量即无脉动的唯一选择,2直叶、0.25滚径比和45°轴向错位角能实现2.25无量纲定值理论输出流量的最大化;2直叶摆线轮廓构造简单易加工,无余隙且容积利用率高等。

保证滑块精度一致性的加工工艺改进

面向产品专业化、批量化生产的需求,对影响滑块加工精度一致性的主要因素进行了系统研究,有针对性地对现有工艺进行改进,提高了滑块加工精度的一致性。最后,以大连机床集团的TD500A钻削中心配套的滑块产品为应用案例,对用传统方法及改善一致性研究成果加工的滑块各项精度指标进行对比,验证了所提出的改善滑块的一致性方法是有效的。此外,还对用原工艺和新工艺生产的滑块组装了20套导轨副,并对其批量精度、噪音、拖动力波动及装配效率等方面进行了对比分析。

基于刚度组集的混联机床的静刚度分析与优化

为了深入研究基于冗余驱动并联机构的混联机床的静刚度,提出一种建立整机刚度模型的方法,这种方法考虑了滚动直线导轨副和轴承的变形。根据刚度组集原理建立整机刚度矩阵,得到整机静刚度分布情况,并讨论了滚动直线导轨对整机静刚度的影响,针对机床薄弱环节,进行结构优化。结果表明:在一定工作空间内,整机x、y、z方向静刚度具有对称性,z向刚度最好,x向刚度最差。滚动直线导轨副对整机刚度影响较大。通过改进某些部件结构提高了整机x向刚度,为此类机床设计和优化提供了理论分析依据。