基于遗传算法的机床主轴动态特性优化设计

机床主轴的设计除了要考虑其强度和刚度外,尚须考虑其动态特性。机床主轴的动态特性设计可归结为特征值反问题的求解。本文研究了基于人工神经网络和遗传算法的机床主轴动态特性结构优化设计的求解方法,利用人工神经网络实现机床主轴动态特性的近似分析,借助遗传算法实现给定固有频率下的最小重量设计。计算结果表明了该方法的有效性。     

采用粘度可控高水基液润滑的高速动静压陶瓷滑动轴承主轴设计

高速主轴作为高速高精密加工机床的关键技术,直接决定着机床的各项工作性能.文中提出一种对粘度一轴承间隙寻优,从而实现主轴高性能的高速高精密主轴设计方法,并设计出新型绿色、粘度可控的高水基液作为润滑剂,随后通过采用动静压陶瓷滑动轴承的高速主轴热弹流数值计算,确定了润滑剂粘度及主轴系统相关结构参数,最终完成了该高速主轴的结构设计.     

电主轴助力高精高速高效加工——我国高性能机床主轴技术现状分析

高性能机床主轴概述 机床主轴是机床的核心部件,其功能是带动刀具（砂轮）或工件旋转,实现高速精密加工。随着现代工业对机床加工精度和加工效率要求的不断提高,机床对主轴性能的要求也越来越高,传统的高速主轴概念已难以充分描述机床主轴的技术内涵。高性能机床主轴是指在满足加工精度和加工效率的前提下,速度、精度、刚度、功率、转矩匹配特性好,可靠性高,性能价格比高的机床主轴。     

粒子群算法在机床结构优化设计中的应用

首先引入了粒子群算法(PSO)的简介,然后根据该算法在MATLAB中开发了PSO工具箱。最后根据机床主轴优化设计的实例采用PSO算法,实现了对机床主轴结构的优化设计。     

基于竞选算法的机床主轴结构优化设计

竞选算法是一种具有并行能力的启发式优化算法,其搜索机制模拟竞选活动中对支持率的追求动机,将其应用于机床主轴的结构优化设计,并以一个实例分析了设计全过程。首先根据在满足各种约束条件下,使机床主轴刚度最好和材料最省的要求,建立了机床主轴结构优化设计的数学模型,应用竞选算法对问题进行了求解,得到了结构优化设计方案。结果表明,竞选算法在机械优化设计中具有实用性和可行性。     

关于高速主轴前端密封结构形式的研究

主轴是机床的心脏,作为主要功能部件其性能直接决定机床的整体的使用情况.主轴的第一道防线就是前端密封结构,大流量冷却及加工尘屑极易污染主轴及主轴轴承,所以主轴部件设计过程中需重点考虑主轴前端密封结构设计及选用.重点介绍了根据机床的结构及加工工况不同,来选用主轴结构类型及其主轴前端密封的结构.     

机床两支承主轴部件静刚度的分析与计算

机床主轴部件的重要性,在于它是执行件,它直接带动工件或刀具(砂轮)参加工件表面的形成运动,其工作性能的好坏直接影响加工质量与机床生产率。 机床主轴部件的工作性能主要表现在四个方面;旋转精度、静刚度、抗振性与热稳定性。静刚度不仅是主轴部件承受负荷能力的重要标志,而且同抗振性也密切相关。所以,正确地评定主轴部件的静刚度,从而合理地决定其结构与有关参数,是不容忽视的。 本文将研究如何全面地正确评定主轴部件的静刚度(指径向的,下同),研究在按静刚度对两支承主轴部件进行设计时,如何选择有关结构与参数,使它在工作时的轴端位移…     

机床高速水动主轴的设计及仿真

针对电主轴在机床高速化的不足,设计了一种利用水来驱动主轴转动的方案,主轴的驱动和转动一体化,利用水实现了驱动功能、冷却功能、支撑功能,可以应用于中小型零件的的高速加工,例如加工半导体零件。本文分析了机床高速水动主轴的工作原理,对于机床高速水动主轴的结构进行了设计,建立了出口截面的结构模型。对于主轴的的各项参数进行了分析,得到了各个物理量间的关系。     

国外机床主轴滚动轴承的动向

机床主轴轴承(特别是前轴承)的结构和精度,在很大程度上决定了机床的性能(加工精度、光洁度、切削能力、温升及噪音等)。面对机床向高精度、高效率及自动化方向发展的总趋向,对机床主轴轴承提出了一些新的和更高的要求,那就是:主轴轴承具备更高的回转精度和更高的静动刚度,在高速重载下具有最小磨擦扭矩和低温升;在较宽的主轴转速范围内保证较小的温差等。这些要求,一般轴承是无法满足的。为此,国外一些著名的轴承厂家,都为机床主轴需要而生产了机床主轴专用轴承。 本文着重介绍国外机床主轴轴承新结构以及提高轴承精度方面的一些动向。 一…     

数控多线切割机床高精度罗拉轴的关键技术研究

为了实现石英晶体等非金属脆硬材料的高精度多线切割的目的,对高精度数控多线切割机床罗拉轴系统关键设计技术和装配工艺进行研究,本文设计了一种高精度多线切割机的罗拉轴系统的结构、温控、防砂系统,以及装配工艺,并对其主轴的温控、防砂和装配性能进行实验研究,获得了基本性能指标,对进一步研究脆硬材料切割加工技术具有重要的指导意义。     

机床—主轴耦合系统动力学建模与模型修正

复杂精密零件的加工对机床装备的性能不断提出新的挑战。为了保证零件加工精度,有必要在设计阶段对机床整机的动态特性进行精确预测和评估。以机床主轴系统为研究对象,介绍一种机床—主轴系统耦合动力学模型,并指出该模型中存在结合面动态特性参数的辨识问题。为了修正该耦合模型,提出一种基于频率响应函数的有限元模型修正技术。采用包含平动自由度(Degree of freedom,DOF),转动DOF以及平动与转动耦合DOF的刚度矩阵来描述结合面的动态特性,通过测量结合面处的动态响应数据,辨识出高速主轴与机床之间结合面的刚度参数,从而达到模型修正的目的。试验结果表明,修正后的机床—主轴耦合模型反映出了机床结构对主轴动态特性的影响,能较好地预测主轴安装到机床上以后的动态特性,从而为高性能机床的数字化设计与制造提供理论依据。     

Analysis of the machining stability of a milling machine considering the effect of machine frame structure and spindle bearings: experimental and finite element approaches

Chatter vibration has been a troublesome problem for a machine tool toward the high precision and high-speed machining. Essentially, the machining performance is determined by the dynamic characteristics of the machine tool structure and dynamics of cutting process of spindle tool. Prediction of the dynamic behavior at spindle tool tip is therefore of importance for assessing the machining stability of a machine tool at design stage. This study was aimed to evaluate the machining stability of a vertical milling system under the interactive influence of the spindle unit and the machine frame structure. To this end, a realistic finite element model of a vertical milling tool was generated by incorporating the spindle-bearing model into the head stock mounted on machine frame. The influences of the dynamics of spindle-bearing system and the machine frame structure were investigated respectively. Current results show that the machine tool spindle system demonstrates different dynamic behaviors at different frequency ranges, which are also characterized as structural modes and spindle modes, respectively. In particular, the maximum compliance of spindle tool tip was found to occur at the bending vibrations of spindle shaft and vary with the preload amount of spindle bearing. The machining stabilities were predicted to different extent, depending on the exciting modes which could be related to the influences of machine frame and spindle unit.     

Optimal mechanical spindle speeder gearbox design for high-speed machining

There are different solutions to upgrade a conventional machine tool to high-speed machining (HSM). One of the cheapest solutions is the use of mechanical spindle speeders. Mechanical spindle speeders allows the increase of the speed of a machine tool by means of a multiplier gearbox, and they have been successfully used in a variety of machining processes, such as drilling, milling, tapping and even grinding. They are mainly used in the mould and die industry, since they provide an effective solution for upgrading an existing lower speed machine tool. In this work, the design of the planetary gear trains (PGTs) used in all of the mechanical spindle speeders marketed nowadays is optimised by minimising the volume and the kinetic energy of these gearboxes, since their functionality depends directly on these two criteria. In the authors’ opinion, the results can be of great interest for spindle speeder manufacturers.     

Robust rotor dynamics for high-speed air bearing spindles

For ultra-precision machining machine tool components need to operate outside critical frequencies of the machining system to avoid insufficient surface finish caused by vibrations. This particularly applies to tooling spindles as those are generally the component of a machine tool with low stiffness and damping values. Surface finish and shape of a machined part rely directly on the overall accuracy in motion of the tooling spindle over the entire machining parameter and speed range. Thus spindle designs for an operation outside critical frequencies combined with high stiffness and damping values are crucial for ultra-precision machining.For sufficient stiffness properties bearing gaps of gas bearings have to have a size of only a few microns and show a distinct sensitivity on temperature and for journal bearings also on speed. This again means that bearing properties change with temperature and speed. Considering a spindle system comprising a rigid shaft rotating in a radial/axial bearing system with changing stiffness and damping properties leads to a resonance speed map with changing rigid mode resonance speeds.This paper treats the influence of shaft speed and temperature on bearing gaps from which rigid mode resonance speeds for a shaft spinning in a bearing system are derived. The quoted influence of centrifugal load and temperature on bearing stiffness, damping and load capacity can be applied to any kind of gas bearing. Therefore the calculation of bearing stiffness, damping or load capacity is not treated in detail. The reader will be shown that there are simple design rules for air bearing systems and shafts of high-speed tooling spindles to avoid critical speeds through the entire speed range. Finally, methods of how to prove the initial design goals and how to verify dynamics of high-speed spindles in production will be presented to the reader. It will also be shown that there are production high-speed spindles available which do not include any critical speed within their speed range and thus show robust rotor dynamics with extremely low errors in motion.Procedures in design, validation and application treated in this paper shall give the reader not only design guidelines for spindles to avoid critical spindle speeds within its speed range, but also recommendations for machine tool builders and end-users for a machine operation taking machine and rotor dynamics into account. As the knowledge for this paper is predominantly based on the experience and work of the author himself only a few references are used. However presented testing results entirely confirm the approach presented in this paper.     

The use of vibration measurements for quality control of machine tool spindles

The assembly of machine tool spindles results in a degree of variability in the effective stiffness of the bearings. This may result in a poor machining performance if the bearing stiffnesses are below their specified design values. Alternatively, the life of the bearings may be reduced if the bearings stiffnesses are above the design values because of excessive preload. This paper describes a method of checking the spindle assembly by making vibration measurements. From these measurements it is possible to determine which bearings (if any) are not at their design stiffness. This then allows appropriate adjustments to be made to ensure the assembled spindle is close to the design specifications.     

机床主轴模糊可靠性设计计算方法

讲述了常规机床主轴设计的不足，提出将模糊可靠性设计运用于主轴的刚度校核中，通过例子阐述主轴模糊可靠性设计过程和结果，以及与常规可靠性设计的不同，说明主轴采用模糊可靠性设计的必要性。     

Electric load management in spindle run-up and run-down for multi-spindle machine tools via optimal power-torque trajectories and peak load synchronization

Electrical energy consumed during machine tool spindle run-up and run-down has a non-negligible impact on overall spindle energy performance. A model-based efficiency analysis of a common spindle unit architecture, with a separate induction motor, is conducted to investigate different loss sources. The identified model is exploited to define optimized motor torque trajectories for spindle run-up/run-down, exploiting the idle time typically available on the fastest machining modules in a transfer machine tool. Study reveals that savings can be achieved, both in terms of peak power and energy losses, by adopting optimal values for the acceleration rate and power limit. To reduce power peaks at the machine level, a unit synchronization algorithm is proposed which avoids simultaneous acceleration/deceleration of multiple spindles. The overall cycle time is preserved by prioritizing the execution of the slowest processing unit. The proposed methodologies have been applied to a three spindles flexible transfer machine tool, estimating the corresponding gains in terms of energy losses and power peak reduction.     

基于改进PSO算法的数控机床主轴优化设计

通过分析主轴结构和加工过程中受载变形情况, 建立了主轴优化设计的数学模型。根据邓克莱法计算得到的一阶固有频率近似值,引入动态约束条件 。针对传统优化设计方法在解决主轴优化设计中出现的问题,引入粒子群优化 (PSO) 算法,并提出了一种惯性权重值适应性递减的粒子群（ADW）算法。将ADW算法用于数控机床主轴优化实例中,得到主轴结构参数优化组合。研究结果表明,运用所建立的主轴优化设计数学模型及改进粒子群算法可以得到主轴结构参数优化组合,充分显示了该研究方法的有效性。