【作者】 崔中；

【导师】 文桂林；

【作者基本信息】 湖南大学 ， 机械设计与理论， 2010， 博士

【摘要】 高速磨床是现代机械加工中重要的工作母机。随着现代工业产品的精度要求不断提高,对高速磨床本身的结构设计也提出了更高的要求,以保证其加工的精度和稳定性。国内外的学者和工程师在此领域内做了很多基础性的研究工作,但是由于高速磨床本身的一些结构特点,使研究工作同时面临着一些瓶颈问题。作为制造业大国,我国在制造装备的设计领域,目前与国际水平还存在着一定的差距,并且国外在这方面的先进技术对我国又是限制出口的,导致相对落后的制造装备大大制约了我国制造业水平的进步,因此高速磨床的自主开发与研制对于我国制造业发展具有极其重要的意义。优化和反求技术是当前国际上十分活跃的研究领域,对于工程设计问题有相当重要的指导作用。本文在总结前人关于高速磨床的设计研究及各种优化技术的基础上,将近似模型技术结合全局优化算法的现代设计方法引入高速磨床结构设计领域,解决了高速磨床设计中遇到的一些难题。围绕高速磨床结构设计中的优化技术及应用这个主题,本论文开展了以下几个方面的研究:1.建立了一种适于高速磨床零部件结构优化设计的优化技术流程,将近似模型技术引入到高速磨床结构优化设计中,代替试验研究和耗时的传统数值计算模型,结合全局优化算法,达到了提高其结构优化的效率和精度的目的。通过对目前高速磨床的结构设计要求及其零部件的结构特征的分析,运用现代设计方法对高速磨床的静、动态性能进行研究,发现一般的优化技术缺少针对性,或是设计的成本太高,致使在工程实际问题中很难进行推广。利用近似回归技术建立研究问题的近似模型,代替无法显式表达的函数关系或是耗时的数值计算问题,是目前解决大规模、复杂问题的有效途径,本文通过研究近似模型的建模理论,采用拟合精度和效率都较好的径向基函数模型处理高速磨床结构设计中的非线性问题,并在此基础上开发出一套高速磨床结构优化软件。2.开展高速磨床动力学和结构分析的联合同步仿真研究,实现工作状态下的关键零部件结构分析的实时与动态仿真分析。在传统的高速磨床动力学分析中,通常将其零部件视为刚体,从而使得到的相关位移、速度和作用力等性能响应数据并不能反映真实的系统情况。动力学分析与结构分析一般是分开进行的,根据动力学分析的结果在结构分析中进行加载模拟和计算,从而降低了分析的精度和效率。另一方面,高速磨床具有精密加工的功能特点,使其分析和设计的过程中,不能忽略零件的弹性变形,尤其是在一些关键参数的选取上,弹性变形会影响设备的加工精度。正是基于上述动力学分析和结构分析的缺陷,本文结合多刚体动力学软件和结构分析软件对高速磨床的运动、加工系统进行了联合同步仿真研究,解决了工作状态中零件结构分析的问题,并对主轴—砂轮架加工系统进行了仿真研究,通过与其多刚体模型进行比较,发现系统中零部件的弹性变形对加工精度具有一定程度的影响。3.开展了针对高速磨床设计中的不确定性问题的研究,将基于区间数的不确定性优化方法引入到高速磨床设计中,并针对高速磨削过程中主轴系统的不确定性问题进行了优化设计。在高速磨床的设计、制造和工作中,存在着很多不确定性的因素,例如,材料特性、边界条件、外界环境等,尤其是磨削过程中的磨削力,以往的设计和分析都将设计参数视为确定性参数,未曾考虑过这些设计参数中的不确定性,然而,这些因素又直接影响设计方案的准确性和可靠性,因此很有必要在结构设计过程中考虑这些不确定性因素。本文以高速磨床主轴系统为研究对象,分析其工作状态并充分考虑磨削力的不确定性,建立了主轴系统工作状态下的不确定性柔性动力学模型,利用基于区间数的不确定优化方法结合隔代映射遗传算法进行了优化研究,结果证明达到了提高主轴系统抗振可靠性的目的。4.提出了一种基于近似模型和变尺度混沌优化算法的高速磨床结构轻量化设计方法。高速磨床结构轻量化的首要前提是保证高速磨床原有的性能不能下降,既要有目的地减轻零部件的重量,又要保证结构的强度、刚度及抗振性等性能要求。对于高速磨床零部件的轻量化设计而言,其设计目的不仅仅是降低成本,同时也是机床进给系统高速化设计的一个重要研究方向,有助于提高进给系统的速度和加速度。然而,进给系统中零件的结构一般都比较复杂,本文借助近似模型方法代替实际结构模型,并结合变尺度混沌优化算法,进行结构轻量化设计。变尺度混沌优化算法是一种利用非线性动力学系统中混沌现象的遍历性、随机性等特点来寻找全局最优值的随机全局性优化方法,相比于其他梯度优化算法和随机优化算法,其原理简单、易懂,用于操作的算法参数少,易于一般工程设计员理解和操作,同时其优化收敛速度快,精度高。本文以高速磨床进给系统中的拖板为研究对象,通过对其进行参数化建模,并建立各个性能目标的近似模型,利用变尺度混沌优化方法进行多目标优化设计,达到了结构轻量化设计的目的。5.对高速磨床整机建模中的各种结合部的建模方式及其等效动力学参数的反求进行了研究,并在此基础上对高速磨床的整机进行了分析。在高速磨床中,结合部的特性研究因其影响因素多并且机理复杂,一直是一个难点。国内外很多学者分别从接触机理方面和动态试验方面进行了探索和研究,本文避开了繁琐复杂的理论公式推导和高成本的试验研究,将结合面等效动力学参数的反求过程视为一个参数寻优并与动态试验相匹配的过程,从而简化了参数反求的过程,同时也可以保证结果的准确性。更多还原

【Abstract】 High-speed grinder is the important machine tool in the modern mechanical manufacturing. With the development of modern product design, the structural design of high speed grinder needs be promoted in order to ensure the precision and stability of products. Many researchers and engineers have done some foundational studies on the design of high speed grinder. There exit some bottleneck problems, caused by the structure characteristics of itself. As a manufacturing industry big country, our manufacturing industry development is restricted by the level of manufacturing equipment, which is still of relatively low quality compared with international advanced level. The technology of optimizing and reverse engineering are popular research fields, and play an important guiding role on engineering design. Therefore, in this paper, based on the exiting work of high-speed grinder design and optimization technique, the approximation model method and the global optimum algorithm are conducted to resolve some problems in the structural design.The main research content and contribution are summarized as follows:1. A structural optimization process is established and applied to the high-speed grinder components’design. The approximation model method is introduced into the design of components, instead of traditional numerical analysis, which are time-consuming. The global optimum algorithm is combined with approximation model method, which achieves at the goal of enhancing optimization precision and efficiency. By analysing the design requirements and the structural characteristics of high-speed grinder components, we can find that the common optimization methods are not suit for the design exactly, or the design cost is too high. The approximation model method is an effective way to solve the complex large-scale engineering computation problems. The radial basis function model can pass every sample point in the design space, and has better fitting accuracy for nonlinear problem in high-speed grinder’s structural design.2. A simulation study combining dynamic analysis and structural analysis has been done in high-speed grinder, which can realize the real-time structural analysis under operating conditions. In the traditional dynamic analysis, the components in high-speed grinder are usually considered as rigid body, so that the performance data obtained from simulation such as displacement, velocity and applied load can not reflect the real situation. And the dynamic analysis and structural analysis are processed by separate systems where structural analysis uses the results obtained from dynmic analysis to compute. The characteristic leads to the low precision and efficiency of simulation. On the other hand, the elastic deformation of components can not be ignored during the precision manufacturing. Especially, some key parameters will affect the precision of high-speed grinder. In this thesis, the problem on simulation combining dynamic analysis and structural analysis has been make on the spindle-carriage machining system. The comparison with rigid model reveals that the elastic deformation of components has effect on the manufacturing precision.3. A uncertainty optimization design method of high-speed grinder is proposed. The uncertainty optimization method based on nonlinear interval number programming is introduced to solve the uncertain problem in the high-speed grinder design. There are many uncertain factors in the manufacture and work process of high-speed grinder, such as material property, boundary condition, external environment, especially for the grinding force in the grinding process, which was considered as determined parameter in the design before. But these uncertain factors affect the veracity and reliability of design. It is necessary to consider the uncertain factors in the design. In this paper, the main spindle system is taken as research subject. By considering the uncertainty of grinding forces, a real-time dynamic flexibility model of main spindle system is established. By using the uncertainty optimization based on intervals and intergeneration projection genetic algorithm, the goal of improving the main spindle system performance is achieved.4. A lightweight optimization design method of high-speed grinder based on the approximation model and mutative scale chaos optimization algorithm (MSCOA) is proposed. The premise of high-speed grinder lightweight is to ensure the performance requirement that the weight of components is reduced and the performance requirement such as strength, stiffness, and vibration resistance, must be satisfied. The purpose of lightweight is one of methods of reducing cost and an important requirement of high speed design of feed system, which can improve the velocity and acceleration of feed system. In this thesis, the approximation model and mutative scale chaos algorithm are employed to lightweight the structure. Chaos optimization algorithm as a method of global stochastic optimization has attracted much attention, which utilizes the characteristics of chaotic maps to search for the global optimal solutions. In compared with the other global optimum algorithms, such as micro genetic algorithms (μGA), the method is relatively simple and easy to be operated. Moreover, MSCOA has a good convergent performance with fast convergent rate. The method is validated by the lightweight problem of the grinder slider.5. The modeling method of joint surface and reverse identification method of dynamic parameters are proposed. With aid of these methods, the whole machine of high-speed grinder is analysed. There are many influencing factors of joint surface, which are always complex. Researchers have investigated the contact mechanism of joint surface and dynamic experiments. In this thesis, the dynamic parameter identification is regarded as a matching process of optimizing search combined with dynamic experiments, which avoids complex theoretical formula and costly experiment study.更多还原