切削颤振分析与模糊控制实验研究

切削颤振是影响金属切削加工生产率和加工质量的重要因素。建立了金属切削过程的二维颤振数学模型;对颤振的稳定性进行了线性分析和非线性分析;并以颤振位移作为反馈变量,建立了基于二维模糊控制器的颤振控制系统。实验结果表明,该分析与控制对降低加工表面粗糙度具有重要意义。     

切削颤振研究的关键技术与进展综述

切削颤振是金属切削加工过程中的一种非常复杂的机械振动现象,影响零件加工质量并限制生产率提高.颤振产生的原因和发生、发展规律与切削过程本身以及切削机床动态特性都有着内在的本质联系,长久以来被众多研究者关注.本文就切削颤振在颤振机理、建模、稳定性分析、颤振识别预报以及颤振控制领域的国内外研究成果进行了详细介绍,讨论和分析了...     

金属切削过程颤振控制技术的研究进展

综述金属加工过程中颤振控制的研究概况和进展。根据颤振发生的原因和特点,把对于颤振的控制策略分为对于机床结构的控制和对于切削过程的控制,对于机床结构的控制又进一步分为被动控制、半主动控制和主动控制,总结归纳了前人的研究成果,梳理当前的研究进展。切削颤振控制技术在理论方面受到的制约仍然存在,一些新的技术和新的材料的出现促进颤振控制研究的快速发展,但同时它们本身的发展还面临的一些亟待突破的问题,对这些问题进行分析。随着智能材料和新的控制理论和思想的发展,除传统的控制方法不断得到改进和发展之外,基于智能材料的各种智能控制技术、时滞控制器,以及针对切削过程的非线性、时变性的模糊控制,神经网络等智能控制算法的应用等一些新的控制方法和趋势逐渐也出现在颤振控制的研究中,对它们的研究状况进行分析和展望。最后对切削颤振控制技术发展的总体状况进行评述。     

用于切削颤振机理分析的在线测量系统

金属切削加工中产生的自激振动对加工质量和表面质量均会产生很大的影响,有时甚至使加工无法进行。利用Delphi,开发出了一套在线测量系统,对切削颤振的机理进行了研究。通过实时采集切削过程中与颤振相关的各种数据,并采用FFT（快速傅立叶变换）技术对切削颤振的频率及功率谱进行计算分析,同时结合李萨如图形对颤振能量消减情况进行跟踪显示,在此基础上对自激振动的谐振频率及主要影响因素进行分析,为寻求相应的消振措施提供必要的理论依据。     

融合颤振控制的恒功率约束自适应加工方法研究

针对切削颤振降低恒功率约束自适应加工过程效率的问题,研究了融合颤振控制的恒功率约束自适应加工方法。通过切削试验分析了颤振对机床主轴功率的影响,给出了控制恒功率约束自适应加工过程中颤振的必要性。基于模糊理论开发了模糊控制器,通过调整主轴进给实现了切削过程的恒功率约束。基于变转速抑制切削颤振理论调整机床主轴转速,实现了颤振抑制。以加工效率为目标制定了机床主轴进给和转速的调整原则,实现了融合颤振控制的恒功率约束自适应加工。通过切削实验验证了研究结果的有效性。     

切削颤振的动力学模型研究

振动是金属切削加工过程巾经常遇到的一种现象,也是影响零件加工质量和限制生产率提高的主要因素之一。本文在切削颤振机理研究的基础上,对切削颤振的二维稳定性进行了研究,推导出了在稳定性极限条件下,轴向切深和主轴转速的关系,并用Matlab进行了计算仿真。     

切削系统可变刚度结构及其颤振控制方法的研究

就电流变材料在切削颤振在线控制中的应用进行了研究,提出了几种用于控制镗削颤振的智能型颤振抑制装置.根据电流变材料的非线性振动特性和再生型颤振控制理论提出了切削颤振的变刚度控制方法.给出的仿真试验结果验证了该方法的有效性.     

高速切削加工稳定性研究的现状和发展趋势

论述了国内外高速切削加工稳定性研究的发展现状。介绍了国内外学者此方面的研究工作。对高速切削加工稳定性模型与机理、切削颤振的预防控制和在线监视控制。进行了归纳和分析。并从目前的国情出发。讨论了高速切削加工稳定性研究的发展趋势。     

切削颤振在线监控的研究现状及进展

介绍了国内外切削颤振在线监测与控制的发展现状,分析了现有的颤振监控方法的技术特点和发展趋势,提出了通过基于智能材料主动控制切削系统动态特性来进行颤振在线抑制的新方法。     

刀具颤振与动力减振浅析

1引言 颤振是金属切削加工中最常见的失效方式之一。颤振发生时，在刀具的切削刃和工件之间，除了正常的切削运动以外，还会叠加一个周期性的相对运动。     

基于ERF的切削颤振控制建模与仿真的研究

针对电流变阻尼器抑制切削颤振存在的困难,设计了一种流动与剪切混合模式的电流变阻尼器。介绍了电流变液及电流变阻尼器的工作原理和性能特点;基于Bingham塑性理论,建立了流动与剪切混合模式的电流变阻尼器的力学模型。实验与仿真结果表明,电流变阻尼器能很好地实现振动的实时控制,并能有效地抑制切削颤振的发生。     

切削加工颤振智能监控技术

切削加工颤振智能监控技术是智能机床中不可或缺的一部分,是智能加工的一个重要发展方向。它对于提高零件的加工精度与效率,增加企业的运营绩效具有重要的意义。以传感器的选择、特征提取、颤振识别和颤振抑制为主线,系统的综述了切削加工过程中颤振智能监控的研究进展。分析颤振信号的选择和时域、频域、时频域以及特征自适应智能提取的特征提取方法;分析神经网络、支持向量机、隐马尔科夫模型、混合模型和在线智能进化模型在颤振识别中的应用;着重分析基于主轴转速调整的颤振智能控制方法。在此基础上,对切削加工颤振智能监控的研究难点进行了分析,并总结了目前存在的问题。最后,对切削加工颤振智能监控技术今后的发展趋势进行了展望。     

CONTINUITY AND BREAK OF CHATTER VIBRATION STATUS

By turning a specifically designed conical part, complete process of metal cutting, in which the chatter occurs and expands, is recorded and analyzed. This process exposes that chatter vibration has two characters called continuity and break. The continuity character means that vibration extent enlarges continuously while chatter frequency is almost changeless as the cutting depth extends downwards continuously. The break one is that chatter frequency moves rapidly downwards to a lower level while chatter remains after the cutting depth reach another given value. It is confirmed through an exciting test that the two chatter frequencies obtained in chatter test belong to the natural frequencies of workpiece system and cutting tool system respectively. From the viewpoints of chatter energy supplying and chatter mass effect, the. chatter should occur on one of the two final executive components in its natural frequency. On this basis, a new chatter model with two chatter active bodies is proposed. This new model can better explain the above phenomenon, and adapt to chatter monitoring and improvement of component structure well.     

变速切削方法的减振原理

在深入研究机床加工系统在变频激励力作用下振动响应规律的基础上,系统地论述了变速切削方法的减振原理。理论分析和试验结果表明,变速切削过程的振动响应是机床加工系统在变频激励力作用下的振动响应,它远比在恒频激励力作用下的振动响应小,这是变速切削方法之所以具有显著减振效果的最为本质的减振机理。     

动态切削力对切削颤振的影响

以外圆车削实验为依据,建立加工过程中刀具振动的非线性动力学模型,并采用数值分析方法,研究切削力中的动态分量对切削颤振的影响.结果表明,随速度变化的切削力分量对颤振幅值影响较小,而且会在短时间内被系统内的结构阻尼所衰减.而与加速度成非线性关系的切削力分量对颤振的影响却很显著,而且加速度系数有临界值存在,当超过这个临界值后,颤振的理论幅度将急剧增大.     

A novel chatter stability criterion for the modelling and simulation of the dynamic milling process in the time domain

The modelling of the dynamic processes in milling and the determination of chatter-free cutting conditions are becoming increasingly important in order to facilitate the effective planning of machining operations. In this study, a new chatter stability criterion is proposed, which can be used for a time domain milling process simulation and a model-based milling process control. A predictive time domain model is presented for the simulation and analysis of the dynamic cutting process and chatter in milling. The instantaneous undeformed chip thickness is modelled to include the dynamic modulations caused by the tool vibrations so that the dynamic regeneration effect is taken into account. The cutting force is determined by using a predictive machining theory. A numerical method is employed to solve the differential equations governing the dynamics of the milling system. The work proposes that the ratio of the predicted maximum dynamic cutting force to the predicted maximum static cutting force can be used as a criterion for the chatter stability. Comparisons between the simulation and experimental results are given to verify the new model.     

Development of chatter detection in milling processes

The aim of this research is to develop an in-process detection of the chatter for the actual milling processes regardless of any cutting condition within the small data processing time by utilizing the dynamic cutting forces obtained during cutting. The proposed method introduces three parameters, which are calculated and obtained by taking the ratio of the average variances of the dynamic cutting forces of three force components, to identify the chatter. The algorithm was developed and implemented on five-axis computer numerical control machining center to detect the chatter in ball-end milling and end milling processes. The chatter and the nonchatter can be simply detected during the in-process cutting by mapping the obtained values of three parameters in the reference feature spaces regarding the determined threshold values. The experimental results showed that the proposed method can be effectively used to detect the chatter during cutting even though the cutting conditions are changed.     

微小型无偏正交车铣加工系统稳定性研究

以微小型车铣复合加工系统为对象,通过对微小型车铣加工工艺系统进行分析将其简化为进行端铣研究。针对加工系统中刚度最低的工件系统利用再生型颤振理论进行分析,得到加工稳定性叶瓣图,并且通过实验验证了该叶瓣图的准确性。得到的微小型车铣稳定性叶瓣图可以指导微小型车铣的加工参数选择,提高微小型车铣加工效率。     

高速切削加工稳定性研究综述

高速切削加工的稳定性是影响加工效率和质量的重要因素,从20世纪初就引起了各国研究者的广泛关注。本文综合介绍了国内外研究者在切削加工稳定性领域的研究成果,在综述切削颤振产生机理和切削稳定性模型建立的基础上,重点论述了切削颤振的检测和控制方法,同时指出了高速切削稳定性研究的发展方向。     

Prediction of regenerative chatter in the high-speed vertical milling of thin-walled workpiece made of titanium alloy

With the wide application of high-speed cutting technology, high-speed machining approach of titanium alloy has become one of the most effective ways to improve processing efficiency and to reduce the processing cost, but the cutting chatter which often occurs in the cutting process not only affects the machining surface quality but also reduces the production efficiency. Regenerative chatter is a typical phenomenon during actual cutting, and it has the greatest impact on the cutting process. With the purpose of avoiding regenerative chatter and selecting appropriate cutting parameters to achieve a steady cutting process and a high surface quality, it is necessary to determine the critical boundary conditions where chatter occurs. Built on the work of previous theoretical researches of regenerative chatter, this paper utilized Visual C++ software to calculate the chatter stability domain during the finish machining of titanium alloy. It was shown that the border between a stable cut and an unstable cut can be visualized in terms of the axial depth of cut as a function of the spindle speed. Using the result, it can find the specific combination of machining parameters, which lead to the maximum chatter-free material removal rate. In order to verify the result, the high-speed milling experiment of an I-shaped thin-walled workpiece made of titanium alloy was conducted. It revealed that the actual machining result was consistent with the calculation prediction. This study will offer a useful guide for effective parameter selection in future CNC machining applications.