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.     

基于颤振预报和预测的稳定性控制理论及方法研究

针对由颤振预测控制策略指导的稳定切削控制方法实时动态调整能力差的缺点,综合颤振预报、预测理论,进行了稳定性在线寻优控制理论及方法的研究。基于刀具—工件系统铣削再生颤振动力学模型,研究了考虑系统结构参数(刀具、工件装夹刚度)和加工参数(切削加工参数优化选择)的切削稳定性评价方法,提出了以扩大稳定性区域和稳定最大材料切除率为控制目标的机床稳定性控制方法。形成了以"预报—控制—效果评估—再控制"为步骤的在线监测、智能诊断和实时控制的集成一体化策略。设计并实施了稳定性控制理论验证实验,获得了与理论分析一致的结论。     

切削过程参数的在线控制

１前言随着电子技术和计算机技术的不断发展,金属切削系统的智能化程度变得越来越高,尽管如此,切削参数的经验选择法和切削颤振仍然普遍存在于切削过程中［１－４］,不但降低了加工效率和加工质量,有时甚至造成严重的经济损失。为了充分发挥数控系统高效率和高质量的加工特点,在线监测切削过程,在线调整切削参数,抑制切削颤振的发生,提高数控系统的稳定性,已成为现代加工业不可回避的重要问题之一,这里建立了切削参数的稳定区搜索控制方法,通过该方法可提高数控系统的加工效率、降低加工成本。２切削颤振的预报方法动态切削力的…     

镗削颤振快速预报技术研究

切削颤振切导致产品质量、生产效率、刀具和机床使用寿命的降低 ,同时造成噪声污染 ,影响操作者身心健康。随着工厂自动化发展 ,操作者日益远离加工现场 ,对切削颤振进行在线监视预报和控制变得越来越重要。但由于其发生发展的过程极其短暂 ,使颤振的在线预报十分困难。本文在讨论了镗削颤振发展机理的基础上 ,提出了一种基于神经网络进行颤振预报的新方法。用 L O- RBF模型进行传感信号预处理 ,结果输入 Fuzzy ARTMap模型进行颤振识别 ,大大缩短了信号处理时间 ,提高了识别的准确性 ,取得了满意的结果。     

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。     

专利

一种机床切削颤振在线智能控制方法及其系统。用于精密柔性制造加工领域。系统包括利用电流变材料设计一种动态特性可以在线快速调整的智能型镗杆,向电流变材料施加高压电场的电斥变换器、计算机、电荷放大器及输入加速度信号的加速度传感器,加工系统动态特性在线调整主要依靠含有电流变材料的机械结构进新行。控制方法包括系统初始化、颤振识别和颤振控制三部分。该方法中采用CDM方法在线     

金属切削颤振机理及其控制研究的新进展

对金属切削颤振控制的研究新进展进行了详细的概述，在归纳和分析切削颤振控制研究现状的基础上，对控制颤振存在的若干问题进行了分析与讨论，提出未来的主要研究方向是：将混沌控制等现代控制理论引入颤振控制，研制出实用智能化的传感器、控制器，实现对金属切削颤振的实时性、精确性控制。     

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。     

利用电流变材料在线改变镗杆固有频率抑制切削颤…

金属切削加工中,再生型颤振是一种不易于通过机械结构改良克服的影响切削加工质量,刀具切削不稳定现象。本文通过连续小范围的改变切削系统固有频率,实现了再生型切削颤振的在线抑制。这种方法非常适用于受加工需要而无法提高切削稳定性的镗削及钻削加工。     

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...     

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。     

Integration of cutting force control and chatter suppression control into automatic cutting feed adjustment system design

Abstract

This study designed an automatic cutting feed adjustment system for computer numerical control (CNC) turning machine tools, which integrate the operational characteristics of cutting force control and chatter suppression control to shorten the machining time and maintain the quality of workpieces. The setting of appropriate machining conditions (such as cutting feed, spindle speed and depth of cut) to consider both machining quality and efficiency often causes difficulties for machine tool operators. Therefore, this study uses cutting force control to design an automatic cutting feed adjustment method for cutting tools, and then, the chatter suppression control design is used to modify the cutting force command to suppress cutting chatter. The experimental results of the CNC turning machine tool show that the use of the cutting force control to adjust the cutting feed can shorten the machining time; however, the cutting chatter results in larger surface waviness on the workpiece surface. When the cutting force command is properly modified by actuating the chatter suppression control, the workpiece shows better surface roughness with prolonged machining time. Therefore, the cutting tests demonstrate that the proposed system is feasible for satisfying the machining requirements of the manufacturing processes of mechanical parts for high speed and high accuracy.     

A novel deep groove machining method utilizing variable-pitch end mill with feed-directional thin support

A novel method for deep groove machining is developed which utilizes a long-shank variable-pitch end mill with a feed-directional thin support in this research. Recently, thin and tall ribs are required for many parts to reduce their weight and material consumption without sacrificing their stiffness and strength. It leads to necessity of deep and narrow grooves in dies and molds for their mass production. However, such deep groove machining is difficult, since long flexible end mills cause severe chatter vibrations induced by regeneration and mode-coupling. There have been many studies on the regenerative chatter vibration, while there have been few studies on the mode-coupling chatter vibration. Both chatter vibrations need to be suppressed in the deep groove machining. In this study, the regenerative chatter vibration is suppressed by employing one of the conventional methods, i.e. a variable-pitch end mill. On the other hand, there is not a good method to suppress the mode-coupling chatter vibration in the deep groove machining. Therefore, a new suppression method is proposed in which the long-shank variable-pitch end mill is supported with a thin plate in the feed direction. The support device and the long-shank variable-pitch end mill are developed and applied to machining of hardened die steel. Validity of the proposed method is verified both analytically and experimentally in this study.     

基于电流变材料的切削颤振在线监控技术研究

提出可以利用电流变材料的电控流变特性,通过在线调控切削系统动态特性以提高切削稳定性。并针对镗削系统,开发出一套可根据实时采集的切削振动信号自适应地快速调整系统动态特性以避免颤振发生的颤振智能监控系统。     

数控车床切削加工过程的颤振稳定性研究

分析了数控车床加工过程中切削颤振的产生机理，总结了现在国内外对切削颤振抑制理论实践的研究现状。基于脉冲激振法针对CJK6140数控车床刀架系统的初步研究，提出了基于计算机仿真技术对加工过程进行动态仿真的方法，从而达到提高加工效率的目的。     

非线性颤振对切削加工过程影响初探

研究了非线性颤振对机械加工过程的影响规律,通过实验得到了颤振稳定性图,分析了切削用量、切削条件与非线性颤振及机械加工质量的关系,提出了避免切削颤振的发生与提高加工质量的工艺措施。     

数控机床切削颤振状态监测与控制技术

针对数控机床加工过程中切削颤振的现象,通过对机床的在线监测,将采样出的加速度信号进行数据处理,提出一种θ法作为判据的方法来判别颤振是否发生,并通过监控计算机对主轴箱和进给箱进行调控,达到抑制颤振的方法。该监控系统通用性强,所用设备少,具有可行性,从而为提高加工效率提供可循的加工依据。     

通过声音信号判断切削颤振的试验研究

通过建立高速铣削试验台获取高速铣削声音信号,并对数据进行分析,发现切削过程声音信号的幅频域特性与其稳定性有着紧密的联系.该试验为利用声音信号判断切削颤振提供了事实依据,并为切削颤振控制打下了试验基础.     

Robust regenerative chatter stability in machine tools

The expeditious nature of manufacturing markets inspires advancements in the effectiveness, efficiency and precision of machining processes. Often, an unstable machining phenomenon, called regenerative chatter, limits the productivity and accuracies in machining operations. Since the 1950s, a substantial amount of research has been conducted on the prevention of chatter vibration in machining operations. In order to prevent regenerative chatter vibrations, the dynamics between the machine tool and workpiece are critical. Conventional regenerative chatter theories have been established based on the assumption that the system parameters in machining are constant. However, the dynamics and system parameters change due to high spindle speeds, tool geometries, orientation of the tool with respect to the rest of the machine, tool wear and non-uniform workpiece material properties. This paper provides a novel method, based on the robust stability theorem, to predict chatter-free regions for machining processes, by taking in account the unknown uncertainties and changing dynamics for machining. The effects of time-variant parameters on the stability are analyzed using the robust stability theorem. The experimental tests are performed to verify the stability of SDOF and MDOF milling systems. The uncertainties and changing dynamics are taken into account in order to accommodate the optimal selection of machining parameters, and the stability region is determined to achieve high productivity and accuracy through applications of the robust stability theorem.