评定机床颤振稳定性的新方法

本文考虑了进行机床动态试验时切削宽度连续变化这一时变因素对机床颤振稳定性的影响。由于切削宽度的连续变化,给切削过程引入了新的反馈因素,从而影响机床颤振稳定性。稳定性条件不仅与机床结构有效动柔度的实部有关,而且与相应的虚部及结构主振频率有关。因而传统理论不再适合做为评定机床动态性能的理论依据。本理论给出的稳定性条件,包含了切削工艺参数、工件材料及形状、机床结构动力学参数对机床颤振稳定性的影响,更符合实际地描述了颤振建立的客观条件,是建立新的机床动态性能评价指标的可靠理论基础。     

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。     

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。     

高速切削加工稳定性研究

振动是金属加工过程中的一个复杂问题,其形成的颤振不仅限制了机床加工效率的提高,还对机床和切削刀具造成很大的危害。对数控加工特别是高速加工过程中颤振的研究和控制技术是先进制造技术的重要研究课题,本文介绍了切削动力学建模的两个环节:切削力建模和刀具—工件动力学建模;根据切削力建模方式的不同,将其归纳为基于试验的经验公式建模法、解析建模法和基于人工智能及软件技术切削力建模法;根据铣削加工过程中稳定区域的不同预测方式,切削稳定性分析方法分为时域分析方法、频域分析方法、试验分析方法,并对三种方法的优势和不足进行对比分析;对切削颤振的抑制措施进行了总结介绍;展望了高速切削加工稳定性研究的关键技术,为切削加工振动的理论研究与工业应用提供借鉴和参考。     

电流变液双电极复合结构在车削颤振控制中的应用

应用电流变液复合结构的特殊性能，研究开发了一种双电极智能颤振抑制结构，用于机床车削过程颤振的控制。实验结果证明，利用电流变智能颤振抑制结构对机床车削振动可以进行有效的控制，从而提高工件表面的加工质量，改善刀具切削加工性能。     

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...     

磁流变减振车刀的迟滞非线性特性建模及试验研究

切削颤振是制约机械产品高效、高精度加工的主要问题之一。为此,研制基于智能材料——磁流变液的减振车刀,以利用智能材料良好的机电耦合特性对切削颤振进行有效地抑制。研究表明,磁流变减振装置具有迟滞非线性特性,建立准确的减振车刀力学模型对有效实施切削颤振控制至关重要。搭建了稳态激振试验平台,通过稳态激振试验,探究不同励磁电流、激振频率下磁流变减振车刀的力——位移迟滞曲线变化规律,运用非线性迟滞理论,结合数据分解与参数识别得到不同外界激励下非线性弹性力、阻尼参数、迟滞环节的刚度及迟滞力。对磁流变减振车刀非线性迟滞模型进行了参数辨识,为后期利用该减振车刀进行颤振控制奠定了基础。     

基于电流变材料的车削切断颤振抑制研究

应用电流变材料的特殊性能——对电信号的快速响应能力和连续可变的阻尼，研制了一种智能切削颤振抑制结构(刀座刚度可变部分)，并将其附加在车床刀架上，建立了机床车副颤振实时监控系统，实现了机床车削切断过程的颤振抑制。实验结果表明，利用电流变材料智能切削颤振抑制结构可以对机床车削振动进行有效控制，刀具的振动幅值减小50％以上，且工件表面的加工质量有较大提高。     

基于电流变效应的车削颤振预报控制技术的研究

将电流变减振技术引入机床切削系统,研制了车床横刀架电流变液减振器。通过流变学动态模量测试方法,求得了该系统的附加阻尼和附加刚度,并对该系统振动响应特性进行了理论分析。研制开发了基于电流变效应的车削颤振预报控制系统。预报控制试验结果表明,利用该系统可以对机床切削颤振实施有效的预报控制。     

一种基于稳定性图的车铣复合机床切削稳定性研究及优化

为提高车铣复合机床的切削稳定性,避免切削过程中的颤振问题,文中以稳定性叶瓣图（以下简称稳定性图）为基础,研究了切削微型零件过程中的颤振问题。通过对车铣复合机床机构和机床模型的分析,得到了机床动态振动模型和机床颤振的数学模型。同时通过锤击试验方法,得到了刀具与工件系统的传递函数,构建了车铣复合机床的稳定性图。最后对机床主轴部件、机床后轴部件和高频铣削部件的稳定区间进行了研究,该实验研究结果指导和优化了车铣加工切削微型零件的参数选择。     

Feedrate optimization for variant milling process based on cutting force prediction

Machining process modeling, simulation and optimization is one of the kernel technologies for virtual manufacturing (VM). Optimization based on physical simulation (in contrast to geometrical simulation) will bring better control of a machining process, especially to a variant cutting process – a cutting process so complex that cutting parameters, such as cutting depth and width, change with cutter positions. In this paper, feedrate optimization based on cutting force prediction for milling process is studied. It is assumed that cutting path segments are divided into micro-segments according to a given computing step. Heuristic methods are developed for feedrate optimization. Various practical constraints of a milling system are considered. Feedrates at several segments or micro-segments are determined together but not individually to make milling force satisfy constraints and approach an optimization objective. After optimization, an optimized cutting location data file is outputted. Some computation examples are given to show the optimization effectiveness. This revised version was published online in October 2004 with a correction to the issue number.     

自由曲面等高加工铣削载荷预报

实际生产过程中球头铣刀主要用于曲面加工,但是关于球头铣刀曲面加工切削力的研究很少.本文针对曲面铣削加工中球头铣刀切削力预报的问题,通过离散近似将动态的切削过程分解为一系列进给方向和刀具与工件接触区不断变化的微小瞬态阶段,将剪切和犁切双重作用的静态球头铣刀切削力模型引入到自由曲面铣削载荷预报中,并选取一自由曲面工件进行铣...     

基于UG的管材切割生产线结构设计

集上料、切割、冲压于一体的管材切割生产线共分3个单元（上料单元、切割单元、冲压收集单元）。该自动化生产线使用接近开关进行信号采集,使用机械手对待切管材进行固定,在设计过程中,着重利用了管材本身的自重。这种结构可降低生产成本、提高工作效率、确保产品精度;而且还能减轻工人劳动强度,并为后续PLC自动控制提供设备支持。本生产线结构采用 UG软件进行设计,可以缩短设计周期、降低设计成本,并且能够直观地展示设计效果。     

模具制造中引入高速切削技术的实例研究

数控高速切削技术应用于模具加工时,要合理规划各个面的加工顺序和粗精加工工艺,正确设置刀具切入工件的方式和刀具路径,保证切削过程各因素平稳,变化光滑连续,使切削过程安全高效进行。     

Intelligent high-speed cutting database system development

In this paper, the components of a high-speed cutting system are analyzed firstly. The component variables of the high-speed cutting system are classified into four types: uncontrolled variables, process variables, control variables, and output variables. The relationships and interactions of these variables are discussed. Then, by analyzing and comparing intelligent reasoning methods frequently used, the hybrid reasoning is employed to build the high-speed cutting database system. Then, the data structures of high-speed cutting case base and databases are determined. Finally, the component parts and working process of the high-speed cutting database system on the basis of hybrid reasoning are presented.     

The actual geometry of the cutting tool involved in machining

Understanding actual geometry of the cutting tool involved in machining is critical to the investigation of the mechanism of cutting process. According to control pattern of the flank and the insert shape, the cutting tools are classified into four different types in this paper including S- and non-S-shaped tools with cylindrical control and conical control. By establishing all the four kinds of tools’ 3-D models, the actual geometry of the cutting tool can be obtained. Research results suggest that the actual geometry involved in machining of the S-shaped inserts whether with cylindrical control or conical control is sphere; non-S-shaped with cylindrical control tools is ellipsoid while non-S-shaped with conical control is paraboloid.     

A composite fitting model of discrete handbook data for peripheral end milling

Machining data handbooks are important reference books in the machining industry, as they provide recommended process parameter values for common machining operations. The machining data, although covering a wide range of relevant cutting conditions, are only listed under discrete cutting conditions. Rough interpolation-based calculations are often needed in order to estimate the process parameter values at the desired cutting condition. In this work, a composite fitting model is presented to fit a composite functional curve through the discrete handbook data of recommended cutting speeds and feeds with respect to the cutting condition of radial depth of cut for peripheral end milling. The objective is to establish a functional relationship from the handbook data such that recommended cutting speed and feed can be obtained for any given radial depth of cut. According to the tabulated layout of the machining data, the entire range of the radial depth of cut is divided into three segments having distinctive formulations and trends. Constraints are then imposed to preserve the trends and smoothly connect the adjacent segments. As a possible application of the presented model, a case study of machining a rectangular pocket is provided. Machining time of a potential process plan is readily evaluated based on the cutting speeds and feeds obtained from the composite model.     

An integrated evolutionary approach for modelling and optimization of laser beam cutting process

This paper presents a new integrated methodology based on evolutionary algorithms (EAs) to model and optimize the laser beam cutting process. The proposed study is divided into two parts. Firstly, genetic programming (GP) approach is used for empirical modelling of kerf width (Kw) and material removal rate (MRR) which are the important performance measures of the laser beam cutting process. GP, being an extension of the more familiar genetic algorithms, recently has evolved as a powerful optimization tool for nonlinear modelling resulting in credible and accurate models. Design of experiments is used to conduct the experiments. Four prominent variables such as pulse frequency, pulse width, cutting speed and pulse energy are taken into consideration. The developed models are used to study the effect of laser cutting parameters on the chosen process performances. As the output parameters Kw and MRR are mutually conflicting in nature, in the second part of the study, they are simultaneously optimized by using a multi-objective evolutionary algorithm called non-dominated sorting genetic algorithm II. The Pareto optimal solutions of parameter settings have been reported that provide the decision maker an elaborate picture for making the optimal decisions. The work presents a full-fledged evolutionary approach for optimization of the process.     

基于模块式工具系统虚拟刀具库的研究

对机械加工刀具系统进行功能分析，将其划分为刀柄模块、中间模块和工作模块三部分；建立了刀具系统组合和装配的数学模型，在装配的过程中提出虚拟刀具库的理论，并进行了探讨。     

弹簧式快速落刀研究硬态42CrMo锯齿形切屑

试验研究了硬态切削42CrMo（52HRC）中碳高强度合金结构钢锯齿形切屑形成过程。采用高速相机记录弹簧式快速落刀装置刀杆运动轨迹,计算落刀速度、加速度,定量分析该装置性能;在车床上直角自由切削盘状试样,以不同参数进行快速落刀试验,将获得的切屑根部制作成金相标本;考察“冻结”的切削区,着重考察剪切带上裂纹源、裂纹扩展以及绝热剪切带,分析锯齿形切屑形成过程。结果表明：裂纹源产生于自由表面,在切屑形成过程中向材料内部扩展,导致切屑分离的最终因素是裂纹扩展;硬态切削42CrMo切屑形成过程可划分为4个阶段。