孔加工刀具及数控工具磨床发展现状与趋势

数控刀具在金属切削加工中占有非常重要地位,数控刀具经过多年的发展,其设计、制造和应用技术具有了很大的变革。近些年来,随着中、小批量生产越来越要求生产的高效率、自动化以及加工中心的飞跃发展与普及,也促进了数控刀具技术的发展。数控刀具的发展又促进了数控工具磨床的进步,包括磨床结构、精度和磨削加工仿真技术等。     

CIMT’97主要展品的技术特点综述

两年一度的中国国际机床展览会是国际机床界和我国机械制造业的一件盛事。第五届中国国际机床展览会(CIMT’97)又一次荟萃了国内、外各机床厂及相关配套件厂和工具厂的精华,既可看到一些名牌企业享有盛名的产品,也会发现一些脱颖而出的新秀企业所展示的精品。从展览会上我们能深刻地领会到机床工具行业的发展动向,也能生动地观察到琳琅满目的新产品和新结构。从中既反映了丰富多采的世界先进实用制造技术和最新制造技术,也展示了中国机床工具行业通过“三大战役”在增强开发能力和竞争实力方面所取得的可喜的巨大进步。     

机床数控软件化结构体系

提出了一种新的机床数控软件化的体系结构及其相关技术 ,该结构体系将数控机床运动控制与工艺性能控制分离 ,分别由两个基于PC的控制器控制 ,其软件具有独立于硬件的性质 ,而且运动控制的软件是通用的。给出了该结构体系下通用的数控机床运动控制基本软件模块 ,工艺性能控制以一种玫瑰线铣削加工为例 ,表明在本技术支持下 ,机床数控具有独立于具体硬件的软件化结构体系。本技术将直接支持工艺性能完全不同的机械制造设备的开发 ,如可以用于铣床、车床等通用金属切削机床的数控化 ,也可以用于开发齿轮和复杂曲面加工的专用数控设备 ,还可支持机器人、铸造、锻压以及剪切设备机械运动的数字控制     

Design and accuracy analysis of a metamorphic CNC flame cutting machine for ship manufacturing

The current research of processing large size fabrication holes on complex spatial curved surface mainly focuses on the CNC flame cutting machines design for ship hull of ship manufacturing. However, the existing machines cannot meet the continuous cutting requirements with variable pass conditions through their fixed configuration, and cannot realize high-precision processing as the accuracy theory is not studied adequately. This paper deals with structure design and accuracy prediction technology of novel machine tools for solving the problem of continuous and high-precision cutting. The needed variable trajectory and variable pose kinematic characteristics of non-contact cutting tool are figured out and a metamorphic CNC flame cutting machine designed through metamorphic principle is presented. To analyze kinematic accuracy of the machine, models of joint clearances, manufacturing tolerances and errors in the input variables and error models considering the combined effects are derived based on screw theory after establishing ideal kinematic models. Numerical simulations, processing experiment and trajectory tracking experiment are conducted relative to an eccentric hole with bevels on cylindrical surface respectively. The results of cutting pass contour and kinematic error interval which the position error is from –0.975 mm to +0.628 mm and orientation error is from –0.01 rad to +0.01 rad indicate that the developed machine can complete cutting process continuously and effectively, and the established kinematic error models are effective although the interval is within a ‘large' range. It also shows the matching property between metamorphic principle and variable working tasks, and the mapping correlation between original designing parameters and kinematic errors of machines. This research develops a metamorphic CNC flame cutting machine and establishes kinematic error models for accuracy analysis of machine tools.     

一种数控切削机床运行能耗状态在线判别方法

机床运行能耗状态由一系列的能耗状态节点和能耗过程构成。针对至今仍存在一些关键状态节点无法判别等问题,提出了一种数控机床运行能耗状态在线判别方法。该方法基于数控机床运行能耗状态和状态节点的系统分析,并综合机床功率信息和数控系统通信信息,提出关键节点状态与过程状态在线判别方法,解决了切削加工开始、完成等关键节点和精加工状态判别等难题,从而实现了数控机床全部运行能耗状态的在线判别。在FANUC数控机床上进行的案例研究验证了该方法的有效性和实用性。     

车间生产过程的能量足迹建模与加工参数协同优化

为降低零件加工过程的生产能耗,提出一种面向节能的车间生产过程多装备加工参数协同优化方法。以包含机床与机器人的定制化生产车间为研究对象,建立了考虑刀具退化动态过程的生产车间系统能量足迹模型。考虑刀具寿命、机器人运输平稳性的成本指标函数,建立了多装备系统的加工参数协同多目标优化模型。以加工时间为约束条件,使用蜂群算法获取了最优参数。实验表明,以节能目标为主的优化方案可降低机床加工能耗17.97%,降低机器人运输能耗18.13%。     

高速切削加工技术在数控机床中的应用

阐述了高速切削加工技术在数控机床中的应用现状,对比国际和国内的区别,高速切削机床的要求及其特点,发展趋势.     

高速切削及关键技术发展现状

论述了高速切削的概念和优越性,以及高速切削机床、高速切削刀具、CNC控制系统等实现高速切削必需的关键技术的发展现状,并介绍了高速切削技术在相关领域的应用。     

面向绕线机的开放式数控系统

针对传统绕线机控制精度低、速度低和产品质量差等缺点,以微处理器MC68HC000为核心,采用集中控制、分时处理的工作方式,根据绕线机的特点开发一种具有高精高速的数控系统,驱动脉冲最高速率为500KPPS,驱动解析度为0．001mm／Pulse。辅以数控系统软件、绕线机系统开发工具和数控绕线机操作软件,为绕线机开发提供一个开放式的控制器设计平台。     

基于随机森林与主成分分析的刀具磨损评估

刀具是数控机床的重要零部件,其性能直接影响着生产加工精度。为实现机床刀具磨损程度的在线分级评估,提出一种刀具磨损状态的评估方法,该方法结合随机森林与主成分分析模型,建立不同工况下主轴电机电流传感器信号样本与刀具磨损等级的非线性映射关系。在不同加工条件下进行刀具性能试验,采集主轴电机的电流信号和铣削加工参数。对信号利用小波包分解、时域统计、频域分析提取特征,利用随机森林得到刀具磨损的分级评估结果。该方法可有效解决样本不平衡的问题,与常见的组合分类方法AdaBoost所得结果相比,该模型能准确地反映刀具的磨损程度,鲁棒性更好。该方法仅利用数控机床内置传感器实现,无需改动机床结构,不影响主轴动态加工性能,可广泛应用于工业数控机床刀具的磨损评估。     

双摆角铣头摆角切削力矩的计算研究

双摆角铣头是高档数控机床的关键功能部件之一。双摆角铣头结构是实现大型数控龙门镗铣床及加工中心五轴联动的主要形式。首先介绍了通过实验方法计算切削力的过程,在摆角范围给定的条件下,通过理论推导和计算给出了某种结构A/B双摆角铣头摆角切削力矩的计算公式,最后通过特殊位置和任意位置进一步验证了公式的正确性。摆角切削力矩是摆角驱动力矩的重要组成部分,此计算公式的研究对摆角铣头的结构设计具有重要的指导意义。     

数控机床主轴系统热误差温度测量点的最优化设计方法

基于信息论与机床热误差有限元分析方法,提出了一种对数控机床温度测量点的位置进行优化的计算方法,这些测点包含机床热变形误差互信息量最大点。将该方法应用于一台数控螺纹磨床主轴系统的热误差温度测点位置的最优化设计选择,并通过主轴热误差测量实验验证了所提出方法的有效性。     

Optimal cutting condition determination for desired surface roughness in end milling

CNC end milling is a widely used cutting operation to produce surfaces with various profiles. The manufactured parts’ quality not only depends on their geometries but also on their surface texture, such as roughness. To meet the roughness specification, the selection of values for cutting conditions, such as feed rate, spindle speed, and depth of cut, is traditionally conducted by trial and error, experience, and machining handbooks. Such empirical processing is time consuming and laborious. Therefore, a combined approach for determining optimal cutting conditions for the desired surface roughness in end milling is clearly needed. The proposed methodology consists of two parts: roughness modeling and optimal cutting parameters selection. First, a machine learning technique called support vector machines (SVMs) is proposed for the first time to capture characteristics of roughness and its factors. This is possible due to the superior properties of well generalization and global optimum of SVMs. Next, they are incorporated in an optimization problem so that a relatively new, effective, and efficient optimization algorithm, particle swarm optimization (PSO), can be applied to find optimum process parameters. The cooperation between both techniques can achieve the desired surface roughness and also maximize productivity simultaneously.     

动态测量数控机床的几何误差

数控机床的检测与修正是机床行业中的一个关键组成部分,每个国家都有相应的测量数控机床几何位置精度,特别是静态几何精度的标准。由于工件是在动态的过程中进行加工,数控机床的静态精度并不能完全代表其几何位置精度,对于某些精密加工和高速加工场合,必须对数控机床进行动态测量补偿,本文介绍了一种动态测量数控机床位置精度的系统,并给出了一些动态误差的实验结果。     

在ANCA TX7+数控磨床上加工PCBN型面铣刀负倒棱的工艺方法

用普通工具磨床难以加工复杂型面铣刀的负倒棱,一般的数控磨床没有现成的负倒棱加工程序。本文以球头铣刀为例,介绍了通过人工建模在ANCA-TX7+数控磨床上加工带负倒棱型面铣刀的编程和工艺方法。     

Analysis of CNC machining based on characteristics of thermal errors and optimal design of experimental programs during actual cutting process

The compensation of thermal errors plays a critical role in developing the machine tools of intelligent computer numerically controlled (CNC). According to the international standards, the testing, modeling, and compensation of thermal error of CNC machine tools are carried out only in a so-called idling state where the spindle is free running without any workload. However, in practical applications, machine tools are often applied in the actual cutting state with more influence factors, such as cutting parameters, cooling liquid, and cutting force. Subsequently, the thermal characteristics at idling state and actual cutting state are compared and analyzed in this paper. It was found that the thermal error compensation model under idling state is not precise enough to be applied in actual cutting state. Also, further research finds that different combinations of cutting parameters, such as spindle speed and feed rate, also have influences on the accuracy of prediction and robustness of thermal error model under actual cutting state. Therefore, the cutting parameters of spindle speed, feed rate, depth of cut, and ambient temperature are studied with the usage of the Taguchi method. Through calculating signal-to-noise ratio (SN) of each combination through residual standard deviation of thermal error model, the combination of optimal cutting parameters can be obtained. The resultant analysis shows that the thermal error model under the combination of optimal cutting parameters demonstrates higher accuracy of prediction and better robustness.     

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.     

航空发动机整体叶盘刀具性能灰色综合评价

以某型航空发动机钛合金整体叶盘的数控铣削为研究对象,提出了一种面向航空发动机整体叶盘的数控铣削刀具性能灰色综合评价方法。首先设计涵盖航空发动机整体叶盘难加工特征的基准件模型,然后基于灰色关联度分别构建了粗精加工刀具性能灰色综合评价模型,最后进行基准件的切削试验并应用所建立的灰色综合评价模型对刀具性能进行综合评价。研究结果表明,所构建的基准件模型和灰色综合评价模型可以快捷、有效地评价刀具性能。     

A Study on an Open Architecture CNC System with a NURBS Interpolator for WEDM

This paper deals with the design and implementation of an open architecture CNC system for wire electrical discharge machining (WEDM) with a consideration of the differences between WEDM and NC cutting machines. Work using open architecture controllers (OACs) has focused mainly on metal cutting machines. WEDM has many aspects similar to milling machines. However, there are differences in the machining processes and control strategies. To close the gap between previous general work on OAC and the WEDM specific needs, an open architecture NC model for WEDM comprised of a synchronisation kernel and an NC functional module is proposed. The proposed CNC system is applied to an existing commercial WEDM system by a retrofitting method. A precise NURBS interpolation function is implemented and sample runs are conducted with a NURBS interpolator that is added to the proposed system.     

用先进的数控系统改造旧机床

南京四开公司是一家中外合资的高新技术企业,推出的主要产品ＳＫＹ数控系统及数控镗铣床荣获’９５中国高新技术、新产品博览会金奖,被国家科委认定为１９９５年度国家级重点新产品。经过市场的长期考验,被用户誉为“真正实用的数控铣床”。它适合加工各种复杂的二、三...