新型立式数控铣床问世

上海海成机械制造有限公司最近自行研制开发成功了一台VM—７４５立式数控铣床。该数控铣床的底座、床身、立柱、滑鞍等主要结构铸件均采用高强度的优质铸铁，金相组织稳定，能长久确保机械加工精度。X、Y、Z三向导轨均配以预加载荷的直线导轨，响应速度快，机械精度保持性好。机床整体结构设计呈金字塔形状，故切削时热稳定性强、抗振效果好。机床主轴设计带有冷却循环用的沟槽，当机床在重切削或高速切削时，可有效地防止主轴热变形。新型立式数控铣床问世     

模具加工用数控镗铣床的选型研究

数控镗铣床是一种重要的模具加工设备。对适用于模具加工的数控镗铣床在加工范围、机床精度、机床结构、主轴、机床进给机构、机床控制系统等方面进行了研究总结。提出了模具用数控镗铣床选型过程中的关键环节和各项关键参数。     

大型落地式镗铣床TKS6916整机有限元分析

利用有限元软件建立了大型落地式镗铣床TKS6916整机模型,并对其进行静力和动力分析。静力分析结果显示:机床的变形是由床身自重以及滑座与立柱间联接螺栓的预紧力两个载荷效应叠加而成;机床最大应力值远低于材料的屈服极限,说明机床的材料使用是足够安全的。动力分析结果说明:前5阶模态与立柱和油缸直接相关,在设计中需要加强其刚度;和立柱有关的模态不会随主轴箱位置的变化而变化,而和油缸有关的模态受主轴箱位置的影响较大。     

专利

专利名称：重型数控龙门镗铣床横梁立柱夹紧机构专利申请号：CN201020630343．3公开号：CN202070911U申请日：2010．11．23公开日：2011．12．14〈br〉 申请人：营口重型机床集团有限公司〈br〉 重型数控龙门镗铣床横梁立柱夹紧机构，属重型数控镗铣床横梁立柱夹紧机构的设计和制造技术领域。在连接法兰的上部有一多倍出力气缸，在直角架内的左端部有一平衡端心轴，在直角架内的右端有一夹紧端心轴，平衡端心轴和夹紧端心轴之间有一杠杆，在平衡端心轴上套装有弹簧，夹紧端心轴上带有夹紧端弹簧。本实用新型的使用是将其安装在重型数控龙门镗铣床横梁上。它的工作原理是；当关闭设备时，靠弹簧的力直接把弹性元件夹紧在立柱上，当启动设备时，多倍出力气缸动作压缩弹簧，使杠杆抬起，弹性元件和立柱脱离，取消夹紧功能。本实用新型的特点是，结构简单，安装方便，多倍气缸出力大，动作敏捷，夹紧性能好，由于夹紧和横梁驱动是分开的，即使在升降驱动出现问题进行检修的时候也不因为不能自锁横梁下滑造成设备和人身事故。解决了现有设备存在的问题。     

垂直安定面专用机床的设计

对垂直安定面的结构和加工表面进行分析,研究机床在切削工况下的受力状态、抗震性、精度保持性、响应速度等,利用ANSYS对立柱等机床重要零件进行有限元分析,优化结构设计,设计了符合垂直安定面精加工要求的卧式三坐标镗铣床。该机床的研制和应用,实现了垂直安定面加工精度高、生产效率高、投资成本低的目标。     

十年发展 SFAE领军中国机床改造业务高端市场

机床改造业务堪称西门子工厂自动化工程有限公司（以下简称“SFAE”）所营业务中历史最久的一项。早在1993年，其已开始在国内进行高端数控机床电气设计、改造项目，成为SFAE的主要赢利点。时至今日，SFAE累计完成各类大型机床数控项目500余个，积累了丰富的大型数控设备改造经验，在凸轮轴磨床、曲轴磨床、齿轮加工机床、大型镗铣床、大型龙门铣床和生产线改造领域处于市场领先地位。[第一段]     

重型数控机床镗轴的疲劳寿命与可靠度分析

重型数控机床的关键部件可靠性直接影响到机床加工精度。对某公司所生产的TK6920型数控落地镗铣床的镗轴进行受力分析,并通过计算和有限元法验算了镗轴的刚度和强度以确保其均满足其设计要求。将分析结果导入有限元软件Hypermesh的疲劳寿命分析模块进行了镗轴疲劳寿命分析,并依据此结果确立镗轴可靠度。该方法对重型机床关键部件的可靠度分析具有一定的理论指导意义。     

基于网络的数控机床故障预警与诊断平台设计与实现

以大型数控曲轴磨床、重型轧辊磨床和用于核电装备制造的重型数控镗铣床等为研究对象,研究了这类装备关键部件信号采集、故障诊断与预警技术,研制了现场监测与故障诊断仪,建立了这类装备的故障诊断知识库,开发了数控机床故障预警与诊断模型和数控机床故障预警与诊断平台,实现了轧辊数控磨床、数控曲轴磨床和重型数控镗铣床等机床的状态显示、故障诊断和性能预报。     

加工中心机床减少了辅助时间

近来,制造厂在介绍新型的加工中心机床时,除了强调其机床精度、结构刚度和高的切削效能外,而且还夸称具有能减少辅助时间的许多特点。这些特点包括多轴头换刀机构,数控调整刀具和快速上料的工件交换台等。加工中心机床在巴黎所进行的表演证明,刀具数量由于孔和螺纹直径等选用了优先数例而大为减少。而特种的多能刀具如数控镗头足以代替大量的予调刀具。     

最不利工况下大型数控机床主轴的强度计算

本文根据某大型数控机床主轴不等截面及主轴工作时轴承支座产生小弹性变形的特征建立主轴计算模型，并以超静定法及强度理论计算及校验最不利工况下机床主轴的强度。本文介绍的计算方法对同类机床主轴的设计、强度及刚度校验具有实际参考价值。     

Prediction of chatter in NC machining based on a dynamic cutting force model for ball end milling

Ball end milling is one of the most widely used cutting processes in the automotive, aerospace, die/mold, and machine parts industries, and the chatter generated under unsuitable cutting conditions is an extremely serious problem as it causes excessive tool wear, noise, tool breakage, and deterioration of the surface quality. Due to the critical nature of detecting and preventing chatter, we propose a dynamic cutting force model for ball end milling that can precisely predict the cutting force for both stable and unstable cutting states because our uncut chip thickness model considers the back-side cutting effect in unstable cutting states. Furthermore, the dynamic cutting force model considers both tool runout and the penetration effect to improve the accuracy of its predictions. We developed software for calculating the cutting configuration and predicting the dynamic cutting force in general NC machining as well as single-path cutting. The chatter in ball end milling can be detected from the calculated cutting forces and their frequency spectra. A comparison of the predicted and measured cutting forces demonstrated that the proposed method provides accurate results.     

数控落地铣镗床进给伺服系统的建模与仿真

基于机械动力学理论和方法,建立了TK6915型数控落地铣镗机床进给传动系统的动力学模型;采用MATLAB软件对模型进行系统仿真,获得反映系统性能变化的仿真结果,上述结果为改善和优化数控落地铣镗机床进给伺服系统的设计提供了理论和试验基础.     

数控铣床逻辑进给振动铣削的试验研究

研究利用数控铣床的逻辑控制系统进行工作台的脉冲式的进给,实现脉冲切削力作用的分离型的数控振动铣削。研究了脉冲振动方向沿进给方向的振动铣削和脉冲振动方向与进给方向成一定角度的振动铣削过程,并对铣削过程进行了切削力对比试验。试验结果表明：脉冲振动方向与进给方向成一定角度的振动铣削可以降低铣削力,强化铣削过程,降低切削温度,对表面粗糙度影响不大;随进给路线、逻辑关系的不同,切削效果差别很大。     

Cutting force prediction in ball end milling of sculptured surface with Z-level contouring tool path

This paper presents an approach to predict cutting force in 3-axis ball end milling of sculptured surface with Z-level contouring tool path. The variable feed turning angle is proposed to denote the angular position of feed direction within tool axis perpendicular plane. In order to precisely describe the variation of feed turning angle and cutter engagement, the whole process of sculptured surface milling is discretized at intervals of feed per tooth along tool path. Each segmented process is considered as a small steady-state cutting. For each segmented cutting, the feed turning angle is determined according to the position of its start/end points, and the cutter engagement is obtained using a new efficient Z-map method. Both the chip thickness model and cutting force model for steady-state machining are improved for involving the effect of varying feed turning angle and cutter engagement in sculptured surface machining. In validation experiment, a practical 3-axis ball end milling of sculptured surface with Z-level contouring tool path is operated. Comparisons of the predicted cutting forces and the measurements show the reliability of the proposed approach.     

某型镗铣床主轴系统结构设计

主轴系统是镗铣床的核心部件,合理地设计结构,能够提高主轴系统的刚性和切削性能,降低振动和噪声.通过对某型镗铣床主轴系统的设计阐述了镗铣类机床主轴系统设计的方法和原则,并以切削试验证明所设计的主轴系统具有良好性能.     

Dynamic analysis of runout correction in milling

Tool runout and its effects is an important area of research within modelling, simulation, and control of milling forces. Tool runout causes tool cutting edges to experience uneven forces during milling. This fact also affects tool life and deteriorates workpiece surface quality. In this article a procedure, in order to diminish the effects of tool runout, is presented. The procedure is based on chip thickness modification by means of the fast correction of the tool feed rate. Dynamic feed rate modification is provided by superposing our own design of a fast feed system driven by a piezoelectric actuator to the conventional feed drive of the CNC machine tool. Previously, a model of the dynamic behaviour of the system was developed to analyze the influence of fast feed rate modification on cutting forces. The model incorporates the piezoelectric actuator response as well as the structural dynamics of the tool and the designed Fast Feed Drive System (FFDS). Simulated and experimental results presented in this paper show the effectiveness and benefits of this new tool runout correction procedure.     

Mechanistic model for prediction of cutting forces in micro end-milling and experimental comparison

Micro end milling is an important process in the manufacture of micro and meso scale products and has an advantage of creating more complex geometry in a wider variety of materials in comparison with other micro-machining methods. In this paper, a new methodology for predicting the cutting coefficients considering the edge radius and material strengthening effects is presented. Further a mechanistic model is developed to predict the cutting forces in micro end milling operation taking into account overlapping tooth engagements. The mechanistic model, derived from basics considering material property and principles of metal cutting, is valid for a wider range of cutting parameters. The model is validated with the results from micro slot end-milling of mild steel carried out on the basis of full factorial design. On comparing the amplitudes of cutting forces, it is seen that mechanistic model predicts the transverse force with an average absolute error of 12.29%, while a higher prediction error of 19.49% is obtained for feed force. Additionally the mechanistic model is able to predict the variations in the cutting forces with rotation of the cutter and average absolute deviations of 13% and 11% are obtained for feed and transverse forces, respectively.     

Theoretical-experimental modeling of milling machines for the prediction of chatter vibration

Productivity of high speed milling operations can be seriously limited by chatter occurrence. Chatter vibrations can imprint a poor surface finish on the workpiece and can damage the cutting tool and the machine. Chatter occurrence is strongly affected by the dynamic response of the whole system, i.e. the milling machine, the tool holder, the tool, the workpiece and the workpiece clamping fixture. Tool changes must be taken into account in order to properly predict chatter occurrence. In this study, a model of the milling machine-tool is proposed: the machine frame and the spindle were modeled by an experimentally evaluated modal model, while the tool was modeled by a discrete modal approach, based on the continuous beam shape analytical eigenfunctions. A chatter identification technique, based on this analytical-experimental model, was implemented. Tool changes can be easily taken into account without requiring any experimental tests. A 4 axis numerically controlled (NC) milling machine was instrumented in order to identify and validate the proposed model. The milling machine model was excited by regenerative, time-varying cutting forces, leading to a set of Delay Differential Equations (DDEs) with periodic coefficients. The stability lobe charts were evaluated using the semi-discretization method that was extended to n>2 degrees of freedom (dof) models. The stability predictions obtained by the analytical model are compared to the results of several cutting tests accomplished on the instrumented NC milling machine.     

Influence of tool inclination on brittle fracture in glass cutting with ball end mills

Glass milling is discussed with influences of tool inclination on brittle fracture. Cutting tests are performed to observe surfaces in the up-cut and the down-cut processes with a ball end mill inclined in the feed direction of the cutter. Brittle fracture occurs in the down-cut process at high feed rates. Then the machined surfaces in cutting with the ball end mills tilted in the vertical plane with respect to the feed direction are associated with those of the up-cut and the down-cut processes. The cutting forces are also measured to discuss brittle fracture with the change of the undeformed chip thickness. The scratches on the surface finished with the tilted ball end mill are shown in an analytical model with a notched edge shape. The maximum feed rates at which brittle fracture does not occur are shown with the tool inclination in the cutting tests.