圆弧-摆线齿廓转子泵啮合齿轮的计算分析

对圆弧-摆线齿廓转子泵工作原理及运动关系进行分析的基础上．提出一种内转子摆线齿廓曲线的参数方程,解决了内转子加工以及损坏后难于测绘的难题。实际应用表明效果良好,大大降低了测绘和加工难度,并且该参数方程有较广泛的适用性。     

某型数控机床主轴系统回转误差动态测试研究

高速主轴的回转误差运动直接影响到被加工零件的加工精度与产品的使用寿命。为了对数控机床的加工性能进行合理评价,分析了同步径向误差运动与工件圆度以及异步误差运动与工件表面粗糙度之间的关系,并采用美国Lion Precision公司开发的主轴误差分析仪对某型数控机床的主轴系统进行回转误差及漂移的测量,根据测量结果对所测主轴加工性能进行评价,为实际生产加工提供了参考。     

一种精密曲线磨床运动建模及实验

根据磨床各平台相对运动关系,建立工件坐标系作为参考坐标系,将砂轮磨削运动分解到工件母线的切向、法向和旋转方向上,即分别代表机床下台、中台的平移和上台的旋转,推导出了工件磨削加工过程的一般模型,并进行了模拟计算.分析了模型加工误差,以加工曲线相对理论曲线的法向误差表征局部误差,以法向误差的峰峰值表征曲线轮廓度.实例的计算结果表明:机床模拟磨削加工的工件轮廓度为3.3 μm,实现了特殊工件的精密加工.     

一种新型板材加工机床

美国 Fewing Gmbh 公司最近推出一种新型多工序金属板材加工机床,称作 Rolltronic该机床采用摆线运动原理加工回转体工件。一般来说,金属板材回转加工艺,如普通旋压和变薄旋压,在转动工件的同时,旋轮     

基于Vericut的直槽连续加工仿真的实现

介绍了摆线加工直槽的原理,基于Vericut软件仿真切削直槽的加工过程。分析了机床的结构并对机床、毛坯、夹具、刀具及NC代码进行设计。通过对仿真结果进行误差分析,证实利用摆线原理加工直槽的可行性。     

基于Free-form型锥齿轮机床的齿面制造技术

介绍了一种基于Free-form型机床切齿加工理论的点啮合齿面制造技术。提供了Free-form型机床3轴联动切齿加工基本方程及详细的计算公式。直接以工件齿轮的转角为运动参数,将机床其它各轴的运动表达为工件齿轮转角的函数。阐明了机床运动函数及其它切齿参数的确定方法。     

基于SAPSO-GA算法的高速曲轴随动数控磨床几何误差辨识方法

以某型数控曲轴磨床作为研究对象,对其结构和运动进行分析,推导出曲轴磨削时理想的砂轮轨迹方程。根据多体系统理论建立含有误差参数的模型,并推导出机床-工件和机床-刀具的运动链位置矩阵,得出机床精密加工的约束方程。对磨床的几何误差进行研究,建立几何误差模型。为快速、准确辨识出各项几何误差,提出一种混合SAPSO-GA算法。通过对比球杆仪测量补偿前后的运动轨迹,分析补偿效果。结果表明:所提方法提高了辨识准确性,通过补偿大大提高了曲轴随动磨床的加工精度。     

摆线在多边形零件加工中的应用

通过对摆线方程的深入研究,提出了一种利用摆线逼近直线的高效加工方法。通过分析摆线各个参数对其形状的影响以及摆线逼近直线的逼近误差,确定了符合要求的摆线参数,并编写了相应的计算程序。最后将计算程序应用于一个给定参数的六边形,通过对该六边形误差的分析计算,使得其理论逼近误差达到了0．018mm,经过实践加工证明了利用这种方法加工多边形零件的可行性。     

TX1600G镗铣加工中心镗削系统空间误差建模研究

随着机床精度要求的不断提高,零部件几何误差间的耦合作用所形成的空间误差已成为影响床身自身精度及加工工件精度不可忽略的误差因素之一。以TX1600G镗铣加工中心镗削系统为研究对象,结合该系统的运动原理及多体系统理论建立拓扑结构及低序体间阵列,并据此获得镗削系统空间误差模型;在模型构建过程中首次将垂直度因素引入相邻体运动关系矩阵中,提高了空间误差表征的准确度,使得工件和刀具之间理论误差关系式更加贴近实际并验证了误差矩阵中误差项,该方法同样适用其它类型机床误差分析。     

基于内置传感器的数控机床动态加工误差测量方法

以HJ044双转台型五轴联动数控机床为例,以机床内置传感器信息和多体系统理论为基础,建立了刀具相对工件的运动学模型,提出了一种基于内置传感器信息的动态加工误差测量方法。该方法利用机床编码器或光栅尺等机床内置传感器信息获取机床各轴运动位移,并结合机床运动学模型,测量由机床的动态特性引起的加工误差。并通过实验表明该方法是一种简单有效的数控机床动态加工误差测量方法。     

数控5轴龙门机床的虚拟加工系统开发

针对新研制的龙门移动式数控5轴车铣复合机床XKA2780结构复杂,已有成熟虚拟加工系统灵活性差,必须要系统厂家深度开发方能实现的问题,文章提出了一种灵活可控的虚拟加工方法,首先基于大型工程软件开发平台ACIS/HOOPS,采用组件结构树的建模方法,建立了机床各组件之间的运动学关系并开发了相应的运动控制模型;其次通过扫描包络技术研究了刀具扫描包络体生成算法;然后以刀具轨迹为引导,将生成的刀具扫描包络体与工件进行布尔运算,实现了仿真环境中工件的虚拟切削;最后,通过对典型航天零部件的加工代码仿真和现场机床切削试验,验证系统的可靠性。实践结果表明,该系统可以对加工代码进行有效验证,且运动控制可兼容各种构型数控机床。     

An accurate,efficient envelope approach to modeling the geometric deviation of the machined surface for a specific five-axis CNC machine tool

Geometric deviation, defined as the difference between the nominal surface and the simulation model of the machined surface, is the fundamental concern of five-axis tool path planning. Since the machined surface is part of the cutter envelope surface generated by the cutter motion, it is necessary to calculate the envelope surface in order to obtain the geometric deviation. In the stage of tool path planning, current approaches calculate the cutter envelope surface by using the cutter motion along the given tool path. However, the cutter motion of practical machining on a specific five-axis CNC machine tool is different from the given tool path. Moreover, the computation is very challenging when the accurate cutter motion of practical machining is applied to calculate the envelope surface. To overcome these two problems, a geometric envelope approach with two major distinctions is proposed in this paper. First, the envelope surface of the cutter undergoing a general motion is efficiently obtained as a closed-form vector expression. Second, the accurate cutter motion, which is determined by machine kinematic and interpolation scheme in practical machining, can be easily applied to calculate the accurate envelope surface. With the envelope surface, the geometric deviation is calculated to estimate the overcut or undercut in five-axis milling. An example is given to demonstrate the validity of the proposed method.     

高速内冷铣孔空蚀机理的数值模拟与实验研究

目的预测高速内冷铣孔过程中空蚀的发生,并初步揭示高速内冷铣削过程中铣刀空蚀失效机理及已加工工件表面的空蚀损伤机理。方法采用三维数值分析与实验相结合的方法,在建立高速内冷铣削封闭流场的基础上进行数值计算,搭建了高速内冷空蚀试验平台并进行实验,通过粗糙度仪对分段后工件样条的已加工表面进行测定,通过电子显微镜对实验后的分段工件样条已加工表面和铣刀形貌进行分析。结果仿真分析发现用40 mm立铣刀以14500 r/min转速铣削60 mm 50 mm孔时,流场中的含气率达到10%左右,预测了高速内冷铣削过程中空蚀现象的存在,空蚀后楔形发散区的孔壁粗糙度Ra为0.311~0.478 m,楔形收缩区的孔壁粗糙度Ra为0.138~0.317 m。工件已加工表面出现麻点和海绵状为主的空蚀针孔,铣刀侧后面出现蜂窝状和鱼鳞状的空蚀坑。结论仿真分析和实验共同验证了高速内冷铣削过程中空蚀现象的存在,空蚀位置可能出现在内冷铣刀侧后刀面及部分工件已加工表面,且铣刀侧后刀面空蚀程度远超工件已加工表面,为高速内冷切削加工过程中空蚀机理的研究提供依据。     

端铣加工面尺寸误差预测

为了精确预测端铣加工面尺寸误差,利用铣削动态力卷积模型,引入表面生成窗概念,并考虑到工件与刀具的变形误差、机床空间误差与刀具偏摆的影响,建立了加工面尺寸误差预测模型。通过在铣床上进行实验,验证了该模型能够正确预测工件尺寸误差及其分布范围,且在铣刀轴向切深、主轴转速和进给速度一定的情况下,增加径向切深不会对工件尺寸误差产生显著影响。     

螺旋锥齿轮端铣加工刀位计算方法

针对螺旋锥齿轮在数控加工中心上加工效率低的问题,提出利用盘状铣刀对螺旋锥齿轮进行端铣的加工方法.由螺旋锥齿轮齿面及刀具的几何特征,调整铣刀与被加工齿面的相对位置,使齿面与刀具包络面的法截面相对法曲率最小,增大切削带宽,同时控制刀轴矢量调整切削深度避免加工干涉.最后将规划的加工刀位转化到数控机床轴上,利用VERICUT进行加工仿真验证该方法的可行性与正确性.     

燃汽轮机缸体倾斜孔数控铣削加工参数化编程

在机械加工中,常会遇到与机床主轴不垂直的空间大斜孔系的铣削加工。在三轴联动的数控镗铣床上,采用万向角度铣头改变机床主轴方向,使孔轴线与铣刀轴线一致,运用空间几何建立各加工变量之间的数学模型,实现空间斜孔铣削加工数控程序参数化。结果表明:只需一次装卡工件,赋予相应变量值,就可完成孔系的加工。该方法的加工精度高,省工省力,可推广到类似空间斜面、倾斜槽的加工。     

A study of back cutting surface finish from tool errors and machine tool deviations during face milling

The surface finish of mechanical components produced by face milling is given by factors such as cutting conditions, workpiece material, cutting geometry, tool errors and machine tool deviations. The contribution of the different tool teeth to imperfections in the machined surface is strongly influenced by tool errors such as radial and axial runouts. The surface profile of milled parts is not only affected by chip removal due to front cutting, but also by back cutting, which must be taken into account when predicting surface roughness. In the present work, the influence of back cutting on the surface finish obtained by face milling operations is studied. Final part surface roughness is modelled from tool runouts and height deviations that affect the surface marks provoked by back cutting. Round insert cutting tools and surface positions defined by cutter axis trajectory are considered, and milling experiments are developed for a spindle speed of 750 rpm, depth of cut of 0.5 mm and feeds from 0.4 to 1.0 mm/rev. Experimental observations are compared with the theoretical predictions provided by the surface roughness model, and good agreement is found between both results. Surface imperfections caused by front and back cutting are analysed, and discrepancies between experiments and numerical predictions are explained by undeformed chip thickness variations along the tool tooth cutting edge, the tearing of the workpiece material, and fluctuations in the feedrate and height deviation during machine tool axis displacement.     

Modelling and simulation of chatter in milling using a predictive force model

A predictive time domain chatter model is presented for the simulation and analysis of chatter in milling processes. The model is developed using a predictive milling force model, which represents the action of milling cutter by the simultaneous operations of a number of single-point cutting tools and predicts the milling forces from the fundamental workpiece material properties, tool geometry and cutting conditions. 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. Runge–Kutta method is employed to solve the differential equations governing the dynamics of the milling system for accurate solutions. A Windows-based simulation system for chatter in milling is developed using the predictive model, which predicts chatter vibrations represented by the tool-work displacements and cutting force variations against cutter revolution in both numerical and graphic formats, from input of tool and workpiece material properties, cutter parameters, machine tool characteristics and cutting conditions. The system is verified with experimental results and good agreement is shown.     

Prediction of cutting forces in milling of circular corner profiles

This paper proposes an approach to predict the cutting forces in peripheral milling of circular corner profiles in which varying radial depth of cut is encountered. The geometric relationship between an end mill and the corner profile is investigated and a mathematical model is presented to describe the different phases of the cutter/workpiece contact. The milling process for circular corner is discretized into a series of steady-state cutting processes, each with different radial depth of cut determined by the instantaneous position of the end mill relative to the workpiece. A time domain analytical model of cutting forces for the steady-state machining conditions is introduced to each segmented process for the cutting force prediction. The predicted cutting forces can be calculated in terms of tool/workpiece geometry, cutting parameters and workpirece material property, as well as the relative position of the tool to workpiece. Experiments are conducted and the measured forces are compared to the predictions for the verification of the proposed method.     

Virtual EDM simulator: Three-dimensional geometric simulation of micro-EDM milling processes

In this paper a three-dimensional geometric simulation method of micro-EDM milling processes is proposed, which introduces a Z-map algorithm to precisely represent the geometries of a machined workpiece and the evolution of the tool shape caused by tool wear during the machining. The micro-EDM milling process is mathematically and geometrically modeled. In order to verify the performance of the developed simulator, an actual square cavity is machined and compared to the simulation result. The developed EDM simulator can be used for tool path generation for tool wear compensation as well as for prediction of tool wear.