Tool path generation method for multi-axis machining of helical milling cutter with specific cross-section profile

The geometry of helical milling cutter with specific cross-section profile is normally generated with form cutter by the toolpath generating method. The general purpose CAD/CAM software can generate the cutter location file of this class of product only by the sculpturing method. To obtain the flexibility of machining process, this paper presents an interference-free toolpath generating method for semi-finish and finish machining of the helical milling cutter. The method for design and machining of the helical milling cutter is established based on the differential geometry and the enveloping theory. In the finish machining of helical milling cutter, the form grinding wheel profile is firstly derived. To reduce the cost and lead time of the generating method with the form-mill cutter for semi-finish machining, a toolpath generating method which combines the advantages of the generating method and sculpturing method was presented. The cutter location uses ball-nose conical end mill is derived according to the geometric characteristics of the enveloping element. The cutting simulations with solid model were performed to verify the proposed toolpath generation method.     

空间凸轮廓面侧铣加工及最小二乘优化刀位方法

通过对空间凸轮非等价加工方式下理论刀轴轨迹曲面微分几何特性的研究，表明加工空间凸轮工作廓面必然存在法矢异向误差。为寻求加工误差最小的最佳刀轴矢量，提出了数控侧铣加工空间凸轮廓面的方法。根据实际刀轴轨迹面是直纹面的性质，以NURBS直纹面重构理论刀轴轨迹面，采用最小二乘优化方法确定侧铣加工刀位，给出了理论加工误差模型，并通过实例的数值计算和加工实验结果证明了该方法的有效性。     

A generating method for digital gear tooth surfaces

Based on the theories of digital conjugate surface and gear meshing, a generating method for digital gear tooth surfaces (DGTS) is demonstrated in this paper. The research focuses on the conjugate motion between the DGTS, represented by discrete points, and the cutter figuration determined by analytic function in the manufacture process. Conjugate points in the cutter section corresponding to the discrete points on the digital surface and conjugate movements are solved. Automated sequence arrangements of the generating movement parameters have been performed and the discrete generating movements are interpolated in a continuous conjugate motion along the order. Strategies of error analysis and error compensation are also discussed in this paper. Computer-simulated examples of the generating machining of involute DGTS and non-standard shaped DGTS, the parameters of machining motions and real tooth surfaces verify the developed method. The research develops a new idea for the machining of DGTS, which breaks the limitations of conventional approaches based on analytic surfaces. It is of important theoretical and practical value to manufacture digital surfaces. Our method is not only be applicable in generating machining of discrete DGTS and analytic gear tooth surfaces with complex geometric design, but also in contributing to the processing of discrete digital cam and other 3-D digital surfaces .     

弧面分度凸轮的非等径数控加工自动编程

弧面分度凸轮廓形的非等径加工自动编程,能够及时有效地补偿刀具尺寸的变化,保证加工精度,降低刀具费用.文章介绍了在三轴联动数控机床上加工弧面分度凸轮时,非等径加工刀具轴线的确定、编程坐标换算和自动编程应用程序框架,并给出了非等径加工程序实例.     

B样条列表曲线直线插补的自适应算法

给出了一种根据零件加工精度要求,对三次Ｂ样条列表曲线进行直线插补,自动生成变步长刀位轨迹的算法,简称自适应算法。该算法当列表曲线曲率大时,使步长变小,反之使步长变大,同时使逼近误差满足要求。该算法稳定、可靠,便于在列表曲线、列表曲面的数控加工中推广应用。     

圆柱凸轮类零件的设计及加工

在SolidWorks环境下,利用包覆特征实现了任意圆柱凸轮三维建模的方法和步骤,并在Motion插件中模拟仿真运动,仿真正确后导入CAXA制造工程师软件中生成四轴加工的数控程序。以余弦圆柱凸轮为例讲解了整个过程,为圆柱凸轮类设计及加工提供了通用的解决方法。     

Machining and dimensional inspection of spatial cams on 5-axis machine tools

An analytical methodology is developed for NC data generation to produce and measure spatial cams on 5-axis machine tools. The Denavit-Hartenberg notation is used for expressing the ability function of the employed machine tool and in the generation of the desired cutter/measuring-probe location. NC data equations are determined by equating the corresponding elements of the machine tool's ability function to the desired tool location matrices. To validate this methodology, a designed cam was machined and its surfaces were measured by an online measurement system equipped with a touch-trigger probe on a 5-axis machine tool. The resultant cutting speed and material-removal rate during machining are also investigated. This methodology is a general one and is applicable to various spatial cams. It also combines the activities of design, manufacturing, and measurement, thus making the production process more flexible, automatic, and controllable.     

基于Pro/E的空间分度凸轮精确建模与加工

建立了空间分度凸轮的从动滚子中心线轨迹方程,利用Pro/Engineer软件提供的“方程式”和“加厚”功能,生成凸轮的理论廓线,实现了空间分度凸轮的三维数字化精确建模.采用Pro/NC模块的4轴轨迹加工方式对凸轮沟槽进行数控加工与模拟,提高了空间分度凸轮数控加工的精度和效率.     

基于包络特征的非圆齿轮齿廓计算方法研究

依据齿条刀具范成法加工非圆齿轮的原理,建立了计算机仿真加工中的刀具与齿坯间运动学模型;通过对仿真齿条刀具加工中齿廓形成过程的分析,提出了一种基于齿廓特征点的齿廓描述方法;根据齿廓的形成规律,提出了齿廓特征点、齿根圆、齿根过渡曲线和齿顶圆等全部齿廓数据的计算算法,并利用该算法编写了椭圆齿轮齿廓计算程序,该程序可直接用于线切割等数控加工设备加工。采用该方法设计加工出的椭圆齿轮已成功应用于所研制的插秧机分插机构样机及其试验台中,从而验证了该方法的可行性。     

弧齿线圆柱齿轮全修形齿面的CNC修形加工方法

针对弧齿线圆柱齿轮全修形齿面的修形控制问题,提出一种在展成加工的同时对齿廓和齿线两个方向进行修形控制的加工方法。通过调整直刃刀盘的展成运动回转半径,实现齿面齿廓方向的修形量控制;通过调整刀倾角,实现齿面齿线方向的修形量控制。基于空间运动学原理,利用矢量旋转公式,在具有倾角的数控机床上与普通多轴联动数控机床上展成加工齿面时,保持刀具和工件的相对位置和相对运动相同,进行两类机床之间的运动转换,建立机床运动控制方程,从而实现弧齿线圆柱齿轮在普通多轴联动数控机床上的修形加工。并通过试件的切削试验和齿面接触分析试验,证明所提出的修形加工方法和分析的加工运动方程的正确性。与弧齿线圆柱齿轮传统的加工方法相比,这种加工方法效率高,运动关系简单,便于推广应用。     

基于极坐标的空间曲线刀心轨迹算法与自动编程实现

介绍了鞋楦的造型方法和数控加工原理,分析了鞋楦加工的刀位计算原理和加工拟合误差,提出了一种基于极坐标的空间曲线的无干涉刀心轨迹生成方法,该算法有效地解决了加工中出现的欠切削及法矢干涉等问题以及在极坐标情况下自动编程所出现的特殊问题,本算法适于各种空间曲线的环切加工。     

大型螺旋曲面5轴旋风式数控铣削技术

基于5轴卧式特制数控铣床,提出了一种旋风式铣削技术。该技术实时调整旋风式铣刀回转面的曲率方向,使其与被加工曲面的曲率密切贴近,极大地增加刀具在被加工曲面上的扫描面积,可显著提高切削效率和节省加工时间。重点分析了螺旋曲面的几何特性、5轴卧式特制数控铣床坐标系的运动关系、旋风式铣削的数学原理和刀位方程等有关问题。     

混联数控机床虚拟加工系统的研究与开发

针对混联机床加工过程中干涉检查、空间刀具半径补偿及编程难等问题,分析了混联机床运动学逆解,提出了一种空间任意面内的刀具半径补偿方法,给出了干涉检查的判断条件。以V is-ual C++为开发环境,应用AutoCAD二次开发工具ObjectARX,建立了由NC代码驱动的混联数控机床加工仿真系统,实现了以真实加工条件为依据的加工过程实时动态模拟,预估加工的过程和结果,为检查NC代码的正确性提供了可靠的依据。     

Generation of collision-free cutter location data in five-axis milling using the potential energy method

In five-axis milling, optimal cutter location data (CL-data) should be generated to have advantages over three-axis milling in terms of accuracy and efficiency. This paper presents an algorithm for generating collision-free CL-data for five-axis milling using the potential energy method. By virtually charging the cutter and part surfaces with static electricity, global collision as well as local interference is eliminated. Moreover, machining efficiency is simultaneously improved by minimising the curvature difference between the part surface and tool swept surface at a cutter contact point (CC-point).     

从测量的散乱数据点云直接生成数控刀具路径的研究

提出了一种直接从测量的散乱数据点云用球头刀对自由曲面进行三轴数控加工时生成刀具路径的方法。不同于现有散乱点云基于逆向工程的刀具路径生成方法,本法考虑并估计了曲面加工误差和粗糙度。将散乱数据点云向XY平面投影,以获得的投影边界为刀具路径的主方向,然后根据曲面所需的加工误差和残留高度要求划分该投影数据点云,得到一系列刀位网格单元。通过最小化每个刀位网格单元的加工误差以确定每个刀位网格的节点位置,加权平均相关联刀位网格节点来对齐相邻刀位网格单元的边缘。为了缩短加工时间,裁去刀位路径上多余的线段,最终生成高效合理的数控加工刀具路径。已用实测的数据点云验证了本法直接生成刀具路径的有效性。     

利用CAD/CAM系统设计与加工空间凸轮

为获得优良的运动特性和动力特性,空间凸轮设计较之一般产品设计,其轮廓曲面要求较高精度.因此,本文着重论述了如何利用CAD/CAM系统设计空间凸轮,以及在完成空间凸轮的建模后,如何利用CAD/CAM系统中的曲面分析功能分析空间凸轮3D模型,并介绍了基于CAD/CAM系统利用3D模型进行数控加工编程的方法.空间凸轮CAD和数控加工的关键问题是如何将从动件的运动规律转换为凸轮轮廓.本文以常见的圆柱凸轮为例,利用Pro/E软件实现了圆柱凸轮的3D设计与数控加工.     

奥利康摆线齿锥齿轮铣刀盘刀齿刃磨方法及加工仿真

根据磨轮与刀齿型面的接触条件,提出了奥利康摆线齿锥齿轮铣刀盘条形刀五轴刃磨加工的刀位点计算方法。利用Vericut软件构建了虚拟机床模型和加工环境,进行条形刀五轴刃磨仿真,验证了刀位点和NC代码的正确性。     

弧面凸轮侧铣加工刀轨的空间线性回归分析

为减小弧面凸轮非等径加工存在的法矢异向误差,根据空间线性回归算法的NURBS直纹面生成原理,寻求加工误差最小的刀轴矢量,进行初步拟合。通过迭代逼近减小初始刀轴矢量误差,将刀轴作为NURBS直纹面母线来重构理论刀轴回归轨迹面。利用最小二乘法进行进一步优化,建立了弧面凸轮侧铣加工刀轨误差优化模型,提出了求解该优化模型的一种实数编码的人工免疫算法。以左旋弧面凸轮进行矢量数值计算和仿真,验证了该算法的有效性。     

Multi-cutter selection and cutter location (CL) path generation for five-axis end-milling (finish cut) of sculptured surfaces

This paper presents an optimization method for planning five-axis end milling (finish cut) of sculptured surfaces with multi-cutters. Compared to single-cutter machining, the application of multi-cutters can produce much shorter cutter location (CL) paths and, hence, reduce the machining time. The work presented in this paper focuses on the selection of an optimal multi-cutter set that is utilized to finish different regions of a design surface, followed by the generation of CL paths for each region/cutter combination. The planning starts by identifying all the feasible cutters that form all the possible multi-cutter sets by evaluating their accessibility. The candidate multi-cutter sets are then extracted by maintaining every cutter's cutting region sufficiently large. Based on a proposed method for machining time estimation without generating the tool path, the optimal multi-cutter set with the best cutting efficiency is selected. The iso-planar CL paths are then generated for the cutters in the optimal set for machining their allocated surface regions. Examples are given to show the validity and robustness of the developed methods.     

圆柱分度凸轮单侧面加工及误差计算方法研究

应用空间啮合原理和旋转变换矩阵理论，推导了圆锥滚子从动件圆柱分度凸轮的理论工作廓面方程及单侧面加工凸轮实际工作廓面方程；廓面采取单侧面加工时，给出了刀具误差对凸轮廓面法向误差影响的精确计算方法和近似计算方法，解决了空间凸轮廓面误差计算的难题，进一步完善了圆柱分度凸轮机构的设计和制造理论。