An algorithm for generating spiral tool path of shoe last with varying pitch

In shoe-last high-speed numerical machining, the key step is to generate CNC machining tool path by data sampled from the shoe last rapidly and accurately. By analyzing the characteristics of helical line and the model of the shoe last expressed in cylindrical-polar coordination system, an algorithm for generating spiral tool path of shoe last with varying pitch was presented. By sample data interpolation, mathematic models with different pitch of helical line were built, and the tool paths with different machining parameters were determined. The effectiveness is verified by the emulation and experimental results represented in the paper.     

类回转体曲面数控加工刀位轨迹规划

针对类回转体曲面高速进给数控加工,提出螺旋线驱动方式下圆环刀具加工轨迹的规划方法。构造螺旋线作为类回转体曲面的导动线,根据曲面上已知接触点轨迹的切线方向估算后续导动点对应的初始接触点。计算初始接触点处圆环刀具的刀心位置,再计算初始刀心位置与后续导动点对应的目标刀位点分别在圆周方向以及轴向的距离差值,利用相邻刀位点与相邻接触点存在的准相似关系,得到接近目标接触点的搜索方向和步长,经过迭代得到目标接触点和刀位点。在分析接触点处曲面曲率和圆环刀曲率的基础上,给出圆环刀加工误差计算方法。将所提出的算法用于鞋楦的五轴数控轨迹规划中,计算结果表明,该算法搜索效率较高,具有理论和实际应用价值,并通过鞋楦的五轴数控加工试验验证了算法的有效性。     

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。     

以Pro/E和MasterCAM为基的鞋楦反求与仿真加工

运用Pro/E逆向技术,对鞋楦原始点云进行处理,并运用小平面建模和重新造型的方法重构鞋楦曲面,完成鞋楦实体模型的构建,然后将实体模型导入MasterCAM软件仿真加工。由于鞋楦为不规则的回转体,故采用四轴加工方法,完成鞋楦的仿真。所做的反求为鞋楦数据的保存和网络化制造提供了支持,同时仿真加工验证了鞋楦模型实际加工的可行性。     

复杂曲面环形刀五轴端铣加工的刀具轨迹规划方法

为了降低复杂曲面类零部件加工的刀具路径,减小刀具路径条数,提高加工效率,提出了一种新的复杂曲面环形刀五轴端铣加工刀具轨迹优化方法。在局部可铣性基础上对刀轴矢量角进行自适应优化,采用新型加工带宽计算方法——等残留高度算法,给出了等残留高度算法的刀具轨迹生成具体步骤。仿真结果表明:与传统等残留高速算法相比,刀具轨迹优化算法的刀具路径更短、条数更少,能够有效提高复杂曲面加工效率。     

型腔边界拐角精加工刀轨生成算法的研究

在识别粗加工余料区域的基础上,从均匀径向切削深度、平滑刀轨路径等方面考虑,研究并实现了型腔边界拐角处的精加工刀轨生成算法。采用将拐角区域加工分为多个循环进行渐进切削的策略,可减小径向切深。同时,每一切削循环内切削段和空程刀轨段、各循环之间均采用圆弧过渡,刀轨路径满足一阶连续,从而可减小切削力的变化幅度和方向突变,提高加工精度。     

Computer-aided process planning for NC tool path generation of complex shoe molds

This paper presents a computer aided process planning (CAPP) system for numerical control tool path generation of complex shoe molds. This CAPP system includes both the automation of auxiliary boundary curve generation and machining strategies. The automation of auxiliary boundary curve generation and machining strategies make tool path generation more accurately and efficiently. Traditional shoe mold making is a very tedious process. Even with the utilization of computer-aided design and computer-aided manufacturing (CAD/CAM), the CAM process requires long hours of tool path programming and debugging. It would also take a long time to calculate (sometimes several hours) the tool path for complex athletic footwear. In order to reduce the tool path editing and programming time, this paper proposes the use of CAPP to reduce processing time and increase efficiency. It is difficult, if not impossible, to develop a generic CAPP system that can generate a process plan to solve general production problems. However, it is quite possible to capture the domain knowledge of a certain production process and embed that knowledge into a CAPP system. We prove, by using such a system, that a very complicated process planning problem can be overcome by a knowledge-based CAPP approach. With such an approach, the traditional manufacturing process of shoe molds can be converted to an automatic manufacturing process with the CAPP system. In fact, shoe molds for real production have been created using the developed CAPP system, demonstrating the effectiveness of this approach. In this paper, we show that several complex and different shoe molds and their machining strategies were automatically planned by the proposed CAPP system. The result of a comparison between the CAPP system with the traditional approach is presented and discussed.     

五轴加工刀具路径生成的有效加工域规划方法

为复杂曲面五轴数控加工的刀具路径优化生成问题提出一种新的有效加工域规划方法。在对工件被加工表面和刀具的几何特征进行分析的基础上,得到在加工件表面上各处的最优可加工域宽度和刀具切削方向。通过采用离散采样和插值计算生成优化的有效加工域集,得到最优化的初始刀具路径;同时建立一种迭代搜索算法,用于解决最优加工域的选择规划问题。采用此算法生成优化的后续刀具路径,使得有效加工域最终完全覆盖整个被加工表面。给出的示例显示相对于传统的五轴加工刀具路径生成算法,有效加工域规划方法可以减少刀具路径的总长度和加工时间,得到更为优化的刀具路径和更好的工件表面质量,因此有效加工域规划方法可以被用于五轴数控加工实践以降低加工成本和提高产品质量。     

航空发动机叶片5轴联动铣削加工刀路规划方法

针对航空发动机叶片形状复杂、加工精度高的特点,在ACIS几何平台上采用截平面法进行刀轨规划,变步长法控制加工精度,刀轴矢量自动调整法避免干涉,反变形补偿法控制加工变形,实现了叶片主面及阻尼台无干涉加工,并开发了航空发动机叶片五轴铣削加工计算机辅助软件.与通用CAM软件相比,该软件具有针对性强、操作简单、走刀路径更优化、对阻尼台的加工处理更方便等优势.     

自由曲面数控加工刀具轨迹映射算法

对自由曲面的数控加工,寻求最优的刀具轨迹生成方法至关重要。本文基于开源3D库Open CASCADE(OCC)和编程开发环境Microsoft Visual Studio 2010(VS2010),应用B样条表达的自由曲面,采用“投影法”思想,研究“重用已有相似刀具路径”方法,提出了处理自由曲面的NC刀具轨迹映射算法。为了验证算法的有效性和可行性,实验建立5类自由曲面,启动设计的轨迹映射算法,输出曲面的NC加工轨迹质量可以满足设计要求,实现了刀具轨迹的重用。     

B-spline tool offset of a free-form curve in the shoe last high-speed machining CNC system

Aiming at the special requirements of a shoe last high-speed machining process and the large dataset which could be gained by the reverse engineering technique, this paper analyzes the conventional tool-offset methods and presents a B-spline tool-offset model. A simple vector-analyzed algorithm to smooth the tool-offset curve in which there are local strange points is proposed, and then the second tool-offsetting, which obtains the fine data of the machining tool’s center points, is directly processed. To reduce the error from tool offsetting of the C2 continuity curve, this paper gains a smoother curve after processing via the edge points joint algorithm, which effectively solved the overcut or undercut problems in the high-speed machining of the spline curve.     

Research on tool path planning method of four-axis high-efficiency slot plunge milling for open blisk

The great mass of machining allowance for blisk is removed in the rough milling, so improving the rough machining efficiency for the blisk’s tunnel is the key of realizing high-efficiency machining of blisk. According to the structure characteristic of open blisk’s tunnel, a four-axis plunge slot rough milling with high-efficiency and low machining cost is advanced. First, the plunge slot process for blisk and the generation process of the ruled enveloping surface for the freeform surface of the blisk’s blade are put forward. Then, the generating method of the ruled enveloping surface for the blade’s freeform surface and the tool path generation method of four-axis plunge slot milling for blisk are studied. The rough milling region of open blisk’s tunnel is determined by generating the ruled enveloping surface of blade’s offset surface, and the algorithm of tool path for four-axis plunge milling is given. When using a ruled surface to approach a freeform surface, the problem of getting boundary is solved, and the error from the calculation of tool path is avoided by the algorithm. At last, the experiment shows that comparing to the traditional side slot milling, the cutting force of four-axis plunge milling can be reduced by 60% and even the rough machining efficiency can be increased to more than double.     

对称多型腔粗加工刀轨快速生成算法

对具有对称特性的多型腔零件的刀轨规划方法进行了研究，提出了一种新的算法：首先生成其中一个型腔的刀轨，然后通过阵列生成其余刀轨，并对刀轨的进退刀进行处理，从而快速生成完整的、连续的、有序的刀具轨迹。该算法尤其适用于高速加工的刀轨规划，实践表明，可大大提高编程效率．节省加工时间。     

NC machining of free-form Kriging surfaces

An algorithm for three-axis NC tool path generation on sculptured surfaces is introduced when the free-form surface is modeled parametrically by free-form surface Kriging. The flexibility of dual Kriging that easily defines the intersection of the surfaces with a set of parallel planes and Cartesian method are combined to generate the tool-paths automatically. The presented algorithm can simultaneously generate the tool path with a predefined machining accuracy and remove gougings along the tool path. The algorithms are validated by three experiments in rough and finish machining and the results prove its reliability. Since Kriging is based on the interpolation of data points, the proposed algorithm can be used for reverse engineering applications. The system was executed on a standard micro-computer and the software was structured to offer a library of machining functions for endusers.     

A manufacturing model of helical groove on rotary burr and a universal post processing method

A systematic machining theory and precision method to determine cutter location in a grinding system is presented for rotary burr. First, the helical cutting edge on various kinds of revolving surfaces is built. Then, based on the geometry model of the helical cutting edge, the smooth spiral rake surface with constant normal rake angle and flank surface can been formed during the one-pass grinding process by this method. No interference between the grinding wheel and workpiece happens by the wheel special rotation. The method has the characteristic of detaching the grinding wheel path solution from specified machining conditions. The grinding wheel path is suitable for different NC machine tools through post processing. Meanwhile, a mechanism kinematic model of the NC machine tool is built, and a generalized algorithm for post-processing of multi-axis NC machine tools is presented. This model is applied to arbitrary configuration of NC machine tool, and the motion value for each axis will be generated by the inputting structure and motion parameters of the machine tool. The model, together with the machining method mentioned in this paper, make the calculation and generation of the grinding wheel path simpler and universal. At last, the validity of the method given in the paper is identified by an example of grinding.     

基于Z-Buffer理论的三坐标无干涉刀位轨迹的生成

针对当前无干涉刀位轨迹生成算法存在的问题，提出一种基于Z-Buffer理论的用于三坐标加工的无干涉刀位轨迹生成算法。该算法已成功地应用于洗衣机波轮、水轮机叶片等复杂曲面零件的NC加工。实践证明该算法具有可行性，计算方法简单，并且能很好地解决干涉问题，对于在三坐标加工中的刀位轨迹生成具有很高的实用价值。     

细分曲面数控加工关键技术

对三角域和四边域细分曲面数控加工的关键技术做了讨论,包括细分曲面数控加工模型的建立,粗加工模型的包围网格生成算法,NC刀轨生成常用的两种方法,精加工模型的等距网格求解算法及等距误差控制方法,给出了应用实例;指出了解决细分曲面数控加工技术实用化问题需要进一步研究的内容。     

基于CAD/CAM软件的鞋楦逆向设计与制造

本文运用CAD/CAM软件—Geomagic Studio、CimatronE,以鞋楦逆向设计为实例,论述了点云处理、错误修复、曲面生成的方法,对样品鞋进行逆向设计及数控加工程序编制,提出了一套完整的鞋楦逆向设计及数控加工的方法,并为模具设计提供了建构复杂曲面模型的有效途径。     

An efficient five-axis machining method of centrifugal impeller based on regional milling

This paper presents an efficient five-axis machining method of centrifugal impeller based on regional milling. As the base of the machining method, geometry of the centrifugal impeller and blade surface is analyzed, and sub-machining regions are presented through the division of the double three-cubic d non-uniform rational B-spline (NURBS) surface. In rough milling, the cutter parameters, tool path interval, tool path curves, and the fixed tool axis vector are calculated by the novel algorithm based on regional milling; the biggest cutter and smaller tool path length are obtained. In finish milling, for the aerodynamic performance of the finished impeller, the tool path curves are modified and interlinked to make them uniform and orderly. A modified algorithm of the finish milling of the blade surface is proposed, and not only are the machining errors reduced; their reasonable distribution is also realized. Numerical simulation and a real test impeller are presented as the test of the proposed method.     

基于遗传算法的笔式加工刀具路径优化

为缩短笔式加工时间和提高加工效率,提出了一种新的基于遗传算法的刀具路径优化方法。笔式加工的特点决定了生成的刀具路径为一系列离散的切削路径段,为了精简搜索数目,将每段刀具路径看作两个遗传基因。使用十进制码构造分段染色体模型,采用改进的遗传算法对笔式加工分段路径进行优化排序,得到刀具路径排布的近似最优解。实验结果表明:改进的自适应遗传算法比一般遗传算法搜索速度提高若干倍,可以明显缩短加工路径的总长度。