实体模型的三轴数控粗加工刀轨生成算法

提出一种适合实体模型的三轴数控粗加工刀位轨迹生成算法。首先根据加工行距作一组平行于刀轴的平面，与模型的待加工表面求交，得到一系列交线；再根据精度规划一组垂直于刀轴的分层平面，与上述交线求交，在每一分层平面上判断加工区域，规划出加工刀位轨迹，将每一分层平面上的刀位轨迹较适当的方式连接起来，就构成零件的整体加工轨迹。该算法避免了轮廓环等距、自交处理和布尔运算等复杂的计算过程；同时，对生成开型腔的加工刀位轨迹也是有效的。     

型腔高速铣削刀轨生成算法研究

在常规的环切刀轨生成算法基础上，设计了型腔高速铣削加工刀轨生成算法．对刀轨的拐角进行了平滑处理，实现了相邻刀轨环之间的光滑曲线过渡，避免了刀具运动方向的急剧变化，可使切削性能得到改善．     

数控车削中等轮廓切削加工轨迹的生成与优化

一、引言在数控车削加工中，由于车削余量较大，需多次走刀才能完成粗加工。根据零件毛坯形状（棒料、锻件和铸件）和零件表面轮廓形状，具体的走刀路线可分为纵向切削循环、横向切削循环和等轮廓切削循环三种方式。其中等轮廓切削循环方式适合了表面轮廓具有复杂或凸凹变化较大的零件，其加工轨迹的生成主要涉及轮廓的等距线生成问题。目前常用的等距线生成算法有多种，传统的算法有Voronio图算法和干涉标志法，它们都是针对二维半锐8林工的，而数控车削加工中等距线的生成有其自身的特点：门）所处理的轮廓多为开放轮廓；门）要求能有效…     

测点数据生成刀具路径研究

为了提高反求加工的效率，提出由大规模测点数据直接生成粗、精加工刀具路径的算法．粗加工采用层切法分层切削材料，首先构造健壮的数据结构——层切网；然后计算无干涉刀位点，并把整个层切网划分为几个优化的子加工区域；最后应用优化的刀路链接法则得到粗加工刀具路径．精加工由大规模数据点构建三角曲面．为了避免干涉，需计算点、面和边的无干涉刀位点．实验结果表明，粗加工刀具路径算法具有较高的效率，只需要占用较小的内存空间；精加工可以成功地避免干涉并且获得可靠的表面精度．     

三角网格表面等残留高度刀轨生成算法

针对截平面法规划的三角网格表面的刀轨长度较长、加工表面残留高度不均匀的问题,提出一种基于改进截平面法的等残留高度刀轨生成算法.首先在估算刀触点轨迹线垂直方向曲率半径的基础上,计算刀触点轨迹投影线并对其进行修正,去除其中冗余的投影点;然后由修正后的刀触点轨迹投影线构造驱动表面,利用驱动表面和网格表面迭代计算刀触点轨迹线;最后由刀触点轨迹线计算无干涉刀轨.与截平面法生成的刀轨进行比较分析的结果表明,文中算法生成的刀轨长度较小且获得的残留高度保持均匀,适合于三角网格表面表示的复杂表面的精加工.     

数控刀位轨迹的新算法

CAM中的一个关键技术就是数控刀位轨迹的生成。本文在HANSEN[1]提出的干涉标志量概念及算法基础上，提出了新的理论观点及相应的新算法。新算法用在研制的美术造型图案模腔自动加工成型系统即GNC统中，几年来运行验证效果一直良好。     

基于Z-map模型的自由曲面无干涉刀具轨迹生成算法研究

刀具轨迹生成是自由曲面零件数控加工中重要的研究内容.本文分析了自由曲面数控加工中常用的刀具轨迹生成策略和方法,设计和实现了一种基于Z-map结构的自由曲面无干涉刀具轨迹生成算法.本算法采用进化算法进行刀具干涉检测,不仅解决了生成刀具轨迹时因走刀步长不合理而产生的过切问题,而且也确保了生成的刀具轨迹为无干涉刀具轨迹.     

轮廓平移无跳刀连接刀路环树优化算法

提出一个无跳刀的轮廓平移刀路轨迹优化算法．根据刀路环之间父环和子环关系，提出“刀路环树”的概念，将加工刀路的一次环切定义为一个“刀路环向量”，并将刀路环的各个属性定义为刀路环向量的分量．根据无跳刀轨迹的要求，针对刀路环树的各个刀路环向量进行遍历，以获得了一个无跳刀的轮廓平移刀路轨迹算法，并通过与其他算法比较，证明该算法无跳刀、无重复切削，并且可以自动执行．     

皮革裁切加工算法

给出了用直刀、圆弧刀冲切皮革的加工算法．根据裁切方向和轮廓特点，分别给出两种轨迹计算方式．第一种直接采用等误差逼近计算直刀刀位，第二种则采用等误差、等步长相结合的逼近方式来计算直刀、圆弧刀组合刀位，其间通过在刀具库中搜索合适刀具和绕刀具自身轴心摆转来避免过切．最后用Improved Greedy—opt2算法对冲孔轨迹进行路径优化，给出了加工实例，取得了满意的效果。     

基于三角Bezier曲面的粗加工数控编程

在反求工程设计中,采用三角Bezier曲面对散乱点数据进行曲面重构有许多优点。文中探讨了适合曲面及型腔加工的、基于三角Bezier曲面模型的粗加工数控编程技术,提出了多种粗加工毛坯的定义方法,针对不同毛坯提出具有特色的变切深均匀厚度分层及等切深曲面跟踪分层等粗加工方案,解决了刀具轨迹的规划与计算,使之达到实用要求,推动了三角Bezier曲面模型在工程制造领域中的应用。     

Computing of the actual shape of removed material for five-axis flat-end milling

This paper describes an algorithm that predicts the shape of material removed by a flat-end milling tool, and this may be used to compute machining strip width and scallop height at different positions of the tool path track. The algorithm computes swept sections, profiles which are swept by a moving tool bottom by passing through given planes. The technique is applicable for finish and semi-finish multi-axis milling strategies that use flat-end tools. For these strategies, the algorithm complexity can be reduced from computation of the 3D envelope of swept volumes to computation of plane-circle intersections. A new adaptive derivative-free method to sample tool motion provides robust means to generate intermediate tool positions. The step length is constrained by and dependent on different geometrical measures. At each point of a tool path, in the plane perpendicular to the cutting direction, the bottom profile of the swept section is an estimate of the profile of material left. By calculating the distance between part geometry and the computed profile of removed material, machining strip width and a scallop profile can be derived. These results can be used by tool path generation and validation routines to accurately determine the step-over between tool path tracks and surface quality.     

Tool path regeneration for mold design modification

This paper proposes a novel mold modification tool path regeneration algorithm for three-axis CNC machining based on ball end-mills. It utilizes the existing tool path points that have been generated for the original mold design prior to modification. With the proposed algorithm, a closed profile of the tool path points for the boundary of the modified region is first calculated. It is proven that if the boundary of the mold modification is interference-free, only the tool path points inside this boundary are affected by the mold modification. The tool path points that are outside the boundary can be reused to machine the modified mold. When the affected tool path points are detected, they are removed and replaced by the new tool path points. The scallop height values for the modified region are then checked. If the scallop height is greater than the given value, more CL points are added to this region to maintain the required surface finish. The algorithm has been tested on several industrial parts, and it is proven to be efficient and robust. The generated new tool path is interference-free and meets the required surface finish.     

A smooth spiral tool path for high speed machining of 2D pockets

We introduce a new algorithm for generating a spiral tool path for high-speed machining of pockets without islands. The pocket may be an arbitrary simply-connected 2D shape bounded by straight-line segments and circular arcs. The tool path is generated by interpolating growing disks placed on the medial axis of the pocket. It starts inside the pocket and spirals out to the pocket boundary. The tool path is guaranteed to be free of self-intersections and allows machining of the pocket without tool retractions. The start point of the spiral may be chosen freely by the user anywhere within the pocket. Most importantly, the spiral tool path complies with a user-specified maximum cutting width. The output of our algorithm is a G¹-continuous spiral path. However, in a post-processing step, a properly adapted variant of the recent “PowerApx” package [Heimlich M, Held M. Biarc approximation, simplification and smoothing of polygonal curves by means of Voronoi-based tolerance bands. International Journal of Computational Geometry & Applications 2008;18(3):221-50] can be used to boost the tool path to C²-continuity. Our new algorithm was implemented and tested successfully on real-world data. We conclude our paper by an analysis of sample tool paths produced by our implementation.     

基于局部搜索和遗传算法的激光切割路径优化

为了缩短激光加工时间,提高加工效率,提出了一种新的局部搜索法与遗传算法相结合的激光切割路径优化算法。该算法从加工轮廓中提取节点,通过局部搜索法对节点进行局部路径优化,再运用的遗传算法求得近似最优解,遗传算法中的选择算子改进为基于相对适应度的轮盘赌选择算子。详细介绍了算法的原理及实现,通过编程仿真证明该算法与传统的遗传算法相比具有良好的优化效果,可明显缩短加工路径,减少加工时间,提高加工效率。     

密集型多轮廓裁片的刀具空行程路径寻优

服装行业中缩短刀具裁剪空行程对于高效裁剪布料具有重要意义。结合服装裁片排列具有轮廓形状复杂、分布密集的特点,将问题转化成广义旅行商问题。 基于最大最小蚁群(MMAS)算法提出了一种新的用于裁片刀具空行程路径寻优的算法--密集多轮廓蚁群算法,该算法包括4步:1)用MMAS算法确定初步裁片顺序;2)由裁片顺序寻找各裁片入刀节点;3)将各裁片的入刀节点再次用MMAS进行顺序优化重组得到初步裁剪路径;4)反复迭代第2)步和第3)步以求得最优路径。实验验证了所提算法的有效性,对比现有的扫描算法以及双信息素蚁群(NACS)算法其结果分别提升了60.15%和22.44%,该算法在刀具空行程优化上具有明显优势。     

Rough and finish tool-path generation for NC machining of freeform surfaces based on a multiresolution method

Progressive fitting and multiresolution tool path generating techniques are proposed in this paper, by which multi-level (LOD) models fitting for different subsets of sampled points are obtained, and then multiresolution rough-cut and finish-cut tool paths are generated based on the LOD models. The advantages of the proposed method are: (1) the user need not care for data reduction in CAD modeling; (2) final result is obtained by interpolating two lower-level reconstructed surfces, and each lower multiresolution CAD representation can be used to generate rough-cut tool paths; (3) different manufacturing requirements utilize different level models to generate tool paths; (4) selective refinement can be applied by interpolating selceted areas at different levels of details. The key avantage of the prograssive fitting algorithm is that it can use different level surfaces to generate adaptive rough-cut and finishi-cut tool path curves directly. Therefore, based on the proposed techniques, tool path length is reduced. Sharp concers are smothed out and large tools can be selected for rough machining. The efficiency of this algorithm has been demonstrated, and it results in a 20% reduction in machining time.     

A Minimum Risk Approach for Path Planning of UAVs

In the last years, the Flight Mechanics Research Group of Politecnico di Torino started a wide research activity, focused on exploration and implementation of path planning algorithms for commercial autopilots, typically adopted on unmanned vehicles. Different path planning approaches were implemented in a Matlab/Simulink based tool, generating waypoints sequences with four methods: geometric predefined trajectories, manual waypoints definition, automatic waypoints distribution (i.e. optimizing camera payload capabilities) and, finally, a comprehensive A*-based approach. The tool was also integrated with functions managing the maps used for planning. In this paper, two approaches to path planning in presence of orographic obstacles are detailed. The first algorithm is subdivided in three phases: the generation of a risk map associated with the ground orography, the transformation of the map in a digraph analyzed with the A* algorithm (to obtain the path with minimum risk/minimum distance) and finally the smoothing phase, to obtain a flyable waypoint sequence, realized with the Dubins curves. The structure of this method was defined and implemented, but its optimization is still in progress. The second algorithm is based on the same risk map, but optimizing polynomial curves with a genetic algorithm. This method produces a flyable waypoints sequence, minimizing a cost function reflecting path length and collision risk. An extension of this path solver, including aircraft performance constraints, was also considered. This method was tested on sample domains and its computational cost has still to be evaluated before the implementation in the tool.