复杂曲面加工干涉避免及轨迹的规划

对复杂曲面进行分析,通过调节后跟角和摆动角来避免刀具与被加工曲面发生干涉,并提出了复杂曲面五坐标数控加工刀具轨迹的规划算法,以改善曲面加工精度和加工效率。     

自由曲面数控加工路径规划的研究

论述了自由曲面数控加工路径规划对加工效率的影响,讨论了目前刀具轨迹算法的优缺点。针对自由曲面走刀方向数控加工的研究,建立了简化的刀具轨迹时间模型,并对路径规划的系统进行了讨论。     

复杂参数曲面高精度刀具轨迹规划算法

在对等残余高度刀具轨迹规划算法加工参数曲面研究的基础上,提出带有误差补偿值的复杂参数曲面高精度刀具轨迹规划算法——高精度刀轨误差补偿算法。通过分析刀触点及与之相应的相邻路径上的粗、精刀位对应点间的关系,引入误差补偿值以提高精对应刀位点的求解精度,得到经过合理简化的误差补偿值表达式,并得出粗、精对应刀位点与理论刀位点的距离误差表达式。高精度刀轨误差补偿算法可以在满足插补运算实时性要求的前提下,使相邻轨迹上与刀触点相对应的刀位点的参数值计算精度得到极大提高,进而提高复杂参数曲面的加工刀具轨迹精度。以使用平底铣刀为例进行仿真加工,结果表明高精度刀轨误差补偿算法适合进行对复杂参数曲面的高精度加工。     

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。     

五轴数控加工光滑无干涉刀具路径的规划措施

五轴数控加工技术的关键就在于路径的规划,在于如何更好地回避刀具与工件的干涉,本文从复杂曲面五轴刀具路径规划的角度入手,分析了五轴数控加工中干涉的分类,提出了五轴数控加工光滑无干涉刀具路径规划的主要措施,主要集中在优化刀具形状以及优化刀具轨迹算法这两个方面,从而确保了加工效率和加工精度。     

裁剪NURBS组合曲面精加工方法

从工程实际应用出发,提出一种适合裁剪ＮＵＲＢＳ组合曲面整体加工的精加工截平面刀具轨迹生成算法,根据曲面的形状规则一组满足加工精度的平面,与裁剪ＮＵＲＢＳ曲面的等距面求交,在截面上对交线进行排序、妆和裁剪等处理,生成无干涉刀具轨迹。解决了组合曲面加工编程中曲面之间存在断开、裂缝、局部搭接现象的刀具轨迹生成问题,实践表明,算法速度快、稳定性好。     

数控铣削加工曲面刀具轨迹的规划

分析自动编程加工曲面的刀具轨迹,综合刀具轨迹编辑处理方法,阐述了曲面加工中刀具轨迹的规划,提出了如何将三轴刀具轨迹转化成五轴刀具轨迹的原理,为五轴刀具路径的获得提供了一种新途径.     

基于定向距离理论的五轴加工刀具轨迹规划算法

针对环形刀五轴加工自由曲面的残留误差问题,在传统等残留高度算法的基础上,提出了一种基于定向距离理论的等最大残留高度刀具轨迹规划算法。首先根据微分几何理论计算已知刀触点的初始侧向行距,并在侧向行距方向进行偏置得到相邻刀触点;然后以基于定向距离理论的残高误差计算模型对相邻刀触点间的实际残高值进行计算;最后通过迭代计算规划出等最大残留高度的相邻刀具轨迹。如此循环,从而获得整个曲面的刀具轨迹。实验结果表明,相对于商用软件MasterCAM9.0,该算法在充分保证曲面加工质量的同时最大限度地减小了刀具轨迹的总长度,从而提高了加工效率。     

基于刀具实际廓形的数控加工刀具轨迹计算

刀具轨迹生成是自由曲面零件数控加工中最重要同时也是研究最为广泛深入的内容,在自由曲面的多坐标数控加工中,刀具轨迹的优劣直接影响其加工精度和加工效率。传统的刀具轨迹计算方法是利用实际刀具的理想廓形进行的,提出利用刀具的实际廓形进行复杂曲面加工,是通过检测旋转刀具加工工件时的实际廓形,利用实际廓形对已知曲面进行刀具轨迹计算。这种计算方法能有效的提高加工精度,并可以检测新生产出来的刀具是否符合标准。该方法适用于加工刀具为旋转运动的数控加工轨迹计算。     

曲面磁力抛光刀具路径规划与驻留时间算法研究

复杂曲面的自动抛光加工方法与效率一直是困扰模具曲面加工的难题,将磁力抛光与数字化测量、控制技术相结合,可以较好地解决曲面抛光加工的效率与自动化问题。参考数控加工理论,对自由曲面加工的刀具轨迹以及轨迹生成算法进行了分析,重点探讨了抛光刀具的驻留时间控制算法。     

一种用于多面体加工的圆弧刀轨生成算法

为提高多面体模型的加工效率,提出了一种用于多面体加工的圆弧刀轨生成算法。采用截平面和多面体模型的等距模型求交来计算初始直线刀轨;由等距模型的顶点曲率估算刀位点处沿刀轨方向和刀轨间隔方向的曲率半径,并根据残留高度确定刀轨行距。提出了基于刀位点曲率半径调节的圆弧拟合算法,算法引入拟合约束条件和曲率半径调节系数;在拟合精度范围内,迭代确定曲率半径调节系数,从而确定拟合圆弧。实验结果表明文中方法生成的刀轨保持G1连续且包含的圆弧段数量较少,有利于提高加工效率。     

A Surface Based Approach for Constant Scallop HeightTool-Path Generation

The machining of sculptured surfaces such as moulds and dies in 3-axis milling relies on the chordal deviation, the scallop height parameter and the planning strategy. The choice of these parameters must ensure that manufacturing surfaces respect the geometrical specifications. The current strategies for machining, consist primarily in driving the tool in parallel planes which generates a tightening of the tool paths. A constant scallop height planning strategy has been developed to avoid this tightening. In this paper, we present a new method of constant scallop height tool-path generation based on the concept of the machining surface. The concept of the machining surface is developed and its use to generate constant scallop height tool paths is described. The approach is compared with existing methods in terms of precision and in particular its aptitude to treat curvature discontinuities.     

Non-redundant tool trajectory generation for surface finish machining based on geodesic curvature matching

The increasing complexity of surface has put forward higher demands for CNC machining trajectory generation. The constant scallop height method has the disadvantage of point redundancy during trajectory discretization. Therefore, a non-redundant tool trajectory generation method for surface finish machining is put forward. The cutting row spacing is determined by the geodesic curvature according to scallop height and the convexity or concavity of the local surfaces. The adjacent cutter contact (CC) points with constant scallop height are expressed point by point from the present CC point. The redundant points are removed by maximizing each cutting step length through making the chord error equal to the machining allowable error. The dual NURBS ruled surface is constructed to realize smooth transition of the tool trajectories and tool axis vector. The prototype system taking ACIS R13 and HOOPS V11.0 as modeling kernel has been developed to verify the proposed method. The experiment results proved that the proposed method can realize non-redundant tool trajectory considering tool interference during surface finish machining.     

A CL surface deformation approach for constant scallop height tool path generation from triangular mesh

In this paper, we present a cutter location (CL) surface deformation approach for constant scallop height tool path generation from triangular mesh. The triangular mesh model of the stereo lithography (STL) format is offset to the CL surface and then deformed in accordance with the deformation vectors, which are computed by the slope and the curvature of the CL surface. In addition, the tool path, which is computed by slicing the deformed CL surface, is inversely deformed by those same deformation vectors to a tool path with a constant scallop height. The proposed method is implemented, and a tool path is generated and tested by simulation and by numerical control (NC) machining. The scallop height was found to be constant over the entire machined surface, demonstrating much better quality than that of mesh slicing, under the same constraints for machining time.     

EQUIVALENT NORMAL CURVATURE APPROACH MILLING MODEL OF MACHINING FREEFORM SURFACES

A new milling methodology with the equivalent normal curvature milling model machining freeform surfaces is proposed based on the normal curvature theorems on differential geometry. Moreover, a specialized whirlwind milling tool and a 5-axis CNC horizontal milling machine are introduced. This new milling model can efficiently enlarge the material removal volume at the tip of the whirlwind milling tool and improve the producing capacity. The machining strategy of this model is to regulate the orientation of the whirlwind milling tool relatively to the principal directions of the workpiece surface at the point of contact, so as to create a full match with collision avoidance between the workpiece surface and the symmetric rotational surface of the milling tool. The practical results show that this new milling model is an effective method in machining complex three- dimensional surfaces. This model has a good improvement on finishing machining time and scallop height in machining the freeform surfaces over other milling processes. Some actual examples for manufacturing the freeform surfaces with this new model are given.     

一种新的数控加工刀位迹排列算法的研究

提出一种基于密切曲率法的刀位轨迹预拉优化算法，使相邻加工轨迹同的残留高度值都等于预定的精度，从而达到最大的切削带宽，在保证精度的前提下，大在提高了数控加工的效率。     

Iso-scallop tool path generation in 5-axis milling

This paper presents a new method of computing constant scallop height tool paths in 5-axis milling on sculptured surfaces. Usually, iso-scallop tool path computation methods are based on approximations. The attempted scallop height is modelled in a given plane to ensure a fast computation of the tool path. We propose a different approach, based on the concept of the machining surface, which ensures a more accurate computation. The machining surface defines the tool path as a surface, which applies in 3- or 5-axis milling with the cutting tools usually used. The machining surface defines a bi-parametric modelling of the locus of a particular point of the tool, and the iso-scallop surface allows to easily find iso-scallop tool centre locations. An implementation of the algorithms is done on a free-form surface with a filleted end mill in 5-axis milling.     

一种新的数控加工刀位轨迹排列算法的研究

提出一种基于密切曲率法的刀位轨迹预控优化算法 ,使相邻加工轨迹间的残留高度值都等于预定的精度 (残留高度值 ) ,从而达到最大的切削带宽 ,在保证精度的前提下 ,大大提高了数控加工的效率     

等残留高度法加工椭球面的刀具轨迹算法

鉴于采用等间隔参数法和截面法加工椭球面零件时存在残留量不均匀、表面质量和加工效率不高等缺点,提出采用等残留高度法原理加工椭球面。推导了该方法的加工刀具轨迹算法,并采用VB编程实现了该算法,生成了NC加工程序。加工结果表明,该方法可以满足光学自由曲面的加工精度要求。