共查询到20条相似文献,搜索用时 15 毫秒
1.
为选取合适的加工刀具尺寸以对自由曲面实现无曲率干涉加工,提出了改进遗传算法并应用于自由曲面全局最大主曲率求取,确定无曲率干涉最大刀具尺寸.根据主曲率特点设计了一种新的非线性自适应度函数,避免算法过早收敛于局部最优值,并给出了新的复制原则.改进遗传算法应用算例分析表明,该算法在500代内能有效求取自由曲面全局最大主曲率,比传统的离散法效率高,选择的最大刀具尺寸满足自由曲面加工无曲率干涉加工的要求. 相似文献
2.
Yuyao Li Jingchun Feng Yuhan Wang Jianguo Yang 《The International Journal of Advanced Manufacturing Technology》2009,40(7-8):769-775
To alleviate the feed fluctuation and to maintain a smooth feed in conventional five-axis machining, an optimal feed interpolation algorithm (look-ahead) is proposed. However, the problem arises where the segment usually cannot be interpolated exactly in an integer period because of the nonzero joint feed at the junction. To overcome this problem, and to achieve faster machining speed and higher quality parts, this paper presents an optimal feed interpolation algorithm for high-speed, five-axis machining having the function of “look-ahead”, i.e., variable-period linear interpolation algorithm. In real applications, the proposed algorithm results in: (1) constant speed; (2) high machining accuracy. Moreover, in this paper, an efficient method for acceleration and deceleration control is presented to achieve the highest-quality feed profiles and to shorten machining times. The precision and speed of machining is improved greatly. Experimental results verify the effectiveness of the proposed method. 相似文献
3.
《计算机集成制造系统》2015,(6)
针对由离散刀位点数据生成的五轴加工等距非均匀有理B样条曲线刀具路径中两条非均匀有理B样条曲线参数不同步的问题,建立了一种等距双非均匀有理B样条曲线参数的同步模型,实现等距双非均匀有理B样条曲线刀具路径插补过程中两条非均匀有理B样条曲线参数的同步运动。将三轴非均匀有理B样条曲线插补算法应用于五轴加工等距双非均匀有理B样条曲线刀具路径中的刀具中心点非均匀有理B样条曲线,根据参数同步模型将插补算法同步到刀轴点非均匀有理B样条曲线中。仿真表明,采用该算法能够使刀具始终沿着等距双非均匀有理B样条曲线刀路进行同步插补,参数同步插补精度主要集中在10-6 mm级数上,适用于复杂曲面的五轴加工。 相似文献
4.
Iso-parametric tool path generation from triangular meshes for free-form surface machining 总被引:2,自引:2,他引:2
Sun Yuwen Guo Dongming Jia zhenyuan Wang Haixia 《The International Journal of Advanced Manufacturing Technology》2006,28(7-8):721-726
The polyhedral model is widely used in the manufacturing industry. However, apart from the iso-planar method, the tool path
generation methods for polyhedral machining are very limited. In such a case, the given tool paths are no longer boundary-conformed
or efficient. This paper presents a new approach to iso-parametric tool path generation for triangular meshes. The strategy
proposed herein first parameterizes the triangular faces via a harmonic map. The cutter-contact (CC) points and the path interval
are then calculated based on the machining tolerance requirements and the iso-parametric tool paths are finally generated.
The method is implemented on a computer and some illustrative examples are provided to show the effectiveness of the developed
algorithm. The main advantage of the proposed method is that the tool paths can be generated naturally along the boundary
of a polyhedral model, thus eliminating internal tight-radius corners in conventional paths. This leads to substantial reductions
of tool wear and machining time. In addition, the proposed method can also be used in other non-iso-parametric tool path planning
methods for triangular meshes and compound surfaces machining. 相似文献
5.
Behnam Moetakef Imani Amirmohammad Ghandehariun 《The International Journal of Advanced Manufacturing Technology》2011,56(5-8):619-629
Various methods for parametric interpolation of non-uniform rational B-spline (NURBS) curves have been proposed in the past. However, the errors caused by the approximate nature of the NURBS interpolator were rarely taken into account. This paper proposes an integrated look-ahead algorithm for parametric interpolation along NURBS curves. The algorithm interpolates the sharp corners on the curve with the Pythagorean-hodograph (PH) interpolation. This will minimize the geometric and interpolator approximation errors simultaneously. The algorithm consists of four different modules: a sharp corner detection module, a PH construction module, a feedrate planning module, and a dynamics module. Simulations are performed to show correctness of the proposed algorithm. Experiments on an X?CY table confirm that the developed method improves tracking and contour accuracies significantly compared to previously proposed algorithms. 相似文献
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Liqiang Zhang Jingchun Feng Yuhan Wang Ming Chen 《The International Journal of Advanced Manufacturing Technology》2009,40(11-12):1191-1201
In free-form surface machining, it is essential to optimize the feedrate in order to improve the machining efficiency. Conservative constant feedrate values have been mostly used up to now since there was a lack of physical models and optimization tools for the machining processes. The overall goal of this research is the integration of geometric and mechanistic milling models for force prediction and feedrate scheduling in five-axis CNC free-form surface machining. For each tool move, the geometric model calculates the cut geometry, and a mechanistic model is used along with a maximum allowable cutting force to determine a desired feedrate. The results are written into the part NC program with optimized feedrates. When the integrated modeling approach based feedrate scheduling strategy introduced in this paper was used, it was shown that the machining time can be decreased significantly along the tool path. 相似文献
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Rong Shean Lee Shuo Peng Liang 《The International Journal of Advanced Manufacturing Technology》2006,28(11-12):1136-1145
In spline-based free-form surface machining, segmented toolpaths are inevitable, and the discontinuities between segments cause large feedrate errors in the generated motion commands. Methods of the geometric design to create smooth composite curves may introduce new error sources in the original curve, and thus they are not suitable for motion planning in high precision free-form surface machining. In this paper, a strain energy minimization model (SEMM) and a non-uniform rational B-spline (NURBS)-based motion planning algorithm is proposed for free-form surface machining. The proposed SEMM and motion planning algorithm are capable of creating composite NURBS-based motion curves with up to C2 integral continuity without oscillations. Results from simulation show that with the proposed energy minimization model and motion curve generation algorithm, the feedrate errors caused by discontinuities in toolpaths can be effectively removed. 相似文献
10.
High-performance machining of free-form surfaces is highly critical in automotive, aerospace, and die–mold manufacturing industries. Therefore, electrochemical machining (ECM) process has been used in such cases in that sense. The most important challenges of using ECM process are the lack of accuracy and difficulty in designing proper machining tool (cathode) surfaces. In this article, a simplified mathematical model is presented to obtain a cathode surface for ECM of free-form surfaces which have high curvatures. In this theoretical approach, the finite-element method (FEM) is used to solve the 3-D Laplace equation and to determine the potential distribution between the anode (workpiece) and cathode (tool) surfaces. A compact and simple program was developed to obtain a proper cathode surface that only requires some nodal coordinates on the anode surface and boundary conditions. In this work, a trial cathode surface is constructed for a given gap distance. For the determined ECM parameters, cathode shape that satisfies the boundary conditions is obtained for the 45th layer. The results are compared with the literature and ANSYS Workbench for verification. The developed theoretical approach benefits simpler and faster FEM solutions, accurate cathode surface, and consequently correct form of machined surface. 相似文献
11.
Abbas Vafaeesefat 《International Journal of Precision Engineering and Manufacturing》2010,11(2):327-333
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. 相似文献
12.
提出一种新的刀具轨迹优化算法,使相邻加工轨迹间的残留高度值都等于允许残留高度值(规定精度),从而达到最大的切削带宽,消除了干涉。同时采用刀位显示验证方法对加工某叶片模型所得到的刀具轨迹进行验证。实验数据表明,在保证精度的前提下,轨迹数和轨迹长度明显减少,大大提高了多轴联动数控加工的效率。 相似文献
13.
多轴联动数控加工刀具轨迹的优化算法的研究和实验验证 总被引:1,自引:0,他引:1
提出一种新的刀具轨迹优化算法,使相邻加工轨迹间的残留高度值都等于允许残留高度值(规定精度),从而达到最大的切削带宽,消除了干涉.同时采用刀位显示验证方法对加工某叶片模型所得到的刀具轨迹进行验证.实验数据表明,在保证精度的前提下,轨迹数和轨迹长度明显减少,大大提高了多轴联动数控加工的效率. 相似文献
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在分析弧面凸轮轮廓曲面上加工刀痕产生的原因,以及对分度机构性能影响的基础上,提出了用NURBS样条插补凸轮从动件运动规律曲线的思想方法.通过对NURBS样条插补改进算法的深入分析,得出了进一步校正满足加工步长条件的NURBS样条参数增量的算式.同时对插补前弧面凸轮从动件运动规律曲线的修正、NURBS插补误差和插补过程的实现进行了计算与分析.结果表明,采用文中给出的方法,能显著提高弧面凸轮轮廓面的加工精度. 相似文献
17.
为提高最短距离计算的精度、效率和稳定性,提出了一种计算点到曲面最短距离的网格法。该方法首先利用曲面上给定的一点作为初始点,以该点为中心按给定步长将曲面划分为四个网格区域;然后分别计算空间点与初始点以及四个网格中心的距离,选取其中最小的距离作为最短距离,并得到相应网格中心;最后以该中心作为初始点,步长减半,重复以上步骤,从而获得满足一定精度的最短距离。分别以两个复杂曲面为计算实例,通过对所提方法与其他方法的计算结果进行比较,验证了该方法的有效性。 相似文献
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J. Jeong Dr K. Kim 《The International Journal of Advanced Manufacturing Technology》1998,14(12):876-881
Voronoi diagrams for closed shapes have many practical applications, ranging from numerical control machining to mesh generation. Curve offsetting based on Voronoi diagrams avoids the topological problems encountered in the traditional offsetting algorithms. In this paper, we propose a procedure using Voronoi diagram-based tool-path generation for machining pockets with free-form boundaries. A pocket can be bounded by 2D free-form curve elements that are differentiable twice. The procedure consists of three steps:
相似文献
1. | Segmentation of a free-form pocket boundary. |
2. | Construction of the Voronoi diagram for the pocket boundary. |
3. | Generation of the tool path for machining the pocket using the Voronoi diagram. |