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《计算机集成制造系统》2016,(10)
为进一步改善数控加工曲面的表面质量,提出一种针对三角网格曲面的螺旋刀具数控加工轨迹规划方法,在充分考虑刀具轨迹的几何与动力学特性以及三角网格单元特性的基础上,有效减少了抬刀次数,保持了刀具轨迹的连续性。该方法从网格边界轮廓曲线上的刀触点开始逐层偏置,在参数域上对刀触点进行规划,并拟合成螺旋轨迹,将其逆映射到网格曲面上得到螺旋加工轨迹。与传统的截面法和环切法相比,该算法可以生成一条具有边界一致性、轨迹光滑连续的、无需多次进退刀的高质量螺旋加工轨迹。 相似文献
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针对曲面高速高精度加工问题,给出一种刀位点轨迹实时生成算法。该方法的实现包括曲面上离散刀触点的生成和基于三次非均匀B样条曲线的刀位点轨迹实时高精度拟合两部分。第一部分,由导动曲线和刀触点轨迹的运动学关系,通过计算导动曲线参数,间接得到投影在曲面上的离散刀触点;第二部分,通过合理参数化、构建模长因子等实现刀位点参数曲线的分段实时拟合。仿真实例表明该算法简单易于编程,曲线拟合精度高,适用于自由曲面笔式加工中刀具路径计算与生成,从而满足复杂曲面高性能数控加工需求。 相似文献
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基于参数曲面映射的五轴数控螺旋加工轨迹计算方法 总被引:2,自引:0,他引:2
采用五轴数控机床进行高速加工时,加工干涉及曲面转角处的突变会造成刀轴矢量剧烈变化,而采用传统的退刀再进刀的方法又难免导致加工效率及质量的降低.针对上述问题,提出一种新颖的适用于五轴高速加工的刀具路径生成算法.该方法由偏微分方程的热传导模型,计算得到映射参数域内满足加工参数的温度等值线,制定映射规则并在标准参数域内规划出加工轨迹,从而在对应参数域内映射生成螺旋轨迹,并将该轨迹映射到参数曲面上获得曲面的螺旋加工轨迹,该轨迹可以实现无退刀加工.采用上述算法进行了仿真,仿真结果表明该方法优于现有加工方法,可实现基于参数曲面及裁剪曲面的复杂型腔的高速加工. 相似文献
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利用平面Hilbert填充曲线生成方法简单、易于控制填充疏密的优点,将其用于了自由曲面数控加工刀具路径的生成.对平面Hilbert填充曲线的生成原理进行了研究,用矩阵运算的方法生成该曲线.结合自由曲面的形成过程,提出将平面Hilbert曲线通过与曲面参数域相对应的方法映射到曲面上,进而生成加工刀具路径的思想.最后用一个具体应用实例验证了生成平面Hilbert曲线方法的正确性,和用此曲线作为数控加工刀具路径的可行性.通过与经典刀具路径生成方法比较可见该方法具有算法简单,加工余量均匀,加工效率与表面质量高的优点. 相似文献
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针对复杂多曲面通道的多坐标数控粗加工,提出了一种新的刀具轨迹生成算法.该算法以传统的插铣加工方法为基础,提出适合于复杂多曲面通道的新插铣方法;利用曲面参数线,使用B样务曲线正算反算方法,在流道划分的多个截面上做由初始孔到截面轮廓的渐变曲线;通过计算满足残留高度的走刀行距,在各个截面的渐变曲线上提取参数点并拟合出相应曲线,进而得到刀具接触点轨迹. 相似文献
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曲面参数线法是多轴数控加工中生成刀具轨迹的主要方法,但是对等参数曲线分布不均匀的情况不适应.平头端铣刀在数控多轴加工中相对于球头枕刀来说,有加工精度高、经济性好的特点,其刀具轨迹的生成方法越来越引起人们的注意.本文针对曲面参数线法的缺点作了相应的改进,提出了适应平头端铣刀的刀具轨迹生成算法,同时用局部检查的方法进行干涉校验,消除了局部干涉.本算法适应于三轴联动以上的机床。 相似文献
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曲面参数线法是多轴数控加工中生成刀具轨迹的主要方法,但是对等参数曲线分布不均匀的情况不适应。平头端铣刀在数控多轴加工中相对于球头铣刀来说,有加工精度高,经济性好的特点,其刀具轨迹的生成方法越来越引起人们的注意。本文针对曲面参数线法的缺点作了相应的改进,提出了适应平头端铣刀的刀具轨迹生成算法,同时用局部检查的方法进行干涉校验,消除了局部干涉。本算法适应于三轴联动以下的机床。 相似文献
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基于矩阵运算描述生成平面Hilbert曲线的方法简单,易于编程实现,将其进行了正确的空间矢量化,应用于了曲面加工刀具轨迹的生成.分析了矩阵变化描述曲线的思想,结合曲面加工刀具轨迹的计算过程,提出将平面Hilbert曲线通过与曲面参数域相对应的方法映射到曲面上,进而生成加工刀具路径的思想.建立了二者之间的映射关系,构建了... 相似文献
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Combined reparameterization-based spiral toolpath generation for five-axis sculptured surface machining 总被引:1,自引:0,他引:1
Fei Ren Yuwen Sun Dongming Guo 《The International Journal of Advanced Manufacturing Technology》2009,40(7-8):760-768
Reparameterization-based toolpath generation methods are usually adopted for machining triangular meshes, trimmed surfaces and compound surfaces. The quality of the reparameterization has an important effect on that of the surface. In this paper, a combined reparameterization procedure is introduced to generate an optimal mapping between the designed surface and a specified planar circular region with relatively less distortion both in length and in angle. Then, for five-axis sculptured surface machining the mathematical model of spiral guide path with maximum path interval is constructed in the circular region. Cutter contact paths are obtained by inversely mapping the guide path onto the designed surface. Under constraints of gouging and collision, continuous and optimal cutter orientations are subsequently calculated. Finally, the results of simulation and experiment of the machining process are given to illustrate the feasibility and applicability of the proposed method. 相似文献
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Travis F. Schraeder Rida T. Farouki 《The International Journal of Advanced Manufacturing Technology》2014,73(1-4):195-208
Experimental results from the implementation of an inverse dynamics compensation scheme on a three-axis CNC mill with an open-architecture software controller are presented. The scheme amounts to imposing a continuously variable displacement on the commanded toolpath, which compensates for the physical limitations (inertia and damping) of each machine axis, producing accurate execution of the prescribed toolpath. Numerical values for the dimensionless parameters that characterize the second-order inverse dynamics model are determined by feeding input and output data from machine runs into a system identification software tool. For a basic P-type controller, exact a priori solutions for the modified path geometry are possible, allowing implementation by simple alterations to the real-time interpolator. The experimental results based on a P-type controller indicate that the inverse dynamics scheme is highly effective in suppressing both feed (lag/lead) error and contour error (deviation from the desired path), even at high feedrates along strongly curved toolpaths. The scheme thus provides a practical means of achieving smooth and accurate execution of free-form paths, without appealing to more complicated “active” control strategies. 相似文献
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Jinting Xu Yuwen Sun Xiangkui Zhang 《The International Journal of Advanced Manufacturing Technology》2013,67(9-12):2489-2500
Almost 80 % of the milling operations to produce mechanical parts are produced by NC pocket milling, especially in aerospace and automobile industry. At present, for 2.5D pocket machining, direction-parallel and contour-parallel machining strategies have gained nearly universal acceptance. However, in such tool path, abrupt change of path direction, frequent acceleration and deceleration, and sharp velocity discontinuous are found to significantly limit the machining efficiency of pockets. To address these problems, this paper introduces a method for generating a spiral tool path that maintains a steady-state cutting process by as smoothly as possible curvature evolution of the tool path for pocket machining. First, the machined region of a layer of a pocket is mapped onto a circular domain by means of mesh mapping, which reduces the task of tool path generation from the geometrically complex pocket region to a topologically simple disk. On this disk, a guide spiral is constructed according to a mathematical function constrained by the calculated path interval map. Using the mapping from the pocket to the disk as a guide, the guide spiral is inversely mapped into the interior of the pocket and then a smooth low-curvature spiral path is derived. The generated tool paths are guaranteed to not inherit any corners in the subsequent interior tool paths and allows cutting of the pocket without tool retractions during the cutting operations. Finally, the proposed method is implemented and tested on several typical sample pockets to demonstrate its validity and significance. 相似文献
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数控车削加工仿真技术的研究 总被引:6,自引:0,他引:6
研究了数控车削仿真的关键技术。根据数据车削加工过程的特点,实现了加工轨迹仿真,加工过程实时仿真和加工过程的干涉碰撞检查,探讨了数控车削NC坐标信息处理方法,对数控车削仿真系统中文本和图形显示进行了开发,提出了实现各种刀具轨迹仿真的可行算法。 相似文献
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As a flexible forming technology, Incremental Sheet Forming (ISF) is a promising alternative to traditional sheet forming processes in small-batch or customised production but suffers from low part accuracy in terms of its application in the industry. The ISF toolpath has direct influences on the geometric accuracy of the formed part since the part is formed by a simple tool following the toolpath. Based on the basic structure of a simple Model Predictive Control (MPC) algorithm designed for Single Point Incremental Forming (SPIF) in our previous work Lu et al. (2015) [1] that only dealt with the toolpath correction in the vertical direction, an enhanced MPC algorithm has been developed specially for Two Point Incremental Forming (TPIF) with a partial die in this work. The enhanced control algorithm is able to correct the toolpath in both the vertical and horizontal directions. In the newly-added horizontal control module, intensive profile points in the evenly distributed radial directions of the horizontal section were used to estimate the horizontal error distribution along the horizontal sectional profile during the forming process. The toolpath correction was performed through properly adjusting the toolpath in two directions based on the optimised toolpath parameters at each step. A case study for forming a non-axisymmetric shape was conducted to experimentally validate the developed toolpath correction strategy. Experiment results indicate that the two-directional toolpath correction approach contributes to part accuracy improvement in TPIF compared with the typical TPIF process that is without toolpath correction. 相似文献
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Stephen J. Ludwick David A. Chargin Joseph A. Calzaretta David L. Trumper 《Precision Engineering》1999,23(4):253-259
We have developed a novel fast tool servo and associated prototype diamond- turning machine for the production of plastic spectacle lenses. Our fast tool servo carries the cutting tool on a rotary arm and, thus, on a circular path, as opposed to straight line paths in conventional designs. The actuator, sensors, and bearings are standard elements that together allow experimentally demonstrated 500 m/s2 instantaneous accelerations at the tool tip over a 3-cm range of cutting depth. We also describe in this paper new approaches we have developed for toolpath generation and calibration. The paper also presents associated control algorithms, because the controller must supply very high dynamic stiffness to the tool servo axis at multiples of the spindle frequency. This stiffness is achieved by means of repetitive control techniques. The new fast tool servo is shown to have great promise for machining asymmetric surfaces with large amplitude asymmetries. 相似文献
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吴福忠 《计算机集成制造系统》2007,13(10):2064-2070
为提高自由曲面数控加工的切削效率,改善刀具的受力状态,提出了一种自由曲面三坐标加工等间距刀具路径规划方法.分析了在实际加工过程中可采用的几种刀具路径规划方法及其实现等距加工的约束条件.研究了等间距刀具路径的计算方法,并针对计算过程中出现的逼近误差校验和刀具路径延伸与裁剪问题给出了解决方法.对等参数线法和等距截面法进行了比较,表明应用该方法规划自由曲面刀具路径,可提高走刀路径对曲面形状变化的适应性和切削行间距分布的均匀性. 相似文献
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A new accurate curvature matching and optimal tool based five-axis machining algorithm 总被引:2,自引:0,他引:2
Than Lin Jae-Woo Lee Erik L. J. Bohez 《Journal of Mechanical Science and Technology》2009,23(10):2624-2634
Free-form surfaces are widely used in CAD systems to describe the part surface. Today, the most advanced machining of free
from surfaces is done in five-axis machining using a flat end mill cutter. However, five-axis machining requires complex algorithms
for gouging avoidance, collision detection and powerful computer-aided manufacturing (CAM) systems to support various operations.
An accurate and efficient method is proposed for five-axis CNC machining of free-form surfaces. The proposed algorithm selects
the best tool and plans the toolpath autonomously using curvature matching and integrated inverse kinematics of the machine
tool. The new algorithm uses the real cutter contact toolpath generated by the inverse kinematics and not the linearized piecewise
real cutter location toolpath. 相似文献