共查询到20条相似文献,搜索用时 140 毫秒
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一种数控自动编程直线插补的新算法 总被引:2,自引:0,他引:2
本文给出了一种根据零件加工精度的要求 ,对三次B样条列表曲线进行直线插补、自动生成变步长刀位轨迹的算法 ,简称自适应算法。该算法可根据曲线曲率大小 ,自动改变步长 ,同时逼近误差满足要求。该算法稳定、可靠 ,便于在列表曲线、列表曲面的数控加工中推广应用 相似文献
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基于自适应变步长算法在大型非圆曲线零件数控加工中的应用 总被引:1,自引:0,他引:1
针对固定步长的圆弧插补算法在大型非圆曲线零件加工中的缺点,提出了自适应变步长算法,该方法按照曲线的曲率变化而采用相应的步长,算法简单,插补误差小,达到了快速、高效的加工效果,避免了以往过切或者加工精度不够的现象。能够提高数控机床的插补精度和加工效率。 相似文献
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分析传统的固定步长插补算法在复杂曲面零件加工中的缺点,提出自适应变步跃算法,该方法按照曲线的曲率变化而采用相应的步长,算法简单,插补误差小,达到快速、高效的加工效果。 相似文献
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提出了一种能适应曲面曲率变化的高精度等弓高误差变步长算法,通过判断曲线上对应参数增量点的曲率符号,采用两种校核方法求取弓高误差,快速确定对应等弓高误差的下一参数点可能的上下区间,采用黄金分割法精确求取曲线上对应的最大弓高误差点及步长参数增量,解决了目前加工步长算法中,假设步长内曲线等曲率半径,采用曲线与直线段中点连线距离代替最大弓高误差造成的超差问题,从而实现了完全意义上的基于等弓高误差法的加工步长规划。仿真结果显示:该算法与传统的步长规划方法相比,可以减少加工步长段数,提高步长内的弓高误差精度。 相似文献
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为提高非均匀有理B样条(NURBS)曲线插补的步长精度,给出了一种基于参数迭代的双NURBS曲线插补算法。先进行刀尖点曲线插补,基于NURBS的局部特性分析,利用插补步长与参数增量间的近似线性关系,通过迭代寻优,获取了精确步长所对应的插补参数;然后依据双NURBS曲线间的同步关系,计算出刀轴矢量曲线的插补参数,实现了面向五轴加工的刀具位姿插补。实验结果表明,该方法所得的步长精度优于Taylor展开插补法,并可保证刀轴矢量与工件表面法线方向的一致性,有利于获得更加光滑的加工表面。 相似文献
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列表点曲线数控加工方法的分析与研究 总被引:4,自引:0,他引:4
分析和研究了列表点曲线的数控加工问题,提出了先以三次参数样条进行插值,再用双圆弧拟合的方法。实例证明:该方法拟合后的曲线光顺,偏差较小,并且算法简单。 相似文献
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基于双圆弧步长伸缩数控插补非圆曲线算法的研究 总被引:7,自引:0,他引:7
为了加工出高质量的非球曲面器件,超精密非球曲面数控系统的数控插补算法非常重要。根据所要加工的非球曲面零件,采用了一种新的非圆曲线数控插补算法“双圆弧步长伸缩数控插补算法”。这种算法采用双圆弧段逼近方式,其双圆弧段彼此相切,一阶导数连续,并且步长可伸缩,其数控插补误差可进行控制。因此加工后的工件表面整体光滑,插补曲线的质量很高,而且适用性很广泛。最后用所研制的数控插补算法进行了大量的磨削加工试验,试验结果表明:该插补算法能加工出高质量的非球曲面零件,加工后的零件面形精度为O.30μm,其表面粗糙度Rrms=11.555nm,Ra=8.538 nm。 相似文献
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数控机床加工的零件轮廓一般由直线、圆弧组成,也有一些非圆曲线轮廓例如高次曲线、列表曲线、列表曲面等,但都可以用直线或圆弧去逼近。本文主要论述了插补算法对数控系统的影响和插补算法的工作流程,并对高次曲线的插补原理进行分析与研究,最后推导出高次曲线插补的递推公式,绘制插补逻辑图,其递推公式和插补逻辑图同样适用于其它高次曲线。 相似文献
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Xiaohui Zhang Dong Yu Taotao Song 《The International Journal of Advanced Manufacturing Technology》2012,62(9-12):1179-1189
The existing interpolation algorithm cannot meet the need of high-speed and high-accuracy machining of a free-form surface. So this paper proposed a correcting and compressing interpolation algorithm. Depending on the distance and angle evaluated from the adjacent command points, the machining path of free form can be divided into two machining types. For those regions where the accurate figure is critical such as corners, the convention linear interpolation is performed exactly between the adjacent command points. For those regions having a large radius of curvature where the smooth figure is critical, firstly, the interior point selection method based on circle transition is derived to reduce the tolerance between the machining path and the original surface; secondly, the interior point correction method based on the least-square method is proposed to reduce the calculation error and round-off error in the interior point and estimate the first- and second-order derivative vectors of the interior point; thirdly, the shape-defining point is selected by the bend direction of the machining path and fitted to a quintic spline curve which has the C2 continuity; fourthly, the fitting accuracy controlling method is proposed to ensure the machining accuracy; lastly, the curve interpolation is performed on the fitted smooth curve. Machining tests carried out on a vertical machining center show that the proposed algorithm can improve the machining efficiency and machining quality of a free-form surface. 相似文献
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Ultra-precision freeform surfaces are non-rotational symmetric surfaces possessing sub-micrometer form accuracy and nanometric surface finish. Although they can be fabricated accurately by ultra-precision machining technology, their surface quality is difficult to be characterized. Surface reconstruction is a vital task in the form characterization of ultra-precision freeform surfaces. This paper presents a robust surface fitting algorithm to reconstruct a high fidelity surface from measured discrete points while the surface smoothness can be ensured as well. A fitting threshold named confidence interval of fitting error is proposed to strike the balance between fitting accuracy and surface smoothness in the fitting process. The fitting algorithm is in two steps. In the first step, bidirectional sampling method is developed to extract a curve network from measured points cloud to construct an initial surface. In the second step, the fitting error of the initial surface is minimized to meet the prescribed fitting error threshold. A series of experimental work has been conducted and the results show that the proposed algorithm is able to provide effective means for increasing the accuracy in the form characterization of ultra-precision freeform surfaces. 相似文献
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Laurent Tapie Bernardin Mawussi Walter Rubio Benoît Furet 《The International Journal of Advanced Manufacturing Technology》2013,69(5-8):1499-1509
Nowadays, high-speed machining is usually used for production of hardened material parts with complex shapes such as dies and molds. In such parts, tool paths generated for bottom machining feature with the conventional parallel plane strategy induced many feed rate reductions, especially when boundaries of the feature have a lot of curvatures and are not parallel. Several machining experiments on hardened material lead to the conclusion that a tool path implying stable cutting conditions might guarantee a better part surface integrity. To ensure this stability, the shape machined must be decomposed when conventional strategies are not suitable. In this paper, an experimental approach based on high-speed performance simulation is conducted on a master bottom machining feature in order to highlight the influence of the curvatures towards a suitable decomposition of machining area. The decomposition is achieved through the construction of intermediate curves between the closed boundaries of the feature. These intermediate curves are used as guidance curve for the tool paths generation with an alternative machining strategy called “guidance curve strategy”. For the construction of intermediate curves, key parameters reflecting the influence of their proximity with each closed boundary and the influence of the curvatures of this latter are introduced. Based on the results, a method for defining guidance curves in four steps is proposed. 相似文献
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Yong-Qing Wang Ye Tao Hong-Jin Zhang Shi-Shan Sun 《The International Journal of Advanced Manufacturing Technology》2013,69(9-12):2149-2159
Point cloud data acquisition is the first key step in digital copying manufacture. In order to reduce extremely dense acquired data while maintaining data accuracy, this paper presents a simple and practical on-line point cloud data reduction method for digital copying manufacture, which is based on Akima spline interpolation. The basic idea of this method is similar to sketch painting: Outline the broad contour of the curve first and then revise local details until the interpolated curve satisfies the required accuracy. In this method, Akima spline interpolation is adopted to connect acquired points for CNC machining in digital copying process. It obtains a smaller data reduction ratio and a smoother machined surface than conventional methods. Experimental results indicate that the proposed Akima reduction method is able to eliminate redundant data effectively under different required accuracy. The reduction performance of this method is superior to equal ATCD reduction method obviously under the same required accuracy. The proposed method can be used in the real-time data acquisition process of digital copying manufacture to replace traditional methods. 相似文献
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Complex pockets with one or more islands have been widely used in industrial and manufacturing production. In this paper, a new double spiral tool-path generation and linking method are proposed for complex pockets with islands which can be used for high-speed machining (HSM) is used. Taking into account the path interval, step length and other processing parameters, precise milling can be achieved without cutter lifting and retraction motions to guarantee machining accuracy and reduce processing time. The method has been implemented in several simulations and validated successfully through the actual machining of a complicated pocket. The results indicate that this method is superior to other existing machining methods, and it can achieve HSM of complicated shaped pockets based on parametric surface. 相似文献
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In the machining of sculptured surfaces, five-axis CNC machine tools provide more flexibility to realize the cutter position as its axis orientation spatially changes. Conventional five-axis machining uses straight line segments to connect consecutive machining data points, and uses linear interpolation to generate command signals for positions between end points. Due to five-axis simultaneous and coupled rotary and linear movements, the actual machining motion trajectory is a non-linear path. The non-linear curve segments deviate from the linearly interpolated straight line segments, resulting in a non-linearity machining error in each machining step. These non-linearity errors, in addition to the linearity error, commonly create obstacles to the assurance of high machining precision. In this paper, a novel methodology for solving the non-linearity errors problem in five-axis CNC machining is presented. The proposed method is based on the machine type-specific kinematics and the machining motion trajectory. Non-linearity errors are reduced by modifying the cutter orientations without inserting additional machining data points. An off-line processing of a set of tool path data for machining a sculptured surface illustrates that the proposed method increases machining precision. 相似文献
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Jinghua Xu Shuyou Zhang Jianrong Tan Xiaojian Liu 《The International Journal of Advanced Manufacturing Technology》2012,62(9-12):1169-1178
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. 相似文献