共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
C.K. Au 《The International Journal of Advanced Manufacturing Technology》2001,17(8):558-561
The features of a sculptured object are represented by a set of section curves. A fast algorithm is presented to calculate
cutting depths based on the scallop height using these curves. The calculated cutting depth can be used for tool-path generation.
This tool-path generation approach is particularly useful for constant z level contouring and high-speed machining. 相似文献
3.
高速铣削刀轨优化技术的研究 总被引:7,自引:0,他引:7
针对高速铣削的特点和编程要求 ,提出了适合高速铣削的粗精加工刀轨优化算法。这些算法主要解决了型腔和轮廓加工刀轨的合理规划和进刀方式的选取 ,运用这些算法可以自动生成光滑C1连续的高速加工无干涉刀轨。仿真结果表明 ,加工表面无过切。经测试 ,算法运算速度快、可靠性好 相似文献
4.
An Effective Global Gouge Detection in Tool-Path Planning for Freeform Surface Machining 总被引:1,自引:0,他引:1
L. Zhou Y.-J. Lin 《The International Journal of Advanced Manufacturing Technology》2001,18(7):461-473
This paper examines a usually neglected gouge phenomenon in tool-path planning for machining parts having freeform surfaces with 3-axis ball-end mills. That is, when a freeform surface is being milled with a ball-end cutter, a gouge may exist anywhere around the cutter circumference, in addition to the tool driving plane. A global gouge detection concept is developed to solve this problem. An effective method is proposed to identify the potential gouge areas on the sculptured surface during machining, before generating tool paths. Thus, it greatly simplifies the tool-path planning procedure and improves the accuracy and reliability of machining. It also facilitates geometric design processes of products and cutter radius selection which are crucial to machining efficiency. The designed part surfaces tested by the proposed methodology are constructed based on bicubic B2-splines and are assumed to be at least C 2 and may possess C 1 or C 0 continuity for generality. The tested examples demonstrate the effectiveness of the developed global gouge detection approach.
This revised version with a corrected online cover date was published online in April 2004. 相似文献
5.
Many fractal generation methods have been developed and used to create an image of a natural scene. Nonlinear dynamic systems
employ fractal theory for population growth. Fractals have also been used to model chaotic problems. In numerical control
(NC) machining, fractal curves have been used in tool-path generation. Although the visualisation of fractal geometry has
been successfully demonstrated by computer graphics, a manufacturing method for physical fractal objects is not available.
Moreover, contemporary computer-aided design (CAD) systems consider only Euclidean geometry and none of them addresses fractal
geometry. Fractal curves have been used in tool-path planning for Euclidean objects, but there is no report on rapid prototyping
(RP) of objects defined in fractal geometry.
In the paper, a new data structure, called the radial–annular tree (RAT) structure, is proposed and implemented to bridge
the gaps between CAD, RP, and fractal geometry. A typical fractal curve, the Koch snowflake curve, will be examined in detail.
Based on the RAT representation, higher-level fractal curves can be generated more efficiently, and repeated information can
be represented concisely. Traversal algorithms are also devised to generate a maximally connected tool path directly. The
tool path can then be used to generate a physical fractal curve without any additional conversion. 相似文献
6.
7.
Dr Y. N. Hu W. C. Tse Y. H. Chen Z. D. Zhou 《The International Journal of Advanced Manufacturing Technology》1998,14(5):321-329
In the manufacture of parts with sculptured cavities from prismatic stock, rough machining usually constitutes most of the machining time owing to the significant difference between the stock and the part shape. When using 2 1/2-D milling or a contour-map approach to do the rough machining, the appropriate selection of tool-path pattern for each cutting layer can significantly reduce rough machining time and hence increase productivity. In this paper, the commonly used toolpath patterns are summarised. A knowledge-based parametric approach for optimising the toolpath pattern of a given cutting layer is proposed. Then, a novel methodology is developed to calculate an arbitrary polygon area and locate the concave cavities in the polygon. Procedures for cutting-layer-shape analysis and the optimal comprehensive tool-path pattern generation are also built and proposed in this paper. These procedures can not only be applied to sculptured cavity parts with simple islands, but also to parts with arbitrarily-shaped islands. Finally, an example is given to illustrate the reasoning process. 相似文献
8.
A Next Generation NC Machining System Based on NC Feature Unit and Real-Time Tool-Path Generation 总被引:1,自引:1,他引:0
L. Zhang J. Deng S. C.-F. Chan 《The International Journal of Advanced Manufacturing Technology》2000,16(12):889-901
In order to improve the control and information integration capability of an NC machining system, this paper provides a new
concept – an NC feature unit (NCFU), which is a feature-based and a basic control unit. First, as a feature-based control
unit, NCFU possesses geometric form and control parameters, which are a subclass of high-level CAD/CAM features so that it
can be used as an information exchange medium between NC machining systems and other manufacturing execution systems. Secondly,
as a basic machining control unit, NCFU uses a geometrically defined closed and non-gouging machined area. On the one hand,
through decompo-sition, a machined object can be divided into a combination of several NCFUs. On the other hand, since NCFUs
are non-gouging, the algorithm for NCFU-based tool-path generation is simple enough to be executable in real-time. This paper
discusses NCFU-based applications in 2.-D profile/pocket and 3D surface mill machining, including the NCFU definition and
the related algorithms for decomposition calculation and area interpolation. A next generation NC machining system based on
NCFU, including an NCFU-based NCP and an NCFU-based CNC system, has been prototyped by China’s State 863/CIMS Design Automation
Laboratory in Beijing University of Aeronautics and Astronautics. An NCFU is being used as the information exchange medium
in an internet-integrated manufacturing system with NC machining at Hong Kong Polytechnic University. 相似文献
9.
Richard B��ar��e Jean-Yves Dieulot Patrice Rabat�� 《The International Journal of Advanced Manufacturing Technology》2011,53(5-8):463-471
A new and fast registration algorithm has been proposed to update the tool-path of a deburring robot, intended to machining composite workpieces under gravity and clamping deformations. A Subdivision Iterative Closest Point algorithm, which considers different parts of the contour with respect to curvature, allows to obtain far better results than classical methods, without complicated assumptions or computations. The procedure has shown to be effective for porthole and nose-cone deburring. Experimental tests conducted on robotic milling workcell demonstrated the efficiency of the registration method. 相似文献
10.
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
11.
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13.
Geometry of chip formation in circular end milling 总被引:1,自引:0,他引:1
Avisekh Banerjee Hsi-Yung Feng Evgueni V. Bordatchev 《The International Journal of Advanced Manufacturing Technology》2012,59(1-4):21-35
Machining along continuous circular tool-path trajectories avoids tool stoppage and even feed rate variation. This helps particularly in high-speed milling by reducing the effect of the machine tool mechanical structure and cutting process dynamics. With the increase in popularity of this machining concept, the need for detailed study of a valid chip formation in circular end milling is becoming necessary for accurate kinematic and dynamic modeling of the cutting process. In this paper, chip formation during circular end milling is studied with a major focus on feed per tooth and undeformed chip thickness along with their analytical derivations and numerical solutions. At first, the difference in the feed per tooth formulation for end milling along linear and circular tool-path trajectories is presented. In the next step, valid formulation of the undeformed chip thickness in circular end milling is derived by considering an epitrochoidal tooth trajectory with a wide range of the tool-path radius. The complex transcendental equations encountered in the derivation are dealt with, by a case-based approach to obtain closed-form analytical solutions. The analytical solutions of undeformed chip thickness are validated with results of numerical simulations of tool and tooth trajectories for circular end milling and also compared to the linear end milling. The close resemblance between analytical and numerical calculations of the undeformed chip thickness in circular end milling suggests validity of the proposed analytical formulations. As a case study, the cutting forces in circular end milling are calculated based on the derived chip thickness formulations and an existing mechanistic model. The calculation results reiterate the need of taking into account adjusted feed per tooth and valid chip thickness formulations in circular end milling, especially for small tool-path radii, for more realistic process modeling. 相似文献
14.
A New Tool-Path Generation Method Using a Cylindrical End Mill for 5-Axis Machining of a Spatial Cam with a Conical Meshing Element 总被引:2,自引:2,他引:0
R. S. Lee J. N. Lee 《The International Journal of Advanced Manufacturing Technology》2001,18(9):615-623
The geometry of a spatial cam is normally generated using a form-milling cutter and a special multi-axis machine and software.
The general purpose CAD/CAM software can generate the cutter location file of this class of product only by the sculpturing
method. Because of the limited choice of cutting tool when using the generating method, this paper presents a new toolpath
generating method which combines the advantages of the generating and sculpturing methods for machining a spatial cam. In
the machining process, the cutter location is derived for rough and finish machining using a cylindrical end mill. The guidelines
for choosing cutter diameter for the machining process are discussed. To avoid interference, the principal curvatures and
the principal induced normal curvatures are analysed. The mathematical errors including chordal deviation and scallop height
are used as the basis for generating appropriate tool-paths. Cutting simulation of a solid model was performed to verify the
proposed tool-path generation method. 相似文献
15.
A Reverse Engineering Approach to Generating Interference-Free Tool Paths in Three-Axis Machining from Scanned Data of Physical Models 总被引:3,自引:4,他引:3
C.-M. Chuang C.-Y. Chen H.-T. Yau 《The International Journal of Advanced Manufacturing Technology》2002,19(1):23-31
An NC tool path is usually generated by sweeping parametric surfaces of a CAD model. In modern design, freeform or sculptured
surfaces are increasingly popular for representing complex geometry for aesthetic or functional purposes. Traditionally, a
prototype is realised by machining the workpiece using the NC codes generated from a CAD model. The machined part can then
be compared with the CAD model by measurement using a coordinate measuring machine. In this paper, a reverse engineering approach
to generating interference-free tool paths in three-axis machining from the scanned data from physical models is presented.
There are two steps in this procedure. First, a physical model is scanned by a 3D digitiser, and multiple data sets of the
complex model are obtained. A surface registration algorithm is proposed to align and integrate those data to construct a
complete 3D data set. A shortest-distance method is used to determine the connecting sequence of the neighbouring points between
two adjacent scan lines, such that the scanned data are converted into triangular polygons. Tool paths are then generated
from the tessellated surfaces. Using the Z-map method, interference-free cutter-location data are calculated, relative to
the vertex, edges, and planes of the triangles. The algorithms for tool-path generation are usually different for cutters
of different geometries. Some algorithms found in the literature require complex numerical calculations and are time consuming.
In this paper, an efficient algorithm is developed to calculate interference-free cutter-location data by easy geometric reasoning
without complex computation. This robust method is suitable for generally used cutters such as ball, flat, and filleted end
mills, and the time taken to obtain full tool paths of compound surfaces is short. Some real applications are presented to
validate the proposed approach. 相似文献
16.
Contour-parallel offset machining for trimmed surfaces based on conformal mapping with free boundary 总被引:1,自引:1,他引:0
Yuwen Sun Fei Ren Xinghua Zhu Dongming Guo 《The International Journal of Advanced Manufacturing Technology》2012,60(1-4):261-271
The parametric surfaces of some manufactured parts are often subjected to the Boolean operation of other objects; generating suitable NC tool paths from such trimmed surface remains a challenge. This paper presents a new planar development-based method to generate contour-parallel offset paths of trimmed surfaces. To avoid direct frequent identifications and removals of interferences of offset curves on 3D-trimmed surface possibly with multiple holes or restricted regions, the original surface is flattened in the plane domain using a two-stage approach which consists of conformal mapping with free boundary and further nonlinear accuracy improvement. Then, sequent offsets of the boundary curves of the planar region are generated, and the global interferences are detected and removed using an efficient and robust divide-and-conquer strategy. Based on a tree data structure, a tool-path linking algorithm is also given with less or no tool retractions, and subsequently, the resulting planar paths are inversely mapped to the physical space. Illustrated examples have been conducted to testify the affectivity and the applicability of the proposed contour-parallel offset machining method. 相似文献
17.
18.
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
19.
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
20.
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