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The iso-scallop method has been long adopted to achieve a shorter overall machining length. The efficiency and machining performance of this method are largely dominated by the initial tool path. The preferred direction field supplies the local best feed directions. Usually, the offset paths generated by the iso-scallop method largely deviate from...
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... 3) Benchmark: ISP and ISSH are chosen as the benchmarks for BRNet, and provide comparisons on length and quality of tool paths on validation set. As traditional path planning TABLE II TOOL-PATH GENERATION SATISFYING SCALLOP HEIGHT ON THE TEST DATASET, BRNET-SP, AND BRNET-EP MEAN IMPLEMENTING OUR METHOD WITH SCALLOP PRIORITY methods, ISP and ISSH remain popular and are frequently mentioned in recent papers [10], [28]. The tool paths are P u i,j (i = 1, . . . ...
Tool-path planning is a crucial factor of computer-aided design (CAD) and computer-aided manufacturing (CAM). Previous path generation methods often transform the problem into local or global optimization methods to solve it, leading to a long computational time. With the development of modern industry, real-time path planning is becoming an urgent issue in advanced manufacturing. This article proposes an efficient neural network-based direct tool-path generation method on B-spline surface for subtractive end milling. In order to build the first corresponding dataset, adaptive iso-scallop height method is proposed, which can effectively avoid generating breakpoints at the boundary. B-Spline reparameterization is used to fit discrete tool paths to obtain regular control points data structure for further deep learning. After that, an intelligent neural network is proposed to learn the relationship between the input B-Spline surface and the reparameterized tool paths. Finally, experimental results and case study are provided to illustrate and clarify our method, which only needs a few microseconds of planning time while ensuring the quality of the generated paths. Due to its simple structure and low computational burden, this method can be easily applied to CAD/CAM software.
... Xu and Li (Xu and Li, 2019) described the optimization of the cutting tool utilizing digital pictures in order to mill free form materials with consistent scallop depth. Su et al. (Su et al., 2020) described a sophisticated cutting tool pathways improvement to provide a constant scallop level in terms of free form edges cutting procedures. Meta-heuristic algorithms for assessing the collapse risk of steel moment frame mid-rise buildings is presented by Karimi Ghaleh Jough and Şensoy (Jough and Şensoy, 2016) in order to provide a better risk management strategy in steel moment frames. ...
The quality of machined part surfaces are under the impact of scallop height which should be analyzed and minimized. Achieving a uniform scallop-height is important for ensuring a smooth surface finish and maintaining consistent material removal across the machined surfaces during CNC machining operations. This approach helps to reduce material waste, tool wear and part production errors while ensuring consistent and high-quality of machined parts. Maintaining a constant scallop height can also help to reduce chatter and vibration during milling operations. The research work develops a virtual machining methodology to produce constant scallops through three-axis milling operations. The proposed approach examines free-form surfaces of workpiece in order to obtain free form surfaces curvatures. Then, free-form surfaces are separated into flat, convex and concave surfaces to provide optimized cutting tool variables in order to provide constant scallop height during CNC cutting tool paths. Achieving a constant scallop height involves optimizing cutting parameters such as feed rate, spindle speed, and step over. To calculate the optimized machining parameters of feed rate, speed of spindle and step over, the Taguchi optimization methodology is utilized in the study. Then, the machining variables of feed rate, speed of spindle and step over are optimized to achieve the uniform scallop height during milling potations of free-form surfaces. As a result, using optimized machining parameters during machining operations, the surface roughness of machined components are reduced by 23.8%. So, the proposed virtual machining method can enhance surface quality of machined parts during CNC milling operations of free-from-surfaces.
... The iso-scallop TPG usually produces paths which significantly deviate from VFPD. Therefore, Su et al. [185] propose a hybrid between the VFPD and iso-scallop paths. The initial toolpath is constructed taking into account the matching degree between these cost functions. ...
... The case studies performed to analyze the method show a reduction of the length of the toolpath of about 30% compared to the conventional iso-parametric path, 13% compared to the method of Kumazawa et al. [156] and 10% compared to Su et al. [185]. Figure 15 illustrates proposed approach applied to the STL surface of the bike seat from the GrabCAD library. ...
... Such non-smoothness in toolpaths could affect machining dynamics and reduce machining efficiency. This indicates a serious limitation of the proposed [187], middle: offset similarity method [185], right: iso-parametric path method but also offers huge potential for improvement." Therefore the following extensions have been proposed. ...
Toolpath generation (TPG) for multi-axis milling machines using vector fields (VF) and vector field analysis (VFA) is becoming increasingly popular in the manufacturing industry. Therefore, the paper presents a survey of algorithms and methods of TPG based on the vector fields of preferred directions (VFPD) for five-axis CNC machining. Two hundred relevant citations in top manufacturing and optimization journals during 1995–2021 have been presented and discussed. Additional 79 references in Appendices are related to a classification of five-axis machines, the theory and recent advances in the area of the vector and tensor fields.
... method [33], which is composed of 58 linear toolpaths with corner points number ranging from 32 to 224. The transition error is 0.02mm and other related parameters are the same as in Table 1. ...
In computer numerical control systems, linear segments generated by computer-aided manufacturing software are the most widely used toolpath format. Since the linear toolpath is discontinuous at the junction of two adjacent segments, the fluctuations on velocity, acceleration and jerk are inevitable. Local corner smoothing is widely used to address this problem. However, most existing methods use symmetrical splines to smooth the corners. When any one of the linear segments at the corner is short, the inserted spline will be micro to avoid overlap. This will increase the curvature extreme of the spline and reduce the feedrate on it. In this article, the corners are smoothed by a C4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${C}^{4}$$\end{document} continuous asymmetric Pythagorean-hodograph (PH) spline. The curvature extreme of the proposed spline is investigated first, and K=2.5\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$K=2.5$$\end{document} is determined as the threshold to constrain the asymmetry of the spline. Then, a two-step strategy is used to generate a blended toolpath composed of asymmetric PH splines and linear segments. In the first step, the PH splines at the corners are generated under the condition that the transition lengths do not exceed half of the length of the linear segments. In the second step, the splines at the corners are re-planned to reduce the curvature extremes, if the transition error does not reach the given threshold and there are extra linear trajectories on both sides of the spline trajectory. Finally, the bilinear interpolation method is applied to determine the critical points of the smoothed toolpath, and a jerk-continuous feedrate scheduling scheme is presented to interpolate the smoothed toolpath. Simulations show that, under the condition of not affecting the machining quality, the proposed method can improve the machining efficiency by 7.27\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$7.27$$\end{document} to 75.11%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$75.11\%$$\end{document} compared to G3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${G}^{3}$$\end{document} and G4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${G}^{4}$$\end{document} methods.
... The polishing path should meet the conditions of no interference, continuous smoothness, and high code quality [10,11]. The common methods of generating the tool path are isoparametric method [12,13], isometric section plane method [14,15], equal residual height method [16,17], etc. Shahzadeh et al. [18] proposed a method based on a polyhedron model with triangular mesh for generating the tool path, which can naturally form a machining path along polyhedron model and can reduce the tool wear and machining time. Wulle et al. [19] proposed a simple and practical isoparametric tool path for free-form surface. ...
Curved surface parts have been widely used in aerospace, automobile, and other fields due to their excellent features in aerodynamics, hydrodynamics, and thermodynamics. Compared with surface modeling technology, the development of surface processing technology is slightly behind. In order to improve the processing quality and efficiency of curved surface, a five-axis CNC polishing machine tool is developed, and the pre-processing and post-processing of machining the curved surface are studied. Taking a metal shell of the mobile phone as an example, three different paths are planned for the flat surface and the curved surface respectively, and a method of generating the tool path is proposed. The kinematics model of the five-axis CNC machine tool is established, which is used to obtain the calculation formula of the movement amount of each axis when polishing on the flat surface and the curved surface of the metal shell. The polishing effects of the different paths on the surface quality and the polishing efficiency of the metal shell are studied through the polishing experiments, and the polishing path with the best surface quality and the highest polishing efficiency is found.
... In this section, a compound freeform surface composed of two NURBS patches, which presented in Fig. 20, is tested. The toolpath of this freeform surface is generated by Su's method [41], which is composed of 58 linear toolpaths with corner points number ranging from 32 to 224. The transition error is 0.02 and other related parameters are the same as in Table 1. ...
In computer numerical control systems, linear segments, which are generated by computer-aided manufacturing software, are the most widely used toolpath format. Since the linear toolpath is discontinuous at the junction of two adjacent segments, the fluctuations on velocity, acceleration and jerk are inevitable. Local corner smoothing is widely used to address this problem. However, most existing methods use symmetrical splines to smooth the corners. When any one of the linear segments at the corner is short, to avoid overlap, the inserted spline will be micro, thereby increasing the curvature extreme of the spline and reducing the feedrate along it. In this article, the corners are smoothed by a 𝐶4 continuous asymmetric Pythagorean-hodograph (PH) spline. The curvature extreme of the proposed spline is investigated first, and 𝐾=2.5 is determined as the threshold to constarin the asymmetry of the spline. Then a two-step strategy is used to generate a blended toolpath composed of asymmetric PH splines and linear segments. In the first step, the PH splines at the corners are generated under the premise that the transition lengths do not exceed half of the length of the linear segments. In the second step, the splines at the corners are re-planned to reduce the curvature extremes, if the transition error does not reach the given threshold and there are extra linear trajectories on both sides of the spline trajectory. Finally, the bilinear interpolation method is applied to determine the critical points of the smoothed toolpath, and a jerk-continuous feedrate scheduling scheme is presented to interpolate the smoothed toolpath. Simulations show that, under the condition of not affecting the machining quality, the proposed method can improve the machining efficiency by 7.84% to 23.98% compared to 𝐺3 and 𝐺4 methods.
... One is to create a new surface based on the new mesh and then regenerate the tool path [29,30]. The other is to obtain a new tool path after offsetting the cutter position [31,32]. The first method is often used to compensate for the error resulted from deformation in the workpiece due to various reasons such as thermal expansion. ...
Drawing process represents a significant area of production technology since it influences the feasibility of producing auto-body die panels. In the drawing process, the plastic deformation of blank is not uniform due to the intermittent deformation behavior of the material. This primes a non-uniform thickness distribution in the formed panels, which directly affects the die life and the quality of panels. In the presented study, a new algorithm was proposed for constructing the numerical control machining tool path for the new die surface obtained from FEM simulation and mesh mapping. The commercial package LS-DYNA was employed for the FEM simulation and to calculate the thickness distribution in the drawn workpiece. In order to construct the new numerical control machining tool path according to the new die surface, the positions of all cutter location points relative to the movement of new die mesh were determined. A set of forming die was machined using the proposed algorithm to fabricate a real workpiece of steel DC04. A comparison between the measured thicknesses in the fabricated workpiece and the FEM simulation results shows that they agree with each other very well, which directly validates the proposed algorithm. The developed method can improve product quality, increase production efficiency, and reduce labor intensity.
... The performance of the iso-scallop tool path is closely bound up with the layout of the master paths which may be selected from the boundaries of surfaces [16] or the loci of the maximum convex curvature of surfaces [17], etc. By optimizing the feed direction of the master path from a local or global view in recent two decades, the machining time can be further reduced [18][19][20]. Indeed, there is no doubt that the iso-scallop method has a great potential to reduce the total length of tool path. ...
To fill the development gap between computer-aided design (CAD) and computer-aided manufacturing (CAM) on non-uniform rational b-spline (NURBS), a general tool path planning method on NURBS surface is proposed in this study. The generated tool path is composed of a series of closed paths which are derived by mapping the contours of a shortest boundary geodesic map (SBGM) from parameter space to 3D Euclidean space. SBGM that is created in parameter space depicts the shortest boundary geodesic distance (SBG) from internal points on NURBS surface to surface boundaries. It is calculated in discrete form firstly and then reconstructed by using a bicubic smoothing spline algorithm to improve the smoothness of the generated tool path. The tool path interval is deduced according to the requirement of residual scallop height constraint and determined conveniently based on the SBG difference of the two adjacent paths. It is confirmed that the proposed tool path planning method can be applied on all kinds of NURBS surface without the requirements of any other post-processing procedures. Typical case studies and experiments are presented to verify the effectiveness of the proposed method. Comparing with other traditional approaches, the proposed tool path planning method has excellent performance in improving the smoothness and reducing the total length of tool path.
... A similar idea was also presented in [22]. Su et al. [23] further proposed an optimization procedure to choose a proper initial tool path for generating iso-scallop tool paths within each patch. Using this hybrid strategy, improved alignment between iso-scallop tool paths and preferred feed directions were demonstrated. ...
... Case study 1 considered simple situation where no segmentation is needed; Case study 2 analyzed a comprehensive situation where the surface has to be segmented into multiple patches; Case study 3 involved a standard saddle surface, which was used to carry out error analysis. Case studies 1 and 2 also presents comparisons with the classic iso-scallop method by Feng and Li [2] and the state-of-the-art method by Su et al. [23]. The comparison results are summarized in Table 1. ...
... For the first two case studies, the overall length of the generated tool paths by the proposed method has been compared with those by the iso-parametric, iso-scallop [2], preferred feed direction [4], and enhanced preferred feed direction [23] (the state of the art) methods. The results are summarized in Table 1. ...
This paper presents a new method to generate tool paths for machining freeform surfaces represented either as parametric surfaces or as triangular meshes. This method allows for the optimal tradeoff between the preferred feed direction field and the constant scallop height, and yields a minimized overall path length. The optimality is achieved by formulating tool path planning as a Poisson problem that minimizes a simple, quadratic energy. This Poisson formulation considers all tool paths at once, without resorting to any heuristic sampling or initial tool path choosing as in existing methods, and is thus a globally optimal solution. Finding the optimal tool paths amounts to solving a well-conditioned sparse linear system, which is computationally convenient and efficient. Tool paths are represented with an implicit scheme that can completely avoid the challenging topological issues of path singularities and self-intersections seen in previous methods. The presented method has been validated with a series of examples and comparisons.
... The polishing path should meet the conditions of no interference, continuous smoothness and high code quality [9,10]. The common methods of generating the tool path are isoparametric method [11,12], isometric section plane method [13,14], equal residual height method [15,16], etc. Sun [17] et al. proposed a method based on a polyhedron model with triangular mesh for generating the tool path, which can naturally form a machining path along polyhedron model, and can reduce the tool wear and machining time. ...
Curved surface parts are widely used in aerospace industry, automotive industry and other fields due to their excellent features in aerodynamics, fluid dynamics and thermodynamics. Compared with the modeling technology of the curved surface, the development of the processing technology of the curved surface is slightly behind. In order to improve the processing quality and efficiency of the curved surface, this paper independently developed a five-axis CNC polishing machine tool, and studied the pre-processing and the post-processing when machining the curved surface. Taking a metal shell of the mobile phone as an example, three different paths are planned for the flat surface and the curved surface respectively, and a method for generating the tool path is proposed. The kinematics model of the five-axis CNC machine tool is established, which is used to obtain the calculation formula of the movement amount of each axis when polishing in the flat surface and the curved surface of the metal shell. The polishing effects of the different paths about the surface quality and the polishing efficiency of the metal shell are studied through the polishing experiments, and the polishing path with the best surface quality and the highest polishing efficiency is found.
