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2004, CIRP Annals - Manufacturing Technology
2013, International Journal of Machine Tools and Manufacture
2012, International Journal of Machine Tools and Manufacture
2014, The International Journal of Advanced Manufacturing Technology
2014, The International Journal of Advanced Manufacturing Technology
2013, The International Journal of Advanced Manufacturing Technology
The objective of the article is to present various off-line calculation methods to calculate polynomial tool trajectories, format well adapted to High-Speed Machining. In particular, we are interested in comparing machining performances of various polynomial calculation algorithms such as interpolation, association or inter-approximation with energy minimization. This comparison is achieved using a test part through simulations and machining tests to justify the efficiency of the calculation methods. Measurements of velocity and position during machining highlight differences between the different association methods. Attention is also paid to the visual and geometrical quality of the machined surfaces.
2008, The International Journal of Advanced Manufacturing Technology
2011, Advanced Materials Research
2014, The International Journal of Advanced Manufacturing Technology
2007, The International Journal of Advanced Manufacturing Technology
Numerous works have shown that the linear format of tool path is not well adapted to HSM for it does allow an optimal follow-up of the tool trajectory by the NC unit, nor a good part surface quality. This paper deals with formats of tool trajectory relying on polynomial models. The tool path can be described as polynomial curves as well as polynomial surfaces. Geometrical and dynamical advantages of using such formats are exposed.
2013, CIRP Journal of Manufacturing Science and Technology
2008, Computer-Aided Design
This article presents a predictive model of the kinematical behaviour during 5-axis machining. This model highlights differences between the programmed tool-path and the actual follow-up of the trajectory. Within the High Speed Machining context, kinematical limits of the couple CNC-machine-tool have to be taken into account in the model. The originality of the model is the use of the inverse-time method to coordinate machine-tool axes, whatever their nature (translation or rotation). The model reconstructs the actual relative velocity tool-surface from each axis velocity profile highlighting trajectory portions for which cutting conditions are not respected.
This article presents a predictive model of the kinematical behaviour during 5-axis machining. This model highlights differences between the programmed tool-path and the actual follow-up of the trajectory. Within the High Speed Machining context, kinematical limits of the couple CNC-machine-tool have to be taken into account in the model. The originality of the model is the use of the inverse-time method to coordinate machine-tool axes, whatever their nature (translation or rotation). The model reconstructs the actual relative velocity tool-surface from each axis velocity profile highlighting trajectory portions for which cutting conditions are not respected.
− The increase in the productivity and the assurance of quality machining on the NC machines depends on, amongst other things, the perfection of the programming using adequate methods of interpolation. The programming language is until now based on the code ISO 6983 which defines the principles of the code G. This latter is not well adapted to the new strategies of machining imposed by the machining of complex surfaces and machining at high speed with the increasingly more severe requirements of precision. The CNC which adopt the interpolation of NURBS (Non Uniform Rational B-spline) are very rare (FANUC Siemens…). Based on the advantages of NURBS (continuity, flexibility, smoothing....), new formats G are currently developed but their use is still very limited. Our work consists on putting forward these new approaches of programming using the interpolation of NURBS. For this reason, a program capable to trace NURBS trajectories under Visual BASIC 6.0 was developed. This program was used thereafter in CAM software for the generation of NURBS formats like their new formats NC.
2010, International Journal Adcanced Manufacturing Technology
The paper presents a survey of five-axis computer numerical controlled (CNC) machining optimization methods employing adaptable geometric patterns. First, the survey introduces evolution of CNC interpolators from the simplest Taylor series-based routines to sophisticated procedures based on constraint minimization from dynamic systems control theory. Furthermore, a variety of methods based on spline interpolation, NURBS interpolation and Farouki's Pythagorean-hodograph curves is presented and analyzed. Next, the survey deals with techniques to optimize the positions and orientations of the tool in a particular neighborhood of the part surface. The most important application of these techniques is cutting by a flat-end or a fillet mill while avoiding local overcuts or undercuts due to the curvature interference and rear gouging. This section is supplemented by detection of global interference using visibility cone schemes and their recent modifications and improvements. Solutions offered by solid modeling are presented as well. Finally, adaptable geometric patterns employed for tool path generation are considered and analyzed. The adaptation is performed using certain criteria of the tool path quality, such as kinematics error, scallops, possible undercuts or overcuts, and the continuity of the path. Also covered are complex pocket milling employing geometric patterns capable of following the boundary, such as the offset methods, regional milling, the potential path methods, and clustering. The chapter also presents tool path optimization based on the adaptable curvilinear grids connecting the cutter location points. Finally, navigation approaches and the shortest-path schemes are considered, along with the adaptive space-filling curve algorithms and their combinations with grid generation.
2009, International Journal of Machine Tools and Manufacture
This paper deals with 5-axis milling of hydraulic blades. The issue developed is essentially linked to problems due to the transition from 3 to 5 axes. A specific attention is done to the Inverse Kinematics Transformation (IKT) which can be source of incoherent behavior during machining due to possible multiplicity of solutions. Such behaviors may lead to slowdowns during machining which affect productivity. Moreover, geometrical surface finish may be altered. To study this phenomenon, we propose to machine a test part with the objective to reach the required quality while preserving productivity. After the analysis of the problems linked to the IKT through specific trajectories we propose solution to solve such problems, based on the local modification of the trajectory. The context of the work is a collaboration between the LMH and the LURPA.
Manufacturing of free form parts relies on the calculation of a tool path based on a CAD model, on a machining strategy and on a given numerically controlled machine tool. In order to reach the best possible performances, it is necessary to take into account a maximum of constraints during tool path calculation. For this purpose, we have developed a surface representation of the tool paths to manage 5-axis High Speed Milling, which is the most complicated case. This model allows integrating early in the step of tool path computation the machine tool geometrical constraints (axis ranges, part holder orientation), kinematical constraints (speed and acceleration on the axes, singularities) as well as gouging issues between the tool and the part. The aim of the paper is to optimize the step of 5-axis HSM tool path calculation with a bi-parameter surface representation of the tool path. We propose an example of integration of the digital process for tool path computation, ensuring the required quality and maximum productivity.
2011, Computer-Aided Design
2011, International Journal of Mechatronics and Manufacturing Systems
This paper presents a smooth spline interpolation technique for five-axis machining of sculptured surfaces. The tool tip and orientation locations generated by the CAM system are first fitted to quintic splines independently to achieve geometric jerk continuity while decoupling the relative changes in position and orientation of the cutter along the curved path. The nonlinear relationship between spline parameters and displacements along the path are approximated with ninth order and seventh order feed correction splines for position and orientation, respectively. The high order feed correction splines allow minimum deviation from the reference axis commands while preserving continuous jerk on three translational and two rotary drives. The proposed method has been experimentally demonstrated to show improvements in reducing the excitation of inertial vibrations while improving tracking accuracy in five-axis machining of curved paths found in dies, molds and aerospace parts.
Computer numerical control (CNC) machines have been widely used in automotive manufacturing industries especially of machining operation in automotive part such as engine body and cylinder. One of the key features that improve efficiency of CNC machining is through the optimization of tool path. Previous researcher to optimize tool path has premeditated several approaches. This paper aims to provide a critical review of those approaches that have been developed in tool path. The developed tool path approaches covered different types of machining process under various constraints condition. This paper focuses on tool path generation in CNC machining such as milling and cutting process. Based on our finding, this review paper collects information on tool path optimization and recommends future research direction.
2012, Mechanical Engineering
2020, 2020 IEEE International Conference on Fuzzy Systems (FUZZ-IEEE)
Optimality and computational efficiency are two very desirable but also competitive attributes of optimal feed planning. A well-designed algorithm can vastly increase machining productivity by reducing tool positioning time subject to limits of the machine tool. The nonlinear optimization problem aims to achieve the highest possible feed along the tool path, while limiting the speed of the actuator level, acceleration and Jerk profiles. Methods proposed in the literature either use rather complex nonlinear optimization solvers, such as Sequential Quadratic Programming, use iterative heuristics that extends computation time, or use conventional assumptions that reduce computation time but lead to slower tool motion.The problem of optimal feed-rate planning along a curved tool path for multi-axis CNC machines with a Jerk limit for each axis is addressed. However, the use of Jerk (rate of change of acceleration) into the feed-rate scheduling problem causes generating both, computationa...
2013, Machining Science and Technology
This paper deals with a predictive model of kinematical performances in 5- axis milling within the context of HSM. Capacities of each axis as well as some NC unit functions can be expressed as limiting constraints. The proposed model relies on each axis’ displacement in the joint space of the machine-tool and predicts the most limiting axis for each trajectory segment. Thus, the calculation of the relative feed rate tool- surface can be performed highlighting zones for which the programmed feed rate is not reached and so, it constitutes an indicator for trajectory optimization. The efficiency of the model is illustrated through an example.
2009, Eprint Arxiv 0905 3079
The current language for CNC programming is G-code which dates from the beginning of the eighties with the norm ISO 6983. With the new technologies, G-code becomes obsolete. It presents drawbacks that create a rupture in the numerical chain at the manufacturing step. A new standard, STEP-NC, aims to overtake these lacks. A STEP-NC file includes all the information for manufacturing, as geometry description of the entities, workplan, machining strategies, tools, etc. For rough pocket milling, the ISO norms propose different kind of classical strategies as bidirectional, parallel or spiral contour, etc. This paper describes a new way of toolpath programming by the repetition of a pattern all along a guide curve. It presents several advantages as building fastness and easiness. The integration of pattern strategies in STEP-NC standard is an other step for the development of these strategies but also for the enrichment of STEP-NC possibilities. A complete STEP-NC numerical chain was built, integrating these pattern strategies. The implementation of this approach of building pattern strategies was made by the development of tools for the complete manufacturing cycle, from the CAD file to the machined part. Several application cases were experimented on machine tool to validate this approach and the efficiency of the developped tools.
2010
2011
2020, INTERNATIONAL JOURNAL OF COMPUTER INTEGRATED MANUFACTURING
This paper proposes a postprocessor which applies the appropriate rotation rules to reduce the kinematic error (KE). Our first contribution is an algorithm which minimizes the KE using the Hausdorff distance. The shortest path algorithm includes the constraints relevant to the limits of the linear and the rotation axis. The proposed procedure is compared with state-of-the-art methods. It demonstrates an advantage in terms of the kinematic error for test surfaces characterized by a sharp curvature. The second contribution is testing interpolation methods of the STL surfaces. The first step of this procedure is the evaluation of the tessellation error (TE), i.e., the difference between the actual surface and the local or global interpolation obtained from the STL file. The numerical results show that a simple local interpolation using normal vectors proposed by Nagata performs well. The method has been tested against several state-of-the-art interpolation procedures, demonstrating a significant advantage. The proposed elements are integrated into a postprocessor. The experiments have been performed on a virtual and the actual tilt-table five-axis machining center (Haas VF-2TR). ARTICLE HISTORY
This paper deals with an advanced modeling of the feed drives of a five axis machine tool within the context of High Speed Machining. The management of the multi axes as well as high velocities causes problems to the set machine tool – Numerical Controller throughout the trajectory execution process. As a result, many errors are introduced during machining all process long affecting the surface quality. The paper aims at modeling the feed drive dynamics during trajectory follow-up including the current, the velocity and position loops as well as the feed forward terms, which characterize classical drives on actual HSM machines. It concerns translational axes as well as rotary axes. A procedure of identification is implemented. Performances of the model are assessed by the comparison between simulated tool paths to the real one. Experimental verifications of the virtual axis model are detailed for three and five axis trajectories presenting various types of geometrical discontinuities.
2013, The International Journal of Advanced Manufacturing Technology
2007, The International Journal of Advanced Manufacturing Technology
2013, Advanced Materials Research
In the context of high speed milling HSM, the feed rate does not always reach the programmed value during the machining process which implies an increase of machining time and non compliance with the programmed feed rate. This phenomenon leads to productivity issues and an underestimation of the cost of machining for the industry. The aim of this study is to identify the kinematic behaviour of the machine tool during any type of discontinuity between linear and circular contours in different combination by taking into account the specific machining tolerances. In order to achieve this, a model of the law of the axes motion and the actual trajectory at discontinuities is necessary. This method is based on the subdividing of the trajectory into elementary geometries according to the type of interpolation (circular or linear). The proposed method can estimate the cycle time with a maximum error of 5% between the actual and the prediction cycle time. Finally, an experimental study was c...
International Journal of Machine Tools and Manufacture