Trochoidal milling is known for its advantages in machining difficult-to-machine materials as it facilitates chip removal and tool cooling.However,the conventional trochoidal tool path presents challenges such as lowe...Trochoidal milling is known for its advantages in machining difficult-to-machine materials as it facilitates chip removal and tool cooling.However,the conventional trochoidal tool path presents challenges such as lower machining efficiency and longer machining time due to its time-varying cutter-workpiece engagement angle and a high percentage of non-cutting tool paths.To address these issues,this paper introduces a parameter-variant trochoidal-like(PVTR)tool path planning method for chatter-free and high-efficiency milling.This method ensures a constant engagement angle for each tool path period by adjusting the trochoidal radius and step.Initially,the nonlinear equation for the PVTR toolpath is established.Then,a segmented recurrence method is proposed to plan tool paths based on the desired engagement angle.The impact of trochoidal tool path parameters on the engagement angle is analyzed and coupled this information with the milling stability model based on spindle speed and engagement angle to determine the desired engagement angle throughout the machining process.Finally,several experimental tests are carried out using the bull-nose end mill to validate the feasibility and effectiveness of the proposed method.展开更多
Iso-scallop height machining means,when machining a freeform surface,the scallop height between any two neighboring tool paths on the surface will be a constant(i.e.,the given threshold),which is preferable among vari...Iso-scallop height machining means,when machining a freeform surface,the scallop height between any two neighboring tool paths on the surface will be a constant(i.e.,the given threshold),which is preferable among various freeform surface machining strategies due to its high machining efficiency as well as better machine tool’s dynamics.However,all the existing iso-scallop height path planning methods pertain to only the ball-end or flat-end types of tools.In recent years,the non-spherical cutting tool has become more and more popular,especially for five-axis machining of complex freeform surfaces,majorly owing to its non-constant curvature which can be utilized to adaptively fit the tool to the surface to both avoid the local gouging and enlarge the cutting width.However,there have been no reported works on iso-scallop height five-axis tool path generation for a non-spherical tool,and,in this paper,we present one.Specifically,we first define and construct two fields on the surface to be machined-the collision-free tool orientation field(vector)and the iso-scallop height distance field(scalar).The iso-lines of the scalar field and their associated tool orientation field vectors then naturally serve as potential iso-scallop height five-axis tool paths,and we present a propagation-based algorithm to construct the desired tool path from the iso-lines.The computer simulation and physical cutting experiments confirm that everywhere on the surface,except maybe near the saddle curves of the scalar filed,the scallop height is exactly the given thresh-old.By adding the saddle curves as extra tool paths,the final machined surface then is assured of the required scallop height requirement.展开更多
The problem of finished surface being not first-order continuous commonly exists in machining sculptured surfaces with a torus cutter and some other types of cutters. To solve this problem, a dual drive curve tool pat...The problem of finished surface being not first-order continuous commonly exists in machining sculptured surfaces with a torus cutter and some other types of cutters. To solve this problem, a dual drive curve tool path planning method is proposed in this article. First, the maximum machining strip width of a whole tool path can be obtained through optimizing each tool position with multi-point machining （MPM） method. Second, two drive curves are then determined according to the obtained maximum machining strip width. Finally, the tool is positioned once more along the dual drive curve under the condition of tool path smoothness. A computer simulation and cutting experiments are carried out to testify the performance of the new method. The machined surface is measured with a coordinate measuring machine （CMM） to examine the machining quality. The results obtained show that this method can effectively eliminate sharp scallops between adjacent tool paths, keep tool paths smooth, and improve the surface machining quality as well as machining efficiency.展开更多
In milling around sharp corners, residual materials are left at sharp corners when the stepover is extremely long in the contour-parallel tool path. Milling force at the sharp corner rises momentarily due to the incre...In milling around sharp corners, residual materials are left at sharp corners when the stepover is extremely long in the contour-parallel tool path. Milling force at the sharp corner rises momentarily due to the increase of the cutter contact length, thus shortening the tool life and leading to machine chatter, even cutter breakage. Then a tool path improvement method by inserting biarc transition segments in the contour-parallel tool path is proposed for milling the pocket. Using the method, the cutter moves along the biarc transition tool path. And the corner material is removed. The improved tool path is continuous for clearing residual materials at the sharp corner. Finally, the machining experiment validates the proposed method.展开更多
The CAD model of molar prosthesis is usually stored in standard templete library （STIr） format. A new topological structure is given based on STL format and the vertex-based entity offset algorithm is presented to r...The CAD model of molar prosthesis is usually stored in standard templete library （STIr） format. A new topological structure is given based on STL format and the vertex-based entity offset algorithm is presented to realize the rapid generation of roughing/finishing tool path for molar prosthesis. Simulation results show that the proposed algorithm prossesses characteristics of excellent stabilization, fast calculation speed and high machining accuracy.展开更多
The current research of the 5-axis tool positioning algorithm mainly focuses on searching the local optimal tool position without gouging and interference at a cutter contact（CC） point,while not considering the smoo...The current research of the 5-axis tool positioning algorithm mainly focuses on searching the local optimal tool position without gouging and interference at a cutter contact（CC） point,while not considering the smoothness and continuity of a whole tool path.When the surface curvature varies significantly,a local abrupt change of tool paths will happen.The abrupt change has a great influence on surface machining quality.In order to keep generated tool paths smooth and continuous,a five-axis tool positioning algorithm based on smooth tool paths is presented.Firstly,the inclination angle,the tilt angle and offset distance of the tool at a CC point are used as design variables,and the machining strip width is used as an objective function,an optimization model of a local tool positioning algorithm is thus established.Then,a vector equation of tool path is derived by using the above optimization model.By analyzing the equation,the main factors affecting the tool path quality are obtained.Finally,a new tool position optimization model is established,and the detailed process of tool position optimization is also given.An experiment is conducted to machine an aircraft turbine blade by using the proposed algorithm on a 5-axis blade grinding machine,and the machined blade surface is measured with a coordinate measuring machine（CMM）.Experimental and measured results show that the proposed algorithm can ensure tool paths are smooth and continuous,improve the tool path quality,avoid the local abrupt change of tool paths,and enhance machining quality and machining efficiency of sculptured surfaces.展开更多
Machining quality of clean-up region has a strong influence on the performances of the impeller. In order to plan clean-up tool paths rapidly and obtain good finish surface quality, an efficient and robust tool path g...Machining quality of clean-up region has a strong influence on the performances of the impeller. In order to plan clean-up tool paths rapidly and obtain good finish surface quality, an efficient and robust tool path generation method is presented, which employs an approach based on point-searching. The clean-up machining mentioned in this paper is pencil-cut and multilayer fillet-cut for a free-form model with a ball-end cutter. For pencil-cut, the cutter center position can be determined via judging whether it satisfies the distance requirement. After the searching direction and the tracing direction have been determined, by employing the point-searching algorithm with the idea of dichotomy, all the cutter contact （CC） points and cutter location （CL） points can be found and the clean-up boundaries can also be defined rapidly. Then the tool path is generated. Based on the main concept of pencil-cut, a multilayer fillet-cut method is proposed, which utilizes a ball-end cutter with its radius less than the design radius of clean-up region. Using a sequence of intermediate virtual cutters to divide the clean-up region into several layers and given a cusp-height tolerance for the final layer, then the tool paths for all layers are calculated. Finally, computer implementation is also presented in this paper, and the result shows that the proposed method is feasible.展开更多
In order to ensure machining stability,curvature continuity and smooth cutting force are very important so as to meet the constraints of both cutting force and kinematics of machine tools.For five-axis flank milling,i...In order to ensure machining stability,curvature continuity and smooth cutting force are very important so as to meet the constraints of both cutting force and kinematics of machine tools.For five-axis flank milling,it is difficult to meet both of the constraints because tool path points and tool axis vectors interact with each other.In this paper,multiple relationships between tool path points and tool axis vectors with cutting force and kinematics of machine tools are established,and the strategies of corner-looping milling and clothoidal spirals are combined so as to find feasible solutions under both of the constraints.Tool path parameters are iterated by considering the maximum cutting force and the feasible range of the tool axis vector,and eventually a curvature continuity five-axis flank milling tool path with smooth cutting force is generated.Machining experimental results show that the conditions of cutting force are satisfied,vibration during the process of machining is reduced,and the machining quality of the surface is improved.展开更多
Based on the object oriented data structure of Voronoi diagram, the algorithm of the trimmed offset generating and the optimal too l path planning of the pocket machining for multiply connected polygonal domains are ...Based on the object oriented data structure of Voronoi diagram, the algorithm of the trimmed offset generating and the optimal too l path planning of the pocket machining for multiply connected polygonal domains are studied. The intersection state transition rule is improved in this algorithm. The intersection is between the trimmed offsets and Voronoi polygon. On this basis, the trimmed offset generating and the optimal tool path planning are mad e with three stacks(I stack, C stack and P stack)in different monotonous pouches of Voronoi diagram. At the same time, a merging method of Voronoi diagram an d offsets generating for multiply connected polygonal domains is also presented. The above algorithms have been implemented in NC machining successfully, and the efficiency is fully verified.展开更多
Structure design and fabricating methods of three-dimensional （3D） artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial c...Structure design and fabricating methods of three-dimensional （3D） artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial compound eyes. However, spherical optical compound eyes are less at optical performance than the eyes of insects, and it is difficult to further improve the imaging quality of compound eyes by means of micro-nano optical manufacturing. In this research, nonhomogeneous aspheric compound eyes （ACEs） are designed and fabricated. The nonhomogeneous aspheric structure is applied to calibrate the spherical aberration. Micro milling with advantages in processing three-dimensional micro structures is adopted to manufacture ACEs. In order to obtain ACEs with high imaging quality, the tool paths are optimized by analyzing the influence factors consisting of interpolation allowable error, scallop height and tool path pattern. In the experiments, two kinds of ACEs are manufactured by micro-milling with different too path patterns and cutting parameter on the miniature precision five-axis milling machine tool. The experimental results indicate that the ACEs of high surface quality can be achieved by circularly milling small micro-lens individually with changeable cutting depth. A prototype of the aspheric compound eye （ACE） with surface roughness （Ra） below 0.12 p.m is obtained with good imaging performance. This research ameliorates the imaging quality of 3D artificial compound eyes, and the proposed method of micro-milling can improve surface processing quality of compound eyes.展开更多
An impeller is difficult to machine because of severe collision due to the complex shape,overlapping and twisted shape of the impeller blades.So,most computer aided manufacturing(CAM)software companies have developed ...An impeller is difficult to machine because of severe collision due to the complex shape,overlapping and twisted shape of the impeller blades.So,most computer aided manufacturing(CAM)software companies have developed CAM module for manufacturing impeller according to their CAM software.But these dedicated modules are difficult to use for inexperienced users.The purpose of this work is to develop a tool-path generation module for impellers.For this purpose,it is based on Visual Basic language and used CATIA graphical environment.The result of simulation for generated tool-path by the module is satisfactory.And it has slow processing speed compared to other commercial modules,but it is easy to use.展开更多
Ruled surfaces found in engineering parts are often blended with a constraint surface,like the blade surface and hub surface of a centrifugal impeller.It is significant to accurately machine these ruled surfaces in fl...Ruled surfaces found in engineering parts are often blended with a constraint surface,like the blade surface and hub surface of a centrifugal impeller.It is significant to accurately machine these ruled surfaces in flank milling with interference-free and fairing tool path,while current models in fulfilling these goals are complex and rare.In this paper,a tool path planning method with optimal cutter locations(CLs)is proposed for 5-axis flank milling of ruled surfaces under multiple geometric constraints.To be specific,a concise three-point contact tool positioning model is firstly developed for a cylindrical cutter.Different tool orientations arise when varying the three contact positions and a tool orientation pool with acceptable cutter-surface deviation is constructed using a meta-heuristic algorithm.Fairing angular curves are derived from candidates in this pool,and then curve registration for cutter tip point on each determined tool axis is performed in respect of interference avoidance and geometric smoothness.On this basis,an adaptive interval determination model is developed for deviation control of interpolated cutter locations.This model is designed to be independent of the CL optimization process so that multiple CLs can be planned simultaneously with parallel computing technique.Finally,tests are performed on representative surfaces and the results show the method has advantages over previous meta-heuristic tool path planning approaches in both machining accuracy and computation time,and receives the best comprehensive performance compared to other multi-constrained methods when machining an impeller.展开更多
The similarity property of conformal parameterization makes it able to locally preserve the shapes between a surface and its parameter domain, as opposed to common parameterization methods. A parametric tool path plan...The similarity property of conformal parameterization makes it able to locally preserve the shapes between a surface and its parameter domain, as opposed to common parameterization methods. A parametric tool path planning method is proposed in this paper through such parameterization of triangular meshes which is furthermore based on the geodesic on meshes. The parameterization has the properties of local similarity and free boundary which are exploited to simplify the formulas for computing path parameters, which play a fundamentally important role in tool path planning, and keep the path boundary-conformed and smooth. Experimental results are given to illustrate the effectiveness of the proposed methods, as well as the error analysis.展开更多
Sheet metal dieless forming is a new metal forming technology. Thistechnology adopts the principle of rapid prototyping technology, so it can form sheet metal partswithout traditional die and moulds. According to the ...Sheet metal dieless forming is a new metal forming technology. Thistechnology adopts the principle of rapid prototyping technology, so it can form sheet metal partswithout traditional die and moulds. According to the characteristic of sheet metal dieless formingtechnology a new way of tool path generation based on the STL file for sheet metal dieless formingis proposed.展开更多
A global energy fairing method,applied to automated fiber placement(AFP)tool path,was proposed.The main purpose was to improve the adaptability of AFP path towards part with sharp curvature variation as well as produc...A global energy fairing method,applied to automated fiber placement(AFP)tool path,was proposed.The main purpose was to improve the adaptability of AFP path towards part with sharp curvature variation as well as product quality.The relation between path geometric property and manufacturing property was discussed and a series of experiments were carried out.Based on cubic B-Spline global fairing method,the AFP tool path was faired which decreased the tool path curvature and curvature changing rate.Compared with initial ones,the path faired by the proposed method was relatively flat and smooth,which contributed to layup efficiency and reducing bulking defects.The method was demonstrated potentials in application for AFP manufacturing,especially for aeronautic and aerospace industry practice.展开更多
An approach is presented to generate rough interference-free tool-paths directly from massive unorganized data in rough machining that is performed by machining volumes of material in a slice-by-slice manner. Unorgani...An approach is presented to generate rough interference-free tool-paths directly from massive unorganized data in rough machining that is performed by machining volumes of material in a slice-by-slice manner. Unorganized point-cloud is firstly converted to cross-section data. Then a robust data-structure named tool-path net is constructed to save tool-path data. Optimal algorithms for partitioning sub-cut-areas and computing interference-free cutter-locations are put forward. Finally the tool-paths are linked in a zigzag milling mode, which can be transformed into a traveling sales man problem. The experiment indicates optimal tool paths can be acquired, and high computation efficiency can be obtained and interference can be avoided successfully.展开更多
This paper presents a new approach for designing the tool paths in the machining of sculptured surfaces for computer nu- merical controlled end milling. In the proposed method, the tool paths are determined so that th...This paper presents a new approach for designing the tool paths in the machining of sculptured surfaces for computer nu- merical controlled end milling. In the proposed method, the tool paths are determined so that the scallop height formed by two adja- cent machining paths is maintained constant across the machined surface. Unlike previous work on iso-scallop height milling, the present work considers the true 3D configuration of the milling procedure and can be used to generate better results, which is shown by examoles.展开更多
A contour-parallel offset （CPO） tool-path linking algorithm is derived without toolretractions and with the largest practicability. The concept of ＂tool-path loop tree＂ （TPL-tree） providing the information on th...A contour-parallel offset （CPO） tool-path linking algorithm is derived without toolretractions and with the largest practicability. The concept of ＂tool-path loop tree＂ （TPL-tree） providing the information on the parent/child relationships among the tool-path loops （TPLs） is presented. The direction, tool-path loop, leaf/branch, layer number, and the corresponding points of the TPL-tree are introduced. By defining TPL as a vector, and by traveling throughout the tree, a CPO tool-path without tool-retractions can be derived.展开更多
Presents the division of non developable ruled surface into divided small areas and flank milling in these divided areas to improve machining efficiency and machined surface quality by controlling the machining error ...Presents the division of non developable ruled surface into divided small areas and flank milling in these divided areas to improve machining efficiency and machined surface quality by controlling the machining error for each area, and the algorithms developed for generation of tool path and calculation of errors, and concludes from computer simulation results that the algorithms are correct.展开更多
With the increasing market demand for optical complex surface parts,the application of multi-axis ultraprecision single-point diamond turning is increasing.A tool path generation method is very important to decrease m...With the increasing market demand for optical complex surface parts,the application of multi-axis ultraprecision single-point diamond turning is increasing.A tool path generation method is very important to decrease manufacturing time,enhance surface quality,and reduce cost.Compared with the tool path generation of the traditional multi-axis milling,that of the ultra-precision single-point diamond turning requires higher calculation accuracy and efficiency.This paper reviews the tool path generation of ultra-precision diamond turning,considering several key issues:cutter location(CL)points calculation,the topological form of tool path,interpolation mode,and G code optimization.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U22A20202 and 52275477).
文摘Trochoidal milling is known for its advantages in machining difficult-to-machine materials as it facilitates chip removal and tool cooling.However,the conventional trochoidal tool path presents challenges such as lower machining efficiency and longer machining time due to its time-varying cutter-workpiece engagement angle and a high percentage of non-cutting tool paths.To address these issues,this paper introduces a parameter-variant trochoidal-like(PVTR)tool path planning method for chatter-free and high-efficiency milling.This method ensures a constant engagement angle for each tool path period by adjusting the trochoidal radius and step.Initially,the nonlinear equation for the PVTR toolpath is established.Then,a segmented recurrence method is proposed to plan tool paths based on the desired engagement angle.The impact of trochoidal tool path parameters on the engagement angle is analyzed and coupled this information with the milling stability model based on spindle speed and engagement angle to determine the desired engagement angle throughout the machining process.Finally,several experimental tests are carried out using the bull-nose end mill to validate the feasibility and effectiveness of the proposed method.
基金supported in part by Foshan HKUST Projects(FSUST20-SRI09E)the Project of Hetao Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone(HZQB-KCZYB-2020083)the National Science and Technology Major Project (J2019-VII-0001-0141)
文摘Iso-scallop height machining means,when machining a freeform surface,the scallop height between any two neighboring tool paths on the surface will be a constant(i.e.,the given threshold),which is preferable among various freeform surface machining strategies due to its high machining efficiency as well as better machine tool’s dynamics.However,all the existing iso-scallop height path planning methods pertain to only the ball-end or flat-end types of tools.In recent years,the non-spherical cutting tool has become more and more popular,especially for five-axis machining of complex freeform surfaces,majorly owing to its non-constant curvature which can be utilized to adaptively fit the tool to the surface to both avoid the local gouging and enlarge the cutting width.However,there have been no reported works on iso-scallop height five-axis tool path generation for a non-spherical tool,and,in this paper,we present one.Specifically,we first define and construct two fields on the surface to be machined-the collision-free tool orientation field(vector)and the iso-scallop height distance field(scalar).The iso-lines of the scalar field and their associated tool orientation field vectors then naturally serve as potential iso-scallop height five-axis tool paths,and we present a propagation-based algorithm to construct the desired tool path from the iso-lines.The computer simulation and physical cutting experiments confirm that everywhere on the surface,except maybe near the saddle curves of the scalar filed,the scallop height is exactly the given thresh-old.By adding the saddle curves as extra tool paths,the final machined surface then is assured of the required scallop height requirement.
基金National Natural Science Foundation of China (50875012)National High-tech Research and Development Program (2008AA04Z124)+1 种基金National Science and Technology Major Project (2009ZX04001-141)Joint Construction Project of Beijing Municipal Commission of Education
文摘The problem of finished surface being not first-order continuous commonly exists in machining sculptured surfaces with a torus cutter and some other types of cutters. To solve this problem, a dual drive curve tool path planning method is proposed in this article. First, the maximum machining strip width of a whole tool path can be obtained through optimizing each tool position with multi-point machining （MPM） method. Second, two drive curves are then determined according to the obtained maximum machining strip width. Finally, the tool is positioned once more along the dual drive curve under the condition of tool path smoothness. A computer simulation and cutting experiments are carried out to testify the performance of the new method. The machined surface is measured with a coordinate measuring machine （CMM） to examine the machining quality. The results obtained show that this method can effectively eliminate sharp scallops between adjacent tool paths, keep tool paths smooth, and improve the surface machining quality as well as machining efficiency.
文摘In milling around sharp corners, residual materials are left at sharp corners when the stepover is extremely long in the contour-parallel tool path. Milling force at the sharp corner rises momentarily due to the increase of the cutter contact length, thus shortening the tool life and leading to machine chatter, even cutter breakage. Then a tool path improvement method by inserting biarc transition segments in the contour-parallel tool path is proposed for milling the pocket. Using the method, the cutter moves along the biarc transition tool path. And the corner material is removed. The improved tool path is continuous for clearing residual materials at the sharp corner. Finally, the machining experiment validates the proposed method.
文摘The CAD model of molar prosthesis is usually stored in standard templete library （STIr） format. A new topological structure is given based on STL format and the vertex-based entity offset algorithm is presented to realize the rapid generation of roughing/finishing tool path for molar prosthesis. Simulation results show that the proposed algorithm prossesses characteristics of excellent stabilization, fast calculation speed and high machining accuracy.
基金supported by National Natural Science Foundation of China (Grant No. 50875012)National Hi-tech Research and Development Program of China (863 Program, Grant No. 2008AA04Z124)+1 种基金National Science and Technology Major Project of China (Grant No. 2009ZX04001-141)Joint Construction Project of Beijing Municipal Commission of Education of China
文摘The current research of the 5-axis tool positioning algorithm mainly focuses on searching the local optimal tool position without gouging and interference at a cutter contact（CC） point,while not considering the smoothness and continuity of a whole tool path.When the surface curvature varies significantly,a local abrupt change of tool paths will happen.The abrupt change has a great influence on surface machining quality.In order to keep generated tool paths smooth and continuous,a five-axis tool positioning algorithm based on smooth tool paths is presented.Firstly,the inclination angle,the tilt angle and offset distance of the tool at a CC point are used as design variables,and the machining strip width is used as an objective function,an optimization model of a local tool positioning algorithm is thus established.Then,a vector equation of tool path is derived by using the above optimization model.By analyzing the equation,the main factors affecting the tool path quality are obtained.Finally,a new tool position optimization model is established,and the detailed process of tool position optimization is also given.An experiment is conducted to machine an aircraft turbine blade by using the proposed algorithm on a 5-axis blade grinding machine,and the machined blade surface is measured with a coordinate measuring machine（CMM）.Experimental and measured results show that the proposed algorithm can ensure tool paths are smooth and continuous,improve the tool path quality,avoid the local abrupt change of tool paths,and enhance machining quality and machining efficiency of sculptured surfaces.
基金National Natural Science Foundation of China （51005183） National Science and Technology Major Project （2011X04016-031）
文摘Machining quality of clean-up region has a strong influence on the performances of the impeller. In order to plan clean-up tool paths rapidly and obtain good finish surface quality, an efficient and robust tool path generation method is presented, which employs an approach based on point-searching. The clean-up machining mentioned in this paper is pencil-cut and multilayer fillet-cut for a free-form model with a ball-end cutter. For pencil-cut, the cutter center position can be determined via judging whether it satisfies the distance requirement. After the searching direction and the tracing direction have been determined, by employing the point-searching algorithm with the idea of dichotomy, all the cutter contact （CC） points and cutter location （CL） points can be found and the clean-up boundaries can also be defined rapidly. Then the tool path is generated. Based on the main concept of pencil-cut, a multilayer fillet-cut method is proposed, which utilizes a ball-end cutter with its radius less than the design radius of clean-up region. Using a sequence of intermediate virtual cutters to divide the clean-up region into several layers and given a cusp-height tolerance for the final layer, then the tool paths for all layers are calculated. Finally, computer implementation is also presented in this paper, and the result shows that the proposed method is feasible.
基金supported by the National Natural Science Foundation of Chin-China Aerospace Science and Technology Corporation on Advance Manufacturing(No.U1537209)National Natural Science Foundation of China(No.51775278)Jiangsu Province Outstanding Youth Fund of China(No.BK20140036).
文摘In order to ensure machining stability,curvature continuity and smooth cutting force are very important so as to meet the constraints of both cutting force and kinematics of machine tools.For five-axis flank milling,it is difficult to meet both of the constraints because tool path points and tool axis vectors interact with each other.In this paper,multiple relationships between tool path points and tool axis vectors with cutting force and kinematics of machine tools are established,and the strategies of corner-looping milling and clothoidal spirals are combined so as to find feasible solutions under both of the constraints.Tool path parameters are iterated by considering the maximum cutting force and the feasible range of the tool axis vector,and eventually a curvature continuity five-axis flank milling tool path with smooth cutting force is generated.Machining experimental results show that the conditions of cutting force are satisfied,vibration during the process of machining is reduced,and the machining quality of the surface is improved.
文摘Based on the object oriented data structure of Voronoi diagram, the algorithm of the trimmed offset generating and the optimal too l path planning of the pocket machining for multiply connected polygonal domains are studied. The intersection state transition rule is improved in this algorithm. The intersection is between the trimmed offsets and Voronoi polygon. On this basis, the trimmed offset generating and the optimal tool path planning are mad e with three stacks(I stack, C stack and P stack)in different monotonous pouches of Voronoi diagram. At the same time, a merging method of Voronoi diagram an d offsets generating for multiply connected polygonal domains is also presented. The above algorithms have been implemented in NC machining successfully, and the efficiency is fully verified.
基金Supported by National Natural Science Foundation of China(Grant No.50935003)National Numerical Control Major Projects of China(Grant No.2013ZX04001000215)
文摘Structure design and fabricating methods of three-dimensional （3D） artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial compound eyes. However, spherical optical compound eyes are less at optical performance than the eyes of insects, and it is difficult to further improve the imaging quality of compound eyes by means of micro-nano optical manufacturing. In this research, nonhomogeneous aspheric compound eyes （ACEs） are designed and fabricated. The nonhomogeneous aspheric structure is applied to calibrate the spherical aberration. Micro milling with advantages in processing three-dimensional micro structures is adopted to manufacture ACEs. In order to obtain ACEs with high imaging quality, the tool paths are optimized by analyzing the influence factors consisting of interpolation allowable error, scallop height and tool path pattern. In the experiments, two kinds of ACEs are manufactured by micro-milling with different too path patterns and cutting parameter on the miniature precision five-axis milling machine tool. The experimental results indicate that the ACEs of high surface quality can be achieved by circularly milling small micro-lens individually with changeable cutting depth. A prototype of the aspheric compound eye （ACE） with surface roughness （Ra） below 0.12 p.m is obtained with good imaging performance. This research ameliorates the imaging quality of 3D artificial compound eyes, and the proposed method of micro-milling can improve surface processing quality of compound eyes.
基金Project supported by the Second Stage of Brain Korea 21 Projects
文摘An impeller is difficult to machine because of severe collision due to the complex shape,overlapping and twisted shape of the impeller blades.So,most computer aided manufacturing(CAM)software companies have developed CAM module for manufacturing impeller according to their CAM software.But these dedicated modules are difficult to use for inexperienced users.The purpose of this work is to develop a tool-path generation module for impellers.For this purpose,it is based on Visual Basic language and used CATIA graphical environment.The result of simulation for generated tool-path by the module is satisfactory.And it has slow processing speed compared to other commercial modules,but it is easy to use.
基金supported by the National Natural Science Foundation of China(Nos.U22A20202 and 52205516)the China Postdoctoral Science Foundation(No.2022 M720641)。
文摘Ruled surfaces found in engineering parts are often blended with a constraint surface,like the blade surface and hub surface of a centrifugal impeller.It is significant to accurately machine these ruled surfaces in flank milling with interference-free and fairing tool path,while current models in fulfilling these goals are complex and rare.In this paper,a tool path planning method with optimal cutter locations(CLs)is proposed for 5-axis flank milling of ruled surfaces under multiple geometric constraints.To be specific,a concise three-point contact tool positioning model is firstly developed for a cylindrical cutter.Different tool orientations arise when varying the three contact positions and a tool orientation pool with acceptable cutter-surface deviation is constructed using a meta-heuristic algorithm.Fairing angular curves are derived from candidates in this pool,and then curve registration for cutter tip point on each determined tool axis is performed in respect of interference avoidance and geometric smoothness.On this basis,an adaptive interval determination model is developed for deviation control of interpolated cutter locations.This model is designed to be independent of the CL optimization process so that multiple CLs can be planned simultaneously with parallel computing technique.Finally,tests are performed on representative surfaces and the results show the method has advantages over previous meta-heuristic tool path planning approaches in both machining accuracy and computation time,and receives the best comprehensive performance compared to other multi-constrained methods when machining an impeller.
基金supported by the National Program on Key Basic Research Project of China (No. 2011CB302400)the National Natural Science Foundation of China (No. 51175495)
文摘The similarity property of conformal parameterization makes it able to locally preserve the shapes between a surface and its parameter domain, as opposed to common parameterization methods. A parametric tool path planning method is proposed in this paper through such parameterization of triangular meshes which is furthermore based on the geodesic on meshes. The parameterization has the properties of local similarity and free boundary which are exploited to simplify the formulas for computing path parameters, which play a fundamentally important role in tool path planning, and keep the path boundary-conformed and smooth. Experimental results are given to illustrate the effectiveness of the proposed methods, as well as the error analysis.
基金This project is supported by National Natural Science Foundation of China(No.50175034).
文摘Sheet metal dieless forming is a new metal forming technology. Thistechnology adopts the principle of rapid prototyping technology, so it can form sheet metal partswithout traditional die and moulds. According to the characteristic of sheet metal dieless formingtechnology a new way of tool path generation based on the STL file for sheet metal dieless formingis proposed.
基金supported by the Major Science and Technology Projects of China (No.2016ZX04002-001-07)Basic Scientific Research Fund(56XAA15057)
文摘A global energy fairing method,applied to automated fiber placement(AFP)tool path,was proposed.The main purpose was to improve the adaptability of AFP path towards part with sharp curvature variation as well as product quality.The relation between path geometric property and manufacturing property was discussed and a series of experiments were carried out.Based on cubic B-Spline global fairing method,the AFP tool path was faired which decreased the tool path curvature and curvature changing rate.Compared with initial ones,the path faired by the proposed method was relatively flat and smooth,which contributed to layup efficiency and reducing bulking defects.The method was demonstrated potentials in application for AFP manufacturing,especially for aeronautic and aerospace industry practice.
文摘An approach is presented to generate rough interference-free tool-paths directly from massive unorganized data in rough machining that is performed by machining volumes of material in a slice-by-slice manner. Unorganized point-cloud is firstly converted to cross-section data. Then a robust data-structure named tool-path net is constructed to save tool-path data. Optimal algorithms for partitioning sub-cut-areas and computing interference-free cutter-locations are put forward. Finally the tool-paths are linked in a zigzag milling mode, which can be transformed into a traveling sales man problem. The experiment indicates optimal tool paths can be acquired, and high computation efficiency can be obtained and interference can be avoided successfully.
基金Partially supported by a grant from NSFC (60821002)
文摘This paper presents a new approach for designing the tool paths in the machining of sculptured surfaces for computer nu- merical controlled end milling. In the proposed method, the tool paths are determined so that the scallop height formed by two adja- cent machining paths is maintained constant across the machined surface. Unlike previous work on iso-scallop height milling, the present work considers the true 3D configuration of the milling procedure and can be used to generate better results, which is shown by examoles.
文摘A contour-parallel offset （CPO） tool-path linking algorithm is derived without toolretractions and with the largest practicability. The concept of ＂tool-path loop tree＂ （TPL-tree） providing the information on the parent/child relationships among the tool-path loops （TPLs） is presented. The direction, tool-path loop, leaf/branch, layer number, and the corresponding points of the TPL-tree are introduced. By defining TPL as a vector, and by traveling throughout the tree, a CPO tool-path without tool-retractions can be derived.
文摘Presents the division of non developable ruled surface into divided small areas and flank milling in these divided areas to improve machining efficiency and machined surface quality by controlling the machining error for each area, and the algorithms developed for generation of tool path and calculation of errors, and concludes from computer simulation results that the algorithms are correct.
基金supports of the Funds for the National Natural Science Foundation of China [grant numbers 51575386,51275344]
文摘With the increasing market demand for optical complex surface parts,the application of multi-axis ultraprecision single-point diamond turning is increasing.A tool path generation method is very important to decrease manufacturing time,enhance surface quality,and reduce cost.Compared with the tool path generation of the traditional multi-axis milling,that of the ultra-precision single-point diamond turning requires higher calculation accuracy and efficiency.This paper reviews the tool path generation of ultra-precision diamond turning,considering several key issues:cutter location(CL)points calculation,the topological form of tool path,interpolation mode,and G code optimization.
