Journal of the Korean Society of Manufacturing Process Engineers, Oct 31, 2019
Recently, lightweight materials such as Ti alloys have been used increasingly in the aerospace an... more Recently, lightweight materials such as Ti alloys have been used increasingly in the aerospace and high-tech industries for weight loss and fuel efficiency. Because of built-up edges and workpiece deflection due to low stiffness, the Ti alloys have poor machinability. In our study, systematic experiments were conducted to investigate the milling characteristics of the Ti alloy (Ti-6A1-4V) with endmills. The independent variables in the experiment were spindle speed, feed per tooth, and axial depth. Cutting force, acceleration RMS, and surface roughness were measured. Using the response surface method, the optimal cutting conditions were analyzed to improve machining quality and productivity.
Journal of the Korean Society for Precision Engineering, 1997
In process planning for pocket machining, the selection of tool size, tool path, overlap distance... more In process planning for pocket machining, the selection of tool size, tool path, overlap distance, and the calculation of machining time are very important factors to obtain the optimal process planning result. Among those factors, the tool size is the most important one because the others depend on tool size. And also, it is not easy to determine the optimal tool size even though the shape of pocket is simple. Therefore, the optimal selection of tool size is the most essential task in process planning for machining a pocket. This paper presents a method for selecting optimal toos in pocket machining. The branch and bound method is applied to select the optimal tools which minimize the machining time by using the range of feasible tools and the breadth-first search.
3D solid models for parts with regular-form surfaces (PRFSs) are effectively generated using trad... more 3D solid models for parts with regular-form surfaces (PRFSs) are effectively generated using traditional parametric design techniques. A new model is obtained by changing some parameters defining the model. The parts with free-form surfaces (PFFSs), however, cannot be defined by several parameters. Usually they are defined by some geometric elements like profile curves. The traditional parametric design approaches have not easily dealt with the PFFSs. A method for generating a solid model and an engineering drawing for PFFSs is proposed in this paper: First, the new profiles are generated from input point data. Second, the profile information is extracted from the existing model. Last, the old profiles are replaced with the new profiles. This method can preserve the associative information of the existing model and automatically generate the drawing including views, dimensions, and annotations. The proposed method has been implemented using a commercial CAD/CAM system, Unigraphics, and API functions written in C-language, and were applied to the blades of a turbine generator. Some illustrative examples are provided in order to show the effectiveness of the proposed method.
In process planning for pocket machining, selection of tool size, tool path, cutting width at eac... more In process planning for pocket machining, selection of tool size, tool path, cutting width at each tool path, and calculation of machining time are very important factors for optimal process planning. The tool size is the most important factor because the other factors depend on tool size. Therefore, the optimal selection of tool size is the most essential task in pocket machining process planning. This paper presents a method for selecting optimal tools for pocket machining for the components of injection mold. The branch and bound method is applied to select the optimal tools which minimize the machining time by using the range of feasible tools and the breadth-first search.
Robotics and Computer-integrated Manufacturing, Feb 1, 2001
Polishing a die that has free-form surfaces is a time-consuming and tedious job, and requires a c... more Polishing a die that has free-form surfaces is a time-consuming and tedious job, and requires a considerable amount of high-precision skill. In order to reduce the polishing time and cope with the shortage of skilled workers, a user-friendly automatic polishing system was developed in this research. The polishing system is composed of two subsystems, a three-axis machining center and a two-axis polishing robot. The developed polishing system with "ve degrees of freedom is able to keep the polishing tool normal to the die surface during operation. A sliding mode control algorithm with velocity compensation is proposed to reduce tracking errors. Trajectory tracking experiments showed that the e!ect of reducing the tracking error by the proposed sliding mode control is superior to that by the proportional derivative control. The polishing data is generated from computer-aided design (CAD) data or from teaching data by PolyCAM, a computer-aided manufacturing (CAM) system consisting of 4 modules: a geometric modeller, a CAD data exchange module, a polishing data generation module, and a graphic simulator. To evaluate the performance of the polishing robot system, some polishing experiments on a shadow-mask die were performed.
Journal of Korean Institute of Industrial Engineers, 1993
Cutter Interference(or part surface gouging) is one of the most critical problems in NC machining... more Cutter Interference(or part surface gouging) is one of the most critical problems in NC machining of sculptured surfaces. Presented in this paper is and algorithmic procedure that converts CC data obtained from a compound surface(several surfaces without topological relationship) into interference-free CL data. The interference handling procedure consists of following steps: (1) Z-map model is constructed from input surfaces. (2) Interference sources are detected using local properties of the sources. (3) Interference regions are completely identified based on global tests for neighboring CC points of the interference sources (4) Cutter paths are reconstructed after removing the CC data in interference regions, while avoiding any new interferences.
Korean Journal of Computational Design and Engineering, 2008
In order to survive worldwide competition, today's industries are experiencing strong pressur... more In order to survive worldwide competition, today's industries are experiencing strong pressure to introduce higher quality products with lower cost and shorter lead-time. Therefore, the role of design in the process of product development is increasing in significance. In this research, two methods for improving the design capability are proposed: construction of design environment and design automation using 3D CAD system. The designers and design process are the core of product design using 3D CAD system. In order to maximize the design performance, construction of the design environment including selection of a suitable system, designer training for best use of the system, establishment of an efficient design process, and stabilization of the environment are required. A method is suggested to construct design environment by systematizing the contents of the projects and consulting experiences carried out for various categories of business such as electronic devices, motorcycles, electricity parts, sanitary wares, injection molds, and die casing molds. Design automation helps reduce tedious and time-consuming jobs, simplify complicated and error-prone modeling and drawing works to shorten the lead time and improve the product quality. To develop a design automation system, understanding the process and the related knowledge on design are very important before implementing the system using API provided by 3D CAD system. In this research, an eight-step procedure is proposed for the development of a design automation system. These eight steps are analysis of needs, determination of specification, verification of specification using 3D CAD system, inspection of related API functions, programming, field test, application in practice, and maintenance. A case study in which five design automation systems in the design of turbine generators using the proposed method is introduced in detail. These systems play important roles in the generation of various output items including 3D models, drafts, material information, and NC data. The case study shows how effectively the design time is reduced and the quality improved using those systems.
This paper presents a new efficient and robust tool-path generation methods for clean-up machinin... more This paper presents a new efficient and robust tool-path generation methods for clean-up machining by employing a curve-based approach. The clean-up machining to be discussed in this paper are pencil-cut and fillet-cut for a polyhedral model of the STL form with a ball-end mill. The pencil-cut and fillet-cut paths are obtained from the curve-based scanning tool paths on the xz, yz, and xy planes. The scanning tool path has exact sharp-concave points and bi-contact vectors, both of which are very useful to detect 'pencil-points', trace the pencil-cut path, and generate the filletcut path. In the paper, some illustrative examples are provided, and the characteristics of the proposed method are discussed.
Journal of the Korean Society of Manufacturing Process Engineers
Titanium alloy (Ti-6Al-4V) has excellent mechanical properties and high specific strength; theref... more Titanium alloy (Ti-6Al-4V) has excellent mechanical properties and high specific strength; therefore, it is widely used in aerospace, automobile, defense, engine parts, and bio fields. Particularly in the aerospace field, as it has a low specific gravity and rigidity, it is used for the purpose of increasing energy efficiency through weight reduction of parts, and most have a thin-walled structure. However, it is extremely difficult to machine thin-walled shapes owing to vibration and deformation. In the case of thin-walled structures, the cutting forces and vibrations rapidly increase depending on the cutting conditions, significantly affecting the surface integrity and tool life. In this study, machining experiments on thin-wall milling of a titanium alloy (Ti-6Al-4V) were conducted for each experimental condition with different axial depths of cut, radial depth of cut, and machining sequence. The machining characteristics were analyzed, and an effective machining method was derived by a comprehensive analysis of the machined surface conditions and cutting signals.
A method for cutting non-circular holes on a bent thick plate is proposed. Generally, in order to... more A method for cutting non-circular holes on a bent thick plate is proposed. Generally, in order to cut holes on large plates, a special-purpose 5-axis machine is needed. However, such a machine is unavailable in most machine shops. This paper provides a description of a method that utilizes a generalpurpose 5-axis water-jet machine in place of the specialpurpose machine: First, the bent piece is transformed into a flat plate, where the shape of the holes is reconstructed by considering deformation during bending. Then, after 5-axis NC data is generated, the holes on the flat plate are cut using the 5-axis water-jet machine. In the final step, the desired shape of the piece is obtained by bending the plate with its newly-cut holes. Some illustrations are provided in order to show the validity of the proposed method.
Korean Journal of Computational Design and Engineering, 2010
Developed in this research is a TP (tangible prototyping) system, which consists of two modules; ... more Developed in this research is a TP (tangible prototyping) system, which consists of two modules; (1) a virtual reality model to evaluate the functions and appearance of the product, and (2) a haptic device to emulate tactile and kinesthetic properties of mechanical dial knobs. As an example, a washing machine is modeled using a commercial CAD system and transformed in VRML and X3D formats. Some dynamic behaviors and kinematic characteristics are programmed using X3D script and Java. Various haptic behaviors of the dial are generated by modulating torque profile according to the rotation angle. A torque profile measuring system is developed to evaluate the behaviors of the haptic dial physically. Haptic sensibility evaluations are accomplished using the TP by semantic differential method.
Journal of the Korean Society for Precision Engineering, 1997
In process planning for pocket machining, the selection of tool size, tool path, overlap distance... more In process planning for pocket machining, the selection of tool size, tool path, overlap distance, and the calculation of machining time are very important factors to obtain the optimal process planning result. Among those factors, the tool size is the most important one because the others depend on tool size. And also, it is not easy to determine the optimal tool size even though the shape of pocket is simple. Therefore, the optimal selection of tool size is the most essential task in process planning for machining a pocket. This paper presents a method for selecting optimal toos in pocket machining. The branch and bound method is applied to select the optimal tools which minimize the machining time by using the range of feasible tools and the breadth-first search.
Cutter Interference(or part surface gouging) is one of the most critical problems in NC machining... more Cutter Interference(or part surface gouging) is one of the most critical problems in NC machining of sculptured surfaces. Presented in this paper is and algorithmic procedure that converts CC data obtained from a compound surface(several surfaces without topological relationship) into interference-free CL data. The interference handling procedure consists of following steps: (1) Z-map model is constructed from input surfaces. (2) Interference sources are detected using local properties of the sources. (3) Interference regions are completely identified based on global tests for neighboring CC points of the interference sources (4) Cutter paths are reconstructed after removing the CC data in interference regions, while avoiding any new interferences.
Korean Journal of Computational Design and Engineering, 2008
In order to survive worldwide competition, today's industries are experiencing strong pressur... more In order to survive worldwide competition, today's industries are experiencing strong pressure to introduce higher quality products with lower cost and shorter lead-time. Therefore, the role of design in the process of product development is increasing in significance. In this research, two methods for improving the design capability are proposed: construction of design environment and design automation using 3D CAD system. The designers and design process are the core of product design using 3D CAD system. In order to maximize the design performance, construction of the design environment including selection of a suitable system, designer training for best use of the system, establishment of an efficient design process, and stabilization of the environment are required. A method is suggested to construct design environment by systematizing the contents of the projects and consulting experiences carried out for various categories of business such as electronic devices, motorcycl...
Journal of the Korean Society of Manufacturing Process Engineers, 2019
Recently, lightweight materials such as Ti alloys have been used increasingly in the aerospace an... more Recently, lightweight materials such as Ti alloys have been used increasingly in the aerospace and high-tech industries for weight loss and fuel efficiency. Because of built-up edges and workpiece deflection due to low stiffness, the Ti alloys have poor machinability. In our study, systematic experiments were conducted to investigate the milling characteristics of the Ti alloy (Ti-6A1-4V) with endmills. The independent variables in the experiment were spindle speed, feed per tooth, and axial depth. Cutting force, acceleration RMS, and surface roughness were measured. Using the response surface method, the optimal cutting conditions were analyzed to improve machining quality and productivity.
Journal of the Korean Society of Manufacturing Process Engineers, Oct 31, 2019
Recently, lightweight materials such as Ti alloys have been used increasingly in the aerospace an... more Recently, lightweight materials such as Ti alloys have been used increasingly in the aerospace and high-tech industries for weight loss and fuel efficiency. Because of built-up edges and workpiece deflection due to low stiffness, the Ti alloys have poor machinability. In our study, systematic experiments were conducted to investigate the milling characteristics of the Ti alloy (Ti-6A1-4V) with endmills. The independent variables in the experiment were spindle speed, feed per tooth, and axial depth. Cutting force, acceleration RMS, and surface roughness were measured. Using the response surface method, the optimal cutting conditions were analyzed to improve machining quality and productivity.
Journal of the Korean Society for Precision Engineering, 1997
In process planning for pocket machining, the selection of tool size, tool path, overlap distance... more In process planning for pocket machining, the selection of tool size, tool path, overlap distance, and the calculation of machining time are very important factors to obtain the optimal process planning result. Among those factors, the tool size is the most important one because the others depend on tool size. And also, it is not easy to determine the optimal tool size even though the shape of pocket is simple. Therefore, the optimal selection of tool size is the most essential task in process planning for machining a pocket. This paper presents a method for selecting optimal toos in pocket machining. The branch and bound method is applied to select the optimal tools which minimize the machining time by using the range of feasible tools and the breadth-first search.
3D solid models for parts with regular-form surfaces (PRFSs) are effectively generated using trad... more 3D solid models for parts with regular-form surfaces (PRFSs) are effectively generated using traditional parametric design techniques. A new model is obtained by changing some parameters defining the model. The parts with free-form surfaces (PFFSs), however, cannot be defined by several parameters. Usually they are defined by some geometric elements like profile curves. The traditional parametric design approaches have not easily dealt with the PFFSs. A method for generating a solid model and an engineering drawing for PFFSs is proposed in this paper: First, the new profiles are generated from input point data. Second, the profile information is extracted from the existing model. Last, the old profiles are replaced with the new profiles. This method can preserve the associative information of the existing model and automatically generate the drawing including views, dimensions, and annotations. The proposed method has been implemented using a commercial CAD/CAM system, Unigraphics, and API functions written in C-language, and were applied to the blades of a turbine generator. Some illustrative examples are provided in order to show the effectiveness of the proposed method.
In process planning for pocket machining, selection of tool size, tool path, cutting width at eac... more In process planning for pocket machining, selection of tool size, tool path, cutting width at each tool path, and calculation of machining time are very important factors for optimal process planning. The tool size is the most important factor because the other factors depend on tool size. Therefore, the optimal selection of tool size is the most essential task in pocket machining process planning. This paper presents a method for selecting optimal tools for pocket machining for the components of injection mold. The branch and bound method is applied to select the optimal tools which minimize the machining time by using the range of feasible tools and the breadth-first search.
Robotics and Computer-integrated Manufacturing, Feb 1, 2001
Polishing a die that has free-form surfaces is a time-consuming and tedious job, and requires a c... more Polishing a die that has free-form surfaces is a time-consuming and tedious job, and requires a considerable amount of high-precision skill. In order to reduce the polishing time and cope with the shortage of skilled workers, a user-friendly automatic polishing system was developed in this research. The polishing system is composed of two subsystems, a three-axis machining center and a two-axis polishing robot. The developed polishing system with "ve degrees of freedom is able to keep the polishing tool normal to the die surface during operation. A sliding mode control algorithm with velocity compensation is proposed to reduce tracking errors. Trajectory tracking experiments showed that the e!ect of reducing the tracking error by the proposed sliding mode control is superior to that by the proportional derivative control. The polishing data is generated from computer-aided design (CAD) data or from teaching data by PolyCAM, a computer-aided manufacturing (CAM) system consisting of 4 modules: a geometric modeller, a CAD data exchange module, a polishing data generation module, and a graphic simulator. To evaluate the performance of the polishing robot system, some polishing experiments on a shadow-mask die were performed.
Journal of Korean Institute of Industrial Engineers, 1993
Cutter Interference(or part surface gouging) is one of the most critical problems in NC machining... more Cutter Interference(or part surface gouging) is one of the most critical problems in NC machining of sculptured surfaces. Presented in this paper is and algorithmic procedure that converts CC data obtained from a compound surface(several surfaces without topological relationship) into interference-free CL data. The interference handling procedure consists of following steps: (1) Z-map model is constructed from input surfaces. (2) Interference sources are detected using local properties of the sources. (3) Interference regions are completely identified based on global tests for neighboring CC points of the interference sources (4) Cutter paths are reconstructed after removing the CC data in interference regions, while avoiding any new interferences.
Korean Journal of Computational Design and Engineering, 2008
In order to survive worldwide competition, today's industries are experiencing strong pressur... more In order to survive worldwide competition, today's industries are experiencing strong pressure to introduce higher quality products with lower cost and shorter lead-time. Therefore, the role of design in the process of product development is increasing in significance. In this research, two methods for improving the design capability are proposed: construction of design environment and design automation using 3D CAD system. The designers and design process are the core of product design using 3D CAD system. In order to maximize the design performance, construction of the design environment including selection of a suitable system, designer training for best use of the system, establishment of an efficient design process, and stabilization of the environment are required. A method is suggested to construct design environment by systematizing the contents of the projects and consulting experiences carried out for various categories of business such as electronic devices, motorcycles, electricity parts, sanitary wares, injection molds, and die casing molds. Design automation helps reduce tedious and time-consuming jobs, simplify complicated and error-prone modeling and drawing works to shorten the lead time and improve the product quality. To develop a design automation system, understanding the process and the related knowledge on design are very important before implementing the system using API provided by 3D CAD system. In this research, an eight-step procedure is proposed for the development of a design automation system. These eight steps are analysis of needs, determination of specification, verification of specification using 3D CAD system, inspection of related API functions, programming, field test, application in practice, and maintenance. A case study in which five design automation systems in the design of turbine generators using the proposed method is introduced in detail. These systems play important roles in the generation of various output items including 3D models, drafts, material information, and NC data. The case study shows how effectively the design time is reduced and the quality improved using those systems.
This paper presents a new efficient and robust tool-path generation methods for clean-up machinin... more This paper presents a new efficient and robust tool-path generation methods for clean-up machining by employing a curve-based approach. The clean-up machining to be discussed in this paper are pencil-cut and fillet-cut for a polyhedral model of the STL form with a ball-end mill. The pencil-cut and fillet-cut paths are obtained from the curve-based scanning tool paths on the xz, yz, and xy planes. The scanning tool path has exact sharp-concave points and bi-contact vectors, both of which are very useful to detect 'pencil-points', trace the pencil-cut path, and generate the filletcut path. In the paper, some illustrative examples are provided, and the characteristics of the proposed method are discussed.
Journal of the Korean Society of Manufacturing Process Engineers
Titanium alloy (Ti-6Al-4V) has excellent mechanical properties and high specific strength; theref... more Titanium alloy (Ti-6Al-4V) has excellent mechanical properties and high specific strength; therefore, it is widely used in aerospace, automobile, defense, engine parts, and bio fields. Particularly in the aerospace field, as it has a low specific gravity and rigidity, it is used for the purpose of increasing energy efficiency through weight reduction of parts, and most have a thin-walled structure. However, it is extremely difficult to machine thin-walled shapes owing to vibration and deformation. In the case of thin-walled structures, the cutting forces and vibrations rapidly increase depending on the cutting conditions, significantly affecting the surface integrity and tool life. In this study, machining experiments on thin-wall milling of a titanium alloy (Ti-6Al-4V) were conducted for each experimental condition with different axial depths of cut, radial depth of cut, and machining sequence. The machining characteristics were analyzed, and an effective machining method was derived by a comprehensive analysis of the machined surface conditions and cutting signals.
A method for cutting non-circular holes on a bent thick plate is proposed. Generally, in order to... more A method for cutting non-circular holes on a bent thick plate is proposed. Generally, in order to cut holes on large plates, a special-purpose 5-axis machine is needed. However, such a machine is unavailable in most machine shops. This paper provides a description of a method that utilizes a generalpurpose 5-axis water-jet machine in place of the specialpurpose machine: First, the bent piece is transformed into a flat plate, where the shape of the holes is reconstructed by considering deformation during bending. Then, after 5-axis NC data is generated, the holes on the flat plate are cut using the 5-axis water-jet machine. In the final step, the desired shape of the piece is obtained by bending the plate with its newly-cut holes. Some illustrations are provided in order to show the validity of the proposed method.
Korean Journal of Computational Design and Engineering, 2010
Developed in this research is a TP (tangible prototyping) system, which consists of two modules; ... more Developed in this research is a TP (tangible prototyping) system, which consists of two modules; (1) a virtual reality model to evaluate the functions and appearance of the product, and (2) a haptic device to emulate tactile and kinesthetic properties of mechanical dial knobs. As an example, a washing machine is modeled using a commercial CAD system and transformed in VRML and X3D formats. Some dynamic behaviors and kinematic characteristics are programmed using X3D script and Java. Various haptic behaviors of the dial are generated by modulating torque profile according to the rotation angle. A torque profile measuring system is developed to evaluate the behaviors of the haptic dial physically. Haptic sensibility evaluations are accomplished using the TP by semantic differential method.
Journal of the Korean Society for Precision Engineering, 1997
In process planning for pocket machining, the selection of tool size, tool path, overlap distance... more In process planning for pocket machining, the selection of tool size, tool path, overlap distance, and the calculation of machining time are very important factors to obtain the optimal process planning result. Among those factors, the tool size is the most important one because the others depend on tool size. And also, it is not easy to determine the optimal tool size even though the shape of pocket is simple. Therefore, the optimal selection of tool size is the most essential task in process planning for machining a pocket. This paper presents a method for selecting optimal toos in pocket machining. The branch and bound method is applied to select the optimal tools which minimize the machining time by using the range of feasible tools and the breadth-first search.
Cutter Interference(or part surface gouging) is one of the most critical problems in NC machining... more Cutter Interference(or part surface gouging) is one of the most critical problems in NC machining of sculptured surfaces. Presented in this paper is and algorithmic procedure that converts CC data obtained from a compound surface(several surfaces without topological relationship) into interference-free CL data. The interference handling procedure consists of following steps: (1) Z-map model is constructed from input surfaces. (2) Interference sources are detected using local properties of the sources. (3) Interference regions are completely identified based on global tests for neighboring CC points of the interference sources (4) Cutter paths are reconstructed after removing the CC data in interference regions, while avoiding any new interferences.
Korean Journal of Computational Design and Engineering, 2008
In order to survive worldwide competition, today's industries are experiencing strong pressur... more In order to survive worldwide competition, today's industries are experiencing strong pressure to introduce higher quality products with lower cost and shorter lead-time. Therefore, the role of design in the process of product development is increasing in significance. In this research, two methods for improving the design capability are proposed: construction of design environment and design automation using 3D CAD system. The designers and design process are the core of product design using 3D CAD system. In order to maximize the design performance, construction of the design environment including selection of a suitable system, designer training for best use of the system, establishment of an efficient design process, and stabilization of the environment are required. A method is suggested to construct design environment by systematizing the contents of the projects and consulting experiences carried out for various categories of business such as electronic devices, motorcycl...
Journal of the Korean Society of Manufacturing Process Engineers, 2019
Recently, lightweight materials such as Ti alloys have been used increasingly in the aerospace an... more Recently, lightweight materials such as Ti alloys have been used increasingly in the aerospace and high-tech industries for weight loss and fuel efficiency. Because of built-up edges and workpiece deflection due to low stiffness, the Ti alloys have poor machinability. In our study, systematic experiments were conducted to investigate the milling characteristics of the Ti alloy (Ti-6A1-4V) with endmills. The independent variables in the experiment were spindle speed, feed per tooth, and axial depth. Cutting force, acceleration RMS, and surface roughness were measured. Using the response surface method, the optimal cutting conditions were analyzed to improve machining quality and productivity.
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