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Development of a one-axis manipulator for laser-assisted machining

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Journal of Central South University 2013年第2期20卷 378-384页

作者： KIM Dong-hyeon lee choon-man Department of Mechanical Design & manufacturing Engineering Changwon National University

Laser-assisted machining has been considered as a new alternative machining method of difficult-to-cut materials. A laser module with one-axis manipulator is developed to focus on preheating laser beam effectively. First of all, the thermal characteristic analysis was performed to verify the importance of laser module location. Laser module should be moved within 1 mm. Analysis conditions of three positions in driving range of the one-axis manipulator are selected. And a C coupling is used as a connection device for spindle and laser module. An initial model has one C coupling, and the number of C coupling has been increased from 1 to 2 in an improved model. And the analysis is carried out again for the one-axis manipulator. The results of the static analysis, the maximum displacement and the maximum stress are decreased by 22% and 11%, respectively, for the improved model when the laser module is located at farthest away from the spindle unit. As a result of the modal analysis, the first natural frequency mode is increased by 13%, 18% and 12% at these positions of the improved model, respectively. The harmonic analysis of the improved model was performed by analyzing the results of the modal analysis. The maximum deformation was 0.33 mm in driving unit at 222 Hz. And the maximum compliance of the ISO axis direction was 0.23 mm/N. Finally, the one-axis manipulator has been fabricated successfully using the analysis result.

关键词： finite element analysis (FEA) laser-assisted machining manipulator

Development of two-axis control index table driven by direct drive motors

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Journal of Central South University 2011年第6期18卷 1962-1968页

作者： KIM Jae-hyun lee choon-man School of Mechatronics Changwon National University

The stability and reliability of a tilting index table should be considered at the design stage. A design method for the lightweight and improvement of the stability of the structure in a tilting index table was proposed using a commercial analysis program, ANSYS Workbench 12, by analyzing the static-thermal characteristics of the developed high-accuracy tilting index table at its design stage. The results of the performed structural analysis show that the maximum stress is generated at the stock tail part. An optimum design for the stock tail part was carried out to reduce the maximum stress and deformation. Also, the design variables were determined by considering the support of the stock tail part for the C-axis body. In the comparison of the results before and after the optimization, the maximum deformation and stress are improved by 2.8% and 8%, respectively.

关键词： tilting index table structural analysis modal analysis thermal analysis optimum design

Multi-stage optimum design of magazine type automatic tool changer arm

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Journal of Central South University 2012年第1期19卷 174-178页

作者： KIM Jae-Hyun lee choon-man School of Mechatronics Changwon National UniversityChangwon 641-773Korea

To enhance machining efficiency,tool change time has to be ***,for an automatic tool changer attached to a machining center,the tool change time is to be *** the automatic tool changer is a main part of the machining center as a driving *** static attributes of the automatic tool changer using the commercial code,ANSYS Workbench V12,were tried to *** the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum *** shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable *** is possible to obtain an optimized model in which the maximum deformation,maximum stress,and mass are reduced by 10.46%,12.89% and 9.26%,respectively,compared with those of the initial ***,the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.

关键词： automatic tool changer optimum design structural analysis exchange arm

Effects of automatic variable preload device on performance of spindle

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Journal of Central South University 2012年第1期19卷 150-154页

作者： KIM Dong-Hyeon lee choon-man Department of Mechanical Design and manufacturing Engineering Changwon National UniversityChangwon 641-773Korea

To increase the machine accuracy by improving the stiffness of bearings,a preload was applied to bearings.A variable preload technology was necessary to perform machining processes in both low and high speed *** automatic variable preload device was fabricated using an eccentric *** installing the fabricated device on a spindle,the effect of the automatic variable preload device on the performance of the spindle was *** the results of the vibration measurement of the spindle,the vibration is increased by 20%-37% according to measurement points at the maximum rotation speed of 5 000 r/***,in the results of the noise measurement of the spindle,the spindle rotation speed is increased by about 1.9% and 1.5% at the front and side of the spindle,*** on the results of this analysis,an improved method that reduces such effects on the performance of the spindle is proposed.

关键词： machine tool spindle automatic variable preload device vibration noise

Lightweight design of 45000r/min spindle using full factorial design and extreme vertices design methods

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Journal of Central South University 2011年第1期18卷 153-158页

作者： PARK Seong-jin lee choon-man HWANG Young-kug Department of Mechanical Design and manufacturing Engineering Changwon National University

Factors for determining the spindle size are the shaft diameter, positions of bearing and motor, and entire length of the spindle. Then, it is important to find the assembling of the optimal design variables, which satisfy the stiffimss and rotational speed required to the spindle. A general full factorial design method was used to verify some factors that affect the natural frequency of a spindle. It is verified that the shorter shaft length and bearing span length represent the higher natural frequency, and there are some effects according to the change in the levels of factors. The detailed spindle dimension is determined by applying an EVD method, which can define the optimal bearing position through considering the limiting condition. Based on the estimated regression model, the optimal spindle size and bearing distance that can improve the primary natural frequency are obtained, and the influence of design factors on the natural frequency is also analyzed.

关键词： high-speed spindle extreme vertices design natural frequency lightweight design full factorial design

Development of CAD/CAM system and profile measuring device for CNC grinding machine to obtain an optimal grinding speed

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Journal of Central South University 2011年第1期18卷 146-152页

作者： LIM Sang-Heon KIM Jae-Hyun lee choon-man Agency of Promoting Technology Innovation Gyeongnam TechnoparkChangwon 641-465Korea School of Mechatronics Changwon National University

Cam mechanics is one of the most popular devices for generating irregular motions and is widely used in automatic equipment,such as textile machines,internal combustion engines,and other automatic *** order to obtain a positive motion from the follower using a rotating cam,its shape should be correctly designed and *** development of an adequate CAD/CAM system for a cam profile CNC grinding machine is necessary to manufacture high-precision *** purpose of this study is the development of a CAD/CAM system and profile measuring device for a CNC grinding machine to obtain an optimal grinding speed with a constant surface *** types of disk cams were manufactured using the proposed algorithm and procedures to verify effectiveness of the developed CAD/CAM system.

关键词： cam CAD/CAM system CNC grinding machine optimal grinding speed

Prediction of preheating conditions for inclined laser assisted machining

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Journal of Central South University 2012年第11期19卷 3079-3083页

作者： KIM Kwang-sun lee choon-man School of Mechatronics Changwon National UniversityChangwon 641-773Korea

For laser assisted machining,shape of preheating laser heat source is changed irregularly because of complexity of material ***,the preheating temperature should be controlled by adjusting the feed rate or the laser *** analyses of the laser assisted machining process for inclination planes were *** analyzing the obtained temperature profile,a proper feed rate control method was proposed according to the inclination *** addition,the temperature distribution of the cross section after feed rate control was *** correlation equation between inclination angles and adjusted proper feed rate was *** results of this analysis can be used to predict the preheating effect on workpiece and can be applied as a preheating temperature control method in laser assisted machining processes.

关键词： laser assisted machining inclination angle feed rate control cross section

NC code generation for laser assisted turn-mill of various type of clovers and square section members

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Journal of Central South University 2012年第11期19卷 3064-3068页

作者： CHOI Jun-young lee choon-man Department of Mechanical Design & manufacturing Engineering Changwon National UniversityChangwon 641-773Korea

Laser assisted turning （LAT） is one of the advanced machining technologies, which uses laser power to heat the surface of a workpiece before the material is removed. It has several advantages of low manufacturing costs, high productivity and high qualities to machine difficult-to-cut materials such as silicon nitride, muUite, zirconia and Ni. A large part of studies on LAT have been focused on a round bar. With increasing demands for high quality products and high performance engineering system, the researches on LAT for clover and square section members are necessary. But, these workpieces are impossible to be machined on conventional CNC lathe and to generate NC code with current CAM softwares. As a basic research for combining LAT with a tilting index table type 5-axis machining center, i.e. laser assisted turn-mill, a new method is suggested to generate NC code that can process various types of clover and square section members through development of C＋＋ program.

关键词： laser assisted turning (LAT) NC code clover section turn-mill square section turn-mill

Estimation of deformed laser heat sources and thermal analysis on laser assisted turning of square member

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Journal of Central South University 2012年第2期19卷 402-407页

作者： KIM Jae-hyun KIM Kwang-sun CHOI Jun-young lee choon-man Department of Mechanical Design and manufacturing Engineering Changwon National University

Laser assisted machining （LAM） has difficulties in estimating temperature after applying a LAM process due to its very small heat input area, large energy and movement. In particular, in the case of laser assisted turning （LAT） process, it is more difficult to estimate the temperature after preheating because it has a shape of ellipse when a laser heat source is rotated. A prediction method and thermal analysis method for heat source shapes were proposed as a square shaped member was preheated. The temperature distribution was calculated according to the rotation of the member. Compared with the results of the former study, the maximum temperature of the calculation results, 1 407.1 ℃, is 8.5 ℃ higher than that of the square member, which is 1 398.6 ℃. In a LAT process for a square member, the maximum temperature is 1 850.8 ℃. It is recognized that a laser power control process is required because square members show a maximum temperature that exceeds a melting temperature at around a vertex of the member according to the rotation.

关键词： laser assisted machining laser assisted turning laser preheating laser power control