• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.743-747
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• 1997

Polishing work for a curved surface die demands simple and repetitive operations and requires much time while it also demands high precision. Therefore it is operated by skilled worker in handiwork. Howener workers avoid polishing work gradually because of the poor environments such as dust and noise. In order to reduce the polishing time and to alleviate the problem of shortage of skilled workers, researches for automation of polishing have been pursued in the developed countries. In the research, a polishing robot with 2 degrees of freedom motion attached to machining center with 3 degrees of freedom and pneumatic system forms an automatic polishing system which keeps the polishing tool vertically on the surface of die and maintains constant pneumatic pressure. A synchronization between machining center and polishing robot is accomplished by using M code of machining center. A rulled surface and shadow mask are polished by the developed polishing robot.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.326-333
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• 2004

This paper presents the structural characteristics analysis of a high-speed horizontal machining center with spindle speed of 50, 000rpm and feedrate of 120m/min. The spindle system is designed based on the built-in motor, angular contact ceramic ball bearings, oil-air lubrication and oil-jacket cooling method. The X-axis and Y-axis feeding systems are composed of the linear motor and linear motion guides, and the Z-axis feeding system is composed of the servo-motor, ball screw and linear motion guide. The structural analysis model of the high-speed horizontal machining center is constructed by the finite element method, and the validity of structural design is estimated based on the structural deformation of the high-speed horizontal machining center and spindle nose caused by the gravity and inertia forces.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.75-81
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• 2000

This study for the roundness and perpendicularity of machining center is classified into two ways. One is the way that progresses the roundness amending the parameter of machining center based on the measured value after the measurement of the roundness of machaning center by means of a existing measuring device, another is the way that measures the roundness by remodeling the existing measuring device. the former is studied by pack hei jae team in Seoul university, the later is studied by TSUTSUMI. Especially TSUTSUMI measures the roundness according to circular compensation after the insertion of developed measuring device using a rotary encoder to the spindle of machining tool. we study how regulation velocity occuring with circular motion of machining center table influences the roundness after measuring the roundness using Circular Test method by a 2 dimention probe and a standard discus in this experiment.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.119-124
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• 2010

In this paper, thermal stabilization design of a new concept compact machining center has been investigated. A new concept machining center adopted a new X-axis as a NC rotary table. A New concept compact machining center is designed that spindle speed, feed rate and NC Rotary table speed are 12,000rpm, 60m/min and 110rpm each. The analysis is carried out by using FEM simulation Solidworks, CATIA and ANSYS. This paper is focused on the thermal deformation according to temperature distribution of a spindle system and feed drive system. Heat transfer analysis is performed according to heat source and atmosphere contact parts. As a result, this compact machining center is designed as a thermally stable structure.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.75-80
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• 2019

One of the most critical aspects of the smartphone industry is the quality of the cover. And the vibrations of machining center are supposed to be the most dominant factors to damage the cover quality. In this study, structure of a machining center has been analyzed through experiments and computer simulations to figure out the main reasons of the vibrations. And the design alterations based on the analysis were applied to identify the effects of those alterations on the vibration suppression. The result shows that the design alterations can effectively suppress about 90% of the vibrations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.49-54
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• 2010

An integrated machining center is developed for high precision and productivity manufacturing. The developed machine is composed of the high precision spindle using ball bearings, the high stiffness bed and the three axis CNC controller with the high resolution AC servo motor. In this paper, structural and modal analysis for the developed machine are carried out to check the design criteria of machine. The analysis is carried out by FEM simulation with using the commercial software, CATIA V5, ANSYS and ARMD. The simulation model of machine is made by shell and solid finite elements. This study also presents the measurement system on the modal analysis of an integrated machining center. The weak part of the machine is found by the analytical evaluation. The results provide with the structural modification data for good dynamic behaviors. And the safety of machine is confirmed by the modal analysis of modified machine design. As this study results can be trustworthy with the analysis of ANSYS and CATIA, integrated machining center can be successfully developed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.698-701
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• 2005

We have investigated experimentally a nano patterning using electron beam lithography for the nickel stamper fabrication. Recently, DVD and Blu-ray disk(BD) have nano-scale patterns in order to increase the storage density. Specially, BD has 100nm-scale patterns which are generally fabricated by electron beam lithography. In this paper, we found optimum condition of electron-beam lithography for 100nm-scale patterning. We controlled various conditions of EHP(acceleration voltage), beam current, dose and aperture size in order to obtain optimum conditions. We used 100nm-thick PMMA layer on a silicon wafer as photoresist. We found that EHP was the most dominant factor in electron-beam lithography.

• Journal of Powder Materials
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• v.20 no.4
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• pp.297-301
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• 2013

Mirror surface machining for large area flattening in the display field has a problem such as a tool wear and a increase in machining time due to large area machining. It should be studied to decrease machining time and tool wear. In this paper, multi-tool machining method using a PCD tool and a SCD tool was applied in order to decrease machining time and tool wear. Machining characteristics (cutting force, machined surface and surface roughness) of PCD tool and SCD tool were evaluated in order to apply PCD tool to flattening machining. Based on basic experiments, the PCD/SCD multi-tool method and the SCD single-tool method were compared through surface roughness and machining time for appllying large area mold machining.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.900-904
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• 1997

A problem in the grinding process using the machining center(MC) with a small diametric wheel is the machining error due to due to decrease of quill diameter. In this paper, a side-cut grinding is performed with a vitrified bonded CBN wheel by the MC, and the relation between grinding force and machining error for grinding conditions is investigated experimentally. It is show that the normal force has a significant effect on the machining error.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.889-897
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• 1986

The purpose of this study is to describe the strategy of machining process suitable for developing adaptive control with constraint of NC-machine tool. The algorithm that controls machining process parameters of every sampling time is established for the constraint of torque in machinig center. To prove this AC algorithm, manual AC-unit control test is used for simulating the on-line AC strategy control. Also machining tests are carried out on a CNC-machining center fitted with the ACC system and compared with the simulated results. The practical effectiveness of the ACC systems so discussed and the reduction of machining time are demonstrated with reference to typical models of cutting workpieces. As a typical model, taper and step geometry model are selected. The computer simulation results have a good agreement with the experimental observation and make it possible to develope a NC-machine tool with an on-line ACC system.