• 한국정밀공학회지
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• 제26권2호
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• pp.35-44
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• 2009

Long stroke Fast Tool Servo (LFTS) with maximum stroke of $432{\mu}m$ is designed, manufactured and tested for fabrication of optical free-form surfaces. The large amount of stroke in LFTS has been realized by utilizing the hinge and lever mechanisms which enable the displacement amplification ratio of 4.3. In this mechanism the peculiar shape was devised for maximizing the displacement of end tip in LFTS and special mechanical spring has been mounted to provide the sufficient preload to the piezoelectric actuator. Also, its longitudinal motion of tool tip can be measured by capacitive type displacement sensor and closed-loop controlled to overcome the nonlinear hysteresis. In order to verify the static and dynamic characteristics of designed LFTS, several features including step response, frequency response and cut-off frequency in closed-loop mode were experimentally examined. Also, basic machining result shows that the proposed LFTS is capable of generating the optical free-form surface as an additional axis in diamond turning machine.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.90-95
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• 2005

To perform the finish outside-diameter grinding process of ferrules which are widely used as fiber optic connectors, a high-precision centerless grinding machine is necessary. In this study, the thermal characteristics of the high-precision centerless grinding machine such as the temperature distribution, temperature rise and thermal deformation, are estimated based on the virtual prototype of the grinding machine and the heat generation rates of heat sources related to the machine operation conditions. The reliability of the predicted results is demonstrated by the temperature characteristics measured from the physical prototype. Especially, the predicted and measured results show the fact that the high-precision centerless grinding machine consisted of the hydrostatic GW and RW spindle systems, hydrostatic RW feeding mechanism, RW swivel mechanism, on-machine GW and RW dressers, and concrete-filled steel bed, has very stable thermal characteristics.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.348-352
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• 2002

a basis such as IT(Information Technology), NT(Nano Technology) and BT(Bio Technology). Recently, NT is applied to various fields that are composed of science, industry, media and semiconductor-micro technology. It has need of IT that is ultra-precision positioning technology with strokes of many hundreds mm and maintenance of nm precision in fields of ultra micro process, ultra precision measurement, photo communication part and photo magnetic memory. This thesis represents optimal design on ultra-precision positioning with single plane X-Y stage and development of artificial control system for adequacy of industrial demand. Also, dynamic simulation on global stage is performed by using ADAMS (Automated Dynamic Analysis of Mechanical System) for the purpose of grasping dynamic characteristic on user designed X-Y global stage. The error between displacements from micro stage and from FEM(Finite Element Method) is 3.53% by verifications of stability on micro stage and control performance. As maximum Von-mises stress on hinge of micro stage is 5.981kg/mm$^2$ that is 1.5% of yield stress, stability on hinge is secured. Preparing previous results, optimal design of micro stage can be possible, and reliance of results with FEM can be secured.

• 한국정밀공학회지
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• 제17권12호
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• pp.68-75
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• 2000

This paper presents the construction of an ultra-precision machining system and machining experiments using the developed system. The system is composed of air bearing system, granite bed, air pad, and linear feeding mechanism. The cutting conditions have great effect on the surface quality in ultra-precision machining. the ultra-precision machining is mainly processed by several ${\mu}{\textrm}{m}$ depth of cut and feed rate. For this, tools with sharper cutting edge and less tool wear are needed. To satisfy these requirement, diamond is generally used as a tool material for ultra-precision machining. In order to evaluate the cutting characteristics of the PCD and MCD tools on the aluminum alloy, the machining experiments performed using the developed system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.466-469
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• 1995

This paper presents a design and performance of the 6 D.O.F linear motion table with a magnetic bearing suspension. The linear positioning of the table with a 150mm stroke is driven by a brushless DC Linear motor and the other attitudes of the stage are controlled by the analog PD controller with magnetic bearing actuators. Each magnetic bearing unit which consists of 3 electromagnets, 3 capacitance probes and 3 backup bearings affords controlled forces by detecting the air gap between the probes and guideways. An integral type capacitance probe amplifier is equipped on the upper plate of the table so that the probe line to the probe amplifier can be shorter therefore the problems due to the stray capacitance and noise can be reduced. Form the pitch-yaw errormeasured by the autocollimator, the vertical and horizont straightness errors of the table are derived that they are maintained below 1.mu. m over 100mm stroke. The positioning accuracy of the linear motion is maintained below 2 .mu. m and the repeatability error is below 1 .mu. m

• 한국정밀공학회지
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• 제32권3호
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• pp.263-268
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• 2015

This paper describes lost motion analysis for a novel 6-DOF ultra-precision positioning stage. In the case of flexure hinge based precision positioning stage, lost motion is generated when the displacement of actuator is not delivered completely to the end-effector because of the elasticity of flexure hinge. Consequently, it is need to compute amount of lost motion to compensate the motion or to decide appropriate control method for precision positioning. Lost motion analysis for the vertical actuation unit is presented. The analysis results are presented in two ways: analytic and numerical analyses. It is found that they closely coincide with each other by 1% error. In finite element analysis result, the amount of lost motion is turned out to be about 3%. Although, the amount is not so large, it is necessary procedure to check the lost motion to establish the control method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.485-486
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• 2006

This paper represents a ultra precision rotational device where the smooth impact drive mechanism(SIDM) is utilized as a driving mechanism. Linear motions of piezoelectric elements are converted to the rotational motion of disk by frictional forces generated between the rotational disk and the friction bars which are attached to the piezoelectric elements. This device was designed to drive a rotational disk using slip-slip motion mechanism based on stick-slip motion mechanism. Experimental results show that the angular velocity was increased in proportion to the magnitude of supplied voltage to piezoelectric element. In our device, the smooth rotational motion was obtained when the driving frequency has been reached to 500Hz under the driving voltage of 100V. The amount of step movement has been revealed to be $3.44{\times}10^{-4}$ radian.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.131-132
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• 2006

This paper presents a micro-positioning platform based on the unique parallel mechanism recently developed by the authors. The platform has a meso-scale rectangular shape whose size is $20{\times}23m$. The stroke is 5 mm for both the x- and y-axis and 100 degrees for the ${\alpha}$-axis(the rotational axis along the x-axis). The platform is actuated by the three sets of two-stage linear actuators: a linear motor for rough positioning and a piezo actuator for fine positioning. The platform is already assembled. Experimental results of the positioning measurements and control performance are presented.

• 한국정밀공학회지
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• 제16권10호
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• pp.11-16
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• 1999

In this study, Ultra-precision finishing system using micro abrasive film experimented using experimental variable film feed speed and grinding speed and structural steel(SM45C) with respect to 12~3{\mu}m$ micro abrasive film. the result are follows; (1) Experimental condition must setup dissimilar about each micro abrasive film. (2) To measurement deviation the smallest machined condition are 20mm/min in 12{\mu}m$, 5mm/min and 15mm/min in 9{\mu}m$ and 5{\mu}m$, 5mm/min in 3{\mu}m$ in film feed speed. (3) To measurement deviation the smallest machined condition are 180m/min in 12{\mu}m$, 84m/min in 9{\mu}m$, 56 and 84m/min in 5{\mu}m$, 104m/min in 3{\mu}m$ in grinding speed.

• 한국정밀공학회지
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• 제25권7호
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• pp.47-54
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• 2008

Recently, application of ceramics has increased gradually due to excellent mechanical properties. Si3n4-BN ceramic which is one of ceramics is very hard and has superior resistance against volatile temperature and wear. However, extremely high hardness of the $Si_3N_4-BN$ ceramic makes conventional machining very difficult. Therefore, the use of machinable ceramic has been in a poor because of difficult industrial processes in spite of many advantages. And so new technology being called IED(In-process electrolytic dressing) was introduced to solve this problem. The aim of this study is to determine the machining characteristics in terms of pressurized weight to the workpiece and the influence with h-BN content using IED lapping system. Also, Acoustic Emission (AE) is used for the monitoring of surface characteristics.