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사파이어 의료용 나이프의 연삭가공에서 지그의 탄성계수가 날 부 형상에 미치는 영향
신건휘(Gun-Hwi Shin),이득우(Deug-Woo Lee),곽태수(Tae-Soo Kwak) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.2
This study focuses on the effect of the elasticity modulus of jig material on blade edge shape in the grinding process of a sapphire medical knife. The ELID grinding process was applied as the edge-grinding method for sapphire material. Carbon steel and copper have been selected as the hard and soft jig materials, respectively. The blade edge created by ELID grinding was measured by a surface roughness tester and optical microscope. The shape of the ground edge and surface roughness were compared using the measurement results. As a result, it was found that chipping in the blade edge of the sapphire knife occurred more than in the case of jig material with a high-elasticity modulus because of the high normal force in the grinding process. Moreover, the maximum height surface roughness, Rmax,of the ground surface was higher in the case of the jig material with a high-elasticity modulus due to the difference in elasticelongation. It was considered to lead to chipping from the notch effect.
사파이어 의료용 나이프의 연삭가공에서 지그의 탄성계수가 날 부 형상에 미치는 영향
신건휘(Gun-Hwi Shin),강병욱(Byung-Ook Kang),곽태수(Tae-Soo Kwak) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.5
This study determines the selection of an appropriate jig material for the blade edge of the medical sapphire knife. The physical properties of the jig material affects the edge shape and chipping phenomenon in machining of the medical sapphire knife. If a grinding wheel is used, brittle workpieces such as sapphire are easily damaged by the propagation of cracks because the grinding force significantly increases. It is important to constantly maintain the grinding force in the grinding process of the brittle materials. The grinding force can be kept constantly by inducing the elastic deformation of the Jig material because the elastic deformation of brittle work-piece is negligibly low. The chipping phenomenon may be reduced by selecting the proper Jig material. Aluminum, copper, stainless steels and carbon steel were used as Jig materials. The experiment was conducted using a cast iron grinding wheel, which was installed on a conventional grinding machine with the ELID grinding system. The thickness and width of the chipping area were measured using an optical microscope and FE-SEM to analyze the shape of the blade edge. According to the experiment result, the chipping phenomenon decreased, and the sharp edge was formed when the jig materials with low elastic modulus were used.
신건휘(Gun-Hwi Shin),곽태수(Tae-Soo Kwak),정명원(Myung-Won Jung),곽인실(Ihn-Sil Kwak) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.6
This study focused on developing an electro-discharge truing method for the ELID grinding process using a metal-bonded grinding wheel. The truing process in grinding plays important roles in enhancing the quality of the ground surface. In this study, a reference current in the electro-discharge truing process was confirmed to be a viable solution for efficient truing through performance experiments. Current and voltage variation experiments were carried out and the variation output data were collected with a monitoring program to understand the electrodischarge phenomenon that occurs between metal-bonded grinding wheels and copper electrodes. The experimental results showed that as the reference current decreased, the average electro-discharge energy decreased. Therefore, the reference current can be used as an indicator to estimate the size of the gap between the truer and grinding wheel.
Development of Auto-Control Power Supply of ELID Electrolysis Speed for Metal-Bonded Grinding Wheel
신건휘(Gun-Hwi Shin),곽태수(Tae-Soo Kwak) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.11
ELID grinding is an excellent technique for the mirror grinding of the variety of the advanced metallic or nonmetallic materials. The focus of this study is the development of an automaticcontrol electrolysis-speed device for the automation of the ELID-grinding process. For the development of the automatic-control electrolysis-speed device, analysis experiments regarding the ELID cycle and oxide-layer removal and creation were conducted according to a truing and dressing process. Also, a comparative experiment was conducted to confirm the variance of the electrolysis speed in accordance with changes of the voltage. The experiment results for the developed automatic-control electrolysis-speed device show that the developed device could control the electrolysis speed according to voltage changes through the use of the data that are monitored during the ELID-grinding process.
강병욱(Byung-Ook Kang),신건휘(Gun-hwi Shin),곽태수(Tae-Soo Kwak) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.11
The purpose of this study is to examine and propose a high quality blade manufacturing method by applying ELID grinding technology to machining the tungsten carbide blade edge for MLCC sheet cutting. In this study, experiments are performed according to the abrasive type of grinding wheel, grinding method and grinding direction using the non-stop continuous dressing ELID grinding technology. By comparing and analyzing the chipping phenomena and surface roughness of both the blade grinding surface and the processed surface, a method for machining the tungsten carbide blade for cutting MLCC sheet is proposed. From the analysis of the surface roughness and chipping phenomena, it is confirmed that the use of diamond abrasive is advantageous for the blade machining. In addition, it succeeds in the machining of 6㎛ fine blade without any chipping, by using the grinding wheel #4000 with the diamond abrasive.
김태규(Tae-Kyu Kim),신건휘(Gun-Hwi Shin),정명원(Myung-Won Jung),곽태수(Tae-Soo Kwak) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.3
Truing process is a very important process for recovering the shape of wheels worn by continuous grinding operation. In this study, the devices, controller, and spindle for electro-discharge truing were developed, and the electro-discharge truing method was applied to metal-bonded grinding wheels and compared with the conventional truing method. The shapes of the grinding wheels were measured by a surface profile measurement device. The protrusion of abrasives on the surface of the wheels was compared with the conventional truing method using an optic microscope measurement device. The experimental results showed that the performance of the electro-discharge truing method, in terms of the protrusion of abrasives on the surface of the wheels and the recovery of the shape of the worn wheels, was similar to that of the conventional truing method.
Myung-Won Jung(정명원),Gun-hwi Shin(신건휘),Geon-Hee Kim(김건희),Hitoshi Ohmori(오오모리 히토시),Tae-Soo Kwak(곽태수) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.1
This study focused on the application of ELID mirror-surface grinding technology to the manufacture of off-axis asymmetric large-area reflecting mirrors made of BK7 glass. The size of the parts, such as asymmetric large-area mirrors or lens, made form-accuracy or roughness especially hard to measure after machining because of the measuring range limit of measurement devices. In this study, the ELID grinding system has been set up for mirror-surface machining experiments manufacturing off-axis asymmetric lenses. A measuring method using a reference workpiece has been suggested to measure the form-accuracy and roughness. According to the experimental results, even when using only a reference workpiece, it is confirmed that the surface roughness was 8 nmRa and form-accuracy was 80 nmRMS, with a best fit asymmetric radius when using a grinding wheel of #8,000. It is found that the accuracy of large-area parts could be estimated by the proposed process.