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토글 조인트장치를 이용한 가변예압장치 개발을 위한 기초 연구
최치혁(Chi Hyuk Choi),차나현(Na Hyeon Cha),이춘만(Choon Man Lee) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.3
To increase the machine accuracy by improving the stiffness of spindle bearings, preload was applied to the spindle bearings. The methods of fixed position preload, convertible preload, constant pressure preload, and variable preload are used to apply the preload to the spindle bearing. The previous studies performed by the author of this study were variable preload methods using rubber pressure and centrifugal force based on mechanical systems. This study proposed a toggle joint mechanism that could be applied to variable preload method using centrifugal force and rubber pressure to increase the preload. Also, a finite element analysis was conducted to predict the deformation of the rubber and change of the preload. And the analysis results showed that the preload by the device using rubber pressure only was increased by the toggle joint mechanism using rubber pressure.
최치혁(Chi-Hyuk Choi),이춘만(Choon-Man Lee) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.3
In the recent field of 5-axis machine tools, it is necessary to improve machining ability. The tilting index table is a key unit in order to manufacture some non-rotational and 3-dimensional parts by using conventional machining centers. In this study, the structural analysis of a tilting index table is carried out and the displacement and distribution of stress in the tilting index table is analysed to design the table safely. The modal analysis is performed in order to confirm the frequency response about the vibration having a large effect on the machine tools. The dynamic analysis is performed in order to confirm the rigidity, and the structural stability has been verified.
최치혁(Chi-Hyuk Choi),김동현(Dong-Hyeon Kim),이춘만(Choon-Man Lee) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.6
In recently, it is demanded development of manufacturing techniques for machining of various mechanical parts. Therefore the development of turning is one of the important manufacturing techniques. In this study, an experimental shape in tapered groove turning was suggested, and the turning process was investigated by analyzing cutting speed, feed rate, tapered angle, depth of cut. The surface roughness and cutting force change in the workpiece was measured. From the results, the optimum machining conditions are obtained by design of experiments.
최치혁(Chi Hyuk Choi),김동현(Dong Hyeon Kim),이춘만(Choon Man Lee) Korean Society for Precision Engineering 2011 한국정밀공학회지 Vol.28 No.4
Recently there has been increase in need for high precision and high speed machining due to economic and environmental reasons. It is a very important issue that determines the optimal preload that is to be applied to bearings in order to satisfy the performance required in bearings according to its operation conditions. This study introduces a variable preload device that can automatically adjust the preload applied in a machine tool spindle using centrifugal force as opposed in existing rubber instrument. In this study, the deformation of the rubber device by the centrifugal force is analyzed and it is discussed that the proposed device can be worked properly through changes of the collar density.
고속스핀들의 고무압을 이용한 가변예압장치 실용화를 위한 기초연구
최치혁(Chi Hyuk Choi),심민섭(Min Seop Sim),이춘만(Choon Man Lee) Korean Society for Precision Engineering 2014 한국정밀공학회지 Vol.31 No.8
One of the most important element technologies for achieving high-precision in machine tool spindle systems is preload technology for the bearing of spindle systems. Fixed position preload, constant pressure preload, conversion preload and variable preload methods have been applied for the spindle systems. In this study, a new variable preload method using centrifugal force and rubber pressure is used for reducing installation costs through simplifying its structure. The main objective of the work is the verification of the operability in a preload device using the rubber pressure by the finite element analysis. It is shown that the variable preload device proposed in this study is applicable to high speed machine tool spindles.
크랭크 샤프트 연삭기용 유정압 스핀들의 유막 간격 선정에 관한 연구
박동근(Dong Keun Park),최치혁(Chi Hyuk Choi),이인재(In Jae Lee),이춘만(Choon Man Lee) Korean Society for Precision Engineering 2011 한국정밀공학회지 Vol.28 No.4
A cylindrical type of self?controlled restrictor is designed for hydrostatic bearing of crank shaft for a grinding wheel spindle. The effect of operation parameters, clearance between spindle and housing on bearing stiffness are analyzed to determine the optimum conditions of operation parameters. The lowest values of the supply pressure and the loads by the theoretical and experimental results assuming oil film thickness and shape of pocket are compared.
공작기계용 힌지벨트형 칩컨베이어 핀헤드 성형공정 개발에 관한 연구
박동근(Dong Geun Park),최치혁(Chi Hyuk Choi),이춘만(Choon Man Lee) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.4
This paper presents an investigation into the pinhead forming process with the objective of finding the optimal forming conditions. In order to this, the orbital forming analysis of a heading M/C was carried out using the explicit finite element method. Relationships between temperature by forming of load and stresses, rake angle by forming final shape and stress distribution were investigated through analysises in order to find an efficient solution. As a result, the higher temperature and orbital rake angle were the better forming conditions.
박동근(Dong Keun Park),최준영(Jun Young Choi),최치혁(Chi Hyuk Choi),이춘만(Choon Man Lee) Korean Society for Precision Engineering 2012 한국정밀공학회지 Vol.29 No.5
Recently, a high speed spindle is an essential part of machine tools to satisfy latest demand of high precision product and machining of hard materials. But, there are many disadvantages such as heat generation of built-in-motor, bearing friction, noise, vibration and displacement because of the high speed. Many researches on spindle systems have been conducted for solving these problems. In this study, technical trend of machine tools spindle systems are analyzed with patent PSM, mapping and grouping. The analysis is carried out for the applied patent during January 2000 and December 2009 in Korea, Japan, EU and U.S.A. And development of the direction, strategy and promising technologies of the spindle system are suggested.