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이경훈(K.H. Lee),고대철(D.C. Go),김상주(S.J. Kim),김병민(B.M. Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
This paper presents a study on micro forming technologies for micro-electro-mechanical systems(MEMS) parts such as micro gears below 450㎛ in diameter and 38 in module. For this purpose, it is important to develop new methods to fabricate micro gears and choose suitable materials for micro forming. Generally micro gears made by MEMS process butin this study micro gears made by extrusion process using micro dies. Photochemically machinable glass has been used to fabricate micro dies by photo-lithography and anisotropic etching techniques. A new forward extrusion machine has been developed for this study. LLDPE(Linear Low Density Polyethylene) and EVA(Ethylene Vinyl Acetate) have been used in micro extrusion. Specimens were placed in a container and extruded by a piezoelectric actuator. Micro extrusion has succeeded in forming micro-gear shafts.
이경훈(K. H. Lee),성낙문(N. M. Sung),이태순(T. S. Lee),김병민(B.M. Kim) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
The aim of this paper is to develop a feasible forming condition under which the radial-axial ring rolling (RARR) process can be established successfully and then leads to diminished fishtail defects. The mathematical model for the RARR process is developed based on the constant volume condition of ring blanks and the constant growth velocity condition (CGVC) of a ring outer diameter. The feasible forming condition is determined by the reasonable rage of extreme growth velocities. For a verification of the feasible forming condition for RARR process, experiments are carried out.
이경훈(K. H. Lee),김병민(B. M. Kim) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.10
In ultrasonic vibration drawing, the drawing forces can be reduced by applying ultrasonically oscillating dies. Ultrasonic vibration drawing has been considered as a means of accommodating high-level drawing processes such as shaped wire, ultrafine wire, and the wire drawing operation in semidry or dry condition. Prior studies were attempted to analyze the mechanism of improved drawing performances, such as reduced drawing force and improved lubrication characteristic. However, researches on design rule for ultrasonic vibration drawing system are not yet carried out. The principal objectives of this work are to design a set of tooling capable to superimpose the oscillations and to observe by experiments the influence of the ultrasonic oscillations on the wire drawing.