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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.
소형 헬리컬 기어 압출 시 Zn-22wt%Al 합금 분말의 강화방법에 따른 미세 조직 변화에 관한 연구
이경훈(K.H. Lee),이정민(J.M. Lee),고대철(D.C. Ko),김병민(B.M. Kim) 한국소성가공학회 2011 압출 및 인발 심포지엄 Vol.2011 No.8
The extrusion with different powder consolidation methods, which is based on the superplastic behavior of the Zn-22wt%Al alloy powder, is proposed to observe the microstructure of helical gears and extrudability. The specifications of the helical gears were as follows: m, 0.3; Z, 12; Dp, 3.727mm; and β, 15˚. Compacted powders were consolidated by solution treatment, dwelling & quenching and sintering. The consolidated billets consisted of equiaxed fine grained structure, lamellar structure and mixed phase. Extrusion experiments were carried out under the following conditions: temperature, 250˚C and extrusion velocity, 0.1mm/min. The mechanical properties of extruded helical gears were investigated by measurement of Vickers hardness, extrusion load and SEM observation.
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.