• Title/Summary/Keyword: Micro-shaft

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Micro-shaft and Micro-hole Machining for Micro Punching (마이크로 펀칭용 미세축, 미세구멍의 가공)

  • Ryu S. H.;Cho P. J.;Lee K. H.;Chu C. N.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2002.02a
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    • pp.239-244
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    • 2002
  • In this study, we developed the manufacturing technology of micro-hole and micro-shaft for micro punching system using micro electrical discharge machining and micro electro chemical machining. Micro punching dies of tungsten carbide with $55\;{\mu}m\;and\;110\;{\mu}m$ diameter and $250\;{\mu}m$ depth were made by micro electrical discharge machining. The form accuracy and surface roughness of die hole were pretty good and it was shown that the punched hole quality was fine. WC micro-shaft with $30\;{\mu}m$ diameter was made by the multistep micro electro chemical machining. The developed technologies can be effectively used in precision manufacturing of micro punching die and mass production of micro-shaft.

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Contact Stress Analysis of Shrink-fitted Specimen considering Micro-slip (미소슬립을 고려한 압입 시편의 접촉응력 해석)

  • Lee Dong-hyong;Goo Byeong-choon;Lee Chan-woo;Jung Heung-che
    • Proceedings of the KSR Conference
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    • 2004.06a
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    • pp.632-637
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    • 2004
  • In the shrink or press fitted shaft such as railway axle, fretting can occur by cyclic stress and micro-slippage due to local movement between the shaft and the hub. When the fretting occurs in the press fitted shaft, the fatigue strength remarkably decreases compared with that of without fretting. In this paper, the analysis of contact stresses in a press fitted shaft in contact with a hub was conducted by finite element method and the micro-slip according to the bending load was analyzed. It is found that the largest stress concentration and maximum slip amplitude of shrink fitted shaft are found at the edge of the interface and the distribution of contact stresses at the contact edge has largely influenced and coefficient of friction.

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Development of Micro Tool using High Speed Etching Process (고속 회전에칭을 이용한 미세공구의 개발)

  • 김성헌;박준민;정해도
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.959-962
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    • 2000
  • In this study, the micro shaft was fabricated by high speed etching process. The integration of the kinetic energy of circumference and the effect of etching takes less time to fabricate the micro shaft than any other conventional methods. First, the end part of the rod(SKD11) was dipped in chemical solution(FeCl$_3$) and the rod rotated at high speed(3500-10000rpm). Experimental setup was simply composed of high speed motor. chemical solution and $\Phi$ 1 mm rod. The main factors of diameter control are chemical concentration, reaction time and rpm. has a result. the diameter of the dipped rod was decreased by 200${\mu}{\textrm}{m}$ by high speed rotation and its shape and surface was good. From this experiment, we found the possibility to manufacture micro shaft without very expensive equipment.

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WC Micro-shaft Fabrication Using Electrochemical Etching (전해 가공을 이용한 WC 미세축 제작)

  • 최세환;류시형;최덕기;주종남
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.6
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    • pp.172-178
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    • 2004
  • Tungsten carbide microshaft can be used as various micro-tools for MEMS because it has high hardness and high rigidity. In this study, experiments are performed to produce tungsten carbide micro-shaft using electrochemical etching. H$_2$SO$_4$ solution is used as electrolyte because it can dissolve tungsten and cobalt simultaneously. Optimal electrolyte concentration and machining voltage satisfying uniform shape, good surface quality, and high MRR of workpiece are experimentally found. By controlling the various machining parameters, a straight micro-shaft with 5 ${\mu}{\textrm}{m}$ diameter, 3 mm length, and 0.2$^{\circ}$taper angle was obtained.

Performance Characteristics for Off-design Operation of Micro Gas Turbines (마이크로 가스터빈의 탈설계 운전 성능특성)

  • Kim, T.S.;Hwang, S.H.
    • The KSFM Journal of Fluid Machinery
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    • v.7 no.3 s.24
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    • pp.39-47
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    • 2004
  • Micro gas turbines are designed with low turbine inlet temperature and pressure ratio. To overcome the efficiency defect of the simple cycle, adoption of the recuperator is an inevitable choice. In addition to the design performance, we should also pay attention to the off-design performance of gas turbines since they usually operate at part-load conditions lot a considerable amount of their lifetime. This study analyzes off-design performance characteristics of micro gas turbines and addresses the importance of the recuperation process doting the part load operation. Comparative analyses have been performed to evaluate the part load performance differences among various design and operating options : simple vs recuperative cycles, single vs two shaft configurations, various operating strategies for the single shaft configuration, and current vs advanced engines. Major finding is that maintaining high turbine exhaust temperature is crucial for efficient operation of micro gas turbines.

Performance Characteristics for Off-design Operation of Micro Gas Turbines (마이크로 가스터빈의 탈설계 운전 성능특성)

  • Hwang, S.H.;Kim, T.S.
    • 유체기계공업학회:학술대회논문집
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    • 2003.12a
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    • pp.80-87
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    • 2003
  • Micro gas turbines are designed with low turbine inlet temperature and pressure ratio. To overcome the efficiency defect of the simple cycle, adoption of the recuperator is an inevitable choice. In addition to the design performance, we should also pay attention to the off-design performance of gas turbines since they usually operate at part-load conditions for a considerable amount of the time. This study aims at analyzing off-design performance characteristics of micro gas turbines and addressing the importance of the recuperator in the part load operation. Comparative analyses have been performed to evaluate the part load performance differences among various design and operating options : simple vs recuperative cycles, single vs two shaft configurations, various operating strategies for the single shaft configuration (fuel only control, variable speed operation, variable inlet guide vane control), and current vs advanced engines. Major finding is that maintaining turbine at high level is crucial in efficient operation of micro gas turbines.

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Review of Micro Electro-Chemical Machining (미세 전해가공 기술 동향)

  • Shin, HongShik
    • Journal of Institute of Convergence Technology
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    • v.2 no.2
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    • pp.25-29
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    • 2012
  • Micro machining technologies have been required to satisfy various conditions in a high-technology industry. Micro electrochemical process is one of the most precision machining methods. Micro electrochemical process has been divided into electrochemical etching through protective layer and electrochemical machining using ultrashort voltage pulses. Micro shaft can be fabricated by electrochemical etching. The various protective layers such as photo-resist, oxide layer and oxidized recast layer have been used to protect metal surface during electrochemical etching. Micro patterning on metal surface can be machined by electrochemical etching through protective layer. Micro hole, groove and structures can be easily machined by electrochemical machining using ultrashort voltage pulses. Recently, the groove with subnanometer was machined using AFM.

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Superplastic Microextrusion for Microgears (초소형 기어 제조를 위한 초소성 재료의 미세압출)

  • Kim, Jae-Yeon;Joo, Se-Min;Kim, Ho-Kyung
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.4
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    • pp.1-7
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    • 2008
  • Fine grained superplastic Zn-22%Al alloy was extruded using a laser machined micro-die to produce a micro-gear shaft. Extrusion process was conducted under a constant pressure at constant temperatures ranging from 503 to 563K. Laser machining was capable to machine a micro-die with close tolerances and adequate surface quality. The extrusion rate increased with extrusion load under constant extrusion temperature. The rate reached a steady state and became constant after a certain period. There was a small instantaneous stroke on application of the load and then a very brief primary stage which preceded steady-state flow. The micro-extrusion process was proven to produce a micro-gear shaft successfully using a fine grained superplastic Zn-22%Al alloy.

Experimental Study on the Dynamic Behaviour of Oil Seals (오일시일의 동적거동에 관한 실험적 연구)

  • 김청균;심우전
    • Tribology and Lubricants
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    • v.11 no.3
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    • pp.54-58
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    • 1995
  • This paper deals with an experimental study on the dynamic behaviour of rubber oil seals when the interferences between the shaft and the seal lip as well as the dynamic eccentricities are present. The micro-separation of the sealing gap was observed with the aid of an image processing apparatus. The temperature of the seal lip edge, friction torque and the dynamic sealing gap profile are experimentally investigated for the initial interference and the shaft eccentricity. The data was simultaneously measured under the operation conditions. Experimental results show that, as the shaft speed is increased, the leakage of sealed fluids is increasing for a certain range of shaft speeds. The test data indicates that the shaft eccentricity clearly produces the gap separation between the shaft and the seal lip which is unable to follow the radial displacement of shaft as the shaft speed increases.

Profile Measurements of Micro-aspheric Surfaces Using an Air-bearing Stylus with a Microprobe

  • Shibuya, Atsushi;Gao, Wei;Yoshikawa, Yasuo;Ju, Bing-Feng;Kiyono, Satoshi
    • International Journal of Precision Engineering and Manufacturing
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    • v.8 no.2
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    • pp.26-31
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    • 2007
  • A novel scanning probe measurement system was developed to enable precise profile measurements of microaspheric surfaces. An air-bearing stylus with a microprobe was used to perform the surface profile scanning. The new system worked in a contact mode and had the capability of measuring micro-aspheric surfaces with large tilt angles and complex profiles. Due to limitations resulting from the contact mode, such as possible damage caused by the contact force and lateral resolution restrictions from the curvature of the probe tip, several system improvements were implemented. An air bearing was used to suspend the shaft of the probe to reduce the contact force, enabling fine adjustments of the contact force by changing the air pressure. The movement of the shaft was measured by a linear encoder with a scale attached to the actual shaft to avoid Abbe errors. A $50-{\mu}m-diameter$ glass sphere was bonded to the tip of the probe to improve the lateral resolution of the system. The maximum contact force of the probe was 10 mN. The shaft was capable of holding the probe continuously if the contact force was less than 40 mN, and the resolution of the probe could be as high as 10 nm, The performance of the new scanning probe measurement system was verified by experimental data.