• 제목/요약/키워드: Process pressure

검색결과 6,551건 처리시간 0.041초

고진공 운송계에서의 정밀 압력제어장치의 설게 및 성능시험 (Design and Performance Evaluation of the Precision Pressure Control System for the High Vacuum Transport Module)

  • Jang, W.I.;Jang, K.H.;Lee, J.H.
    • 한국정밀공학회지
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    • 제12권7호
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    • pp.92-98
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    • 1995
  • In the cluster tool, it is necessary to precisely control the vacuum pressure for the wafer transportation between transport module and cassette or process modules with the range of 1*10$^{-4}$ to 5*10$^{-5}$ torr. So we have designed the pressure control system for the transport module of the cluster tool and have evaluated its performance. Digital PID is utilized with the weighted sum of both three previous errors and one current error. The feedback signal is put into the nitrogen mass flow controller using the transport module controller. This pressure control system can prevent the transport module from the particle generation and backstreaming of hazardous process gases of the process chamber.

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드로우 금형의 에어포켓 유출 유동해석 (Flow Analysis of the Air Pocket in Draw Die)

  • 황세준;박원규;김철;오세욱;조남영
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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    • pp.345-348
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    • 2006
  • In sheet metal forming process using press and draw die some defect can be made because of the high pressure of air pocket between draw die and the product. The purpose of this study is to develop a program to decide an optimal combination of air vent hole size and number to prevent those defect on product. The air inside air pocket is considered as ideal gas and the compression and expansion is assumed as isentropic process. The mass flow is computed in two flow condition: unchocked and chocked condition. The present computation obtains required cross-sectional area of air vent hole for not exceeding the user specified pressure such as the pressure for yielding strength of the product or the pressure for unchocked flow. To validate the program the present results are compared with the results of other researchers and commercial CFD code.

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이중복합봉 정수압 압출시 접합면 거동에 관한 연구 (A Bonding Surface Behavior of Bi-metal Bar through Hydrostatic Extrusion)

  • 박훈재;나경환;조남선;이용신
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 춘계학술대회논문집
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    • pp.140-143
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    • 1997
  • The present study is concerned with the hydrostatic extrusion process of copper-clad aluminium bar to investigate the basic flow characteristics. Considering the bonding mechanism of bi-metal contact surface as cold pressure welding, the normal pressure and the contact surface expansion are selected as process parameters governing the bonding condition. The critical pressure required for the bonding at the interface is obtained by solving a "local extrusion" using a slip line meyhod. A viscoplastic finite element method is used to analyze the steady state extrusion process. The boundary profile of bi-metal rod is predicted by tracking a particle path adjacent to interface surface. The variations of contact surface area and the normal pressure along the interface profile are predicted and compared to those by experiments.

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사출성형시 보압이 냉각시간에 미치는 영향 (Effects of holding pressure affecting cooling time in injection molding)

  • 문영배;최윤식;정영득
    • Design & Manufacturing
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    • 제2권1호
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    • pp.39-43
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    • 2008
  • There occur not only many problems in the injection process but also low quality productivity due to the injection conditions of various injection factors. Injection molding process factors such as molding temperature, injection pressure, flow rate and flow velocity, must be controlled properly in filling and packing phases in the injection molding process. In this study, effects of these factors on the injection molding were investigated through the flow analysis for the holding pressure affecting cooling time. Results of this study would be helpful to setting of holding pressure for optimization of forming condition in order to reduce cooling time in injection molding.

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하이드로 포밍 공정의 압력 추종제어에 관한 연구 (A pressure tracking controller for hydroforming process)

  • 박희재;조형석;현봉섭
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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    • pp.317-323
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    • 1987
  • A pressure tracking control of hydroforming processes, which is used in the precision forming of. sheet metals, is considered in this paper. The hydroforming of sheet metal is performed between the high-pressure chamber controlled by pressure control valve and the punch moving with constant speed. Since the pressure in the forming chamber is a critical factor to the quality of the product severely. It is important to control the pressure to follow a prescribed pressure trajectory, depending upon the material volume and shape of the parts to be formed. Taking into consideration of the volume chamge of forming chamber during the process and the nonlinearity of the electro-magnetic relief valve, a mathematical formulation of the model describing the dynamic characteristics of this model obtained. Based upon this model a PID controller is designed for the pressure tracking.

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FAMILY MOLD의 유동 밸런스와 금형 내압에 관한 연구 (A Study on Flow Balance and Cavity Pressure in Family Mold)

  • 김태철;이대근;홍기복;김영근;박인수
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 추계학술대회 논문집
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    • pp.603-607
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    • 2002
  • Cavity pressure is a factor of what is occurring inside the mold and is used as one of the process parameters that control the overall injection molding cycle. The insight of cavity pressure is able to predict part quality and optimum process condition. In this paper, it is adapted ejector pin sensor to measure the cavity pressure and investigates the flow balance and the cavity pressure according to different runner thickness for adjusting the flow balance. Flow balance is very important to have not the poor results such as flash and warpage in the family mold. This paper predicted flow balance and cavity pressure using CAE analysis tool and compared with the test results. The results of analysis and test have a good agreement with the cavity pressure profile and flow pattern of the test.

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저압보일러에서 고온의 온수 생성 후 압축기에서 고압수를 생성하는 고온·고압 세척시스템에 관한 연구 (A Study on a High-Temperature/High-Pressure Washing System in which High-Temperature Water is Generated in a Low-Pressure Boiler and High-Pressure Water is Generated Thereafter in a Compressor)

  • 조동현
    • 한국기계가공학회지
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    • 제18권1호
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    • pp.94-100
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    • 2019
  • This study was conducted on a high-temperature/high-pressure washer in which low-pressure cold water in a boiler is heated to a temperature range of $70{\sim}80^{\circ}C$ by supplying diesel combustion heat. The high-temperature water is sent to a compressor to increase its pressure to 200 bar, thereby making high-temperature/high-pressure water, which is sprayed through a spray nozzle. In the results of this study, the spray temperature of the high-pressure washing was shown to be the highest when the ratio between the actual amount of combustible air and the theoretical amount of air was 1:1 and the energy consumption rate of the low-pressure boiler type high-pressure washer was shown to be much lower than that of the high-pressure boiler type high-pressure washer.

The Effect of Pressure on the Properties of Carbon/Carbon Composites during the Carbonization Process

  • Joo, Hyeok-Jong;Oh, In-Hwan
    • Carbon letters
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    • 제3권2호
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    • pp.85-92
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    • 2002
  • 4D carbon fiber preforms were manufactured by weaving method and their carbon fiber volume fractions were 50% and 60%. In order to form carbon matrix on the preform, coal tar pitch was used for matrix precursor and high density carbon/carbon composites were obtained by high densification process. In this process, manufacture of high density composites was more effective according to pressure increasement. When densificating the preform of 60% fiber volume fraction with 900 bar, density of the composites reached at 1.90 $g/cm^3$ after three times processing. Degree of pressure in the densification process controls macro pore but it can not affect micro pore. During the carbonization process, micro pore of the preform were filled fully by once or twice densification processing. But micro pore were not filled easily in the repeating process. Therefore, over three times densification processing is the filling micro pore.

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알루미늄 소재의 레오로지 직접단조공정에서 가압력이 액상 편석에 미치는 영향 (The Effect of Pressure on Liquid Segregation in Direct Rheo-Forging Process of Aluminum Alloys)

  • 오세웅;배정운;강충길
    • 소성∙가공
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    • 제16권3호
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    • pp.178-186
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    • 2007
  • Rheo-forging process of aluminum alloy is suitable for large parts of net shape without defects and excellent mechanical properties in comparison with conventional die casting and forging process. To control the microstructure of the product with high mechanical properties in rheo-forming, solid fraction is required to prevent porosity and liquid segregation. Therefore, in rheo-forging process, die shape, pressure type and solid fraction are very important parameters. The defects such as porosity, liquid segregation and unfitting phenomena occur during rheo-forging process. To prevent these defects, mechanical properties and microstructure analysis of samples versus the change of pressure are carried out and the problem and its solutions are proposed. Also, the mechanical properties versus various pressures were compared with and without heat treatment. The alloys used for rheo-forming are A356 and 2024 aluminum alloy. The rheology material is fabricated by electromagnetic process with controlling current and stirring time.

Modelling of Optimum Design of High Vacuum System for Plasma Process

  • Kim, Hyung-Taek
    • International journal of advanced smart convergence
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    • 제10권1호
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    • pp.159-165
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    • 2021
  • Electronic devices used in the mobile environments fabricated under the plasma conditions in high vacuum system. Especially for the development of advanced electronic devices, high quality plasma as the process conditions are required. For this purpose, the variable conductance throttle valves for controllable plasma employed to the high vacuum system. In this study, we analyzed the effects of throttle valve applications on vacuum characteristics simulated to obtain the optimum design modelling for plasma conditions of high vacuum system. We used commercial simulator of vacuum system, VacSim(multi) on this study. Reliability of simulator verified by simulation of the commercially available models of high vacuum system. Simulated vacuum characteristics of the proposed modelling agreed with the observed experimental behaviour of real systems. Pressure limit valve and normally on-off control valve schematized as the modelling of throttle valve for the constant process-pressure of below 10-3 torr. Simulation results plotted as pump down curve of chamber, variable valve conductance and conductance logic of throttle valve. Simulated behaviors showed the applications of throttle valve sustained the process-pressure constantly, stably, and reliably in plasma process.