• 제목/요약/키워드: Cold-working

검색결과 325건 처리시간 0.025초

냉간압연가공시 Work roll 마멸과 판면조도에 관한 연구 (A Study on Work Roll Wear and Surface Roughness of Steel Strip in the Cold Rolling)

  • 전언찬;김순경
    • 한국정밀공학회지
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    • 제8권4호
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    • pp.33-40
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    • 1991
  • The decrease in surface roughness of work roll and steel strip in cold rolling of low carbon steel strip has been investigated by working distance, materials, total separating force and total reduction ratio. The main results are as follows; For the same lubricating conditions. 1) The changing of surface roughness of steel strip were similar to work roll. The transcription ratio is in inverse proportion to the carbon content of steel strip. 2) The surface roughness of steel strip is hardly change according to changing of total separating force and total reduction ration. 3) The wear of work rolls surface is more rapid in that case of continuous casted steel strip than ingot casted steel strip. The aluminium content dull powder adhere on the rolls surface, and so. It makes the mirror surface of work roll accelerate.

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회전성형법에 의한 분말성형체의 고밀도화 연구 (The Cold Rotary Repressing Process of Sintered Preform)

  • 윤덕재;임성주;최석우;나경환
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 춘계학술대회논문집
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    • pp.281-286
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    • 1997
  • Thin study is concerned with the cold repressing of sintered preform by rotary forging process. A experiment has been carried out using the rotary powder forging press(500kN) which was designed and constructed in the authors' laboratory. The effect of process variables and aspect ratios of sintered preform was observed and measured by several mechanical test, such as working force, hardness distribution, density, and microstructures of the specimens. It is found that the highly densified P/M parts can be obtained and this process is very effective for improving quality of the powder products.

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마멸모델을 이용한 금형마멸 예측에 관한 연구 (A Study on the Prediction of Die Wear using Wear Model)

  • 박종남
    • 한국기계가공학회지
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    • 제12권1호
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    • pp.90-96
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    • 2013
  • During the cold forming, due to high working pressure acting on the die surface, failure mechanics must be considered before die design. One of the main reasons of die failure in industrial application of metal forming technologies is wear. Die wear affects the tolerances of formed parts, metal flow and costs of process etc. The only way to control these failures is to develop methods which allow prediction of die wear and which are suited to be used in the design state in order to optimize the process. In this paper, the wear experiments to obtain the wear coefficients and the upsetting processes was accomplished to observe the wear phenomenon during the cold forming process. The analysis of upsetting processes was accomplished by the rigid-plastic finite element method. The result from the deformation analysis was used to analyse the die wear during the processes and the predicted die wear profiles were compared with the measured die wear profiles.

정수압 압출 소재의 열처리 조건에 따른 마그네슘합금(AZ31)의 특성 변화 (Characteristics of Extruded Mg alloy(AZ31) for various annealing temperatures)

  • 서영원;최호준;윤덕재
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2005년도 추계학술대회 논문집
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    • pp.463-466
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    • 2005
  • Restoring ductility or removing residual stresses is a necessary operation when a large amount of cold working is to be performed, such as in a cold-forging or warm forging process. The advantage of annealing temperatures was investigated. After Hydrostatic Extrusion process, extruded materials were annealed at $200^{\circ}C,\;350^{\circ}C,\;450^{\circ}C$ for 1 hour. Microstructure of the annealed material was observed to make an understand about the difference in mechanical properties.

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북서태평양 명태 어장의 해황 - 2 . 기후의 특성 - (Oceanography in the Waters Adjacent to Kamchatka and Kurile islands in the Northwestern Pacific - II)

  • 한영호
    • 수산해양기술연구
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    • 제13권1호
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    • pp.17-25
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    • 1977
  • For four calender years (1971-1974), daily observations of weather conditions (air temperature, humidity, wind speed, wind direction, cloud amount, fog, precipitation etc.) at six stations in the north western Pacific Ocean are used to calculate mean monthly values and to check extra-conditions. At Petropavlosk and Miko'skoe, where indicate the characteristics of modified continental climate, the temperature and humidity are high in summer, and Iow in winter. At A Dak and She Mya, where indicate the characteristics of warm current type maritime climate, humidity is high in all season and annual range of air temperature is nearly negligible. At Simusir and Vasi!' eva, where indicate the characteristics of cold current type maritime climate, humidity is high in all season and annual range of air temperature is $15^{\circ}C.$ As dry cooling power is relatively high in winter, working condition on deck is bad. Most of fogs are advection fog in the area of cold current type climate in summer.

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LNG 냉열을 이용하는 동력사이클 열역학 해석 (Thermodynamic Analysis of Power Generation Cycle Utilizing LNG Cold Energy)

  • 최권일;장홍일
    • 한국초전도ㆍ저온공학회논문지
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    • 제1권1호
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    • pp.48-55
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    • 1999
  • thermodynamic cycle analysis has been performed for the power generation systems to utilize the cold energy of liquefied natural gas (LNG). The power cycle used the air or water at room temperature as a heat source and the LNG at cryogenic temperature as a heat sink. Among manypossible configurations of the cycle. the open Rankine cycle. and the closed Brayton cycle, and the closed Rankine cycle are selected for the basic analysis because of their practical importance. The power output per unit mass of LNG has been analytically calculated for various design parameters such as the pressure ratio. the mass flow rate. the adiabatic efficiency. the heat exchanger effectiveness. or the working fluid. The optimal conditions for the parameters are presented to maximize the power output and the design considerations are discussed. It is concluded that the open Rankine cycle is the most recormmendable both in thermodynamic efficency and in practice.

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신경망을 이용한 냉연 압하력 예측 (Rolling Force Prediction in Cold rolling Mill using Neural Networks)

  • 조용중;조성준
    • 산업공학
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    • 제9권3호
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    • pp.298-305
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    • 1996
  • Cold rolling mill process in steel works uses stands of rolls to flatten a strip to a desired thickness. Most of rolling processes use mathematical models to predict rolling force which is very important to decide the resultant thickness of a coil. In general, these mathematical models are not flexible for variant coil types and cannot handle various elements which is practically important to decide accurate rolling force. A corrective neural network is proposed to improve the accuracy of rolling force prediction. Additional variables-composition of the coil, coiling temperature and working roll parameters-are fed to the network. The model uses an MLP with BP to predict a corrective coefficient. The test results using 1,586 process data collected at POSCO in early 1995 show that the proposed model reduced the prediction error by 30% on average.

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보텍스튜브에서 랭퀴-힐쉬효과와 줄-톰슨효과가 에너지분리에 미치는 영향 (The Influence of Ranque-Hilsch Effect and Joule-Thomson Effect to Energy Separation in a Vortex Tube)

  • 유갑종;방창훈;김병하
    • 설비공학논문집
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    • 제12권8호
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    • pp.703-710
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    • 2000
  • Energy separation characteristic occurring in a counterflow vortex tube was studied experimentally, where air, $C_2$, and R22 were used as working fluids. The experiments were carried out with pressure ratio from 3 to 8 and cold mass fraction(y) from 0.1 to 0.9. As results, Ranque-Hilsch effect showed different results from adiabatic expansion process. Temperature difference in vortex tube outlet was affected by Joule-Thomson effect as well as Ranque-Hilsch effect. The more effective the energy separation was, the more increased the entropy in the cold oulet of vortex tube was.

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헬리컬기어 냉간단조 금형의 정밀방전가공 (Precision Electric Discharge Machining of a Cold Forging Die for Helical Gear Manufacturing)

  • 권정재;전병윤;전만수
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2005년도 추계학술대회 논문집
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    • pp.158-161
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    • 2005
  • In this paper, the precision electric discharge machining technology, the powder electric discharge machining technology, is applied to making a cold forging die for making the helical type of clutch gear. Various working conditions are investigated with emphasis on reduction of the electrode wear and enhancement of the surface roughness. Through the research work, the key technology of making the helical gear forging dies is achieved.

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탄소중립 확보를 위한 친환경 동절기 대체 열원 성능 검증 (Performance Verification of Curing Method in Cold-Weather with Using Energy Saving Electronic Heater for achieving Korean Carbon Neutra)

  • 조만기;김상균;홍성민;박종훈
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2021년도 가을 학술논문 발표대회
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    • pp.192-193
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    • 2021
  • Recently, the need to strengthen the Air Environment Conservation Act and secure alternative heat sources during the winter by carbon neutrality policies has been raised. Accordingly, winter construction, which has safety and quality measures, is emerging as an essential factor. It is believed that eco-friendly tropical type electric hot air heaters will be able to solve most of the problems of winter construction at construction sites, especially prevention of suffocation and fire accidents. In addition, as a result of on-site performance verification, it has secured more than the same performance as the existing curing method, and the curing technology can create an eco-friendly and pleasant working environment while considering safety and construction.

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