• 제목/요약/키워드: Roll reduction

검색결과 189건 처리시간 0.037초

SCM435 강의 고온마찰계수 계산 (Computation of High Temperature Friction Coefficient of SCM435 Steel)

  • 성중의;조상흠;이형직;이영석
    • 소성∙가공
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    • 제20권3호
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    • pp.243-249
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    • 2011
  • In this study, an approach designed to compute high temperature friction coefficients for SCM 435 steel through a pilot hot rolling test and a finite element analysis, is proposed. Single pass pilot hot flat rolling tests with reduction ratios varying from 20 to 40% were carried out at temperatures ranging from 900 to $1200^{\circ}C$. In the proposed approach, the friction coefficient is calculated by comparing the measured strip spread and the roll force with the simulation results. This study showed that the temperature and reduction ratio had a significant influence on the friction coefficient. As both material temperature and reduction ratio become higher, the friction coefficient increases monotonically. This finding is not in agreement with the Ekelund model, which is widely used in the analysis of the hot rolling process. In the present work, the friction coefficient at a reduction ratio of 40% was found to be 1.2 times greater than that at a reduction of 30%. This higher friction coefficient means that an increment of the roll thrust force is expected at the next stand. Therefore, a roll pass designer must understand this phenomenon in order to adjust the reduction ratio at the stands while keeping the driving power, the roll housing structure and the work roll strength within the allowable range.

도그본 고려한 조압연 압연하중 예측모델 개발 (Model for the prediction of Roll Force of Roughing Mill considering Width reduction)

  • 곽우진;이성진
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2007년도 춘계학술대회 논문집
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    • pp.223-225
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    • 2007
  • Online models predicting roll force and forward slip of roughing mill was developed using nondimensional parameters. Using the effective inlet thickness, roll force model take into account the effect of inlet dog-bone shape of slab which take places after width reduction through edger rolling in roughing mill. The prediction accuracy of the proposed model is examined through comparison with measurements.

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FPSO의 횡요 감쇠 장치에 대한 고찰 (A Study on Roll Reduction Devices for FPSOs)

  • 박인규;양진호;신현수
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2004년도 학술대회지
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    • pp.30-35
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    • 2004
  • Several roll motion reduction devices are reviewed and suggested for the application in FPSO. The firstly suggested solution is the shape of the bilge. The next is a bilge keel. The last suggestion is the ART (anti-rolling tank). Typical U-tube type ART is designed for a FPSO and examined extensively by model experiment. The model section was made of transparent acryl. Free decay test, forced oscillation test and wave test were carried out at a two-dimensional wave flume. U-tube type ART is effective only when the natural periods of ART and ship are same. Therefore, the divided U-tube type ART with split plate is suggested for the reduction of the roll motion of a FPSO over the wide range of the roll period.

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승용차의 차량 롤 제어를 위한 시스템 구현 (Implementation of Roll Control System for Passenger Car)

  • 장주섭;이상호
    • 한국자동차공학회논문집
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    • 제5권5호
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    • pp.20-26
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    • 1997
  • A System for reducing vehicle body roll by active control is developed. The stabilizer bar with hydraulic rotary actuator produces anti-roll moment which suppresses roll tendency. This reduction of roll improves the driving safety as well as the ride comfort. Vehicle test data shows considerable reduction of roll angle during steady-state turning. Also improvement of ride comfort is achieved by making the actuator freely rotatable, i.e. by connecting all chambers of actuator in normal driving conditions. A control algorithm using steering wheel angle and vehicle speed signal as input valve is applied. It is compared with signal of the G-sensor.

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파인블랭킹 공정에서의 곡률부 다이롤 감소를 위한 전단 공정 설계 (Design of shearing process to reduce die roll in the curved shape part of fine blanking process)

  • 전용준
    • Design & Manufacturing
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    • 제17권3호
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    • pp.15-20
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    • 2023
  • In the fine blanking process, which is a press operation known for producing parts with narrow clearances and high precision through the application of high pressure, die roll often occurs during the shearing process when the punch penetrates the material. This die roll phenomenon can significantly reduce the functional surface of the parts, leading to decreased product performance, strength, and fatigue life. In this research, we conducted an in-depth analysis of the factors influencing die roll in the curvature area of the fine blanking process and identified its root causes. Subsequently, we designed and experimentally verified a die roll reduction process specifically tailored for the door latch manufacturing process. Our findings indicate that die roll tends to increase as the curvature radius decreases, primarily due to the heightened bending moment resulting from reduced shape width-length. Additionally, die roll is triggered by the absorption of initial punch energy by scrap material during the early shearing phase, resulting in lower speed compared to the product area. To mitigate the occurrence of die roll, we strategically selected the Shaving process and carefully determined the shaving direction and clearance area length. Our experiments demonstrated a promising trend of up to 75% reduction in die roll when applying the Shaving process in the opposite direction of pre-cutting, with the minimum die roll observed at a clearance area length of 0.2 mm. Furthermore, we successfully implemented this approach in the production of door latch products, confirming a significant reduction in die roll. This research contributes valuable insights and practical solutions for addressing die roll issues in fine blanking processes.

콕스밀에서 평균변형율, 압하력, 단면감소율에 대한 수식모델개발 (Development of Online Model for Mean Effective Strain, Roll Force and Area Reduction in Bar Rolling with Three Rolls)

  • 제상현;황상무
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2001년도 추계학술대회 논문집
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    • pp.162-165
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    • 2001
  • In industrial practice, caliber design in shape rolling depends on the designer's experience, which in general is obtained through costly trial-and error process. on-line model which is relations of mean effective strain, roll force and area reduction is derived from finite element process simultion in bar rolling with three rolls.

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조타장치 제어에 의한 횡동요 감소 효과 (Effects for reduction of roll motion by the control of steering gear)

  • 최찬문;이창헌;안장영;요시무라 야스오
    • 수산해양기술연구
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    • 제47권1호
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    • pp.37-45
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    • 2011
  • Reduction of ship's rolling is the most important performance requirement for improving the safety of the crew on board and preventing damage to cargo as well as improving the comfort of the ride. It is a common experience for mariners, to see that steering with a rudder generally induces rolling of the ship, though the original aim of the rudder is to keep the ship's heading to the required course. At the first stage, when a rudder is steered, usually a ship heels in an inward direction, due to the roll moment acting on the rudder. At the next stage in steering, the main heel may change to an outward. This coupling between rudder and roll motion has become an attractive problem from the point of view of roll stabilization using the rudder, because it is a natural in sight that if the rudder action is skillfully related to the change of roll as well as to the course deviation, the roll can be reduced to a certain degree. The main aim of this paper is to discuss the results of the actual full-scale sea trials carried out on steer gear No.1 and No.1 2, the individual quartermaster and to make clear their statistical properties, using the actual data which included measurement of roll angle, roll rate and the comparative tests were carried out immediately after each other, in order to minimize any statistical variation in sea conditions. It can be concluded that the steer gear No. 1 2 reduced the roll motion on average by about 21% in comparison with the No.1 and confirmed the some difference as per a ability of quarter-master's maneuver.

유한요소법을 이용한 조압연에서의 압하력 및 압연동력 예측 온라인 모델 개발 (Development of an On-Line Model for the Prediction of Roll Force and Roll Power in Roughing Mill by FEM)

  • 김성훈;곽우진;황상무
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2001년도 추계학술대회 논문집
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    • pp.134-137
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    • 2001
  • In this paper on-line model is derived from investigating via series of finite element process simulation. Some variables that little affect on non-dimensional parameters. ie. forward slip and torque factor. is extracted from composing on-line model Especially, this research focused on deriving on-line model which exactly predict roll force and roll power in the roughing mill process under small shape factor and small reduction ratio. The prediction accuracy of the proposed model is examined through comparison with predictions from a finite element process model

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파이프 비닐온실용 권취식 창개폐기의 개발 (Development of roll - up ventilation system for pipe- constructed plastic film greenhouse)

  • 이기명;박규식;김유일;김태홍
    • 생물환경조절학회지
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    • 제4권2호
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    • pp.232-239
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    • 1995
  • This study was carried out to get required torque data needed to design and develop a roll-up ventilation system in a pipe-constructed plastic film green-house. The results obtained from this study are as follows : 1. The required torques of a roll-up ventilation system in greenhouse are the functions of its length. The torques should multiplied by the conversion coefficients (2.0 in ceiling vent, 1.8 in side vent) in case of application. 2. In constructing pipe-constructed plastic film greenhouse, a shaft pipe is the largest essential element in roll - up shaft weight constitution which have an effect on the required torques. Therefore, the pipe should be light using nonferrous materials like aluminum alloy. 3. A planetary reduction ventilator of differential ring gear type is suitable for a roll-up ventilation system, because it can make high efficient reduction just using the first step shift.

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고속도공구강롤을 적용한 열간유압연 사용특성 연구 (Investigation of Effect of Hot Rolling Oil of on Rolling with HSS Roll)

  • 유재희;황상무;김철희
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 추계학술대회논문집
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    • pp.115-118
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    • 1997
  • Recently, hot rolling oil lubrication technology is required to face with the new environments such as the rapid introduction of high wear resistent high speed steel roll the development of continuous hot rolling technology. In the hot strip mill, according to rolling and quality required conditions are constrict, Roll material of hot rolling finishing stand is changing Hi-Cr Roll to High Speed Steel [HSS] Roll. The problem of HSS Roll of roll force and strip scale defects are increasing in hot strip mill, So we have tested HSS Roll in hot rolling simulator as rolling condition, rolling speed, draft, hot oil concentration. To reduce roll force and prevent scale defects. We get some merit rolling force, rolling torque, roll wear reduction, roll and strip surface roughness and hot rolling critical oil concentration 0.4%. Finally we are going to investigate the effect of hot rolling oil of on rolling with HSS Roll.

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