• Title, Summary, Keyword: controlled rolling

Search Result 144, Processing Time 0.042 seconds

Study of Material Properties of High Strength Microalloyed Steel for Cold Forming by Controlled Rolling and Cooling Technology (제어압연.제어냉각기술로 제조된 냉간성형용 비조질강의 소재특성)

  • Kim, N.G.;Park, S.D.;Kim, B.O.;An, J.Y.;Choi, H.J.
    • Transactions of Materials Processing
    • /
    • v.15 no.8
    • /
    • pp.603-608
    • /
    • 2006
  • The main purpose of the present study has been placed on investigating the mechanical properties and microstructures of C-Si-Mn-V steels for cold forming manufactured by controlled rolling and cooling technology. The steels were manufactured in electric arc furnace (EAF) and casted to $160{\times}160mm$ billet. The billets were reheated in walking beam furnace and rolled to coil, the stocks were rolled by Controlled Rolling and Cooling Technology (CRCT), so rolled at low temperature by water spraying applied in rolling stage and acceleratly cooled before coiling. Rolled coils were cold drawed to the degree of 16%, 27% of area reduction respectively without heat treatment. Microstructual observation, tensile test, compression test and charpy impact tests were conducted. The mechanical properties of the steels were changed by area reduction of cold drawing and it is founded that there are optimum level of cold drawing to minimize compression stress for these steels. From the result of this study, it is conformed that $80kg_{f}/mm^{2},\;90kg_{f}/mm^{2}$ grade high strength microalloyed steel for cold forming are developed by accelerated cooling and optimum cold drawing.

Development of High Strength Microalloyed Steel for Cold Forming by Controlled Rolling and Cooling Technology (제어압연${\cdot}$제어냉각기술을 이용한 고강도 냉간성형용 비조질강의 개발)

  • Kim N. G.;Park S. D.;Kim B. O.;Choi H. J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • /
    • pp.321-324
    • /
    • 2005
  • The main purpose of the present study has been placed on investigating the effects of controlled rolling and cooling on the microstructures and mechanical properties of C-Si-Mn-V steels for cold forming. The steels were manufactured in vacuum induction melting(VIM) furnace and casted to 1.1ton Ingots and the ingots were forged to $\Box150$ billet. The forged billets were reheated in walking beam furnace and rolled to coil, the stocks were rolled by Controlled Rolling and Cooling Technology (CRCT), so rolled at low temperature by water spraying applied in rolling stage and acceleratly cooled before coiling. Rolled coils were cold drawed to the degree of $27\%$ of area reduction without heat treatment. Microstructual observation, tensile test, compression test and charpy impact tests were conducted. The mechanical properties of the steels were changed by area reduction of cold drawing and it is founded that there are optimum level of cold drawing to minimize compression stress for these steels. From the result of this study, it is conformed that mechanical properties and microstructure of C-Si-Mn-V steels for cold forming were enhanced by accelerated cooling and founded optimum level of cold drawing.

  • PDF

A Study on the Design of the Anti-Rolling Control System for a Ship (선박의 횡동용 방지 장치 개발에 관한 연구)

  • Kim, Young-Bok;Byun, Jung-Hoan
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.7 no.5
    • /
    • pp.438-444
    • /
    • 2001
  • In this paper, an actively controlled anti-rolling system is considered to reduced the rolling motion of the ship. In this control system, a small auxiliary mass is installed on the upper area of the ship, and the actuator is connected between the auxiliary mass and the ship. The actuator reacts against the auxiliary mass, applying inertial control corves to the ship to reduce the rolling motion in the desired manner. in this paper, we apply the PID controller to design the anit-rolling control system for the controlled hip. And the experimental result shows that the desirable control performance is achieved.

  • PDF

An Experimental Study on the Rolling Motion Control of a Ship Based on LMI Approach (LMI를 이용한 선박 횡동요 제어에 관한 실험적 연구)

  • 채규훈;김영복
    • Journal of Ocean Engineering and Technology
    • /
    • v.17 no.2
    • /
    • pp.60-66
    • /
    • 2003
  • In this paper, an actively controlled anti-rolling system is considered, in order to reduce the rolling motion of a ship. In this control system, a small auxiliary mass is installed on the upper area of the ship, and an actuator is connected between the auxiliary mass and the ship. The actuator reacts the auxiliary mass, applying inertial control forces to the ship to reduce the rolling motion in the desired manner. In this paper, we introduce LMI based H$_{\infty}$ control approach to design the anti-rolling control system for the controlled ship. And the experimental results show that the desirable control performance can be achieved.

An Experimental Study on the Development of the Anti-Rolling Control System for a Ship (선체 횡동요 방지 장치 개발을 위한 실험적 연구)

  • 김영복;변정환;양주호
    • Journal of Ocean Engineering and Technology
    • /
    • v.14 no.4
    • /
    • pp.43-48
    • /
    • 2000
  • In this paper, an actively controlled anti-rolling system is considered to reduce the rolling motion of the ship. In this control system, a small auxiliary mass is installed on the upper area of the ship, and actuator us connected between the auxiliary mass and a ship. The actuator reacts against the auxiliary mass, applying inertial control forces to the ship to reduce the rolling motion in the desired manner. In this paper, we apply the PID controller to design the anti-rolling control system for the controlled ship. And the experimental result shows that the desirable control performance is achieved.

  • PDF

Microstructure Characteristics and Identification of Low-Carbon Steels Fabricated by Controlled Rolling and Accelerated Cooling Processes (제어 압연과 가속 냉각에 의해 저탄소강에서 형성되는 미세조직의 특징과 구분)

  • Lee, Sang-In;Hong, Tae-Woon;Hwang, Byoungchul
    • Korean Journal of Materials Research
    • /
    • v.27 no.11
    • /
    • pp.636-642
    • /
    • 2017
  • In the present study the microstructure of low-carbon steels fabricated by controlled rolling and accelerated cooling processes was characterized and identified based on various microstructure analysis methods including optical and scanning electron microscopy, and electron backscatter diffraction(EBSD). Although low-carbon steels are usually composed of ${\alpha}-ferrite$ and cementite($Fe_3C$) phases, they can have complex microstructures consisting of ferrites with different size, morphology, and dislocation density, and secondary phases dependent on rolling and accelerated cooling conditions. The microstructure of low-carbon steels investigated in this study was basically classified into polygonal ferrite, acicular ferrite, granular bainite, and bainitic ferrite based on the inverse pole figure, image quality, grain boundary, kernel average misorientation(KAM), and grain orientation spread(GOS) maps, obtained from EBSD analysis. From these results, it can be said that the EBSD analysis provides a valuable tool to identify and quantify the complex microstructure of low-carbon steels fabricated by controlled rolling and accelerated cooling processes.

A study on the improvement of thickness accuracy in a plate mill

  • Lee, Duk-Man
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.723-727
    • /
    • 2003
  • In this paper, two methods are discussed for good rolling force prediction in a plate mill. One is about the development of a long and a short learning scheme using a Neural Network for normal rolling and the other is about a mathematical model improvement by considering microstructural changes for controlled rolling. The research results are implemented in a on-line system of Pohang Works in POSCO and the field tests have showed that the prediction accuracies of rolling force are highly improved.

  • PDF

The Effect of Roll Arrangement in the Cold Rolling Mill on the Wear (냉간 압연기용 롤의 배열이 마멸에 미치는 영향)

  • 손영지
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
    • /
    • /
    • pp.74-80
    • /
    • 1999
  • Work roll wear in the cold rolling of mild steel strip is strongly affected by rolling materials, rolling conditions such as roll arrangement in the cold rolling mill and lubrication. The tests were performed to find the effects of roll arrangement n the cold rolling mill on the work roll wear under the same lubricating conditions. The obtained results are as follows:If the distance of cold rolling is about 60km, the surface roughness of its was reduced by half(Ra 0.49${\mu}{\textrm}{m}$) and Pc(peak count) also was decreased to 60 ea/cm.It is easier for CC(Continuous casting) to make a slip on rolling than IC(Ingot casting). It is due to surface mirror in which first residual product appears and iron powder included Al2O3 is sticked. Because bending degree of 4Hi-rolling mill is higher than 6Hi-rolling mill, the first surface mirror was occurred to its center-point which is loaded strongly. 6Hi-rolling mill shape-controlled by intermediate roll doesn't need the initial crown to work roll. Therefore, fatigue and wear would appear a little bit.

  • PDF

Study on the Spheroidization of Cementite by Controlled-Rolling and Martensitic Nucleation and its Growth during Cooling in Ultra High Carbon Steel (초고탄소강의 제어압연에 의한 세멘타이트의 구상화와 냉각중 마르텐사이트의 핵발생과 성장의 현상론적 고찰)

  • Choi, C.S.;Yoon, J.K.
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.6 no.2
    • /
    • pp.98-106
    • /
    • 1993
  • Ultra high carbon steel (Fe-1.4%C) was prepared by means of a high frequency induction furnace. The preferred nucleation site of martensite was observed. The changes of hardness and impact thoughness due to tempering temperatures, and the spheroidization of cementite by controlled -rolling were also studied for the steel. The preferred nucleation site of martensite in the ultra high carbon steel is prior austenite grain boundary. The hardness of the steel is slightly increased up to about $300^{\circ}C$, and then decreased with further tempering temperature. However, the impact energy keeps a almost constant value, independent of the tempering temperature. The spheroidization of cementite is accelerated as the reduction in thickness per rolling pass is increased and the number of the rolling passes becomes greater.

  • PDF

Crop Control by Using Roll Gap Difference in Plate Mill (두께차 압연에 의한 후강판 크롭저감 연구)

  • 이준정
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • /
    • pp.48-51
    • /
    • 2000
  • In plate mill studies on crop decrease of the top and bottom ends of hot rolled plate have been performed. The plane view shape for the thin plate after broadside rolling was controlled by roll gap difference with AGC in broadside rolling process. New models for thin slab after broadside rolling have been formulated based on the actual production rolling data to give optimal rolling condition A new plate rolling method called by dog bone rolling has been applied making it is possible to prevent non-uniform plastic deformation at top and bottom ends. By new rolling method crop losses of rolled plate have been improved by 10% on average with an effective fishtail crop shape.

  • PDF