• Proceedings of the KSR Conference
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• 2003.10a
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• pp.144-150
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• 2003

This paper shows the systematic design technology for development of new high speed rolling stock and the important item by the instance of G7 R＆D project titled "Development of High Speed Railway Technology". This paper also describes core technology and concrete examples of its application during the development of high speed rolling stock.

• Transactions of Materials Processing
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• v.8 no.1
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• pp.78-91
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• 1999

The endless hot rolling has been focused as an innovative process technology for increasing the productivity drastically and reducing the imperfection of quality in hot rolled steel strip. To realize it in actual mill, a lots of new facilities such as bar coiler, movable LASER welder and high speed strip shear should be equipped. And also it is necessary to develop the control technique for changing the roll gap and rolling speed during rolling, which is named as Flying Gap and Speed Change control technology. To prevent a strip rupture caused by excessive tension, it is very important to minimize fluctuations in strip thickness and intension during FGSC control. In this paper, the mathematical model for FGSC control algorithm was suggested and dynamic simulation is performed to accertain the effect of suggested control method on fluctuations in strip thickness and tension. For endless hot rolling simulation, a lots of FGSC control situations, for instance - strip thickness change from strip to strip - strip width change from strip to strip - carbon content change from strip to strip are considered.

• Korean Journal of Materials Research
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• v.19 no.5
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• pp.265-269
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• 2009

The through-thickness variations of strain and microstructure during high-speed hot rolled 5052 aluminum alloy sheet were investigated. The specimens were rolled at temperature ranges from 410 to $560^{\circ}C$ at a rolling speed of 15 m/s without lubrication and quenched into water at an interval of 30 ms after rolling. The redundant shear strain induced by high friction between rolls and the aluminum sheet was increased largely beneath the surface at a rolling reduction above 50%. Dynamic recrystallization occurred in the surface regions of the specimen rolled under conditions of high temperatures or high rolling reductions.

• Transactions of Materials Processing
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• v.12 no.3
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• pp.244-250
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• 2003

Sheets of aluminum alloy 1100 were asymmetrically cold rolled in a rolling mill with different roll speeds. In order to promote the shear deformation during asymmetrical rolling, cold rolling without lubrication was performed with a roll speed ratio of 1.5/l.0. The evolution of texture components during asymmetrical rolling was investigated by the calculation of the orientation distribution function (ODF) using the monoclinic sample symmetry. The strain state during asymmetrical rolling was tackled by means of FEM calculations. Asymmetrical rolling gave rise to the development of pronounced strain gradients throughout the thickness layers which resulted in the formation of strong texture gradients in the aluminum sheet.

• Korean Journal of Materials Research
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• v.26 no.1
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• pp.8-12
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• 2016

Effects of conventional rolling(CR) and differential speed rolling(DSR) on the microstructure and mechanical properties of Cu-Ni-Si alloy were investigated in detail. The copper alloy with thickness of 3 mm was rolled to 50 % reduction at ambient temperature without lubricant with a differential speed ratio of 2:1. The conventional rolling in which the rolling speed of upper and lower rolls is identical was performed under identical rolling conditions. The shear strain introduced by the CR showed positive values at positions of upper roll side and negative values at positions of lower roll side. However, it showed zero or positive values at all positions for the samples rolled by the DSR. The microstrucure and texture development of the as-rolled copper alloy did not show any significant difference between CR and DSR. The tensile strength of the DSR processed specimen was larger than that of the CR processed specimen. The effects of rolling methods on the microstructure and mechanical properties of the as-rolled copper alloy are discussed in terms of the shear strain.

• Tribology and Lubricants
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• v.19 no.1
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• pp.1-8
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• 2003

Recently, PM-high speed steel(PM-HSS) has reportedly been a good alternative material for rolling mill because of its superior performance to conventional HSS. This paper has been aimed to investigate the possibility for application to rolling contact element for PM-HSS by X-ray diffraction technique. The X-ray elastic constant for PH-HSS has been found by X-ray diffraction during the four-point bending test. Residual stress and half-value breadth on the contact surface during rolling contact fatigue process by X-ray diffraction have also been measured. The result of this study shows that the application of X-ray diffraction technique to PM-HSS could be as possible alternative material as conventional HSS. Half-value breadth on rolling contact surface by X-ray diffraction is not changed during rolling contact fatigue process. On the other hand, the residual stress is changed. This suggests that dislocation reaction has been hardly occurred in rolling contact, depending on super-saturated carbon in PM-HSS.

• Journal of Mechanical Science and Technology
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• v.20 no.9
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• pp.1410-1417
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• 2006

The metal processing system usually consists of various components such like motors, work rolls, backup rolls, idle rolls, sensors, etc. Even a simple fault in a single component in the system may cause a serious damage on the final product. It is therefore necessary to diagnose the faults of the components to detect and prevent system failure. Especially, the defects in a work roll are critical to the quality of strip. It is especially difficult to detect faults of a roll by using the existing frequency analysis method if the speed of the roll is changing. In this study, a new diagnosis method for roll eccentricity under the roll speed changes was developed. The new method was induced from analyzing the rolling mechanism by using rolling force models, radius-speed relationship, and measured rolling force, etc. Simulation results by using the field data show that the proposed method is very useful.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.2
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• pp.102-107
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• 1996

It is difficult to analyze the high speed rolling missile with the generally used missile body fixed coordinates. In this study, we formulate the dynamic equations of the high speed rolling missile with the principal axis of inertia, and make the analytical model of one axis steering missile using pitch/yaw symmetry and complex summation method. With this model we analyze the control characteristics and propose the design considerations of high speed rolling missile with one axis control fin using PNG law in conjuntion with a seeker signal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.393-397
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• 2005

Since the braking system of rolling stock is directly linked to it's safety, ensuring reliability of braking system and evaluation of performance of it are very important. To develope the performance of braking system, it is required advanced technology and gradually various factors in the field test result. This study is designed to analyze the air pressure control about braking force in rolling stock, also, by comparing braking force of high speed railway with that of high speed train. This paper suggests to establish a method of computation of braking force form the air pressure control. And The high speed train researches into patterns of braking system such as the train of speed up and introduction of electric and pneumatic braking system.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.191-198
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• 2009

There are almost no studies on verification of requirements for high speed rolling stocks by means of RAM goals and on setting RAM goals by means of verification on practical reliability, availability and maintainability for high speed rolling stocks though they are covered in specification of an order that RAM goals asked of rolling stocks are shown for gaining high quality of them and availability when they are in operation. This study is for estimating number of high speed train-sets that would be supplementarily placed an order through verification of RAM goals of a project for the introduction of KTX-II 100 cars. It verify that optimized requirements for high speed rolling stocks by relatively comparison with between requirements for train-sets through setting RAM goals and requirements for train-sets through analysis of prospects for management balance with high speed rolling stocks.