• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.08a
• /
• pp.27-36
• /
• 1999

To have high flatness quality of hot rolled strip in the hot strip finishing mill train, a new inter-stand tension profile measuring device of segmented looper roll type(coined as Flatness Sensing Inter-stand Looper, FlatSIL) and a new flatness control system have been developed in this study. The device measures the strip tension profile across the strip width and informs the strip wave pattern to new flatness control system where work roll bending mode to relieve the strip wave is determined. The existing automatic shape control system which uses laser type shape-meter installed at the outlet of the last finishing mill stand strip tension between down coiler and last finishig mill since the latent wave concealed by the strip tension between down coiler and last finishing mill stand cannot be measured by the laser distance-meter. Thus the existing shape control system is not able to control the flatness through the full strip length. The new flatness control system, however, works for full strip length during strip rolling as far as the tension profile measuring device and work roll bender are on. With the new flatness control system, work roll bender is automatically controller to minimize the latent wave of the running strip and the flatness quality as well as strip travelling stability has been noticeably improved from strip head through body to tail.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.05a
• /
• pp.223-225
• /
• 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.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.826-831
• /
• 2004

In this study. problems caused during production process of stainless steel carbody are investigated and solutions are found out. Roll forming process to make complex shape is introduced and surface crack on high strength stainless steel plate is investigated. Also, surface indentation is discussed and the effect of welding condition is clarified. Insulated tip to reduce the indentation is recommended for improvement of surface smoothness. Lastly. corrosion of welded joint is discussed and the effects of material, stress and environment are investigated.

• Tribology and Lubricants
• /
• v.11 no.3
• /
• pp.31-39
• /
• 1995

Grease thermal elastohydrodynamic lubrication (TEHL) problems of line contacts are analyzed numerically. The effects of temperature and rheological paraineters on grease TEHL are investigated using the Herschel-Bulkley model as a theological model of greases. The pressure distribution, the shape of grease film, mean film temperature and surface temperature of solid wall in line contacts are obtained. It is found that thermal effects on the minimum film thickness become remarkable at high rolling speeds. The effect of yield stress of Herschel-Bulkley model on minimum film thickness is negligible, while the theological index and viscosity parameter have significant effects on minimum film thickness.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.169-169
• /
• 2000

The modeling for the looper of a hot strip finishing mill to control the tension of the strip is presented. The looper is an arm pushing against the strip between stands in a tandem mill to keep the strip tension constant and to isolate the interactions of the adjacent stands. Tension is influenced by the difference in mass flow through the up stream and down-stream rolling stands. Tension is critical to strip quality, influencing width, gauge, and shape. This paper presents how looper angle and strip tension are controlled for a hot strip finishing mill.

• Journal of the Korean Society for Heat Treatment
• /
• v.3 no.1
• /
• pp.34-41
• /
• 1990

Effects of grain size and cold rolling degree on shape memory ability and transformation temperature were studied in Fe-35% Mn-6% Si shape memory alloy. Md point of the alloy was determined by variation of yield stress with test temperature. The Md point measured in this way was linearly increased with increasing grain size. Shape memory ability of the alloy was decreased with increasing grain size, showing a minimum value at around $63{\mu}m$, and then increased with increasing grain size. From this result, it was concluded that the shape memory ability in the grain size smaller than a critical value is controlled by amount of retained ${\gamma}$ and prior ${\varepsilon}$ phase, but that the shape memory ability in the grain size greater than the critical value is mainly dominated by grain boundary area in unit volume of parent phase. The shape memory ability was decreased with increasing deformation degree. This was because the ${\gamma}$ content being available for the formation of ${\varepsilon}$ martensite during bending was decreased with increasing deformation degree.

• Tribology and Lubricants
• /
• v.21 no.6
• /
• pp.272-277
• /
• 2005

Continuously variable transmission (CVT) of toroidal type has a elliptical shape of contact zone under the elastohydrodynamic lubrication (EHL) condition, where the power is transmitted only by shearing the lubricant. Due to the small contact area of elliptical shape, the traction of the shear behaviors of lubricant over the contact zone is under extremely high contact pressure over 1.0GPa. During the power transmission by shearing the fluid, many kinds of mechanical movements occur such as squeezing, sliding, rolling and spin. Among the movements, the spin effect that is the most undesirable contact behavior in transmitting the power frequently makes significant abnormal wear damage. In this work, the analysis of elliptical contact of EHL with spin effect is performed, which will give very useful information to understand the traction behaviors in toroidal type of CVT system.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.748-753
• /
• 2004

Aluminum alloy is very useful material for high speed transportations due to its high strength and light weight characteristics. Especially because of a weight reduction a large extrustion of aluminum alloy carbody has been manufactured. This aluminum extruded panel is a hallow extruded panel. This shape and thickness is various by designer's sense and experience and VAW's profiles. So it is important to find an optimized shape and thickness of AEP. In this study we get the AEP's thickness to minimize a weight by applying an applying an optimization algorithm. The results of the study can be used as basic guidelines double-deck trains in the future.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.2
• /
• pp.257-266
• /
• 1993

Computer Simulation based of divided element method was done to predict strip shape in20-high Sendzimir Mill and has been used to find a way for preventing quarter waves occurring in the wide and thin gaged strip rolling. The simulation showed that it was difficult to prevent quarter waves by the existing methods of controlling actuators such as the shifting of the first intermediate roll and the profile control of As-U-Roll in back up roll. It was, however, confirmed analytically and experimentally that quarter waves could be effectively reduce by changing taper mode at the barrel-end taper radius of the first intermediate roll.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.5 s.176
• /
• pp.1238-1245
• /
• 2000

One of the main causes of severe wear or crack initiation in wheel and rail is the contact stress due to wheel-rail contact. First, we obtain contact stress due to the rail mounting slope using the finite element method. Second, the shape design based on more reasonable contact stress analysis rather th~n a general Hertzian contact theory is investigated in order to reduce the contact stress. The optimum -design is performed using the simple 2-D finite element model and its results are verified by 311) finite element analysis.