Coupled Dynamic Modeling of Rolls Model and Metal Model for Four High Mill Based on Strip Crown Control

The crown is a key quality index of strip and plate, the rolling mill system is a complex nonlinear system, the strip qualities are directly affected by the dynamic characteristics of the rolling mil. At present, the studies about the dynamic modeling of the rolling mill system mainly focus on the dynamic simulation for the strip thickness control system, the dynamic characteristics of the strip along the width direction and that of the rolls along axial direction are not considered. In order to study the dynamic changes of strip crown in the roiling process, the dynamic simulation model based on strip crown control is established. The work roll and backup roll are considered as elastic continuous bodies and the work roll and backup roll are joined by a Winkler elastic layer. The rolls are considered as double freely supported beams. The change rate of roll gap is taken into consideration in the metal deformation, based on the principle of dynamic conservation of material flow, the two dimensional dynamic model of metal is established. The model of metal deformation provides exciting force for the rolls dynamic model, and the roils dynamic model and metal deformation model couple together. Then, based on the two models, the dynamic model of rolling mill system based on strip crown control is established. The Newmark-13 method is used to solve the problem, and the dynamic changes of these parameters are obtained as follows： （1） The bending of work roll and backup roll changes with time; （2） The strip crown changes with time; （3） The distribution of rolling force changes with time. Take some cold tandem rolling mill as subject investigated, simulation results and the comparisons with experimental results show that the dynamic model built is rational and correct. The proposed research provides effective theory for optimization of device and technological parameters and development of new technology, plays an important role to improve the strip control precision and strip shape quality.

A High-Resolution Modeling Study of the 19 June 2002 Convective Initiation Case during IHOP 2002:Localized Forcing by Horizontal Convective Rolls

The initiation processes of one of the initial convective cells near and on the east side of a dryline on 19 June 2002 during the IHOP 2002 field experiment in the central United States is analyzed in detail based on a high-resolution numerical simulation. Prominent horizontal convective rolls and associated near-surface moisture convergence bands [called roll convergence bands(RCBs) here] develop within the convective boundary layer(CBL) due to surface heating, in the hours leading to convective initiation(CI). The RCBs east of the dryline are advected toward the primary dryline convergence boundary(PDCB) by the southerly moist flow as the CBL deepens with time. Backward trajectories of air parcels forming the initial precipitating updraft of the convective cell are found to primarily originate at about 1–1.5 km above ground, within the upper portion of the shallower CBL earlier on. The representative air parcel is found to follow and stay on top of a surface RCB as the RCB moves toward the PDCB, but the RCB forcing alone is not enough to initiate convection. As this RCB gets close to the PDCB, it moves into a zone of mesoscale convergence and a deeper CBL that exhibits an upward moisture bulge associated with the PDCB. The combined upward forcing of the RCB and the mesoscale PDCB convergence quickly lifts the representative air parcel above its level of free convection to initiate convection. A conceptual model summarizing the CI processes is proposed.

High-speed steel rolls used for cold rolling

During cold rolled production of steel, each change of rolls causes a halt in production and affects the roll＇ s grinding maintenance and consumption. Consequently,rolls are very critical to the costs of steel production. Besides the rolling accidents, surface quality problems, including inhomogeneous wear and a decrease of the surface roughness of the rolls are other main reasons for outage and a change of the rolls. Therefore, safe rolls, with superior wear resistance and roughness retentivity will be a future trend in the cold rolling steel industry. In this study, the property characteristics and in-service performance of high-speed steel （HSS） cold rolling work rolls at Baosteel are discussed. The results of this study indicate that in-service performance of HSS cold work rolls has an improvement over conventional rolls. Implementation of HSS work rolls will prolong the rolling campaign and improve the rolling stability, thus, the cost of cold rolling production can be better controlled.

Test and analysis of mechanism and influential elements of axial drifting of weldment on turning rolls

The mechanism of axial drifting of weldment on welding turning rolls was investigated. The simulation test for influential element has been carried out as well. The results show that axial drifting is caused by unparallel between the axis of roller and weldment resulting in axial force. When the helical angle λ between rolls and weldment is from 1°to 6°, the tanλ is linearly related to axial drifting speed v. Increase of number of deflected rollers causes non linear increase of v. The angle of λ makes more effect on speed v than what the angle of deflection does. The turning speed of weldment is proportion to axial drifting speed v. The dead weight of weldment has little effect on speed v.

Analysis of surface cracking in water-cooled rolls and heat transfer between furnace chamber and rolls in a direct flame furnace

In the direct fired furnace of a continuous annealing line, seal rolls are susceptible to deformation that leads to surface defects of steel strips. According to failure analysis, the reasons include improper structural design and heat imbalance. An improved design has been proposed to reduce stress concentration and thermal radiation. A heat transfer model has been employed to determine the proper water flow rate for roll cooling. Industrial application proves that seal rolls with the new design has less deformation and longer service life.

THE INTEGRAL AS A FUNCTlON OF THE UPPER LIMIT AND DEPENDING ON A PARAMETER TO SOLVE DRAWING THROUGH IDLING ROLLS

The relocity and sirain-rate .field which are different from Avilzur's have beenestablished in Caitesian coordinates. Using the integral as a function of the upper limitand integration depending on a parameler, an analylical upper-bound solution todrawing stress through idling rolls has been obtained in this paper.

ZTE Rolls Out a Series of Industry's First TD-SCDMA Handset Products at PT/WIRELESS & NETWORKS COMM CHINA 2007

ZTE Corporation (ZTE), a leading global provider of telecommunications equipment and network solutions, unveiled

ZTE Rolls Out New Unified Open Environment Platform

ZTE Corporation (ZTE),a leading global provider of telecommunications equipment and network solutions,on February 12,2009,released a unique Unified Open Environment (UOE) platform that will make it easier fortelecom operators

ZTE Rolls Out the First Full-Scale BBU+RRU Solution in the Industry

August 7,2007,Shenzhen,China-ZTE Corporation ("ZTE"),a leading global provider of telecommunications equipment and network solutions,announced today the official launch of its GSM BBU+RRU Solution

Crisp Fried Beef Rolls(Xiangsu Niuroujuan)

300 grams ground beef 350 grams bread crumbs 2 eggs1 gram MSG2 grams salt10 grams (1 tbsp) cooking wine5 grams chopped spring onion5 grams chopped ginger10 grams (1 tbsp) cornslarch300 grams (3/5 cup) cooking oilMix ground beef with salt, MSG, cooking wine. chopped spring onion and ginger, and 5 grams of cornslarch. Beat eggs in a bowl.Make ground beef into three rolls, about 5 cm in diameter and 15 cm long. Place on a plate and steam until cooked. Coat the rolls in beaten egg and then in breadcrumbs.Heat oil in a wok. fry the rolls until brown. Cut the meat rolls into 3-cm sections, arrange on a plate, and serve.

百年飞天 奢华依旧 劳斯莱斯(Rolls Royce)

劳斯莱斯,车坛中的贵族,四轮的皇者。从诞生之日起就注定拥有高人一等的血统。无论你是否喜欢劳斯莱斯老气的造型,它终究是身份与地位的象征。

Trouble Increases as Tire Rolls

Background President Obama will soon be required to decide whether to impose quotas or other restrictions against imports of passenger and light truck tires from China.

Influence of Rare Earth Elements on Microstructure and Mechanical Properties of Cast High-Speed Steel Rolls

The influence of rare earth （RE） elements on the solidification process and eutectic transformation and mechanical properties of the high-V type cast, high-speed steel roll was studied. Test materials with different RE additions were prepared on a horizontal centrifugal casting machine. The solidification process, eutectic structure transformation, carbide morphology, and the elements present, were all investigated by means of differential scanning calorimetry （DSC） and scanning electron microscopy energy dispersive spectrometry （SEM-EDS）. The energy produced by crack initiation and crack extension was analyzed using a digital impact test machine. It was found that rare earth elements increased the tensile strength of the steel by inducing crystallization of earlier eutectic γ-Fe during the solidification process, which in turn increased the solidification temperature and thinned the dendritic grains. Rare earth elements with large atomic radius changed the lattice parameters of the MC carbide by forming rare earth carbides. This had the effect of dispersing longpole M C carbides to provide carbide grains, thereby, reducing the formation of the gross carbide and making more V available, to increase the secondary hardening process and improve the hardness level. The presence of rare earth elements in the steel raised the impact toughness by changing the mechanism of MC carbide formation, thereby increasing the crack initiation energy.

Comprehensive contour prediction model of work rolls in hot wide strip mill

The predictive calculation of comprehensive contour of work rolls in the on-line strip shape control model during hot rolling consists of two important parts of wear contour calculation and thermal contour calculation, which have a direct influence on the ac- curacy of shape control. A statistical wear model and a finite difference thermal contour model of work rolls were described. The comprehensive contour is the equivalence treatment of the sum of grinding, wear, and thermal contours. This comprehensive contour calculation model has been applied successfully in the real on-line strip shape control model. Its high precision has been proved through the large amounts of actual roll profile measurements and theoretical analyses. The hit rates （percent of shape index satisfying re- quirement） of crown and head flatness of the strips rolled, by using the shape control model, which includes the comprehensive contour calculation model, have about 16% and 10% increase respectively, compared to those of strips rolled by using manual operation.

Analysis of the thermal profile of work rolls in the hot strip rolling process

A 2-dimension axisymmetric model was developed by the finite-differencemethod, which can be used to predict the transient temperature field and thermal profile of workrolls in the hot strip rolling process. To demonstrate the accuracy and reliability of the solutiondeveloped, the calculation results were compared with the production data of a 1700 mm hot striprolling mill and good agreement was found between them. The effect of strip width and roll shiftingon the thermal expansion of the work rolls was studied. It is found that the strip width has markedeffect on the efficient thermal crown. Initially, when the rolling strip changes from narrow towide, a bigger efficient thermal crown can be quickly achieved; afterwards, when the rolling stripchanges from wide to narrow, not only the influence of uneven wear can be reduced but also theexcessive efficient thermal crown can be avoided. It is also found that the work roll shifting has adeterminate but not obvious effect on the reduction of the efficient thermal crown, and will makethe strip shape unstable without being used properly.

Gauge-meter model building based on the effect of elastic deformation of rolls in a plate mill

The calculation error of the gauge-meter model will affect the gap setting precision and the self-learn precision of rolling force. The precision of the gauge-meter model is strongly influenced by plate width, working roll radius, backup roll radius, working roll crown, backup roll crown, and rolling force. The influence rules are hard to get by measuring. Taking a conventional 4-h plate mill as the research subject, these influences were transferred into the calculation of roll deflection and flattening deformation. To calculate these deformations, the theory of the influence function method was adopted. By modifying the traditional gauge-meter model, a novel model of the effect of roll elastic deformation on the gap setting was built by data fitting. By this model, it was convenient to analyze the variation caused by the rolling condition. Combining the elastic deformation model of rolls with the kiss-rolls method, a gauge-meter model was put forward for plate thickness prediction. The prediction precision of thickness was greatly improved by the new gauge- meter model.

Thermal spray coating on conductor rolls in electroplating line

In electroplating lines,many conductor rolls are installed in electroplating bath.Typical electroplatings are tin plating(ETL) and zinc plating(EGL),and from required product qualities,a vertical cell for the former and a horizontal cell for the latter is often used.Generally,chrome plating or WC cermet thermal spray coating is applied to stainless steel conductor roll in ETL for prolonging service life by improvement of wear resistance and corrosion resistance.On the other hand,Hastelloy type alloy substrate is used for conductor rolls in EGL due to severe corrosion environment of electro plating solution.Thermal spray coating is effective for reducing wear,but there are many cases where the coating cannot complete expected service life when corrosion becomes an issue.In this study,thermal spray coating for ETL conductor roll and development of the coating for EGL conductor roll to meet expected service life are described.