Three-Di mensional Model for Strip Hot Rolling

A three-dimensional model for strip hot rolling was developed, in which the plastic deformation of strip, the thermal crown of rolls, roll deflection and flattening were calculated by rigid-plastic finite element method, finite difference method, influential function method and elastic finite element method respectively. The roll wear was taken into consideration. The model can provide detailed information such as rolling pressure distribution, contact pressure distribution between backup rolls and work rolls, deflection and flattening of work rolls, lateral distribution of strip thickness, and lateral distribution of front and back tensions. The finish rolling on a 1 450 mm hot strip mill was simulated.

Cast-rolling force model in solid-liquid cast-rolling bonding(SLCRB) process for fabricating bimetal clad strips

Based on twin-roll casting, a cast-rolling force model was proposed to predict the rolling force in the bimetal solid-liquid cast-rolling bonding(SLCRB) process. The solid-liquid bonding zone was assumed to be below the kiss point(KP). The deformation resistance of the liquid zone was ignored. Then, the calculation model was derived. A 2D thermal-flow coupled simulation was established to provide a basis for the parameters in the model, and then the rolling forces of the Cu/Al clad strip at different rolling speeds were calculated. Meanwhile, through measurement experiments, the accuracy of the model was verified. The influence of the rolling speed, the substrate strip thickness, and the material on the rolling force was obtained. The results indicate that the rolling force decreases with the increase of the rolling speed and increases with the increase of the thickness and thermal conductivity of the substrate strip. The rolling force is closely related to the KP height. Therefore, the formulation of reasonable process parameters to control the KP height is of great significance to the stability of cast-rolling forming.

Recrystallization model for hot-rolling of 5182 aluminum alloy

A recrystallization model for hot rolling of 5182 aluminum alloy was presented by means of the fractional softening during double interval deformation. It is found that the recrystallization rate depends on strain rate more sensitively than deformation temperature, and the time for full recrystallization is very short as strain rate is greater than 1?s -1 . Using the recrystallization—time—temperature curves, the desirable hot rolled microstructure can be obtained by controlling the rolling speed, temperature and cooling rate before cooling during the last pass in reversing mill.[

Mathematic model of rolling pressure during a semisolid shearing-rolling process

A mathematic model of rolling pressure during a novel semisolid shearing-rolling process was established. The rolling pressure in this process is higher than that in the conventional rolling. The increment of rolling pressure in the backward slip zone is higher than that in the forward slip zone, and the neutral plane moves toward to the roll gap entrance. The maximum and the average rolling pressures increase with the decrease of strip thickness, and the effects of strip thickness on the rolling pressure is more obvious in the forward slip zone than in the backward slip zone. Meanwhile, the neutral plane moves toward the roll gap exit with the decrease of strip thickness. The maximum and average rolling pressures increase with the decrease of strip width, and the strip width affects the pressure more obviously in the backward slip zone than in the forward slip zone. At the same time, the neutral plane moves toward the roll gap entrance with the decrease of strip width. The maximum and average rolling pressures increase with increasing roll radius, and the neutral plane moves toward the roll gap exit.

Establishment of mathematical moment model in twin casting rolling rolls

In continuous casting rolling process, the deformed body is different from the hot rolling strip. The metal in casting rolling zone is first assumed to be viscous fluid and the mathematical model of casting rolling force is established, then the calculating formula for casting rolling torque is derived. In addition, considering the effects of deforming cone and appendant torque of rotary junctions sealing ring, the calculating model which accords with casting rolling condition is found out. Theoretical formula is proved by experiment.

Modeling for driving systems of four-high rolling mill

A modeling method for driving systems of four high rolling mill was put forward in order to analyze the origin of rolling mill’s chatter that brings about light and shade streaks on the surface of steel strip from aspect of electromechanical coupling. The process and steps of modeling method was introduced by means of an example. The correctness of the model and the feasibility of the modeling method were verified in simulation experiment.

TIN_DDM Buffer Surface Construction Algorithm Based on Rolling Ball Acceleration Optimization Model

In view of the TIN_DDM buffer surface existing in the construction and application of special data type,algorithm efficiency and precision are not matching;the paper applied the rolling ball model in the process of TIN_DDM buffer surface construction.Based on the precision limitation analysis of rolling ball model,the overall precision control method of rolling ball model has been established.Considering the efficiency requirement of TIN_DDM buffer surface construction,the influence principle of key sampling points and rolling ball radius to TIN_DDM buffer surface construction efficiency has been elaborated,and the rule of identifying key sampling points has also been designed.Afterwards,by erecting the numerical relationship between key sampling points and rolling ball radius,a TIN_DDM buffer surface construction algorithm based on rolling ball acceleration optimization model has been brought forward.The time complexity of the algorithm is O(n).The experiments show that the algorithm could realize the TIN_DDM buffer surface construction with high efficiency,and the algorithm precision is controlled with in 2σ.

Modeling of the Shape Forming of Composite Roll

A shape modeling of spray formed composite roll, which is utilized to predict the shape and dimension of roll during spray forming process, is developed in this paper. The influences of the principal spray forming parameters, such as the spatial distribution of melt mass flux, spray distance, rotating and translating speeds of substrate bar etc. , on the geometry and dimension of spray formed product were investigated.

Work roll thermal contour prediction model of nonoriented electrical steel sheets in hot strip mills

The demands for profile and flatness of nonoriented electrical steels are becoming more and more severe. The temperature field and thermal contour of work rolls are the key factors that affect the profile and flatness control in the finishing trains of the hot rolling. A theoretic mathematical model was built by a two-dimensional finite difference to calculate the temperature field and thermal contour at any time within the entire rolling campaign in the hot rolling process. To improve the calculating speed and precision, some special solutions were introduced, including the development of this model, the simplification of boundary conditions, the computation of heat transfer coefficient, and the narrower mesh along the edge of the strip. The effects of rolling pace and work roll shifting on the temperature field and thermal contour of work rolls in the hot rolling process were demonstrated. The calculated results of the prediction model are in good agreement with the measured ones and can be applied to guiding profile and flatness control of nonoriented electrical steel sheets in hot strip mills.

KDD-based rolling schedule model for plate mill

A novel method for generating a rolling schedule is presented, which is fundamentally different from the existing ones. KDD (knowledge discovery in database) techniques are applied for discovering association rules between rolling parameters in a large database of rolling operation, and based on these rules, the schedule for the crucial last six finishing passes is generated. Operational evaluation shows that the schedule generated by the new method outperforms that generated by existing methods. It also shows how in this application the human's domain knowledge is applied to speed up the KDD process and to ensure the validity of the knowledge discovered.

Water Modeling of Twin-Roll Strip Casting

Twin-roll strip casting is regarded as a prospective technology of near net shape continuous casting. The fluid flow field and level fluctuation in the pool have a strong influence not only on composition and temperature homogeneity of pool, but also on the strip quality. A 1 ： 1 water model of a twin-roll strip caster was set up based on the criteria of Froude number and Reynold number similarity. The level fluctuation was measured. The influence of pool depth, casting speed and feeding system configuration on level fluctuation in the pool was studied. The experimental results provided a basis for the optimization of feeding system and process parameters.

Model of Aluminium Foil Rolling Force Based on Neural Networks

Based on the principle of BP neural networks, the rolling force model is established after thoroughly analyzing and reprocessing the data of 1 350 mm aluminium foil mill. It states that the difference between the output of artificial neural networks rolling force model and the real value is in the order of 3 percent. The model reflects the real feature of process.

Self-Learning and Its Application to Laminar Cooling Model of Hot Rolled Strip

The mathematical model for online controlling hot rolled steel cooling on run-out table （ROT for abbreviation） was analyzed, and water cooling is found to be the main cooling mode for hot rolled steel. The calculation of the drop in strip temperature by both water cooling and air cooling is summed up to obtain the change of heat transfer coefficient. It is found that the learning coefficient of heat transfer coefficient is the kernel coefficient of coiler temperature control （CTC） model tuning. To decrease the deviation between the calculated steel temperature and the measured one at coiler entrance, a laminar cooling control self-learning strategy is used. Using the data acquired in the field, the results of the self-learning model used in the field were analyzed. The analyzed results show that the self-learning function is effective.

MODELING OF CONTROLLED THERMO-MECHANICAL PROCESSING OF TUBES FOR ENHANCED MANUFACTURING AND PERFORMANCE

An integrated mathematical model to simulate seamless tube rolling processes has been developed at The Timken Company. The model is capable of simulating the thermal, deformation and microstructure evolution in the piercing, elongating and reducing/sizing and the austenite decomposition in the mill annealing and cooling operations. Finite difference schemes are employed to model cooling, reducing/sizing and stretch reducing, and finite-element schemes are employed to simulate piercing and elongating. The model predicts the thermal history, deformation, rolling load, torque, recrystallization and grain growth in hot tube rolling, austenite decomposition in cooling or annealing, and the final structure-properties. In this paper mathematical models which are employed to describe the thermal, deformation and microstructure evolution along with the modeling results are presented. The developed 'tube rolling mill in the computer' provides a powerful tool for engineers for product and process development, process control, process optimization and quality control.

Experimental Study and Finite Element Polycrystal Model Simulation of the Cold Rolling Textures in a Powder Metallurgy Processed Pure Aluminum Plate

Ingot metallurgy (IM) aluminum has long been the subject and attracted the attention of many metallurgists and textural researchers of materials. Due to the introduction of large amounts of ex situ interfaces, however, the textures in powder metallurgy (PM) processed aluminum has been rarely reported. In this article, a pure aluminum plate was prepared via PM route. The starting billet was first produced with uni-axially cold compaction and flat hot-extrusion and then followed by cold rolling processes. The hot-extruded and cold rolling deformation textures of the pure PM aluminum at 50%, 80% and 90% cold rolling reductions were studied by orientation distribution functions (ODFs) analysis. The finite element polycrystal model (FEPM) was finally utilized to simulate the cold rolling textural evolution at various stages of cold rolling. In FEPM simulation, the initial hot-extruded textures were taken into account as inputs. The results showed that typical β-fiber texture formed in pure PM aluminum with the cold rolling reduction increased till 80%, and there was not much change after excessive cold rolling deformation. Homogeneous slip is not the only deformation mode in PM processed pure aluminum plate at over 80% cold rolling reduction. The experimental results were qualitatively in good agreement with the simulated ones.

Force Parameter Model of 3-Roll Mills for Continuous Cold Rolling Wires

Based on experimental data, the mathematical model of rolling force parameters of 3-roll mills was studied. The structure ofthe model was theoretically set up and the coefficients were determined by static analysis of the data. The torque in continuous rollingwas measured, and the characteristics and efficiency of 3-roll mills are investigated.

Roll System and Stock's Multi-parameter Coupling Dynamic Modeling Based on the Shape Control of Steel Strip

The existence of rolling deformation area in the rolling mill system is the main characteristic which dis- tinguishes the other machinery. In order to analyze the dynamic property of roll system＇s flexural deformation, it is necessary to consider the transverse periodic movement of stock in the rolling deformation area which is caused by the flexural deformation movement of roll system simul- taneously. Therefore, the displacement field of roll system and flow of metal in the deformation area is described by kinematic analysis in the dynamic system. Through intro- ducing the lateral displacement function of metal in the deformation area, the dynamic variation of per unit width rolling force can be determined at the same time. Then the coupling law caused by the co-effect of rigid movement and flexural deformation of the system structural elements is determined. Furthermore, a multi-parameter coupling dynamic model of the roll system and stock is established by the principle of virtual work. More explicitly, the cou- pled motion modal analysis was made for the roll system. Meanwhile, the analytical solutions for the flexural defor- mation movement＇s mode shape functions of rolls are discussed. In addition, the dynamic characteristic of the lateral flow of metal in the rolling deformation area has been analyzed at the same time. The establishment ofdynamic lateral displacement function of metal in the deformation area makes the foundation for analyzing the coupling law between roll system and rolling deformation area, and provides a theoretical basis for the realization of the dynamic shape control of steel strip.

A Cumulative Damage Reliability Model on the Basis of Contact Fatigue of the Rolling Bearing

A cumulative damage reliability model of contact fatigue of the rolling bearing is more identical with the actual conditions. It is put forward on the basis of contact fatigue life probability distribution of the rolling bearing that obey Weibull distribution and rest on the Miner cumulative damage theory. Finally a case is given to predict the reliability of bearing roller by using these models.

Modelling of Microstructural Evolution and Prediction of Mechanical Properties of Plain Carbon Strip Steel in Hot Rolling Process

Based on hot rolling production line of strip steel, the off-line in-house software, termed as ROLLAN (Rolling Analysis), is developed. The code is mainly used to predict the evolution of temperature, rolling force, fraction and grain size of recrystallization, fraction and grain size of phase transformation and final mechanical properties. Almost all the processing parameters affecting microstructure and mechanical properties in the schedule from reheating to the coiling process are considered in detail. Self-learning coefficient is adopted to adjust the deviation between predicted and measured temperatures, such as roughing exit temperature (RT2), finishing exit temperature (FT7) and coiling temperature (CT). Due to the application of low-speed-threading, increasing-speed-rolling and decreasing-speed-delivery process during finishing rolling and different cooling condition, after coiling the thermal-mechanical history of different position, along strip longitudinal direction is different resulting in inhomogeneous mechanical properties. So the segments are divided along longitudinal direction to identify the variation of microstructure and mechanical properties. An example of plain carbon strip steel Q235 with various thickness is used to compare the calculated mechanical properties with measured ones. For the specific grade of Q235 , the maximum deviation of tensile strength is less than 10.3 MPa, the yield strength is less than 13.2 MPa, and elongation is less than 1.99%. Further work will focus on the on-line application and consider the effect of macrosegregation and sulfur content of cast slab.

The finite element analysis of articular cartilage fiber-reinforced composite model under rolling load

Articular cartilage is a layer of low-friction,load-bearing soft hydrated tissue covering bone-ends in diarthrosis,which plays an important role in spreading the load,reducing the joint contact stress,joint friction and wear during exercise.The vital mechanical function