Mechanics of design and model development of CVC-plus roll curve

The mathematic model of CVC-Plus work roll curve is built. The ratio of the initial shifting value to the target crown is determined, and the mathematical model considering the relationship between the coefficients A2, A3, A4, A5 and is established. According to the theoretical analysis, the distance between the maximum or minimum point of the high order equivalent crown for work roll with CVC-plus roll curve and the rolling central point is the times of the roll barrel length. In general, the initial shifting value of the CVC-plus roll curve is not equal to the initial shifting value of the 3-order CVC roll curve . The coefficient A1 can also be obtained by optimizing the target function with minimizing the axial force

Study on surface asperity flattening in cold quasi-static uniaxial planar compression by crystal plasticity finite element method

In order to study the surface asperity flattening in a quasi-static cold uniaxial planar compression, the experimental results of atomic force microscope and electron backscattered diffraction have been employed in a ratedependent crystal plasticity model to analyze this process. The simulation results show a good agreement with the experimental results: in this quasi-static deformation process, lubrication can hinder the surface asperity flattening process even under very low deformation rate. However, due to the limitation of the model and some parameters, the simulation results cannot predict all the properties in detail such as S orientation {123}and the maximum stress in sample compressed without lubrication. In addition, the experimental results show, with an increase in gauged reduction, the development of Taylor factor, and CSL boundaries show certain tendencies. Under the same gauged reduction, friction can increase the Taylor factor and Σ = 7

Setup Models of Finishing Temperature and Rolling Speed for Hot Strip Mill

For the requirement of highly accurate finishing temperature control during accelerating hot strip rolling, the finishing temperature and rolling speed setup models have been successfully established. The relationship between the threading speed and finishing temperature was obtained, and a method to determine the speed, acceleration rate and high acceleration zone distance was proposed when the strip is rolled at high acceleration period using iteration calculation. A method to determine the starting and ending points of speed drop was discussed in the paper. In order to ensure the available characteristics of setup and control models, the self-learning strategies including the self-learning of the model coefficients, acceleration rate and slab temperature slope were built up in this study. According to the on-line control results of strip temperature composing of feed-forward and feed-back control models which was employed in a plant, the control accuracy of finishing temperature satisfies the requirement well

Effect of asymmetrical stand stiffness on hot rolled strip shape

The difference of elastic springs between the operating side (OS) and driving side (DS) of rolling mill has a significant influence on the strip shape not just the strip thickness. Based on the slit beam and roll deformation theories, the roll force distribution was analysed considering the asymmetric stiffness of the OS and DS of rolling mill, and the work roll and backup roll deformation equations were deduced respectively, and the thickness distribution in lateral direction of the hot rolled strip at exit was discussed. Using the roll elastic deformation analysis software which was developed previously based on the influence coefficient method, the roll flattening distribution, roll pressure distribution and the rolling force distribution caused by the asymmetric stand stiffness were calculated and analysed, and the exit strip profile of the rolling mill was also presented. The relationship between the mill stiffness difference and the strip wedge shape or single wave was obtained. Effect of the upstream asymmetric mill on strip crown and flatness of the downstream stands was discussed

Effect of initial crown on shape of hot rolled strip

Based on the influence coefficient method, the effect of entry strip crown on the shape of hot rolled strip was analyzed using the software of roll elastic deformation simulation. According to the practical condition of a domestic hot rolled strip plant, the unit strip crown change from the first stand to the last stand was calculated when the entry crown of hot strip varies. The calculated result shows that the entry strip crown does not significantly affect the target strip crown at the exit of the last finishing stand in respect to a fixed strip shape control reference (such as bending force). The calculation was analyzed, and the research is helpful in modeling strip shape setup and shape control

Graphene sheets encapsulating SiC nanoparticles: A roadmap towards enhancing tensile ductility of metal matrix composites

In this study, β-SiC nanoparticles were well dispersed in a matrix of aluminium making use of encapsulation capacity of graphene sheets, semi-solid stirring of the aluminium melt, ultrasonic treatment, and pressure application during solidification. A new solidification model taking into account the alteration of the solidification mechanism from particle pushing to particle engulfment, making use of at least 40% enhancement in higher thermal conductivity and diminished repelling forces of SiC nanoparticles tuned by encapsulating graphene sheets was suggested. This nanostructure manipulation can make about 350% and 258% enhancement in yield strength and tensile ductility, respectively, compared to that of unreinforced aluminum alloy. The results achieved based on the devised analytical model have shown the significant effect of thermal activated dislocation in strengthening due to considerable mismatch between thermal expansion coefficient of graphene sheets and aluminium matrix. Fractographic observations disclosed a dimple fracture surface for the semi-solid-processed aluminium matrix composite reinforced by the nanoparticles that were encapsulated by graphene sheets using ball-milling process compared with the cleavage fracture surface of those fortified without the application of graphene