Xian-lei Hu

Horizontal Velocity of Variable Gauge Rolling: Theory and Finite Elements Simulation

Within the production chain of longitudinal profiled (LP) plates and tailor rolled blanks (TRB), variable gauge rolling (VGR) represents the vital important forming stage, in which shape and properties are tailored to satisfy customers’ requirements. It is of vital importance to reveal the relationship between work-piece horizontal velocity and roll vertical velocity during VGR, which is not only a key point to understand the deformation law, but also an important content for setting VGR process parameters. It is proved that the simplified assumption of equal discharge per second condition (EDSC) breaks down during VGR. Due to this reason the differential equation of the work-piece horizontal velocity (VGR-V) is performed by keeping the material volume constant. To attain a comprehensive understanding of this underlying process in detail, numerical approaches based on finite elements method have been performed by utilizing the Abaqus Explicit. Rolling experiment is carried out which indicates that the numerical result coincides with the experimental result well. A fine spatial discretization of work-piece is essential for special emphasis has to be put on detecting different horizontal velocity of work-piece cross section, often leading to a hundred thousand degrees of freedom even for plane strain calculations. The data obtained by using Abaqus Explicit coincide with the results determined by theory. A theoretical basis on deformation parameters and mechanical parameters during VGR process is provided.

Long- and Short-Term Self-Learning Models of Rolling Force in Rolling Process Without Gaugemeter of Plate

Owing to a lack of gaugemeter and the variety of steel grades and standards in some plate mills, the long-and short-term self-learning models of rolling force based on gauge soft-measuring with high precision were brought up. The soft-measuring method and target value locked method were used in these models to confirm the actual exit gauge of passes, and thick layer division and exponential smoothing method were used to dispose the deformation resistance parameter, which could be calculated from the actual data of the rolling process. The correlative mathematical methods can also be adapted to self-learning with gaugemeter. The models were applied to the process control system of AGC (automatic gauge control) reconstruction on 2 800 mm finishing mill of Anyang steel and favorable effect was obtained.

Residual Curvature of Longitudinal Profile Plate Roller in Leveling Process

Roller leveling process of longitudinal profile (LP) plate is hardly studied because plate thickness changes. Deformation characteristics and residual curvature during LP plate leveling process were investigated based on curvature integral by elastic-plastic differences. It was found that entry intermesh section is reduced with increasing thickness and entry intermesh should be from 0. 7 to 1.1 mm for LP plate with 42/54 mm in thickness. In order to get cshould be selected and exit intermesh should be 0 mm. In addition, thickness section for LP plate which can be leveled by 11 roller leveler is from 24 to 60 mm. Finally, there is an intermesh schedule that could level LP plate with initial curvature less than elastic limit curvature.

Application of Temperature Inference Method Based on Soft Sensor Technique to Plate Production Process

There is a certain extent of measuring error for each pyrometer in plate production process, which has a great impact on process control system. A soft sensor technique is used to calculate the confidence interval of measuring temperature data from pyrometers and an inference estimator is designed by partial least square method, then the pyrometer with highest confidence is considered as the reference one, with which inference estimation for measured data on-line of other pyrometers is started and the measuring error is conformed. From actual application it can be found that this method can improve the measuring accuracy by 3% — 5 %, and has high field application value.

Analysis of Process Control Model of Plate MAS Rolling

Using the identification quantity to identify the long ear disfigurement was brought up, and by calculation, it can be found that identification quantity should be set as the quantity of long ear disfigurement of the position which is about 0.2 times of plate width to the plate border. Conception of plate head tiny cell was brought up, and the long ear disfigurement was uncoupled into the product of elongation percentage and length of tiny cell. On the basis of prediction of long ear disfigurement, process control model of MAS rolling was built up, and application indicates that it can fit the on-line production and eliminate the long ear disfigurement commendably.

Forward and Backward Slip Models in MAS Rolling Process and Its On-Line Application

Based on the MAS rolling process in plate mill, the mathematical models of forward and backward slips of the wedges at plate head and tail were derived. According to the new model, the difference between the forward slip of the wedge and that of the normal part of the plate is obviously very small. The deviation is less than 2. 5% in general. Thus, in actual application, the forward slip of normal part of the plate can be used to calculate the length of rolled plate instead of the derived model. The rationality of this simplified method was confirmed with the application in Shougang 3 500 mm plate mill. The test results showed that the wedges of plate head and tail are symmetrical. The plate width deviation is greatly decreased by using the MAS method.

Application of Adaptive Threading Technique to Hot Strip Mill

Thickness deviation of hot strip rolling needs to be strictly controlled in the computer system. An adaptive threading technique was researched, in which the measured data from threaded stands were used to predict thickness and material hardness errors, to modify the setup for the remaining unthreaded stands. After the adaptive threading model was used online on the hot strip mill of the Panzhihua Iron and Steel Group Co Ltd, the thickness deviation was decreased obviously. The hit rate of thickness control of different steel grades increases.

Derivation of Simplified Models of Plan View Pattern Control Function for Plate Mill

The plan view pattern control theoretical models were simplified. Under the condition of constant volume for the plan view pattern compensation, the relation between the thickness and the length can be simplified to the linearity in the segment for the plan view pattern control function. The compensation volume can be dispersed for easy calculation. By comparing the model calculation result with the actual result, it was concluded that the simplified model can be used for the online control process.