Determination of Optimal Work Roll Profile for Cold Strip Mill

The model of predicting distribution of strip thickness at the exit and tension stress is established by using weighted residual method and variational method with consideration of rolled metal lateral flow.A New method of calculating loaded roll gap in relation to target tension stress is proposed.The minimum square summation of loaded roll gap deviation is used as an objective function for the first time to optimize initial work roll profile.

Roll profile electromagnetic control characteristics under roll heterogeneity

The electromagnetic control roll(ECR)and electromagnetic stick(ES)are the core elements and the main driving parts of roll profile electromagnetic control technology(RPECT).To prolong the service life,it is necessary to treat ECR and ES surfaces.According to the heterogeneous characteristics of surface treatments,the roll profile electromagnetic control characteristics were analyzed for different parameters.An electromagnetic-thermal-force coupled axisymmetric finite element model was built to explore the differences in performance as a result of several treatment strategies,and the model was verified by experimental results measured with a roll profile electromagnetic control experimental platform.This model was used to analyze the influence of the heterogeneity of ECR inner hole and ES on the roll crown,the roll profile,the average contact pressure,and the stress state during RPECT process.The results indicate that the heterogeneous layer at ECR inner hole has a restrictive effect on RPECT and that the heterogeneous layer of ES can enhance the profile control ability of RPECT.A reasonable configuration scheme between the heterogeneity of ECR inner hole and the ES can increase the life of ECR and maintain the control ability of RPECT.

Roller Profile Online Measurement Based on Ultrasonic Circulation Pulse-echo Technology

In order to meet the high precision requirement of wide steel strip in industry field, a novel online measurement of roller profile based on sonic circulation and pulse-echo technology was introduced. All kinds of the factors influencing the accuracy of roller profile online measurement were analyzed in detail and error compensation analysis of system was accordingly presented. In order to reduce count error, field program gate array(FPGA) was introduced and a highprecision data acquisition system was designed based on digital phase-shift technology. Experiments indicate that the standard deviation of measure data was 7.27 μm, which showed the feasibility and validity of the proposed method, and realized the roll profile measurement with high precision.

Thermal profile of work roll during strip hot rolling

The thermal expansion of work rolls during hot strip rolling was modeled by a two-dimensional difference method. The calculation model was validated by comparison between the predictions to the measured results. With that model ,the effects of rolling process parameters such as the rolling plan, mill pacing ,coolant flow rate and stepped cooling on the roll thermal profile were investigated. The result shows that stepped cooling of work rolls can be used to control complicated flatness defects such as quarter buckles during hot strip rolling.

Application of innovative technologies in the strip rolling mill field

Many new types of rolling mills have been studied and developed corresponding to the needs of improvement in productivity and quality.This presentation reflects back at some of the innovative technologies,which were developed by Mitsubishi-Hitachi Metals Machinery,Inc.(hereinafter referred to as M-H),including the evolution of the pair cross mill,mill stabilizing device,on-line roll profiler,shape meter for hot-rolling,endless hot-rolling, recent application of UCM,and M-H split housing type 20-high mill.

Determination of the Influence of the Speed of the Saw Cylinder of the Saw Gin on the Density, Speed and Composition of the Seed Roll

The article consists of studying the influence of the speed of the saw cylinder on the quality of the fiber and the productivity of the machine, as well as on the change in the density and composition of the seed roll.

Experimental investigation on slip conditions during thread rolling with flat dies

The process design of flat die rolling operations can be a tedious and costly process due to the challenges posed by small process windows.Within this work,an effort is made to closely investigate and understand the process limits caused by excessive slippage of the workpiece.Optical measurements are carried out to capture the characteristics of excessive slippage and the influence of the stroke rate and the tribological system on this process limit.Large differences in slippage were observed,depending on the tribological system.While systems with polymer based lubricants showed excessive slippage at low stroke rates,systems using oil or no lubricant endured higher stroke rates before process limits were reached.The optical measurements revealed three major forms of slippage:successful rolling without slippage,failure due to excessive slippage at process start,and failure due to excessive slippage at around one workpiece rotation.

Numerical simulation of wheel wear evolution for heavy haul railway

The prediction of the wheel wear is a fundamental problem in heavy haul railway. A numerical methodology is introduced to simulate the wheel wear evolution of heavy haul freight car. The methodology includes the spatial coupling dynamics of vehicle and track, the three-dimensional rolling contact analysis of wheel-rail, the Specht's material wear model, and the strategy for reproducing the actual operation conditions of railway. The freight vehicle is treated as a full 3D rigid multi-body model. Every component is built detailedly and various contact interactions between parts are accurately simulated, taking into account the real clearances. The wheel-rail rolling contact calculation is carried out based on Hertz's theory and Kalker's FASTSIM algorithm. The track model is built based on field measurements. The material loss due to wear is evaluated according to the Specht's model in which the wear coefficient varies with the wear intensity. In order to exactly reproduce the actual operating conditions of railway,dynamic simulations are performed separately for all possible track conditions and running velocities in each iterative step.Dimensionless weight coefficients are introduced that determine the ratios of different cases and are obtained through site survey. For the wheel profile updating, an adaptive step strategy based on the wear depth is introduced, which can effectively improve the reliability and stability of numerical calculation. At last, the wear evolution laws are studied by the numerical model for different wheels of heavy haul freight vehicle running in curves. The results show that the wear of the front wheelset is more serious than that of the rear wheelset for one bogie, and the difference is more obvious for the outer wheels. The wear of the outer wheels is severer than that of the inner wheels. The wear of outer wheels mainly distributes near the flange and the root; while the wear of inner wheels mainly distributes around the nominal rolling circle. For the outer wheel of front wheelset of each bogie, the development of wear is gradually concentrated on the flange and the developing speed increases continually with the increase of traveled distance.

Improvement of the Process of Separation of Cotton Fiber from Seeds

The differential equation, obtained as a result of the theoretical study of the movement of the bare seed on the surface of the grate of the saw gin, made it possible to determine the trajectory of the movement of the seed. The rib is one of the main working bodies of the saw gin. It serves for the free passage of the saw blades through it into the working chamber, for the withdrawal of the fiber caught on the saw teeth after separating it from the seed. A number of studies have been carried out to improve the working elements of the saw gin. The purpose of the research is to create the possibility of timely withdrawal of bare seeds from the working chamber of the saw gin by creating a concavity on the working surface of the grate. The use of the Euler equation for the movement of bare cotton seed along the grate contour, taking into account its speed V, density ρ, pressure P, made it possible to obtain a graph of seed distribution along the grate contour. An experimental 30-saw gin was developed and manufactured, the research carried out on it allowed to determine the rational parameters of new grates, which are recommended for introduction into production. The dependence of the location of the rectilinear part of the general contour on the shape of its convexity and concavity is determined. Based on the above equations, using separate functions, we present the view of the grate profile in the coordinate system modeled on the MAPLE-17 program.

Thermal-force control ability under variation of electromagnetic stick structure parameters in RPECT

Thermal-force driving of roll profile electromagnetic control technology(RPECT),which can be used to adjust the roll profile,can be affected by the sequential temperature rise between the electromagnetic stick(ES)and electromagnetic control roll.Due to the limited space of ES and induction coil,the cross-sectional area of induction coil can be inevitably affected by changing the size of the ES induction zone,which can further change the energy input under the same electromagnetic parameters,the temperature rising effect and the bulging ability.To investigate this phenomenon,the effects of the radius of the induction zone on the thermal-force contribution ratio,the heating ability of ES and the temperature distribution were analyzed through an electromagnetic-thermal-structural finite element model.To ensure that the results are applicable to RPECT,the thermal energy conversion ability and thermal-force roll crown control ability under different lengths of the induction zone were analyzed.It was found that whether the current density regulation mode or the current frequency regulation mode is adopted,the cases with 20 or 25 mm radius of the induction zone have the great thermal energy conversion ability and the good thermal-force roll crown control ability.The reasonable adjustment of the length of the induction zone can reduce the radius required for the maximum energy efficiency regulation.Combined with the results of the simulation analysis,the optimization of ES based on the control ability maximization requirement is achieved,which provides the base for the design and configuration of ES in RPECT.

Theoretical and numerical research on effect of tension mechanisms in strip flatness electromagnetic control rolling mills

To achieve stable rolling,the influence of a tension mechanism of a large diameter ratio roll system on the rolling process of a strip flatness electromagnetic control rolling mill is studied.Through the analysis of the rolling deformation zone,the deformation zone composition form of a large diameter ratio roll system and a calculation formula of neutral angle under tension are proposed.To analyze the effect of front and post tensions on the rolling characteristic and the strip flatness control characteristic,a three-dimensional rolling finite element(FE)model of a large diameter ratio roll system with the function of roll profile electromagnetic control is established by FE software and verified by a strip flatness electromagnetic control rolling mill.Based on the model,the strip thickness characteristic,metal transverse flow,strip flatness state,and adjustment range of the loaded roll gap are analyzed for different front and post tensions setting values.The results show that changing the front or post tension setting values can improve the single-pass reduction rate of a large diameter ratio roll system and have little effect on the flatness control ability of the strip flatness electromagnetic control rolling mill.