Millsim is a range of software to simulate flat rolling, coating and annealing. The software is used to analyse operational practices and problems, evaluate the impact of new or modified equipment, evaluate control strategies and train operators and automation engineers.

  Mill Analysis User Interface

Interactive Rollgap Program

Measured Rolling Mill Data Analysis

Reduction Scheduling Algorithm

 Mill Setup Calculation

Rollgap Model Sensitivity Analysis

Thermal Camber Analysis

Shape and Profile Analysis

Roll Stack Deflection Analysis

Mill Throughput Analysis

Dynamic Mill Simulator

Coil Winding Analysis 

Dynamic Coating Mass Control Simulator

Annealing Simulation

Mill Analysis User Interface MILLSIM consists of a number of program modules which operate from a common database. Each data file holds data for a particular aspect of the rolling operation such as mill characteristics, roll profiles, rolling schedules and material properties. While all programs can be executed in "stand-alone" mode, the Mill Analysis User Interface simplifies operation of the programs and minimises the computer expertise required. The interface also protects the data and facilitates manipulation of it by means of text sensitive editing and appropriate data screening.  

Interactive Rollgap Program  This is an interactive tool for analysing rollgap variables, one stand or pass at a time. The program is menu driven and has default material properties and rollgap variables for steel and aluminium rolled under hot and cold conditions. This makes it suitable for use by inexperienced personnel, for training purposes and for answering questions requiring a small number of rollgap calculations. The program allows the use of a number of rollgap models:

The ‘Universal’ model provides fast approximate solutions for the full rolling regime
The ‘Circular-Arc’ model provides accurate solutions for hot and cold rolling
The ‘Non-Circular-Arc’ model provides accurate solutions for cold, temper and foil rolling.

The Non-Circular-Arc model is the leading edge of rollgap modelling and simulates the roll flattening behaviour associated with aluminium foil rolling and steel double reduction rolling. The program integrates the differential equation of equilibrium in the regions of plastic reduction and calculates the roll profile using the direct influence function of Jortner. This allows the distance between the work roll centres to be determined and thus predict the onset of roll touching outside of the strip edges. Forward slip is determined from the location of the pressure distribution peak at the neutral point.

The model calculates force, torque, slip and exit temperature.
The model can be inverted to calculate yield stress, friction coefficient or other parameters.
It includes elastic, plastic and thermal properties of selected materials.
It is suitable for cold, temper and foil rolling.
The model allows explicitly for mixed slipping and sticking conditions.
Elastic compression and recovery effects are included.  

Measured Rolling Mill Data Analysis  This program facilitates tuning of the rolling models to match the measured behaviour of a particular rolling mill. Due to physical limitations certain parameters, particularly friction coefficients and yield stress, are known with less precision than others and require fine tuning if the full potential of the models is to be realised.

The program compares measured force, torque and strip temperature with values predicted by the model. This is done by inverting the rollgap model equations to calculate the errors in the friction coefficients, yield stress offsets and heat transfer coefficients for multiple sets of measured data. Adaption models are also included and may be used to realistically assess the performance of the rollgap models in an online environment. 

Reduction Scheduling Algorithm  These algorithms calculate optimum rolling strategies including thickness reduction, tension and rolling speed for each pass or stand, subject to processing limitations to achieve high productivity. Users may specify operator practices to suit particular mills and have a choice of power optimisation or alternative scheduling algorithms.

The algorithms can achieve a specified force on the last stand or pass which is important for hot rolling or when shotblast rolls are used in cold mills. Specified exit temperatures can also be attained for hot rolling mills. 

Mill Setup Calculation  Threading setup references for speed, rollgap position, and shape control actuators are calculated from the full speed rolling schedule and the work roll thermal camber. The results may be used to manually set up cold mills with improved threading and head end thickness control performance.

Rollgap Model Sensitivity Analysis  Rollgap model equations are solved for nominal and perturbed rolling conditions to calculate the sensitivity of the key rolling variables: force, torque and slip to the independent rollgap parameters of thickness, tension, friction and hardness. Sensitivities may be presented in either absolute or dimensionless form and are used to calculate gains for online control systems.

Thermal Camber Analysis  Axi-symmetric heat flow and radial expansion transients are simulated along the roll barrel. A model for work and backup roll wear is incorporated as well as the ability to side-shift the work rolls.The latter feature may be employed to investigate optimum strategies for side shift operations in hot strip mills.Graphical displays show thermal camber and roll wear over an extended period of rolling with inter-coil delays. 

Shape and Profile Analysis  This program permits analysis of the complete range of flatness and profile problems arising in hot and cold rolling. It predicts the transverse distributions of longitudinal stress, thickness profile, buckling amplitude and width strain. A complete set of tension stress and thickness profile parameter sensitivities to independent input parameters (e.g. ground and thermal crown, roll force, roll bending, yield stress and input profile) are generated. Optimum ground roll profiles which ensure flat strip may also be calculated.Unique features include a three dimensional spread model and models for plane stress deformation, both upstream and downstream of the rollgap, plastic deformation via inter-stand creep and buckle amplitude of manifest flatness defects.

Roll Stack Deflection Analysis  Shape control actuator settings are calculated to achieve flat strip for a specified roll force and thickness profile. Ground and thermal roll cambers and roll edge chamfers are used in calculating roll deflections. Optimum roll bending force, side shift position or roll force can be calculated, given the other two settings. It is also possible to calculate the optimum ground crown for any rolling schedule.

Mill Throughput Analysis  Mill throughput (both product specific and overall) is analysed in terms of product mix, coil masses and rolling speed. It provides a useful tool for evaluating the benefits achievable through reduced delays in threading or roll changing, increasing rolling speeds, or changing product mix.

Dynamic Mill Simulator  The simulator emulates tandem or single stand rolling mills in real time and includes dynamic models for rollgap processes, mill actuators, tensions and exit strip shape. It can accommodate force, thickness, extension and tension controls. Hot mills may also have interstand loopers with their associated control systems. The operator interface includes a control desk, mill mimic, a strip shape display and a simulated chart recorder display. The system supports a full range of standard operator functions such as threading, acceleration and deceleration trims. Typical mill disturbances can be triggered and gains and controls strategies modified during execution of the program. It is used for operator training and testing automation systems.

Coil Winding Analysis  Coil collapse is a common problem for cold rollers of tinplate and thin strip and can lead to major losses in reclamation costs, yield and late delivery. The interactions between winding tension, transverse thickness profile and strip flatness are complex. The coil winding analysis program analyses the three dimensional tangential and radial stresses within a coil. It can be used to investigate the effect of factors such as surface roughness, longitudinal and transverse strip thickness, temperature profiles and mandrel characteristics. A recent consulting project used the program to reduce coil collapse by a factor of four.

Dynamic Coating Mass Control Simulator   A key factor in the efficient operation of a continuous galvanizing line is automatic control of the stripping jets. The ability to predict the impact of changes and take appropriate control action results in the reduction of both transition lengths and coating variability. The Dynamic CMC simulator includes models for the jet stripping rig and coating gauge and solves the non-linear Navier Stokes equations to determine the coating thickness at the exit of the stripping zone. The simulator is used for operator training and the testing of automation systems.

Annealing Simulation  The objective of batch annealing operations is to get all parts of the coils to reach a target temperature in minimum time without overheating any part of the charge. Control of the process is complicated by the fact that it is not possible to measure the coil interior temperature (or cold spot). The annealing simulation model predicts the temperature distribution throughout the charge; including the cold and hot spot temperatures. The uses of the program are therefore the following:

Off-line simulation permits control strategies to be evaluated and modified to improve product quality and throughput. In most cases this information is used to determine the most efficient heating and cooling times.
Simulation of different combinations of coils helps select the best combination for charge building.
The model can be used on-line using to real-time thermocouple measurements to predict hot and cold spots for direct use in control strategies.
Equipment modifications or purchases (such as high flow fans or pure hydrogen atmospheres) can be evaluated prior to installation to assess impacts.
Coupled with the coil winding analysis to investigate batch annealing stickers.