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Level 2 Model Improvement

Key Benefits

  • A Simple Way to Add 20,000 Metallurgical Models into Existing Level 2 System
  • Intelligent Learning to Eliminate Learning Logic Errors and Learning Limitations
  • Improved Shape, Size Tolerance and Mechanical Properties
  • Low Investment Returned in One Month!

Recent series: Improved Level 2 Draft Scheduling for Good Plate Shape and Properties.

As mentioned in the cover page of the Consulting section, in producing high strength steel such as linepipe grades X80 - X120, rolling and cooling processes need to achieve exact process targets (temperatures, drafts, cooling rates etc.). Level 2 model improvement, by accurate predicting force, temperature, roll/stand deformation and thus metal deformation, provides increasing safety for the control system to predict and achieve the targets while the strip/plate shape is guaranteed. In addition, by integrating metallurgical strengthening measures in the Level 2 draft scheduling logics, such as to apply high draft in certain temperature ranges and thicknesses, much higher mechanical properties can be received for the same grade. This would lead to a huge profit, of about a million US dollars per month for a steckle plate mill. Metal Pass' ongoing projects are primarily in those fields. Such work requires excellent knowledge on physical metallurgy knowhow and rolling process models, as well as high-level software development skills in handling industry automation systems (Level 2, Level 3, Level 1 and AGC, etc.). The center point is the draft scheduling in Level 2 model.

In consulting on the Level 2 model improvement, we apply the entire rolling mill models we developed. We perform Level 2 development, Level 2 support, and particularly mill process modeling (including draft scheduling improvement).

Level 2 Model Performance Discussion  (Ask a question)

Rolling mill Level 2 model is, in traditional sense, an expanded roll pass design program, which creates pass schedule (draft distribution and rolling/holding stage plan) based on a long list of influence parameters. See Mill Level 2 Model Basics.

A slight modification of the Level 2 model would create great benefit. In many cases, the modification is only necessary for the input data files or inside a single function in a single file. The resume pass after the hold may have over 40% force error, as in the case of a client. Modification for such a system is necessary. Quite often, in the finish pass with a draft 10% or lower, some formula is actually not valid. This causes force error, and thus a wrong draft schedule would be created and the steel of bad shape would be produced.

Product Defects vs. Poor Level 2 Model

When the mill Level 2 model goes wrong, there would be all kinds of quality and operation problems, repeatable or unrepeatable. The draft schedule would be inappropriate and the rolling operation would be shifted away from the planned rolling conditions (temperature, force, torque, and number of passes, etc.). Consequently, targeted properties could be missed, product shape could be poor and in worst case, there could be equipment damage.

See Product Defects and Level 2 Model Error for a list of product defects, reasons for the defects and the common causes of the Level 2 model error. For example, center buckle and edge wave may be caused by unequal draft over the width.

Draft Scheduling vs. Level 2 model

Draft schedule is one of the most important results from the Level 2 model. A high quality draft schedule leads to good product quality while a poor draft schedule causes product defects. Level 2 model creates draft schedule by considering various constrains.

See details on Level 2 Draft Scheduling Issues in the document Level 2 Draft Scheduling Improvement.

Benefits of Metallurgical Level 2 Model

Traditional Level 2 model as a mechanical system cannot sufficiently meet today's production requirements which are deeply involved in the metallurgical processes (controlled rolling, etc.). Therefore, Level 2 model as a metallurgical system is in need. Metal Pass consulting intends to integrate metallurgical models into the Level 2 system, together with the use of intelligent learning to compensate for immaturity of some metallurgical models in the industry.

Please refer to Benefits of metallurgical Level 2 Model for details.

Significance of Accurate Level 2 Force Prediction

Level 2 model force prediction accuracy is one of the most critical factors for the Level 2 model quality and the quality of the draft schedule, and thus rolled steel properties. Flat rolling draft scheduling is primarily based on force prediction together with force related roll deformation (e.g. deflection, flattening), equipment capacity, etc. Accurate force prediction is one of the most difficult and significant problems in Level 2 model. For example, 1% force error reduction in the strip or plate mill Level 2 model may have a economic value of 1 million US dollar per year (see 1% Force Error Reduction = 1 Million US Dollars Per Year). Too much force error causes center buckle and edge wave, etc. of the rolled strip or plate (see description). For this reason, Metal Pass consulting would take Level 2 force model improvement as the start point for the Level 2 improvement.

Click to review the document Significance of Accurate Level 2 Force Prediction.

Significance of Accurate Temperature Prediction

Sufficient accuracy of the model prediction, especially that for the temperature, makes it possible for the scheduled metallurgical procedure to be actually achieved. Low accuracy of the temperature prediction results in a poor product quality (both shape and properties) and low yield, because the actual production is conducted in a condition different from the optimal one from the production scheduling. For detailed discussion, please review Significance of Accurate Temperature Prediction.

Level 2 Model Performance Issues 
(Ask a question)

Current Level 2 systems in the market, due to the history reason, primarily use simple formulas and thus reach only limited accuracy. Some systems are even with design error in adaptive learning. Various issues, if not handled correctly, would cause significant error of the Level 2 model. For the technical coverage on those issues, please refer to Metal Pass recent publications. Some keynotes for those publications are listed below as example.

Level 2 Model Basic Issues

Level 2 Model as a Metallurgical System

Solution on Level 2 Model Improvement  (Ask a question)

Just like a man with physically strong body has few occasions in sickness, a Level 2 model with all the parameters accurately predicted greatly reduces chances of strange problems. If the scheduling algorithms (in Level 3 production scheduling and Level 2 draft scheduling, etc.) are also optimal, the model operation should be good. The concept of Metal Pass model improvement is to give you an accurate and well-performed model system following the steps described below:

  1. Improve Level 2 force prediction model, which is the weakness of many systems
  2. Improve Level 2 Temperature Prediction Model, if it is also a source of problem
  3. Improve the roll deformation model and draft scheduling system
  4. Double check whether the scheduled metallurgical parameters are the optimal
  5. Integrate metallurgical models into the Level 2 system
  6. Improve algorithms of scheduling
  7. And so on.

The actual execution of the Level 2 model improvement, however, involves extensive technologies, because every step described above requires very high technical expertise. Metal Pass' strength is exactly in those areas.

In general, improvement of the rolling mill Level 2 model utilizes the models as described in Rolling mill Level 2 model.

Level 2 Draft Scheduling Improvement

See new series Improved Level 2 Draft Scheduling for Good Plate Shape and Properties.

Primary purpose for a plate/strip mill Level 2 model is to create quality draft schedule for good shape and product properties. Three key issues should be well addressed in a Level 2 model. Firstly, the logic in creating draft schedule based on predicted parameters should be effective; secondly, parameter prediction as basis for the draft scheduling should be accurate; and thirdly, metallurgical issues such as retained strain, recrystallization, etc., for model accuracy and rolled steel properties, should be well considered. On the one hand, a higher draft is preferred to reduce number of passes and to achieve better mechanical properties (in view of controlled rolling); on the other hand, a lower draft is helpful for better shape, especially in the finish passes.

See How we Improve your Draft Schedule in the document Level 2 Model Draft Scheduling Improvement.

Rolling Mill Force Model Improvement

One of the primary parameters the Level 2 model takes into account in creating draft schedule is the roll separating force. For a given mill, the roll separating force is the one to determine whether the limits of the mill are reached (force and torque, etc.). Many Level 2 force models use simple formula and thus only reach limited accuracy. Some systems are even with design errors in adaptive learning. Adaptive learning with the flow stress is with certain limitations and thus can only reach limited accuracy for force prediction. By applying sophisticated rolling process models and improved learning logics, and by introducing metallurgical models into Level 2 system, we can greatly increase Level 2 force model accuracy (about 5% error) and thus significantly improve finish product shape and rolled steel properties, and increase mill yield and productivity.

See Improvement on Level 2 Model Force Prediction for more detailed discussion.

Level 2 Temperature Model Improvement

We provide accurate model for heat transfer coefficients for every heat transfer stage. For example, the heat transfer during rolling in the roll gap depends on roll and stock materials, roll RPM, pressure, descaling procedure and roll cooling, etc. The heat transfer coefficients in the inter-pass or during traveling on the run-out table depends on relative speed between stock and air, etc. We also integrate those models into your temperature learning procedure. In addition, our work on rolling mill force model improvement is of great benefit to the Level 2 temperature model improvement. See Improvement on Level 2 Model Force Prediction.

See Temperature Model Improvement for details.

Integration with Metallurgical Model

Integration with metallurgical model can greatly improve the quality of the Level 2. Traditional Level 2 model was designed without metallurgical concept in mind. Such a design, however, is facing ever strong challenge due to the application of the new rolling technologies such as the low temperature rolling (in which the recrystallization cannot be completed), hold in the middle of rolling passes, and rolling of steels with microalloys.

For details on Metal Pass Level 2 model improvement with metallurgical integration, please refer to Integration of Metallurgical Model into Mill Level 2.

Level 2 Model System Further Development
  (Ask a question)

Level 2 model system further development can be categorized in the consulting for Level 2 model improvement. However, such an improvement may require more than several lines of source code modification. Due to the larger scales of the change, the effect of improvement is more significant.

Level 2 System Architecture Development

Level 2 System Architecture has been newly developed and published recently (AIST08, MS&T08, etc.). It is designed with full metallurgical principles integrated, uninterrupted upgrade, and state-of-the-art software engineering technologies. Related Level 2 Model Architecture will include process models, metallurgical models, expert system, system learning, etc.

Metal Pass Level 2 model system development covers a variety of areas such as

  • Rolling Mill Level 2 Model
  • Reheating furnace models
  • Accelerated controlled cooling (ACC) model
  • Integration of metallurgical model into Level 2 system
  • Prediction of rolled steel properties (also in Level 3 model)
  • Slab size optimization and slab grade optimization (also in Level 3 model)

For a deep technical coverage, please refer to Level 2 System Development.

Rolling Mill Level 2 Metallurgical Model Development

Metallurgical model can be integrated into the rolling mill Level 2 model to increase its accuracy. The model can solve the problems of the retained strain, controlled rolling including hold, etc. Due to the complexity of the model development, intelligent learning may be used.

Detailed models and model development are described in Rolling mill Level 2 model.

Reheating furnace Level 2 model Development/Improvement

Over-heating a slab wastes energy and reduces steel quality, but under-heating a slab may cause more problems. We apply a list of reheating models to improve your reheating process. The models include those to predict temperature field, thermal stress, and microstructure, etc.

See document Reheating furnace Level 2 model for details.

Controlled cooling Level 2 model Development/Improvement

The controlled cooling process and the start point for the controlled cooling, should be determined based on metallurgical models. Accurate prediction of the heat transfer coefficients and temperature process also require high level of the heat transfer models. We can apply our high quality models to improve your controlled cooling Level 2 system and your cooling process.

For details, please review Controlled cooling Level 2 model.

Level 2 Model Improvement Case Study - Oregon Steel

Level 2 force model improvements were performed to EOS steckel mill with very high accuracy and least source code changes. Learning logic errors were corrected, adaptive learning limitation was removed, and metallurgical principles were applied.

  1. Introduction
  2. Data Collection and Data Analysis
  3. First Improvement
  4. Testing Results for the First Improvement
  5. Second Improvement
  6. Summary/References

Metal Pass Resources on Level 2 Model Improvement  (Ask a question)

See the profile for the primary consultant Dr. Benjamin Li. You may also view our company and personnel profiles. Please contact us via email admin@metalpass.com or by phone (001) 503 516 9625 for top quality consulting services.

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