Software Engineering Issues
in Level 2
Please refer to
Mill Level 2 Model Basics for the symbols and basic terms
used in the section.
System Architecture based on Interactive Relationship of Mill Process Models
Highly efficient rolling mill Level 2 model system can be designed based on the object-oriented principle together with the interactive relationship of the mill process models. For example, in the structure design, the relationship between microstructure and flow stress could be reflected; and similarly, draft, flow stress and roll force. It is pursued that at least 80% of the classes are consistent to the corresponding data structures. The design of DBMS should also follow the structure design.
In the design, one single set of the parent classes should be created based on general features of the mill. The classes for roughing mill, intermediate mill and finishing mill, etc., should be derived from the parent classes during which the special features for each mill stages can be added. Consistently, a single set of general structures can be designed for the general mill, and the composite structures designated for roughing mill, intermediate mill and finishing mill, etc., should use the general structures as data types. Every class, parent or derived, should take the corresponding structure (general or composite) as its data type to define its properties. In this way, every variable (e.g. the property) in the class may represent dozens or even hundreds of mill parameters. Any data type (either structure or composite structure) can be used in various mill stages (roughing, intermediate and finishing, etc.) and in various scopes (local, module and global). One example to apply the object-oriented principle is a program suite to calculate roll force for nine pass-sequences . Almost all the calculations were done in a single class, the parent class. The eight derived classes (for those other than the general pass) only made minimal modifications to the parent class, primarily in the calculation for cross-section and contact areas.
Currently some poorly designed Level 2 systems are with, for example, over 400 letter size pages for parameter definition. This adds tremendous difficulty for newly hired engineers to modify or support such systems. It is believed that a well-designed Level 2 may only needs one tenth of those parameters (about 40 pages).
Web-based Level 2 System
Some of our clients still run the steel rolling facilities without Level 2, while some other clients, especially those in Asia, bought the Level 2 systems but had to retire them due to the lack of skills to support them (OpenVMS-based). It seems that a web-based Level 2 system can help those mills without the Level 2 or with the Level 2 of limited functionality. We tested the capacity of the web for engineering applications, by running a computing-intensive program. It is a finite-differential program to calculate the temperature distribution over the cross-section of the rolled steel, say, in every 0.05 seconds along the 28 passes of the rolling and controlled cooling in water-boxes . The result is satisfactory. The data transfer for Level 2 should be sufficiently fast. The numbers and text files really don’t take very long to transfer, and the model calculation should have lower computing intensity as the FDM program.
Level 2 developers know that a great portion of the Level 2 programming is usually spent in the data communication and memory management. However, in a web-based Level 2, those functions have been included in the web servers! While financial institutions use web to run much more mission-critical applications than the steel mill Level 2, there should not be any concern on the data security or availability. If the user prefers, the web server can be put inside the mill, the same as the Windows-based Level 2. New technologies such as Microsoft .Net enable the developers to write a web-based application in exactly the same way as the Windows-based one. Web servers are usually free of charge and are available in most versions of the Windows (e.g. Windows 2000 Professional) and for other operating systems. Technologies are mature in this area. The cost for development and thus purchase of such a web-based Level 2 system should be much lower than a traditional one. In addition, it is very easy to use, to support and to upgrade.
In the software engineering aspect, the steel industry is usually ten to dozens years behind the IT industry. Since long in the IT industry, the software system has evolved from client-server architecture to three-tier (client, server and database) and multiple tier architecture, and to the distributed architecture and further, to today’s Service-Oriented Architecture (SOA). Technologies such as SOA and COM+ (Component Object Model plus), make it possible to develop powerful software systems with little effort. SOA allows various sub-systems and applications from various platforms to be easily integrated . Applications based on the old platform cannot take advantages of the new information technologies. Currently, it is still quite popular in the steel industry to use the DOS-like OpenVMS to run Level 2 application. Most OpenVMS-based Level 2 systems are still in the client-server architecture, with data stored in only a short-term.
While European vendors for Level 2 systems have gradually moved to Windows, most US-supplied Level 2 packages are still based on OpenVMS. Steel mills with OpenVMS–based Level 2 have at least following concerns:
Long-term availability of hardware and system supports.
Personnel and upgrade issues. Less and less new engineers have the knowledge of OpenVMS. OpenVMS does not have the features such as uninterrupted upgrade for the application software.
Integration to present IT. Many current information technologies cannot be easily applied in OpenVMS. Some technologies such as OPC (OLE for Process Control) were primarily developed based on Windows.
Metal Pass Consulting