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TECHNOLOGIES AND AUTOMATIC CONTROL SYSTEMS FOR
THE PROCESSES OF ROLLING AND HARDWARE PRODUCTION
THE AUTOMATED SYSTEM FOR THE CONTINUOUS MILL PRODUCTION.
Continuous rolling mills are the main suppliers of finished metallurgical production. The rolled-products range at these mills must be as large as possible to satisfy the market requirements. That demands frequent mill readjustment and makes preproduction difficult. The modern hardware makes it possible to automatize the roll pass design process and the mill adjustment. An industrial computer based system of this kind, designed by the Ukrainian company DONIX, is described in this article.
The section mill 250 is designed to produce 10-30 mm rounds and flats from 50x10 to 20x3 mm. It consists of 7 stand roughing group, 3 stand intermediate group and two finishing lines. The first one includes 12 stands and the second one - 9 stands. Two different products are produced simultaneously which demands matching the settings of two finishing lines and the common stands group. Thin profiles are usually rolled on the first line which includes more stands, but anyway the second volumes of the metal which passes the mill must be equal. So the feature of this rolling mill setup is that the roll pass design for the production of two different products as well as the speed schedules of the two finishing lines and of the common group must be coordinated. The setup sheets (table 1) which contained information about the roll pass design and the speed regime were used for preproduction.
Table 1.
| Mill setup Sheet Product: 30RD Line 1 Date 12 May 2002 |
| Stand |
Shape |
Pass |
Stock size (WxH) |
Gap, mm |
Speed, m/s |
| 1 |
|
|
|
|
|
| 2 |
|
|
|
|
|
These Mill setup sheets were several hundreds in number. The same product could be manufactured on the finishing line from different stocks coming from the intermediate group. The rolls speed regime was controlled with a hand tachometer which made the process of the mill setup labour-consuming and increased the risk for the attendants.
Proceeding from the current situation analysis, the following measures were taken before the systems introduction:
- a) the roll-pass design was revised and the number of stock sizes from the intermediate group was reduced to four;
- b) the universal roll-pass design was created for first three stands to produce goods from the billet with sizes from 120x120 mm to 130x130 mm;
- c) the registration of the actual rolls diameters at the stands was better organized.
In the process of the system structure creation it was taken into account, that the main persons, responsible for the mill adjustment are the foreman and the operator. Their duties are divided in the following way: the foreman prepares the Mill set-up Sheets for the both lines and gives the necessary information to the rollers and electricians; the operator adjusts the stand motor speeds so as to obtain the required linear speed. According to that the System consists of two units: the main one at the pulpit, industrial computer based, and the additional one, implemented on the foreman's PC.
The main unit's functions are: to accept information about the stand motors speeds and current, to visualize the received information in numerical and trend forms; to input, store and display the mill setup parameters (roll diameters, passes-codes, stock sizes, and so on). The flow-charts data base, daily reports and recorded trends are stored in the industrial computer memory. The flow-charts base editing, daily reports and registered trends handling are carried out on the foreman's PC.
The hardware and software of the units were selected according to the above mentioned tasks. The PCA-6772F-Q1A1 industrial computer, mounted in IPC-6806S case (Advantech) with Back-UPS is used for the main unit (Fig.1). The high performance ADC converter card PCL-818L-A6 provides the conversion of normalized analogue signals into a digital form. Normalizing converters SCM5B41-03 (Data forth) are installed on four SCMPB02-3 Back panels. Their connection with the ADC card is realized through Cable-Wiring Terminal ADAM-3937-A. The SCMXRK-002 power supply provides the necessary voltage for SCM5B41-03 Converters operation. All the above mentioned modules are mounted in AK 1652.600 Rittal cubicle, located in the Main Pulpit's room. To provide the operator's interface the Industrial Flat Panel Monitor FPM-3176TVR, industrial keyboard KS801 (Indukey) and protected Mousebutton KH8243 are mounted on a separate spot in the pulpit which is comfortable for work. The connection between the main unit and the foreman's PC is realized through Ethernet Local Area Network. All the input signals for the System operation are received as voltages from the corresponding electrical drive panels.
The main unit controller works in a real-time mode. It collects data about 64 main and 8 additional signals with at a 100 Hz frequency, stores them in the memory, and displays them as well as the operator's interface and network functions. The real- time Operational system Neutrino, designed by QSSL (Canada) is used to ensure the error-free performance of the System. The common Windows OS is used on the foreman's computer. The operator's interface is created using the Photon graphics editor. All the application software is written in the C language. Special programs Flowchart Editor (Ed) and Trends Viewer (Vie) were created for the user's needs. The first one provides access to the data base to edit the existent flowcharts and create the new ones. The main Ed screen is shown at Fig. 2. According to the rolling mill lay-out the information is divided into three main groups. The first group "Line 1" contains the adjustment parameters for stands 8-22 of the first line for the production of different stock sizes. In the same way the second group "Line 2" contains the same information for stands A-L. As the stands of the intermediate group are used for the both lines, they have double signs. For example, the first intermediate group stand is indicated as №8 for Line 1 and №A for Line 2. In the flow charts names always contain information about the product name and the pass of the last intermediate group stand. It is necessary for the auto check of a possibility to produce the selected products simultaneously. The user has an opportunity to edit the selected flowchart by pressing the "Edit" button. The information in the appearing window (Fig 3) is similar to the one in Table 1, but instead of an absolute value of the roll linear speed it contains the R-factor, that is a ratio of the linear speeds of the actual stand to the previous one. The stands which are not in use must be marked as Dummy on the corresponding screens. The Ed can be used on any PC, but the saved Flowchart can be sent directly to the main unit using Ethernet facilities only from the Foreman's PC. And correspondingly there is a possibility to load the existing Flowchart vice versa from the main unit to the Foreman's PC.
The Flowchart for the Roughing group stands is designed for the input billets of three sizes (120x120), (125x125), (130x130). This information is located in the "Other" option of the Ed main screen. The window with the information about the Roughing Group settings (Fig.4) contains the speed of Stand 1 which is the basis for calculation of all the other speeds through the R-factors and roll diameters.
The created Flowchart can be sent to the main unit and its back-up copy can be saved on the Foreman's PC. At the beginning of the shift the operator selects the required flowcharts and sets them using the SVS operator's main screen interface (Fig.5). The accuracy of roll diameters, billet sizes and other parameters can be checked using the "Preview" function. These data can be corrected directly on the main unit by the authorized staff members, using the password mode. If the indicated values are correct, the operator loads the target speed of the Stand 1 motor, and gets the reference speed values for all the other stands, recalculated through the R-factors. Then he adjusts the actual speeds manually to make them equal to the reference and the rolling process can be started. The speeds (linear or rotating) and the currents of drive motors can be indicated in digital, scope (Fig.6) and diagrams mode. The operator can also save the scope data to file for further detailed analysis. This function allows the attendants to find out the reasons of troubles in the rolling process. The scope mode is also useful for the precise adjustment of the mill, as all the current changes can be clearly observed on the screen when the stock passes through different stands.
The speeds, diameters and sizes values can be saved to the Flowcharts data base for future rolling, when the mill is set up precisely. This function can be realized only by authorized attendants. The amount of input billets and output stocks is calculated automatically and indicated on the main screen. All the accumulated information is saved to the Report text file at the operator's command at the end of the day.
The introduction of the automated system for the continuous mill production gives the following advantages:
- The Flowcharts data base creation becomes easier and more accurate;
- The mill adjustment time when changing for a new product is shortened essentially;
- The adjustment of the motor speeds becomes easier and more accurate;
- The time, necessary to find out the reasons of errors in the mill operation, is shortened;
As a result, the above mentioned advantages allow to increase the rolling mill output and efficiency.
Fig. 1. System Structure Scheme.
Fig. 2. The main Editor screen.
Fig. 3. Screen for Line 1 Setup Sheet edition.
Fig. 4. Screen for Roughing Group Setup Sheet edition.
Fig. 5. SVS operator's main screen interface.
Fig. 6. The scope mode of speed and current visualization.
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