DIAGNOSTICS OF SURFACE DEFECTS AS CONTROL SUPPORT IN STEELWORKS

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1 Oxigen A cetylene , Brno, Czech Republic, EU DIAGNOSTICS OF SURFACE DEFECTS AS CONTROL SUPPORT IN STEELWORKS Pavel ŠVEC a, Jiří DAVID a, Robert FRISCHER a. VŠB Technical University of Ostrava, Department of Automation and Computer Application in Metallurgy, 17. listopadu 15, Ostrava - Poruba, Czech republic. pavel.svec@vsb.cz, j.david@vsb.cz, robert.frischer@vsb.cz Abstract (title 10 pt. bold, gaps 24 and 0) The article describes a laboratory model of non-destructive monitoring of crystallizers desks by laser sensor while on high surface temperatures, its possibilities and limitations. Uses this model will help us to scan blanks from all four sides and thus analyze its surface with purpose of control support of technology on continuous casting devices and increasing of quality of the blanks. Keywords: defect, diagnostics, quality control, control systems, continuous casting device 1. INTRODUCTION The article describes a laboratory model of non-destructive monitoring of crystallizers desks by laser length sensor while on high surface temperatures. There will be described two laboratory models, on which the tests have passed. As a result of this research will be creation of laboratory model, which will be able to recognize the surface defect on continuous casting device. 2. DEFECTS Continuous steel casting is a technological progress, whereat isn t possible to exclude the defect occurrence. Liquid steel is pouring into the cold crystallizer, where the liquid steels surface is exposed to influence of oxidation atmosphere. Solidification runs from perimeter to the centre. That s why we can find similar or the same defects when the liquid steel is processed by both ways. This presumption is concerned as the surface so the inners defects. In the frame of this article are presented research results incurred on the lab models. 3. MODELS PRINCIPLE AND USED HARDWARE Primary cooling Secondary cooling Water Crystallizer Control room ZPO The monitoring system Laser distance sensor Cutting blank The goal of this solution is to design a system, whereby we could scan blanks from all of the sides, so that we can analyze its surface (from the view of lengthwise defect). Current suggestion supposes sensors placing, behind the straightening devices, respectively behind dividing and marking device (where the blank is uniquely identified). Into this spots we are supposing to place four laser distance sensor, which could scan the entire surface from all sides of the blank (Fig. 1). Scanned data would be recorded to the Fig. 1 Diagnostics principle defects monitoring system. On the staffs monitor would be displayed four windows, in which would each blanks surface be monitored. In the case of surface

2 defect the system could be able to generate alarm signal. In current time the laboratory model is making to verify possibilities of this approach, without influence of flakes, which are limiting factor of this solution. 4. HW COMPONENTS AND DATA EVALUATION FROM THE LABORATORY MODEL TO SCANING DEFECTS ON BLANKS Fig. 2. Special HW card NI PCI pin. Fig. 3 Block diagrams in Simulink In this section will be described current state of work on laboratory model, when all tasks were focused to connection of distance laser sensor, to all scanned data could be stored to PC and so to the measuring of some surfaces for example metal ingot. Measured data were stored to the PC through the special HW card NI-PCI (Fig. 2). To allowed current surface scanning through NI-MCI 6221 we have to setup the MATLAB environment (Fig. 3). After that the measuring was made. On the (Fig. 3) we can see interconnection of each components intended to measure in laboratory diagnostics system. Further was necessary to setup parameters: measuring mode between synchronous and asynchronous, measuring card type, samples per second number setting, block size, measuring channel setting and so on. For measurement, there was setup these parameters: asynchronous signal, 10k samples per second, channel A8, measurement time 0.08s and measurement type Normal. These parameters were setup in simulink environment. We did several measurements, which were displayed in block called Scope. File with time domain running was inserted to the block called Simout with possibility of visualize of measured running. Fig. 4 Laboratory model, overall look. Fig. 5 Laboratory model of surface scanner The first laboratory model (Fig. 4, 5), ensure automatic shift control of laser sensor in x axis direction and controlled movement of sample in y axis direction. This model comes from assembled laboratory model for crystallizer s surface measurement.

3 A software application is developing which is able to visualize measured data. On figures 6 and 7 can be seen a demonstration of the proposal of this application. Application should be able to visualize individual measurement points as in discrete so as in continuous spectrum and visualize sample profile on selected coordinates. Fig. 6 Visualization of surface in discrete form Fig. 7 Visualization of surface in continuous form and profile in current position Core of the model will make decision of defects and its classification. 5. SYSTEM TESTING Result is to verify possibility of surface scanning by laser distance sensor, when temperature is increasing. For measuring purposes was in the VSB-TU premises made a laboratory model (Fig. 8). It was completed from heating rods, ratio pyrometer (Fig. 10) and distance sensor (laser sensor) (Fig. 11). Fig. 8. Laboratory models scheme On the further figures 12. and 13. there is presented a heating rod, placed in special holder. This holder carries also a ratio pyrometer and laser Fig. 9. Heating rod sensor. After the laser sensor was connected, the heating rod was heating up and a fake defect were simulated. This defect is monitored while increasing temperature. As we mentioned above, the purpose is to verify sensor behavior under the high temperature levels. Temperature was closed to real ZPO working temperature.

4 Obr. 10. Pyrometr LAND FP12 and processing unit Obr. 11. Laser distance sensor Fig. 12. Laser sensor pointed to the hottest place of the rating rod. Fig. 13. Laser sensor and the ratio pyrometer. After the initial testing was necessary to find out what is the maximum sensing temperature for used distance sensor. For that test were used a heating rod with 2,9Ω resistance. The heating rod was connected to the power supply and then burden with current of several values. Passing current invoked temperature to increase. The heating rod reaches its maximum temperature of about 1300 C. This is an appropriate temperature which is responding to blank on continuous steel casting devices (CSTD) temperatures. In this phase of experiment didn t need to fasten laser sensor and pyrometer on interposer bar. Aiming on the individual spot (hottest place on the rod) was enough. The experiment was started, when the heating rod reach the temperature of 500 C. This temperature value was increased to the limit value of 1250 C. It was increased after 100 C steps to the limit value of 900 C. From the 900 C the temperature steps were lowered (50 C). When the temperature has changed, we wait for the while, to stabilize final temperature value. Than the laser sensor was applied and we red if the output value is in limits and if is possible to detect defect. Output signal were red from the oscilloscope. This temperature is enough to measure inner defect on CSTD. 6. CONCLUSION Two laboratory models were made. The first is scanning surface defect. Main contribution were possibilities, where can be special equipment can be fixed and what possibilities we have, if scanning surface defects. The second model was intended to tell us, what is the maximum read temperature or that sensor. Both models shows us, what is the next direction of research when designing diagnostics device to identification of surface defect on continuous steel casting devices.

5 ACKNOWLEDGMENTS This paper can origin by suuprt of Department of commerce of Czech Republic: solving grant project TIP ev. č. FR-TI1/319 Vývoj nových progresivních nástrojů a systémů podpory řízení spolehlivostí primárního chlazení na bramovém zařízení plynulého odlévání ocelí pro zvyšování kvality náročných plochých výrobků. LITERATURA [1] DAVID, J. A KOL.: Vývoj nových progresivních nástrojů a systémů podpory řízení spolehlivosti primárního chlazení na bramovém zařízení plynulého odlévání pro zvyšování kvality náročných plochých výrobků (Souhrnná zpráva o řešení projektu v roce 2011 na VŠB-TU Ostrava). VŠB-TU Ostrava, 12/2011, 23 s. [2] DAVID, J., HEGER, M., VROŽINA, M., VÁLEK, L. Visualisation of Data Fields. Archives of Metalurgy and Materials, volume 55, issue 3/2010, p , ISSN [3] LENORT, R.; SAMOLEJOVÁ, A. Analysis and Identification of Floating Capacity Bottlenecks in Metallurgical Production. Metalurgija, January-March 2007, vol. 46, no. 1, s ISSN [4] MAZALOVÁ, H., ŠVEC, P., DAVID, J.: Exploitation of Method Datamining for Prediction of Surface Defects on Flat Casting. METAL 2011, str. 136, Tanger, spol. s r.o. Ostrava, Ostrava, ISBN