Tetsu-to-Hagané
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ONLINE ISSN: 1883-2954
PRINT ISSN: 0021-1575

Tetsu-to-Hagané Vol. 70 (1984), No. 9

  • The Historical View of Measurement Technology in the Japanese Iron and Steel Industry

    pp. 987-991

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  • An Expectation of Measurement from the System Control Engineering

    pp. 992-993

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  • Recent Development of Sensing Technology

    pp. 994-999

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  • Non-Destructive Testing and Image Processing

    pp. 1000-1006

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  • New Methods for Temperature Measurement and Their Applications to Steel Process

    pp. 1007-1013

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    This report shows three new methods for temperature measurement and their applicationsΔto steel process.
    (1) The effect of multiple reflection in the radiation thermometry was theoretically and experimentally studied, and a method for simultaneous measurement of both temperature and emissivity was developed and applied at the color coated strip process.
    (2) The self-scanning photodiode array was applied to temperature distribution measurement. The characteristics of photodiode arrays were investigated, and the micro-computer based system is now operated for temperature measurement of the welding bead at the ERW process.
    (3) The temperature distribution measurement system using optical fiber was developed, and applied at the exit of C.C. spray zone and under the mould.
  • Temperature Distribution Measurement in the Flue and Its Relation to Operating Conditions of the Coke Oven

    pp. 1014-1021

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    The apparatus which can measure the temperature distribution of a flue wall of a coke oven was developed. The following results are obtained by measuring the temperature distributions at various conditions of coke oven.
    (1) Radiation pyrometer which is set in the water cooled probe can measure the flue wall temperature of coke oven.
    (2) The quantitative relations between the temperature distributions in the flue and the operating conditions of coke oven were obtained. The method to improve the temperature distributions in the flue was derived.
    (3) The coke quality at the upper part of the oven is inferior for the coke oven which has single stage burner. It is verified that the lower limit of coke quality can be guaranteed by controlling the temperature at the upper part in the flue.
  • Control Method of Secondary Cooling Water for Bloom Continuous Casting on the Basis of Temperature Estimation

    pp. 1022-1029

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    Dynamic control of secondary cooling water for bloom continuous casting (C. C.) is described. This method is based on online estimation of bloom temperature by one dimensional heat transfer model. Field data, such as molten steel temperature, actual water flow, casting speed are used in the estimation. The heat transfer model is updated by adaptive control of heat transfer factor to equalize calculated temperature with measured one. To attain closer control, feed forward control method is applied. Bloom temperature is predicted by the updated model and appropriate water flow for each zone is determined by the difference between predicted temperature and aimed one. Since cooling process is considered in this method, surface temperature is controlled at the aimed one not only in the case of steady casting speed and also in the case of transient casting speed. Therefore, this method compensates for the problems of usual cascade control method.
    Dynamic control system is introduced to bloom C. C. line No. 3 in Kobe Works and it is confirmed that change of temperature has been remarkably reduced and surface cracks have been prevented compared with usual control.
  • Optimal Heating of Ingots in the Soaking Pit Based on Temperature Estimation

    pp. 1030-1036

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    The investigation is concerned with the optimal operation of soaking pits by means of the systems engineering technique. The mathematical models of heat transfer for ingots and soaking pits are developed. The model for the ingot was evaluated to the data on surface and inner temperatures of ingot, while the model for the soaking pit was tested against the data on fuel flow. The results obtained are satisfactory to estimate the optimal heating pattern of the soaking pits. The optimization equations are formulated and the solution is obtained by using a multiplier method. Numerical results are given and the relation between the track time and the optimal solution is discussed. It is found that there exists an optimal heating time which minimizes the fuel consumption. When the heating time is shorter than the optimal value, the lowest temperature of the ingot becomes the constraint. On the other hand, when the heating time is longer than the optimal value, the mean temperature of the ingot becomes the constraint.
  • Radiation Thermometry of Cold Rolled Steel Strips in a Continuous Annealing Furnace

    pp. 1037-1044

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    This paper describes the principle and an application of a newly developed radiation thermometry, which can measure temperature and emissivity simultaneously, and also eliminate stray radiation coming from heat sources.
    The system of the method is composed of a radiometer and a reflecting mirror which are disposed symmetrically at an angle θ with respect to the normal to the surface of a measured object. p value defined as a specular reflection factor is important and substantial for this method.
    This system was applied to a continuous annealing furnace for cold rolled steel strips at Nagoya Works of Nippon Steel Corporation.
    The accuracy was estimated to be within ±10°C.
    x

    Readers Who Read This Article Also Read

    1. 日本鉄鋼協会第108回講演大会 講演概要集(II) その7 Tetsu-to-Hagané Vol.70(1984), No.13
    2. 日本鉄鋼協会第108回講演大会 講演概要集(II) その3 Tetsu-to-Hagané Vol.70(1984), No.13
    3. 日本鉄鋼協会第108回講演大会 講演概要集(II) その9 Tetsu-to-Hagané Vol.70(1984), No.13
  • Temperature Pattern Measurement and Weld Control in Electric Resistance Welded Tube Mill

    pp. 1045-1051

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    In order to realize highly reliable quality of electric resistance welded (ERW) tubes, it is indispensable to grasp precise heat condition of weld portion. Out of such need, the pattern thermometer (PT) have been developed as a sensor which can directly measure temperature pattern of weld portion, and it can also pick out the temperature of the position which is necessary for weld control in its measuring view.
    Following results have been obtained by installing the PT in the ERW tube mill.
    (1) The temperature of the portion just before weld V point is suitable for the index to control heat input for weld, because it can be measured stably and well corresponds to heat condition of weld portion.
    (2) The highly stabilized weld control system have been achieved by combining feed-back control of weld temperature measured by the PT with feed-forward control for compensation of wall thickness fluctuation.
  • Improvement of Traceability for Radiation Pyrometers in the Steel Industry

    pp. 1052-1058

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    A traceability system for radiation pyrometers has been established. In this system a radiation pyrometer is calibrated beforehand at several fixed points, and it is used as the primary standard pyrometer. In the range of 800°C-1 350°C an automatic optical pyrometer is used as the primary standard and in the range between 500°C-800°C the 0.9 μm silicon-cell pyrometer is used.
    The emissivity of blackbody has been calculated by the integral equation method, and then the systematic errors have been evaluated as follows: The primary standard calibrated at the fixed points has an accuracy better than ±1K ; The secondary standard (Si-cell radiation pyrometers) has an accuracy better than ±2K, when calibrated by the primary standard. Radiation pyrometers can be calibrated by using the above secondary standard, and have an accuracy better than ±3K which is accurate enough for use in the steel industry.
  • Measurement of Burden Profile in Blast Furnaces and Analysis of Measured Results

    pp. 1059-1065

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    Three different types of burden profile meter used at blast furnaces, mechanical, micro-wave, and laser types, were developed during almost the same term. At present, these are used in actual operations of blast furnaces.
    Main characteristics of each type are as follows. They are mechanisms to drive the weight and to prevent the swing of it (mechanical type), one-antenna system and countermeasures to the power attenuation caused by the interference phenomenon (micro-wave type), and utilization of visible argon laser and data processing technique (laser type).
    Indices of measured burden profile are scattered even under the same charging condition. Statistical analysis and simulation model are effective for using the measured results in a usual operation.
    At the present stage, the micro-wave type is best mainly from the viewpoint of maintainability. Completion of a maintainance-free laser type is expected due to its excellent functions.
  • Optical Width Gauge for Hot Radiant Plates

    pp. 1066-1070

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    An optical width gauge for hot plates has been developed, which can be installed near the rolling mill without backlight equipment. The device consists of solid state linear image sensors, a signal processor and a microcomputer. Edge points of plates are detected by finding the steepest points in the video signals of the radiant images. Furthermore, highly resolved edge data can be derived from the discrete differential signals by calculating the quadratically interpolated peak points of the signals. The edge data are stable and accurate even if the temperatures of the objects are varied.
    This paper describes the method of detection for plate edges and experimental data concerned with the high resolving power. An application of the equipment is given for the camber display system which has been installed near the finishing mill in the plate shop and which displays the camber shape of plates immediately after finish rolling and gives useful information to mill operaters.
  • Flatness Measurement of Hot Strip by Laser Scanning Method

    pp. 1071-1077

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    A new type of hot strip shape meter is developed to measure the flatness shape of hot strip at the exit of hot finishing mill with high accuracy and fast response time. This shape meter detects the strip vertical displacement distribution along transversal direction using laser beam, and measures the flatness shape from the variance of displacement. Laser beam from Ar laser is parallel scanned by high speed polygonal mirror and parabolic mirror, and irradiates the strip surface aslant. The strip displacement is measured by detecting the reflected light timing, with photo sensor arranged upper part of the strip. By sample test, it was confirmed that the accuracy of displacement sensing is within ±1mm. This shape meter was installed on the hot strip mill of Yawata Works in 1982 for practical use, and has been playing an important part in mill operation and in automatic shape control system.
  • Development of Plate Flatness Meter Based on Light Section Method on Hot Rolling

    pp. 1078-1082

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    The hot plate flatness meter has been developed in order to improve yield ratio and quality of products in the plate mill. It consists of an Ar laser, a rotating mirror with eight facets, a TV camera and an image processor, and the principle of measurement is based on the light section method. The plate flatness meter can measure the elongation rate of hot plates even if the temperature is around 1000°C within an average error of 0.04% by using an image processing technique.
  • わが国におけるプロセスコンピュータ設置台数の推移/エレクトロニクスの進歩/我が国における鉄鋼の研究開発投資/ECにおける計測の研究・開発/理論と実際のギャップ/他産業における計装技術者集団

    pp. 1082-1082,1138

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  • Development of Plate Sizing Apparatus for Plate Finishing Yard

    pp. 1083-1087

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    Plate sizing apparatus was developed and installed in the hot plate shop at Kakogawa Works of Kobe Steel Ltd. in March, 1981.
    The apparatus consists of five parts: (1) a fixed measuring deck, (2) a movable measuring deck, (3) a spray marker, (4) contollers, and (5) an operation room. It was designed to be semi-automatic system in order to increase flexibility. The system was simply composed, making effective use of laser markers and television cameras.
    Its functions are as follows:
    (1) Determination of the cutting position of a plate, after checking the front shape.
    (2) Marking a cutting line at the position automatically.
    (3) Measuring the width and the effective length of the plate.
    Adoption of digital position contoller and rack-pinion mechanism have realized high measuring accuracy, that is ±3mm in width, and ±30mm in length.
    This apparatus has been contributing to saving man-power and releasing workers from manual works under high temperature environment.
  • On-line System for Measuring Thickness of Hydrated Chromium Oxide Film on Tin Free Steel

    pp. 1088-1094

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    Hydrated chromium oxide (CrOX) layer on Tin Free Steel (TFS) is an extremely thin film, from about 50Å to 250Å in thickness. CrOX film thickness is an important factor for TFS to have corrosion-resistance and lacquer adhesion. An advanced on-line system for measuring thickness of CrOX film has been developed.
    The main features of the instrument are as follows:
    (1) Spectral reflectance mainly at ultraviolet wavelengths are measured, and the thickness is calculated from those multi-wavelength reflective curve.
    (2) It has very simple structure, and consists of three main parts, that is, Hg-lamp, rotary filters, and integrating sphere with photomultiplier. Thus, it has good stability against various kinds of disturbances which occur at on-line measurement.
    (3) Measurement is done nondestructively and continuously.
  • Analysis of Light Reflection from Cold-rolled Steel Sheets and Its Application to On-line Measurement of Surface Roughness

    pp. 1095-1102

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    The relation between reflected light intensity and surface roughness parameters was analysed by numerical calculations based on BECKMANN'S theory. In addition, detailed analysis was made in case that the statistical characteristic of surface topography deviated from the one assumed in the theory.
    From these considerations, the conditions appropriate for surface roughness measurement were selected in terms of the incident angle and wavelength of a light beam. The experiments under these conditions gave good results for different kinds of steel sheets.
    These results lead to the development and installment of an on-line roughness measurement system in a TPL, (temper and processing line) of Chiba Works.
    x

    Readers Who Read This Article Also Read

    1. 日本鉄鋼協会第108回講演大会 講演概要集(II) その3 Tetsu-to-Hagané Vol.70(1984), No.13
    2. 日本鉄鋼協会第108回講演大会 講演概要集(II) その7 Tetsu-to-Hagané Vol.70(1984), No.13
    3. 日本鉄鋼協会第108回講演大会 講演概要集(II) その9 Tetsu-to-Hagané Vol.70(1984), No.13
  • Measurement of Hot Metal Level in a Torpedo Car by Microwave

    pp. 1103-1109

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    Microwave type hot metal level meter in a torpedo car was developed by Kawasaki Steel. One point of development is an improvement in gain and directivity of the antenna by the use of parabola type, and the other is an improvement in signal processing by microprocessor. It achieved the measuring accuracy ±50 mm.
    This level meter was installed at Chiba No. 6 blast furnace for practical use and has been working satisfactorily. It has contributed to lightening the operators' load for watching and increase in efficiency of hot metal transportation.
  • Ultrasonic Displacement Meter with Water Column for Hot Steel Product

    pp. 1110-1115

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    We adapted an available displacement meter for measuring the shape of the hot steel product in the continuous casting machine and the rolling mill. The meter is an ultrasonic level one, but it uses a water column instead of atmosphere as the propagation medium.
    The characteristics of the meter are summarized as follows:
    (1) Its effective range is about 100 mm, and the resolution is 0.05 mm.
    (2) It is strong and reliable with usage of water column, therefor useful for in-line measurement.
    (3) It is useful for the hot steel product as a target.
  • Dimension and Shape Measurement Using Water Column Distance Meter

    pp. 1116-1122

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    The technology of the dimension and shape measurement of steel products is one of the most importantΔbases on the quality control of steel production process.
    Kawasaki Steel Corporation has developed an excellent measurement technique which employs "water column method" to meet with strict requirements such as inconvenient environment, on-line continuous measurement and others.
    The water column method is based on two kinds of principles. One is the ultrasonic measurement. Ultrasonic pulses are transmitted and received via water column to and from the object. The distance to the object and its thickness can be obtained from time intervals between echo pulses. The other is the electric resistance measurement. A constant electric current is fed to a water column which connects an electrically insulated fixed nozzle with an earthed object. By measuring the electric potential of the nozzle, the length of the water column, which shows one of the factors of the object's shape, can be known.
    Five of on-line applications are as follows:
    1) Thickness and outer/inner diameters measuring system for medium seamless pipes.
    2) The same system for small seamless pipes as mentioned above.
    3) Width gauge for hot sheet bar at hot strip mill.
    4) Edger roll position sensor at heavy plate mill.
    5) Flatness measuring system for hot strip.
  • On-line Measurement of Solidification Shell Thickness and Estimation of Crater-end Shape of CC-slabs by Electromagnetic Ultrasonic Method

    pp. 1123-1130

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    To establish the technique for producing very high temperature steel slabs required in a continuous casting-direct rolling process, the measurement method for the solidification shell thickness of a continuous casting steel slab has been developed using the electromagnetic ultrasonic technique, and industrialized at Sakai Works, Nippon Steel Corporation. The main features of this method are as follows:
    (1) On-line, real time, non-contact and continuous measurement is done at every 15 seconds.
    (2) Sensors are transversally scanned and the measurement is done at any desired points.
    The measurement error was determined to be 1.2 mm (standard deviation) by comparing the measured results with the destructive method, driving a special aluminum plated rivet into a slab of 250 mm in thickness.
    Combining the shell thickness measurement with the two dimensional solidification simulation, the estimation method for the location and the shape of the crater-end (solidification completion end) was also developed.
    In the real operation of the continuous casting machine, the shell thickness variation due to the casting speed change was clearly measured and moreover, the interesting shape of the W-figure type craterend was obtained. This measurement system has become very useful for the stable operation of the continuous casting machine and is now working very well.
  • Development of the Wall Thickness Measuring System Using the Electromagnetic Acoustic Technique for Hot Seamless Steel Tubes and Pipes

    pp. 1131-1138

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    The electromagnetic acoustic transducer system has been developed for the measurement of hot seamless steel tubes and pipes. The system consists of tunnel type electromagnet which generates the strong axial magnetic field around the pipe, and six sensors including transmitting and receiving coils which are arranged between poles and around the pipe. The system can measure 6 circumferencial points wall thickness of the pipe at the rate of 250 Hz.
    The ultrasonic properties in hot steel such as velocity and sensitivity have basically been investigated. The measuring accuracy of the system has also been investigated in the laboratory and at No. 1 tube making plant in Kainan Steel Tube Works of Sumitomo Metal Industries, Ltd. The basic experiments showed that ultrasonic velocity can be calculated by measuring the surface temperature, and that the sensitivity changes due to the changes of air-gap and surface temperature can be compensated by AGC (automatic gain control) circuit. The system was positioned at the outlet of the finishing stand of the stretch reducer mill, and pipes of various sizes (42.7 mm-177.8 mm dia.×3.2-25 mm thickness) were produced to measure the wall thickness. The results showed that the measuring accuracy was less than±0.1 mm.
  • Hot On-line Wall Thickness Gage System for Seamless Tubes

    pp. 1139-1145

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    Kawasaki Steel Corporation has developed an on-line wall thickness gage with joint efforts of Fuji Electric Co., Ltd.. The development took four calender years. This gage was developed for the first time in the world, and started on-line use in October, 1981.
    This gage utilizes γ-rays and is possible to measure continuously the wall thickness along the longitudinal direction of pipe to an accuracy of 0.1 mm and a response speed of 0.1 second with no physical touch. Principle of measurement of this gage is named multi-beam method which is based on a premise that three γ-ray beams forming triangular shape cross each other within the pipe wall thickness.The wall thickness gage utilyzes micro computer systems effectively. Particurally analyzing the twist angle of the wall thickness deviation, FFT (Fast Fourier Transformer) was used at first time for on-line analysis.
    With the running of this gage system, the suitable action on the wall thickness control has been established in seamless tube production line. As a result, this gage system has advanced the new tube production technology and improved the dimensional quality of seamless tube.
  • Measuring Technic of Lumpy Zone in the Blast Furnace and It's Application

    pp. 1146-1152

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    A monitoring system for lumpy and cohesive zones in the blast furnace has been developed to help clarify the phenomena ocurring in the furnace and stabilize blast furnace operation. This system consists of hardware which measures the condition of gas and burden, and mathematical model which estimates the state in the furnace using the data obtained by the hardware. New sensors, such as a gas velocity meter using a hot wire velocity meter and a layer thickness meter using a magnetmeter, have been developed and practically applied to a blast furnace. The state in the blast furnace can be precisely clarified by these sensors and the model.
  • Development of Double Sheathed Multiple Thermocouples and Analyzing Method of Lining Erosion of Refractory Wall

    pp. 1153-1159

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    The lining erosion measuring system for blast furnace has been developed. This system consists of double sheathed multiple thermocouple (FMT Sensor : Fine Multi Thermo-Sensor) and computer software for the estimation of lining erosion of refractory wall (Trigger-Response method).
    The sensor can simultaneously measure the temperature variations at a number of positions across the thickness of the lining. The Trigger-Response method can calculate the remaining thickness of lining by analyzing the time-delay occuring in the propagation of temperature variations in the lining. By analyzing the signals out of FMT-Sensors by the Trigger-Response method, the extent of erosion of the refractory lining is estimated within an error tolerance of less than 5%.
    These techniques have been successfully systematized to on-line lining erosion monitoring system for blast furnace. Also, this paper describes the newly developed Ansatz Measuring Sensor of which principle is based on the application of FMT-Sensors. It is considered that signals out of FMT-Sensor may carry the useful data as operation guidance for blast furnace.
  • The Eddy-current Type Continuous Casting Mold Level Meter

    pp. 1160-1166

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    In the continuous casting (CC) process, it is technically of great importance to measure accurately the level of molten steel in the mold and to keep the level constant, because this results in the more stable casting operation and the improved casting quality.
    The development has been made on an eddy-current CC mold level meter based on the method of a positive feedback amplification. This new non-contact level meter is capable of measuring the molten steel level without the influence of the mold powder. An accuracy of the level meter is ±1mm under a quick response. Moreover, aΔdifferential type of the detecting coil has been developed from a theoretical analysis of the electro-magnetic field of the level meter. This type of the level meter is more stable against an influence of the environmental condition, such as a position of the mold wall. By using the differential type, a small sized level detector of which diameter of 30 mm is realized and it can be applied to a billet casting with a smaller cross-section.
    The eddy-current type mold level meter is in use not only at NKK's Keihin and FukuyamaΔWorks, but also abroad, to improve the CC technology.
  • Cold Strip Shape Estimation Using Plate Vibration Analysis

    pp. 1167-1174

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    In cold strip mills, strip is usually rolled under longitudinal high tension, where the strip wavy shape is not visible directly because of the longitudinal elastic deformation.
    To detect the strip shape indirectly during rolling, the strip vibration principle has been applied, and various kinds of shape meters have been developed so far. To clarify the measuring principle of these shape meters precisely, the authors carried out the analysis for the strip vibration by solving the differential equation strictly. Here transverse tension distribution which corresponds to the implicit strip shape is perturbed, and the state of strip vibration can be figured out by using perturbation method. As a result, the relation between the strip vibration and its shape is clarified. It is concluded that the strip shape can be estimated through the measured vibration amplitude distribution by applying some restricted outer force onto the strip.
  • Non-destructive Inspection

    pp. 1175-1180

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  • On-line Inspection Techniques for Surface Detects of Hot Slabs

    pp. 1181-1187

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    The steel industry has recently started the directly-linked steelmaking-rolling process in order to save energy. One of the techniques supporting this process is the hot slab surface flaw detection. Various methods have been developed to satisfy this need. So far, the optical method, eddy current one, and induction-heating one have been commercialized and are contributing to quality assurance of the continuously cast slabs in steel industry.
    This paper presents the characteristic features of each method and also the detail of the induction-heating surface-flaw inspection system developed by Nippon Steel Corporation.
  • The Development of a Surface Flaw Inspection System for Hot Continuously Cast Slabs

    pp. 1188-1193

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    A surface inspection system for hot continuously cast slabs has been developed. The system was designed so as to automatically detect harmful longitudinal cracks, with a width over 0.5 mm and a length over 50 mm, discriminating them from longitudinal dents. The principle of crack detection is based on the fact that a shadow is produced only at a crack by an appropriate lighting condition. Longitudinal cracks are automatically recognized, using an image processing technique, from the image of slab surface obtained by a line scan camera under the lighting condition.
    Prototype equipment was manufactured and provided to experiments in order to confirm the performance of the system. On-line experiments showed good results under the good surface condition, namely, the system could inspect harmful longitudinal cracks on the slab surface travelling at a speed of 60 m/min in a real-time manner.
    Based on these experimental results, the on-line equipment inspecting longitudinal cracks is now planned to be installed in Fukuyama Works of NKK.
  • Automatic Surface Inspection System for Hot Rolled Slabs by Real Time Image Processing Method

    pp. 1194-1201

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    An automatic surface inspection system for grading hot slabs during the direct rolling process is described. The system, based on an optical method, employs CCD (Charge Coupled Device) line-scan cameras and real-time signal processors. CCDs can take hot radiant images of the moving slabs with high resolution. The signal processors, which use advanced image processing techniques, can perform the following functions. Firstly, the background level of the image of the slab can be correctly detected. Secondly, ill-defined signals caused by harmful defects can be discriminated with high signal-to-noise ratio. Thirdly, two-dimensional patterns associated with defects can be recognized.
    The effects obtained when the system is applied to operation are discussed. The ability of the system to detect dark and gray defects is comparable with that of human visual inspection. The system is now in successful operation in the direct rolling process.
  • Eddy Current Inspection for Continuously Casted Slabs in a Production Line

    pp. 1202-1209

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    Eddy current inspection methods for continuously casted slabs under hot stage have been developed. In order to suppress the signal caused by oscillation marks, several signal processings are discussed. A new signal processing combined with multifrequency eddy current testing and signal pattern analysis can detect fine transverse cracks at the bottom of oscillation mark.
    An eddy current testing system with a spot scarfer for the detection of subsurface cracks is operating in Kashima Steel Works of Sumitomo Metals. The scarfing nozzel is used for both smoothing the surface before eddy current inspection and removing cracks by the inspection results.
    These methods can detect cracks whose depth is 2mm, and will greatly contribute to the expansion of hot charge rolling process (HCR).
  • Automatic Ultrasonic Inspection for Surface Flaws of Square Billets

    pp. 1210-1215

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    The new automatic ultrasonic inspection system using the surface wave technigue has been developed for the detection of surface and sub-surface flaws of square billets. The high speed and reliable inspection is performed with this system. This paper describes the basic and on-line experimental results of the technique and the outline of the system. The system has been installed at Kokura Steel Works of Sumitomo Metal Industries Ltd.
    The following results are obtained from the experiments.
    (1) More than 95 percent natural surface defects deeper than 0.5 mm can be detected.
    (2) It is observed experimentally that the sub-surface flaw of 1.5 λ (λ : wave length) in depth from the surface can be detected by the surface wave technique.
  • Fully Automatic Inspection and Removal System of the Defects in Square Billets

    pp. 1216-1221

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    The pattern recognition techniques have been applied to fluorescent magnetic particle testing for automatic inspection of defects, and a development has been made on automatic conditioning machine that can remove defects accurately even on slightly curved billets.
    Installing the defect inspection equipment and the conditioning machine on a transfer line that is controlled by a process computer, the authors have established a fully automatic inspection and removal system for the defects of spuare billets.
    Emphasis is placed in this paper, on showing the mechanism of the defect inspection equipment and the conditioning machine, and features of the whole system, including the transfer system.
  • Magnetic Particle Inspection Technique for the Entire Surface of the Large Diameter Pipe

    pp. 1222-1227

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    In order to improve the surface quality assurance of the pipe, Nippon Kokan K. K constructed the magnetic particle flaw detection equipment for the complete outside and inside surface of the pipe.
    Magnetic particle inspection has been used for a long time, but not a few techniques have depended on customary practice. Then, we investigated theoretically diffusion of magnetic flux and method of evaluation of residual magnetism.
    The results obtained are summarized as follows:
    (1) The theoretical model for a calculation of residual magnetism is made.
    (2) The new method of evaluation of residual magnetism by artificial defects is established.
    The magnetic particle flaw detection equipment for the large diameter pipe, that was installed based on the previous investigations, has been running favourably since June 1983.
  • The Development of a Moisture Measurement System for Blast Furnace Coke

    pp. 1228-1234

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    Conventional neutron moisture gauges for blast furnaces have poor accuracy caused by a measuring principle itself, that is ±2wt% when measuring moisture content of 5wt%. In order to solve the problem of accuracy, a new method of moisture measurement for blast furnace coke has been developed, using transmission of fast neutrons and γ-rays from 252Cf. In this method, an organic scintillator and pulse counter system which has pulse shape discrimination properties are used to detect fast neutrons and γ-rays simultaneously, and it enables the measurement of moisture and bulk density at the same time.
    A moisture gauge using this method shows good linearity over a wide moisture range permitting measurements with a very high accuracy of ±0.5wt%. Further, it can measure the moisture of coke accurately even if wet coke and dry coke are present in a mixed state in the coke hopper. Therefore this moisture gauge is suitable for blast furnace operations which aim at precise heat level control.
  • Development of Quality Control SystemΔfor Sintered Ore

    pp. 1235-1241

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    The quality measurement system has been developed in order to control RDI (Reduction Degradation Index) of sintered ore. It consists of the measurement systems of free carbon contents from an exhaust gas analysis, FeO contents in raw materials, particle size distribution of coke breeze and FeO contents in sintered ore.
    After sufficient results were obtained about each measurement system, these systems were adopted in sintering plant as a total system. As a results, the quality indices of RDI of sintered ore can be controlled fairly stable by making use of this system.
  • A Study on an Oscillating-plate Viscometer for Instantaneous and Simultaneous Measurements of the Viscosity of Melts and the Noise with their Chemical Reactions

    pp. 1242-1249

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    In order to understand various phenomena in the metallurgical processes, a new oscillating-plate viscometer using a non-contact electro-optical system connected with a signal separator has been made on an experimental basis.
    The apparatus allows us not only to give instantaneous and continuous indications of the product of density and viscosity (ρμ) of a liquid being in a state of unsteady flow with fair accuracy, but also to make simultaneous measurements of ρμ and noise during chemical reaction.
    It is expected that the data obtained experimentally on the changes in viscosity and noise with slag/metal reactions may provide us any useful information about a degree of chemical reactions and dynamical behaviour of the reaction products.
  • Effect of Phase Composition in Solid Electrolytes of ZrO2-8.1 mol%MgO on Oxygen Activity Measurement in Molten Steel

    pp. 1250-1255

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    Thermal-shock resistance and response performance of solid electrolytes for an oxygen probe applied in steelmaking processes were studied. One-end closed tubes of ZrO2-8.1 mol% MgO with various volume fraction of cubic phase (Vc) were used for measuring oxygen activity in a production line, and changes of phase composition in ZrO2 during immersion into molten steel were investigated. Good thermal-shock resistance was realized by decrease in the cubic phase whereas good response performance was obtained by increase in the cubic phase. For the ZrO2-8.1 mol% MgO, an optimum fraction of cubic phase was 27%. The relationship between reliability of measured oxygen activity and the phase composition was also discussed.
  • An Application of the Optimal Control Theory to the OG Pressure Control System

    pp. 1256-1261

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    In the OG pressure control system equipped by only PI controller, there existed the problem that was very slow to respond to violent process fluctuations. The optimal control method was applied to improve this problem. Instead of installing another new sensing device, the existing sensing facilities were used and modification was made on the process variables which were measured by them. The higher controllability was achieved by means of the compensation of the delay time of the PI controller by identifing the process characteristics using higher differential equations.
    In this paper, the new control system achieved by the method mentioned above is described. It is clearly indicated that the new method is very helpful in obtaining a high rate of LDG recovery.
  • Development of Measuring System for Friction in Continuous Casting Mold

    pp. 1262-1268

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    It is very important for the Continuous Casting (C.C.) process to stabilize the operation and keep high quality of the slabs. An investigation has been made of a method for preventing surface defects of C.C. slabs generated in the mold. Generation rate of surface defects is dependent on the powder flow condition between the mold and slabs. The method is based on friction measurement which is made by observing the transfer characteristics of the omld oscillator. Several facts affecting the friction have been found as follows:
    (1) The friction force changes depending on several conditions of C.C. operation, especially on the casting speed and on the mold oscillation frequency.
    (2) Under the constant operating conditions mentioned above, fluctuations of the friction inform the dynamical behavior of the stability between the mold and slabs. The surface defects can be predicted by watching the level of the fluctuation.
    (3) The estimation possibility of predicting a sticking type breakout can reach about 60% by this method.
    Finally the system has been established to mesure the friction betwreen the mold and slabs dynamically, continuously and quantitatively.
  • New Tension Measurement and Control System in Hot Strip Finishing Mill

    pp. 1269-1276

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    In the hot strip finishing mill, the range of the strip dimension has been widened as represented by rolling the high grade heavy line pipe material. On the other hand, the dimensional accuracy of the strip is also required to be further improved. Hence, the loopers in the finishing mill must have a large scaled mechanical frame to lift up the interstand heavy material. This scale up of the looper frame inevitably reduces its tension control performance especially for the light interstand material to disturb the product dimensional accuracy.
    To cope with this problem, the authors developed full stand looperless tension control system for heavy material by adopting statistical processing scheme to estimate the rolling model parameters and realizing accurate tension measurement using rolling moter information. This was successfully applied to the hot strip mill (HSM) of Keihin Works, NKK.
    This resulted in developping a new rolling method characterized in that the loopers are designed only for the use of light material to control fine tension to improve the dimensional accuracy of the HSM products.
  • Apparatus for the On-line Telescopic Color-Spectrophotometry

    pp. 1277-1284

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    The surface color difference of steel sheets, especially of colored galvanized sheets, is one of the most important factors to be measured. The measurement is usually carried out by 'on-line' or 'off-line' visual inspection, or by 'off-line' instrumental one, but it has not been done by 'on-line' instrumental one.
    Through a strong request to establish automatic inspection technique for on-line use, a new inspection system has been developed. In this system, two light-sources illuminate a travelling sheet with the intensity of more than 105 lux.A high speed data processor provides the spectral reflective property of the illuminated sheet surface. Remote inspection of the instrument has an advantage that it can be installed in almost any production line. On-line performance tests have proved high reliabilityof the instrument ; the values of the color difference measured by this instrument coincide within ±0.2 with those measured by an 'off-line' sampling test with a spectrophotometer. Applying this instrument to the production line, the color difference of the sheet to its standard color is successfully measured over the whole length of a coil. It is resultantly expected that the control of the color difference in the production line will be realized with this instrument.
  • Progress and Technical Trend of Process Analyzer

    pp. 1285-1291

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  • The Development of Condition Diagnosis Technology

    pp. 1292-1298

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    Condition Diagnosis Technology has replaced manpower with condition monitor and can detect the deterioration of equipments, but has a problem not to be linked with the quality of products. To search the profound connection with equipment and quality, authors have been developing Process Diagnosis Technology being applied to profile control of coiled hot strip which is influenced by a side guide or a mandrel.
    Process Diagnosis Technology consists of two main techniques, one is software such as Discriminant function method, the other is Online Realtime Analyzer-as epitomized by Realtime transfer function analyzer(RFA) and Thyristor fail tracer (TFT). RFA takes only a few minutes to diagnose, as for TFT enable real time observation of the movement of gate pulse signal of Thyristor devise at a moment.
    The result of this research and development introduced in a number of process is applicable to almost all equipment.
  • Current Sensors in Industrial Measurement and Control

    pp. 1299-1304

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  • A Review of New Measuring Instruments Technologies in Steel

    pp. 1305-1310

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  • Progress of Measurement and Control in Iron and Steel Industry

    pp. 1311-1312

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