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2 Journal of Achievements in Materials and Manufacturing Engineering

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Quality control for the continuous casting process using electromagnetic transducers

Kim I. S., Son J. S., Kim H. J., Sung B. S.

Journal of Achievements in Materials and Manufacturing Engineering

2008

Vol. 31, nr 2

683-689

Purpose: The continuous casting process is controlled automatically because various sensors and control units are connected to the mold and lower tundish roll. The solidification point in the process has a major factor on the quality of products, but the point has been predicted depending on the inaccurate calculated results from a computer simulation until now. Therefore, the objective of this paper is to develop the EMAT sensors for the measurement of the solidification point made by a through transmission technique based on the relationship between ultrasonic speed and measured temperature. Design/methodology/approach: The EMAT sensor is composed of an Elongated Spiral (ES) forming an eddy current and a permanent magnetic core generating a static magnetic field. ES coils of the sensor to measure 0.08mm, 0.2mm and 0.45mm as solidification points were employed respectively. Probes for receiving and transmitting which included 4 permanent magnets measuring 5 x 5 x 10mm, were placed together in one unit. Each coil was used to magnetic cores measuring 0.08mm and 0.45mm wound around it forty three times. The AI 75 x 75mm and 75 x 100mm simulators to identify whether the solidification point can be detected using an EMAT sensor, were machined with 2mm, 4mm, 8mm, 16mm and 32mm holes in diameter respectively. Findings: The electromagnetic interaction decreases in a high sphere of lift-off. Solidification point in a continuous casting processing could be detected through a series of tests with the use of a fabricated probe and the amplitude extent of ultrasonic wave decreases as the hole diameter of the simulators increases, Furthermore, the sensor developed is useful for measuring things such as lift-off. Research limitations/implications: A considerable amount of time and energy for miniaturization of the sensor and construction of an on-line system for a field installation should be saved by reducing mistake ratio and curtailing unnecessary processes. Originality/value: The solidification point in a continuous casting processing could be detected through a series of tests with the use of the developed EMAT sensor.

A study on electromagnetic transducers for the continuous casting process

Kim I. S., Son J. S., Kim H. J., Chin B. A.

Journal of Achievements in Materials and Manufacturing Engineering

2006

Vol. 17, nr 1-2

357--360

Purpose: One of the areas in the continuous casting process that has not been definitively instrumented is a method for reliably locating the part of a continuously cast strand that remains liquid for a period after the outer portion has solidified. Therefore, this paper is focused on the measurement of the solidification point made by a through transmission technique based on the relationship between ultrasonic speed and measured temperature using an EMAT sensor. Design/methodology/approach: An EMAT (Electro Magnetic Acoustic Transducer) has been designed and fabricated with an elongated spiral coil and a permanent magnetic core. Al75×75mm and 75×100mm simulators with 2, 4, 8, 16 and 32 mm holes were produced and demonstrated that the location of the final solidification point during the continuous casting process can be monitored using a 1.0 MHz frequency. Findings: The solidification point in a continuous casting bloom could be detected through a series of tests with the use of a fabricated probe and the amplitude extent of ultrasonic wave decreases as the hole diameter of the simulators increases. Furthermore, through a test of lift-off effect it was found that the extent of amplitude decreases as lift-off increases, thus one of the most important factors for a field application. Research limitations/implications: As cutting speed and cutting length can be predicted from a miniaturization of the sensor and construction of an on-line system for a field installation, a considerable amount of time and energy can be saved by reducing mistake ratio and curtailing unnecessary processes. Originality/value: The measured ultrasonic waves allow for prediction of the casting speed necessary to correctly locate the liquid core and thereby maximize the benefits of soft reduction and the productivity of the machine.