JP3484969B2 - Online ultrasonic flaw detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an online ultrasonic flaw detector connected to a steel sheet processing line for performing various processing such as shearing. 2. Description of the Related Art An ultrasonic flaw detection test is often performed on a steel sheet after rolling or a steel sheet after heat treatment in order to ensure quality. Therefore, it is required to efficiently perform an ultrasonic flaw detection test on a steel sheet conveyed from an on-line accelerated cooling facility or a heat treatment facility installed on the exit side of a rolling mill. In an ultrasonic flaw detection test of a steel sheet, water is used as an ultrasonic medium between the ultrasonic sensor and the steel sheet, for example, as disclosed in Japanese Utility Model Application Laid-Open No. 62-62960. In practice, a water film is formed by spreading water on the upper surface of a steel plate, and scanning is performed while an ultrasonic flaw detector is brought into contact with the water film to perform a test. As described above, since water is used as a medium in the ultrasonic test, it is necessary to sufficiently lower the temperature of the steel sheet. Therefore, conventionally, the test was performed after cooling in a cooling floor. In that case, the cooled steel sheet was transported to an ultrasonic flaw detector or a test was conducted on the spot. For example, Japanese Patent Application Laid-Open No. Sho 62-30952 proposes a portable steel sheet automatic ultrasonic flaw detector. In this technique, a scanner for scanning the ultrasonic flaw detector, a rail for sending the scanner, a control carriage, and a water supply carriage are carried in and a test is performed. Japanese Utility Model Application Laid-Open No. Sho 61-48359 proposes a cooling device installed in an automatic ultrasonic inspection line upstream of the automatic ultrasonic inspection device. This device is a technology that includes a cooling water spray device and a temperature sensor, detects the temperature of a steel sheet, and performs cooling control to reach a set temperature. However, the test material is a heavy material such as a steel plate. In order to transfer the test material from the cooling floor to the test device, it is necessary to perform a transport operation using a crane, a bogie, or the like. There is. A crane and a truck on the cooling floor are installed to carry the steel sheet from the exit side of the rolling mill or the heat treatment equipment and carry it out to the next process such as a finishing yard. Therefore, the equipment capacity of the transport equipment is set for this purpose, and in order to carry the work to the test equipment, it is necessary to enhance the transport equipment. In the technique described in Japanese Patent Application Laid-Open No. 62-30952, an automatic ultrasonic flaw detector is installed on a steel plate before each test, and after the test, the device is removed from the steel plate in order to carry out the steel plate. Must. A signal cable, a water supply hose, and a power supply cable for moving the scanner, which are not described in the gazette, may be connected between the ultrasonic flaw detector and the control trolley, the water supply trolley, and the like. is necessary. In addition, it is difficult to automatically perform the test work and the work before and after the test work, particularly, the installation of the apparatus and equipment.
Since it depends on human labor, it is against labor saving.
Further, since the cooling floor is not originally a place for performing a test operation, it cannot be said that the working environment is good, and performing the test operation there has a problem in occupational health. [0010] In addition, since a control cart, a water supply cart and the like are also installed around the test material, a space for that purpose must be secured. It is also necessary to secure a work space on the cooling floor. In these conventional techniques, a cooling floor is used to cool a test material such as a steel plate to a testable temperature. Cooling in the cooling floor is basically natural cooling, and the cooling rate decreases as the temperature approaches room temperature. Therefore, it takes a very long time to cool down to a temperature at which the test can be performed, and there is also a problem that the ultrasonic flaw detection test reduces the production efficiency. In the technique described in Japanese Utility Model Laid-Open Publication No. 61-48359, cooling of a steel sheet is performed by a cooling water spray device installed on a transport line at right angles to the transport direction. When the cooling water is sprayed on only one side of the steel sheet as described above, a cooling strain is generated particularly when the cooling water is cooled from a high temperature range, and it may be difficult to detect a flaw. Although cooling control is performed based on the amount of cooling water, the control range is generally narrow only with the amount of cooling water, and cooling control is impossible. Further, in general, the processing speeds of the cooling water spraying device and the automatic ultrasonic flaw detection device are different, and the latter processing speed is high, so that cooling is generally insufficient. An object of the present invention is to solve the above-mentioned problems in the conventional method of cooling a metal plate, and to provide an ultrasonic flaw detector capable of improving production efficiency without the need to carry a test material such as a steel plate. With the goal. [0015] The present invention relates to an on-line ultrasonic flaw detector connected to a steel sheet processing line for performing processing in steel sheet manufacturing, wherein the ultrasonic flaw detector main body and a steel plate are provided upstream thereof. together with line cooling device for cooling the upper and lower surfaces is provided, the entrance side thermometer for measuring the inlet side of a steel sheet temperature of the line cooling device, and cooling to control the conveying speed of the steel plate passing through the line cooler A control device, the online cooling device
The installation direction of the cooling water nozzle is directed to the upstream side,
The cooling control device calculates the transport speed of the steel sheet required to cool the surface temperature of the steel sheet to a temperature that does not cause bubbles in water for the ultrasonic medium from the measured value of the entrance side temperature and the thickness of the steel sheet. An online ultrasonic flaw detector having a function. In the present invention, the treatment in the production of a steel sheet means various treatments in the production of a steel sheet, such as rolling, on-line heat treatment after the rolling, heat treatment, and shearing. Collectively. In addition,
The steel sheet temperature in these steel sheet processing lines is 200 ° C.
Before or after or more. Here, being connected to the steel sheet processing line means that means for automatically transporting the steel sheet from the steel sheet processing line, such as a transport roll, is provided, and as a result, it is necessary to perform a separate transport operation. Disappears. The on-line cooling device may be of any type as long as the steel plate can be cooled from both upper and lower surfaces and a certain amount of cooling water can be secured. By cooling the steel sheet from both the upper and lower surfaces, deformation such as warpage of the steel sheet in single-sided cooling can be prevented. The control range of the cooling capacity or the transport speed for determining the cooling water amount is as described below (the section of the embodiment).
What is necessary is just to determine according to the steel plate temperature from the connected steel plate processing line. The cooling control device calculates a required transport speed from the temperature difference to be cooled and the thickness of the steel sheet. The temperature difference to be cooled is the difference between the measured value of the entrance temperature and the target temperature. The calculation of the transport speed may be a heat transfer calculation, but can be easily performed by putting together past actual values and giving them by a table or an empirical formula. Such an arithmetic function can be easily realized by a microcomputer or the like. The target temperature for cooling the steel sheet is a temperature at which bubbles are not generated in water for the ultrasonic medium. Here, the temperature at which bubbles are not generated in water is because, when bubbles are generated in water for an ultrasonic medium, ultrasonic waves are irregularly reflected at an interface between the water and the bubbles, resulting in noise. This temperature is a temperature somewhat lower than 100 ° C., and varies depending on the conditions of the ultrasonic flaw detection test, but is usually 80 to 90 ° C. The cooling control device controls the transport speed of the online cooling device according to the calculation result. In this case, if the transport speed cannot be continuously controlled, the transport speed may be controlled to be equal to or lower than the calculation result. Since the apparatus according to the present invention can be connected to various kinds of steel sheet processing lines before the ultrasonic flaw detection test by a transfer table, there is no need to transport test materials such as steel sheets. In addition, since the steel sheet is cooled to an appropriate temperature by the on-line cooling device, it is possible to use an ultrasonic flaw detector using water as a medium even for steel sheets with relatively high temperatures immediately after various types of steel sheet processing, which reduces production efficiency. It is improved. FIG. 1 is a side view schematically showing one example of an embodiment of the present invention. The entire apparatus is connected to a steel sheet processing line 8 in a previous process by a transfer table 5. An entry-side thermometer 2 is installed at the entry side of this device, and transmits a measured value of the steel plate temperature to the cooling control device 3. The cooling control device 3 calculates a required transfer speed and controls the transfer speed of the online cooling device 1. The transport speed is controlled by the roll rotation speed of the transport table 5. The online cooling device 1 may be of any type, but here, a spray nozzle is used. About the lower surface of a steel plate, it cools also from a space between a conveyance roll using a spray nozzle. As specific equipment specifications, the line length of the cooling zone is 6 m, and the cooling water amount is 10 to 16
m ³ / min, and the transport speed is 0.1 to 1 m / s. Since the control range of the cooling capacity is small, the cooling control device 3 mainly calculates the transport speed. The difference between the measured value of the entrance temperature and the target temperature (here, 80 ° C.) is calculated, and the required cooling time t is calculated from the relationship between the plate thickness and the cooling speed in the online cooling device 1. FIG. 2 shows an example of the relationship between the plate thickness and the cooling rate. This figure is input to the cooling control device 3 in the form of a table, and is used for calculating the cooling time t. Needless to say, instead of the relationship between the plate thickness and the cooling speed, the relationship between the plate thickness and the cooling time or the relationship between the plate thickness and the transport speed may be directly input. Next, the cooling control device 3 divides the line length L of the cooling zone by the required cooling time t to obtain a transport speed V = L
/ T is calculated. These arithmetic functions are realized by a computer. In this case, the transfer speed is a four-stage speed change type, and the cooling time of the steel sheet is ensured by transferring at a transfer speed equal to or lower than the obtained transfer speed. The temperature of the cooled steel plate 9 is checked by the outlet thermometer 6 installed in the cooling device, and the steel plate 9 is inserted into the ultrasonic flaw detector main body 4. If feedback to the cooling control is performed using the measurement value of the outlet thermometer 6, more appropriate cooling control can be performed. In the ultrasonic test equipment main body 4, the steel plate 9
Is cooled to an appropriate temperature, so that a high-accuracy ultrasonic flaw detection test can be performed without generating bubbles or the like. Although the outlet thermometer 6 does not need to be installed, collecting the actual temperature results in optimizing the cooling condition of the on-line cooling device, studying the saving of cooling water, and the like. Further, as for the transport table of the online cooling device and the ultrasonic flaw detector main body, when the length of the steel plate such as a long object is long, it is necessary to synchronize both the rotations because it spans both. Therefore, it is preferable to control the speeds of both transfer tables by a signal from the cooling control device. In FIG. 1 described above, the transfer controller 31 controls the speed of the transfer table. When the transport control device 31 sends a signal to the flaw detection mechanism control device 32, the flaw detection mechanism control device 32 controls the ultrasonic flaw detection device main body 4 to perform ultrasonic flaw detection of the steel plate. Since the cooling water contains a large amount of air bubbles generated on the surface of the steel sheet, it becomes a noise in the ultrasonic flaw detection, lowering the measurement accuracy and making the ultrasonic flaw detection itself impossible. For example, in the technique described in Japanese Utility Model Application Laid-Open No. Sho 61-48359, a mechanism for performing ultrasonic inspection while cooling a steel plate is used, so that cooling water flows into the automatic inspection device. Therefore, it is desirable that the cooling water discharged from the on-line cooling device does not flow into the ultrasonic testing device main body. As one means for solving this, the installation location of the online cooling device is set to a position that is longer than the length of the steel plate from the ultrasonic test equipment main body. In this way, the steel plate does not enter the online flaw detector in both the ultrasonic flaw detector and the cooling water can be prevented from flowing into the automatic flaw detector. Alternatively , an on-line cooling device
Is located at a long distance from the ultrasonic testing equipment body
Instead, as another means, the jet direction of the cooling water nozzle is directed to the upstream side. Thereby, the water flow on the steel plate is guided to the upstream side, so that the cooling water can be prevented from flowing into the automatic flaw detector. In this way, it is possible to perform ultrasonic flaw detection without a decrease in measurement accuracy or the like. According to the present invention, since the ultrasonic flaw detector can be connected to various steel sheet processing lines, the work of transporting test materials such as steel sheets becomes unnecessary. In addition, since the temperature is cooled to an appropriate temperature by the online cooling device, the ultrasonic flaw detector using water as a medium can be used even immediately after various steel sheet treatments, and the production efficiency is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view schematically showing one example of an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a relationship between a plate thickness and a cooling rate. [Description of Signs] 1 Online cooling device 2 Inlet thermometer 3 Cooling control device 4 Ultrasonic flaw detector main unit 5 Transfer table 6 Outlet thermometer 8 Steel plate processing line (pre-process) 9 Steel plate 11 Nozzle 31 Transfer control device 32 Flaw detection Mechanism control device

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akira Murayama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (56) References JP-A-10-5846 (JP, A) JP-A Sho53 −44075 (JP, A) Fully open 1986-48359 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (1)

(1) An on-line ultrasonic flaw detector connected to a steel sheet processing line for performing processing in steel sheet manufacturing, wherein a steel sheet is vertically arranged on an ultrasonic flaw detector main body and an upstream side thereof. with online cooling device is provided for cooling from both sides inlet side thermometer for measuring the inlet side of a steel sheet temperature of the line cooling device, and the conveying speed of the line cooling device passing <br/> over the steel plate A cooling control device for controlling, wherein the online cooling device is configured to inject cooling water nozzles.
The direction is directed to the upstream side, and the cooling control device is configured to cool the surface temperature of the steel sheet from the measured value of the entrance temperature and the thickness of the steel sheet to a temperature that does not cause bubbles in water for the ultrasonic medium. An online ultrasonic flaw detector having a function of calculating a required steel sheet transport speed.