JPH0465744B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an apparatus for measuring the thickness of a molten liquid layer (powder molten layer) of powder introduced into a continuous casting mold.

(Prior art and its problems) In continuous casting equipment, measuring the thickness of the molten powder layer on the surface of molten steel is extremely important in order to produce high-quality slabs and prevent operational troubles such as breakouts. is important.

Conventional electrode-type powder molten layer measurement equipment measures the resistance value in each layer by lowering a probe into the mold from above at a constant speed, and utilizes the fact that the resistance value changes discontinuously as it passes through each layer. The purpose is to measure the powder melt thickness by measuring the time interval when the discontinuity point passes. However, this conventional device has no choice but to perform intermittent measurements. Measurement errors due to fluctuations in the hot water level during measurement cannot be avoided. Since there is a tundish, etc. above the mold, it is difficult to install the probe, its vertical movement mechanism, etc. above the mold, which is an unavoidable problem. Furthermore, in place of the above-mentioned electrodes, a measurement method has been proposed in Japanese Patent Application Laid-Open No. 57-56146 that uses ultrasonic waves and takes advantage of the fact that in the molten powder region, a characteristic waveform occurs due to reflection from the surface of the molten steel. ,
In addition to the same problems as the electrode type, there are also problems such as adhesion of molten steel to the measurement terminal or melting damage.

In addition, the temperature measurement type powder molten layer measuring device is
Iron wire melts in molten steel, but remains unmelted in the molten powder layer, while copper wire melts in the molten steel and in the molten powder layer. Taking advantage of this fact, a rod-shaped object wrapped with iron wire and copper wire is inserted into the mold. The purpose is to measure the thickness of the molten powder layer by immersing the wire, taking it out after a few seconds, and measuring the difference in remaining length between the iron wire and the copper wire. However, this conventional device has no choice but to perform intermittent measurements. Measurement errors that occur due to human measurements such as how to determine the immersion time related to the amount of erosion, reading errors, etc., and measurement errors due to fluctuations in the hot water level during measurement cannot be avoided. There was no escape from the problem of being exposed to danger when working above the mold.

(Object of the Invention) The present invention was devised in order to solve the above-mentioned conventional problems, and an object of the present invention is to enable non-contact and almost continuous measurement of the thickness of the molten powder layer with high accuracy. .

(Structure of the Invention) The powder molten layer thickness measuring device in the continuous casting mold of the present invention includes a bar-shaped gamma ray source arranged along the vertical direction on one side of the opposing mold wall, and a vertically movable source on the other side of the mold wall. possible arranged γ
ray detector and a hot water level measuring device,
The present invention is characterized in that it is provided with an arithmetic unit that corrects the vertical position of the line detector based on the detected value of the hot water level measuring device.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

In the figure, 1 and 2 are opposing mold walls, and inside one mold wall 1, there is a rod-shaped γ-ray source 3 along the vertical direction that covers the fluctuation range of the powder molten layer B and the powder grain layer C. It is arranged close to the inner wall 4. Inside the other mold wall 2, a gamma ray detector, for example, a scintillation counter 5, is movable up and down by a moving device 7 to move the fluctuation range of the powder particle layer A and the powder molten layer B close to the mold inner wall 6. , and is arranged so that its position can be detected by a moving distance detector 8 provided in the device 7.

Reference numeral 9 denotes a conventionally known microwave or laser light type hot water level measuring device, which is disposed above the hot water level 10 between the mold walls 1 and 2. The device 9 injects microwave or laser light toward the hot water surface 10, captures the reflected wave from the hot water surface 10, and determines the hot water surface level based on the interference waves or incidence/reflection angles of the microwave or laser light. The structure is such that it can be detected.

(Function) The γ-rays emitted from the γ-ray source 3 pass through the molten metal layer A, the powder molten layer B, the powder particle layer C, and the air layer D, reach the scintillation counter 5, and their intensity is detected. Ru. On the other hand, the position of the scintillation counter 5 is detected by a moving distance detector 8.

The intensity of γ-ray is I=2.54×10 ⁶ [Ci]・∫ ^l ₀ 1/l ² dl・_o 〓 ⁱ⁼¹ Bi・e ¹ 〓 ⁱ

Claims (1)

[Claims] 1. A rod-shaped gamma ray source arranged along the vertical direction on one side of the opposing mold wall, and a gamma ray detector arranged vertically movably on the other side of the mold wall,
What is claimed is: 1. A CC powder molten layer thickness measuring device, comprising: a hot water level measuring device; and an arithmetic unit for correcting the vertical position of the gamma ray detector based on the detected value of the hot water level measuring device.