JPS61271401A - Thickness measuring method for molten slag layer - Google Patents

Abstract

PURPOSE:To improve measuring accuracy, by immersing a pair of metallic wires of different melting poins into a molten metal meniscus inside a continuous casting mold for fusion and measuring distance of the fused points. CONSTITUTION:A pair of metallic wires 6 is constructed, fixedly in a parallel manner one to an other of a metallic wire 1 of melting point below temperature of the molten metal inside a casting mold and of that above temperature of molten slag covering said molten metal, and a low-temperature melting metallic sire 2 of the melting paint below the molten slag temperature. And, the pair of metallic wires 6 is suspended from the extreme and of a suspension 7 fastened to a mold cover 9. The end portion of the metallic wire 1 penetrates through unmolten 12 and molten layers 11 of synthetic slag spread over molten metal 10 inside the mold 8 for immersion into the melt 10. After holding this condition for 5-10sec, the pair 6 is taken out of the mold 8. And, the distance between fused ends of the metallic wires 1, 2 is measured for determining the thickness of the molten slag layer from this measured value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to a method for measuring the thickness of a molten slag layer in a mold in a continuous metal casting apparatus.

(Prior art) When metal is continuously cast using a continuous casting machine, the molten metal is poured into the mold for the purpose of keeping the surface of the molten metal warm, absorbing nonmetallic inclusions in the molten metal, and lubricating between the inner wall of the mold and the solidified shell. A varnish slag consisting mainly of minerals is sprinkled on the surface. The sprinkled varnish slag is melted by the heat from the molten metal, forming a molten slag layer on the surface of the molten metal with a thickness of several millimeters + 7 meters to several tens of millimeters.

Controlling the thickness of this molten slag layer is extremely important when operating a continuous casting machine, and if the molten slag thickness is inappropriate, slag scratches, pinhole scratches, and cracks may occur on the surface of the slab. This was a major impediment to operations, such as causing quality defects in the slabs such as scratches and making breakouts more likely to occur. For this reason, it is necessary to control the thickness of the molten slag layer to an appropriate thickness from the start to the end of casting.To this end, the method for measuring the thickness of the molten slag layer is to insert a steel wire from the surface of the molten metal in the mold. A method was used in which the total thickness of υ slag was detected based on the length of slag adhering to the surface of a steel wire that had been immersed and pulled up.

(Problem to be Solved) According to the conventional method, while the steel wire inserted from the surface of the molten metal is being pulled up from the molten metal, the unmolten layer varnish slag floating on the surface of the molten slag is deposited on the surface of the steel wire. It was not possible to clearly grasp the molten slag adhesion boundary line, and therefore it was difficult to accurately measure the molten slag layer thickness.

(Means for Solving the Problems) The present invention was made to solve the problems of the prior art, and its characteristics are that the temperature of the molten metal injected into the continuous casting device is lower than that of the molten metal, and the surface of the molten metal is coated. A metal wire having a melting point higher than the molten slag temperature and a metal wire covering the molten metal surface having a melting point lower than the molten slag temperature arranged in parallel to form a pair in a continuous casting mold. The metal wire pair is vertically inserted and immersed below the molten metal meniscus injected into the mold, the metal wire pair is fused by the molten metal and molten slag, and after being pulled up from the mold, the distance between the fused tips of the metal wire pair is measured.

The present invention focuses on the temperature difference between the molten metal and the molten slag, and uses a pair of metals having different melting points as described above to achieve the object.

(Example) The present invention will be explained in detail based on the drawings.

FIG. 1 shows a pair of metal wires for measuring the thickness of a molten slag layer used in the method of the present invention. 1 is below the temperature of the molten metal in the mold,
A high melting point metal wire 2 has a melting point higher than the molten slag temperature covering the molten metal surface, and 2 is a low melting point metal wire having a melting point lower than the molten slag temperature covering the molten metal surface. The high melting point metal wire 1 and the low melting point metal wire 2 are fastened in parallel to each other by a metal wire fastener 3 provided integrally with a support rod 4 so as to form a pair. FIG. 2 shows an embodiment of the method of the present invention using the metal wire pair 6 shown in FIG.

Next, an example of the method of the present invention during continuous casting of steel will be described. In Figure 2, the high melting point metal wire 1 has a diameter of 2
An aluminum wire with a diameter of 2fi was used as the low-carbon steel wire (C≦0.1%) gold and low melting point metal wire 2, and one end of each was aligned with the metal wire stopper 3 with the tightening bolt 5. The tip of the above-mentioned high-melting point metal wire 1 is attached to the tip of the hanging jig 7 fixed to the mold cover 9, and the unmolten layer 12 of the varnish slag is sprinkled on the molten metal 10 in the mold 8. It penetrates the fusible layer 11 and is immersed in the molten metal 10 to be molded. After maintaining this state for 5 to 10 seconds, the metal wire pair 6 is taken out of the mold 8. The distance between the fused steel wire and the aluminum wire to their respective fused ends was measured, and the molten slag thickness was obtained from this measured value.

As a result of repeating the above-mentioned measurements, the variation in the measured values was 0.5 to 2 pups. On the other hand, in the conventional method, there was a large variation of =LO to 2.6 degrees, and it was confirmed that the method of the present invention has excellent reproducibility and accuracy.

Note that the molten metal surface during continuous casting is not necessarily in a static state, and may be subject to slight natural vibrations or intentional vibrations. In such a case, the fused edges A and B have an abacus bead shape and are not straight. In such a state, when measuring between A and B, an accurate measurement value can be obtained by measuring from the central protrusion as a starting point.

(Effects) Since the metal wire pair can be inserted perpendicularly to the molten metal surface using an insertion dipping jig, the accuracy and reproducibility of the measured values are improved, and control corresponding to the thickness of the molten slag can be easily performed. This also made it possible to obtain high-quality slabs and solve various operational problems such as breakouts.

[Brief explanation of the drawing]

FIG. 1 is a pair of metal wires for measuring the thickness of a molten slag layer used in the method of the present invention, and FIG. 2 is a side view showing an embodiment of the method of the present invention. 1: High melting point metal wire 2: Low melting point metal wire 3: Metal wire stopper 4: Support rod 5: Tightening bolt 6: Metal wire pair 7: Hanging jig 8: Mold

Claims (1)

[Claims] A metal wire having a melting point below the temperature of the molten metal injected into the continuous casting device and above the temperature of the molten slag covering the molten metal surface is compatible with a metal wire having a melting point below the molten slag temperature covering the molten metal surface. Pairs of parallel metal wires are inserted vertically into a continuous casting mold to below the meniscus of the injected molten metal, immersed, the metal wire pairs are fused by the molten metal and molten slag, and after being pulled out of the mold, the metal wires are A method for measuring the thickness of a molten slag layer in a continuous casting device, characterized by measuring the distance between a pair of fusing tips.