JP2007098400A - Continuous casting apparatus and method for measuring flowing rate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a flowing rate measuring accuracy of the molten steel by avoiding the bad effect caused by the thickness of solidified shell. <P>SOLUTION: A continuous casting apparatus 300 is provided with a mold 102 composed of one pair of water-cooled long wall sides, one pair of water-cooled short wall sides held to the interval of the one pair of water-cooled long wall sides and being adjustable to the casting width by parallel shifting with the one pair of water-cooled long wall sides, and a pouring nozzle 110 for pouring the molten steel into the casting space formed with the one pair of water-cooled long wall sides and the one pair of water-cooled short wall sides. This continuous casting apparatus is characterize by further including a flowing rate measuring part 310 for molten steel, fixed to the outer side surface of the water-cooled short wall side and composed of a primary coil 500 for generating AC magnetic field and a secondary coil 510 crossing at the right angle to the primary coil in the center axis and measuring the magnetic field with the primary coil and the magnetic field generated with the fluidity of the molten steel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a continuous casting apparatus and a flow velocity measuring method, and, for example, to a continuous casting apparatus and a flow velocity measuring method provided with a flow velocity measuring unit that detects a flow velocity of molten steel in a continuous casting mold of steel.

  In general, continuous casting of steel is performed by injecting molten steel into a water-cooled mold through an injection nozzle and continuously solidifying and drawing the molten steel while lubricating the molten steel with a lubricant called mold powder and vibration of the mold. The

  For example, when the mold is composed of a pair of water-cooled long sides and a pair of water-cooled short sides, the molten steel injected by the injection nozzle collides with the surface on the water-cooled short side (hereinafter referred to as the short side surface). In the molten steel pool, it is branched into two flows: a flow toward the meniscus (molten surface) and a flow toward the bottom of the molten steel pool. The upper and lower flows from the two discharge ports form four large vortices when viewed from the surface on the long side of the water cooling (hereinafter referred to as the long side surface).

  In the continuous casting of steel, the flow of molten steel dominates the flow of non-metallic inclusions contained in the molten steel, and the flow of molten steel itself is an important control target. Depending on the position where the molten steel flow is trapped by the solidified shell, it may cause scratches on the surface of the slab, or impurities may be carried inside the slab and cause defects.

  In particular, of the above flows, the asymmetrical flow seen from the long side is called a drift, and the amount and size of inclusions in the slab are increased, or the flow velocity of the meniscus is increased on one side. As a result of this increase, the powder that exists as a lubricant in the meniscus is entrained and transported into the slab. Therefore, it is necessary to detect and control the current drift.

  Conventionally, the rise of the meniscus on the short side of the meniscus is measured from the left and right when the meniscus rises and the kinetic energy is equal to the potential energy. Known detection means include a method of directly immersing a flow velocity measuring unit composed of a rod in molten steel, and a method of back-calculating the flow imbalance from the temperature difference of a thermocouple embedded in the copper plate of the mold.

  Moreover, the technique which detects the flow velocity of molten steel using an alternating magnetic field is also developed (for example, patent document 1).

JP 2002-336945 A

  The method of measuring the meniscus swell and the method of directly measuring the flow velocity in the prior art described above is a means of directly knowing the downflow related to the internal defect of the slab, although it is possible to know the left-right imbalance of the meniscus flow. It will not be.

  In addition, the thermocouple method can obtain not only the meniscus but also relatively lower information. However, as the molten steel descends from the meniscus, the solidified shell dissociates from the mold and the contact state changes constantly. There was a problem that it was difficult to grasp the flow accurately. Furthermore, a more fundamental problem is that the solidified shell gradually becomes thicker as it descends from the meniscus, and the flow velocity cannot be measured by a method that requires contact with molten steel.

  The present invention has been made in view of the above-mentioned problems of conventional molten steel flow velocity detection, and the object of the present invention is to avoid the adverse effect that the flow velocity detection accuracy of molten steel deteriorates due to the thickness of the solidified shell, It is to provide a new and improved continuous casting apparatus and flow velocity measuring method capable of increasing the flow velocity measurement accuracy of molten steel.

  In order to solve the above-described problems, according to the present invention, the casting width is adjusted by moving in parallel with the pair of water-cooled long sides sandwiched between the pair of water-cooled long sides and the pair of water-cooled long sides. Continuous casting apparatus comprising a mold comprising: a pair of possible water-cooled short sides; and an injection nozzle for injecting molten steel into a casting space formed by the pair of water-cooled long sides and the pair of water-cooled short sides. A primary coil for generating an alternating magnetic field, and a secondary coil for measuring a magnetic field generated by a magnetic field generated by the primary coil and a flow of the molten steel, with a central axis orthogonal to the primary coil. A continuous casting apparatus is provided, comprising a flow rate measuring unit for molten steel fixed to the outer surface of the water-cooled short side.

  With this configuration, it is possible to detect the flow velocity (flow velocity) of the molten steel flowing inside the pair of water-cooled short sides with high accuracy and fine resolution.

Further, the frequency f [Hz] of the alternating current flowing through the primary coil is
f ≦ 1 / {πμ ((√σ _Cu ) d _Cu + (√σ _Fe ) d _Fe ) ² }
(Where d _Cu : mold copper plate thickness [m],
d _Fe = k√ (H / v _c ): solidified shell thickness [m]
σ _Cu : Electric conductivity [S / m] of the mold copper plate,
σ _Fe : electrical conductivity of steel [S / m],
H: Vertical distance [m] from the meniscus (water surface) to the center of the height of the flow velocity measurement unit,
v _c : casting speed [m / min],
k: coagulation constant [m / min ^1/2 ],
μ: Magnetic permeability [H / m]. )
It may be expressed as With this configuration, it is possible to derive the frequency f of the alternating current suitable for detecting the flow velocity.

  The flow velocity measuring unit may be fixed to the outer surfaces of the pair of water-cooled short sides. With this configuration, it is possible to comprehensively observe the left and right flows as viewed from the long side surface, and to detect left and right drifts, unbalances, etc., and to perform more accurate control of the molten steel flow.

  In order to solve the above problems, according to the present invention, there is provided a flow rate measuring method for measuring a flow rate of molten steel flowing in a mold using the continuous casting apparatus, wherein an alternating current is applied to an outer surface of the mold. There is provided a flow velocity measuring method characterized by generating a magnetic field and measuring a magnetic field generated by the alternating magnetic field and the flow of the molten steel.

  Moreover, the flow velocity measuring part provided in the said continuous casting apparatus can also be provided as an independent apparatus.

  As described above, according to the present invention, it is possible to avoid the adverse effect that the molten steel as a measurement object is separated by the thickness of the solidified shell and the flow velocity of the molten steel cannot be measured accurately, and the flow velocity measurement accuracy of the molten steel is improved. By accurately grasping the internal state of the slab such as drift, it is possible to predict whether or not there is a possibility of defects in the slab, and the quality of the slab can be improved by flow control.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First Embodiment: Vertical arrangement of flow velocity measuring unit in continuous casting apparatus)
FIG. 6 is a schematic diagram for explaining the flow of molten steel in the conventional continuous casting apparatus 100. In continuous casting of steel, the injection nozzle 110 used in a state of being immersed in the molten steel pool 108 in the continuous casting apparatus 100 includes, for example, a mold 102 of the continuous casting apparatus 100 and a pair of water-cooled long sides. In the case of being constituted by a pair of water-cooled short sides that can be adjusted in the casting width by moving in parallel with the pair of water-cooled long sides, And an outlet 114. The inflow port 112 is formed in a cylindrical shape above the injection nozzle 110, and the discharge port 114 is opened with an inclination parallel to the long side of the mold.

  The molten steel 120 injected into the injection nozzle 110 collides with the short side surface and branches into two flows, a flow toward the meniscus (molten surface) and a descending flow in the molten steel pool 108. Four large vortices 122 are formed in the molten steel pool 108 by the vertical flow from the two discharge ports. Further, as the molten steel 120 descends the molten steel pool 108, the surface is cooled and becomes a solidified shell 124.

  In continuous casting of steel, the flow of the molten steel 120 dominates the flow of non-metallic inclusions contained in the molten steel, and this molten steel flow itself is an important control target. Depending on the position where the flow of the molten steel 120 is captured by the solidified shell 124, it may cause scratches on the surface, or it may be carried into the slab and cause defects. In particular, among the above flows, the asymmetrical flow seen from the long side is called drift, and it is necessary to detect and control the drift. Conventionally, the flow rate measuring unit 130 for detecting the flow rate of molten steel as described above has been installed separately from the mold 102 below the continuous casting apparatus 100 shown in FIG.

  In this way, by arranging the flow velocity measuring unit 130 outside the short side surface of the continuous casting apparatus 100, it is possible to measure the left and right drifts. However, the conventional flow velocity measuring unit 130 attached below the continuous casting apparatus 100 is suitable for detecting the accurate flow velocity of the molten steel 120 because a solidified shell having a predetermined thickness exists between the molten steel 120 and the molten steel 120. There wasn't.

  FIG. 7 is a schematic diagram for explaining the problem of the detection of the flow velocity depending on the position of the flow velocity measuring unit 130. In this schematic diagram, the lower part of the continuous casting apparatus 100 shown in FIG. 6 is extracted. Referring to FIG. 7, in the molten steel pool 108 of the continuous casting apparatus 100, the molten steel 120 moves toward the bottom surface of the continuous casting apparatus 100 at a flow velocity v, and the flow velocity is slow based on a drop in ambient temperature during the movement process. A solidified shell 124 is obtained. In particular, the thickness of the solidified shell 124 gradually increases as compared with the molten steel 120 below (on the bottom side) the continuous casting apparatus 100 as shown in FIG.

Originally, the flow velocity to be detected by the flow velocity measuring unit 130 is the flow velocity v of the molten steel 120 flowing inside the molten steel pool 108. A magnetic field (magnetic flux) B output from the flow velocity measurement unit 130 to measure the flow velocity v penetrates the molten steel pool 108 through the side wall of the continuous casting apparatus 100. However, in the molten steel pool 108, there are mainly two types of movements such as the lowering of the molten steel 120 and the lowering of the solidified shell 124. Flow rate measurement unit 130, the flow rate of the flow velocity v and the solidified shell 124 of the molten steel 120, that is, to detect the synthesized velocity and casting speed v _c, it can not be resolved both velocity v, v _c. Therefore, the accurate flow velocity v of the molten steel 120 cannot be measured.

  What is detrimental in measuring the flow rate of the molten steel 120 is the thickness of the solidified shell 124 interposed between the flow rate measuring unit 130 and the molten steel 120, particularly the solidified shell 124. Therefore, in order to solve the above problem, the position of the flow velocity measuring unit is moved above the continuous casting apparatus 100, that is, to the meniscus side where the solidified shell 124 is not yet thick. Specifically, it is installed in the mold 102.

  FIG. 1 is a schematic diagram for explaining the flow of molten steel in the continuous casting apparatus 300 of the present embodiment. In the continuous casting apparatus 300, the molten steel 120 discharged from the injection nozzle 110 forms four large vortices 122, as shown in FIG. As the molten steel 120 moves below the molten steel pool 108, it changes from the surface to the solidified shell 124.

  In FIG. 1, the flow velocity measuring unit 310 is embedded in the side wall of the mold 102 of the continuous casting apparatus 100. Since the position of the flow velocity measuring unit 310 shown in FIG. 1 is short from the meniscus, the width of the solidified shell 124 is not yet thick, and the flow velocity v of the molten steel 120 measured by the flow velocity measuring unit 310 is accurately detected. It becomes possible to do.

  By the way, in the direct process in which the continuous casting process and the rolling process are directly connected, it is necessary that the order of the strips from the continuous casting machine becomes the rolling order in the rolling mill. Therefore, it is necessary to change the slab width even during casting. For this reason, the slab is sent out while adjusting the width of the slab even at the molten steel stage.

FIG. 8 is a schematic diagram for explaining the relationship between the continuous casting apparatus 100 in which the slab width is changed and the conventional flow velocity measuring unit 130. The slab delivered from the continuous casting apparatus 100 is squeezed inward when a narrow slab is manufactured, and widened when a wide slab is manufactured by a cylinder 412 connected to a mold. .

  The conventional flow velocity measuring unit 130 is installed around the width changing wall 410 of the continuous casting apparatus 100. However, since the width changing wall 410 also fluctuates with fluctuations in the width of the slab, it is not appropriate as an installation location of the flow velocity measuring unit 130. Therefore, the conventional flow velocity measuring unit 130 is hooked on the side wall of the upper mold 102. In such a configuration, the distance a between the flow velocity measuring unit 130 and the molten steel 120 changes as the width is changed by the width changing wall 410. Therefore, when the flow velocity v is measured, the detection value needs to be corrected, which causes a further problem in terms of measurement accuracy.

  In FIG. 1, since the flow velocity measuring unit 310 according to the present embodiment is embedded in the short side of the fixed mold 102, even if the width of the width changing wall of the continuous casting apparatus 300 is changed due to the change in the width of the slab. , The distance to the molten steel 120 does not change and does not affect the measurement of the flow velocity v. Therefore, it is not necessary to perform correction based on the variation in distance and correction of relative inclination as described above.

(2nd Embodiment: Arrangement | positioning on the plane of the flow-speed measurement part in a continuous casting apparatus)
The flow velocity measuring unit 310 described above generates a magnetic field (magnetic flux) B, detects the magnetic field B ′ that is inductively generated in accordance with the flow of the molten steel 120 toward the bottom of the continuous casting apparatus 300, and obtains the flow velocity.

  FIG. 2 is an explanatory diagram showing the principle of detection of the flow velocity of the molten steel 120. Here, a primary coil 500 and a secondary coil 510 serving as the flow velocity measuring unit 310 are arranged with respect to the mold 102 of the continuous casting apparatus 300. Further, the molten steel 120 flows at a flow velocity v in the mold 102 of the continuous casting apparatus 300.

When an alternating current I _{1 is} passed through the primary coil 500, a magnetic field B is generated, and this magnetic field B penetrates the side wall of the mold 102. The magnetic field B interferes with the flow (flow velocity v) of the molten steel 120, and the induced current _Iu is generated in the direction shown in the figure. The induced current I _u further generates a magnetic field B ′.

The secondary coil 510 receives a current that is a combination of the induced current caused by the magnetic field B directly produced by the primary coil 500 and the induced current caused by the induced magnetic field B ′ produced by the induced current I _u generated by the interference in the molten steel 120. . Here, since the positional relationship between the primary coil 500 and the secondary coil 510 is known, the induced current of the secondary coil by the primary coil 500 can be derived. Therefore, the induction is induced by the induced magnetic field B ′ by calculating the difference. Current can be extracted. Such a current value can be converted into a flow velocity v using a value calibrated in advance.

  The frequency of the alternating current flowing through the primary coil 500 is determined by the distance between the primary coil 500 and the molten steel 120 to be measured. If this distance is long, the frequency of the alternating current flowing through the primary coil 500 is limited.

  When the frequency of the alternating current decreases, the output gain from the flow velocity measuring unit 310 decreases, and accordingly, the detection signal at the secondary coil also decreases, and it can be determined whether the detected signal is a desired signal or noise. Disappear. Here, in order to maintain a predetermined output gain, the number of primary coils 500 and secondary coils 510 of the flow velocity measuring unit 310 can be increased, but this leads to an increase in the flow velocity measuring unit 310, Occupied volume and cost become a problem.

  However, the thickness of the solidified shell 124 is reduced by the configuration in which the flow velocity measuring unit 310 described above is installed in the mold 102 above the continuous casting apparatus 100, and accordingly, the distance between the primary coil 500 and the molten steel 120 is shortened. Therefore, even if the magnetic field B generated by the primary coil 500 is the same, the induced magnetic field B 'increases and the measurement accuracy is improved. Further, at such an installation position, compared with the lower part of the continuous casting apparatus 100, the flow rate of the molten steel in the mold itself is large, so that the detection amount is inevitably increased, and the measurement accuracy is further improved.

  Considering the distance between the primary coil 500 and the molten steel 120 to be measured, the thickness of the side wall of the mold 102 and the thickness of the solidified shell 124 existing between the flow velocity measuring unit 310 and the molten steel 120 should be considered. Is mentioned. Therefore, not only the thickness of the solidified shell 124 but also the thickness of the side wall of the mold 102 was examined.

For example, the thickness of the mold copper plate is d _Cu [m], and the thickness of the solidified shell 124 is d _Fe = k√ (H / v _c ) [m] (where H is the flow velocity measurement section from the meniscus (molten surface)). vertical distance to the height center (distance in the height direction) [m], _{v c} is the casting speed [m / min], k is a coagulation constant ^{[m / min 1/2].)} , flow rate measurement unit When the magnetic field generated on the copper plate surface by the primary coil 500 of 310 is B ₀ , the magnetic field generated inside the solidified shell, that is, at the interface between the molten steel 120 and the solidified shell is “110th and 111th Nishiyama Memorial Technology Course Steel Recent Progress in Solidification and Casting Processes of the Japan Iron and Steel Institute edited by the Japan Iron and Steel Institute (January 16, 1986, p123-127).

_{B = B 0 × exp (-d} Cu / δ Cu) × exp (-d Fe / δ Fe) = B 0 × exp (-d Cu / δ Cu -d Fe / δ Fe) ... ( Equation 1)
here,
δ _Cu = 1 / √ (μσ _Cu πf) (Expression 2),
δ _Fe = 1 / √ (μσ _Fe πf) (Formula 3)
In and, sigma _Cu is the electrical conductivity of the copper plate [S / m], σ _Fe represents the electrical conductivity of the steel [S / m].

  The fact that the primary coil 500 of the flow velocity measuring unit 310 has a sufficient strength of the magnetic field B generated at the interface between the solidified shell 124 and the molten steel 120 is based on the index effect 1 of the above exponential decay from the viewpoint of the skin effect. / E (e is a natural index 2.71828 ...) or more.

FIG. 3 is an explanatory diagram showing the relationship between the distance q from the surface and the magnetic field B. Referring to FIG. 3, the penetrating magnetic field B decreases as the distance q from the surface increases. When the skin depth is δ and the magnetic field B greater than or equal to B ₀ / e is required for the flow velocity measurement by the flow velocity measuring unit 310, the frequency of the alternating magnetic field B is limited.

That is, referring to Equation 1, d _Cu / δ _Cu + d _Fe / δ _Fe ≦ 1 is a condition, and when Equations 2 and 3 are substituted into Equation 1,
√ (μπf) × ((√σ _Cu ) d _Cu + (√σ _Fe ) d _Fe ) ≦ 1 (Formula 4)
And
f ≦ 1 / {πμ ((√σ _Cu ) d _Cu + (√σ _Fe ) d _Fe ) ² } (Formula 5)
Is derived.

  As described above, the limit of the frequency that can be given to the coil changes according to the change in the thickness of the copper plate and the thickness of the solidified shell 124 (distance from the meniscus). In other words, as described in the first embodiment, by arranging the flow velocity measuring unit 310 above the continuous casting apparatus 300, the solidified shell 124 can be measured in a relatively thin region. The wall thickness of the mold 102 is generally determined by the mold durability, mold rigidity, etc., and the amount of rework performed after use for a predetermined time, and is usually constant at about 15 to 50 mm. The frequency of the alternating magnetic field B is determined by Equation 5.

In the present embodiment, the frequency f can be exemplified as about 30 Hz or less. Further, for example, typical physical property values in normal operation (π = 3.14, μ = 4π × 10 ⁻⁷ , σ _Cu = 10 ⁷ , σ _Fe = 0.7 × 10 ⁶ , d _Cu = 0.03 , with _d Fe = 0.01), the 23.8Hz When the calculation of the equation 5. In order to reduce the magnetic field lost in the copper plate, the lower the frequency, the better. Therefore, the frequency of the alternating magnetic field B is desirably 10 Hz or less.

  FIG. 4 is a schematic diagram for explaining the position on the horizontal plane of the flow velocity measuring unit 310 in the second embodiment. Here, the mold 102 includes copper plates 710 and 720 and stainless plates 712 and 722 as back plates. The copper plate 710 and the stainless plate 712 form a water-cooled long side, and the copper plate 720 and the stainless plate 722 form a water-cooled short side. To do. In the molten steel pool 108 surrounded by the copper plates 710 and 720, the solidified shell 124 that is solidified around the molten steel 120 is covered. Further, the flow velocity measuring unit 310 includes the primary coil 500 and the secondary coil 510 as described above.

The molten steel 120 flowing at a flow velocity v in the mold 102 receives interference of the magnetic field B generated by the primary coil 500 of the flow velocity measuring unit 310 and generates an induced current _Iu in the direction shown in the figure. At this time, since the flow velocity measuring unit 310 is embedded in the stainless steel 722 and installed in contact with the copper plate 720, the distance between the flow velocity measuring unit 310 and the molten steel 120 becomes very short. In addition, a cutting hole may be formed in the copper plate 720, and the flow velocity measuring unit 310 may be embedded in the cutting hole to further reduce the distance.

  As described above, when the distance between the primary coil 500 and the molten steel 120 to be measured is shortened, the flow velocity can be measured with sufficient setting accuracy even if the frequency of the alternating current flowing through the primary coil 500 is set low. Further, when the frequency of the alternating current is increased, the output (gain) increases accordingly, and the induced current due to the flow of the molten steel 120 that can be received by the secondary coil 510 also increases, so that the S / N ratio is improved and the flow velocity is increased. The measurement accuracy is further improved.

  FIG. 5 is a cross-sectional view for explaining the arrangement of the flow velocity measuring unit 310 in the mold 102 in more detail. Here, the primary coil 500 is embedded in the stainless steel plate 722 of the mold 102, and the secondary coil 510 is further installed in or adjacent to the primary coil 500. In the secondary coil 510, the primary coil 500 and the coil central axis are orthogonal to each other.

The casting mold 102 of the continuous casting apparatus 300 as shown in FIGS. 1 and 4 has a width of 1500 mm, a height of 800 mm, and a cavity (casting space) thickness of 250 mm. Placed on the outer surface of the. The angle of the injection nozzle 110 in the continuous casting apparatus 300 was set to 25 degrees downward, and the signal value index, which is the actual measurement value of the flow velocity, was measured when the casting speed was 1,1.3, 1.5 m / min. . Here, the larger the signal value index, the higher the received signal level (higher gain). In addition, the frequency of the alternating current passed through the primary coil is the physical property value , the mold copper plate thickness, etc. (π = 3.14, μ = 4π × 10 ⁻⁷ , σ _Cu = 10 ⁷ , σ _Fe = 0 in this example). 7 × 10 ⁶ , d _Cu = 0.03, d _Fe = 0.01), and 5 Hz is selected from the frequency of 23.8 Hz or less of the alternating current derived using Equation 5 .

Further, for comparison with conventional flow velocity detection, a flow velocity measurement unit was disposed at a position 1.2 m from the meniscus, which is below the continuous casting apparatus 300, and an alternating current with a frequency of 50 Hz was applied to the primary coil. The measurement results are shown in Table 1.

Referring to Table 1, the data (signal value index) of the conventional flow velocity measurement unit is almost noise level, and the flow velocity due to the descent is high, for example, it is difficult to measure except when the casting speed is 1.5 m / min. It is understood. On the other hand, in the flow velocity measurement unit of the present embodiment, the output (gain) itself can be increased, and the signal value index is much higher than the noise signal level even when the casting speed is low 1 m / min. It can be understood that it shows a high signal level and can be measured with sufficient accuracy and fine resolution.

Further, in the casting clogging of the one side of the nozzle occurs in the casting speed is the same 1.5 m / min, a flow rate of the right and left short side (signal value index), i.e. measuring the drift degree, shown in Table 2. As can be seen from the comparison in Table 2, it is difficult to grasp because the degree of drift is almost equal to the noise signal level in the conventional continuous casting apparatus, but it can be clearly detected in the continuous casting apparatus of this embodiment.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above-described embodiment, the configuration in which the flow velocity measuring unit is installed only on the water-cooled short side is described. However, the present invention is not limited to this, and can be installed on the water-cooled long side.

  Moreover, although the structure of FIGS. 4 and 5 is described as the flow velocity measuring unit, for example, the present invention is not limited to this, and various methods having a structure for measuring a magnetic field (magnetic flux) due to the flow of molten steel can be taken. .

  The present invention relates to a continuous casting apparatus and a flow velocity measuring method. For example, in a continuous casting mold of steel, the present invention is applicable to a continuous casting apparatus and a flow velocity measuring method provided with a flow velocity measuring unit that detects a flow velocity of molten steel.

It is a schematic diagram for demonstrating the flow of the molten steel in a continuous casting apparatus. It is explanatory drawing which shows the principle of the detection of the flow rate of molten steel. It is explanatory drawing which showed the relationship between skin depth and a magnetic field. It is a schematic diagram for demonstrating the position in the horizontal surface of the flow-velocity measurement part in 2nd Embodiment. It is a cross-sectional view for explaining the arrangement of the flow velocity measuring unit in the mold in more detail. It is a schematic diagram for demonstrating the flow of the molten steel in the conventional continuous casting apparatus. It is a schematic diagram for demonstrating the problem of the detection of the flow velocity by the position of a flow velocity measurement part. It is a schematic diagram for demonstrating the relationship between the continuous casting apparatus from which slab width is changed, and the conventional flow velocity measurement part.

Explanation of symbols

100, 300 Continuous casting apparatus 102 Mold 108 Molten steel pool 110 Injection nozzle 120 Molten steel 124 Solidified shell 130, 310 Flow rate measuring unit 500 Primary coil 510 Secondary coil

Claims (4)

A pair of water-cooled long sides, a pair of water-cooled short sides that are sandwiched between the pair of water-cooled long sides and move parallel to the pair of water-cooled long sides and can adjust the casting width, and the pair of water-cooled long sides A continuous casting apparatus comprising a casting mold comprising an injection nozzle for injecting molten steel into a casting space formed by a water-cooled long side and the pair of water-cooled short sides,
A primary coil that generates an alternating magnetic field, and a secondary coil that measures the magnetic field generated by the magnetic field generated by the primary coil and the flow of the molten steel, with the central axis orthogonal to the primary coil, and the water-cooled short coil A continuous casting apparatus comprising a flow rate measuring unit for molten steel fixed to the outer side surface of the side. The frequency f [Hz] of the alternating current flowing through the primary coil is
f ≦ 1 / {πμ ((√σ _Cu ) d _Cu + (√σ _Fe ) d _Fe ) ² }
(Where d _Cu : mold copper plate thickness [m],
d _Fe = k√ (H / v _c ): solidified shell thickness [m]
σ _Cu : Electric conductivity [S / m] of the mold copper plate,
σ _Fe : electrical conductivity of steel [S / m],
H: Vertical distance [m] from the meniscus (water surface) to the center of the height of the flow velocity measurement unit,
v _c : casting speed [m / min],
k: coagulation constant [m / min ^1/2 ],
μ: Magnetic permeability [H / m]. )
The continuous casting apparatus according to claim 1, wherein   3. The continuous casting apparatus according to claim 1, wherein the flow velocity measuring units are respectively fixed to outer surfaces of the pair of water-cooled short sides. A flow rate measurement method for measuring a flow rate of molten steel flowing in a mold using the continuous casting apparatus according to any one of claims 1 to 3,
A flow velocity measuring method, wherein an alternating magnetic field is generated on an outer surface of the mold, and a magnetic field generated by the alternating magnetic field and the flow of the molten steel is measured.

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