JP6947059B2 - Shape design method for molten metal pot - Google Patents

Description

The present invention relates to a method for designing the shape of a pan for molten metal.

In hot metal pots that hold hot molten metal, such as hot metal from converters and torpedo cars, and hot metal pots that receive molten steel, changing the shape of the pot to increase the volume of the pot is the manufacturing cost of the ironmaking process. It is an effective means to reduce. In recent years, in order to expand the volume of the molten metal pot, the plane shape that has been generally used has been changed from a circular pot with a circular shape to an elliptical pot with an elliptical shape, and the plane shape is substantially rectangular. A change to a rectangular pan has also been proposed (for example, Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2016-59940 Japanese Unexamined Patent Publication No. 2000-256728 Japanese Patent No. 4506587

Specifications For Design And Use Of Ladles, AISE Technical Report No.9,1991

The strength of the iron skin in the shape design of the molten metal pot is generally examined by using a numerical analysis program by the finite element method. At this time, since the molten metal pot is configured by lining the inner surface of the iron skin with a refractory material, in actual operation, the refractory material expands due to the heat of the molten metal held inside the pot. A force is applied to the iron skin, causing stress and deformation in the pot iron skin. In the shape design of the molten metal pot, based on the estimation results of the stress and deformation amount generated in the pot in this way, the optimum shape is searched from the viewpoint of productivity and equipment life, and the final pot shape is determined.

However, in the conventional shape calculation of the molten metal pot, the physical properties of the refractory that change depending on the water content and composition are not sufficiently considered, and the estimation accuracy of the stress and the amount of deformation generated in the pot iron skin is not always accurate. It wasn't expensive. In addition, for circular pots or elliptical pots that are usually used, the standard strength design is specified in Non-Patent Document 1, but for pots that have begun to be used relatively recently, such as rectangular pots, such strength design guidelines. Does not exist. Also in Patent Documents 1 to 3 above, the shape design method of the molten metal pot is not particularly limited.

Therefore, when designing a new shape pot, there is no clear guideline for determining the optimum shape, and there are fluctuations in the physical characteristics of refractories. There is a concern that the estimation accuracy of the stress and the amount of deformation generated in the pot will be further reduced as compared with the case where it is performed. Therefore, a method for determining a pan for molten metal having an optimum shape from the viewpoint of productivity and equipment life has been desired.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to estimate the stress generated in the molten metal pan with high accuracy and determine the optimum pan shape. It is an object of the present invention to provide a new and improved method for designing a shape of a molten metal pan.

In order to solve the above problems, according to a certain viewpoint of the present invention, a method for designing the shape of a molten metal pot, which is constructed by constructing a fireproof material on the inner surface of an iron skin and holds molten metal, is in operation. For the existing pot, which is a pot for molten metal, the first stress calculation is performed using the Young's ratio of the refractory material set based on the past operating conditions, and the calculated stress value, which is the stress generated in the existing pot, is obtained. It was used in the first stress calculation so that the difference between the calculation step, the measurement step of measuring the stress generated in the existing pot and obtaining the measured stress value, and the measured stress value and the calculated stress value is within the allowable range. Using the correction step for correcting the Young rate and the corrected Young rate, the stress generated in the target pot, which is the hot metal pot to be designed, is calculated by the second stress calculation, and the optimum shape of the target pot is obtained. A design process and a method for designing the shape of a molten metal pot, including the design process, are provided.

Young's modulus is the first Young's modulus in the drying step of drying the molten metal pot before operation, the second Young's modulus in the preheating step of preheating the molten metal pot after the drying step, and melting after the preheating step. In the correction step, the first Young's modulus, the second Young's modulus and the third Young's modulus used in the first stress calculation include the third Young's modulus in the operation process in which the holding and discharging of the metal are repeated. Each rate may be corrected and a second stress calculation may be performed in the design process using the corrected first Young's modulus, the corrected second Young's modulus and the corrected third Young's modulus. ..

The design process, based on the stress calculated by the second stress calculation and corrected Young's modulus may further calculate the amount of deformation of the subject pot.

It is desirable that the existing pot and the target pot have substantially the same type and thickness of the refractory to be installed inside the pot.

The target pot may have a rectangular pot having a substantially rectangular shape in a plan view of the accommodating portion for accommodating the molten metal , or any other shape.

As described above, according to the present invention, it is possible to estimate the stress generated in the molten metal pan with high accuracy and determine the optimum pan shape.

It is a flowchart which shows the shape design method of the molten metal pot which concerns on one Embodiment of this invention. It is a top view and a side view which show the shape of an elliptical pot. It is a top view and a side view which show the shape of a rectangular pot. It is a graph which shows one relation example of the measured stress value, the calculated stress value before Young's modulus correction of a refractory, and the calculated stress value after Young's modulus correction of a refractory about an existing pot. It is a graph which shows one relation example of the radial displacement and the number of operation cycles. It is a graph which shows the calculated stress value and the measured stress value of the target pot in the comparative example. It is a graph which shows the calculated stress value and the measured stress value of the target pot in an Example.

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

<1. Overview>
The method for designing the shape of a molten metal pan according to an embodiment of the present invention is a method for determining the optimum shape of a molten metal pan to be designed from the viewpoint of productivity and equipment life. In this method, first, the stress (measured stress value) generated in the existing pot is measured for the existing pot in operation, and the Young's modulus of the fireproof material set based on the past operating conditions is used for the existing pot. The stress is calculated, the stress generated in the existing pot (calculated stress value) is calculated, and Young's modulus is corrected so that the difference between the measured stress value and the calculated stress value is within the allowable range. Then, using the corrected Young's modulus, the stress generated in the target pot, which is the design target, is calculated by stress calculation, and the optimum shape of the target pot is obtained.

In this way, by setting an appropriate Young's modulus of the fireproof material and improving the accuracy of stress calculation, it is calculated from the presence or absence of stress concentration points in the pot and the stress when the shape of the pot under consideration is used. It has become possible to more accurately determine the amount of plastic deformation accumulated in the pot after multiple cycles from the amount of plastic deformation of the pot in each operation cycle, and the molten metal with a more optimal shape compared to the current method. The shape of the pot can be determined. Hereinafter, the shape design method of the molten metal pan according to the present embodiment will be described in detail.

<2. Shape design method for molten metal pot>
The shape design method of the molten metal pan according to the present embodiment will be described in detail with reference to FIG. FIG. 1 is a flowchart showing a method for designing the shape of a molten metal pan according to the present embodiment.

In this embodiment, a molten steel pot that holds molten steel as a pot for molten metal will be described. Further, in the present embodiment, the elliptical pot shown in FIG. 2 will be used as an existing pot, and the rectangular pot shown in FIG. 3 will be used as a target pot. As shown in FIG. 2, the elliptical pan 10 has an elliptical shape of the accommodating portion for accommodating molten steel when viewed from a plane. The elliptical pot 10 is constructed by constructing a refractory material 13 inside the iron skin 11. The elliptical pan 10 is configured to be tiltable about the axis 15. As shown in FIG. 3, the rectangular pot 20 also has a refractory material 23 installed inside the iron skin 21 and is configured to be tiltable about the shaft 25, as in the elliptical pot 10.

The present invention is not limited to such an example, and the shape of the existing pot does not matter as long as the pot can obtain the measured stress value. Further, the shape of the target pot is not limited, and it is sufficient that at least the type and thickness of the refractory to be constructed are substantially the same as the existing pot having the Young's modulus used at the time of shape design. The closer the type and thickness of the refractory to the pot, the more accurately the Young's modulus of the target pot to be designed can be set.

(S100: calculation process)
In the method for designing the shape of the molten metal pot according to the present embodiment, as shown in FIG. 1, the stress generated in the pot is calculated for the existing pot (S100). The stress is calculated using, for example, a general-purpose numerical analysis program by the Finite Element Method (FEM) method. At this time, based on the actual operating conditions, for example, various physical property values such as Young's modulus of iron skin and refractory, temperature boundary conditions, and the like are set and analyzed. The stress obtained by such a calculation step is used as a calculated stress value as information for correcting Young's modulus, which will be described later.

(S110: Measurement process)
Further, with respect to the existing pot, the stress generated in the pot is measured and the measured stress value is acquired (S110). The measured stress value can be obtained, for example, based on the strain of the pot measured by the strain gauge installed on the iron skin surface of the existing pot. The stress can be determined by the product of the strain and Young's modulus.

The strain gauge should be installed at a place where the stress is particularly large, based on the result of the stress calculation performed on the existing pot. For example, in the present embodiment, as shown in FIG. 2, strain gauges 31 to 34 are installed on the surface of the iron skin 11 of the elliptical pot 10, and the strain of the pot is measured at a plurality of positions in the circumferential direction and the height direction. The strains measured by the strain gauges 31 to 34 are continuously recorded in a storage device such as a data logger. The strain is measured, for example, in a drying step of drying the pot before the operation of the pot, a preheating step of preheating the pot after the drying step, and an operation process of repeating steel receiving, casting, and scavenging every one operation cycle after the preheating process. NS. In the operation process, it is sufficient that at least the strain until the first operation cycle is completed can be acquired.

When the strain of the existing pot operated by the strain gauges 31 to 34 is measured, the stress at the installation position of the strain gauges 31 to 34 is calculated from the strain and Young's modulus. The calculated stress is used as the measured stress value and as information for correcting the Young's modulus of the refractory, which will be described later.

(S120: Correction step)
When the calculated stress value and the measured stress value of the existing pot are acquired, Young's modulus is adjusted so that these values approach each other (S120). It is known that Young's modulus changes greatly based on the water content and temperature of refractories. In addition, Young's modulus is a parameter that greatly affects the result of stress calculation, and the accuracy of the stress calculation result can be improved by appropriately setting Young's modulus.

To adjust Young's modulus, first, the drying process and the drying process and so that the temperature level of the iron skin temperature of the existing pot when the measured stress value is measured and the iron skin temperature set in the stress calculation to obtain the calculated stress value match. The heat flux applied to the inner surface of the pot in the preheating process is adjusted to determine the temperature conditions to be set in the stress calculation. Next, the Young's modulus is changed in the stress calculation, and the Young's modulus used in the stress calculation is determined so that the difference between the obtained calculated stress value and the actually measured stress value is within the allowable range. For example, Young's modulus used in the stress calculation may be determined so that the calculated stress value is within the range of ± 10% of the measured stress value.

Here, changes in physical properties due to the water content of the refractory, thermal expansion of bricks and amorphous refractories, and the like greatly change depending on the state of the pot until the operation process. Therefore, the Young's modulus of the refractory also changes in the drying process, the preheating process, and the operating process. Therefore, in order to further improve the accuracy of stress calculation, Young's modulus may be corrected and set for each process. For example, due to the difference in the water content of the fireproof material, the Young's modulus in the drying process (first Young's modulus), the Young's modulus in the preheating process (second Young's modulus), and the Young's modulus in the operating process (third Young's modulus). Young's modulus) may be set.

FIG. 4 shows the actually measured stress values acquired in step S110 under five operating conditions, the calculated stress values calculated in step S100, and the calculated stress values after correcting the Young's modulus of the refractory in S120 for the existing pot. Show the relationship. The upper side of FIG. 4 shows the calculated stress value before the Young's modulus correction of the refractory, and the lower side of FIG. 4 shows the calculated stress value after the Young's modulus correction of the refractory. The time shown on the horizontal axis and the stress shown on the vertical axis of the graph of FIG. 4 show normalized values. As shown on the upper side of FIG. 4, before the Young's modulus was corrected, the calculated stress value was much larger than the measured stress value. That is, it is probable that the operating conditions set in the initial stress calculation were the conditions for highly evaluating the stress of the iron skin, and the actual life of the pot was longer than the life of the pot obtained as a result of the analysis.

Therefore, in step S120, the Young's modulus of the refractory was adjusted for each of the drying step, the preheating step, and the operating step so that the calculated stress value approaches the actual stress value as shown in the lower part of FIG. When the difference between the calculated stress value and the actual stress value is within the permissible range, the Young's modulus (first Young's modulus) of the refractory in the drying process becomes a value 5% larger than the initially set Young's modulus, and preheating. The Young's modulus of the refractory in the process (second Young's modulus) was set to a value continuously increased by 5 to 20% from the initially set Young's modulus.

As described above, in step S120, the Young's modulus of the refractory material is changed so that the calculated stress value approaches the actual stress value, and the Young's modulus of the refractory material set at the time of stress calculation is the difference between the calculated stress value and the actual stress value. Is corrected to the value when is within the allowable range.

(S130: Design process)
Then, based on the Young's modulus of the refractory obtained in step S120, the stress generated in the target pot to be designed is calculated, and the shape of the target pot is determined (S130). In step S130, first, the shape of the pot is tentatively set in consideration of the increase in volume, the connection with the existing equipment, and the like, and the stress generated in the pot is calculated by stress calculation based on the past operating conditions. From the calculated stress, it is determined whether or not there is a place where stress is concentrated in the target pot, and if there is a place where stress exceeding a predetermined value is generated, the shape of the pot at this time is Not adopted. Then, a new pot shape is set so that the stress concentration is relaxed, and the stress calculation is executed again.

Further, based on the stress calculated by the stress calculation and the corrected Young's modulus, the amount of deformation generated in the pot is calculated, the amount of deformation accumulated by continuously using the pot is obtained, and the accumulated deformation is obtained. Calculate its life from the quantity. Specifically, for example, the radial displacement in the middle abdomen of the pot is considered as the amount of deformation. Then, first, the radial displacement of the middle abdomen of the pot after the completion of casting from the first operation cycle to the eighth operation cycle of the operation process is calculated from the stress calculated by the stress calculation and Young's modulus. Next, the amount of increase in radial displacement in each operation cycle is obtained, and an approximate expression representing the relationship between the amount of increase in radial displacement and the number of operation cycles is obtained. Then, using such an approximate expression, the cumulative value of the radial displacement after a lapse of a predetermined time is obtained.

FIG. 5 shows an example of the relationship between the radial displacement and the number of operation cycles. FIG. 5 shows the calculated results of the elliptical pot shown in FIG. 2 as the existing pot and the rectangular pot shown in FIG. 3 as the target pot. The radial displacement shown on the vertical axis of the graph of FIG. 5 shows a normalized value. FIG. 5 shows the result of calculating the radial displacement of the middle abdomen of the pot after the completion of casting from the 1st operation cycle to the 8th operation cycle from the stress calculated by the stress calculation and Young's modulus. By obtaining the relationship between the radial displacement and the number of operating cycles, it is possible to calculate the number of operating cycles when the cumulative value of the radial displacement, which is the life of the pot, exceeds the specified value.

Based on the pot life calculated for each tentatively set pot shape, it is determined whether or not the life required for the target pot is satisfied. The specified value of the cumulative value of the radial displacement set for determining the life of the pot may be the same as that of the existing pot, for example. As a result of the determination, if the life of the temporarily set pot shape does not meet the life required for the pot, the pot shape is not adopted. Then, a new pot shape is set so that the stress concentration is relaxed, and the stress calculation is executed again. In this way, in the design of the target pot, the shape of the pot is set, the presence or absence of stress concentration and the calculation of the life are repeated in the case of such a shape, and the volume is as large as possible and the required life is satisfied. Determine the shape of the pot.

The method of designing the shape of the molten metal pan according to the present embodiment has been described above. According to the present embodiment, the Young's modulus is corrected so that these values approach each other based on the calculated stress value and the measured stress value acquired for the existing pot, and the stress of the target pot is calculated using the corrected Young's modulus. calculate. By correcting the Young's modulus, the stress calculation is performed in a state in which the state of the refractory of the molten metal pot is more appropriately reflected, so that the stress calculation accuracy can be improved. Since the stress can be calculated with high accuracy, the amount of deformation of the pot can be calculated more accurately. As a result, even in the design of a new pot for molten metal, the optimum pot shape can be determined from the viewpoint of productivity and equipment life.

As an example, in order to determine the shape of the rectangular pot to be designed based on the shape design method of the molten metal pot of the present invention, Young corrected based on the calculated stress value and the actual stress value of the existing pot, the elliptical pot. Using the rate, the stress generated in the rectangular pan was calculated by stress calculation. For the existing pot, the shape of the pot was different from that of the target pot, but the type and thickness of the refractory to be installed inside the pot could be regarded as the same. Young's modulus was set for each of the drying process, the preheating process, and the operating process. On the other hand, as a comparative example, the Young's modulus was not corrected, and the stress was calculated using the same Young's modulus as the Young's modulus used for the stress calculation of the existing pot, and the stress of the target pot was calculated. FIG. 6 shows the calculated stress value and the measured stress value of the target pot in the comparative example, and FIG. 7 shows the calculated stress value and the measured stress value of the target pot in the example. The time shown on the horizontal axis and the stress shown on the vertical axis of the graphs of FIGS. 6 and 7 show normalized values.

In the comparative example, as shown in FIG. 6, the actually measured stress value and the calculated stress value deviate greatly, and the calculated stress value shows a large value. When the shape of the pot is designed using such calculated stress values, the volume cannot be increased sufficiently, and as a result of estimating the amount of deformation during hot use, the life is assumed to be short. Become. On the other hand, in the example, as shown in FIG. 7, there was no significant difference between the measured stress value and the calculated stress value as compared with the comparative example. From this, by using the shape design method for the molten metal pot of the present invention, the stress generated in the pot can be estimated more accurately, and the optimum pot shape can be determined.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

For example, in the above embodiment, the Young's modulus that reflects the state of the refractory is corrected among the parameters of the stress calculation, but the present invention is not limited to such an example. For example, for parameters other than Young's modulus, the calculated stress value and the measured stress value may be corrected so as to be close to each other.

10 Elliptical pot 11, 21 Iron skin 13, 23 Refractory 15, 25 Axis 20 Rectangular pot

Claims (5)

It is a method of designing the shape of a molten metal pot that holds refractory metal by constructing a refractory material on the inner surface of the iron skin.
For the existing pot, which is a pot for molten metal in operation, the first stress calculation is performed using the Young's modulus of the refractory set based on the past operating conditions, and the calculated stress, which is the stress generated in the existing pot, is calculated. The calculation process to get the value and
A measurement process for measuring the stress generated in the existing pot and acquiring the measured stress value,
A correction step for correcting Young's modulus used in the first stress calculation so that the difference between the measured stress value and the calculated stress value is within an allowable range.
Using the corrected Young's modulus, the stress generated in the target pot, which is the pot for molten metal to be designed, is calculated by the second stress calculation, and the design process for obtaining the optimum shape of the target pot, and the design process.
How to design the shape of a pan for molten metal, including. The Young's modulus is
The first Young's modulus in the drying step of drying the molten metal pot before operation, and
After the drying step, the second Young's modulus in the preheating step of preheating the molten metal pot,
After the preheating step, the third Young's modulus in the operation process in which the holding and discharging of the molten metal are repeated, and
Including
In the correction step, the first Young's modulus, the second Young's modulus, and the third Young's modulus used in the first stress calculation are corrected, respectively.
In the design step, the second stress calculation is performed using the corrected first Young's modulus, the corrected second Young's modulus, and the corrected third Young's modulus. The method for designing the shape of a pan for molten metal described in 1. Prior SL design process based on the said stress calculated by the second stress calculation and the corrected Young's modulus, and calculates the amount of deformation of the object pan, for molten metal according to claim 1 or 2 How to design the shape of the pot. The method for designing the shape of a molten metal pot according to any one of claims 1 to 3, wherein the existing pot and the target pot have substantially the same type and thickness of the refractory material installed inside the pot. The method for designing the shape of a pot for molten metal according to any one of claims 1 to 4, wherein the target pot has a substantially rectangular plane shape in a plan view of a storage portion for accommodating the molten metal.

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