JP2020059904A - Structure for preventing brick in sloped part from dropping down - Google Patents

Abstract

To provide a structure in an uppermost part of a sloped part, for preventing a brick from dropping down from an uppermost rung of the sloped part.SOLUTION: A structure of this invention for preventing a brick in a sloped part 2 from dropping down prevents the brick 4 piled on a sloped part 2 of a revolving furnace 1 from dropping down, wherein the structure is formed so that: in an uppermost brick 4T provided on an uppermost part of the sloped part 2, an upper surface of the uppermost brick 4T is sloped at a tilt angle θto be turned upward from an inside of the furnace to a backside thereof; and a surface on the inside of the furnace is turned vertically. The tilt angle θis set so that resultant force is reduced to a minimum, the resultant force being generated by: force toward the inside of the furnace, generated by struggles of piled bricks 4 in a vertical direction; and force toward the inside of the furnace, generated due to expansion difference between a metallic material arranged on the sloped part 2 and the brick.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technique for suppressing expansion, deformation, and damage of a brick used in a smelting reaction vessel such as a converter, and in particular, the present invention relates to the dropping of refractory bricks used in a narrowed portion of a converter. The present invention relates to a brick fall prevention structure that prevents

The furnace body of the converter is generally formed in the shape of a cylinder with a bottom that opens upward, and the upper part has a throttle structure that is inclined toward the inside of the furnace and is narrowed. A refractory material such as brick is lined on the inner peripheral surface of the furnace body.
More specifically, from the perspective of preventing damage to the entire diaphragm (falling, cracking by pushing up), the brick of the drawn part has a constant inclination angle (angle formed by the upper surface with respect to the horizontal plane, generally an angle of about 0 ° to 30 °). ) Is stacked from the bottom side.

Further, a furnace mouth metal fitting for vertically restraining the plurality of vertically stacked bricks is provided on the uppermost brick that is finally stacked. The gap between the top brick and the furnace mouth metal is filled with iron plate and cast refractory (castable), and it is adjusted to exert a certain binding force on the brick.
The angle of inclination of the upper surface of the uppermost brick is not the same as the angle of inclination of the brick (hereinafter referred to as the drawn portion brick) provided in the narrowed portion below the uppermost brick. That is, the inclination angles of the narrowed portion bricks are generally aligned at about 0 ° to 30 ° for the reasons described above. However, the inclination angle of the upper surface of the uppermost brick is usually aligned with the inclination angle of the lower surface of the furnace opening metalwork in order to make the restraint (holding down) by the furnace opening metalwork effective. is there. For example, the inclination angle θ ₁ between the bottom surface of the furnace metal fitting and the top surface of the uppermost brick is 0 °.

In the following description, it is assumed that the upper surface of the uppermost brick has an inclination angle θ ₁ = the lower surface of the furnace mouthpiece.
By the way, the above refractory material exhibits various forms of wear depending on the installation site in the furnace and operating conditions. For example, in the uppermost stage of the narrowed portion, there is a problem that the number of furnaces (the number of times of use) is increased and the uppermost brick is often dropped off, which causes an increase in repair cost and a decrease in furnace life. In particular, in order to remove the metal, there is a case where the machine is hit with a heavy machine, and there are many cases where the metal comes off after the hit.

  As a conventional technique for preventing the falling of the uppermost brick, hooks are embedded in the side surface and the back surface of the brick as shown in Patent Document 1 and Patent Document 2, and the hook is welded to the inner surface of the iron skin and hooked on the added rail. Therefore, a method for suppressing the occurrence of falling out has been proposed. Further, Patent Documents 3 to 5 also propose a method of connecting adjacent bricks to each other with a pin or a metal case to suppress the occurrence of falling.

  Further, in FIG. 1 of Patent Document 6 and Patent Document 7, the inclination angle of the lower surface of the presser metal object (furnace mouth metal object) is made the same as the inclination angle of the narrowed portion brick (the inclination angle of the brick of the entire diaphragm) (furnace The refractory structure of the uppermost drawing is described in which the lower surface of the die and the drawing brick are parallel to each other.

JP-A-1-309915 Japanese Utility Model Publication No. 8-6023 Japanese Utility Model Publication No. 8-6022 Utility model registration No. 2553203 JP 2004-10936 A Japanese Utility Model Publication No. 61-159357 Japanese Utility Model Publication No. 3-67050

The methods of Patent Documents 1 to 5 described above are for increasing the manufacturing cost of bricks and the cost of building a furnace, or extending the furnace building time. Even if the topmost brick can be prevented from falling off, the cost and Operating time is sacrificed. Therefore, a fundamental and structural solution is necessary to prevent bricks from falling off.
Further, in the furnace body structures of Patent Documents 6 and 7, there is a problem in removing the metal attached to the uppermost brick. That is, in order to prevent the growth of the metal attached to the uppermost part, the metal is regularly hit with a heavy machine to drop the metal (peeling from the uppermost brick). At this time, in the structures of Patent Documents 6 and 7, since the operating surface of the uppermost brick and the striking direction are not orthogonal to each other, it is difficult to hit the boundary between the metal and the operating surface, and it is difficult to drop the adhered metal (for example, FIG. (See the diagram on the left side of 3). In other words, in the furnace body structures of Patent Documents 6 and 7, only the upper part of the uppermost brick can be hit, so that it is difficult to remove the attached metal. In addition, it is possible that the topmost brick may be smashed and broken in order to forcibly drop the attached metal.

  The present invention has been made in view of the above-mentioned problems, and it is possible to easily remove adhered metal and to prevent the uppermost brick from falling off from the uppermost stage of the narrowed portion without fail. It is intended to provide a superstructure. In other words, according to the present invention, by adjusting the inclination angle of the uppermost brick of the narrowed portion, the adhered metal can be easily dropped and the uppermost brick can be surely prevented from falling off. It is intended to provide a structure.

In order to solve the above-mentioned problems, the structure for preventing the falling of the brick of the narrowed portion of the present invention takes the following technical means.
That is, the brick falling-off preventing structure of the throttle portion of the present invention is a brick falling-off preventing structure for preventing the bricks stacked in the throttle portion of the converter from falling off, and the uppermost brick arranged at the top of the throttling portion. With respect to the above, the upper surface of the uppermost brick is inclined at an inclination angle θ ₁ so as to face upward from the inside of the furnace toward the back side, and the surface of the inside of the furnace is formed to face vertically. Characterize.

In addition, preferably, the combined force of the force inward of the furnace due to the vertical interference of the loaded bricks and the force inward of the furnace due to the difference in expansion between the furnace mouth metal fittings and the bricks provided in the narrowed portion. The tilt angle θ ₁ is preferably set so that
In addition, it is preferable that the upper surface of the diaphragm brick arranged from the middle stage to the lower stage of the throttle unit satisfies the relationship represented by the formula (2) when the inclination angle is θ ₂ with respect to the horizontal direction. In addition, it is preferable that the inclination angle θ ₁ is set.

θ ₁ ≧ 0.5 θ ₂ + X and θ ₁ ＞ 0 ・ ・ ・ (2)
However, X is a constant from 0 to 10

  ADVANTAGE OF THE INVENTION According to the technique of this invention, the adhered metal can be easily dropped and it is possible to reliably prevent the uppermost brick from dropping from the uppermost stage of the narrowed portion. By adjusting the inclination angle of the uppermost brick of the narrowed portion, the adhered metal can be easily dropped and the uppermost brick can be reliably prevented from falling off.

It is the figure which showed the converter with which the falling-off prevention structure of the brick concerning this invention was provided. It is the figure which expanded and showed the throttle part of the converter of FIG. It is a figure which compared the state of the operation side with the prior art and this invention. It is sectional drawing which expanded and showed the throttle part of this invention. FIG. 3 is a diagram schematically showing a component force P ₁ and a component force P ₂ acting on the uppermost brick. It is a figure which compared the cross-sectional structure of a diaphragm part with the prior art and this invention. FIG. 9 is a diagram showing how the sum of component forces (P ₁ + P ₂ ) changes when the tilt angles θ ₁ and θ ₂ are changed. It is the figure which showed an example of the falling-off prevention structure concerning the present invention.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, an embodiment of a structure for preventing a falling-off of a narrowed portion according to the present invention will be described in detail with reference to the drawings.
First, the processing container provided with the brick fallout prevention structure of the present embodiment and the narrowed portion 2 of the processing container will be described.
As shown in FIG. 1, of the processing vessels (smelting reaction vessels) used in the field of iron making such as dephosphorization furnaces and converters, which are the subject of the present invention, the converter 1 is taken as an example and its outline is shown. explain.

In the following description, the vertical direction of FIG. 1 is referred to as the vertical direction when describing the converter 1. Further, in the converter 1 of FIG. 1, the direction from the outside of the furnace to the center of the furnace is “inside the furnace” or “inside the furnace”, and the direction from the center of the furnace to the outside of the furnace is “back side” or “back side”. Side.
FIG. 1 is a schematic cross-sectional view of the converter 1 cut along a cut surface passing through the core of the converter 1, in which some of constituent members are omitted. That is, FIG. 1 schematically shows an example of the converter 1 of the present invention. It should be noted that the processing container in which the brick fall prevention structure of the present invention is provided is not limited to that shown in FIG.

  As shown in FIG. 1, the converter 1 is a bottomed cylindrical container having an open top, and a steel shell 3 is provided on the outermost side of the container. In the converter 1, since molten metal (molten iron) tapped from the blast furnace is charged into the furnace, a fixed refractory material (brick brick 4) is provided inside the iron shell 3 (on the side where the molten metal is charged). ) Is piled up from the bottom part (laying part) to the upper part of the body part (furnace mouth). The barrel of the converter 1 is provided with a tap hole (not shown) for discharging the molten metal to the outside.

By the way, the converter 1 has a "throttled portion 2" having a shape that is narrowed toward the inside of the furnace from the upper side of the vertical middle portion of the body portion toward the furnace opening at the upper end.
As shown in FIG. 2, the throttle portion 2 includes an iron shell 3 provided along the outer edge of the converter 1 on the back side, a brick 4 stacked inside the furnace of the iron shell 3, and a converter 1 of the converter 1. The furnace mouth metal fitting 5 is fitted into the furnace mouth from above. Among the stacked bricks 4, the brick 4 located at least one step from the top is called the top brick 4T. An amorphous refractory (castable) or the like is provided between the uppermost brick 4T and the furnace mouth metal 5.

The iron shell 3 is formed in a bottomed cylindrical shape using cast iron or the like so as to follow the outer shape of the converter 1. The thickness of the iron shell 3 is about 30 mm to 100 mm in the case of the converter 1 having a thickness of about 100 t to 300 t, and can withstand the weight of the bricks 4 stacked inside the furnace and the molten metal charged into the furnace. ing.
The brick 4 is formed of a material such as MgO-C brick into a rectangular shape (rectangular parallelepiped shape), and is stacked in a plurality of layers in the vertical direction from the bottom to the top of the converter 1. Specifically, the bricks 4 described above are stacked in the body of the converter 1 along the horizontal direction (the upper surface and the lower surface are aligned along the horizontal direction).

  On the other hand, in the narrowed portion 2, the bricks 4 are stacked in multiple stages in a state of being inclined so as to incline upward from the inside of the furnace toward the back side. The bricks 4 provided in the narrowed portion 2, that is, the bricks 4 stacked in a plurality of stages in a state of being inclined toward the back surface side are “diaphragm bricks 4S”. Further, among the narrow bricks 4S, the one located at least one step from the uppermost portion of the narrowed portion 2 is the uppermost brick 4T. The uppermost brick 4T is a brick 4 different from the above-described diaphragm brick 4S and brick 4 provided on the body. An operating surface 6 that contacts the molten metal is formed inside the furnace of the uppermost brick 4T.

In other words, the above-described narrowing portion 2 is provided with two bricks, the uppermost brick 4T and the narrower brick 4S that is arranged below the uppermost brick 4T.
The furnace mouth metal member 5 is made of cast iron or the like like the iron shell 3 and the like. The furnace mouth metal 5 is a member that can be hung by a crane and fitted into the furnace mouth of the converter 1 from above, and presses the bricks 4 stacked in the vertical direction so as not to collapse. An opening corresponding to the furnace opening is formed at the center of the furnace mouth metal 5 so as to open both upward and downward.

  The height adjuster 7 is provided between the furnace mouth metal 5 and the uppermost brick 4T, and is provided to fill the gap between the furnace mouth metal 5 and the uppermost brick 4T. By providing the height adjusting body 7, the stacked bricks 4 are surely pressed by the furnace mouth metal piece 5 and the collapse of the bricks 4 can be prevented. In addition, castable refractory such as castable is often used for the height adjuster 7 described above, but it may be adjusted by sandwiching an iron plate or the like.

By the way, as shown in FIG. 4, in the structure for preventing the falling of the brick of the narrowed portion 2 of this embodiment, the shape of the brick 4 for at least one step at the uppermost portion is such that the upper surface inclines to a position higher toward the rear side (upward). It is characterized in that it is inclined (inclination angle θ ₁ > 0) and the operating surface 6 is oriented vertically.
In other words, in the structure for preventing the falling of the brick of the narrowed portion 2 of the present embodiment, the uppermost brick 4T located at least one step from the uppermost portion of the narrowed portion 2 has the upper surface of the uppermost brick 4T facing the rear side. It is characterized in that it is inclined so as to be higher (inclination angle θ ₁ > 0), and that the working surface 6 facing the inside of the furnace is erected in the vertical direction.

  By the way, since the uppermost brick 4T, which becomes hot during operation, is formed of a refractory material, it thermally expands in the vertical direction. As a result of this thermal expansion, a contact force along the vertical direction is generated on the uppermost brick 4T itself. Here, if the inclination angle of the upper surface of the uppermost brick 4T changes, the component force of the vertical force generated by thermal expansion also changes, so the acting force that promotes (or suppresses) the falling of the uppermost brick 4T changes. To do.

Specifically, as shown in FIG. 5, the component force of the force (contact force) generated by the above-mentioned thermal expansion is the inclination angle θ ₁ of the upper surface of the upper brick 4 and the inclination angle θ ₂ of the narrow brick 4S ( It varies in relation to the theta ₂₎ tilt angle of the entire aperture portion 2.
Here, “the inclination angle θ _{1 formed by} the upper surface of the upper brick 4 with respect to the horizontal direction” means the angle formed by the upper surface of the uppermost brick 4T of the narrowed portion 2 with respect to the furnace inward direction (horizontal direction). . More precisely, this inclination angle θ ₁ is also the angle that the upper surface of the uppermost brick 4T makes with the horizontal plane in the cross section of the narrowed portion 2 cut along the cutting surface extending in the vertical direction through the core. it can.

Further, “the inclination angle θ ₂ of the squeeze brick 4S” means an angle formed by (the lower surface or the upper surface of) the squeeze brick 4S with respect to the horizontal direction. More precisely, this inclination angle θ ₂ is the angle that the upper surface or the lower surface of the drawing brick 4S makes with respect to the horizontal plane that faces the inside of the furnace in the cross section cut along the cutting surface extending vertically through the core. You can also
Here, the influence of the inclination angles of the uppermost brick 4T and the narrow brick 4S will be considered.

The refractory that becomes hot during operation has a vertical thermal expansion as a result (as a result of receiving a reaction force of the thermal expansion force from the adjacent bricks 4) in the uppermost brick 4T itself. Here, when the above-mentioned contact force component is generated, this horizontal component force acting on the uppermost brick 4T promotes (or suppresses) the uppermost brick 4T falling out toward the inside of the furnace. It becomes the acting force to do. That is, when the tilt angle θ ₁ and the tilt angle θ ₂ are changed, the magnitude of the component force of the above-mentioned contact force also changes, and the acting force that promotes (or suppresses) the falling of the uppermost brick 4T changes.
(A) First, consider the component force P _{1 of the} contact force received by the uppermost brick 4T due to the vertical crossing.

Specifically, the acting force described above is shown as the sum of the component forces P ₁ and P ₂ , and each component force is derived as follows.
The inclination angle theta ₁ of the upper surface of the uppermost bricks 4T described above, stop when the inclination angle theta ₂ of the brick 4S differs, the contact force F ₁ in accordance with the difference of these angles furnace inward (or furnace outward) Occurs. At this time, the component force P ₁ of the contact force F ₁ is expressed by the following equation (3).

P ₁ = sin ((θ ₂ -θ ₁ ) / 2) × contact force F ₁・ ・ ・ (3)
Where P ₁ is the component force of the uppermost brick 4T inward toward the furnace due to the vertical interference θ ₁ : The angle of inclination of the upper surface of the uppermost brick 4T with respect to the inward direction θ ₂ : The narrowed brick 4S Inclination angle to the inside of the furnace For example, when the inclination angle θ ₂ of the narrow brick 4S is 10 ° and the inclination angle θ ₁ of the upper surface of the uppermost brick 4T is 0 ° toward the rear surface, the upper furnace mouth metal fitting And, as a result of the upper and lower contact force F ₁ received from the lower drawing brick 4S, a component force P ₁ = sin 5 ° × F ₁ inward of the furnace is generated.

Here, the component force P ₁ toward the inside of the furnace can be reduced by increasing the difference (θ ₂ −θ ₁ ) in the inclination angle, but θ ₂ is determined by the structural constraint of the entire throttle unit 2. In many cases, the angle cannot be changed. Therefore, it is effective to increase the inclination angle θ ₁ of the upper surface of the uppermost brick 4T.
Therefore, in many converters 1, the upper surface of the uppermost brick 4T is horizontal, but when the brick fall-out prevention structure of the present invention is adopted, the uppermost brick 4T is intentionally moved toward a higher position toward the rear side with respect to the upper surface. Design so that it inclines (θ ₁ has a negative value).
(B) Next, consider the component force P ₂ of the contact force that the uppermost brick 4T receives due to the difference in thermal expansion.

  Above the uppermost brick 4T, there is a furnace mouth metal 5 for preventing the brick 4 from falling off by sandwiching a height adjuster 7 such as an irregular refractory. The coefficient of thermal expansion differs between the metal such as iron that constitutes the furnace metal fitting 5 and the uppermost brick 4T formed of a refractory material such as an oxide. Therefore, an action force is generated even as a result of thermal expansion of the uppermost brick 4T and the furnace mouthpiece 5 having different thermal expansion coefficients.

Note that the thermal expansion coefficient is generally smaller for refractory materials that are required not to be damaged by thermal strain at high temperatures, and is larger for metals such as iron.
It is the inclination angle of the lower surface of the furnace metal piece 5 that affects the acting force generated by the difference in the coefficient of thermal expansion. That is, since the inclination angle of the lower surface of the furnace mouthpiece 5 is the same as the inclination angle θ ₁ of the upper surface of the uppermost brick 4T, the inclination angle θ ₁ of the upper surface of the uppermost brick 4T is the above-mentioned acting force (component force). Influence P ₂ ).

Specifically, if the acting force described above, in other words, the rearward facing force generated by the difference in the coefficient of thermal expansion between iron (furnace mouthpiece 5) and refractory (uppermost brick 4T) is F ₂ , The inward component of the furnace is P ₂ = sin θ ₁ × F ₂ .
P ₂ = sin θ ₁ × F ₂ (4)
Here, P _2: thermal component of the expansion furnace inward uppermost bricks 4T receives from the difference between the theta _1: inclination angle upper surface of the uppermost bricks 4T makes with furnace direction Incidentally, the uppermost bricks 4T Since the coefficient of thermal expansion of the drawing brick 4S is almost the same, it is not necessary to consider the acting force caused by the difference in coefficient of thermal expansion, and the inclination angle of the lower surface of the uppermost brick 4T is the above-mentioned component force P ₂ . Is irrelevant.

The above-mentioned inward component force P ₁ and component force P ₂ using the elastic coefficient E, which is a physical property value, the linear expansion coefficient α, and the temperature increase amount ΔT, are expressed by the following equation (3 ′) and It is represented by formula (4 ′). In addition, "A" used as a subscript indicates that the refractory, that is, the uppermost brick has a physical property value of 4T. Further, “B” used in the subscript indicates that the physical property value of the metal, that is, the furnace mouthpiece 5.

P ₁ = sin (1/2 × (θ ₁ -θ ₂ )) (α _A ΔT _A・ E _A ) ・ ・ ・ (3 ′)
P ₂ = sin θ ₁ · E _A (α _B ΔT _B -α _A ΔT _A ) ・ ・ ・ (4 ′)
The in-furnace component force P ₁ represented by the above equation (3 ′) and the in-furnace component force P ₂ represented by the equation (4 ′) are obtained, and the sum of these component forces (P ₁ + P _It is preferable to use the inclination angle θ ₁ of the upper surface of the uppermost brick 4T such that ₂ ) has a minimum value, for example, 0 or less, preferably negative. If the sum of the above component forces (P ₁ + P ₂ ) is set to 0 or less, preferably negative, it is possible to prevent the uppermost brick 4T from falling off the narrowed portion 2.

Further, regarding the brick falling-off preventing structure of the throttle unit 2 that satisfies the above-described relationship, it is better to further satisfy the relationship of the following expression (2).
θ ₁ ≧ 0.5 θ ₂ + X and θ ₁ > 0 ・ ・ ・ (2)
However, X is a constant of 0 or more and 10 or less If the relation of the above-mentioned formula (2) is satisfied, even if the metal adhered to the working surface 6 is knocked off in the vertical direction, the uppermost brick 4T falls off. This prevents the uppermost brick 4T from falling off more reliably.

Next, the function and effect of the brick fall-out prevention structure of the present invention will be described in detail with reference to Comparative Examples and Examples.
In the comparative example and the example, when the uppermost brick 4T and the furnace mouthpiece 5 having the characteristic values shown in Table 1 are used and the heat is applied under the temperature conditions shown in Table 1, the uppermost brick 4T acts on the uppermost brick 4T. This is the sum of the component forces (P ₁ + P ₂ ) toward the inside of the furnace.

The elastic coefficient E and the linear expansion coefficient α shown in Table 1 are general values for refractory materials and cast iron, and the temperature rise amount ΔT is the temperature of the refractory material and the iron shell 3 and is empirically determined from past measurement results. The value obtained in was used.
Regarding the inclination angle θ _{1 formed} by the upper surface of the uppermost brick 4T with respect to the horizontal direction and the inclination angle θ _{2 formed by} (the upper surface or the lower surface of) the diaphragm brick 4S with respect to the horizontal direction, θ ₁ and θ ₂ are set. All of them are changed at nine levels of -20 °, -15 °, -10 °, -5 °, 0 °, 5 °, 10 °, 15 °, 20 °, and in each combination of θ ₁ and θ ₂ (P The value of ₁ + P ₂ ) was calculated. The value of (P ₁ + P ₂ ) thus obtained is plotted on a graph in which the horizontal axis is the tilt angle θ ₁ and the vertical axis is the tilt angle θ _2, and is shown in FIG.

The actual measurement value for the sum of the component forces in the furnace direction (P ₁ + P ₂ ) described above is the size of the circle (diameter size) plotted in FIG. 5, and is the absolute value of the calculated value. The size is shown. As for the color of the circle plotted in FIG. 5, black color indicates a positive value and white color indicates a negative value.
Looking at FIG. 7, the actual measurement values shown by the white circles and the actual measurement values shown by the black circles are distributed in the lower right and upper left among the actual measurement values arranged vertically and horizontally on the graph. There is. From this, whether or not the sum of the above-mentioned inward component forces (P ₁ + P ₂ ) has a negative value is determined by the boundary of the line where the slope of θ ₁ with respect to θ ₂ is 0.5. Conceivable. That is, when the inclination angle θ ₁ of the upper surface of the uppermost brick 4T satisfies the relationship of the following expression (5) with respect to the inclination angle θ ₂ of the diaphragm brick 4S, the sum of component forces (P ₁ + P ₂ ) Is a negative value.

θ ₁ ＞ 0.5 θ ₂・ ・ ・ (5)
Note that it is desirable to impose a strict condition on θ ₁ if the acting force by hitting the adhered metal with a heavy machine is also assumed. Therefore, it is more realistic to add X as a safety factor to the right side of Expression (5). From such a concept, the derived formula is the following formula (2).
θ ₁ ≧ 0.5 θ ₂ + X and θ ₁ > 0 ・ ・ ・ (2)
However, X is a constant of 0 or more and 10 or less. When the above safety factor is set to X = 0, in other words, when the safety factor is not considered, the sum of component forces in the furnace direction acting on the uppermost brick 4T. (P ₁ + P ₂ ) has a negative value when the value of (P ₁ + P ₂ ) exists on the right side of the solid line in FIG. 7. Equation (2) in this case is substantially the same as equation (5). The expression (2) when X = 0 shows the minimum inclination angle θ _{1 at} which the uppermost brick 4T does not fall off.

On the other hand, considering the acting force caused by hitting the adherent metal with a heavy machine, the safety factor X is set to 5 or more so that the value of (P ₁ + P ₂ ) exists on the right side of the dotted line in FIG. 7. Good to do. Furthermore, more preferably, assuming that the impact force of the adhered metal is the largest, the safety factor X is set so that the value of (P ₁ + P ₂ ) exists on the right side of the alternate long and short dash line in FIG. Should be 10 or more. From the results described above, the relationship “X is a constant of 0 or more and 10 or less” as shown in Expression (2) is derived.

From the above, by obtaining the inclination angle θ ₁ that satisfies the relationship of the expression (1) described above, preferably the expression (2) in addition to the expression (1), the uppermost brick 4T is surely prevented from falling off. can do.
That is, as shown in “Prior Art 1” of FIG. 6B, when the operating surface 6 of the uppermost brick 4T has a shape protruding toward the inside of the furnace as it goes upward, the protruding portion is an obstacle. As a result, it becomes difficult to knock down the metal attached to the working surface 6.

In addition, as shown in “Prior Art 2” in FIG. 6C, when the uppermost brick 4T has a shape that does not satisfy the above-described formulas (1) and (2), the component force (P ₁ + P ₂ ) acts, and the top brick 4T easily falls off.
However, in the “present invention” of FIG. 6 (A), it is easy to knock down the metal on the working surface 6, and the topmost brick 4T does not fall off, so the metal can be easily knocked off. It is possible to exert an excellent effect that it is possible to reliably prevent the uppermost brick 4T from falling off.

  It should be considered that the embodiments disclosed this time are exemplifications in all points and not restrictive. In particular, in the embodiments disclosed this time, matters not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, and volumes of components deviate from the scope normally practiced by those skilled in the art. However, a value that can be easily assumed by a person having ordinary skill in the art is adopted.

1 Converter 2 Drawing part 3 Iron skin 4 Brick 4T Top brick 4S Drawing brick 5 Furnace mouthpiece 6 Operating surface 7 Height adjuster

Claims (3)

It has a brick falling prevention structure that prevents the bricks stacked in the narrowed part of the converter from falling off.
Regarding the uppermost brick arranged at the uppermost part of the narrowed portion, the uppermost brick has an upper surface inclined at an inclination angle θ ₁ so as to face upward from the inner side of the furnace toward the rear side, and A structure that prevents the falling of the goodwill of the narrowed part, whose surface is formed to face vertically. The combined force between the force inward of the furnace due to the vertical interference of the stacked bricks and the force inward of the furnace due to the difference in expansion between the furnace mouthpiece and the bricks arranged in the throttle part is minimized. The tilt angle θ ₁ is set in the structure according to claim 1, wherein the goodwill of the narrowed portion is prevented from falling off. When the upper surface of the diaphragm brick arranged from the middle stage to the lower stage of the throttle portion has an inclination angle θ ₂ with respect to the horizontal direction, the inclination angle is set so as to satisfy the relationship represented by the formula (2). θ ₁ is set. The structure for preventing falling of the goodwill of the throttle portion according to claim 1 or 2, wherein.
θ ₁ ≧ 0.5 θ ₂ + X and θ ₁ ＞ 0 ・ ・ ・ (2)
However, X is a constant from 0 to 10