JP2023136044A - Gas blowing plug and gas blowing plug production method - Google Patents

Abstract

To increase a gas flow rate compared with the conventional plugs.SOLUTION: A gas blowing plug comprises: a core body part 2 made of a porous refractory; an outer circumferential part 3 made of a dense refractory and at least partially surrounding the core body part 2; a gas pool 5 in contact with the core body part 2; and a gas feed pipe 6 fluid-connected to the gas pool 5. A clearance 7 at least partially extending to a space between the core body part 2 and the outer circumferential part 3 and not contacted with the gas pool 5 is provided, and the clearance 7 is opened at a tip face 12.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas injection plug and a method for manufacturing a gas injection plug.

BACKGROUND ART A commonly used method for stirring molten metal in a container for handling molten metal, such as a ladle or a crucible, is to blow gas from the bottom of the container and cause the molten metal to flow with the gas. As shown in FIG. 8, the gas blowing plug attached to the bottom of the container for this purpose includes a core portion 2 made of porous refractory material, and a dense refractory material provided surrounding the core portion 2. A gas blowing plug 8 is exemplified, which includes an outer peripheral portion 3 made of material and an air supply pipe 6 that supplies gas to the core portion 2. In this gas blowing plug 8, the core portion 2 functions as a gas flow path, and the gas supplied from the air supply pipe 6 passes through the core portion 2 and is discharged from the tip surface 22 into the container (path A ). This type of gas injection plug is sometimes referred to as a porous plug.

In a porous plug, molten metal adheres to the tip and penetrates into the pores of the porous refractory, causing the gas path to become clogged. Due to this phenomenon, the gas flow rate in the porous plug gradually decreases through repeated operations. Blockage of the porous plug can be resolved by oxygen cleaning by spraying oxygen on the tip, but at this time the refractory is eroded, so repeated oxygen cleaning shortens the life of the porous plug. Therefore, in order to extend the life of the porous plug, it is necessary to reduce the frequency of oxygen cleaning by making it difficult for molten metal to adhere to the tip, and various structures are being considered for this purpose.

For example, Japanese Utility Model Application Publication No. 3-68958 (Patent Document 1) discloses a porous plug in which a porous joint is provided around a plug body made of a porous refractory. According to the porous plug of Patent Document 1, when the plug body is occluded, the joints are eroded and the lower part of the occluded part (infiltrated layer) is eroded and the occluded part peels off, so that the plug occludes itself. be done.

Furthermore, in Japanese Patent Application Laid-Open No. 9-194927 (Patent Document 2), in place of the core part made of porous refractories used in general porous plugs, rod-shaped refractories made of dense refractories are used in a staggered pattern. A plug is disclosed in which the rod-shaped refractories are arranged side by side and the joints between the rod-shaped refractories are used as gas flow paths. According to the plug disclosed in Patent Document 2, since the cross-sectional area of each gas flow path is small, it is difficult for molten metal to enter and blockage is difficult to occur.

Utility Model Publication No. 3-68958 Japanese Patent Application Publication No. 9-194927

Although the technology of Patent Document 1 reduces the need for maintenance work when a blockage occurs, the gas flow rate during normal times was similar to the technology prior to Patent Document 1. In addition, in the technique of Patent Document 2, the side surface of the rod-shaped refractory disposed at the outermost periphery is blocked by the dense refractory at the outer periphery, making it difficult to increase the gas flow rate. As described above, the conventional plug has room for improvement from the viewpoint of increasing the gas flow rate.

Therefore, there is a need for a gas injection plug that can increase the gas flow rate compared to conventional plugs and a method for manufacturing the same.

The gas injection plug according to the present invention includes a core made of a porous refractory, an outer peripheral part made of a dense refractory that at least partially surrounds the core, and a gas pool in contact with the core. and an air supply pipe in fluid communication with the gas pool, a gap extending at least partially between the core portion and the outer circumferential portion and not in contact with the gas pool; It is characterized in that the void is open.

According to this configuration, the path for the gas supplied from the air supply pipe to flow out from the tip of the gas blowing plug is through the tip surface of the core portion, and the side surface and gap of the core portion. Two routes are formed: a route and a route. Of these, the former is a route that similarly exists in the gas injection plug according to the prior art, but the latter is a route that does not exist in the gas injection plug according to the prior art, so in the above configuration, the latter route is The number of gas flow paths is increased compared to the conventional technology. This allows for increased gas flow rates compared to conventional plugs.

Further, the method for manufacturing a gas blowing plug according to the present invention includes a first step of forming a preformed body of a gas blowing plug, a second step of firing the preformed body, and the first step is a step of forming a core portion of the preform using a porous refractory, a step of forming an outer peripheral portion of the preform using a dense refractory, and a step of forming the core of the preform using a dense refractory. placing a combustible material between the body portion and the outer peripheral portion, the second step including burning out at least a portion of the combustible material, and placing the combustible material. In the step, the combustible material is arranged so as to be exposed at the distal end surface of the preformed body and not exposed at the proximal end surface of the preformed body.

According to this configuration, since the method of providing the gap is relatively simple, a plug with an increased gas flow rate compared to a conventional plug can be obtained without impairing productivity.

Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited to the preferred embodiments described below.

In one embodiment, the gas blowing plug according to the present invention preferably further includes a metal case that at least partially surrounds the outer peripheral portion.

According to this configuration, the air supply pipe can be easily installed. Moreover, it can be used as a support part for pulling out and replacing the gas injection plug.

In one embodiment of the gas blowing plug according to the present invention, the width of the gap is preferably 0.10 mm or more and 0.50 mm or less.

According to this configuration, it is easy to ensure gas flow rates for both the path passing through the distal end surface of the core portion and the path passing through the side surface and gap of the core portion, so that both paths are unlikely to be clogged.

In one embodiment of the method for manufacturing a gas blowing plug according to the present invention, it is preferable that the combustible material is in the form of a wire, a rod, a sheet, or a combination thereof.

According to this configuration, voids with uniform thickness can be easily formed.

Further features and advantages of the invention will become clearer from the following description of exemplary and non-limiting embodiments, written with reference to the drawings.

FIG. 2 is a longitudinal cross-sectional view of a gas blowing plug according to an embodiment. FIG. 3 is a top view of the gas blowing plug according to the embodiment. 2 is a cross-sectional view taken along line III-III in FIG. 1. FIG. It is a figure showing the procedure of manufacturing a gas blowing plug concerning an embodiment. It is a figure showing the procedure of manufacturing a gas blowing plug concerning an embodiment. It is a figure showing the procedure of manufacturing a gas blowing plug concerning an embodiment. It is a figure showing the procedure of manufacturing a gas blowing plug concerning an embodiment. FIG. 2 is a longitudinal cross-sectional view of a gas blowing plug according to the prior art. It is a figure showing the result of an air circulation test.

Embodiments of a gas blowing plug and a method of manufacturing a gas blowing plug according to the present invention will be described with reference to the drawings. Below, an example in which the gas blowing plug according to the present invention is applied to a gas blowing plug 1 (hereinafter simply referred to as "plug 1") installed at the bottom of a molten metal refining container will be described.

[Plug configuration]
The plug 1 according to this embodiment includes a core portion 2, an outer peripheral portion 3 surrounding the core portion 2, and a metal case 4 that accommodates the core portion 2 and the outer peripheral portion 3 (FIG. 1). The base end surface 21 of the core portion 2 is in contact with the gas pool 5 , and an air supply pipe 6 that is in fluid communication with the gas pool 5 is welded to the metal case 4 . The plug 1 is a porous plug that discharges gas supplied from the base end 11 side from the distal end surface 12, and the core portion 2 made of porous refractory functions as a gas flow path. A gap 7 is provided between the core portion 2 and the outer peripheral portion 3, and the gap 7 is open to the tip end surface 12 of the plug 1.

The tip of the plug 1 refers to the side exposed inside the molten metal refining container when the plug 1 is used (the upper side in Figure 1), and the base end of the plug 1 refers to the side exposed inside the molten metal refining container when the plug 1 is used. This refers to the side facing outward (the lower side in Figure 1). Therefore, the tip end surface 12 of the plug 1 is exposed to molten metal during use.

The core portion 2 is made of porous refractory material. As the porous refractory, porous refractories commonly used in this field can be used, such as high alumina refractories, magnesia refractories, and the like. That is, the porous refractory is a press-molded product that can contain metal oxides of alumina, magnesia, and chromia. Further, the porous refractory may contain carbon, mullite, zirconia compounds, boron compounds, clay, and the like.

The shape of the core portion 2 is not particularly limited, and may be any shape such as a truncated cone or a truncated pyramid. In this embodiment, as an example, the upper portion 24 of the core portion 2 has a truncated cone shape, and the lower portion 25 has a truncated quadrangular pyramid shape (FIGS. 2 and 3). The tip surface 22 of the core portion 2 is circular.

The outer peripheral portion 3 is made of a dense refractory material and is provided in such a manner as to surround the core portion 2 in the circumferential direction. As the dense refractory material constituting the outer peripheral portion 3, dense refractories commonly used in this field can be used, and for example, refractories such as high alumina, alumina magnesia, alumina spinel, etc. can be used. . That is, the dense refractory is a cast product that can contain metal oxides such as alumina, magnesia, spinel, and the like. Further, the dense refractory may contain alumina cement, silica flour, metal powder, a dispersant, and the like.

In this embodiment, an example is shown in which the outer peripheral portion 3 has a truncated conical shape. Correspondingly, the tip surface 12 and the cross section of the plug 1 are circular (FIGS. 2, 3). Note that the cross-sectional shapes of the core portion 2 and the outer peripheral portion 3 may be different, or the cross-sectional shapes of both may be of the same type (circular and circular, etc.).

The metal case 4 is a metal case that houses the core portion 2 and the outer peripheral portion 3. The metal constituting the metal case 4 is not particularly limited, and may be, for example, SPCC, SUS304, or the like. The metal case 4 is open on the distal end side of the plug 1, so that the core portion 2 and the outer peripheral portion 3 are exposed at the distal end surface 12 of the plug 1. On the other hand, the side surfaces and proximal ends of the core portion 2 and the outer peripheral portion 3 are surrounded by a metal case 4.

A gas pool 5 is provided between the base end surface 21 of the core portion 2 and the base end surface 31 of the outer peripheral portion 3 and the metal case 4. The gas pool 5 is a space in which no tangible member is provided, and functions as a space for the gas flowing in from the air supply pipe 6 to diffuse in the lateral direction (in the direction intersecting the longitudinal direction of the plug 1).

Further, an air supply pipe 6 that fluidly communicates with the gas pool 5 is welded to the metal case 4. The air supply pipe 6 is a metal pipe, and the metal may be, for example, SGP, STPG370, or the like. The metal that constitutes the metal case 4 and the metal that constitutes the air supply pipe 6 may be the same metal, or may be different metals as long as they can be welded together.

In the plug 1 according to this embodiment, a gap 7 is provided between the upper portion 24 of the core portion 2 and the outer peripheral portion 3. On the other hand, no gap is provided between the lower portion 25 of the core portion 2 and the outer peripheral portion 3. Therefore, the gap 7 opens at the distal end surface 12 of the plug 1 and extends along the core portion 2 and the outer peripheral portion 3, but does not touch the gas pool 5 (FIGS. 1 to 3).

Gas supplied to the plug 1 from a gas source (not shown) reaches the gas pool 5 through the air supply pipe 6, and diffuses in the radial direction of the plug 1 in the gas pool 5. It enters the pores of body part 2. The gas further passes through the core portion 2 and a portion thereof flows into the interior of the molten metal refining vessel through the tip face 22. A portion also flows into the gap 7 from the side surface 23 and flows into the interior of the molten metal refining vessel via the gap 7. In this way, in the plug 1 according to the present embodiment, the path A (which similarly exists in the conventional plug 8 (FIG. 8)) passing through the tip surface 22 is used as a path for gas to flow into the interior of the molten metal refining container. ), a route B passing through the side surface 23 and the gap 7 is additionally provided. Thereby, the amount of ventilation of the plug 1 can be improved.

In this embodiment, the width of the gap 7 is set to 0.30 mm. As in this example, when the width of the gap 7 is 0.10 mm or more, gas easily flows into the gap 7, so that it is easy to ensure a sufficient gas flow rate for the plug 1 as a whole. Furthermore, if the width of the gap 7 is 0.50 mm or less, it is difficult for molten metal to flow into the gap 7, so that clogging of the gap 7 can be easily avoided. The width of the void 7 is more preferably 0.15 mm or more, and even more preferably 0.18 mm or more. Further, the width of the void 7 is more preferably 0.45 mm or less, and even more preferably 0.40 mm or less.

Note that since the void 7 is provided in such a manner that it does not come into contact with the gas pool 5, both the gases in the path A and the path B pass through the core portion 2. Thereby, it is easy to ensure a sufficient gas flow rate in both the path A and the path B, and it is possible to suitably prevent molten metal from adhering to the entire tip surface 12 of the plug 1. On the other hand, if the void 7 were in contact with the gas pool 5, most of the gas would bypass the core portion 2 and flow into the molten metal refining container via the void 7, so the gas at the tip surface 22 would be The flow rate of the molten metal decreases significantly, and molten metal tends to adhere to the tip surface 22.

[Plug manufacturing method]
Next, a method for manufacturing the plug 1 will be explained. The method for manufacturing the plug 1 includes a first step of forming a preformed body 1a of the plug 1, a second step of firing the preformed body 1a, and a housing of the fired body obtained in the second step in a metal case 4. A third step of doing so. The first step includes forming a core portion 2a of the preform 1a, a second step of surrounding the core portion 2a of the preform 1a with a combustible material 7a, and a second step of forming the core portion 2a of the preform 1a. It is further divided into a third step of forming the outer peripheral portion 3a.

(1) First step In the first step of the first step, the core portion 2a of the preform 1a is formed using a porous refractory (FIG. 4). The porous refractories used here are as listed above, and the core portion 2a of the preform 1a is shaped so that the desired shape of the core portion 2 of the plug 1 is obtained after firing the preform 1a. The shape is determined. Note that tools, auxiliary agents, etc. that are commonly used for preforming porous refractories may be used.

In the second step of the first process, the core portion 2a of the preform 1a is surrounded by a combustible material 7a (FIG. 5). The combustible material 7a used here is a substance that burns at the firing temperature (for example, 500° C. or lower) of the porous refractory that constitutes the core portion 2 of the plug 1 and the dense refractory that constitutes the outer peripheral portion 3. . Further, the position and size of the combustible material 7a are determined so that the voids formed by burning off the combustible material 7a during firing of the preform 1a have the desired shape of the voids 7. In particular, the combustible material 7a is aligned flush with the tip surface 22a of the core portion 2a, corresponding to the fact that the gap 7 is open to the tip surface 12 of the plug 1 and does not touch the gas pool 5. However, it does not reach the proximal end surface 21a of the core portion 2a. It is preferable that the combustible material 7a is linear, rod-shaped, sheet-shaped, or a combination thereof, since the voids 7 having a uniform thickness can be easily formed.

In the third step of the first process, the outer peripheral portion 3a of the preform 1a is formed using a dense refractory (FIG. 6). In this embodiment, the third step is performed after the second step, so for the portion where the core portion 2a is surrounded by the combustible material 7a, the outer peripheral portion is 3a will be formed. The dense refractories used here are as listed above, and the shape of the outer peripheral portion 3a of the preform 1a is adjusted so that the outer peripheral portion 3 of the preform 1a has the desired shape after firing the preform 1a. It is determined. Note that tools, auxiliary agents, etc. that are commonly used for preforming dense refractories may be used.

Through the above three steps, a preformed body 1a including a core portion 2a, an outer peripheral portion 3a, and a combustible material 7a is obtained. As is clear from the above procedure, the second step can be said to be a step of arranging the combustible material 7a between the core portion 2a and the outer peripheral portion 3a of the preformed body 1a.

(2) Second step The second step is a step of firing the preformed body 1a. Known equipment and firing conditions can be used for firing, including the types of porous refractories and dense refractories used, the types of auxiliary materials such as additives and auxiliaries, and the dimensions of the preform 1a. The decision will be made taking into account the following. During firing of the preformed body 1a, the combustible material 7a is burned out, and a fired body 1b in which voids 7 are formed is obtained (FIG. 7). That is, the second step includes burning out at least a portion of the combustible material 7a.

(3) Third step The third step is a step in which the fired body 1b obtained in the second step is housed in the metal case 4. The third step can be carried out by a method normally carried out when housing a fired refractory body in a metal case in a porous plug manufacturing method.

[Other embodiments]
Finally, other embodiments of the gas blowing plug and the method of manufacturing the gas blowing plug according to the present invention will be described. Note that the configurations disclosed in each of the embodiments below can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction occurs.

In the above embodiment, the configuration in which the gap 7 is provided over the entire circumference of the upper portion 24 of the core portion 2 has been described as an example. However, in the gas blowing plug according to the present invention, it is sufficient that the gap at least partially extends between the core portion and the outer circumferential portion, and the gap may have a shape that surrounds the core portion as in the above example. It doesn't have to be a void.

In the above embodiment, the configuration in which the plug 1 includes the metal case 4 has been described as an example. However, the gas blowing plug according to the present invention may not include a metal case. Further, when a metal case is provided, the entire outer peripheral portion may be housed in the metal case as in the above embodiment, but only a part of the outer peripheral portion may be housed in the metal case.

In the above embodiment, the method for manufacturing the plug 1 includes a first step of forming the core portion 2a of the preform 1a, a second step of surrounding the core portion 2a of the preform 1a with a combustible material 7a, The third step of forming the outer circumferential portion 3a of the preformed body 1a is performed in this order to obtain the preformed body 1a. However, in the first step of the method for manufacturing a gas injection plug according to the present invention, as long as a preform in which a combustible material is disposed between the core portion and the outer peripheral portion is obtained, the order of implementation of each step is is not limited.

Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects, and the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that modifications can be made as appropriate without departing from the spirit of the present invention. Therefore, other embodiments that are modified without departing from the spirit of the present invention are naturally included within the scope of the present invention.

In the following, the present invention will be further explained by showing examples. However, the following examples do not limit the present invention.

[Air circulation test]
(Example and comparative example)
As Example 1, a plug having the cross-sectional shape shown in FIG. 1 was manufactured. As a comparative example, a plug having a cross-sectional shape shown in FIG. 8 was manufactured. The porous refractories constituting the core portions of both plugs and the dense refractories constituting the outer peripheral portions were the same. Specifically, the composition of the porous refractory was 89% alumina, 7% silica, and 2% chromia, and the composition of the dense refractory was 91% alumina and 7% magnesia. The total length of the refractory portion (core portion and outer peripheral portion) of the plug was 300 mm. The upper part of the core part was shaped like a truncated cone, with a length of 240 mm, an upper end diameter of 80 mm, and a lower end diameter of 120 mm. Further, the lower part had a truncated pyramid shape with a square cross section, a length of 60 mm, a side of the upper end of 80 mm, and a side of the lower end of 100 mm. In the plug of Example 1, the width of the gap was 0.3 mm. On the other hand, the plug of the comparative example had a structure in which the core portion and the outer peripheral portion were in close contact with each other, and no void was provided.

(evaluation)
Each plug of the example and comparative example was connected to a gas source (not shown), gas was supplied at a pressure in the range of 0.1 to 0.3 MPa, and the gas flow rate (in L/min) was measured. FIG. 9 shows the relationship between pressure and flow rate for each plug. It was revealed that when the plug of Example 1 was used in the gas supply pressure range of 0.1 to 0.3 MPa, the gas flow rate was improved compared to the case where the plug of Comparative Example was used. .

[Actual use test]
(Example and comparative example)
In addition to the above Example 1 and Comparative Example, Examples 2 to 8 were produced which had the same structure as the plug of Example 1 except that the width of the gap was changed in the range of 0.10 to 0.70 mm. Note that specific values of the gap width in each example are shown in Table 1 below.

(evaluation)
Each nozzle of Examples 1 to 8 and Comparative Example was attached to a 300 ton ladle and used for batch casting of steel. At the end of each batch, if the flow rate when gas is supplied to the gas blow plug at a pressure of 0.1 MPa is less than 150 L/min, perform oxygen cleaning, and if the height of the gas blow plug is 60 mm or less has determined that the plug is unusable. The number of times each plug was judged to be unusable was recorded (Table 1). In Examples 1 to 8, it was observed that the lifespan was extended compared to the comparative example (nozzle according to the prior art) having no voids. In Examples 1 to 7 in which the width of the void was 0.10 mm or more and 0.50 mm or less, the life span was particularly significantly extended.

Table 1: Actual use test

The present invention can be used, for example, as a gas blowing plug installed at the bottom of a molten metal refining vessel.

1: Gas blowing plug 11: Base end of gas blowing plug 12: Distal end surface of gas blowing plug 2: Core portion 21: Base end surface of core portion 22: Distal end surface of core portion 23: Core portion 3: Outer peripheral portion 31: Base end surface of the outer peripheral portion 4: Metal case 5: Gas pool 6: Air supply pipe 7: Gap 1a: Preformed body 2a: Core portion of the preformed body 21a: Core body of the preformed body Base end surface of the part 22a: Distal end surface of the core portion of the preform 3a: Outer peripheral portion of the preform 7a: Flammable material 8: Gas blowing plug (prior art)
A, B: Gas route

Claims (5)

A core part made of porous refractory material,
an outer peripheral portion made of a dense refractory that at least partially surrounds the core portion;
a gas pool in contact with the core portion;
an air supply pipe in fluid communication with the gas pool;
A gap is provided that extends at least partially between the core portion and the outer peripheral portion and does not contact the gas pool,
A gas blowing plug in which the gap is opened at the tip surface. The gas blowing plug according to claim 1, further comprising a metal case that at least partially surrounds the outer peripheral portion. The gas blowing plug according to claim 1 or 2, wherein the width of the gap is 0.10 mm or more and 0.50 mm or less. A first step of forming a preformed body of a gas blowing plug, and a second step of firing the preformed body,
The first step is
forming a core portion of the preform using a porous refractory;
forming an outer peripheral portion of the preform using a dense refractory;
disposing a combustible material between the core portion and the outer peripheral portion of the preform;
The second step includes burning out at least a portion of the combustible material,
A method for manufacturing a gas blowing plug, wherein in the step of arranging the combustible material, the combustible material is arranged so as to be exposed on the distal end surface of the preform and not exposed on the proximal end surface of the preform. . The method for manufacturing a gas injection plug according to claim 4, wherein the combustible material is linear, rod-shaped, sheet-shaped, or a combination thereof.

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