Gas blowing pipe
Patent Information
- Application Number
- JP2023108232
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-06-30
- Publication Date
- 2025-01-17
Smart Images
Figure 2025007071000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a gas injection tube that is immersed in a molten metal in a molten metal container and injects gas into the molten metal. [Background technology]
[0002] Conventionally, in order to eliminate gases such as oxygen and hydrogen mixed in the molten metal, gas injection has been performed by injecting an inert gas into the molten metal. For example, a gas injection device for a holding furnace described in Patent Document 1 as a conventional example is configured by installing a gas injection tube in the molten metal holding furnace and extending the tip of the gas injection tube to the vicinity of the bottom surface of the molten metal holding furnace. A porous blowing tool is connected to the tip of the gas injection tube. The inert gas flows into the holding furnace through the blowing tube and diffuses into the molten metal through the pores of the blowing tool. According to this configuration, the inert gas physically adsorbs to the oxygen in the molten metal, thereby making the oxygen inert. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 4-200858 Summary of the Invention [Problem to be solved by the invention]
[0004] However, in the conventional example, since the blowing tool is connected only to the tip of the gas blowing pipe, there is a risk that the blowing tool will fall off and be damaged by the gas pressure when the gas is blown in. In that case, there is a risk of bumping, in which gas is blown out forcefully from the tip. In addition, when pressure is applied inside the holding furnace, there is a risk of the molten metal flowing back into the gas blowing pipe.
[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a gas injector tube that reduces the risk of the tip falling off. [Means for solving the problem]
[0006] A gas injection pipe according to an aspect of the present invention is a gas injection pipe that is immersed in a molten metal in a molten metal container to inject gas, and includes a cylindrical pipe member having a first pipe end on the downstream side and a second pipe end on the upstream side in a gas flow direction, a porous member formed inside the pipe member, a protective material covering the outside of the pipe member, and a gas pipe connected to the upstream side of the pipe member, the direction connecting the first pipe end and the second pipe end is defined as an axial direction, and a direction perpendicular to the axial direction is defined as a radial direction, and the porous member is configured to extend from the downstream end to the upstream side. In a predetermined range, at least a part of the outer periphery of the porous member has a step that is recessed in the radial direction, the pipe member has a pipe protrusion that has a predetermined thickness in the axial direction at the pipe first end relative to a pipe wall portion that forms the outer periphery and protrudes radially inwardly, the pipe protrusion covers at least a part of the downstream side of the step in the porous member, at least a part of the porous member protrudes downstream further than the pipe first end, and the protective material is formed to cover the outer periphery of the pipe member and the pipe first end with at least a part of the porous material first end, which is the downstream end of the porous member, exposed to the downstream side.
[0007] According to this, the step portion of the porous member on the downstream side, which is the tip portion, is covered by the pipe protruding portion, so that it is possible to reduce the possibility of the porous member falling off and being damaged by the gas pressure when the gas is blown in. Furthermore, since the protective material is formed to cover the first end portion of the pipe, it is possible to reduce the possibility of the pipe member being melted and damaged by the heat of the molten metal. Therefore, it is possible to further reduce the possibility of the porous member falling off and being damaged.
[0008] In addition, the first end of the porous material of the gas injection pipe may be on the same plane as the first end of the protective material, which is the downstream end of the protective material, or may protrude downstream further than the first end of the protective material.
[0009] In this case, the downstream end of the porous member is on the same plane as the downstream end of the protective material or protrudes downstream, thereby reducing condensation of the gas blown through the porous member.
[0010] The gas blowing pipe may have a first end portion of the porous material recessed toward the upstream side from a first end portion of the protective material, which is a downstream end portion of the protective material. In this case, the first end portion of the porous material recessed toward the upstream side from the first end portion of the protective material, thereby reducing the possibility of the porous material falling off.
[0011] In addition, the gas blowing pipe has a protective material inclined portion formed so that the protective material opens more widely on the side of the first end of the protective material in the axial direction. In this case, the gas blown from the porous material is blown along the inclined surface of the protective material, so that coagulation of the gas can be reduced.
[0012] The gas blowing pipe may have a protective material fall-off prevention portion formed between an outer periphery of the pipe wall portion and an outer periphery of the protective material. In this case, it is possible to reduce the protective material from falling off from the outer periphery of the pipe member.
[0013] In addition, the gas injection pipe may be a lath net in which the anti-fall-out portion is formed to surround the outer periphery of the pipe, and the downstream end of the lath net may be formed downstream of the first end of the pipe.
[0014] In this case, the lath mesh, which is the anti-fall-off portion, is formed downstream of the first end of the pipe, thereby further reducing the protective material falling off from the outer periphery of the pipe member.
[0015] In addition, the gas blowing pipe may have a concave-convex portion formed on the outer periphery of the pipe as the fall-off prevention portion. In this case, the concave-convex portion is formed on the outer periphery of the pipe wall portion, so that it is possible to reduce the protective material from falling off from the outer periphery of the pipe member.
[0016] Moreover, the gas injection pipe may be configured such that the pipe member has a first pipe member and a second pipe member, the inner diameter of the second pipe member is smaller than the inner diameter of the first pipe member, the pipe protruding portion is formed in the first pipe member, the upstream inner wall surface of the pipe protruding portion and the porous member are in contact with each other via a first sealant, the downstream end of the gas pipe and the porous member are in contact with each other via a second sealant that sandwiches both sides of a washer, the first pipe member and the second pipe member are integrally joined, and the gas pipe is fastened to the second pipe member.
[0017] In this case, the porous member contacts the pipe protruding portion of the first pipe member on the downstream side via the first sealant, and contacts the gas pipe and the washer on the upstream side via two second sealants that sandwich the gas pipe and the washer, and the gas pipe is further fastened to the second pipe member. This improves the airtightness between the first pipe member, the porous member, and the gas pipe, and reduces gas leakage from other than the porous member.
[0018] Furthermore, the gas injection pipe may have a pipe protruding portion that covers the downstream side of the step in the porous member over the entire circumference in the circumferential direction. In this case, since the pipe protruding portion covers the step in the porous member over the entire circumference in the circumferential direction, the pipe protruding portion can support the porous member evenly in the circumferential direction when the porous member tries to pass through to the downstream side.
[0019] Furthermore, the gas injection pipe may have a pipe protruding portion that covers the downstream side of the step in the porous member over a portion of the circumferential direction. In this case, since the pipe protruding portion covers the step in the porous member over a portion of the circumferential direction, the pipe protruding portion can support the porous member when it tries to slip out to the downstream side. [Brief description of the drawings]
[0020] [Figure 1] FIG. 2 is a diagram showing a state in which the gas-blowing tube 1 of the present invention is immersed in a molten metal container 60. [Diagram 2]FIG. 1 shows a gas injection pipe 1a according to a first embodiment of the present invention, in which (a) is a cross-sectional view of the downstream tip portion cut along the axial center C, and (b) is an oblique view of the downstream tip portion of (a), in which the hatched area with dashed lines indicates the portion where the porous member 3a is exposed. [Diagram 3] FIG. 1 shows a partial modification of the gas injection pipe 1a according to the first embodiment of the present invention, in which (a) is a cross-sectional view of the downstream tip portion cut along the axial center C, (b) is a first example of a detailed view of part A, and (c) is a second example of a detailed view of part A. [Figure 4] FIG. 1 shows a gas injection pipe 1b according to a second embodiment of the present invention, in which (a) is a cross-sectional view of the downstream tip portion cut along the axial center C, and (b) is an oblique view of the downstream tip portion of (a), and the hatched area with dashed lines indicates the portion where the porous member 3b is exposed. [Diagram 5] FIG. 1 shows a gas injection pipe 1c according to a third embodiment of the present invention, in which (a) is a cross-sectional view of the downstream tip portion cut along the axial center C, and (b) is an oblique view of the downstream tip portion of (a), in which the hatched area with dashed lines indicates the portion where the porous member 3c is exposed. [Figure 6] FIG. 1 shows a gas injection pipe 1d according to a fourth embodiment of the present invention, in which (a) is a cross-sectional view of the downstream tip portion cut along the axial center C, and (b) is an oblique view of the downstream tip portion of (a), and the hatched area with dashed lines indicates the portion where the porous member 3d is exposed. [Figure 7] FIG. 1 shows a gas injection pipe 1e according to a fifth embodiment of the present invention, in which (a) is a cross-sectional view of the downstream tip portion cut along the axial center C, (b) is an oblique view of the downstream tip portion of (a), the hatched area with dashed lines indicates the portion where the porous member 3e is exposed, and (c) is a partial view showing another example of part B of (a). [Figure 8] FIG. 1 shows a gas injection pipe 1f according to a sixth embodiment of the present invention, in which (a) is a cross-sectional view of the downstream tip portion cut along the axial center C, and (b) is an oblique view of the downstream tip portion of (a), and the hatched area with dashed lines indicates the portion where the porous member 3f is exposed. [Figure 9]FIG. 11 shows a gas injection pipe 1g according to a seventh embodiment of the present invention, in which (a) is a cross-sectional view of the downstream tip portion cut along the axial center C, and (b) is an oblique view of the downstream tip portion of (a), and the hatched area with dashed lines indicates the portion where the porous member 3g is exposed. [Figure 10] 13 shows a gas injection pipe 1h according to an eighth embodiment of the present invention, in which (a) is a cross-sectional view of the downstream tip portion cut along the axial center C, and (b) is an oblique view of the downstream tip portion of (a), and the hatched area with dashed lines indicates the portion where the porous member 3h is exposed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] Hereinafter, a gas injection pipe 1 embodying the present invention will be described with reference to the drawings. The description of the embodiment of the invention and the drawings to which reference is made are used to explain technical features that may be adopted by the present invention. The present invention is not limited to these. The configurations shown in the drawings are merely illustrative examples and are not intended to limit the present invention.
[0022] <Contents and effects common to each embodiment> 1 to 3 as representative examples, a configuration common to each embodiment of the gas blowing pipe 1 according to the present invention will be described. As shown in FIG. 1, the gas blowing pipe 1 is immersed in the molten metal 61 in the molten metal container 60 and blows in the gas 8. As shown in FIG. 2, the side where the gas 8 is supplied in the flow direction of the gas 8 is the upstream side, and the side where the gas 8 is blown into the molten metal 61 is the downstream side. The gas blowing pipe 1 includes a cylindrical pipe member 2 having a first pipe end 25 on the downstream side and a second pipe end 26 on the upstream side, a porous member 3 formed inside the pipe member 2, a protective material 4 covering the outside of the pipe member 2, and a gas pipe 9 connected to the upstream side of the pipe member 2. The direction connecting the first pipe end 25 and the second pipe end 26 is the axial direction, and the direction perpendicular to the axial direction is the radial direction.
[0023] As shown in FIG. 2 etc., the porous member 3 has a step 33 in which at least a part of the porous material outer periphery 36 of the porous member 3 is recessed in the radial direction in a predetermined range from the downstream end toward the upstream side. The tube member 2 has a tube protrusion 23 formed at the tube first end 25, which has a predetermined thickness in the axial direction and protrudes radially inward from the tube wall portion 29 forming the tube outer periphery 20. The tube protrusion 23 covers at least a part of the downstream side of the step 33 in the porous member 3. At least a part of the porous member 3 protrudes downstream beyond the tube first end 25. The protective material 4 is formed to cover the tube outer periphery 20 and the tube first end 25 of the tube member 2, with at least a part of the porous material first end 34, which is the downstream end of the porous member 3, exposed downstream.
[0024] Next, the protective material 4 will be described. As an example of the protective material 4, castable refractory is used. Castable refractory is a powdered, unshaped refractory material to which water and a binder have been added, poured into a mold and hardened. As an example of a manufacturing method, a unit in which the parts of the gas injection pipe 1 excluding the protective material 4 are assembled is inserted into a mold, and the powdered, unshaped refractory material is poured into the mold and hardened after water and a binder have been added. As another example, a clay-like unshaped refractory material may be applied to the unit.
[0025] Next, the porous member 3 will be described. As an example, a shaped refractory material is used as the porous member 3. An example of the shaped refractory material is a brick formed by pressure molding.
[0026] In general, the hydrogen concentration in molten aluminum or copper can be reduced by injecting an inert gas such as argon gas or nitrogen gas into the molten metal. In addition, impurities such as oxides in the molten metal can be agglomerated by the gas bubbles and separated from the molten metal as slag, improving the performance of the metal. Conventionally, agitation-type devices that inject fine gas bubbles from the tip of a rotating blade rotating at high speed have been widely used for this degassing process, but these devices are prone to equipment trouble due to high speed rotation, and it is difficult to make the bubbles finer when the amount of gas is large.
[0027] The gas 8 injected from the gas injection pipe 1 into the molten metal 61 in the molten metal container 60 passes through the porous member 3, so that the bubbles can be made finer, improving the degassing performance. Since at least a part of the porous material first end 34 of the gas injection pipe 1 is exposed to the downstream side, the gas 8 made finer by the porous member 3 can be directly injected from the porous member 3 into the molten metal 61. The gas 8 causes impurities such as oxides in the molten metal 61 to coagulate with the bubbles of the gas 8, and can be separated as slag.
[0028] The molten metal 61 in the molten metal container 60 reaches a high temperature of, for example, about 1400 degrees. The gas injection tube 1 is exposed to the high-temperature molten metal 61, and if the tube member 2, for example, is exposed to the molten metal 61, there is a possibility that it may melt or be damaged. As illustrated in Fig. 2, the protective material 4 has a thickness t1 between the tube first end portion 25 and the protective material first end portion 41 of 10 mm or more, and a thickness t2 between the outer periphery of the protective material 4 and the tube outer periphery 20 of the tube member 2 of 10 mm or more.
[0029] The configuration of the gas blowing pipe 1 described above provides the following effects. On the downstream side where the porous member 3 is the tip, the step portion 33 of the gas blowing pipe 1 is covered by the pipe protruding portion 23. This reduces the likelihood of the porous member 3 falling off and being damaged by the pressure of the gas 8 when the gas 8 is blown in. Furthermore, since the protective material 4 is formed so as to cover the pipe first end portion 25, it is possible to reduce the likelihood of the pipe member 2 being melted or otherwise damaged by the heat of the molten metal 61. This further reduces the likelihood of the porous member 3 falling off and being damaged.
[0030] Next, the fall-off prevention part 7 that prevents the protective material 4 from falling off will be described. As shown in FIG. 2 and FIG. 3, the fall-off prevention part 7 of the protective material 4 is formed between the pipe outer circumference 20 of the pipe wall part 29 and the outer circumference of the protective material 4. The fall-off prevention part 7 can be configured in several ways. As shown in FIG. 2, the first example of the fall-off prevention part 7 is a lath net 7a formed to surround the pipe outer circumference 20. The downstream end of the lath net 7a is formed downstream of the first pipe end 25. Furthermore, the downstream end of the lath net 7a may be formed to the first protective material end 41, which is the downstream end of the protective material 4. The mesh shape and mesh size of the lath net 7a are selected according to the particle size of the material used for the protective material 4 and other conditions. Also, as shown in FIG. 2, the lath net 7a is embedded in an approximately midpoint between the pipe outer circumference 20 and the outer peripheral surface of the protective material 4 in the radial direction, for example. The lath net 7a is embedded so as not to be exposed to the outer peripheral surface of the protective material 4.
[0031] 3, a second example of the fall-off prevention part 7 is an uneven part 7b formed on the outer periphery 20 of the pipe. The shape of the uneven part 7b may be an uneven shape formed of peaks and valleys on the outer periphery 20 of the pipe, as in the example shown in FIG. 3(b). Alternatively, as shown in FIG. 3(c), an uneven shape formed of peaks and valleys may be formed on the outer periphery 20 of the pipe, with a flat surface formed on a part of the outer periphery 20 on the peak side and a flat surface formed on the recessed part on the valley side. Alternatively, the fall-off prevention part 7 of the second example may have another shape as long as an uneven shape is formed on the outer periphery 20 of the pipe.
[0032] The above-described configuration of the fall-off prevention part 7 has the following effects. Since the fall-off prevention part 7 is formed between the gas blowing tube 1's tube outer periphery 20 and the outer periphery of the protective material 4, the protective material 4 is less likely to fall off from the outer periphery of the tube member 2. Therefore, the protective material 4 can more reliably protect the tube member 2.
[0033] When the falling-off prevention portion 7 is the first example of lath net 7a, the lath net 7a is formed downstream of the first pipe end 25, which can further reduce the protective material 4 from falling off from the outer periphery of the pipe member 2. Furthermore, when the downstream end of the lath net 7a is formed up to the first protective material end 41, it is possible to reduce the protective material 4 from falling off further downstream than the first pipe end 25.
[0034] When the falling-off prevention portion 7 is the uneven portion 7b of the second example, the uneven portion 7b can be formed directly on the outer periphery 20 of the pipe of the pipe member 2. Therefore, there is no need to add a new part to prevent the protective material 4 from falling off, and costs can be reduced.
[0035] Next, the structure of the gas blowing pipe 1 will be described. As shown in FIG. 2 and other figures, the pipe member 2 of the gas blowing pipe 1 has a first pipe member 21 and a second pipe member 22. The inner diameter of the second pipe member 22 is smaller than the inner diameter of the first pipe member 21. The pipe protruding portion 23 is formed in the first pipe member 21, and the upstream pipe protruding portion inner surface 28 of the pipe protruding portion 23 and the porous member 3 are in contact with each other via a first seal material 51. The downstream end of the gas pipe 9 and the second porous member end 35 of the porous member 3 are in contact with each other via a second seal material 52 that sandwiches both sides of a washer 53. The first pipe member 21 and the second pipe member 22 are integrally joined. For example, the first pipe member 21 and the second pipe member 22 are welded at a welded portion 50. The gas pipe 9 is in a state of being fastened to the second pipe member 22. For example, the gas pipe 9 is fastened to the second pipe member 22 at a threaded portion 10.
[0036] The structure of the gas blowing pipe 1 described above has the following effects. The porous member 3 contacts the pipe protruding portion 23 of the first pipe member 21 on the downstream side via the first seal material 51, and contacts the gas pipe 9 on the upstream side via two second seal materials 52 that sandwich the washer 53, and further the gas pipe 9 is fastened to the second pipe member 22. Therefore, the airtightness between the first pipe member 21 and the porous member 3 and the gas pipe 9 is improved, and gas leakage from other than the porous member 3 can be reduced.
[0037] <<Description of contents and effects common to multiple embodiments>> <Positional Relationship Between Porous Material First End 34 and Protective Material First End 41 in the Axial Direction> Next, among the embodiments of the gas blowing pipe 1 according to the aspect of the present invention, the contents common to a plurality of embodiments will be described. First, the positional relationship between the first end 34 of the porous material and the first end 41 of the protective material in the axial direction will be described. In the examples shown in Figs. 1 to 5 and Figs. 8 to 10, the gas blowing pipe 1a of the first embodiment to the gas blowing pipe 1c of the third embodiment, and the gas blowing pipe 1f of the sixth embodiment to the gas blowing pipe 1h of the eighth embodiment have the following configurations. That is, in the gas blowing pipe 1, the first end 34 of the porous material is on the same plane as the first end 41 of the protective material, which is the downstream end of the protective material 4, or protrudes downstream from the first end 41 of the protective material. Other examples shown in Figs. 6 and 7 will be described later with the gas blowing pipe 1d of the fourth embodiment and the gas blowing pipe 1e of the fifth embodiment.
[0038] The above-described configuration has the following effects. The first porous end 34, which is the downstream end of the porous member 3, is flush with or protrudes downstream from the first protective end 41, which is the downstream end of the protective member 4. This makes it possible to reduce aggregation of the gas 8 blown in from the porous member 3.
[0039] <Relationship between the pipe protruding portion 23 and the step portion 33 and its effect> Next, a description will be given of the relationship between the pipe protruding portion 23 and the step portion 33. First, as a first example, as shown in Fig. 1 to Fig. 7, in the gas blowing pipe 1a of the first embodiment to the gas blowing pipe 1e of the fifth embodiment, the pipe protruding portion 23 covers the downstream side of the step portion 33 of the porous member 3 over the entire circumference in the circumferential direction.
[0040] According to the configuration of the first example described above, the pipe protruding portion 23 covers the step portion 33 of the porous member 3 around the entire circumferential direction, so that the pipe protruding portion 23 can support the porous member 3 evenly around the circumferential direction when the porous member 3 tries to pass through to the downstream side.
[0041] As a second example, as shown in Figures 8 to 10, from the gas injection pipe 1f of the sixth embodiment to the gas injection pipe 1h of the eighth embodiment, the pipe protrusion 23 covers the downstream side of the step portion 33 in the porous member 3 in part of the circumferential direction.
[0042] According to the configuration of the second example described above, the pipe protrusion 23 covers part of the step portion 33 of the porous member 3 in the circumferential direction, and is therefore able to support the porous member 3 when it attempts to slip through to the downstream side.
[0043] <<Description of contents and effects unique to each embodiment>> <Contents and Effects of the Gas Injection Pipe 1a of the First Embodiment> Next, the contents specific to each embodiment will be described. A gas injection pipe 1a of the first embodiment will be described with reference to FIG. 2. The porous member 3a is formed of a cylindrical small diameter portion 31 forming a step portion 33 and a cylindrical large diameter portion 32. The step portion 33 is formed over the entire circumference in the circumferential direction. The pipe member 2a is composed of a first pipe member 21a covering at least a part of the porous member 3a, and a second pipe member 22 connected to the first pipe member 21a and covering the gas pipe 9. The first pipe member 21a has a pipe protruding portion 23a formed over the entire circumference in the circumferential direction at the first pipe end portion 25, and a pipe opening portion 30 having an outer diameter smaller than the inner diameter of the pipe wall portion 29 is formed. The pipe protruding portion inner surface 28, which is the upstream surface of the pipe protruding portion 23a, contacts the downstream side of the step portion 33 in the porous member 3a over the entire circumference in the circumferential direction via a first seal material 51. As already explained, the gas blowing pipe 1a shown in FIG. 3 is another example in which the falling-off prevention portion 7 is formed by the uneven portion 7b.
[0044] According to the gas injection pipe 1a of the first embodiment described above, in addition to the effects common to each of the embodiments already described, the following effects are achieved. The inner surface 28 of the pipe protruding portion 23a contacts the downstream side of the step portion 33 of the porous member 3a via the first seal material 51 over the entire circumference in the circumferential direction. Therefore, the porous member 3a can be further reduced from falling off and being damaged by the pressure of the gas 8 when the gas 8 is injected. Since the protective material 4 covers the downstream side of the pipe protruding portion 23a over the entire circumference in the circumferential direction, it is possible to further reduce the melting damage of the pipe member 2a by the molten metal 61. Since the step portion 33 of the porous member 3a is covered by the pipe protruding portion 23a over the entire circumference in the circumferential direction, it is possible to reduce the leakage of the gas 8 from the step portion 33. Furthermore, since the porous material first end portion 34 and the protective material first end portion 41 are on the same plane, it is possible to reduce the aggregation when the gas 8 is injected.
[0045] <Contents and Effects of the Gas Injection Pipe 1b of the Second Embodiment> Next, a gas inlet pipe 1b of a second embodiment will be described with reference to Fig. 4. The gas inlet pipe 1b differs from the gas inlet pipe 1a in that the porous member 3b protrudes downstream from the first end 41 of the protective material. The first pipe member 21b of the pipe member 2b has the same configuration and shape as the first pipe member 21a of the pipe member 2a of the gas inlet pipe 1a, including the pipe protruding portion 23b. The porous member 3b protruding downstream from the first end 41 of the protective material has a cylindrical shape.
[0046] The gas blowing pipe 1b of the second embodiment described above has the following effects in addition to the effects of the gas blowing pipe 1a of the first embodiment already described. In the gas blowing pipe 1b, the porous member 3b protrudes downstream from the first protective member end 41. The surface area of the porous member 3b exposed to the molten metal 61 increases. Thus, the gas blowing pipe 1b can increase the amount of gas 8 blown in. Also, agglomeration of the gas 8 when blown in can be reduced.
[0047] <Contents and Effects of the Gas Injection Pipe 1c of the Third Embodiment> Next, a gas inlet pipe 1c of a third embodiment will be described with reference to Fig. 5. The gas inlet pipe 1c is different from the gas inlet pipe 1b in the shape of the porous material first end portion 34 of the porous member 3c. The first pipe member 21c of the pipe member 2c has the same configuration and shape as the first pipe member 21a of the gas inlet pipe 1a, including the pipe protruding portion 23c. The porous material first end portion 34 is formed with a porous material inclined portion 37 by chamfering the end portion over the entire circumference.
[0048] The gas blowing pipe 1c of the third embodiment described above has the following effect in addition to the effects of the gas blowing pipe 1b: The porous first end portion 34 of the gas blowing pipe 1c is chamfered to form a porous inclined portion 37 around the entire circumference, which reduces breakage of the porous member 3c during work, etc.
[0049] <Contents and Effects of the Gas Injection Pipe 1d of the Fourth Embodiment and the Gas Injection Pipe 1e of the Fifth Embodiment> Next, a gas injecting pipe 1d of a fourth embodiment and a gas injecting pipe 1e of a fifth embodiment will be described with reference to Figs. 6 and 7. The positional relationship between the porous material first end 34 and the protective material first end 41 in the axial direction will be described. In the gas injecting pipe 1d of the fourth embodiment and the gas injecting pipe 1e of the fifth embodiment, which are examples shown in Figs. 6 and 7, the porous material first end 34 is recessed upstream from the protective material first end 41, which is the downstream end of the protective material 4. The first pipe member 21d of the pipe member 2d and the first pipe member 21e of the pipe member 2e have the same configuration and shape as the first pipe member 21a of the gas injecting pipe 1a, including the pipe protruding portion 23d and the pipe protruding portion 23e.
[0050] Next, a gas inlet pipe 1d of a fourth embodiment will be described with reference to Fig. 6. The gas inlet pipe 1d differs from the gas inlet pipe 1a in that a porous member 3d is recessed upstream of a protective material first end 41. A recess 44 having approximately the same diameter as the outer diameter of the porous material first end 34 is formed in the protective material 4 at a position downstream of the porous material first end 34.
[0051] Next, a gas inlet pipe 1e of a fifth embodiment will be described with reference to Fig. 7. The gas inlet pipe 1e is different from the gas inlet pipe 1d in the shape of the protective material first end 41. In the gas inlet pipe 1e of the fifth embodiment, a protective material inclined portion 42 is formed so that the protective material 4 opens more widely on the side of the protective material first end 41 in the axial direction, and a truncated cone-shaped recess 45 is formed. The starting point of the protective material inclined portion 42 may be at the porous material first end 34 of the porous member 3e as shown in Fig. 7(a), or may be at the radially outer end of the straight portion 43 as shown in Fig. 7(c).
[0052] The gas blowing pipe 1d of the fourth embodiment and the gas blowing pipe 1e of the fifth embodiment described above have the following effects in addition to the effects common to each embodiment. Since the porous material first end 34 is recessed upstream of the protective material first end 41, it is possible to reduce the loss of the porous member 3. Furthermore, in the gas blowing pipe 1e of the fifth embodiment, a protective material inclined portion 42 is formed by the protective material 4 between the porous material first end 34 and the protective material first end 41 so that the downstream side is opened more widely. Therefore, the gas 8 blown from the porous member 3 is blown along the protective material inclined portion 42 of the protective material 4, so it is possible to reduce the aggregation of the gas 8.
[0053] <Contents and Effects of Gas Injection Pipe 1f of the Sixth Embodiment> Next, referring to FIG. 8, a gas inlet pipe 1f of a sixth embodiment will be described. The first pipe member 21f of the pipe member 2f in the gas inlet pipe 1f has a different shape of the first pipe end 25 from the gas inlet pipe 1a. The first pipe end 25 has a shape in which a part in the circumferential direction is cut toward the upstream side, and the pipe protruding portion 23f protrudes toward the downstream side. In the example shown in FIG. 8(b), the pipe protruding portion circumferential end 27 is formed so that the pipe protruding portion 23f is in a range of 180 degrees in the circumferential direction. A part of the downstream side of the step portion 33 of the porous member 3f contacts the pipe protruding portion inner surface 28 of the pipe protruding portion 23f via the first seal material 51, and the other part contacts the protective material 4. The pipe protruding portion 23f does not necessarily have to be semicircular, and can be formed in any range in the circumferential direction. Furthermore, the pipe protruding portion 23f may be formed independently at a plurality of positions in the circumferential direction.
[0054] The gas blowing pipe 1f of the sixth embodiment described above has the following effect in addition to the effects common to the previously described embodiments. The gas blowing pipe 1f has a pipe protruding portion 23f formed at a portion in the circumferential direction. In contrast, the porous member 3f can be easily manufactured, including the large diameter portion 32, since the small diameter portion 31 is formed in a cylindrical shape.
[0055] <Contents and Effects of the Gas Injection Pipe 1g of the Seventh Embodiment> Next, referring to FIG. 9, a gas inlet pipe 1g of a seventh embodiment will be described. The gas inlet pipe 1g is different from the gas inlet pipe 1f in the shape of the step 33 of the porous member 3g. The first pipe member 21g of the pipe member 2g has the same configuration and shape as the first pipe member 21f of the gas inlet pipe 1f. The step 33 of the porous member 3g is formed in the circumferential direction in a range where the pipe protruding portion 23g is formed, and is not formed in other parts. As shown in FIG. 9(b), the small diameter portion 31 of the porous member 3g has a small outer diameter in a part in the circumferential direction, and the other parts have the same outer diameter as the large diameter portion 32. The downstream side of the step 33 of the porous member 3g contacts the pipe protruding portion inner surface 28 of the pipe protruding portion 23g through the first seal material 51 in the entire region.
[0056] The gas blowing pipe 1g of the seventh embodiment described above has the following effect in addition to the effects common to the above-described embodiments. The gas blowing pipe 1g has the pipe protruding portion 23g formed in a part of the circumferential direction, and the small diameter portion 31 of the porous member 3g has a step portion 33 formed in accordance with the shape of the pipe protruding portion 23g. That is, in the region in the circumferential direction where the pipe protruding portion 23g is not formed, the outside diameter of the small diameter portion 31 is the same as the outside diameter of the large diameter portion 32, and continues to the first end portion 34 of the porous material. Therefore, when the gas 8 is supplied to the gas pipe 9, leakage of the gas 8 from the porous member 3g inside the gas blowing pipe 1g is reduced.
[0057] <Contents and Effects of the Gas Injection Pipe 1h of the Eighth Embodiment> Next, a gas blowing pipe 1h of an eighth embodiment will be described with reference to Fig. 10. The gas blowing pipe 1h is different from the gas blowing pipe 1g in that the porous member 3h protrudes downstream from the first end 41 of the protective material. The first pipe member 21h of the pipe member 2h, including the pipe protruding portion 23h, has the same configuration and shape as the first pipe member 21f of the gas blowing pipe 1f. As shown in Fig. 10(b), the small diameter portion 31 of the porous member 3h protruding downstream from the first end 41 of the protective material has a small outer diameter in a part of the circumferential direction and the same outer diameter as the large diameter portion 32 in the other part.
[0058] The gas blowing pipe 1h of the eighth embodiment described above has the following effects in addition to the effects of the gas blowing pipe 1g already described. In the gas blowing pipe 1h, the porous member 3h protrudes downstream from the first protective member end 41. The surface area of the porous member 3h exposed to the molten metal 61 increases. Thus, the gas blowing pipe 1h can increase the amount of gas 8 blown in. Also, agglomeration of the gas 8 when blown in can be reduced. [Explanation of symbols]
[0059] 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h Gas inlet tube 2, 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h pipe members 3, 3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h Porous member 4. Protective materials 7 Falling prevention part 7a Lath net 7b Uneven part 8. Gas 9 Gas Pipes 21, 21a, 21b, 21c, 21d, 21e, 21f, 21g, 21h First pipe member 22 Second tubular member 23, 23a, 23b, 23c, 23d, 23e, 23f, 23g, 23h Pipe protrusion 25 Pipe first end 26 Pipe second end 29 Pipe wall 33 Stepped section 34 Porous material first end 41 Protective material first end 42 Protective material slope part 51 First sealant 52 Second seal material 53 Washer 60 Molten metal container 61 Molten Metal
Claims
1. A gas injection pipe that is immersed in the molten metal in the molten metal container and injects gas into the molten metal, In the flow direction of the gas, the side where the gas is supplied is defined as the upstream side, and the side where the gas is injected into the molten metal is defined as the downstream side, a cylindrical tubular member having a first tubular end on the downstream side and a second tubular end on the upstream side; a porous member formed inside the tube member; A protective material for covering the outside of the pipe member; a gas pipe connected to the upstream side of the pipe member, A direction connecting the first end portion of the tube and the second end portion of the tube is defined as an axial direction, and a direction perpendicular to the axial direction is defined as a radial direction. The porous member has a step portion in which at least a part of an outer periphery of the porous member is recessed in the radial direction in a predetermined range from the downstream end toward the upstream side, The pipe member has a pipe protruding portion that has a predetermined thickness in the axial direction and protrudes radially inward from a pipe wall portion that forms an outer periphery at the first pipe end portion, the pipe protruding portion covers at least a portion of the downstream side of the step portion of the porous member, At least a portion of the porous member protrudes toward the downstream side beyond the first end of the pipe, The protective material is a gas injection pipe formed to cover the outer periphery of the pipe member and the first end of the pipe, with at least a portion of the first end of the porous material, which is the downstream end of the porous material, exposed to the downstream side.
2. The gas injection pipe according to claim 1 , wherein the first end of the porous material is flush with the first end of the protective material, which is the downstream end of the protective material, or protrudes downstream beyond the first end of the protective material.
3. 2. The gas injection pipe according to claim 1, wherein the first end of the porous material is recessed toward the upstream side relative to the first end of the protective material, which is a downstream end of the protective material.
4. 4. The gas inlet pipe according to claim 3, wherein the protective material has an inclined portion formed so that the first end side of the protective material is opened larger in the axial direction.
5. 2. The gas inlet pipe according to claim 1, wherein a portion for preventing the protective material from falling off is formed between an outer periphery of the pipe wall portion and an outer periphery of the protective material.
6. The fall-off prevention portion is a lath net formed to surround the outer periphery of the pipe, 6. The gas injection pipe according to claim 5, wherein the downstream end of the lath screen is formed downstream of the first end of the pipe.
7. 6. The gas injection pipe according to claim 5, wherein the fall-off prevention portion is an uneven portion formed on the outer periphery of the pipe.
8. The tubular member includes a first tubular member and a second tubular member, The inner diameter of the second tubular member is smaller than the inner diameter of the first tubular member, the tube projection is formed on the first tube member; the inner wall surface on the upstream side of the pipe protruding portion and the porous member are in contact with each other via a first sealant, the downstream end of the gas pipe and the porous member are in contact with each other via a second seal material that sandwiches both sides of a washer; the first pipe member and the second pipe member are integrally joined, 8. The gas inlet pipe according to claim 1, wherein the gas pipe is fastened to the second pipe member.
9. 9. The gas injection pipe according to claim 8, wherein the pipe protruding portion covers the downstream side of the step portion in the porous member over the entire circumferential direction.
10. 9. The gas injection pipe according to claim 8, wherein the pipe protruding portion covers a downstream side of the step portion of the porous member in a part in a circumferential direction.