Welding injection pipe

Abstract

A fusion welding injection pipe comprises a first pipe section and a second pipe section, the first pipe section and the second pipe section are provided with air cavity channels, the air cavity channels are arranged in the second direction, and the first pipe section and the second pipe section are connected in an inserted mode in the second direction, so that the first pipe section is partially located in the second pipe section or the second pipe section is partially located in the first pipe section. A certain angle is formed between the third direction and the second direction, a pin hole is formed in the inserting position of the first pipe section and the second pipe section and extends in the third direction, a part of the pin hole is formed in the first pipe section, the other part of the pin hole is formed in the second pipe section, and a locking pin is arranged in the pin hole. The locking pin is inserted into the pin hole to limit the first pipe section to move relative to the second pipe section in the second direction, and the locking pin, the first pipe section and the second pipe section are made of the same material so that the locking pin, the first pipe section and the second pipe section can be welded. The air cavity channel can be directly formed in the first pipe section in a tapping mode, so that the air cavity channel is not prone to cracking, and all parts of the fusion welding injection pipe are made of polycrystalline silicon and are convenient to machine.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor silicon material manufacturing, and in particular to a welding injection tube. Background Art

[0002] In the field of chemical vapor deposition (CVD) equipment for semiconductors, the injection tube is a key component in the thin film deposition furnace that passes special gases such as SiH4, NH3, and N2O into the reaction chamber. Injection tubes can be divided into non-welded injection tubes and fused injection tubes according to the way they are assembled. The advantages of fused injection tubes are that they are relatively simple to process and have a large gas flow rate. The disadvantages are that there are weld gaps in the tube body, there is a risk of cracking, and the cost is relatively high. The overall strength of a fused injection tube is generally composed of structural strength, material strength, and glue strength, among which glue strength plays a dominant role. In actual use of fused injection tubes, a layer of deposited silicon will grow at the weld seam on the tube body. Due to the internal stress difference between the deposited silicon layer and the native silicon, as the thickness of the silicon deposited layer increases, the injection tube breaks at the weld seam on the tube body. The existing glue strength can only delay the fracture trend, but cannot prevent it. Non-welded jet tubes, also known as integrated jet tubes, offer advantages such as integrated small-hole machining, the absence of weld gaps, and reliable strength without tube fracture caused by silicon deposition. However, their disadvantages are the difficulty of machining small holes, low gas flow rates, and high cost. However, CVD equipment typically requires jet tubes with high airflow and resistance to breakage. Existing technical solutions include using welded jet tubes to increase airflow and maximize weld strength through structural design, weld surface roughness, and the development of new adhesives, thereby delaying or even preventing tube fracture. There are some problems and limitations in the manufacture or use of welding nozzle tubes. First, after the weld glue on the tube body solidifies, it will cause the weld gap to become larger, and the deposited silicon will grow in these larger gaps and cause the tube body to crack. Secondly, there is little knowledge in the application field of silicon materials, and there is a lack of practical experience in the use of nozzle tube materials. For example, it is impossible to determine the strength difference between single-crystal silicon materials and polycrystalline silicon materials. In addition, the structure of the welding nozzle tube is complex, and the welding part usually has a small area of thin-walled features. In summary, the existing technology has some problems and limitations in improving the strength of welding nozzle tubes.

[0003] Chinese patent announcement number "CN213507187U" discloses a fusion-type injection tube, which aims to solve the problem that the current silicon crystal used as an injection tube is prone to deviation when drilling long holes, and the verticality and parallelism of the holes cannot be guaranteed. The utility model includes a male component and a female component. The male component and the female component are provided with slots along the length direction. The male component and the female component are fitted together, and the slots are combined to form a vent. The side of the male component facing the female component is provided with a protruding boss, and the female component is provided with a concave groove. The boss is adapted to the groove, and the slot on the male component is provided on the boss. The injection tube is composed of welded components, and the hole in the tube is formed by grooving the components and then combining them. Therefore, it can avoid the problem that the whole piece of material cannot be drilled over a long distance when the processing hole diameter is small. However, it adopts a design of half male and female components, which is prone to cracking after long-term use. Summary of the Invention

[0004] The present application provides a welding injection pipe to at least solve the technical problem of easy cracking in the prior art.

[0005] According to the present application, a welding injection pipe is provided, including a first pipe section and a second pipe section, the first pipe section and the second pipe section are provided with an air cavity channel, the air cavity channel is arranged along the second direction, the first pipe section and the second pipe section are plugged in along the second direction, so that the first pipe section is partially located in the second pipe section or the second pipe section is partially located in the first pipe section, the third direction forms a certain angle with the second direction, a pin hole is provided at the plug-in position of the first pipe section and the second pipe section, the pin hole extends along the third direction, a part of the pin hole is formed in the first pipe section and the other part is formed in the second pipe section, a locking pin is provided in the pin hole, and the locking pin is inserted into the pin hole to limit the relative movement of the first pipe section relative to the second pipe section along the second direction, the locking pin, the first pipe section and the second pipe section are made of the same material so that the locking pin, the first pipe section and the second pipe section can be welded.

[0006] Compared with the prior art, the welding injection pipe of the present application has the following beneficial effects: The air cavity can be formed directly by opening a hole in the first pipe section, so that the air cavity is not easy to crack. The locking pin can prevent the first pipe section from moving relative to the second pipe section along the second direction. The locking pin, the first pipe section and the second pipe section can be welded to form an integrated structure. The welding can be achieved using welding materials, glue or silicon melt bonding. It needs to be heated to 1100°C to complete the welding. The entire welding injection pipe is made of high-temperature resistant polysilicon material, which is convenient for processing and chamfering.

[0007] In one embodiment, the first tube section is provided with a stepped hole at the opening of the air cavity. The stepped hole includes a first stepped section and a second stepped section, the first stepped section having a smaller diameter than the second stepped section. The second tube section is provided with a stepped tube at the location where it connects to the first tube section. The stepped tube includes a first stepped tube and a second stepped tube. The outer diameter of the first stepped tube is smaller than the outer diameter of the second stepped tube. The outer diameter of the first stepped tube is smaller than the inner diameter of the first stepped hole, resulting in a certain gap between the first stepped tube and the first stepped hole. The outer diameter of the second stepped tube is the same as the inner diameter of the second stepped hole. This provides the first stepped tube with a larger deformation space, and the gap provides space for the silicon deposited layer to grow, so that the silicon deposited layer has a larger radial growth space. The stepped hole also increases the welding area and improves the welding strength.

[0008] In one embodiment, a sleeve is provided outside the first stepped tube. The sleeve's outer diameter is equal to the inner diameter of the first stepped hole. The sleeve's length in the second direction is less than the first stepped hole's depth in the second direction, so that a certain axial clearance exists between the sleeve and the first stepped tube after the sleeve is inserted into the first stepped hole. This provides increased support for the first stepped tube, making it less susceptible to rupture. The sleeve's design allows for radial deformation of the first stepped tube, and the support provided by the sleeve allows for controlled deformation.

[0009] In one embodiment, the first pipe section is provided with a first air cavity channel, a second air cavity channel and a third air cavity channel, and the first air cavity channel, the second air cavity channel and the third air cavity channel are arranged along a first direction, which can increase the gas flow speed and the gas flow rate.

[0010] In one embodiment, the second pipe segment is plugged into the third pipe segment, an air inlet pipe is provided at the second end of the third pipe segment, and a conical cavity is provided at the first end of the third pipe segment. The cross-section of the conical cavity close to the second end is smaller than the cross-section away from the second end, so that a single pipeline can be divided into multiple air cavities.

[0011] In one embodiment, a guide pin is provided in the conical cavity, and the guide pin is located at the center of the conical cavity. The first section of the guide pin contacts the second pipe section, and the second section of the guide pin contacts the third pipe section, so that the guide pin can limit the movement of the second pipe section relative to the third pipe section along the second direction. The guide pin can play a guiding role to avoid large airflow in the central air cavity, and can also serve as a locking pin to realize the locking function of the second pipe section and the third pipe section.

[0012] In one embodiment, the cross-section of the guide pin is an isosceles triangle, the vertex of the isosceles triangle is close to the second end, and the third pipe segment is provided with a through hole matching the guide pin, so that the guide pin can be inserted into the through hole to limit the third pipe segment.

[0013] In one embodiment, the second pipe section is provided with a dovetail groove so that the bottom corner of the guide pin can be inserted into the dovetail groove, thereby limiting the position of the second pipe section in the second direction.

[0014] In one embodiment, the first pipe section is provided with a plurality of air holes, some of which are arranged along the third direction, and the other part of the air holes are at a certain angle to the third direction, so that the spraying is more uniform and the spraying range is larger.

[0015] In one embodiment, the first tube segment is formed by plugging together multiple small tube segments. The air cavities of the small tube segments are processed from both ends to the center and pass through the center area. This can reduce the length of a single air cavity and increase the accuracy of the opening positions at both ends.

[0016] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the exemplary embodiments of the present application will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present application are shown in an illustrative and non-limiting manner, in which: In the drawings, the same or corresponding reference numerals denote the same or corresponding parts.

[0018] Figure 1 A schematic diagram of the assembly state of the welding injection pipe in Example 1 of the present application is shown; Figure 2 An explosion diagram of the welding injection pipe in Example 1 of the present application is shown; Figure 3 A half-section schematic diagram perpendicular to the third direction of the welding injection pipe of Example 1 of the present application is shown; Figure 4 Shown Figure 3 A in the middle is an enlarged schematic diagram; Figure 5 A half-section schematic diagram perpendicular to the first direction of the welding injection pipe of Example 5 of the present application is shown; Figure 6 Shown Figure 5 The enlarged schematic diagram of point B in the middle; Figure 7 A half-section schematic diagram perpendicular to the third direction of the welding injection pipe of Example 2 of the present application is shown; Figure 8 Shown Figure 7 Enlarged schematic diagram at point C in the middle; Figure 9 A partial schematic diagram of the welding injection pipe of Example 3 of the present application is shown; Figure 10 A partial cross-sectional schematic diagram of the welding injection pipe of Example 3 of the present application is shown; Figure 11A partial schematic diagram of the assembled state of the welding injection pipe of Example 6 of the present application is shown; Figure 12 A partial explosion diagram of the welding injection pipe of Example 6 of the present application is shown; Figure 13 A schematic diagram of the relative positions of the guide pin and the cylindrical pin of the welding injection pipe in Example 6 of the present application is shown.

[0019] Description of the numbers in the figure: X, first direction; Y, second direction; Z, third direction; 1. First pipe section; 2. Second pipe section; 3. Third pipe section; 4. Air channel; 5. Pin hole; 6. Locking pin; 7. Blocking bolt; 8. Guide pin; 9. Cylindrical pin; 10. Air hole; 11. Bottom surface; 12. Side surface; 13. Transition surface; 14. Small pipe section; 15. Stepped pipe; 16. First stepped pipe; 17. Second stepped pipe; 18. Sleeve; 19. End surface; 20. Dovetail groove; 21. First conical cavity; 22. Second conical cavity; 23. Third conical cavity; 24. Second pin hole ; 25. Waist groove hole; 31. Air intake pipe; 32. Conical cavity; 33. First end; 34. Second end; 35. Third pin hole; 36. Triangular pin hole; 41. First air cavity channel; 42. Second air cavity channel; 43. Third air cavity channel; 44. Step hole; 45. First step section; 46. Second step section; 51. Semicircular pin groove; 81. First section; 82. Second section; 83. Inner recess; 84. Waist groove; 91. Flat pin; 92. Second pin; 93. Third pin. DETAILED DESCRIPTION

[0020] In order to make the purpose, features, and advantages of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0021] Example 1: like Figure 1 and Figure 2As shown, a welding jet pipe includes a first pipe section 1 and a second pipe section 2. The first pipe section 1 and the second pipe section 2 are provided with an air cavity 4. The air cavity 4 is a channel for airflow arranged along a second direction. The air cavity 4 can be designed into a cylindrical, conical, quadrangular pyramidal, or other commonly used channel shapes according to different location requirements. A smooth design is used as much as possible to reduce air resistance. The first pipe section 1 and the second pipe section 2 are plugged together along the second direction, so that the first pipe section 1 is partially located within the second pipe section 2 or the second pipe section 2 is partially located within the first pipe section 1. The third direction is at a certain angle to the second direction. A pin hole 5 is provided at the plug-in position of the first pipe section 1 and the second pipe section 2. The pin hole 5 extends along the third direction. The pin hole 5 is partially formed in the first pipe section 1 and the other part is formed in the second pipe section 2. A locking pin 6 is provided in the pin hole 5. When inserted into the pin hole 5, the locking pin 6 can limit the relative movement of the first pipe section 1 relative to the second pipe section 2 in the second direction. The locking pin 6, the first pipe section 1, and the second pipe section 2 are made of the same material, so that the locking pin 6, the first pipe section 1, and the second pipe section 2 can be welded. The first, second, and third directions are perpendicular to each other. In this embodiment, two pin holes 5 are provided in the first pipe segment 1. To prevent the pin holes 5 from penetrating the air passage 4, a semicircular pin groove 51 is provided in the second pipe segment 2. This restricts relative movement of the first pipe segment 1 relative to the second pipe segment 2 in the second direction. The pin holes 5 are machined after the first and second pipe segments 1 and 2 are assembled, making machining convenient and highly precise.

[0022] like Figure 2 and Figure 3 As shown, a blocking bolt 7 is provided at the end of the air cavity channel 4, and the blocking bolt 7 is fixed to the air cavity channel 4 by a threaded connection.

[0023] like Figure 2 and Figure 4 As shown, in one embodiment, the first pipe section 1 is provided with a stepped hole 44 at the opening of the air cavity 4. The stepped hole 44 includes a first stepped section 45 and a second stepped section 46. The first stepped section 45 has a smaller diameter than the second stepped section 46. The second pipe section 2 is provided with a stepped tube 15 at the connection position with the first pipe section 1. The stepped tube 15 includes a first stepped tube 16 and a second stepped tube 17. The outer diameter of the first stepped tube 16 is smaller than the outer diameter of the second stepped tube 17. The outer diameter of the first stepped tube 16 is smaller than the inner diameter of the first stepped hole 44, so that a certain gap exists between the first stepped tube 16 and the first stepped hole 44. The outer diameter of the second stepped tube 17 is the same as the inner diameter of the second stepped hole 44. In some embodiments, a third stepped hole 44 and a third stepped tube 15 can be provided as needed to further improve the sealing and stability of the connection and prevent the stepped tube 15 from rupturing or leaking.

[0024] like Figure 2 and Figure 4As shown, in one embodiment, a sleeve 18 is provided outside the first stepped tube 16. The outer diameter of the sleeve 18 is equal to the inner diameter of the first stepped hole 44. The length of the sleeve 18 in the second direction is less than the depth of the first stepped hole 44 in the second direction, so that a certain axial gap exists after the sleeve 18 is inserted into the first stepped hole 44 following the first stepped tube 16. The end surface 19 of the first stepped tube 16 can be designed to be tapered, which facilitates the growth of deposited silicon and prevents the tube from rupturing due to the growth of deposited silicon.

[0025] like Figure 2 and Figure 4 As shown, in one embodiment, the first tube section 1 is provided with a first air cavity channel 41 , a second air cavity channel 42 and a third air cavity channel 43 , and the first air cavity channel 41 , the second air cavity channel 42 and the third air cavity channel 43 are arranged along a first direction.

[0026] like Figure 3 and Figure 4 As shown, in one embodiment, the second pipe section 2 is plugged into the third pipe section 3. The second end 34 of the third pipe section 3 is provided with an air inlet pipe 31, and the first end 33 of the third pipe section 3 is provided with a tapered cavity 32. The cross-section of the tapered cavity 32 near the second end 34 is smaller than the cross-section away from the second end 34. The first tapered cavity 21, the second tapered cavity 22, and the third tapered cavity 23 are provided at the entrances of the first air channel 41, the second air channel 42, and the third air channel 43 of the second pipe section 2, respectively. The first tapered cavity 21, the second tapered cavity 22, and the third tapered cavity 23 guide the airflow to the first air channel 41, the second air channel 42, and the third air channel 43, respectively.

[0027] Example 2: like Figure 7 and Figure 8 As shown, in one embodiment, the first pipe segment 1 is formed by plugging together a plurality of small pipe segments 14. The air cavity 4 of the small pipe segment 14 is processed from both ends to the center and passes through the center area. In order to ensure a smooth transition of the inner wall, the intersection position can be polished. The length of the small pipe segment 14 is determined according to the size of the processing hole and the accuracy of the processing equipment. The position deviation of the processing holes at both ends does not exceed 2 mm. A pin hole 5 is provided at the plug-in position. The pin hole 5 extends along the third direction. A locking pin 6 is provided in the pin hole 5. The locking pin 6 is inserted into the pin hole 5 to limit the relative movement of adjacent small pipe segments 14 along the second direction. Figure 8 As shown, the guide pin 8 has a diamond-shaped cross section, and the second pipe section 2 extends toward the second end 34 of the third pipe section 3 and exceeds the center of the guide pin 8 , so that the guide pin 8 can be restricted from moving in the second direction after the second pipe section 2 is grooved.

[0028] Example 3: like Figure 9 and Figure 10As shown, in one embodiment, the cross section of the guide pin 8 is an isosceles triangle, and the vertex of the isosceles triangle is close to the second end 34. The second pipe section 2 is provided with a dovetail groove 20 so that the bottom corner of the guide pin 8 can be inserted into the dovetail groove 20. Figure 10 As shown, the guide pin 8 is provided with an arc-shaped inner concave portion 83 along the second direction. Compared to the embodiment of Example 3, while reducing the overall flow resistance, the air flow rate of the second air channel 42 can be reduced, and the flow rates of the first air channel 41 and the third air channel 43 can be increased. This advantage can be applied in Example 4, that is, more air holes 10 are provided in the first air channel 41 and the third air channel 43. Under the premise of requiring a higher air flow rate, it is necessary to increase the flow rates of the first air channel 41 and the third air channel 43 while minimizing the flow resistance.

[0029] Example 4: like Figure 2 As shown, the first pipe section 1 is provided with a plurality of air holes 10 , a portion of the air holes 10 is arranged along the third direction, and another portion of the air holes 10 forms a certain angle with the third direction.

[0030] like Figure 2 As shown, part of the air holes 10 of the first air cavity channel 41 and the third air cavity channel 43 are arranged on the bottom surface 11, and the other part is arranged on the transition surface 13. The transition surface 13 is located between the bottom surface 11 and the side surface 12. The bottom surface 11 and the side surface 12 are perpendicular. The transition surface 13 can be a curved surface. The transition surface 13 can be processed into an inclined surface first, and then processed into a curved surface after the air holes 10 are processed.

[0031] Example 5: like Figure 2 、 Figure 5 and Figure 6 As shown, in one embodiment, a guide pin 8 is provided in the conical cavity 32, and the guide pin 8 is located at the center of the conical cavity 32. The first section 81 of the guide pin 8 contacts the second pipe section 2, and the second section 82 of the guide pin 8 contacts the third pipe section 3, so that the guide pin 8 can limit the movement of the second pipe section 2 relative to the third pipe section 3 in the second direction. The specific positions of the first section 81 and the second section 82 can be set according to the positions of the second pipe section 2 and the third pipe section 3. In the figure, a portion of the second pipe section 2 is covered outside the third pipe section 3, so the first section 81 is closer to the outer end than the second section 82. The second pipe section 2 is provided with a triangular pin hole 36, and the third pipe section 3 is provided with a triangular pin hole 36. The guide pin 8 passes through the triangular pin hole 36 of the second pipe section 2 and the triangular pin hole 36 of the third pipe section 3 to fix the second pipe section 2 and the third pipe section 3 together.

[0032] Example 6: like Figure 11 and Figure 12As shown, the third pipe section 3 and the second pipe section 2 have an insertion area so that the third pipe section 3 is surrounded by the second pipe section 2 or the second pipe section 2 is surrounded by the third pipe section 3. A flat column pin 91 is provided at one end of the guide pin 8. The guide pin 8 is provided with a waist groove 84 to match the flat column pin 91. A second pin hole 24 and a waist groove hole 25 are provided on both sides of the second pipe section 2. The waist groove hole 25 matches the flat column pin 91. The third pipe section 3 is provided with a third pin hole 35. The third pin hole 35 is in a corresponding matching position with the second pin hole 24. The cylindrical pin 9 is provided with a second pin column 92 and a third pin column 93. The second pin hole 24 matches the second pin column 92, and the third pin hole 35 matches the third pin column 93. Figure 11 and Figure 13 As shown, the guide pin 8 can be first fixed to the second pipe section 2 through the flat cylindrical pin 91, and then the third pipe section 3 and the second pipe section 2 can be fixed together through the cylindrical pin 9.

[0033] All components in the above embodiments are made of polysilicon and are finally welded at 1100° C. to form an integrated structure, which is convenient for manufacturing and assembly.

[0034] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this application can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of this application can be achieved. This is not limited herein.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0036] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A welding injection pipe, characterized in that: The invention comprises a first pipe section (1) and a second pipe section (2), wherein the first pipe section (1) and the second pipe section (2) are provided with an air cavity (4), wherein the air cavity (4) is arranged along a second direction, and the first pipe section (1) and the second pipe section (2) are plugged together along the second direction so that the first pipe section (1) is partially located in the second pipe section (2) or the second pipe section (2) is partially located in the first pipe section (1), and the third direction forms a certain angle with the second direction, and a pin hole (5) is provided at the plugging position of the first pipe section (1) and the second pipe section (2), and the pin hole (5) ) is extended along a third direction, a portion of the pin hole (5) is formed in the first pipe section (1) and another portion is formed in the second pipe section (2), a locking pin (6) is provided in the pin hole (5), and the locking pin (6) inserted into the pin hole (5) can limit the relative movement of the first pipe section (1) relative to the second pipe section (2) along the second direction, and the locking pin (6), the first pipe section (1) and the second pipe section (2) are made of the same material so that the locking pin (6), the first pipe section (1) and the second pipe section (2) can be welded.

2. The welding injection pipe according to claim 1, characterized in that: The first pipe section (1) is provided with a stepped hole (44) at the opening of the air cavity channel (4), the stepped hole (44) includes a first stepped section (45) and a second stepped section (46), the diameter of the first stepped section (45) is smaller than that of the second stepped section (46), the second pipe section (2) is provided with a stepped tube (15) at the plugging position with the first pipe section (1), the stepped tube (15) includes a first stepped tube (16) and a second stepped tube (17), the outer diameter of the first stepped tube (16) is smaller than that of the second stepped tube (17), the outer diameter of the first stepped tube (16) is smaller than that of the second stepped tube (17), and the outer diameter of the first stepped tube (16) is smaller than that of the inner diameter of the first stepped hole (44), so that a certain gap exists between the first stepped tube (16) and the first stepped hole (44), and the outer diameter of the second stepped tube (17) is the same as the inner diameter of the second stepped hole (44).

3. The welding injection pipe according to claim 2, characterized in that: A sleeve (18) is provided outside the first stepped tube (16), the outer diameter of the sleeve (18) being equal to the inner diameter of the first stepped hole (44), and the length of the sleeve (18) in the second direction being less than the depth of the first stepped hole (44) in the second direction, so that a certain gap exists axially after the sleeve (18) follows the first stepped tube (16) and is inserted into the first stepped hole (44).

4. The welding injection pipe according to any one of claims 1 to 3, characterized in that: The first tube section (1) is provided with a first air cavity channel (41), a second air cavity channel (42) and a third air cavity channel (43), and the first air cavity channel (41), the second air cavity channel (42) and the third air cavity channel (43) are arranged along a first direction.

5. The welding injection pipe according to claim 4, characterized in that: The second pipe section (2) is plugged into the third pipe section (3); the second end (34) of the third pipe section (3) is provided with an air inlet pipe (31); the first end (33) of the third pipe section (3) is provided with the tapered cavity (32); the cross section of the tapered cavity (32) close to the second end (34) is smaller than the cross section away from the second end (34).

6. The welding injection pipe according to claim 5, characterized in that: A guide pin (8) is provided in the conical cavity (32), and the guide pin (8) is located at the center of the conical cavity (32). The first section (81) of the guide pin (8) contacts the second pipe section (2), and the second section (82) of the guide pin (8) contacts the third pipe section (3), so that the guide pin (8) can limit the second pipe section (2) from moving relative to the third pipe section (3) along the second direction.

7. The welding injection pipe according to claim 6, characterized in that: The guide pin (8) has a cross-section in the form of an isosceles triangle, the vertex of the isosceles triangle is close to the second end (34), and the third pipe section (3) is provided with a through hole matching the guide pin (8).

8. The welding injection pipe according to claim 7, characterized in that: The second pipe section (2) is provided with a dovetail groove (20), so that the bottom corner of the guide pin (8) can be inserted into the dovetail groove (20).

9. The welding injection pipe according to claim 8, characterized in that: The first pipe section (1) is provided with a plurality of air holes (10), a portion of the air holes (10) are arranged along a third direction, and another portion of the air holes (10) form a certain angle with the third direction.

10. The welding injection pipe according to claim 9, characterized in that: The first pipe section (1) is formed by splicing together a plurality of small pipe sections (14), and the air cavity (4) of the small pipe section (14) is processed from both ends toward the center and is connected in the center area.

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