A bent pipe welding device and a welding method

Abstract

The present application provides an elbow welding device and a welding method, which relate to the field of elbow welding for refrigeration systems. It includes a welding platform and a fixture, a welding tool, a gas supply mechanism, and an electrode conveying mechanism arranged on the welding platform; the fixture is used for clamping the elbow to be welded; a pair of the welding tools are respectively arranged on both sides of the elbow, the welding tool includes a turntable and a plurality of welding nozzles, and the plurality of welding nozzles are arranged in a circular pattern on the turntable, and a servo motor drives the turntable to rotate, and the plurality of welding nozzles are sequentially rotated to the position pointing to the welding part; the gas supply mechanism supplies gas to the welding nozzle pointing to the welding part; the electrode conveying mechanism conveys the electrode to the welding part. The present application has the effect of reducing the working time of a single welding nozzle, preventing the welding nozzle from burning out, and improving the welding efficiency by means of the rotation and position change of the welding nozzle.

Description

Technical Field

[0001] This application relates to the field of bent pipe welding for refrigeration systems, and particularly to a bent pipe welding device and a welding method. Background Art

[0002] There are many copper bent pipes in the refrigeration system of air conditioners. Multiple bent pipes need to be welded to form a pipeline for refrigerant flow. Due to the pressure inside the pipeline, in order to prevent refrigerant leakage and ensure the refrigeration effect, the welded bent pipes need to have high strength and airtightness, which poses high requirements for the welding work of bent pipes.

[0003] Currently, flame brazing is generally used for welding bent pipes. Flame brazing heats the bent pipe and the welding rod through a flame. After the welding rod melts into a liquid state, it fills the gap between the joint surfaces of the two bent pipes through capillary action, and reaches a connection state with strong firmness and good airtightness after cooling. In the actual production process, in order to improve the continuity of the process, the welding torch will be in a long-term working state, and there is a possibility that the welding tip will burn out. In order to prevent the welding tip from burning out, it is necessary to use multiple welding torches alternately to achieve the overall cooling of the welding torch.

[0004] However, when the cooled welding torch is used again, it needs to be manually ignited again after the bent pipe to be welded is fixed, and the continuity is poor, which reduces the working efficiency of bent pipe welding. Summary of the Invention

[0005] In order to improve the problems of poor continuity and low efficiency of welding operations caused by the alternating use of multiple welding torches, this application provides a bent pipe welding device and a welding method.

[0006] In a first aspect, this application provides a bent pipe welding device, adopting the following technical solutions:

[0007] A bent pipe welding device includes a welding platform and a fixture, a welding tool, a gas supply mechanism, and a welding rod conveying mechanism arranged on the welding platform;

[0008] The fixture is used for clamping the bent pipe to be welded;

[0009] A pair of the welding tools are respectively arranged on both sides of the bent pipe. The welding tool includes a turntable and a plurality of welding tips. The plurality of welding tips are arranged in a circular pattern on the turntable, and a servo motor drives the turntable to rotate, and the plurality of welding tips sequentially rotate to the position pointing to the welding part;

[0010] The gas supply mechanism supplies gas to the welding tip pointing to the welding part;

[0011] The welding rod conveying mechanism conveys the welding rod to the welding part.

[0012] By adopting the above technical solution, under the driving action of the servo motor, among the multiple welding nozzles of any turntable, only one points to the part to be welded. By arranging welding nozzles on both sides of the part to be welded, the left and right sides of the part to be welded are heated by the flames ejected from the welding nozzles, with high uniformity. After the part to be welded is heated, the electrode conveying mechanism conveys the electrode to a position where it contacts the unflared elbow and the contact position is 2-3 mm away from the pipe orifice of the flared elbow. At the same time, the electrode is continuously fed into the upper side of the part to be welded at an obliquely downward angle, avoiding direct heating of the electrode by the flame, forming welding beads and splashing everywhere, and also facilitating the flow and spreading of the molten welding liquid after the electrode melts; after one welding is completed, the servo motor on one side drives the corresponding turntable to rotate, so that the welding nozzle pointing to the part to be welded changes, and the welding nozzle pointing to the part to be welded on the other side remains unchanged. In this way, after the air supply mechanism on one side supplies air to the welding nozzle that points to the part to be welded after rotation, the welding nozzle that is still in the flame spraying state on the other side can perform the ignition operation on the welding nozzle on one side. Then, the new elbow to be welded is fixed on the fixture, and the two welding nozzles on both sides can enter the flame spraying and heating state again to complete the welding operation; after the second welding is completed, the servo motor on the other side drives the corresponding turntable to rotate, so that the welding nozzle pointing to the part to be welded changes, and the welding nozzle pointing to the part to be welded on one side remains unchanged. In this way, after the air supply mechanism on the other side supplies air to the welding nozzle that points to the part to be welded after rotation, the welding nozzle that is still in the flame spraying state on one side can perform the ignition operation on the welding nozzle on the other side. Then, the new elbow to be welded is fixed on the fixture, and the two welding nozzles on both sides can enter the flame spraying and heating state for the third time to complete the welding operation; that is to say, under the driving action of the servo motor, each time a welding nozzle in a cooling state rotates to the position pointing to the part to be welded and sprays fire, while ensuring the continuity of welding, the continuous working time of a single welding nozzle is effectively reduced, preventing the welding nozzle from being burned out. Moreover, the conversion of different welding nozzles and the re-ignition after conversion are all automatically completed, with high continuity and safety of operation, effectively improving the work efficiency; an automatic ignition device can also be set on the welding nozzle to prevent the distance between the two welding nozzles from being too large when welding an elbow with a larger diameter, so that the flame ejected from one welding nozzle cannot perform the ignition operation on the other welding nozzle.

[0013] Preferably, the welding tool and the air supply mechanism are both provided on a support plate, and the support plate is driven by a first screw rod transmission mechanism to reciprocate axially along the part to be welded.

[0014] By adopting the above technical solution, during the process of heating the part to be welded, when the first lead screw drive mechanism drives the pallet to reciprocate with a small displacement, the heating uniformity of the two welding nozzles on the part to be welded can be improved, the welding fluid can be promoted to fully penetrate, and the penetration depth meets the standard; after the part to be welded is heated and welded, when the first lead screw drive mechanism drives the pallet to move with a large displacement, the turntable can be driven away from the part to be welded, which is convenient for taking out the welded bent pipe, putting in the bent pipe to be welded and replacing the welding nozzles, can increase the operating space, prevent the flame of the welding nozzle from burning personnel during the taking and placing of the bent pipe, and improve the safety of the operation.

[0015] Preferably, a first bracket is provided on the pallet, the servo motor is fixedly arranged on the first bracket, and the output shaft of the servo motor is connected to the turntable and drives the turntable to rotate.

[0016] By adopting the above technical solution, through the setting of the first bracket, it plays a role in fixing the servo motor and the turntable, ensuring that the servo motor can reliably drive the turntable.

[0017] Preferably, the gas supply mechanism includes a second bracket, and the second bracket is driven by a second lead screw drive mechanism to reciprocate radially along the part to be welded;

[0018] A mixed gas input pipe and an oxygen input pipe are provided on the second bracket. The mixed gas input pipe supplies gas to one welding nozzle pointing to the part to be welded, and the oxygen input pipe supplies gas to the other welding nozzle facing the part to be welded after rotation.

[0019] By adopting the above technical solution, the mixed gas input pipe inputs the mixed gas of acetylene and oxygen to the welding nozzle pointing to the part to be welded, ensuring that the flame ejected from the welding nozzle has enough temperature to heat the bent pipe. The oxygen input pipe continuously inputs oxygen to the welding nozzle waiting to turn to point to the part to be welded in a small flow rate to prevent air from mixing into the welding nozzle and directly igniting to cause a gunshot or backfire explosion, omitting the air evacuation process and reducing the consumption of acetylene gas; at the same time, under the action of the second lead screw drive mechanism, the mixed gas input pipe and the oxygen input pipe can be separated from the welding nozzle, which is convenient for the rotation of the turntable and the replacement of the welding nozzle entering the position pointing to the part to be welded. At the same time, after the welding nozzle replacement is completed, the first lead screw drive mechanism can insert the mixed gas input pipe and the oxygen input pipe into the corresponding welding nozzle again.

[0020] Preferably, a pair of fixing rings are further provided on the second bracket. The mixed gas input pipe and the oxygen input pipe respectively pass through a pair of fixing rings in a one-to-one correspondence. A sealing ring is provided on the side of the fixing ring facing the welding nozzle, and the sealing ring seals the gap between the end face of the fixing ring and the end face of the welding nozzle.

[0021] By adopting the above technical solution, under the action of the second lead screw transmission mechanism, the mixed gas input pipe and the oxygen input pipe can smoothly and accurately disengage from or insert into the welding nozzle. After the insertion is completed, the fixing ring approaches the welding nozzle, and the sealing ring is pressed by the fixing ring and the welding nozzle, so that the sealing function can be reliably performed to prevent the mixed gas or oxygen from leaking from the corresponding nozzle.

[0022] Preferably, there is an angle of 40°-45° between the welding electrode and the part to be welded and between the welding nozzle pointing to the part to be welded and the part to be welded.

[0023] By adopting the above technical solution, the welding electrode is inclined, which can reduce the influence of the flame of the welding nozzle on the welding electrode far from the welding point, ensure that the welding electrode can be reliably conveyed to the part to be welded, and prevent softening and deformation during the process; the welding nozzle is inclined, which can improve the uniformity of heating the part to be welded.

[0024] Preferably, the two welding nozzles of a pair of welding tools respectively point to the left side and the right side of the part to be welded, and the conveying direction of the welding electrode points to the upper side of the part to be welded.

[0025] By adopting the above technical solution, it avoids the direct heating of the welding electrode by the flame of the welding nozzle, thus forming welding beads that splash everywhere, and can promote the flow and spreading of the welding liquid.

[0026] Preferably, the fixture includes a base, a support rod, an upper clamping piece and a lower clamping piece;

[0027] The base is connected to the welding platform in a magnetic adsorption manner. One end of the support rod is connected to the base by a thread. The other end of the support rod is fixedly connected to the upper clamping piece. The upper clamping piece and the lower clamping piece are locked by bolts. The elbow pipe is adaptively clamped in the groove between the upper clamping piece and the lower clamping piece.

[0028] By adopting the above technical solution, the base and the welding platform are magnetically attracted, so that the placement position of the base can be reasonably selected according to the different shapes of different elbow pipes, thereby reliably clamping the elbow pipe; the groove formed after the upper clamping piece and the lower clamping piece are surrounded is adapted to the elbow pipe, which improves the clamping stability of the elbow pipe and will not cause the elbow pipe to collapse.

[0029] In a second aspect, the present application provides a method for welding an elbow pipe, adopting the following technical solution:

[0030] A method for welding an elbow pipe includes the following steps:

[0031] S1. Insert the elbow pipe passing through the inside into the elbow pipe passing through the flared outside and fix it on the fixture. The pipe orifice of the outside elbow pipe is the part to be welded;

[0032] S2. The servo motor drives the turntable to rotate so that any welding nozzle points to the part to be welded;

[0033] S3. The air supply mechanism moves towards the turntable direction, the mixed gas input pipe is inserted into the welding nozzle pointing to the part to be welded, and the oxygen input pipe is inserted into the adjacent welding nozzle;

[0034] S4. The two welding nozzles pointing to the part to be welded are ignited, and the pallet reciprocates to form uniform heating on the left and right sides of the part to be welded;

[0035] S5. The electrode conveying mechanism conveys the electrode to a position 2 - 3 mm away from the part to be welded forward. After the electrode melts into welding fluid, it flows into the inner part of the elbow pipe on the outside. After the welding fluid cools, the welding is completed;

[0036] S6. The two pallets move in the same direction and away from the welding part. The mixed gas input amount and oxygen input amount of the air supply mechanism on one side are reduced, and the input of the mixed gas and oxygen of the air supply mechanism on the other side is stopped. At the same time, the second bracket on the other side moves in the direction away from the turntable, and the mixed gas input pipe and the oxygen input pipe are disengaged from the corresponding welding nozzles;

[0037] S7. The servo motor on the other side drives the turntable to rotate, and the welding nozzle disengaged from the oxygen input pipe is rotated to the position of the welding nozzle disengaged from the mixed gas input pipe;

[0038] S8. The second bracket on the other side moves in the direction close to the turntable, and the mixed gas input pipe and the oxygen input pipe are inserted into the corresponding welding nozzles;

[0039] S9. The air supply of the air supply mechanisms on both sides is restored. The flame generated by the welding nozzle on one side ignites the welding nozzle on the other side. The two pallets move in the same direction and close to the new part to be welded, and welding is carried out again.

[0040] By adopting the above technical solutions, after one welding is completed, during the process of taking out the welded elbow pipe and putting in the elbow pipe to be welded, the welding nozzle pointing to the part to be welded on either side can be replaced, and the ignition operation is carried out through the flame ejected from the welding nozzle pointing to the part to be welded on the other side, reducing the continuous working time of the welding nozzle and effectively preventing the welding nozzle from being burned due to overheating; at the same time, through the adjustment of the air supply amount of the air supply mechanism, it is ensured that the welding nozzle whose position is not adjusted can maintain a low gas consumption flame spraying state, reducing the loss of the mixed gas.

[0041] Preferably, the inner wall of the pipe orifice of the outer elbow pipe and the outer wall of the pipe orifice of the inner elbow pipe are both polished.

[0042] By adopting the above technical solutions, after the pipe orifice of the inner elbow pipe is inserted into the pipe orifice of the outer elbow pipe, the gap between them is more uniform, facilitating the flow of the welding fluid.

[0043] To sum up, the present application includes the following beneficial effects:

[0044] 1. Driven by the servo motor, the turntable rotates, causing the position of the welding torch to change. Each time, a welding torch in a cooling state rotates to a position pointing to the part to be welded and sprays fire. While ensuring the continuity of welding, the continuous working time of a single welding torch is effectively reduced, preventing the welding torch from burning out.

[0045] 2. During the process of changing the position of the welding torch, by adjusting the gas supply volume of the gas supply mechanism, it is ensured that the welding torch whose position has not been adjusted can maintain a low gas consumption spraying state, reducing the loss of the mixed gas.

[0046] 3. The fixture is connected to the welding platform by magnetic attraction, and the placement position of the fixture can be flexibly adjusted to ensure that the fixture can clamp elbows with different shapes, ensuring that an appropriate gap is formed after the two elbows are inserted for the filling of the welding fluid. Description of the Drawings

[0047] Figure 1 is a schematic perspective view of the present application;

[0048] Figure 2 is Figure 1 a reference diagram of the action state of

[0049] Figure 3 is a schematic perspective view of the fixture;

[0050] Figure 4 is a schematic perspective view of the welding tool;

[0051] Figure 5 is Figure 2 a schematic partial enlarged view of part A in

[0052] Figure 6 is Figure 2 a schematic partial enlarged view of part B in

[0053] In the figure: 1. Welding platform; 2. Fixture; 21. Base; 22. Support rod; 23. Upper clamping piece; 24. Lower clamping piece; 25. Bolt; 26. Groove; 3. Welding tool; 31. Turntable; 32. Welding torch; 33. Servo motor; 34. First bracket; 4. Gas supply mechanism; 41. Second bracket; 42. Second lead screw drive mechanism; 43. Mixed gas input pipe; 44. Oxygen input pipe; 45. Fixed ring; 46. Sealing ring; 5. Electrode conveying mechanism; 50. Electrode; 6. Elbow; 60. Part to be welded; 7. Support plate; 70. First lead screw drive mechanism. Detailed Description of the Embodiment

[0054] The following further describes the present application in detail with reference to the attached Figures 1-6 drawings.

[0055] Figure 1is a schematic perspective view of the present application, Figure 2 is Figure 1 a reference view of the operating state of. Refer to Figure 1 and Figure 2 , a bent pipe welding device, comprising a welding platform 1 and a fixture 2, a welding tool 3, a gas supply mechanism 4 and a welding rod 50 conveying mechanism 5 provided on the welding platform 1;

[0056] Figure 3 is a schematic perspective view of the fixture 2. Refer to Figure 3 , the fixture 2 includes a base 21, a support rod 22, an upper clamping piece 23 and a lower clamping piece 24. A magnet is provided at the bottom of the base 21, and the magnet can be adsorbed on the top of the welding platform 1. One end of the support rod 22 is connected to the base 21 by a thread, and the height of the top of the support rod 22 can be adjusted within a certain range. Both the magnetic adsorption connection and the threaded connection can improve the clamping stability of the bent pipe 6 with different shapes, ensuring that an appropriate gap can be formed after the two bent pipes 6 are inserted for the filling of the welding liquid. The other end of the support rod 22 is fixedly connected to the upper clamping piece 23, and the upper clamping piece 23 and the lower clamping piece 24 are locked by a bolt 25. The bent pipe 6 is adaptively clamped in the groove 26 between the upper clamping piece 23 and the lower clamping piece 24.

[0057] Figure 4 is a schematic perspective view of the welding tool 3. Refer to Figure 4 , a pair of welding tools 3 are respectively arranged on both sides of the bent pipe 6. The welding tool 3 includes a turntable 31 and a plurality of welding nozzles 32. The plurality of welding nozzles 32 are arranged in a circular pattern on the turntable 31. The servo motor 33 drives the turntable 31 to rotate, so that there is and only one welding nozzle 32 on any turntable 31 pointing to the welding part 60 to be welded, and an angle of 40° - 45° is maintained between the welding nozzle 32 and the welding part 60 to be welded. After one welding is completed, the welded bent pipe 6 is taken out and the bent pipe 6 to be welded is put in. During this process, the welding nozzle 32 pointing to the welding part 60 on any side can be replaced, and the ignition operation is carried out through the flame ejected by the welding nozzle 32 on the other side pointing to the welding part 60, reducing the working time of a single welding nozzle 32 and avoiding the welding nozzle 32 being burned out due to long-term work. Moreover, oxygen is always passed through the welding nozzle 32 that is about to turn to the position pointing to the welding part 60, which can prevent the welding nozzle 32 from being filled with air, and an evacuation operation is not required before ignition, simplifying the operation process.

[0058] Figure 5 is Figure 2 a schematic partial enlarged view of the A position in. Refer to Figure 5, the gas supply mechanism 4 includes a second bracket 41, a mixed gas inlet pipe 43 and an oxygen inlet pipe 44 provided on the second bracket 41. The mixed gas inlet pipe 43 supplies gas to one welding nozzle 32 pointing to the welding part 60, and the oxygen inlet pipe 44 supplies gas to the other welding nozzle 32 facing the welding part 60 after rotation. That is to say, the mixed gas inlet pipe 43 always inputs the mixed gas of acetylene and oxygen to the welding nozzle 32 pointing to the welding part 60, and the oxygen inlet pipe 44 always supplies gas to the welding nozzle 32 that is about to turn to point to the welding part 60. A pair of fixing rings 45 are also provided on the second bracket 41. The mixed gas inlet pipe 43 and the oxygen inlet pipe 44 respectively and correspondingly pass through a pair of fixing rings 45. A sealing ring 46 is provided on the side of the fixing ring 45 facing the welding nozzle 32. After the mixed gas inlet pipe 43 or the oxygen pipe is inserted into the corresponding welding nozzle 32, the sealing ring 46 can possibly seal the gap between the fixing ring 45 and the welding nozzle 32 to prevent gas leakage.

[0059] Figure 6 Yes Figure 2 Schematic partial enlarged view at B in [Figure]. See Figure 6 , the electrode 50 conveying mechanism 5 uses a cylinder to push the strip-shaped electrode 50 to displace the electrode 50 to convey the electrode 50 to the welding part 60. There is an angle of 40° - 45° between the electrode 50 and the welding part 60, and the electrode 50 is located above the welding part 60 and 2 - 3 mm away from the nozzle of the outer elbow 6, which can avoid the flame ejected by the welding nozzle 32 directly burning the electrode 50, causing welding beads and welding liquid to splash everywhere, and can also promote the uniform flow of the welding liquid in the gap between the two elbows 6 to improve the welding effect. At the same time, in order to further improve the uniformity of the penetration of the welding liquid, before welding, it is necessary to polish the outer wall of the nozzle of the inner elbow 6 and the inner wall of the nozzle of the outer elbow 6.

[0060] On the welding platform 1, there is also a pallet 7 driven by a first lead screw drive mechanism 70. On the pallet 7, there is a first bracket 34 for installing the servo motor 33 and a second bracket 41 for fixing the mixed gas input pipe 43 and the oxygen input pipe 44. The second bracket 41 is driven by a second lead screw drive mechanism 42. The first lead screw drive mechanism 70 drives the pallet 7 to move along the axial direction of the welding part 60, and the second lead screw drive mechanism 42 drives the second bracket 41 to move along the radial direction of the welding part 60. The second bracket 41 is shaped in a special way to prevent it from colliding with the first bracket 34 during movement; through the movement of the pallet 7, on the one hand, the flames ejected from the two welding nozzles 32 can swing at the welding part 60, improving the uniformity of heating the welding part 60. On the other hand, the welding tool 3 can be moved to a place far away from the welding part 60 by a large displacement, facilitating the removal of the welded elbow 6 and the fixing of the un-welded elbow 6 with enough space under the condition that the welding nozzles 32 do not go out; through the movement of the second bracket 41, the mixed gas input pipe 43 and the oxygen input pipe 44 can be inserted into or separated from the welding nozzle 32, that is, during the rotation of the turntable 31 and the change of the position of the welding nozzle 32, the mixed gas input pipe 43 and the oxygen pipe are separated from the welding nozzle 32, and after the position of the welding nozzle 32 is changed, the mixed gas input pipe 43 and the oxygen pipe are inserted into the welding nozzle 32 to realize the supply of mixed gas and oxygen.

[0061] A method for welding elbows in this application includes the following steps:

[0062] S1. Insert the elbow 6 passing through the inner side into the elbow 6 passing through the flared outer side and fix it on the fixture 2. The pipe orifice of the outer elbow 6 is the welding part 60.

[0063] S2. The servo motor 33 drives the turntable 31 to rotate so that any welding nozzle 32 points to the welding part 60.

[0064] S3. The gas supply mechanism 4 moves towards the turntable 31. The mixed gas input pipe 43 is inserted into the welding nozzle 32 pointing to the welding part 60, and the oxygen input pipe 44 is inserted into the adjacent welding nozzle 32.

[0065] S4. Ignite the two welding nozzles 32 pointing to the welding part 60, and the pallet 7 reciprocates to form uniform heating of the left and right sides of the welding part 60.

[0066] S5. The electrode 50 conveying mechanism 5 conveys the electrode 50 to a position 2 - 3 mm forward and away from the welding part 60. After the electrode 50 melts into welding fluid, it flows into the inner part of the outer elbow 6. After the welding fluid cools, the welding is completed.

[0067] S6. The two pallets 7 move in the same direction and away from the welding part, reducing the input amount of the mixed gas and the oxygen input amount of the gas supply mechanism 4 on one side, stopping the input of the mixed gas and the oxygen input of the gas supply mechanism 4 on the other side. At the same time, the second bracket 41 on the other side moves in the direction away from the turntable 31, and the mixed gas input pipe 43 and the oxygen input pipe 44 are separated from the corresponding welding nozzles 32;

[0068] S7. The servo motor 33 on the other side drives the turntable 31 to rotate, and rotates the welding nozzle 32 separated from the oxygen input pipe 44 to the position of the welding nozzle 32 separated from the mixed gas input pipe 43;

[0069] S8. The second bracket 41 on the other side moves in the direction close to the turntable 31, and the mixed gas input pipe 43 and the oxygen input pipe 44 are inserted into the corresponding welding nozzles 32;

[0070] S9. The gas supply mechanisms 4 on both sides resume gas supply, and the flame generated by the welding nozzle 32 on one side ignites the welding nozzle 32 on the other side. The two pallets 7 move in the same direction and close to the new part 60 to be welded, and welding is performed again.

[0071] Through the above steps, after one welding is completed, the welding nozzle 32 pointing to the part 60 to be welded on either side can be replaced, and the ignition operation is carried out by the flame ejected from the welding nozzle 32 pointing to the part 60 to be welded on the other side, reducing the continuous working time of a single welding nozzle 32, effectively preventing the welding nozzle 32 from being burned due to overheating, and the replacement operation of the welding nozzle 32 is carried out simultaneously with the taking out and putting in of the bent pipe 6, improving the continuity of the welding operation and thus improving the working efficiency.

[0072] The above are all the preferred embodiments of the present application, and the protection scope of the present application is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for welding a bent pipe using a bent pipe welding device, characterized in that, The elbow welding device includes a welding platform (1), a fixture (2), a welding tool (3), a gas supply mechanism (4), and an electrode (50) conveying mechanism (5) arranged on the welding platform (1); The fixture (2) is used to clamp the elbow (6) to be welded; A pair of the welding tools (3) are respectively arranged on both sides of the elbow (6). The welding tool (3) includes a turntable (31) and a plurality of welding nozzles (32). The plurality of welding nozzles (32) are arranged in a circular pattern on the turntable (31). A servo motor (33) drives the turntable (31) to rotate, and the plurality of welding nozzles (32) are sequentially rotated to the position pointing to the welding part (60); The gas supply mechanism (4) supplies gas to the welding nozzle (32) pointing to the welding part (60); The electrode (50) conveying mechanism (5) conveys the electrode (50) to the welding part (60); A support plate (7) is further arranged on the welding platform (1). The welding tool (3) and the gas supply mechanism (4) are both arranged on the support plate (7). The support plate (7) is driven by a first lead screw transmission mechanism (70) and reciprocates axially along the welding part (60); The gas supply mechanism (4) includes a second support (41). The second support (41) is driven by a second lead screw transmission mechanism (42) and reciprocates radially along the welding part (60); A mixed gas input pipe (43) and an oxygen input pipe (44) are arranged on the second support (41); The welding method includes the following steps: S1. Insert the inner elbow (6) into the flared outer elbow (6) and fix it on the fixture (2). The pipe orifice of the outer elbow (6) is the welding part (60); S2. The servo motor (33) drives the turntable (31) to rotate so that any welding nozzle (32) points to the welding part (60); S3. The gas supply mechanism (4) moves towards the turntable (31). The mixed gas input pipe (43) is inserted into the welding nozzle (32) pointing to the welding part (60), and the oxygen input pipe (44) is inserted into the adjacent welding nozzle (32); S4. Ignite the two welding nozzles (32) pointing to the welding part (60). The support plate (7) reciprocates to form uniform heating of the left and right sides of the welding part (60); S5. The electrode (50) conveying mechanism (5) conveys the electrode (50) to a position 2 - 3 mm forward and away from the welding part (60). After the electrode (50) melts into welding fluid, it flows into the inner part of the outer elbow (6). After the welding fluid cools, the welding is completed; S6. The two support plates (7) move in the same direction and away from the welding part. Reduce the input amount of the mixed gas and the oxygen input amount of the gas supply mechanism (4) on one side, stop the input of the mixed gas and the oxygen input of the gas supply mechanism (4) on the other side. At the same time, the second support (41) on the other side moves in the direction away from the turntable (31), and the mixed gas input pipe (43) and the oxygen input pipe (44) are separated from the corresponding welding nozzles (32); S7. The servo motor (33) on the other side drives the turntable (31) to rotate, and rotates the welding torch (32) that has been separated from the oxygen input pipe (44) to the position of the welding torch (32) that has been separated from the mixed gas input pipe (43). S8. The second bracket (41) on the other side moves towards the turntable (31), and the mixed gas input pipe (43) and the oxygen input pipe (44) are inserted into the corresponding welding torches (32). S9. The gas supply mechanisms (4) on both sides resume gas supply. The flame generated by the welding torch (32) on one side ignites the welding torch (32) on the other side. The two pallets (7) move in the same direction and approach the new part to be welded (60), and welding is performed again.

2. The elbow welding method according to claim 1, characterized in that, A first bracket (34) is provided on the pallet (7). The servo motor (33) is fixedly arranged on the first bracket (34). The output shaft of the servo motor (33) is connected to the turntable (31) and drives the turntable (31) to rotate.

3. The elbow welding method according to claim 1, characterized in that A pair of fixing rings (45) are further provided on the second bracket (41). The mixed gas input pipe (43) and the oxygen input pipe (44) respectively and correspondingly pass through the pair of fixing rings (45). A sealing ring (46) is provided on the side of the fixing ring (45) facing the welding torch (32), and the sealing ring (46) seals the gap between the end face of the fixing ring (45) and the end face of the welding torch (32).

4. The elbow welding method according to claim 1, characterized in that, An angle of 40° - 45° exists both between the welding electrode (50) and the part to be welded (60) and between the welding torch (32) pointing to the part to be welded (60) and the part to be welded (60).

5. The elbow welding method according to claim 1, wherein The two welding torches (32) of a pair of welding tools (3) respectively point to the left side and the right side of the part to be welded (60), and the conveying direction of the welding electrode (50) points to the upper side of the part to be welded (60).

6. The elbow welding method according to claim 1, characterized in that The fixture (2) includes a base (21), a support rod (22), an upper clamping piece (23) and a lower clamping piece (24). The base (21) is connected to the welding platform (1) in a magnetic adsorption manner. One end of the support rod (22) is connected to the base (21) by a thread. The other end of the support rod (22) is fixedly connected to the upper clamping piece (23). The upper clamping piece (23) and the lower clamping piece (24) are locked by a bolt (25). The elbow pipe (6) is adaptively clamped in the groove (26) between the upper clamping piece (23) and the lower clamping piece (24).

7. The elbow welding method according to claim 1, characterized in that, The inner wall of the pipe orifice of the outer elbow pipe (6) and the outer wall of the pipe orifice of the inner elbow pipe (6) are both polished.

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