Alloy pipe vacuum rotating friction plug welding device and welding method

Abstract

The invention discloses an alloy pipe vacuum rotating friction plug welding device and welding method.The device comprises a shell which is installed on the periphery of a heat insulation pipe inner pipe and a heat insulation pipe outer pipe which are in a concentric sleeving state and provided with an inner cavity, a sealed space is formed between the shell and the heat insulation pipe outer pipe, and the two ends of the heat insulation pipe inner pipe and the two ends of the heat insulation pipe outer pipe are welded; an air exhaust hole communicated with an inner cavity of the shell is formed in the pipe wall of one end of the heat insulation pipe outer pipe, a motor is installed in the inner cavity of the shell, a rotary connector of the motor is connected with a plug matched with the air exhaust hole, and the motor drives the plug to rotate to plug the welding air exhaust hole; one side of the shell is provided with an air exhaust nozzle communicated with the inner cavity of the shell, the air exhaust nozzle is connected with a vacuum pump, the space between the inner cavity of the shell and the inner and outer pipes of the heat insulation pipe is vacuumized, the vacuum degree needed by welding is achieved, and the high-quality welding effect is ensured. When the device is used for long pipe welding, oxidation can be avoided, the operation difficulty is reduced, and the production efficiency and the welding quality are improved.

Description

Technical Field

[0001] The present invention relates to a plug welding device, and particularly to a vacuum rotary friction plug welding device and welding method for alloy pipes. Background Art

[0002] In fields such as oil extraction and geothermal energy utilization, in order to reduce heat loss, pipes with internal and external heat insulation are often used to transfer media, ensuring that the heat exchange inside and outside the pipe is close to zero. In a conventional environment, due to the presence of oxygen, aluminum alloys are extremely prone to oxidation during welding. When traditional argon arc welding or laser welding is carried out in air, problems such as pores and cracks are likely to occur, which in turn affect the sealing performance of the welded part. The solder joints after plug welding of the air extraction holes need to have high-strength sealing performance, but conventional filler solders may cause uneven structure and stress, and cannot guarantee long-term application. Especially under the harsh conditions of the application well site, there is a great risk of air leakage. In addition, although vacuum welding technology can theoretically avoid oxidation problems, there are also great difficulties in actual operation. The vacuum welding equipment itself has a complex structure and high requirements for the operating environment and technology. More troublesome is that the length of aluminum alloy and titanium alloy heat-insulating pipes is generally about 10 meters, and it is difficult to completely place them in the vacuum chamber for air extraction and plug welding of the air extraction holes, which greatly limits the application of this efficient welding method in actual production. Summary of the Invention

[0003] The purpose of the present invention is to provide a vacuum rotary friction plug welding device and welding method for alloy pipes, which solves the problem of plugging the vacuum air extraction holes of heat-insulating alloy pipes such as aluminum alloys, avoids air leakage and oxidation during welding, reduces the operation difficulty, adapts to long pipe welding, thereby improving production efficiency and welding quality, and at the same time enhancing the vacuum degree of the heat-insulating pipe.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] A vacuum rotary friction plug welding device for alloy pipes includes a housing with an inner cavity installed around the inner heat-insulating pipe and the outer heat-insulating pipe that are concentrically sleeved. A sealed space is formed between the housing and the outer heat-insulating pipe. The two ends of the inner heat-insulating pipe and the outer heat-insulating pipe are welded. An air extraction hole communicating with the inner cavity of the housing is opened on the pipe wall at one end of the outer heat-insulating pipe. A motor is installed in the inner cavity of the housing. The rotary joint of the motor is connected with a plug adapted to the air extraction hole, and the plug is rotated by the motor to plug and weld the air extraction hole. An air extraction nozzle communicating with the inner cavity of the housing is arranged on one side of the housing, and a vacuum pump is connected through the air extraction nozzle, so that the inner cavity of the housing and the space between the inner heat-insulating pipe and the outer heat-insulating pipe can be evacuated to a vacuum.

[0006] Further, the outer shell includes a closed cavity at the upper end and an open part in a saddle shape at the lower end. The circular diameter of the open part at the lower end is larger than the outer diameter of the heat-insulating pipe. A fixing ring adapted to the outer pipe of the heat-insulating pipe is integrally provided at the open part at the lower end of the outer shell. A fastening ear is provided on one side of the fixing ring, and the outer shell is fixed on the outer pipe of the heat-insulating pipe by locking the fastening ear with a bolt.

[0007] Further, a sealing ring is provided at the position where the open part at the lower end of the outer shell contacts the outer pipe of the heat-insulating pipe, so as to form a sealed space between the open part in a saddle shape at the lower end of the outer shell and the outer pipe of the heat-insulating pipe.

[0008] Further, the air extraction hole is in the shape of an inverted truncated cone, and its diameter gradually decreases from outside to inside.

[0009] Further, air-permeable grooves are provided on the side surface of the plug, and the groove depth is greater than 0.1 mm.

[0010] Further, an annular motor lifting ring is fixed on the inner side wall of the outer shell. A motor tray for assembling a motor is installed through the annular motor lifting ring. A plurality of guiding columns are installed on the annular motor lifting ring. Guiding holes matching the guiding columns are provided on the motor tray. The guiding columns penetrate through the guiding holes and are connected to the annular motor lifting ring to install the motor tray in the inner cavity of the outer shell, and the motor tray can move up and down along the guiding columns; the motor is vertically installed on the motor tray, and the distance from the motor tray to the outer pipe of the heat-insulating pipe is less than the length after the plug is connected to the rotary joint. A pushing spring is sleeved on the guiding column between the annular motor lifting ring and the motor tray.

[0011] Further, an insulating sealing pressing plate is fixed on the other side of the outer shell by bolts. A wiring terminal is encapsulated in the insulating sealing pressing plate. The start-stop and speed of the motor are controlled by an external power supply through the wiring terminal. A vacuum sealing gasket is installed between the insulating sealing pressing plate and the outer shell to ensure the sealing effect; an electrical junction box is also installed at the position of the insulating sealing pressing plate on the outer side of the outer shell.

[0012] A welding method for an alloy pipe vacuum rotary friction plug welding device includes the following steps:

[0013] Step 1: Weld the two ends of the inner heat-insulating pipe and the outer heat-insulating pipe. An air extraction hole is opened at a position on the outer heat-insulating pipe more than 100 mm away from the pipe end. Rotate the inner and outer heat-insulating pipes so that the air extraction hole is located above. Install the outer shell on the outer heat-insulating pipe and ensure sealing.

[0014] Step 2: The plug connected to the motor is inserted into the air extraction hole. The motor is lifted and drives the motor tray to move upward along the guiding column. The pushing spring is in an elastically compressed state, so that the pressure on the welding surface is greater than 10 kN.

[0015] Step 3: Connect a vacuum pump to the air extraction nozzle and evacuate to make the vacuum degree between the inner cavity of the housing, the inner tube and the outer tube of the heat-insulating tube reach 3×10 -2 Pa, then start the motor to drive the plug to rotate and block and weld the air extraction hole; the initial rotational speed of the motor is 1000 rpm to 1500 rpm, and it rotates continuously for 2 to 10 seconds; then the rotational speed is reduced to 300 rpm to 800 rpm and it continues to rotate for 2 to 6 seconds; finally, let it stand for more than 2 seconds to complete the welding.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] Through local enclosure, the present invention realizes the welding of the plug for the vacuum air extraction hole of the heat-insulating tube such as aluminum alloy under a vacuum state. The inner and outer tube cavities of the heat-insulating tube are evacuated and the air extraction hole is welded and blocked under a vacuum state. At the same time, the rotary welding mechanism is enclosed in the vacuum cavity for welding operation to ensure that materials such as aluminum alloy are not oxidized during welding. By utilizing the vacuum environment to inhibit oxidation and combining the solid-state welding advantages of rotary friction welding, high-quality metallurgical connection of the same materials is realized, significantly improving the welding performance.

[0018] The present invention reduces the cavity space to be evacuated through the combination of the housing and the seal, speeds up the vacuum extraction speed, and improves the working efficiency. In addition, by enclosing the rotating parts inside the housing and avoiding the existence of an external rotating mechanism, seamless welding is realized, ensuring no air leakage during the welding process.

[0019] Furthermore, the present invention sets the distance between the motor tray and the outer tube of the heat-insulating tube to be less than the distance between the plug connected by the rotary joint and the outer tube of the heat-insulating tube. When the plug is inserted into the air extraction hole, the motor is lifted, driving the motor tray to make the thrust spring in a compressed state. The compressed spring generates a downward thrust acting on the welding surface. The plug and the air extraction hole adopt a matching frustum structure. Under the action of the gravity of the motor and the elastic force of the spring, the conical surface of the air extraction hole bears the weight of the motor and the thrust of the spring, making the welding surface receive a rotating pressure during the welding process. At the same time, air-permeable grooves are processed on the conical surface of the plug, which not only ensures the smoothness of the air extraction channel but also increases the friction between the welding surfaces, improves the welding efficiency, and ensures the consistency of the welded base material and the weld seam for welding of the same materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic cross-sectional structure diagram of the plug welding device of the present invention;

[0021] Figure 2 is Figure 1 a partial enlarged view of part A in

[0022] Figure 3 a schematic welding structure diagram of the inner and outer tubes of the heat-insulating tube.

[0023] In the figure: 1 - inner pipe of the heat-insulating pipe; 2 - outer pipe of the heat-insulating pipe; 3 - fixing ring; 31 - fastening ear; 4 - outer shell; 5 - sealing ring; 6 - air extraction hole; 7 - air extraction nozzle; 8 - motor; 81 - rotary joint; 9 - plug; 10 - annular motor lifting ring; 11 - guiding column; 12 - motor tray; 13 - pushing spring; 14 - insulating sealing pressing plate; 15 - terminal; 16 - vacuum gasket; 17 - electrical junction box. Specific embodiments

[0024] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] As Figure 1 , 2 shown, a vacuum rotary friction plug welding device for alloy pipes according to this embodiment includes an outer shell 4 with an inner cavity installed around the concentrically sleeved inner pipe 1 and outer pipe 2 of the heat-insulating pipe. The outer shell 4 includes a closed cavity at the upper end and an open part in a saddle shape at the lower end, with a thickness greater than 3 mm. The circular diameter of the open part at the lower end is slightly larger than the diameter of the outer pipe 2 of the heat-insulating pipe. A fixing ring 3 adapted to the outer pipe 2 of the heat-insulating pipe is integrally provided at the open part at the lower end of the outer shell 4. A fastening ear 31 is provided on one side of the fixing ring 3, and the outer shell 4 is fixed on the outer pipe 2 of the heat-insulating pipe by locking the fastening ear 31 with bolts. A sealing ring 5 is provided at the position where the open part at the lower end of the outer shell 4 contacts the outer pipe 2 of the heat-insulating pipe, so that a sealed space is formed between the open part in a saddle shape at the lower end of the outer shell 4 and the outer pipe 2 of the heat-insulating pipe. As Figure 3 shown, the inner pipe 1 and the outer pipe 2 of the heat-insulating pipe are welded at both ends. An air extraction hole 6 communicating with the inner cavity of the outer shell 4 is opened on the wall of one end of the outer pipe 2 of the heat-insulating pipe at a position more than 100 mm away from the pipe end. The air extraction hole 6 is in the shape of an inverted frustum, and the diameter gradually decreases from outside to inside. A motor 8 is installed in the inner cavity of the outer shell 4. The rotary joint 81 of the motor 8 is connected with a plug 9 adapted to the air extraction hole 6, and the plug 9 is driven by the motor 8 to rotate and seal and weld the air extraction hole 6. Venting grooves are opened on the side of the plug 9, and the groove depth is greater than 0.1 mm. An air extraction nozzle 7 communicating with the inner cavity of the outer shell 4 is provided on one side of the outer shell 4. By connecting a vacuum pump through the air extraction nozzle 7, the inner cavity of the outer shell 4 and the space between the inner pipe 1 and the outer pipe 2 of the heat-insulating pipe can be evacuated to the vacuum degree standard required for welding, so as to achieve a local vacuum environment and ensure a high-quality welding effect. During welding or evacuation, the venting grooves can allow air to be discharged from around the plug 9, ensuring that there are no bubbles or residual gases in the welding area and reaching a vacuum state, thereby improving the welding quality.

[0026] A circular motor sling 10 is fixed on the inner side wall of the outer shell 4. A number of guide posts 11 are installed on the circular motor sling 10. Guide holes matching the guide posts 11 are provided on the motor tray 12. The guide posts 11 penetrate through the guide holes and are connected to the circular motor sling 10 to install the motor tray 12 in the inner cavity of the outer shell 4, and the motor tray 12 can move up and down along the guide posts 11; the motor 8 is vertically installed on the motor tray 12, and the distance from the motor tray 12 to the outer tube 2 of the heat-insulating tube is less than the length after the plug 9 is connected to the rotary joint 81. A push spring 13 is sleeved on the guide posts 11 between the circular motor sling 10 and the motor tray 12. When the plug 9 is inserted into the air extraction hole 6, the motor 8 is lifted up, driving the motor tray 12 to move upward along the guide posts 11, so that the push spring 13 is in a compressed state. The compressed push spring 13 generates a downward thrust force, which can uniformly apply pressure and act together with the gravity of the motor 8, so that the motor tray 12 has a tendency and thrust to move downward along the guide posts 11 between the circular motor sling 10 and the motor 8, providing a stable welding pressure and ensuring more stable welding.

[0027] On the other side of the outer shell 4, a terminal 15 encapsulated in an insulating sealing pressing plate 14 is provided. The start-stop and speed of the motor 8 are controlled by an external power supply through the terminal 15. The insulating sealing pressing plate 14 is fixed on the outer shell 4 by bolts, and a vacuum sealing gasket 16 is installed between the insulating sealing pressing plate 14 and the outer shell 4 to ensure the sealing effect. An electrical junction box 17 is also installed at the position of the insulating sealing pressing plate 14 on the outside of the outer shell 4, preventing accidental contact of personnel with live parts and reducing the risk of electric shock.

[0028] A welding method for an alloy tube vacuum rotary friction plug welding device includes the following steps:

[0029] Step 1: Weld the two ends of the inner heat-insulating tube 1 and the outer heat-insulating tube 2. An air extraction hole 6 is opened on the outer heat-insulating tube 2 at a position more than 100 mm away from the tube end, and the inner and outer heat-insulating tubes are rotated so that the air extraction hole 6 is located above. The outer shell 4 is installed on the outer heat-insulating tube 2 and the sealing is ensured;

[0030] Step 2: The plug 9 connected to the motor 8 is inserted into the air extraction hole 6. The motor 8 is lifted up and drives the motor tray 12 to move upward along the guide posts 11. The push spring 13 is in an elastically compressed state, so that the pressure on the welding surface is greater than 10 kN;

[0031] Step 3: Connect a vacuum pump to the air extraction nozzle 7 to extract air so that the vacuum degree in the inner cavity of the outer shell 4 and between the inner heat-insulating tube 1 and the outer heat-insulating tube 2 reaches 3×10 -2After [Pa], start the motor 8 to drive the plug 9 to rotate and block and weld the air extraction hole 6; the initial rotational speed of the motor 8 is 1000 rpm to 1500 rpm, and it rotates continuously for 2 to 10 seconds; then reduce the rotational speed to 300 rpm to 800 rpm and continue to rotate for 2 to 6 seconds; finally, stand still for more than 2 seconds to complete the welding.

Claims

1. An alloy tube vacuum rotary friction welding device, characterized in that: The invention comprises an outer shell (4) with an inner cavity which is installed on the periphery of an insulating inner tube (1) and an insulating outer tube (2) which are in a concentric sleeve state, a sealed space is formed between the outer shell (4) and the insulating outer tube (2), the inner tube (1) and the insulating outer tube (2) are welded at both ends, an exhaust hole (6) which is connected to the inner cavity of the outer shell (4) is opened on the tube wall at one end of the insulating outer tube (2), a motor (8) is installed in the inner cavity of the outer shell (4), a rotating joint (81) of the motor (8) is connected to a plug (9) which is adapted to the exhaust hole (6), and the plug (9) is driven by the motor (8) to rotate and seal the welded exhaust hole (6); an exhaust nozzle (7) which is connected to the inner cavity of the outer shell (4) is arranged on one side of the outer shell (4), and a vacuum pump is connected to the exhaust nozzle (7) to evacuate the inner cavity of the outer shell (4) and the space between the inner tube (1) and the insulating outer tube (2) into a vacuum.

2. The alloy tube vacuum rotary friction welding device according to claim 1 is characterized in that: The outer shell (4) comprises a closed cavity at the upper end and a saddle-shaped opening at the lower end, the circular diameter of the opening at the lower end is larger than the diameter of the outer tube (2) of the thermal insulation pipe, and the lower end opening of the outer shell (4) is also integrally provided with a fixing ring (3) adapted to the outer tube (2) of the thermal insulation pipe, and a fastening ear (31) is provided on one side of the fixing ring (3), and the outer shell (4) is fixed to the outer tube (2) of the thermal insulation pipe by bolting the fastening ear (31).

3. The alloy tube vacuum rotary friction welding device according to claim 2 is characterized in that: A sealing ring (5) is provided at a position where the lower opening of the outer shell (4) contacts the outer tube (2) of the heat-insulating tube, so that a sealed space is formed between the saddle-shaped opening at the lower end of the outer shell (4) and the outer tube (2) of the heat-insulating tube.

4. The alloy tube vacuum rotary friction welding device according to claim 3 is characterized in that: The air extraction hole (6) is in the shape of an inverted truncated cone, and its diameter gradually decreases from the outside to the inside.

5. The alloy tube vacuum rotary friction welding device according to claim 4 is characterized in that: A ventilation groove is provided on the side of the plug (9), and the groove depth is greater than 0.1 mm.

6. The alloy tube vacuum rotary friction welding device according to any one of claims 1 to 5, characterized in that: An annular motor hanging ring (10) is fixed on the inner side wall of the shell (4), and a motor tray (12) for assembling the motor (8) is installed through the annular motor hanging ring (10). A plurality of guide posts (11) are installed on the annular motor hanging ring (10). The motor tray (12) is provided with guide holes matching the guide posts (11). The guide posts (11) pass through the guide holes and are connected to the annular motor hanging ring (10). The motor tray (12) is installed in the inner cavity of the shell (4), and the motor tray (12) can move up and down along the guide posts (11). The motor (8) is vertically installed on the motor tray (12), and the distance between the motor tray (12) and the outer tube (2) of the insulation tube is less than the length after the plug (9) is connected to the rotary joint (81). A push spring (13) is sleeved on the guide post (11) between the annular motor hanging ring (10) and the motor tray (12).

7. The alloy tube vacuum rotary friction welding device according to claim 6, characterized in that: An insulating sealing plate (14) is fixed to the other side of the housing (4) by bolts, a terminal (15) is encapsulated in the insulating sealing plate (14), and the start / stop and speed of the motor (8) are controlled by an external power supply via the terminal (15), and a vacuum sealing gasket (16) is installed between the insulating sealing plate (14) and the housing (4) to ensure a sealing effect; an electrical junction box (17) is also installed outside the housing (4) at a position of the insulating sealing plate (14).

8. A welding method for the alloy tube vacuum rotary friction welding device as claimed in claim 7, characterized in that: The following steps are involved: Step 1: Weld the two ends of the inner tube (1) and the outer tube (2) of the heat-insulating tube, open an exhaust hole (6) at a position greater than 100 mm away from the tube end on the outer tube (2), rotate the inner and outer tubes of the heat-insulating tube so that the exhaust hole (6) is located at the top, and install the outer shell (4) on the outer tube (2) of the heat-insulating tube to ensure sealing; Step 2: The plug (9) connected to the motor (8) is embedded in the exhaust hole (6), the motor (8) is lifted up and drives the motor tray (12) to move upward along the guide column (11), pushing the spring (13) to be in an elastically compressed state, so that the welding surface pressure is greater than 10kN; Step 3: Connect the vacuum pump to the vacuum nozzle (7) to evacuate the air so that the vacuum degree of the inner cavity of the shell (4) and between the inner tube (1) and the outer tube (2) of the thermal insulation pipe reaches 3×10 -2 After Pa, the motor (8) is started to drive the plug (9) to rotate and seal the welding exhaust hole (6); the initial rotation speed of the motor (8) is 1000rpm to 1500rpm, and the rotation is continued for 2 to 10 seconds; then the rotation speed is reduced to 300rpm to 800rpm, and the rotation is continued for 2 to 6 seconds; finally, it is left to stand for more than 2 seconds to complete the welding.

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