CN114700581A

CN114700581A - Connecting pipe welding device

Info

Publication number: CN114700581A
Application number: CN202210312750.7A
Authority: CN
Inventors: 杨久子; 柳永刚; 张行; 李敏; 甘威; 郭涛
Original assignee: Gree Electric Appliances Inc of Zhuhai; Gree Hefei Electric Appliances Co Ltd
Current assignee: Gree Electric Appliances Inc of Zhuhai; Gree Hefei Electric Appliances Co Ltd
Priority date: 2022-03-28
Filing date: 2022-03-28
Publication date: 2022-07-05

Abstract

The invention provides a connecting pipe welding device, which comprises: overcoat and inner core, the inside of overcoat has the chamber of holding, the inner core is including first shaft segment and the second shaft segment that meets, first shaft segment and second shaft segment all are located the inside of holding the chamber, the inside of inner core is provided with first inside passage and second inside passage, the at least part of first inside passage is located the inside of first shaft segment, the at least part of second inside passage is located the inside of second shaft segment, and first inside passage and second inside passage intercommunication, the aperture of first inside passage is less than the aperture of second inside passage and forms first step in both meet departments, can block the air current through first step when the air current flows to first inside passage from second inside passage, welding set can weld the connecting pipe of different materials. The invention can improve the uniform mixing degree of the air and the gas mixture, the flame temperature field is softer, and the problem of high welding difficulty of the copper-aluminum connecting pipe is effectively solved.

Description

Connecting pipe welding set

Technical Field

The invention belongs to the technical field of welding, and particularly relates to a connecting pipe welding device.

Background

The existing heat exchanger relates to the welding of a copper pipe and an aluminum pipe, however, the welding difficulty of a copper-aluminum connecting pipe is high, the copper-aluminum welding difficulty is mainly that the melting point of copper is about 600 ℃ higher than that of aluminum, and the aluminum pipe base metal is easy to over-burn and damage in the welding and heating process. Therefore, the requirement on the temperature field of heating flame is extremely high when copper and aluminum are welded, the aluminum pipe also reaches the welding point temperature when the flame is required to heat the copper pipe to the welding temperature, and the aluminum pipe cannot be over-sintered. The welding means or structure in the prior art can not realize the full-automatic production welding of the copper-aluminum assembly.

The invention provides a welding device for connecting pipes, which is researched and designed because the technical problems that the welding difficulty of copper-aluminum connecting pipes in the prior art is high, the full-automatic production welding of copper-aluminum components cannot be realized, and the like.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defects that the copper-aluminum connecting pipe in the prior art has high welding difficulty and can not realize full-automatic production welding of a copper-aluminum assembly, thereby providing a connecting pipe welding device.

The invention provides a connecting pipe welding device, which comprises:

the welding device comprises an outer sleeve and an inner core, wherein an accommodating cavity is formed in the outer sleeve, the inner core comprises a first shaft section and a second shaft section which are connected, the first shaft section and the second shaft section are located in the accommodating cavity, a first internal channel and a second internal channel are arranged in the inner core, at least part of the first internal channel is located in the first shaft section, at least part of the second internal channel is located in the second shaft section, the first internal channel is communicated with the second internal channel, the aperture of the first internal channel is smaller than that of the second internal channel, a first step is formed at the joint of the first shaft section and the second shaft section, airflow can be blocked by the first step when flowing to the first internal channel from the second internal channel, and the welding device can weld connecting pipes made of different materials.

In some embodiments, one end of the first internal channel is located at a position where the first shaft section meets the second shaft section and communicates with the second internal channel, the other end of the first internal channel extends to communicate with the accommodating cavity, one end of the second internal channel is located at a position where the first shaft section meets the second shaft section, and the other end of the second internal channel extends to the air inlet end of the inner core.

In some embodiments, the first internal passage is located entirely inside the first shaft section and extends in the axial direction of the inner core, one end of the first internal passage is located at one axial end of the first shaft section, the other end is located at the other axial end of the first shaft section, and a portion of the second internal passage is located inside the second shaft section and also extends in the axial direction of the inner core.

In some embodiments, a first gap is formed between the outer periphery of the second shaft section and the inner wall of the outer sleeve, a communication hole is formed in the second shaft section, one end of the communication hole is communicated with the second internal channel, the other end of the communication hole is communicated with the first gap, and gas in the second internal channel can be conducted into the first gap through the communication hole.

In some embodiments, the communication hole extends in a radial direction of the second shaft section; and/or the communication holes are multiple and are arranged at intervals along the circumferential direction of the second shaft section.

In some embodiments, the outer diameter of the first shaft section is larger than the outer diameter of the second shaft section to form a second step at the junction of the first shaft section and the second shaft section, a second gap is provided between the outer periphery of the first shaft section and the inner wall of the outer sleeve, the air flow from the first gap to the second gap can be blocked by the second step, and the air flow reaching the second gap can enter the accommodation cavity.

In some embodiments, the inner core further comprises a third shaft segment, the third shaft segment is connected with one axial end of the second shaft segment, so that the second shaft segment is located between the first shaft segment and the third shaft segment, a first external thread is arranged on the periphery of the third shaft segment, an internal thread is arranged on the inner wall of the outer sleeve opposite to the third shaft segment, and the first external thread and the internal thread can be in threaded fit to fix the inner core and the outer sleeve.

In some embodiments, the inner core further includes a fourth axial segment and a fifth axial segment, the fifth axial segment abuts against an end surface of one axial end of the sheath, the fifth axial segment is of a hexahedral structure, an outer periphery of a cross section of the fifth axial segment is hexagonal, the fourth axial segment is located between the third axial segment and the fifth axial segment, one end of the fourth axial segment is connected with the third axial segment, the other end of the fourth axial segment is connected with the fifth axial segment, and an outer peripheral wall of the fourth axial segment is a circumferential surface.

In some embodiments, the inner core further comprises a sixth shaft section, one end of the sixth shaft section is connected with the fifth shaft section, the other end of the sixth shaft section is formed into an air inlet end, mixed air of air and fuel gas can enter the second internal channel through the air inlet end, and a second external thread is arranged on the outer peripheral wall of the sixth shaft section and can be tightly connected with the welding gun.

In some embodiments, the aperture of the accommodating cavity of the outer sleeve is 10mm to 12mm, and the portion of the outer sleeve, which is connected with the fifth shaft section, is also a head end which is arranged in a hexahedral structure, and the outer periphery of the cross section of the outer sleeve is hexagonal in shape so as to match with the fifth shaft section in the hexahedral structure.

In some embodiments, the first shaft section is a cylindrical structure having a circumferential outer surface, and the second shaft section is a cylindrical structure having a circumferential outer surface.

In some embodiments, the connecting tube of different materials comprises a copper tube and an aluminum tube.

The welding device for the connecting pipe provided by the invention has the following beneficial effects:

1. the inner core matched with the outer sleeve is arranged into a structure comprising the first shaft section and the second shaft section, the first internal channel is positioned at the position of the first shaft section, the second internal channel is positioned at the position of the second shaft section, the aperture of the first internal channel is smaller than that of the second internal channel, and when air flows from the second internal channel to the first internal channel, partial air flow is blocked by the first step, so that partial air flow can be blocked and returned to the second internal channel, and the aim of further mixing with the air flow in the second internal channel is fulfilled, therefore, the uniform mixing degree of air and gas mixture can be improved, the gas and air are uniformly mixed, the flame temperature field is better, the requirement that the temperature of the aluminum pipe slowly rises to reach the welding melting point when the copper pipe reaches the welding temperature, and the aluminum pipe also slowly reaches the welding point temperature when the flame heats the copper pipe to the welding temperature, the aluminum pipe can not be overburnt, the problem of high welding difficulty of the copper-aluminum connecting pipe is effectively solved, and the full-automatic production welding of the copper-aluminum assembly is effectively realized. The invention adopts a brand-new gun nozzle structure, overcomes the high-difficulty welding technical barriers of copper-aluminum dissimilar base metals, develops an air welding gun nozzle initiated by the industry, realizes uniform flame control, meets the technical requirements of copper-aluminum welding, fills the blank of the industry and solves the difficult problem of the copper-aluminum flame welding technology;

2. the invention also can enable the gas in the second internal channel to enter the first gap through the communicating hole by arranging the communicating hole at the second internal channel, reduce the flowing speed of the gas flow, further improve the mixing uniformity of the gas and the air mixture, further solve the problem of overburning of the aluminum pipe and solve the problem of high welding difficulty of the copper-aluminum connecting pipe; the invention also can further block the flow of air current through the second step formed on the periphery of the first shaft section and the second shaft section, further improve the mixing uniformity of gas and air mixture, and further solve the problem of high welding difficulty of the copper-aluminum connecting pipe; the second clearance that forms between first shaft section and the overcoat can be with the air current that is blockked by the second step and get into in the air current leading-in to holding the chamber in the first clearance, because the flow area of second clearance is less than the flow area in first clearance, can further reduce the flow velocity of air current, improves the mixture degree of consistency of gas and air mixture, further solves the problem that the aluminum pipe is overburnt, solves the big problem of copper aluminium connecting pipe welding degree of difficulty.

Drawings

FIG. 1 is a front view of a welding apparatus for a connection pipe according to the present invention;

FIG. 2 is a view showing an internal cross-section of a connecting pipe welding apparatus according to the present invention;

FIG. 3 is a view showing the appearance of an inner core in the welding apparatus for connecting pipes according to the present invention;

FIG. 4 is a view showing an external appearance of an outer jacket of the joint pipe welding apparatus of the present invention;

fig. 5 is a sectional view showing the inside of an outer jacket in the joint pipe welding apparatus of the present invention.

The reference numbers in the figures denote:

1. a jacket; 10. an accommodating chamber; 11. an internal thread; 12. a tip; 2. an inner core; 21. a first shaft section; 22. a second shaft section; 23. a first internal passage; 24. a second internal passage; 25. a first step; 26. an air inlet end; 27. a first gap; 28. a communicating hole; 29. a second step; 210. a second gap; 211. a third shaft section; 212. a first external thread; 213. a fourth shaft section; 214. a fifth shaft section; 215. a sixth shaft section; 216. a second external thread.

Detailed Description

As shown in fig. 1 to 5, the present invention provides a connecting pipe welding apparatus, which includes:

the outer sleeve 1 and the inner core 2 (or core print), the inner part of the outer sleeve 1 has a containing cavity 10, the inner core 2 includes a first shaft section 21 and a second shaft section 22 which are connected, the first shaft section 21 and the second shaft section 22 are both located inside the containing cavity 10, the inner core 2 is provided with a first internal channel 23 and a second internal channel 24 inside, at least part of the first internal channel 23 is located inside the first shaft section 21, at least part of the second internal channel 24 is located inside the second shaft section 22, the first internal channel 23 is communicated with the second internal channel 24, the aperture of the first internal channel 23 is smaller than that of the second internal channel 24 to form a first step 25 at the joint of the two, and when the air flow flows from the second internal channel 24 to the first internal channel 23, the air flow can be blocked by the first step 25, the welding device can weld connecting pipes made of different materials.

According to the invention, the inner core matched with the outer sleeve is arranged into a structure comprising the first shaft section and the second shaft section, the first internal channel is positioned at the position of the first shaft section, the second internal channel is positioned at the position of the second shaft section, the aperture of the first internal channel is smaller than that of the second internal channel, and when the airflow flows to the first internal channel from the second internal channel, partial airflow is blocked by the first step, so that partial airflow can be blocked and returned to the second internal channel, the purpose of further mixing with the airflow in the second internal channel is completed, therefore, the mixing uniformity degree of the air and the gas mixture can be further improved, the gas and the air are uniformly mixed, the flame temperature field is softer, the requirement that the temperature of the aluminum pipe slowly rises to reach the welding melting point when the copper pipe reaches the welding temperature, and the aluminum pipe also slowly reaches the welding point temperature when the copper pipe is heated to the welding temperature by flame, the aluminum pipe can not be over-burnt, the problem of high welding difficulty of the copper-aluminum connecting pipe is effectively solved, and the full-automatic production welding of the copper-aluminum assembly is effectively realized. The invention adopts a brand new gun nozzle structure, overcomes the high difficulty of welding the copper-aluminum dissimilar parent metal, develops the air welding gun nozzle initiated by the industry, realizes uniform flame control, meets the technical requirements of copper-aluminum welding, fills the blank of the industry and solves the problem of the copper-aluminum flame welding technology.

The device mainly comprises a stainless steel gun nozzle outer sleeve and a brass inner core, and is mainly used for welding and heating different parent metals with larger melting point temperature difference, such as copper, aluminum and the like, wherein external threads at the end part of the inner core are tightly matched and locked with a welding gun in normal use, air and fuel gas enter a second internal channel 24 simultaneously and rapidly flow to a first step 25, about 30% of mixed combustion gas directly flows out through a circular inner hole (namely a communicating hole 28) at the first internal channel 23, the rest 70% of gas is blocked by the first step 25 to rebound and then rapidly diffuse after colliding with the subsequently entered air and fuel gas mixed gas, at the moment, 50% of the rest gas flows out (upwards again) from the second internal channel 24 in a re-vortex mode, 50% of the rest gas flows out through the communicating hole 28, the gas flowing out from the side hole collides with the inner wall of the outer sleeve, and flows out through a gap between the outer sleeve and the inner core in a snake-shaped mode under the push of the subsequently flowed gas.

The structure of the invention realizes the guiding function of air and fuel gas, so that the gas can be uniformly distributed at the connecting position of the inner core and the outer sleeve, the gas at the outflow end of the gun head is uniform, the uniformity of a welding flame temperature field can be ensured if the outflow gas is uniform, and the welding stability is further improved.

The difficulty of copper-aluminum welding is mainly that the melting point of copper is about 600 ℃ higher than that of aluminum, and the aluminum pipe base metal is easy to be over-burnt and damaged in the welding and heating process, so that the requirement on the temperature field of heating flame during copper-aluminum welding is extremely high, the aluminum pipe also reaches the welding point temperature when the flame is required to heat the copper pipe to the welding temperature, and the aluminum pipe cannot be over-burnt. The invention adopts the combination structure of the inner core and the outer cylinder, realizes the rapid mixing of air and fuel gas during welding, ensures that flame is distributed at a uniform speed to form a uniform temperature field, ensures that the fuel gas and the air are uniformly mixed, ensures that the flame temperature field is softer, ensures that the temperature of the aluminum pipe slowly rises to meet the requirement of welding melting point when the copper pipe reaches the welding temperature, ensures that the aluminum pipe cannot be overburnt, and meets the technical requirement of copper-aluminum welding.

In some embodiments, one end of the first internal channel 23 is located at the position where the first shaft section 21 meets the second shaft section 22 and is communicated with the second internal channel 24, the other end of the first internal channel 23 is extended to be communicated with the accommodating cavity 10, and one end of the second internal channel 24 is located at the position where the first shaft section 21 meets the second shaft section 22 and is extended to be the air inlet end 26 of the inner core 2. The first internal channel extends from the joint position of the first shaft section and the second shaft section to the other end of the first shaft section, so that the air flow can be guided out of the first internal channel and enter the accommodating cavity, the second internal channel introduces the mixed gas of gas and air from the air inlet end of the inner core and guides the mixed gas to the first internal channel, and the first step is blocked at the joint position of the first internal channel and the second internal channel, so that the mixing uniformity is effectively increased, the flame temperature field is softer, the aluminum pipe also slowly reaches the welding point temperature when the flame heats the copper pipe to the welding temperature, the aluminum pipe cannot generate an overburning phenomenon, and the problem of the copper-aluminum flame welding technology is solved.

In some embodiments, the first internal channel 23 is located entirely inside the first shaft segment 21 and extends in the axial direction of the inner core 2, one end of the first internal channel 23 is located at one axial end of the first shaft segment 21, the other end is located at the other axial end of the first shaft segment 21, and a part of the second internal channel 24 is located inside the second shaft segment 22 and also extends in the axial direction of the inner core 2. The first internal channel is completely positioned inside the first shaft section, extends along the axial direction of the inner core, can be communicated with the second internal channel from one axial end of the first shaft section to introduce mixed gas and lead the mixed gas to the other axial end of the first shaft section to enter the accommodating cavity, and also extends along the internal axial direction of the second shaft section to introduce gas and is partially blocked at the joint position of the first internal channel, so that the mixing uniformity is improved, the aluminum pipe cannot be overburnt, and the requirement of copper-aluminum welding is met.

In some embodiments, a first gap 27 is formed between the outer periphery of the second shaft section 22 and the inner wall of the outer sleeve 1, a communication hole 28 is opened on the second shaft section 22, one end of the communication hole 28 is communicated with the second internal channel 24, and the other end is communicated with the first gap 27, so that the gas in the second internal channel 24 can be conducted to the first gap 27 through the communication hole 28. The invention also can enable the gas in the second internal channel to enter the first gap through the communicating hole by arranging the communicating hole at the second internal channel, reduce the flowing speed of the gas flow, further improve the mixing uniformity of the gas and the air mixture, further solve the problem of overburning of the aluminum pipe and solve the problem of high welding difficulty of the copper-aluminum connecting pipe.

In some embodiments, the communication hole 28 extends in a radial direction of the second shaft section 22; and/or the communication holes 28 are multiple, and the communication holes 28 are arranged at intervals along the circumferential direction of the second shaft section 22. This is a further preferable configuration of the communication hole of the present invention, which extends in the radial direction and is capable of guiding the gas in the second internal passage in the radial direction into the first gap, and the flow rate is reduced by the communication hole to improve the mixing uniformity; the plurality of communication holes distributed at intervals along the circumferential direction can increase the flow rate of the spray to the first gap, increase the spray space and the spray flow rate, and further improve the uniform mixing degree.

In some embodiments, the outer diameter of the first shaft segment 21 is larger than the outer diameter of the second shaft segment 22 to form a second step 29 at the junction of the first shaft segment 21 and the second shaft segment 22, a second gap 210 is provided between the outer periphery of the first shaft segment 21 and the inner wall of the outer sleeve 1, the second step 29 can block the air flow flowing from the first gap 27 to the second gap 210, and the air flow reaching the second gap 210 can enter the accommodating cavity 10. The invention also can further block the flow of air current through the second step formed on the periphery of the first shaft section and the second shaft section, further improve the mixing uniformity of gas and air mixture, and further solve the problem of high welding difficulty of the copper-aluminum connecting pipe; the second clearance that forms between first shaft section and the overcoat can be with the air current that is blockked by the second step and get into in the air current leading-in to holding the chamber in the first clearance, because the flow area of second clearance is less than the flow area in first clearance, can further reduce the flow velocity of air current, improves the mixture degree of consistency of gas and air mixture, further solves the problem that the aluminum pipe is overburnt, solves the big problem of copper aluminium connecting pipe welding degree of difficulty.

In some embodiments, the inner core 2 further includes a third shaft segment 211, the third shaft segment 211 is connected to one axial end of the second shaft segment 22, such that the second shaft segment 22 is located between the first shaft segment 21 and the third shaft segment 211, a first external thread 212 is provided on the outer circumference of the third shaft segment 211, an internal thread 11 is provided on the inner wall of the outer sleeve 1 opposite to the third shaft segment 211, and the first external thread 212 and the internal thread 11 can be screwed to fix the inner core 2 and the outer sleeve 1. According to the invention, the outer wall of the third shaft section can be provided with the first external thread, and the inner wall of the outer sleeve opposite to the third shaft section is provided with the internal thread, so that the third shaft section and the outer sleeve form threaded fit, thereby effectively fixing part of the structural threads of the inner core to the inside of the outer sleeve.

In some embodiments, the inner core 2 further includes a fourth shaft section 213 and a fifth shaft section 214, the fifth shaft section 214 abuts on an end surface of one axial end of the outer sleeve 1, the fifth shaft section 214 is a hexahedral structure, an outer peripheral shape of a cross section thereof is a hexagon, the fourth shaft section 213 is located between the third shaft section 211 and the fifth shaft section 214, one end of the fourth shaft section 213 is connected to the third shaft section 211, the other end is connected to the fifth shaft section 214, and an outer peripheral wall of the fourth shaft section 213 is a circumferential surface. The fifth shaft section is of a hexahedral structure, so that the fifth shaft section is convenient to operate when being locked and assembled with the outer sleeve part, and the outer sleeve part is prevented from being locked and limited, so that the structure of the device realizes locking and sealing feasibility.

In some embodiments, the inner core 2 further comprises a sixth shaft section 215, one end of the sixth shaft section 215 is connected with the fifth shaft section 214, the other end is formed as an air inlet end 26, the mixture of air and gas can enter the second internal channel 24 through the air inlet end 26, a second external thread 216 is arranged on the outer peripheral wall of the sixth shaft section 215, and the second external thread 216 can be tightly connected with the welding gun. The welding device is characterized in that the outer wall of the sixth shaft section is provided with a second outer thread, so that the sixth shaft section can be effectively in threaded fastening connection with an external welding gun, the mixed gas of gas and air in the welding gun is effectively sprayed into an inner core of the welding device and further enters the outer sleeve, and finally the mixed gas is sprayed to a joint of two pipes made of different materials (such as a copper pipe and an aluminum pipe) through the outer sleeve, so that the mixing uniformity is improved, the aluminum pipe is prevented from being burnt, and the welding requirement is ensured.

In some embodiments, the aperture of the containing cavity 10 of the casing 1 is 10mm to 12mm, the portion of the casing 1 connected with the fifth shaft section 214 is also a head 12 configured in a hexahedral structure, and the outer periphery of the cross section of the head 12 is hexagonal in shape to match with the fifth shaft section 214 in a hexahedral structure.

The outer sleeve of the connecting pipe welding device is processed by stainless steel, the appearance of the outer sleeve is of a circular structure, the end 12 is of a hexagonal shape and is convenient to be matched with a wrench for operation when being locked, the inner circular hole diameter is 10mm-12mm, the end of the inner hole is provided with an internal thread structure and is mainly locked and assembled with the inner core thread.

In some embodiments, the first shaft section 21 is a cylindrical structure with a circumferential outer surface, and the second shaft section 22 is a cylindrical structure with a circumferential outer surface.

The inner core part is preferably machined by brass materials and mainly comprises 8 structures, firstly, a first shaft section 21 at the top of the inner core is of a circular structure and is connected with a second shaft section 22 in a step-shaped manner, a third shaft section 211 is provided with a first external thread and is mainly matched and locked with an external thread, a circular structure transition (namely a fourth shaft section 213) is adopted between the third shaft section 211 and a fifth shaft section 214, the fifth shaft section 214 is of a hexahedral structure and is convenient to operate when being locked and assembled with the external sleeve part, and the external sleeve part is prevented from being locked and limited at the same time, so that the structure of the device realizes the locking sealing feasibility; the aperture of the first internal channel 23 is required to be smaller than that of the second internal channel 24, and the first internal channel 23 and the second internal channel 24 jointly penetrate through the whole inner core device to form a gas flow channel; the communication holes 28 are formed in the radial direction of the cylindrical structure, and the circular holes are uniformly distributed on the surface of the cylindrical structure; the outer wall of the sixth shaft section 215 is an external thread structure, and is mainly fastened and connected with an external welding gun.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention. The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, it is possible to make various improvements and modifications without departing from the technical principle of the present invention, and those improvements and modifications should be also considered as the protection scope of the present invention.

Claims

1. The utility model provides a connecting pipe welding set which characterized in that: the method comprises the following steps:

an outer sleeve (1) and an inner core (2), wherein the inner part of the outer sleeve (1) is provided with a containing cavity (10), the inner core (2) comprises a first shaft section (21) and a second shaft section (22) which are connected, the first shaft section (21) and the second shaft section (22) are both positioned in the containing cavity (10), the inner part of the inner core (2) is provided with a first internal channel (23) and a second internal channel (24), at least part of the first internal channel (23) is positioned in the first shaft section (21), at least part of the second internal channel (24) is positioned in the second shaft section (22), the first internal channel (23) is communicated with the second internal channel (24), the aperture of the first internal channel (23) is smaller than that of the second internal channel (24), and a first step (25) is formed at the joint of the first internal channel and the second internal channel (24), the gas flow can be blocked by the first step (25) when flowing from the second inner passage (24) to the first inner passage (23), and the welding device can weld connecting pipes of different materials.

2. The connecting pipe welding apparatus according to claim 1, wherein:

one end of the first internal channel (23) is located at a position where the first shaft section (21) and the second shaft section (22) are connected and is communicated with the second internal channel (24), the other end of the first internal channel (23) extends to be communicated with the accommodating cavity (10), one end of the second internal channel (24) is located at a position where the first shaft section (21) and the second shaft section (22) are connected and the other end of the second internal channel extends to the air inlet end (26) of the inner core (2).

3. The connecting pipe welding apparatus according to claim 2, wherein:

the first internal channel (23) is located in the first shaft section (21) and extends along the axial direction of the inner core (2), one end of the first internal channel (23) is located at one axial end of the first shaft section (21), the other end of the first internal channel is located at the other axial end of the first shaft section (21), and part of the second internal channel (24) is located in the second shaft section (22) and also extends along the axial direction of the inner core (2).

4. The connecting pipe welding apparatus according to claim 1, wherein:

a first gap (27) is formed between the periphery of the second shaft section (22) and the inner wall of the outer sleeve (1), a communication hole (28) is formed in the second shaft section (22), one end of the communication hole (28) is communicated with the second internal channel (24), the other end of the communication hole is communicated with the first gap (27), and gas in the second internal channel (24) can be conducted into the first gap (27) through the communication hole (28).

5. The connecting pipe welding apparatus according to claim 4, wherein:

the communication hole (28) extends in a radial direction of the second shaft section (22); and/or the communication holes (28) are multiple, and the communication holes (28) are arranged at intervals along the circumferential direction of the second shaft section (22).

6. The connecting pipe welding apparatus according to claim 4, wherein:

the outer diameter of the first shaft section (21) is larger than that of the second shaft section (22) so as to form a second step (29) at the joint of the first shaft section (21) and the second shaft section (22), a second gap (210) is formed between the outer periphery of the first shaft section (21) and the inner wall of the outer sleeve (1), the air flow flowing from the first gap (27) to the second gap (210) can be blocked by the second step (29), and the air flow reaching the second gap (210) can enter the accommodating cavity (10).

7. The connecting pipe welding apparatus according to claim 1, wherein:

inner core (2) still include third shaft segment (211), third shaft segment (211) with the axial one end of second shaft segment (22) meets, makes second shaft segment (22) be located first shaft segment (21) with between third shaft segment (211), just be provided with first external screw thread (212) on the periphery of third shaft segment (211), overcoat (1) go up with be provided with on the inner wall that third shaft segment (211) is relative internal thread (11), first external screw thread (212) with internal thread (11) can screw-thread fit in order to be right inner core (2) with overcoat (1) is fixed.

8. The connecting tube welding apparatus according to claim 7, wherein:

inner core (2) still include fourth shaft part (213) and fifth shaft part (214), fifth shaft part (214) butt is in on the terminal surface of the axial one end of overcoat (1), just fifth shaft part (214) are the hexahedron structure, and the outer peripheral shape of its cross section is the hexagon, fourth shaft part (213) are located third shaft part (211) with between fifth shaft part (214), the one end of fourth shaft part (213) with third shaft part (211) meet, the other end with fifth shaft part (214) meet, just the periphery wall of fourth shaft part (213) is the periphery.

9. The connecting tube welding apparatus according to claim 8, wherein:

the inner core (2) further comprises a sixth shaft section (215), one end of the sixth shaft section (215) is connected with the fifth shaft section (214), the other end of the sixth shaft section is formed into an air inlet end (26), mixed gas of air and fuel gas can enter the second internal channel (24) through the air inlet end (26), second external threads (216) are arranged on the outer peripheral wall of the sixth shaft section (215), and the second external threads (216) can be fixedly connected with a welding gun.

10. The connecting tube welding apparatus according to claim 8, wherein:

the aperture of the accommodating cavity (10) of the outer sleeve (1) is 10-12 mm, the part of the outer sleeve (1) connected with the fifth shaft section (214) is also provided with a head (12) in a hexahedral structure, and the outer periphery of the cross section of the head (12) is hexagonal so as to be matched with the fifth shaft section (214) in the hexahedral structure.

11. The connecting pipe welding apparatus according to any one of claims 1 to 10, wherein:

the first shaft section (21) is of a cylindrical structure, the outer peripheral surface of the first shaft section is a circumferential surface, and the second shaft section (22) is of a cylindrical structure, and the outer peripheral surface of the second shaft section is a circumferential surface.

12. The connecting pipe welding apparatus according to any one of claims 1 to 11, wherein:

the connecting pipe made of different materials comprises a copper pipe and an aluminum pipe.