A pipeline all-position multi-torch grinding-free joint welding process and welding device

Abstract

The present invention provides a pipeline all-position multi-torch grinding-free joint welding process and a welding device, which belongs to the field of pipeline welding technology. In the pipeline all-position multi-torch grinding-free joint welding process, when welding the first pipeline and the second pipeline, the first welding trolley and the second welding trolley respectively move clockwise or counterclockwise along the circumference of the weld. A fixed length arc starting segment is provided at the top of the weld. The welding torch on the first welding trolley starts welding from one end of the arc starting segment and rotates clockwise to complete the welding of the entire arc starting segment. After the first welding trolley completes the welding of the arc starting segment, the second welding trolley starts welding from the other end of the arc starting segment. By adopting the design of the arc starting segment and adjusting the welding process on the first welding trolley and the second welding trolley, the protrusion of the arc starting segment and the arc starting point can be avoided, the grinding of the operator during the welding process can be reduced, and the welding quality can be improved while improving the welding efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of pipeline welding, and in particular relates to a pipeline all-position multi-torch grinding-free joint welding process and a welding device. Background Art

[0002] During the automatic welding process of pipelines, a welding machine is required to perform multi-layer welding. In order to improve the welding efficiency of pipelines, multiple welding torches are usually used for synchronous welding. During the welding process of pipelines, the joints at the arc starting point often protrude from the welding part. If it is not processed during subsequent welding, defects will occur. The current treatment method usually uses manual grinding to grind off the arc starting point to eliminate potential defects. On the one hand, there are large differences in grinding quality, which affects the stability of welding quality. Therefore, during the automatic welding process, when the same section needs to be repeatedly filled and welded, in order to avoid the protruding parts affecting the welding quality, the protruding parts on the arc starting section of the previous welding need to be polished in advance before the subsequent filling welding can be performed. Continuous welding operations cannot be achieved. Therefore, during pipeline welding, the arc starting section needs to be repeatedly manually polished during the pipeline welding process, which affects the overall welding efficiency of the pipeline. Summary of the Invention

[0003] The embodiment of the present invention provides a pipeline all-position multi-torch grinding-free joint welding process, which aims to solve the problem in the prior art that the arc starting point of the pipeline needs to be ground during welding, which affects the welding quality and welding efficiency.

[0004] To achieve the above object, the technical solution adopted by the present invention is to provide a pipeline all-position multi-torch grinding-free joint welding process, comprising:

[0005] S1 defines two pipes to be welded as a first pipe and a second pipe, a first welding carriage for welding along the circumference of the first pipe is installed on the first pipe, and a second welding carriage for welding along the circumference of the second pipe is installed on the second pipe;

[0006] S2. A certain length of the top of the weld between the first pipe and the second pipe is set as the arc starting section, with the highest point of the weld located in the middle of the arc starting section;

[0007] S3. The first welding carriage starts welding from one end of the arc-starting segment and moves clockwise to weld. After the arc-starting segment is welded, the second welding carriage starts welding from the other end of the arc-starting segment and moves counterclockwise to weld. The welding thickness of the arc-starting segment is less than that of the remaining sections.

[0008] S4. When the first welding carriage and the second welding carriage are welded to the lowest point of the weld, stop welding and move to the top of the weld to repeat the welding steps of S3 until the welding is completed.

[0009] In a possible implementation, during arc starting section welding, the moving speed of the first welding carriage and the second welding carriage on the first pipe and the second pipe is greater than the moving speed of other welding parts.

[0010] In combination with the first aspect, the present invention also provides a welding device, comprising at least two first welding carriages installed on the first pipe, and at least two second welding carriages installed on the second pipe, the two first welding carriages weld the welds in sequence along a clockwise direction, and the two second welding carriages weld the welds in sequence along a counterclockwise direction.

[0011] In a possible implementation, at least two welding torches are installed on the first welding carriage and the second welding carriage, and both welding torches adopt a consumable electrode welding process.

[0012] In a possible implementation, the first welding carriage and the second welding carriage have the same structure, and the first welding carriage includes:

[0013] body;

[0014] A swing arm has one end mounted on the vehicle body and a welding torch mounted on the other end. When the vehicle body moves to the top of the weld, the swing arm has the freedom to adjust along the pitch angle on the vehicle body.

[0015] In one possible implementation, a storage arm is hingedly provided at one end of the swing arm away from the vehicle body, a hinge axis of the storage arm on the swing arm is arranged parallel to the hinge axis of the swing arm on the vehicle body, and the welding torch is mounted on the storage arm.

[0016] In a possible implementation, the vehicle body is further provided with a pushing component for driving the swing arm to move back and forth along the axis of the first pipe or the second pipe.

[0017] In a possible implementation, the pushing component includes:

[0018] A mounting seat, slidably arranged on the vehicle body, and the swing arm is hingedly arranged on the mounting seat;

[0019] A threaded sleeve, fixedly mounted on the mounting seat;

[0020] A lead screw, threadedly connected to the threaded sleeve and rotatably arranged on the vehicle body;

[0021] A driving member is mounted on the vehicle body, and a driving end of the driving member is transmission-connected to the lead screw for driving the lead screw to rotate.

[0022] In a possible implementation, there are two first welding carriages, and when the welding torch on one of the first welding carriages is located at the welding starting point, the welding torch on the other first welding carriage is located at the welding end point.

[0023] In one possible implementation, the second welding trolley and the first welding trolley are respectively installed alternately on the first pipe and the second pipe along the circumference of the weld, and the distance between the welding torch on the first welding trolley and the welding torch on the second welding trolley is not less than the length of the arc starting section.

[0024] Compared to the prior art, the solution shown in the embodiment of the present application is characterized by installing a first welding carriage and a second welding carriage on the first and second pipes, respectively, when welding the first and second pipes. The first and second welding carriages move clockwise or counterclockwise, respectively, along the circumference of the weld. A starting arc segment of a fixed length is provided at the very top of the weld. When welding the first and second pipes, the welding torch on the first welding carriage begins welding from one end of the starting arc segment and rotates clockwise to complete the welding of the entire starting arc segment. Subsequent welding is then performed according to the normal welding process until the lowest point of the weld is reached. After the first welding carriage completes the welding of the starting arc segment, the second welding carriage begins welding from the other end of the starting arc segment and rotates counterclockwise to complete the welding of the entire starting arc segment. Subsequent welding is then performed according to the normal welding process until the lowest point of the weld is reached. This reciprocating operation of the first and second welding carriages is repeated to finally complete the welding of the entire pipe. This application adopts the design of the arc starting section and adjusts the welding process on the first welding trolley and the second welding trolley, which can avoid the protrusion of the arc starting section and the arc starting point, reduce the operator's grinding during the welding process, improve the welding quality and improve the welding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the installation structure of the first welding carriage and the second welding carriage provided in the embodiment of the present invention Figure 1 ;

[0026] Figure 2 Schematic diagram of the installation structure of the first welding carriage and the second welding carriage provided in the embodiment of the present invention Figure 2 ;

[0027] Figure 3 A schematic structural diagram of a first welding carriage provided in an embodiment of the present invention;

[0028] Figure 4 A schematic diagram of the welding process provided by an embodiment of the present invention.

[0029] Description of reference numerals:

[0030] 1. First pipeline; 2. Second pipeline; 3. First welding carriage; 31. Carriage; 32. Swing arm; 33. Storage arm; 4. Second welding carriage; 5. Welding seam; 51. Arc starting section; 6. Pushing assembly; 61. Mounting seat; 62. Threaded sleeve; 63. Lead screw; 64. Driving part. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] Please also refer to Figures 1 to 4 The present invention provides a pipeline all-position multi-torch grinding-free joint welding process. The pipeline all-position multi-torch grinding-free joint welding process includes the following steps:

[0033] S1 defines two pipes to be welded as a first pipe 1 and a second pipe 2, a first welding carriage 3 for welding along the circumference of the first pipe 1 is installed on the first pipe 1, and a second welding carriage 4 for welding along the circumference of the second pipe 2 is installed on the second pipe 2;

[0034] S2. A certain length of the top of the weld seam 5 of the first pipe 1 and the second pipe 2 is set as the arc starting section 51, and the highest point of the weld seam 5 is located in the middle of the arc starting section 51;

[0035] S3. The first welding carriage 3 starts welding from one end of the arc-starting segment 51 and moves clockwise to weld. After the arc-starting segment 51 is welded, the second welding carriage 4 starts welding from the other end of the arc-starting segment 51 and moves counterclockwise to weld. The welding thickness of the arc-starting segment 51 is less than that of the remaining sections.

[0036] S4. When the first welding carriage 3 and the second welding carriage 4 are welded to the lowest point of the weld seam 5, stop welding and move to the top of the weld seam 5 to repeat the welding steps of S3 until the welding is completed.

[0037] Compared with the prior art, the pipeline all-position multi-torch grinding-free joint welding process provided in this embodiment is characterized by installing a first welding carriage 3 and a second welding carriage 4 on the first pipeline 1 and the second pipeline 2, respectively, when welding the first pipeline 1 and the second pipeline 2. The first welding carriage 3 and the second welding carriage 4 move clockwise or counterclockwise along the circumference of the weld 5, respectively. A fixed-length arc-starting section 51 is provided at the top of the weld 5. When welding the first pipeline 1 and the second pipeline 2, the welding torch on the first welding carriage 3 starts welding from one end of the arc-starting section 51 and rotates clockwise to complete the welding of the entire arc-starting section 51. Subsequent welding is then performed according to the normal welding process until the weld is welded to the lowest point of the weld 5. After the first welding trolley 3 completes welding the arc-starting section 51, the second welding trolley 4 starts welding from the other end of the arc-starting section 51 and rotates counterclockwise to complete the welding of the entire arc-starting section 51. Then, subsequent welding is performed according to the normal welding process until the lowest point of the weld 5 is reached. The reciprocating operation of the first welding trolley 3 and the second welding trolley 4 is repeated to finally complete the overall welding of the pipeline. In this application, by adopting the design of the arc-starting section 51 and adjusting the welding process on the first welding trolley 3 and the second welding trolley 4, it is possible to avoid the arc-starting section 51 and the arc-starting point from protruding, reduce the operator's grinding during the welding process, improve welding quality, and improve welding efficiency.

[0038] Specifically, in this embodiment, during the welding of weld seam 5, the welding torch on the first welding carriage 3 performs the initial welding on the arc starting segment 51. Furthermore, the second welding carriage 4 is located clockwise to one side of the first welding carriage 3. Before the first welding carriage 3 passes the second welding carriage 4, the welding torch on the second welding carriage 4 is retracted to avoid interference with the welding torch on the first welding carriage 3. After the first welding carriage 3 passes the second welding carriage 4, the welding torch on the second welding carriage 4 flips to the working position, and welding begins. The first welding carriage 3 and the second welding carriage 4 each weld half of the weld seam 5, completing the entire weld seam 5.

[0039] In some embodiments, the following process can be used when welding the arc starting section 51, see Figure 1 、 Figure 4 During welding in the arc starting section 51, the first and second welding carriages 3 and 4 move faster on the first and second pipes 1 and 2 than on the remaining welded sections. The same consumable electrode welding process is used for welding in the arc starting section 51 as for the other sections. However, the weld thickness in the arc starting section 51 can be reduced by increasing the movement speeds of the first and second welding carriages 3 and 4, as well as the wire feed speed and welding current. This ensures that the weld thickness in the arc starting section 51 is smaller than that in the normal welding sections.

[0040] Preferably, the welding thickness of the arc starting segment 51 is reduced to 1 / 2 of the normal welding thickness by controlling the movement speed of the first welding carriage 3 and the second welding carriage 4 and increasing the wire feed speed and welding current. In this application, during welding, the arc starting segment 51 can be repeatedly welded by the welding torches on the first welding carriage 3 and the second welding carriage 4. This prevents protrusion at the arc starting position. Furthermore, during a single welding cycle, the arc starting segment 51 is welded by both the first welding carriage 3 and the second welding carriage 4, ensuring that its thickness is the same as that of other parts. This avoids the need for filling the arc starting segment 51 later, allowing the arc starting segment 51 to be welded synchronously with other parts.

[0041] Specifically, in this embodiment, the first welding carriage 3 and the second welding carriage 4 both move on the first pipeline 1 and the second pipeline 2 along a top-down welding manner.

[0042] Please also refer to Figure 1 、 Figure 2 , the welding device provided by the present invention will now be described. The welding device includes at least two first welding carriages 3 installed on the first pipeline 1, and at least two second welding carriages 4 installed on the second pipeline 2. The two first welding carriages 3 weld the weld seam 5 in sequence along the clockwise direction, and the two second welding carriages 4 weld the weld seam 5 in sequence along the counterclockwise direction. Both first welding carriages weld the weld seam 5 in sequence along the clockwise direction, and the welding torches on the multiple first welding carriages 3 all start welding from the starting point of the arc starting section 51, thereby improving the welding efficiency. The welding torches on the multiple second welding carriages 4 all start welding from the starting point at the other end of the arc starting section 51. The welding torches on the arc starting section 51 and the first welding carriage 3 are welded alternately to improve the welding efficiency of the pipeline.

[0043] Specifically, in this embodiment, there are two first welding carriages 3, which are arranged adjacent to each other. When the front first welding carriage 3 moves clockwise to weld, the rear first welding carriage 3 moves clockwise along with the front first welding carriage 3 to weld. When the rear first welding carriage 3 reaches the lowest point of the weld seam 5, the two first welding carriages 3 stop welding and return clockwise or counterclockwise to the top of the weld seam 5, repeating the welding process in step S3. There are two second welding carriages 4, which are arranged adjacent to each other. When the front second welding carriage 4 moves counterclockwise to weld, the rear second welding carriage 4 moves counterclockwise along with the front second welding carriage 4 to weld. When the rear second welding carriage 4 reaches the lowest point of the weld seam 5, the two second welding carriages 4 stop welding and return clockwise or counterclockwise to the top of the weld seam 5, repeating the welding process in step S3.

[0044] Optionally, in this embodiment, there are two first welding carriages 3, which are spaced apart circumferentially along the weld seam 5. When the front first welding carriage 3 moves to the point where the welding torch is at the bottom of the weld seam 5, the welding torch on the rear first welding carriage 3 is at the top of the weld seam 5. Furthermore, the two first welding carriages 3 always move in a clockwise direction. This allows the two first welding carriages 3 to weld alternately. There are two second welding carriages 4, which are spaced apart circumferentially along the weld seam 5. When the front second welding carriage 4 moves to the point where the welding torch is at the bottom of the weld seam 5, the welding torch on the rear second welding carriage 4 is at the top of the weld seam 5. Furthermore, the two second welding carriages 4 always move counterclockwise, allowing the two second welding carriages 4 to weld alternately.

[0045] In some embodiments, the first welding carriage 3 and the second welding carriage 4 can be used as follows: Figure 1 、 Figure 2 and Figure 3 See also Figure 1 、 Figure 2 and Figure 3 The first welding carriage 3 and the second welding carriage 4 are each equipped with at least two welding torches, both of which utilize a consumable electrode welding process. Two welding torches are mounted on each of the first welding carriage 3 and the second welding carriage 4, spaced apart along the length of the weld seam 5. When the first welding carriage 3 makes a single rotation, the two torches on the first welding carriage 3 can complete two passes of welding. The structure of the second welding carriage 4 is identical to that of the first welding carriage 3. The presence of two welding torches effectively improves pipeline welding efficiency.

[0046] Preferably, in this embodiment, both welding torches on the first welding carriage 3 use the same consumable electrode welding process. Combined with the welding method of the arc starting segment 51, the same welding method can be used. By changing the wire feed speed and welding current during the welding process, the welding thickness of the arc starting segment 51 can be reduced, thereby ensuring that both welding torches on the first welding carriage 3 can complete the entire weld, thereby improving the overall welding efficiency of the weld seam 5.

[0047] Preferably, in this embodiment, argon, carbon dioxide, and nitrogen are used during the welding process of the weld 5. This can reduce the oxidation reaction of the metal in the molten pool caused by oxygen generated by the decomposition of carbon dioxide at high temperature, and reduce the formation of oxide impurities in the cold wind.

[0048] In some embodiments, the first welding carriage 3 may be used as follows: Figure 3 The structure shown. Figure 3The first welding carriage 3 and the second welding carriage 4 employ the same structure, comprising a carriage body 31 and a swing arm 32. One end of the swing arm 32 is mounted on the carriage body 31, and the other end is mounted with a welding torch. When the carriage body 31 moves to the top of the weld seam 5, the swing arm 32 is freely adjustable along the pitch angle on the carriage body 31. Guide rails are mounted on both the first and second pipelines 1 and 2 for guiding the movement of the first and second welding carriages 3 and 4. The carriage body 31 of the first welding carriage 3 is mounted on the guide rails, and the swing arm 32 is swingably mounted on the carriage body 31. The welding torch is mounted on the swing arm 32. When the first and second welding carriages 3 and 4 move relative to each other and meet, the swing arm 32 on the first or second welding carriage 3 or 4 can drive the welding torch to tilt upward, avoiding the welding process and preventing interference between the first or second welding carriages 3 and 4 during the meeting.

[0049] Specifically, in this embodiment, one end of the swing arm 32 is hingedly set on the vehicle body 31, and a motor for driving the swing arm 32 to swing is also installed on the vehicle body 31. The motor can drive the swing arm 32 to swing to achieve switching between the working state and the storage state.

[0050] In some embodiments, the swing arm 32 may be configured as follows: Figure 3 The structure shown. Figure 3 The end of the swing arm 32 away from the vehicle body 31 is further hingedly provided with a storage arm 33. The hinge axis of the storage arm 33 on the swing arm 32 is arranged parallel to the hinge axis of the swing arm 32 on the vehicle body 31, and the welding torch is mounted on the storage arm 33. A storage arm 33 is further hingedly provided at the end of the swing arm 32 away from the vehicle body 31, and the welding torch is mounted on the storage arm 33. For convenience, the welding torch can be further stored on the vehicle body 31 to effectively avoid it. At the same time, the storage arm 33 can be used to adjust the tilt angle of the welding torch during the welding process to ensure effective welding quality. The position of the swing arm 32 and the storage arm 33 can be adjusted according to the distance between the vehicle body 31 and the weld seam 5, so that the welding torch and the weld seam 5 maintain a stable welding angle.

[0051] In some embodiments, the vehicle body 31 may be formed as follows: Figure 3 The structure shown. Figure 3 The vehicle body 31 is also provided with a driving assembly 6 for driving the swing arm 32 to reciprocate along the axis of the first pipe 1 or the second pipe 2. When the vehicle body 31 is mounted on the first pipe 1 or the second pipe 2, the mounting end of the swing arm 32 on the vehicle body 31 can slide along the axis of the first pipe 1 or the second pipe 2. As the swing arm 32 slides back and forth, it drives the welding torch to reciprocate, completing the welding of the weld seam 5.

[0052] In some embodiments, the pushing component 6 can be used as follows Figure 3 The structure shown. Figure 3 The pushing assembly 6 includes a mounting seat 61, a threaded sleeve 62, a lead screw 63, and a driving member 64. The mounting seat 61 is slidably mounted on the vehicle body 31, and the swing arm 32 is hingedly mounted on the mounting seat 61; the threaded sleeve 62 is fixedly mounted on the mounting seat 61; the lead screw 63 is threadedly connected to the threaded sleeve 62 and is rotatably mounted on the vehicle body 31; and the driving member 64 is mounted on the vehicle body 31. The driving end of the driving member 64 is in transmission connection with the lead screw 63, and is used to drive the lead screw 63 to rotate. The driving member 64 is a motor, and the driving end of the driving member 64 is in transmission connection with the lead screw 63. When the lead screw 63 rotates, the lead screw 63 can drive the threaded sleeve 62 to move, thereby driving the mounting seat 61 to reciprocate.

[0053] Preferably, in this embodiment, after the vehicle body 31 is mounted on the first pipeline 1 or the second pipeline 2 , the welding torch on the mounting seat 61 can be adjusted to move to the weld 5 by moving the mounting seat 61 .

[0054] In some embodiments, the first welding carriage 3 and the second welding carriage 4 can both be used as follows: Figure 2 The structure shown. Figure 2 There are two first welding carriages 3, and when the welding torch on one of the first welding carriages 3 is at the welding starting point, the welding torch on the other first welding carriage 3 is at the welding end point. There are two first welding carriages 3, and both first welding carriages 3 are arranged on the first pipe 1 in a clockwise rotation. When the welding torch on one of the first welding carriages 3 is at the highest point of the weld seam 5, the welding torch on the other first welding carriage 3 is at the lowest point of the weld seam 5. After the welding torch on one of the first welding carriages 3 completes welding, the welding on the other first welding carriage 3 has already started from the top of the weld seam 5, allowing the two first welding carriages 3 to be connected sequentially during the welding process, thereby improving welding efficiency.

[0055] Specifically, in this embodiment, the number of the second welding carriages 4 is two, and the welding method of the two second welding carriages 4 is the same as the welding method of the first welding carriage 3 .

[0056] Preferably, in this embodiment, the highest point of the weld seam 5 is located in the middle of the arc starting section 51. When the welding torch on one of the first welding carriages 3 is at the lowest point of the weld seam 5, the welding on the other first welding carriage 3 has already started welding in the arc starting section 51 and has welded to the middle of the arc starting section 51 at the highest point of the weld seam 5. The arc starting sections 51 of the welding areas of the first welding carriage 3 and the second welding carriage 4 overlap.

[0057] In some embodiments, the first welding carriage 3 and the second welding carriage 4 can be used as follows: Figure 2 The structure shown. Figure 2 , the second welding trolley 4 and the first welding trolley 3 are respectively installed on the first pipe 1 and the second pipe 2 in an alternating manner along the circumference of the weld seam 5, and the distance between the welding torch on the first welding trolley 3 and the welding torch on the second welding trolley 4 is not less than the length of the arc starting segment 51. During the initial welding, the first welding trolley 3 and the second welding trolley 4 are arranged in an alternating manner. And the second welding trolley 4 is located on the clockwise side of the first welding trolley 3 along the circumference of the weld seam 5. The first welding trolley 3 starts welding first, and the welding gun on the second welding trolley 4 is in an avoidance storage state. After the welding torch on the first welding trolley 3 completes welding the arc starting segment 51, the welding torch on the second welding trolley 4 swings to the working state and starts welding from the other end point of the arc starting segment 51. The cross welding of the first welding trolley 3 and the second welding trolley 4 effectively improves the welding efficiency of the pipeline.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pipeline all-position multi-torch grinding-free joint welding process, characterized in that: include: S1. Two pipes to be welded are defined as a first pipe (1) and a second pipe (2), a first welding carriage (3) for welding along the circumference of the first pipe (1) is installed on the first pipe (1), and a second welding carriage (4) for welding along the circumference of the second pipe (2) is installed on the second pipe (2); S2. A certain length of the top of the weld (5) between the first pipe (1) and the second pipe (2) is set as the arc starting section (51), and the highest point of the weld (5) is located in the middle of the arc starting section (51); S3. The first welding trolley (3) starts welding from one end of the arc starting section (51) and moves clockwise to weld. After the arc starting section (51) is welded, the second welding trolley (4) starts welding from the other end of the arc starting section (51) and moves counterclockwise to weld. The first welding trolley (3) and the second welding trolley (4) both include a body and a swing arm hingedly arranged on the body. When the first welding trolley and the second welding trolley move relative to each other until they meet, the swing arm on the first welding trolley or the second welding trolley can drive the welding torch to flip upward to avoid the welding in progress. S4. When the first welding trolley (3) and the second welding trolley (4) are welded to the lowest point of the weld seam (5), stop welding and move to the top of the weld seam (5) to repeat the welding steps of S3 until the welding is completed; When welding the arc starting section (51), the moving speed of the first welding carriage (3) and the second welding carriage (4) on the first pipe (1) and the second pipe (2) is greater than the moving speed of the remaining welding parts; By controlling the moving speeds of the first welding carriage (3) and the second welding carriage (4) and increasing the wire feeding speed and welding current, the welding thickness of the arc starting section (51) is made 1 / 2 of the normal welding thickness; During a single welding cycle, the arc starting section (51) is double-welded by the first welding carriage (3) and the second welding carriage (4), so that the thickness of the arc starting section (51) is the same as that of other parts.

2. A welding device, using the pipeline all-position multi-torch grinding-free joint welding process according to claim 1, characterized in that: The invention comprises two first welding carriages (3) installed on the first pipeline (1), and two second welding carriages (4) installed on the second pipeline (2); the two first welding carriages (3) weld the weld seam (5) in sequence along a clockwise direction, and the two second welding carriages (4) weld the weld seam (5) in sequence along a counterclockwise direction.

3. The welding device according to claim 2, wherein: The first welding carriage (3) and the second welding carriage (4) are both equipped with two welding torches for welding, and both welding torches adopt a consumable electrode welding process.

4. The welding device according to claim 2, wherein: The first welding carriage (3) and the second welding carriage (4) have the same structure, and the first welding carriage (3) comprises: Vehicle body (31); A swing arm (32) is mounted on the vehicle body (31) at one end and a welding torch is mounted on the other end. When the vehicle body (31) moves to the top of the weld seam (5), the swing arm (32) has the freedom to adjust along the pitch angle on the vehicle body (31).

5. The welding device according to claim 4, wherein: A storage arm (33) is hingedly provided at one end of the swing arm (32) away from the vehicle body (31); a hinge axis of the storage arm (33) on the swing arm (32) is arranged parallel to a hinge axis of the swing arm (32) on the vehicle body (31); and the welding torch is mounted on the storage arm (33).

6. The welding device according to claim 5, wherein: The vehicle body (31) is also provided with a pushing component (6) for driving the swing arm (32) to move back and forth along the axis of the first pipe (1) or the second pipe (2).

7. The welding device according to claim 6, wherein: The pushing component (6) comprises: A mounting seat (61) is slidably arranged on the vehicle body (31), and the swing arm (32) is hingedly arranged on the mounting seat (61); A threaded sleeve (62) is fixedly mounted on the mounting seat (61); A lead screw (63) is threadedly connected to the threaded sleeve (62) and is rotatably arranged on the vehicle body (31); A driving member (64) is mounted on the vehicle body (31), and a driving end of the driving member (64) is in transmission connection with the lead screw (63) for driving the lead screw (63) to rotate.

8. The welding device according to claim 2, wherein: There are two first welding carriages (3), and when the welding torch on one of the first welding carriages (3) is located at the welding starting point, the welding torch on the other first welding carriage (3) is located at the welding end point.

9. The welding device according to claim 8, wherein: The second welding trolley (4) and the first welding trolley (3) are respectively installed alternately on the first pipe (1) and the second pipe (2) along the circumference of the weld seam (5), and the distance between the welding torch on the first welding trolley (3) and the welding torch on the second welding trolley (4) is not less than the length of the arc starting section (51).

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