Root cleaning-free welding process for butt welds

Abstract

The present application relates to the field of welding technology, and in particular to a butt weld root cleaning-free welding process, comprising: S1, completing the blanking and forming of steel plates, and opening two-sided symmetrical grooves at the weld positions where two plates to be welded are connected, and a blunt edge is provided between the two grooves of the lower plate to be welded; S2, grinding and removing rust from the weld areas of the two plates to be welded with a grinding wheel machine; S3, assembling and positioning welding the two plates to be welded; S4, preheating the weld area; S5, performing gas shielded base welding on both sides of the weld in the same direction, and using an arc in the form of droplet transition or jet transition during welding; S6, performing gas shielded filling and cap welding on both sides of the weld in the same direction, and using an arc in the form of pulsed droplet transition during welding. It can be seen that the present method can achieve full penetration welding without root cleaning, and can adapt to a wider range of gap variation tolerances, so that the root cleaning process can be effectively promoted.

Description

Technical Field

[0001] The present application relates to the field of welding technology, and in particular to a butt weld root cleaning-free welding process. Background Art

[0002] At present, the root cleaning-free horizontal welding process for butt welds has very strict assembly requirements and can only adapt to a maximum root gap variation tolerance of 0 to 1 mm. Therefore, its application range is very narrow, especially for the welding and manufacturing of large structural parts and thick plates. The automated root cleaning-free horizontal welding process is almost not applicable. Summary of the Invention

[0003] The purpose of this application is to provide a butt weld root cleaning-free welding process, which to a certain extent solves the technical problem that the existing butt weld root cleaning-free horizontal welding process has very strict assembly requirements and can only adapt to a maximum root gap variation tolerance of 0 to 1 mm. Therefore, its application range is very narrow, especially for the welding and manufacturing of large structural parts and thick plates, the automated root cleaning-free horizontal welding process is almost not applicable.

[0004] This application provides a butt weld root cleaning-free welding process, comprising the following steps:

[0005] S1. Complete the blanking and forming of the steel plate to form two plates to be welded, and open bilaterally symmetrical grooves at the weld positions where the two plates to be welded meet, with a blunt edge provided between the grooves on both sides of the lower plate to be welded;

[0006] S2. Grind and remove rust from the welding areas of the two plates to be welded using a grinding machine;

[0007] S3. Assemble and position weld the two plates to be welded, ensuring that the butt weld is located in the horizontal welding position;

[0008] S4. Preheating the weld area formed between the two plates to be welded before welding;

[0009] S5. Perform gas shielded backing welding on both sides of the weld simultaneously and in the same direction, and use droplet transfer or jet transfer arc during welding;

[0010] S6. Gas shielded filling and cap welding are performed simultaneously and in the same direction on both sides of the weld, and pulse droplet transfer arc is used during welding.

[0011] In the above technical solution, further, in step S1, the thickness of the blunt edge between the grooves on both sides of the lower plate to be welded is b, and 6mm≤b≤8mm.

[0012] In any of the above technical solutions, further, in step S1, the thickness of the blunt edge between the grooves on both sides of the upper plate to be welded is a, and 0mm≤a≤2mm.

[0013] In any of the above technical solutions, further, in step S1, when 20mm≤t<80mm, 0mm≤a≤2mm, 6mm≤b≤8mm; when t≥80mm, 1mm≤a≤2mm, 6mm≤b≤8mm.

[0014] In any of the above technical solutions, further, in step S3, the positioning weld is ground before welding to remove welding defects, and the end is ground to form a transition slope, and the error tolerance of the assembly weld is ensured to be 0 to 3 mm, and its root gap tolerance is 0 to 4 mm.

[0015] In any of the above technical solutions, further, in step S5, during the bottom welding, the front welding gun does not swing, the welding wire end of the front welding gun points to the lower blunt edge line, the angle between the front welding gun and the horizontal plane is 8 to 10°, the welding current of the front welding gun is 240-280A, the welding voltage of the front welding gun is 27-30V, and the welding speed of the front welding gun is adjusted in real time according to the size of the root gap of the weld to ensure that the bottom welding does not burn through.

[0016] In any of the above technical solutions, further, in step S5, when the root gap tolerance of the weld is 0-2 mm, the welding speed of the front welding gun is 300 mm / min; when the root gap tolerance of the weld is 2-3 mm, the welding speed of the front welding gun is 250-300 mm / min; when the root gap tolerance of the weld is 3-4 mm, the welding speed of the front welding gun is 190-250 mm / min.

[0017] In any of the above technical solutions, further, during the bottom welding process, the front welding gun adjusts the welding speed in real time according to the size of the weld, and the other welding parameters remain unchanged.

[0018] In any of the above technical solutions, further, in step S5, during the bottom welding, the rear welding gun does not swing, the welding wire end of the rear welding gun points to the center of the weld, the welding speed of the rear welding gun is consistent with the welding speed of the front welding gun, and the welding current and welding voltage are adjusted in real time according to the size of the root gap of the weld to ensure that the bottom weld of the rear gun is formed without sagging.

[0019] In any of the above technical solutions, further, in step S5, when the root gap tolerance of the weld is 0-2mm, the welding current of the rear welding gun is 300-320A, and the welding voltage of the rear welding gun is 30-33V; when the root gap tolerance of the weld is 2-3mm, the welding current of the rear welding gun is 260-300A, and the welding voltage of the rear welding gun is 28-31V; when the root gap tolerance of the weld is 3-4mm, the welding current of the rear welding gun is 220-260A, and the welding voltage of the rear welding gun is 24-28V.

[0020] In any of the above technical solutions, further, during the bottom welding process, the rear welding gun adjusts the wire feeding speed in real time according to the size of the weld, controls the welding current and welding voltage by the wire feeding speed, and the other welding parameters remain unchanged.

[0021] In any of the above technical solutions, further, in step S6, during the filling and capping welding process, both welding guns adopt non-swinging multi-layer and multi-pass welding, the welding current of both welding guns is 220-280A, the welding voltage of both welding guns is 24-30V, and the welding speed of both welding guns is 300-320mm / min.

[0022] In any of the above technical solutions, further, the butt weld root cleaning-free welding process further includes the following steps: S7, performing appearance inspection, internal structure inspection and mechanical property inspection on the weld.

[0023] In any of the above technical solutions, further, in step S5 and step S6, the welding material is a solid welding wire that matches the base material, the welding wire diameter is 1.2 mm, and the shielding gas is 80% Ar+20% CO2.

[0024] In any of the above technical solutions, further, a welding robot is used to perform welding operations in step S5 and step S6.

[0025] In any of the above technical solutions, further, when the thickness of the steel plate is ≤80 mm, the grooves of the upper plate to be welded and the lower plate to be welded form an X-shaped groove, and the angle of the X-shaped groove is 60°; when the thickness of the steel plate is greater than 80 mm, the grooves of the upper plate to be welded and the lower plate to be welded form a U-shaped groove, and the angle of the U-shaped groove is 20°-25°.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The welding process for welds without root cleaning provided by the present application uses two welding guns and gas shielded welding to directly perform double-sided base welding and double-sided filling and covering. In the base welding process, the welding parameters of the rear gun are larger. When the assembly gap is 0-3mm, a jet transition arc is adopted, and the arc is strong and powerful. When the assembly gap is 3-4mm, a droplet transition arc is adopted, and the front gun has completed the back penetration, and the weld quality can be guaranteed. Therefore, the base welding can achieve effective penetration. During the filling and covering welding process, the arcs of the two welding guns both adopt a pulsed droplet transition form, with high welding efficiency, small spatter, and beautiful forming. The peak current of the pulsed arc can help effectively melt the interlayer oxide scale, avoiding the interlayer grinding and cleaning work, and the strong arc force can bring out impurities at the root of the base weld, ensuring the quality of the base weld.

[0028] In addition, for the two upper and lower plates to be welded, the welding gun is basically horizontal, and the arc during welding directly heats the grooves of the upper and lower plates to be welded, which can ensure effective penetration of the weld, and blunt edges are set between the grooves on the left and right sides of the upper and lower plates to be welded, and the lower blunt edge is made larger. The inclination angle of the front welding gun is 8 to 10 degrees, and the end of the welding wire points to the lower blunt edge line. During bottom welding, the arc heat is mainly used to heat the lower blunt edge, which can avoid the weld burn-through defect when the assembly gap exceeds 2 mm, thereby effectively improving the process tolerance.

[0029] It can be seen that when this method is used to achieve root welding, the arc heat is mainly used to heat the lower blunt edge, which can avoid the weld burn-through defect when the assembly gap exceeds 2 mm. Therefore, it can effectively improve the process tolerance and enable the root cleaning process to be effectively promoted. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A schematic diagram of the butt connection of two plates to be welded provided in an embodiment of the present application;

[0032] Figure 2 A schematic diagram of the structure of the welding seam and welding gun provided in an embodiment of the present application;

[0033] Figure 3 Another schematic diagram of the connection between two plates to be welded provided in an embodiment of the present application;

[0034] Figure 4Another schematic diagram of the connection between two plates to be welded provided in an embodiment of the present application.

[0035] Reference numerals:

[0036] 1-plate to be welded, 11-upper plate to be welded, 12-lower plate to be welded, 2-groove, 3-upper blunt edge, 4-lower blunt edge, 41-edge line, 5-weld center line, 6-front welding gun, 7-rear welding gun. DETAILED DESCRIPTION

[0037] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0038] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the present application.

[0039] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0040] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0042] Refer to the following Figures 1 to 4 The invention describes a butt weld root cleaning-free welding process according to some embodiments of the present application.

[0043] See also Figures 1 to 3As shown, an embodiment of the present application provides a butt weld root cleaning-free welding process, comprising the following steps:

[0044] S1. Complete the blanking and forming of the steel plate to form two panels 1 to be welded, and provide bilaterally symmetrical grooves 2 at the weld seams of the two panels 1 to be welded, with a blunt edge provided between the grooves 2 on both sides of the lower panel 12 to be welded;

[0045] S2, grinding and removing rust from the welding areas of the two plates 1 to be welded using a grinding machine;

[0046] S3, assembling and positioning welding the two plates 1 to be welded, ensuring that the butt weld is located in the horizontal welding position;

[0047] S4, preheating the area of ​​the weld formed between the two plates 1 to be welded before welding;

[0048] S5. Perform gas shielded backing welding on both sides of the weld simultaneously and in the same direction, and use droplet transfer or jet transfer arc during welding;

[0049] S6. Gas shielded filling and cap welding are performed simultaneously and in the same direction on both sides of the weld, and pulse droplet transfer arc is used during welding.

[0050] According to the above description, the welding process without root cleaning provided by the present application uses two welding guns and gas shielded welding to directly perform double-sided base welding and double-sided filling and covering. In the base welding process, the welding parameters of the rear gun are larger. When the assembly gap is 0-3mm, the jet transition arc is adopted, and the arc is strong and powerful. When the assembly gap is 3-4mm, the droplet transition arc is adopted, and the front gun has completed the back penetration, and the weld quality can be guaranteed. Therefore, the base can achieve effective penetration. During the filling and covering welding process, the arcs of the two welding guns adopt the pulsed droplet transition form, with high welding efficiency, small spatter, and beautiful forming. The peak current of the pulse arc can help to effectively melt the interlayer oxide scale, avoiding the interlayer grinding and cleaning work, and the strong arc force can bring out impurities at the root of the base weld, thereby ensuring the quality of the base weld.

[0051] In addition, for the two upper and lower plates to be welded, the welding gun is basically horizontal, and the arc during welding directly heats the grooves 2 of the upper and lower plates to be welded, which can ensure effective penetration of the weld, and blunt edges are set between the grooves 2 on the left and right sides of the upper and lower plates to be welded, and the lower blunt edge 4 is made larger. The inclination angle of the front welding gun 6 is 8 to 10 degrees, and the end of the welding wire points to the edge line 41 of the lower blunt edge 4. During bottom welding, the arc heat is mainly used to heat the lower blunt edge 4, which can avoid the weld burn-through defect when the assembly gap exceeds 2 mm, thereby effectively improving the process tolerance.

[0052] It can be seen that when the base welding can be achieved using this method, the arc heat is mainly used to heat the lower blunt edge 4, which can avoid the weld burn-through defect when the assembly gap exceeds 2 mm. Therefore, it can effectively improve the process tolerance and enable the root cleaning process to be effectively promoted.

[0053] In this embodiment, preferably, Figure 1 As shown, in step S1, the thickness of the blunt edge between the grooves 2 on both sides of the lower plate 12 to be welded, that is, the lower blunt edge 4, is b, and 6mm≤b≤8mm, thereby enabling this process to expand the range of the root gap tolerance c to 0~4mm. Of course, the length of the blunt edge of the grooves 2 on both sides of the lower plate 12 to be welded is not limited to this, and can also be selected according to actual needs.

[0054] In this embodiment, preferably, Figure 1 As shown, in step S1 , the length of the blunt edge between the grooves 2 on both sides of the upper plate 11 to be welded, ie, the upper blunt edge 3 , is a, and 0 mm ≤ a ≤ 2 mm.

[0055] According to the above description, no upper blunt edge 3 is provided between the grooves 2 on both sides of the upper plate 11 to be welded, or a smaller blunt edge can be provided. This is mainly for effective penetration, and the specific selection is based on actual needs.

[0056] In this embodiment, preferably, Figure 1 As shown, in step S1, when 20mm≤t<80mm, a double-sided symmetrical groove 2 is opened by flame cutting, and 0mm≤a≤2mm, 6mm≤b≤8mm; when t≥80mm, a double-sided symmetrical groove 2 is opened by machining, and 1mm≤a≤2mm, 6mm≤b≤8mm.

[0057] According to the above description, when the thickness of the steel plate exceeds 80 mm, the filling amount of the V-groove 2 becomes larger, the welding deformation increases, and the efficiency decreases. Therefore, the length of the blunt edge of the upper plate 11 to be welded is appropriately increased to reduce welding deformation and improve efficiency.

[0058] Furthermore, preferably, in step S1, when 20 mm ≤ t < 80 mm, flame cutting is used to create a double-sided symmetrical groove 2; when t ≥ 80 mm, machining is used to create a double-sided symmetrical groove 2. It can be seen that when the thickness of the steel plate is relatively small, flame cutting can be used, which is convenient to operate. When the thickness of the steel plate is relatively large, machining is more convenient, saves time and effort, and has higher work efficiency.

[0059] In this embodiment, preferably, Figure 1As shown, in step S3, the tack weld is ground before welding to remove welding defects and a transition slope is ground at the end. The assembly weld error tolerance is ensured to be 0-3 mm, and the root gap tolerance c is 0-4 mm. This process can accommodate a gap variation tolerance of 0-4 mm, and has a wider range of practical applications.

[0060] In this embodiment, preferably, the welding equipment in step S5 and step S6 is an industrial robot, especially a trackless all-position crawling welding robot of Boqing Technology, and the welding power supply is CLOOS-A500FG, which has a "rapidweld" or deep penetration welding mode, corresponding to a welding arc in a jet transition form, and it also has a "speed weld" or a fast pulse welding mode, corresponding to a welding arc in a pulse droplet transition form. Of course, it is not limited to this, and can also be selected according to actual needs.

[0061] In this embodiment, preferably, Figure 2 and Figure 3 As shown, in step S5 and step S6, the front welding gun 6, i.e., the front welding gun, performs uniform penetration and back forming on the root of the groove 2, and the rear welding gun 7, i.e., the rear welding gun, performs remelting welding on the root of the penetration weld.

[0062] In this embodiment, preferably, Figures 1 to 3 As shown, in step S5, during the bottom welding, the front welding gun 6 does not swing, the welding wire end of the front welding gun 6 points to the edge line 41 of the lower blunt edge 4, the angle β between the front welding gun 6 and the horizontal plane is 8 to 10° (and preferably the angle between the welding wire of the welding gun and the horizontal plane is β), the welding current of the front welding gun 6 is 240-280A, the welding voltage of the front welding gun 6 is 27-30V, and the welding speed of the front welding gun 6 is adjusted in real time according to the size of the root gap of the weld to ensure that the bottom welding is not burned through.

[0063] According to the above description, when welding the base, the power supply of the front gun selects the "rapid weld" mode, which can adjust a concentrated and stable high-intensity jet arc to achieve stable base penetration and back penetration.

[0064] In this embodiment, preferably, Figures 1 to 3 As shown, in step S5, when the root gap tolerance c of the weld is 0-2 mm, the welding speed of the front welding gun 6 is 300 mm / min; when the root gap tolerance c of the weld is 2-3 mm, the welding speed of the front welding gun 6 is 250-300 mm / min; when the root gap tolerance c of the weld is 3-4 mm, the welding speed of the front welding gun 6 is 190-250 mm / min.

[0065] According to the above description, the corresponding relationship between tolerance and welding speed is given, so by selecting different welding speeds, welding with different root gap tolerances c can be adapted.

[0066] In this embodiment, preferably, Figure 2 and Figure 3 As shown, during the root welding process, the front welding gun 6 adjusts the welding speed in real time according to the size of the weld, while the other welding parameters remain unchanged, thereby reducing welding variables and lowering the difficulty of the operation.

[0067] In this embodiment, preferably, Figure 2 and Figure 3 As shown, in step S5, during the bottom welding, the rear welding gun 7 does not swing, the welding wire end of the rear welding gun 7 points to the center of the weld, that is, the weld center line 5, the welding speed of the rear welding gun 7 is consistent with the welding speed of the front welding gun 6, and the welding current and welding voltage are adjusted in real time according to the size of the root gap of the weld to ensure that the bottom weld of the rear gun is not drooped.

[0068] According to the above description, when welding the base, the power supply of the rear gun selects the "rapid weld" mode, which can adjust a concentrated and stable high-intensity jet arc to achieve stable base penetration and back penetration.

[0069] In this embodiment, preferably, Figures 1 to 3 As shown, in step S5, when the root gap tolerance c of the weld is 0-2mm, the welding current of the rear welding gun 7 is 300-320A, and the welding voltage of the rear welding gun 7 is 30-33V; when the root gap tolerance c of the weld is 2-3mm, the welding current of the rear welding gun 7 is 260-300A, and the welding voltage of the rear welding gun 7 is 28-31V; when the root gap tolerance c of the weld is 3-4mm, the welding current of the rear welding gun 7 is 220-260A, and the welding voltage of the rear welding gun 7 is 24-28V.

[0070] According to the above description, the corresponding relationship between the tolerance and the welding current speed and welding voltage is given. Therefore, by selecting different welding current speeds and welding voltages, welding with different root gap tolerances c can be adapted.

[0071] In this embodiment, preferably, Figure 2 and Figure 3 As shown, during the root welding process, the rear welding gun 7 adjusts the wire feed speed in real time according to the size of the weld, controlling the welding current and welding voltage by the wire feed speed while keeping the other welding parameters unchanged, thereby reducing welding variables and making the operation easier. Of course, this is not the only option.

[0072] In this embodiment, preferably, Figures 1 to 3As shown, in step S6, during the filling and capping welding process, both welding guns adopt non-swinging multi-layer multi-pass welding, the welding current of both welding guns is 220-280A, the welding voltage of both welding guns is 24-30V, and the welding speed of both welding guns is 300-320mm / min.

[0073] According to the above description, pulse arc is used for filling and cap welding, and welding is carried out according to the above welding parameters, which can adjust a concentrated and stable high-intensity jet arc. The pulse peak current is used to break the oxide scale and the stable swinging effect of the robot welding gun can realize cleaning-free welding between layers, and the welding efficiency is high, the spatter is small, and the shape is beautiful.

[0074] In this embodiment, preferably, the butt weld root cleaning-free welding process also includes the following steps: S7, performing visual inspection of the weld, internal structure inspection such as UT inspection and mechanical property inspection, especially the workpiece welded by this process is inspected to be free of defects and the mechanical property inspection is qualified.

[0075] In this embodiment, preferably, in step S5 and step S6, the welding material is a solid welding wire that matches the base material, and the welding wire diameter is 1.2 mm to ensure the stability and firmness of the weld structure; the shielding gas is 80% Ar + 20% CO2, and the strong blowing force of the gas shielded welding can remove impurities at the root of the base weld, thereby ensuring the quality of the base weld.

[0076] In this embodiment, preferably, Figure 2 As shown, in step S5, the bottom welding is carried out simultaneously in the same direction on both sides of the weld, and the distance L between the two welding guns, namely the front welding gun 6 and the rear welding gun 7, is 50 to 100 mm. It should be noted that: the welding starting point and the welding end point of the two welding guns are the same, and in the bottom welding process, the two welding guns are arranged one in front and the other in the back, wherein the welding gun close to the welding end point is the aforementioned front welding gun 6, and the welding gun close to the welding starting point is the aforementioned rear welding gun 7.

[0077] According to the above description, a preset distance needs to be maintained between the two welding guns, which can effectively avoid arc interference and thus ensure welding efficiency and quality.

[0078] In this embodiment, preferably, Figures 1 to 3 As shown, the two grooves 2 of the upper plate 11 to be welded and the lower plate 12 to be welded form a total V-shaped groove (see Figure 1 As shown), the angle of the V-shaped groove is 60°, that is, the single-side angle θ1 is 30.

[0079] Of course, the above structure is not limited thereto, and other structures may also be used, for example: the two grooves 2 of the upper plate 11 to be welded and the lower plate 12 to be welded form a total U-shaped groove (see Figure 4 As shown, preferably, the bottom radius of the U-shaped groove is 10 mm, of course, not limited to this, and can also be selected according to actual needs), and preferably, the angle θ2 of the U-shaped groove is 20°-25°. Of course, not limited to this, the shape and angle of the groove 2 can also be selected according to actual needs.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A butt weld root cleaning-free welding process, characterized in that: The steps include: S1. Complete the blanking and forming of the steel plate to form two plates to be welded, and open bilaterally symmetrical grooves at the weld positions where the two plates to be welded meet, with a blunt edge provided between the grooves on both sides of the lower plate to be welded; S2. Grind and remove rust from the welding areas of the two plates to be welded using a grinding machine; S3. Assemble and position weld the two plates to be welded, ensuring that the butt weld is located in the horizontal welding position; S4, preheating the weld area formed between the two plates to be welded; S5. Perform gas shielded backing welding simultaneously and in the same direction on both sides of the weld, and use either a droplet transition or a jet transition arc during welding. When the assembly gap between the two plates to be welded is 0-3 mm, use a jet transition arc, and when the assembly gap between the two plates to be welded is 3-4 mm, use a droplet transition arc. S6. Perform gas shielded filling and cap welding simultaneously and in the same direction on both sides of the weld, and use pulsed droplet transfer arc during welding; In step S5, during the bottom welding, the front welding gun does not swing, the welding wire tip of the front welding gun points to the lower blunt edge line, the angle between the front welding gun and the horizontal plane is 8-10 degrees, the welding current of the front welding gun is 240-280A, and the welding voltage of the front welding gun is 27-30V; In step S5, when the root gap tolerance of the weld is 0-2 mm, the welding speed of the front welding gun is 300 mm / min; when the root gap tolerance of the weld is 2-3 mm, the welding speed of the front welding gun is 250-300 mm / min; when the root gap tolerance of the weld is 3-4 mm, the welding speed of the front welding gun is 190-250 mm / min; In step S5, during the bottom welding, the rear welding gun does not swing, the welding wire end of the rear welding gun points to the center of the weld, and the welding speed of the rear welding gun is consistent with the welding speed of the front welding gun; In step S5, when the root gap tolerance of the weld is 0-2 mm, the welding current of the rear welding gun is 300-320 A, and the welding voltage of the rear welding gun is 30-33 V; when the root gap tolerance of the weld is 2-3 mm, the welding current of the rear welding gun is 260-300 A, and the welding voltage of the rear welding gun is 28-31 V; when the root gap tolerance of the weld is 3-4 mm, the welding current of the rear welding gun is 220-260 A, and the welding voltage of the rear welding gun is 24-28 V; In step S5, the bottom welding is performed simultaneously on both sides of the weld in the same direction, and the distance between the two welding guns is 50-100 mm.

2. The butt weld root cleaning-free welding process according to claim 1 is characterized in that: In step S1 , the thickness of the blunt edge between the grooves on both sides of the lower plate to be welded is b, and 6 mm ≤ b ≤ 8 mm.

3. The butt weld root cleaning-free welding process according to claim 2 is characterized in that: In step S1 , the thickness of the blunt edge between the grooves on both sides of the upper plate to be welded is a, and 0 mm ≤ a ≤ 2 mm.

4. The butt weld root cleaning-free welding process according to claim 3 is characterized in that: In step S1, when 20 mm ≤ t < 80 mm, 0 mm ≤ a ≤ 2 mm, 6 mm ≤ b ≤ 8 mm; when t ≥ 80 mm, 1 mm ≤ a ≤ 2 mm, 6 mm ≤ b ≤ 8 mm; wherein t is the thickness of the plate to be welded.

5. The butt weld root cleaning-free welding process according to claim 1 is characterized in that: In step S3, the tack weld is ground before welding to remove welding defects, and the end is ground to form a transition slope, and the misalignment tolerance of the assembly weld is ensured to be 0-3 mm, and the root gap tolerance is 0-4 mm.

6. The butt weld root cleaning-free welding process according to claim 1 is characterized in that: In step S6, during the filling and capping welding process, both welding guns use non-swinging multi-layer multi-pass welding, the welding current of both welding guns is 220-280A, the welding voltage of both welding guns is 24-30V, and the welding speed of both welding guns is 300-320mm / min.

7. The butt weld root cleaning-free welding process according to any one of claims 1 to 6, characterized in that: The butt weld root cleaning-free welding process further comprises the following steps: S7, performing appearance inspection, internal structure inspection and mechanical property inspection on the weld; and / or In step S5 and step S6, the welding material is a solid welding wire that matches the base material, the welding wire diameter is 1.2 mm, and the shielding gas is 80% Ar + 20% CO2; and / or In step S5 and step S6, a welding robot is used to perform welding operations; and / or When the thickness of the steel plate is ≤80mm, the grooves of the upper plate to be welded and the lower plate to be welded form an X-shaped groove, and the angle of the X-shaped groove is 60°; when the thickness of the steel plate is greater than 80mm, the grooves of the upper plate to be welded and the lower plate to be welded form a U-shaped groove, and the angle of the U-shaped groove is 20°-25°.

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