Back gouging-free full penetration automatic welding method for thick plate H steel

Abstract

The invention relates to the field of thick plate H steel welding, in particular to a back-gouging-free full penetration automatic welding method for thick plate H steel, and provides the following scheme aiming at the problems of large welding shrinkage and low welding efficiency during full penetration welding of H steel thick plates in the prior art: the method comprises the following steps: S1, forming single-side 35-degree grooves in two sides of an H steel web; s2, the welding position in the middle of the H-steel flange plate and the groove position of a web plate are polished; s3, according to different thicknesses of the H steel plates, the reversible deformation angle of the flange plate is adjusted; and S4, H steel is assembled, two times of positioned welding and fixing are conducted between the web and the two flange plates, and temporary supports are arranged. According to the method, the thick plate H steel is prefabricated in advance and subjected to reverse deformation, flange plate deformation and cross section size deviation are reduced, the operation without back gouging on the reverse side is achieved through the welding mode of low-current bottoming and submerged-arc welding secondary penetration, and the machining efficiency and the full penetration first-pass yield of the thick plate H steel are improved.

Description

Technical Field

[0001] The present invention relates to the field of thick plate H-beam welding, and particularly to an automatic welding method for full penetration without root gouging of thick plate H-beams. Background Art

[0002] At present, for the full penetration composite weld of thick plate H-beams (web thickness ≥ 20 mm), the conventional process manufacturing method is to open a single-sided 35° groove on the web of the H-beam. After manually assembling the H-beam, first manually weld the backing and filling on the groove side, then perform air gouging to remove the root on the reverse side. After the root gouging is completed, the capping is carried out. Although this welding process method is maturely applied, there are still the following problems: on the one hand, for the full penetration composite weld of thick plate H-beams, the heat input during a single welding process is large and concentrated, which will form a large amount of welding shrinkage, resulting in deformation of the flange plate and deviation of the cross-sectional dimensions. Moreover, after the thick plate H-beam is welded, certain welding deformation will occur, and additional equipment and labor are required for correction, increasing the additional processing cost.

[0003] On the other hand, there are welding defects in the backing layer on the groove side of the H-beam, and full penetration cannot be guaranteed at the root. It is necessary to remove the welding defects by air gouging on the reverse side of the groove side. And air gouging has factors such as noise and dust that are harmful to the human body and the environment. Moreover, for the welding process form of full penetration welding on the front side and root gouging on the reverse side of thick plate H-beams, on the one hand, it increases the air gouging time and reduces the welding efficiency. On the other hand, the one-time qualification rate, efficiency, and cost of its full penetration welding have not been improved and broken through for a long time. Therefore, this solution proposes an automatic welding method for full penetration without root gouging of thick plate H-beams. Summary of the Invention

[0004] An automatic welding method for full penetration without root gouging of thick plate H-beams proposed by the present invention solves the problems of large welding shrinkage and low welding efficiency during full penetration welding of thick plate H-beams in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An automatic welding method for full penetration without root gouging of thick plate H-beams includes the following steps:

[0007] S1. Open a single-sided 35° groove on both sides of the web of the H-beam;

[0008] S2. Grind the welding position in the middle of the flange plate of the H-beam and the groove position of the web;

[0009] S3. Adjust the reverse deformation angle of the flange plate according to the different thicknesses of the H-beam plate;

[0010] S4. Assemble the H-beam, perform two positioning welds to fix it between the web and the two flange plates, and set temporary supports with a spacing of 1 m and a distance of 200 mm from the end on the groove side during the second positioning weld;

[0011] S5. Weld the main weld of the H-beam and adjust the extension length of the welding wire before welding;

[0012] S6. Weld in the order of the backing layer and the filling layer. For the first two passes of backing welding, use small current and small voltage for welding, and the depth of each backing layer is 3 - 4 mm;

[0013] S7. After the backing and filling are completed, the front of the H-beam and the reverse side of the groove side are both covered with automatic submerged arc welding;

[0014] S8. The welding is completed, and the full penetration of the weld and the reverse deformation amount are detected.

[0015] Through the above technical solutions, prefabricate the reverse deformation for the thick plate H-beam in advance. After welding, the shrinkage amount resists the reverse deformation amount, and the cross-section deviation is controlled within the standard range, reducing the time of secondary mechanical or flame correction. Moreover, it effectively avoids the cumbersome steps of root cleaning on the reverse side in the traditional welding method, not only improving the welding efficiency but also reducing the labor intensity of workers.

[0016] As a further improvement of the above solution, in step S2, when grinding, continue to grind the slag, scale, rust and other impurities within 50 mm on both sides of the groove position and the weld position until the surface is smooth and presents a silver-white color.

[0017] As a further improvement of the above solution, in step S4, if the reverse deformation amount of the H-beam is too large or too small, secondary mechanical or flame correction is required. When the web thickness of the H-beam is 20 mm ≤ t < 35 mm, the pre-deformation angle is 3 - 3.5°; when the web thickness of the H-beam is 35 mm ≤ t < 50 mm, the pre-deformation angle is 5 - 6°.

[0018] As a further improvement of the above solution, the temporary support set in step S4 is a detachable rigid support and is fixed to the web and flange by welding.

[0019] As a further improvement of the above solution, in step S5, before welding the main weld of the H-beam, clean the groove welding surface twice to ensure that there are no impurities and rust around the weld. At the same time, use a heating gun to preheat along the length of the weld. When measuring and monitoring the preheating temperature with an infrared thermometer, when the steel plate thickness t < 20 mm, the preheating temperature ≥ 20°C; when 20 mm ≤ t ≤ 40 mm, the preheating temperature ≥ 80°C; when t > 40 mm, the preheating temperature ≥ 100°C.

[0020] As a further improvement of the above solution, in step S5, when adjusting the welding wire, ensure that the wire feeding wheel supplies the welding wire tightly and ensure that the dry extension length of the welding wire is 15 - 20 mm.

[0021] As a further improvement of the above solution, in step S6, before welding, select a suitable protective sleeve according to different plate thicknesses and groove depths, including: 350A reducer sleeve (Φ14×100mm): used for priming the root of the groove with t≥60mm; 500A reducer sleeve (Φ18×84mm): used for filling the middle part with 35mm≤t<60mm; standard 500A sleeve (Φ24×84mm): used for filling the upper part with t<35mm.

[0022] As a further improvement of the above scheme, in step S6, after the base is laid to the second layer, the temporary support is removed. After the first two base weldings, the welding current and voltage are appropriately increased, and the filling layer is welded according to the multi-layer and multi-pass welding process. When welding to the penultimate layer, the height of the weld surface from the web surface is controlled to be 2-3 mm.

[0023] As a further improvement to the above scheme, in step S9, when inspecting the welds, an ultrasonic flaw detector is used to inspect the thick plate H-steel welds. When the full penetration pass rate reaches 96.8% or above, the welding requirements are met. At the same time, the cross-sectional height of the H-steel is remeasured to ensure that the cross-sectional height deviation is ≤1.5mm / m.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Through precise data analysis and experimental verification, this paper successfully established a prediction model for the shrinkage of thick plate H-steel welds. This model accurately predicts the shrinkage of thick plate H-steel welds of varying specifications and materials during welding. Based on this model, a corresponding pre-deformation is simultaneously applied during the H-steel assembly stage, effectively offsetting deformation during welding and significantly reducing flange deformation and cross-sectional dimensional deviation.

[0026] 2. The introduction of an assembly machine for equipment assembly not only improves the accuracy and stability of the assembly compared to the traditional manual assembly method, but also significantly shortens the assembly time and reduces labor costs. At the same time, since the assembly machine has automatic positioning and adjustment functions, it further reduces the need for secondary correction and improves overall production efficiency.

[0027] 3. Through the welding method of low current rooting and submerged arc welding secondary penetration, while ensuring the welding quality, it realizes the back side without root cleaning, effectively avoiding the noise, smoke and other hazards caused by the traditional welding process of gas gouging. In addition, this new welding method also significantly improves the welding efficiency and reduces the welding cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of the web and flange plates of the present invention;

[0029] Figure 2Structural schematic diagram for adjusting the reverse deformation angle of the flange plate in the present invention

[0030] Figure 3 It is a structural schematic diagram when assembling the H-shaped steel with the lower flange centered and the web vertical, and pre-assembling the T-shaped structure;

[0031] Figure 4 It is a structural schematic diagram when loosening the web tightening wheel on the reverse side of the groove during the assembly of the H-shaped steel;

[0032] Figure 5 It is a structural schematic diagram when assembling the H-shaped steel with the lower flange centered and the web inclined, and pre-assembling the T-shaped structure;

[0033] Figure 6 It is a structural schematic diagram when adjusting and presetting the reverse deformation during the assembly of the H-shaped steel;

[0034] Figure 7 It is a structural schematic diagram when performing secondary positioning welding, fixing and erecting temporary supports during the assembly of the H-shaped steel;

[0035] Figure 8 It is a structural schematic diagram when fixing the other side flange plate;

[0036] Figure 9 It is a welding schematic diagram during backing and filling;

[0037] Figure 10 It is a structural schematic diagram during submerged arc surfacing;

[0038] Figure 11 It is a structural schematic diagram when installing the reducing protective sleeve. Specific implementation manner

[0039] Next, in combination with the accompanying drawings and specific implementation manners, the present invention will be further described. It should be noted that, on the premise of no conflict, the following-described embodiments or technical features can be arbitrarily combined to form new embodiments.

[0040] Embodiment 1:

[0041] Please refer to Figures 1-9 A full-penetration automatic welding method for thick plate H-shaped steel without root chipping in this embodiment includes the following steps:

[0042] S1. As shown in Figure 1 , on both sides of the H-shaped steel web, a single-sided 35° groove is opened. When opening the groove, semi-automatic preparation is used to ensure the groove quality.

[0043] S2. As shown in Figure 1As shown, grind the welding position in the middle of the H-beam flange plate and the groove position of the web. When grinding, continue to grind the slag, scale, rust and other impurities within 50 mm on both sides of the groove position and the weld position until the surface is smooth and silver-white. For the middle welding position of the H-beam web corresponding to the flange plate, the surface also needs to be cleaned with a grinder to provide suitable welding conditions. The groove surface of the web is ground with a grinder, and the flange plate is ground with a belt sander.

[0044] S3. As Figure 2 shown, adjust the reverse deformation angle of the flange plate according to the different thicknesses of the H-beam steel plate. When the thickness t of the H-beam web is 20 mm ≤ t < 35 mm, the pre-deformation angle is 3 - 3.5°; when the thickness t of the H-beam web is 35 mm ≤ t < 50 mm, the pre-deformation angle is 5 - 6°. If the reverse deformation amount of the H-beam is too large or too small, secondary mechanical or flame correction is required.

[0045] S4. Position through the H-beam assembly machine and perform two tack welds to fix it between the web and the two flange plates. Then, when performing the second tack weld, set temporary supports with a spacing of 1 m and a distance of 200 mm from the end on the groove side. As Figures 3-8 shown, first center the H-beam flange plate and tighten the pressure wheels at both ends; then lift the web, adjust and center it in the middle of the flange plate. At the same time, after tightening the pressure wheels on both sides of the web, perform preliminary tack welding. After the tack welding, loosen the pressure wheel on the reverse side of the groove of the web by a certain distance, and then push the pressure wheels of the flange plate synchronously towards the flange plate side. Then, according to the pre-deformation amount, adjust the angle between the web and the flange plate. The distance by which the pressure wheel is loosened mainly depends on the setting of the reverse deformation amount, and it is reconfirmed twice through the measured angle or pre-deformation amount. Angle gauges, steel rulers, tape measures, etc. can be used for measurement and verification. After confirmation, perform the second tack welding and add temporary supports to fix its reverse deformation. Finally, after the H-beam equipment assembly reverse deformation is completed, recheck the reverse deformation angle with a tape measure, steel ruler, etc. If there are some deformations that do not meet the setting, fine-tuning is required, and then fix the other flange plate and the web in the same way (as Figure 8 shown).

[0046] S5. Weld the main weld of the H-beam with an all-round automatic welder, and adjust the extension length of the welding wire before welding. When adjusting the welding wire, ensure that the wire feeding wheel supplies the wire tightly, and ensure that the dry extension length of the welding wire is 15 - 20 mm. Before welding the main weld of the thick-plate H-beam, clean the groove welding surface for the second time to ensure that there are no impurities and rust around the weld. At the same time, use a heating gun to preheat along the length of the weld. When preheating, use an infrared thermometer to measure and monitor the preheating temperature. When the thickness of the steel plate t < 20 mm, the preheating temperature ≥ 20°C; when 20 mm ≤ t ≤ 40 mm, the preheating temperature ≥ 80°C; when t > 40 mm, the preheating temperature ≥ 100°C.

[0047] S6. Weld in the order of base layer and filling layer, and use small current and small voltage for the first two base welding. The depth of each layer is 3-4mm. Before welding, select the appropriate protective cover according to the different plate thickness and groove depth to ensure the arc angle of the groove bottom welding and the welding efficiency of the subsequent pass.

[0048] like Figure 9 As shown, during welding, in the first two primers at the bottom of the groove, the depth of each primer is 3-4mm, so as to avoid failure of penetration during subsequent submerged arc welding on the reverse side due to welding defects that are too deep or too thick. The first two welding passes need to use small current and small voltage to ensure that the reverse side is not welded to the root. After the first two welding passes, the welding current and voltage are appropriately increased, and welding is performed according to the multi-layer and multi-pass welding process. When welding to the penultimate layer, the height of the weld surface from the web surface is controlled to be 2-3mm to ensure the quality of the rear cover. At the same time, during this welding process, after the two layers of primer are laid, the temporary support needs to be removed, and the rear weld is in a naturally contracted state, and no external mechanical stress is provided to hinder deformation recovery.

[0049] S7, such as Figure 10 As shown in the figure, after the base filling is completed, in order to make the weld shape beautiful, the front and back sides of the H-steel are covered with automatic submerged arc welding to ensure the appearance of the weld. The back side is directly welded by submerged arc welding. The welding defects remaining in the bottom layer of the groove are relatively thin. The heat of the back side submerged arc welding is instantly concentrated and input to form secondary melting, avoiding the working environment of back side root cleaning and gouging, and improving the welding efficiency and full penetration qualification rate.

[0050] S8. After welding is completed, the full penetration and reverse deformation of the weld are tested. When testing the weld, use an ultrasonic flaw detector to test the thick plate H steel weld. When the full penetration pass rate reaches 96.8% or above, the welding requirements are met. At the same time, re-measure the cross-sectional height of the H steel to ensure that the cross-sectional height deviation is ≤1.5mm / m.

[0051] In this embodiment, the temporary support is a detachable rigid support and is fixed to the web and flange plates by welding. The temporary support is used to support the web and flange plates, which can offset a portion of the shrinkage of the previous weld.

[0052] In this embodiment, as specifically shown in Table 1, under conditions of different web plate thicknesses, the reverse deformation angles are inconsistent; and under conditions of the same web plate thickness, although the reverse deformation angles are consistent, the flange plate widths are different, and the pre-deformation amounts will be different.

[0053]

[0054] Table 1 In this embodiment, when the plate thickness is different, the gas shielded welding process parameters of the automatic welding machine are adjusted accordingly:

[0055]

[0056]

[0057] Table 2

[0058] As shown in Table 2, by reasonably setting the welding process parameters of the multi-layer and multi-pass welding of the H-shaped steel combined weld, the first-pass qualification rate of full penetration welding is effectively improved. During the welding process, the welding current and voltage should be strictly controlled to avoid overheating or overcooling welding conditions to ensure the strength and toughness of the weld. In addition, the welding consumables should be dried before welding to remove moisture and gas in the welding consumables and avoid porosity and cracks during welding.

[0059] Example 2:

[0060] Combined with Figure 11 , on the basis of Example 1, the further improvement of this example lies in: before welding, a suitable protective sleeve is selected according to different plate thicknesses and groove depths. In the prior art, the protective sleeve 500A is used for welding. However, due to its large outer diameter, when welding at the root of the groove, the 500A protective sleeve is prone to interference with the groove surface, and the welding wire cannot reach the root of the groove. Only the dry extension length of the welding wire can be increased or the groove can be enlarged. But on the one hand, it is easy to produce root welding defects at the root and the full penetration of the weld cannot be guaranteed, and the welding quality cannot be achieved; on the other hand, the increase in the groove angle also increases the filling amount of the welding wire, resulting in cost waste and low efficiency. In this example, when selecting the protective sleeve, specifically as shown in Table 3,

[0061]

[0062] Table 3

[0063] It can be seen from Table 3 that: the 350A reducing sleeve (Φ14×100mm) is used for backing welding at the root of the groove with t≥60mm; the 500A reducing sleeve (Φ18×84mm) is used for middle filling with 35mm≤t<60mm; the standard 500A sleeve (Φ24×84mm) is used for upper filling with t<35mm. Then, as the web plate thickness increases, the groove depth becomes deeper and deeper. To ensure the welding penetration quality at the bottom of the groove and avoid back gouging, the welding protective sleeve needs to be adjusted timely during the welding process. By switching the welding reducing protective sleeve, there is enough swing arc space at the root of the groove, and rapid welding can be carried out at the upper part of the groove.

[0064] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection required by the present invention.

Claims

1. An automatic welding method for full penetration without root gouging of thick plate H-beam, characterized in that, The following steps are involved: S1. Open a single-sided 35° groove on both sides of the H-steel web; S2. Grind the welding position in the middle of the H-steel flange plate and the web groove position; S3. Adjust the anti-deformation angle of the flange plate according to the thickness of the H steel plate; S4. Assemble the H-steel and perform two tack welds between the web and the two flanges. During the second tack weld, set up temporary supports on the groove side with a spacing of 1m and 200mm from the end. S5. Weld the main weld of H steel and adjust the extension length of welding wire before welding; S6. Weld in the order of base layer and filling layer, and use low current and low voltage for the first two base weldings. The depth of each base layer is 3-4mm. S7. After the base filling is completed, the H steel front and groove side are covered with automatic submerged arc welding; S8. Welding is completed, and the full penetration and reverse deformation of the weld are tested.

2. The automatic welding method for full penetration without root cleaning of heavy plate H-shaped steel according to claim 1, characterized in that, In step S2, during grinding, continue to twist and grind away impurities such as cutting slag, oxide scale, and rust within a range of 50 mm on both sides of the groove position and the weld position until the surface is smooth and silvery white.

3. A full penetration automatic welding method for thick plate H-beam without root gouging, according to claim 1, characterized in that In step S4, if the H-steel reverse deformation is too large or too small, secondary mechanical or flame correction is required. When the H-steel web thickness is 20mm≤t<35mm, the pre-deformation angle is 3-3.5°; when the H-steel web thickness is 35mm≤t<50mm, the pre-deformation angle is 5-6°.

4. A full penetration automatic welding method for thick plate H-beams without root chipping, as claimed in claim 1, characterized in that, The temporary support set in step S4 is a detachable rigid support and is fixed to the web and flange plates by welding.

5. A full penetration automatic welding method for thick plate H-beams without root gouging, characterized in that, In step S5, before welding the main weld of H steel, the groove welding surface is cleaned twice to ensure that there are no impurities or rust around the weld. At the same time, a drying gun is used to preheat along the length of the weld. During preheating, an infrared thermometer is used to measure and monitor the preheating temperature. When the steel plate thickness t<20mm, the preheating temperature is ≥20℃; when 20mm≤t≤40mm, the preheating temperature is ≥80℃; when t>40mm, the preheating temperature is ≥100℃.

6. A method for automatic welding of full penetration without root gouging of thick plate H-shaped steel according to claim 5, characterized in that In step S5, when adjusting the welding wire, ensure that the wire pressing wheel and the welding wire are closely fed, and ensure that the dry extension length of the welding wire is 15-20 mm.

7. A full penetration automatic welding method for thick plate H-beams without root gouging, according to claim 5, characterized in that In step S6, before welding, select the appropriate protective sleeve according to the different plate thickness and groove depth. Specifically, it includes: 350A reducer sleeve (Φ14×100mm): used for priming the root of the groove with t≥60mm; 500A reducer sleeve (Φ18×84mm): used for filling the middle part with 35mm≤t<60mm; standard 500A sleeve (Φ24×84mm): used for filling the upper part with t<35mm.

8. A method for automatic welding of full penetration without root cleaning of thick plate H-beam according to claim 1, characterized in that, In step S6, after the base is laid to the second layer, the temporary support is removed. After the first two base welding passes, the welding current and voltage are appropriately increased, and the filling layer is welded according to the multi-layer and multi-pass welding process. When welding to the penultimate layer, the height of the weld surface from the web surface is controlled to be 2-3 mm.

9. A full penetration automatic welding method for thick plate H-beams without root cleaning, as claimed in claim 1, wherein In step S9, when inspecting the welds, an ultrasonic flaw detector is used to inspect the thick plate H-steel welds. When the full penetration pass rate reaches 96.8% or above, the welding requirements are met. At the same time, the cross-sectional height of the H-steel is remeasured to ensure that the cross-sectional height deviation is ≤1.5 mm / m.

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