Welding method for butt weld of steel plate

Abstract

The invention relates to the field of welding processes of steel structural members, in particular to a welding method for butt welding seams of steel plates, which is suitable for welding seams under the condition that a gap between a first steel member to be welded and a second steel member to be welded is large. Comprising the following steps that a, the component size and the weld joint gap and truncated edge size between a first steel component and a second steel component are checked; b, manufacturing a liner plate; c, two magnetic supports of a connecting rod of the gasket positioning device are arranged between the gasket plate and the first steel member and between the gasket plate and the second steel member, and the two magnetic supports are attracted to the bottoms of the first steel member and the second steel member through magnetic pieces; d, the liner plate is fixed to the first steel member and the second steel member through fillet weld spot welding, and then the liner positioning device is pulled out; and e, purging and cleaning the welding position area of the welding seam, and then completing the remaining welding process. The method is particularly suitable for welding process occasions with large welding gaps of steel structural parts of steel box bridges.

Description

Technical Field

[0001] The invention relates to the field of steel structure welding technology, in particular to a welding method for a steel plate butt weld. Background Art

[0002] Large steel structure components, such as steel pipe piles, hollow steel pipe arches for bridges, large pipe trusses, metallurgical system components, etc., involve butt welding of round pipe components during manufacturing and installation. After welding, non-destructive testing is required to determine the weld qualification. If defects are found during the test, the weld needs to be planed and reworked, resulting in losses in welding auxiliary materials, welding energy, labor, construction period, etc. The common single-sided welding and double-sided forming welding process is mainly ceramic liner welding. This type of method has the following main disadvantages: 1. The welding cost caused by the ceramic liner itself increases significantly; 2. The ceramic liner has no adhesion to the cladding metal, and the cladding metal in the molten pool is easy to slide off, especially in horizontal welding, vertical welding, overhead welding and other welding positions; 3. The ceramic liner is attached to the surface of the parent material with adhesive. After welding and heating, the adhesive of the ceramic liner itself is easy to fall off, especially in the flat welding position. After heating, the liner is more likely to fall off under the action of gravity in the molten pool, which has an adverse effect on the welding process; The ceramic liner has certain requirements for the size of the weld gap of the parent material assembly. The uneven gap has a greater impact on the welding qualification rate, and larger gaps cannot be welded; 4. When assembling steel pipe segments on site, it is necessary to enter the hall pipe to paste the ceramic liner, which is cumbersome.

[0003] Taking the patent with announcement number CN114346383A, titled "A Submerged Arc Welding Single-Sided Welding Double-Sided Forming Process" as an example, it involves a common welding process. The solution includes pre-treatment of the pipe base material weld, followed by grooving and welding. However, in the welding process after the base material weld is pre-treated, the same docking interface may involve butt welds of horizontal welding, vertical welding, overhead welding and other welding positions. As long as ceramic liners are used for these welds, there will be defects of no adhesion to the cladding metal, and the welding position changes with the shape, which requires high welding skills and increases the difficulty of welding. Especially for docking during on-site installation, it is necessary to paste and install the ceramic liner inside the pipe, which is not conducive to improving construction efficiency, and there are construction safety hazards in the box operation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a welding method for steel plate butt welds which is suitable for welding welds when the gap between a first steel component to be welded and a second steel component is relatively large.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a welding method for a butt weld of a steel plate, including a gasket positioning device, comprising the following steps:

[0006] a. Check the component size and the weld gap and blunt edge size between the first steel component and the second steel component according to the BIM model data and design drawing requirements, and perform groove surface pretreatment;

[0007] b. Making a liner plate, wherein the liner plate is made of the same material as the first steel member and the second steel member. After the liner plate is cut according to size, the oxide and burrs of the liner plate are cleaned to ensure a smooth surface;

[0008] c. The pad positioning device includes a connecting rod, which is U-shaped, and magnetic supports are provided at both free ends of the connecting rod. A magnetic member is fixedly provided on the magnetic support, and the thickness of the magnetic support is equal to the gap between the pad plate and the steel structure. The distance between the center points of the two magnetic supports is less than the length of the pad plate. A handle is provided at the bend of the middle section of the U-shaped connecting rod;

[0009] The two magnetic supports of the connecting rod of the liner positioning device are arranged between the liner plate and the first steel component and the second steel component, the two magnetic supports are adsorbed on the bottom of the first steel component and the second steel component through magnetic parts, the top surface of the liner plate is close to the magnetic supports, and the gap between the top surface of the liner plate and the bottom of the first steel component and the second steel component is 2 to 3 mm;

[0010] d. Fix the liner plate to the first steel member and the second steel member by spot welding with fillet welds, and then remove the liner positioning device;

[0011] e. Purge and clean the weld area and then complete the remaining welding process.

[0012] Furthermore, in step a, when the first steel member and the second steel member cannot be deformed and corrected after welding, or when the first steel member and the second steel member are curved parts, an anti-deformation fixture is installed to position and shape the first steel member and the second steel member to prevent the first steel member and the second steel member from being deformed due to welding thermal stress.

[0013] Furthermore, in step b, the liner plate is processed by using the leftover scraps of the steel structure and cut by laser.

[0014] Furthermore, in step b, the dimension parameters of the backing plate are as follows:

[0015] Thickness of backing plate t: 5≤t≤T min / 2, unit: mm, T min is the thickness of the smaller member between the first steel member and the second steel member;

[0016] Length of backing plate a: 300≤a≤2sqrt((R min +1) 2 -R min 2)), unit: mm, R min The radius value of the maximum curvature of the current surface weld line shape;

[0017] Height h of the backing plate: h = δ max +20 and 30≤h≤50, unit: mm, δ max is the maximum weld gap value.

[0018] Furthermore, in step c, the distance between the center points of the two magnetic supports is equal to one third of the length of the backing plate.

[0019] Furthermore, the magnetic support includes a fixed edge and a positioning edge, which are perpendicular to each other to form an L-shape, the fixed edge of the magnetic support is fixedly arranged at the end of one end of the connecting rod, the magnetic part is arranged on the positioning edge of the magnetic support, and the thickness of the positioning edge of the magnetic support is equal to the gap size between the lining plate and the steel structure.

[0020] Furthermore, the magnetic component is a neodymium iron boron permanent magnet sheet.

[0021] Furthermore, the connecting rod is a bent structure, and the extension direction of the handle axis is parallel to the extension direction of the positioning edge of the magnetic support.

[0022] The beneficial effects of the present invention are as follows: 1. Instead of using high-cost ceramic liner, it is made of basically useless steel plate waste, which belongs to the reuse of waste, thereby reducing the welding cost. 2. The liner plate itself will not fall off, and the deposited metal has good adhesion, which is easy to weld, reducing the welding difficulty in various welding positions. 3. The requirements for the dimensional accuracy of the weld gap are low, and it has good adaptability to the situation where the assembly gap is difficult to be completely uniform in complex situations such as curved structures and pipe truss results. Therefore, it has a higher and more stable welding qualification rate than ceramic liner, reduces the rework rate, thereby reducing the processing cost, welding auxiliary material cost, labor cost, and construction period caused by rework, and also reduces the increase in safety risks caused by rework, and reduces environmental pollution caused by welding smoke. 4. The welding inside the box is reduced, the unfavorable working environment is avoided, and the safety risks such as suffocation during welding inside the box are avoided. 5. When the steel box bridge is butt-jointed and assembled on site, there is no need to enter the box or the bottom of the box to paste the ceramic liner, and welding is convenient. The present invention is particularly suitable for welding process occasions where the welding gap of steel structural parts of steel box bridges is large. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of an embodiment of the liner positioning device of the present invention for realizing liner plate positioning during welding.

[0024] Figure 2 yes Figure 1 Side view of.

[0025] Figure 3It is a schematic diagram of an embodiment of a U-shaped connecting rod of a pad positioning device of the present invention and magnetic supports arranged at both ends of the connecting rod.

[0026] Figure 4 yes Figure 3 Side view of.

[0027] Marked in the figure are: a first steel component 1, a second steel component 2, a liner plate 3, a liner positioning device 4, a handle 41, a connecting rod 42, a magnetic support 44, a gap D, a sealing plate 43, and a NdFeB permanent magnet sheet 45. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0029] like Figures 1 to 4 The figure shows an embodiment of the gasket positioning device 4 and the positional relationship between the gasket positioning device 4 and the first steel member 1, the second steel member 2 and the gasket plate 3 during welding. The gasket positioning device 4 first includes a connecting rod 42, which is a U-shaped structure. The U-shaped connecting rod 42 is provided with magnetic supports 44 at both free ends. For a gasket plate 3 with a long length, such as Figure 1 As shown, the two magnetic supports 44 can be used to fix the gap along the length direction of the backing plate 3. Generally, it is preferred that the spacing between the center points of the two magnetic supports 44 is equal to one-third of the length of the backing plate 3, so that the stable position of the backing plate 3 set closely below can be limited, and the space occupied by the U-shaped connecting rod 42 can be ensured not to be too large, so as to prevent the U-shaped connecting rod 42 from being inconvenient to use due to the large spacing between the center points of the two magnetic supports 44. Especially during welding operation, if the spacing between the center points of the two magnetic supports 44 is too large, the welding operator may not be able to set the magnetic support 44 to the gap between the first steel member 1 and the second steel member 2 and the backing plate 3. The U-shaped connecting rod 42 can be a bent structure, that is, the axis of the connecting rod 42 is a curve, which is convenient for the construction personnel to extend the magnetic support 44 at the other end of the connecting rod 42 to an angle and position that is easy to operate when holding the handle 41, so as to facilitate subsequent welding. The bending state of the connecting rod 42 can be flexibly adjusted according to the actual welding needs. The two magnetic supports 44 are both L-shaped bending structures, and the L-shaped bending structures include a fixed edge and a positioning edge that are perpendicular to each other, and the fixed edge and the positioning edge are welded by Q235B steel plates. Figure 3 The structure fixedly connected to one end of the connecting rod 42, the positioning edge of the magnetic support 44 is Figure 3The structure is perpendicular to the fixed edge of the magnetic support 44, and the NdFeB permanent magnet sheet 45 is arranged on the positioning edge of the magnetic support 44. The NdFeB permanent magnet sheet 45 can be attached to the positioning edge of the magnetic support 44 with silicone glue, and the silicone glue can be evenly applied to the exposed part of the NdFeB permanent magnet sheet 45 to protect the permanent magnet sheet. When the first steel member 1 and the second steel member 2 cannot be deformed after welding, or the first steel member 1 and the second steel member 2 are curved parts, an anti-deformation fixture is installed to fix the first steel member 1 and the second steel member 2 in place to prevent the first steel member 1 and the second steel member 2 from being deformed due to welding thermal stress.

[0030] In actual use, the operator holds the handle 41 and sets the positioning edges of the magnetic supports 44 at both ends to the bottom of the first steel component 1 and the second steel component 2 to be welded through the connecting rod 42. At this time, the NdFeB permanent magnet sheets 45 of the magnetic supports 44 at both ends are adsorbed to the bottom of the first steel component 1 and the second steel component 2 to fix the magnetic supports 44. Subsequently, an iron or steel backing plate 3 is set at the bottom of the positioning edge of the magnetic support 44. The backing plate 3 is also tightly attached by the magnetic attraction of the NdFeB permanent magnet sheet 45, thereby locking the relative position between the first steel component 1 and the second steel component 2 and the backing plate 3. The gap D between the first steel component 1 and the second steel component 2 and the backing plate 3 is equal to the thickness of the positioning edge of the magnetic support 44. Generally, the gap D ranges from 2 to 3 mm, preferably 2 mm. Subsequently, the backing plate 3 is fixed to the first steel component 1 and the second steel component 2 by electric welding, wherein the spot welding length is 20 mm ≤ L 1 ≤40mm, spacing 250mm≤L≤350mm, welding foot size 5mm≤h f ≤t+2, commonly used spot welding length is 20mm, spacing is 300mm, and weld foot size is 8mm. The commonly used sizes of spot welding length, spacing, and weld foot are the minimum sizes. Smaller sizes are prone to cause the gasket to deform due to heat and fall off during the main weld welding process. After fixing the liner plate 3 in this way, the liner plate 3 is bonded to the first steel component 1 and the second steel component 2 as a whole, which can avoid entering the box to paste the ceramic liner, greatly reducing the difficulty of welding and improving welding efficiency. After the liner is welded and fixed, the liner positioning device 4 is pulled out. At this time, there is a gap D between the liner plate 3 and the first steel component 1 and the second steel component 2, and the liner plate 3 does not need to be supported anymore, and will not fall off during subsequent welding, ensuring the welding quality.

[0031] The detailed welding process steps are as follows: a. Check the component size and the weld gap and blunt edge size between the first steel component 1 and the second steel component 2 according to the BIM model data and the design drawing requirements, and perform groove surface pretreatment; b. Make a backing plate 3, the backing plate 3 is made of the same material as the first steel component 1 and the second steel component 2. After the backing plate 3 is cut according to the size, the oxides and burrs of the backing plate 3 are cleaned to ensure the surface is smooth; c. The backing positioning device 4 includes a connecting rod 42, the connecting rod 42 is U-shaped, and the two free ends of the connecting rod 42 are provided with a magnetic support 44, and a magnetic part is fixedly provided on the magnetic support 44. The thickness of the magnetic support 44 is equal to the gap D between the backing plate 3 and the steel structure. The distance between the center points of the magnetic supports 44 is less than the length of the backing plate 3, and a handle 41 is provided at the bend of the middle section of the U-shaped connecting rod 42; the two magnetic supports 44 of the connecting rod 42 of the backing positioning device 4 are arranged between the backing plate 3 and the first steel member 1 and the second steel member 2, and the two magnetic supports 44 are adsorbed on the bottom of the first steel member 1 and the second steel member 2 through magnetic parts, and the top surface of the backing plate 3 is close to the magnetic supports 44, and the gap D between the top surface of the backing plate 3 and the bottom of the first steel member 1 and the second steel member 2 is 2 to 3 mm; d. The backing plate 3 is fixed to the first steel member 1 and the second steel member 2 by spot welding of the fillet weld, and then the backing positioning device 4 is pulled out; e. The weld area is purged and cleaned, and then the remaining welding process is completed. The remaining welding process is to weld the main weld between the first steel member 1 and the second steel member 2 according to the welding process and parameters of the welding process assessment, and solid welding wire, flux-cored welding wire, gas shielded welding, submerged arc welding, manual welding, robot welding, etc. can be welded with corresponding process parameters.

[0032] As the core component of welding, the backing plate 3 needs to be adapted to and matched with the outer contour surfaces of the first steel member 1 and the second steel member 2. In order to better achieve the above matching and ensure the quality of the weld, the preferred size parameters of the backing plate 3 are as follows: Thickness t of the backing plate 3: 5≤t≤T min / 2, unit: mm, T min is the thickness of the smaller member of the first steel member 1 and the second steel member 2. If the thickness of the backing plate is too thin, it is easy to burn through during welding. If it is too thick, it may increase the cost and cause waste. The length a of the backing plate 3 is: 300≤a≤2sqrt((R min +1) 2 -R min 2 )), unit: mm, R min It is the radius of the maximum curvature of the current curved weld line shape. The commonly used length is 500-600mm. The length is determined to control the shortest and longest values ​​of the plate length when the gap distance deviation between the backing plate and the curved base material is between 0 and 1mm; the height of the backing plate h: h = δ max+20 and 30≤h≤50, unit: mm, δ max It is the maximum value of the weld gap, and the commonly used height is 30mm.

[0033] Example

[0034] The following is an example of on-site assembly and welding of a curved steel box bridge section, using Q355C material and a 20mm thick top plate longitudinal butt joint (for an extra-wide steel box girder, the longitudinal butt joint is the joint along the direction of the road, and the curve line shape is consistent with the direction of the road).

[0035] 1. According to the BIM model data and the requirements of the detailed design drawings, check the dimensions of the first steel member 1 and the second steel member 2, as well as the weld gap and blunt edge dimensions between the first steel member 1 and the second steel member 2, and confirm that the interface between the first steel member 1 and the second steel member 2 is well protected, no deformation is caused during transportation and loading and unloading, and the docking mark is correct. Install anti-deformation fixtures on the first steel member 1 and the second steel member 2 to prevent deformation caused by welding thermal stress.

[0036] 2. Set up an on-site welding operation platform.

[0037] 3. The workshop manufactures the steel liner plate 3, and preferably uses the leftover materials for processing, and preferably uses laser cutting for cutting. Laser cutting has a smooth cut surface and less oxide. The liner plate 3 uses the same Q355C material as the parent material, where the thickness of the liner plate 3 is 8mm, the length is 500mm, and the height is 30mm. After the steel liner plate 3 is cut according to the controlled size, oxides, burrs, etc. are cleaned, and the surface is flat.

[0038] 4. The workshop installs the steel backing plate 3. A gap D of 2 mm is left between the top surface of the steel backing plate 3 and the bottom of the first steel member 1 and the second steel member 2. The specific way to leave the gap D is to clamp the two magnetic supports 44 in the aforementioned way, and the spacing between the center points of the two magnetic supports 44 is 150 mm. The center of the backing plate 3 is directly opposite the center of the weld gap between the first steel member 1 and the second steel member 2. Neodymium iron boron permanent magnet sheets 45 are used to assist in fixing the backing plate 3 and determining the gap D. It is preferred to use neodymium iron boron permanent magnet sheets 45 for installation, and there are 2 neodymium iron boron permanent magnet sheets 45. The edge of the steel backing plate 3 is fixed to the first steel member 1 and the second steel member 2 by corner weld spot welding, with a spot welding length of 20 mm, a spacing of 300 mm, and a weld leg size of 8 mm. Only one side of the steel backing plate 3 is welded to the first steel member 1 and the second steel member 2, and the other side does not need to be welded. After the steel backing plate 3 is welded and fixed in this way, the operator can avoid entering the box to paste the ceramic backing, which greatly improves the welding efficiency. After the backing is welded and fixed, the magnetic support 44 of the backing positioning device 4 is pulled out.

[0039] 5. The main weld area between the first steel component 1 and the second steel component 2 is purged and cleaned on site.

[0040] 6. The main weld shall be welded according to the welding process and parameters of the welding process assessment. Solid welding wire, flux-cored welding wire, gas shielded welding, submerged arc welding, manual welding, robot welding, etc. can be used with corresponding process parameters.

[0041] This welding method is suitable for various welding positions. According to experimental tests, under the same welding conditions, the technical solution is used to perform single-sided welding and double-sided forming process welding in horizontal welding, vertical welding, and overhead welding positions. The average pass rate of one welding is 98.5%, which is 11.5 percentage points higher than the average pass rate of 87% of conventional welding methods, and the pass rate deviation is smaller and the pass rate is more stable. The increase in the pass rate means the reduction of the rework rate. In addition to consuming the same welding auxiliary materials and working hours during rework, the carbon rod, electricity, and labor costs consumed by carbon arc gouging are also increased. The increased carbon arc gouging working hours are about 1 / 3 of the welding working hours. The reduction in the rework rate also reduces the pollution to the environment by carbon arc gouging and welding.

Claims

1. A method for welding a butt weld of a steel plate, comprising a liner positioning device (4), It is characterized in that The steps include: a. Check the component dimensions and the weld gap and blunt edge dimensions between the first steel component (1) and the second steel component (2) according to the BIM model data and design drawing requirements, and perform groove surface pretreatment; b. manufacturing a lining plate (3), wherein the lining plate (3) is made of the same material as the first steel component (1) and the second steel component (2), and after the lining plate (3) is cut according to size, the oxides and burrs of the lining plate (3) are cleaned to ensure a smooth surface; c. The pad positioning device (4) comprises a connecting rod (42), the connecting rod (42) is U-shaped, and magnetic supports (44) are arranged at both free ends of the connecting rod (42), a magnetic part is fixedly arranged on the magnetic support (44), the thickness of the magnetic support (44) is equal to the gap (D) between the pad plate (3) and the steel structure, the distance between the center points of the two magnetic supports (44) is less than the length of the pad plate (3), and a handle (41) is arranged at the bend of the middle section of the U-shaped connecting rod (42); The two magnetic supports (44) of the connecting rod (42) of the pad positioning device (4) are arranged between the pad plate (3) and the first steel component (1) and the second steel component (2); the two magnetic supports (44) are adsorbed on the bottom of the first steel component (1) and the second steel component (2) through magnetic parts; the top surface of the pad plate (3) is closely attached to the magnetic supports (44); and the gap (D) between the top surface of the pad plate (3) and the bottom of the first steel component (1) and the second steel component (2) is 2 to 3 mm; d. Fixing the liner plate (3) to the first steel member (1) and the second steel member (2) by spot welding with fillet welds, and then pulling out the liner positioning device (4); e. Purge and clean the weld area and then complete the remaining welding process.

2. The welding method for the butt weld of steel plates according to claim 1, Features: In step a, when the first steel member (1) and the second steel member (2) cannot be deformed after welding, or when the first steel member (1) and the second steel member (2) are curved parts, an anti-deformation fixture is installed to fix the first steel member (1) and the second steel member (2) in place and shape, so as to prevent the first steel member (1) and the second steel member (2) from being deformed due to welding thermal stress.

3. The welding method for the butt weld of steel plates according to claim 1, Features: In step b, the liner plate (3) is processed by using the leftover scraps of the steel structure and cut by laser.

4. The welding method for a steel plate butt weld according to claim 1, Features: In step b, the dimension parameters of the backing plate (3) are as follows: Thickness t of the backing plate (3): 5≤t≤T min / 2, unit: mm, T min is the thickness value of the smaller one of the first steel component (1) and the second steel component (2); Length a of the backing plate (3): 300≤a≤2sqrt((R min +1) 2 -R min 2 )), unit: mm, R min The radius value of the maximum curvature of the current surface weld line shape; Height h of the backing plate: h = δ max +20 and 30≤h≤50, unit: mm, δ max is the maximum value of the weld gap.

5. The welding method for the butt weld of steel plates according to claim 1, Features: In step c, the distance between the center points of the two magnetic supports (44) is equal to one third of the length of the backing plate (3).

6. The welding method for a butt weld of steel plates according to any one of claims 1 to 5, Features: The magnetic support (44) includes a fixed edge and a positioning edge, the fixed edge and the positioning edge are perpendicular to each other to form an L shape, the fixed edge of the magnetic support (44) is fixedly arranged at the end of one end of the connecting rod (42), the magnetic part is arranged on the positioning edge of the magnetic support (44), and the thickness of the positioning edge of the magnetic support (44) is equal to the gap (D) between the lining plate (3) and the steel structure.

7. The welding method for a butt weld of steel plates as claimed in claim 6, Features: The magnetic component is a neodymium iron boron permanent magnet sheet (45).

8. The method for welding a butt weld of steel plates as claimed in claim 6, Features: The connecting rod (42) is a bent structure, and the extension direction of the axis of the handle (41) is parallel to the extension direction of the positioning edge of the magnetic support (44).

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