Cylindrical steel structural part welding method

Abstract

The invention relates to the field of steel structural part welding processes, in particular to a cylindrical steel structural part welding method suitable for weld joint welding under the condition of a large gap, which comprises a backing plate and comprises the following steps of: a, checking the size of a component and the size of a weld joint gap and a truncated edge between a first steel component and a second steel component; b, manufacturing a liner plate; c, a magnetic support at one end of a connecting rod of the gasket positioning device is arranged between a whole formed by the first steel member and the second steel member and the gasket plate, and the magnetic support is attracted to the bottom of the first steel member and the bottom of 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 cylindrical steel structural parts.

Description

Technical Field

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

[0002] Large cylindrical 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 is completed, non-destructive testing is required to determine the weld qualification. If defects are found during the inspection, 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 pipe to paste the ceramic liner, which is cumbersome.

[0003] Taking the patent with announcement number CN108687428A, named "Single-sided welding and double-sided forming fillet welding submerged arc welding method" as an example, a common welding process is involved. When butt-jointing cylindrical steel structural parts, a single-sided welding and double-sided forming process with ceramic pads is adopted. However, during the welding process, the adhesive of the ceramic pad is easy to fall off, which has a great impact on the welding progress and quality. During the assembly and installation welding process of cylindrical steel components, the same butt joint may involve butt welds of horizontal welding, vertical welding, overhead welding and other welding positions. These welds use ceramic pads, which have 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 butt joints during on-site installation, it is necessary to paste and install the ceramic pad inside the pipe, which is not conducive to improving construction efficiency, and there are construction safety hazards in the operation inside the box. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a welding method for cylindrical steel structural parts which is suitable for welding a weld seam when the gap between a first steel member to be welded and a second steel member is relatively large.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for welding a cylindrical steel structure, including a backing plate, comprises 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 lining plate, wherein the lining plate is made of the same material as the first steel member and the second steel member, and after the lining plate is cut according to size, the oxide and burrs of the lining plate are cleaned;

[0008] c. The magnetic support at one end of the connecting rod of the liner positioning device is arranged between the whole formed by the first steel member and the second steel member and the liner plate. The magnetic support is adsorbed on the bottom of the first steel member and the second steel member through a magnetic part. The top surface of the liner plate is in close contact with the magnetic support. The gap between the top surface of the liner plate and the bottom of the first steel member and the second steel member is 2 to 3 mm.

[0009] 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;

[0010] e. Purge and clean the weld area and then complete the remaining welding process.

[0011] Furthermore, in step a, when the component is a rolled welded steel pipe, the rolled welded steel pipe is inspected and corrected for roundness, and an annular stiffening rib is added to the steel pipe wall.

[0012] Furthermore, in step b, the liner plate is processed by using the leftover scraps of the steel structure and cut by laser.

[0013] Furthermore, in step b, the dimension parameters of the backing plate are as follows:

[0014] Thickness t: 5≤t≤T / 2, unit: mm, T is the wall thickness of the butt-jointed steel pipe;

[0015] Theoretical radius r' of liner plate rolling: r'=RT-2, unit: mm, R is the outer wall radius of the current steel pipe, T is the wall thickness of the butt steel pipe, and the allowable deviation of the liner plate radius is [-5%, 0);

[0016] Arc length a of the backing plate: πr / 3≤a≤(180°-arccos(((Rr-2) 2 +(r+3) 2 -R 2 ) / (2*(Rr-2)*(r+3))))*2 / 360°*2πr, and a=πr / n, unit is mm, R is the outer wall radius of the current steel pipe, r is the outer radius of the liner plate, and n is a positive integer;

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

[0018] Furthermore, the pad positioning device includes a connecting rod, one end of which is provided with a magnetic support, on which a magnetic part is fixedly provided, the thickness of the magnetic support is equal to the gap between the pad plate and the steel structure, and the other end of the connecting rod is provided with a handle.

[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 accuracy of the weld gap size 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 pipe components are butt-jointed and assembled on site, there is no need to enter the pipe to paste the ceramic liner, and welding is convenient. The present invention is particularly suitable for welding processes with large welding gaps of cylindrical steel structural parts. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0025] Figure 3 Schematic diagram of an embodiment of a pad positioning device of the present invention.

[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 Shown is an embodiment of the pad positioning device 4 and the positional relationship between the pad positioning device 4 and the first steel member 1, the second steel member 2 and the pad plate 3 during welding. The pad positioning device 4 first includes a connecting rod 42. The connecting rod 42 can be a bent structure, so that the construction personnel can 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 magnetic support 44 is an L-shaped bending structure. The L-shaped bending structure includes a fixed edge and a positioning edge that are perpendicular to each other. The fixed edge and the positioning edge are welded with Q235B steel plates. The fixed edge of the magnetic support 44 is Figure 3 The structure fixedly connected to one end of the connecting rod 42, the positioning edge of the magnetic support 44 is Figure 3 The 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 is evenly applied to the exposed part of the NdFeB permanent magnet sheet 45 to protect the permanent magnet sheet.

[0030] In actual use, the operator holds the handle 41 and sets the positioning edge of the magnetic support 44 at 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 sheet 45 is adsorbed on the bottom of the first steel component 1 and the second steel component 2 to fix the magnetic support 44. Subsequently, the 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. The spot welding length is 20mm≤L1≤40mm, the spacing is 250mm≤L≤350mm, and the weld foot size is 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 design drawing requirements, and perform groove surface pretreatment; when the component is a rolled welded steel pipe, check and correct the roundness of the rolled welded steel pipe, and add annular stiffening ribs to the steel pipe with thinner wall; b. Make a lining plate 3, which is made of the same material as the first steel component 1 and the second steel component 2. After the lining plate 3 is cut according to the size, clean the oxide and burrs of the lining plate 3 to ensure a smooth surface; the lining plate 3 is made of the leftover scraps of the steel structure. Processing, laser cutting is used for blanking; c. The magnetic support 44 at one end of the connecting rod 42 of the gasket positioning device 4 is set between the gasket plate 3 and the first steel component 1 and the second steel component 2. The magnetic support 44 is adsorbed on the bottom of the first steel component 1 and the second steel component 2 through the magnetic part. The top surface of the gasket plate 3 is close to the magnetic support 44. The gap D between the top surface of the gasket plate 3 and the bottom of the first steel component 1 and the second steel component 2 is 2 to 3 mm; d. The gasket plate 3 and the first steel component 1 and the second steel component 2 are fixed by spot welding of the fillet weld, and then the gasket 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 component 1 and the second steel component 2 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 welded with corresponding process parameters.

[0032] As the core component of welding, the backing plate 3 needs to adapt to and match the outer contour surface 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 size parameters of the backing plate 3 are preferably as follows: thickness t: 5≤t≤T / 2, unit mm, T is the wall thickness of the butt steel pipe; the theoretical radius r' of the backing plate rolling: r'=RT-2, unit mm, R is the outer wall radius of the current steel pipe, T is the wall thickness of the butt steel pipe, and the allowable deviation of the backing plate radius is [-5%, 0); the arc length a of the backing plate: πr / 3≤a≤(180°-arccos(((Rr-2)2 +(r+3) 2 -R 2 ) / (2*(Rr-2)*(r+3))))*2 / 360°*2πr, and a=πr / n, unit is mm, R is the outer wall radius of the current steel pipe, r is the outer radius of the liner plate, n is a positive integer; the height h of the liner plate: h=δ max +20 and 30≤h≤50, unit: mm, δ max is the maximum value of the weld gap.

[0033] Example

[0034] The following example takes the on-site assembly and welding of the R800 arch rib of a landscape bridge steel pipe, Q355C material, and 20mm wall thickness butt joints.

[0035] 1. According to the BIM model data and the requirements of the in-depth 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 docking interface of 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.

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

[0037] 3. The workshop manufactures the steel backing plate 3 and installs it to the docking interface of the circular tube arch rib at the lower end of the first steel member 1 and the second steel member 2. The steel backing plate 3 manufactured by the workshop is preferably processed with scraps and is preferably cut with laser cutting. The cut surface of the laser cutting is smooth and has less oxide. In this embodiment, the steel backing plate 3 is made of the same Q355C material as the parent material. The thickness of the steel backing plate 3 is 8mm, the arc length is 348mm, and the height is 30mm. After the steel backing plate 3 is cut and cut according to the controlled size, oxides, burrs, etc. are cleaned and the surface is smooth.

[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 magnetic support 44 in the above-mentioned way. The center of the backing plate 3 is directly opposite to the center of the weld gap between the first steel member 1 and the second steel member 2. A neodymium iron boron permanent magnet sheet 45 is used to assist in fixing the backing plate 3 and determining the gap D. Preferably, a neodymium iron boron permanent magnet sheet 45 is used for installation. There is one neodymium iron boron permanent magnet sheet 45, which is fixed at the center position of the positioning edge of the magnetic support 44. The edge of the steel backing plate 3 is fixed to the first steel member 1 and the second steel member 2 by spot welding with a fillet weld. The spot welding length is 20 mm, the spacing is 300 mm, and the weld leg size is 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. Remove the protective film of the main weld area between the first steel component 1 and the second steel component 2 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%, which is 11 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 cylindrical steel structure, comprising a backing plate (3), 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, oxides and burrs on the lining plate (3) are cleaned; c. The magnetic support (44) at one end of the connecting rod (42) of the pad positioning device (4) is arranged between the whole formed by the first steel member (1) and the second steel member (2) and the pad plate (3), the magnetic support (44) is adsorbed on the bottom of the first steel member (1) and the second steel member (2) through a magnetic part, the top surface of the pad plate (3) is closely attached to the magnetic support (44), and the gap (D) between the top surface of the pad plate (3) and the bottom of the first steel member (1) and the second steel member (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 cylindrical steel structure welding method according to claim 1, characterized in that: In step a, when the component is a rolled welded steel pipe, the rolled welded steel pipe is inspected and corrected for roundness, and an annular stiffening rib is added to the steel pipe wall.

3. The cylindrical steel structure welding method according to claim 1, characterized in that: In step b, the liner plate (3) is processed by using the leftover scraps of the steel structure and cut by laser.

4. The cylindrical steel structure welding method according to claim 2, characterized in that: In step b, the dimension parameters of the backing plate (3) are as follows: Thickness t: 5≤t≤T / 2, unit: mm, T is the wall thickness of the butt-jointed steel pipe; Theoretical radius of liner plate rolling r': r' = RT-2, unit: mm, R is the outer wall radius of the current steel pipe, T is the wall thickness of the butt steel pipe, and the allowable deviation of the liner plate radius is [-5%, 0); Arc length a of the backing plate: πr / 3≤a≤(180°-arccos(((Rr-2) 2 +(r+3) 2 -R 2 ) / (2*(Rr-2)*(r+3))))*2 / 360°*2πr, and a=πr / n, unit is mm, R is the outer wall radius of the current steel pipe, r is the outer radius of the liner plate, and n is a positive integer; 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 cylindrical steel structure welding method according to any one of claims 1 to 4, characterized in that: The pad positioning device (4) comprises a connecting rod (42), one end of which is provided with a magnetic support (44), a magnetic part is fixedly provided on the magnetic support (44), the thickness of the magnetic support (44) is equal to the size of the gap (D) between the pad plate (3) and the steel structure, and the other end of the connecting rod (42) is provided with a handle (41).

6. The cylindrical steel structure welding method according to claim 5, characterized in that: 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 cylindrical steel structure welding method according to claim 6, characterized in that: The magnetic component is a neodymium iron boron permanent magnet sheet (45).

8. The cylindrical steel structure welding method according to claim 6, characterized in that: 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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