Welding method for improving nondestructive testing qualified rate of main welding seam of curve steel box bridge

Abstract

The invention relates to the field of steel structural part welding processes, in particular to a welding method for improving the nondestructive testing qualification rate of a main welding seam of a curve steel box bridge, which is suitable for welding of a welding seam with a large gap, and comprises the following steps: a, according to BIM model data and a design drawing, carrying out part cutting blanking and welding groove treatment; b, a bottom plate, a top plate and a web plate are assembled on the ground tire through a forward assembling method or a reverse assembling method, and after the assembling size is checked to be qualified, spot welding is conducted for firm fixing; c, a liner plate is manufactured, and the liner plate, the bottom plate and the top plate are made of the same material; d, arranging two zirconia ceramic rods of a connecting rod of the liner positioning device between the bottom of the liner plate and the bottom plate; e, the side, tightly attached to the web, of the liner plate is fixed through fillet weld spot welding, and then the liner positioning device is pulled out; and f, the welding position area of the main welding seam is purged and cleaned, and the remaining welding process is completed. The method is suitable for the welding process of the main welding seam of the curved steel box bridge.

Description

Technical Field

[0001] The invention relates to the field of steel structure welding technology, in particular to a welding method for improving the non-destructive testing pass rate of main welds of curved steel box bridges. Background Art

[0002] The main welds between the web and top plate, and between the web and bottom plate of a curved steel box bridge are usually full penetration fillet welds. After welding, nondestructive testing is required to determine the weld qualification. If there are defects in the detection, the weld needs to be planed and reworked, resulting in losses in welding auxiliary materials, welding energy, labor, construction period, etc. Due to the poor working conditions during welding inside the box and the large safety risks of welding in closed spaces, single-sided welding and double-sided forming welding processes are now mostly used. The main welds of a curved steel box bridge are irregular curves, and it is difficult to achieve complete standardization of the welding gap control between the top plate and the web, and between the bottom plate and the web, which further makes it difficult to stabilize the welding qualification rate at a high level.

[0003] Taking the patent CN114346383A, named "A submerged arc welding single-sided welding and double-sided forming process" as an example, the patent discloses the process steps of pretreatment, grooving, welding and other process steps for the pipe base material weld. Among them, the overall solution is a conventional welding process, and the main defects are as follows: There are the following main disadvantages: 1. The welding cost caused by the ceramic liner itself is greatly increased; 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 base 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 gravity of the molten pool, which has an adverse effect on the welding process. 4. The ceramic liner has certain requirements for the size of the weld gap of the base material assembly. The uneven gap has a greater impact on the welding pass rate, and larger gaps cannot be welded. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a welding method suitable for welding of welds with larger gaps and improving the non-destructive testing pass rate of main welds of curved steel box bridges.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a welding method for improving the non-destructive testing pass rate of the main weld of a curved steel box bridge, including a liner positioning device, comprising the following steps:

[0006] a. According to the BIM model data and design drawings, parts cutting and welding groove processing are carried out, and the bottom plate, top plate and web plate are respectively made on the ground tire. After completing the above production, the size and weld inspection need to be tested;

[0007] b. Assemble the bottom plate, top plate and web plate on the ground tire by the upright or inverted method. After the assembly dimensions are checked to be qualified, spot weld them to fix them firmly, and check the assembly dimensions again to confirm that they are correct;

[0008] c. Make the lining plate, which is made of the same material as the bottom plate and the top plate;

[0009] d. Place two zirconia ceramic rods of the connecting rod of the liner positioning device between the bottom of the liner plate and the base plate, and adsorb the permanent magnet rod on the liner plate. The gap between the bottom of the liner plate and the base plate is 3 to 5 mm.

[0010] e. Fix the side of the liner plate that is in close contact with the web plate by spot welding with a fillet weld, and then pull out the liner positioning device;

[0011] f. Purge and clean the main weld area between the web and bottom plate, and then complete the remaining welding process.

[0012] Furthermore, in step c, the liner plate is processed using leftover scraps and cut using laser cutting.

[0013] Furthermore, in step c, the thickness t of the liner plate is: 5≤t≤T min / 2, unit: mm, T min It is the smaller thickness value between the web plate and the bottom plate.

[0014] Furthermore, the length a of the liner plate: 300≤a≤2sqrt((R min +1) 2 -R min 2 )), unit: mm, R min When the web is a curved surface, it is the smaller radius of the horizontal curve of the web and the vertical curve of the web.

[0015] Furthermore, the height h of the backing plate is: h = δ max +20 and 30≤h≤50, unit: mm, δ max is the maximum value of the weld gap.

[0016] Furthermore, in step d, the pad positioning device includes a connecting rod, which is U-shaped, and both ends of the connecting rod are provided with fixing clips, which are perpendicular to the ends of the connecting rod, a zirconia ceramic rod is provided at the bottom of the fixing clip, and a permanent magnet rod is provided at the top of the fixing clip, the zirconia ceramic rod and the permanent magnet rod are parallel to the ends of the connecting rod, the diameter of the zirconia ceramic rod is equal to the size of the gap between the bottom of the pad plate and the bottom plate, the distance between the center points of the two fixing clips is less than the length of the pad plate, and a handle is provided at the bend of the middle section of the U-shaped connecting rod.

[0017] Furthermore, an auxiliary fixing clip is provided between the end of the connecting rod and the permanent magnet bar.

[0018] Furthermore, an auxiliary fixing clip is provided between the end of the connecting rod and the zirconia ceramic rod.

[0019] The beneficial effects of the present invention are as follows: 1. Instead of using high-cost ceramic liners, they are made of basically useless steel plate waste, which is a recycling of waste materials, thereby reducing welding costs. 2. The liners themselves will not fall off, and the deposited metal has good adhesion, which is easy to weld, reducing the difficulty of welding 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 of the curved structure is difficult to be completely uniform. Therefore, it has a higher and more stable welding pass rate than ceramic liners, and 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 increased safety risks caused by rework, and reduces the environmental pollution caused by welding fumes. 4. It also belongs to the single-sided welding and double-sided forming welding process, which avoids welding inside the box, avoids an unfavorable working environment, and at the same time avoids safety risks such as suffocation during welding inside the box. The present invention is particularly suitable for the welding process of the main weld of a curved steel box bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of an embodiment of a pad positioning device of the present invention.

[0021] Figure 2 It is a schematic diagram of the positional relationship between the liner positioning device of the present invention and the liner plate, the web plate and the bottom plate.

[0022] Figure 3 yes Figure 2 Oblique view of .

[0023] Marked in the figure are: gasket positioning device 10, handle 1, round sealing plate 2, connecting rod 3, auxiliary fixing card 4, fixing card 5, permanent magnet rod 6, zirconia ceramic rod 7, gasket plate 8, web plate 9, bottom plate 91, gap D. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] like Figure 1 , Figure 2 , Figure 3 , the specific structure of the liner positioning device 10, and the matching relationship between the liner positioning device 10 and the liner plate 8, the web plate 9, and the bottom plate 91. Figure 1As shown, the liner positioning device 10 includes a connecting rod 3, which is U-shaped and provides basic support during welding. The U-shaped structure can be simultaneously provided with fixing clips 5 at both ends of the U-shaped structure, that is, both ends of the connecting rod 3 are provided with fixing clips 5. The fixing clips 5 are perpendicular to the ends of the connecting rod 3, a zirconia ceramic rod 7 is provided at the bottom of the fixing clip 5, and a permanent magnet rod 6 is provided at the top of the fixing clip 5. The zirconia ceramic rod 7 and the permanent magnet rod 6 are both perpendicular to the fixing clip 5, and the zirconia ceramic rod 7 and the permanent magnet rod 6 are parallel to the ends of the connecting rod 3. The diameter of the zirconia ceramic rod 7 is equal to the size of the gap D between the bottom of the liner plate 8 and the bottom plate 91, and the commonly used gap D is 4 to 5 mm. The distance between the center points of the two fixing clips 5 is less than the length of the liner plate 8, and a handle 1 is provided at the bend of the middle section of the U-shaped connecting rod 3. The permanent magnet rod 6 and the zirconia ceramic rod 7 pass through the fixing card 5 respectively, and then are bonded to the auxiliary fixing card 4. The remaining parts except the permanent magnet rod 6 and the zirconia ceramic rod 7 can be made of Q235B steel and are welded to each other.

[0026] Figure 2 The figure shows a schematic diagram of an embodiment when the web 9 and the bottom plate 91 are welded. Based on the same welding principle, the bottom plate 91 can also be replaced by the top plate to realize the welding process of the web 9 and the top plate. In this embodiment, the corresponding welding structure is illustrated by welding the web 9 and the bottom plate 91. In actual operation, the handle 1 of the pad positioning device 10 is held by hand, and the angle is adjusted so that the fixing cards 5 at the two ends of the connecting rod 3 are set on the bottom plate 91, and the bottom edge of the zirconia ceramic rod 7 is tangent to the top surface of the bottom plate 91. The spacing between the fixing cards 5 at the two ends of the connecting rod 3 is 1 / 3 of the length of the liner plate 8, and the connecting rod 3 is placed in the center. The zirconia ceramic rod 7 extends into the bottom of the liner plate by 3 to 5 mm. If it is too short, the liner plate 8 is easy to fall off. If it is too long, it is not conducive to the subsequent removal of the liner plate 8. Subsequently, the lowest edge of the backing plate 8 is set on the zirconia ceramic rod 7 in the vertical direction. At this point, the gap D between the lowest edge of the backing plate 8 and the top surface of the bottom plate 91 is just equal to the outer diameter of the zirconia ceramic rod 7. The zirconia ceramic rod 7 is used to assist in determining the gap D. This method of determining the gap D can avoid the sparking phenomenon that may be caused when using welding wire or other metals to assist in determining the gap, thereby preventing the smoothness and cleanliness of the welding surface at the root of the weld from being affected. In this embodiment, the outer diameter of the zirconia ceramic rod 7 is 5mm. Subsequently, the web 9 is set tightly against the side of the backing plate 8 in the vertical direction. Then, the corner welds are spot welded to the sides where the backing plate 8 and the web 9 are tightly attached, and the backing plate 8 and the web 9 are fixed into an integrated structure. Generally, the preferred spot welding length is 20mm≤L1≤40mm, the spacing is 250mm≤L≤350mm, and the weld foot size is 5mm≤h f≤t, commonly used spot welding length is 20mm, spacing is 300mm, and weld leg size is 5mm. The commonly used sizes of spot welding length, spacing, and weld leg are the minimum sizes. Smaller sizes are prone to cause the gasket to deform and fall off due to heat during the main weld welding process. After the gasket is welded and fixed, pull out the gasket positioning device 10. Finally, the main weld welding area between the lowest edge of the gasket plate 8 and the top surface of the web 9 and the bottom plate 91 is purged and cleaned, and then the main weld is 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 welded with corresponding process parameters.

[0027] As for the lining plate 8, its material is preferably consistent with the material of the web 9 and the bottom plate 91. Taking the steel lining plate 8 as an example, its specifications are preferably as follows: the thickness t of the lining plate: 5≤t≤T min / 2, unit: mm, T min The smaller thickness of the two parent materials of the main weld. If the backing plate 8 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 commonly used thickness is 5mm or 8mm. The length of the backing plate a: 300≤a≤2sqrt((R min +1) 2 -R min 2 )), unit: mm, R min When the web 9 is a curved surface, the smaller radius of the flat curve of the web 9 and the vertical curve of the web 9 is used. The length a of the backing plate is determined to control the minimum and maximum values ​​of the plate length when the gap distance deviation between the backing plate 8 and the curved surface base material of the web 9 is between 0 and 1 mm, thereby further improving the welding quality. The height h of the backing plate 8: h = δ max +20 and 30≤h≤50, unit: mm, δ max The maximum value of the weld gap. After the backing plate 8 is cut according to the size, the oxides, burrs, etc. are cleaned and the surface is flat. By limiting the size specifications of the backing plate 8, it is possible to effectively deal with the unfavorable situation that the gap of special-shaped welds such as curves is difficult to be accurately consistent, and it is also suitable for welding welds with larger gaps.

[0028] Example

[0029] Take the main weld welding between the web 9 and the bottom plate 91 of a curved steel box bridge made of Q355C material and 20 mm thick as an example.

[0030] 1. According to the BIM model data and the detailed design drawings, the parts are cut and blanked and the welding grooves are processed. The bottom plate 91, the top plate and the web plate 9 are respectively completed on the ground tire, including the assembly and welding of the respective stiffening ribs of the diaphragm. Through this step, each assembly unit has a good anti-deformation ability. After the production of each assembly unit is completed, the size and weld inspection are required to be qualified.

[0031] 2. Assemble the bottom plate 91, top plate, web plate 9 and diaphragm on the ground tire by the normal assembly method. After the assembly dimensions are checked and qualified, the above components are spot welded and fixed firmly, and the assembly dimensions are checked again to confirm that they are correct. If the unit assembly method is not adopted, but the direct assembly method of parts is adopted, the steel box bridge will be greatly deformed when welding the main weld, which is very unfavorable to the control of the linear shape of the curved steel box bridge after forming.

[0032] 3. During assembly, steel backing plate 8 is made, and it is preferred to use leftover materials for processing, and laser cutting is preferred for cutting. Laser cutting has a smooth cut surface and less oxide. Backing plate 8 is made of Q355C material, which is the same as the parent material, according to the parent material. If the steel box girder with common curve curvature is welded, the specifications of backing plate 8 can be: backing plate 8 thickness 8mm, length 500mm, height 30mm. After cutting and cutting the backing plate 8 according to the controlled size, clean the oxides, burrs, etc., and the surface is flat.

[0033] 4. Install the backing plate 8: Place the backing plate 8 in the vertical direction, with the right side wall of the backing plate 8 close to the web 9, and a gap of 5mm is left between the bottom of the backing plate 8 and the top surface of the base plate 91. Zirconia ceramic rods 7 with an outer diameter of 5mm are used to determine the gap, and the spacing between the axes of the two zirconia ceramic rods 7 is 150mm. The side edges where the backing plate 8 and the web 9 are close to each other are spot welded to fix the backing plate 8 and the web 9 to form an integrated structure. The spot welding length is 20mm, the spacing is 300mm, and the weld foot size is 5mm. After the backing plate 8 is welded and fixed, pull out the backing positioning device 10. At this time, the gap between the bottom of the backing plate 8 and the top surface of the base plate 91 is 5mm.

[0034] 5. Blow and clean the main weld area between the web 9 and the bottom plate 91.

[0035] 6. According to the welding process and parameters of the welding process assessment, the main weld shall be welded. Solid welding wire, flux-cored welding wire, gas shielded welding, submerged arc welding, manual welding, robot welding, etc. can be used in conjunction with corresponding process parameters.

[0036] This process method significantly improves the non-destructive testing pass rate of the main welds of curved steel box bridges, and 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, vertical and overhead welding positions. The average pass rate of one-time welding is more than 98%, which is more than 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 in 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 caused by carbon arc gouging and welding.

Claims

1. A welding method for improving the nondestructive testing pass rate of the main weld of a curved steel box bridge, comprising a liner positioning device (10), characterized in that: The steps include: a. According to the BIM model data and design drawings, parts are cut and blanked and welding grooves are processed to produce the bottom plate (91), the top plate and the web plate (9) on the ground tire. After the above production is completed, the dimensions and weld seams need to be inspected and checked to be qualified; b. Assemble the bottom plate (91), the top plate and the web plate (9) on the ground tire by the upright or inverted method. After the assembly dimensions are checked to be qualified, spot weld them to fix them firmly, and check the assembly dimensions again to confirm that they are correct; c. Making a lining plate (8), wherein the lining plate (8) is made of the same material as the bottom plate (91) and the top plate; d. The two zirconia ceramic rods (7) of the connecting rod (3) of the liner positioning device (10) are arranged between the bottom of the liner plate (3) and the bottom plate (91), and the permanent magnetic rod (6) is adsorbed on the liner plate (3), and the gap (D) between the bottom of the liner plate (3) and the bottom plate (91) is 3 to 5 mm; e. Fix the side of the liner plate (8) that is in close contact with the web plate (9) by spot welding with a fillet weld, and then remove the liner positioning device (10); f. The main weld area between the web (9) and the bottom plate (91) is purged and cleaned, and then the remaining welding process is completed.

2. The welding method for improving the nondestructive testing pass rate of the main weld of a curved steel box bridge according to claim 1, characterized in that: In step c, the liner plate (8) is processed using leftover scraps and cut using laser cutting.

3. The welding method for improving the nondestructive testing pass rate of the main weld of a curved steel box bridge according to claim 1 or 2, characterized in that: In step c, the thickness t of the liner plate (8) is: 5≤t≤T min / 2, unit: mm, T min It is the smaller thickness value between the thickness of the web (9) and the thickness of the bottom plate (91).

4. The welding method for improving the nondestructive testing pass rate of the main weld of a curved steel box bridge according to claim 3, characterized in that: Length a of the backing plate (8): 300≤a≤2sqrt((R min +1) 2 -R min 2 )), unit: mm, R min When the web (9) is a curved surface, the smaller radius value between the radii of the horizontal curve of the web (9) and the vertical curve of the web (9) is obtained.

5. The welding method for improving the nondestructive testing pass rate of the main weld of a curved steel box bridge according to claim 3, characterized in that: 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.

6. The welding method for improving the nondestructive testing pass rate of the main weld of a curved steel box bridge according to claim 1 or 2, characterized in that: In step d, the pad positioning device (10) includes a connecting rod (3), the connecting rod (3) is U-shaped, and both ends of the connecting rod (3) are provided with fixing clips (5), the fixing clips (5) are perpendicular to the ends of the connecting rod (3), a zirconia ceramic rod (7) is provided at the bottom of the fixing clip (5), and a permanent magnet rod (6) is provided at the top of the fixing clip (5), the zirconia ceramic rod (7) and the permanent magnet rod (6) are parallel to the ends of the connecting rod (3), the diameter of the zirconia ceramic rod (7) is equal to the size of the gap (D) between the bottom of the pad plate (8) and the bottom plate (91), the distance between the center points of the two fixing clips (5) is less than the length of the pad plate (8), and a handle (1) is provided at the bend of the middle section of the U-shaped connecting rod (3).

7. The welding method for improving the nondestructive testing pass rate of the main weld of a curved steel box bridge according to claim 6, characterized in that: An auxiliary fixing clamp (4) is provided between the end of the connecting rod (3) and the permanent magnetic rod (6).

8. The welding method for improving the nondestructive testing pass rate of the main weld of a curved steel box bridge according to claim 7, characterized in that: An auxiliary fixing clamp (4) is provided between the end of the connecting rod (3) and the zirconium oxide ceramic rod (7).

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