A method for manufacturing a dense structure by unconventional assembly and welding

Abstract

The application discloses a dense structure unconventional welding manufacturing method, which is used for realizing welding of full penetration t-shaped butt welds of dense plates and metal parent plates, the thickness of the dense plate is not less than 26 mm, one side of the dense plate is provided with an obstacle plate, the ratio of the height of the obstacle plate to the distance from any point on the obstacle plate to the dense plate is not less than tan52°, the distance from any point on the obstacle plate to the dense plate is not greater than the distance for welding equipment or people to pass, the method comprises the following steps: setting the cutting angle and depth of the inner and outer side grooves, and adopting the method of welding first on the inner side shallow groove and welding later on the outer side deep groove after side cleaning.

Description

Technical Field

[0001] This invention relates to the field of steel structure manufacturing and welding technology, and in particular to an unconventional welding manufacturing method for dense structures. Background Technology

[0002] In welding, dense structures refer to the closely arranged structures formed during the welding process. The continuity and strength of these dense structures with the base metal are crucial. Steel anchor boxes in steel bridge structures are examples of dense structures in steel fabrication. The anchor box structure is installed on the outer side of the web plate. The anchor box mainly consists of anchor plates, anchor bearing plates, force transmission webs, stiffening plates, and anchor pipes. Anchor plates are welded to one side of the anchor bearing plate and have a through-hole for the cable to pass through. Force transmission webs are vertically welded to the other side of the anchor bearing plate at intervals. Stiffening plates are vertically installed along the outer wall of the force transmission webs and extend along the height of the webs, and are arranged in parallel at intervals along the width of the webs. The anchor pipes are sleeved on the outside of the stiffening plates and are cylindrical in shape on the upper part of the force transmission webs.

[0003] When plates are joined to the base material by welding, double-sided beveling is required for easily weldable materials such as carbon steel and low-alloy steel with a plate thickness between 12 and 26 mm. For difficult-to-weld materials such as stainless steel with a plate thickness between 7 and 30 mm, double-sided beveling is also required. When the plate thickness exceeds 26 mm, it is considered an ultra-thick plate. If a single-sided beveling welding process is used, the filler metal area becomes too wide. When the welding rod melts and fills the filler metal, it is not easy to fully fuse and mix with the plate and base material, easily forming an unfused zone, which affects the strength and density of the weld joint. Furthermore, the filler metal area has a high temperature and a large area, and the high temperature lasts for a long time, which can cause changes in the microstructure and properties of the base material in contact. Therefore, double-sided beveling is required for welding the plates.

[0004] The main challenge in manufacturing dense structures in steel structures lies in the small spacing and high height of adjacent plates to be welded to the base metal. This results in a large welding angle on opposite sides of the plates, making it difficult to fully fill the bevels with molten alloy. Dense structures are difficult to symmetrically bevel for welding and assembly, often requiring a single-sided bevel with steel backing. This leads to a large amount of welding, high consumption of welding materials, long welding time, and angular deformation shrinking to one side, resulting in excessive joint stress and overall deformation. Furthermore, the use of steel backing also results in poor fatigue performance of the welded joint. Only by adopting a new joint type and construction method can product manufacturing be carried out. Summary of the Invention

[0005] This invention provides a method for manufacturing a dense structure using unconventional welding techniques. It designs an unconventional T-joint form with full penetration welding, which enables double-sided welding, reduces welding volume, welding material consumption, and welding time, further reduces residual stress in the welded joint, controls angular deformation to the maximum extent, avoids the use of steel gaskets, and improves the fatigue performance of the joint.

[0006] For steel anchor boxes in steel structure bridges, the technical solution of the present invention is: a method for manufacturing a dense structure by unconventional assembly and welding, used to realize the welding of a full penetration T-shaped butt weld between a dense plate and a metal base plate, wherein the thickness of the dense plate is not less than 26mm, and a barrier plate is provided on one side of the dense plate, the ratio of the height of the barrier plate to the distance from any point on the barrier plate to the dense plate is tan52°~tan60°, and the distance from any point on the barrier plate to the dense plate is not greater than the distance for welding equipment or people to pass through;

[0007] The unconventional assembly and welding manufacturing method includes the following steps:

[0008] (1) Cut an inner bevel on the side of the edge where the dense board and the metal mother plate meet, facing the barrier board, and cut an outer bevel on the other side of the edge. The cutting angle of the inner bevel is set such that the tangent of the cutting angle is greater than the ratio and not greater than tan 60°. The depth of the inner bevel is 1 / 4 of the thickness of the dense board. A blunt edge with a thickness of 4 mm is left between the inner bevel and the outer bevel of the dense board. The cutting angle of the outer bevel is 45° and the depth of the outer bevel is the remaining value of the thickness of the dense board.

[0009] (2) Welding is carried out by first welding the inner shallow bevel and then welding the outer deep bevel after root cleaning.

[0010] Furthermore, when the inner bevel cutting angle is 60° and the thickness of the dense board is 40mm, the inner bevel depth is set to 10mm.

[0011] Furthermore, the outer bevel cutting angle is 45°, and the outer bevel depth is 26mm.

[0012] Furthermore, in step (2), CO2 gas shielded welding is used for welding, and the weld is welded in layers and intermittently. Each time the weld is welded, the filling amount is 1 / 3 to 1 / 2 of the weld.

[0013] Implementation effect

[0014] This welding method has yielded significant economic benefits.

[0015] 1. The reduced cross-sectional area of ​​the weld significantly reduces the amount of welding material used. After the design improvement, the cross-sectional area of ​​the weld is reduced by 47%, which means that the amount of welding material used in this part will also be reduced by 47%.

[0016] 2. Due to the reduction in welding volume, the corresponding demand for welding time is reduced, and the equipment occupancy time is also reduced, resulting in a reduction of approximately 30% in welding operation time.

[0017] 3. Minimal deformation after welding. With additional support and fixation before welding, the welds between the force transmission web, bearing plate, and outer web require almost no deformation correction after welding, significantly reducing the time required for deformation correction. Attached Figure Description

[0018] Figure 1 This is a structural diagram of a bridge steel anchor box.

[0019] Figure 2 A diagram showing the welding angle range on the inner side of the force-transmitting web;

[0020] Figure 3 Diagram showing the inner bevel and depth of the force-transmitting web;

[0021] Figure 4 Diagram showing the angle and depth of the bevel on the outer side of the force-transmitting web;

[0022] Figure 5 This is a graph showing the change in the cross-sectional area of ​​the weld. Detailed Implementation

[0023] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other. The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] A method for manufacturing dense structures using unconventional assembly and welding techniques, such as Figure 1 Taking a steel anchor box for a steel structure bridge as an example, the anchor box includes an anchor plate 1, an anchor bearing plate 2, a force transmission web 3, a stiffening plate 4, and an anchor pipe 5. The anchor box is welded to the outside of the side web 6. The force transmission web 3 is a dense structure welded to the outside of the side web 6. The thickness of the force transmission web 3 is 40 nm. The main implementation steps and scheme of its double-sided welding are briefly described as follows:

[0025] 1. Calculate the viewing angle range for welding the inner weld seam of the force transmission web 3.

[0026] like Figure 2 As shown, the height of the force transmission web 3 is 540mm and the spacing of the force transmission web 3 is 430mm. The viewing angle range for welding on the inner side of the force transmission web 3 is calculated according to the tangent formula. When the viewing angle is not less than 52°, that is, when the height of the force transmission web 3 increases while the spacing of the force transmission web 3 remains unchanged.

[0027] 2. Determine the angle and depth of the inner bevel of the force-transmitting web.

[0028] like Figure 3 As shown, according to the above-mentioned anchor box force transmission web 3 inner side viewing angle range of not less than 52°, due to the bevel control requirements of "Bevel Fabrication and Process", the bevel angle and chamfer are generally 30° to 60° to facilitate welding operation and improve weld strength. In this embodiment, the inner bevel angle between adjacent force transmission webs 3 is determined to be 60°. This angle can ensure the accessibility of the welding line of sight and is also the maximum angle for flame bevel opening. The bevel depth is taken as one-quarter of the plate thickness of the force transmission web 3, which is 10mm in this embodiment. If this depth is too large, it will block welding on one side. If the depth is too small, it will lead to an increase in the outer bevel depth, which will lead to a decrease in welding quality and easy to cause welding defects such as incomplete penetration and incomplete fusion.

[0029] 3. Angle and depth of the outer bevel of the force-transmitting web.

[0030] To ensure that the welding material fully penetrates the joint between the force-transferring web 3 and the side web 6, forming a dense and continuous metallic structure that runs through the entire weld thickness, the joint thickness of the force-transferring web 3 and the side web 6 should not be too thick. Simultaneously, to prevent the molten welding material from breaking through the molten pool and flowing out from the back of the bevel, causing perforation, the joint thickness of the force-transferring web 3 and the side web 6 should not be too thin. According to the requirements for full penetration welding with a single-sided bevel, a 2mm blunt edge should be left in the bevel (the blunt edge is the unbeveled end face along the thickness direction of the weldment when it is beveled). Therefore, if... Figure 4 As shown, the force transmission web 3 is designed with a 4mm blunt edge for double-sided beveling welding. Based on the requirements of the outer root cleaning and welding process, as well as the requirements of ensuring penetration depth and reducing welding material consumption and heat input, the outer beveling angle of the force transmission web 3 is set to 45° and the depth is 26mm.

[0031] 4. Welding shall be performed by first welding the inner shallow bevel and then cleaning the root before welding the outer deep bevel.

[0032] Due to the limited operating space inside the anchor box, it is difficult to observe the root condition of the inner side after root cleaning. Therefore, the method of welding is adopted to first weld the shallow bevel side on the inner side and then weld the deep bevel side on the outer side after root cleaning. CO2 gas shielded welding is used for welding. The weld is welded in layers and intermittently. Each weld fills 1 / 3 to 1 / 2 of the weld amount. The interpass temperature is strictly controlled. The same type of weld is welded multiple times and alternately.

[0033] The outer root cleaning uses a small-diameter air-gouged carbon rod (Ф6 or Ф8mm). The metal luster is visible from the deep bevel side root cleaning. Low heat input is used, which is beneficial to refine the grains and improve toughness. The weld microstructure is mainly ferrite, bainite and martensite. The weld microstructure and properties can be controlled by using reasonable welding materials and processes. When the welding heat input is less than 18kJ / cm (Q=IU / v), the weld zone can obtain excellent mechanical properties.

[0034] like Figure 5 As shown on the left, in existing technologies, welding involves an outer-side single-sided bevel weld with a steel backing welded to the inner side for plate support. The weld cross-sectional area is 1436 square millimeters, requiring a large amount of welding material, long welding time, and angular deformation that shrinks to one side, leading to excessive joint stress and overall deformation. Furthermore, the use of a steel backing results in poor fatigue performance of the welded joint. This invention provides a dense structure unconventional assembly and welding manufacturing method, designing an unconventional penetration weld T-joint form that enables double-sided welding. Figure 5 As shown on the right, the weld cross-sectional area becomes 764 square millimeters, a reduction of 47%. This means that the amount of welding material used in this area will also be reduced by 47%. Reducing the amount of welding, the amount of welding material consumed, and the welding time further reduces the residual stress of the welded joint, controls angular deformation to the maximum extent, avoids the use of steel backing, and improves the fatigue performance of the joint.

Claims

1. A method for manufacturing a dense structure using unconventional assembly and welding, characterized in that, This is used to achieve full penetration T-shaped butt welds between dense plates and metal base plates. The thickness of the dense plates is not less than 26mm, and a barrier plate is provided on one side of the dense plates. The ratio of the height of the barrier plate to the distance from any point on the barrier plate to the dense plates is tan52°~tan60°. The distance from any point on the barrier plate to the dense plates is not greater than the distance for welding equipment or people to pass through. The unconventional assembly and welding manufacturing method includes the following steps: (1) Cut an inner bevel on the side of the edge where the dense board and the metal mother plate meet, facing the barrier board, and cut an outer bevel on the other side of the edge. The cutting angle of the inner bevel is set such that the tangent of the cutting angle is greater than the ratio and not greater than tan 60°. The depth of the inner bevel is 1 / 4 of the thickness of the dense board. A blunt edge with a thickness of 4 mm is left between the inner bevel and the outer bevel of the dense board. The cutting angle of the outer bevel is 45° and the depth of the outer bevel is the remaining value of the thickness of the dense board. (2) Welding is carried out by first welding the inner shallow bevel and then welding the outer deep bevel after root cleaning.

2. The method for manufacturing a dense structure using unconventional assembly and welding according to claim 1, characterized in that, When the inner bevel cutting angle is 60° and the thickness of the dense board is 40mm, the inner bevel depth is set to 10mm.

3. The method for manufacturing a dense structure using unconventional welding according to claim 2, characterized in that, The outer bevel cutting angle is 45°, and the outer bevel depth is 26mm.

4. A method for manufacturing a dense structure using unconventional welding according to any one of claims 1 to 3, characterized in that, Step (2) Welding is performed using CO2 gas shielded welding. The weld is welded in layers and intermittently. Each time the weld is welded, the filler amount is 1 / 3 to 1 / 2 of the weld.

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