A welded joint of stacked steel plates and a manufacturing method thereof, and a metal sandwich panel

Abstract

The present invention relates to the technical field of welding of steel structures, and discloses a welding joint and a manufacturing method of stacked steel plates, as well as a metal sandwich plate, which solve the problems of low welding strength of stacked steel plates and great difficulty in welding in a narrow space. The key points of its technical solution are that it includes a first steel plate member and a second steel plate member, the first steel plate member and the second steel plate member overlap or partially overlap in the thickness direction; the first steel plate member has a closed welding cavity in the overlapping area, and the closed welding cavity divides the first steel plate member into an inner plate located within the closed welding cavity and a remaining outer plate; welding is performed along the closed welding cavity to form a closed weld, and the inner plate, outer plate and second steel plate member are welded together. The present invention is applicable to a wider range of thickness of steel plates of workpieces and a larger area, and the fatigue resistance of the welded joint is stronger. At the same time, internal welds and external welding in narrow spaces or inner cavities can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of welding of steel structures, and in particular to a welded joint of stacked steel plates and a manufacturing method thereof, as well as a metal sandwich plate. Background Art

[0002] Steel structure is a structure made mainly of steel, with components mainly made of steel sections and steel plates. Because of its light weight and simple construction, it is widely used in large buildings, bridges, venues, ships and other fields.

[0003] Steel structure connections are primarily made by welding, bolting, and riveting, with welding accounting for the largest proportion. Because structural steel components must maintain the required stiffness and strength to withstand various loads, certain requirements are placed on the thickness of the steel plates. Face-to-face welding of thicker steel plates—that is, connecting two or more layers of steel components stacked across the thickness—is a challenging aspect of steel structure welding.

[0004] Welding in inner cavities, narrow spaces, and some welding spaces that are difficult to access is particularly difficult. For example, a metal sandwich panel consists of two layers of metal panels and a lightweight core with high rigidity. This structure has a light weight, low structural height, and good integrity. Compared with a single-layer panel, it has an increased virtual thickness and has good bending, torsion, impact resistance, and energy absorption characteristics. It has a large load-bearing capacity and is widely used in steel bridge panels, ship floors and cabins, offshore platforms, buildings, and other fields. Since the connection between the core and the panel is on the inside, welding is difficult. Even if welding is performed by a welding robot, since the weld is in the inner cavity, it is difficult to perform subsequent inspection and maintenance.

[0005] One of the existing technologies is to use traditional plug welding, in which a hole is opened in one of the steel plates and the entire area inside the hole is welded. However, the disadvantage of this type of welding is that the area is small. If a solid larger area welding is used for the surface welding of the welding interface, the entire area needs to be welded. Not only is the heat input large, forming a larger range of heat-affected sensitive zone, but the filled weld is often uneven. Secondly, the weld trajectory of small-area plug welding is single, while the radial trajectory of the weld in the large-area hole is different. The complex weld trajectory makes defects inevitable. It is difficult for the weld to directly withstand the complex load-bearing requirements of all-directional loads and it is difficult to form a load-bearing function in multiple directions. That is, when a load that is not conducive to the direction of the weld occurs, the weld is very likely to crack or fatigue. Therefore, it is stated in the relevant welding standards that general plug welding cannot be used for structural welding.

[0006] The second existing technology uses a laser beam to melt the metal in the weld area, forming a surface-to-surface bond. Because the laser beam is focused, aligned, and guided by optical instruments, it must be placed at an appropriate distance from the workpiece. This limits welding space and is typically limited to small, thin metal sheets under 1.5 mm thick, and precision workpieces in workshops. Furthermore, the laser beam is typically focused on a very small area. While melting thick metal sheets is theoretically possible, it's not practical in actual production operations. Furthermore, the equipment is expensive, making it unsuitable for welding large steel structures such as buildings and bridges. Summary of the Invention

[0007] The main purpose of the present invention is to solve the problems of low welding strength of welded joints of stacked steel plates, especially large structural parts, and difficulty in welding in narrow spaces. It provides a welding joint with high welding structure strength, which can be suitable for welding thick steel plates and narrow spaces, and a welding method thereof, as well as a metal sandwich panel using the welding joint.

[0008] In order to achieve the above-mentioned object of the invention, a first aspect of the present invention provides a welded joint of stacked steel plates, comprising a first steel plate member and a second steel plate member, wherein the first steel plate member overlaps or partially overlaps the second steel plate member in a thickness direction;

[0009] The first steel plate has a closed welding cavity in the overlapping area, and the closed welding cavity divides the first steel plate into an inner plate located within the closed welding cavity and a remaining outer plate;

[0010] The closed welding cavity includes at least one slot-shaped sub-welding cavity penetrating the upper and lower surfaces of the first steel plate and at least one connecting rib connecting the inner plate and the outer plate;

[0011] Welding is performed along the closed welding cavity to form a closed weld seam, and the inner plate, the outer plate and the second steel plate are welded together.

[0012] The connecting ribs are not only used as a temporary measure before welding, but also can ensure that the inner plate and the outer plate do not separate when the closed welding cavity of the first steel plate is cut, which is convenient for subsequent transportation and circulation. At the same time, they provide positioning for the inner plate, outer plate and second steel plate during welding, preventing the uneven groove width of the welding cavity caused by the offset of the inner and outer plates, which may cause a decline in welding quality.

[0013] Since the ends of the open welds are stress concentration points, in order to ensure that the connecting ribs can be melted during welding to form a closed weld and avoid the weld becoming an open weld with two ends and becoming a fatigue sensitive point, it is preferred that the length t of the connecting ribs is less than the groove width b of the closed weld cavity.

[0014] Preferably, an inner welding cavity is provided on the inner plate. When the inner plate is large in area, further grooves are formed on the inner plate for welding, and the inner plate is further divided into multiple small areas to further increase the welding strength.

[0015] Preferably, the inner welding cavity is communicated with the closed welding cavity.

[0016] Preferably, the inner welding cavity and the closed welding cavity form a continuous one-stroke curve. Since arc starting and arc ending are areas with a high probability of defects, connecting the inner welding cavity with the outer welding cavity and further forming a one-stroke curve can effectively reduce the number of arc starting and arc endings, thereby reducing the occurrence of fatigue.

[0017] Preferably, the inner welding cavity is a spiral line with one end connected to the closed welding cavity. The circular line of the closed welding cavity merges the arc start into the closed weld seam. The spiral inner welding cavity hides the arc end in the center of the entire weld area, which is the least sensitive stress area, thus avoiding arc end defects.

[0018] As an advantage, the inner welding cavity is a straight line or a curve with both ends connected to the closed welding cavity. The weld trajectory can be flexibly designed according to the actual welding or workpiece structure.

[0019] Preferably, the thickness of the first steel plate in the overlapping area is greater than or equal to 1.5 mm. Laser welding is commonly used for thin plates and can melt the metal of the panel without cutting grooves in the panel. The embodiment of the present invention is more suitable for welding thicker steel plates of 1.5 mm and above.

[0020] Preferably, the closed welding cavity is circular, elliptical, or rectangular, which makes the welding track more designable.

[0021] In conjunction with the first aspect of the present invention, the present invention provides a method for manufacturing a welded joint of stacked steel plates, comprising the following processes:

[0022] a. Cutting the first steel plate to form a closed welding cavity, which divides the first steel plate into an inner plate located radially within the closed welding cavity and a remaining outer plate;

[0023] b. The first steel plate and the second steel plate are bonded to each other, overlapping or partially overlapping, with the inner plate and the closed welding cavity located in the overlapping area;

[0024] c. Continuously weld along the trajectory of the closed welding cavity to form a closed weld, welding the inner plate, outer plate and the second steel plate together.

[0025] Another aspect of the present invention provides a metal sandwich panel, comprising two parallel panels and a core panel arranged between the two panels, wherein the core panel is partially bonded to the inner surface of the panel, and the area where the core panel is partially bonded to the inner surface of the panel is welded and fixed using the above-mentioned welding joint, wherein the first steel plate member is the panel and the second steel plate member is the core panel.

[0026] Preferably, the core plate is a corrugated plate.

[0027] Compared with the prior art, the present invention adopts the above technical solution and has significant technical effects:

[0028] 1. The overlapping steel plate weld joint and welding method provided by the embodiment of the present invention are applicable to a wider range of workpiece steel plate thicknesses, and are particularly suitable for connecting thick steel plate workpieces such as large bridges and buildings. By opening a closed welding cavity in the first steel plate, that is, forming the welding cavity by slotting, and then welding it to the second steel plate, unlike the laser welding method that requires melting the first steel plate, the present invention is not limited by the thickness of the welded workpiece. At the same time, the weld joint of the embodiment of the patent can be welded by traditional welding equipment with lower welding cost and better economic performance, and is more suitable for welding load-bearing steel structural parts.

[0029] 2. In terms of stress, the welded joint of stacked steel plates and the welding method provided by the embodiments of the present invention are more suitable for large-area, high-strength surface welding, and the welded joint has stronger fatigue resistance.

[0030] First of all, unlike the traditional method of filling the welding hole with welding materials, the weld of the present invention retains an intermediate inner plate formed by the base material. The shear, tensile and fatigue resistance of the base material are much better than the weld in terms of stability. The base material is used as a smooth transition between welds, avoiding the sudden change of cross-section between welds. When the connection area bears load, the weld directly transmits shear and bending forces, which can effectively improve the fatigue resistance of the weld.

[0031] Secondly, the welded joint of the present invention solves the unidirectional stress problem of plug or straight welds, meeting the functional requirements of complex, multi-directional working conditions. Because plug or straight welds offer excellent stress resistance in one direction but poor performance in another, the weld trajectory can be flexibly designed within the weld plane based on factors such as the structure of the welded component, the required weld area, and the varying local loads in different areas, ensuring weld extension in both the longitudinal and transverse directions, thus accommodating stress in all directions.

[0032] 3. The present invention forms a closed weld by continuous welding in a closed welding cavity, thereby reducing the number of welding arc starting points and arc ending points, avoiding the probability of welding defects caused by too many arc starting points and arc ending points, forming a structure similar to circumferential welding, and having better weld strength.

[0033] 4. The welded joint of the present invention overcomes some space or height restrictions during on-site steel structure construction, enabling internal and external welding in narrow spaces or inner cavities. This not only reduces welding difficulty, improves economic performance, but also makes weld quality easier to detect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic structural diagram of a welded joint of stacked steel plates before welding according to Example 1 of the present invention;

[0035] Figure 2Schematic diagram of the structure of the welded joint of the stacked steel plates after welding according to Example 1 of the present invention;

[0036] Figure 3 for Figure 2 Cross-section along the AA direction;

[0037] Figure 4 This is a schematic structural diagram of a closed welding cavity with connecting ribs according to Example 1 of the present invention;

[0038] Figure 5 for Figure 4 Schematic diagram of the structure after welding, where the connecting ribs are melted during welding;

[0039] Figure 6 This is a structural schematic diagram of an inner plate with an inner welding cavity in Example 1 of the present invention;

[0040] Figure 7 This is a schematic structural diagram of another form of the inner welding cavity in Example 1 of the present invention;

[0041] Figure 8 A schematic diagram of the structure of a closed welding cavity in a rectangular shape in Example 1 of the present invention;

[0042] Figure 9 This is a schematic structural diagram of a metal sandwich panel according to Example 2 of the present invention.

[0043] Reference numerals: 1—first steel plate, 11—inner plate, 12—outer plate, 2—second steel plate, 3—closed welding cavity, 31—connecting rib, 32—sub-welding cavity, 4—inner welding cavity, 5—closed weld. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings. It should be noted that, in the description of the present invention, the terms "transverse," "longitudinal," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention.

[0045] Example 1:

[0046] like Figures 1 to 3 As shown in the figure, it is a welded joint of stacked steel plates. Figure 1 As shown, the first steel plate member 1 and the second steel plate member 2 are made of steel plates, and the first steel plate member 1 and the second steel plate member 2 are partially overlapped or placed in an overlapping manner in the plate thickness direction.

[0047] like Figure 1 As shown, the first steel plate 1 is provided with an annular groove running through the upper and lower surfaces of the steel plate to form a closed welding cavity 3. Of course, the first steel plate 1 and the second steel plate 2 are relative to each other, and the groove can also be provided on the second steel plate 2, or on both sides to enhance the welding strength. However, for some parts with limited space, such as one side is an inner cavity or a space that is difficult to enter, the groove should be provided on a part that is convenient for welding. The closed welding cavity 3 can be in the shape of a closed curve such as a circle, an ellipse, or a rectangle. Figure 8 The closed weld cavity 3 shown is rectangular. The closed weld cavity 3 divides the first steel sheet 1 into an inner plate 11 located within the closed weld cavity 3 and a remaining outer plate 12. The inner plate 11 is the remaining material formed when the closed weld cavity 3 is cut from the first steel sheet 1, or it can be formed by separate processing.

[0048] The closed welding cavity 3 can also be formed by a plurality of discontinuous sub-welding cavities 32 to form a closed welding path, such as Figure 4 The closed welding cavity 3 includes a plurality of sub-welding cavities 32 that pass through the upper and lower surfaces of the first steel plate 1 and a plurality of connecting ribs 31. The sub-welding cavity 32 is in the shape of a narrow groove. The connecting ribs 31 connect the inner plate 11 and the outer plate 12. As a measure to temporarily fix the inner plate 11 and the outer plate 12 before welding, it can ensure that the inner plate 11 and the outer plate 12 do not separate when the closed welding cavity 3 of the first steel plate 1 is cut, and it is convenient for the transportation and flow of subsequent workpieces. It is preferably used with two or more connecting ribs 31, which can be more stable.

[0049] During welding, welding is performed continuously along the trajectory of the closed welding cavity 3. Figure 2 、 3 for Figure 1 After continuous welding in the closed welding chamber 3, a closed weld bead 5 is formed. Figure 5 for Figure 4 Schematic diagram after welding, continuous welding is performed while melting the connecting ribs 31 between adjacent sub-welding cavities 32, and a continuous closed weld 5 is formed in the closed welding cavity 3. Figure 3 As shown, the connecting rib 31 is located between the two ends of adjacent sub-weld cavities 32. If the connecting rib is too wide, it will be difficult to melt the connecting rib 31 during continuous welding, making it difficult to form a continuous closed weld. Instead, an open weld with two ends will be formed, where stress concentration areas and fatigue-sensitive points will occur. Therefore, the length t of the connecting rib 31 should ensure that the connecting rib 31 can be melted during welding. After experimental verification, the length t of the connecting rib 31 is less than the groove width b of the closed weld cavity 3. During welding, continuous welding is performed along the trajectory of the closed weld cavity 3, and the connecting rib is melted, forming a closed weld 5 within the closed weld cavity 3. The closed weld 5 welds the inner plate 11, the outer plate 12, and the second steel plate 2 together.

[0050] At the same time, during the welding process, the connecting ribs 31 provide positioning for the inner plate 11, the outer plate 12, and the second steel plate when welding, ensuring the relative position of the inner plate 11 and the outer plate 12, and preventing the inner plate 11 from shifting and causing uneven groove width of the welding cavity, resulting in inconsistent weld cross-sections and reduced welding quality.

[0051] The manufacturing of the welded joint of this embodiment includes the following process steps:

[0052] First, the first steel plate 1 is cut into a closed welding cavity 3, and the closed welding cavity 3 divides the first steel plate 1 into an inner plate 11 located radially inside the closed welding cavity 3 and a remaining outer plate 12;

[0053] The first steel plate 1 and the second steel plate 2 are bonded to each other, and the two are placed overlapping or partially overlapping, and the inner plate 11 and the closed welding cavity 3 are located in the overlapping area;

[0054] Continuous welding is performed along the trajectory of the closed welding cavity 3 to form a closed weld 5 , thereby fixedly connecting the inner plate 11 , the outer plate 12 and the second steel plate 2 .

[0055] Compared with laser welding, the above-mentioned welded joints of stacked steel plates are more suitable for welding load-bearing structural parts, especially for large steel structural parts of buildings, bridges, ships, etc., such as bridge decks, floor decks, ship holds, etc. Laser welding directly melts steel plates in a non-contact manner. The width of the weld bead, the thickness of the welded workpiece, and the working space are limited by the laser source and equipment. It is often used for thin plates. The welded joints of Example 1 of this patent can be welded by traditional welding equipment with lower welding costs and better economic performance. The grooving makes the applicable steel plate thickness range wider, and it is especially suitable for the connection of thicker steel plates with a thickness greater than or equal to 1.5 mm.

[0056] At the same time, compared with traditional methods such as plug welding, the present application is more suitable for large-area surface welding. By retaining the intermediate inner plate 11 inside the closed weld 5 as a smooth transition between welds, it avoids the formation of cross-section mutations between welds, resulting in a situation where the weld directly transmits force through shear and bending when bearing load. Since the transmission of shear and bending forces is generally weaker than tension or compression, and the sudden deformation of the cross-section at this location can cause a more obvious fatigue factor, retaining the intermediate inner plate formed by the base material in the weld can effectively improve the fatigue resistance of the weld and meet the functional requirements of complex working conditions in all directions.

[0057] In the plane of the welding area, the weld trajectory can also be flexibly designed according to factors such as the structure of the welded component, the required welding area size, and the different local loads in different areas. This allows for greater design flexibility and ensures weld extension in both the longitudinal and transverse directions. This effectively solves the problem of plug welding or straight welding having good stress performance in one direction but poor in the other, and allows for balanced stress in all directions.

[0058] like Figure 2 A closed weld 5 is formed by continuous welding in the closed welding cavity 3, forming a structure similar to a circumferential weld. The arc starting point and arc ending point are frequent points of welding defects. The closed weld 5 makes the arc starting point and arc ending point coincide with each other, and the weld strength is greater.

[0059] In the case of a large area of ​​the inner plate 11, the inner plate 11 is further grooved for welding, and the inner plate 11 is further divided into multiple small areas to further increase the welding strength. Figure 6 As shown, various internal welding cavities can be formed on the inner plate 4 to increase the welding area and thus enhance weld strength. The internal welding cavity 4 communicates with the closed welding cavity 3. Preferably, the path curve of the internal welding cavity 4 forms a continuous one-stroke curve with the closed welding cavity 3. Since arc start and arc end are areas with a high probability of defects, connecting the internal welding cavity 4 with the outer welding cavity 3 and further forming a one-stroke pattern can effectively reduce the number of arc starts and arc end, thereby reducing fatigue. Figure 6 The inner welding cavity shown is a spiral. The circular closed welding cavity 3 is drawn in one stroke to merge the arc start into the circular closed weld. The spiral inner welding cavity 4 hides the arc end in the center of the entire welding area, which is the least sensitive stress area, avoiding the defect of arc end.

[0060] Of course, the inner welding cavity 4 may not form a one-stroke curve with the closed welding cavity, such as Figure 7 Shown are straight lines or curves, both ends of which are connected to the closed welding cavity 3.

[0061] Example 2:

[0062] Embodiment 2 of the present invention provides a metal sandwich plate, which is a specific case of the welding joint of embodiment 1 being used for welding metal sandwich plates, and realizes internal weld and external welding of narrow spaces or inner cavities of metal sandwich plates. Figure 9 As shown, a metal sandwich panel includes two parallel panels and a core panel arranged between the two panels. The core panel is a corrugated plate with straight peaks and troughs. The peaks and troughs are bonded to the inner surfaces of the panels. Since the bonding surface between the core panel and the panel is located inside the panel of the metal sandwich panel, the welding between the core panel and the panel is an inner cavity welding in a narrow space due to the height limitation of the sandwich panel.

[0063] like Figure 9 When assembling the sandwich panel, the weld seam on one side of the upper and lower panels can be directly welded, while the other side cannot be welded because it needs to be covered with a panel. The side that cannot be welded uses the weld joint of Example 1, where the panel serves as the first steel plate 1 and the core plate serves as the second steel plate 2. Multiple closed welding cavities are opened on the panel for welding, forming multiple closed welds 5. The internal weld seam in the narrow space is transferred to the outside, achieving the effect of internal seam external welding, reducing the welding difficulty, and making the weld quality easier to detect and repair later.

[0064] At the same time, when assembling, in the actual working environment of the metal sandwich panel, the welds in the tension area are open welded, and the welds in the compression area are welded using this patented welding method. This can better meet structural needs when used.

[0065] The above are preferred embodiments of the present invention. Those skilled in the art may make several modifications and improvements without departing from the principles of the present invention, and these modifications and improvements should also be considered within the scope of protection of the present invention.

Claims

1. A welded joint of stacked steel plates, comprising a first steel plate member (1) and a second steel plate member (2), wherein the first steel plate member (1) and the second steel plate member (2) overlap or partially overlap in a thickness direction, characterized in that: The first steel plate (1) is provided with a closed welding cavity (3) in the overlapping area, and the closed welding cavity (3) divides the first steel plate (1) into an inner plate (11) located within the closed welding cavity (3) and a remaining outer plate (12); The closed welding cavity (3) includes at least one narrow groove-shaped sub-welding cavity (32) penetrating the upper and lower surfaces of the first steel plate (1) and at least one connecting rib (31) connecting the inner plate (11) and the outer plate (12); welding is performed along the closed welding cavity (3) to form a closed weld (5), and the inner plate (11), the outer plate (12) and the second steel plate (2) are welded together.

2. The welded joint of stacked steel plates according to claim 1, wherein: The length t of the connecting rib (31) is smaller than the groove width b of the closed welding cavity (3).

3. The welded joint of stacked steel plates according to claim 1, wherein: An inner welding cavity (4) is provided on the inner plate (11).

4. The welded joint of stacked steel plates according to claim 3, wherein: The inner welding cavity (4) is communicated with the closed welding cavity (3).

5. The welded joint of stacked steel plates according to claim 3, wherein: The inner welding cavity (4) and the closed welding cavity (3) form a continuous one-stroke curve.

6. The welded joint of stacked steel plates according to claim 3, wherein: The inner welding cavity (4) is a spiral line with one end connected to the closed welding cavity (3).

7. The welded joint of stacked steel plates according to claim 3, wherein: The inner welding cavity (4) is a straight line or a curve, both ends of which are connected to the closed welding cavity (3).

8. The welded joint of stacked steel plates according to claim 1, wherein: The thickness of the first steel plate (1) in the overlapping area is greater than or equal to 1.5 mm.

9. The welded joint of stacked steel plates according to claim 1, wherein: The closed welding cavity (3) is circular, elliptical, or rectangular.

10. A method for manufacturing a welded joint of stacked steel plates according to claim 1, characterized in that: Including the following processes: a. Cutting the first steel plate (1) to form a closed welding cavity (3), and the closed welding cavity (3) divides the first steel plate (1) into an inner plate (11) located radially inside the closed welding cavity (3) and a remaining outer plate (12); b. The first steel plate (1) and the second steel plate (2) are bonded to each other, overlapped or partially overlapped, and the inner plate (11) and the closed welding cavity (3) are located in the overlapping area; c. Continuously welding along the trajectory of the closed welding cavity (3) to form a closed weld (5), and welding the inner plate (11), the outer plate (12) and the second steel plate (2) together.

11. A metal sandwich panel comprising two parallel face sheets and a core sheet disposed between the two face sheets, wherein the core sheet is partially bonded to the inner surfaces of the face sheets, wherein: The core plate and the inner surface of the panel are partially bonded in a welding manner using the welding joint described in any one of claims 1 to 9. The first steel plate (1) is the panel, and the second steel plate (2) is the core plate.

12. The metal sandwich panel according to claim 11, characterized in that: The core plate is a corrugated plate.

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