Methods for welding metal plates
Friction stir welding combined with electron beam welding addresses the challenge of welding large metal plates by creating a root pass weld first, ensuring high-quality welds for large structures like pressure vessels and wind turbines.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- AQUASIUM TECH
- Filing Date
- 2024-05-30
- Publication Date
- 2026-07-08
AI Technical Summary
Welding large metal plates for structures like pressure vessels and wind turbines is challenging due to their size and weight, leading to difficulties in maintaining welding quality and efficiency, especially when multiple plates are joined to form larger cylinders.
A method involving friction stir welding to create a root pass weld along the butt weld line followed by electron beam welding, ensuring high-quality welds without defects, using a combination of a friction stir welding machine and electron beam gun positioned appropriately to weld heavy metal plates efficiently.
Enables high-quality welding of multiple large metal plates into cylindrical shapes without defects, allowing for faster processing and improved weld quality, especially for diameters exceeding 11 m, by generating a root pass weld before electron beam welding.
Smart Images
Figure 2026522645000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method of welding metal plates, particularly large metal plates used, for example, to form pressure vessels, reactors, and wind turbines.
Background Art
[0002] Welded structures for pressure vessels, reactors, and wind turbines are difficult due to the size and weight of the metal plates that need to be welded together. Offshore wind energy structures typically consist of multiple hollow metal cylinders or cladding tubes formed from metal plates with a maximum thickness of 130 mm. Typically, two metal plates are rolled, each plate forming half of the cylinder, and then the two rolled plates are welded together to form the complete cylinder. The size and weight of the plates make the process very difficult and require a great deal of time.
[0003] Considering the increasing requirements for larger diameter cylinders for offshore monopiles, pressure vessels, and reactors, and the maximum size of available metal plates, when welded, more than two metal plates need to be joined together to obtain a cylinder with a circumference of about 40 m. However, when the joined plates are rolled and ready to be welded into a cylinder, it is difficult to maintain welding quality using existing techniques.
Summary of the Invention
Means for Solving the Problems
[0004] According to one aspect of the present invention, a method of welding metal plates, comprising: i) starting friction stir welding using a friction stir welding machine along the lower edge of a butt weld line between adjacent metal plates having a weight exceeding 50 tons, preferably exceeding 80 tons, to generate a root pass weld along the butt weld line, and positioning the friction stir welding machine under the plates for welding in an upward position; ii) A method is provided comprising the steps of: initiating electron beam welding using an electron beam gun along the upper edge of a joint weld line to generate a weld seam between adjacent plates after friction stir welding, wherein the electron beam gun is positioned on the plates. By generating a root pass weld before electron beam welding, the vertical edges of adjacent metal plates can be welded using electron beam welding without compromising the quality of the electron beam weld. The resulting weld allows the joint plates to be rolled into a hollow cylindrical shape ready for final welding without defects in the weld seam.
[0005] Preferably, each metal plate has dimensions of approximately 10 m in length, approximately 4 m in width, and a wall thickness between 90 mm and 130 mm, and preferably, at least three adjacent metal plates are welded together to form a tube with a diameter of more than 11 m.
[0006] The method may further include the steps of replacing the welding head of a friction stir welding machine with a milling head, and milling along the joint weld line before friction stir welding is performed. This eliminates the need to move heavy metal sheets between rolling and friction stir welding, and as a result simply forms a portion of the weld depth, and the metal sheets typically have a thickness of 90 mm to 130 mm.
[0007] Preferably, the root pass weld is 12 mm to 20 mm deep.
[0008] Preferably, electron beam welding is performed in a vacuum.
[0009] Friction stir welding may be performed in a vacuum to prevent oxidation of the friction stir welding tools.
[0010] Electron beam welding and friction stir welding may be performed within a common exhaust housing.
[0011] Preferably, the metal sheet is supported on a conveyor (e.g., a roller conveyor) so that it is movable relative to the friction stir welding machine and the electron beam gun. Preferably, the friction stir welding machine and the electron beam gun are spaced apart relative to the direction of travel of the metal sheet, so that the friction stir welding machine is upstream of the electron beam gun, and therefore any portion of the metal sheet passes through the friction stir welding machine before reaching the electron beam gun. This allows two seams to be processed in cooperation, forming a root pass weld relative to one joint weld while performing electron beam welding of a joint weld line having a root pass weld.
[0012] The metal sheet may be formed from steel such as C-Mn structural steel, alloy steel, or any other metallic material requiring welding (e.g., nickel, titanium, aluminum, and their alloys).
[0013] According to another aspect of the present invention, a metal tube formed by the method described above is provided, preferably having a diameter of 11 m or more.
[0014] Now, the present invention will be described as an example with reference to the attached drawings. [Brief explanation of the drawing]
[0015] [Figure 1] This is a perspective view of an electron beam assembly that welds a hollow cylinder formed from two metal plates. [Figure 2] This is a perspective view of a first embodiment of a welding configuration for initiating the method according to the present invention. [Figure 3] This is a schematic diagram illustrating the formation of a root path weld. [Figure 4] This is a photograph of a root path weld. [Figure 5] This is a schematic diagram of a modified friction stir welding machine used to begin milling metal sheets. [Figure 6] This is a schematic diagram showing a milled plate adjacent to a friction stir welding plate. [Figure 7] This is a perspective cross-sectional view of a second embodiment of the welded configuration. [Figure 8] This is a schematic diagram illustrating the milling process of a rolled cylinder. [Figure 9] This is a schematic diagram of friction stir welding of a rolled cylinder. [Figure 10] This is a schematic cross-sectional view of a rolled cylinder using a friction stir welding machine and electron beam gun located inside a vacuum housing. [Modes for carrying out the invention]
[0016] Figure 1 shows a prior art configuration for electron beam welding two rolled metal sheets 10, 12 together to form a hollow cylindrical tube, also known as a cladding tube, which is used, for example, to form a transition piece in a wind turbine monopile or to generate the wall of a pressure vessel or reactor. Typically, each sheet is about 10 m long, about 4 m wide, and between 90 mm and 130 mm thick. An electron beam gun in a housing 14 is used to weld the sheets 10, 12 together at an adjacent longitudinal seam 16, the seam 16 being held horizontally to prevent the welding material from dripping from the seam during formation. In Figure 1, one seam position is shown, with the second seam position hidden by the housing 14. A skilled human worker 18 is shown to give a sense of scale. While this type of configuration can be used to weld tubes with a diameter of several meters, for diameters exceeding 11 m, more than two metal sheets are required, and processing the metal sheets and achieving a high-quality weld becomes extremely difficult.
[0017] Generally, when welding adjacent metal plates, welds along vertical edges cause liquid metal to form during the welding process, which then falls due to gravity, resulting in a porous, low-quality weld. In prior art configurations, this can be prevented by fixing a backing plate between the lowest edges of the adjacent plates, and removing the backing plate after welding. Another option is to use arc welding, which creates a plug extending along the lower edge, sealing the bottom of the joint weld line far from the incident electron beam. However, these configurations compromise the quality of the final weld and / or cause delays in weld testing.
[0018] Figure 2 shows an apparatus 20 for welding together a plurality of metal plates 22 for subsequent rolling into a cylinder exceeding 11 m before final welding. Typically, each plate 22 has a length of about 10 m, a width of about 4 m, a thickness between 90 mm and 130 mm, and a weight exceeding 50 tons (generally in the range of 50 tons to 100 tons). Typically, three or more plates are to be welded together and, after welding, rolled into a cylinder with a diameter exceeding 11 m. The metal plates are formed from steel such as, for example, C-Mn structural steel, alloy steel, or any other metal material requiring welding (e.g., nickel, titanium, aluminum, and their alloys).
[0019] The apparatus 20 includes an electron beam welding assembly 24 and a friction stir welder 26. The electron beam assembly 24 includes an electron beam gun 28 that is disposed above the plates 22 and is movable across the metal plates so as to be able to weld longitudinal seams along the joint weld lines between adjacent plates. The electron beam gun 28 generally moves perpendicular to the direction of travel 30 of the metal plates 22 along a roller conveyor 32 that moves in a horizontal plane parallel to the upper surface 34 of the plates 22. The electron beam gun 28 is within an evacuable seal housing 36 for generating a vacuum, and the plates 22 move along the roller conveyor 32 into this evacuable region 36 for welding. Further, the friction stir welder 26 is movable across the metal plates 22 using a linear drive configuration and is disposed beneath the plates 22 close to the lower plate surface 38 for performing upward welding.
[0020] Before electron beam welding is performed, the friction stir welder 26 is used to create a continuous root pass weld 42 extending along the entire length of the joint weld line 40 between adjacent plates to join the plates 22, 22', and to seal the bottom of the joint weld line 40 before electron beam welding is performed (see FIGS. 3 and 4). Typically, the root pass weld 42 is performed from below the plates as an upward weld using argon, which is typically used as a shielding gas to reduce oxidation during welding. The root pass weld 42 typically has a depth of from 12 mm to 20 mm.
[0021] After generating the root pass weld 42 along the width of the adjacent plates 22, 22', electron beam welding is performed along the upper edge of the joint weld line 40 to generate a full penetration weld seam extending from the upper surface 34 to the lower surface 38 along the width of the plates 22, 22'. The seam is cold to the touch immediately after welding, and as a result, unlike the case where arc welding is used and requires several hours of cooling time before testing can be performed, it can be tested immediately. By generating the root pass weld prior to electron beam welding, the vertical edges of adjacent metal plates can be welded using electron beam welding without degrading the quality of the electron beam weld. The resulting seam is a combination of friction stir welds and electron beam welds and is sufficiently elastic to ensure that the joined plates can be rolled into a hollow cylindrical shape ready for final welding without defects in the weld seam. Thus, at least three adjacent metal plates can be welded together to form a tube having a diameter exceeding 11 m.
[0022] In FIG. 2, the friction stir welder 26 is positioned upstream of the electron beam assembly 24 such that any given joint weld line meets the friction stir welder 26 before the electron beam gun 28. Thereby, one joint weld line 40 can be friction stir welded to generate the root pass weld, and at the same time, the joint weld line that has already been processed to have the root pass weld can be welded by the electron beam assembly 24, resulting in a faster overall processing of the plate 22.
[0023] If necessary, the welding head of the friction stir welding machine 26 can be replaced with a milling cutter 50 (see Figure 5), and the edges of the joint weld line 40 are milled from below along the width of the plates 22, 22' in the direction of arrow 51 using a linear drive unit, ensuring that any burrs or rough edges are removed in the root pass weld area and that the metal plates 22, 22' can be butted together in close proximity. After milling, the milling cutter 50 is replaced with a friction stir welding head 52, and the plates 22, 22' are butted together in close proximity to create the root pass weld 42 before electron beam welding is performed (see Figure 6). By using the same machine to mill and then friction stir weld, there is no need to move the metal plates between milling and friction stir welding.
[0024] The process of generating a root pass weld along the joint weld line before electron beam welding ensures that metal plates with vertically adjacent surfaces can be welded together without loss of welding material. Replacing the friction stir welding head 52 with the milling cutter 50 to remove burrs and rough edges ensures that adjacent plates can be butted together in close proximity, improving the quality of the root pass weld and ensuring that no gaps occur around the root pass weld if the plates have uneven edges. The generation of the root pass weld 42 ensures that very heavy metal plates can be processed by electron beam welding in a cost-effective and time-efficient manner before rolling. Furthermore, since friction stir welding generates very little heat, the quality of the root pass weld can be inspected and defects corrected before the metal plates are moved along the roller conveyor 32 to the electron beam welding machine.
[0025] If necessary, the friction stir welding machine 26 can be incorporated into a vacuum housing as shown in Figure 7, and if necessary, in the same vacuum housing 36 as the electron beam assembly 20, oxidation of the friction stir welding head is prevented, thereby extending the life of the friction stir welding tool. The electron beam gun 28 and the friction stir welding machine 26 weld from opposite sides along the same joint line, and the friction stir welding machine 26 finishes the root pass weld before the electron beam gun finishes the root pass weld.
[0026] As shown in Figure 8, when rolling the weld metal sheet to form a final cylinder 58 that requires welding along the final seam 60, optionally, as shown in Figure 9, the edges 62, 64 are milled using a milling cutter 50 before butting them together and friction stir welding. Although the embodiment shown in Figure 9 uses argon shielding, if necessary, an electron beam assembly 70 and friction stir welder 26 positioned in an exhaust housing 74 can be used, as shown in Figure 10, and the housing 74 can be exhausted using vacuum ports 76, 76'. The friction stir welder 26 generates a root pass weld along the joint weld line 60 before electron beam welding is performed.
Claims
1. A method for welding metal plates, i) A step of initiating friction stir welding using a friction stir welding machine along the lower edge of a joint weld between adjacent metal plates weighing more than 50 tons in order to generate a root pass weld along the joint weld line, wherein the friction stir welding machine is positioned below the plates in an upward position for welding, ii) After friction stir welding, initiating electron beam welding using an electron beam gun along the upper edge of the joint weld line to create a weld seam between adjacent plates, the steps being to position the electron beam gun on the plates. A method that includes this.
2. The method according to claim 1, wherein each metal plate has dimensions of approximately 10 m in length, approximately 4 m in width, and a thickness between 90 mm and 130 mm.
3. The method according to claim 1 or 2, wherein at least three adjacent metal plates are welded together to form a pipe having a diameter of more than 11 m.
4. The method according to any one of claims 1 to 3, further comprising the steps of replacing the welding head of the friction stir welding machine with a milling head, and milling along the joint weld line before friction stir welding is performed.
5. The method according to any one of claims 1 to 4, wherein the root path weld has a depth of 12 mm to 20 mm.
6. The method according to any one of claims 1 to 5, wherein the electron beam welding is performed in a vacuum.
7. The method according to any one of claims 1 to 6, wherein the friction stir welding is performed in a vacuum.
8. The method according to any one of claims 1 to 7, wherein the electron beam welding and the friction stir welding are performed in a common exhaust housing.
9. The method according to any one of claims 1 to 7, wherein the metal plate is movable along a conveyor, the friction stir welding machine and the electron beam gun are located away from the direction of movement of the metal plate, and the friction stir welding machine is located upstream of the electron beam gun.
10. The method according to any one of claims 1 to 9, wherein the metal plate is formed from one or more of steel, C-Mn structural steel, alloy steel, nickel, titanium, aluminum, nickel alloy, titanium alloy, and aluminum alloy.
11. A metal tube formed according to the method described in any one of claims 1 to 10.
12. The metal pipe according to claim 11, having a diameter exceeding 11 m.