A trunnion support welding device and a support welding method for a large-diameter pressure-resistant shell

Abstract

This invention discloses a trunnion support welding device and method for large-diameter pressure-resistant housings. The trunnion support welding device includes a trunnion support fixture and a connecting support fixture. The trunnion support fixture includes a circular plate, a first H-beam perpendicularly fixed to one side of the circular plate, and an intermediate plate fixed to the end of the first H-beam. The end face of the circular plate is machined with a stop for interference or transition fit with the inner hole of the trunnion to be welded. The connecting support fixture includes a second H-beam and connecting plates respectively fixed to both ends of the second H-beam. Through the above device and method, two independent trunnions are transformed into a whole constrained by an internal rigid frame during the welding process, thereby ensuring high coaxiality accuracy of the final product. The device of this invention is easy to assemble and disassemble, reliable in performance, and reusable. The method steps are clear and effective, and it is particularly suitable for welding trunnions of pressure-resistant housings with large diameter and high precision requirements.

Description

Technical Field

[0001] This invention relates to the field of manufacturing technology for large pressure vessels and deep-sea equipment, and more specifically, to a trunnion support welding device and support welding method for large-diameter pressure hulls. Background Technology

[0002] Large-diameter pressure hulls are the core pressure-bearing structures of equipment such as deep-sea submersibles and underwater workstations. Their manufacturing precision directly affects the load-bearing capacity, sealing reliability, and service life of the entire equipment. These hulls typically require symmetrical trunnions welded to both sides for connection to the external frame or as hoisting fulcrums. The high precision requirements for trunnion welding, especially extremely high coaxiality (e.g., ≤Φ0.3mm), pose a significant challenge in the manufacturing process.

[0003] Traditional methods typically involve directly machining trunnion mounting holes into the cylinder body, then inserting and welding the trunnion in place. This method has significant drawbacks: First, when welding thick-walled trunnions directly to thin-walled cylinder bodies, the massive concentrated heat input causes severe localized shrinkage deformation of the cylinder body, resulting in out-of-tolerance roundness and misalignment of the pre-machined trunnion mounting holes. Second, the welding process lacks effective positioning and rigid support for the trunnion, making it prone to fretting under thermal stress, thus compromising the coaxiality of both trunnions after welding. Even with precise alignment during assembly, welding deformation can compromise this precision. Therefore, traditional processes struggle to consistently meet high-precision coaxiality requirements, and rework is difficult and costly. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a trunnion support welding device and support welding method for large-diameter pressure-resistant housings that can effectively suppress welding deformation and ensure coaxiality of both trunnions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A trunnion support welding device for large-diameter pressure-resistant housings, the trunnion support welding device includes a trunnion support fixture and a connecting support fixture; The trunnion support fixture includes a circular plate, a first H-beam vertically fixed to one side of the circular plate, and an intermediate plate fixed to the end of the first H-beam. The end face of the circular plate is machined with a stop for interference or transition fit with the inner hole of the trunnion to be welded through machining. The edge of the circular plate is evenly distributed with threaded holes along the circumference. At least one first through hole is provided on the intermediate plate. The connecting support fixture includes a second H-beam and connecting plates respectively fixed to both ends of the second H-beam. The connecting plates are provided with a second through hole corresponding to the first through hole. The trunnion support fixture and the connecting support fixture are detachably fixedly connected by a connector that passes through the first through hole and the second through hole, so that the first H-beam and the second H-beam are parallel to each other and form an internal rigid support frame.

[0006] Furthermore, the trunnion support fixture also includes a reinforcing plate welded to the first H-beam and close to the circular plate side; the connecting support fixture also includes a reinforcing plate welded to the second H-beam, with the reinforcing plates on the first H-beam and the second H-beam distributed on the same side.

[0007] Furthermore, each of the reinforcing plates is machined with lifting holes.

[0008] Furthermore, the connector includes a hexagonal head bolt, a flat washer, a standard spring washer, and a hexagonal nut that pass through in sequence.

[0009] A method for supporting and welding trunnions on both sides of a large-diameter pressure-resistant housing is also provided, using the trunnion support and welding device described above. The support and welding method includes the following steps: S1. Prepare the cylinder body, and after welding stiffening plates on the cylinder body, machine out the symmetrical trunnion mounting holes on both sides; S2. Connect and fix the connecting support fixture and the trunnion support fixture through a connector to form a trunnion support welding device; according to the inner hole size of the trunnion to be installed, respectively machine stop edges that are interference fit or transition fit with the inner hole of the trunnion to be installed on the two circular plates of the trunnion support fixture. S3. Sleeve the trunnion onto the stop of the circular plate and fix it to form a trunnion-device assembly; S4. Insert the trunnion-device assembly into the symmetrical trunnion mounting holes on both sides; S5. Following the symmetrical welding process, weld the two trunnions to the cylinder body. After welding, grind the weld. Then, weld trunnion reinforcing ribs around the trunnions. S6. After welding is completed, remove the connector, move the connecting support fixture away, and then take out the trunnion support fixture from the inner hole of each of the two trunnions.

[0010] Further, in step S2), the specific process of connecting and fixing the connecting support fixture and the trunnion support fixture to form the trunnion support welding device via connectors is as follows: install lifting eye bolts in the lifting holes of the trunnion support fixture and the connecting support fixture respectively, and then pull the connecting support fixture from the lower end to the upper end until the lifting holes of the trunnion support fixture and the connecting support fixture are on the same horizontal line; fix the trunnion support fixture and the connecting support fixture in the first through hole of the intermediate plate and the second through hole of the connecting plate with hexagonal head bolts, flat washers, standard spring washers, and hexagonal nuts.

[0011] Further, the specific process of installing the trunnion-device assembly into the symmetrical trunnion mounting holes in step S4) is as follows: Before assembly, measure the diameter of the trunnion and the size of the symmetrical trunnion mounting holes on both sides, and insert it into the cylinder from the end of the trunnion mounting hole with the larger gap, so that the trunnion is located in the trunnion mounting hole on that side; adjust the device so that the trunnion support fixture on the other side is aligned with the trunnion mounting hole on the opposite side, insert the second trunnion from the opposite side and make its inner hole fit on the corresponding stop; use the trunnion fixing bracket to temporarily spot weld the two trunnions to the cylinder.

[0012] Furthermore, in step S1, symmetrical welding is used when welding the stiffening plates to control deformation.

[0013] Furthermore, in step S4, 6-12 trunnion fixing brackets are arranged approximately evenly along the circumference of the trunnion.

[0014] Furthermore, the welding of the trunnion in step S5 includes front welding and back welding after root cleaning.

[0015] The technology, principle, and effects of this invention are described in detail below: 1. This invention utilizes a device comprising a rigid beam support structure with a detachable connection and an internally machined stop, combined with the welding method of this invention, for high-precision welding of symmetrical trunnions on both sides of a large-diameter pressure-resistant housing. It fundamentally suppresses the influence of welding thermal deformation on the trunnion position, and in particular, can stably achieve an extremely high coaxiality requirement of ≤0.3mm, solving the core problem of unsatisfactory coaxiality in traditional processes.

[0016] Traditional methods involve directly welding thick-walled trunnions to thin-walled cylinders. The massive concentrated heat input causes severe shrinkage and deformation of the cylinder, compromising roundness and misaligning the pre-machined trunnion mounting holes. Furthermore, the lack of effective constraints on the trunnions during welding makes it difficult to guarantee coaxiality. This invention pre-assembles the trunnions and support device into a rigid assembly externally, then inserts the entire assembly into the housing. During welding, an internal rigid support frame (composed of H-beams and connectors) rigidly locks both trunnions in three-dimensional space, forming a high-rigidity internal frame.

[0017] 2. The trunnion support fixture of the device of the present invention is provided with a machineable stop for interference or transition fit with the inner hole of the trunnion. This eliminates the influence of the cumulative manufacturing tolerances of the trunnion parts and the fixture itself on the positioning accuracy, ensuring that each device can achieve precise positioning with the corresponding trunnion, and improving the adaptability of the method and the consistency and reliability of the final accuracy.

[0018] Different trunnions have manufacturing tolerances in their inner bore dimensions. If the tooling stop size is fixed, the manufacturing tolerances of the trunnion and the tooling will overlap, affecting the final positioning accuracy. This invention employs a fitting process. After the device is assembled, the stop on the tooling is precision machined according to the actual dimensions of the inner bore of the trunnion to be welded, ensuring optimal fit with the trunnion.

[0019] 3. The trunnion support welding device of the present invention adopts a detachable connection (such as bolt connection), and the tooling is provided with lifting holes. This greatly improves the convenience and operability of the device in the limited space inside a large housing, making the tooling applicable to actual large product manufacturing environments and improving work efficiency.

[0020] Large pressure housings typically have limited internal space, making it difficult to transport and install bulky, monolithic fixtures. This invention divides the device into two parts: a trunnion support fixture and a connecting support fixture, which are detachably connected by bolts. After welding, the connecting support fixture can be disassembled first, and then the smaller trunnion support fixture can be removed from the inner holes of the trunnions on both sides. Lifting holes facilitate hoisting and position adjustment both inside and outside the housing.

[0021] 4. The welding method of this invention involves fitting the trunnion onto a pre-machined stop device to form an assembly. The assembly is then inserted into the housing through the hole on the side with the larger gap, adjusted, and temporarily fixed. Symmetrical welding is then performed, and the device is removed after welding. This method not only ensures the coaxiality of the trunnion but also effectively protects the original roundness of the cylinder and the positional accuracy of the pre-machined trunnion mounting holes. It achieves systematic control over welding deformation and improves the manufacturing precision and quality stability of the entire housing structure.

[0022] This invention systematically combines assembly, positioning, rigid support, and welding processes. Pre-assembly of the trunnion-device assembly ensures precise alignment of the trunnion using tooling before welding; installation from the side with the larger gap solves the installation path problem of the overall rigid frame within a limited space; during welding, the internal rigid beam structure bears and offsets welding thermal stress, while the external symmetrical welding process further evens out heat input, reducing the overall deformation of the cylinder. The dual control mechanisms (internal rigid constraint + external symmetrical welding) work together.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention achieves precise positioning of the trunnion through a machineable stop, and then firmly locks the relative position of the two trunnions during the welding process through an internal rigid beam structure, fundamentally suppressing the influence of welding deformation on coaxiality, and can stably achieve the high coaxiality requirement of ≤Φ0.3mm.

[0024] 2. The rigid internal support structure and symmetrical welding process of this invention form a dual deformation control mechanism, which effectively protects the original roundness of the cylinder and the positional accuracy of the trunnion mounting hole.

[0025] 3. The device of the present invention has a robust structure and can be reused; the design of the stop and machining makes it adaptable to different sizes of trunnions, and has strong versatility; the detachable connection design makes the device easy to assemble and disassemble in a narrow space.

[0026] 4. The welding method of the present invention improves welding efficiency and quality stability, and is suitable for standardized operations of welding large pressure-resistant shell trunnions. Attached Figure Description

[0027] Figure 1 A schematic diagram of a large-diameter pressure-resistant shell structure to be welded; Figure 2 This is a schematic diagram of the overall structure of the welding support device of the present invention; Figure 3 for Figure 2 A magnified view of part I in the middle; Figure 4 for Figure 2 Front view of the trunnion support fixture; Figure 5 for Figure 2 Left view of the trunnion support fixture; Figure 6 for Figure 2 Main view of the connecting support fixture; Figure 7 for Figure 2 Left view of the connecting support fixture; Figure 8 This is a schematic diagram showing the assembly state of the device of the present invention with the trunnion and the housing.

[0028] In the diagram: 1-Large diameter pressure-resistant shell, 2-Cylinder body, 3-Firming plate, 4-Ternary mounting hole, 5-Ternary, 6-Ternary reinforcing rib, 7-Support welding device, 8-Ternary support fixture, 9-Connecting support fixture, 10-Hex head bolt, 11-Flat washer, 12-Standard spring washer, 13-Hex nut, 14-Round plate, 15-First H-beam, 16-Intermediate plate, 17-Reinforcing plate, 18-Lifting hole, 19-Threaded hole, 20-First through hole, 21-Second H-beam, 22-Connecting plate, 23-Second through hole, 24-Ternary inner hole, 25-Stop, 26-Ternary fixing bracket. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. This embodiment takes a pressure-resistant shell with an inner diameter of Φ4.2m, a wall thickness of 25mm, and a requirement that the coaxiality of the trunnions on both sides be ≤Φ0.3mm as an example.

[0030] like Figure 1As shown, the workpiece to be welded is a large-diameter pressure-resistant shell 1. The main body of the large-diameter pressure-resistant shell 1 is a rolled and welded cylinder 2. Several stiffening plates 3 have been welded on the cylinder 2 to enhance its rigidity, and symmetrical trunnion mounting holes 4 are precisely machined on both sides.

[0031] like Figures 2 to 7 As shown, the trunnion support welding device 7 of the present invention includes a trunnion support fixture 8 and a connecting support fixture 9. The trunnion support fixture 8 includes a circular plate 14, a first H-beam 15 vertically fixed to one side of the circular plate 14, and an intermediate plate 16 fixed to the end of the first H-beam 15. The circular plate 14, the first H-beam 15, and the intermediate plate 16 are welded together, and a reinforcing plate 17 is welded on the first H-beam 15 and close to the side of the circular plate 14. All connections are continuous fillet welds, and the weld height shall not be less than 70% of the thickness of the thin plate. After welding, leveling is performed to improve the overall flatness. The end face of the circular plate 14 is machined with a stop 25 for interference or transition fit with the inner hole of the trunnion 5 through machining (the final size of the stop needs to be machined, see...). Figure 3 The circular plate 14 has threaded holes 19 evenly distributed around its circumference, and the intermediate plate 16 has at least one first through hole 20. The connecting support fixture 9 includes a second H-beam 21 and connecting plates 22 respectively fixed to both ends of the second H-beam 21. The second H-beam 21 and the connecting plates 22 are welded together, and a reinforcing plate 17 is welded on the second H-beam 21. All connections are continuous fillet welds, and the weld height shall not be less than 70% of the thickness of the thin plate. After welding, the plate is leveled to improve the overall flatness. The connecting plate 22 has a second through hole 23 corresponding to the first through hole 20. At the same time, the reinforcing plates 17 on the first H-beam 15 and the reinforcing plates 17 on the second H-beam 21 are distributed on the same side, and all reinforcing plates 17 are machined with lifting holes 18.

[0032] The trunnion support fixture 8 and the connecting support fixture 9 are detachably fixedly connected by a connector passing through the first through hole 20 and the second through hole 23, so that the first H-beam 15 and the second H-beam 21 are parallel to each other and form an internal rigid support frame. The connector includes a hexagonal head bolt 10, a flat washer 11, a standard spring washer 12 and a hexagonal nut 13 passing through in sequence.

[0033] The specific welding method is as follows: S1. Shell Prefabrication: During the rolling and welding of the cylinder 2, the weld gap must be controlled (e.g., 2.5-3mm) and the surface must be ground smooth after welding to ensure sufficient overall roundness and dimensional stability of the cylinder, providing a reliable foundation for subsequent high-precision machining of the trunnion mounting holes. Position lines for the locating stiffeners 3 and the double-sided trunnion mounting holes 4 are marked on the cylinder. All stiffeners 3 are welded using anti-deformation techniques such as symmetrical skip welding. Finally, the double-sided symmetrical trunnion mounting holes 4 are machined on a large boring machine using precision clamping and alignment, ensuring the initial coaxiality of the two holes.

[0034] S2. Assembly and Machining: Install eye bolts in the lifting holes 18 of the trunnion support fixture 8 and the connecting support fixture 9, respectively. Then pull the connecting support fixture 9 from end A (lower end) to end B (upper end) until the lifting holes 18 of the trunnion support fixture 8 and the connecting support fixture 9 are on the same horizontal line. The first through hole 20 of the intermediate plate 16 and the second through hole 23 of the connecting plate 22 are fixed to the trunnion support fixture 8 and the connecting support fixture 9 by using hexagonal head bolts 10, flat washers 11, standard spring washers 12, and hexagonal nuts 13, forming a complete internal support frame. Use precision measuring tools to measure the actual size of the trunnion inner hole 24 of the trunnion 5 to be welded. Based on this, perform machining on the stop 25 (including the outer circle, fillet, and chamfer) on the circular plate 14 of the trunnion support fixture 8 to ensure a transition fit with the trunnion inner hole and provide a precise positioning reference.

[0035] S3, Trunnion and assembly pre-installed: such as Figure 8 As shown, two trunnions 5 are respectively fitted onto the stop 25 of the trunnion support fixture 8 on both sides of the device to form a trunnion-device assembly. Since the stop is machined, a tight and accurate fit can be achieved.

[0036] S4. Overall Installation and Positioning: Before assembly, measure the diameter of the trunnion 5 and the dimensions of the symmetrical trunnion mounting holes 4 on both sides. Using the lifting hole 18, insert the assembled trunnion-device assembly into the cylinder 2 from the end of the trunnion mounting hole 4 with the larger gap, so that the trunnion 5 is located in the trunnion mounting hole 4 on that side. Adjust the device so that the trunnion support fixture 8 on the other side is aligned with the trunnion mounting hole 4 on the opposite side. Insert the second trunnion 5 from the opposite side and fit its inner hole onto the corresponding stop 25. Use the 8 trunnion fixing brackets 26 to roughly distribute them evenly along the circumference and spot weld them to the cylinder 2 to complete the initial positioning and fixing.

[0037] S5. Symmetrical Welding and Reinforcement: Following the predetermined welding procedure, symmetrical welding is performed on the circumferential seams of the trunnions 5 and the cylinder 2. Typically, the main weld on one side is welded first, followed by root cleaning of the back of the weld before welding the other side to ensure complete penetration. During welding, the internal trunnion support welding device 7 acts as an internal rigid support frame, significantly suppressing displacement of the trunnion due to uneven heating. After welding, the weld is ground to meet non-destructive testing requirements. Finally, the designed trunnion reinforcing ribs 6 are welded around the trunnion, also using symmetrical welding to control deformation, followed by grinding.

[0038] S6. Device Disassembly: After the weld has completely cooled, first remove all trunnion fixing brackets 26. Then, loosen and remove the connectors connecting the two support fixtures. Move the connecting support fixture 9 to one side (end A) to detach it, and then remove the trunnion support fixtures 8 from the inner holes of the trunnions 5 on both sides in sequence to complete the entire welding support process.

[0039] The above-described device and method transform two independent trunnions into a single unit constrained by an internal rigid frame during the welding process, thereby ensuring high coaxiality accuracy of the final product. This invention features a convenient and reliable device that is reusable, with clear and effective steps, making it particularly suitable for welding pressure-resistant housing trunnions with large diameters and high precision requirements.

[0040] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A trunnion support welding device for large-diameter pressure-resistant housings, characterized in that, The trunnion support welding device includes a trunnion support fixture (8) and a connecting support fixture (9); The trunnion support fixture (8) includes a circular plate (14), a first H-beam (15) vertically fixed to one side of the circular plate (14), and an intermediate plate (16) fixed to the end of the first H-beam (15). The end face of the circular plate (14) is machined with a stop (25) for interference or transition fit with the inner hole of the trunnion (5) to be welded. The edge of the circular plate (14) is evenly distributed with threaded holes (19) in the circumferential direction. The intermediate plate (16) is provided with at least one first through hole (20). The connecting support fixture (9) includes a second H-beam (21) and connecting plates (22) fixed to both ends of the second H-beam (21). The connecting plates (22) are provided with a second through hole (23) corresponding to the first through hole (20). The trunnion support fixture (8) and the connecting support fixture (9) are detachably fixedly connected by a connector that passes through the first through hole (20) and the second through hole (23), so that the first H-beam (15) and the second H-beam (21) are parallel to each other and form an integral rigid beam structure.

2. The trunnion support welding device according to claim 1, characterized in that, The trunnion support fixture (8) also includes a reinforcing plate (17) welded to the first H-beam (15) and close to the circular plate (14); the connecting support fixture (9) also includes a reinforcing plate (17) welded to the second H-beam (21), and the reinforcing plate (17) on the first H-beam (15) and the reinforcing plate (17) on the second H-beam (21) are distributed on the same side.

3. The trunnion support welding device according to claim 2, characterized in that, Each of the reinforcing plates (17) is machined with lifting holes (18).

4. The trunnion support welding device according to claim 1, characterized in that, The connector includes a hexagonal head bolt (10), a flat washer (11), a standard spring washer (12), and a hexagonal nut (13) that pass through in sequence.

5. A method for supporting and welding symmetrical trunnions on both sides of a large-diameter pressure-resistant housing, characterized in that, The trunnion support welding apparatus according to any one of claims 1-4, wherein the support welding method comprises the following steps: S1. Prepare the cylinder (2), and weld the reinforcing plate (3) on the cylinder (2), and then process the trunnion mounting holes (4) with double symmetrical sides. S2. Connect and fix the connecting support fixture (9) and the trunnion support fixture (8) through the connector to form a trunnion support welding device (7); according to the actual size of the inner hole of the trunnion (5) to be installed, respectively machine stop (25) on the two circular plates (14) of the trunnion support fixture (8) to be interference fit or transition fit with the inner hole of the trunnion (5) to be installed. S3. The trunnion (5) is fitted and fixed on the stop (25) of the circular plate (14) to form a trunnion-device assembly; S4. Insert the trunnion-device assembly into the trunnion mounting holes (4) on both sides symmetrically. S5. Following the symmetrical welding process, the two trunnions (5) are welded and fixed on the cylinder (2). After the welding is completed, the weld is ground. Then, trunnion reinforcing ribs (6) are welded around the trunnions (5). S6. After welding is completed, remove the connector, move the connecting support fixture (9) away, and then take out the trunnion support fixture (8) from the inner hole of each of the two trunnions (5).

6. According to the support welding method of claim 5, the specific process of connecting and fixing the connecting support fixture (9) and the trunnion support fixture (8) to form the trunnion support welding device (7) in step S2) is as follows: install lifting eye screws in the lifting holes (18) of the trunnion support fixture (8) and the connecting support fixture (9) respectively, and then pull the connecting support fixture (9) from the lower end to the upper end until the lifting holes (18) of the trunnion support fixture (8) and the connecting support fixture (9) are on the same horizontal line; fix the trunnion support fixture (8) and the connecting support fixture (9) through the first through hole (20) of the intermediate plate (16) and the second through hole (23) of the connecting plate (22) with hexagonal head bolts (10), flat washers (11), standard spring washers (12) and hexagonal nuts (13).

7. According to the support welding method of claim 5, the specific process of installing the trunnion-device assembly into the symmetrical trunnion mounting holes (4) in step S4) is as follows: Before assembly, measure the diameter of the trunnion (5) and the size of the symmetrical trunnion mounting holes (4) on both sides, and install it into the cylinder (2) from one end of the trunnion mounting hole (4) with a larger gap, so that the trunnion (5) is located in the trunnion mounting hole (4) on that side; adjust the device so that the trunnion support fixture (8) on the other side is aligned with the trunnion mounting hole (4) on the opposite side, install the second trunnion (5) from the opposite side and make its inner hole fit on the corresponding stop (25); use the trunnion fixing bracket (26) to temporarily spot weld the two trunnions (5) to the cylinder (2).

8. The method according to claim 5, characterized in that, In step S1, symmetrical welding is used when welding the stiffening plate (3) to control deformation.

9. The method according to claim 5, characterized in that, In step S4, 6-12 trunnion fixing irons (26) are arranged approximately evenly along the circumference of the trunnion (5).

10. The method according to claim 5, characterized in that, The welding of the trunnion (5) in step S5 includes front welding and back welding after root cleaning.

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