Method of assembling a metal housing with lugs

Abstract

The application discloses a kind of assembly method and assembly tool of metal shell with lug, utilize coaxality control tool, the original process flow: scribe→assembly→positioning welding, is simplified as assembly→positioning welding, through coaxality control tool, cooperation welding auxiliary tool and positioning welding, realize the assembly of metal shell with external feature structure, complete positioning welding process under the condition of tool.The application utilizes coaxality control tool to realize the positioning of multiple lugs and cylinder assembly once.Coaxality control tool has the characteristics of flexibility, by designing replacement inner profile slider, outer profile slider size and adjusting inner profile slider, outer profile slider position on column, realize the assembly positioning of multiple size lugs.Product verification shows that the coaxality of lug is less than 0.3mm, which avoids the over-difference situation caused by manual alignment assembly, effectively ensures the assembly accuracy.Furthermore, it reduces the complexity of assembly, improves the production efficiency, and saves 8-10 minutes compared with the prior art in the whole assembly positioning process.

Description

Technical Field

[0001] This invention relates to the field of pressure vessel shell manufacturing, specifically a method for ensuring the assembly accuracy of shells with multiple lifting lugs. Background Technology

[0002] A certain pressure vessel product is assembled from multiple lifting lugs and a cylindrical body by welding. The product's structural characteristics require that the coaxiality of the lifting lugs after welding be no greater than 0.5mm, necessitating sufficient machining allowance for the next machining process. The initial assembly method involves pre-marking and manual assembly. This method is highly dependent on manual labor and cannot effectively guarantee coaxiality, leading to multiple reworks and reassemblies due to coaxiality deviations, thus impacting production efficiency.

[0003] A utility model patent with publication number CN216263971U discloses a tooling for argon arc welding that can guarantee coaxiality. This tooling proposes a lower support and a top pressure cap mechanism, using locating pins to position and constrain the coaxiality of the parts to be welded. Although the tooling structure is simple, it cannot simultaneously position and weld two or more rotating parts.

[0004] Chinese patent publication CN113977486B discloses a positioning mechanism and assembly method for maintaining the coaxiality of grinding discs in a double-disc refiner. The method proposes to restrict the movement of the machine body and cover through bolt connections, and then effectively ensure the coaxiality of the machine body and cover by using pin holes on the positioning plate. However, this tooling does not consider the adjustment of misalignment after assembly. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies where assembly efficiency and precision cannot be simultaneously achieved, this invention proposes an assembly method and assembly fixture for a metal shell with lifting lugs.

[0006] This invention relates to an assembly method for a metal shell with lifting lugs. The metal shell with lifting lugs has a multi-segment structure, each segment consisting of a lifting lug welded to a cylindrical component. The lifting lug is annular, with radially protruding lifting blocks on its outer circumference. The lifting blocks cooperate with a slider on an assembly fixture to achieve the assembly of the metal shell with lifting lugs. The lifting lugs are classified into outer surface lifting lugs and inner surface lifting lugs based on the profile of the surface where the lifting block mates with the slider.

[0007] The specific process is as follows:

[0008] Step 1, Preliminary assembly:

[0009] According to the design, the cylindrical component in the metal housing, which is assembled with the lifting lug, is vertically placed on the upper surface of the base plate of the coaxiality control fixture. The lifting lug is placed on the upper end face of the cylindrical component, and the two are made coaxial. The lifting lug can be an external surface lifting lug or an internal surface lifting lug.

[0010] When using an external surface lifting lug, the external surface slider of the coaxiality control tooling is embedded in the slider groove on the column according to the axial dimension of the lifting lug, so that the external surface slider is fully constrained, ensuring that no movement or circumferential rotation occurs during the assembly process, and that the inner surface of the external surface slider groove on the external surface slider is in contact with the two side surfaces of the lifting lug.

[0011] When using an inner surface lifting lug, the inner surface slider of the coaxiality control fixture is embedded in the slider groove on the column according to the axial dimension of the lifting lug, so that the inner surface slider is fully constrained, ensuring that no movement or circumferential rotation occurs during assembly, and that the surfaces on both sides of the inner surface slider are in contact with the inner surface of the lifting lug.

[0012] Step 2, assemble the first section.

[0013] Adjust the misalignment and gap between the first cylindrical part and the first lifting lug using welding fixtures, so that the misalignment is <0.2mm and the gap is <0.3mm.

[0014] Slide the limiting rod along the groove (7) in the base plate so that the inner surface of the limiting rod contacts the outer circumferential surface of the cylindrical part, and fix the limiting rod with the tightening bolt to achieve constraint on the cylindrical part. Assemble the first cylindrical part and the first lifting lug into place to complete the assembly of the first section.

[0015] The welding fixture comprises multiple components, each used for assembling different sections. Each fixture includes a circular top cylinder, adjusting bolts, and adjusting nuts. In use, the circular top cylinder is fitted onto the outer circumference of the cylindrical component, ensuring it is coaxial with the component. The tightness of the adjusting bolts is then adjusted to regulate the misalignment and gap between the cylindrical component and the lifting lug.

[0016] Step 3: Assemble the remaining sections.

[0017] Repeat step 2 to continue assembling the cylindrical component and other lifting lugs. Specifically,

[0018] Place the second cylindrical component on the upper surface of the first lifting lug; fit the second welding fixture onto the second cylindrical component using the same method as when assembling the first cylindrical component. Repeat the process of adjusting the misalignment and gap between the cylindrical component and the lifting lug during the assembly of the first section, and adjust the misalignment and gap between the second cylindrical component and the first lifting lug.

[0019] Place the second lifting lug on the upper end face of the second cylindrical component; mate the inner or outer surface slider with the surface of the lifting lug and fix it in place. Repeat the process of adjusting the misalignment and gap between the second cylindrical component and the first lifting lug, adjusting the misalignment and gap between the second lifting lug and the second cylindrical component.

[0020] This completes the assembly of the second section.

[0021] Repeat the assembly process between the second cylindrical component and the second lifting lug, and then complete the assembly of the remaining sections in sequence.

[0022] Step 4, tack welding.

[0023] After assembling the remaining sections in sequence, argon arc welding is used to spot weld and position each weld seam according to the process requirements. During spot welding, the spot welds must be evenly distributed, with each pair of spot welds forming a group, and each group of welds symmetrically distributed at 180°.

[0024] After spot welding and positioning at each weld location, the metal shell with lifting lugs is welded according to process requirements.

[0025] At this point, the welding and assembly of the metal shell with lifting lugs is complete.

[0026] The coaxiality control fixture for the metal housing equipped with lifting lugs proposed in this invention includes a base plate, a slider, a column, and a limiting rod; the slider includes an inner surface slider and an outer surface slider. The column is vertically welded and fixed to the surface of the base plate, and the geometric center of the column is located on the center line of the width direction of the base plate; the distance between the surface of the column near the limiting rod and the edge of the base plate must be greater than the outer diameter of the cylindrical component.

[0027] One surface of the base plate along its length has a pair of limit rod grooves for mounting limit rods and extending along the length of the base plate.

[0028] The column has multiple slider grooves evenly distributed along its height on one side surface; the sliders are respectively embedded and fixed in the slider grooves on the surface of the column; the number of sliders increases or decreases according to the number of lifting lugs.

[0029] The limiting rod is located on the upper surface of the base plate, and its two ends are engaged in a pair of limiting rod grooves on the upper surface of the base plate; there are tightening bolts on the limiting rod.

[0030] After welding and assembly, the perpendicularity between the column and the base plate is ≤0.2°.

[0031] The geometric center distance between adjacent slider slots is 50mm.

[0032] The outer surface slider is U-shaped, and the inner groove surface is the surface that mates with the outer surface lug; the two side surfaces of the inner surface slider are the surfaces that mate with the inner surface lug. The outer surface slider and the inner surface slider have similar structures, except that the top surface of the outer surface slider is machined with a slider groove, the dimensions of which match the radial dimensions of the lug to prevent it from rotating around the axis during assembly.

[0033] This invention addresses the shortcomings of existing assembly methods, which cannot simultaneously achieve both assembly efficiency and precision. By designing coaxiality control tooling, combined with conventional welding tooling and a reasonable locating welding method, it efficiently assembles metal shells with multi-section lifting lugs.

[0034] This invention utilizes coaxiality control fixtures to simplify the original process flow from scribing → assembly → tack welding to assembly → tack welding, eliminating the scribing step. The specific method is as follows:

[0035] First, place the cylindrical component end to be assembled with the lifting lug on the upper surface of the base plate. Then, align the outer surface slider with the axial dimension of the lifting lug and embed it into the appropriate slot in the column. Tighten the outer surface slider with M10 bolts to achieve a fully constrained state, ensuring no movement or rotation occurs during assembly. Fit the outer surface of the lifting lug structure with the inner surface of the slot of the outer surface slider 3 to prevent rotation around the axis. Simultaneously, initially align the cylindrical component end with the lifting lug end; the cylindrical component will support the lifting lug and prevent it from falling directly. Use conventional welding fixtures to adjust the misalignment and gap between the cylindrical component and the lifting lug to meet welding process requirements: misalignment no greater than 0.2mm and gap less than 0.5mm. Next, adjust the position of the limiting rod along the sliding groove direction in the base plate 1 to constrain the movement of the cylindrical component. After adjusting the position, clamp and fix the limiting rod 5 with two M6 bolts. This completes the assembly of one cylindrical component and one lifting lug. After assembly, with the tooling available, manual argon arc welding is used to complete the tack welding process by symmetrical tack welding.

[0036] The key technology in this invention lies in:

[0037] 1. By using coaxiality control tooling, welding auxiliary tooling, and tack welding, the assembly of metal shells with external feature structures can be achieved.

[0038] 2. Overall structure of the coaxiality control fixture.

[0039] This invention utilizes a coaxiality control fixture to achieve simultaneous assembly and positioning of multiple lifting lugs and cylinders. The coaxiality control fixture is flexible, allowing for the assembly and positioning of lifting lugs of various sizes by designing and changing the dimensions of the inner and outer surface sliders, as well as adjusting their positions on the column. Product verification shows that this invention can control the coaxiality of the lifting lugs within 0.3mm, avoiding the deviations that occur in existing manual alignment assembly and effectively ensuring assembly accuracy. Furthermore, compared to existing assembly methods, this invention reduces assembly complexity, improves production efficiency, and saves 8-10 minutes in the entire assembly and positioning process compared to existing technologies. Attached Figure Description

[0040] Figure 1It is the overall assembly drawing of the coaxiality control tooling.

[0041] Figure 2 This is a schematic diagram of the internal surface slider; where, Figure 2 'a' is the main view. Figure 2 b is the right view.

[0042] Figure 3 This is a structural schematic diagram of the outer surface slider; where, Figure 3 'a' is the main view. Figure 3 b is the right view.

[0043] Figure 4 This is a structural diagram of the column; among which, Figure 4 'a' is the main view. Figure 4 b is Figure 4 View AA in a, Figure 4 c is Figure 4 Enlarged view of part I in b

[0044] Figure 5 This is a schematic diagram of the lifting lug structure.

[0045] In the diagram: 1. Base plate; 2. Inner surface slider; 3. Outer surface slider; 4. Column; 5. Limiting rod; 6. Lifting lug; 7. Slide groove. Detailed Implementation

[0046] This embodiment describes an assembly method for a metal casing with lifting lugs.

[0047] The metal shell with lifting lugs has a multi-segment structure, each segment consisting of a lifting lug and a cylindrical component welded together; the structure of the lifting lugs is shown below. Figure 4 The assembly requirements for this metal shell must ensure that the coaxiality of the lifting lugs is ≤0.5mm; the misalignment is <0.2mm; the gap is <0.5mm; and the welding process requirements must be met.

[0048] The lifting lug is annular, with radially protruding lifting blocks on its outer circumference. These lifting blocks cooperate with a slider on an assembly fixture to assemble the metal shell with the lifting lug. The lifting lug is classified into external surface lifting lugs and internal surface lifting lugs based on the surface profile of the cooperation between the lifting block and the slider.

[0049] The specific process of this invention is as follows:

[0050] Step 1, preliminary assembly:

[0051] According to the design, the cylindrical component of the metal housing assembled with the lifting lug is vertically placed on the upper surface of the coaxiality control fixture base plate 1. The coaxiality control fixture is a tooling designed by this invention to achieve the technical objectives. During assembly and use, this fixture is placed on a horizontal worktable. The lifting lug is placed on the upper end face of the cylindrical component, and the two are made coaxial. The cylindrical component supports the lifting lug, preventing it from falling directly.

[0052] According to the design requirements of the metal shell, the lifting lug can be an external surface lifting lug or an internal surface lifting lug. When an external surface lifting lug is used, the external surface slider 3 of the coaxiality control fixture is embedded in the slider groove on the column 4 according to the axial dimension of the lifting lug, so that the external surface slider is fully constrained, ensuring that no movement or circumferential rotation occurs during assembly, and that the inner surface of the external surface slider groove on the external surface slider is in contact with the two side surfaces of the lifting lug.

[0053] When using an inner surface lifting lug, the inner surface slider 2 of the coaxiality control fixture is embedded in the slider groove on the column 4 according to the axial dimension of the lifting lug, so that the inner surface slider reaches a fully constrained state, ensuring that no movement or circumferential rotation occurs during the assembly process, and that the surfaces on both sides of the inner surface slider are in contact with the inner surface of the lifting lug.

[0054] The second step is to assemble the first section.

[0055] The misalignment and gap between the first cylindrical part and the first lifting lug are adjusted using conventional welding fixtures, so that the misalignment is less than 0.2 mm and the gap is less than 0.3 mm.

[0056] The welding fixture is a conventional external jack, consisting of a circular jack cylinder, adjusting bolts, and adjusting nuts. In use, the circular jack cylinder is fitted onto the outer circumference of the cylindrical component, and the circular jack cylinder is coaxial with the cylindrical component. The misalignment and gap between the cylindrical component and the lifting lug are adjusted by adjusting the tightness of the adjusting bolts.

[0057] The limiting rod 5 slides along the groove 7 in the base plate 1, so that the inner surface of the limiting rod contacts the outer circumferential surface of the cylindrical component, and the limiting rod is fixed by tightening bolts. This achieves constraint on the cylindrical component, assembling the first cylindrical component and the first lifting lug into place, completing the assembly of the first section.

[0058] The third step is to assemble the remaining sections.

[0059] Repeat step one to assemble the cylindrical component with the other lifting lugs. Specifically,

[0060] Place the second cylindrical component on the upper surface of the first lifting lug; fit the second welding fixture onto the second cylindrical component using the same method as when assembling the first cylindrical component. Repeat the process of adjusting the misalignment and gap between the cylindrical component and the lifting lug during the assembly of the first section, and adjust the misalignment and gap between the second cylindrical component and the first lifting lug.

[0061] Place the second lifting lug on the upper end face of the second cylindrical component; mate and fix the inner surface slider 2 or the outer surface slider 3 with the surface of the lifting lug. Repeat the process of adjusting the misalignment and gap between the second cylindrical component and the first lifting lug, adjusting the misalignment and gap between the second lifting lug and the second cylindrical component.

[0062] This completes the assembly of the second section.

[0063] Repeat the assembly process between the second cylindrical component and the second lifting lug, and then complete the assembly of the remaining sections in sequence.

[0064] Step 4: Tack welding.

[0065] After assembling the remaining sections in sequence, argon arc welding is used to spot weld and position each weld seam according to the process requirements. During spot welding, the spot welds must be evenly distributed, with each pair of spot welds forming a group, and each group of welds symmetrically distributed at 180°.

[0066] After spot welding and positioning at each weld location, the metal shell with lifting lugs is welded according to process requirements.

[0067] At this point, the welding and assembly of the metal shell with lifting lugs is complete.

[0068] The coaxiality control fixture proposed in this embodiment is made of 20 steel and includes a base plate 1, a slider, a column 4, and a limiting rod 5. The slider includes an inner surface slider 2 and an outer surface slider 3. The column is vertically welded and fixed to the surface of the base plate, and the geometric center of the column is located on the center line of the width direction of the base plate. The distance between the surface of the column near the limiting rod 5 and the edge of the base plate must be greater than the outer diameter of the cylindrical component.

[0069] After welding and assembly, the perpendicularity between the column 4 and the base plate 1 is ≤0.2°.

[0070] The base plate 1 is rectangular, and one surface of its length direction has a pair of limit rod grooves for mounting the limit rod 5 and extending along the length of the base plate.

[0071] The sliders are respectively embedded in the slider grooves on the surface of the column; the number of sliders increases or decreases according to the number of lifting lugs. Each slider is fixedly connected to the column by screws.

[0072] The column has multiple slider grooves evenly distributed along its height on one side surface; the geometric center distance between adjacent slider grooves is 50mm.

[0073] The limiting rod is located on the upper surface of the base plate, and its two ends are engaged in a pair of limiting rod grooves on the upper surface of the base plate; there are tightening bolts on the limiting rod.

[0074] In this embodiment, the base plate 1 has a length of ld = 990mm, a width of wd = 900mm, and a height of hd = 20mm; the limit rod groove has a length of 600mm, a width of 10mm, and a depth of 10mm. The column 4 is elongated, with a length of lz = 80mm, a width of wz = 50mm, and a height of hz = 2000mm. 39 slider grooves, each 30mm long, 20mm wide, and 32mm deep, are evenly distributed on the surface of the column. The geometric center distance between two adjacent slider grooves is 50mm, and each groove has a φ12 through hole machined at its bottom geometric center. The positions of the inner surface slider 2 and the outer surface slider 3 on the column can be arbitrarily adjusted through the slider grooves to cover and assemble a metal shell with lifting lugs whose total length is no greater than the height of the column 4.

[0075] The outer surface slider is U-shaped, with the inner groove surface being the surface that mates with the outer surface lug; the two side surfaces of the inner surface slider are the surfaces that mate with the inner surface lug. The outer surface slider 3 has a similar structure to the inner surface slider 2, except that the top surface of the outer surface slider is machined with a slider groove, the dimensions of which match the radial dimensions of the lug to prevent rotation around the axis during assembly. The limiting rod 5 has two M6 threaded holes symmetrically machined on it, which are clamped and fixed to the base plate 1 by bolts.

[0076] In this embodiment, the inner surface slider 2 is machined with a boss that is 30mm long, 20mm wide, and 32mm deep, and has a threaded hole with a depth of 40mm for connecting with the column 4. The top surface structural dimensions of the inner surface slider 2 match the inner surface dimensions of the inner surface lifting lug.

Claims

1. A method for assembling a metal shell with lifting lugs, characterized in that, The metal shell with lifting lugs has a multi-segment structure, each segment being welded together from a lifting lug and a cylindrical component; the lifting lug is annular, with radially protruding lifting blocks on the outer circumference of the annular ring; the lifting blocks cooperate with the slider on the assembly fixture to realize the assembly of the metal shell with lifting lugs; the lifting lugs are divided into outer surface lifting lugs and inner surface lifting lugs according to the profile of the lifting block and the slider; The assembly fixture includes a base plate (1), a slider, a column (4), and a limiting rod (5); the slider includes an inner surface slider (2) and an outer surface slider (3); the column is vertically welded and fixed to the surface of the base plate, and the geometric center of the column is located on the center line of the width direction of the base plate; the distance between the surface of the column near the limiting rod and the edge of the base plate must be greater than the outer diameter of the cylindrical part; The base plate (1) has a pair of limit rod grooves on one surface along its length for mounting the limit rod (5) and extending along the length of the base plate. The column has multiple slider slots evenly distributed along its height on one side surface; the sliders are respectively embedded and fixed in the slider slots on the surface of the column; the number of sliders increases or decreases according to the number of lifting lugs. The limiting rod is located on the upper surface of the base plate, and both ends of the limiting rod are engaged in a pair of limiting rod grooves on the upper surface of the base plate; there are tightening bolts on the limiting rod; The specific process is as follows: Step 1, Preliminary assembly: According to the design, the cylindrical component in the metal housing assembled with the lifting lug is vertically placed on the upper surface of the base plate of the coaxiality control fixture; the lifting lug is placed on the upper end face of the cylindrical component, and the two are made coaxial; the lifting lug is an external surface lifting lug or an internal surface lifting lug; Step 2, assemble the first section; The misalignment and gap between the first cylindrical part and the first lifting lug are adjusted by welding fixtures so that the misalignment is less than 0.2mm and the gap is less than 0.3mm. Slide the limiting rod (5) along the sliding groove (7) in the bottom plate (1) so that the inner surface of the limiting rod contacts the outer circumferential surface of the cylindrical part and fixes the limiting rod with the tightening bolt to achieve the constraint of the cylindrical part; assemble the first cylindrical part and the first lifting lug into place to complete the assembly of the first section; Step 3: Assemble the remaining sections; Repeat step 2 to continue assembling the cylindrical component and other lifting lugs; specifically, Place the second cylindrical component on the upper end face of the first lifting lug; fit the second welding fixture onto the second cylindrical component using the same method as when assembling the first cylindrical component; repeat the process of adjusting the misalignment and gap between the cylindrical component and the lifting lug during the assembly of the first section, and adjust the misalignment and gap between the second cylindrical component and the first lifting lug. Place the second lifting lug on the upper end face of the second cylindrical piece; fit the inner surface slider (2) or the outer surface slider (3) with the surface of the lifting lug and fix it; repeat the process of adjusting the misalignment and gap between the second cylindrical piece and the first lifting lug, and adjust the misalignment and gap between the second lifting lug and the second cylindrical piece. This completes the assembly of the second section; Repeat the assembly process between the second cylindrical component and the second lifting lug to complete the assembly of the remaining sections in sequence; Step 4, tack welding; After assembling the remaining sections in sequence, argon arc welding is used to spot weld and position each weld seam according to the process requirements. During the spot welding, the spot welding points are required to be evenly distributed, with each group of two spot welding points forming a group, and the group of welding points being symmetrically distributed at 180°. After spot welding and positioning at each weld location, the metal shell with lifting lugs is welded according to the process requirements. At this point, the welding and assembly of the metal shell with lifting lugs is complete.

2. The assembly method of the metal shell with lifting lugs as described in claim 1, characterized in that, When using an external surface lifting lug, according to the axial dimension of the lifting lug, the external surface slider (3) of the coaxiality control tooling is embedded in the slider groove on the column (4) so ​​that the external surface slider reaches a fully constrained state, ensuring that no movement or circumferential rotation occurs during the assembly process, and that the inner surface of the external surface slider groove on the external surface slider is in contact with the two side surfaces of the lifting lug.

3. The assembly method of the metal shell with lifting lugs as described in claim 1, characterized in that, When using an inner surface lifting lug, according to the axial dimension of the lifting lug, the inner surface slider (2) of the coaxiality control tooling is embedded in the slider groove on the column (4) so ​​that the inner surface slider reaches a fully constrained state, ensuring that no movement or circumferential rotation occurs during the assembly process, and that the surfaces on both sides of the inner surface slider are in contact with the inner surface of the lifting lug.

4. The assembly method of the metal shell with lifting lugs as described in claim 1, characterized in that, The welding fixture has multiple components, each used for assembling different sections. The welding fixture consists of a circular top cylinder, adjusting bolts, and adjusting nuts. In use, the circular top cylinder is fitted onto the outer circumference of the cylindrical component, and the circular top cylinder is made coaxial with the cylindrical component. The misalignment and gap between the cylindrical component and the lifting lug are adjusted by adjusting the tightness of the adjusting bolts.

5. The assembly method of the metal shell with lifting lugs as described in claim 1, characterized in that, After welding and assembly, the verticality between the column (4) and the base plate (1) is ≤0.2°.

6. The assembly method of the metal shell with lifting lugs as described in claim 1, characterized in that, The geometric center distance between adjacent slider slots is 50mm.

7. The assembly method of the metal shell with lifting lugs as described in claim 1, characterized in that, The outer surface slider is U-shaped, and the inner groove surface is the surface that mates with the outer surface lug; the two side surfaces of the inner surface slider are the surfaces that mate with the inner surface lug; the outer surface slider (3) is similar in structure to the inner surface slider (2), except that the top surface of the outer surface slider is machined with a slider groove, and the size of the slider groove surface matches the radial size of the lug, which is used to prevent it from rotating around the axis during assembly.

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