A closure and method of welding manufacture thereof

Abstract

A housing includes a shell, three sheet metal parts, a long rib, a short rib, and two sheet metal parts. The shell contains annularly distributed inner support blocks. An upper flange is located at the top of the shell, a lower flange at the bottom, and a middle flange is located between the upper and lower flanges on the inner wall of the shell. Two sheet metal parts are located between the lower flange and the side wall of the shell. The sides of the two sheet metal parts are connected to the side of the middle flange by an arc-shaped connecting plate. An upper horizontal circumferential seam exists at the connection between the connecting plate and the middle flange, and a lower horizontal circumferential seam exists at the connection between the connecting plate and the two sheet metal parts. Gaps exist at both the upper and lower ends of the side wall of the shell, filled with insulating cotton sealing plates. A layer of insulating cotton is also provided on the inner wall of the shell. This design reduces the depth of the arc crater, effectively avoiding arc crater crack defects, simplifies the manufacturing of structural components, and significantly improves the welding quality of the wall panels and the housing.

Description

Technical Field

[0001] This invention relates to an improvement in wall panel welding manufacturing technology, belonging to the field of welding, and particularly to a cover and its welding manufacturing method. Background Technology

[0002] The domestically produced 40MW gas turbine casing wall panel-shell, due to the long-term operating temperature increase from 800℃ to 860℃, uses GH4099 material, which can operate at 900℃ for extended periods. GH4099 is an age-hardening high-temperature alloy with poor weldability, making it a difficult alloy to weld. It is also sensitive to residual stress in the components, and the welds are prone to cracking after aging. The wall panel-shell is assembled from multiple components such as flanges, shells, wall panels, ribs, and plates using various welding methods such as electron beam welding and argon arc welding. The casing has a complex shape and welding structure, which easily leads to stress concentration and weld cracks, making the manufacturing of structural components particularly difficult.

[0003] Chinese patent application CN201910973000.2, filed on October 14, 2019, discloses a welding fixture for the outer shell of a gas turbine combustor. The welding fixture includes a base, multiple support blocks, and multiple wedges, with each wedge corresponding to one of the support blocks. The base includes two annular plates and a connecting plate. The two annular plates are arranged opposite each other, and the connecting plate is positioned between the two annular plates and fixedly connected to them. Multiple strip-shaped guide grooves a are provided on the surface of the annular plates without the connecting plate. Each strip-shaped guide groove a extends radially from the outer ring of the annular plate, and each strip-shaped guide groove a corresponds to one of the support blocks. Each support block includes an arc-shaped support portion and a strip-shaped guide portion. The first end of the strip-shaped guide portion is slidably disposed within the strip-shaped guide groove a corresponding to the support block to which the strip-shaped guide portion belongs. The wedge is engaged between the first end of the strip-shaped guide portion of the support block to which the wedge is located and the side of the strip-shaped guide groove a opposite to the first end of the strip-shaped guide portion. The second end of the strip guide is vertically fixed on the plane of the arc-shaped support included in the support block to which the strip guide belongs. The curved surface of the arc-shaped support is used to abut against the combustion chamber shell. However, the above technology has not solved the problem of the difficulty in manufacturing structural components.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this patent application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of high manufacturing difficulty of structural components in the prior art, and to provide a cover and its welding manufacturing method with low manufacturing difficulty.

[0006] To achieve the above objectives, the technical solution of the present invention is: a cover, the cover comprising a shell, three sheet metal parts, a long rib, a short rib, and two sheet metal parts;

[0007] The shell is provided with annularly distributed internal support blocks;

[0008] The top of the housing is provided with an upper flange, the bottom of the housing is provided with a lower flange, the inner wall of the housing is provided with a middle flange between the upper flange and the lower flange, and two sheet metal parts are provided between the lower flange and the side wall of the housing.

[0009] The sides of the two sheet metal parts are connected to the side of the middle flange by an arc-shaped connecting plate. There is an upper horizontal circumferential seam at the connection between the connecting plate and the middle flange, and a lower horizontal circumferential seam at the connection between the connecting plate and the two sheet metal parts.

[0010] There are gaps at both the upper and lower ends of the side of the shell, and the gaps are filled with thermal insulation cotton sealing plates. A layer of thermal insulation cotton is provided on the inner wall of the shell, and three sheet metal parts are provided between the thermal insulation cotton and the thermal insulation cotton sealing plates.

[0011] The three sheet metal parts include long ribs and short ribs, and the long ribs and short ribs are formed and configured.

[0012] The long rib is located inside the insulation cotton, and the sides of the short rib are connected to the insulation cotton, the insulation cotton sealing plate, and the inner wall of the shell, respectively.

[0013] A method for welding a housing, the method comprising the following steps:

[0014] Step 1: Manufacture the shell from a blank workpiece using the uniform deformation method;

[0015] Step 2: Use a progressive stamping method to manufacture two sheet metal parts from the two blank workpieces;

[0016] Step 3: Use CNC pressing to manufacture three sheet metal parts from the three blank workpieces;

[0017] Step 4: Weld the shell, second sheet metal part, and third sheet metal part into a cover using low-stress welding and mixed inert gas shielded welding.

[0018] In step one, the shell is manufactured from a blank workpiece using a uniform deformation method as follows:

[0019] The top and bottom of a conical blank workpiece are radially expanded, thereby deforming the thin end at the top and the thick end at the bottom of the blank workpiece into a trumpet-shaped semi-finished workpiece. The semi-finished workpiece is then processed and shaped to obtain a shell.

[0020] The processing and forming includes rough forming, fine forming, and an annealing process to eliminate internal stress in the area between the two after rough forming and fine forming are completed; the rough forming refers to the further outward expansion of the thick end of a blank workpiece, and the fine forming refers to the further outward expansion of the thin end of a blank workpiece.

[0021] The further expansion refers to:

[0022] a. Assemble the rough end and fine end of a blank workpiece in sequence with the expansion machine;

[0023] b. Place a blank workpiece into the mold and lock the top stop block with screws;

[0024] c. Then set the expansion parameters, operate the expansion machine, and use a π ruler to check the forming dimensions of the processed parts after the operation is completed;

[0025] d. Compare the dimensions of the machined part with the theoretical dimensions. If the dimensions do not reach the theoretical dimensions, continue to set the expansion parameters until the theoretical values ​​are reached.

[0026] In step two, the two blank workpieces are manufactured into two sheet metal parts using a progressive stamping method: first, the inner profile lines of the two blank workpieces are stamped, then the inner profile lines are pressed by a mold, and then the outer profile lines are stamped. After the stamping is completed, the two blank workpieces are taken out of the mold to obtain two sheet metal parts.

[0027] Before stamping the inner profile of the two blank workpieces, the two blank workpieces need to be heated and held under pressure. After the pressure holding is completed, the stamping of the inner profile can begin.

[0028] The pressure holding time shall not be less than 2 hours, and the heating temperature shall be controlled at 500~600℃;

[0029] After the inner profile is stamped, it undergoes intermediate annealing to relieve stress. The heating temperature is 1100±10℃, and the holding time is 15~30min. After air cooling and exiting the furnace, the inner profile is pressed by a mold.

[0030] In step three, the three blank workpieces are manufactured into three sheet metal parts using CNC pressing:

[0031] Before pressing using the CNC pressing method, machining allowances are left for the long and short ribs of the three blank workpieces. At the same time, the center pressing line is drawn on the three blank workpieces, and then the width of the lower die of the CNC bending machine is adjusted.

[0032] Calculate the required downward pressure of the upper die based on the width of the lower die of the CNC bending machine;

[0033] After the three blank workpieces are pressed, the front and back of the rounded corners are colored for inspection. After completion, the excess material is cut off by laser cutting.

[0034] In step four, the shell, the second sheet metal part, and the third sheet metal part are welded into a cover using a low-stress welding method and a mixed inert gas shielded welding method.

[0035] The low-stress welding method is as follows: First, the upper horizontal circumferential seam at the connection between the connecting plate and the middle flange is welded by electron beam welding, and then the lower horizontal circumferential seam at the connection between the connecting plate and the two sheet metal parts is welded.

[0036] After the shell is welded, medium-temperature annealing is used to eliminate the weld stress of multiple horizontal circumferential seams;

[0037] Electron beam welding uses non-penetrating process parameters for welding, and adds electron beam pulses during welding to reduce the required welding heat input for the same penetration depth.

[0038] The mixed inert gas shielded welding method is as follows:

[0039] The shell, three sheet metal parts, and insulation cotton sealing plate after low-stress welding are manually tungsten-grade argon arc welded into a cover.

[0040] Three sheet metal parts are welded to the side of the shell after low-stress welding, insulation cotton is filled to the inside of the shell after low-stress welding, and insulation cotton sealing plates are welded to the gaps in the shell.

[0041] A. Clean and dry before welding;

[0042] B. Intermittent welding is used for welding;

[0043] C. Single-pass welding is adopted, with a weld height of 3±1mm;

[0044] E. The casing is welded using manual tungsten inert gas welding;

[0045] F. Welding current 90~120A, welding speed 10-20cm / min, nozzle diameter greater than 18mm, gas flow rate 30~35L / min;

[0046] G. When welding the casing, weld the weld seams of the long ribs first, and then weld the weld seams of the short ribs.

[0047] H. Immediately after the casing is welded, use an R5 round-headed hammer to hammer the weld area.

[0048] I. Flat welding shall be used when welding the casing;

[0049] J. After the casing is welded, the weld seam is ground with a pneumatic grinding wheel until a smooth transition is achieved.

[0050] K. After the casing is welded, the surface of the casing is sandblasted.

[0051] The mixed inert gas shielded welding method also includes:

[0052] He / Ar mixed gas was used as the protective gas for shell welding;

[0053] The welds of the three sheet metal parts are welded using an intermittent method, with the arc pulled back and paused briefly when the arc is closed.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0055] 1. In this invention, a casing and its welding manufacturing method are described. A structural component is manufactured by low-stress welding of a sheet metal part, two sheet metal parts, and multiple flanges. The structural component and three sheet metal parts are then welded into a casing using a mixed inert gas shielded welding method. The welds of the three sheet metal parts are performed intermittently, significantly reducing the heat input during welding and thus reducing residual welding stress. During arc termination, the arc is pulled back and paused briefly to reduce the crater depth, effectively preventing crater crack defects. This reduces the manufacturing difficulty of the structural component and significantly improves the welding quality of the wall panel and the casing. Therefore, this design reduces manufacturing difficulty and improves welding quality.

[0056] 2. In the casing and its welding manufacturing method of this invention, a He / Ar mixed gas is used as the shielding gas for welding, which concentrates the energy of the electric arc column, reduces the viscosity of the molten pool, and improves its fluidity. This results in better appearance and ensures a bright, non-blackened weld surface. The corner areas of the ribs are not welded, effectively avoiding stress concentration at the corners, thus significantly reducing costs and ensuring better stability of the finished product's appearance. Therefore, this design has low cost and high stability.

[0057] 3. In the cover and its welding manufacturing method of the present invention, a blank workpiece is assembled into a structural component by electron beam welding of a sheet metal part, two sheet metal parts, and multiple flanges. Electron beam welding employs non-penetrating process parameters, and electron beam pulses are added during welding to reduce the required welding heat input for the same penetration depth. The use of non-penetrating process parameters ensures the welding heat input is minimized while maintaining the penetration depth. Furthermore, the addition of electron beam pulses further reduces the required welding heat input for the same penetration depth. To prevent weld cracking, medium-temperature annealing is used after welding to eliminate weld stress. Therefore, this design can prevent cracking and eliminate weld stress. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the structure of the present invention.

[0059] Figure 2 This is a schematic diagram of a blank workpiece structure in this invention.

[0060] Figure 3 This is a side view of a blank workpiece in this invention.

[0061] Figure 4 This is a schematic diagram of the semi-finished casing in this invention.

[0062] Figure 5 This is a schematic diagram of the structure of the two blank workpieces in this invention.

[0063] Figure 6 This is a schematic diagram of the structure of the three blank workpieces in this invention.

[0064] Figure 7 This is a top view of the installation of the present invention.

[0065] In the diagram: 1. Shell; 2. Inner support block; 3. Three sheet metal parts; 4. Long rib; 5. Short rib; 61. Upper flange; 62. Middle flange; 63. Lower flange; 64. Upper horizontal circumferential seam; 65. Two sheet metal parts; 66. Lower horizontal circumferential seam; 67. Connecting plate; 7. Insulation cotton; 8. Gap; 9. Insulation cotton sealing plate; 1. Raw workpiece A; 2. Raw workpiece B; 3. Raw workpiece C; 4. Semi-finished workpiece D. Detailed Implementation

[0066] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0067] See Figures 1 to 7 A housing, the housing comprising a shell 1, three sheet metal parts 3, a long rib 4, a short rib 5, and two sheet metal parts 65;

[0068] The housing 1 is provided with annularly distributed inner support blocks 2;

[0069] The top of the housing 1 is provided with an upper flange 61, the bottom of the housing 1 is provided with a lower flange 63, the inner wall of the housing 1 is provided with a middle flange 62 between the upper flange 61 and the lower flange 63, and two sheet metal parts 65 are provided between the lower flange 63 and the side wall of the housing 1.

[0070] The sides of the two sheet metal parts 65 are connected to the side of the middle flange 62 by an arc-shaped connecting plate 67. There is an upper horizontal circumferential seam 64 at the connection between the connecting plate 67 and the middle flange 62, and a lower horizontal circumferential seam 66 at the connection between the connecting plate 67 and the two sheet metal parts 65.

[0071] There are gaps 8 at both the upper and lower ends of the side of the shell 1. The gaps 8 are filled with insulation cotton sealing plates 9. A layer of insulation cotton 7 is provided on the inner wall of the shell 1. Three sheet metal parts 3 are provided between the insulation cotton 7 and the insulation cotton sealing plates 9.

[0072] The three sheet metal parts 3 include a long rib plate 4 and a short rib plate 5, which are arranged in an L-shape.

[0073] The long rib 4 is located inside the insulation cotton 7, and the side of the short rib 5 is connected to the insulation cotton 7, the insulation cotton sealing plate 9 and the inner wall of the shell 1 respectively.

[0074] A method for welding a housing, the method comprising the following steps:

[0075] Step 1: Use a blank workpiece A to manufacture shell 1 using the uniform deformation method;

[0076] Step 2: Use the progressive stamping method to manufacture two sheet metal parts 65 from the two blank workpieces B;

[0077] Step 3: Use CNC pressing to manufacture three sheet metal parts 3 from the three blank workpieces C;

[0078] Step 4: Weld shell 1, sheet metal part 65, and sheet metal part 3 into a cover using low-stress welding and mixed inert gas shielded welding.

[0079] In step one, the shell 1 is manufactured from a blank workpiece A using a uniform deformation method.

[0080] The top and bottom of a conical blank workpiece A are radially expanded, thereby deforming the thin end at the top and the thick end at the bottom of the blank workpiece A into a trumpet-shaped semi-finished workpiece D. The semi-finished workpiece D is then processed and shaped to obtain the shell 1.

[0081] The processing and forming includes rough forming, fine forming, and an annealing process to eliminate internal stress in the area between the two after rough forming and fine forming are completed; the rough forming refers to the further outward expansion of the thick end of a blank workpiece A, and the fine forming refers to the further outward expansion of the thin end of a blank workpiece A.

[0082] The further expansion refers to:

[0083] a. Assemble the rough end and fine end of a blank workpiece A with the expansion machine in sequence;

[0084] b. Place a blank workpiece A into the mold and lock the top stop block with screws;

[0085] c. Then set the expansion parameters, operate the expansion machine, and use a π ruler to check the forming dimensions of the processed parts after the operation is completed;

[0086] d. Compare the dimensions of the machined part with the theoretical dimensions. If the dimensions do not reach the theoretical dimensions, continue to set the expansion parameters until the theoretical values ​​are reached.

[0087] In step two, the two blank workpieces B are manufactured into two sheet metal parts 65 by progressive stamping: first, the inner profile lines of the two blank workpieces B are stamped, then the inner profile lines are pressed by the mold, and then the outer profile lines are stamped. After the stamping is completed, the two blank workpieces B are taken out of the mold to obtain two sheet metal parts 65.

[0088] Before stamping the inner profile of the two blank workpieces B, it is necessary to heat and hold the pressure on the two blank workpieces B. After the pressure holding is completed, the stamping of the inner profile can begin.

[0089] The pressure holding time shall not be less than 2 hours, and the heating temperature shall be controlled at 500~600℃;

[0090] After the inner profile is stamped, it undergoes intermediate annealing to relieve stress. The heating temperature is 1100±10℃, and the holding time is 15~30min. After air cooling and exiting the furnace, the inner profile is pressed by a mold.

[0091] In step three, the three blank workpieces C are manufactured into three sheet metal parts 3 using CNC pressing:

[0092] Before pressing using the CNC pressing method, machining allowances are left for the long rib plate 4 and short rib plate 5 of the three blank workpieces C. At the same time, the center pressing line is drawn on the three blank workpieces C, and then the width of the lower die of the CNC bending machine is adjusted.

[0093] Calculate the required downward pressure of the upper die based on the width of the lower die of the CNC bending machine;

[0094] After the three blank workpieces C are pressed, the front and back of the rounded corners are colored for inspection. After completion, the excess material head is cut off by laser 3D cutting method.

[0095] In step four, the shell 1, the second sheet metal part 65, and the third sheet metal part 3 are welded into a cover using a low-stress welding method and a mixed inert gas shielded welding method.

[0096] The low-stress welding method is as follows: First, the upper horizontal circumferential seam 64 at the connection between the connecting plate 67 and the middle flange 62 is welded by electron beam welding, and then the lower horizontal circumferential seam 66 at the connection between the connecting plate 67 and the two sheet metal parts 65 is welded.

[0097] After the shell 1 is welded, medium-temperature annealing is used to eliminate the weld stress of multiple horizontal circumferential seams;

[0098] Electron beam welding uses non-penetrating process parameters for welding, and adds electron beam pulses during welding to reduce the required welding heat input for the same penetration depth.

[0099] The mixed inert gas shielded welding method is as follows:

[0100] The shell 1, three sheet metal parts 3, and thermal insulation cotton sealing plate 9, after low-stress welding, are manually tungsten-grade argon arc welded into a cover.

[0101] Three sheet metal parts 3 are welded to the side of the shell 1 after low-stress welding, thermal insulation cotton 7 is filled inside the shell 1 after low-stress welding, and thermal insulation cotton sealing plate 9 is welded to the gap of the shell 1.

[0102] A. Clean and dry before welding;

[0103] B. Intermittent welding is used for welding;

[0104] C. Single-pass welding is adopted, with a weld height of 3±1mm;

[0105] E. The casing is welded using manual tungsten inert gas welding;

[0106] F. Welding current 90~120A, welding speed 10-20cm / min, nozzle diameter greater than 18mm, gas flow rate 30~35L / min;

[0107] G. When welding the cover, weld the weld of the long rib plate 4 first, and then weld the weld of the short rib plate 5.

[0108] H. Immediately after the casing is welded, use an R5 round-headed hammer to hammer the weld area.

[0109] I. Flat welding shall be used when welding the casing;

[0110] J. After the casing is welded, the weld seam is ground with a pneumatic grinding wheel until a smooth transition is achieved.

[0111] K. After the casing is welded, the surface of the casing is sandblasted.

[0112] The mixed inert gas shielded welding method also includes:

[0113] He / Ar mixed gas was used as the protective gas for welding shell 1;

[0114] The weld seam of sheet metal part 3 is welded using the intermittent method, and the arc is pulled back and paused briefly when the arc is closed.

[0115] Example 1:

[0116] A housing includes a shell 1, three sheet metal parts 3, a long rib 4, a short rib 5, and two sheet metal parts 65; the shell 1 has annularly distributed inner support blocks 2; the top of the shell 1 has an upper flange 61, the bottom of the shell 1 has a lower flange 63, a middle flange 62 is provided on the inner wall of the shell 1 between the upper flange 61 and the lower flange 63, and two sheet metal parts 65 are provided between the lower flange 63 and the side wall of the shell 1; the sides of the two sheet metal parts 65 are connected to the side of the middle flange 62 by an arc-shaped connecting plate 67, and the connecting plate 67 is connected to the middle flange 62. There is an upper horizontal circumferential seam 64 at the connection point, and a lower horizontal circumferential seam 66 at the connection point between the connecting plate 67 and the two sheet metal parts 65; there are gaps 8 at both the upper and lower ends of the side wall of the shell 1, and the gaps 8 are filled with thermal insulation cotton sealing plates 9. A layer of thermal insulation cotton 7 is provided on the inner wall of the shell 1, and three sheet metal parts 3 are provided between the thermal insulation cotton 7 and the thermal insulation cotton sealing plates 9; the three sheet metal parts 3 include a long rib plate 4 and a short rib plate 5, which are arranged in an L-shape; the long rib plate 4 is located inside the thermal insulation cotton 7, and the side of the short rib plate 5 is connected to the thermal insulation cotton 7, the thermal insulation cotton sealing plates 9 and the inner wall of the shell 1 respectively.

[0117] A method for welding a housing, the method comprising the following steps:

[0118] Step 1: Use a blank workpiece A to manufacture shell 1 using the uniform deformation method;

[0119] Step 2: Use the progressive stamping method to manufacture two sheet metal parts 65 from the two blank workpieces B;

[0120] Step 3: Use CNC pressing to manufacture three sheet metal parts 3 from the three blank workpieces C;

[0121] Step 4: Weld shell 1, sheet metal part 65, and sheet metal part 3 into a cover using low-stress welding and mixed inert gas shielded welding.

[0122] Example 2:

[0123] Example 2 is basically the same as Example 1, except that:

[0124] like Figures 2 to 4As shown, a method for manufacturing a casing by welding is described. In step one, the casing is manufactured by uniformly deforming a blank workpiece. The process involves pre-forming a 3mm thick steel plate (GH4099HB5332) into a conical blank workpiece A. This blank workpiece A is then expanded radially outwards by simultaneously expanding each equally divided inner support block 2, thereby deforming it into a trumpet-shaped semi-finished workpiece D. The semi-finished workpiece D is then processed into two stages: rough forming and fine forming. Rough forming involves a larger amount of material, while fine forming involves a smaller amount. An annealing process is used between rough forming and fine forming to eliminate internal stress. The total expansion amount is set to 6mm. The value of 'm' mainly considers the stroke of the expanding equipment and the elongation of the material. The larger the stroke of the expanding equipment and the greater the elongation of the material, the larger the upper limit of the total expanding amount can be. In principle, the expanding amount should not exceed half of the elongation, because the larger this value, the more severe the cold work hardening of the material. The rough expanding amount is set to 4mm. After rough expanding, intermediate annealing is performed at 1100℃ for 30 minutes, followed by air cooling. The fine expanding amount is set to 2mm. After expanding, the average diameter tolerance of the cylinder can reach 0~+0.5mm. The excess at both ends is then removed by machining. The larger the ratio of rough expanding to fine expanding, the smaller the residual internal stress after expanding.

[0125] The rough forming refers to the further outward expansion of the rough end of a blank workpiece, and the fine forming refers to the further outward expansion of the fine end of a blank workpiece; the further outward expansion refers to:

[0126] a. Assemble the rough end and fine end of a blank workpiece in sequence with the expansion machine;

[0127] b. Place a blank workpiece into the mold and lock the top stop block with screws;

[0128] c. Then set the expansion parameters, operate the expansion machine, and use a π ruler to check the forming dimensions of the processed parts after the operation is completed;

[0129] d. Compare the dimensions of the machined part with the theoretical dimensions. If the dimensions do not reach the theoretical dimensions, continue to set the expansion parameters until the theoretical values ​​are reached.

[0130] Example 3:

[0131] Example 3 is basically the same as Example 1, except that:

[0132] like Figure 5As shown, a method for manufacturing a casing by welding, in step two, two blank workpieces B are manufactured into two sheet metal parts 65 using a progressive stamping method: First, the inner profile of the two blank workpieces B is stamped, then the inner profile is pressed by a mold, and then the outer profile is stamped. After stamping, the two blank workpieces B are removed from the mold. The blanks are 3mm thick, GH4099 / HB5332 annular steel plates. A 10mm pre-welding machining allowance is left for the inner and outer radii according to the generatrix, and no other allowance is left. Laser cutting is used for blanking. After blanking, the inner profile is first stamped using a die, using hot stamping. The specific method is as follows: First, the annular two blank workpieces B are placed in the groove of the first die, and the bolts are tightened with a torque of 350 N•m to press the pressure ring against the area within 100mm of the outer circle of the annular steel plate; then... Then, the two men stood symmetrically in a circle, each holding a flame gun. After ignition, they used the outer flame to heat the two annular blank workpieces B back and forth, sweeping the flame gun in a fan shape to heat the plate surface within the length range of the inner profile to be stamped to 500±50℃ relatively evenly. The plate temperature was detected by a contact thermocouple. After completion, the workpiece was held under pressure for 2 hours with the first die closed. After completion, the workpiece was removed from the die and transferred to the heat treatment workshop for intermediate annealing to relieve stress. The heating temperature was 1100±10℃, and the holding time was 15~30 minutes. After air cooling, the workpiece was removed from the furnace. After the workpiece cooled to room temperature, it was placed in the second die and the inner profile was pressed with a pressure ring. The above heating operation was repeated. The second die was closed and held under pressure for 2 hours. After completion, the workpiece was removed from the die, resulting in two sheet metal parts 65.

[0133] Example 4:

[0134] Example 4 is basically the same as Example 1, except that:

[0135] like Figure 6 As shown, a method for manufacturing a casing by welding includes step three, in which three blank workpieces C are manufactured into three sheet metal parts 3 using CNC pressing. Before CNC pressing, machining allowances are left on the long rib plate 4 and short rib plate 5 of the three blank workpieces C. At the same time, a center pressing line is drawn on the three blank workpieces C. The long rib plate 4 and short rib plate 5 are L-shaped angle steel structures, made of GH4099 / HB5332 steel with a thickness of 3mm. The three blank workpieces C are made of 3mm thick GH4099 steel plate, with machining allowances left on the width and allowances for pressing straight edges. Before pressing, a scribing needle is used. Draw the center pressing line, adjust the width of the lower die of the CNC bending machine to 20mm, calculate the required pressing amount of the upper die based on the width of the lower die of the CNC bending machine, and correct the pressing amount of the upper die through trial pressing to ensure the forming round corners and angles after pressing. Then, all long ribs 4 and short ribs 5 are pressed into shape using a curing process to ensure that all long ribs 4 and short ribs 5 have consistent forming dimensions such as round corners and angles. After pressing, the front and back of the round corners are 100% colored for inspection. After completion, the excess material is cut off by laser 3D cutting method.

[0136] Example 5:

[0137] Example 5 is basically the same as Example 1, except that:

[0138] like Figure 7 As shown, a method for manufacturing a casing by welding, wherein in step four, the casing 1, the second sheet metal part 65, and the third sheet metal part 3 are welded into a casing using a low-stress welding method and a mixed inert gas shielded welding method:

[0139] The low-stress welding method is as follows: First, the upper horizontal circumferential seam 64 at the connection between the connecting plate 67 and the middle flange 62 is welded by electron beam welding, and then the lower horizontal circumferential seam 66 at the connection between the connecting plate 67 and the two sheet metal parts 65 is welded.

[0140] After the shell 1 is welded, medium-temperature annealing is used to eliminate the weld stress of multiple horizontal circumferential seams;

[0141] Electron beam welding uses non-penetrating process parameters to minimize welding heat input while ensuring penetration depth. Electron beam pulses are added during welding to reduce the required welding heat input for the same penetration depth.

[0142] The mixed inert gas shielded welding method is as follows:

[0143] The shell 1, three sheet metal parts 3, and thermal insulation cotton sealing plate 9, after low-stress welding, are manually tungsten-grade argon arc welded into a cover.

[0144] Three sheet metal parts 3 are welded to the side of the shell 1 after low-stress welding, thermal insulation cotton 7 is filled inside the shell 1 after low-stress welding, thermal insulation cotton sealing plate 9 is welded to the gap 8 of the shell 1, and the shell 1 is aged at 900℃ after welding. After aging, the shell 1 is inspected and then machined.

[0145] A. Clean and dry before welding;

[0146] B. Intermittent welding is used for welding;

[0147] C. Single-pass welding is adopted, with a weld height of 3±1mm;

[0148] E. The casing is welded using manual tungsten inert gas welding with DC positive polarity and a mixture of 75% Ar and 25% He with a purity of 99.99%.

[0149] F. Welding current 90~120A, welding speed 10-20cm / min, nozzle diameter greater than 18mm, gas flow rate 30~35L / min;

[0150] G. When welding the cover, weld the weld of the long rib plate 4 first, and then weld the weld of the short rib plate 5.

[0151] H. Immediately after the casing is welded, use an R5 round-headed hammer to hammer the weld area.

[0152] I. Flat welding shall be used when welding the casing;

[0153] J. After the casing is welded, the weld seam is ground with a pneumatic grinding wheel until a smooth transition is achieved.

[0154] K. After the casing is welded, the surface of the casing shall be sandblasted. Sandblasting requires the use of 110~220 mesh Al2O3 abrasive. After sandblasting, the surface cleanliness shall reach Sa3 level, and the surface roughness shall be 15~30um. Sandblasting can put the weld surface in a compressive stress state, reducing the probability of weld cracking.

[0155] The mixed inert gas shielded welding method also includes:

[0156] Using He / Ar mixed gas as the shielding gas for welding shell 1, the energy of the electric arc column is more concentrated, the viscosity of the molten pool is reduced and the fluidity is improved, resulting in better appearance and ensuring that the weld surface is bright and does not turn black.

[0157] The welds of sheet metal part 3 are welded using an intermittent method. When the arc is terminated, it is pulled back and paused briefly, which greatly reduces the heat input of the weld and thus reduces the residual stress of the weld. Pulling back the arc and pausing briefly when the arc is terminated reduces the depth of the arc crater and effectively avoids the occurrence of arc crater crack defects. No welding is performed within 20mm of the corner of the rib plate, which effectively avoids stress concentration at the corner.

[0158] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A housing, characterized in that: The cover includes a shell (1), three sheet metal parts (3), a long rib (4), a short rib (5), and two sheet metal parts (65). The shell (1) is provided with annularly distributed inner support blocks (2). The top of the housing (1) is provided with an upper flange (61), the bottom of the housing (1) is provided with a lower flange (63), the inner wall of the housing (1) is provided with a middle flange (62) between the upper flange (61) and the lower flange (63), and two sheet metal parts (65) are provided between the lower flange (63) and the side wall of the housing (1). The sides of the two sheet metal parts (65) are connected to the side of the middle flange (62) by an arc-shaped connecting plate (67). There is an upper horizontal circumferential seam (64) at the connection between the connecting plate (67) and the middle flange (62), and a lower horizontal circumferential seam (66) at the connection between the connecting plate (67) and the two sheet metal parts (65). There are gaps (8) at both the upper and lower ends of the side of the shell (1). The gaps (8) are filled with insulation cotton sealing plates (9). A layer of insulation cotton (7) is provided on the inner wall of the shell (1). Three sheet metal parts (3) are provided between the insulation cotton (7) and the insulation cotton sealing plates (9). The three sheet metal parts (3) include a long rib (4) and a short rib (5), which are arranged in an L-shape. The long rib (4) is located inside the insulation cotton (7), and the side of the short rib (5) is connected to the insulation cotton (7), the insulation cotton sealing plate (9) and the inner wall of the shell (1) respectively.

2. The welding manufacturing method for a casing according to claim 1, characterized in that: The method for manufacturing the casing welding includes the following steps: Step 1: The shell (1) is manufactured from a blank workpiece (A) using a uniform deformation method, specifically as follows: The top and bottom of a conical blank workpiece (A) are radially expanded, thereby expanding and deforming the thin end at the top and the thick end at the bottom of the blank workpiece (A) into a trumpet-shaped semi-finished workpiece (D). The semi-finished workpiece (D) is then processed and shaped to obtain a shell (1). Step 2: Use the progressive stamping method to manufacture two sheet metal parts (65) from the two blank workpieces (B); Step 3: Use CNC pressing to manufacture three sheet metal parts (3) from the three blank workpieces (C); Step 4: Weld the shell (1), the second sheet metal part (65), and the third sheet metal part (3) into a cover using low-stress welding and mixed inert gas shielded welding.

3. The method for manufacturing a casing by welding according to claim 2, characterized in that: The processing and forming includes rough forming, fine forming, and an annealing process to eliminate internal stress in the area between the two after rough forming and fine forming are completed; the rough forming refers to the further expansion of the thick end of a blank workpiece (A), and the fine forming refers to the further expansion of the thin end of a blank workpiece (A). The further expansion refers to: a. Assemble the rough end and fine end of a blank workpiece (A) with the expansion machine in sequence; b. Place a blank workpiece (A) into the mold and lock the top stop block with screws; c. Then set the expansion parameters, operate the expansion machine, and use a π ruler to check the forming dimensions of the processed parts after the operation is completed; d. Compare the dimensions of the machined part with the theoretical dimensions. If the dimensions do not reach the theoretical dimensions, continue to set the expansion parameters until the theoretical values ​​are reached.

4. The method for manufacturing a casing by welding according to claim 2, characterized in that: In step two, the two blank workpieces (B) are manufactured into two sheet metal parts (65) by progressive stamping: first, the inner profile of the two blank workpieces (B) is stamped, then the inner profile is pressed by the mold, and then the outer profile is stamped. After the stamping is completed, the two blank workpieces (B) are taken out of the mold to obtain two sheet metal parts (65).

5. The method for manufacturing a casing by welding according to claim 4, characterized in that: Before stamping the inner profile of the two blank workpieces (B), the two blank workpieces (B) need to be heated and held under pressure. After the pressure holding is completed, the stamping of the inner profile can begin. The pressure holding time shall not be less than 2 hours, and the heating temperature shall be controlled at 500~600℃; After the inner profile is stamped, it undergoes intermediate annealing to relieve stress. The heating temperature is 1100±10℃, and the holding time is 15~30min. After air cooling and exiting the furnace, the inner profile is pressed by a mold.

6. The method for manufacturing a casing by welding according to claim 2, characterized in that: In step three, the three blank workpieces (C) are manufactured into three sheet metal parts (3) using CNC pressing: Before pressing by the CNC pressing method, the long rib (4) and short rib (5) of the three blank workpiece (C) are left with machining allowance. At the same time, the center pressing line is drawn on the three blank workpiece (C), and then the width of the lower die of the CNC bending machine is adjusted. Calculate the required downward pressure of the upper die based on the width of the lower die of the CNC bending machine; After pressing the three blank workpieces (C), the front and back of the rounded corners are colored for inspection. After completion, the excess material is cut off by laser 3D cutting method.

7. A method for manufacturing a casing by welding according to claim 2, characterized in that: In step four, the shell (1), the second sheet metal part (65), and the third sheet metal part (3) are welded into a cover using a low-stress welding method and a mixed inert gas shielded welding method. The low-stress welding method is as follows: First, the upper horizontal circumferential seam (64) at the connection between the connecting plate (67) and the middle flange (62) is welded by electron beam welding, and then the lower horizontal circumferential seam (66) at the connection between the connecting plate (67) and the two sheet metal parts (65) is welded. After the shell (1) is welded, medium-temperature annealing is used to eliminate the weld stress of multiple horizontal circumferential seams; Electron beam welding uses non-penetrating process parameters for welding, and adds electron beam pulses during welding to reduce the required welding heat input for the same penetration depth.

8. The method for manufacturing a casing by welding according to claim 7, characterized in that: The mixed inert gas shielded welding method is as follows: The shell (1), three sheet metal parts (3), and insulation cotton sealing plate (9) after low stress welding are manually tungsten-grade argon arc welded into a cover. Three sheet metal parts (3) are welded to the side of the shell (1) after low stress welding, insulation cotton (7) is filled to the inside of the shell (1) after low stress welding, and insulation cotton sealing plate (9) is welded to the gap (8) of the shell (1).

9. A method for manufacturing a casing by welding according to claim 8, characterized in that: The mixed inert gas shielded welding method also includes: He / Ar mixed gas was used as the protective gas for welding the shell (1); The welds of the three sheet metal parts (3) are welded using the intermittent method, and the arc is pulled back and paused briefly when the arc is closed.

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