Tailor-welding, spinning and variable-wall-thickness forming method for large-sized extension section of liquid propellant rocket engine

Abstract

A tailor-welding, spinning and variable-wall-thickness forming method for a large-sized extension section of a liquid propellant rocket engine, which belongs to the technical field of metal forming. The method comprises: performing laser numerical control machining on a GH3044 superalloy to obtain two chord-tangent circles; performing electron beam welding to obtain a complete circle; performing a vacuum solid solution treatment; performing pre-forming to obtain a shallow dish shape; performing a vacuum solid solution treatment; assembling a variable-wall-thickness flat blank and a spinning mandrel of a first spinning die, and then performing spinning on a spinning machine to form a curved generatrix variable-wall-thickness blank part; performing a vacuum solid solution treatment; and assembling the curved generatrix variable-wall-thickness blank part and a spinning mandrel of a second spinning die, and then performing spinning on the spinning machine to form a curved generatrix variable-wall-thickness part. The present invention is mainly used for the manufacturing of an ultra-large-sized GH3044 extension section of the liquid propellant rocket engine, which has a diameter of 1200 mm and a length of 1500 mm, and the product precision reaches a wall thickness tolerance of + / -0.05 mm for each point and a surface profile of ≤3 mm.

Description

Tailor-welded spinning variable wall thickness forming method for large-size extension section of liquid rocket engine

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 202311431664.9, filed with the Patent Office of China on October 31, 2023, entitled “Method for welding and spinning variable wall thickness forming of large-size extension section of liquid rocket engine”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The invention belongs to the technical field of metal forming, and in particular relates to a tailor-made welding and spinning variable-wall-thickness forming method for a large-size extension section of a liquid rocket engine. Background Art

[0004] A liquid rocket engine with high thrust is made of GH3044, a high-temperature alloy rarely used for spinning. The thrust chamber extension section is an oversized GH3044 thin-walled precision part with a small end wall thickness of 1.5mm, which is much larger than the large end wall thickness of 0.65mm. Much larger than the small end diameter Axial distance 1485mm.

[0005] At present, the extension section of this type of engine is the largest variable wall thickness curved busbar extension section. The spinning performance of GH3044 is not well understood, and the spinning is very difficult.

[0006] Since the large-size GH3044 with a thickness of δ3.5mm on the market needs to be specially customized, the material ordering cycle is long and the cost is high.

[0007] Summary of the Invention

[0008] The technical problem solved by the present application is: to overcome the shortcomings of the existing technology, to provide a method for forming a large-size extension section of a liquid rocket engine by tailor welding and spinning with variable wall thickness, to obtain a flat blank of the required spinning size by electron beam welding, to ensure that the strength of the weld and the flatness after welding meet the requirements of the spinning process, to use the high-temperature alloy GH3044, and to utilize a targeted forming method (preforming + primary cold spinning + secondary cold spinning) to spin into an ultra-large-size variable-wall-thickness curved busbar extension section.

[0009] The technical solutions provided in this application are as follows:

[0010] A tailor-welded spinning variable-wall-thickness forming method for a large-size extension section of a liquid rocket engine comprises:

[0011] S1: Cut the plate into two tangential circles, electron beam weld them into a full circle to obtain a flat blank, and vacuum solution treat;

[0012] S2: The flat blank is drawn into a shallow dished blank through a preforming die and then subjected to vacuum solution treatment;

[0013] S3: The shallow dish-shaped spinning blank is subjected to the first spinning to obtain a first-spin blank, and vacuum solution treatment is performed;

[0014] S4: The first spinning blank is spun for the second time to form a variable wall thickness super-large size curved busbar variable wall thickness extension section, the large end diameter of the extension section is not less than The axis length shall not be less than 1485mm.

[0015] In step 1, due to the large size of the extended section of the high-temperature alloy GH3044, the width of the plate does not meet the process requirements. The GH3044 plate is laser cut into two tangential circles with a diameter of The flat blank is obtained by electron beam welding into a full circle, ensuring that the flatness of the flat blank is no more than 3mm.

[0016] In step 1, electron beam welding is used to join the two tangentially cut circles together to prevent distortion and deformation after welding that could affect the spinning process. Full penetration is required during this process, and after welding, the weld quality is X-ray inspected according to the Level I standard of GJB1718A-2005. Welding fixtures are used to prevent significant deformation after welding, and the flatness after welding must be no greater than 3 mm.

[0017] In step S1, the conditions for electron beam welding are as follows: before welding, two arc-starting plates with a size of not less than 30×60 mm are positioned at both ends of the weld, the arc-starting plate profile should fit the outer circle of the circular plate, the assembly gap should not be greater than 0.2 mm, and the misalignment should not be greater than 0.15 mm. Before welding, the surface of the joint is cleaned by pickling or mechanical cleaning. Before welding, a test plate of equal thickness is used for trial welding. After confirming that the weld is fully penetrated, formal welding is carried out. After welding, non-destructive testing is required to ensure that there are no defects inside the weld.

[0018] In step S1, the two tangential circles are fixed in a welding tool for electron beam welding. The welding tool includes a support assembly, a first fixing plate, a second fixing plate and a third fixing plate. The surface of the support assembly is used to place the two tangential circles. The first fixing plate, the second fixing plate and the third fixing plate are all located above the two tangential circles, and both ends are detachably connected to the support assembly. The first fixing plate and the second fixing plate are pressed above the larger tangential circle, and the third fixing plate is pressed above the smaller tangential circle. The second fixing plate and the third fixing plate are respectively located on both sides of the splicing position of the two tangential circles.

[0019] In step 1, in order to eliminate welding stress, solution treatment is performed. The heat treatment system is as follows: heating to 950±10℃ within 90 minutes, keeping warm for 26 to 30 minutes, then heating to 1150±10℃, and keeping warm for 14 to 16 minutes.

[0020] In step 2, the drawing debugging material is 1Cr18Ni9Ti, which has two functions: one is to adjust the blanking force and drawing force so that the shallow dished parts drawn are wrinkle-free or slightly wrinkled, ensuring the quality of the subsequent drawn formal products; the other is that the drawing debugging material is also the debugging material for subsequent spinning, which adjusts the spinning parameters for the formal product spinning.

[0021] In step S2, the preforming mold includes a pressure ring, a positioning column, a female mold, a push rod and a male mold. The positioning column is connected to the middle of the parting surface of the male mold and cooperates with the center hole of the flat blank. The pressure ring is sleeved on the outside of the male mold and is slidably connected to the male mold along the moving direction of the female mold.

[0022] In step S2, after the flat blank is deep-drawn into a shallow dish shape by a pre-forming die, the shallow dish-shaped blank is rotated 90° around its own axis, and a stretching forming process is performed again by the pre-forming die to correct the shallow dish-shaped blank and eliminate the wrinkling phenomenon at the large end to obtain a shallow dish-shaped blank, and then vacuum solution treatment is performed.

[0023] In step S3, the first spinning adopts a spinning mold, and the spinning mold includes a first tail top, a first positioning column, a first spinning tire body, a first adapter plate and a first push rod. The large end of the first spinning tire body is fixed on the first adapter plate, and a through hole is provided at the axial position of the first spinning tire body. The first push rod is located in the through hole and can move along the axial direction of the first spinning tire body. One end of the first push rod covers the small end of the first spinning tire body, the first positioning column is coaxially fixedly connected to the end of the first push rod, and a positioning hole is provided at the axial position of the first tail top that cooperates with the first positioning column so that the first positioning column is coaxially connected to the first tail top. The shallow dish-shaped blank is located between the small end of the first spinning tire body and the first tail top. The first positioning column passes through the central positioning hole of the shallow dish-shaped blank. After spinning, the shallow dish-shaped blank is loosened from the first spinning tire body by using the first push rod.

[0024] In step S3, an initial allowance is determined based on the material of the shallow dished blank to obtain an initial spinning gap for each part. The initial spinning gap = the theoretical wall thickness at each location of the shallow dished blank minus the allowance. Based on the initial spinning gap, a 1Cr18Ni9Ti test material consistent with the shape of the shallow dished blank is first used for trial spinning. The spinning gap is continuously adjusted. When the wall thickness of the part is large, the spinning gap is reduced, and when the wall thickness is small, the spinning gap is increased. Rather than using a single gap value for all parts, the wall thickness of the test material meets the requirements after the trial spinning, thereby obtaining an adjusted spinning gap. The shallow dished blank is then spun using the adjusted spinning gap to obtain a single dished blank. The 1Cr18Ni9Ti test material is consistent with the shape of the shallow dished blank, and the specifications are within the allowable error range.

[0025] In step S3, before the first spinning, the shallow dish-shaped blank is measured evenly on at least four busbars, and the wall thickness is measured at intervals of 50-60 mm. A total of 13 wall thickness values ​​are measured for one busbar, and a total of 52 wall thickness values ​​are measured for the four busbars. During the first spinning process, the spinning gap is adjusted according to the measured wall thickness. When the wall thickness value of the part is large, the spinning gap is smaller, and when the wall thickness value is small, the spinning gap is larger. Instead of using one gap value for all parts, the wall thickness of the subsequent variable wall thickness flat blank after spinning is closer to the theoretical value.

[0026] The clearance adjustment value of the spinning gap is within ±0.06mm.

[0027] In the step S3, during the first spinning process, the spinning speed is 10 mm / min, the spindle speed is 54-25 rpm, and the radius R of the spinning wheel during spinning is 8-10 mm.

[0028] In step 3, before the first spinning, after the shallow dish-shaped blank is installed, the shallow dish-shaped blank is aligned, and the runout of the small end is ≤1mm.

[0029] In step S4, the initial yield is determined according to the material of the first spinning blank, and the initial spinning gap of each part is obtained. The initial spinning gap = the theoretical wall thickness of each part of the second spinning blank - the yield;

[0030] According to the initial spinning gap, first use the 1Cr18Ni9Ti debugging material with the same shape as the first spinning blank for trial spinning, and continuously adjust the spinning gap until the wall thickness of the debugging material after the trial spinning meets the requirements, and the adjusted spinning gap is obtained; the 1Cr18Ni9Ti debugging material has the same shape as the first spinning blank, and the specification parameters are within the allowable error range;

[0031] Then, the blank is spun using the adjusted spinning gap. During the second spinning process, the spinning speed is 10 mm / min and the spindle speed is 54-25 rpm. The radius of the spinning wheel corner during spinning is R8-R10 mm. A variable wall thickness extension section of a super-large curved busbar with variable wall thickness is obtained.

[0032] Before the second spinning, measure the actual wall thickness of a spinning blank at different positions on at least four busbars, and adjust the spinning gap according to the measured wall thickness. When the wall thickness value of the part is large, the spinning gap is smaller, and when the wall thickness value is small, the spinning gap is larger. Instead of using one gap value for all parts, the wall thickness of the subsequent variable wall thickness flat blank after spinning is closer to the theoretical value; the gap adjustment value is within ±0.06mm.

[0033] In step 3, the initial spinning gap is determined by subtracting a setback of 0.45 mm from the theoretical wall thickness value at each point of the blank, performing trial spinning with a 1Cr18Ni9Ti test material according to the initial spinning gap, measuring the wall thickness at each point of the test piece, and comparing it with the theoretical value. If the wall thickness is greater than the theoretical value, the spinning gap is reduced, and if the wall thickness is less than the theoretical value, the spinning gap is increased until the wall thickness of the part meets the requirement after the trial spinning, thereby obtaining an adjusted spinning gap; and then spinning a GH3044 part using the adjusted spinning gap; wherein the 1Cr18Ni9Ti test material and the GH3044 part have the same shape and parameters.

[0034] In summary, this application has at least the following beneficial technical effects:

[0035] (1) In the present invention, a method of electron beam welding a flat plate blank is adopted to obtain a flat plate blank of sufficient area size, without the need to specially purchase and customize a large-sized plate blank.

[0036] (2) The present invention provides a welding tool design for electron beam welding of flat blanks and the requirements for the die size after electron beam welding, which ensures that the requirements of the subsequent spinning forming process are met and the quality of the one-time forming can be guaranteed;

[0037] (3) The spinning method includes pre-drawing, one-time cold spinning of variable wall thickness curved busbar blank and two-time cold spinning of variable wall thickness curved busbar parts. By controlling the parameters of each process such as blank wall thickness, spinning gap, feed speed, etc., the spinning process is stable and reproducible, and the product accuracy reaches the wall thickness tolerance of each point ±0.06mm and the surface profile ≤3mm;

[0038] (4) In the present invention, the forming of the extension section completely depends on the spinning forming parameters, and there is no need for subsequent turning of the wall thickness. The turning is only designed for the processing allowance at the large and small ends, which solves the impact of turning on the wall thickness and reduces the processing risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic structural diagram of a preforming die;

[0040] Figure 2 is a schematic diagram of a spin mold structure;

[0041] Figure 3 is a schematic diagram of the structure of a two-rotation mold;

[0042] Figure 4 shows two chord-tangent circles;

[0043] Figure 5: Shallow dish blank part drawing;

[0044] Figure 6 - Drawing of a blank part;

[0045] Figure 7: Two-turn blank part drawing;

[0046] Figure 8 Electron beam welding tooling.

[0047] Explanation of the accompanying numbers: 1. Pressure ring; 2. Positioning column; 3. Female mold; 4. Push rod; 5. Male mold; 6. First tail top; 7. First positioning column; 8. First spun tire body; 9. First adapter plate; 10. First push rod; 11. Second tail top; 12. Second positioning column; 13. Second spun tire body; 14. Second adapter plate; 15. Second push rod; 16. Support assembly; 17. First fixed plate; 18. Second fixed plate; 19. Third fixed plate. DETAILED DESCRIPTION

[0048] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0049] The word "exemplary" is used exclusively herein to mean "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0050] The present invention provides a method for forming a large-size extension section of a liquid rocket engine by tailor welding and spinning with variable wall thickness, comprising the following steps:

[0051] Step 1: Due to the oversized extension of the high-temperature alloy GH3044, the sheet width does not meet the process requirements. The GH3044 sheet is laser cut into two tangentially cut circles, as shown in Figure 4. Electron beam welding is then performed to form a full circle to obtain a flat blank. The electron beam welding conditions are as follows: Before welding, two arc-starting plates measuring 30×60 mm are positioned at both ends of the weld. The arc-starting plate profile should align with the outer diameter of the circular plate, with an assembly gap of no more than 0.2 mm and a misalignment of no more than 0.15 mm. Before welding, the joint surface is cleaned using pickling. Before welding, a test weld is performed using a test plate of equal thickness. After confirming full penetration, the weld is then welded. Nondestructive testing is performed after welding to ensure the weld is free of internal defects. Vacuum solution treatment is then performed. The vacuum solution treatment conditions are as follows: heating to 950±10°C within 90 minutes, holding for 26–30 minutes, then heating to 1150±10°C and holding for 14–16 minutes.

[0052] As shown in Figure 8, a welding tool is used to fix two tangential circles during electron beam welding. The welding tool includes a support assembly, a first fixing plate, a second fixing plate and a third fixing plate. The surface of the support assembly is used to place the two tangential circles. The first fixing plate, the second fixing plate and the third fixing plate are all located above the two tangential circles, and both ends are detachably connected to the support assembly. The first fixing plate and the second fixing plate are pressed above the larger tangential circle, and the third fixing plate is pressed above the smaller tangential circle. The second fixing plate and the third fixing plate are respectively located on both sides of the splicing position of the two tangential circles.

[0053] Step 2: Using 1Cr18Ni9Ti as a debugging material to perform deep drawing through a preforming die, then deep drawing the variable wall thickness flat blank through the preforming die into a shallow dished spinning blank, and performing vacuum solution treatment; specifically comprising:

[0054] First, the test material is drawn through a pre-forming die into a shallow dish shape. During this process, the blank holder and forming force parameters are determined. Then, using the blank holder and forming force parameters determined for the test material, the variable-wall-thickness flat blank is drawn through the pre-forming die into a shallow dish-shaped spun blank. The shallow dish-shaped blank is rotated 90° about its own axis and subjected to a further stretching forming process through the pre-forming die to correct the shallow dish shape and eliminate wrinkling at the large end. Both the shallow dish-shaped test material and the shallow dish-shaped blank undergo vacuum solution treatment. The vacuum solution treatment conditions are: heating to 950±10°C within 90 minutes, holding for 26-30 minutes, then heating to 1150±10°C and holding for 14-16 minutes.

[0055] As shown in Figure 1, the pre-forming die includes a blank holder 1, a positioning column 2, a female die 3, a push rod 4, and a male die 5. The female die is located on one side of the male die and can be moved in the direction close to or away from the male die. The positioning column is connected to the middle of the parting surface of the male die and cooperates with the center hole of the flat blank. The blank holder is sleeved on the outside of the male die and is slidably connected to the male die along the moving direction of the female die. During deep drawing, the flat blank has a center hole, which passes through the positioning column and is placed on the male die. The push rod lifts the blank holder and the part. The female die is pressed downward on the blank holder. The main cylinder pressure is 500 tons and the blank holder force is 350 tons to form the part. After forming, the female die is raised, the blank holder lifts the part, and the part is rotated 90°. The process is carried out once according to the deep drawing procedure, and the large end of the part is wrinkled and deformed. A pre-formed shallow dish-shaped blank is obtained, as shown in Figure 5.

[0056] Step 3: Spin the shallow dish-shaped blank for the first time to obtain a first-spin blank, and then perform vacuum solution treatment.

[0057] An initial allowance is determined based on the material of the shallow dished blank to obtain an initial spinning clearance at each location. The initial spinning clearance = theoretical wall thickness at each location of a spun blank minus the allowance. Based on the initial spinning clearance, a 1Cr18Ni9Ti test material having the same shape as the shallow dished blank is first installed on a spinning die for trial spinning. The spinning clearance is continuously adjusted until the wall thickness of the test material meets the requirements after the trial spinning, thereby obtaining an adjusted spinning clearance. After the shallow dished blank is installed, the shallow dished blank is aligned until the small end runout is ≤1 mm. The shallow dished blank is then spun using the adjusted spinning clearance to obtain a spun blank. During the spinning process, the spinning speed is 10 mm / min and the spindle speed is 54-25 rpm. The radius R of the spinning wheel corner during spinning is 8-10 mm. The conditions of vacuum solution treatment are: heating to 950±10°C within 90 minutes, keeping warm for 26 to 30 minutes, then heating to 1150±10°C, and keeping warm for 14 to 16 minutes.

[0058] Before the first spinning, measure the actual wall thickness of the shallow dished blank at multiple different positions evenly distributed on at least four busbars. During the first spinning process, adjust the spinning gap according to the measured wall thickness. When the wall thickness value of the part is large, the spinning gap is smaller, and when the wall thickness value is small, the spinning gap is larger. Instead of using one gap value for all parts, the wall thickness of the subsequent variable wall thickness flat blank after spinning is closer to the theoretical value; the gap adjustment value of the spinning gap is within ±0.06mm.

[0059] As shown in Figure 2, a spin mold includes a first tail top 6, a first positioning column 7, a first spinning tire body 8, a first adapter plate 9 and a first push rod 10. The large end of the first spinning tire body 8 is fixed on the first adapter plate 9. A through hole is provided at the axial position of the first spinning tire body 8. The first push rod 10 is located in the through hole and can move along the axial direction of the first spinning tire body 8. One end of the first push rod 10 covers the small end of the first spinning tire body 8. The first positioning column 7 is coaxially fixedly connected to the end of the first push rod 10. The first tail top axis A positioning hole is provided at the line position to cooperate with the first positioning post, so that the first positioning post 7 is coaxially connected to the first tail top 6. The small end of the first spinning tire body 8 is coaxially connected to the first tail top 6 through the first positioning post 7. The preformed blank is located between the small end of the first spinning tire body 8 and the first tail top 6. The first positioning post 7 passing through the central positioning hole of the preformed blank and the pressure of the first tail top 6 fix the part to the outside of the first spinning tire body 8. After spinning, the first push rod 10 is used to loosen the part from the first spinning tire body 8 and remove the part. A spinning blank is obtained, as shown in Figure 6.

[0060] Step 4: The first spinning blank is spun for the second time to form a variable wall thickness super-large size curved busbar variable wall thickness extension section. The large end diameter of the extension section is Axis length 1485mm. Specifically includes:

[0061] Determine the initial setback based on the material of the first-turn blank to obtain the initial spinning clearance of each part. The initial spinning clearance = the theoretical wall thickness of each part of the second-turn blank - the setback.

[0062] According to the initial spinning gap, first use 1Cr18Ni9Ti debugging material with the same shape as the first spinning blank for trial spinning, and continuously adjust the spinning gap until the wall thickness of the debugging material meets the requirements after the trial spinning, and obtain the adjusted spinning gap;

[0063] Then, the blank is spun using the adjusted spinning gap. During the second spinning process, the spinning speed is 10 mm / min and the spindle speed is 54-25 rpm. The radius R of the spinning wheel during spinning is 8-10 mm. A variable wall thickness extension section of a super-large curved busbar with variable wall thickness is obtained.

[0064] Before the second spinning, measure the actual wall thickness of a spinning blank at different positions on at least four busbars. Measure a wall thickness value every 10-20mm on each busbar. Adjust the spinning gap according to the measured wall thickness. When the wall thickness value of the part is large, the spinning gap is smaller, and when the wall thickness value is small, the spinning gap is larger. Instead of using one gap value for all parts, the wall thickness of the subsequent variable wall thickness flat blank after spinning is closer to the theoretical value. The gap adjustment value is within ±0.06mm.

[0065] The structure of the second spin mold is the same as that of the first spin mold, with only the size being different. As shown in Figure 3, the second spin mold includes a second tail top 11, a second positioning post 12, a second spinning body 13, a second adapter plate 14, and a second push rod 15. The large end of the second spinning body 13 is fixed to the second adapter plate 14, and the small end is coaxially connected to the second tail top 11 via the second positioning post 12. A spinning blank is located between the small end of the second spinning body 13 and the second tail top 11. It is fixed to the outside of the second spinning body 13 by the pressure of the second positioning post 12 passing through the center positioning hole of the first spin blank and the second tail top 11. After spinning, the second push rod 15 is used to loosen the part from the second spinning body 13 and remove the part. The second spinning blank is obtained, as shown in Figure 7.

[0066] In the present invention, the extension section obtained by the above-mentioned liquid rocket engine GH3044 super-large size tailor-welded spinning variable wall thickness extension section forming method has a product accuracy reaching a wall thickness tolerance of ±0.06mm at each point and a surface contour of ≤3mm.

[0067] In the present invention, for a thickness of 3.5 mm, laser cutting is performed into two tangential circles with a diameter of 1400 mm, and electron beam welding is performed into a full circle; after the first spinning, the wall thickness of the small end curved surface of the blank with a curved busbar and a wall thickness of The wall thickness of the large end curved surface is After secondary spinning, the wall thickness of the small end curved surface of the curved busbar variable wall thickness part is 1.5±0.06mm, and the wall thickness of the large end curved surface is 0.65±0.06mm.

[0068] Example:

[0069] Example 1

[0070] (1) High temperature alloy tangential cutting circle, electron beam welding becomes The electron beam welding conditions are as follows: Before welding, two arc-starting plates with dimensions no less than δ3.5×30×60mm should be positioned at each end of the weld. The arc-starting plate profile should align with the outer diameter of the circular plates, ensuring a clearance of 0.1mm and a misalignment of 0.1mm. Before welding, the joint surfaces should be cleaned with pickling. A test weld should be performed using a test plate of equal thickness. Once penetration is confirmed, the weld should be welded properly. After welding, an X-ray should be taken to inspect the weld for internal defects. Simultaneously, a 1Cr18Ni9Ti stainless steel test piece should be cut. The test piece should be the same size and shape as the high-temperature alloy. The high-temperature alloy undergoes solution heat treatment. The solution heat treatment schedule is: heating to 950±10°C within 90 minutes, holding for 26-30 minutes, then heating to 1150±10°C, and holding for 14-16 minutes. Solution treatment of 1Cr18Ni9Ti stainless steel.

[0071] (2) Pre-forming, i.e., deep drawing, is performed on an 800-ton hydraulic press, with a main cylinder pressure of 500 tons and a blank holder force of 350 tons. The steel is then rotated 90 degrees and the stretching process is repeated, using the same pressure to correct the shape and eliminate the wrinkling quadrant at the large end. Solution heat treatment is performed, with the following schedule: heating to 950±10°C within 90 minutes, holding at this temperature for 26-30 minutes, then heating to 1150±10°C and holding at this temperature for 14-16 minutes.

[0072] (3) Install a spinning wheel on a 60-ton spinning bed and adjust it. The radial runout of the large and small ends of the spinning wheel is ≤0.06mm. Prepare a spinning program and prepare 24-point spinning gaps along the axial direction. The principle of selecting 24 points is that the theoretical wall thickness of the part between two points should differ by 0.03-0.05mm. The spinning gap is the distance between the R angle of the spinning roller and the spinning wheel. The spinning gap is the wall thickness of the part at this point minus the allowance. After the program is compiled, use a feeler gauge to measure and confirm the spinning gap point by point. After the part is installed, it is spun into a curved busbar variable wall thickness blank. First, use stainless steel 1Cr18Ni9Ti debugging material for trial spinning. Adjust the spinning gap according to the wall thickness of the trial spinning part until the wall thickness of the debugging part meets the process requirements, and then spin the high-temperature alloy part. Solution treatment of high-temperature alloy parts. The solution heat treatment system is: heat to 950±10℃ within 90 minutes, keep warm for 26-30 minutes, then heat to 1150±10℃ and keep warm for 14-16 minutes. Solution treatment of stainless steel 1Cr18Ni9Ti.

[0073] (4) Install the second spinning wheel on the 60-ton spinning machine and adjust it. The radial runout of the large and small ends of the spinning wheel is ≤0.06mm. Prepare the spinning program and prepare 24-point spinning gaps along the axial direction. The principle of selecting the 24 points is that the theoretical wall thickness of the part between the two points should differ by 0.03-0.05mm. The spinning gap is the distance between the R angle of the spinning roller and the spinning wheel. The spinning gap is the wall thickness of the part at this point minus the allowance. After the program is compiled, use a feeler gauge to measure and confirm the spinning gap point by point. After the part is installed, it is spun into a curved busbar variable wall thickness blank. First, use stainless steel 1C18Ni9Ti debugging material for trial spinning. Adjust the spinning gap according to the wall thickness of the trial spinning part until the wall thickness of the debugging part meets the process requirements. Then spin the high-temperature alloy 3044 part. The large and small ends of the part are turned to the final size.

[0074] In this embodiment, the thickness of the flat plate blank is 3.45-3.55 mm.

[0075] After electron beam welding, the weld should be polished to a thickness not less than the thickness of the plate substrate. The flatness after electron beam welding should be guaranteed to be no greater than 3mm.

[0076] After the first spinning, the wall thickness of the curved busbar changes to 3.5mm at the small end of the blank, and the wall thickness of the small end curved surface is The diameter of the small end is 337mm; the wall thickness of the large end is The effective diameter of the large end is 1176mm; the effective length of the blank is 754.5mm.

[0077] After the second spinning, the wall thickness of the small end plane of the curved busbar part with variable wall thickness is 3.5mm, the wall thickness of the small end curved surface is 1.5±0.06mm, and the small end diameter is 337mm; the wall thickness of the large end curved surface is 0.65±0.06mm, and the effective diameter of the large end is 1176mm; the effective length of the part is 1476.5mm.

[0078] The product precision reaches the wall thickness tolerance of each point ±0.06mm, and the surface contour is ≤3mm.

[0079] The present application has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present application. Those skilled in the art will appreciate that, without departing from the spirit and scope of the present application, various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present application, all of which fall within the scope of the present application. The scope of protection of the present application shall be determined by the appended claims.

[0080] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

Claims

1. A method for forming a large-size extension section of a liquid rocket engine by welding and spinning with variable wall thickness, characterized in that: include: S1: Cut the plate into two tangential circles, electron beam weld them into a full circle to obtain a flat blank, and vacuum solution treat; S2: The flat blank is drawn into a shallow dish-shaped blank through a preforming die, and vacuum solution treatment is performed; S3: subjecting the shallow dish-shaped spinning blank to a first spinning process to obtain a first spinning blank, and subjecting it to vacuum solution treatment; S4: The first spinning blank is spun for the second time to form a variable wall thickness super-large size curved busbar variable wall thickness extension section, and the large end diameter of the extension section is not less than The axis length shall not be less than 1485mm.

2. The forming method according to claim 1, characterized in that: In the step S1, two tangent circles are fixed in a welding tool for electron beam welding. The welding tool comprises a support assembly (16), a first fixing plate (17), a second fixing plate (18) and a third fixing plate (19). The surface of the support assembly (16) is used to place the two tangent circles. The first fixing plate (17), the second fixing plate (18) and the third fixing plate (19) are all located above the two tangent circles and are detachably connected to the support assembly at both ends. The first fixing plate (17) and the second fixing plate (18) are pressed above the larger tangent circle, and the third fixing plate (19) is pressed above the smaller tangent circle. The second fixing plate and the third fixing plate are respectively located on both sides of the splicing position of the two tangent circles.

3. The forming method according to claim 1, characterized in that: In the step S2, the preforming mold includes a pressure ring (1), a positioning column (2), a female mold (3), a push rod (4) and a male mold (5). The female mold (3) and the male mold (5) are arranged relative to each other. The positioning column (2) is connected to the middle of the parting surface of the male mold (5) and cooperates with the center hole of the flat blank. The pressure ring (1) is sleeved on the outside of the male mold (5) and is slidably connected to the male mold along the moving direction of the female mold (3).

4. The forming method according to any one of claims 1 to 3, characterized in that: In step S2, after the flat blank is deep-drawn into a shallow dish shape by a pre-forming die, the shallow dish-shaped blank is rotated 90° around its own axis and subjected to another stretching forming process by the pre-forming die to correct the wrinkling deformation of the large end of the shallow dish-shaped blank to obtain a shallow dish-shaped blank, which is then subjected to vacuum solution treatment.

5. The forming method according to claim 1, characterized in that: In the step S3, a spin mold is used for the first spinning, and the spin mold includes a first tail top (6), a first positioning column (7), a first spinning tire body (8), a first adapter plate (9) and a first push rod (10), the large end of the first spinning tire body (8) is fixed on the first adapter plate (9), a through hole is provided at the axial position of the first spinning tire body (8), the first push rod (10) is located in the through hole and can move along the axial direction of the first spinning tire body (8), and one end of the first push rod (10) covers the first spinning tire body (8). The first positioning column (7) is coaxially fixedly connected to the end of the first push rod at the small end of the pressed tire body, and a positioning hole matching with the first positioning column (7) is provided at the axial position of the first tail top (6) so that the first positioning column (7) and the first tail top (6) are coaxially connected. The shallow dish-shaped blank is located between the small end of the first spun tire body (8) and the first tail top (6), and the first positioning column (7) passes through the central positioning hole of the shallow dish-shaped blank. After spinning, the shallow dish-shaped blank is loosened from the first spun tire body (8) by using the first push rod (10).

6. The forming method according to claim 1, characterized in that: In the step S3, the initial allowance is determined according to the material of the shallow dish-shaped blank, and the initial spinning gap of each part is obtained, where the initial spinning gap = the theoretical wall thickness of each part of the shallow dish-shaped blank - the allowance; according to the initial spinning gap, a 1Cr18Ni9Ti test material consistent with the shape of the shallow dish-shaped blank is first used for trial spinning, and the spinning gap is continuously adjusted until the wall thickness of the test material meets the requirement after the trial spinning, thereby obtaining the adjusted spinning gap; and the shallow dish-shaped blank is spun using the adjusted spinning gap to obtain a shallow dish-shaped blank.

7. The forming method according to claim 1, characterized in that: In the step S3, before the first spinning, the shallow dish-shaped blank is evenly distributed on at least four generatrixes, and the wall thickness is measured at intervals of 50-60 mm. During the first spinning process, the spinning gap is adjusted according to the measured wall thickness value. When the wall thickness value of the part is large, the spinning gap is smaller, and when the wall thickness value is small, the spinning gap is larger. The clearance adjustment value of the spinning clearance is within ±0.06mm.

8. The forming method according to claim 1, characterized in that: In the step S3, during the first spinning process, the spinning speed is 10 mm / min, the spindle speed is 54-25 rpm; and the radius R of the spinning wheel during spinning is 8-10 mm.

9. The forming method according to claim 1, characterized in that: In the step S4, Determine the initial setback amount according to the material of the first-turn blank, and obtain the initial spinning gap of each part. The initial spinning gap = the theoretical wall thickness of each part of the second-turn blank - the setback amount; According to the initial spinning gap, first use the 1Cr18Ni9Ti test material with the same shape as the first spinning blank for trial spinning, and continuously adjust the spinning gap until the wall thickness of the test material meets the requirements after the trial spinning, and obtain the adjusted spinning gap; Then use the adjusted spinning gap to spin the blank for the second spinning process. The spinning speed is 10 mm / min, the spindle speed is 54-25 rpm; the radius R of the spinning wheel during spinning is 8-10 mm; a variable wall thickness extension section of a super-large size curved generatrix with variable wall thickness is obtained.

10. The forming method according to claim 9, characterized in that: In step S4, before the second spinning, the actual wall thickness of a spun blank is measured at different positions on at least four busbars, and a wall thickness value is measured every 10-20 mm for each busbar. The spinning gap is adjusted according to the measured wall thickness. When the wall thickness value of the part is large, the spinning gap is smaller, and when the wall thickness value is small, the spinning gap is larger; the gap adjustment value is within ±0.06 mm.

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