Integrated machining method for niobium-tungsten alloy composite surface variable-wall-thickness thin-walled workpiece

Abstract

The invention relates to an integrated machining method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-wall part, and belongs to the field of metal plate forming. Determining the size of a niobium-tungsten alloy plate according to the size of the composite surface; groove milling is conducted on the spinning clamping position of the niobium-tungsten alloy plate; the machined plate is arranged on a spinning tire, and a tail top is used for clamping and fixing; the variable wall thickness forming of the curved generatrix part is realized by adopting strong shearing spinning and common spinning deep drawing spinning; the equal-wall-thickness forming of the cylindrical part is realized by adopting multi-pass deep drawing and spinning; the tiny allowance of the outer wall is removed through precise turning cutting, and it is guaranteed that the wall thickness meets the product use requirement; polishing the inner and outer surfaces to reduce the surface roughness; the niobium-tungsten alloy plate is used for forming, the material utilization rate is increased, split connection weld joints are reduced through a highly-integrated forming method, and the structural reliability is improved.

Description

Technical Field

[0001] The present invention belongs to the field of sheet metal forming, and relates to an integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part. Background Art

[0002] During the operation of a liquid rocket engine, it is necessary to rely on a thrust chamber for deceleration and attitude adjustment. The working temperature of the thrust chamber body reaches as high as 1400 °C, and niobium-tungsten alloy has high temperature resistance and is the preferred material for body processing. At the same time, in order to avoid ablation of the cabin wall during the operation of the thrust chamber, the body structure needs to have the function of lateral flame exhaust. Therefore, a 30° bevel cutting design is adopted at the outlet of the body extension section. In order to ensure that the body still has sufficient rigidity after bevel cutting, the extension section is designed as a composite surface structure. The composite surface is composed of a curved generatrix and a cylindrical shape, where the curved generatrix is the variable-wall-thickness area and the cylindrical shape is the equal-wall-thickness area.

[0003] Using bar machining for the niobium-tungsten alloy composite surface body not only has low material utilization rate, low part strength, but also has a long processing cycle. If a segmented welding process method is adopted, it is difficult to control the welding deformation of thin-walled parts, and there are high dimensional accuracy requirements for the mating parts. Summary of the Invention

[0004] The technical problem solved by the present invention is: overcoming the deficiencies of the prior art, and proposing an integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part, using niobium-tungsten alloy sheet for forming, improving material utilization rate, and reducing the split connection welds through a highly integrated integrated forming method to improve the structural reliability.

[0005] The solution to the technical problem of the present invention is:

[0006] An integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part, characterized by comprising:

[0007] Determining the size of the niobium-tungsten alloy sheet according to the size of the composite surface;

[0008] Milling grooves for the spinning clamping position of the niobium-tungsten alloy sheet;

[0009] Installing the processed sheet on a spinning mandrel and using a tailstock for clamping and fixing;

[0010] Adopting power shear spinning and conventional spinning drawing to realize the variable-wall-thickness forming of the curved generatrix part;

[0011] Adopting multi-pass drawing spinning to realize the equal-wall-thickness forming of the cylindrical part;

[0012] Adopting precision turning to remove the tiny surplus on the outer wall to ensure that the wall thickness meets the product use requirements;

[0013] Grinding the inner and outer surfaces to reduce the surface roughness.

[0014] In the above-mentioned integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part, the composite surface includes a curved generatrix part and a cylindrical part; the large-diameter end of the curved generatrix part is coaxially butted with the cylindrical part; the curved generatrix part has a variable-wall-thickness structure, and the cylindrical part has a constant-wall-thickness structure.

[0015] In the above-mentioned integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part, the inner diameter D1 of the small-diameter end of the curved generatrix part is 25 - 35 mm; the wall thickness δ1 of the small-diameter end is 2 - 2.5 mm; the inner diameter D2 of the large-diameter end of the curved generatrix part is 60 - 70 mm; the wall thickness δ2 of the large-diameter end is 1 - 1.5 mm; the total length L1 is 60 - 70 mm; the inner diameter and wall thickness of the cylindrical part are the same as those of the large-diameter end part of the curved generatrix, and the total length L2 of the cylindrical part is 100 - 120 mm.

[0016] In the above-mentioned integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part, the initial wall thickness of the niobium-tungsten alloy sheet is δ0, and the diameter is D0; the initial wall thickness δ0 of the niobium-tungsten alloy sheet is 1.5 - 2 times the wall thickness δ1 of the small-diameter end of the curved generatrix part; the diameter D0 of the niobium-tungsten alloy initial sheet is:

[0017]

[0018] where x is the coordinate of the niobium-tungsten alloy initial sheet along the axial direction;

[0019] a, b, and c are the cubic term coefficient, quadratic term coefficient, and linear term coefficient of x respectively;

[0020] d is the constant term coefficient;

[0021] Round up the result.

[0022] In the above-mentioned integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part, the length of the groove after milling is 12 mm, the width of the groove is 3 mm, and the depth of the groove is between 1 / 2 and 1 / 3 of the initial wall thickness δ0 of the niobium-tungsten alloy sheet.

[0023] In the above-mentioned integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part, a positioning block is left at the top of the spinning mandrel; the positioning block has a clearance fit with the sheet milling groove dimension of 0.1 mm on one side, and is clamped and fixed with a tailstock after clamping.

[0024] In the above-mentioned integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part, the process of power shear spinning and conventional spinning deep drawing is as follows:

[0025] The spinning wheel is divided into one working step every 3 mm along the axial direction of the curved generatrix; each working step is a circular trajectory of the spinning wheel for one pass; after every 3 - 5 working steps, the spinning wheel feeds reversely along the drawing and spinning direction to ensure the conformability of the processed part in the previous 3 - 5 working steps to the mandrel.

[0026] In the above - mentioned integrated processing method for a niobium - tungsten alloy composite - surface variable - wall - thickness thin - walled part, the corner radius of the spinning wheel circle is 8 mm, the diameter of the spinning wheel is 230 mm, the attack angle of the spinning wheel is 45°, and the rotational speed of the spinning mandrel is 270 - 330 r / min.

[0027] In the above - mentioned integrated processing method for a niobium - tungsten alloy composite - surface variable - wall - thickness thin - walled part, the technological process of multi - pass drawing and spinning is as follows:

[0028] The spinning wheel is divided into one working step every 4 mm along the cylindrical axial direction. Each working step is a circular trajectory of the spinning wheel for one pass. After every 5 working steps, the spinning wheel feeds reversely along the drawing and spinning direction to ensure the conformability of the processed part in the previous 5 working steps to the mandrel.

[0029] In the above - mentioned integrated processing method for a niobium - tungsten alloy composite - surface variable - wall - thickness thin - walled part, the corner radius of the spinning wheel circle is 8 mm, the diameter of the spinning wheel is 230 mm, the attack angle of the spinning wheel is 45°, and the rotational speed of the spinning mandrel is 270 - 330 r / min.

[0030] The beneficial effects of the present invention compared with the prior art are as follows:

[0031] (1) In the integrated processing method for a niobium - tungsten alloy composite - surface thin - walled part of the present invention, the composite surface is composed of a curved generatrix and a cylinder. The curved generatrix part is the variable - wall - thickness area, and the cylinder part is the equal - wall - thickness area. The method of spinning + machining is used to replace the traditional overall machining or split - welding process.

[0032] (2) The present invention uses the spinning forming of niobium - tungsten alloy sheet instead of the machining of niobium - tungsten alloy bar stock, improving the material utilization rate.

[0033] (3) The composite surface of the present invention uses the overall spinning forming to replace the split - welding process, reducing the processes and the product turnover process, and improving the production efficiency.

[0034] (4) The present invention has a weld - free structure, reducing welding deformation and improving the product dimensional accuracy and structural strength. Description of the Drawings

[0035] Figure 1 It is the integrated processing flow chart of the variable - wall - thickness thin - walled part of the present invention;

[0036] Figure 2 It is the structural schematic diagram of the composite surface of the present invention;

[0037] Figure 3 It is the schematic diagram of the spinning wheel trajectory of the present invention. Detailed implementation manners

[0038] The present invention will be further described below in conjunction with embodiments.

[0039] The present invention provides an integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part. The curved bus + cylindrical composite surface is formed through multi-pass spinning, and then the external surplus is removed by single-sided precision numerical control turning to make the wall thickness meet the requirements. Finally, the surface roughness is ensured through grinding and polishing. This method has the following advantages: using niobium-tungsten alloy sheet material for forming, improving the material utilization rate, reducing the split connection welds through a highly integrated integrated forming method, improving the structural reliability, providing a highly integrated, highly reliable and low-cost method for processing niobium-tungsten alloy composite surface thin-walled parts, and meeting the requirements for forming the extension section of the reverse thrust chamber of a certain aerospace model product.

[0040] The integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part, as Figure 1 described, specifically includes the following steps:

[0041] Determine the size of the niobium-tungsten alloy sheet material according to the size of the composite surface.

[0042] The composite surface includes a curved bus part and a cylindrical part; the large-diameter end of the curved bus part is coaxially butted with the cylindrical part; the curved bus part is a variable-wall-thickness structure, and the cylindrical part is an equal-wall-thickness structure, as Figure 2 shown.

[0043] The inner diameter D1 of the small-diameter end of the curved bus part is 25-35 mm; the wall thickness δ1 of the small-diameter end is 2-2.5 mm; the inner diameter D2 of the large-diameter end of the curved bus part is 60-70 mm; the wall thickness δ2 of the large-diameter end is 1-1.5 mm; the total length L1 is 60-70 mm; the inner diameter and wall thickness of the cylindrical part are the same as those of the large-diameter end part of the curved bus, and the total length L2 of the cylindrical part is 100-120 mm.

[0044] The initial wall thickness of the niobium-tungsten alloy sheet material is δ0, and the diameter is D0; the initial wall thickness δ0 of the niobium-tungsten alloy sheet material is 1.5-2 times the wall thickness δ1 of the small-diameter end of the curved bus part; the diameter D0 of the niobium-tungsten alloy initial sheet material is:

[0045]

[0046] In the formula, x is the coordinate of the niobium-tungsten alloy initial sheet material along the axial direction;

[0047] a, b, and c are the cubic term coefficient, quadratic term coefficient, and linear term coefficient of x respectively;

[0048] d is the constant term coefficient;

[0049] Round up the result.

[0050] Milling slots at the clamping position of niobium-tungsten alloy sheet for spinning; after milling, the slot length is 12 mm, the slot width is 3 mm, and the slot depth is between 1 / 2 and 1 / 3 of the initial wall thickness δ0 of the niobium-tungsten alloy sheet.

[0051] Install the processed sheet on the spinning mandrel and use the tailstock to clamp and fix it; there is a positioning block at the top of the spinning mandrel; the clearance between the positioning block and the milled slot of the sheet is 0.1 mm on one side, and after clamping, use the tailstock to clamp and fix it.

[0052] Adopt power shear spinning and conventional spinning with deep drawing to achieve variable wall thickness forming of the curved generatrix part.

[0053] The technological processes of power shear spinning and conventional spinning with deep drawing are as follows:

[0054] The spinning wheel divides every 3 mm along the axial direction of the curved generatrix into one working step; each working step is a circular trajectory of the spinning wheel for one pass; after every 3 - 5 working steps, the spinning wheel feeds reversely along the deep drawing spinning direction to ensure the conformability of the processed part in the first 3 - 5 working steps.

[0055] The specific process parameters are: the corner radius of the spinning wheel circle is 8 mm, the diameter of the spinning wheel is 230 mm, the attack angle of the spinning wheel is 45°, and the rotational speed of the spinning mandrel is 270 - 330 r / min.

[0056] Adopt multi-pass deep drawing spinning to achieve equal wall thickness forming of the cylindrical part.

[0057] The technological process of multi-pass deep drawing spinning is as follows:

[0058] The spinning wheel divides every 4 mm along the axial direction of the cylinder into one working step, each working step is a circular trajectory of the spinning wheel for one pass, and after every 5 working steps, the spinning wheel feeds reversely along the deep drawing spinning direction to ensure the conformability of the processed part in the first 5 working steps.

[0059] The specific process parameters are: the corner radius of the spinning wheel circle is 8 mm, the diameter of the spinning wheel is 230 mm, the attack angle of the spinning wheel is 45°, and the rotational speed of the spinning mandrel is 270 - 330 r / min, as Figure 3 shown.

[0060] Adopt precision turning to remove the tiny remaining amount on the outer wall to ensure that the wall thickness meets the product usage requirements;

[0061] Polish the inner and outer surfaces to reduce the surface roughness.

[0062] The technical key points of the present invention are as follows:

[0063] 1. The composite surface is composed of a curved generatrix and a cylinder. The curved generatrix is the variable wall thickness area, and the cylinder is the equal wall thickness area. Adopt multi-pass spinning for forming, supplemented by precision turning to ensure the wall thickness accuracy of the part, and finally ensure the surface roughness through grinding and polishing.

[0064] 2. Determine the initial blank specifications and dimensions of the niobium-tungsten alloy by combining the product structure, wall thickness, dimensions, and material properties.

[0065] 3. Pre-process the initial blank to ensure that the blank does not undergo circumferential sliding relative to the spinning mandrel during the processing.

[0066] 4. Divide the spinning process steps and perform multi-pass spinning according to the spinning wheel trajectory for each step.

[0067] 5. Determine reasonable spinning wheel process parameters and the spinning mandrel rotation speed.

[0068] Embodiment

[0069] The embodiment of the present invention is an extended section of the thrust chamber body of a certain reverse thrust, with a composite surface, mainly composed of a curved generatrix part 1 and a cylindrical part 2. The wall thickness of the curved generatrix part decreases uniformly from the small end to the large end and smoothly transitions to the cylindrical part, and the cylindrical part has a constant wall thickness.

[0070] In the embodiment of the present invention, the initial blank 3 is mounted on the spinning mandrel 4 and fixed using the tailstock 5. During the processing, the spinning mandrel drives the initial blank to rotate, and the spinning wheel 6 feeds along the trajectory line.

[0071] The specific implementation steps are as follows:

[0072] (1) As Figure 1 shown, the inner diameter D1 of the small end of the curved generatrix part of the product is 30.7 mm, the wall thickness δ1 is 2.2 mm, the inner diameter D2 of the large end is 66 mm, the wall thickness δ2 is 1 mm, and the total length L1 is 65 mm; the total length L2 of the cylindrical part is 117 mm. Determine the initial blank wall thickness δ0 = 3.5 mm and D0 = 190 mm according to the product structure dimensions.

[0073] (2) Milling slot processing of the initial blank, with the slot length being 12 mm, width being 3 mm, and depth being 1.5 mm.

[0074] (3) Mount the initial blank on the spinning mandrel. The positioning block at the top of the spinning mandrel has a length of 11.8 mm, width of 2.8 mm, and height of 1.5 mm. After assembly, hold the initial blank by hand and fix it using the tailstock.

[0075] (4) The initial blank rotates with the spinning mandrel at a speed of 300 r / min, and the fork-type double spinning wheel feeds along the trajectory line of each process step according to the control program. The fillet radius of the spinning wheel is 8 mm, the diameter of the spinning wheel is 230 mm, and the attack angle of the spinning wheel is 45°.

[0076] (5) In step 4, the wheel circular trajectory is divided into five segments. The first segment is a fast linear approach to the starting position of spinning. The second segment is a slow approach and contact to the spinning position. The third segment of the trajectory is determined based on material strength, the semi-cone angle at the contact position, the thickness of the raw material, and the material thickness reduction. It performs a forward spinning feed of 3 mm along the axial direction, and applies a film at this segment during spinning. The fourth segment is that the wheel draws and spins forward the material that is not in contact with the die tire along the involute to the tail end position until the wheel separates from the part. The fifth segment is that the wheel quickly returns to the starting position of the next spinning cycle.

[0077] (6) In step 4, after every 3 - 5 working step cycles, a sizing process is performed. The third segment of the wheel cycle working steps performs a sizing on the selected outer surface of the part with a small radial feed amount to ensure smooth indirect tooling at the spinning passes on the inner surface of the part.

[0078] (7) After the forming of the curved generatrix part, ensure that the rotation speed of the spinning tire remains unchanged and the wheel process parameters remain unchanged. The wheel trajectory combines the involute forward drawing spinning and the return spinning trajectory. As the spinning length increases, gradually increase the length of the third segment of the wheel cycle working steps for each spinning cycle. For each pass cycle, it increases by about 1 mm until the part is spun to the end of the cylindrical shape.

[0079] (8) In step 7, after every 5 working step cycles, a sizing process is performed. The third segment of the wheel cycle working steps performs a sizing on the selected outer surface of the part with a small radial feed amount to ensure smooth indirect tooling at the spinning passes on the inner surface of the part.

[0080] (9) After the forming of the cylindrical part, perform precision turning to ensure that the wall thickness δ2 of the cylindrical part is 1 + 0.2 0 mm.

[0081] (10) After the machining of the extension section, polish and buff the inner and outer surfaces, control the surface roughness Ra to 1.6, and ensure the surface is in the best state for coating preparation.

[0082] (11) Detect that the inner profile meets the requirement that the profile tolerance does not exceed 0.2, and both the diameter and wall thickness meet the dimensional requirements.

[0083] The present invention discloses an integrated processing method for a niobium - tungsten alloy composite - shaped thin - wall part. The composite shape is composed of a curved generatrix and a cylinder. The curved generatrix part is a variable - wall - thickness area, and the cylinder part is an equal - wall - thickness area. The method of spinning + machining is used to replace the traditional overall machining or split - body welding process.

[0084] The present invention uses the spinning forming of niobium - tungsten alloy sheet material instead of the machining of niobium - tungsten alloy bar stock to improve the material utilization rate. The composite shape of the present invention uses the overall spinning forming instead of the split - body welding process, reducing the processes and the product turnover process, and improving the production efficiency.

[0085] The present invention adopts a seamless - weld structure, reducing welding deformation and improving the product dimensional accuracy and structural strength.

[0086] Although the present invention has been disclosed above in preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and decorations made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. An integrated processing method for a niobium-tungsten alloy composite surface variable-wall thickness thin-walled part, characterized in that: Including: Determine the size of the niobium-tungsten alloy sheet according to the size of the composite surface; Milling grooves at the spinning clamping position of the niobium-tungsten alloy sheet; Install the processed sheet on the spinning mandrel and use the tailstock to clamp and fix it; Adopt power shear spinning and conventional spinning deep drawing to achieve variable wall thickness forming of the curved busbar part; Adopt multi-pass deep drawing spinning to achieve equal wall thickness forming of the cylindrical part; Use precision turning to remove the tiny surplus on the outer wall to ensure that the wall thickness meets the product usage requirements; Grind the inner and outer surfaces to reduce the surface roughness.

2. The integrated processing method of a niobium-tungsten alloy composite surface variable-wall thickness thin-walled part according to claim 1, characterized in that: The composite surface includes a curved busbar part and a cylindrical part; the large-diameter end of the curved busbar part is coaxially butted with the cylindrical part; the curved busbar part is a variable wall thickness structure, and the cylindrical part is an equal wall thickness structure.

3. The integrated processing method of a niobium-tungsten alloy composite surface variable-wall thickness thin-walled part according to claim 2, characterized in that: The inner diameter D1 of the small-diameter end of the curved busbar part is 25 - 35 mm; the wall thickness δ1 of the small-diameter end is 2 - 2.5 mm; the inner diameter D2 of the large-diameter end of the curved busbar part is 60 - 70 mm; the wall thickness δ2 of the large-diameter end is 1 - 1.5 mm; the total length L1 is 60 - 70 mm; the inner diameter and wall thickness of the cylindrical part are the same as those of the large-diameter end part of the curved busbar, and the total length L2 of the cylindrical part is 100 - 120 mm.

4. The integrated processing method for a niobium-tungsten alloy complex surface variable-wall-thickness thin-walled part according to claim 3, characterized in that: The initial wall thickness of the niobium-tungsten alloy sheet is δ0, and the diameter is D0; the initial wall thickness δ0 of the niobium-tungsten alloy sheet is 1.5 - 2 times the wall thickness δ1 of the small-diameter end of the curved busbar part; the diameter D0 of the niobium-tungsten alloy initial sheet is: where x is the coordinate of the niobium-tungsten alloy initial sheet along the axial direction; a, b, and c are the cubic term coefficient, quadratic term coefficient, and linear term coefficient of x respectively; d is the constant term coefficient; Round up the result.

5. An integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part according to claim 1, characterized in that: The length of the groove after milling is 12 mm, the width of the groove is 3 mm, and the depth of the groove is between 1 / 2 and 1 / 3 of the initial wall thickness δ0 of the niobium-tungsten alloy sheet.

6. The integrated processing method of a niobium-tungsten alloy composite surface variable-wall thickness thin-walled part according to claim 1, wherein: There is a positioning block at the top of the spinning mandrel; the clearance between the positioning block and the sheet milling groove is a unilateral 0.1 mm clearance fit, and after clamping, use the tailstock to clamp and fix it.

7. An integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part according to claim 1, characterized in that: The process of power shear spinning and conventional spinning deep drawing is: The spinning wheel divides every 3 mm along the axial direction of the curved busbar into 1 working step; each working step is a cycle track of the spinning wheel; after every 3 - 5 working steps, the spinning wheel feeds reversely along the deep drawing spinning direction to ensure the conformability of the processed part in the previous 3 - 5 working steps.

8. An integrated processing method for a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part according to claim 7, characterized in that: The corner radius of the spinning wheel circle is 8 mm, the diameter of the spinning wheel is 230 mm, the attack angle of the spinning wheel is 45°, and the spinning mandrel speed is 270 - 330 r / min.

9. The integrated processing method of a niobium-tungsten alloy composite surface variable-wall-thickness thin-walled part according to claim 1, characterized in that: The process of multi-pass deep drawing spinning is: The spinning wheel divides every 4 mm along the axial direction of the cylinder into one working step, each working step is a track of the spinning wheel, and after every 5 working steps, the spinning wheel feeds reversely along the deep drawing spinning direction to ensure the conformability of the processed part in the previous 5 working steps.

10. A method for integrally machining a niobium-tungsten alloy composite surface variable-wall thickness thin-walled part according to claim 9, characterized in that: The corner radius of the spinning wheel circle is 8 mm, the diameter of the spinning wheel is 230 mm, the attack angle of the spinning wheel is 45°, and the spinning mandrel speed is 270 - 330 r / min.

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