Machining methods for irregular wall structures in aero engines

Abstract

This invention discloses a method for processing irregularly shaped walls of aero-engines, comprising sequential steps of stretching, first cutting, welding, heat treatment, bulging, and second cutting, ultimately obtaining an accurate shape for the irregularly shaped wall. This invention employs a method of pre-forming the skin by stretching, followed by welding, and then integral bulging. During skin stretching, different stretching templates are used to form the convex and concave surfaces respectively. During bulging, different bulging blocks are used for different types of surfaces and transition areas between different surfaces, forming both internal and external bulging. Combined with two cutting steps, the final shape contour is obtained. This invention produces irregularly shaped walls with accurate surfaces, high processing efficiency, and low processing difficulty.

Description

Technical Field

[0001] This invention belongs to the field of machining and relates to a machining method for large irregular shaped parts with 90° variable cross-section for aero engines. Background Technology

[0002] like Figure 1 The image shows an irregularly shaped wall structure for an aero-engine, specifically a large, 90° (the axis of surface B is perpendicular to the axes of surfaces C and D) variable cross-section irregularly shaped component. This component has a diameter of 1.5m, and its cross-section continuously changes. Surface A is spherical, surfaces C and B are straight-walled arc surfaces that smoothly transition to surface A, surface D is symmetrical to surface C, and surface B is concave. N represents the outward-facing flange line, and H is an arc line.

[0003] Due to the complexity of the parts' structure, they were difficult to form. The previous solution was to splice the cylindrical structure. However, the splicing structure resulted in too many welds on the parts, large welding deformation, excessively high requirements for the operator's processing skills, high labor intensity, and extremely low processing efficiency.

[0004] For the reasons mentioned above, there is an urgent need to propose a processing method for the variable cross-section irregular wall of aero-engines. Summary of the Invention

[0005] The present invention aims to provide a method for processing irregularly shaped walls of aero-engines, which reduces the number of welds, lowers the processing difficulty, improves forming quality and efficiency, and meets the requirements of part dimensional accuracy.

[0006] The core idea of ​​this invention is: to use skin stretching pre-forming followed by welding, and then to bulge the whole body. During skin stretching, different stretching molds are used to form the convex and concave surfaces respectively. During bulging, different bulging blocks are used for different types of surfaces and the transition areas between different surfaces to form the inner and outer hoops. The final outline is obtained by combining two cutting methods.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for machining irregularly shaped walls of an aero-engine, wherein the irregularly shaped wall includes surface A, surface B, and surface C, wherein surface A is a sphere, surface B is a concave straight-walled arc surface, and surface C is a straight-walled arc surface. The machining method includes...

[0009] Step 1: Drawing and forming. Two irregular wall blanks are formed by drawing sheet metal into two irregular wall blanks using a skin drawing machine. The inner wall profile of the irregular wall blank is consistent with the inner wall profile of the aero-engine irregular wall. The profile of the drawing die is 1 / 2 of the inner wall profile after the complete inner wall profile of the aero-engine irregular wall is divided along the axial symmetry plane.

[0010] Step 2: First cut: Cut along the profile of the aero-engine wall to obtain the outer contour of the aero-engine wall, and remove the burrs and remelted layer from the edge of the outer contour.

[0011] Step 3: Welding. After splicing the two irregularly shaped blanks together, weld them into a ring-shaped blank.

[0012] Step 4: Heat treatment to remove stress from welding and stretching of the ring-shaped blank;

[0013] Step 5: Expansion forming. For the annular blank, the internal expansion and external clamping methods are used to precisely expand and form the profile of the irregular wall of the aero-engine.

[0014] Step 6: Second cutting, cutting away the excess part to obtain the final shape of the aero-engine irregular wall.

[0015] Furthermore, in step 1, the sheet material is a rectangular sheet material, and the sheet material is in a solution-treated state, with the two sides in the width direction of the sheet material being flat and smooth.

[0016] Furthermore, in step 1, the forming die includes a first punch for forming surface A and surface C, and a second punch for forming surface B. The first forming process produces surface A and surface C, and the second forming process produces surface B, or the first forming process produces surface B, and the second forming process produces surface A and surface C.

[0017] Furthermore, in step 2, a five-axis laser cutting machine is used to cut the irregular wall blank along the outer shape of the forming die to obtain the outer contour of the irregular wall of the aero-engine.

[0018] Furthermore, in step 3, the joint of the two irregular wall blanks is polished and cleaned to ensure that the joint gap and misalignment dimensions meet the requirements.

[0019] Furthermore, in step 3, two irregularly shaped blanks are welded using argon arc welding.

[0020] Furthermore, in step 4, welding stress and tensile forming stress are relieved according to the material of the sheet metal in step 1.

[0021] Furthermore, in step 5, during the bulging process, the surface of the irregular wall of the aero-engine is divided into a left surface and a right surface according to the axial symmetry plane. The left surface and the right surface are further divided into surface A, the transition area between surface A and surface C, the transition area between surface C and surface B, and surface B. Different bulging blocks are used for each area.

[0022] Furthermore, in step 5, the mold used for bulging includes a lower template, a top plate, an upper template, an outer cone, an outer bulging block, an inner bulging block, and an inner cone, wherein:

[0023] The top plate is vertically and retractably connected to the lower template, and the upper end of the top plate is supported on the lower end of a portion of the internal expansion block.

[0024] The outer cone and the inner cone are fixedly connected to the lower template. The outer cone has a first groove with the same taper on its conical surface, and the inner cone has a second groove with the same taper on its conical surface.

[0025] The outer expansion block is slidably connected to the first slide groove via a slider, and the inner expansion block is slidably connected to the second slide groove via a slider. When the upper template drives the outer expansion block and the inner expansion block to move towards the lower template, the expansion surfaces of the outer expansion block and the inner expansion block approach each other.

[0026] Furthermore, in step 6, a cutting template is used in conjunction with a five-axis laser cutting machine for a second cutting. The cutting template includes multiple spaced blocks that are symmetrically distributed about the axial direction of the complete inner wall surface of the aero-engine irregular wall. Each block contains a part of the characteristic surface of the aero-engine irregular wall, and the cutting template is etched with lines.

[0027] Compared with the prior art, the processing method of the present invention has the following characteristics:

[0028] (1) There is only one weld, and the weld is on the axial symmetry plane of the aero-engine irregular wall, which ensures that the deformation of the two sides of the axial symmetry plane is basically consistent.

[0029] (2) By adopting a batch drawing forming method, the concave curved surface and the convex curved surface are drawn separately to obtain more accurate surface features and reduce the forming difficulty;

[0030] (3) When stretching the sheet material, ensure that the sides in the width direction are smooth and flat to avoid severe wavy structures at the edges during the stretching process;

[0031] (4) When bulging the whole, different bulging blocks (lobes) are used for different curved surface areas to obtain more accurate surface features;

[0032] (5) The combination of stretching and bulging reduces the difficulty of forming, which is conducive to controlling the accuracy of variable cross-section irregular wall, shortening the development cycle and reducing processing costs;

[0033] (6) In the two cuts, the first cut directly uses the stretching mold (complete irregular wall surface), and the second cut uses the characteristic surface to construct the cutting mold (only some of the key and characteristic surfaces of the irregular wall). The cutting efficiency is high and the quality of the irregular wall outline dimensions is guaranteed.

[0034] The processing method of this invention is currently being used in the field, achieving the purpose and technical requirements of this invention. Attached Figure Description

[0035] Figure 1This is a schematic diagram of the irregular wall structure of an aircraft engine;

[0036] Figure 2 This is the main view of the bulging mold assembly;

[0037] Figure 3 This is a top view of the bulging mold;

[0038] Figure 4 This is a cross-sectional view of section BB along the inner and outer expansion blocks numbered 4;

[0039] Figure 5 It is a cut-type tire axle view;

[0040] In the diagram, 1 is the lower template; 2 is the top plate; 3 is the upper template; 4 is the outer cone; 5 is the outer expansion block; 6 is the inner expansion block; and 7 is the inner cone. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0042] like Figures 2-5 The image shows the bulging mold and cutting die used in the aero-engine irregular wall processing method of this invention. During processing, as shown... Figure 1 The aero-engine irregular wall is divided into upper and lower parts along the plane of symmetry of points a, b, c, d, and e in the diagram. First, the skin is stretched to form both parts, then cut and welded (the weld seams correspond to the planes of symmetry of points a, b, c, d, and e). Then, it is bulged, and finally cut and trimmed. The aero-engine irregular wall processing method includes the following steps:

[0043] Step 1: Stretching (skin stretching). Select a sheet material with dimensions of 1000×2000. The sheet material is in a solution-treated state. Stretch the sheet material into shape using a skin stretching machine. The long end of the sheet material is fixed in the clamp of the skin stretching machine for clamping. The machine is used for processing under high pressure. Under high pressure, the equipment has high pressure and slow stretching speed. Stretching uses a punch stretching die. The die shape is consistent with the inner surface shape of the irregular wall (the stretching die is composed of two parts, one with the B-side concave feature and the other with the A and C-side convex features). The die requires a gap of at least 40mm between the bottom surface and the platform in the clamping direction. When forming irregular walls, it can extend to the root of the irregular wall. Stretching is done in two stages: one to complete the B-side and the other to complete the A and C-sides. Finally, two symmetrical irregular wall blanks are obtained.

[0044] Step 2: First cut, cut along the surface. Use a five-axis laser cutting machine to place the irregular wall blank on the drawing die, cut the outline along the shape of the die, and remove the surrounding burrs and remelted layer.

[0045] Step 3: Welding. Argon arc welding is used to weld the two irregular wall blanks into a ring blank along the axial symmetry plane of the irregular wall. Before welding, the area to be welded needs to be polished to ensure that the area to be welded is clean and that the gap between the butt joints is no more than 0.2mm and the misalignment is no more than 0.2mm.

[0046] Step 4: Heat treatment to remove welding and stretching stress. Select the appropriate material heat treatment standard according to the material of the sheet (in this invention, the material of the irregular wall is a high-temperature alloy).

[0047] Step 5: Expansion forming, using internal expansion and external clamping to ensure the profile of the irregular wall; such as Figures 2-4 This is a mold used for bulging, and the equipment used is a 20000KN hydraulic press to drive the mold bulging. The bulging mold includes a lower template 1, a top plate 2, an upper template 3, an outer cone 4, an outer bulging block 5, an inner bulging block 6, and an inner cone 7. (The text repeats itself here.) Figure 3 As shown, the bulging mold is divided into 8 regions (i.e., the inner bulging block 6, the outer bulging block 5, and the inner and outer surfaces of the irregular wall are symmetrically divided into 8 regions, with a gap of 40mm between the bulging blocks), and numbered counterclockwise as Region 1, Region 2, Region 3, Region 4, Region 5, Region 6, Region 7, and Region 8. Each region includes an outer cone 4, an outer bulging block 5, an inner bulging block 6, and an inner cone 7. Regions 1, 2, 3, and 4 are symmetrical about Regions 8, 7, 6, and 5. Regions 1 and 8 correspond to surface A of the irregular wall, Regions 2 and 7 correspond to the transition surface from surface A to surface C, Regions 3 and 6 correspond to the transition surface from surface C to surface B on the irregular wall, and Regions 4 and 5 correspond to surface B on the irregular wall. T-slots are opened on the conical surfaces of the outer cone 4 and the inner cone 7. The outer bulging block 5 and the inner bulging block 6 slide relative to the outer cone 4 and the inner cone 7 through T-slot sliders to achieve inner expansion and outer clamping. The inner expansion blocks 6 in regions 3, 4, 5, and 6 are split into upper and lower parts (i.e., each inner expansion block 6 is divided into an upper half and a lower half). The top plate 2 is lifted upward from the lower template 1 by the push rod, and the inner expansion blocks 6 are fully expanded. The upper half of the inner expansion blocks 6 corresponding to regions 3, 4, 5, and 6 is removed. After the annular blank is inserted into the inner expansion blocks 6, the upper half of the inner expansion blocks 6 in regions 3, 4, 5, and 6 is installed. The hydraulic press drives the upper template 3 to move downward, and the inner expansion blocks 6 push the annular blank to expand outward until the annular blank is stuck to the outer expansion block 5. The expansion pressure is 3000KN.

[0048] Step 6: Second Cut: Cut the outer shape of the bulged ring blank on a five-axis laser cutting machine, as shown below. Figure 5The cutting template shown is placed on the laser cutting machine platform, and the symmetry point is used to align the cutting template. The cutting template adopts a key feature point frame structure, in which multiple blocks are symmetrical along the central axis. Before cutting, a model of the irregular wall needs to be established, the reference point is aligned, the program is programmed, and the program is saved. Before cutting, a low-power laser is used to etch lines on the cutting template. The correctness of the program is confirmed by comparing the etch lines with a template. Then, the accurate shape of the irregular wall is cut according to the program.

[0049] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A method for processing irregularly shaped walls of an aero-engine, wherein the irregularly shaped wall of the aero-engine includes a surface A, a surface B, and a surface C, wherein surface A is a sphere, surface B is a concave straight-walled arc surface, and surface C is a straight-walled arc surface, characterized in that: include, Step 1: Drawing and forming. Two irregular wall blanks are formed by drawing sheet metal into two irregular wall blanks using a skin drawing machine. The inner wall profile of the irregular wall blank is consistent with the inner wall profile of the aero-engine irregular wall. The profile of the drawing die is 1 / 2 of the inner wall profile after the complete inner wall profile of the aero-engine irregular wall is divided along the axial symmetry plane. Step 2: First cut: Cut along the profile of the aero-engine wall to obtain the outer contour of the aero-engine wall, and remove the burrs and remelted layer from the edge of the outer contour. Step 3: Welding. After splicing the two irregularly shaped blanks together, weld them into a ring-shaped blank. Step 4: Heat treatment to remove stress from welding and stretching of the ring-shaped blank; Step 5: Expansion forming. For the annular blank, the internal expansion and external clamping methods are used to precisely expand and form the profile of the irregular wall of the aero-engine. Step 6: Second cutting, cutting away the excess to obtain the final shape of the aero-engine irregular wall; In step 1, the forming die includes a first punch for forming surface A and surface C, and a second punch for forming surface B. The first forming process produces surface A and surface C, and the second forming process produces surface B, or the first forming process produces surface B, and the second forming process produces surface A and surface C.

2. The method for processing irregularly shaped walls of aero-engines according to claim 1, characterized in that: In step 1, the sheet material is a rectangular sheet material, and the sheet material is in a solution-treated state. The two sides of the sheet material in the width direction are flat and smooth.

3. The method for processing irregularly shaped walls of aero-engines according to claim 1, characterized in that: In step 2, a five-axis laser cutting machine is used to cut the irregular wall blank along the outer shape of the forming die to obtain the outer contour of the irregular wall of the aero-engine.

4. The method for processing irregularly shaped walls of aero-engines according to claim 1, characterized in that: In step 3, the joint of the two irregular wall blanks is polished and cleaned to ensure that the joint gap and misalignment dimensions meet the requirements.

5. The method for processing irregularly shaped walls of aero-engines according to claim 1, characterized in that: In step 3, two irregularly shaped blanks are welded using argon arc welding.

6. The method for processing irregularly shaped walls of aero-engines according to claim 1, characterized in that: In step 4, welding stress and tensile stress are relieved according to the material of the sheet metal in step 1.

7. The method for processing irregularly shaped walls of aero-engines according to claim 1, characterized in that: In step 5, during the bulging process, the profile of the aero-engine irregular wall is divided into a left profile and a right profile according to the axial symmetry plane. The left profile and the right profile are further divided into the A-side region, the transition region between the A-side and the C-side, the transition region between the C-side and the B-side, and the B-side region. Different bulging blocks are used for each region.

8. The method for processing irregularly shaped walls of aero-engines according to claim 1, characterized in that: In step 5, the mold used for bulging includes a lower template (1), a top plate (2), an upper template (3), an outer cone (4), an outer bulging block (5), an inner bulging block (6), and an inner cone (7), wherein: The top plate (2) is vertically connected to the lower template (1), and the upper end of the top plate (2) is supported on the lower end of the partial inner expansion block (6); The outer cone (4) and the inner cone (7) are fixedly connected to the lower template (1). The outer cone (4) has a first groove with the same taper on its conical surface, and the inner cone (7) has a second groove with the same taper on its conical surface. The outer expansion block (5) is slidably connected to the first slide groove by a slider, and the inner expansion block (6) is slidably connected to the second slide groove by a slider. When the upper template (3) drives the outer expansion block (5) and the inner expansion block (6) to move toward the lower template (1), the expansion surface of the outer expansion block (5) and the expansion surface of the inner expansion block (6) approach each other.

9. The method for processing irregularly shaped walls of aero-engines according to claim 1, characterized in that: In step 6, a cutting template is used in conjunction with a five-axis laser cutting machine for a second cut. The cutting template includes multiple spaced blocks that are symmetrically distributed about the axial direction of the complete inner wall surface of the aero-engine irregular wall. Each block contains a part of the characteristic surface of the aero-engine irregular wall, and the cutting template has etched lines.

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