A method for manufacturing an aircraft engine diffuser

Abstract

This invention discloses a method for machining an aero-engine diffuser, comprising: clamping a fixture on a vertical lathe; aligning the fixture's positioning stop with the machine tool's table rotation center; and fixing the fixture on the machine tool. With the diffuser's large end facing down, place the outer circle of its large end flange within the fixture's positioning stop, and then fix the diffuser onto the fixture. Install upper and lower end-face turning tools and align the tool holders. Perform tool setting, with the zero points of both the upper and lower end-face turning tools set on the tool setting groove end face of the fixture. Machin the lower end face of the heat shield from bottom to top, with axial feed, ensuring dimension H1. Machin the upper end face from top to bottom, with axial feed, ensuring dimension H2. This invention's machining method is simple, ensures the quality of diffuser machining, and improves machining efficiency compared to laser cutting.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically relating to a machining method for an aero-engine diffuser. Background Technology

[0002] Aircraft engine diffuser (see) Figure 1 This is a typical large, thin-walled part with a double-layer structure. The part has a maximum diameter of 1200mm and a height of approximately 720mm. It is assembled from components such as the diffuser outer wall 1, heat shield 2, bow-shaped frame 3, nut 4, and bolt 5. After the diffuser is assembled, the upper and lower end faces of the heat shield 2 need to be machined to ensure dimensions H1 and H2. H1 represents the vertical distance from the lower end face of the heat shield 2 to the lower end face of the diffuser outer wall 1, and H2 represents the vertical distance from the upper end face of the heat shield 2 to the lower end face of the heat shield 2.

[0003] The current processing method involves using a five-dimensional laser cutting machine, which requires a long clamping and auxiliary time. Before processing, a laser cutting protection device needs to be installed on the inner wall of the diffuser's outer wall. If the laser cutting protection device is not properly installed, the outer wall of the diffuser will be burned during laser cutting, resulting in scrap and inconsistent processing quality. At the same time, the molten slag produced by laser cutting adheres to the heat shield and is difficult to remove. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention aims to provide a processing method for aero-engine diffusers. This method is simple to operate, ensures processing quality, and improves processing efficiency.

[0005] The present invention adopts the following technical solution:

[0006] A method for manufacturing an aero-engine diffuser, the diffuser including an outer wall, an inner side of which is a heat shield, and flange edges provided on the outer surfaces of both axial ends of the outer wall. The outer wall and the heat shield are assembled to form a double-layer structure. The manufacturing method includes the following steps.

[0007] Step 1: Install the fixture with the positioning stop on the vertical lathe. Align the positioning stop on the fixture with the rotation center of the worktable of the vertical lathe, and then fix the fixture on the vertical lathe.

[0008] Step 2: Place the diffuser with the larger outer diameter end facing down, and place the flange edge corresponding to the larger outer diameter end into the positioning stop of the fixture, and then fix the diffuser on the fixture.

[0009] Step 3, install the end face turning tool, including installing the upper end face turning tool for machining the upper end face of the heat insulation screen on the left side of the machine tool spindle and leveling the tool holder, and installing the lower end face turning tool for machining the lower end face of the heat insulation screen on the right side of the machine tool spindle and leveling the tool holder. The vertical distance from the end of the lower end face turning tool to the axis of the machine tool spindle is greater than the vertical distance from the end of the upper end face turning tool to the axis of the machine tool spindle.

[0010] Step 4: Tool setting. The zero point for setting both the upper and lower face turning tools is set at the same position on the fixture.

[0011] Step 5: Machin the lower end face of the heat insulation screen from bottom to top, with the feed direction being axial, to ensure that the dimension H1 is met;

[0012] Step 6: Machin the upper surface of the heat insulation screen from top to bottom, with the feed direction being axial, to ensure that the dimension H2 is met.

[0013] Furthermore, in step 1, the fixture includes,

[0014] The base is a disc structure. Multiple evenly distributed threaded holes and bolt holes are provided on the upper surface of the base along the circumferential direction. The upper surface of the base is also provided with a positioning stop for quick positioning of the flange edge and a tool setting groove for tool setting. An avoidance step is provided on the inner side of the positioning stop.

[0015] The pressure plate and screws are connected to the threaded hole by the screws. The threaded hole, which is connected to the screw and the pressure plate, is used to fix the diffuser to the fixture, and the bolt hole is used to fix the fixture to the machine tool table.

[0016] Furthermore, in step 3, the upper and lower face turning tools are carbide indexable turning tools. These tools have chip breaker grooves, a cutting edge length of 15–18 mm, a rake angle of 4°–5°, a clearance angle of 2°–3°, and a cutting edge inclination angle of 0°. It should be noted that indexable turning tools refer to tools where the insert is mechanically clamped to the tool holder, allowing for direct replacement of the insert when the tool becomes worn and unusable.

[0017] Furthermore, in step 3, a dial indicator is used to level the tool holder of the upper end face turning tool and the machine tool spindle, as well as the tool holder of the lower end face turning tool and the machine tool spindle.

[0018] Furthermore, in step 3, the lower end face turning tool is connected to the machine tool spindle via an extended tool holder. The extended tool holder includes a square block and a clamping part. The square block is connected to the machine tool spindle, and there is a groove on the clamping part. The tool shank of the lower end face turning tool is detachably connected in the groove.

[0019] Furthermore, in steps 5 and 6, when the machining reaches the dimensions H1 and H2, the feed of the upper and lower end face cutting tools is paused for a period of time to machine the end face.

[0020] Compared with the prior art, the present invention has the following characteristics:

[0021] (1) The present invention uses a fixture with a positioning stop to clamp the diffuser, which is simple to operate and has a short clamping time. After the fixture is aligned, the part (diffuser) does not need to be aligned again.

[0022] (2) The present invention designs an extended tool post to expand the machining range of the lathe and realize the machining of the upper and lower end faces of the heat insulation screen in one clamping of the diffuser, which has high machining efficiency. At the same time, the long cutting edge end face turning tool is used to overcome the problems of large circumferential runout of the heat insulation screen (the heat insulation screen is not on a circle) and unstable machining quality. The cutting edge of the long cutting edge end face turning tool can cover the entire heat insulation screen.

[0023] (3) Since the diameters of the two ends of the diffuser axis are inconsistent (one large and one small), it is easier to process when the smaller diameter end is clamped upwards to avoid tool vibration. If the machine tool spindle is moved directly for turning, the spindle will interfere with the small end. In order to avoid interference between the machine tool spindle and the inner wall of the upper end of the heat shield, an extended tool holder is adopted.

[0024] (4) Compared with milling, turning is more efficient. When milling two end faces, it takes 60 minutes to process one end face, while turning only takes 5 minutes. Therefore, milling cannot meet production needs. In addition, if milling two end faces is used, it is not only necessary to clamp twice to complete the process, but also the auxiliary clamping time is long, and the milling cutter wears out quickly, resulting in high cost.

[0025] (5) The outer wall of the diffuser and the heat shield are connected by screws to form a double-layer structure. When laser cutting is used in the traditional way, protection is required to avoid burning the outer wall of the diffuser during cutting, which would result in scrap. The processing efficiency is low and cannot meet the production needs. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the diffuser structure in this invention;

[0027] Figure 2 This is a schematic diagram of the clamping of the upper and lower end face turning tools in this invention;

[0028] Figure 3 This is a schematic diagram of the extended tool holder structure in this invention;

[0029] Figure 4 This is a schematic diagram of the tool path for machining the lower end face in this invention;

[0030] Figure 5 This is a schematic diagram of the tool path for machining the upper end face in this invention;

[0031] Figure 6 This is a schematic diagram of the clamp structure of the present invention;

[0032] In the diagram: 1. Diffuser outer wall; 2. Heat shield; 3. Bow-shaped frame; 4. Nut; 5. Bolt; 6. Machine tool spindle; 7. Extended tool post; 8. Lower end face turning tool; 9. Upper end face turning tool; 10. Fixing bolt. Detailed Implementation

[0033] 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.

[0034] like Figure 1 As shown, in order to ensure that the vertical distance H1 from the lower end face of the heat shield 2 to the lower end face of the diffuser outer wall 1, and the vertical distance H2 from the upper end face of the heat shield 2 to the lower end face of the heat shield 2 meet the design requirements, the present invention provides a processing method for an aero-engine diffuser.

[0035] like Figures 2-6 As shown, a method for machining an aero-engine diffuser involves clamping the diffuser onto a CNC vertical lathe using a fixture. An upper end-face cutting tool 9 and a lower end-face cutting tool 8 are simultaneously mounted on the machine tool spindle 6. The lower end face of the heat shield 2 is machined first, followed by the upper end face, with the tool feed direction aligned with the diffuser's axial direction. Figure 6 The fixture includes a base, a pressure plate, and screws. The base is a disc structure with multiple evenly distributed threaded holes and bolt holes in the circumferential direction. A positioning stop is provided at the upper end of the base for quick positioning of the parts. A tool setting groove is provided at the upper end of the base for easy tool setting. An avoidance step is provided inside the positioning stop to prevent the tool bar from interfering with the worktable when machining the heat shield on the lower end face, so that the upper and lower end faces of the heat shield 2 can be machined in one clamping of the diffuser.

[0036] The specific processing method for aircraft engine diffusers includes the following steps:

[0037] (1) Mount the fixture on the vertical lathe, align the fixture positioning stop with the rotation center of the machine tool table, and then fix the fixture on the lathe.

[0038] (2) Clamp the part, with the larger outer diameter end of the diffuser facing down, and place the outer circle of the flange edge on the outer surface of the larger outer diameter end inside the positioning stop of the fixture, and then fix the diffuser on the fixture.

[0039] (3) Install the face turning tool. Mount the upper face turning tool 9, used for machining the upper surface of the heat insulation screen 2, on the left side of the machine tool spindle 6. Use a dial indicator to level the tool holder of the upper face turning tool 9. Mount the lower face turning tool 8, used for machining the lower surface of the heat insulation screen 2, on the right side of the machine tool spindle 6 via the extended tool holder 7. Use a dial indicator to level the tool holder of the lower face turning tool 8. Figure 3 The extended tool holder 7 has a square end, which is clamped to the machine tool spindle 6 by fixing bolts 10. The other end is a clamping part with a straight groove for holding the tool shank of the lower end face turning tool 8. Three screws are provided on one side of the straight groove to fix the tool shank of the lower end face turning tool 8. Both the upper end face turning tool 9 and the lower end face turning tool 8 are carbide indexable turning tools. The turning tools have chip breaking grooves, a cutting edge length of 15-18mm, a rake angle of 4°-5°, a clearance angle of 2°-3°, and a cutting edge inclination angle of 0°.

[0040] (4) Tool setting: The tool setting zero points of the upper end face turning tool 9 and the lower end face turning tool 8 are both set on the tool setting groove end face of the fixture.

[0041] (5) Machining the lower end face of the heat insulation screen 2 from bottom to top, with the feed direction being the diffuser axis. The speed of the machine tool spindle 6 is 8-10 rpm, and the feed rate is 0.05-0.08 mm / rpm. When the theoretical size (i.e., theoretical size H1) is reached, the feed is paused for 5-10 seconds to facilitate the flattening of the end face and ensure size H1.

[0042] (6) Machining the upper end face of the heat insulation screen 2 from top to bottom, with the feed direction being the diffuser axial machining. The speed of the machine tool spindle 6 is 8 to 10 revolutions per minute, and the feed rate is 0.05 to 0.08 mm / revolution. When the theoretical size (i.e., theoretical size H2) is reached, the feed is paused for 5 to 10 seconds to facilitate machining the end face and ensure size H2.

[0043] 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 an aero-engine diffuser, the diffuser comprising a diffuser outer wall (1), an inner side of the diffuser outer wall (1) being a heat shield (2), flange edges being provided on the outer surfaces of both axial ends of the diffuser outer wall (1), and the diffuser outer wall (1) and the heat shield (2) forming a double-layer structure after assembly, characterized in that: The processing method includes the following steps: Step 1: Install the fixture with the positioning stop on the vertical lathe. Align the positioning stop on the fixture with the rotation center of the worktable of the vertical lathe, and then fix the fixture on the vertical lathe. Step 2: Place the diffuser with the larger outer diameter end facing down, and place the flange edge corresponding to the larger outer diameter end into the positioning stop of the fixture, and then fix the diffuser on the fixture. Step 3, install the end face turning tool, including installing the upper end face turning tool (9) for machining the upper end face of the heat insulation screen on the left side of the machine tool spindle (6) and leveling the tool bar, and installing the lower end face turning tool (8) for machining the lower end face of the heat insulation screen on the right side of the machine tool spindle (6) and leveling the tool bar. The vertical distance from the end of the lower end face turning tool (8) to the axis of the machine tool spindle (6) is greater than the vertical distance from the end of the upper end face turning tool (9) to the axis of the machine tool spindle (6). The lower end face turning tool (8) is connected to the machine tool spindle (6) through the extension tool holder (7). The extension tool holder (7) includes a square block and a clamping part. The square block is connected to the machine tool spindle (6). There is a groove on the clamping part. The tool bar of the lower end face turning tool (8) is detachably connected in the groove. Step 4, tool setting: the zero point of the upper end face turning tool (9) and the lower end face turning tool (8) are both set at the same position on the fixture; Step 5: Machin the lower end face of the heat insulation screen (2) from bottom to top, with the feed direction being axial, to ensure that the dimension H1 is met; Step 6: Machin the upper surface of the heat insulation screen (2) from top to bottom, with the feed direction being axial, to ensure that the dimension H2 is met.

2. The processing method of an aero-engine diffuser according to claim 1, characterized in that: In step 1, the fixture includes, The base is a disc structure. Multiple evenly distributed threaded holes and bolt holes are provided on the upper surface of the base along the circumferential direction. The upper surface of the base is also provided with a positioning stop for quick positioning of the flange edge and a tool setting groove for tool setting. An avoidance step is provided on the inner side of the positioning stop. A pressure plate and screws, wherein the pressure plate is connected to a threaded hole by screws.

3. The processing method of an aero-engine diffuser according to claim 1, characterized in that: In step 3, the upper end face turning tool (9) and the lower end face turning tool (8) are carbide indexable turning tools. The turning tools are equipped with chip breaking grooves, the cutting edge length is 15-18mm, the rake angle is 4°-5°, the clearance angle is 2°-3°, and the cutting edge inclination angle is 0°.

4. The processing method of an aero-engine diffuser according to claim 1, characterized in that: In step 3, a dial indicator is used to level the tool holder of the upper end face turning tool (9) and the machine tool spindle (6), as well as the tool holder of the lower end face turning tool (8) and the machine tool spindle (6).

5. The processing method of an aero-engine diffuser according to claim 1, characterized in that: In steps 5 and 6, when the machining reaches the dimensions H1 and H2, the feed of the upper end face cutting tool (9) and the lower end face cutting tool (8) is paused for a period of time to machine the end face.

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