A method for machining an asymmetric aft support ring of an aeroengine

Abstract

The application provides a processing method of an asymmetric rear support ring of an aero-engine, which can solve the problems of large part deformation, easy size deviation, complex processing tooling and long manufacturing cycle of the existing rear support ring processing method. The method comprises the following steps: blank size reinspection, reference repair, milling of the joint surface, assembly, rough turning of both ends and profile, rough milling of the inner and outer profiles, stress relief heat treatment, splitting, large end reference repair, fine milling of the longitudinal installation edge and installation hole, assembly, small end reference repair, semi-fine turning of the large end / small end, semi-fine milling of the inner / outer profile, stable treatment, fine turning of the large end / small end, fine milling of the small end, fine milling of the large end, fine milling of the large end / small end reference, fine milling of the small end hole, process platform turning, milling of the large end groove and hole, splitting, fine milling of the joint surface, marking repair, fluorescent penetration inspection and final inspection.

Description

Technical Field

[0001] This invention relates to the field of aero-engine component processing technology, specifically a processing method for an asymmetric rear support ring of an aero-engine. Background Technology

[0002] The rear support ring is a separate structural component at the rear end of the intermediate casing unit of an aero-engine. One model of the rear support ring has the following material and structural parameters: It is made of 2618 aluminum alloy, with a diameter of 1730mm, a height of 289mm, and a minimum wall thickness of 5mm. It is a typical large, thin-walled, split structural component, machined from a solution-treated and aged forged blank. The part consists of two asymmetrical semi-rings. Except for having the same radius of gyration and height, the number and position of bosses, the shape and position of elliptical windows, the distribution and size of holes, and the size and shape of slots at the top and bottom ends differ between the two semi-rings. The circumferential angles of the two semi-rings are also asymmetrical; one semi-ring extends 10mm beyond the 180° center plane on one side, while the other half has distances of 12mm and 23mm from the 180° center plane at its two ends. During assembly, the two semi-rings are connected by bolts using two connecting plates inserted between them to form a complete support ring assembly.

[0003] 2618 aluminum alloy is a heat-treatable aluminum-copper-magnesium-iron-nickel alloy. This alloy exhibits high heat resistance and good hot and cold working properties, making it suitable for manufacturing parts used at high temperatures. However, this material has a high coefficient of thermal expansion, making it prone to deformation during thin-walled machining. Furthermore, these parts are typically manufactured using ring-forged integral blanks during the R&D phase, resulting in high internal stress. During machining, due to large allowances and easy cutting, higher cutting parameters are often used to improve efficiency, generating more cutting heat and increasing machining stress. This leads to significant deformation of the parts after machining. These factors can cause serious deviations in dimensional or final form and position dimensions during subsequent processes.

[0004] For thin-walled, asymmetrical semi-ring parts like the rear support ring, a common and economical machining method is to use an integral ring forging. After rough machining, it is cut by wire EDM, and then connected with bolts to form the whole ring, similar to the machining method for split-ring parts. Finally, it is cut according to design requirements, and the cut surfaces are finished to obtain the final product. However, due to the very high internal stress of aluminum alloy ring forgings, the deformation of the part after rough machining and wire EDM is very large (the opening shrinkage can reach 40mm), and the radial shrinkage of the two semi-ring openings is not consistent. At the same time, due to differences in structure and thickness, the radial deformation of the semi-ring cutting surface along the height direction is also inconsistent. This means that the allowance left in rough machining is far from enough to cover the deformation of the part, making subsequent processes impossible and even resulting in scrap. Summary of the Invention

[0005] To address the problems of large part deformation and difficulty in ensuring dimensional accuracy in existing rear support ring machining methods, this invention provides a machining method for asymmetric rear support rings of aero-engines, in which deformation is controllable and machining accuracy meets design requirements.

[0006] The technical solution is as follows: a processing method for an asymmetric rear support ring of an aero-engine, comprising the following steps: blank processing, datum repair, rough processing, semi-finishing, and finishing. The method is characterized in that, during blank processing, the ring-shaped part is cut in half to form two semi-ring parts before subsequent processing; before rough processing, the two semi-ring parts are connected into a single ring for processing; after rough milling, the single ring formed by connecting the two semi-ring parts undergoes stress-relieving heat treatment, and then it is disassembled, repaired, and reconnected into a single ring, and a semi-finishing datum is established; during semi-finishing, processing is performed based on the semi-finishing datum.

[0007] Furthermore, it specifically includes the following steps: 1. Blank processing; the ring part is cut in half to form two semi-ring parts, each semi-ring part including a large end and a small end located at both ends, the diameter of the large end is larger than the diameter of the small end and the inner shape of the large end is stepped. 2. Re-inspect the dimensions of the blank; measure the dimensions of the semi-ring part to ensure sufficient allowance on each machined surface, and check the surface quality of the part; 3. Adjust the reference; in the free state, fit the mating surfaces of the two semi-ring parts together to form a ring shape, use the small end to position and press the step surface of the part, and machine the large end face flat for positioning. 4. Milling the mating surfaces; using the large end face for positioning, level the mating surfaces on the left and right sides, align the center of the semi-ring, press the small end of the part, rough mill the inner circle of the small end, the longitudinal mounting edge formed by the mating surface extending outward from the part, and machine the connecting holes and positioning pin holes on the longitudinal mounting edge. 5. Assembly; Use connectors to fix the two semi-ring parts together through the machined connecting holes to form a whole circular ring part; 6. Rough machining of both ends and the profile; When rough machining the small end, the large end of the assembled ring part is positioned and clamped, and the small end and the outer profile are rough machined to remove some of the excess material; When rough machining the large end, the small end of the assembled ring part is positioned and clamped, and the large end and the inner profile are rough machined to remove some of the excess material, and a process step is machined on the outer profile of the large end. 7. Rough mill the inner and outer contours; using the large end face and inner hole for positioning, press the large end process step, and rough mill the inner and outer contours; 8. Stress-relieving heat treatment: Heat treatment is performed on the assembled ring parts to remove the internal stress of the parts after rough machining; 9. Disassemble; remove the connecting parts to split the ring part into two semi-ring parts; 10. Repair the large end datum; in the free state, fit the mating surfaces of the two semi-ring parts together to form a ring shape, use the small end for positioning and pressing, and machine the large end face and positioning step. 11. Precision milling of mating surfaces; after positioning and pressing the upper surface of the large end process step with the large end end face and positioning step, precision mill the longitudinal mounting edge and the connecting holes and positioning pin holes on the longitudinal mounting edge; 12. Assembly; Use connectors to fix the two semi-ring parts together through the machined connecting holes to form a whole ring; 13. Repair the small end datum; use the large end face for positioning, press it on the upper surface of the large end process step, and after re-determine the center of the assembly, use this as the datum to precision machine the small end face and the inner circle of the small end stop. 14. Semi-finish turning of the large and small end profiles; using the small end face and the inner cylindrical surface of the stop for positioning, after semi-finish turning the large end profile, flip the part over, using the large end face and the large end inner cylindrical stop for positioning, press it from the upper surface of the large end process step, and then semi-finish turning the small end profile. 15. Semi-finish milling of inner and outer contours; using the large end face and inner hole for positioning, press the upper surface of the large end process step, and semi-finish mill the inner and outer contours; 16. Stabilization treatment: The assembled ring parts undergo stabilization heat treatment to remove internal stress after semi-finishing. 17. Finish machine the large end; use the small end face and the inner cylindrical surface of the stop for positioning, finish machine the large end and leave a certain allowance for subsequent processing, while retaining the process step of the large end; 18. Finish turn the small end; using the large end face and the inner cylindrical surface of the stop for positioning, finish turn the small end face and inner and outer circles, leaving a certain allowance for subsequent processing; 19. Finish mill the contour of the small end; using the large end face and the large end inner hole for positioning, press the upper surface of the process step, and finish mill the contour near the small end; 20. Finish mill the large end contour; turn the finished small end part over and mount it on the fixture, using the small end face and inner hole for positioning, press it along the upper side of the small end mounting edge, and finish mill the contour near the large end. 21. Refine the small end datum; using the large end face and the large end inner hole for positioning, press the upper surface of the process step, and machine the small end face and inner and outer circles to remove the excess and obtain the final dimensions; 22. Fine-tune the large end datum; use the small end face and the inner cylindrical surface of the stop for positioning, use the back of the small end mounting edge for clamping, fine-machine the large end face to ensure the overall height to the final dimension and ensure parallelism requirements, and then fine-machine the inner surface to the final dimension; 23. Mill the small end hole; use the finished large end face and inner hole for positioning, press the large end process step, provide auxiliary support for the inner shape of the part, and ensure that the runout of the small end inner circle is no more than 0.03mm before machining; 24. Machining the process table; using the small end face and the inner cylindrical surface of the stop for positioning, and using the upper surface of the small end mounting edge for clamping, precision machine the outer circle of the large end process table and the large end mounting edge profile to the final dimensions; 25. Precision milling of the large end groove and hole; 26. Disassemble; remove the connecting parts to split the ring part into two semi-ring parts; 27. Precision milling of mating surfaces; With the small end of the semi-ring part facing upwards, use the large end face and the inner hole of the thin-walled straight edge of the large end for positioning, press it tightly against the large end mounting edge and the upper surface of the large end reinforcing rib, first mill off the longitudinal mounting edge, and then precision mill the groove to the required shape and angle; 28. Trimming; removing surface defects; 29. Fluorescent penetrant inspection: Inspect the surface of the parts. If defects are found, return them to the previous process for rework and perform fluorescent penetrant inspection again. 30. Final inspection: Inspect the dimensions and surface quality of the parts to ensure they meet the requirements of the support ring design drawings and specifications.

[0008] Furthermore, in step 6, the part has a uniform allowance of A mm in the radial direction and a uniform allowance of B mm in the height direction, where A is greater than B.

[0009] Furthermore, in steps 7, 15, and 19, when milling the outer contour, an adjustable flexible auxiliary support consistent with the surface is added to the inner contour to increase the rigidity of the part; when milling the inner contour, an adjustable flexible auxiliary support is added to the outer contour of the part.

[0010] Furthermore, in step 11, a small process plane perpendicular to the large end face is machined on the part on the same machining datum. In step 13, the process planes of the two semi-rings are flattened and then centered to redetermine the center of the assembly.

[0011] Furthermore, in step 17, the height difference of the inner step at the large end is reduced to a tolerance of ±0.01mm. When precision machining the large end, the outer surface of the process step is precision machined together, leaving a certain allowance for subsequent processing.

[0012] Furthermore, in step 21, during the clamping process, the small end face is checked with a dial indicator to ensure that the clamping deformation is no greater than 0.01mm. If the deformation exceeds 0.01mm, an adjustment shim is placed on the large end face at the corresponding position to level the small end face.

[0013] The beneficial effects of this invention are as follows: by using two pre-cut semi-ring blanks, and then connecting the two semi-ring blanks into a whole ring part for processing, it is not only convenient for subsequent turning and milling, but also simplifies the structure of tooling fixtures, saves a lot of processing and tooling costs, and avoids the deformation of parts cut after rough machining of integral ring forgings; the parts are heat treated after rough milling to remove the internal stress of the parts after rough machining, reduce the deformation caused by stress release in subsequent processes, and by re-repairing the joint surfaces and connecting holes to eliminate the deformation of the previous process, the parts are reassembled and a semi-finishing datum is established for semi-finishing, so that subsequent processes have a stable and reliable datum and can be effectively transferred. Attached Figure Description

[0014] Figure 1 A schematic diagram of the overall structure of the rear support ring of an aero-engine; Figure 2 This is a front sectional view of the blank used in this invention; Figure 3 This is a schematic diagram of the reference standard for the present invention; Figure 4 This is a schematic diagram of the milled mating surface of the present invention; Figure 5 This is a schematic diagram of the assembly structure of one side of the part of the present invention; Figure 6 This is a schematic diagram of the coarse machining of the small end of the present invention; Figure 7 This is a schematic diagram of the rough machining of the large end of the present invention; Figure 8 This is a schematic diagram of the rough milling of the inner and outer shapes of the small end of the present invention; Figure 9 This is a schematic diagram of the large-end reference of the present invention; Figure 10 This is a schematic diagram of the precision milling of the longitudinal mounting edge and end face holes of the present invention; Figure 11 This is a schematic diagram of the little-endian reference of the present invention; Figure 12 This is a schematic diagram of the semi-finished machining of the large end of the present invention; Figure 13 This is a schematic diagram of the semi-finished small end of the present invention; Figure 14 This is a schematic diagram of the semi-finish milling of the inner and outer shapes of the present invention; Figure 15 This is a schematic diagram of the precision machining of the large end of the present invention; Figure 16 This is a schematic diagram of the precision machining of the small end of the present invention; Figure 17 This is a schematic diagram of the precision milling of the small end contour of the present invention; Figure 18 This is a schematic diagram of the precision milling of the large end contour of the present invention; Figure 19This is a schematic diagram of the precision little-endian reference of the present invention; Figure 20 This is a schematic diagram of the precision machining reference of the small end of the present invention; Figure 21 This is a schematic diagram of the precision milling of the small end hole according to the present invention; Figure 22 for Figure 21 A diagram showing the view from below; Figure 23 This is a schematic diagram of the precision machining table for the large end of the present invention; Figure 24 Schematic diagram of milling large end groove; Figure 25 This is a schematic diagram of the cross-section of the milled large end groove; Figure 26 This is a schematic diagram of the precision milling mating surface. Detailed Implementation

[0015] A method for machining an asymmetric rear support ring for an aero-engine, which is used to machine such as Figure 1 The asymmetric rear support ring of the aero-engine shown is shown. Figure 1 In the diagram, 1-small end mounting edge; 2-large end mounting edge; 3-elliptical hole; 4-large end process mounting edge; 5-large end groove; 6-large end reinforcing rib; 7-groove plane; 8-square boss; 9-outer countersunk hole; 10-square hole periphery boss; 11-square hole; 12-large end inner screw hole; 13-inner small round boss; 14-small end groove. Specifically, it includes the following steps: 1. Blank processing; the ring-shaped part is cut in half to form two semi-ring parts. Each semi-ring part includes a large end and a small end located at both ends. The diameter of the large end is larger than the diameter of the small end, and the inner shape of the large end is stepped.

[0016] 2. Re-inspection of blank dimensions; measure the dimensions of the semi-ring part to ensure sufficient allowance on each machined surface, and check the surface quality of the part. There should be no forging defects such as slag inclusions, porosity, cracks, or overlaps. The blank structure should be as follows: Figure 2 As shown, Figure 2 The shape of the dashed line in the mid-section represents the cross-sectional shape of the semi-finished product processed by the rear support ring machine.

[0017] 3. Adjust the reference; in the free state (unlike when fixed together with connectors, the free state is simply splicing and pasting together), fit the mating surfaces of the two semi-ring parts together to form a ring shape, using the small end for positioning and pressing the step surface A of the part, and then machine the large end face flat for positioning, such as... Figure 3 As shown in the figure, similar to the following figures, the bolded part in the figure indicates the processing position of this step.

[0018] 4. Milling the mating surfaces; using the large end face for positioning, level the mating surfaces on the left and right sides, align the center of the semi-ring, and then tighten the small end of the part. Figure 4Rough milling is performed on the longitudinal mounting edge 15 extending outward from the part, and connecting holes 16 and locating pin holes are machined on the longitudinal mounting edge 15. Then, the inner circle of the small end is milled with the same axial reference for alignment in the next process.

[0019] 5. Assembly: Use connectors to fix the two semi-ring parts together through the machined connecting holes to form a complete circular ring. Specifically, place the parts flat on the work platform with the large end facing down. First, install four locating pins 17, then use six connecting bolts 18 to assemble the two semi-rings into a complete circular ring. Figure 5 As shown.

[0020] 6. Rough turning of both ends and the profile; When rough turning the small end, use a high-speed rail and four-jaw chuck to position and clamp the large end of the assembled ring part. Rough turn the small end and the outer profile on a CNC lathe, removing some excess material, such as... Figure 6 As shown. Then flip the part over, supporting it with the small end face against the high-speed rail, and clamp it with the outer circle of the small end using a four-jaw chuck. Rough-machine its large end and inner surface, remove some excess material, and machine the large end process step 19 on the outer surface of the large end, as shown. Figure 7 The part is shown in bold. Considering that the radial deformation of the part tends to be large while the axial deformation is small in subsequent processes, a uniform allowance of 6mm is made in the radial direction and a uniform allowance of 4mm is made in the height direction.

[0021] 7. Rough mill the inner and outer contours; using the large end face and inner hole for positioning, press the large end process step, and rough mill the inner and outer contours. Specifically, add an adjustable flexible auxiliary support consistent with the profile surface on the inner contour to increase the rigidity of the part. Figure 8 Rough mill the outer contour of the part on a five-axis machining center (rough mill the bosses, holes, etc. on the contour surface); then remove the inner support, add an adjustable flexible auxiliary support to the outer contour of the part, and rough mill the inner contour; the rough milling of the outer contour retains the same machining allowance (6mm) as the rough turning process.

[0022] 8. Stress-relieving heat treatment: In order to remove the internal stress of the parts after rough machining and reduce the deformation caused by stress release in subsequent processes, the parts are subjected to stress-relieving heat treatment in an air furnace after rough milling; in order to prevent excessive deformation of the parts during the heat treatment process, the parts are put into the furnace for heat treatment in an assembled state.

[0023] 9. Disassemble; remove the connecting bolts and locating pins of the parts to separate the ring part into two semi-ring parts.

[0024] 10. Repair the large end datum; in the free state, fit the mating surfaces of the two semi-ring parts together to form a ring shape, position and press the small end on the machine tool table, and machine the large end face and positioning step, such as... Figure 9 As shown.

[0025] 11. Precision milling of the mating surfaces; after positioning and clamping the upper surface of the large-end process step using the large-end end face and positioning step, precision mill the longitudinal mounting edge and the connecting holes and positioning pin holes on the longitudinal mounting edge on a five-axis machining center, such as... Figure 10 As shown; to facilitate the alignment of the two semi-ring centers during machining, a small process plane for alignment is milled on the part on the same datum (for example, in the 90° direction of the large end, i.e., parallel to the section joint surface of the support ring).

[0026] 12. Assembly: Place the part flat on the work platform with the large end facing down. First, install 4 positioning pins, and then use 8 connecting bolts to assemble the two half rings into a whole circular ring structure.

[0027] 13. Repair the small end datum; Due to the significant deformation caused by previous stress relief (including heat treatment stress relief), and the offset of the part center after precision milling of the mating surface, coupled with the inconsistent deformation of the two semi-rings, the amount of allowance to be removed during milling of the mating surface differs. After assembly, a new part center needs to be established using the small process plane machined on the large end mounting edge during milling, providing a reliable datum for subsequent processes. Specifically, the large end face is used for positioning, and the surface of the large end process step is pressed tightly. After re-determining the center of the assembled part, this is used as the datum to precision machine the small end face and the inner circle of the small end stop, ensuring the flatness of the end face and the roundness of the inner circle in the free state. Figure 11 As shown. The method for redetermining the center of the assembly can be achieved by using the aforementioned process planes, flattening the process planes at the large ends of the two semi-rings, and then centering them.

[0028] 14. Semi-finish turning of the large and small end profiles; the main purpose of the semi-finish turning process is to eliminate deformation of the assembled parts and further remove excess material from the blank. Using the small end face and the inner cylindrical surface of the stop at 20mm for positioning, semi-finish turn the large end profile, leaving a uniform allowance of 2mm on the profile. Figure 12 As shown in bold lines. Then flip the part over, positioning it using the large end face and the large end inner circle stop 21. Clamp it from the upper surface of the large end process step, and semi-finish machine the small end profile (with a uniform 2mm allowance on the profile). Strictly control the overall height and the inner hole size of the positioning stop circle, as detailed below. Figure 13 The section shown in bold is the part shown.

[0029] 15. Semi-finish milling of inner and outer contours; using the large end face and inner hole for positioning, clamp the upper surface of the large end process step, and semi-finish mill the inner and outer contours; specifically, use an adjustable flexible auxiliary device to support the inner contour surface to increase part rigidity, reduce machining vibration, improve surface quality, and reduce machining deformation. Leave a uniform allowance of 2mm on the contour surface for semi-finish milling of the outer contour; after the outer contour is completed, remove the inner contour support, and use an adjustable flexible auxiliary device to support the outer contour surface on the milled outer contour surface. Leave a uniform allowance of 2mm on the contour surface for semi-finish milling of the inner contour, as detailed below. Figure 14 As shown.

[0030] 16. Stabilization treatment: Due to the large size of the parts, the parts are stabilized in an air furnace. The internal stress of the parts is removed by heat treatment at a lower temperature in the assembled state, while keeping the size of the assembled parts small.

[0031] 17. Finish machine the large end; use the small end face and the inner cylindrical surface of the stop for positioning, according to... Figure 15 The large end profile is precision machined. For part positioning, the process boss structure is retained at the large end, with a 1mm allowance on the end face and inner profile. To ensure reliable positioning during milling, the height difference of the inner profile step is reduced to a tolerance of ±0.01mm to facilitate clamping of the milling fixture. To facilitate part alignment after clamping, the outer surface B of the small cylinder at the lower end of the process step is also precision machined, with a 1mm allowance until the final finishing of the large end.

[0032] 18. Finish machine the small end; using the large end face and the inner cylindrical surface of the stop for positioning, according to... Figure 16 The small end face and inner and outer circles are precision machined, and the overall height of the part and the inner hole size of the positioning circle are strictly controlled; preferably, the machining length of the small end outer circle should exceed the thickness of the longitudinal mounting edge by 2mm.

[0033] 19. Finish mill the small end contour; using the large end face and large end inner hole for positioning, press the upper surface of the process step, and finish mill the contour near the small end; specifically, to increase the rigidity of the part, reduce the vibration of the milling tool, and improve the surface quality of the machined part, add an adjustable flexible auxiliary support to the inner conical surface. First, finish mill the square boss 8 and the square hole periphery boss 10, and then finish mill the outer conical surface to the final size and smoothly connect the tool with the rounded corners around the boss. This can greatly improve the efficiency of finishing milling the conical surface. Since the longitudinal mounting edge is only used for process connection, it will be cut off in the final process to form two side slots. When finishing milling the outer shape, it is not necessary to finish mill the longitudinal mounting edge again. When finishing milling the outer conical surface, it is advisable to exceed the width of the final slot plane 7 by about 5mm; then finish mill the elliptical hole 3 and the square hole 11 to the final size. Note that the elliptical hole requires asymmetrical tolerance, and programming should be based on the middle difference value; finally, finish mill the lower side of the small end mounting edge 1 to ensure the thickness of the upper mounting edge, and finish mill the upper surface of the large end mounting edge 2 to ensure the height difference between the upper and lower mounting edges. After machining the outer shape, remove the inner auxiliary support. Evenly install flexible, adjustable auxiliary supports on the outer conical surface. First, precision mill a ring of small circular bosses around the upper part of the inner conical surface, then precision mill the upper half of the inner conical surface. Specifically... Figure 17 As shown, the lower part of the conical surface and the lower side of the boss are placed in the finish milling process of the large end.

[0034] 20. Finish mill the large end contour; flip the finished small end part over and mount it on the fixture, using the small end face and inner hole for positioning, and press it along the upper side of the small end mounting edge. Finish mill the contour near the large end; specifically, first finish mill the upper ring of inner small round bosses 13 on the inner conical surface, then finish mill the inner square bosses 10 around the square hole and the corresponding square bosses 8, and then finish mill the upper half of the inner conical surface to ensure the final wall thickness requirement and flush with the root of the previously machined bosses, as detailed below. Figure 18 As shown. Dividing the internal shape into two processing steps allows for direct machining by the machine tool spindle, which simplifies programming (avoids the use of bent parts), improves processing efficiency, and results in more regular and consistent machining patterns and better surface quality.

[0035] 21. Fine-tune the small end datum; using the large end face and inner hole for positioning, clamp the upper surface of the process step, and machine the small end face and inner and outer circles to remove excess material and obtain the final dimensions. Specifically, during the clamping process, check with a dial indicator that the clamping deformation should not exceed 0.01mm (small end deformation). If the deformation exceeds 0.01mm, appropriate adjusting shims need to be placed on the corresponding large end face area to prevent the part from springing back after the part is machined and the fixture is released, affecting the flatness and roundness of the machined small end. During machining, leave a 0.15mm allowance on the inner circle and end face initially, and remove the excess material with the last cut to obtain the final dimensions, ensuring good surface quality, flatness, and roundness. A machining diagram is shown below. Figure 19 As shown.

[0036] 22. Fine-tune the large end datum; using the small end face and the inner cylindrical surface of the stop for positioning, and using the back of the small end mounting edge for clamping, fine-machine the large end face to ensure the overall height reaches the final dimension and ensures parallelism requirements. Then, fine-machine the inner profile to the final dimension to facilitate subsequent hole machining. A machining diagram is shown below. Figure 20 As shown. The allowance on the outer side of the process step is retained to enhance positioning stability.

[0037] 23. Finish mill the small end hole; using the finished large end face and inner hole for positioning, tighten the large end process step, and provide auxiliary support for the inner shape of the part. Adjust the adjusting bolts according to the part's surface position to achieve reliable support. After aligning the small end's inner circle runout to no more than 0.03mm, drill and ream the small hole on the small end mounting edge 1 and mill the threaded hole on the large end mounting edge 2. Then, finish mill the outer countersunk hole 9, the through hole on the square hole peripheral boss 10, and the large hole on the square boss 8. Finally, finish mill the groove plane 7 and machine the connecting hole 16 on the connecting plane to the required size. The width of the finish-milled connecting plane is consistent with the width of the conical surface machined during finish milling of the outer shape. The machining diagram is shown below. Figure 21 , Figure 22 As shown.

[0038] 24. Machining the process table; positioning is done using the small end face and the inner cylindrical surface of the stop, and clamping is performed using the upper surface of the small end mounting edge. Figure 23The outer diameter of the large end mounting edge 4 and the large end mounting edge profile are precision machined to the final size. The focus is on ensuring the wall thickness of the thin edge of the process table and the height of the mounting edge. After machining, the part is transferred to the next process with the fixture.

[0039] 25. Milling the large end groove and hole: Mount the fixture with the part on the machine tool, align the part, first mill the inner screw hole 12 of the large end, then mill the asymmetrical large end groove near the longitudinal mating surface, and finally mill the positioning stud hole on the bottom surface of the large end groove. A machining diagram is shown below. Figure 24 and Figure 25 As shown.

[0040] 26. Disassemble; Remove the longitudinal mounting edge positioning pins and connecting bolts, and disassemble the entire ring part into two halves so that the groove areas can be machined separately later.

[0041] 27. Precision milling of the mating surfaces; With the small end of the semi-ring part facing upwards, use the large end face and the inner hole of the thin-walled straight edge of the large end for positioning. Over-positioning can be used on the lower surface of the large end reinforcing rib 6 to enhance positioning stability (over-positioning support blocks are added to both ends of the groove). Press firmly against the large end mounting edge (specifically, its inclined surface) and the upper surface of the large end reinforcing rib 6. First, mill off the longitudinal mounting edge, then precision mill the groove to the required shape and angle. A machining diagram is shown below. Figure 26 As shown.

[0042] 28. Fitting and repair; fitters remove burrs from milling parts and surface defects such as scratches and indentations; then mark the parts with a vibrating pen in a designated area for traceability identification.

[0043] 29. Fluorescent penetrant inspection: Inspect all machined surfaces of the parts for defects such as cracks; if defects are found, return to the previous process for rework and perform fluorescent penetrant inspection again.

[0044] 30. Final inspection: Inspect the dimensions and surface quality of the parts to ensure they meet the requirements of the support ring design drawings and specifications.

[0045] The rear support ring machining method of this invention uses two pre-cut semi-ring blanks. By reasonably adjusting and designing the circumferential distribution of the two asymmetrical upper / lower rear support rings, and adding two longitudinal process mounting edges, the two semi-ring blanks are connected into a whole ring part for machining. This not only facilitates subsequent turning and milling machining, simplifies the structure of tooling fixtures, and saves significant machining and tooling costs, but also avoids the deformation of parts cut after rough machining of integral ring forgings. This method reserves a process step during rough machining of the large end, strengthens the rigidity of the large end, and facilitates the clamping and positioning of the part during subsequent rough milling, semi-finish turning, semi-finish milling, finish milling, and finish turning, making the part machining more convenient and efficient. After rough milling, the part undergoes heat treatment to fully deform the rough-machined semi-finished part. By re-repairing the mating surfaces and connecting holes, the deformation from the previous process is eliminated, and the parts are reassembled and machined to establish a semi-finishing datum, providing a stable and reliable datum for subsequent processes and enabling effective transfer of data. At the same time, the distribution of the allowance for semi-finishing and finishing is reasonably arranged to effectively reduce the machining deformation during the finishing process, which greatly improves the final machining accuracy of the parts and ensures that the parts meet the drawing requirements and the assembly requirements of the components.

[0046] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for processing an asymmetric rear support ring for an aero-engine, comprising the following steps: The process of blank machining, datum repair, rough machining, semi-finishing, and finishing is characterized in that, during blank machining, the ring-shaped part is cut in half to form two semi-ring-shaped parts before subsequent machining; before rough machining, the two semi-ring-shaped parts are connected into a whole ring-shaped part for machining; after rough milling, the whole ring-shaped part formed by connecting the two semi-ring-shaped parts is subjected to stress-relieving heat treatment; then it is disassembled, repaired, and reconnected into a whole ring-shaped part and a semi-finishing datum is established; during semi-finishing, machining is performed based on the semi-finishing datum. The parts to be processed are two thin-walled semi-ring parts with an asymmetrical structure; Specifically, it includes the following steps:

1. Blank processing; the ring part is cut in half to form two semi-ring parts. The semi-ring parts include a large end and a small end located at both ends. The diameter of the large end is larger than the diameter of the small end and the inner shape of the large end is stepped.

2. Re-inspect the dimensions of the blank; measure the dimensions of the semi-ring part to ensure sufficient allowance on each machined surface, and check the surface quality of the part; 3. Adjust the reference; in the free state, fit the mating surfaces of the two semi-ring parts together to form a ring shape, use the small end to position and press the step surface of the part, and machine the large end face flat for positioning. Unlike those that are fixed together with connectors, the free state is simply a matter of piecing them together; 4. Milling the mating surfaces; using the large end face for positioning, level the mating surfaces on the left and right sides, align the center of the semi-ring, press the small end of the part, rough mill the inner circle of the small end, the longitudinal mounting edge formed by the mating surface extending outward from the part, and machine the connecting holes and positioning pin holes on the longitudinal mounting edge.

5. Assembly; Use connectors to fix the two semi-ring parts together through the machined connecting holes to form a whole circular ring part; 6. Rough machining of both ends and the profile; When rough machining the small end, the large end of the assembled ring part is positioned and clamped, and the small end and the outer profile are rough machined to remove some of the excess material; When rough machining the large end, the small end of the assembled ring part is positioned and clamped, and the large end and the inner profile are rough machined to remove some of the excess material, and a process step is machined on the outer profile of the large end.

7. Rough mill the inner and outer contours; using the large end face and inner hole for positioning, press the large end process step, and rough mill the inner and outer contours; 8. Stress-relieving heat treatment: Heat treatment is performed on the assembled ring parts to remove the internal stress of the parts after rough machining; 9. Disassemble; remove the connecting parts to split the ring part into two semi-ring parts; 10. Repair the large end datum; in the free state, fit the mating surfaces of the two semi-ring parts together to form a ring shape, use the small end for positioning and pressing, and machine the large end face and positioning step.

11. Precision milling of mating surfaces; after positioning and pressing the upper surface of the large end process step with the large end end face and positioning step, precision mill the longitudinal mounting edge and the connecting holes and positioning pin holes on the longitudinal mounting edge; 12. Assembly; Use connectors to fix the two semi-ring parts together through the machined connecting holes to form a whole ring; 13. Repair the small end datum; use the large end face for positioning, press it on the upper surface of the large end process step, and after re-determine the center of the assembly, use this as the datum to precision machine the small end face and the inner circle of the small end stop.

14. Semi-finish turning of the large and small end profiles; using the small end face and the inner cylindrical surface of the stop for positioning, after semi-finish turning the large end profile, flip the part over, using the large end face and the large end inner cylindrical stop for positioning, press it from the upper surface of the large end process step, and then semi-finish turning the small end profile.

15. Semi-finish milling of inner and outer contours; using the large end face and inner hole for positioning, press the upper surface of the large end process step, and semi-finish mill the inner and outer contours; 16. Stabilization treatment: The assembled ring parts undergo stabilization heat treatment to remove internal stress after semi-finishing.

17. Finish machine the large end; use the small end face and the inner cylindrical surface of the stop for positioning, finish machine the large end and leave a certain allowance for subsequent processing, while retaining the process step of the large end; 18. Finish turn the small end; using the large end face and the inner cylindrical surface of the stop for positioning, finish turn the small end face and inner and outer circles, leaving a certain allowance for subsequent processing; 19. Finish mill the contour of the small end; using the large end face and the large end inner hole for positioning, press the upper surface of the process step, and finish mill the contour near the small end; 20. Finish mill the large end contour; turn the finished small end part over and mount it on the fixture, using the small end face and inner hole for positioning, press it along the upper side of the small end mounting edge, and finish mill the contour near the large end.

21. Refine the small end datum; using the large end face and the large end inner hole for positioning, press the upper surface of the process step, and machine the small end face and inner and outer circles to remove the excess and obtain the final dimensions; 22. Fine-tune the large end datum; use the small end face and the inner cylindrical surface of the stop for positioning, use the back of the small end mounting edge for clamping, fine-machine the large end face to ensure the overall height to the final dimension and ensure parallelism requirements, and then fine-machine the inner surface to the final dimension; 23. Mill the small end hole; use the finished large end face and inner hole for positioning, press the large end process step, provide auxiliary support for the inner shape of the part, and ensure that the runout of the small end inner circle is no more than 0.03mm before machining; 24. Machining the process table; using the small end face and the inner cylindrical surface of the stop for positioning, and using the upper surface of the small end mounting edge for clamping, precision machine the outer circle of the large end process table and the large end mounting edge profile to the final dimensions; 25. Precision milling of the large end groove and hole; 26. Disassemble; remove the connecting parts to split the ring part into two semi-ring parts; 27. Precision milling of mating surfaces; With the small end of the semi-ring part facing upwards, use the large end face and the inner hole of the thin-walled straight edge of the large end for positioning, press it tightly against the large end mounting edge and the upper surface of the large end reinforcing rib, first mill off the longitudinal mounting edge, and then precision mill the groove to the required shape and angle; 28. Trimming; removing surface defects; 29. Fluorescent penetrant inspection: Inspect the surface of the parts. If defects are found, return them to the previous process for rework and perform fluorescent penetrant inspection again.

30. Final inspection: Inspect the dimensions and surface quality of the parts to ensure they meet the requirements of the support ring design drawings and specifications; In step 11, a small process plane perpendicular to the large end face is machined on the part on the same machining datum. In step 13, the process planes of the two semi-rings are flattened and then centered to redetermine the center of the assembly.

2. The method for processing an asymmetric rear support ring for an aero-engine according to claim 1, characterized in that: In step 6, the part is uniformly left with a margin of A mm in the radial direction and a uniform margin of B mm in the height direction, where A is greater than B.

3. The method for processing an asymmetric rear support ring for an aero-engine according to claim 1, characterized in that: In steps 7, 15, and 19, when milling the outer contour, an adjustable flexible auxiliary support consistent with the surface is added to the inner contour to increase the rigidity of the part; when milling the inner contour, an adjustable flexible auxiliary support is added to the outer contour of the part.

4. The method for processing an asymmetric rear support ring for an aero-engine according to claim 1, characterized in that: In step 17, the height difference of the inner step at the large end is reduced to a tolerance of ±0.01mm. When precision machining the large end, the outer surface of the process step is precision machined together, leaving a certain allowance for subsequent processing.

5. The method for processing an asymmetric rear support ring for an aero-engine according to claim 1, characterized in that: Step 21: During the clamping process, check the small end face with a dial indicator to ensure that the clamping deformation is no more than 0.01 mm. If the deformation exceeds 0.01 mm, place an adjusting shim on the large end face at the corresponding position to level the small end face.

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