Machining method for three-petal type stator machining assembly with two-stage blades of aero-engine

Abstract

The invention provides a machining method for a three-petal type stator machining assembly with two-stage blades of an aero-engine. The machining method can solve the problems that the two-stage blades in a three-petal type stator are difficult to machine, parts are large in deformation after spraying and combined machining, and the shape and position sizes such as the blade profile tolerance, the flow channel profile tolerance and the concentricity of assembly parts at the front end and the rear end of the stator are out of tolerance. The method comprises the following steps of blank inspection, rough turning of an inner shape and an outer shape, rough milling of an outer shape, milling, finish milling, clamp trimming, finish trimming, finish turning, finish milling, finish turning, inspection, spraying, turning of a large-end coating, turning of a small-end coating, grinding of a blade tip, clamp trimming of a mark, fluorescent penetrant inspection and final inspection. The method is characterized in that: The working procedures between the outer shape rough milling step and the inspection step specifically comprise segmentation, stress relief heat treatment, joint surface and hole milling, grinding, combination, benchmark trimming, two end and inner shape fine turning, outer shape finish milling, splitting, blade shape finish milling, clamp trimming, combination, large end benchmark fine trimming, small end finish turning, small end lace and hole finish milling and large end finish turning. .

Description

Technical Field

[0001] The invention relates to the technical field of aircraft engine parts processing, in particular to a processing method for a three-petal stator machine assembly with two-stage blades of an aircraft engine. Technical Background

[0002] The three-petal stator machine assembly is an important structural part in the supercharger stage of a certain type of aircraft engine. It is made of 17-4Ph precipitation hardened stainless steel, with a diameter of 360mm, a height of 152mm, and a minimum wall thickness of 1.2mm. The outer mold has three layers of thin-walled reinforcement ribs and 12 evenly distributed mounting bosses. The small end mounting edge has lace and 15° inclined holes, and the large end is a thin-walled cylindrical structure without mounting edges; the inner mold has two stages (63 and 66 blades each) of stator blades, and three sections of aluminum silicon-polyester coating are sprayed on the flow channel. It is a typical small thin-walled complex structural part. The solid solution + aging full-ring forging blank is used for processing. The part is an evenly divided three-petal structure, and each petal inner mold is distributed with two stages (containing 21 and 22 blades respectively). It is positioned by three longitudinal mounting edges through locating pins and connected to form a full-ring stator through connecting bolts.

[0003] 17-4Ph stainless steel is a precipitation-hardened stainless steel with copper added. The alloy has high strength, hardness and good corrosion resistance, and relatively good processing performance. Through reasonable cutting parameters and tool selection, efficient and accurate cutting can be achieved; in addition, the material can be further improved through heat treatment, cold working and other means. It is widely used in the processing of aircraft engine parts and turbine blades.

[0004] However, because the wall thickness of the three-petal stator machine component itself is very thin, the part only has a mounting edge at the small end and a thin-walled cylindrical structure at the large end. In addition, the three longitudinal mounting edge joint surfaces evenly distributed along the circumference destroy the balance of the whole ring structure of the part. The stress distribution of the part at the joint surface and nearby areas is quite different from that in other areas, reflecting poor structural rigidity and stability; in addition, such parts are basically made of integral blanks by ring forging during the research and development stage, and there is large stress inside the blank; the blank has a large allowance, and the cutting force and cutting heat will be relatively large, resulting in large processing stress. After processing, there will be large deformation, resulting in changes in the overall roundness of the part, including the roundness of the reference circle, and the corresponding flow channel and blade contours and hole position will be affected, which may easily cause subsequent processes to be unable to be processed or the shape and position dimensions to be seriously out of tolerance, and even directly affect the assembly of the component or reduce the performance of the unit body and cause it to be scrapped. Summary of the invention

[0005] The three-petal stator machine plus component itself has a very thin wall thickness, the part has only a mounting edge at the small end and the large end is a thin-walled cylinder, and the three longitudinal mounting edge joint surfaces evenly distributed along the circumference destroy the balance of the whole ring structure of the part. The stress distribution of the part at the joint surface and the surrounding area is quite different from that in other areas, reflecting poor structural rigidity and stability. In addition, this type of part adopts an integral blank forged by ring forging, and there is a large stress inside, which makes the subsequent process unable to be processed or the shape and position dimensions are seriously out of tolerance, and even directly affects the assembly of the component or reduces the performance of the unit body and causes scrapping. The present invention provides a processing method for a three-petal stator machine plus component with two-stage blades for an aircraft engine. The process arrangement is reasonable, the deformation in the processing process is controllable, the final size and shape and position tolerances are guaranteed, and the structural rigidity and stability are good.

[0006] The technical solution is as follows: It includes the following steps: rough turning of inner and outer shapes → rough milling of outer shapes → milling → fine milling → clamp repair → fine repair → fine turning → fine milling → fine turning → inspection → spraying → turning of big end coating → turning of small end coating → grinding of blade tip → clamp repair and marking → fluorescent penetration inspection → final inspection, and is characterized in that the process between the rough milling of outer shapes and the inspection steps is specifically cutting → stress relief heat treatment → milling of joint surfaces and holes → grinding → assembly → repair of datum → fine turning of both ends and inner shapes → fine milling of outer shapes → splitting → fine milling of blade shapes → clamp repair → assembly → fine repair of big end datum → fine turning of small end → fine milling of small end lace and holes → fine turning of big end.

[0007] It is further characterized by: The cutting: using wire cutting to cut the whole ring rough milling workpiece into three evenly distributed 120° sector segments; The stress relief heat treatment: the parts are subjected to stress relief heat treatment using an air furnace to fully release the internal stress of rough processing.

[0008] The milling of the joint surface and hole: locate the large end face and inner hole, find the symmetry center of the fan-shaped segment, mill the inner and outer planes of the joint surface and process the joint hole surface, and at the same time mill out the small end positioning inner circle (see attached Figure 6 Benchmark B).

[0009] The grinding: grinding the joint surface to ensure the flatness, contour and surface connection requirements.

[0010] The assembly is positioned by a process positioning pin, and the three-petal rough-machined sector segments are combined into an integral circular ring member by connecting bolts; The said large end repairing reference: using the small end for positioning, flattening the large end end surface and outer circle for positioning in the next process; The said fine turning of the two ends and the inner profile: fine turning of the end faces and the inner profile of the two ends, uniforming of the two ends, the inner profile flow channel and the blade contour margin, and establishing a single-petal processing positioning reference, by fine turning the two ends to establish the reference, the single petal blade profile and flow channel milling processing to ensure the contour accuracy of the blade profile and the flow channel; The described fine milling of the exterior: using the longitudinal installation edge to find the correct angle, fine milling the longitudinal installation edge of the exterior, the rib plate, the outer side surface of the flow channel and the boss to the final size.

[0011] The splitting: splitting the whole ring part into three separate sector segments; The precision milling of the blade profile: positioning by the small end face and the inner circle, precision milling the two-stage blades and the flow passages in the root area of ​​the blade profile to the final contour; The repair includes repairing the blade tip burrs, the fillet of the blade root and the knife marks in the flow channel area, and polishing the blade surface.

[0012] The assembly is positioned by a process positioning pin, and the three-petal rough-machined sector segments are combined into an integral circular ring member by connecting bolts; The said finishing big end reference: positioning with the small end, flattening the big end end surface and outer circle for positioning in the next process; The small end is finely turned: the large end face and the outer cylindrical surface are used for positioning, the small end face and the inner flow channel are finely turned, and the spraying receiving groove is finely turned; The precision milling of the small end lace and the outer mounting seat hole: positioning with the large end face and the outer cylindrical surface, precision milling of the small end face lace, the end face oblique hole, the boss threaded hole on the outer contour, etc.; and precision milling of the precision bolt positioning hole on the longitudinal mounting edge; The large end is finely turned: the small end face and the inner circle stop are used for positioning, the large end face and the inner flow channel are finely turned, and the spraying receiving groove is finely turned.

[0013] The blank inspection: measure the size of the ring forging blank, check the blank surface quality, mark and forging material report to see if they meet the forging drawing and specification requirements; Rough turning of the inner and outer shapes: Rough turning of the two ends and the inner and outer contours to efficiently remove the blank excess; The rough milling of the outer shape: positioning and clamping with the inner blade contour, rough milling of the outer rib plate and the longitudinal installation edge contour; The inspection includes intermediate inspection and fluorescent penetrant inspection. The intermediate inspection: in the state of full ring, the constraints are carried out according to the constraints allowed by the design, and the three-coordinate inspection is used to detect the internal and external contour dimensions and form and position tolerances; the fluorescent penetrant inspection: overall inspection of all processed surfaces of the parts to see if there are cracks and other linear display defects; The spraying: spray the flow channel area according to the technical requirements of the parts, and pay attention to ensuring the minimum spraying thickness; The spray coating on the big end is positioned by the end face of the small end and the stop circle, and the coating of the two layers of the flow channel area of ​​the big end is fine-turned to the final size and aligned with the milled flow channel; The spray coating on the small end is positioned by the end face of the large end and the outer cylindrical surface, and the coating on the flow channel area of ​​the small end is fine-turned to the final size and aligned with the milled flow channel; The blade tip grinding: positioning by the small end face and the stop circle, grinding the letter line contour of the blade tip of the two-stage blade to ensure the contour degree requirements of the blade tip parent and child lines; The said clamp repair marking: the clamp worker removes the burrs on the blade tip, smoothly transfers the clamp repair coating area to the milled hub surface, and marks it according to the product design requirements; The fluorescent penetrant inspection: a local fluorescent penetrant inspection is performed on the machined area after the intermediate inspection; The final inspection: final inspection of parts surface quality, marking, size and geometric tolerances.

[0014] The three-petal stator machined assembly is cut and processed after rough milling and then split to perform fine milling of the joint surface and holes, thereby eliminating deformation of the parts after rough machining and ensuring the flatness and surface profile requirements of the 120° joint surface.

[0015] When milling the joint surface and the hole, only the technical hole is processed for assembly, and when fine milling the outer shape, the installation positioning hole is combined and bored to ensure the position consistency of the assembly hole.

[0016] A 0.5mm margin is left on the surface of the flow channel for spraying, and the entire flow channel is machined after spraying to ensure smoothness of the flow channel.

[0017] The two-stage blade tip allowance of the three-petal stator machined assembly is ground after fine turning and coating to ensure that the blade tip meets the profile requirement of the reference.

[0018] The beneficial effects of the present invention are as follows: through overall rough turning, rough milling, cutting, and heat treatment to relieve stress, the structure of the parts limits the processing of the blade profile to be separated into three petals for separate processing; after the parts are cut, there are stress and deformation, so firstly heat treatment is carried out to relieve stress, then the joint surface and positioning circle are repaired again and then reassembled to re-establish the benchmark, and the inner fine turning and outer fine milling are completed, and then the parts are disassembled to respectively perform fine milling of the blade profile on the three-petal fan-shaped segments, and then they are combined for fine repair, fine turning, milling of lace and holes, etc.; then the whole ring assembly is sprayed, and in order to prevent the coating from tearing after subsequent disassembly and resulting in an incomplete joint surface, the three-petal casing connecting bolts are loosened, and a 1mm thick pad is placed between the joint surfaces and then the connecting bolts are tightened for overall spraying. After the spraying is completed, the coating is turned, the blade tip is ground, and local fluorescence is performed, so the entire process only has one cutting, two combinations, and one splitting. During the disassembly process, the deformation of the parts is controllable, the influence of the benchmark conversion on the shape and position tolerance of important features is small, the final size and shape and position tolerance are guaranteed, and the structural rigidity and stability are good. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of a three-petal stator assembly with two-stage blades for an aircraft engine; Figure 2 It is a main cross-sectional view of the blank used in the present invention; Figure 3 This is a schematic diagram of the rough-turned exterior of the present invention; Figure 4 This is a schematic diagram of the rough milling appearance of the present invention; Figure 5 It is a schematic diagram of wire cutting of the present invention; Figure 6 This is a schematic diagram of the milling joint surface of the present invention; Figure 7 It is a schematic diagram of the grinding bonding surface of the present invention; Figure 8 This is a schematic diagram of the combination of the present invention; Fig. 9 This is a schematic diagram of the refinement of the big end reference of the present invention; Fig.10 This is a schematic diagram of the small end of the thin car of the present invention; Fig.11 This is a schematic diagram of the large end of the thin car of the present invention; Fig.12 This is a schematic diagram of the fine milling of the external rib plate of the present invention; Fig.13 This is a schematic diagram of the semi-finished milled external boss mounting seat of the present invention; Fig.14 This is a schematic diagram of the fine milling longitudinal installation edge of the present invention; Fig.15 This is a schematic diagram of the fine milling blade profile of the present invention; Fig.16 This is a schematic diagram of the refinement of the big end reference of the present invention; Fig.17 This is a schematic diagram of the fine turning small end of the present invention; Fig.18 This is a schematic diagram of the fine milling of the small end lace of the present invention; Fig.19 This is a schematic diagram of the precision milling joint surface of the present invention; Fig. 20 This is a schematic diagram of the precision milling of the side wall hole of the present invention; Fig.21 This is a schematic diagram of the fine turning big end of the present invention; Fig. 22 It is a schematic diagram of spraying of the present invention; Fig.23 This is a schematic diagram of the coating on the small end of fine turning; Fig.24 This is a schematic diagram of the coating on the large end of the precision ruler; Fig.25 This is a schematic diagram of grinding the blade tip; Figure markings: 1-longitudinal mounting edge; 2-process bolt; 3-side wall mounting seat; 4-annular rib plate; 5-belly wall of casing; 6-small end mounting edge; 7-large end cylinder; 8-front stage blade; 9-flow channel; 10-rear stage blade; 11-spray layer. DETAILED DESCRIPTION

[0020] The invention discloses a processing method for a three-petal stator machine assembly with two-stage blades of an aero-engine, which comprises the following steps: rough inspection→rough turning of inner and outer shapes→rough milling of outer shapes→cutting→stress relief heat treatment→milling of joint surfaces and holes→grinding→assembly→repairing of datum→fine turning of two ends and inner shapes→fine milling of outer shapes→splitting→fine milling of blade shapes→clamp repair→assembly→fine repair of large end datum→fine turning of small end→fine milling of small end lace and holes→fine turning of large end→intermediate inspection→fluorescent penetrant inspection→spraying→turning of large end coating→turning of small end coating→grinding of blade tip→clamp repair of marking→fluorescent penetrant inspection→final inspection.

[0021] Cutting: Use wire cutting to cut the entire ring of rough milled workpiece into three evenly distributed 120° sector segments.

[0022] Stress relief heat treatment: Use an air furnace to perform stress relief heat treatment on parts to fully release the internal stress of rough machining.

[0023] Milling joint surface and hole: locate the large end face and inner hole, find the symmetry center of the fan-shaped segment, mill the inner and outer planes of the joint surface and process the joint hole, and mill out the small end positioning inner circle at the same time (see attached Figure 6 Benchmark B).

[0024] Grinding: Grind the mating surface to ensure flatness, contour and surface connection requirements.

[0025] The assembly is positioned by process positioning pins, and the three-petal rough-machined sector segments are assembled into an integral circular ring part by connecting bolts; Repair the big end reference: use the small end for positioning, and flatten the big end end face and outer circle for positioning in the next process; Fine turning of both ends and inner profile: Fine turning of both ends and inner profile, homogenization of both ends, inner profile flow channel and blade contour allowance, and establishment of single-petal machining positioning reference, by fine turning both ends to establish the reference, single-petal blade profile and flow channel milling to ensure the contour accuracy of blade profile and flow channel; Finish milling of the exterior: Use the longitudinal installation edge to find the correct angle, and finish mill the longitudinal installation edge, rib plate, outer side surface of the flow channel and boss to the final size.

[0026] Split: Split the full ring part into three separate sectors; Fine milling of blade profile: positioning by the small end face and inner circle, fine milling of the two-stage blades and the flow channel in the root area of ​​the blade profile to the final contour; Repair: Repair the burrs on the blade tip, the fillet on the blade root and the knife marks in the flow channel area, and polish the blade surface.

[0027] The assembly is positioned by process positioning pins, and the three-petal rough-machined sector segments are assembled into an integral circular ring part by connecting bolts; Fine-tune the big end reference: use the small end for positioning, flatten the big end end face and outer circle for positioning in the next process; Fine turning of small end: positioning by the large end face and the outer cylindrical surface, fine turning of the small end face and the inner flow channel, fine turning to form a spraying receiving groove; Fine milling of the small end lace and the outer mounting seat hole: positioning with the large end face and the outer cylindrical surface, fine milling of the small end face lace, the end face oblique hole, the boss threaded hole on the outer contour, etc.; and fine milling of the precision bolt positioning hole on the longitudinal mounting edge; Finish turning the big end: Position with the small end face and the inner circle stop, finish turning the big end face and the inner flow channel, and finish turning to form a spray-fitting groove.

[0028] Blank inspection: Measure the dimensions of the ring forging blank, check the surface quality, marking and forging material report of the blank to see if they meet the forging drawing and specification requirements; Rough turning of inner and outer shapes: Rough turning of both ends and inner and outer contours to efficiently remove the blank excess; Rough milling of the exterior: positioning and clamping based on the inner blade profile, rough milling of the outer rib plate and longitudinal installation edge profile; The inspection includes intermediate inspection and fluorescent penetrant inspection. The intermediate inspection: in the state of full ring, the constraints are carried out according to the constraints allowed by the design, and the three-coordinate inspection is used to detect the internal and external contour dimensions and form and position tolerances; the fluorescent penetrant inspection: overall inspection of all machined surfaces of the parts to see if there are cracks and other linear display defects; Spraying: Spray the flow channel area according to the technical requirements of the parts, and pay attention to ensuring the minimum spraying thickness; Turn the spray coating on the big end: Position it with the end face and stop circle of the small end, finish turn the coating of the two layers of flow channel area on the big end to the final size and align it with the milled flow channel; Turning the spray coating on the small end: Positioning with the large end face and the outer cylindrical surface, finish turning the coating on the small end flow channel area to the final size and aligning it with the milled flow channel; Blade tip grinding: Positioning by the small end face and the stop circle, grinding the letter line contour of the two-stage blade tip to ensure the contour requirements of the blade tip parent and child lines; Bench repair and marking: Bench workers remove burrs on blade tips, smoothly connect the bench repair coating area with the milled hub surface, and mark according to product design requirements; Fluorescent penetrant inspection: Conduct local fluorescent penetrant inspection on the machined area after intermediate inspection; Final inspection: Final inspection of parts surface quality, marking, dimensions, geometric tolerances, etc.

[0029] The three-petal stator machined assembly is cut and processed after rough milling and then split to perform fine milling of the joint surface and holes, thereby eliminating part deformation after rough machining and ensuring the flatness and surface profile requirements of the 120° joint surface.

[0030] When milling the joint surface and the hole, only the technical hole is processed for assembly, and when fine milling the outer shape, the installation positioning hole is combined and bored to ensure the position consistency of the assembly hole.

[0031] A 0.5mm margin is left on the surface of the flow channel for spraying, and the entire flow channel is machined after spraying to ensure smoothness of the flow channel.

[0032] The two-stage blade tip allowance of the three-petal stator machined assembly is ground after fine turning and coating to ensure that the blade tip meets the profile requirements of the reference.

[0033] The specific processing method of the present invention is described below in conjunction with the accompanying drawings. Figures 1 to 20 , which comprises the following steps: Step 1, blank inspection: Check the size of the ring forging blank to ensure that it meets the requirements of the forging blank drawing; check the surface quality of the blank, and there should be no forging defects such as slag inclusions, cracks, and defects; check whether the mark on the blank is consistent with the relevant traceability information on the certificate; check whether the material report attached to the blank is qualified. Figure 2 As shown, Figure 2 The dotted outline inside the center section line represents the cross-sectional shape of the finished three-opening stator; Step 2: Rough turn the big end and the small end: On the CNC vertical lathe, support one end face of the blank, position the outer circle of the blank, clamp the outer circle with the clamping jaws, rough turn the small end, leave 4mm along the overall contour of the part, and quickly remove most of the excess of the blank; then turn the part over and turn the outer circle of the big end to size, and finally flush the end face of the big end, such as Figure 3 As shown; Step 3, rough milling shape: Center with the inner circle of the large end, axially locate and press with the plane contour of the previous blade, use the five-axis machining center to rough mill the part shape, mill out three longitudinal mounting edges 1, annular ribs 4 and all mounting bosses 3 (all features are uniformly left 4mm), such as Figure 1 and Figure 4 As shown; Step 4, cutting: Align the rotation center of the part, align the two side faces of any longitudinal installation edge to determine the cutting angle, use the slow wire cutting machine to evenly cut the part into three-petal fan-shaped segments along the bisector of the longitudinal installation edge. After cutting, check whether the wall thickness of the longitudinal installation edge is consistent. Figure 5 As shown; Step 5, stress relief heat treatment: Place the three-petal fan-shaped segment with the small end free on the heat treatment tray, and perform stress relief heat treatment on the three-petal fan-shaped segment parts within a certain range of temperature within the material annealing temperature to eliminate the stress generated after rough machining and material removal. At the same time, let the three-petal parts fully release the forging stress after cutting in a free state, reduce the deformation caused by stress in subsequent processes, and thus ensure the final processing accuracy of the parts; Step 6, fine mating surface and mounting holes on the mating surface: center with the inner circle of the large end, perform axial positioning and pressing with the plane contour of the previous blade, use the five-axis CNC machining center to fine mill the 120° mating surface to ensure the flatness and contour requirements; mill the end face flat and mill out the inner circle countersunk hole of the small end to establish an axial reference for subsequent processes and ensure that the three-petal fan-shaped segments form a consistent center of circle after being combined into a complete annular casing; mill the back of the longitudinal mounting edge mating surface to facilitate the connection bolt installation during assembly; mill the mating surface hole to ensure the position requirements with the reference, ensure the smooth combination of the three-petal fan-shaped segments to prevent the influence of clamping deformation on the dimensional accuracy of the parts; as follows Figure 6 shown.

[0034] Step 7, grinding the joint surface: Grind the 120° sector-shaped joint surface plane milled in step 6 on the grinding platform to ensure the flatness requirements, and use the coloring method to check the ground surface to ensure that the joint surface coloring is continuous and uninterrupted and the coloring area is greater than 90%; Figure 7 shown.

[0035] Step 8, assembly: Place the three-petal fan-shaped segment flat on a clean workbench with the small end facing downward, install the process positioning bolt 2 into the connection hole on the longitudinal mounting edge 5, assemble the three-petal fan-shaped segment parts into a complete ring casing, and tighten the bolts according to the specified torque, such as Figure 8 As shown; Step 9, repair the big end reference: use the small end face formed by the combination to locate, press the small end installation edge, flatten the big end face and the upper surface of the rear blade for positioning and pressing in the next process. Fig. 9 As shown; Step 10, fine turning of the small end and the large end: fine turning is to re-establish the part reference based on the circle formed by the combination of the inner arc segments of the three-petal fan-shaped segments processed by milling. On the one hand, it eliminates the misalignment and deformation of the inner and outer shapes after the three-petal casing is combined, and on the other hand, it evenly removes the excess; when fine turning the small end, it supports the large end face of the part and is positioned with the outer circle of the large end. The small inner and outer contours of the part are semi-finished, and the surface is evenly left with an excess of 1mm. Considering that the deformation of the subsequent process has little effect on the spraying area, it is processed to the final size in this process, such as Fig.10 As shown in the bold outline in the figure; turn the part over, support the small end face of the part, locate it with the small end outer circle, semi-finish the large end contour of the part, and leave a uniform allowance of 1mm on the surface. The coating area is also processed to the final size, as shown in the figure below: Fig.11 The outline shown in the bold line part; Step 11, fine milling of the exterior: support the end face of the large end of the part, position it with the outer cylindrical surface of the large end, use the small end positioning plate to center the small end reference circle to ensure the concentricity of the upper and lower ends, and press from the small end face, fine mill the external annular rib plate 4, the belly wall of the casing 5, the side wall boss mounting seat 3 and the longitudinal mounting edge 1 to the final size. When fine milling the longitudinal mounting edge, it is necessary to remove a process bolt and reinstall it after the processing is completed, and then remove the next spiral to continue processing; leave a margin on the end face of the boss to prevent deformation in subsequent processes to provide margin for compensation, and wait for the final processing of the fine hole process; see the attached for details Fig.12 , Attachment Fig.13 And attached Fig.14 ; Step 12, disassembly: remove the positioning process bolts and connecting bolts on the longitudinal installation edge, disassemble the stator casing into three independent fan-shaped segments, and properly store the process bolts for the next assembly; Step 13, fine milling of the blade profile: place the part reference C end (sector segment joint surface) close to the positioning block on the left side of the fixture, and position the small end reference hole against the fixture positioning ring, and surround and constrain the part from the overall appearance, fix the sector stator segment reliably on the fixture and keep it concentric with the center of the fixture, and fine mill the two-stage stator blades and flow channels to ensure the blade profile and flow channel surface profile. Because the blades are small and dense, the distance between the blades is relatively small, and the surface profile of the blades is required to be relatively high, the company's more mature technology is used to process the blade profile by the rough and fine mixed milling solution of the integral blade disc blade. Because the two-stage blades are on the inside of the casing, and the two-stage blades are misaligned with each other, affecting the axial feed of the tool, the processing can only be fed in the radial direction of the part and milled along the blade profile. During milling, the fixture needs to remain open in the 120° sector segment inner area to prevent interference. For details, see the attached Fig.15 .

[0036] Step 14, repair by clamping: repair the radial processing marks of the inlet and outlet edges and the chamfered area of ​​the blade root, polish and repair the local defects of the fillet of the inlet and outlet edges, and polish and repair the flow channel surface to make it smoothly transition with other areas to meet the blade acceptance requirements; Step 15: Assemble: Assemble the three-petal stator segment according to the same requirements as step 8.

[0037] Step 16, repair the big end reference: Position the small end face and inner circle stop formed by the combination, press from the small end installation edge, and machine and flatten the big end face and outer cylindrical surface to establish a reliable positioning reference for the next process of fine turning, such as Fig.16 As shown; Step 17, precision turning of the small end: when clamping, support the end face of the large end of the part, and use the large end outer circle 7 for positioning. Use a special pressing plate to press the small step on the upper side of the outer cylinder. After aligning the small end reference inner circle, precision turn the small end face, reference inner circle and step to the final size to ensure the form and position tolerance requirements such as roundness and verticality. In order to ensure the needs of subsequent positioning and dimensional control, the reference circle diameter tolerance is appropriately compressed; the parts in this process do not need to be removed from the fixture, and the fixture can be transferred to the next process together with the parts, which can reduce clamping deformation and alignment deviation, and is beneficial to improving product quality. Specific examples Fig.17 Indicated by bold lines; Step 18, precision milling of the small end lace and side wall holes: After aligning the end face and reference circle of the part, tighten the clamp, install a slip-fit ​​limit pressure plate on the small end reference circle and end face, support the inner circle of the small end of the part and axially press the lower end, which is beneficial to enhance the rigidity of the small end and reduce deformation caused by milling the lace. First mill the lace on the small end 6 and then mill the inclined hole on the end face. Subsequently, remove the process bolts 2 on the left and right sides of the uppermost layer of the longitudinal mounting edge 1, process the longitudinal mounting edge holes and the countersunk table surface, install new process bolts after processing, and then process the remaining three rows of mating surface surfaces according to the above steps. Finally, process the boss end face and boss hole to the requirements of the drawing. As shown in the attached figure Fig.18 , Attachment Fig.19 And attached Fig. 20 As shown; Step 19, fine turning the big end: the runout of the positioning surface of the alignment fixture is no more than 0.01, the small end 1 end face and inner circle are used as the reference for positioning, and the inclined surface on the upper side of the small end installation edge is pressed tightly, and the big end end face is fine turned to ensure the total height, and the big end outer circle 7 is fine turned to ensure the diameter and coaxiality requirements. In order to eliminate the influence of part deformation on roundness and coaxiality after spraying, the big end outer circle 7 is left with 0.3mm in the final processing of the coating process. Fig.21 As shown; Step 20, intermediate inspection: Inspect all diameter dimensions and form and position tolerances in the full ring state, and rework the out-of-tolerance dimensions before circulation; Step 21, Fluorescent penetrant inspection: Conduct an overall fluorescent penetrant inspection on the entire surface of the stator assembly and the blade surface to check whether there are cracks and linear defects beyond the tolerance standard on the machined surface of the parts; Step 22, spraying: Place a 1mm process gasket on the joint surface of the longitudinal installation edge and tighten the process bolts again. Spray the three areas of the flow channel area according to the spraying process requirements in the state of the whole ring part to ensure the minimum spraying thickness requirements; after spraying, loosen the process bolts, remove the process gasket, and re-install the parts with the process bolts. Fig. 22 As shown; Step 23, turn the small end coating: Position with the large end face and the large end outer cylindrical surface, press from the small end face, align the small end face and the reference inner circle, turn the secondary blade (a layer of coating near the small end), and ensure the surface profile requirements of the coating and the flow channel area; to prevent the coolant from corroding the coating, turn off the coolant when turning the coating. Fig.23 As shown; Step 24, turn the coating on the big end: Align the fixture positioning surface, position it with the small end face and the reference inner circle stop, press it from the inclined surface on the upper side of the small end, and finish turn the two layers of coating on the big end to ensure the surface profile requirements of the coating and the flow channel area; in order to prevent the coolant from corroding the coating, it is not allowed to use coolant for cooling when turning the coating. Fig.24 As shown; Step 25, grinding the blade tip: Align the fixture positioning surface, position it with the small end face and the reference inner circle stop, press it from the inclined surface on the upper side of the small end, and grind the blade tip on a CNC grinder to ensure the blade tip sub-line profile requirements. Because the blade is thin and has poor rigidity, it is easy to cause the knife to vibrate when worn, and the grinding surface is relatively rough. After testing, the green corundum grinding wheel can be used to grind to obtain better surface quality. Fig.25 As shown; Step 26, repair and mark: Repair and remove surface defects such as scratches, indentations, and joints on the parts; laser mark the part traceability information in the designated area according to the drawing requirements.

[0038] Step 27, Fluorescent penetrant inspection: Conduct local fluorescent penetrant inspection on the machined surface and blade tip formed by the stator assembly coating to check whether there are cracks and linear defects beyond the tolerance standard on the machined surface of the parts; Step 28, Final Inspection: Conduct full-size inspection on parts to verify whether the product can fully meet the requirements of the customer's design drawings.

[0039] The three-petal stator machining component processing method of the present invention innovatively adopts the rough processing of the whole ring forging blank, cuts it into three petals, fine mills the joint surface and the connecting hole, combines the datum repair and fine milling the appearance, splits the fan-shaped segment structure into single petals to process the blade shape, and then combines the process scheme of processing the precision surface and all holes and other precision features. The process route is relatively simple, and the datum conversion remains continuous and consistent. The precision five-axis machining center is used to clamp and process the 120-degree fan-shaped segment joint surface and the joint surface positioning hole, the axial positioning end face of the part and the inner circle of the positioning stop at one time, ensuring that the intersection line of the joint surface of the three-petal fan-shaped segment coincides with the center of the positioning arc, and then ensuring that the center of the positioning arc of the three-petal stator after assembly is the same, forming a standard full circle and using it as the positioning circle for datum conversion and transmission to the subsequent process; the precision mounting hole of the joint surface is formed by combined processing during the final fine milling of the small end and the side wall hole, which on the one hand ensures that the position of the precision mounting hole relative to the datum is qualified, and on the other hand ensures that the position of the holes on the two halves of the mounting edge is consistent, which is beneficial to the assembly of the stator component and reduces assembly Deformation; after the datum is fine-turned to the final size, spraying, fine-turning coating, and finally grinding the blade tip, which not only eliminates the influence of deformation that may be caused by spraying on the surface contour of the blade tip, but also makes the datum consistent, which is conducive to ensuring that the contours of key features such as the blade shape, blade tip and flow channel remain consistent and all qualified; except for the fine milling of the joint surface and the blade shape processing process, all processes of the entire scheme are processed by the overall ring structure, the tooling structure is simple, the manufacturing difficulty is not high, the tooling cost is low and can meet the needs of mass production, and it has good process economy; the blade shape processing tooling adopts fan-shaped positioning cylinder centering and uses one side of the joint surface for angular positioning, so that the fan-shaped area with its inner side pointing to the center of the circle remains in a fully open state, which is conducive to radial feed for blade milling; the outside of the part adopts a fully enclosed support limit plate, and the small end mounting edge and the large end cylindrical surface of the part are fully constrained, so that the positioning of the part is stable and reliable, the rigidity of the stator casing is strengthened, and the blade shape will not be deformed during processing, ensuring that the surface contour of the blade shape and the flow channel at the root of the blade are qualified.

Claims

1. A method for machining a three-petal stator machine assembly with two-stage blades for an aircraft engine, comprising the following steps: Blank inspection → rough turning of inner and outer shapes → rough milling of outer shapes → milling → fine milling → clamp repair → fine repair → fine turning → fine milling → fine turning → inspection → spraying → turning of big end coating → turning of small end coating → grinding of blade tip → clamp repair and marking → fluorescent penetration inspection → final inspection, characterized in that: the process between the rough milling of outer shapes and the inspection steps is specifically cutting → stress relief heat treatment → milling of joint surfaces and holes → grinding → assembly → repair of datum → fine turning of both ends and inner shapes → fine milling of outer shapes → splitting → fine milling of blade shapes → clamp repair → assembly → fine repair of big end datum → fine turning of small end → fine milling of small end lace and holes → fine turning of big end.

2. The method for machining a three-petal stator assembly of an aircraft engine with two-stage blades according to claim 1, characterized in that: The cutting: using wire cutting to cut the whole ring rough milling workpiece into three evenly distributed 120° sector segments; The stress relief heat treatment: using an air furnace to perform stress relief heat treatment on the parts to fully release the internal stress of rough processing; The milling of the joint surface and hole: positioning with the large end face and the inner hole, aligning the symmetry center of the fan-shaped segment, milling the inner and outer planes of the joint surface and processing the joint surface hole, and milling out the small end positioning inner circle at the same time; The grinding: grinding the joint surface to ensure the flatness, contour and surface connection requirements.

3. The method for machining a three-petal stator assembly of an aircraft engine with two-stage blades according to claim 1 or 2, characterized in that: The assembly is positioned by a process positioning pin, and the three-petal rough-machined sector segments are combined into an integral circular ring member by connecting bolts; The said large end repairing reference: using the small end for positioning, flattening the large end end surface and outer circle for positioning in the next process; The said fine turning of the two ends and the inner profile: fine turning of the end faces and the inner profile of the two ends, uniforming of the two ends, the inner profile flow channel and the blade contour margin, and establishing a single-petal processing positioning reference, by fine turning the two ends to establish the reference, the single petal blade profile and flow channel milling processing to ensure the contour accuracy of the blade profile and the flow channel; The described fine milling of the exterior: using the longitudinal installation edge to find the correct angle, fine milling the longitudinal installation edge of the exterior, the rib plate, the outer side surface of the flow channel and the boss to the final size.

4. The method for machining a three-petal stator assembly of an aircraft engine with two-stage blades according to claim 3, characterized in that: The splitting: splitting the whole ring part into three separate sector segments; The precision milling of the blade profile: positioning by the small end face and the inner circle, precision milling the two-stage blades and the flow passages in the root area of ​​the blade profile to the final contour; The repair includes repairing the blade tip burrs, the fillet of the blade root and the knife marks in the flow channel area, and polishing the blade surface.

5. The method for machining a three-petal stator assembly with two-stage blades of an aircraft engine according to claim 4, characterized in that: The assembly is positioned by a process positioning pin, and the three-petal rough-machined sector segments are combined into an integral circular ring member by connecting bolts; The said finishing big end reference: positioning with the small end, flattening the big end end surface and outer circle for positioning in the next process; The small end is finely turned: the large end face and the outer cylindrical surface are used for positioning, the small end face and the inner flow channel are finely turned, and the spraying receiving groove is finely turned; The precision milling of the small end lace and the outer mounting seat hole: positioning with the large end face and the outer cylindrical surface, precision milling of the small end face lace, the end face oblique hole, the boss threaded hole on the outer contour, etc.; and precision milling of the precision bolt positioning hole on the longitudinal mounting edge; The large end is finely turned: the small end face and the inner circle stop are used for positioning, the large end face and the inner flow channel are finely turned, and the spraying receiving groove is finely turned.

6. The method for machining a three-petal stator machine assembly with two-stage blades of an aircraft engine according to claim 5, characterized in that: The blank inspection: measure the size of the ring forging blank, check the blank surface quality, mark and forging material report to see if they meet the forging drawing and specification requirements; Rough turning of the inner and outer shapes: Rough turning of the two ends and the inner and outer contours to efficiently remove the blank excess; The rough milling of the outer shape: positioning and clamping with the inner blade contour, rough milling of the outer rib plate and the longitudinal installation edge contour; The inspection includes intermediate inspection and fluorescent penetrant inspection. The intermediate inspection: in the state of full ring, the constraints are carried out according to the constraints allowed by the design, and the three-coordinate inspection is used to detect the internal and external contour dimensions and form and position tolerances; the fluorescent penetrant inspection: overall inspection of all processed surfaces of the parts to see if there are cracks and other linear display defects; The spraying: spray the flow channel area according to the technical requirements of the parts, and pay attention to ensuring the minimum spraying thickness; The spray coating on the big end is positioned by the end face of the small end and the stop circle, and the coating of the two layers of the flow channel area of ​​the big end is fine-turned to the final size and aligned with the milled flow channel; The spray coating on the small end is positioned by the end face of the large end and the outer cylindrical surface, and the coating on the flow channel area of ​​the small end is fine-turned to the final size and aligned with the milled flow channel; The blade tip grinding: positioning by the small end face and the stop circle, grinding the blade tip profile of the two-stage blade to ensure the profile requirements of the blade tip parent line; The said clamp repair marking: the clamp worker removes the burrs on the blade tip, smoothly transfers the clamp repair coating area to the milled hub surface, and marks it according to the product design requirements; The fluorescent penetrant inspection: a local fluorescent penetrant inspection is performed on the machined area after the intermediate inspection; The final inspection: final inspection of parts surface quality, marking, size and geometric tolerances.

7. The method for machining a three-petal stator assembly with two-stage blades of an aircraft engine according to claim 6, characterized in that: The three-petal stator machined assembly is cut and processed after rough milling and then split to perform fine milling of the joint surface and holes, thereby eliminating part deformation after rough machining and ensuring the flatness and surface profile requirements of the 120° joint surface.

8. The method for machining a three-petal stator assembly with two-stage blades of an aircraft engine according to claim 7, characterized in that: When milling the joint surface and the hole, only the technical hole is processed for assembly, and when fine milling the outer shape, the installation positioning hole is combined and bored to ensure the position consistency of the assembly hole.

9. The method for machining a three-petal stator machine assembly with two-stage blades of an aircraft engine according to claim 1 or 6, characterized in that: A 0.5mm margin is left on the surface of the flow channel for spraying, and the entire flow channel is machined after spraying to ensure smoothness of the flow channel.

10. The method for machining a three-petal stator assembly with two-stage blades of an aircraft engine according to claim 1, characterized in that: The two-stage blade tip allowance of the three-petal stator machined assembly is ground after fine turning and coating to ensure that the blade tip meets the profile requirement of the reference.

Images