Method and tool for machining high-precision thin-wall casing of aero-engine

Abstract

The invention provides a machining method and tool for a high-precision thin-wall casing of an aero-engine, and belongs to the field of precision machining of thin-wall components of aero-engines. Comprising a clamp body which is provided with a hoisting hole and supporting plate mounting positions distributed in the circumferential direction. The inner-layer clamping mechanism and the outer-layer clamping mechanism are composed of supporting plates distributed along the circumference of the clamp body, each supporting plate is longitudinally provided with a plurality of sets of ejector rods, the ejector rods are locked through ejector rod installation nuts, and the tail ends of the ejector rods are provided with copper alloy ejector rod heads; the outer layer clamping mechanism comprises a pressing plate used for axially pressing the end face of the casing. The support plate is provided with three groups of upper, middle and lower ejector rod screw-thread fit holes. The tool not only has the part positioning function and the clamping space meeting the requirement that rough machining and finish machining of the cartridge receiver can share the same tool, but also has the functions of internal and external multi-point independent supporting and internal and external multi-point simultaneous supporting. According to the technological method, two times of heat treatment is added to remove stress generated by cutting machining, and two numerical control lathe finish machining procedures are refined into seven procedures.

Description

Technical Field

[0001] The present invention relates to the field of precision machining of thin-walled components of aero-engines, and particularly to a machining method and tooling for a high-precision thin-walled casing of an aero-engine. Background Art

[0002] The maximum outer diameter of the thin-walled casing of an aero-engine is 1360 mm, and the minimum wall thickness is only 1.45 mm. It has 22 high-precision holes with dimensional accuracy of ±0.009 mm and position accuracy of 0.018 mm. The end face runout requirement is 0.02 mm, and the roundness requirement in the free state is 0.15 mm. Its structure is complex, the allowance is large, the rigidity is poor, and it is easily affected by cutting force, clamping stress and residual stress, resulting in deformation.

[0003] The existing technology processes have the following defects: (1) The traditional process does not set a stress relief step. The manufacturing process is simple and rough, and the operability is poor. In the free state after machining, the roundness exceeds the tolerance by 0.02 - 0.16 mm, the position tolerance exceeds the tolerance by 0.01 - 0.15 mm, and the qualified rate is only 60%; (2) The tooling that uses a pressing plate to press the end face lacks multi-point support, and the clamping rigidity is insufficient, resulting in machining vibration, easy generation of chatter marks on the machining surface, and poor surface roughness.

[0004] (3) It is difficult to align the casing, and it is extremely difficult to meet the high-precision alignment requirement of circumferential runout of 0.01. Moreover, the alignment time is long, and the alignment machining time exceeds more than 540 hours, resulting in low machining efficiency of the casing.

[0005] The existing tooling adopts an equidistant support design, resulting in interference between the tool and the ejector rod. It is necessary to repeatedly adjust the position of the support plate, with low efficiency and potential safety hazards.

[0006] The existing methods cannot meet the high-precision machining requirements of the thin-walled casing, specifically manifested as insufficient control of machining deformation, resulting in dimensional tolerance; poor rigidity of the clamping system, unable to achieve high-precision roundness adjustment of 0.008 mm; unstable hole machining process, and low qualified rate of high-precision holes (such as Ø9 + 0.009 mm). Summary of the Invention

[0007] The purpose of the present invention is to provide a machining method and tooling for a high-precision thin-walled casing of an aero-engine, providing a process method that can eliminate machining stress and control deformation in stages; designing a multi-point adjustable support tooling to achieve high-precision clamping of the thin-walled casing.

[0008] The present invention is implemented by the following technical solutions: A processing tooling for high-precision thin-walled casings of aero-engines, including a fixture body, which is made of high-quality cast iron and subjected to aging treatment, and is provided with a lifting hole and a support plate mounting position distributed in the circumferential direction; an inner and outer two-layer clamping mechanism, the inner and outer layers are composed of support plates distributed along the circumference of the fixture body, and multiple groups of ejector rods are longitudinally arranged on each support plate. The ejector rods are locked by ejector rod mounting nuts, and a copper alloy ejector rod head is provided at the end of the ejector rod; the outer clamping mechanism includes a pressing plate, which is fixed on the fixture body through pressing plate mounting screws and pressing plate adjusting screws and is used to axially press the end face of the casing; three groups of ejector rod threaded holes, namely upper, middle and lower, are arranged on the support plate, with a total of 64 groups and 192 points, which are used to correct the radial circular runout of the casing to ≤0.008 mm.

[0009] Through the design of this tooling structure, high-precision and stable clamping of complex thin-walled casings can be achieved, effectively controlling the deformation during the processing, and improving the overall processing precision and consistency.

[0010] Furthermore, the fixture body adopts an overall stepped ring design, and the inner hole diameter is as large as possible under the condition of meeting the tooling installation to reduce the weight and improve the rigidity; the pressing plates are distributed between every two support plates, and the height can be finely adjusted through the pressing plate adjusting screws.

[0011] This structural design reduces the overall weight of the tooling, improves the structural rigidity, and ensures uniform force on the end face of the casing through the fine adjustment of the pressing plate, thereby improving the installation precision and clamping stability.

[0012] Furthermore, the ejector rod and the support plate adopt a threaded fit, and the material of the ejector rod head is H62 copper alloy, which is used to avoid damaging the surface of the casing; the layout of the support plates is a non-equidistant design to avoid machining interference between the tool and the ejector rod.

[0013] The design of the copper alloy ejector rod head ensures the integrity of the casing surface, and the non-equidistant layout of the support plates can avoid structural interference during the processing, ensuring the continuity and stability of the processing.

[0014] A processing method for high-precision thin-walled casings of aero-engines includes the following steps: S1 Rough machining: Removing the surplus of the casing blank with a large cutting amount; S2 Machining of the reference surface and secondary rough machining: Precision turning the large end face of the casing as the subsequent reference, with the end face runout ≤0.02 mm, and performing secondary rough turning of the inner and outer shapes; S3 Semi-finishing machining: Semi-precision turning the inner and outer shapes of the casing to a wall thickness tolerance of ±0.1 mm; S4 Finishing machining and high-precision hole machining: Through the positioning and clamping of the tooling, precision turning to the final size and machining Φ9 high-precision holes, with the hole position accuracy reaching φ0.018 mm and the dimensional accuracy reaching 0.009 mm.

[0015] Adopt high-precision tooling to ensure the repeat positioning accuracy of the machining process, so as to achieve extremely high dimensional and position accuracy requirements.

[0016] Furthermore, after step S1, vacuum heat treatment is carried out to eliminate residual stress, and after S3, secondary vacuum heat treatment is carried out.

[0017] Double vacuum heat treatment can significantly reduce the influence of machining stress on the part shape and improve the overall dimensional stability.

[0018] Furthermore, the clamping steps in step S4 include: Step 1, press the casing end face through a pressing plate and adjust the radial symmetric point error to ≤0.02 mm; Step 2, use a push rod to correct the outer circle runout to ≤0.008 mm, and finely adjust the end face parallelism to ≤0.01 mm through a lever dial indicator.

[0019] The high-precision clamping process can minimize the clamping error to the greatest extent and provide a reliable guarantee for ultra-high-precision hole machining.

[0020] Furthermore, the high-precision hole machining steps in step S4 include: Step 1, use an alloy center drill for spot drilling and positioning; Step 2, use an internal cooling alloy drill bit to machine small holes; Step 3, use an end face spiral milling cutter to expand the hole and a circular arc radial milling cutter to repair the hole; Step 4, semi-precision boring to adjust the hole position; Step 5, use an alloy milling reamer to finish reaming to the final size.

[0021] Through a multi-process progressive precision machining process, ensure that the geometric accuracy and dimensional accuracy of the hole position reach the limit requirements.

[0022] A method and tooling for machining a high-precision thin-walled casing of an aero-engine according to the present invention have the following beneficial effects: This tooling not only meets the requirements that the part positioning and clamping space can be shared by the rough and finish machining of the casing, but also has the functions of internal and external multi-point independent support and internal and external multi-point simultaneous support; this tooling not only meets the clamping requirements of multi-point internal and external independent support for separate machining of the inner cavity and outer shape in multiple NC turning processes, but also meets the clamping requirements of multi-point internal and external simultaneous support for NC milling of lace and hole machining, and greatly improves the alignment and adjustment accuracy of the part, enhances the clamping rigidity, and meets the alignment requirements of high-precision hole positions (positional tolerance φ0.018) of the part; the enhancement of the part clamping rigidity increases the cutting parameters, greatly improves the machining efficiency, and well guarantees the qualification rate and quality stability of the high-precision thin-walled casing machining.

[0023] This innovative process method, firstly, adds 2 heat treatments to remove the stress generated by cutting, and secondly, refines the original 2 NC turning finish machining processes into 7 processes, gradually reducing the deformation caused by part structure changes and cutting, and improving the machining accuracy. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. The drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0025] Figure 1 Structural schematic diagram of the present invention; Figure 2 For Figure 1 Partial schematic view in the direction of A in In the figure, 1 - fixture body, 2 - support plate, 3 - support plate mounting screw, 4 - pressing plate, 5 - ejector rod, 6 - ejector rod head, 7 - ejector rod mounting nut, 8 - pressing plate mounting screw, 9 - pressing plate adjusting screw, 10 - lifting hole. Specific embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0028] As Figure 1-2 shown, a high-precision thin-walled casing processing tooling for an aero-engine includes a fixture body 1 and a clamping mechanism installed on the fixture body 1. The clamping mechanism includes an inner and an outer layer, and the casing is arranged between the inner and outer clamping mechanisms. The clamping mechanism includes a plurality of ejector rods 5. The ejector rods 5 are arranged on the support plates 2. The support plates 2 are arranged along the circumferential direction of the fixture body 1, and a plurality of ejector rods 5 are arranged longitudinally on each support plate 2.

[0029] The clamping mechanism further includes a pressing plate 4, which is arranged on the outer clamping mechanism and is disposed between every two support plates 2. The support plates 2 are fixed to the fixture body 1 by support plate mounting screws 3, and the pressing plate 4 is fixed to the fixture body 1 by pressing plate mounting screws 8. A pressing plate adjusting screw 9 is further arranged between the tail of the pressing plate 4 and the fixture body 1. One end of the ejector rod 5 in contact with the casing is also provided with an ejector rod head 6. A lifting hole 10 is further arranged on the fixture body 1. The ejector rod 5 is threadedly connected to the support plate 2, and an ejector rod mounting nut 7 is further arranged on the ejector rod 5 to lock the ejector rod 5 on the support plate 2 through the ejector rod mounting nut 7.

[0030] This tooling not only meets the requirements that the part positioning and clamping space can be shared by the rough and finish machining of the casing with the same tooling, but also has the functions of internal and external multi-point independent support and internal and external multi-point simultaneous support; this tooling not only meets the clamping requirements of multi-point internal and external independent support for separate machining of the inner cavity and outer shape in multiple CNC turning processes, but also meets the clamping requirements of multi-point internal and external simultaneous support for CNC milling lace and hole machining, greatly improving the alignment and adjustment accuracy of the part and enhancing the clamping rigidity, meeting the alignment requirements of high-precision hole positions (positional tolerance φ0.018) of the part; the enhancement of the clamping rigidity of the part enables an increase in its cutting parameters, resulting in a significant improvement in processing efficiency and ensuring the qualification rate and quality stability of the machining of high-precision thin-walled casings.

[0031] Working principle: The end face of the casing contacts the upper plane of the fixture body 1, and axial positioning and clamping of the casing are achieved through the pressing plate 4; three groups of upper, middle, and lower ejector rod threaded mating holes are designed on the support plate 2, with a total of 64 groups and 192 points. The ejector rods 5 on the support plate 2 can be used to adjust multiple points on the upper, middle, and lower parts of the casing respectively, correcting the deformed position of the casing to meet the process requirements, achieving radial positioning of the casing and high-precision roundness adjustment and alignment of 0.008. A corresponding ejector rod mounting nut 7 is installed on each ejector rod 5 to lock the ejector rod 5 to ensure that the ejector rod 5 will not loosen due to the force during cutting, resulting in a reduction in the radial positioning accuracy of the casing; the support of numerous ejector rods 5 increases the clamping rigidity of the casing, avoiding vibration during machining, reducing the machining deformation of the casing, and improving the machining efficiency and quality; the clamping mechanism on the tooling adopts a non-equidistant design, which can avoid the collision and interference between the tool and the ejector rod 5 when machining the upper part of the middle step holes, eliminating the need to pause and move the position of the support plate 2 during the machining of the part, thus reducing the operation time and the quality and safety risks.

[0032] The fixture body 1 is made of high-quality cast iron and undergoes aging treatment. The resulting fixture body 1 not only has high hardness, good wear resistance, and low manufacturing cost, but also has good stability and shock absorption. Moreover, it can meet the requirements of small deformation and good precision retention during long-term repeated use of the fixture body 1. The main body adopts an overall stepped ring design to improve the overall strength and rigidity of the tooling. At the same time, the large-diameter inner hole and stepped design significantly reduce the weight of the tooling, making it convenient for handling and installation operations. The external dimensions of the fixture body 1 are designed according to the maximum contour dimensions of the casing. While ensuring sufficient installation space for the casing, the outer diameter dimension is minimized as much as possible, thereby further reducing the weight of the fixture body 1 and also reducing the specification requirements of the fixture body 1 for the machine tool, lowering the production cost. The ejector head 6 is made of copper alloy H62 material, which can not only prevent damage to the surface of the part but also ensure that the ejector head 6 has sufficient strength to meet the support requirements.

[0033] The material of this casing is a GH4169 superalloy forging. The material is very difficult to machine, has a large machining allowance, large machining deformation, and extremely high precision requirements. Controlling machining deformation is the key to the manufacturing production of thin-walled casings, which directly affects the qualification of product machining. And the process method, clamping method, specific machining route arrangement, and parameters are the key points of deformation control. The process method provided by the present invention is as follows: S1, Rough machining: Use a large cutting amount to machine and remove the large allowance of the casing blank, laying a foundation for subsequent machining.

[0034] S2, Machining of the reference surface and secondary rough machining: Precision turn the large end face of the casing to form a reference for subsequent machining, ensuring that the runout between the end face and the reference surface is ≤0.02mm. Rough turn the inner cavity and outer shape of the casing respectively for a second time to further remove the allowance. The casing wall is thin, and chatter will occur during machining. To solve the chatter problem and improve machining efficiency, the casing must be supported and fixed before machining.

[0035] S3, Semi-finishing machining: Semi-precision turn the inner and outer shapes of the casing to control the uniformity of the allowance, with a wall thickness tolerance of ±0.1mm.

[0036] S4, Finishing machining and high-precision hole machining: Precision turn the casing to the final size, and position and clamp the casing through this machining fixture. When clamping, adjust the circular runout ≤0.01mm through the ejector rod of the fixture, ensuring that the end face parallelism is ≤0.01mm. Finally, machine 22 high-precision holes of Φ9 in sequence.

[0037] Among them, after step S1, the casing after rough machining is subjected to vacuum heat treatment to eliminate the residual stress generated by rough machining and reduce subsequent deformation. After step S3, the casing after semi-finishing machining is subjected to secondary vacuum heat treatment to further eliminate machining stress and ensure the stability of finishing machining.

[0038] The positioning and clamping steps of the casing in step S4 include the following steps: Step 1: Place the tooling on the rotary workbench, use a dial indicator to align the center of the inner circle of the tooling with the center of the workbench, with an error not exceeding 0.1, and clamp it on the workbench through bolts and pressure plates.

[0039] Step 2: Place the end face to be machined of the casing upward, and place its corresponding end face on the upper surface of the fixture 1, and visually conduct a rough radial positioning of the casing.

[0040] Step 3: Place the pressure plate 4 on the pressing surface of the lower end face of the casing through the pressure plate mounting screw 8, adjust the height of the pressure plate adjusting screw 9 so that the lower plane of the pressure plate 4 is slightly higher than the contact surface of the casing, and then gently rotate the pressure plate mounting screw 8 by hand to slightly contact the surface of the pressure plate 4.

[0041] Step 4: Select 4 symmetric points evenly distributed on the outer circle at the upper end of the casing, rotate the workbench and move the part, measure the symmetry point error of the 4 points within 0.02 by a lever dial indicator, adjust the center of the casing to the rotary center of the workbench, and then gently press the casing by rotating the pressure plate mounting screw 8 by hand (the casing can move radially but not axially).

[0042] Step 5: Rotate the workbench, use a lever dial indicator to find and mark on the outer circle at the upper end of the casing, and take this as the reference, then select 2 more points to form 4 symmetric points evenly distributed; first adjust the ejector rod 5 at the outer circle of the maximum point part so that the error between the maximum point and the minimum point is within 0.02, then adjust the ejector rod 5 at the outer circle of other parts, adjust the overall runout of the outer circle of the casing to within 0.02, and then adjust the ejector rod 5 of the inner ring of the tooling to contact the inner ring surface of the casing.

[0043] Step 6: Replace the lever dial indicator with a lever micrometer, and mark 32 runout error values corresponding to the ejector rod 5 on the upper end face of the casing; first adjust the symmetric point with the largest error value, rotate the ejector rod mounting nut 7 for pre-tightening, and then gradually adjust the ejector rod 5 at other parts with larger error values, finely adjust the overall runout of the outer circle of the casing to within 0.008, and at the same time rotate the ejector rod mounting nut 7 for locking.

[0044] Step 7: Use an internal hexagon wrench to rotate the pressure plate mounting screw 8 clockwise to press the end face of the casing. At this time, the casing cannot move axially or radially, is in the correct position for processing and machining, and reaches the positioning and alignment accuracy of the casing, completing the clamping and alignment of the casing.

[0045] The high-precision hole machining in the said Step S4 specifically includes the following steps: Step 1: Use an alloy center drill for point hole positioning; Step 2: Use an internal coolant alloy drill bit to machine small holes (internal coolant can effectively reduce the temperature of the cutting area and improve the tool durability. The reason for choosing a smaller drill bit is to reduce the cutting force and avoid deformation of the casing due to excessive drilling force). Step 3: Use a milling cutter to perform reaming by end face spiral milling; Step 4: Use a milling cutter to perform hole finishing by arc radial milling to ensure uniform and stable hole allowance; Step 5: Use a boring cutter to perform semi-precision boring to adjust or correct the position accuracy of the hole (boring is an effective method to ensure the hole position accuracy of φ0.018); Step 6: Finally, use an alloy milling reamer to perform finish reaming to achieve a dimensional accuracy of Φ9 hole of 0.009 and ensure its extremely high machining stability (reaming does not change the position accuracy).

[0046] The present invention solves the technical problems existing in the existing processing technology methods of high-precision thin-walled casings of aero-engines, such as insufficient stress relief treatment, large machining deformation, simple and rough manufacturing process, poor operability, poor clamping rigidity of the casing, difficult alignment, easy deformation during machining, low machining efficiency, and difficult to guarantee accuracy. It overcomes the deficiencies in the aspects of internal stress removal and thin-wall deformation control technology of the existing process methods, as well as the deficiencies in the effective support of the thin-walled casing and the accuracy and quickness of high-precision alignment in the fixture design.

[0047] Through heat treatment aging and refined processing technology, the present invention effectively eliminates the stress generated during the production process of parts due to structural changes and cutting processing, and reduces the deformation of thin-walled casing parts. The innovative fixture design not only has the advantages of reasonable structure, convenient manufacturing, and low production cost, but also has the same fixture used in multiple processes, which can not only save the fixture design and manufacturing costs, shorten the fixture manufacturing cycle, but also reduce the die change time and the storage space occupied by large fixtures; more importantly, this fixture has the functions of internal and external multi-point independent support and internal and external multi-point simultaneous support, which not only meets the clamping requirements of multi-point independent support for separate machining of the inner cavity and outer shape in CNC turning, but also meets the clamping requirements of multi-point simultaneous support for CNC milling of lace and hole processing, and greatly improves the alignment and adjustment accuracy of the parts, enhances the clamping rigidity, and meets the alignment requirements of high-precision hole positions (positional tolerance φ0.018) of the parts; the enhancement of the clamping rigidity of the parts increases their machining parameters, makes the machining quality more stable, well guarantees the machining quality of high-precision thin-walled casings, increases the machining qualification rate by 36%, reduces the clamping alignment and machining time by 32 hours per piece, increases the machining efficiency by 41%, and effectively reduces the production cost by 6,800 yuan per piece.

[0048] In the above embodiments, the basic principles, main features, and advantages of the present invention are described. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, any modifications and changes made by those skilled in the art should fall within the protection scope of the appended claims of the present invention.

Claims

1. A high-precision thin-wall casing processing tooling for an aero-engine, characterized in that It includes a fixture body (1), which is made of high-quality cast iron material and has been aged. It is provided with a lifting hole (10) and support plate mounting positions distributed in the circumferential direction; an inner and outer layer clamping mechanism, where the inner and outer layers are composed of support plates (2) distributed along the circumference of the fixture body (1). A plurality of sets of ejector rods (5) are longitudinally arranged on each support plate (2). The ejector rods (5) are locked by ejector rod mounting nuts (7), and a copper alloy ejector rod head (6) is provided at the end of the ejector rods (5); the outer layer clamping mechanism further includes a pressing plate (4), which is fixed on the fixture body (1) by pressing plate mounting screws (8) and pressing plate adjusting screws (9) for axially pressing the end face of the casing. There are three sets of ejector rod thread engagement holes, upper, middle and lower, on the support plate (2), a total of 64 sets and 192 points, for correcting the radial circular runout of the casing to ≤0.008 mm.

2. The machining tooling for a high-precision thin-walled casing of an aero-engine according to claim 1, wherein, The fixture body (1) adopts an integral stepped ring design, and the inner hole diameter is determined to meet the installation of the tooling; the pressing plates (4) are distributed between every two support plates (2), and height fine adjustment is realized through the pressing plate adjusting screws (9).

3. The machining tooling for a high-precision thin-walled casing of an aero-engine according to claim 1, wherein, The ejector rods (5) are in threaded engagement with the support plates (2), and the material of the ejector rod head (6) is H62 copper alloy to avoid damaging the surface of the casing; the layout of the support plates (2) is a non-equidistant design to avoid machining interference between the tool and the ejector rods (5).

4. A machining method for a high-precision thin-walled casing of an aero-engine, which is realized by using the machining tooling for a high-precision thin-walled casing of an aero-engine according to any one of claims 1 to 3, and is characterized in that, It includes the following steps: S1 Rough machining: Remove the surplus of the casing blank. S2 Machining of the reference surface and secondary rough machining: Precision turn the large end face of the casing as the subsequent reference, with the end face runout ≤0.02 mm, and perform secondary rough turning of the inner and outer shapes. S3 Semi-finishing machining: Semi-precision turn the inner and outer shapes of the casing to a wall thickness tolerance of ±0.1 mm. S4 Finishing machining and high-precision hole machining: Through the tooling positioning and clamping described in any one of claims 1-3, precision turn to the final size and machine a Φ9 high-precision hole, with the hole position accuracy reaching φ0.018 mm and the dimension accuracy reaching 0.009 mm.

5. A machining method for a high-precision thin-wall casing of an aero-engine according to claim 4, characterized in that, After step S1, vacuum heat treatment is carried out to eliminate residual stress, and after step S3, secondary vacuum heat treatment is carried out.

6. A method for machining a high-precision thin-walled casing of an aero-engine according to claim 4, characterized in that, The clamping steps in step S4 include: Step 1, pre-press the end face of the casing through the pressing plate (4) to adjust the radial symmetry point error to ≤0.02 mm; Step 2, use the ejector rod (5) to correct the outer circle runout to ≤0.008 mm, and finely adjust the end face parallelism to ≤0.01 mm through a lever dial indicator.

7. A method for machining a high-precision thin-walled casing of an aeroengine according to claim 4, characterized in that, The high-precision hole machining steps in step S4 include: Step 1, use an alloy center drill to drill and position the hole; Step 2, use an internal cooling alloy drill to machine a small hole; Step 3, end face spiral milling to expand the hole and arc radial milling to repair the hole; Step 4, semi-precision boring to adjust the hole position accuracy; Step 5, use an alloy milling reamer to finish reaming to the final size.

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