Coaxiality adjusting method for bearing mounting holes in aero-engine case

Abstract

The invention discloses a method for adjusting the coaxiality of bearing mounting holes in an aero-engine case, which comprises the following steps of: S1, measuring the coaxiality of a front bearing mounting hole and a rear bearing mounting hole in an inner case relative to an outer case, and establishing a polar coordinate system on the outer case, respectively marking the phases of the front bearing mounting hole and the rear bearing mounting hole in the polar coordinate system; s2, calculating a corresponding tension bolt adjustment amount according to the coaxiality of the bearing mounting hole relative to the outer casing and the phase of the bearing mounting hole in the polar coordinate system; s3, the adjustment amount of the draw-in bolt is converted into a torsion angle so as to turn the draw-in bolt, then the coaxiality of the bearing mounting hole is adjusted, and it is ensured that the tightening torque is within a set range; and S4, the coaxiality of the front bearing mounting hole and the rear bearing mounting hole in the inner casing relative to the outer casing is measured again, and whether the coaxiality of the front bearing mounting hole and the rear bearing mounting hole relative to the outer casing meets the set requirement or not is judged according to the coaxiality judgment condition.

Description

Technical Field

[0001] The present invention relates to the technical field of engine casing assembly, and in particular, to a method for adjusting the coaxiality of bearing mounting holes on an aero-engine casing. Background Technique

[0002] In an aero-engine, high requirements are imposed on the coaxiality of bearing supports to ensure that the rotor during high-speed rotation can withstand additional acting forces and operate stably.

[0003] In an aero-engine, the casing for mounting bearings is mainly divided into an inner casing and an outer casing. The inner casing is circumferentially provided with uniformly distributed rib plates, and threaded holes are provided on the rib plates. Each rib plate is connected to the outer casing through a tension bolt. To ensure the coaxiality of the bearings, it is necessary to check the runout of the bearing mounting holes with respect to the outer casing stop after assembly. However, since there are multiple detachable parts on the inner casing, and these parts are all in large interference fits, there are one or more high and low points with different radii between the outer diameter of the inner casing and the inner diameter of the outer casing. The high point position of the outer diameter of the inner casing is easily aligned with the high point position of the inner diameter of the outer casing, and the high points of the inner and outer diameters will squeeze each other, resulting in casing offset, and the runout inspection results often exceed the tolerance by several times, and the coaxiality between the bearing mounting holes and the outer casing cannot be controlled. Summary of the Invention

[0004] The present invention provides a method for adjusting the coaxiality of bearing mounting holes on an aero-engine casing to solve the technical problem of poor coaxiality between the bearing mounting holes and the outer casing in existing aero-engines.

[0005] According to one aspect of the present invention, there is provided a method for adjusting the coaxiality of bearing mounting holes on an aero-engine casing, including the following steps: S1: Measure the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing with respect to the outer casing, and establish a polar coordinate system on the outer casing to respectively mark the phases of the front bearing mounting hole and the rear bearing mounting hole in the polar coordinate system, as well as the distribution of a plurality of circumferentially uniformly distributed tension bolts in the polar coordinate system; S2: Calculate the corresponding tension bolt adjustment amount according to the coaxiality of the bearing mounting hole with respect to the outer casing and the phase of the bearing mounting hole in the polar coordinate system; S3: Convert the tension bolt adjustment amount into a torsional angle to twist the tension bolt, thereby adjusting the coaxiality of the bearing mounting hole and ensuring that the tightening torque is within the set range; S4: Measure the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing with respect to the outer casing again, and judge whether the coaxiality of the front bearing mounting hole and the rear bearing mounting hole with respect to the outer casing meets the set requirements according to the coaxiality judgment condition. If the set requirements are met, the adjustment is ended. If the set requirements are not met, repeat steps S2 - S4 until the set requirements are met.

[0006] As a further improvement of the above technical solution:

[0007] Further, in step S2, when the phase of the bearing mounting hole in the polar coordinate system is α, and when adjusting two adjacent tension bolts that are 180° different from α in the polar coordinate system, the following calculation formula is obtained:

[0008]

[0009] Among them, A is the eccentricity of the bearing mounting hole in the polar coordinate system, A1 is the adjustment amount of the first tension bolt, A2 is the adjustment amount of the second tension bolt, i is the phase of the first tension bolt in the polar coordinate system, and n is the number of tension bolts evenly distributed in the circumferential direction.

[0010] Further, in step S2, the calculation formula for the adjustment amount of the tension bolt is:

[0011] ΔA = k·A·cosα;

[0012] Among them, ΔA is the adjustment amount of the tension bolt, k is the proportionality coefficient, A is the eccentricity of the bearing mounting hole in the polar coordinate system, and α is the phase of the bearing mounting hole in the polar coordinate system.

[0013] Further, in step S3, the conversion formula between the adjustment amount of the tension bolt and the torsional angle is:

[0014] ΔA / P = γ / 2π;

[0015] Among them, P is the pitch of the tension bolt, and γ is the torsional angle.

[0016] Further, k is 0.5, 0.284 or 0.797.

[0017] Further, the specific steps for establishing a polar coordinate system on the outer casing are as follows:

[0018] Select the rear end face of the outer casing as the X plane, select the line connecting the axis of the positioning pin on the rear end face of the outer casing and the axis of the outer casing as the Y plane, select the intersection point of the X plane and the axis of the outer casing as the origin of the polar coordinates, and select the intersection line of the X plane and the Y plane as the starting position of the angle, so as to establish a polar coordinate system.

[0019] Further, in step S4, the condition for the coaxiality to meet the set requirements is:

[0020] A F ≤0.01, A B ≤0.01;

[0021] Among them, A F is the coaxiality of the front bearing mounting hole relative to the outer casing, and A B is the coaxiality of the rear bearing mounting hole relative to the outer casing.

[0022] Further, when measuring the coaxiality, there are at least 3 cross-sections for coaxiality measurement, and when measuring repeatedly, the axial deviation of the measurement position is ensured to be no more than 2 mm.

[0023] Further, before step S1, there is also a step: during the assembly of the outer casing and the inner casing, all the tension bolts evenly distributed circumferentially are tightened in a star-shaped order with the tightening torque gradually increased, and the upper limit of the tightening torque is the middle value of the set torque range.

[0024] Further, before step S1, there is also a step: installing the casing on a turntable or a coordinate measuring machine.

[0025] The present invention has the following beneficial effects:

[0026] The coaxiality adjustment method for the bearing mounting holes on the aero-engine casing of the present invention measures the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing relative to the outer casing, and establishes a polar coordinate system on the outer casing to respectively mark the phases of the front bearing mounting hole and the rear bearing mounting hole in the polar coordinate system, as well as the distribution of the tension bolts evenly distributed circumferentially in the polar coordinate system, so as to correlate the bearing mounting holes and the tension bolts with each other in the polar coordinate system; calculates the adjustment amount of the tension bolts according to the coaxiality of the bearing mounting holes relative to the outer casing and the phases of the bearing mounting holes in the polar coordinate system, and then can adjust the coaxiality of the bearing mounting holes relative to the outer casing by screwing the tension bolts; converts the adjustment amount of the tension bolts into a torsional angle to twist the tension bolts, thereby adjusting the coaxiality of the bearing mounting holes. The torsional angle and the tightening torque of the tension bolts are in a linear relationship, so as to facilitate obtaining the tightening torque of the tension bolts according to the change of the torsional angle, thereby ensuring that the tightening torque is within the set range, avoiding loosening due to too small tightening torque and damage caused by mutual extrusion due to too large tightening torque; measures the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing relative to the outer casing again, and judges whether the coaxiality of the front bearing mounting hole and the rear bearing mounting hole relative to the outer casing meets the set requirements according to the coaxiality judgment conditions. If the set requirements are met, the adjustment is ended. If the set requirements are not met, the above steps are repeated until the set requirements are met, realizing precise control of the coaxiality of the bearing mounting holes and the outer casing; compared with the prior art, the present solution correlates the coaxiality of the bearing mounting holes with the adjustment amount of the tension bolts by establishing a polar coordinate system, and can effectively control the coaxiality of the bearing mounting holes relative to the outer casing by screwing the tension bolts, so as to ensure that the coaxiality of the bearing mounting holes relative to the outer casing meets the design requirements and avoid the out-of-tolerance of the runout inspection results. It has strong practicability and is suitable for wide promotion and application.

[0027] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The following will refer to the drawings for a further detailed description of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which form a part of this application, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 is a flowchart of the method for adjusting the coaxiality of the bearing mounting holes on the aero-engine casing according to a preferred embodiment of the present invention;

[0030] Figure 2 is a schematic structural diagram of the outer casing in the method for adjusting the coaxiality of the bearing mounting holes on the aero-engine casing according to a preferred embodiment of the present invention;

[0031] Figure 3 is a schematic layout diagram of the tension bolts in the polar coordinate system in the method for adjusting the coaxiality of the bearing mounting holes on the aero-engine casing according to a preferred embodiment of the present invention. Detailed Embodiment

[0032] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways defined and covered by the following.

[0033] As Figures 1 - 3 shown, the method for adjusting the coaxiality of the bearing mounting holes on the aero-engine casing in this embodiment includes the following steps: S1: Measure the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing relative to the outer casing, and establish a polar coordinate system on the outer casing to respectively mark the phases of the front bearing mounting hole and the rear bearing mounting hole in the polar coordinate system, and the distribution of a plurality of circumferentially evenly distributed tension bolts in the polar coordinate system; S2: Calculate the corresponding tension bolt adjustment amount according to the coaxiality of the bearing mounting hole relative to the outer casing and the phase of the bearing mounting hole in the polar coordinate system; S3: Convert the tension bolt adjustment amount into a torsional angle to twist the tension bolt, thereby adjusting the coaxiality of the bearing mounting hole and ensuring that the tightening torque is within the set range; S4: Measure the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing relative to the outer casing again, and judge whether the coaxiality of the front bearing mounting hole and the rear bearing mounting hole relative to the outer casing meets the set requirements according to the coaxiality judgment condition. If the set requirements are met, the adjustment is ended. If the set requirements are not met, repeat steps S2 - S4 until the set requirements are met.

[0034] As Figures 1 - 3As shown in the figure, specifically, for the method of adjusting the coaxiality of the bearing mounting holes on the aero-engine casing of the present invention, by measuring the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing relative to the outer casing, and establishing a polar coordinate system on the outer casing to respectively mark the phases of the front bearing mounting hole and the rear bearing mounting hole in the polar coordinate system, as well as the distribution of the circumferentially evenly distributed tension bolts in the polar coordinate system, so as to correlate the bearing mounting holes and the tension bolts with each other in the polar coordinate system; calculating the adjustment amount of the tension bolts according to the coaxiality of the bearing mounting holes relative to the outer casing and the phases of the bearing mounting holes in the polar coordinate system, then the coaxiality of the bearing mounting holes relative to the outer casing can be adjusted by screwing the tension bolts; by converting the adjustment amount of the tension bolts into a torsional angle to twist the tension bolts, thereby adjusting the coaxiality of the bearing mounting holes. There is a linear relationship between the torsional angle and the tightening torque of the tension bolts, which is convenient to obtain the tightening torque of the tension bolts according to the change of the torsional angle, so as to ensure that the tightening torque is within the set range, avoid being too small and easy to loosen, and avoid being too large and squeezing and damaging each other; measure the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing relative to the outer casing again, and judge whether the coaxiality of the front bearing mounting hole and the rear bearing mounting hole relative to the outer casing meets the set requirements according to the coaxiality judgment conditions. If the set requirements are met, the adjustment is ended. If the set requirements are not met, repeat the above steps until the set requirements are met, realizing precise control of the coaxiality of the bearing mounting holes and the outer casing; compared with the prior art, by establishing a polar coordinate system to correlate the coaxiality of the bearing mounting holes with the adjustment amount of the tension bolts, the coaxiality of the bearing mounting holes relative to the outer casing can be effectively controlled by screwing the tension bolts, so as to ensure that the coaxiality of the bearing mounting holes relative to the outer casing meets the design requirements and avoid the over-tolerance of the runout inspection results. It has strong practicability and is suitable for wide promotion and application.

[0035] It should be understood that the casing includes an outer casing and an inner casing.

[0036] It should be understood that the bearing mounting holes include a front bearing mounting hole and a rear bearing mounting hole.

[0037] It should be understood that the outer casing and the inner casing are connected by a plurality of circumferentially evenly distributed tension bolts.

[0038] As Figure 3 shown, in one embodiment, there are 7 tension bolts evenly distributed along the circumferential direction.

[0039] As Figure 3 shown, in this embodiment, in step S2, when the phase of the bearing mounting hole in the polar coordinate system is α, when adjusting two adjacent tension bolts that are 180° different from α in the polar coordinate system, the following calculation formula is obtained:

[0040]

[0041] Wherein, A is the coaxiality of the bearing mounting hole relative to the outer casing, A1 is the adjustment amount of the first tension bolt, A2 is the adjustment amount of the second tension bolt, i is the phase of the first tension bolt in the polar coordinate system, and n is the number of tension bolts evenly distributed circumferentially.

[0042] Specifically, the coaxiality of the bearing mounting hole relative to the casing is the eccentricity of the bearing mounting hole in the polar coordinate system, that is, the above calculation formula can be obtained by conversion based on trigonometric functions. Then, by calculating the adjustment amounts of the two tension bolts arranged opposite to the bearing mounting hole through the above calculation formula, the tightening torque of these two tension bolts can be increased, so that the axis of the bearing mounting hole can be close to the axis of the outer casing, thereby effectively controlling the coaxiality of the bearing mounting hole relative to the outer casing.

[0043] In this embodiment, in step S2, the calculation formula for the adjustment amount of the tension bolt is:

[0044] ΔA = k·A·cosα;

[0045] Wherein, ΔA is the adjustment amount of the tension bolt, k is the proportionality coefficient, A is the coaxiality of the bearing mounting hole relative to the outer casing, and α is the phase of the bearing mounting hole in the polar coordinate system.

[0046] Specifically, the above formula is a simplified formula, and the proportionality coefficient is an empirical coefficient, which is beneficial to saving the calculation amount, quickly obtaining the calculation result of the adjustment amount of the tension bolt, and then improving the efficiency of coaxiality adjustment.

[0047] In this embodiment, in step S3, the conversion formula between the adjustment amount of the tension bolt and the torsional angle is:

[0048] ΔA / P = γ / 2π;

[0049] Wherein, P is the pitch of the tension bolt, and γ is the torsional angle.

[0050] Specifically, through the above formula, the adjustment amount of the tension bolt can be converted into the torsional angle, and whether the tightening torque is within the set range can be verified through the torsional angle, so as to ensure that the tightening torque of the tension bolt meets the set requirements.

[0051] In this embodiment, k is 0.5, 0.284 or 0.797. Specifically, when the center of the bearing mounting hole is on the X-axis of the polar coordinate system and the coaxiality of the bearing mounting hole relative to the outer casing is e, it is only necessary to move the center of the bearing mounting hole in the -X direction by e. By adjusting the corresponding tension bolt, the resultant motion direction is made in the -X direction and the distance is e. In a certain embodiment, the proportionality coefficient k of the corresponding tension bolt is 0.5; when the center of the bearing mounting hole is on the Y-axis of the polar coordinate system and the coaxiality of the bearing mounting hole relative to the outer casing is e, it is only necessary to move the center of the bearing mounting hole in the -Y direction by e. By adjusting the corresponding tension bolt, the resultant motion direction is made in the -Y direction and the distance is e. At this time, in a certain embodiment, the proportionality coefficient k of the first tension bolt is 0.284, and the proportionality coefficient k of the second tension bolt is 0.797.

[0052] It should be understood that the proportionality coefficient is an empirical coefficient. In the initial adjustment process, usually, the adjustment amount of the tension bolt is first calculated using a conversion formula, and then the proportionality coefficient is obtained using a simplified formula to gradually accumulate the coaxiality of adjusting the bearing mounting hole relative to the outer casing in different situations. When encountering the same situation subsequently, the adjustment amount of the tension bolt can be directly obtained using the simplified formula, thereby saving the calculation amount and improving the adjustment efficiency.

[0053] As Figure 2 shown, in this embodiment, the specific steps for establishing a polar coordinate system on the outer casing are as follows: Select the rear end face of the outer casing as the X-plane, select the line connecting the axis of the positioning pin on the rear end face of the outer casing and the axis of the outer casing as the Y-plane, select the intersection point of the X-plane and the axis of the outer casing as the origin of the polar coordinates, and select the intersection line of the X-plane and the Y-plane as the starting position of the angle, thereby establishing a polar coordinate system. Specifically, through the above polar coordinate system, the coaxiality of the bearing mounting hole relative to the outer casing can be correlated with the adjustment amount of the tension bolt, so as to effectively control the coaxiality of the bearing mounting hole relative to the outer casing by screwing the tension bolt.

[0054] In this embodiment, in step S4, the condition for the coaxiality to meet the set requirements is:

[0055] A F ≤0.01, A B ≤0.01;

[0056] wherein, A F is the coaxiality of the front bearing mounting hole relative to the outer casing, and A B is the coaxiality of the rear bearing mounting hole relative to the outer casing.

[0057] In this embodiment, when measuring the coaxiality, the coaxiality measurement sections are no less than 3, and the axial deviation of the measurement position is ensured to be no greater than 2 mm when the measurement is repeated. Specifically, the coaxiality measurement accuracy is ensured by ensuring the number of coaxiality measurement sections and the axial deviation of the measurement position during repeated measurement, thereby effectively controlling the coaxiality of the bearing mounting hole relative to the outer casing.

[0058] In this embodiment, before step S1, the following step is also included: during the assembly process of the outer casing and the inner casing, all the circumferentially uniformly distributed tension bolts are tightened in a star-shaped sequence with gradually increasing tightening torque, and the upper limit of the tightening torque is the middle value of the set torque range. Specifically, by gradually increasing the tightening torque to tighten all the circumferentially uniformly distributed tension bolts in a star-shaped sequence, it is ensured that the initial torque of all tension bolts is the same and in a relatively stable state; and by making the upper limit of the tightening torque the middle value of the set torque range, after the coaxiality is adjusted, the tightening torque of the tension bolt is made within the set torque range as much as possible, thereby meeting the design requirements.

[0059] In this embodiment, before step S1, the step of: installing the casing on the turntable is further included. Specifically, after the casing is installed on the turntable, the coaxiality of the bearing mounting hole relative to the outer casing is quickly determined by using a dial indicator in conjunction with a rotating mark; and the coaxiality of the bearing mounting hole relative to the outer casing can be quickly determined by using a three-coordinate method by installing the casing on a three-coordinate measuring machine.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0061] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0062] In this article, specific examples are used to illustrate the principles and implementation modes of this application. The description of the above examples is only used to help understand the method and its core idea of this application. The above is only the preferred implementation mode of this application. It should be noted that due to the limited nature of language expression and objectively infinite specific structures, for those of ordinary skill in the art, without departing from the principles of this application, several improvements, refinements or changes can be made, or the above technical features can be combined in an appropriate way; these improvements, refinements, changes or combinations, or directly applying the inventive concept and technical solution to other occasions without improvement, shall all be regarded as within the protection scope of this application.

Claims

1. A method for adjusting the coaxiality of bearing mounting holes on an aeroengine casing, characterized in that It includes the following steps: S1: Measure the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing relative to the outer casing, and establish a polar coordinate system on the outer casing to respectively mark the phases of the front bearing mounting hole and the rear bearing mounting hole in the polar coordinate system, as well as the distribution of a plurality of circumferentially evenly distributed tension bolts in the polar coordinate system; S2: Calculate the corresponding tension bolt adjustment amount according to the coaxiality of the bearing mounting hole relative to the outer casing and the phase of the bearing mounting hole in the polar coordinate system; S3: Convert the tension bolt adjustment amount into a torsional angle to twist the tension bolt, thereby adjusting the coaxiality of the bearing mounting hole and ensuring that the tightening torque is within the set range; S4: Measure the coaxiality of the front bearing mounting hole and the rear bearing mounting hole on the inner casing relative to the outer casing again, and judge whether the coaxiality of the front bearing mounting hole and the rear bearing mounting hole relative to the outer casing meets the set requirements according to the coaxiality judgment condition. If the set requirements are met, the adjustment is ended. If the set requirements are not met, repeat steps S2 - S4 until the set requirements are met.

2. The coaxiality adjustment method of the bearing mounting holes on the aero-engine casing according to claim 1, characterized in that In step S2, when the phase of the bearing mounting hole in the polar coordinate system is α, and when adjusting two adjacent tension bolts β that are 180° different from α in the polar coordinate system, the following calculation formula is obtained: Where, A is the eccentricity of the bearing mounting hole in the polar coordinate system, A1 is the adjustment amount of the first tension bolt, A2 is the adjustment amount of the second tension bolt, i is the phase of the first tension bolt in the polar coordinate system, and n is the number of circumferentially evenly distributed tension bolts.

3. The coaxiality adjustment method for the bearing mounting holes on the aero-engine casing according to claim 1, characterized in that In step S2, the calculation formula for the tension bolt adjustment amount is: ΔA = k·A·cos α; Where, ΔA is the tension bolt adjustment amount, k is the proportionality coefficient, A is the eccentricity of the bearing mounting hole in the polar coordinate system, and α is the phase of the bearing mounting hole in the polar coordinate system.

4. The coaxiality adjustment method for the bearing mounting holes on the aero-engine casing according to claim 3, characterized in that In step S3, the conversion formula between the tension bolt adjustment amount and the torsional angle is: ΔA / P = γ / 2π; Where, P is the pitch of the tension bolt, and γ is the torsional angle.

5. The coaxiality adjustment method for the bearing mounting holes on the aero-engine casing according to claim 3, characterized in that k is 0.5, 0.284 or 0.

797.

6. The coaxiality adjustment method for the bearing mounting holes on the aero-engine casing according to any one of claims 1-5, characterized in that, The specific steps for establishing the polar coordinate system on the outer casing are: Select the rear end face of the outer casing as the X plane, select the connection line between the axis of the positioning pin on the rear end face of the outer casing and the axis of the outer casing as the Y plane, select the intersection point of the X plane and the axis of the outer casing as the polar coordinate origin, and select the intersection line of the X plane and the Y plane as the starting position of the angle, thereby establishing the polar coordinate system.

7. The method for adjusting the coaxiality of the bearing mounting holes on the aeroengine casing according to any one of claims 1-5, characterized in that In step S4, the condition for the coaxiality to meet the set requirements is: A F ≤0.01, A B ≤0.01; Among them, A F is the coaxiality of the front bearing mounting hole relative to the outer casing, and A B is the coaxiality of the rear bearing mounting hole relative to the outer casing.

8. The coaxiality adjustment method for the bearing mounting holes on the aero-engine casing according to any one of claims 1-4, characterized in that When measuring the coaxiality, the number of coaxiality measurement sections is not less than 3, and when repeating the measurement, ensure that the axial deviation of the measurement position is not greater than 2 mm.

9. The coaxiality adjustment method for the bearing mounting holes on the aero-engine casing according to any one of claims 1-4, characterized in that Before step S1, there is also a step: During the assembly process of the outer casing and the inner casing, all circumferentially evenly distributed tension bolts are tightened in a star sequence, gradually increasing the tightening torque, and the upper limit of the tightening torque is the middle value of the set torque range.

10. The coaxiality adjustment method for the bearing mounting holes on the aeroengine casing according to any one of claims 1-4, characterized in that Before step S1, there is also a step: Install the casing on a turntable or a three - coordinate measuring instrument.

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