Assembly method of aircraft engine shaft nut

Abstract

The present invention provides an assembly method for an aircraft engine shaft nut, and relates to the technical field of aircraft engines. The assembly method for the aircraft engine shaft nut specifically includes the following steps: S1. Nut selection, selecting engine shaft nuts and bolts of appropriate sizes according to the aircraft engine model, checking whether the shapes and dimensional accuracy of the nuts and bolts related to assembly are qualified, and checking whether there is deformation or damage, S2. Assembly alignment, S3. Lubricant application, S4. Torque loading, S5. Bolt length detection, S6. Nut detection. By using a pneumatic or electric screwdriver to reinforce the nut and using a two-step loading method to avoid thread adhesion caused by excessive screwing speed and rapid temperature rise during assembly, at the same time, by using a pneumatic or electric screwdriver to reinforce the nut, it is beneficial to ensure that the maximum torque can be provided to the nut during assembly, reduce the operating difficulty and labor intensity of the processing personnel, and improve the work efficiency of the processing personnel.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engines, in particular to an assembly method for a shaft nut of an aero-engine. Background Art

[0002] Self-locking nuts are a type of metal part that uses various closing processes to deform the threaded hole at the tail of the nut. When the bolt is screwed into the tail of the nut, an interference fit is generated to achieve a self-locking function. Self-locking nuts are used in large quantities as threaded connectors in new-generation aircraft engines due to their reliable anti-vibration and anti-loosening functions and reusability. As self-locking nuts are connectors, almost all nuts have torque requirements for installation. The assembly and disassembly torque of nuts for small and medium-sized engines is approximately 5-2000N.m. Usually, during the assembly process of the nut, a torque wrench is used to set the torque value of the torque wrench according to the process torque requirements of the nut installation to achieve the torque requirements of the nut.

[0003] Generally speaking, a torque of 5-200 is easily achieved with a torque wrench, but it is very difficult to operate a large torque above 200N.m, especially above 1000N.m, which requires 2-3 people using a 1.2m long torque wrench to operate. The labor intensity is high and the efficiency is low. It is very easy to cause the nut to slip. Moreover, since a large torque nut requires a large force when tightening, it is also easy to cause changes in the coaxiality, accuracy and other parameters of other related components, resulting in the engine accuracy not meeting the requirements. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In response to the shortcomings of the existing technology, the present invention provides an assembly method for aircraft engine shaft nuts, which solves the problem that the existing nuts are labor-intensive and inefficient during installation, and are very likely to cause the nuts to slip. In addition, since nuts with high torque require a large force when tightening, it is also easy to cause changes in the coaxiality, accuracy and other parameters of other related components, thereby causing the engine accuracy to fail to meet the requirements.

[0006] (2) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for assembling an aero-engine shaft nut, specifically comprising the following steps:

[0008] S1. Nut selection

[0009] Select the appropriate size of engine shaft nuts and bolts according to the aircraft engine model, check whether the shape and dimensional accuracy of the nuts and bolts related to assembly are qualified, check for deformation and damage, and mark the corresponding nuts and bolts to prevent incorrect installation. Perform preliminary assembly of the bolts and nuts;

[0010] S2. Assembly alignment

[0011] Clean the installation location and use two dial indicators on the end face of the installation location. The two dial indicators are symmetrically set at equal distances from the shaft center to eliminate the influence of axial movement on the end face measurement reading. Ensure that the nut is perpendicular to the axis of the engine installation location and that the axis between the bolt and the nut is aligned and not tilted.

[0012] S3. Apply lubricant

[0013] Clean the thread surfaces of the bolts and nuts to ensure they are clean, burr-free, and apply grease to the mating thread surfaces of the bolts and nuts for lubrication;

[0014] S4. Torque loading

[0015] At room temperature, assemble the nut onto a pneumatic or electric screwdriver and tighten the nut using the cross-cross method according to the specified torque. The torque loading is performed in two steps: the first tightening is 50% of the design tightening torque value, and the second tightening is 100% of the design tightening torque value.

[0016] S5. Bolt length detection

[0017] Use the thread integrated scanner measurement method to detect the exposed length of the bolt after installation to ensure that the bolt is exposed for at least twice the pitch of the nut or other internal threaded parts;

[0018] S6. Nut inspection

[0019] Use a three-coordinate measuring machine combined with a three-needle measurement method to check whether the self-locking torque of the nut meets the use requirements. The minimum self-locking torque during nut assembly should not be lower than the use limit value of the nut self-locking torque, otherwise the self-locking nut should be replaced with a new one.

[0020] Preferably, in S1, the bolts and nuts are subjected to cold cycle inspection and fluorescent inspection. If the roughness requirements of the mating surfaces of the bolts and nuts are difficult to meet, a gasket needs to be added between the mating surfaces of the nuts and bolts.

[0021] Preferably, in S1, if the bolts and nuts are cracked, deformed or severely scratched, they should be stopped from use.

[0022] Preferably, in S2, before performing assembly alignment, the bolt holes should be checked to see if they are clean and have no burrs, and the planes where the connected parts contact the bolts and nuts should be checked to see if they are perpendicular to the bolt holes. At the same time, the tightness of the bolts and nuts should also be checked.

[0023] Preferably, in S4, the maximum no-load speed of the pneumatic or electric screwdriver is 360 rpm.

[0024] Preferably, in said S4, the torque is loaded in the final approach stage and the rotation speed is reduced so that the parts are not screwed into place too quickly.

[0025] Preferably, in S5, the bolt length detection cannot exceed the maximum tightening torque value to ensure that the bolt is fully exposed.

[0026] Preferably, in S6, the self-locking torque is not allowed to be corrected by twisting and deforming the locking device or amplifying the tapping screw.

[0027] (3) Beneficial effects

[0028] The present invention provides an assembly method for an aircraft engine shaft nut. It has the following beneficial effects:

[0029] 1. The present invention provides an assembly method for an aircraft engine shaft nut. Compared with the existing nut assembly method, the nut assembly method uses a pneumatic or electric screwdriver to reinforce the nut and adopts a two-step loading method to avoid thread adhesion caused by excessively fast screwing speed and rapid temperature rise during assembly. At the same time, reinforcing the nut by a pneumatic or electric screwdriver is conducive to ensuring that the maximum torque can be provided to the nut during assembly, reducing the operating difficulty and labor intensity of the processing personnel and improving the work efficiency of the processing personnel.

[0030] 2. The present invention provides an assembly method for aircraft engine shaft nuts. Compared with the existing nut assembly method, the nut assembly method detects the bolt length and thread after the nut is installed, thereby avoiding the situation where the minimum self-locking torque during nut assembly is lower than the nut self-locking torque usage limit value or exceeds the maximum tightening torque value due to excessive or insufficient torque after the nut is installed by a pneumatic or electric screwdriver, thereby improving the stability and safety of the nut after installation. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] Example:

[0033] An embodiment of the present invention provides a method for assembling an aircraft engine shaft nut, which specifically includes the following steps:

[0034] S1. Nut selection

[0035] Select the appropriate size of engine shaft nuts and bolts according to the aircraft engine model, check whether the shape and dimensional accuracy of the nuts and bolts related to assembly are qualified, check for deformation and damage, and mark the corresponding nuts and bolts to prevent incorrect installation. Perform preliminary assembly of the bolts and nuts to ensure the assembly effect of the bolts and nuts;

[0036] S2. Assembly alignment

[0037] Clean the installation location and use two dial indicators on the end face of the installation location. The two dial indicators are symmetrically set at equal distances from the center of the shaft to eliminate the influence of axial movement on the end face measurement reading. Ensure that the nut is perpendicular to the axis of the engine installation location and that the axis between the bolt and the nut is aligned and not tilted. This is conducive to ensuring the stability of the bolt and nut connection and preventing the nut from loosening after long-term use.

[0038] S3. Apply lubricant

[0039] Clean the thread surfaces of the bolts and nuts to ensure they are clean, burr-free, and apply grease to the mating thread surfaces of the bolts and nuts to improve lubrication and prevent the nuts from rusting due to prolonged contact with air.

[0040] S4. Torque loading

[0041] At room temperature, assemble the nut onto a pneumatic or electric screwdriver and tighten the nut using the cross-cross method according to the specified torque. The torque loading should be loaded in two steps: the first tightening should be 50% of the designed tightening torque value, and the second tightening should be 100% of the designed tightening torque value to avoid damage to the nut caused by excessive torque at the moment.

[0042] S5. Bolt length detection

[0043] The exposed length of the bolt after installation is tested by the thread integrated scanner measurement method to ensure that the bolt is exposed at least twice the pitch of the nut or other internal threaded parts, ensuring that the nut still has a certain strength after installation;

[0044] S6. Nut inspection

[0045] Use a three-coordinate measuring machine combined with a three-needle measurement method to check whether the self-locking torque of the nut meets the use requirements. The minimum self-locking torque during nut assembly should not be lower than the use limit value of the nut self-locking torque. Otherwise, the self-locking nut should be replaced with a new one to ensure that the bolt and nut can be used normally after installation.

[0046] In S1, the bolts and nuts are subjected to cold cycle inspection and fluorescent inspection. If the roughness requirements of the bolt and nut mating surfaces are difficult to meet, a gasket needs to be added between the nut and the bolt mating surfaces to avoid damage between the nut end face and the bolt and increase the service life of the nut. In S1, if the bolts and nuts are cracked, deformed or severely scratched, they should be stopped from use to ensure the safety of the engine. In S2, before assembly and centering, the bolt holes should be checked for cleanliness and burrs, and the contact planes of the connected parts with the bolts and nuts should be checked to see if they are perpendicular to the bolt holes. At the same time, the tightness of the bolts and nuts should also be checked. This helps ensure the assembly effect of bolts and nuts during assembly and reduces wear of bolts and nuts during use. In S4, the maximum no-load speed of the pneumatic or electric screwdriver is 360 rpm, which helps avoid adhesion due to increased nut temperature. In S4, the torque is loaded in the final approach stage and the speed should be reduced so that the parts are not screwed into place too quickly. In S5, the bolt length detection cannot exceed the maximum tightening torque value to ensure that the bolt is fully exposed. In S6, the self-locking torque is not allowed to be corrected by twisting the locking device or enlarging the tapping screw. This helps further ensure the service life of the bolt after assembly and improve the safety of engine use.

[0047] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for assembling an aero-engine shaft nut, characterized in that: The specific steps include: S1. Nut selection Select engine shaft nuts and bolts of appropriate sizes based on the aircraft engine model. Check the shape and dimensional accuracy of the nuts and bolts related to assembly to ensure they meet the requirements. Check for deformation and damage. Mark the corresponding nuts and bolts to prevent misassembly. Perform cold cycle inspection and fluorescence inspection on the nuts and bolts. If the mating surfaces of the nuts and bolts cannot meet the roughness requirements, add a gasket between the mating surfaces of the nuts and bolts, and perform preliminary assembly of the nuts and bolts. S2. Assembly alignment Before assembling and aligning, check whether the bolt holes are clean and have no burrs. Check whether the contact planes of the connected parts with the bolts and nuts are perpendicular to the bolt holes. At the same time, check the tightness of the bolts and nuts. Clean the installation location. Use two dial indicators on the end face of the installation location. The two dial indicators are symmetrically set at equal distances from the center of the shaft to eliminate the influence of axial movement on the end face measurement readings. Ensure that the nut is perpendicular to the axis of the engine installation location and that the axis between the bolt and nut is aligned and not tilted. S3. Apply lubricant Clean the thread surfaces of the bolts and nuts to ensure they are clean, burr-free, and apply grease to the mating thread surfaces of the bolts and nuts for lubrication; S4. Torque loading At room temperature, assemble the nut onto a pneumatic or electric screwdriver and tighten the nut using the cross-cross method according to the specified torque. The torque loading is performed in two steps: the first tightening is 50% of the design tightening torque value, and the second tightening is 100% of the design tightening torque value. S5. Bolt length detection Use the thread integrated scanner measurement method to detect the exposed length of the bolt after installation to ensure that the bolt is exposed for at least twice the pitch of the nut or other internal threaded parts; S6. Nut inspection Use a three-coordinate measuring machine combined with a three-needle measurement method to check whether the nut self-locking torque meets the use requirements. The minimum self-locking torque during nut assembly should not be lower than the nut self-locking torque use limit value, otherwise the self-locking nut should be replaced with a new one.

2. The method for assembling an aircraft engine shaft nut according to claim 1, characterized in that: In S1, if the bolts and nuts are cracked, deformed or severely scratched, they should be discontinued from use.

3. The method for assembling an aircraft engine shaft nut according to claim 1, characterized in that: In the S4, the maximum no-load speed of the pneumatic or electric screwdriver is 360 rpm.

4. The method for assembling an aircraft engine shaft nut according to claim 1, characterized in that: In S4, the torque is applied in the final approach stage and the rotation speed is reduced so that the parts are not screwed into place too quickly.

5. The method for assembling an aircraft engine shaft nut according to claim 1, characterized in that: In S5, the bolt length detection cannot exceed the maximum tightening torque value to ensure that the bolt is fully exposed.

6. The method for assembling an aircraft engine shaft nut according to claim 1, characterized in that: In S6, the self-locking torque is not allowed to be corrected by twisting and deforming the locking device or amplifying the tapping screw.