A method for installing and detecting deep hole bushings of aircraft engines

Abstract

The present invention discloses a method for detecting the installation of a deep-hole bushing for an aircraft engine. The present invention adopts an impact measurement device, through which an impact force and a pressing force are applied to the bushing, and the displacement change before and after the force is applied is measured, thereby determining whether the bushing is installed in place. In addition, the present invention can also detect whether the bushing is skewed by measuring at multiple different locations. The present invention converts the method for determining whether the lower bushing is installed in place into measuring the installation distance and the plane difference, which can quickly and accurately detect the displacement and deflection of the bushing, solving the problem of low detection accuracy and efficiency when in-situ detecting the installation condition of a deep-hole bushing at a certain aircraft piston engine use site.

Description

Technical Field

[0001] This invention relates to the field of engine bushing installation and inspection technology, and more specifically, to a method for inspecting the installation of deep-hole bushings for aero-engines. Background Technology

[0002] The vertical shaft support of a certain aircraft piston engine transmission device is located between the upper bushing and the bushing of the accessory transmission device, such as... Figure 1 Below the spline of the vertical shaft is an outer cylindrical surface that supports the upper bushing of the rear cover, serving as the upper support for the vertical shaft. Below the bevel gear of the vertical shaft is another outer cylindrical surface that mates with the bushing on the rear cover, serving as the lower support for the vertical shaft. The bushing is pressed into the hole in the housing and fixed to the rear cover by two bolts. Its upper end face is the axial limiting surface of the vertical shaft. The bushing and the mounting hole in the housing are a transition fit; during assembly, the vertical shaft is first installed into the housing mounting hole, and then the bushing is pressed into the housing mounting hole. If the bushing is not installed properly or is slightly misaligned, it will cause abnormal stress on the bushing during operation, resulting in fatigue cracks.

[0003] The bushing serves as the lower support for the vertical shaft, on which a bevel gear is mounted. Confirming proper installation by disassembling and reinstalling the bushing using conventional methods is impractical when the engine is in its complete state. Such installation would be extremely difficult and could potentially damage the already assembled gear transmission mechanism. Therefore, an in-situ inspection method is considered. There are two ways in which the bushing may not be properly installed in the mounting holes of the engine casing:

[0004] (1) The bushing was not fully installed in the mounting hole of the casing;

[0005] (2) The bushing is installed at an angle in the mounting hole of the casing.

[0006] Therefore, it is necessary to measure the depth of the bushing in the mounting hole of the engine casing before and after striking it to determine whether the bushing is installed correctly, thereby ensuring the normal operation of the engine. CN202110938132.9 discloses an installation tool and method for an aero-engine rigid shaft bushing. The tool is made entirely of a cylindrical copper rod, with a fixed-length inspection mark on its surface. The inner end face of the cylindrical copper rod makes contact with the circular end face of the rigid shaft bushing, and the outer end face of the cylindrical copper rod serves as the striking surface. After the rigid shaft bushing presses against the engine casing boss, the installation requirements of the rigid shaft bushing are determined by judging whether the fixed-length inspection mark is aligned with the plane of the engine casing. The method of use is as follows: Insert the inner end of the cylindrical copper rod into the mounting hole of the attachment shaft until the inner end of the cylindrical copper rod contacts the circular end face of the attachment shaft bushing; use a rubber hammer to tap the outer end of the cylindrical copper rod to move the attachment shaft bushing towards the attachment housing until the attachment shaft bushing abuts against the attachment housing boss; check the relative position of the dimensional inspection mark on the cylindrical copper rod and the plane of the attachment housing to determine whether the dimensional inspection mark and the plane of the attachment housing are aligned; if aligned, it indicates that the installation of the attachment shaft bushing meets the requirements. However, in this aviation piston engine transmission device, when measuring in situ, the lower bushing mounting hole faces downwards, the space is limited and affected by the engine position and surrounding pipelines, and the following problems exist in measuring dimensions with a depth vernier caliper:

[0007] 1. Because the mounting hole of the lower bushing inside the accessory transmission housing faces downwards, it is blocked by pipelines and mounting brackets during the measurement process. The measurement position cannot be seen visually when measuring from bottom to top, and it is basically a blind measurement operation. The mounting surface of the lubricating pump is relatively narrow, and it is difficult to place the depth gauge stably and securely, which has a significant impact on the measurement accuracy.

[0008] 2. After the nylon rod impacts the bushing, the bushing quickly returns to its original position under the pressure of gravity and other gears, making it impossible to measure the actual position of the bushing and thus impossible to effectively determine whether the bushing is installed correctly.

[0009] 3. Interference from surrounding pipelines, whether due to impact or measurement of the lower bushing, can have a certain impact on the quality control of the measurement process.

[0010] Therefore, the installation and inspection of the lower bushing supported by the vertical shaft in the accessory transmission device is difficult. Summary of the Invention

[0011] The main technical problem to be solved by the present invention is to address the shortcomings of the existing technology in the in-situ inspection of the deep hole bushing installation of a certain aviation piston engine, which has low detection accuracy and efficiency. The present invention provides a method for inspecting the installation of deep hole bushings in aviation engines.

[0012] The objective of this invention is achieved through the following technical solution:

[0013] A method for inspecting the installation of deep-hole bushings in aero-engines, the method being based on an impact measuring device. The impact measuring device includes a base, an impact device mounted on the base, and a gauge holder. The base has mounting holes for the impact device, measuring holes for the gauge holder, and fixing holes for securing the base. The impact device includes an impact head and a screw. The screw is fitted onto the rod portion of the impact head, with one end of the screw contacting the head of the impact head. The outer wall of the screw is threaded and connected to the mounting holes. The gauge holder includes a holder body and a gauge head. The holder body is connected to the measuring holes, and the gauge head is mounted on the holder body.

[0014] The testing steps include:

[0015] S1. Install the base on the lower end face of the rear cover, and install the impact head and screw sleeve together on the base, while ensuring that the head of the impact head does not contact the bushing;

[0016] S2. Insert the meter holder into the measuring hole, with the end of the meter holder body contacting the bushing, and record the meter reading H1;

[0017] S3. Tap the rod of the impact head to make the head of the impact head fit into the bushing, and tighten the screw to keep the impact head and bushing in contact.

[0018] S4. Insert the meter holder into the measuring hole again, with the end of the meter holder body contacting the bushing, and record the meter reading H2;

[0019] S5. Determine whether the bushing is installed correctly based on the difference between the values ​​H2 and H1.

[0020] Furthermore, the base is provided with two or more measuring holes, and the installation of the bushing is determined by measuring at multiple different points to determine whether there is any misalignment.

[0021] Furthermore, a gasket is provided between the screw and the impact head to reduce friction between the screw and the impact head and protect the impact head.

[0022] Furthermore, the head of the impact indenter is provided with a groove to avoid the vertical axis protruding from the bushing.

[0023] Furthermore, the impact head is made of nylon to avoid damaging the bushing.

[0024] Furthermore, the values ​​H1 and H2 are the average values ​​of multiple measurements, respectively.

[0025] Furthermore, the difference between the plurality of measured values ​​is no greater than 0.02 mm.

[0026] Furthermore, when the impact head and the bushing are in contact, the impact head applies a force of 4 to 6 N·m to the bushing.

[0027] Furthermore, the gauge is zeroed before each measurement.

[0028] Furthermore, if the difference between the numerical values ​​H2 and H1 is not greater than 0.03 mm, it is determined that the bushing is installed in place.

[0029] Compared with existing technologies, the beneficial effects are:

[0030] This invention utilizes the characteristic of a bushing that fits tightly and flatly against the engine casing when properly installed. An impact measuring device applies impact and compression to the bushing, continuously applying a certain torque to accurately measure its initial and remeasured dimensions. By comparing the differences in measurements from multiple different measuring points and using the difference between the remeasured value H2 and the initial value H1 as a standard, the method for determining proper bushing installation is transformed into measuring the installation distance and plane difference. This allows for rapid and accurate detection of bushing displacement and misalignment, thus determining whether the bushing is properly installed. This invention enables efficient on-site, in-situ testing of engine bushings, improving work efficiency and shortening the testing cycle. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the transmission device structure;

[0032] Figure 2 This is a structural diagram of the impact measuring device;

[0033] Figure 3 This is a cross-sectional view of the impact measuring device.

[0034] Among them, 1-vertical shaft gear; 2-upper bushing; 3-lower bushing; 4-vertical shaft; 5-base; 6-impact head; 7-screw; 8-tablet holder; 9-shield. Detailed Implementation

[0035] The following examples further explain and clarify the invention, but the specific examples do not limit the invention in any way.

[0036] Example 1

[0037] This embodiment provides an impact measurement device for detecting the installation of deep-hole bushings in aero-engines, such as... Figures 2-3 The impact measuring device includes a base 5 and an impact device and a gauge holder 8 mounted on the base 5. The base 5 has a mounting hole for the impact device, the inner wall of which is threaded, and the mounting hole is opposite to the end of the vertical shaft 4. The base 5 also has a measuring hole. This measuring hole is a through hole and can be used to mount the gauge holder 8. The base 5 has circumferential fixing holes for fixing the base 5 to the bolts in the mounting hole of the lubricating pump in the accessory drive housing.

[0038] The impact device includes an impact head 6 and a screw 7. The impact head 6 is made of nylon and includes a head and a rod, with the rod passing through the screw 7. The screw 7 has a through hole in its center, allowing it to support and press the impact head 6. Its outer wall has threads that match the mounting hole. One end of the screw 7 contacts the head of the impact head 6, and a washer 9 is provided between them to reduce friction and protect the impact head 6.

[0039] The dial indicator frame 8 includes a frame body and a dial indicator head. The lower end face of the frame body serves as the measuring mating surface of the dial indicator, fitting snugly against the surface of the base 5 for measurement. Simultaneously, the frame body and the dial indicator clamp are connected via mounting holes and secured with screws. The dial indicator head is mounted on the frame body and is used to measure and display the distance between the lower bushing 3 and the base 5.

[0040] Example 2

[0041] This embodiment provides a method for detecting the installation of deep hole bushings in aero engines based on the impact measuring device described in Embodiment 1. The steps include:

[0042] S1. Install the base 5 on the lower end face of the rear cover, and extend the rod of the impact head 6 through the through hole of the screw 7. Connect and fix the base 5 to the transmission housing, and the head of the impact head 6 does not contact the lower bushing 3.

[0043] S2. Insert the zeroing gauge holder 8 into the measuring hole, with the lower end face of the gauge holder body in contact with the surface of the base 5, measure the distance between the lower bushing 3 and the base 5, record the gauge value, and obtain the initial value H1.

[0044] S4. Strike the rod of the impact head 6 to make the head of the impact head 6 fit against the lower bushing 3, and tighten the screw 7 to keep the impact head 6 applying a force of 5 N·m to the lower bushing 3.

[0045] S5. Insert the zeroing gauge 8 into the measuring hole again, record the value after applying torque, and calculate the average value to obtain the remeasured value H2.

[0046] S6. Determine whether the lower bushing 3 is installed in place based on the difference between the remeasured value H2 and the initial value H1. If the remeasured value H2 - the initial value H1 ≤ 0.03 mm, it indicates that the lower bushing 3 fits well with the end face of the casing hole and the lower bushing 3 is installed in place.

[0047] Example 3

[0048] This embodiment provides an impact measuring device for testing the installation of deep-hole bushings in aero-engines. The impact measuring device includes a base 5, an impact device mounted on the base 5, and a gauge 8. The base 5 has mounting holes for the impact device, with threads on the inner wall of the mounting holes, and the mounting holes are opposite to the end of the vertical shaft 4. The base 5 also has three measuring holes at different locations, with measuring holes 1, 2, and 3 located above the lower bushing 3. These measuring holes are through holes and can be used to mount the gauge 8. The base 5 has circumferential fixing holes for fixing the base 5 to the bolts in the mounting holes of the accessory drive gearbox lubricating pump.

[0049] The impact device includes an impact head 6 and a screw 7. The impact head 6 is made of nylon and includes a head and a rod. The head of the impact head 6 has a groove that fits with the vertical shaft 4 to avoid the protrusion of the vertical shaft 4 in the lower bushing 3. The rod of the impact head 6 passes through the screw 7. The screw 7 has a through hole in its center, allowing it to support and press the impact head 6. The outer wall has threads that match the mounting hole. One end of the screw 7 contacts the head of the impact head 6, and a washer 9 is provided between them to reduce friction between the screw 7 and the impact head 6 and protect the impact head 6.

[0050] The dial indicator stand 8 includes a stand body and a dial indicator head. The lower end face of the stand body serves as the measuring mating surface of the dial indicator, fitting snugly against the surface of the base 5 for measurement. Simultaneously, the stand body and the dial indicator clamp are connected together through mounting holes, and the dial indicator is secured with screws. The dial indicator head is mounted on the stand body for measurement.

[0051] Example 4

[0052] This embodiment provides a method for detecting the installation of deep hole bushings in aero engines based on the impact measuring device described in Embodiment 3. The steps include:

[0053] S1. Install the base 5 on the lower end face of the rear cover, and fit the head groove of the impact head 6 to the end of the vertical shaft 4. The through hole of the rod punch 7 extends out, and the base 5 is connected and fixed to the transmission housing. The head of the impact head 6 does not contact the lower bushing 3.

[0054] S2. Insert the zeroing gauge holder 8 into the measuring hole 1, so that the lower end face of the gauge holder body is in contact with the surface of the base 5, measure the distance between the lower bushing 3 and the base 5, and record the gauge reading.

[0055] S3. Use the gauge holder 8 to measure the values ​​in measuring holes 2 and 3 in sequence, and record the values ​​of the gauge head respectively. If the difference between the measured values ​​of the three points is not greater than 0.02mm, it indicates that the lower bushing 3 is installed without deviation. Calculate the average value to obtain the initial value H1.

[0056] S4. Strike the rod of the impact head 6 to make the head of the impact head 6 fit against the lower bushing 3, and tighten the screw 7 to keep the impact head 6 applying a force of 5 N·m to the lower bushing 3.

[0057] S5. Use the zeroing gauge holder 8 again to insert into measuring holes 1, 2 and 3 respectively, record the values ​​after applying torque, and calculate the average value to obtain the remeasured value H2;

[0058] S6. Determine whether the lower bushing 3 is installed in place based on the difference between the remeasured value H2 and the initial value H1. If the remeasured value H2 - the initial value H1 ≤ 0.02mm, it indicates that the lower bushing 3 fits well with the end face of the casing hole and the lower bushing 3 is installed in place.

[0059] Example 5

[0060] This embodiment provides an impact measuring device for testing the installation of deep hole bushings in aero engines. The difference between this embodiment and embodiment 3 is that the base 5 is also provided with four measuring holes at different locations. Three measuring holes, number 1, 2 and 3, are located above the lower bushing 3, and the other measuring hole, number 4, is located above the asbestos pad on the lower bushing 3.

[0061] The testing steps include:

[0062] S1. Install the base 5 on the lower end face of the rear cover, and fit the head groove of the impact head 6 to the end of the vertical shaft 4. The through hole of the rod punch 7 extends out, and the base 5 is connected and fixed to the transmission housing. The head of the impact head 6 does not contact the lower bushing 3.

[0063] S2. Insert the zeroing gauge holder 8 into the measuring hole 1, so that the lower end face of the gauge holder body is in contact with the surface of the base 5, measure the distance between the lower bushing 3 and the base 5, and record the gauge reading.

[0064] S3. Using gauge holder 8, measure the values ​​in measuring holes 2 and 3 sequentially, and record the gauge readings. The difference between the measurements at the three points should not exceed 0.02 mm, indicating that the lower bushing 3 is installed without misalignment. Calculate the average value to obtain the initial value H1. Simultaneously, use gauge holder 8 to measure the value in measuring hole 4 and obtain the value H.

[0065] S4. Strike the rod of the impact head 6 to make the head of the impact head 6 fit against the lower bushing 3, and tighten the screw 7 to keep the impact head 6 applying a force of 5 N·m to the lower bushing 3.

[0066] S5. Use the zeroing gauge holder 8 again to insert into measuring holes 1, 2 and 3 respectively, record the values ​​after applying torque, and calculate the average value to obtain the remeasured value H2; at the same time, measure measuring hole 4 to obtain the value H'.

[0067] S6. With the lower bushing 3 installed in place, under a force of 5 N·m, there is a compression of 0.01 to 0.02 mm between the numerical values ​​H' and H. If the difference between the remeasured value H2 and the initial value H1 is ≤0.03 mm, it indicates that the lower bushing 3 fits well with the end face of the casing hole, and the lower bushing 3 is installed in place.

[0068] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for inspecting the installation of deep-hole bushings in aero-engines, characterized in that, The method is based on an impact measuring device for detection. The impact measuring device includes a base, an impact device and a gauge holder mounted on the base. The base has mounting holes for mounting the impact device, measuring holes for measuring the gauge holder, and fixing holes for fixing the base. The impact device includes an impact head and a screw. The screw is fitted onto the rod of the impact head, and one end of the screw contacts the head of the impact head. The outer wall of the screw is threaded and connected to the mounting holes. The gauge holder includes a gauge holder body and a gauge head. The gauge holder body is connected to the measuring holes, and the gauge head is mounted on the gauge holder body. The testing steps include: S1. Install the base on the lower end face of the aircraft engine rear cover, and install the impact head and screw sleeve together on the base, while ensuring that the head of the impact head does not contact the bushing; S2. Insert the meter holder into the measuring hole, with the end of the meter holder body contacting the bushing, and record the meter reading H1; S3. Tap the rod of the impact head to make the head of the impact head fit into the bushing, and tighten the screw to keep the impact head and bushing in contact. S4. Insert the meter holder into the measuring hole again, with the end of the meter holder body contacting the bushing, and record the meter reading H2; S5. Determine whether the bushing is installed correctly based on the difference between the values ​​H2 and H1.

2. The method for testing the installation of deep-hole bushings in aero-engines according to claim 1, characterized in that, The base has two or more measuring holes.

3. The method for testing the installation of deep-hole bushings in aero-engines according to claim 1, characterized in that, A gasket is also provided between the screw and the impact head.

4. The method for testing the installation of deep-hole bushings in aero-engines according to claim 1, characterized in that, The head of the impact indenter is provided with a groove to avoid interference with the vertical shaft end of the aero-engine transmission device.

5. The method for testing the installation of deep-hole bushings in aero-engines according to claim 1, characterized in that, The impact indenter is made of nylon.

6. The method for testing the installation of deep-hole bushings in aero-engines according to claim 1, characterized in that, The values ​​H1 and H2 are the average values ​​of multiple measurements, respectively.

7. The method for testing the installation of deep-hole bushings in aero-engines according to claim 6, characterized in that, The difference between the multiple measured values ​​is no greater than 0.02 mm.

8. The method for testing the installation of deep-hole bushings in aero-engines according to claim 1, characterized in that, When the impact head and the bushing are in contact, the impact head applies a force of 4~6 N·m to the bushing.

9. The method for testing the installation of deep-hole bushings in aero-engines according to claim 1, characterized in that, All measurements on the meter stand are zeroed before measurement.

10. The method for testing the installation of deep-hole bushings in aero-engines according to claim 1, characterized in that, If the difference between the values ​​H2 and H1 is not greater than 0.03 mm, the bushing is determined to be installed in place.

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