A test method for spalling damage of aircraft engine bearings

Abstract

The present application provides a method for testing spalling damage of an aero-engine bearing, comprising: obtaining the spalling damage morphology according to the test requirements, and determining the spalling damage parameters, wherein the spalling damage parameters include the spalling area, the maximum spalling depth and the average spalling depth; using a hardness testing machine for loading, wherein the material and process treatment used for the indenter of the hardness testing machine are the same as those of the bearing ball, and the shape and size of the indenter are determined according to the spalling damage parameters; determining the location for preparing spalling damage on the bearing according to the location of the fault, determining the number of preparation damage points according to the spalling area, and determining the indenter used for each damage point according to the spalling depth; constructing a test fixture, and adjusting the relative position of the bearing and the indenter in conjunction with the upper and lower adjustment trays of the hardness testing machine; performing prefabrication on a test piece of the same material as the inner ring of the bearing to obtain prefabrication process parameters; fixing the bearing on the test fixture, and performing bearing spalling damage prefabrication using the prefabrication process parameters.

Description

Technical Field

[0001] The present application belongs to the technical field of aero-engine testing, and in particular relates to a method for testing aero-engine bearing spalling damage. Background Art

[0002] With the continuous development of aircraft engine technology, aircraft engines are moving towards high thrust-to-weight ratio, high reliability and long life.

[0003] As an important component of aircraft engines, bearings are subjected to high temperatures, high stresses and large sliding-rolling ratios during operation. Therefore, fatigue pitting, spalling, adhesion and gluing failures may occur on their contact surfaces. If the above failures occur at any point in the bearing, extremely serious consequences will occur.

[0004] Contact fatigue spalling is the most common failure mode of bearings. Inclusions and carbides in bearing steel, as well as the heat treatment quality and grinding process of bearing steel are all important factors affecting the fatigue spalling resistance of bearings.

[0005] In order to study the spalling problem of bearings, the prior art either removes the faulty parts to obtain the spalling defect bearings, or uses a bearing life tester to age the new bearings, hoping to produce the desired spalling defect bearings during the aging process. The test is usually accompanied by the use of laser equipment and electric spark preparation equipment to artificially create defects on the bearings, which has poor randomness and is prone to damage to the bearing surface due to high temperature processing.

[0006] This method is unpredictable, and the test process consumes a lot of manpower and material resources. Summary of the invention

[0007] The purpose of the present application is to provide a method for testing the spalling damage of an aircraft engine bearing to solve or alleviate at least one problem in the background technology.

[0008] The technical solution of the present application is: a method for testing the spalling damage of an aero-engine bearing, characterized in that the method comprises:

[0009] Acquire the spalling damage morphology according to the test requirements, and determine the spalling damage parameters according to the spalling damage morphology, wherein the spalling damage parameters include spalling area, maximum spalling depth and average spalling depth;

[0010] A hardness tester is used for loading, wherein the material of the indenter of the hardness tester is the same as that of the bearing ball, and the process of the indenter is the same as that of the bearing ball, and the shape and size of the indenter are determined according to the spalling damage parameter;

[0011] Determine the location of the spalling damage on the bearing according to the location of the fault, determine the number of damage points according to the spalling area, and determine the indenter used for each damage point according to the maximum spalling depth and the average spalling depth;

[0012] Constructing a test fixture, wherein the test fixture cooperates with the upper and lower adjustment trays of the hardness testing machine to adjust the relative positions of the bearing and the pressure head;

[0013] Select a suitable indenter according to the desired spalling damage morphology, and perform prefabrication on a test piece of the same material as the bearing inner ring. After prefabrication, compare the prefabricated spalling damage morphology with the ideal spalling damage morphology. According to the comparison results, adjust the size and shape of the indenter and the parameters of the testing machine to obtain the prefabrication process parameters.

[0014] The bearing is fixed on the test fixture and the bearing spalling damage is prefabricated using the prefabrication process parameters.

[0015] Furthermore, the spalling damage morphology is obtained through the spalling loss morphology of an existing faulty bearing, or through the spalling damage morphology of a past faulty bearing.

[0016] Furthermore, the hardness testing machine has at least a plurality of loading positions.

[0017] Furthermore, the shape of the pressure head includes a circular shape, a trapezoidal pressure head and an elliptical shape.

[0018] Furthermore, the spalling damage morphology is achieved by using a single or a combination of multiple indenters to achieve an ideal damage morphology.

[0019] Furthermore, the test fixture includes a mounting seat, a bearing outer ring support seat, a baffle, bolts and a base;

[0020] The bearing outer ring support seat has an arc-shaped groove, and the arc-shaped groove is used to cooperate with the bearing outer ring to enable the bearing to rotate in the circumferential direction;

[0021] The mounting seat is provided with a rectangular groove, and the bearing outer ring support seat is installed in the rectangular groove;

[0022] The baffle is arranged on the outside of the bearing outer ring support seat, and the bolt passes through the baffle and is connected to the mounting seat to clamp and fix the bearing outer ring support seat in the rectangular groove of the mounting seat;

[0023] The base has a plurality of stepped bosses in the circumferential direction, and the bosses are distributed at a certain angle. When the bearing is fixed to different steps, damage prefabrication at any angle in the radial direction of the bearing can be completed.

[0024] Furthermore, after the bearing spalling damage is prefabricated, it also includes:

[0025] The prefabricated bearing with spalling damage is installed in the engine for test run;

[0026] After the trial run, the spalling damage morphology of the bearing was compared with that of the same faulty parts by using instruments and equipment.

[0027] Furthermore, the instruments and equipment include a profilometer, a white light interferometer, an optical microscope and an X-ray photoelectron spectrometer.

[0028] The aircraft engine bearing spalling damage preparation test method provided in the present application can solve the damage preparation of aircraft engine bearings under laboratory conditions using an existing hardness testing machine. The process is easy to control, defects can be quantified, and there will be no impact of thermal processing on the bearings. It is economical and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0030] Figure 1 This is a flow chart of the aircraft engine bearing spalling damage test method of this application.

[0031] Figure 2 FIG. 1 is a schematic diagram of the spalling damage morphology and spalling damage parameters according to an embodiment of the present application.

[0032] Figure 3 Schematic diagram of the types of indenters used in this application.

[0033] Figure 4 FIG. 1 is a schematic diagram of the location of spalling damage according to an embodiment of the present application.

[0034] Figure 5 Schematic diagram of the test fixture of this application.

[0035] Figure 6 Schematic diagram of the test fixture supporting the outer ring of the bearing in this application.

[0036] Figure 7 This is a schematic diagram of the base angle adjustment of this application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0038] like Figure 1 As shown, the aircraft engine bearing spalling damage test method provided by the present application comprises the following steps:

[0039] 1) Determine the spalling damage morphology

[0040] The spalling damage morphology can be obtained according to the test requirements. The spalling damage morphology can be obtained by the spalling loss morphology of the existing faulty bearing, or by referring to the spalling damage morphology of the past bearing spalling failure. Figure 2 The spalling damage morphology required in one embodiment of the present application is shown. According to the spalling damage morphology, the spalling area S, the maximum spalling depth H and the average spalling depth h to be obtained can be determined, which are collectively referred to as spalling damage parameters hereinafter. The above spalling damage parameters can be measured by optical microscopes, profilometers and other equipment.

[0041] It should be noted that the spalling area S of the spalling damage morphology can be determined using the image processing software of an optical microscope, and the maximum spalling depth H and the average spalling depth h of the bearing damage site can be measured using a profilometer.

[0042] 2) Determine the test equipment and pressure head

[0043] In this application, a hardness testing machine is used for loading. The hardness testing machine is a Rockwell hardness testing machine. The Rockwell hardness testing machine has three gears of 60kg, 100kg, and 150kg. The indentation of the Rockwell hardness testing machine is small, and the pressure head and the holding time can be replaced according to actual needs to produce different degrees of damage indentations, and ensure that the degree of damage is the same under the same position parameters.

[0044] The material used for the pressure head is the same as the bearing ball material.

[0045] The shape of the indenter is determined according to the spalling damage parameters obtained above. In a preferred embodiment, a variety of indenters can be mixed and used to achieve an ideal damage state. For example, when the spalling area S is large and the average spalling depth h is small, a larger circular indenter can be used; if the spalling area S is large and the average spalling depth h is also large, a larger circular indenter can be used first to damage, and then a smaller circular indenter can be used to perform secondary damage on the area with a larger spalling depth.

[0046] like Figure 3 The three types of pressure head shapes listed in this embodiment of the present application are shown, including a circular pressure head, a trapezoidal pressure head and an elliptical pressure head. It can be understood that the pressure shapes used in the present application include but are not limited to the above three shapes.

[0047] The heat treatment process and surface roughness of the pressure head are the same or similar to those of the bearing ball material.

[0048] 3) Determine the location of spalling damage

[0049] Determine the location of the spalling damage on the bearing according to the location of the fault, and determine the number of damage points to be prepared according to the spalling damage area. At the same time, determine the indenter used for each damage point according to the damage depth and mark them.

[0050] like Figure 4 a~ Figure 4 d is a schematic diagram of the location of the spalling damage in an embodiment of the present application. According to the failure analysis, the damage characteristics of the failure are as follows: the total spalling area S is 50 mm 2 , arranged in a rectangular shape along the circumference of the bearing, with a maximum spalling depth of 4 mm and an average spalling depth of 2 mm. According to the above parameters, a spherical indenter (with a diameter of 5 mm) and a square indenter were selected for damage preparation.

[0051] according to Figure 4 Schematic diagram: Damage preparation is performed in the damage area to be determined, and a spherical indenter is used to perform damage preparation once at a certain angle, and finally the entire damage area is covered. A square indenter is used to select several locations for damage preparation of the maximum depth.

[0052] 4) Construction of test fixture

[0053] like Figures 5 to 7 As shown, the test fixture includes a mounting seat 21, a bearing outer ring support seat 22, a baffle 23, a bolt 24 and a base 25. The bearing outer ring support seat 22 has an arc groove, which is used to match the bearing outer ring 1 so that the bearing can rotate in the circumferential direction, which is convenient for adjusting the position to be prepared for damage, and the part in contact with the bearing is relatively smooth, which will not cause damage to the bearing outer ring. The mounting seat 21 has a rectangular groove, and the bearing outer ring support seat 22 is installed in the rectangular groove. The baffle 23 is arranged on the outside. The bolt 24 passes through the baffle 23 and is connected to the mounting seat 21 to clamp the bearing outer ring support seat 22 in the rectangular groove of the mounting seat 21.

[0054] The base 25 has a plurality of stepped bosses 251A to 256B in the circumferential direction. The bosses are distributed at certain angles. When the bearing is fixed to different steps, damage prefabrication at any angle in the radial direction of the bearing can be completed. For example, bosses 251A and 251B form a support for the horizontal angle of the bearing, and bosses 252A and 252B form a support for the horizontal deflection of the bearing by 10 degrees. The rest is not repeated. The relative position of the bearing and the pressure head can be accurately adjusted by using the test fixture in conjunction with the upper and lower adjustable trays of the hardness machine.

[0055] In one embodiment of the present application, the base 25 can be made of ordinary steel material, which can effectively support the bearing, and can fix the bearing to the test bench through a limiting device, and ensure that the bearing remains stable during the prefabrication process.

[0056] 5) Preliminary test

[0057] According to the defect morphology you want to prefabricate, select a suitable indenter and prefabricate it on a test piece made of the same material as the bearing inner ring. After prefabrication, use a profilometer to measure the indentation profile of the test piece surface and the inner surface of the pit to determine the deformation of the pit edge and compare the result with the defect morphology you want to prefabricate. According to the comparison results, adjust the indenter and the gear position of the testing machine to optimize the parameters of the test process.

[0058] 6) Formal test

[0059] Fix the bearing on the test fixture and use the test parameters and pressure head optimized in the previous test to preform damage.

[0060] 7) Post-test processing

[0061] After the test, the outer ring raceway surface and the inner surface of the pit were measured using instruments to determine the deformation of the pit edge. The bearings after the test were analyzed using instruments including profilometers, white light interferometers, optical microscopes (OM), and X-ray photoelectron spectrometers (XPS) to observe the damage preparation.

[0062] 8) Commissioning test

[0063] The prepared damaged bearings were installed in the engine for test runs to verify the spalling damage effect of the prepared bearings. After the test, the bearings were microscopically analyzed with the help of profilometers, white light interferometers, optical microscopes (OM), X-ray photoelectron spectrometers (XPS) and other analytical methods, and the results were compared with the spalling morphology of the faulty parts.

[0064] The aircraft engine bearing spalling damage preparation test method provided in the present application can solve the damage preparation of aircraft engine bearings under laboratory conditions using an existing hardness testing machine. The process is easy to control, defects can be quantified, and there will be no impact of thermal processing on the bearings. It is economical and convenient.

[0065] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for testing the spalling damage of an aircraft engine bearing, characterized in that: The method comprises: Acquire the spalling damage morphology according to the test requirements, and determine the spalling damage parameters according to the spalling damage morphology, wherein the spalling damage parameters include spalling area, maximum spalling depth and average spalling depth; A hardness tester is used for loading, wherein the material of the indenter of the hardness tester is the same as that of the bearing ball, and the process of the indenter is the same as that of the bearing ball, and the shape and size of the indenter are determined according to the spalling damage parameter; Determine the location of the spalling damage on the bearing according to the location of the fault, determine the number of damage points according to the spalling area, and determine the indenter used for each damage point according to the maximum spalling depth and the average spalling depth; A test fixture is constructed, wherein the test fixture cooperates with the upper and lower adjustment trays of the hardness tester to adjust the relative positions of the bearing and the pressure head, wherein the test fixture comprises a mounting seat (21), a bearing outer ring support seat (22), a baffle (23), a bolt (24) and a base (25), wherein the bearing outer ring support seat (22) has an arc groove, wherein the arc groove is used to cooperate with the bearing outer ring (1) so that the bearing rotates in a circumferential direction, and wherein the mounting seat (21) has a rectangular groove, wherein the bearing outer ring support seat ( The bearing outer ring support seat (22) is installed in the rectangular groove, the baffle plate (23) is arranged on the outside of the bearing outer ring support seat (22), the bolt (24) passes through the baffle plate (23) and is connected to the mounting seat (21) to clamp and fix the bearing outer ring support seat (22) in the rectangular groove of the mounting seat (21), and the base (25) has a plurality of stepped bosses in the circumferential direction, and the bosses are distributed at a certain angle. When the bearing is fixed to different steps, damage prefabrication at any angle in the radial direction of the bearing can be completed; Select a suitable indenter according to the desired spalling damage morphology, and perform prefabrication on a test piece of the same material as the bearing inner ring. After prefabrication, compare the prefabricated spalling damage morphology with the ideal spalling damage morphology. According to the comparison results, adjust the size and shape of the indenter and the parameters of the testing machine to obtain the prefabrication process parameters. The bearing is fixed on the test fixture and the bearing spalling damage is prefabricated using the prefabrication process parameters.

2. The aircraft engine bearing spalling damage test method according to claim 1, characterized in that: The spalling damage morphology is obtained through the spalling loss morphology of an existing faulty bearing, or through the spalling damage morphology of a past faulty bearing.

3. The aircraft engine bearing spalling damage test method according to claim 1, characterized in that: The hardness testing machine has at least a plurality of loading gears.

4. The aircraft engine bearing spalling damage test method according to claim 1, characterized in that: The shapes of the pressure head include circular, trapezoidal and elliptical.

5. The aircraft engine bearing spalling damage test method according to claim 4, characterized in that: The spalling damage morphology is achieved by using a single or a combination of multiple indenters to achieve an ideal damage morphology.

6. The aircraft engine bearing spalling damage test method according to claim 1, characterized in that: After the bearing spalling damage is preformed, it also includes: The prefabricated bearing with spalling damage is installed in the engine for test run; After the trial run, the spalling damage morphology of the bearing was compared with that of the same faulty parts by using instruments and equipment.

7. The aircraft engine bearing spalling damage test method according to claim 6, characterized in that: The instruments and equipment include a profilometer, a white light interferometer, an optical microscope and an X-ray photoelectron spectrometer.

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