A method for testing the rolling contact fatigue performance of GCr15 bearing steel used for manufacturing high-speed ceramic hybrid bearings

Abstract

The application relates to the field of service behavior research of machine tool bearing materials, in particular to a method for testing the rolling contact fatigue performance of GCr15 bearing steel used for manufacturing high-speed ceramic hybrid bearings. The testing method simulates the actual high-speed ceramic hybrid bearing material, and corresponding GCr15 bearing steel and ceramic rolling body material are selected. The bearing steel to be tested is processed into a bearing steel rod sample with a diameter of 12 mm and a length of 120 mm, and the ceramic rolling body material is processed into a ceramic ball with a diameter of 12.7 mm. A ball-rod type rolling contact fatigue test is carried out, and the contact fatigue life of the bearing steel is estimated by using the fixed number of cut-off method. The contact stress cycle cut-off value can be set as 2*10 8 , the contact stress value is 5 GPa, and the rotating speed of the bearing steel rod is 5000 rpm. The testing method of the application is close to the service working condition of the actual machine tool ceramic hybrid bearing, and can more reliably evaluate the rolling contact fatigue life of the bearing steel.

Description

Technical Field

[0001] This invention relates to the field of rolling contact fatigue service behavior evaluation of GCr15 bearing steel, and particularly to the evaluation of rolling contact fatigue service behavior of high-end machine tool bearings. Specifically, it is a method for testing the rolling contact fatigue performance of GCr15 bearing steel used in the manufacture of high-speed ceramic hybrid bearings. Background Technology

[0002] As crucial equipment for machining precision parts, the precision of the spindle bearings in high-end precision machine tools is closely related to the quality of the machined parts. Bearings operate in relatively harsh environments during service, significantly impacting their lifespan. Therefore, the precision lifespan and fatigue life of high-end precision machine tool bearings are of paramount concern. Figure 4 As shown, rolling bearings are one of the most common core basic components in mechanical equipment. The basic structure of a rolling bearing consists of a left seal 13, an outer ring 14, rolling elements 15, a cage 16, an inner ring 17, and a right seal 18. The rolling elements and the inner and outer rings are the most prone to failure and are the key factors that determine the overall performance of the bearing.

[0003] During bearing service, sliding friction wear and rolling contact fatigue are the two most common causes of failure. This invention simulates the rolling contact fatigue between the rolling elements and the inner and outer rings. It uses material-grade GCr15 bearing steel to rub against the ceramic rolling elements in an actual bearing to evaluate the rolling contact fatigue performance of GCr15 bearing steel.

[0004] like Figure 1 As shown, the rolling contact fatigue testing machine is a testing device that can simulate the rolling contact fatigue behavior of rolling elements and inner and outer rings in actual bearings. During the test, a ball-and-bar type rolling contact fatigue testing machine is used, with weights applied and levers adjusted for balance. Based on the actual bearing contact stress, Hertzian contact stress is used to calculate the different stresses between the bearing steel bar sample and the ceramic rolling elements by applying different weights. Then, rolling contact fatigue tests are performed, and finally, the rolling contact fatigue performance of GCr15 bearing steel is obtained. This testing device can serve as a good method for simulating the structure, materials, and operating conditions of ceramic hybrid bearings used in high-end machine tools. It is of great significance for testing the rolling contact fatigue performance of GCr15 bearing steel, studying fatigue mechanisms, and selecting materials.

[0005] Current domestic reports on rolling contact fatigue performance mostly employ four-ball testing machines, which are cumbersome for sample fabrication. Common bearing bench tests, due to numerous influencing factors, can only barely assess the service performance of bearing components and cannot obtain information on the rolling contact fatigue performance of GCr15 bearing steel. Ball-and-bar testing machines offer simpler sample fabrication, and the ceramic rolling elements can directly utilize materials from actual bearings or ceramic balls.

[0006] In addition, there are some tests and methods specifically for the rolling contact fatigue performance of GCr15 bearing steel. However, these methods have drawbacks, such as the inability to change the lubrication conditions, friction pair, and cage materials in the test conditions according to the actual situation of high-end precision machine tool bearings. Therefore, they cannot provide a reliable evaluation of the rolling contact fatigue performance of GCr15 bearing steel.

[0007] Finally, existing evaluation methods do not comprehensively consider the impact of contact fatigue cycle life and the morphological changes of GCr15 bearing steel during rolling contact fatigue on precision life. Therefore, the evaluation of GCr15 bearing steel is no longer applicable to the development of high-end precision machine tools.

[0008] Therefore, there is an urgent need to develop a testing method for the rolling contact fatigue performance of GCr15 bearing steel used in high-end machine tools, which is also simple to manufacture, easier to operate, and inexpensive. This device can easily evaluate the rolling contact fatigue life between material-grade GCr15 bearing steel and actual ceramic rolling elements used in bearings using a conventional ball-and-bar testing machine. Summary of the Invention

[0009] The purpose of this invention is to provide a method for testing the rolling contact fatigue performance of GCr15 bearing steel used in the manufacture of high-speed ceramic hybrid bearings, which solves the problems of existing methods that mostly use bench tests, resulting in high costs and many influencing factors, and cannot directly obtain the rolling contact fatigue life.

[0010] The technical solution of this invention is:

[0011] A method for testing the rolling contact fatigue properties of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings, the specific steps of which are as follows:

[0012] a. Material selection: Simulate actual high-speed ceramic hybrid bearing materials, and select appropriate GCr15 bearing steel and ceramic rolling element materials;

[0013] b. The GCr15 bearing steel to be tested is processed into a bearing steel bar sample with a diameter of 12mm and a length of 120mm. The ceramic rolling element material is processed into a ceramic ball with a diameter of 12.7mm. The precision grade is consistent with the precision grade of the ceramic rolling element in the actual bearing.

[0014] c. Conduct ball-and-bar rolling contact fatigue tests, and use the constant-number truncation method to estimate the contact fatigue life of the bearing steel. The contact stress cycle truncation value is set to 2 × 10⁻⁶. 8 The contact stress value is 5 GPa, the rotational speed of the bearing steel bar sample is 5000 rpm, and the grease used in the actual bearing is selected for lubrication.

[0015] The method for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings, using a ball-and-bar type rolling contact fatigue testing machine, mainly includes: a limiting plate, an upper thrust bearing, an upper conical ring base, a GCr15 bearing steel bar, an upper conical ring, ceramic rolling elements, a column, a lower conical ring, a cage, a lower conical ring base, a lower thrust bearing, and a fixed plate platform. The specific structure is as follows:

[0016] Two parallel columns are vertically mounted on a horizontal fixed platform. A GCr15 bearing steel bar is vertically positioned between the two columns. The upper thrust bearing, upper conical ring base, upper conical ring, lower conical ring, lower conical ring base, and lower thrust bearing are sequentially mounted on the GCr15 bearing steel bar from top to bottom. The GCr15 bearing steel bar is connected to the inner rings of the upper and lower thrust bearings respectively. The inner surfaces of the upper and lower conical rings are annular conical surfaces and correspond to each other. The upper conical ring is embedded in the central hole of the upper conical ring base, and the lower conical ring is embedded in the central hole of the lower conical ring base. A cage and ceramic rolling elements are set between the upper and lower conical rings. The three ceramic rolling elements are evenly mounted on the cage. The upper conical ring is loaded downwards through its upper surface, and the inner surface of the upper conical ring applies pressure to the ceramic rolling elements. The lower conical ring is loaded upwards through its lower surface, and the inner surface of the lower conical ring applies pressure to the ceramic rolling elements.

[0017] Three holes are made on the horizontal limiting plate. The holes on both sides correspond to and match the columns, and the hole in the middle corresponds to and matches the GCr15 bearing steel rod. After assembly, the limiting plate is fitted onto the two columns and the GCr15 bearing steel rod, and slides with them. During testing, the upper end of the GCr15 bearing steel rod is connected to the rotating spindle, which is driven by a motor or electric spindle. The GCr15 bearing steel rod rotates at high speed under the drive of the spindle. The rotation of the GCr15 bearing steel rod causes the ceramic rolling elements to rotate on their own axis and revolve around the bearing steel rod, thus simulating the motion of the ceramic rolling elements in an actual bearing.

[0018] The method for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings, based on the exploration of the rolling contact fatigue testing machine, determines the roughness of the GCr15 bearing steel sample bar to be 0.02 μm.

[0019] The method described above for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings involves measuring 40mm from one end of the selected GCr15 bearing steel bar and clamping it in a fixture. This test method is repeated ten times on a single GCr15 bearing steel bar.

[0020] The method described above for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings obtains the fatigue life of GCr15 bearing steel by means of a constant-truncation calculation method after the rolling contact fatigue test, thus directly simulating the fatigue life of the actual bearing.

[0021] The method described above for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings involves, based on the actual service conditions of the bearing, the rolling contact fatigue testing machine's loading spindle is pushed by weights and levers. By using weights for loading and adjusting the lever balance, different weights are added to the lever, and Hertzian contact stress is used to calculate different contact stresses, which are consistent with the actual bearing contact stress.

[0022] The method described above for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings involves fixing the dimensions of the bearing steel bar sample and the rolling element, and replacing the bearing steel bar sample and the rolling element with different materials.

[0023] The method for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings, based on actual service conditions, directly selects engineering grease lubrication conditions for rolling contact fatigue testing of GCr15 bearing steel.

[0024] The method described herein is to test the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings, and to conduct rolling contact fatigue experiments and observe the morphology of the surface and cross-section of the GCr15 bearing steel after the test.

[0025] The method described above for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings uses material-grade GCr15 bearing steel to simulate the rolling contact fatigue between rolling elements and raceways in actual bearings.

[0026] The design concept of this invention:

[0027] This invention provides a method for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings. This method can simulate the actual service conditions of bearings, and the materials of the cage and cone ring can be changed according to the actual conditions. The fatigue and precision life of the material can be accurately and quickly analyzed through the experimental results.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] 1. Based on the dimensions of the 12mm diameter GCr15 bearing steel and the 12.7mm diameter ceramic rolling elements, upper and lower cone rings, and cage, materials of the same dimensions can be used for replacement.

[0030] 2. The contact form, friction material, lubrication and cage material of the rolling contact fatigue test of GCr15 bearing steel in this invention can all be kept consistent with those of actual machine tool bearings.

[0031] 3. In addition to examining the fatigue spalling life of GCr15 bearing steel, this invention also uses the observation and analysis of micro-pitting corrosion in the surface morphology of GCr15 bearing steel after fatigue testing as a measure of the precision life of GCr15 bearing steel, so as to meet the precision life requirements of high-end precision machine tool bearings.

[0032] 4. This method can perform 10 tests on the same GCr15 bearing steel bar, and can avoid the influence of different bars when evaluating the rolling contact fatigue life of GCr15 bearing steel. Attached Figure Description

[0033] Figure 1 An exploded view of the assembly of the core components of the ball-and-stick contact fatigue testing machine.

[0034] Figure 2 This is a schematic diagram of the structure of a GCr15 bearing steel sample bar.

[0035] Figure 3 This is a schematic diagram of the cage structure. (a) is the front view, and (b) is the top view.

[0036] Figure 4 This is a schematic diagram of the basic components of a bearing.

[0037] Figure 5 The image shows the contact fatigue life curves obtained from a fixed-number truncated test using rare-earth GCr15 bearing steel and ceramic balls. The horizontal axis represents the life (N, number of cycles), and the vertical axis P(X) represents the failure probability (%).

[0038] Figure 6 The surface morphology of rare earth GCr15 bearing steel after rolling contact fatigue tests at different cycles is shown.

[0039] In the diagram, 1. Limiting plate, 2. Upper thrust bearing, 3. Upper conical ring base, 4. GCr15 bearing steel bar, 5. Upper conical ring, 6. Ceramic rolling element, 7. Column, 8. Lower conical ring, 9. Cage, 10. Lower conical ring base, 11. Lower thrust bearing, 12. Fixed plate platform; 13. Left seal, 14. Outer ring, 15. Rolling element, 16. Cage, 17. Inner ring, 18. Right seal. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings.

[0041] like Figure 1As shown, the core components of the ball-and-bar contact fatigue testing machine mainly include: a limiting plate 1, an upper thrust bearing 2, an upper conical ring base 3, a GCr15 bearing steel bar 4, an upper conical ring 5, ceramic rolling elements 6, a column 7, a lower conical ring 8, a cage 9, a lower conical ring base 10, a lower thrust bearing 11, and a fixed plate platform 12. The specific structure is as follows:

[0042] Two relatively parallel columns 7 are vertically arranged on a horizontal fixed plate platform 12. A GCr15 bearing steel rod 4 is vertically positioned between the two columns 7. An upper thrust bearing 2, an upper conical ring base 3, an upper conical ring 5, a lower conical ring 8, a lower conical ring base 10, and a lower thrust bearing 11 are sequentially fitted onto the GCr15 bearing steel rod 4 from top to bottom. The GCr15 bearing steel rod 4 is connected to the inner rings of the upper thrust bearing 2 and the lower thrust bearing 11, respectively. The inner surfaces of the upper conical ring 5 and the lower conical ring 8 are annular conical surfaces. Correspondingly, the upper tapered ring 5 is embedded in the central hole of the upper tapered ring base 3, and the lower tapered ring 8 is embedded in the central hole of the lower tapered ring base 10. A cage 9 and ceramic rolling elements 6 are arranged between the upper tapered ring 5 and the lower tapered ring 8. The three ceramic rolling elements 6 are evenly installed on the cage 9. The upper tapered ring 5 is loaded downwards through its upper surface, and pressure is applied to the ceramic rolling elements 6 by its inner surface. The lower tapered ring 8 is loaded upwards through its lower surface, and pressure is applied to the ceramic rolling elements 6 by its inner surface. During the test, the ceramic rolling elements 6 simultaneously make rolling contact with the central GCr15 bearing steel bar 4 (simulating the inner ring), the upper and lower tapered rings (simulating the outer ring), and the cage under lubrication with grease or lubricating oil (simulating the lubrication of an actual bearing).

[0043] Three holes are made on the horizontal limiting plate 1. The holes on both sides correspond to and match the columns 7, and the hole in the middle corresponds to and matches the GCr15 bearing steel rod 4. After assembly, the limiting plate 1 is sleeved on the two columns 7 and the GCr15 bearing steel rod 4, and slides with the columns 7 and the GCr15 bearing steel rod 4.

[0044] During the experiment, the upper end of the GCr15 bearing steel rod 4 is connected to the rotating spindle via a high-precision collet. The spindle is driven by a motor or electric spindle, and the GCr15 bearing steel rod 4 rotates at high speed under the drive of the spindle. The rotation of the GCr15 bearing steel rod 4 causes the ceramic rolling element 6 to rotate on its own axis and revolve around the bearing steel rod, thereby simulating the motion of the ceramic rolling element 6 in an actual bearing.

[0045] Loading is achieved by bringing the upper conical ring 5 and the lower conical ring 8 closer together. After the limiting plate 1 is fixed to the column 7 with bolts, the lower conical ring base 10 and the lower thrust bearing 11 rise linearly under the push of the loading spindle. The push of the loading spindle can be achieved by weights and levers.

[0046] like Figure 2 , Figure 3As shown, the dimensions of the corresponding GCr15 bearing steel bar and cage are drawn using drawing software. For example, the diameter of the ceramic rolling element in the actual bearing is selected as... The ceramic rolling element must be tangent to both the GCr15 bearing steel rod and the inner surface of the tapered ring, and the outer diameter of the tapered ring must match the inner diameter of the tapered ring base. Based on these requirements, the corresponding diameter is... For ceramic rolling elements, the outer ring of the tapered roller bearing can be selected as model 32004 (GBT 297-2015), and the outer diameter of the GCr15 bearing steel bar is designed to be... Based on the distance of 1.32mm from the tangent point between the ceramic rolling element and the inner surface of the tapered ring to the center of the ceramic rolling element, and the distance of 15.25mm from the upper surface of the tapered ring to the center of the ceramic rolling element 6, it can be concluded that in order to ensure a certain gap between the upper tapered ring 5 and the lower tapered ring 8, the height of the outer ring of the 32004 tapered roller bearing needs to be reduced by 2.4mm by a surface grinder.

[0047] After the dimensions of the upper tapered ring 5, lower tapered ring 8, and GCr15 bearing steel bar are designed, the external dimensions of the cage are designed so that the cage does not interfere with the upper tapered ring 5, lower tapered ring 8, and the center-rubbing GCr15 bearing steel bar, while limiting the thickness of the cavity of the ceramic rolling elements.

[0048] The fatigue cycle life of GCr15 bearing steel in rolling contact fatigue performance was tested by conducting a fixed-number truncated test. The truncated value was determined through exploratory testing. Vibration of the oil box (located outside the lower conical ring base, tightly fitted with the lower conical ring) was measured using an accelerometer. When spalling of the GCr15 bearing steel occurred, the vibration value exceeded the threshold, and the testing machine automatically stopped. Referring to GB10622-89 "Metallic Materials - Rolling Contact Fatigue Test Method", the fatigue cycle data was processed using the Weibull distribution to provide L10 and L50 lives and the b-value.

[0049] The precision life characterization of rolling contact fatigue performance of GCr15 bearing steel was measured by conducting rolling contact fatigue tests of different cycles on the same GCr15 bearing steel bar. After different cycles of testing, the surface three-dimensional morphology of micropitting was observed at different magnifications using Keyence microscopy and white light interferometry. The quantity, size, shape, and depth of micropitting under different cycles were statistically analyzed.

[0050] By combining fatigue cycle life and precision life measurement results, the contact fatigue performance of GCr15 bearing steel is evaluated from two different dimensions.

[0051] The present invention will be further described in detail below through embodiments.

[0052] Example 1:

[0053] In this embodiment, a ball-and-bar type rolling contact fatigue testing machine is used. Three rolling elements are distributed at 120° and roll in contact with the GCr15 bearing steel rod. The diameter of the ceramic rolling element is 12.7 mm. Based on the size of the 12 mm diameter GCr15 bearing steel rod to be tested, the geometric relationship is determined by the rolling element forming a three-point contact with the GCr15 bearing steel rod and the upper and lower tapered rings, while ensuring a certain gap between the upper and lower tapered rings. A 32004 type tapered roller bearing is selected, and its outer ring is used as the upper and lower tapered rings, or it can be machined (reducing the height of the outer ring without any machining of the inner surface) to serve as the upper and lower tapered rings.

[0054] After the dimensions of the upper tapered ring, lower tapered ring, and GCr15 bearing steel bar are designed, the external dimensions of the cage are designed to ensure that the cage does not interfere with the upper tapered ring, lower tapered ring, and the center-rubbing GCr15 bearing steel bar, while also limiting the thickness of the pockets for the ceramic rolling elements. A cage made of the same material as the actual bearing is machined to simulate the lubrication conditions of the actual bearing. Grease lubrication is selected, and ball-and-bar experiments are conducted.

[0055] like Figure 1 As shown, a method for testing the rolling contact fatigue performance of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings is described below.

[0056] a. Mark 40mm from one end of the GCr15 bearing steel rod 4, add it into the fixture through a high-precision collet, and install the limit plate 1;

[0057] b. Place the lower thrust bearing 11 on the fixed plate platform 12 between the two columns 7, and put the lower conical ring base 10, lower conical ring 8, cage 9, upper conical ring 5, upper conical ring base 3, and upper thrust bearing 2 into the oil box in sequence.

[0058] c. Lift the upper cone ring 5 and above with your left hand, and place the ceramic rolling elements 6 into the three holes of the cage 9 in turn with your right hand;

[0059] d. First load, then turn on the power. Set the speed and vibration value to zero. Adjust the speed of GCr15 bearing steel rod 4 clockwise. First, adjust it to about 1000 rpm. Slightly lift the lever to find the balance. After it is balanced, set the speed of GCr15 bearing steel rod 4 to 5000 rpm.

[0060] e. Vibration alarm value setting: Set the initial value to 200. After the machine vibration stabilizes for about 5 minutes, observe the vibration range and enter a value that is 1.5 times the maximum value.

[0061] f. When the experiment reaches the preset vibration value, an automatic alarm will sound, the experiment will stop, the power will be turned off, and the computer will save the data.

[0062] The fatigue cycle life of the rolling contact fatigue performance of GCr15 bearing steel bars was tested by conducting a fixed-number truncation test. The truncation value was determined through exploratory testing. The vibration of the oil box was tested by an accelerometer. When spalling of the GCr15 bearing steel occurred, the vibration value exceeded the threshold, and the testing machine automatically stopped.

[0063] By conducting rolling contact fatigue tests at different cycles, the surface morphology changes in the rolling contact fatigue performance of GCr15 bearing steel were tested, which are closely related to its accuracy and service life. After the tests, the three-dimensional surface morphology of the GCr15 bearing steel was observed at different magnifications, and the number, size, shape, and depth of micropitting at different cycles were statistically analyzed.

[0064] By combining the surface morphology changes from fatigue cycle life and measurement accuracy life, the contact fatigue performance of material-grade GCr15 bearing steel is evaluated from two different dimensions.

[0065] The experimental data for this embodiment are as follows:

[0066] Following the steps outlined above, a ball-on-rod rolling contact fatigue test was conducted using rare-earth GCr15 bearing steel and ceramic balls. Fixed-number truncated tests and tests with different cycle counts were performed. The experimental results are as follows:

[0067] Table 1

[0068]

[0069] Table 2

[0070]

[0071] In Table 2, P0 represents stress, Route represents heat treatment method, and β represents the slope (discrepancy) of the straight line.

[0072] like Figure 5 As shown in Tables 1 and 2, a total of 16 tests were conducted. It can be seen that rare earth GCr15 bearing steel with uniform carbides has a better fatigue life.

[0073] like Figure 6 As shown, rolling contact fatigue tests were conducted at different cycles of 20,000, 80,000, 320,000, and 640,000 cycles. The number of micropittings increased with the increase of the number of cycles, and the precision life decreased.

[0074] The results show that this invention employs a testing method that more closely approximates the actual service conditions of ceramic hybrid bearings used in machine tools, enabling a more reliable evaluation of the rolling contact fatigue life of bearing steel. This saves time and costs, and provides a convenient and reliable evaluation of rolling contact fatigue life and precision life, contributing to the improvement of bearing performance from a tribological perspective and accelerating the production of high-end precision machine tool bearings in my country.

Claims

1. A method for testing the rolling contact fatigue properties of GCr15 bearing steel used in the manufacture of high-speed ceramic hybrid bearings, characterized in that, The specific steps are as follows: a. Material selection: Simulate actual high-speed ceramic hybrid bearing materials, and select appropriate GCr15 bearing steel and ceramic rolling element materials; b. The GCr15 bearing steel to be tested is processed into a bearing steel bar sample with a diameter of 12 mm and a length of 120 mm. The ceramic rolling element material is processed into a ceramic ball with a diameter of 12.7 mm. The precision grade is consistent with the precision grade of the ceramic rolling element in the actual bearing. c. Conduct ball-and-bar rolling contact fatigue tests, and use the constant-number truncation method to estimate the contact fatigue life of the bearing steel. The contact stress cycle truncation value is set to 2 × 10⁻⁶. 8 The contact stress value is 5 GPa, the rotation speed of the bearing steel bar sample is 5000 rpm, and the grease used in the actual bearing is selected for lubrication. The rolling contact fatigue testing machine used in the ball-and-bar type test mainly includes: a limiting plate, an upper thrust bearing, an upper conical ring base, a GCr15 bearing steel bar specimen, an upper conical ring, ceramic rolling elements, a column, a lower conical ring, a cage, a lower conical ring base, a lower thrust bearing, and a fixed plate platform. The specific structure is as follows: Two relatively parallel columns are vertically set on a horizontal fixed plate platform. A GCr15 bearing steel bar sample is vertically set between the two columns. The upper thrust bearing, upper conical ring base, upper conical ring, lower conical ring, lower conical ring base, and lower thrust bearing are sequentially fitted onto the GCr15 bearing steel bar sample from top to bottom. The GCr15 bearing steel bar sample is connected to the inner rings of the upper thrust bearing and the lower thrust bearing respectively. The inner surfaces of the upper and lower conical rings are annular conical surfaces and correspond to each other. The upper conical ring is embedded in the central hole of the upper conical ring base, and the lower conical ring is embedded in the central hole of the lower conical ring base. A cage and ceramic rolling elements are set between the upper and lower conical rings. The three ceramic rolling elements are evenly installed on the cage. The upper conical ring is loaded downwards through the upper surface, and the inner surface of the upper conical ring applies pressure to the ceramic rolling elements. The lower conical ring is loaded upwards through the lower surface, and the inner surface of the lower conical ring applies pressure to the ceramic rolling elements. Three holes are made on the horizontal limiting plate. The holes on both sides correspond to and match the columns, and the hole in the middle corresponds to and matches the GCr15 bearing steel bar sample. After assembly, the limiting plate is fitted onto the two columns and the GCr15 bearing steel bar sample, and slides with the columns and the GCr15 bearing steel bar sample. During testing, the upper end of the GCr15 bearing steel bar sample is connected to the rotating spindle, which is driven by a motor or electric spindle. The GCr15 bearing steel bar sample rotates at high speed under the drive of the rotating spindle. The rotation of the GCr15 bearing steel bar sample causes the ceramic rolling elements to rotate on their own axis and revolve around the bearing steel bar sample, thereby simulating the motion of the ceramic rolling elements in an actual bearing. By conducting rolling contact fatigue tests of different cycles on the same GCr15 bearing steel bar sample, the precision life characterization of the rolling contact fatigue performance of GCr15 bearing steel is measured.

2. The method for testing the rolling contact fatigue properties of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings according to claim 1, characterized in that, Based on the exploration of the rolling contact fatigue testing machine, the surface roughness of the GCr15 bearing steel bar specimen was determined to be 0.02 μm.

3. The method for testing the rolling contact fatigue properties of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings according to claim 1, characterized in that, The selected GCr15 bearing steel bar specimen is clamped in a fixture with a 40mm mark on one end. This test method is repeated ten times on a single GCr15 bearing steel bar specimen.

4. The method for testing the rolling contact fatigue properties of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings according to claim 1, characterized in that, After rolling contact fatigue test, the fatigue life of GCr15 bearing steel is obtained by calculation method with constant truncation, which directly simulates the fatigue life of actual bearing.

5. The method for testing the rolling contact fatigue properties of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings according to claim 1, characterized in that, Loading is achieved by bringing the upper and lower conical rings closer together. After the limiting plate is fixed to the column with bolts, the lower conical ring base and the lower thrust bearing rise linearly under the push of the loading spindle. According to the actual service conditions of the bearing, the pushing of the loading spindle of the rolling contact fatigue testing machine is achieved by weights and levers. By using weights for loading and adjusting the lever balance, different weights are added to the lever, and different contact stresses are obtained by Hertzian contact stress calculation, which is consistent with the actual contact stress of the bearing.

6. The method for testing the rolling contact fatigue properties of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings according to claim 1, characterized in that, The dimensions of the bearing steel bar sample and rolling elements are fixed, and the bearing steel bar sample and rolling elements of different materials are replaced.

7. The method for testing the rolling contact fatigue properties of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings according to claim 1, characterized in that, Based on actual service conditions, for the rolling contact fatigue test of GCr15 bearing steel, the rolling contact test was directly carried out under the conditions of engineering grease lubrication.

8. The method for testing the rolling contact fatigue properties of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings according to claim 1, characterized in that, Rolling contact fatigue tests were conducted, and the morphology of the surface and cross-section of the GCr15 bearing steel after the test was observed.

9. The method for testing the rolling contact fatigue properties of GCr15 bearing steel used in manufacturing high-speed ceramic hybrid bearings according to claim 1, characterized in that, Material grade GCr15 bearing steel was selected to simulate rolling contact fatigue between rolling elements and raceways in actual bearings.

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