A method for measuring bearing radial clearance

Abstract

This invention relates to the field of rolling bearing testing technology, specifically to a method for measuring bearing radial clearance. By acquiring three-dimensional coordinates at multiple points in the non-stressed area of ​​the bearing outer ring, the center position of the bearing outer ring is accurately determined using the least squares method. This effectively avoids measurement errors A caused by local elastic deformation of the bearing outer ring due to the measuring force of the measuring instrument itself, and measurement errors B caused by local elastic deformation of the bearing outer ring due to radial loading. Simultaneously, a zero-radial-clearance bearing is introduced as a calibration benchmark. Combined with measured data, the method identifies radial clearance changes caused by local deformation that are undetectable by traditional methods, and compensates and corrects the radial clearance measurement results accordingly. This not only avoids measurement errors caused by local deformation due to the measuring force of the measuring instrument itself in principle, but also significantly improves the accuracy and reliability of bearing radial clearance measurement, achieving high-precision and repeatable testing.

Description

Technical Field

[0001] This invention relates to the field of rolling bearing testing technology, and specifically to a method for measuring bearing radial clearance. Background Technology

[0002] The radial clearance of a bearing directly affects its lifespan, noise, and temperature rise. Excessive clearance can lead to vibration and wear, while insufficient clearance can cause high-temperature seizure. Appropriate clearance must be selected based on the operating conditions to ensure optimal working clearance during operation. Currently, the bearing industry commonly uses specialized radial clearance measuring instruments to measure bearing radial clearance. This method typically involves fixing the bearing inner ring with a mandrel and gland, then applying a specified radial load to the outer ring, and using a measuring instrument to read the displacement variation of the outer ring between two extreme positions, thereby calculating the radial clearance value.

[0003] However, this traditional method for measuring bearing clearance has inherent limitations in measurement accuracy. One portion of the measurement error arises from the local deformation of the bearing caused by the radial load; another portion arises from the measuring instrument's large measuring force, which further causes local deformation of the bearing's outer ring, leading to measurement errors. Specifically, because the bearing's outer ring itself has relatively weak rigidity, and the applied force is concentrated radially during measurement, the outer ring is prone to local elastic deformation. Since the measuring point of the measuring instrument is near the applied force, this deformation induced by the measuring load itself causes the measured displacement to include spurious deformation, resulting in a deviation from the true value. Simultaneously, the measuring instrument itself also exerts a measuring force, which can also cause deformation of the bearing's outer ring, further altering the bearing's radial clearance and creating measurement errors that cannot be detected by existing methods. Therefore, there is an urgent need for a bearing radial clearance measurement method that can eliminate the aforementioned measurement errors to achieve high-precision detection of bearing radial clearance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for measuring the radial clearance of a bearing. This method can avoid measurement errors caused by local deformation at the measurement point, and can also quantify and compensate for clearance changes caused by loading deformation, thus significantly improving the accuracy and reliability of bearing radial clearance measurement.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for measuring the radial clearance of a bearing includes the following steps: S2-1: Install the bearing under test: Position the inner diameter of the bearing under test on the mandrel, place the pressure plate on the end face of the inner ring of the bearing under test, and tighten the pressure plate with bolts to fix the inner ring of the bearing under test. S2-2: Establishing a spatial coordinate system for measurement: A coordinate measuring machine (CMM) is used to collect data on the inner surface of the V-shaped fork of the loading head in the loading device; the line connecting the intersection of the two inner surfaces of the V-shaped fork on one side of the loading device with the line connecting the two inner surfaces of the V-shaped fork on the other side of the loading device forms plane I; data is collected on the upper end face of the inner ring of the bearing under test to determine plane II; data is collected on the inner diameter of the inner ring of the bearing under test in a single plane to determine the spatial coordinates O of the inner ring center. 内 Inner circle center spatial coordinates O 内 The projection onto plane II is O. 原点 Let the intersection of plane I and plane II be the X-axis, and let point O be the origin of the X-axis. 原点 Assume that the line is perpendicular to plane II and passes through O. 原点 Let the perpendicular line be the Z-axis; let it be perpendicular to plane I and pass through O. 原点 The perpendicular line is the Y-axis; that is, the origin of the X-axis, Y-axis, and Z-axis is O. 原点 The X, Y, and Z axes can be set arbitrarily; this completes the establishment of the spatial coordinate system for measurement. S2-3: First loading of the outer ring of the bearing under test: The loading head on one side of the loading component is used to apply the first loading to the middle of the outer diameter of the outer ring of the bearing under test. S2-4: Determination of the center O3 position of the outer ring of the tested bearing: Data is collected from the unloaded side of the outer diameter of the outer ring of the tested bearing using a coordinate measuring machine. The arc angle of the data collection should be greater than 45° to avoid inaccurate evaluation of the center position due to a small measurement angle. The data collection area should not overlap with the loaded area. The spatial coordinates O3 (X3, Y3, Z3) of the center are obtained by fitting using the least squares method. S2-5: Second loading of the outer ring of the bearing under test: The middle part of the outer diameter of the outer ring of the bearing under test is loaded a second time using the loading head on the other side of the loading component; S2-6: Determination of the center O4 position of the outer ring of the tested bearing: Data is collected on the unloaded side of the outer diameter arc of the outer ring of the tested bearing using a coordinate measuring machine. The arc angle of the data collection should be greater than 45° to avoid inaccurate evaluation of the center position due to a small measurement angle. The data collection area should not overlap with the loaded area. The spatial coordinates O4 (X4, Y4, Z4) of the center are obtained by fitting using the least squares method. S2-7: Calculation of radial clearance of the bearing under test: Since the outer ring of the bearing under test moves along the X-axis under the action of the loading component, Y3=Y4 and Z3=Z4. Therefore, the radial clearance of the bearing under test = |X3-X4|-measurement error B = |X3-X4|-|X1-X2|.

[0006] Furthermore, the method for measuring the measurement error B employs the following operational steps: S1-1: Installing a zero-radial-clearance bearing: Position the inner diameter of the selected zero-radial-clearance bearing on the mandrel, place the pressure plate on the end face of the bearing inner ring of the zero-radial-clearance bearing, and tighten the pressure plate with bolts to fix the bearing inner ring of the zero-radial-clearance bearing. S1-2: Establishing a spatial coordinate system for measurement: Data is collected from the inner surface of the V-shaped fork of the loading head using a coordinate measuring machine; the line connecting the intersection of the two inner surfaces of the V-shaped fork on one side of the loading head with the line connecting the two inner surfaces of the V-shaped fork on the other side of the loading head constitutes plane I; data is collected from the upper end face of the inner ring of the zero-radial clearance bearing to determine plane II; data is collected from the inner diameter of the inner ring of the zero-radial clearance bearing in a single plane to determine the spatial coordinates O of the inner ring center. 内 Inner circle center spatial coordinates O 内 The projection onto plane II is O. 原点 Let the intersection of plane I and plane II be the X-axis, and let point O be the origin of the X-axis. 原点 Assume that the line is perpendicular to plane II and passes through O. 原点 Let the perpendicular line be the Z-axis; let it be perpendicular to plane I and pass through O. 原点 The perpendicular line is the Y-axis; that is, the origin of the X-axis, Y-axis, and Z-axis is O. 原点 The X, Y, and Z axes can be set arbitrarily; this completes the establishment of the spatial coordinate system for measurement. S1-3: Determination of the position of the center O1 of the outer ring of the zero radial clearance bearing: Data is collected from the middle of the outer diameter of the outer ring of the zero radial clearance bearing using a coordinate measuring machine, and the spatial coordinates of the center O1 (X1, Y1, Z1) are obtained by fitting the data using the least squares method. S1-4: Loading the outer ring of a zero radial clearance bearing: Loading is applied to the middle of the outer diameter of the outer ring of the zero radial clearance bearing using a loading head on one side of the loading component; S1-5: Determination of the center O2 position of the outer ring of the zero radial clearance bearing: Data is collected from the unloaded side of the outer diameter of the outer ring of the zero radial clearance bearing using a coordinate measuring machine. The arc angle of the data collection should be greater than 45° to avoid inaccurate evaluation of the center position due to a small measurement angle. The data collection area should not overlap with the loaded area. The spatial coordinates O2 (X2, Y2, Z2) of the center are obtained by fitting using the least squares method. S1-6: Calculation of measurement error B: Since the outer ring of the zero radial clearance bearing moves along the X-axis under the action of the loading component, Y1=Y2 and Z1=Z2. Therefore, the measurement error B=|X1-X2|.

[0007] Furthermore, the loading device includes a base plate, a mandrel, a pressure plate, and loading components; the entire loading device is used to load and fix the bearing under test or the zero radial clearance bearing. A mandrel is provided on the base plate, and the bearing under test or the zero radial clearance bearing is mounted on the mandrel. Loading components are provided on both sides of the bearing under test or the zero radial clearance bearing in the radial direction. A pressure plate for pressing the inner ring of the bearing under test or the zero radial clearance bearing is installed on the inner ring of the bearing under test or the zero radial clearance bearing.

[0008] Furthermore, the base plate has a square structure, with a through hole a in the center for mounting the mandrel. The mandrel is mounted in the center of the base plate by bolts, and loading components are mounted in the center of two opposite sides of the base plate.

[0009] Furthermore, the mandrel has a cylindrical structure and is used to position the inner ring of the bearing under test or the zero radial clearance bearing. A threaded hole b is provided in the middle of the mandrel to fix the mandrel to the center of the base plate. At the same time, the mandrel, through the threaded hole c in the middle, cooperates with the bolt and the pressure plate to achieve the clamping of the bearing under test or the zero radial clearance bearing.

[0010] Furthermore, the pressure plate has a Y-shaped structure, which fixes the bearing under test or the zero radial clearance bearing by bolts and a mandrel. During use, the pressure plate does not come into contact with other parts outside the inner ring of the bearing under test or the zero radial clearance bearing.

[0011] Furthermore, the loading component is a conventional adjustable force pneumatic loading component, with a loading head provided at the loading end of the loading component for stable loading of the bearing under test or the zero radial clearance bearing; the loading component is located at the middle position of two opposite sides of the base plate.

[0012] Furthermore, the bearing under test is a bearing that requires radial clearance measurement, and the zero radial clearance bearing is a bearing with zero radial clearance. The loading device and the bearing under test or the zero radial clearance bearing form a measured object, which is placed on the measuring platform of a coordinate measuring machine. The coordinate measuring machine is a conventional high-precision coordinate measuring machine with data acquisition and data analysis functions.

[0013] The beneficial effects of this invention are as follows: The bearing radial clearance measurement method provided by this invention uses a coordinate measuring machine (CMM) instead of a traditional measuring instrument. By acquiring three-dimensional coordinates at multiple points in the non-stressed area of ​​the bearing outer ring, the center position of the bearing outer ring is accurately determined using the least squares method. This effectively avoids the measurement error B caused by local elastic deformation of the bearing outer ring due to radial loading and the measuring force of the measuring instrument itself. At the same time, a zero-radial clearance bearing is introduced as a calibration benchmark. Combined with actual measurement data, the radial clearance change caused by local deformation, which cannot be detected by traditional methods, is identified. Based on this, the radial clearance measurement results are compensated and corrected. Compared with traditional methods, this technology not only avoids the measurement error caused by local deformation due to the measuring force of the measuring instrument itself in principle, but also quantifies and compensates for the clearance change caused by loading deformation. This significantly improves the accuracy and reliability of bearing radial clearance measurement, achieves high-precision and repeatable detection, and has stronger scientific and engineering application value. Attached Figure Description

[0014] Figure 1 This is a three-dimensional structural diagram of the bearing radial clearance measurement method according to the present invention. Figure 2 This is a schematic diagram of the three-dimensional structure for measuring the measurement error B of the present invention; Figure 3 This is a flowchart of the bearing radial clearance measurement method of the present invention; Figure 4 This is a schematic diagram of the spatial coordinate system used for measurement in this invention; Figure 5 This is a schematic diagram of the base plate of the present invention; Figure 6 This is a schematic diagram of the mandrel of the present invention; Figure 7 This is a schematic diagram of the loading device of the present invention; The numbers in the figure are: 1. Loading device; 101. Base plate; 102. Mandrel; 103. Pressure plate; 104. Loading component; 2. Coordinate measuring machine; 3. Bearing under test; 4. Zero radial clearance bearing; 5. Plane I; 6. Plane II; 7. Through hole a; 8. Threaded hole c; 9. Threaded hole b. Detailed Implementation

[0015] The technical solution of the present invention will be clearly and completely described below with reference to embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In order to solve the problem that existing bearing radial clearance measurement methods cannot avoid measurement errors caused by local deformation due to the measuring force of the measuring instrument itself and clearance changes caused by loading deformation, resulting in inaccurate bearing radial clearance measurement and poor reliability, the present invention designs a bearing radial clearance measurement method. This method introduces a coordinate measuring machine 2 to replace the traditional measuring instrument for data acquisition. The coordinate measuring machine 2, with its multi-point three-dimensional coordinate acquisition and mathematical fitting capabilities, acquires multiple spatial coordinate points in the non-stressed area of ​​the bearing outer ring (i.e., the rigid area without local deformation), and fits the true center position of the bearing outer ring by the least squares method, so as to avoid the measurement error A (the measurement error A has no special meaning and is only for illustrative purposes) caused by the measuring force of the measuring instrument. Then, by selecting a zero-radial clearance bearing 4 and using a coordinate measuring machine 2, the measurement error B (which is undetectable by traditional measurement methods due to changes in the radial clearance caused by local deformation of the bearing outer ring) is obtained. This measurement error B has no special meaning and is only used for illustrative purposes. Finally, the radial clearance measurement value of the tested bearing 3 is compensated using the measurement error B, resulting in a more accurate radial clearance measurement value.

[0016] As per the instruction manual Figure 1 To the instruction manual Figure 7 As shown, the bearing radial clearance measurement method of the present invention requires the use of a loading device 1 and a coordinate measuring machine 2. The loading device 1 is a conventional loading device, which includes a base plate 101, a spindle 102, a pressure plate 103, and loading components 104. The loading device 1 is used to load and fix the bearing 3 or zero radial clearance bearing 4 under test. A spindle 102 is provided on the base plate 101, and the bearing 3 or zero radial clearance bearing 4 under test is mounted on the spindle 102. Loading components 104 are provided on both sides of the bearing 3 or zero radial clearance bearing 4 in the radial direction. A pressure plate 103 is installed on the inner ring of the bearing 3 or zero radial clearance bearing 4 to press the inner ring of the bearing 3 or zero radial clearance bearing 4.

[0017] The base plate 101 has a square structure with a through hole a7 in the center for mounting the mandrel 102. The mandrel 102 is mounted on the center of the base plate 101 by bolts. Loading components 104 are mounted on the center of two opposite sides of the base plate 101. The mandrel 102 has a cylindrical structure and is used to position the inner ring of the bearing 3 or the zero radial clearance bearing 4 under test. The mandrel 102 has a threaded hole b9 in the center for fixing the mandrel 102 to the center of the base plate 101. At the same time, the mandrel 102 is connected to the pressure plate 103 through the threaded hole c8 in the center to press the bearing 3 or the zero radial clearance bearing 4 under test. The pressure plate 103 has a Y-shaped structure. The pressure plate 103 fixes the bearing 3 or the zero radial clearance bearing 4 under test by bolts and mandrel 102. During use, the pressure plate 103 does not contact other parts outside the inner ring of the bearing 3 or the zero radial clearance bearing 4 under test. The loading component 104 is a conventional pneumatic loading component with adjustable force. The loading end of the loading component 104 is provided with a loading head for stably loading the bearing 3 or the zero radial clearance bearing 4 under test. The loading component 104 is located in the middle of two opposite sides of the base plate 101.

[0018] The bearing 3 under test is the bearing for which radial clearance measurement is required. The zero radial clearance bearing 4 is a bearing with zero radial clearance, which can be achieved by selecting and matching the inner ring, outer ring, and steel balls of the bearing. The loading device 1 and the bearing 3 or the zero radial clearance bearing 4 form a measured object, which is placed on the measuring platform of the coordinate measuring machine 2. The coordinate measuring machine 2 is a conventional high-precision coordinate measuring machine with data acquisition and data analysis functions.

[0019] The present invention provides a method for measuring bearing radial clearance, specifically employing the following steps for measuring measurement error B: S1-1: Install the zero radial clearance bearing 4: Position the inner diameter of the selected zero radial clearance bearing 4 on the spindle 102, place the pressure plate 103 on the bearing inner ring end face of the zero radial clearance bearing 4, and tighten the pressure plate 103 with bolts to fix the bearing inner ring of the zero radial clearance bearing 4. S1-2: Establishing a spatial coordinate system for measurement: A coordinate measuring machine 2 is used to collect data on the inner surface of the V-shaped fork of the loading head of the loading component 104; the line connecting the intersection of the two inner surfaces of the V-shaped fork on one side of the loading component 104 with the line connecting the two inner surfaces of the V-shaped fork on the other side of the loading component 104 forms plane I5; data is collected on the upper end face of the inner ring of the zero radial clearance bearing 4 to determine plane II6; data is collected on the inner diameter of the inner ring of the zero radial clearance bearing 4 in a single plane to determine the spatial coordinates O of the inner ring center. 内 Inner circle center spatial coordinates O内 The projection onto plane II6 is O. 原点 Let the intersection of plane I5 and plane II6 be the X-axis, and let point O be the origin of the X-axis. 原点 Assume that the line is perpendicular to plane II6 and passes through O. 原点 The perpendicular line is the Z-axis; let it be perpendicular to plane I5 and pass through O. 原点 The perpendicular line is the Y-axis; that is, the origin of the X-axis, Y-axis, and Z-axis is O. 原点 The X, Y, and Z axes can be set arbitrarily; this completes the establishment of the spatial coordinate system for measurement. S1-3: Determination of the position of the center O1 of the outer ring of the zero radial clearance bearing 4: Data is collected from the middle of the outer diameter of the outer ring of the zero radial clearance bearing 4 using a coordinate measuring machine 2, and the spatial coordinates of the center O1 (X1, Y1, Z1) are obtained by fitting the data using the least squares method. S1-4: Loading the outer ring of the zero radial clearance bearing 4: Loading is applied to the middle of the outer diameter of the outer ring of the zero radial clearance bearing 4 using the loading head on one side of the loading component 104; S1-5: Determination of the position of the center O2 of the outer ring of the zero radial clearance bearing 4: Data is collected on the unloaded side of the outer diameter of the outer ring of the zero radial clearance bearing 4 using a coordinate measuring machine 2. The arc angle of the data collection should be greater than 45° to avoid the inability to accurately evaluate the center position due to a small measurement angle. The data collection area should not overlap with the loaded area. The spatial coordinates O2 (X2, Y2, Z2) of the center are obtained by fitting using the least squares method. S1-6: Calculation of measurement error B: Since the outer ring of the zero radial clearance bearing 4 moves along the X-axis under the action of the loading component 104, Y1=Y2 and Z1=Z2. Therefore, the measurement error B=|X1-X2|.

[0020] A method for measuring the radial clearance of a bearing, specifically for measuring the radial clearance of the bearing 3 under test, comprises the following steps: S2-1: Install the bearing under test 3: Position the inner diameter of the bearing under test 3 on the mandrel 102, place the pressure plate 103 on the end face of the inner ring of the bearing under test 3, and tighten the pressure plate 103 with bolts to fix the inner ring of the bearing under test 3. S2-2: Establishing a spatial coordinate system for measurement: A coordinate measuring machine 2 is used to collect data on the inner surface of the V-shaped fork of the loading head of the loading component 104; the line connecting the intersection of the two inner surfaces of the V-shaped fork on one side of the loading component 104 with the line connecting the two inner surfaces of the V-shaped fork on the other side of the loading component 104 forms plane I5; data is collected on the upper end face of the inner ring of the bearing under test 3 to determine plane II6; data is collected on the inner diameter of the inner ring of the bearing under test 3 in a single plane to determine the spatial coordinates O of the inner ring center. 内Inner circle center spatial coordinates O 内 The projection onto plane II6 is O. 原点 Let the intersection of plane I5 and plane II6 be the X-axis, and let point O be the origin of the X-axis. 原点 Assume that the line is perpendicular to plane II6 and passes through O. 原点 The perpendicular line is the Z-axis; let it be perpendicular to plane I5 and pass through O. 原点 The perpendicular line is the Y-axis; that is, the origin of the X-axis, Y-axis, and Z-axis is O. 原点 The X, Y, and Z axes can be set arbitrarily; this completes the establishment of the spatial coordinate system for measurement. S2-3: First loading of the outer ring of the tested bearing 3: The loading head on one side of the loading component 104 is used to apply the first loading to the middle of the outer diameter of the outer ring of the tested bearing 3. S2-4: Determination of the position of the center O3 of the outer ring of the tested bearing 3: Data is collected on the unloaded side of the outer diameter of the outer ring of the tested bearing 3 using a coordinate measuring machine 2. The arc angle of the data collection should be greater than 45° to avoid the inability to accurately evaluate the center position due to a small measurement angle. The data collection area should not overlap with the loading area. The spatial coordinates O3 (X3, Y3, Z3) of the center are obtained by fitting using the least squares method. S2-5: Second loading of the outer ring of the tested bearing 3: The loading head on the other side of the loading component 104 is used to apply a second loading to the middle of the outer diameter of the outer ring of the tested bearing 3. S2-6: Determination of the position of the center O4 of the outer ring of the tested bearing 3: Data is collected on the unloaded side of the outer diameter of the outer ring of the tested bearing 3 using a coordinate measuring machine 2. The arc angle of the data collection should be greater than 45° to avoid the inability to accurately evaluate the center position due to a small measurement angle. The data collection area should not overlap with the loading area. The spatial coordinates O4 (X4, Y4, Z4) of the center are obtained by fitting using the least squares method. S2-7: Calculation of radial clearance of the tested bearing 3: Since the outer ring of the tested bearing 3 moves along the X-axis under the action of the loading component 104, Y3=Y4 and Z3=Z4. Therefore, the radial clearance of the tested bearing 3 = |X3-X4|-measurement error B = |X3-X4|-|X1-X2|.

[0021] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for measuring the radial clearance of a bearing, characterized in that, Includes the following steps: S2-1: Install the bearing to be tested (3): Position the inner diameter of the bearing to be tested (3) on the mandrel (102), place the pressure plate (103) on the end face of the inner ring of the bearing to be tested (3), and tighten the pressure plate (103) with bolts to fix the inner ring of the bearing to be tested (3); S2-2: Establishing a spatial coordinate system for measurement: A coordinate measuring machine (2) is used to collect data on the inner surface of the loading head V-shaped fork of the loading component (104) in the loading device (1); the line connecting the two inner surfaces of the loading head V-shaped fork on one side of the loading component (104) and the line connecting the two inner surfaces of the loading head V-shaped fork on the other side of the loading component (104) forms plane I (5). Data was collected from the upper end face of the inner ring of the tested bearing (3) to determine plane II (6); Collecting data of single plane inner diameter of inner ring of the bearing (3) to determine spatial coordinates O of the center of the inner ring 内 ; The inner ring center space coordinate O 内 The projection on the plane II (6) is O 原点 ; the intersection line of the plane I (5) and the plane II (6) is the X axis, and the origin of the X axis is the point O 原点 ; the vertical line perpendicular to the plane II (6) and passing through O 原点 is the Z axis; and the vertical line perpendicular to the plane I (5) and passing through O 原点 is the Y axis; That is, the origin of the X-axis, Y-axis, and Z-axis is O. 原点 The X, Y, and Z axes can be set arbitrarily; this completes the establishment of the spatial coordinate system for measurement. S2-3: First loading of the outer ring of the bearing under test (3): The loading head on one side of the loading component (104) is used to apply the first loading to the middle of the outer diameter of the outer ring of the bearing under test (3); S2-4: Determination of the center O3 position of the outer ring of the bearing under test (3): Data is collected on the side of the outer diameter of the outer ring of the bearing under test (3) without loading by a coordinate measuring machine (2). The arc angle of the data collection should be greater than 45° to avoid the inability to accurately evaluate the center position due to the small measurement angle. The data collection area does not overlap with the loading area. The center spatial coordinates O3 (X3,Y3,Z3) are obtained by fitting using the least squares method. S2-5: Second loading of the outer ring of the bearing under test (3): The loading head on the other side of the loading component (104) is used to apply a second loading to the middle of the outer diameter of the outer ring of the bearing under test (3); S2-6: Determination of the center O4 position of the outer ring of the bearing under test (3): Data is collected on the side of the outer diameter of the outer ring of the bearing under test (3) without loading by a coordinate measuring machine (2). The arc angle of the data collection should be greater than 45° to avoid the inability to accurately evaluate the center position due to the small measurement angle. The data collection area does not overlap with the loading area. The center spatial coordinates O4 (X4, Y4, Z4) are obtained by fitting using the least squares method. S2-7: Radial clearance calculation of the bearing under test (3): Since the outer ring of the bearing under test (3) moves along the X-axis under the action of the loading component (104), Y3 = Y4 and Z3 = Z4. Therefore, the radial clearance of the bearing under test (3) = |X3-X4|-measurement error B = |X3-X4|-|X1-X2|.

2. The method for measuring bearing radial clearance according to claim 1, characterized in that, The measurement method for the measurement error B adopts the following operating steps: S1-1: Install the zero radial clearance bearing (4): Position the inner diameter of the selected zero radial clearance bearing (4) on the spindle (102), place the pressure plate (103) on the bearing inner ring end face of the zero radial clearance bearing (4), and tighten the pressure plate (103) with bolts to fix the bearing inner ring of the zero radial clearance bearing (4); S1-2: Establishing a spatial coordinate system for measurement: A coordinate measuring machine (2) is used to collect data on the inner surface of the V-shaped fork of the loading head of the loading component (104); the line connecting the two inner surfaces of the V-shaped fork on one side of the loading component (104) and the line connecting the two inner surfaces of the V-shaped fork on the other side of the loading component (104) forms plane I (5); data is collected on the upper end face of the inner ring of the zero radial clearance bearing (4) to determine plane II (6); data is collected on the inner diameter of the inner ring of the zero radial clearance bearing (4) in a single plane to determine the spatial coordinate O of the inner ring center. 内 Inner circle center spatial coordinates O 内 The projection onto plane II (6) is O. 原点 Let the intersection of plane I (5) and plane II (6) be the X-axis, and let point O be the origin of the X-axis. 原点 ; Suppose that it is perpendicular to plane II (6) and passes through O 原点 The perpendicular line is the Z-axis; let it be perpendicular to plane I (5) and pass through O. 原点 The perpendicular line is the Y-axis; that is, the origin of the X-axis, Y-axis, and Z-axis is O. 原点 The X, Y, and Z axes can be set arbitrarily; this completes the establishment of the spatial coordinate system for measurement. S1-3: Determination of the position of the center O1 of the outer ring of the zero radial clearance bearing (4): Data is collected from the middle of the outer diameter of the outer ring of the zero radial clearance bearing (4) by a coordinate measuring machine (2), and the spatial coordinates of the center O1 (X1,Y1,Z1) are obtained by fitting the data using the least squares method. S1-4: Loading the outer ring of the zero radial clearance bearing (4): Loading is performed on the middle of the outer diameter of the outer ring of the zero radial clearance bearing (4) using the loading head on one side of the loading component (104); S1-5: Determination of the center O2 position of the outer ring of the zero radial clearance bearing (4): Data is collected on the unloaded side of the outer diameter of the outer ring of the zero radial clearance bearing (4) using a coordinate measuring machine (2). The arc angle of the data collection should be greater than 45° to avoid the inability to accurately evaluate the center position due to the small measurement angle. The data collection area does not overlap with the loading area. The center spatial coordinates O2 (X2, Y2, Z2) are obtained by fitting using the least squares method. S1-6: Calculation of measurement error B: Since the outer ring of the zero radial clearance bearing (4) moves along the X-axis under the action of the loading component (104), Y1=Y2 and Z1=Z2. Therefore, the measurement error B=|X1-X2|.

3. The method for measuring bearing radial clearance according to claim 2, characterized in that, The loading device (1) includes a base plate (101), a spindle (102), a pressure plate (103), and a loading component (104). The entire loading device (1) is used to load and fix the bearing (3) or the zero radial clearance bearing (4) under test. A spindle (102) is provided on the base plate (101). The bearing (3) or the zero radial clearance bearing (4) under test is installed on the spindle (102). Loading components (104) are provided on both sides of the bearing (3) or the zero radial clearance bearing (4) under test in the radial direction. A pressure plate (103) for pressing the inner ring of the bearing (3) or the zero radial clearance bearing (4) under test is installed on the inner ring of the bearing (3) or the zero radial clearance bearing (4).

4. The method for measuring bearing radial clearance according to claim 3, characterized in that, The base plate (101) is a square structure. The center of the base plate (101) is provided with a through hole a (7) for mounting the mandrel (102). The mandrel (102) is mounted at the center of the base plate (101) by bolts. Loading components (104) are installed in the middle of the two opposite sides of the base plate (101).

5. The method for measuring bearing radial clearance according to claim 4, characterized in that, The mandrel (102) is a cylindrical structure used to position the inner ring of the bearing (3) or the zero radial clearance bearing (4) under test. The mandrel (102) has a threaded hole b (9) in the middle, which is used to fix the mandrel (102) to the center of the base plate (101). At the same time, the mandrel (102) is connected to the bolt and the pressure plate (103) through the threaded hole c (8) in the middle to achieve the pressing of the bearing (3) or the zero radial clearance bearing (4) under test.

6. The method for measuring bearing radial clearance according to claim 5, characterized in that, The pressure plate (103) has a Y-shaped structure and is used to fix the bearing (3) or zero radial clearance bearing (4) under test by bolts and mandrel (102). During use, the pressure plate (103) does not contact other parts outside the inner ring of the bearing (3) or zero radial clearance bearing (4) under test.

7. The method for measuring bearing radial clearance according to claim 6, characterized in that, The loading component (104) is a conventional adjustable force pneumatic loading component. A loading head is provided at the loading end of the loading component (104). The loading head is a V-shaped fork structure, which is used to stably load the bearing (3) or the zero radial clearance bearing (4) under test. The loading component (104) is located at the middle position of two opposite sides of the base plate (101).

8. The method for measuring bearing radial clearance according to claim 2, characterized in that, The bearing under test (3) is a bearing that needs to be measured for radial clearance. The zero radial clearance bearing (4) is a bearing with zero radial clearance. The loading device (1) and the bearing under test (3) or the zero radial clearance bearing (4) form a measured object. The measured object is placed on the measuring platform of the coordinate measuring machine (2). The coordinate measuring machine (2) is a conventional high-precision coordinate measuring machine with data acquisition and data analysis functions.

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