A device for measuring the end face runout of a crossed roller bearing

Abstract

This application relates to the field of bearing testing technology, specifically a cross roller bearing end face runout measuring device, comprising: a base assembly with an annular positioning groove on its top for accommodating and supporting the bearing under test; a loading assembly for applying an axial load to the inner ring end face of the bearing under test; and a lower part of a mandrel that is a smooth shaft section adapted to the bearing's inner bore for insertion into the bearing's inner bore. This application utilizes a mandrel smooth shaft section with a precise, slight interference fit to the bearing's inner bore, combined with a constant axial load provided by the load body's own weight, to generate uniform, stable, and sufficient static friction between the mandrel and the bearing's inner bore wall without external impact or excessive pressing force. This solves the slippage problem caused by loose fit in traditional methods, ensuring absolute synchronous rotation between the drive assembly and the bearing's inner ring during measurement, laying the foundation for the stability and repeatability of the measurement data.

Description

Technical Field

[0001] This application relates to the field of bearing testing technology, specifically a device for measuring the runout of the end face of a crossed roller bearing. Background Technology

[0002] Crossed roller bearings, due to their superior performance in terms of high rigidity, high rotational accuracy, and ability to withstand combined loads in multiple directions, have become core support components in high-end equipment such as industrial robot joints, precision CNC rotary tables, medical devices, and high-precision optical instruments. The axial runout accuracy of their inner ring end face is one of the key indicators for evaluating bearing quality grade and predicting the rotational performance of the host machine, directly affecting the positioning accuracy, operational stability, and service life of the assembled equipment.

[0003] Currently, the industry generally relies on general-purpose measuring instruments, such as runout gauges, to indirectly measure bearing end face runout in conjunction with standard mandrels or expansion sleeves. However, this traditional method has revealed several insurmountable technical shortcomings in long-term practice:

[0004] First, the stability and consistency of the measurement clamping are difficult to guarantee. The fit between the commonly used standard mandrel (such as a tapered mandrel) and the bearing's inner bore is not easily controlled precisely. If a clearance fit is used, a microscopic gap exists between the mandrel and the bearing's inner ring, which can easily lead to relative slippage or momentary disengagement during manual rotation measurement. This results in large data dispersion and poor repeatability, severely affecting the reliability of the measurement results and the accuracy of the judgment. If a mandrel with a large interference fit is used to achieve stable contact, external force (such as hammering or hydraulic pressure) is required to force it in. This excessive radial clamping force can easily cause elastic or plastic deformation of the thin-walled inner ring of the bearing, not only destroying the original geometric accuracy of the bearing and distorting the measurement values, but also potentially causing irreversible damage to high-value precision bearings.

[0005] Secondly, the measurement conditions are severely out of sync with actual service conditions. In real-world operation, the inner ring face of a bearing is typically subjected to a precisely calculated axial preload from adjacent structural components (such as locknuts or end caps). This preload alters the bearing's internal clearance, adjusting the contact state between the raceway and rolling elements, thus significantly impacting the inner ring's runout. However, traditional measurement methods often do not apply axial force, or rely solely on the operator's feel to apply uncertain, unquantifiable minute pressures, completely failing to simulate the bearing's true condition under preload. Runout data measured under these "no-load" or "unspecified load" conditions has a weak correlation with the bearing's actual performance after assembly and preload, making it difficult to serve as an effective basis for guiding precision assembly and predicting final rotational accuracy. Summary of the Invention

[0006] The technical problem to be solved by this application is to overcome the existing defects and provide a cross roller bearing end face runout measuring device, which can effectively solve the problems in the background art.

[0007] To achieve the above objectives, this application provides the following technical solution: a cross roller bearing end face runout measuring device, comprising:

[0008] The base assembly has an annular positioning groove on its top for accommodating and supporting the bearing to be tested;

[0009] A loading assembly is used to apply an axial load to the inner ring end face of the bearing under test; the loading assembly includes a mandrel and a load body; the lower part of the mandrel is a smooth shaft section adapted to the inner hole of the bearing, used for insertion into the inner hole of the bearing; the load body is connected to the upper end of the mandrel, and its bottom is provided with an annular bearing groove coaxial with the mandrel, the outer flange plane of the annular bearing groove is in contact with the inner ring end face of the bearing;

[0010] The load body transmits power through the spindle, and the optical axis section of the spindle contacts the inner wall of the bearing, so that the inner ring of the bearing and the spindle rotate synchronously.

[0011] As a preferred embodiment of this application, the base assembly is a ring-shaped support, and the annular positioning groove at the center of the support is consistent with the outer diameter of the bearing outer ring.

[0012] As a preferred technical solution of this application, the mandrel and the load body are connected by screws to achieve a detachable fixed connection.

[0013] As a preferred technical solution of this application, the diameter of the optical axis section at the lower part of the mandrel is interference-fitted with the inner hole of the bearing.

[0014] As a preferred technical solution of this application, a ring channel is provided on the top of the load body.

[0015] As a preferred technical solution of this application, it also includes a measuring component, wherein the probe of the measuring component is vertical and contacts the annular track at the top of the load body.

[0016] Compared with existing technologies, the advantages of this application are as follows: By employing a spindle shaft section with a precise, slight interference fit to the bearing inner bore, and combining this with a constant axial load provided by the weight of the load body, uniform, stable, and sufficient static friction is generated between the spindle and the bearing inner bore wall without external impact or excessive pressing force. This solves the slippage problem caused by loose fit in traditional methods, ensuring absolute synchronous rotation between the drive assembly (spindle-load body) and the bearing inner ring during measurement, laying the foundation for the stability and repeatability of measurement data. Simultaneously, because the interference fit is strictly controlled, the load is applied uniformly through the annular bearing groove flange plane, effectively avoiding harmful deformation of the bearing inner ring that may be caused by traditional forced pressing or point contact loading, achieving non-destructive testing of precision bearings and protecting the original precision of the workpiece.

[0017] The load body is connected to the spindle by screws, applying a constant axial preload to the inner ring end face of the bearing under test. This ensures that the measurement conditions closely match the bearing's actual stress state during installation and operation (i.e., the inner ring end face is axially compressed). The end face runout data measured under this simulated load can accurately reflect the bearing's overall accuracy performance under load. The obtained data provides a direct and highly reliable indicator for predicting the bearing's actual rotational accuracy, axial runout, and operational stability after assembly with the main machine. This effectively solves the problem of the disconnect between traditional "no-load" measurement data and actual working conditions, providing a reliable input basis for precision assembly processes. Attached Figure Description

[0018] Figure 1 This is the main view of this application;

[0019] Figure 2 This is the main view of the load body;

[0020] Figure 3 This is a schematic diagram of the mandrel structure.

[0021] In the figure: 1. Support; 2. Crossed roller bearing to be tested; 3. Mandrel; 4. Screw; 5. Load body; 5a. Ring track; 5b. Annular bearing groove; 6. Measuring components. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Please see Figure 1This application provides a technical solution: a cross roller bearing end face runout measuring device. The main body of the base assembly is an annular support 1, and the inner hole of the annular support is a precision-machined stepped hole. The large diameter D of the stepped hole is designed according to the outer diameter d of the outer ring of the target bearing 2, and is usually taken as D≈d+(0.02~0.05)mm, forming a precision positioning. The groove depth H is less than the width B of the bearing outer ring, ensuring that after the bearing is placed, its outer ring end face is higher than the top plane of the support 1, providing full circumferential support for the bearing.

[0024] The loading assembly is the motion unit that performs the measurement. The spindle 3 is a two-section structure: the upper section is a connecting section with a central aperture for connection to the load body 5; the lower section is an optical shaft section with a diameter d3 designed according to the inner diameter d2 of the bearing 2, using a slight interference fit. The end of the optical shaft section is machined with a guiding chamfer for easy insertion. The load body 5 has a blind hole at its center, which is positioned with a small clearance fit to the upper end of the spindle 3. The two are axially fastened by screws 4 to ensure a rigid connection. At the bottom of the load body 5 is an annular bearing groove 5b with a machined circular cross-section. The lower end face of the annular bearing groove 5b is in close contact with the inner ring end face of the bearing 2, and the outer diameter of the annular bearing groove 5b is smaller than the outer diameter of the inner ring end face of the bearing 2.

[0025] When the assembly is placed, only the annular flange plane on the outer side of the annular bearing groove 5b contacts the end face of the bearing inner ring.

[0026] The top of the load body 5 is provided with a machined ring track 5a, the horizontal surface of which is precision ground. The probe of the measuring component 6 is a contact displacement sensor, providing an ideal and clean measurement reference for the contact displacement sensor.

[0027] Since the annular track 5a is integrated with the load body 5 that carries the runout signal of the inner ring end face, any runout error of the bearing inner ring end face will be converted into a radial offset of the annular track 5a relative to the theoretical center of rotation on a 1:1 basis. During measurement, the probe of the measuring component 6 is pressed vertically and lightly on the annular track 5a. As the loading component rotates, the radial offset of the annular track 5a is continuously recorded by the sensor. The precision-ground annular track 5a provides a more stable and clearer measurement signal, effectively reducing measurement errors and improving resolution and accuracy.

[0028] In use: Place the crossed roller bearing 2 to be tested into the annular positioning groove of the support 1. Under its own weight, the outer cylindrical surface of the bearing 2's outer ring makes slight contact with the inner wall of the annular positioning groove, while the end face of the outer ring makes complete contact with the bottom of the groove, thus achieving rapid, accurate, and stable radial and axial positioning. At this time, the bearing's outer ring is fully constrained.

[0029] The operator selects a loading assembly with a corresponding diameter mandrel 3 based on the inner diameter of bearing 2, i.e., assembling the corresponding mandrel 3 and load body 5 using screws 4. The smooth section of mandrel 3 is aligned with the inner bore of bearing 2 and pressed vertically under its own weight and slight pressure. Due to the slight interference fit, mandrel 3 will produce a uniform elastic fit with the inner wall of the bearing bore, forming a tight friction pair. Simultaneously, the outer surface of the annular bearing groove 5b at the bottom of load body 5 presses steadily against the end face of the bearing inner ring. At this point, load body 5 acts on the inner ring through this annular contact surface, and through the rolling elements inside the bearing and the outer ring, ultimately transmits the force to support 1. The device enters a stable mechanical equilibrium state.

[0030] Gently press the spherical probe of measuring component 6 vertically towards the center of the top ring 5a of the load body 5. Adjust the dial indicator base so that the dial indicator reads zero at the initial position, or record an initial value. Use the ring 5a at this moment as the physical reference plane for the entire measurement.

[0031] At this time, the load body 5 rotates uniformly and slowly. The strong static friction generated by the tight fit between the spindle 3 and the bearing inner hole effectively transmits the rotational torque. The spindle 3 begins to rotate, causing the inner ring of the bearing, which is in close contact with it, to rotate synchronously. If the end face of the bearing inner ring is tilted or uneven with respect to the ideal plane, this unevenness will force the annular bearing surface of the load body 5 in contact with it to undergo periodic height changes as the inner ring rotates. Since the load body 5 and the spindle 3 are rigidly connected, this height change is directly converted into a periodic slight tilting oscillation of the axis of the spindle 3. This tilting oscillation is transmitted to the top of the load body 5, causing the center line of the top annular track 5a to wobble synchronously, and its outer circular surface to produce a periodic radial displacement change relative to the fixed dial indicator probe.

[0032] The load body 5 rotates at least one full revolution. During this period, observe the changes in the readings of the measuring component 6. Record the maximum value (Max) and minimum value (Min) of the readings during one revolution. According to the definition of runout, the total runout value T of the bearing inner ring end face is: T = |Max - Min|. The T value is the runout accuracy data of the bearing inner ring end face under simulated preload. This value is used to determine whether the bearing is qualified.

[0033] Through the above steps, the entire clamping process is quick and stable, the force state is clear and repeatable, and the measurement results are intuitive and reliable. When changing the bearing model, only the corresponding mandrel 3 and the matching load body 5 need to be replaced to start a new measurement cycle, which greatly improves the operating efficiency.

[0034] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for measuring the runout of the end face of a crossed roller bearing, characterized in that, include: The base assembly has an annular positioning groove on its top for accommodating and supporting the bearing (2) to be tested; A loading assembly is used to apply an axial load to the inner ring end face of the bearing (2) under test; the loading assembly includes a spindle (3) and a load body (5); the lower part of the spindle (3) is a smooth shaft section adapted to the inner hole of the bearing (2) for insertion into the inner hole of the bearing (2); the load body (5) is connected to the upper end of the spindle (3), and its bottom is provided with an annular bearing groove (5b) coaxial with the spindle (3), and the outer flange plane of the annular bearing groove (5b) contacts the inner ring end face of the bearing (2); The load body (5) transmits power through the spindle (3). The optical axis section of the spindle (3) contacts the inner wall of the bearing (2), so that the inner ring of the bearing (2) and the spindle (3) form a synchronous rotation relationship.

2. The cross roller bearing end face runout measuring device according to claim 1, characterized in that, The base assembly is a ring-shaped support (1), and the annular positioning groove at the center of the support (1) is consistent with the outer diameter of the outer ring of the bearing (2).

3. The cross roller bearing end face runout measuring device according to claim 1, characterized in that, The mandrel (3) is connected to the load body (5) by screws (4).

4. The cross roller bearing end face runout measuring device according to claim 3, characterized in that, The diameter of the optical axis section at the lower part of the spindle (3) is interference-fitted with the inner hole of the bearing (2).

5. The cross roller bearing end face runout measuring device according to claim 1, characterized in that, The top of the load body (5) is provided with a ring channel (5a).

6. The cross roller bearing end face runout measuring device according to claim 5, characterized in that, It also includes a measuring component (6), the probe of which is perpendicular and in contact with the annulus (5a) at the top of the load body (5).

Images