Angular contact ball bearing axial assembly consistency evaluation system

Abstract

The application discloses a kind of angular contact ball bearing axial assembly consistency evaluation system, implementation steps are as follows: S1 is clamped and realizes axial single side limiting to be measured double-row bearing;S2 applies centering load to make rolling element and raceway fully adhere;S3 fixes one of bearing inner ring or outer ring, and the other part is applied to axial load cycle, and the detection data of force sensor and displacement sensor are synchronously collected;S4 generates force-displacement characteristic curve and determines bearing axial assembly consistency according to this.The system only needs once clamping and once load cycle to complete detection, greatly shortens detection time, adapts production line online full detection demand;Reflect the dynamic working performance of bearing through force-displacement curve, intuitively reflect the contact of two rows of raceways and load distribution state, avoid the one-sidedness of static geometric detection;It can also identify the implicit load bias caused by steel ball size dispersion and micro error of channel, effectively reduce the risk of misjudgment.

Description

Technical Field

[0001] The present invention relates to a detection system, and more particularly to an evaluation system for the axial assembly consistency of angular contact ball bearings. Background Art

[0002] Double-row tandem angular contact ball bearings are widely used in precision transmission applications such as the main shafts of CNC machine tools and ball screw pairs. Their axial assembly consistency directly determines whether the two rows of rolling elements can carry loads evenly, and thus affects the stiffness and life of the system. In the prior art, when detecting this consistency, the assembled bearing is usually placed on a special measuring device. Under a specified standard axial measuring load, the probe is used to contact the reference end faces of the inner ring and the outer ring respectively to obtain the "assembly height" of the first row of raceways, that is, the relative distance between the inner ring end face and the outer ring end face under a specific load. Subsequently, the bearing needs to be flipped or repositioned, and the same loading method and measurement reference are used to independently obtain the assembly height of the second row of raceways. Finally, the difference between the assembly heights of the two rows is compared. If this difference falls within the preset tolerance range, the axial assembly consistency is determined to be qualified. The entire process requires two independent clamping, loading, and reading operations on a single set of bearings.

[0003] However, the existing methods have significant drawbacks: the detection efficiency is low, requiring two independent clamping, loading, and reading operations, resulting in a slow production beat and difficulty in meeting the requirements of large-scale online full inspection; the information obtained is one-sided, and the assembly height is only a static geometric quantity, which cannot dynamically reveal the contact state between the two rows of raceways and the uniformity of the internal load distribution when the bearing is actually jointly loaded; and there is a risk of misjudgment. Affected by factors such as the size dispersion of steel balls, the microscopic geometric errors of raceways, and the guiding clearances of cages, even if the difference in assembly height meets the tolerance, the bearing may still experience load eccentricity, and this method cannot effectively identify this. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides an evaluation system for the axial assembly consistency of angular contact ball bearings that solves the problems of low detection efficiency, one-sided information, and easy misjudgment in the assembly consistency detection of double-row tandem bearings.

[0005] To achieve the above object, the technical solution of the present invention is as follows: An evaluation system for the axial assembly consistency of angular contact ball bearings includes an axial loading unit, a force sensor, a displacement sensor, a data acquisition and control unit, a clamping fixture, and a double-row bearing to be measured, and is implemented in the following manner: S1, install the double-row bearing to be measured on the clamping fixture and limit one axial side of the double-row bearing to be measured through the clamping fixture; S2, apply a centering load between the rolling elements and the raceways on the double-row bearing to be measured through the axial loading unit; S3, fix one of the outer ring or inner ring of the double row bearing under test, control the axial loading unit to apply axial load cyclically to the other of the outer ring or inner ring of the double row bearing under test, and collect data from the force sensor and displacement sensor in real time through the data acquisition and control unit while applying the axial load cyclically. S4. Generate a force-displacement characteristic curve based on the data collected in S3, and determine the axial assembly consistency of the double-row bearing under test based on the generated force-displacement characteristic curve.

[0006] The beneficial effects of this invention are: inspection can be completed with only one clamping and one axial load cycle, significantly shortening inspection time and meeting the online full inspection requirements of the production line; the force-displacement characteristic curve reflects the dynamic functional performance of the bearing, directly reflecting the contact state and load distribution of the two raceways, avoiding the limitations of static geometric inspection; it can identify implicit load imbalances caused by steel ball size dispersion and microscopic errors in the raceways, reducing the risk of misjudgment. As a preferred method, the clamping fixture adopts a split support base with an adjustable self-centering structure, achieving uniform support for the bearing outer ring through three-point centering; as another preferred method, the data acquisition and control unit integrates a motion control card and a data acquisition card, enabling synchronous triggering of loading commands and data acquisition clocks.

[0007] Furthermore, the force sensor and displacement sensor are jointly calibrated.

[0008] Joint calibration eliminates the error superposition problem caused by individual calibration, establishes a unified mapping relationship between true axial force and true axial displacement, and corrects measurement deviations caused by the deformation of the detection system itself, ensuring the accuracy of subsequent stiffness calculations and feature parameter extraction. As a preferred method, a standard stiffness component is used as the calibration benchmark, and the output signals of the two sensors are synchronously acquired and fitted to correct the model through gradient loading. Another preferred method is to automatically execute the joint calibration process each time the equipment is powered on, compensating for sensor zero-point drift in real time.

[0009] Furthermore, the axial load cycle includes at least one process of loading from the initial state to a preset rated test load and then unloading back to the initial state.

[0010] A complete load-unload cycle can simultaneously acquire the stiffness characteristics of the bearing during both loading and unloading phases, and can extract characteristic parameters reflecting internal friction and contact states, such as hysteresis ring area and curve asymmetry, comprehensively covering the evaluation dimensions of assembly consistency. As a preferred approach, the axial loading unit uses a servo electric cylinder to achieve uniform and stable loading, avoiding interference from impact loads on the raceway contact state. As another preferred approach, the loading process employs segmented speed control, reducing the loading speed in the low-load range to increase data acquisition density.

[0011] Furthermore, the force-displacement characteristic curve is generated based on the axial force value sequence and the corresponding axial displacement value sequence.

[0012] A continuous force-displacement characteristic curve is generated based on the synchronously acquired axial force value sequence and the corresponding displacement value sequence. This curve can intuitively present the variation law of bearing axial stiffness with load, providing a reliable data foundation for the subsequent extraction of multi-dimensional characteristic parameters. As a preferred method, the least squares method is used to fit the discrete data points to eliminate the influence of random noise on the curve shape. As another preferred method, the generated curve is stored synchronously with the original data, which facilitates subsequent quality traceability and statistical process control.

[0013] Furthermore, several characteristic parameters can be extracted from the force-displacement characteristic curve. By comparing several characteristic parameters of the double-row bearing under test with the qualified threshold, the axial assembly consistency of the double-row bearing under test can be characterized.

[0014] By comprehensively comparing multiple characteristic parameters with acceptable thresholds, the assembly consistency of the two raceways can be reflected from different dimensions, avoiding the limitations of single-parameter judgment and improving the accuracy and reliability of the evaluation results. As a preferred approach, the acceptable thresholds of the characteristic parameters are preset in the control unit to achieve automatic judgment of test results and automatic sorting triggering of non-conforming products. Another preferred approach is to establish a database of characteristic parameter thresholds for bearings of different specifications to achieve compatible testing of multiple bearing models.

[0015] Furthermore, the characteristic parameters include at least the stiffness difference coefficient, curve asymmetry, and hysteresis loop area.

[0016] The stiffness difference coefficient quantifies the load sharing consistency between the two raceways, while the curve asymmetry and hysteresis loop area reflect the uniformity of internal friction and contact conditions within the bearing. Combining these three factors allows for a comprehensive and accurate assessment of the axial assembly consistency of double-row bearings. One preferred method is to calculate the average stiffness values ​​for the low-load and high-load ranges separately to obtain the stiffness difference coefficient. Another preferred method is to calculate the area of ​​the closed region enclosed by the loading and unloading curves using numerical integration to obtain the hysteresis loop area. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 This is a schematic diagram comparing the force-displacement characteristic curves of an embodiment of the present invention. Detailed Implementation

[0018] An embodiment of the present invention provides an axial assembly consistency evaluation system for angular contact ball bearings, such as... Figure 1-2As shown, this system mainly consists of an axial loading unit 1, a force sensor 11, a displacement sensor 12, a data acquisition and control unit 2, a clamping fixture 3, and the double-row bearing 4 to be tested. The force sensor 11 and displacement sensor 12 are jointly calibrated before the equipment is put into use to eliminate measurement deviations and ensure the matching of the output data of the two types of sensors. The clamping fixture 3 has an axial limiting structure, which can stably achieve unilateral axial position constraint of the double-row bearing 4 under test. The axial loading unit 1 can use a servo electric cylinder or a pneumatic-hydraulic booster cylinder as the power component. Its output axial load is cyclically limited to a complete process from loading from the initial state to the preset rated detection load, and then unloading back to the initial state. The displacement sensor 12 adopts a high-resolution non-contact structure, and the clamping fixture 3 is also equipped with an adjustable structure to avoid additional bending moments generated in the double-row bearing 4 under test during loading. The data acquisition and control unit 2 establishes signal connections with the force sensor 11 and the displacement sensor 12 respectively, and can collect the axial force value sequence and the corresponding axial displacement value sequence in real time, and generate a force-displacement characteristic curve based on the above two sets of sequences. This unit incorporates a data processing algorithm capable of extracting various characteristic parameters from the curve. These parameters include, but are not limited to, stiffness difference coefficients, curve asymmetry, and hysteresis loop area. The calculation methods are as follows: Stiffness difference coefficient (K_ratio): Calculate the first stiffness value K_low in the low load range and the second stiffness value K_high in the high load range of the force-displacement curve, and calculate their ratio K_ratio = K_high / K_low. For bearings with good consistency, K_ratio approaches 1.

[0019] Curve asymmetry: Under the same axial force value, calculate the absolute difference between the displacement δ_load of the loading curve and the displacement δ_unload of the unloading curve, and statistically analyze the maximum or average value of this difference throughout the entire cycle. The greater the asymmetry, the worse the consistency.

[0020] Hysteresis loop area (Area_h): Calculates the area of ​​the closed region enclosed by the loading curve and the unloading curve. Poor consistency leads to uneven internal friction, increasing the hysteresis loop area. The stiffness difference coefficient is calculated according to the formula K_ratio=K_high / K_low, where K_low is the first stiffness value in the low load range and K_high is the second stiffness value in the high load range. The system ultimately compares the extracted feature parameters with preset qualified thresholds to determine the axial assembly consistency of the double-row bearing under test.

[0021] The working principle of this embodiment is as follows: First, the double row bearing 4 to be tested is placed on the clamping fixture 3, and the clamping fixture 3 is used to limit and fix the double row bearing 4 on one side of the axial direction. Then, the axial loading unit 1 is controlled to apply a centering load to the double row bearing 4 to make the rolling elements inside the bearing fully fit with the raceway. Next, one of the outer ring and inner ring of the double row bearing 4 to be tested is fixed, and then the axial loading unit 1 applies a complete axial load cycle to the other part. During the entire process of load application, the data acquisition and control unit 2 synchronously acquires the detection data of the force sensor 11 and the displacement sensor 12 to obtain a continuous axial force value sequence and axial displacement value sequence. Then, the force-displacement characteristic curve is plotted using the acquired data, and characteristic parameters such as stiffness difference coefficient, curve asymmetry, and hysteresis loop area are extracted from the curve. The characteristic parameters are compared with the preset qualified threshold one by one to determine whether the axial assembly consistency of the double row bearing 4 to be tested meets the standard.

[0022] like Figure 2 As shown, curve A represents the F-δ curve of a bearing with good consistency, exhibiting high linearity, with the loading and unloading curves almost coinciding and a small hysteresis loop. Curve B, on the other hand, represents the curve of a bearing with poor consistency. In the low-load region (before point P), the stiffness is low, with only one raceway bearing the load. After point P, the other raceway begins to make full contact, resulting in a sharp increase in overall stiffness, a clear inflection point on the curve, and separation of the loading and unloading paths, forming a large hysteresis loop. By extracting parameters such as K_ratio and asymmetry from curve B, its inconsistency can be quantitatively determined.

[0023] The above embodiments are merely one preferred embodiment of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included within the protection scope of the present invention.

Claims

1. A system for evaluating the axial assembly consistency of angular contact ball bearings, comprising an axial loading unit, a force sensor, a displacement sensor, a data acquisition and control unit, a clamping fixture, and a double-row bearing to be tested, implemented in the following manner: S1, install the double row bearing to be tested onto the clamping fixture and limit the axial side of the double row bearing to be tested through the clamping fixture; S2, applying a centering load between the rolling elements and the raceway to the double-row bearing under test via an axial loading unit; S3, fix one of the outer ring or inner ring of the double row bearing under test, control the axial loading unit to apply axial load cyclically to the other of the outer ring or inner ring of the double row bearing under test, and collect data from the force sensor and displacement sensor in real time through the data acquisition and control unit while applying the axial load cyclically. S4. Generate a force-displacement characteristic curve based on the data collected in S3, and determine the axial assembly consistency of the double-row bearing under test based on the generated force-displacement characteristic curve.

2. The axial assembly consistency evaluation system for angular contact ball bearings according to claim 1, characterized in that: The force sensor and displacement sensor are jointly calibrated.

3. The axial assembly consistency evaluation system for angular contact ball bearings according to claim 1, characterized in that: The axial load cyclic shaft includes at least one process of loading from the initial state to a preset rated detection load and then unloading back to the initial state.

4. The axial assembly consistency evaluation system for angular contact ball bearings according to claim 1, characterized in that: The force-displacement characteristic curve is generated based on the axial force value sequence and the corresponding axial displacement value sequence.

5. The axial assembly consistency evaluation system for angular contact ball bearings according to claim 1 or 4, characterized in that: Several characteristic parameters can be extracted from the force-displacement characteristic curve. By comparing several characteristic parameters of the double-row bearing under test with the qualified threshold, the axial assembly consistency of the double-row bearing under test can be characterized.

6. The axial assembly consistency evaluation system for angular contact ball bearings according to claim 5, characterized in that: The characteristic parameters include at least the stiffness difference coefficient, curve asymmetry, and hysteresis loop area.

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