JP2003130762A - Method and device for evaluating rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for evaluating rolling bearing by which the contact angle of a preloaded rolling bearing can be found with accuracy. SOLUTION: At the time of finding the contact angle of the preloaded rolling bearing, measurement of at least one of the natural frequencies of the bearing in the angular direction and in the radial direction and the coupled natural frequency of the two frequencies is measured in addition to the natural frequency of the bearing in the axial direction, and the frequency ratio between the measured natural frequencies is found. Then the contact angle is found from a profound relation between the frequency ratio and contact angle. In addition, the preload imparted to the bearing is found from the rigidity of the bearing in the axial direction found from the natural frequency of the bearing in the axial direction. Therefore, the preload imparted to the rolling bearing can be found with accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing evaluation method and a rolling bearing evaluation apparatus capable of evaluating rolling bearings such as double row bearings and combination bearings to which a preload is applied.

[0002]

2. Description of the Related Art Generally, in a double-row bearing or a combined bearing to which a preload is applied, high rigidity is required in terms of performance of a machine in which the bearing is incorporated. However, if the amount of preload is increased to make the rigidity too high, the preload becomes excessive and the bearing performance (increase in friction moment, abnormal heat generation, fatigue life, etc.) is deteriorated. Therefore, it is necessary to control the rigidity value of the bearing within a certain range while associating it with the preload amount.

The following are known techniques for measuring the rigidity value of a bearing. JP-A-5-10835
Japanese Patent Laid-Open Publication No. 2003-242242 discloses a method of determining a contact angle of a rolling element and a resonance frequency fa of a bearing by performing a frequency analysis of a vibration signal generated from a rotating bearing, and determining a bearing rigidity Ka and a preload amount from the contact angle and the resonance frequency. Is listed. Further, Japanese Patent Application Laid-Open No. 2000-74788 discloses a method of extracting the optimum resonance frequency in the axial direction to obtain the axial rigidity of the bearing from a plurality of resonance frequencies.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the techniques disclosed in JP-A-74788 and JP-A-5-10835, the rigidity in the axial direction of the rolling bearing can be obtained, and if the contact angle of the rolling bearing is constant, the obtained axial direction can be obtained. The bearing preload can be accurately evaluated by using the rigidity of. However, when the contact angle varies due to the dimensional error of the bearing, the bearing preload cannot be accurately evaluated only by obtaining the rigidity of the bearing in the axial direction.

The present invention has been made in view of the above problems of the prior art, and provides a rolling bearing evaluation method and an evaluation device capable of accurately obtaining a contact angle in a preloaded rolling bearing. The purpose is to do.

[0006]

In the rolling bearing evaluation method of the present invention, in addition to measuring the natural frequency in the axial direction of the rolling bearing, the natural frequency in the angular direction, the natural frequency in the radial direction, In addition, the step of measuring at least one of the natural frequencies of which the two are coupled, the step of obtaining the frequency ratio of the measured natural frequencies, and the contact angle from the relationship between the previously obtained frequency ratio and the contact angle And a preload of the bearing from the axial rigidity obtained from the natural frequency in the axial direction.

In the rolling bearing evaluation apparatus of the present invention,
In addition to measuring the natural frequency of the rolling bearing in the axial direction, at least one of the natural frequency in the angular direction, the natural frequency in the radial direction, and the natural frequency in which the two are coupled is measured. Measuring means, means for obtaining the frequency ratio of the measured natural frequencies, and a contact angle is obtained from the relationship between the previously obtained frequency ratio and the contact angle, and axial rigidity obtained from the axial natural frequency. And means for determining the preload of the bearing.

[0008]

In the rolling bearing evaluation method of the present invention, in addition to measuring the natural frequency in the axial direction of the rolling bearing, the natural frequency in the angular direction, the natural frequency in the radial direction,
In addition, the step of measuring at least one of the natural frequencies of which the two are coupled, the step of obtaining the frequency ratio of the measured natural frequencies, and the contact angle from the relationship between the previously obtained frequency ratio and the contact angle And the step of obtaining the preload of the bearing from the axial rigidity obtained from the natural frequency in the axial direction, the preload of the bearing can be accurately obtained.

In the rolling bearing evaluation apparatus of the present invention,
In addition to measuring the natural frequency of the rolling bearing in the axial direction, at least one of the natural frequency in the angular direction, the natural frequency in the radial direction, and the natural frequency in which the two are coupled is measured. Measuring means, means for obtaining the frequency ratio of the measured natural frequencies, and a contact angle is obtained from the relationship between the previously obtained frequency ratio and the contact angle, and axial rigidity obtained from the axial natural frequency. It is possible to accurately obtain the preload of the bearing, which includes means for obtaining the preload of the bearing.

The present invention will be described below with reference to specific examples.
First, a general combination bearing as shown in FIG. 1 will be considered. In FIG. 1, a rotary shaft 101 is rotatably supported on a housing 102 by angular contact ball bearings 103 and 104. Here, the contact angle of the bearing is α, and the left and right bearings 103 and 104 are the same. Further, a vibration model of such a system is shown in FIG. In this case, since the vibration mode changes depending on whether the center of gravity position G is in the center of the vibrating body, two types will be considered below.

(A) Case of al = a2 = a First, the case is symmetrical with respect to the center of gravity of the vibrating body. At this time, according to the vibration model of FIG.
The axial rigidity Ka can be expressed by the equations (1) and (2). j is the number of rolling elements. Kr = Σ (Ko (j)) + Ki (j)) cos (α) = Acos (α) (1) Ka = Σ (Ko (j)) + Ki (j)) sin (α) = Bsin (α) ( 2)

Next, the motions of the vibrating body m in the x and y directions and around the center of gravity can be expressed by equations (3) to (6).

[Equation 1]

Equation (6) has the following three eigenvalue solutions because it does not include a coupling term. Here, the natural frequency in the axial direction is Ωa, the natural frequency in the radial direction is Ωr, and the natural frequency in the angular direction around the center of gravity is Ωθ.

[Equation 2]

Here, when the ratio of Ωr and Ωa is calculated as in the equation (10), a function of only the contact angle α is obtained.

[Equation 3]

From this, the contact angle α can be obtained from the natural frequency in the radial direction (Ωr) and the natural frequency in the axial direction (Ωa). 1 / c ² is a constant determined by the bearing and can be obtained in advance by analysis or experiment.

Next, let us consider a more general case in which the center of gravity of the vibrating body is geometrically asymmetric. (B) In the case of a1 ≠ a2 (i) Similarly, first, the equation of motion is expressed by equations (12), (13),
It is shown in (14) and (15). Here, the motion in the axial direction is the same as that in (a), but the motions in the radial direction and the angular direction are coupled to each other.

[Equation 4]

Here, the solution of the equation (15) is the same as the equation (7) in the non-coupling axial direction and becomes the equation (16), but the equation (17) is changed in the radial direction and the angular direction. It is a complete solution and is different from (a).

[Equation 5]

Further, by substituting the equations (8) and (9) into the equation (17), the following equation is obtained.

[Equation 6]

Further, by solving the equation (18), the following solution is obtained.

[Equation 7]

Here, as in (a), Ωa which is a non-coupling component.
Taking the quotient of equation (19) by the square of and using equation (10), the following equation is obtained. Equation (20) has two solutions with multiple solutions, and using either of them, a function of only α can be obtained.
Specifically, the contact angle α can be obtained by the ratio of any one of the two natural frequencies Ωr and Ωθ measured in addition to the axial natural frequency Ωa to Ωa.

[Equation 8]

Similar to (a), the function of the contact angle α can be obtained by taking the ratio with Ωa. Since the coefficient of tan (α) and other terms can be obtained by analysis and experiment, if Ωa and another natural frequency Ω are obtained,
The contact angle α can be obtained.

Further, if the contact angle is obtained as in (a) and (b), the axial rigidity Ka can be estimated from Ωa, so that the bearing preload can also be obtained. According to this method, even if the contact angle varies due to the dimensional tolerance of the bearing and the preload cannot be accurately evaluated only by the axial rigidity of the bearing, the preload can be evaluated.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a schematic configuration diagram showing the overall configuration of the rolling bearing evaluation apparatus according to the present embodiment. As shown in FIG. 3, such an evaluation device includes a vibrating section 1 that applies vibration of a predetermined frequency to a bearing to which a preload has been applied.
And a vibration detection unit 2 for detecting the vibration of the outer ring of the bearing, the rigidity of the bearing 4 is obtained from the detected vibration of the outer ring of the bearing, and the rigidity is given to the bearing from the obtained bearing rigidity. An arithmetic processing unit 3 for calculating the preload,
A double row bearing (hereinafter, simply referred to as a bearing) 4 made up of a hub III bearing attached to a wheel of an automobile is attached to this apparatus as a measured bearing.

The bearing 4 includes an outer ring 42 having two rows of rolling surfaces formed on the inner circumference thereof, and a hub shaft 41 having a rolling surface opposite to one of the rolling surfaces of the outer ring 42 formed on the outer circumference thereof. Outer ring 4
2 has an inner race member 45 formed on the outer circumference with a raceway surface facing the other raceway surface of the inner race member 45,
1, the inner ring member 45 and the hub shaft 41 cooperate with each other to form an inner ring with respect to the outer ring 42. Outer ring 4
Balls 43 and 44 are inserted between the two and the hub shaft 41 and the inner ring member 45. A flange portion 41a is integrally formed at one end of the hub shaft 41, and the flange 41a is provided with a plurality of holes for receiving bolts 47 for fixing the bearing 4 to a mounting target portion. A shoulder portion is formed at an intermediate portion of the hub shaft 41, and a screw portion 41b into which the nut 46 is screwed is formed at the other end portion. The inner ring member 45 is
The end portion is pressed against the shoulder portion of the hub shaft 41 and is tightened by a nut 46 screwed to the screw portion 41b, and by this tightening, a ball 43 between the outer ring 42 and the hub shaft 41 and the inner ring member 45, A preload is applied to 44. Further, a negative gap is formed between the end faces of the outer ring 42 and the hub shaft 41 that face each other.

The vibrating section 1 has an oscillator 1a for generating a voltage waveform that sweeps a sine wave from the lower limit to the upper limit frequency of the measurement frequency band at a high speed, and an amplitude and a frequency corresponding to the voltage waveform generated by the oscillator 1a. An electrodynamic exciter 1b that generates an excitatory force, and an exciter rod 1 for transmitting the excitable force generated by the electrodynamic exciter 1b to the hub shaft 41 of the bearing 4.
c and a vibration isolation base 1d for fixing the first inner ring 41 of the bearing 4, and the flange portion 41a of the first inner ring 41 is placed on the vibration isolation base 1d. Here, 1 to 10 KHz is set as the measurement frequency band, and a sine wave having a constant amplitude is swept to generate a voltage waveform, thereby
It is set to generate an exciting force having a constant amplitude at 10 KHz. Therefore, vibration is excited in the bearing 4 by the above-mentioned exciting force. The vibration modes excited in the bearing 4 include an axial rigid body mode (a vibration mode in the axial direction of the bearing 4) and a conical rigid body mode (vibration due to the inclination of the outer ring 42) due to the bearing spring in the frequency band of the exciting force. ) And the flange portion 41 of the hub shaft 41 in the local mode.
The elastic bending mode of a and the elastic bending mode of the outer ring 42 are included.

The vibration detecting section 2 which is a measuring means includes a vibration detecting sensor 21a arranged at the center of the hub shaft 41.
And 180 for detecting the axial vibration of the outer ring 42, respectively.
A pair of vibration detection sensors 21b, 21 arranged at a distance
c and a vibration detection sensor 21d that detects the radial vibration of the outer ring 42. Each vibration detection sensor 21a, 21
Reference numerals b, 21c, and 21d are moving coil type sensors, and the sensors output the detected vibration waveform as a voltage signal. Here, each vibration detection sensor 21a, 21b, 21
The vibrations detected by c and 21d are vibrations in which the respective vibration modes excited in the bearing 4 are superimposed on each other.

Each vibration detection sensor 21 for the outer ring 42
The output signals of b and 21c correspond to the summing amplifiers 22a and 22a,
After being amplified by 22b, they are added in time series by the adder 23, and the vibration component of the conical rigid body mode is eliminated by this addition. That is, the signal output from the adder 23 is
The signal has the vibration component of the conical rigid body mode removed. On the other hand, the signal output from the subtractor 25 is a signal in which the vibration component of the translational rigid body mode is eliminated. Adder 23
The signal output from is amplified by the main amplifier 24a and then input to the high-pass filter 25a. here,
Since the main amplifier 24a is a signal obtained by adding the input signals, the level of the main amplifier 24a is reduced to 1/2. this is,
This is because the vibration level of the sensor 21a needs to be the same in order to perform the transfer function calculation in the calculation processing unit 3. The signal output from the subtractor 26 is also the main amplifier 24.
c, and is input to the high pass filter 25c. The signals from the subtractor are subtracted to obtain the sensors 21b and 21c.
Since the local mode of the flange portion 41a of the hub shaft 41 which has the same phase is eliminated and the calculation processing unit 3 does not need to perform the transfer function calculation, it is not necessary to reduce the level of the main amplifier 24c like 24a. .

As for the signal of the sensor 21d, when the natural frequency in the radial direction is measured as shown in FIG. 8, the S / N ratio may be improved as compared with the case where the natural frequency in the angular direction is measured. In addition, it is used by switching depending on the object to be measured. Signal processing is performed by the main amplifiers 24c and 25.
same as c. In addition, the signal of 21d is not affected because the measurement direction is 90 degrees out of phase with the vibration of the local mode due to the flange portion 41a of the hub shaft 41.
It can be directly input to the main amplifier 24d. The high-pass filter 25a cuts frequency components (500 Hz to 1 kHz) below the measurement frequency band from the input signal. That is, the S / N ratio can be improved by cutting the vibration component of 500 Hz to 1 KHz that causes external noise with the high-pass filter 25a. On the other hand, the output signals of the vibration detection sensors 21a and 21d are input to the high-pass filters 25b and 25c after being amplified by the main amplifiers 24b and 24c, and the high-pass filters 25b and 25c are below the measurement frequency band from the input signals. Frequency components (500 Hz to 1 KHz), that is, vibration components that cause external noise are cut.

The arithmetic processing unit 3, which is a means for obtaining the frequency ratio and a means for obtaining the preload, is provided with each high-pass filter 25a.
It has a transfer function operation device 3a for inputting the output signal of 25b and a frequency analysis device 3f for inputting the output signals of the high-pass filters 25c and 25d, both of which are fast Fourier transform (F
FT: Fast Fourier Transform
Use m). The transfer function calculation device deletes the in-phase component included in each of the input signals to calculate the resonance frequency (natural frequency) fa of the bearing 4. Specifically, FFT
Then, the transfer function H between the inner and outer rings (between the hub shaft 41 and the outer ring 42) is calculated, and the local mode vibration component (in-phase component) included in each input signal is deleted from this transfer function H. A vibration mode in which the resonance frequency (natural frequency) fa appears where the phases are different by π / 2 is obtained. The component of this vibration mode is represented by the transfer function H as a vibration component in which the axial rigidity mode and the elastic bending mode of the outer ring 42 are coupled. This transfer function H is calculated by the following equation (21). H (f) = Sy (f) .Sx * (f) / Sx (f) .Sx * (f) (21) where Sx (f) .Sx * (f) is the output power of the high-pass filter 25b. Spectrum, Sy (f) / Sx *
(F) is a cross spectrum of the output of the high pass filter 25a and the output of the high pass filter 25b. The frequency analyzer determines two resonance frequencies in the radial direction and the angular direction. Of these, the vibration component having a high S / N ratio is adopted to obtain the preload.

The vibration waveform obtained from the transfer function is displayed on the waveform display device 3b, and the vibration waveform obtained from the frequency analysis device is displayed on the waveform display device 3b.
It is displayed in g. Further, the obtained resonance frequency (natural frequency) fa is input to the stiffness conversion computing device 3c.
The stiffness conversion calculation device 3c approximates the relationship between the bearing stiffness Ka and the resonance frequency (natural frequency) fa previously obtained by FEM analysis with a polynomial, and inputs the resonance frequency (natural frequency) fa using the polynomial. Calculate the bearing stiffness Ka with respect to. Specifically, as a function showing the relationship between the bearing stiffness Ka and the resonance frequency (natural frequency) fa, the following (22)
Since the function shown in the equation is defined, the contact angle α is given in advance to obtain a discrete value by FEM analysis, and the function is approximated by a polynomial having the resonance frequency (natural frequency) fa as a variable from the discrete value, By converting the resonance frequency (natural frequency) fa obtained using this polynomial into the bearing rigidity Ka,
The bearing rigidity Ka is calculated. Ka = f (fa, α) (22) [0031] Further, the bearing rigidity Ka and the axial natural frequency Ωa obtained above and Ω (either Ωr or Ωθ) obtained by the frequency analysis device are the preload calculation device. 3e is input. The preload calculation device 3e receives the input bearing rigidity Ka.
Based on the above, the preload amount Fa applied to the bearing 4 is obtained. Specifically, the preload amount Fa applied to the bearing 4 is calculated by the following (23)
Since it is defined by the function shown in the formula, the contact angle α is given in advance, the above function is approximated by a polynomial, and the preload amount Fa is obtained from the bearing rigidity Ka obtained by using this polynomial. Fa = f (Ka, α) (23)

The method of obtaining the bearing rigidity Ka and the preload amount Fa from the contact angle α and the resonance frequency (natural frequency) fa is "NSK Report" 1989 issued by the applicant.
It is described on pages 59 to 66 of the November issue of the year, and the detailed description thereof is omitted. In this way, the arithmetic processing unit 3
The value of the bearing rigidity Ka and the amount of preload Fa obtained in step 3 are displayed on the display device 3d.

FIG. 4 shows the vibration modes measured by the above-mentioned evaluation device, which are obtained by FEM analysis. Vibration mode 1 is a vibration mode when vibrating at a natural frequency (Ω) in which an angular direction and a translation mode are coupled, and vibration mode 2 is a vibration mode when vibrating at an axial natural frequency (Ωa). The vibration frequency is determined by the axial rigidity of the bearing and the mass of the outer ring.

Each of these two natural frequencies can be measured. Step (1): The bearing rigidity in the axial direction is obtained from the measured Ωa. Step (2): However, as is apparent from FIG. 5, when the contact angle (α) changes, it is impossible to evaluate the preload only by the axial rigidity. Here, Ω / Ωa is obtained by using the two measured natural frequencies Ωa and Ω.
Here, (Ω-Ωa) / Ωa (hereinafter, frequency ratio) may be used instead of Ω / Ωa.

FIG. 6 is a plot of the relationship between the frequency ratio and the contact angle, in which the preload (negative clearance) was changed to −3 μm, −15 μm, and −28 μm at each contact angle. From the figure, it can be seen that if this frequency ratio is used, the contact angle can be obtained regardless of the preload amount. The contact angle range is set so that the contact angle may change due to dimensional tolerance or the like.

Step (3): FIG. 7 shows the relationship between the frequency ratio and the preload, which are considered to be the characteristic characteristic of axial rigidity (Ωa) and the characteristic characteristic of contact angle, which is considered to be the characteristic characteristic of axial rigidity. is there. If the relationship between the axial rigidity and the contact angle and the preload is obtained in advance by experiments and analysis, the preload can be evaluated in the preloaded composite bearing by measuring Ωa and Ω by this method. it can. As shown in FIG. 5, even when the natural frequency in the axial direction (rigidity in the axial direction) is almost the same, the preload can be correctly evaluated by using the frequency ratio. As described above, the axial rigidity, the contact angle, and the preload can be evaluated by Ωa and Ω from steps (1) to (3). In this way, by measuring the natural frequency obtained by vibrating the bearing, the contact angle and the preload of the combined bearing to which the preload is applied can be easily evaluated.

[0036]

In the rolling bearing evaluation method of the present invention, in addition to measuring the natural frequency in the axial direction of the rolling bearing, the natural frequency in the angular direction, the natural frequency in the radial direction, and the two A step of measuring at least one of the coupled natural frequencies, a step of obtaining a frequency ratio of the measured natural frequencies, and a contact angle obtained from the relationship between the frequency ratio and the contact angle obtained in advance, Since the step of obtaining the preload of the bearing from the axial rigidity obtained from the natural frequency in the axial direction is performed, the preload of the bearing can be obtained with high accuracy.

In the rolling bearing evaluation apparatus of the present invention,
In addition to measuring the natural frequency of the rolling bearing in the axial direction, at least one of the natural frequency in the angular direction, the natural frequency in the radial direction, and the natural frequency in which the two are coupled is measured. Measuring means, means for obtaining the frequency ratio of the measured natural frequencies, and a contact angle is obtained from the relationship between the previously obtained frequency ratio and the contact angle, and axial rigidity obtained from the axial natural frequency. It is possible to accurately obtain the preload of the bearing, which includes means for obtaining the preload of the bearing.

[Brief description of drawings]

FIG. 1 is a schematic view of a combined bearing.

FIG. 2 is a diagram showing a model of a vibration system of the combined bearing of FIG.

FIG. 3 is a schematic configuration diagram showing an overall configuration of a rolling bearing evaluation device according to the present embodiment.

FIG. 4 is a diagram showing vibration modes at measured natural frequencies.

FIG. 5 is a diagram showing the relationship between rigidity and preload when the contact angle changes.

FIG. 6 is a diagram showing a relationship between a parameter obtained from a natural frequency ratio and a contact angle.

FIG. 7 is a diagram showing the relationship among preload, rigidity and contact angle.

FIG. 8 is a diagram showing vibration modes at measured natural frequencies.

[Explanation of symbols]

1 Vibration part 1a oscillator 1b Electrodynamic vibration exciter 1c Excitation rod 1d anti-vibration table 2 Vibration detector 3 arithmetic processing unit 3a Transfer function computing device 3b Waveform display device 3c Rigidity conversion computing device 3d display device 4 Double row bearing 21a, 21b, 21c, 21d Vibration detection sensor 22a, 22b Summing amplifier 23 adder 24a, 24b, 24c Main amplifier 25a, 25b, 25c High-pass filter 41 hub shaft 41a Flange part 42 outer ring 43,44 balls 45 Inner ring member 46 nuts

Claims (2)

[Claims] 1. In a rolling bearing evaluation method, in addition to measuring the natural frequency in the axial direction of the rolling bearing, the natural frequency in the angular direction, the natural frequency in the radial direction, and the combination of the two. Measuring at least one of the natural frequencies; determining the frequency ratio of the measured natural frequencies; determining the contact angle from the relationship between the frequency ratio and the contact angle determined in advance; A method for evaluating a rolling bearing, comprising the step of obtaining a preload of the bearing from the axial rigidity obtained from the natural frequency of. 2. In a rolling bearing evaluation device, in addition to measuring the natural frequency in the axial direction of the rolling bearing, the natural frequency in the angular direction, the natural frequency in the radial direction, and the combination of the two. Measuring means for measuring at least one of the natural frequencies; means for obtaining a frequency ratio of the measured natural frequencies; and a contact angle obtained from the relationship between the frequency ratio and the contact angle obtained in advance, and the axis A method for evaluating a rolling bearing, comprising: means for determining a preload of the bearing from axial rigidity obtained from the natural frequency in the direction.