JP2001200841A - Bearing abnormality detecting device in bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect damage with high accuracy when fine damage exists on the raceway surface of a bearing for supporting a spindle. SOLUTION: In a bearing device for supporting a spindle 3 by bearings 2 installed to the inside of a housing 1, mounting recessed parts are provided in a ring-like member 5 which is to be subjected to pre-loads of the bearings 2, and piezoelectric film sensors 25 are installed to the mounting recessed parts. Output signals outputted from the sensors are processed to detect damage on the raceway surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing abnormality detecting device in a spindle bearing device.

[0002]

2. Description of the Related Art In bearings of various bearing devices, if damage such as peeling off or abrasion of a raceway surface occurs, vibration occurs in the shaft, and the function of the bearing device is impaired. For this reason,
In order to detect the above-mentioned damage at an early stage, an acceleration pickup is attached to the apparatus to detect the magnitude of vibration of the shaft. Further, a method of detecting a displacement amount of a shaft runout may be used.

Further, a piezoelectric film sensor is attached on the back side of the raceway surface of the bearing or around the fixed shaft, and the damage of the bearing is detected by a signal waveform of a certain level or more in the vibration waveform detected by the sensor. A known method is also known (see JP-A-8-110285).

[0004]

However, the above-mentioned conventional detection method is suitable for detecting a relatively large damage to a bearing, but it is suitable for detecting a small damage such as small peeling of the bearing and initial wear. In the case of severe damage, the vibration of the shaft is small, so that it is mixed with the vibration transmitted from another device or the like, and it is difficult to separate a vibration component caused by damage to the bearing.

Accordingly, the present invention is to make it possible to detect damage to a bearing based on a change in the preload when a preload is applied to the bearing as in a bearing device incorporating a bearing for supporting a spindle. Another object of the present invention is to make it possible to accurately detect minute damage to a bearing.

[0006]

In order to achieve the above object, a bearing abnormality detecting device in a bearing device according to the present invention comprises a bearing for supporting a spindle inserted into a housing, and a preload applied to the bearing. A supporting step for supporting the bearing is provided on an inner diameter surface of the housing, and a piezoelectric film sensor is mounted on an annular member interposed between the bearing and the supporting step. It adopts the configuration described above.

[0007] According to the above configuration, when the spindle oscillates due to damage in the bearing race, the deflection causes a radial load change and an axial load change to the bearing. The change results in a change in the preload of the bearing, causing distortion of the annular member. The piezoelectric film sensor outputs an electromotive force according to the magnitude of the distortion.

A configuration in which a mounting recess is provided in the annular member, and the piezoelectric film sensor is mounted in the mounting recess;
The mounting recesses are provided at positions corresponding to the positions of the rolling elements of the bearing, and the mounting recesses are provided at four circumferential positions on one surface of the annular member, and two adjacent mounting portions are mounted. It is possible to adopt a configuration in which one set of recesses is formed, and a lead wire extraction groove is formed between each set of mounting recesses.

According to these configurations, since the piezoelectric film sensor and the lead wire do not affect the parallelism of the annular member, the bearing rigidity can be kept high.

[0010] As another mounting configuration of the piezoelectric film sensor when the parallelism of the annular member is not required to be high, an annular member is interposed between the bearing and the supporting step portion, and between the bearing and the annular member, or A configuration in which a piezoelectric film sensor is sandwiched between the annular member and the supporting step can be employed.

In the above-described bearing abnormality detecting device, in order to improve the detection accuracy, a piezoelectric film sensor is disposed at a position symmetrical about the center of the spindle, and output signals output from the piezoelectric film sensors are respectively transmitted. Can be adopted in which the absolute value of the sum is added and combined. As a result, even if the output signal of each piezoelectric film sensor is minute, it becomes larger by adding the signals,
It can be distinguished from noise, and the detection accuracy is improved.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the bearing device according to the first embodiment shown in FIGS. 1 to 5, a pair of bearings 2 and 2 ′ (ball bearings in the illustrated case) are fixed to both ends inside the housing 1, respectively, and are inserted through the housing 1. The spindle 3 is rotatably supported by the bearings 2 and 2 '.

As shown in FIG. 2, the inner end surface of the one bearing 2 has a support step 4 provided on an inner diameter surface of the housing 1.
Is pressed through the annular member 5. Further, on the outer end surface of the bearing 2, an outer ring fixing member 6 pressed against the end surface of the outer ring 2 a, which is a fixed race, is fixed to the housing 1 by bolts 7.

Further, a preload applying member 8 pressed against the end face of the inner race 2b, which is a rotating race ring, is fitted to the outer diameter surface of the spindle 3 and is screwed to the screw portion 9 at the tip of the spindle 3. The preload adjusting nut 11 is pressed against the preload applying member 8. A cover member 12 that covers the outer peripheral surface of the preload adjusting nut 11 and the outer peripheral end portions of the preload applying member 8 and the outer ring fixing member 6 is fixed to the outer ring fixing member 6 with bolts 13.

As shown in FIG. 1, at the opposite end of the housing 1, a supporting step 1 provided on an inner diameter surface thereof is provided.
4, a spring 16 is housed via a spring receiving washer 15, and an annular member 17 is interposed between the spring 16 and the inner end face of the outer ring 2'a of the bearing 2 '. Further, a preload applying member 19 screwed to the screw portion 18 of the spindle 3 is pressed against the inner end surface of the inner ring 2′b of the bearing 2 ′. Reference numeral 20 denotes a lubrication oil supply port.

In the above bearing device, when the preload adjusting nut 11 is rotated, the inner race 2 is rotated via the preload applying member 8.
b is pushed in, and a predetermined preload is applied to the bearing 2. The preload is supported by the supporting step 4 via the annular member 5. On the other side of the housing 1, when the preload applying member 19 is rotated, a predetermined preload is applied to the bearing 2 '. The preload is the ring member 1
7 and is supported by the supporting step portion 14.

As shown in FIG. 4, the annular member 5 on the bearing 2 side has four mounting recesses 21 radially transversely crossed on one surface in the axial direction at equal intervals in the circumferential direction. It is provided in the shape. Two adjacent ones of these mounting recesses 21 are set as one set, and a lead wire extracting groove 22 is provided between the mounting recesses 21 of each set. Each lead wire outlet groove 22
A take-out port 23 opened to the outside diameter side is provided at an intermediate portion of the take-out port.

The number of the mounting recesses 21 and the pitch in the circumferential direction are desirably set equal to the number of rolling elements of the bearing 2 and the arrangement pitch. A detent hole 24 is provided on the outer diameter surface of the annular member 5.

As shown in FIG. 3, each of the mounting recesses 2
The piezoelectric film sensor 25 is fixed to the bottom of the first. The piezoelectric film sensor 25 is formed of a piezoelectric polymer that generates an electromotive force according to the magnitude of the distortion when the film itself is distorted, and a lead wire 26 is connected to one end thereof. The lead wire 26 is led out to the same lead wire outlet groove 22 for each set, and the outlet 2
3 and is connected to an external signal processing device 27 (see FIG. 5) through a hole 28 in the housing 1.

The above-mentioned annular member 5 is prevented from rotating by inserting the distal end of the fixing pin 29 screwed from the outside of the casing 1 into the above-mentioned rotation stopping hole 24.
Each piezoelectric film sensor 25 is positioned so as to match the position of each rolling element 10.

The signal processing device 27 shown in FIG. 5 comprises a pair of piezoelectric film sensors 25, 25 located at a centrally symmetric position.
Is amplified by the amplifying circuit 31 and then input to the synthesizing processing circuit 32, and for a signal having a certain threshold value or more, the output signal (+ a) of one piezoelectric film sensor 25 is amplified to + A and Amplify the other output signal (-a) generated at the same time to -A, change its sign, and add these to obtain a composite signal (+ 2A). In short, the signal processing circuit 32 adds the absolute values of both output signals. The result of the combining process is displayed on the monitor 33 as appropriate.

The first embodiment is as described above.
If the spindle 3 is installed in the vertical direction and the spindle 2 is driven in a state where the bearings 2, 2 ′ are applied with a predetermined amount of preload, when the raceway surface of the bearing 2 is worn or peeled, An abnormal run-out of the spindle 3 occurs. Due to the deflection, a change in the load in the radial direction and a change in the load in the axial direction are given to the bearing 2. The change results in a change in the preload of the bearing 2, causing distortion in the annular member 5. The piezoelectric film sensor 25 outputs an electromotive force according to the magnitude of the distortion.

At this time, one output signal of the pair of piezoelectric film sensors 25 provided at the centrally symmetric position is a positive signal in the direction in which the load increases from the level of the initial load, while the other output signal is used. Is a negative signal in the direction in which the load decreases from the level of the initial load. Therefore,
When the signals are combined by the signal processing circuit shown in FIG. 5 after amplification, a doubled output signal (2A) is obtained.

In the above embodiment, the abnormality detecting device for one of the bearings 2 has been described. However, the same configuration can be adopted for the bearing 2 '. This is the same in the following embodiments.

Next, in the second embodiment shown in FIGS. 6 to 8, between the bearing 2 and the supporting step 4, the annular member 5 is arranged on the bearing 2 side, and the washer 34 is arranged on the supporting step 4 side. The piezoelectric film sensor 25 is sandwiched between the annular member 5 and the washer 34. The annular member 5 in this case
As shown in FIG. 8, concave surfaces 3
5 are provided, and the piezoelectric film sensors 25 are fixed to a total of four positions on both ends of the land portion 36 between the concave surfaces 35. Then, as shown in FIG. 7, each lead wire 26 of two adjacent piezoelectric film sensors 25 is put together at the concave surface 35. The lead wire 26 is connected to the hole 28 of the housing 1.
From the outside. Other configurations are the same as those of the first embodiment.

In the case of the second embodiment, the spindle 3
The change in the preload caused by the vibration of the piezoelectric element directly acts on the piezoelectric film sensor 25, and distorts this to output an electromotive force.

Next, in the third embodiment shown in FIGS. 9 and 10, an annular member 5 is disposed on the supporting step portion 4 and a piezoelectric film sensor is provided between the annular member 5 and the outer ring 2a of the bearing 2. 25 is sandwiched. As shown in FIG. 10, the piezoelectric film sensor 25 in this case is formed to have a narrow width of about half of the annular member 5 and the outer ring 2 a of the bearing 2.
Is formed so as to be substantially equal to the width.

The other configuration and operation are the same as those of the above-described second embodiment. Therefore, the same portions are denoted by the same reference numerals, and description thereof will be omitted.

[0029]

As described above, according to the present invention, when the shaft vibrates due to damage on the raceway surface of the bearing, the preload of the bearing changes, and the change can be detected by the piezoelectric film sensor via the annular member. it can. A large signal is obtained by providing the above piezoelectric film sensor at a centrally symmetric position and adding the absolute values of both output signals,
It can be distinguished from noise transmitted from other devices.
Therefore, highly accurate detection can be performed even if the damage on the raceway surface is minute.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a bearing device according to a first embodiment.

FIG. 2 is a partially enlarged sectional view of the above.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a perspective view of the annular member according to the first embodiment;

FIG. 5 is a block diagram of a signal processing circuit of the above.

FIG. 6 is a partial cross-sectional view of the second embodiment.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 6;

FIG. 8 is a perspective view of the above annular member.

FIG. 9 is a partial cross-sectional view of the third embodiment.

FIG. 10 is a sectional view taken along line XX of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2, 2 'Bearing 2a, 2'a Outer ring 2b, 2'b Inner ring 3 Spindle 4 Support step part 5 Annular member 6 Outer ring fixing member 7 Bolt 8 Preload applying member 9 Screw part 10 Rolling element 11 Preload adjusting nut 12 Cover Member 13 Bolt 14 Support step 15 Spring receiving washer 16 Spring 17 Annular member 18 Screw part 19 Preload applying member 20 Oil filler 21 Mounting recess 22 Lead wire extraction groove 23 Extraction port 24 Lock hole 25 Piezoelectric film sensor 26 Lead wire 27 Signal Processing Device 28 Hole 29 Fixing Pin 31 Amplification Circuit 32 Synthesis Processing Circuit 33 Monitor 34 Washer 35 Concave Surface 36 Land

Claims (7)

[Claims] 1. A bearing device comprising a bearing for supporting a spindle inserted through a housing and a preload applying means for applying a preload to the bearing, wherein a supporting step for supporting the bearing is provided on an inner diameter surface of the housing. An abnormality detecting device for a bearing in a bearing device, wherein a piezoelectric film sensor is attached to an annular member provided between the bearing and the supporting step. 2. The bearing abnormality detecting device according to claim 1, wherein a mounting recess is provided in the annular member, and the piezoelectric film sensor is mounted in the mounting recess. 3. The bearing abnormality detecting device according to claim 2, wherein the mounting recess is provided at a position corresponding to a position of each rolling element of the bearing. 4. The mounting recesses are provided at four circumferential positions on one side of the annular member, and two adjacent mounting recesses form one set, and a lead is provided between each set of mounting recesses. 2. A wire taking-out groove is formed.
4. A bearing abnormality detecting device in the bearing device according to any one of claims 1 to 3. 5. A bearing device comprising: a bearing for supporting a spindle inserted through a housing by a bearing mounted inside the housing; and a preload applying means for applying a preload to the bearing. A support step is provided on the inner diameter surface of the housing, an annular member is interposed between the bearing and the support step, and between the bearing and the annular member, or between the annular member and the support step, An abnormality detection device for a bearing in a bearing device characterized by sandwiching a piezoelectric film sensor. 6. The method according to claim 1, wherein the piezoelectric film sensor is disposed at a position symmetrical with respect to the center of the spindle, and an output signal output from each piezoelectric film sensor is combined with an absolute value of each of the signals. An abnormality detection device for a bearing in the bearing device according to claim 1. 7. The bearing according to claim 1, wherein said housing is provided with engagement means for said annular member, thereby preventing rotation of said annular member. An abnormality detection device for bearings in equipment.