KR20210081410A - bearing device - Google Patents

Abstract

The bearing device 2 includes bearings 5a and 5b including inner rings 5ia and 5ib, outer rings 5ga and 5gb and rolling elements Ta and Tb, and a spindle 4 supported by the bearings 5a and 5b. ) disposed adjacent to the bearings 5a, 5b, and a spacer 6 including an inner ring spacer 6i and an outer ring spacer 6g, and a sensor unit disposed on the inner ring spacer 6i or the outer ring spacer 6g (9) is provided. The sensor unit 9 includes a first sensor and a second sensor. The first sensor is a heat flow sensor 10 , and the second sensor includes at least one of a vibration sensor 11 , a temperature sensor 12 , and a load sensor 13 . The bearing device 2 also includes an abnormality diagnosis processing device 15 for diagnosing an abnormality in the bearing based on the outputs of the first and second sensors, and the rotational speed N of the main shaft 4 .

Description

bearing device

The present invention relates to a bearing device, and more particularly, to a bearing device having a function of diagnosing signs such as seizure of a bearing used for a main spindle spindle of a machine tool.

In the spindle device of a machine tool, it is calculated|required to detect a sign of an abnormality before a bearing occurs, and to prevent abnormality of a bearing in advance.

In the assembled diagnostic device described in Japanese Patent Application Laid-Open No. 2017-90318 (Patent Document 1), a thermal buffer sandwiched between two heat flow sensors (also referred to as a heat flux sensor) is fixed to the measurement target, and the two heat flow sensors The proper preload condition of the bearing is diagnosed from the signal, and the assembly condition is determined.

In the bearing device with a sensor described in Japanese Patent Application Laid-Open No. 2004-169756 (Patent Document 2), a sensor portion is provided in the outer ring spacer. The sensor unit includes at least one of a vibration sensor, a temperature sensor, and a rotation speed sensor. An abnormal state of the bearing is detected from this at least one sensor signal.

In the apparatus for diagnosing an abnormality of a rotating body described in Japanese Patent Laid-Open No. 2004-93185 (Patent Document 3), the wave generated from the rotating body, the temperature and the rotational speed of the rotating body are detected, and an abnormality diagnosis is performed based on these information.

Japanese Patent Application Laid-Open No. 2017-90318 Japanese Patent Laid-Open No. 2004-169756 Japanese Patent Laid-Open No. 2004-93185 Japanese Patent Application Laid-Open No. 2014-071085

In the case of the heat flow sensor described in Japanese Patent Application Laid-Open No. 2017-90318 (Patent Document 1), it may be difficult to determine the proper assembly state of the bearing. For example, in a spindle device of a machine tool, a cooling medium flow path is usually formed on the outer peripheral surface of a housing, and the spindle device is cooled by flowing a cooling medium thereto. When the sensor part is fixed to the cylindrical surface of the outer diameter of the housing near the cooling medium flow path, it is also assumed that the heat flow sensor cannot accurately measure the heat generated by the difference in the rotational speed or preload of the bearing during operation.

In addition, the sensor unit described in Japanese Patent Application Laid-Open No. 2017-90318 (Patent Document 1) sandwiches a heat buffer between the first heat flow sensor and the second heat flow sensor, and a heat sink is disposed on the second heat flow sensor on the side away from the housing. is a structure that has been In this structure, since there are many components, space for arranging a sensor part is required, and since two heat flow sensors are used for one sensor part, the cost of an apparatus increases.

In addition, a cooling medium flow path is usually formed in the housing of the spindle device of the machine tool. The bearing is cooled by flowing a cooling medium through the housing. When applying for bearing diagnosis of a spindle device of a machine tool, it is assumed that fixing the sensor part to the outer diameter cylindrical surface of the housing will affect the measurement sensitivity, making accurate measurement impossible.

Since the heat capacity of metal parts such as housing, spacer, and main shaft is large, the temperature sensor attached to the outer ring spacer of JP-A-2004-169756 (Patent Document 2), when abnormal heat is generated in the bearing, the temperature change in the member to be measured It takes time to occur, and it is difficult to quickly detect an abnormal state.

Moreover, the vibration sensor of Unexamined-Japanese-Patent No. 2004-93185 (patent document 3) detects abnormal vibration by bearing damage. However, since the vibration is caused by damage to the bearing and is generated, it is difficult for the vibration sensor of Patent Document 3 to detect abnormal signs at an early stage.

The present invention has been made in order to solve the above problems, and an object of the present invention is to provide a bearing device having an abnormality diagnosis function capable of quickly and accurately detecting a sign such as seizure of a bearing used for a main spindle spindle of a machine tool, etc. .

The present disclosure relates to a bearing device. The bearing device includes a first bearing including an inner ring, an outer ring and a rolling element, a spacer disposed adjacent to the first bearing on a shaft supported by the first bearing, and including an inner ring spacer and an outer ring spacer, the first bearing or spacer; A first sensor and a second sensor disposed in the. The first sensor is a heat flow sensor, and the second sensor includes at least one of a heat flow sensor, a vibration sensor, a temperature sensor, and a load sensor. The bearing device also includes an abnormality diagnosis device that determines abnormality based on the output of the first sensor and the output of the second sensor.

Preferably, the second sensor includes at least one of a vibration sensor, a temperature sensor, and a load sensor. The abnormality diagnosis apparatus diagnoses the abnormality of the bearing based on the outputs of the first and second sensors and the rotational speed of the shaft.

More preferably, the abnormality diagnosis apparatus includes a threshold value storage unit and a diagnostic processing unit that performs diagnostic processing on the basis of the threshold value stored by the threshold value storage unit on signals from a sensor unit including the first sensor and the second sensor.

More preferably, the threshold value storage unit stores, for each of the first sensor and the second sensor, a threshold value corresponding to each of a plurality of rotational speeds.

More preferably, when the output of the first sensor does not exceed the threshold value corresponding to the first sensor memorized by the threshold storage unit, the diagnostic processing unit does not execute abnormal diagnosis based on the output of the second sensor, and When the output exceeds the threshold corresponding to the first sensor, an abnormality diagnosis is performed based on the output of the second sensor.

More preferably, the threshold storage unit stores a coefficient for weighting the outputs of the first sensor and the second sensor in response to the rotational speed.

More preferably, the abnormality diagnosis apparatus outputs an abnormality diagnosis result according to the size of the total when the sum of the numbers multiplied by the coefficients corresponding to each of the output of the first sensor and the output of the second sensor exceeds a preset threshold. print out

Preferably the bearing arrangement also has a second bearing which supports the shaft together with the first bearing. The first sensor is a first heat flow sensor provided to correspond to the first bearing. The second sensor is a second heat flow sensor provided to correspond to the second bearing. The abnormality diagnosis apparatus detects the presence or absence of occurrence of abnormality in a bearing portion including the first bearing and the second bearing based on a difference in output of the first heat flow sensor and the second heat flow sensor or a difference in output change rate. includes a judging unit.

More preferably, the first bearing and the second bearing respectively support the first part and the second part spaced apart from each other of the shaft.

More preferably the spacer is arranged between the first bearing and the second bearing. The first heat flow sensor and the second heat flow sensor are disposed in the spacer. A position where the first heat flow sensor is disposed on the spacer is closer to the first bearing than a position where the second heat flow sensor is disposed on the spacer. A position where the second heat flow sensor is disposed on the spacer is closer to the second bearing than a position where the first heat flow sensor is disposed on the spacer.

More preferably, based on the sign of the difference, the abnormality determination part judges which bearing of the 1st bearing and the 2nd bearing has an abnormality generate|occur|produced.

More preferably, if N is a natural number equal to or greater than 3, the bearing device includes N heat flow sensors. The first heat flow sensor and the second heat flow sensor are two of the N heat flow sensors. The abnormality determination unit has an amount of change in the output of the sensor group excluding the first heat flow sensor from the N heat flow sensors before and after the lapse of the predetermined time is greater than the first threshold, and the amount of change in the output of the first heat flow sensor is equal to or less than the first threshold. When it is smaller than the second threshold, it is determined that a failure has occurred in the first heat flow sensor.

In another aspect, the present disclosure relates to a spindle device having any of the above bearing devices.

Advantageous Effects of Invention According to the present invention, it is possible to quickly and accurately detect a sign such as seizure of a bearing used for a main spindle spindle of a machine tool or the like.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the schematic structure of the spindle apparatus on which the abnormality diagnosis apparatus is mounted.
Fig. 2 is a block diagram showing details of the sensor unit 9 and the abnormality diagnosis processing device 15;
Fig. 3 is a flowchart for explaining an abnormality diagnosis process executed by the diagnosis processing unit 16;
Fig. 4 is a diagram showing a schematic view of a list of sensor output threshold values for each rotation speed stored in the threshold value storage unit 17;
Fig. 5 is a diagram showing an example when a plurality of thresholds are set;
Fig. 6 is a waveform diagram showing an example of a temporal change of each sensor output and an abnormality diagnosis level E;
Fig. 7 is a diagram showing a list of weighting coefficients for each rotation speed stored in the threshold value storage unit 17;
Fig. 8 is a block diagram of an abnormality diagnosis processing apparatus according to a second embodiment;
Fig. 9 is a flowchart for explaining the processing executed by the diagnosis processing unit 16A in the abnormality diagnosis processing apparatus 15A;
Fig. 10 is a cross-sectional view showing a schematic configuration of a spindle device according to a third embodiment;
Fig. 11 is an enlarged view of a main part on the left side of Fig. 10;
Fig. 12 is a waveform diagram showing an example of output of two heat flow sensors when the bearing is normal;
Fig. 13 is a waveform diagram showing an example of output of two heat flow sensors at the time of bearing abnormality;
Fig. 14 is a block diagram of an abnormality determination unit 125 that determines an abnormality in a bearing from the outputs of two heat flow sensors used in the third embodiment.
Fig. 15 is a block diagram showing the configuration of an abnormality determination unit 125A, which is an improved example of Fig. 14;
Fig. 16 is a diagram showing the structure of a bearing device 130A according to the fourth embodiment in which a main shaft is supported by four bearings.
It is a block diagram of the abnormality determination part 125B which judges the abnormality of a bearing from the output of two heat flow sensors used in Embodiment 4. FIG.
Fig. 18 is a diagram showing another configuration of an abnormality determining unit;
Fig. 19 is a flowchart for explaining the processing executed by the processor 202 in Fig. 18;
Fig. 20 is a flowchart for explaining a process for judging a sensor failure;

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described, referring drawings. In addition, in the following drawings, the same reference number is attached|subjected to the same or corresponding part, and the description is not repeated.

[Embodiment 1]

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the schematic structure of the spindle apparatus mounting the abnormality diagnosis apparatus. The spindle device 1 is applied to, for example, a spindle device of a built-in motor type of a machine tool. In this case, a motor (not shown) is assembled to one end side of the main shaft 4 supported by the spindle device 1, and a cutting tool (not shown) such as an end mill is connected to the other end. The main shaft 4 is rotatably supported by a plurality of bearings 5a and 5b provided in the housing 3 embedded in the inner diameter portion of the outer cylinder 7 .

A bearing device 2 according to the first embodiment includes bearings 5a and 5b , a spacer 6 , a sensor unit 9 , and an abnormality diagnosis processing device 15 . The bearing 5a includes an inner ring 5ia, an outer ring 5ga, a rolling element Ta, and a retainer Rta. The bearing 5b includes an inner ring 5ib, an outer ring 5gb, a rolling element Tb, and a retainer Rtb. The spacer 6 is arranged adjacent to the bearings 5a, 5b on the main shaft 4 supported by the bearings 5a, 5b. The bearing 5a supports the position Pa of the main shaft 4 , and the bearing 5b supports the position Pb of the main shaft 4 . The position Pa and the position Pb are positions spaced apart by the dimension of the spacer 6 . The spacer 6 includes an inner ring spacer 6i and an outer ring spacer 6g.

In the main shaft 4, the inner ring 5ia of the bearing 5a spaced apart in the axial direction and the inner ring 5ib of the bearing 5b are fitted in an interference fit state (press-fit state). An inner ring spacer 6i is disposed between the inner rings 5ia-5ib, and an outer ring spacer 6g is disposed between the outer rings 5ga-5gb.

The bearing 5a is a rolling bearing in which a plurality of rolling elements Ta are disposed between the inner ring 5ia and the outer ring 5ga. The spacing between these rolling elements Ta is maintained by the retainer Rta. The bearing 5b is a rolling bearing in which a plurality of rolling elements Tb are disposed between the inner ring 5ib and the outer ring 5gb. The distance between these rolling elements Tb is maintained by the retainer Rtb.

Although the structure in which the main shaft 4 is supported by the two bearings 5a, 5b is illustrated and demonstrated here, the structure which supports the main shaft 4 by two or more bearings may be sufficient.

FIG. 2 is a block diagram showing details of the sensor unit 9 and the abnormality diagnosis processing device 15 . 1 and 2, the sensor unit 9 is disposed in an inner ring spacer 6i or an outer ring spacer 6g (outer ring spacer 6g in FIG. 1). The sensor unit 9 includes a first sensor and a second sensor. The first sensor is a heat flow sensor 10 , and the second sensor includes at least one of a vibration sensor 11 , a temperature sensor 12 , and a load sensor 13 . The second sensor may include a plurality of the vibration sensor 11 , the temperature sensor 12 , and the load sensor 13 . That is, the sensor unit 9 includes at least one of the vibration sensor 11 , the temperature sensor 12 , and the load sensor 13 in addition to the heat flow sensor 10 .

The rotation sensor 14 may be provided in the sensor unit 9, or a rotation sensor for motor control attached to the motor of the main shaft may also be used.

In the case where the load sensor 13 is a thin film sensor for measuring the preload, it may be disposed so as to be sandwiched between the outer ring spacer 6g and the outer ring 5ga as shown at the position 9c in Fig. 1 . As such a thin film sensor, the thin film sensor of Unexamined-Japanese-Patent No. 2014-071085 can be used, for example. The abnormality diagnosis processing apparatus 15 diagnoses the abnormality of a bearing based on the output of a 1st sensor and a 2nd sensor, and the rotation speed N of the main shaft 4 .

The bearing device 2 uses two angular ball bearings as the bearings 5a and 5b. An outer ring spacer 6g and an inner ring spacer 6i are inserted between the bearings 5a and 5b, and a preload is applied. In the bearing device 2, the sensor unit 9 is fixed to the vicinity of the bearings 5a and 5b serving as heat generation and vibration sources, for example, to an outer ring spacer 6g.

The abnormality diagnosis processing apparatus 15 is fixed to the outer ring spacer 6g, for example. The abnormality diagnosis processing apparatus 15 signal-processes the sensor signal SS from the sensor unit 9, and outputs the determination result JR.

By disposing the heat flow sensor 10 in the vicinity of the bearing heat source (the contact portion between the inner and outer rings and the rolling element), the heat generation state of the bearings 5a and 5b can be detected quickly. In order to accurately determine whether this heat generation is at a normal level or an abnormal level, the abnormality diagnosis processing device 15 uses at least one signal of the vibration sensor 11 , the temperature sensor 12 , and the load sensor 13 to determine the abnormality level. Diagnose. In the spindle device 1 used under various conditions, it is difficult to judge an abnormality or to estimate the cause of the abnormality only with the signal from the heat flow sensor 10, but by grasping the state of the spindle device 1 using other sensors, a more accurate abnormality Diagnosis or estimation of the cause of the abnormality is possible.

Moreover, the abnormality diagnosis processing apparatus 15 is equipped with the function which diagnoses abnormality from a sensor signal, and outputs the determination result JR. By arranging the abnormality diagnosis processing apparatus 15 in the spacer 6 close to the sensor unit 9, the influence of electromagnetic noise can be reduced and measurement accuracy can be improved.

Preferably, as shown in FIG. 2 , the abnormality diagnosis processing device 15 includes a threshold value storage unit 17 and a threshold value storage unit 17 storing the sensor signal SS from the sensor unit 9 . and a diagnostic processing unit 16 that performs diagnostic processing based on the threshold.

3 is a flowchart for explaining an abnormality diagnosis process executed by the diagnosis processing unit 16. As shown in FIG. First, in steps S1 and S2 , the diagnostic processing unit 16 acquires a sensor signal from the heat flow sensor 10 and acquires a sensor signal from the rotation sensor 14 . Further, in steps S3 to S5 , the diagnostic processing unit 16 acquires a sensor signal from at least one of the vibration sensor 11 , the temperature sensor 12 , and the load sensor 13 .

In the threshold value storage unit 17, a threshold value of each sensor output corresponding to the rotational speed is stored in advance. In step S6, the diagnostic processing unit 16 compares each sensor signal with a threshold value of each sensor output corresponding to the rotation speed stored in the threshold value storage unit 17, and executes an abnormality diagnosis processing.

In step S7, when all of the sensor signals do not exceed the corresponding threshold (NO in S7), the diagnostic processing unit 16 determines that there is no abnormality, and outputs a judgment result JR of "OK" in step S8. . On the other hand, in step S7, when the sensor signal of the heat flow sensor 10 exceeds the corresponding threshold, and there is also another sensor that outputs a sensor signal exceeding the threshold (YES in S7), the diagnostic processing unit 16 It is determined that there is an abnormality, and a determination result JR of "NG" is output in step S9. For example, when the sensor output of the heat flow sensor 10 and the output of at least one other sensor exceed a preset threshold, the diagnostic processing unit 16 outputs "NG" as the determination result JR .

Hereinafter, some examples of the abnormality diagnosis processing executed in step S6 of FIG. 3 will be described.

(Anomaly diagnosis processing example 1)

4 is a diagram showing a list of sensor output threshold values for each rotation speed stored in the threshold value storage unit 17 . In the abnormality diagnosis processing example 1, when the output of the heat flow sensor 10 and the output item of at least one of the vibration sensor 11, the temperature sensor 12, and the load sensor 13 exceeds the threshold, the abnormality diagnosis processing apparatus (15) outputs an abnormality determination result.

As the sensor output items, as sequentially shown from the top in FIG. 4 , the sensor output (H) of the thermal flow sensor 10, the amount of time change (ΔH/Δt) of the sensor output of the thermal flow sensor 10, and the load sensor 13 ) of the sensor output (L), the amount of time change (ΔL/Δt) of the sensor output of the load sensor 13, the sensor output (T) of the temperature sensor 12, the amount of time change (ΔT) of the sensor output of the temperature sensor 12 /Δt), the sensor output V of the vibration sensor 11, the maximum value of the power spectrum after frequency analysis of the vibration sensor 11, or the integral value Vf in a specific frequency region are set. The threshold values of these sensor output items are set in advance according to the rotational speed N, as shown in FIG.

That is, as shown in Fig. 4, the threshold value storage unit 17 corresponds to a plurality of rotational speeds for each of the first sensor (heat flow sensor 10) and the second sensor (sensor other than the heat flow sensor), respectively. A plurality of threshold values are stored.

Heat flow and temperature will be described in detail. The threshold value corresponding to the first sensor in heat flow sensor 10, the rotational speed N <2000 (1 / min) threshold (H _1), the rotational speed 2000≤N <4000 (1 / min) which corresponds to about (H ₂ ), the threshold value corresponding to the rotational speed 4000≤N <6000 (1 / min) (H 3), the threshold value corresponding to the rotational speed 6000≤N <8000 (1 / min) (H 4), the rotational speed 8000≤N < and stores in the 10000 (1 / min) threshold ₍₅ H), rotation speed N≥10000 (1 / min), the threshold value set in advance (H _6), and the threshold value storage unit 17 corresponding to the corresponding to the. _{Further, regarding the temperature sensor 12 which is one of the second sensors, the threshold value T 1} corresponding to the rotation speed N < 2000 (1/min), the rotation speed 2000 ≤ N < 4000 (1/min) corresponding to the the threshold value (T _2), the rotational speed 4000≤N <6000 (1 / min) threshold value which corresponds to (T _3), the rotational speed 6000≤N <8000 thresholds corresponding to _{(1 / min) (T 4} ), the rotational speed 8000≤N threshold value corresponding to the <10000 (1 / min) ( T 5), the rotational speed N≥10000 (1 / min) threshold (T _6), the pre-set and stored in the threshold value storage unit 17 corresponding to the make it

For example, three examples of the logical expression of abnormality determination in the rotation speed of 3000 min ^{-1 are shown in (1)-(3) below.}

(H≥H ₂ OR ΔH/Δt≥Ht ₂ ) AND (L≥L ₂ OR ΔL/Δt≥Lt ₂ ) … (One)

(H≥H ₂ OR ΔH/Δt≥Ht ₂ ) AND (T≥T ₂ OR ΔT/Δt≥Tt ₂ ) … (2)

(H≥H ₂ OR ΔH/Δt≥Ht ₂ ) AND (V≥V ₂ OR Vf≥Vf ₂ ) … (3)

In addition, a plurality of threshold values stored in advance in the threshold value storage unit 17 may be set in the rotation speed region, and abnormality determination results such as “normal”, “attention” and “warning” may be output according to the level of abnormality diagnosis. Fig. 5 is a diagram showing an example of setting a plurality of thresholds. 5 shows a list of thresholds when the thresholds at a rotational speed of 3000 min ^{-1 are divided into two stages.} Although not shown, a plurality of threshold values are similarly set for other rotational speeds. Examples of logical expressions at the time of abnormal judgment at this time are shown in (4) to (10) below.

Examples of logical expressions that are judged as “normal”

H<H _2L OR ΔH/Δt<Ht _2L … (4)

An example of a logical expression that judges “attention”

(H _2L ≤H<H _2H OR Ht _2L ≤ΔH/Δt<Ht _2H ) AND (L _2L ≤L<L _2H OR Lt _2L ≤ΔL/Δt<Lt _2H ) … (5)

_{(H 2L ≤H <H 2H OR} Ht 2L ≤ΔH / Δt <Ht 2H) AND (T 2L ≤T <T 2H OR Tt 2L ≤ΔT / Δt <Tt 2H) ... (6)

(H _2L ≤H<H _2H OR Ht _2L ≤ΔH/Δt<Ht _2H ) AND (V _2L ≤V<V _2H OR Vf _2L ≤Vf<Vf _2H ) … (7)

Example of a logical expression that judges “warning”

_{(H 2H ≤H OR Ht 2H ≤ΔH} / Δt) AND (L 2H ≤L OR Lt 2H ≤ΔL / Δt) ... (8)

_{(H 2H ≤H OR Ht 2H ≤ΔH} / Δt) AND (T 2H ≤T OR Tt 2H ≤ΔT / Δt) ... (9)

_{(H 2H ≤H OR Ht 2H ≤ΔH} / Δt) AND (V 2H ≤V OR Vf 2H ≤Vf) ... (10)

In addition, you may estimate the damage state of a bearing, or the cause of damage by the combination of the output of the heat flow sensor 10 and another sensor, and you may output the estimation result. For example, when an excessive load is input from a machining tool attached to the tip of the spindle, the contact surface pressure between the rolling element of the bearing and the inner and outer rings rises, and heat is generated. When abnormality determination is made by the combination of the heat flow sensor 10 and the load sensor 13, the estimated result is output as "abnormal heat generation due to excessive load".

In addition, if the surface roughness of the raceway, which is caused by poor lubrication of the bearing or mixing of foreign substances, progresses, the raceway is damaged and heat is generated. For example, when an abnormality determination is made by the combination of the heat flow sensor 10 and the vibration sensor 11, an estimation result such as "abnormal heat generation due to damage to the track surface" is output.

(Anomaly diagnosis processing example 2)

In the abnormality diagnosis processing example 1, a case in which the sensor output is simply compared with a threshold value corresponding to the sensor output has been described. It is not limited to this, and when the sensor output of the heat flow sensor 10 and at least one other sensor output are weighted and their total exceeds a preset threshold, judgment result to the effect of abnormality (JR) may be printed out. By providing the threshold value and weighting coefficient according to the rotation speed, more accurate abnormal diagnosis suitable for the purpose of abnormality diagnosis can be performed.

Specifically, the diagnostic processing unit 16 weights the output of the heat flow sensor 10 and the output of at least one of the vibration sensor 11, the temperature sensor 12, and the load sensor 13, and outputting an abnormality determination result when the total amount of sensor outputs after weighting calculation (abnormality diagnosis level E) exceeds a preset threshold.

Fig. 6 is a waveform diagram showing an example of the time change of each sensor output and the abnormal diagnosis level E. As shown in Figs. FIG. 7 is a diagram showing a list of weighting coefficients for each rotation speed stored in the threshold value storage unit 17 .

As sequentially shown in FIG. 7 from the top, as items of the weight imparting coefficient, the heat flow sensor output (H), the time change amount of the heat flow sensor output (ΔH/Δt), the load sensor output (L), and the time change amount of the load sensor (ΔL/Δt), temperature sensor output (T), time change amount of temperature sensor (ΔT/Δt), vibration sensor output (V), the maximum value of the power spectrum after frequency analysis of the vibration sensor, or the integral value in a specific frequency region ( Vf) is set. The coefficients for weighting of these sensor output items are set in advance according to the rotation speed.

As shown in Fig. 7, the threshold value storage unit 17 is a coefficient for weighting the outputs of the first sensor (heat flow sensor 10) and the second sensor (sensor other than the heat flow sensor) in response to the rotation speed. remember

Specifically, with respect to the heat flow sensor 10 which is the first sensor, the threshold value storage unit 17 has a coefficient kh ₁ ^{corresponding to the rotation speed N<2000 (min −1} ), the rotation speed 2000≤N<4000 ( min ^-1 ) a coefficient corresponding to (kh ₂ ), a coefficient corresponding to a rotational speed of 4000≤N<6000(min ^-1 _{) (kh 3} ), a coefficient corresponding to a rotational speed of 6000≤N<8000(min ^-1 ) (kh ₄ ), a coefficient (kh ₅ ) corresponding to the rotational speed 8000≤N<10000 (min ^-1 ), and a coefficient (kh ₆ ) corresponding to the rotational speed N≥10000 (min ^-1 ) are stored.

In addition, representatively describing the temperature sensor 12 which is one of the second sensors, the threshold storage unit 17 has a coefficient kt ₁ ^{corresponding to the rotation speed N<2000 (min −1} ), the rotation speed 2000≤ N <4000 (min ^-1) coefficient (kt _2), coefficients corresponding to the rotational speed ^{4000≤N <6000 (min -1) (} kt 3), the rotational speed 6000≤N <8000 (min ^-1) corresponding to Memorize the coefficient corresponding to (kt ₄ ), the coefficient (kt ₅ ) corresponding to the rotation speed 8000≤N<10000(min ^-1 ), and the coefficient (kt ₆ ) corresponding to the rotation speed N≥10000(min ^{-1 )} do.

As an example, the calculation formula of the total E of the sensor outputs after weighting calculation when the ^{rotational speed N is less than 2000 min -1 is shown in Equation (11).}

E=H*kh ₁ +ΔH/Δt*kht ₁ +L*kl ₁ +ΔL/Δt*klt ₁ +T*kt ₁ +ΔT/Δt*ktt ₁ +V*kv ₁ +Vf*kvf ₁ … (11)

Preferably, as shown in FIG. 6 , the abnormality diagnosis processing apparatus 15 multiplies the output of the first sensor and the output of the second sensor by the coefficients respectively corresponding to the sum E of a preset threshold ( If Et _L , Et _H ) is exceeded, an abnormality diagnosis result according to the size of the total amount (E) is output. For example, when the size of the total E _{does not exceed the threshold value Et L} , Normal is output as an abnormal diagnosis result, and when Et _L ≤ E < Et _H , as an abnormal diagnosis result A caution may be output, and when E≥Et _H , a warning may be output as an abnormality diagnosis result.

As described above, in the bearing device shown in the first embodiment, by providing the spacer with a sensor unit including a heat flow sensor provided near the bearing, it is possible to detect a sign of abnormal heat generation in the bearing at an early stage. In addition, by using the heat flow sensor signal and other sensor signals mounted on the sensor unit for diagnosis, the accuracy of the abnormal diagnosis result can be improved and the type of abnormal state of the bearing can be estimated.

[Embodiment 2]

In the second embodiment, an example of improvement of the abnormality diagnosis processing apparatus described in the first embodiment will be described. The configuration of the spindle device 1 and the bearing device 2 shown in Fig. 1 is also common to the second embodiment.

Fig. 8 is a block diagram of the abnormality diagnosis processing apparatus according to the second embodiment. The abnormality diagnosis processing apparatus 15A shown in FIG. 8 is further provided with the power changeover switch 18 in addition to the diagnostic processing part 16A and the threshold value memory|storage part 17A.

The diagnosis processing unit 16A normally performs abnormality diagnosis based on the rotation speed N indicated by the sensor signal SS1 of the heat flow sensor 10 and the sensor signal of the rotation sensor 14 . At this time, when it is diagnosed as "abnormal", the diagnostic processing unit 16A operates the power changeover switch 18 according to the power ON command PON, and the vibration sensor 11, the temperature sensor 12, and the load sensor ( 13) is supplied with the power supply (PWR). And the diagnosis processing part 16A acquires the sensor signal SS2 of the vibration sensor 11, the temperature sensor 12, and the load sensor 13, and performs more accurate abnormality diagnosis.

By providing the power supply changeover switch 18 in the abnormality diagnosis processing apparatus 15A, power saving of the vibration sensor 11, the temperature sensor 12, and the load sensor 13 can be aimed at.

9 is a flowchart for explaining the processing executed by the diagnosis processing unit 16A in the abnormality diagnosis processing apparatus 15A.

First, in steps S11 and S12 , the diagnostic processing unit 16A acquires a sensor signal from the heat flow sensor 10 and acquires a sensor signal from the rotation sensor 14 . At this time, the diagnostic processing unit 16A sets the power changeover switch 18 to the OFF state.

In step S13, the diagnostic processing unit 16A compares the sensor signal of the thermal flow sensor 10 with a threshold value corresponding to the thermal flow sensor 10 stored in the threshold value storage unit 17, and the main shaft 4 rotates. It is determined whether the sensor signal of the rotation sensor 14 indicates what is being done.

In step S14, when the sensor signal of the heat flow sensor 10 does not exceed the corresponding threshold (NO in S14), the diagnostic processing unit 16A determines that there is no abnormality, and in step S15 the determination result of "OK" (JR) is output, and the process returns to steps S11 and S12 again.

On the other hand, in step S14, when the sensor signal of the heat flow sensor 10 exceeds the corresponding threshold (YES in S14), the diagnostic processing unit 16A temporarily determines that there is an abnormality, and in step S16, the power changeover switch 18 is turned on. Control in ON state.

Then, the power supply voltage is supplied to the vibration sensor 11, the temperature sensor 12, and the load sensor 13, and it becomes possible to obtain a sensor signal from these sensors. In steps S17 to S19 , the diagnostic processing unit 16A acquires a sensor signal from at least one of the vibration sensor 11 , the temperature sensor 12 , and the load sensor 13 .

The threshold value of each sensor output corresponding to the rotation speed is stored in advance in the threshold value storage unit 17A. In step S20, the diagnosis processing unit 16A compares the threshold values stored in the threshold value storage unit 17A with each sensor signal, and executes an abnormality diagnosis processing.

In step S21, when all of the sensor signals do not exceed the corresponding threshold (NO in S21), the diagnostic processing unit 16A determines that there is no abnormality, and outputs a judgment result JR of "OK" in step S23, , After that, the power changeover switch 18 is controlled to be OFF in step S24, and the process returns to steps S11 and S12. On the other hand, when there is a sensor outputting a sensor signal exceeding the threshold value in other sensors other than the heat flow sensor 10 in step S21 (YES in S21), the diagnostic processing unit 16A determines that there is an abnormality. At this time, the diagnosis processing unit 16A outputs a determination result JR of "NG" in step S22, and outputs an estimation result of an abnormal state corresponding to the sensor whose sensor signal exceeds the threshold, and in steps S11 and S12 revert processing.

That is, as shown in the block diagram of FIG. 8 and the flowchart of FIG. 9 , the diagnostic processing unit 16 outputs the first sensor (heat flow sensor 10) of the first sensor that the threshold value storage unit 17 stores. If the threshold value corresponding to is not exceeded (NO in S14), abnormal diagnosis based on the output of the second sensor (at least one of the vibration sensor 11, the temperature sensor 12, and the load sensor 13) is performed. Without execution, when the output of the first sensor exceeds the threshold value corresponding to the first sensor (YES in S14), an abnormality diagnosis (S20) is executed based on the output of the second sensor.

Regarding the abnormal diagnosis processing, the abnormal diagnosis processing example 1 and the abnormal diagnosis processing example 2 described in the first embodiment can also be applied to the second embodiment.

In the bearing device shown in Embodiment 2, while being able to acquire the same effect as the bearing device shown in Embodiment 1, by providing the power supply changeover switch 18 in 15A of abnormal diagnosis processing apparatuses further, a vibration sensor ( 11), power saving of the temperature sensor 12 and the load sensor 13 can be achieved.

[Embodiment 3]

In Embodiments 1 and 2, the thermal flow sensor and other sensors were combined. However, it is also possible to improve the accuracy of abnormality determination by combining the thermal flow sensors.

10 is a cross-sectional view showing a schematic configuration of a spindle device according to a third embodiment. Fig. 11 is an enlarged view of a main part on the left side of Fig. 10; 11 mainly shows the bearing arrangement 130 .

The spindle device 101 shown in Fig. 10 is used, for example, as a spindle device of a built-in motor system of a machine tool. In this case, the motor 140 is assembled to one end side of the spindle 104 supported by the spindle device 101 for the machine tool spindle, and a cutting tool such as an end mill (not shown) is connected to the other end side.

The spindle device 101 includes bearings 105a and 105b, a spacer 106 disposed adjacent to the bearings 105a and 105b, heat flow sensors 111a and 111b, a motor 140, and a rear side of the motor. and a bearing 116 that becomes The main shaft 104 is rotatably supported by a plurality of bearings 105a and 105b provided in the housing 103 embedded in the inner diameter portion of the outer cylinder 102 . The bearing 105a includes an inner ring 105ia, an outer ring 105ga, a rolling element Ta, and a retainer Rta. The bearing 105b includes an inner ring 105ib, an outer ring 105gb, a rolling element Tb, and a retainer Rtb. The spacer 106 includes an inner ring spacer 106i and an outer ring spacer 106g.

The heat flow sensors 111a and 111b for measuring the heat flux are fixed to the inner diameter surface 106gA of the outer ring spacer 106g, and oppose the outer diameter surface 106iA of the inner ring spacer 106i.

The main shaft 104 is fitted with an inner ring 105ia of the bearing 105a spaced apart in the axial direction and an inner ring 105ib of the bearing 105b in an interference fit state (press-fitting state). An inner ring spacer 106i is disposed between the inner rings 105ia-105ib, and an outer ring spacer 106g is disposed between the outer rings 105ga-105gb.

The bearing 105a is a rolling bearing in which a plurality of rolling elements Ta are disposed between the inner ring 105ia and the outer ring 105ga. The spacing between these rolling elements Ta is maintained by the retainer Rta. The bearing 105b is a rolling bearing in which a plurality of rolling elements Tb are disposed between the inner ring 105ib and the outer ring 105gb. The distance between these rolling elements Tb is maintained by the retainer Rtb.

The bearings 105a and 105b are bearings capable of applying a preload with an axial force, and an angular ball bearing, a deep groove ball bearing, or a tapered roller bearing may be used. An angular ball bearing is used for the bearing device 130 shown in FIG. 11, and two bearings 105a, 105b are provided in the back surface combination (DB combination).

Although the structure in which the main shaft 104 is supported by two bearings 105a, 105b is illustrated and demonstrated here, the structure which supports the main shaft 104 by two or more bearings may be sufficient.

The single row rolling bearing 116 is a cylindrical roller bearing. The load in the radial direction and the load in the axial direction acting on the spindle device 101 are supported by the bearings 105a and 105b which are angular ball bearings. The load in the radial direction acting on the spindle device 101 for the machine tool spindle is supported by the single row bearing 116 which is a cylindrical roller bearing.

A cooling medium flow path G is formed in the housing 103 . By flowing a cooling medium between the housing 103 and the outer cylinder 102 , the bearings 105a and 105b can be cooled.

In addition, a lubricating oil supply path is provided for cooling and lubricating the bearings 105a and 105b. Lubricating oil is sprayed in the state of air oil or oil mist together with the air which conveys lubricating oil from a discharge hole (nozzle). In addition, a lubricating oil supply path is not shown here. In addition, when a grease-lubricated bearing is used as the bearings 105a and 105b, the lubricating oil supply path is unnecessary.

At the time of assembly, the bearing 105a, the spacer 106, the bearing 105b, and the spacer 109 are sequentially inserted with respect to the main shaft 104 at first, and an initial preload is given by tightening the nut 110. After that, until the right side of the outer ring 105gb of the bearing 105b in FIG. 10 comes into contact with the stepped portion 103a provided in the housing 103, the main shaft 104 to which the bearings 105a and 105b are attached is connected to the housing ( 103) is inserted. Thereafter, the main shaft 104 is fixed to the housing 103 by pressing the outer ring 105ga of the bearing 105a on the left by the front cover 112 .

A force is applied to the end face of the inner ring 105ib of the bearing 105b through the spacer 109 by firmly tightening the nut 110, and the inner ring 105ib is pressed toward the inner ring spacer 106i. This force is transmitted to the inner ring 105ib, the rolling element Tb, and the outer ring 105gb to apply a preload to the bearing 105b, and is also transmitted from the outer ring 105gb to the outer ring spacer 106g. A pressing force is applied from the right outer ring 105gb to the outer ring spacer 106gb, and this force is transmitted from the bearing 105a to the outer ring 105ga, the rolling element Ta, and the inner ring 105ia, and the left bearing ( 105a) is also preloaded. The preload applied to the bearings 105a and 105b is determined by, for example, the amount of movement limited by the dimensional difference between the widths of the outer ring spacer 106g and the inner ring spacer 106i.

Moreover, regarding the single-row bearing 116, the inner ring 116a is positioned in the axial direction by the cylindrical member 115 which fitted the outer periphery of the main shaft 104, and the inner ring presser 119. As shown in FIG. The inner ring presser 119 is prevented from coming off by a nut 120 screwed to the main shaft 104 . The outer ring 116b of the bearing 116 is fitted to the positioning member 121 fixed to the cylindrical member 115 and the positioning member 118 fixed to the inner ring presser 119, In response to expansion and contraction, it slides with respect to the end member 117 integrally with the inner ring 116a.

At an intermediate position in the axial direction sandwiched between the double-row bearings 105a and 105b and the single-row bearing 116 in the space 122 formed between the main shaft 104 and the outer cylinder 102, the main shaft ( A motor 140 driving 104 is arranged. The rotor 114 of the motor 140 is fixed to a cylindrical member 115 fitted to the outer circumference of the main shaft 104 , and the stator 113 of the motor 140 is fixed to the inner circumference of the outer cylinder 102 . .

In addition, the cooling medium flow path for cooling the motor 140 is not shown here.

Heat flow sensors 111a and 111b for measuring heat flux are mounted on the spindle device 101 as the sensor unit 111 . In the examples shown in Figs. 10 and 11, one surface of each of the heat flow sensors 111a and 111b is fixed to the inner diameter surface 106gA of the outer ring spacer 106g, and the other surface is the outer diameter of the inner ring spacer 106i. It faces the face 106iA. Here, the heat flow sensor 111a is arrange|positioned in the vicinity of the bearing 105a, and the heat flow sensor 111b is arrange|positioned in the vicinity of the bearing 105b.

As the surface pressure of the rolling elements Ta and Tb of the bearings 105a and 105b increases, and the raceway surfaces of the inner rings 105ia and 105ib and the outer rings 105ga and 105gb, the inner rings 105ia and 105ib and the outer rings 105ga and 105gb the temperature rises At this time, heat generated between the raceways of the rolling elements Ta and Tb and the inner rings 105ia and 105ib and the outer rings 105ga and 105gb is initially generated by the inner ring spacer 106i, the outer ring spacer 106g, the main shaft 104, It is transmitted to the housing (103). The temperature of the housing 103 having a large heat capacity and the outer ring spacer 106g is delayed until it rises. Since the housing 103 is cooled, there is a further delay in the rise in temperature.

In order to detect a sign of seizure of the bearings 105a and 105b, when trying to measure and detect the temperatures of the inner rings 105ia and 105ib, the outer rings 105ga and 105gb, and the spacer 106, there is a delay in the temperature rise. , it is also assumed that signs cannot be detected early. In such a case, if the heat flow sensors 111a and 111b are used, since the heat flow changes quickly, it is possible to quickly detect rapid heat generation.

The control device 150 for controlling the motor 140 includes an abnormality determination unit 125 and a motor control unit 123 . The heat flow sensors 111a and 111b respectively output the output signals HSa and HSb to the abnormality determination unit 125 .

It is a waveform diagram which shows the example of the output of the heat flow sensor at the time of a bearing normal. It is a waveform diagram which shows the example of the output of the heat flow sensor at the time of a bearing abnormality. In FIGS. 12 and 13 , the waveform of the output signal HSa of the heat flow sensor 111a is indicated by a solid line, and the waveform of the output signal HSb of the heat flow sensor 111b is indicated by a dashed-dotted line.

In the normal case, as the rotational speed of the main shaft 104 of the spindle device 101 increases, the temperature of the two bearings 105a and 105b rises substantially equally. Therefore, as shown in FIG. 12 , the output signals HSa and HSb of the heat flow sensors 111a and 111b both show the same upward tendency during the rotational speed increase, and the rotational speed of the main shaft 104 becomes constant and time When this elapses, the output signals HSa and HSb become stable.

In a method of judging an abnormality when the rate of change (time differential) of the output signals HSa, HSb or the output signals HSa, HSb exceeds a preset threshold, it is difficult to set the threshold, and in some cases, the accuracy of erroneous judgment It is assumed

Therefore, in the present embodiment, the absolute value of the difference between the output signals HSa and HSb of the two heat flow sensors 111a and 111b or the absolute value of the difference in the signal change rates of the output signals HSa and HSb is a preset threshold value. By determining that it is abnormal when the width is exceeded, the determination accuracy is improved. In addition, judging by the absolute value of the difference between two signals is because the value of the difference is positive or negative depending on which bearing the abnormality has occurred. You may determine by the square of a difference, etc. instead of an absolute value.

In Fig. 13, at time T1, a sign of a temperature rise is seen in one bearing 105a, and the other bearing 105b is monitored for an output signal HSa of the heat flow sensor 111a to rise rapidly. The output signal HSb of the heat flow sensor 111b is normal, and an increase in the output is not observed.

Since it is rare that the two bearings 105a and 105b burn out at the same time in an abnormal situation, and one bearing is often burned out, the output signals HSa, HSb show a tendency as shown in FIG. 13 in an abnormal state. . In this case, as the bearing 105a burns out, the output signal HSa rises first, and the output signal HSb starts to rise with a slight delay as shown at time T2 by the transmission of the heat. Moreover, when one bearing 105a burns out, the other bearing 105b may also burn out after that.

Referring back to FIGS. 10 and 11 , the bearing device 130 includes a bearing portion 105 including at least a first bearing 105a and a second bearing 105b supporting the main shaft 104 , and the first bearing A first heat flow sensor 111a and a second heat flow sensor 111b provided corresponding to the 105a and the second bearing 105b, respectively, and an abnormality determination unit 125 for diagnosing an abnormality of the bearing unit 105 are provided. do. The abnormality determination unit 125 determines the difference between the outputs of the first heat flow sensor 111a and the second heat flow sensor 111b (|HSa-HSb|) or the difference between the output change rates (|ΔHSa/Δt-ΔHSb/Δt| ), the presence or absence of an abnormality in the bearing portion 105 is detected.

Preferably, the first bearing 105a and the second bearing 105b support the first part (Pa in FIG. 11 ) and the second part (Pb in FIG. 11 ) spaced apart from each other of the main shaft 104 , respectively.

More preferably, the bearing device 130 is disposed between the first bearing 105a and the second bearing 105b, and the spacer 106 on which the first heat flow sensor 111a and the second heat flow sensor 111b are mounted. ) is also provided. The position where the first heat flow sensor 111a is disposed on the spacer 106 is closer to the first bearing 105a than the position where the second heat flow sensor 111b is disposed on the spacer 106, and the second heat flow sensor 111b The position at which the false spacer 106 is disposed is closer to the second bearing 105b than the position at which the first heat flow sensor 111a is disposed at the spacer 106 .

14 : is a block diagram of the abnormality determination part 125 which judges the abnormality of a bearing from the output of the two heat flow sensors used in Embodiment 3. FIG. Referring to FIG. 14 , output signals HSa and HSb of the two heat flow sensors 111a and 111b mounted inside the spindle device 101 are input to the abnormality determination unit 125 .

The abnormality determination unit 125 includes a differential (D) and a comparator (C). The differential D receives the output signals (or the rate of change of the output signals) HSa and HSb of the two heat flow sensors 111a and 111b and calculates differential outputs. The comparator C compares the absolute value of the output of the differential D with a predetermined criterion (threshold value) JS. When the absolute value of the differential output is larger than the determination criterion (threshold value) JS, the comparator C determines that the bearing is abnormal.

Moreover, the abnormality determination part 125 may further be provided with the bearing specifying part PJ which discriminate|determines which of the bearings 105a, 105b an abnormality or abnormality sign is seen. The bearing specification unit PJ may output the bearing specification result to the outside. By the sign of the output of the differential D, it is possible to specify which of the bearings 105a and 105b shows abnormality or a sign of abnormality. Only when the determination result by the comparator C shows the determination that there is an abnormality or an abnormality sign, you may make it output the bearing specifying part PJ.

In this way, the abnormality determination unit 125 determines which bearing among the first bearing and the second bearing has an abnormality based on the sign of the difference output by the differential D in the bearing specifying unit PJ of FIG. 14 . judge Specifically, the bearing specifying part PJ judges that an abnormality has occurred in the bearing 105a if HSa-HSb>0 (sign is positive), and if HSa-HSb<0 (sign is negative), the bearing 105b is Assume that an error has occurred.

FIG. 15 is a block diagram showing the configuration of an abnormality determination unit 125A that is an improved example of FIG. 14 . The comparator C of the abnormality determination unit 125A shown in FIG. 15 adds the output of the differential D and the threshold JS to the operation information MI of the spindle device 101 (rotation of the motor 140 ). speed, lubrication conditions, cooling conditions, other sensor information, etc.). The comparator C may further consider these information to determine the presence or absence of an abnormality.

When the abnormality determination unit 125 or 125A predicts that any one of the bearings 105a and 105b will stick, the motor control unit 123 of FIG. It is also possible to perform measures such as stopping or increasing the supply amount of lubricating oil.

When the abnormality determination unit 125 determines that there is an abnormality in the output signals HSa and HSb (or the rate of change of the output signals HSa, HSb) of the two heat flow sensors 111a and 111b, a difference of a certain level or more is observed. , it is possible to increase the determination accuracy compared to determining the output signals of the heat flow sensors 111a and 111b one by one. Thereby, erroneous determination is prevented and more accurate abnormality (prediction) detection becomes possible. If the abnormality determination method performed by the abnormality determination unit 125 is applied to the bearing device 130 and the spindle device 101 using the same, it is possible to prevent the bearing device 130 and the spindle device 101 from sticking to the bearing. becomes

As described above, in the third embodiment, two angular ball bearings are used as bearings 105a and 105b, and an outer ring spacer 106g and an inner ring spacer 106i are inserted between the bearings to apply a preload. In the device 130 , heat flow sensors 111a and 111b are respectively disposed in the vicinity of the bearings 105a and 105b. The heat flow sensors 111a and 111b have one surface fixed to the inner diameter surface 106gA of the outer ring spacer 106g, and the other surface to the inner ring 105ia, 105ib or the outer diameter surface 106iA of the inner ring spacer 106i. placed to face each other.

When the spindle device 101 is in normal operation, as the rotation speed of the main shaft 104 of the spindle device 101 increases, the amount of heat generated from the bearings 105a and 105b increases, and the temperature of the spacer 106 also increases. For this reason, the value of the output signal of the heat flow sensors 111a and 111b also rises.

In a general determination method, it is determined as abnormal when the output signals HSa and HSb of the heat flow sensors 111a and 111b or the rate of change (time differential) of the output signals HSa, HSb exceeds a preset threshold. In this method, it is difficult to set an appropriate threshold value due to the influence of the operating state of the spindle device or the secular variation of the preload, and in some cases, an erroneous judgment is assumed. For this reason, in this embodiment, when the difference of the output signal of the heat flow sensor arrange|positioned near each bearing or the difference of the change speed of the output signal of two heat flow sensors exceeds the preset determination reference range, it determines with abnormal.

Since it is rare for two bearings to burn out at the same time in an abnormal situation, the amount of heat generated from either bearing increases and eventually burns out. In the third embodiment, when a difference is observed in the output signals of the heat flow sensors 111a and 111b, abnormal judge that Thereby, erroneous determination is prevented and more accurate predictive determination is attained. If such a determination method is applied, it becomes possible to prevent the bearing from sticking of a bearing apparatus and a spindle apparatus.

[Embodiment 4]

In Embodiment 3, the structure in which the main shaft 104 is supported by the two bearings 105a, 105b as the bearing apparatus 130 has been demonstrated. However, it is not limited to such a configuration, and the abnormality determination method of the present invention can be applied similarly to a structure in which the main shaft 104 is supported by two or more bearings.

16 : is a figure which shows the structure of the bearing apparatus 130A of Embodiment 4 which supports a main shaft with four bearings. The spindle apparatus of Embodiment 4 is provided with the bearing apparatus 130A shown in FIG. 16 instead of the bearing apparatus 130 in the structure of the spindle apparatus 101 of FIG.

In the bearing device 130A shown in FIG. 16 , spacers 131c and 131d and bearings 105c and 105d are added to both outer sides of the bearings 105a and 105b of the bearing device 130 shown in FIG. 11 , respectively. A heat flow sensor 111c is disposed on the inner diameter surface 131gAc of the outer ring spacer 131gc of the added spacer 131c, and a heat flow sensor (131gAd) on the inner diameter surface 131gAd of the outer ring spacer 131gd of the added spacer 131d. 111d) is placed. Since the other structures are the same as those of FIG. 11, the description is omitted. In addition, although the heat flow sensor is arrange|positioned for all bearings in FIG. 16, the heat flow sensor may be arrange|positioned by selecting the bearing which an abnormality tends to generate|occur|produce from a plurality of bearings by design or experience.

17 : is a block diagram of the abnormality determination part 125B which judges the abnormality of a bearing from the output of the two heat flow sensors used in Embodiment 4. FIG.

The abnormality determining unit 125B shown in Fig. 17 further includes a differential D2, a comparator C2, and an OR circuit OR, in addition to the configuration of the abnormality determining unit 125 shown in Fig. 14 . The differential D2 receives the output signals (or the rate of change of the output signals) HSc and HSd of the added heat flow sensors 111c and 111d and calculates these differential outputs. The comparator C2 compares a preset determination criterion (threshold value) JS with the absolute value of the differential output calculated by the differential D2.

The OR circuit OR calculates the OR of the output signal of the comparator C and the output signal of the comparator C2. When an abnormality or abnormality prediction is detected in either the comparator C or the comparator C2, the OR circuit OR determines that there is an abnormality or an abnormality sign, and outputs the judgment result to the outside.

The bearing specifying unit PJ determines which of the bearings 105a, 105b, 105c, and 105d shows an abnormality or a symptom of abnormality. The bearing specifying part PJ is the sign of the output signal of the differential D of the two heat flow sensors 111a and 111b, the sign of the output signal of the differential D2 of the two heat flow sensors 111c and 111d, and , from the output signals of the two comparators C and C2, it is possible to specify the bearing in which the abnormality occurred.

When there are four bearings, the output comparison of the heat flow sensors 111a and 111b that monitors the two central bearings 105a and 105b and the heat flow sensors 111c and 111d that monitors the two outer bearings 105c and 105d ), an abnormality or an abnormality sign was determined by comparison of the outputs, but the combination of the heat flow sensors 111a to 111d to be compared is not limited thereto. Preferably, when the outputs of the heat flow sensors that monitor the bearings separated from each other are compared, the mutual influence is small, so that the measurement accuracy is improved.

Even when the number of bearings to be monitored is an odd number, two can be selected from among the heat flow sensors for monitoring them, and an abnormality or abnormality can be determined from the comparison result.

In the above, a method for directly comparing the outputs of two heat flow sensors was shown. However, in the case where there are a plurality of heat flow sensors to be used, the average value of the output of each heat flow sensor may be calculated and then the respective output of each heat flow sensor may be compared with the average value, and the maximum output and minimum output from the outputs of a plurality of heat flow sensors may be used. You may specify the signals of the output and compare them. In this way, it is possible to prevent erroneous judgment when the outputs of a plurality of heat flow sensors start to catch abnormal signs at once.

In the above description, heat flow sensors are disposed on the inner diameter surfaces 106gA, 131gAc, and 131gAd of the non-rotating outer ring spacers 106g, 131gc, and 131gd. However, the structure in which a heat flow sensor is arrange|positioned on the non-rotating side railing ring (outer ring) of bearing 105a-105d, and the heat flow sensor is made to oppose a rotary ring (inner ring) may be sufficient.

In the above description, the configuration in which the outer ring of the bearing is the fixed side and the inner ring is the rotating side has been described as an example, but also in the case of outer ring rotation and inner ring fixing, the present invention can be applied by attaching a heat flow sensor to the fixed side. .

In the fourth embodiment, heat flow sensors are respectively disposed in the vicinity of three or more bearings serving as heat sources, and output signals of a plurality of heat flow sensors or change rates of output signals are compared with each other, and the difference is a predetermined reference width (threshold value) is exceeded, it is judged as abnormal. For this reason, similarly to Embodiment 3, the predictive determination more accurate than abnormal determination using one heat flow sensor becomes possible. Moreover, with the bearing specifying part PJ, which bearing among three or more bearings is abnormal, or whether the abnormality is shown can be specified.

In addition, although the structure in the case of realization by hardware is shown with respect to the abnormality determination part in FIG. 14, 15, and FIG. 17, it is also possible to implement|achieve by a microcomputer and software.

18 is a diagram showing another configuration of an abnormality determination unit. Referring to FIG. 18 , the abnormality determination units 125 and 125A include an A/D converter 201 receiving the output of the sensor unit 111 and a processor (CPU) processing the conversion result of the A/D converter 201 ( 202 and a memory 203 that stores a program read by the processor 202 and stores data during the arithmetic processing of the processor 202 .

19 is a flowchart for explaining the processing executed by the processor 202 of FIG. 18 .

The abnormality determination method implemented in Embodiment 3 and 4 is the bearing part 105 which includes at least the 1st bearing 105a and the 2nd bearing 105b which support a shaft, the 1st bearing 105a, and the 2nd bearing It is an abnormality determination method of the bearing apparatus 130 including the 1st heat flow sensor 111a and the 2nd heat flow sensor 111b provided corresponding to (105b) respectively. The abnormality determination method executed by the processor 202 is based on the step S51 of calculating the difference between the outputs of the first heat flow sensor 111a and the second heat flow sensor 111b or the difference between the output change rates, and the calculated difference. Steps S52 to S54 for detecting the presence or absence of abnormal occurrence in the bearing part 5 are provided.

More specifically, in step S51, the processor 202 generates a difference (|HSa-HSb|) between the outputs of the first heat flow sensor 111a and the second heat flow sensor 111b or a difference in output change rates (ΔHSa/) Δt-ΔHSb/Δt|) is calculated.

Next, in step S52, the processor 202 determines whether the calculated difference is greater than a threshold value. If the difference is larger than the threshold value (YES in S52), the processor 202 determines that there is a bearing abnormality in step S53. If the difference does not exceed the threshold (NO in S52), the processor 202 determines that there is no bearing abnormality in step S54. When the determination in step S53 or step S54 is determined, the process returns to the main routine in step S55.

In addition, when three or more sensors are used in this way, it is also possible to determine the sensor failure in the same way by noting that it is rare that two sensors fail at the same time.

20 is a flowchart for explaining a process for judging a sensor failure. In this flowchart, the case where the A/D converter shown in FIG. 18 converts the outputs of N sensors (N is a natural number equal to or greater than 3) into digital values and sends them to the CPU 202 will be described. By this process, for example, when the output of a normal sensor gradually increases with an increase in rotational speed as in the initial stage of FIGS. 12 and 13, the case where the malfunctioning sensor shows a fixed value can be detected.

Referring to Fig. 20, in step S61, the CPU 202 acquires data D1 (1) to D1 (N) from the sensors 1 to N, respectively. Next, a waiting time is performed in step S62 until the predetermined time ?t has elapsed. When the predetermined time ?t has elapsed, the CPU 202 acquires data D2(1) to D2(N) from the sensors 1 to N, respectively, in step S63. Then, in step S64, the CPU 202 calculates the differences ΔD(1) to ΔD(N) before and after the lapse of the predetermined time Δt for each of the sensors 1 to N. Then, by the following processing, it is checked whether there is a sensor whose change amount of only one of the differences ?D(1) to ?D(N) is significantly smaller than that of the other sensors.

The CPU 202 determines that, before and after the elapse of the predetermined time Δt, the amount of change in the output of the N heat flow sensors excluding the Mth heat flow sensor is larger than the first threshold, and the output of the Mth heat flow sensor is larger than the first threshold. When the amount of change is smaller than the second threshold equal to or less than the first threshold, it is determined that a failure has occurred in the M-th heat flow sensor. This determination process is described in detail below.

First, the variable M is initialized to 1 in step S65. Next, in step S66, the average value AVE(M) is calculated for the group excluding ΔD(M) from the differences ΔD(1) to ΔD(N). By comparing ?D(M) and AVE(M), it can be judged whether or not the change in the sensor M is remarkably small compared to other sensors. Specifically, in step S67, in the CPU 202, the magnitude of the average value (|AVE(M)|) exceeds the first threshold, and the magnitude of the change amount of the sensor M |ΔD(M)|) is It is determined whether or not it is smaller than a second threshold value less than or equal to a first threshold value. When the condition of step S67 is satisfied, it is considered that there is little change in the sensor M compared with other sensors. In this case, since it is estimated that a failure such as disconnection or short circuit has occurred in the sensor M, the CPU 202 determines in step S68 that the sensor M has failed, and the processing advances to step S69. At this time, the CPU 202 may turn on a warning lamp notifying the occurrence of a failure, or output a warning sound, a notification signal, or the like as necessary. When the condition of step S67 is not satisfied, the CPU 202 advances the processing to step S69 without executing the processing of step S68. Incidentally, in the above processing, the average value of the outputs of sensors other than the sensor M was calculated in order to detect that the sensor M has little change compared with the other sensors, but the output of the sensors other than the sensor M is another method. It is also possible to evaluate the behavior of For example, the maximum value, minimum value, variance, etc. may be used for evaluation.

When the variable M has not reached N in step S69, the variable M is incremented in step S70, and the processing after step S66 is executed again. On the other hand, in step S69, if the variable M has reached N, the process ends in step S71, and control is transferred to the main routine.

As described above, by providing a plurality of sensors and referencing them to each other, it is also possible to determine the failure of the sensors. Because of this, it becomes possible to distinguish between a bearing failure and a sensor failure.

It should be considered that embodiment disclosed this time is an illustration and not restrictive in all points. The scope of the present invention is indicated by the claims rather than the description of the embodiments, and it is intended that all changes within the meaning and scope equivalent to the claims are included.

1, 101: spindle device
2: Bearing device
3, 103: housing
4, 104: spindle
5a, 5b, 105a, 105b, 105c, 105d, 116: bearing
5ga, 5gb, 105g, 105ga, 105gb, 116b: outer ring
5ia, 5ib, 105i, 105ia, 105ib, 116a: inner ring
6, 106, 109, 131c, 131d: spacer
6g, 106g, 106gb, 131gc, 131gd: outer ring spacer
6i, 106i: inner ring spacer
7: Outer box
9: Sensor unit
10, 111, 111a, 111b, 111c, 111d: heat flow sensor
11: Vibration sensor
12: temperature sensor
13: load sensor
14: rotation sensor
15, 15A: anomaly diagnostic processing unit
16, 16A: diagnostic processing unit
17, 17A: threshold storage unit
18: power changeover switch
102: outer barrel
103a: step part
105: bearing part
106gA, 131gAc, 131gAd: inner surface
106iA: outer diameter
110, 120: nut
112: front cover
113: stator
114: rotor
115: cylindrical member
117: end material
118, 121: positioning member
119: inner ring pressed
122: space part
123: motor control unit
125, 125A, 125B: abnormality determination unit
130, 130A: bearing device
140: motor
150: control device
201: A/D converter
202: processor
203: memory
C, C2: comparator
D, D2: Differential
OR: OR circuit
PJ: Bearing specific part
Rta, Rtb: maintainer
Ta, Tb: rolling element

Claims (13)

A first bearing including an inner ring, an outer ring and a rolling element;
a spacer disposed adjacent to the first bearing on a shaft supported by the first bearing and including an inner ring spacer and an outer ring spacer;
a first sensor disposed on the first bearing or the spacer;
and a second sensor,
The first sensor is a heat flow sensor,
The second sensor includes at least one of a heat flow sensor, a vibration sensor, a temperature sensor, and a load sensor,
An abnormality diagnosis device for determining abnormality based on the output of the first sensor and the output of the second sensor is further provided. According to claim 1,
The second sensor includes at least one of a vibration sensor, a temperature sensor, and a load sensor,
and the abnormality diagnosis apparatus diagnoses an abnormality of the bearing based on the outputs of the first and second sensors and the rotational speed of the shaft. 3. The method of claim 2,
The abnormal diagnosis device,
threshold memory,
and a diagnostic processing unit that performs diagnostic processing based on a threshold value that the threshold value storage unit stores signals from a sensor unit including the first sensor and the second sensor. 4. The method of claim 3,
The said threshold value storage part memorize|stores the threshold value corresponding to each of a plurality of rotational speeds with respect to each of the said 1st sensor and the said 2nd sensor, The bearing apparatus characterized by the above-mentioned. 5. The method of claim 3 or 4,
The diagnosis processing unit does not execute abnormality diagnosis based on the output of the second sensor when the output of the first sensor does not exceed a threshold value corresponding to the first sensor memorized by the threshold value storage unit, When the output of the first sensor exceeds a threshold corresponding to the first sensor, an abnormality diagnosis is executed based on the output of the second sensor. 6. The method according to any one of claims 3 to 5,
and the threshold value storage unit stores a coefficient for weighting the outputs of the first sensor and the second sensor in response to the rotation speed. 3. The method of claim 2,
The abnormality diagnosis apparatus is configured to generate an abnormality diagnosis result according to the size of the total when the sum of the numbers obtained by multiplying the coefficients corresponding to the output of the first sensor and the output of the second sensor exceeds a preset threshold. Bearing device, characterized in that the output. According to claim 1,
a second bearing supporting the shaft together with the first bearing;
The first sensor is a first heat flow sensor provided to correspond to the first bearing,
The second sensor is a second heat flow sensor provided to correspond to the second bearing,
The abnormality diagnosis apparatus is configured to generate an abnormality in a bearing unit including the first bearing and the second bearing based on a difference in output between the first heat flow sensor and the second heat flow sensor or a difference in output change rate. A bearing device comprising an abnormality determination unit for detecting the presence or absence of . 9. The method of claim 8,
The first bearing and the second bearing support a first portion and a second portion spaced apart from each other of the shaft, respectively. 10. The method of claim 9,
the spacer is disposed between the first bearing and the second bearing, the first heat flow sensor and the second heat flow sensor are disposed in the spacer;
A position where the first heat flow sensor is disposed on the spacer is closer to the first bearing than a position where the second heat flow sensor is disposed on the spacer,
The bearing device according to claim 1, wherein a position where the second heat flow sensor is disposed on the spacer is closer to the second bearing than a position where the first heat flow sensor is disposed on the spacer. 11. The method according to any one of claims 8 to 10,
The said abnormality determination part judges which bearing of the said 1st bearing and the said 2nd bearing an abnormality generate|occur|produced based on the sign of the said difference, The bearing apparatus characterized by the above-mentioned. 12. The method according to any one of claims 8 to 11,
If N is a natural number greater than or equal to 3,
Equipped with N heat flow sensors,
The first heat flow sensor and the second heat flow sensor are two of the N heat flow sensors,
The abnormality determination unit may include, before and after the lapse of a predetermined time, an amount of change in output of a sensor group excluding the first heat flow sensor from the N heat flow sensors is greater than a first threshold, and a change amount of output of the first heat flow sensor When it is smaller than the 2nd threshold value below the said 1st threshold value, it determines with the failure generate|occur|produced in the said 1st heat flow sensor, The bearing apparatus characterized by the above-mentioned. A spindle device comprising the bearing device according to any one of claims 1 to 12.

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