JP6799977B2 - Bearing abnormality diagnosis method in rotary shaft device and rotary shaft device - Google Patents

Description

The present invention relates to a method of diagnosing an abnormality in a bearing in a rotary shaft device in which a rotary shaft is pivotally supported by a bearing, such as a spindle device of a machine tool, and a rotary shaft device capable of carrying out the method.

Bearings are used in many rotary shaft devices such as spindle devices for machine tools. Among them, a rolling bearing is generally composed of an inner ring, an outer ring, a plurality of rolling elements, and a cage for keeping the rolling elements at equal intervals, the inner ring rotates with a rotating shaft, and the outer ring is incorporated in a housing. It is fixed.
Such bearing abnormalities include poor lubrication, foreign matter contamination, wear, and excessive load. If rotation failure or seizure occurs due to these, the rotary shaft device cannot operate normally and until the device is repaired. During that time, the stopped state continues. Therefore, in order to prevent such a situation, preventive maintenance for early diagnosis of bearing abnormality is required. For example, Patent Documents 1 to 3 disclose a method of monitoring measurement information by sensors such as a vibration sensor, a sound sensor, and a temperature sensor to diagnose a bearing abnormality and a life in advance in real time.
Further, in Patent Document 4, the resistance torque generated in the bearing is calculated from the change in the rotation speed when the rotation shaft is inertially rotated by using the rotation speed detector installed as standard in the machine tool, and this resistance torque is calculated. Is disclosed as a method of diagnosing a bearing abnormality by comparing with a reference value.

JP-A-2009-2009 Japanese Unexamined Patent Publication No. 2013-47690 JP-A-2002-346884 Special Fair 6-65189

In order to carry out the methods of Patent Documents 1 to 3, additional hardware costs (vibration, sound) and low detection sensitivity (temperature) become problems.
The method of Patent Document 4 does not cause such a problem, can accurately diagnose bearing abnormalities, and does not incur additional costs, but it is necessary to wait for the natural stop of the rotating shaft from inertial rotation, and it is a high-speed rotation specification. In that case, it takes a lot of time to diagnose the abnormality.

Therefore, the present invention can diagnose the presence or absence of an abnormality at low cost and with high accuracy even if the abnormality of the bearing is diagnosed by using the coastal rotation, and the diagnosis time can be shortened. It is an object of the present invention to provide a method for diagnosing an abnormality of a bearing in an apparatus and a rotary shaft apparatus.

In order to achieve the above object, the invention according to claim 1 is obtained by coasting the rotating shaft from a predetermined rotation speed in a rotating shaft device in which the rotating shaft is pivotally supported by a bearing, and obtaining the rotating shaft at the time of the coasting rotation. It is a method of diagnosing an abnormality of the bearing based on the information obtained.
After the start of the coastal rotation, when the rotation speed of the rotation shaft drops to a preset target speed before the rotation is stopped, the first coastal rotation step for ending the coastal rotation and the rotation speed are set to the target speed. a reduction step of decelerating to a lower initial rate than, after combined, the second coasting steps performed again the inertial rotation from the starting speed running at least once, the respectively obtained by each of said inertial rotation step It is characterized in that the presence or absence of abnormality of the bearing is determined based on the information.
The invention according to claim 2 is characterized in that, in the configuration of claim 1, the inertial rotation is started by shutting off the power supply to the rotating shaft during rotation.
The invention according to claim 3 is characterized in that, in the configuration of claim 1 or 2, the decrease to the target speed is confirmed by the information obtained from the sensor during the inertial rotation of the rotating shaft.
The invention according to claim 4 is characterized in that, in the configuration of claim 3, the sensor is a detector of the rotational speed.
In order to achieve the above object, the invention according to claim 5 is a rotary shaft device in which a rotary shaft is pivotally supported by a bearing.
A first inertial rotation means for coasting the rotation axis from a predetermined rotation speed to a preset target speed before the rotation is stopped, and a first coastal rotation means for finishing the coastal rotation at the target speed and exceeding the target speed. Based on the deceleration means for decelerating the rotating shaft to a lower starting speed, the second coasting rotating means for coasting the rotating shaft again from the starting speed, and the information obtained at the time of executing each of the coasting rotating means. It is characterized by comprising a determination means for determining the presence or absence of abnormality of the bearing.

According to the present invention, even if an abnormality of a bearing is diagnosed by using inertial rotation, the presence or absence of an abnormality can be diagnosed with low cost and high accuracy because it does not wait until the inertial rotation is stopped, and the diagnosis time is increased. It can also be shortened.

It is a schematic diagram of a spindle device. It is a flowchart of abnormality diagnosis control. It is explanatory drawing which shows the change of the rotation speed of abnormality diagnosis control. It is a graph which shows the relationship between a rotation speed and a resistance torque. Is a rolling element.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing a spindle device of a machine tool, which is an example of a rotary shaft device.
The spindle device 1 comprises a spindle 4 as a rotating shaft that is rotationally driven by a motor 3 including a stator and a rotor in a housing 2, and is pivotally supported by bearings 5, 5 and ... That are rolling bearings. The tool can be attached to and detached from the tip of the bearing. Ball bearings, roller bearings, and tapered roller bearings are used as rolling bearings, but sliding bearings may also be used.

A draw bar (not shown) for holding a tool is provided in the spindle 4, and the housing 2 has a lubricating oil supply mechanism for supplying lubricating oil to the bearing 5, and the bearing 5 and the stator are cooled by a coolant. A cooling mechanism is provided for this purpose (both are not shown).
However, the power supply to the spindle 4 is not limited to the motor 3, for example, the spindle 4 is driven via a gear, the spindle 4 and the motor are connected and driven by a coupling, or the spindle 4 is driven via a belt. Each method can be adopted, such as driving the rotor or driving the rotor as a magnet.

Further, a temperature sensor 6 for detecting the temperature in the vicinity of the bearing 5 and a rotation speed detector 7 for detecting the rotation speed of the spindle 4 are attached to the housing 2. However, the sensors are not limited to this, and the accelerometer and displacement meter for detecting the vibration of the spindle 4, the air pressure detector when supplying lubrication to the bearing 5, the viscosity measuring instrument for lubricating oil, and the rotation of the spindle 4 It also includes a microphone that measures the sound that sometimes occurs.

Reference numeral 10 denotes a control device, and the control device 10 is provided with a command device 11, a determination device 12, an arithmetic device 13, a storage device 14, and a display device 15.
The command device 11 issues a command to drive the rotor of the spindle 4 at the commanded rotation speed by the command information input to the display device 15 which also functions as a touch panel (input device) or the input program information. On the other hand, in the abnormality diagnosis control of the bearing 5 described later, when an inertial rotation command is input, the spindle 4 can be brought into an inertial rotation (inertial rotation) state by shutting off the power supply. At that time, the lubricating oil supply mechanism and the cooling mechanism should continue to operate.
Further, when the specified target speed is reached during the inertial rotation, the power supply can be restarted to return the control from the inertial rotation state and issue a command to decelerate to the specified rotation speed. That is, it functions as the first and second inertial rotation means and deceleration means of the present invention.

However, the command method is not limited to the above method, and for example, a means for executing an operation with a button attached to the control device 10 or a means for executing the operation by remote control via a communication network or the like can be adopted.
Further, as the target speed for terminating the inertial rotation, information stored in advance as a parameter in the storage device 14 may be acquired in addition to the above command method.
Further, it is possible to change whether or not the lubricating oil supply mechanism and the cooling mechanism are driven during the inertial rotation.
Then, in the inertial rotation state, in addition to shutting off the power supply, the inertial rotation state can be simulated by sending a rotation command corresponding to the change in the rotation speed during the inertial rotation.

The determination device 12 acquires the rotation speed information of the spindle 4 from the rotation speed detector 7. When the command device 11 issues an inertial rotation command to the target speed, the rotation speed information of the spindle 4 can be acquired, and when the target speed is reached, the information can be sent to the command device 11.
The storage device 14 has calculation parameters such as a target speed and a start speed at the time of abnormality diagnosis control, a moment of inertia of the spindle 4 used at the time of calculation in the calculation device 13, and a rotation speed at the time of inertial rotation and its information. The resistance torque information obtained by processing in step 13 is stored.
However, as the items to be stored, for example, information such as the temperature sensor 6, the above-mentioned accelerometer and displacement meter, the air pressure detector, the viscosity measuring instrument, and the microphone can be stored.

At the time of abnormality diagnosis control, the arithmetic device 13 uses the following equation (1), which uses the rotational speed V at the time of inertial rotation, the moment of inertia M, and the acceleration stored in the storage device 14, to resist the inertial rotation. The torque T is calculated, and the presence or absence of an abnormality in the bearing 5 is determined based on the calculated resistance torque. That is, it functions as a determination means of the present invention.
T =-(2πM / 60) x (dV / dt) ... (1)

Using a touch panel, the display device 15 can input values such as a target speed at the time of inertial rotation and a calculation parameter used at the time of calculation in the calculation device 13 to the storage device 14.
Further, the stored information such as the rotation speed at the time of inertial rotation stored in the storage device 14 and the resistance torque information obtained by processing the information by the arithmetic device 13 can be displayed as a graph, and the determination result of the abnormality diagnosis control can be displayed. Can be done.
However, the information to be displayed is not limited to this, and information such as the temperature sensor 6, the accelerometer and displacement meter described above, the air pressure detector, the viscosity measuring instrument, and the microphone stored in the storage device 14 should also be displayed. Can be done.

The abnormality diagnosis control of the bearing 5 executed by the control device 10 in the spindle device 1 configured as described above will be described with reference to the flowchart of FIG.
First, in S1, the spindle 4 is rotated at a predetermined first starting speed (here, 8000 min ^-1 ), and then the power supply of the spindle 4 rotating in S2 is cut off to start the first inertial rotation (in this case, 8000 min ^-1 ). The first resistance torque T1 is calculated by the above equation (1) together with the part A in FIG.
Next, in S3, it is determined whether or not the rotation speed obtained from the rotation speed detector 7 during the inertial rotation has decreased to the first target speed (here, 7000 min ^-1 ). When it is confirmed that the first target speed has been reached here, the power supply is restarted in S4 to end the inertial rotation (up to this point, the first inertial rotation step).

Next, in S5, the rotation speed of the spindle 4 is decelerated to a second start speed (here, 4000 min ^-1 ) lower than the first target speed (deceleration step). After that, in S6, the power supply of the spindle 4 is cut off and the second inertial rotation is started (part B in FIG. 3, the second inertial rotation step), and the second resistance torque T2 is calculated by the above equation (1). Make a calculation.

Next, in S7, it is determined whether or not the rotation speed obtained from the rotation speed detector 7 during the inertial rotation has decreased to the second target speed (2000 min ^{-1 in} this case). When it is confirmed that the second target speed has been reached here, the power supply is restarted in S8 to end the inertial rotation.
Next, in S9, the rotation speed of the spindle 4 is decelerated to a third start speed (here, 1000 min ^-1 ) lower than the second target speed (deceleration step). After that, in S10, the power supply of the spindle 4 is cut off and the third inertial rotation is started (C part in FIG. 3, the second inertial rotation step), and the third resistance torque T3 is calculated by the above equation (1). Make a calculation.
Next, in S11, it is determined whether or not the rotation speed obtained from the rotation speed detector 7 during the inertial rotation has decreased to the third target speed (here, 0 min ^-1 ).

When it is confirmed that the third target speed has been reached, the waveforms of the three resistance torques T1 to T3 obtained during each inertial rotation are analyzed in S12 to determine the presence or absence of an abnormality as shown in FIG. I do. For example, it is determined whether or not the resistance torques T1 to T3 are larger than the preset threshold value at each stage, and if it is larger than the threshold value, an abnormality determination is performed, or the amount of change is a predetermined amount as compared with the previous measurement result. It is conceivable to perform an abnormality determination when the value is larger, or to perform an abnormality determination when the error is large compared to the reference feature amount by calculating the feature amount of each waveform.
The result of the determination in this way is displayed on the display device 15 in S13.

As described above, according to the spindle device 1 of the above-described embodiment, when the rotation speed of the spindle 4 drops to the preset target speed before the rotation is stopped (S3, S7) after the start of the coastal rotation, the coastal rotation is terminated. A first coasting rotation step (S4, S8), a deceleration step (S5, S9) for decelerating the rotation speed to a start speed lower than the target speed, and a second coasting rotation step for performing coasting rotation again from the start speed. After executing (S6, S10) twice, it is determined whether or not there is an abnormality in the bearing 5 based on the resistance torque obtained in each inertial rotation step. Therefore, the inertial rotation of the bearing 5 is used. Even if an abnormality is diagnosed, the presence or absence of the abnormality can be diagnosed at low cost and with high accuracy. In particular, since the diagnosis is not performed between the maximum rotation speed and the stop of the inertial rotation as in the conventional case, the diagnosis time can be shortened.
The dotted line shown in FIG. 3 shows the case where the inertial rotation is continuously performed until the rotation is stopped as in the conventional case, but the third inertial rotation in the present embodiment is completed as compared with the diagnosis time t0 here. It can be seen that the diagnosis time t1 is shorter.

In the above embodiment, the first inertial rotation step and the second inertial rotation step after the deceleration step are repeated twice to perform the abnormality diagnosis, but the abnormality diagnosis may be performed only once, or conversely, 3 It may be repeated more than once. Further, the start speed and the target speed are not limited to the above-mentioned form, and can be changed as appropriate.
Furthermore, the confirmation of reaching the target speed during inertial rotation is not limited to the speed information from the rotation speed detector, but when an accelerometer, displacement meter, microphone, etc. are provided as sensors as described above, these When the frequency obtained from the sensor reaches an arbitrary set frequency, it can be determined that the target speed has been reached.
In addition, the method for diagnosing an abnormality of a rotary shaft device or a bearing of the present invention is applicable not only to the spindle device of a machine tool but also to other mechanical equipment such as an automobile, a railroad vehicle, and a ship.

1 ... Spindle device, 2 ... Housing, 3 ... Motor, 4 ... Spindle, 5 ... Bearing, 6 ... Temperature sensor, 7 ... Rotation speed detector, 10 ... Control device, 11 ... Command Device, 12 ... Judgment device, 13 ... Arithmetic device, 14 ... Storage device, 15 ... Display device.

Claims (5)

In a rotary shaft device in which a rotary shaft is pivotally supported by a bearing, the rotary shaft is coasted from a predetermined rotation speed, and an abnormality of the bearing is diagnosed based on the information obtained during the coastal rotation.
After the start of the inertial rotation, when the rotation speed of the rotation shaft drops to a preset target speed before the rotation stops, the first inertial rotation step for ending the inertial rotation
A deceleration step that reduces the rotation speed to a start speed lower than the target speed, and
A second inertial rotation step in which the inertial rotation is performed again from the start speed,
A method for diagnosing a bearing abnormality in a rotary shaft device, which comprises determining the presence or absence of an abnormality in the bearing based on the information obtained in each of the inertial rotation steps after a total of at least one execution. The method for diagnosing an abnormality in a bearing in a rotating shaft device according to claim 1, wherein the inertial rotation is started by cutting off the power supply to the rotating shaft during rotation. The method for diagnosing an abnormality in a bearing in a rotating shaft device according to claim 1 or 2, wherein the decrease to the target speed is confirmed by information obtained from a sensor during inertial rotation of the rotating shaft. The method for diagnosing an abnormality of a bearing in a rotary shaft device according to claim 3, wherein the sensor is a detector for the rotational speed. A rotary shaft device in which the rotary shaft is supported by bearings.
A first inertial rotation means for inertially rotating the rotation axis from a predetermined rotation speed until the rotation speed drops to a preset target speed before the rotation is stopped.
A deceleration means for terminating the inertial rotation at the target speed and decelerating the rotation shaft to a start speed lower than the target speed.
A second inertial rotation means for inertially rotating the rotation axis from the start speed,
A determination means for determining the presence or absence of an abnormality in the bearing based on the information obtained at the time of execution of each of the inertial rotation means, and
A rotary shaft device characterized by comprising.

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