JP5516839B2 - Spindle device abnormality detection device, spindle device abnormality detection method, spindle device, and machine tool - Google Patents

Description

  The present invention relates to a spindle device abnormality detection device, a spindle device abnormality detection method, a spindle device, and a machine tool.

Conventionally, an abnormality is detected by monitoring a heat generation state of a spindle bearing of a machine tool or the like (see, for example, Patent Document 1).
As shown in FIG. 4, in the spindle device 100 described in Patent Document 1, the spindle 101 is rotatably supported inside a body 102 via a plurality of rolling bearings 103, and includes a built-in type including a stator 104a and a rotor 104b. The main shaft motor 104 is rotationally driven. A temperature sensor 105 that detects the temperature of the rolling bearing 103 is attached to the outer ring 103 a of each rolling bearing 103.

  The spindle device 100 also includes a signal conversion unit 106 that converts the detection signal from the temperature sensor 105 to digitize the bearing temperature, a memory unit 107 that stores the digitized detection signal as time series data, and this time series. A calculation unit 108 that calculates a predicted value of the bearing temperature based on the data and a motor control unit 109 that controls the spindle motor 104 based on the calculation result are provided.

Therefore, when the spindle motor 104 is started by the command of the motor control unit 109 and the spindle 101 rotates, the rolling bearing 103 rises in temperature. The bearing temperature at this time is detected by the temperature sensor 105, digitized by the signal conversion unit 106, and stored as time series data in the memory unit 107. When a preset time has elapsed since the main shaft 101 started rotating, a predicted value of the bearing temperature is calculated by the calculation unit 108 based on the time-series data in the memory unit 107. Then, the predicted value of the bearing temperature is compared with a preset dangerous temperature, and when the predicted value exceeds the dangerous value, the rotational speed of the spindle 101 is reduced. This prevents the bearing from being damaged.
JP-A-7-308846 (FIG. 1)

  Incidentally, in the spindle device 100 described in Patent Document 1, since the bearing temperature is directly measured by the temperature sensor 105, there is a disadvantage that it takes time to determine that the bearing is abnormal from the time of occurrence of the bearing abnormality. That is, the bearing temperature is a secondary result determined by the heat generation of the bearing, the heat transfer state with the structural members and air around the bearing, the spindle cooling structure, etc. However, there is a problem that rapid heat generation due to abnormal preload cannot be detected, and the bearing is damaged. Further, since the temperature follows insensitivity to sudden abnormal fluctuations in heat generation, it was impossible to grasp the lubrication state inside the bearing. In addition, since the amount of heat generated by the bearing is unknown, it was difficult to determine whether or not there was an improper assembly such as a preload adjustment error.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to detect an abnormality such as a lubrication state of a bearing in real time and to prevent damage to the spindle device. An object of the present invention is to provide a spindle apparatus abnormality detection method, a spindle apparatus, and a machine tool.

The above object of the present invention is achieved by the following configurations.
(1) A main spindle device body having a main shaft rotatably supported by a bearing, a motor that rotationally drives the main shaft, a power supply unit that supplies power to the motor, and controls the power of the power supply unit An abnormality detection device for a spindle device that detects an abnormality of the bearing of the spindle device comprising:
In a lubrication method in which lubricating oil is discharged to the bearing at a lubrication timing, a value of input power supplied from the power supply unit when the main shaft rotates at a constant speed with no load is measured, and the input power A power measurement unit capable of holding time-series data of values of
When comparing the time series data measured by the power measuring unit with the time series data obtained in advance at normal time, in the measured time series data, there is a wide protrusion on a part of the lubrication timing. When the tendency of both time-series data is different due to the formation of a large number of projections at a timing other than the lubrication timing, it is determined that the bearing is abnormally heated and the lubrication state of the bearing A detection unit for detecting abnormalities of
An abnormality detection device for a spindle device, comprising:
(2) The abnormality detection device according to (1) is provided,
When the abnormality detection device detects an abnormality in a lubrication state, the control unit controls at least one of the main shaft device main body and a lubrication device that supplies a lubricant to the bearing.
(3) A machine tool comprising the spindle device according to (2).
(4) A main spindle device main body having a main shaft rotatably supported by a bearing, a motor that rotationally drives the main shaft, a power supply unit that supplies power to the motor, and controls the power of the power supply unit An abnormality detection method for a spindle device that detects an abnormality of the bearing of the spindle device comprising:
In a lubrication method in which lubricating oil is discharged to the bearing at a lubrication timing, a step of measuring input power supplied to the motor when the main shaft rotates at a constant speed with no load by a power measuring unit;
Creating the measured value of the input power as time-series data;
The time series data is compared with time series data obtained in advance at normal times. In the measured time series data, a wide protrusion is formed at a part of the lubrication timing, or the lubrication is performed. A step of detecting an abnormality in the lubrication state of the bearing by determining that the bearing has abnormally heated when the tendency of both time series data is different due to the formation of a large number of protrusions at a timing other than the timing ; and
An abnormality detection method for a spindle apparatus, comprising:

  According to the present invention, the input power supplied from the power supply unit to the motor that rotationally drives the main shaft rotatably supported by the bearing in the main spindle device body is measured by the power measurement unit, and the detection unit is measured. Since the bearing heat generation state is judged based on the input power value and the abnormality of the bearing lubrication state is detected, the occurrence of the abnormality such as the bearing lubrication state can be detected in real time, and damage to the bearing can be prevented. .

  Hereinafter, a spindle apparatus abnormality detection device, a spindle apparatus abnormality detection method, a spindle apparatus, and a machine tool according to an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, a spindle apparatus abnormality detection device 10 according to an embodiment of the present invention includes a bearing 32a that rotatably supports a spindle 31 of a spindle apparatus body 21 in, for example, a spindle apparatus 20 used in a machine tool. , 32b is detected.

  The spindle device main body 21 includes a housing 30 attached to a machine tool main body (not shown), a spindle 31 that is disposed in the housing 30 so as to be relatively rotatable with respect to the housing 30 by bearings 32a and 32b, and holds a tool T at a tip thereof A motor 33 that is disposed between the housing 30 and the main shaft 31 and that rotationally drives the main shaft 31;

  An axial hole 31a formed through the axis of the main shaft 31 is attached to the draw bar 34 so as to be movable relative to the main shaft 31 in the axial direction. The draw bar 34 is externally mounted. A spring 35 is disposed between the springs 34 so as to be compressible. The draw bar 34 pulls a tool holder 37 clamped by a collet portion 36 provided at the tip thereof inward in the axial direction by a spring 35, and fixes the tool T to the main shaft 31.

  The motor 33 includes a rotor 33 a that is externally fitted and fixed to the intermediate portion in the axial direction of the main shaft 31, and a stator 33 b that is internally fitted and fixed to the intermediate portion in the axial direction of the housing 30.

  The bearings 32a and 32b are disposed on the tool side (the left end side in the figure) with respect to the rotor 33a of the motor 33, and include a front bearing 32a constituted by two angular ball bearings, and a counter tool side (see FIG. A rear bearing 32b that is disposed on the middle right end side) and is configured by a cylindrical roller bearing. In addition, the front side bearing 32a and the rear side bearing 32b can be used by combining various bearings arbitrarily and in any number.

  Lubricating oil is supplied to the bearings 32 a and 32 b via the lubricating oil supply passages 38 a and 38 b formed in the housing 30 by the lubricating device 11 provided outside the spindle device main body 21. Any lubricating system can be used, and oil lubrication such as oil-air lubrication, oil mist lubrication, and direct injection lubrication, grease-filled lubrication, grease replenishment lubrication, and the like can be applied.

  Furthermore, the spindle device main body 21 is disposed at the end of the spindle 31 on the side opposite to the tool, and when unclamping the tool holder 37, a hydraulic unclamping mechanism 39 that applies an unclamping force to the draw bar 34 by hydraulic pressure, An encoder 40 that is a rotation speed measuring unit that measures the rotation speed of the main shaft 31 around the opposite side of the main shaft 31 is provided.

  The spindle device 20 includes a power supply unit 22 that supplies power to the stator 33a of the motor 33, a control unit 23 that controls the power of the power supply unit 22, and a power measurement unit. Current measuring device 24 and voltage measuring device 25, and a detection unit 26 including a time series data display unit 26a and a power calculation unit 26b. The control unit 23 is provided with an abnormality determination unit 23a that performs abnormality determination based on the signal detected by the detection unit 26 to control the device.

  The power supply unit 22 includes a three-phase AC power source 22b and a main shaft amplifier 22a as a driver. The main shaft amplifier 22 a controls the power from the power source 22 b based on a command signal corresponding to a predetermined rotation speed of the main shaft 31 sent from the control unit 23, and supplies the power to each phase of the motor 33. 27 to supply.

  The current measuring device 24 and the voltage measuring device 25 provided on the power line 27 measure the current and voltage supplied to the motor 33, respectively, and these current and voltage are sent to the detection unit 26. In the detection unit 26, the power calculation unit 26b calculates the value of the input power, and holds this input power value as time series data. The detection unit 26 displays the input power value on the time-series data display unit 26a, determines the heat generation state of the bearings 32a and 32b based on the input power value, and detects an abnormality in the lubrication state of the bearings 32a and 32b. To do.

  In the spindle device 20 configured as described above, when a predetermined number of rotations is commanded by the control unit 23, a control current flows from the power supply unit 22 to each phase of the motor 33, and the motor 33 rotates. Here, the encoder 40 measures the rotation speed of the motor 33, and the control unit 23 inputs necessary power to the motor 33 so that the measured rotation speed is maintained at the commanded rotation speed. . This input power takes into account the friction loss due to the bearings 32a and 32b, the loss of the motor 33, and the windage loss of the rotating member. The input power increases for reasons other than these reasons when the load torque increases, that is, when a cutting load is applied, or when the rotation of the spindle 31 is accelerated.

  Therefore, in a state where the main shaft 31 is rotating at a constant no-load speed, the loss and windage loss of the motor 33 do not change greatly, so the input power value does not change due to these losses. If the input power value changes in this state, it means that the loss of the bearing 32, that is, the heat generation state has changed. In particular, in the case of oil lubricated bearings, heat generation increases immediately after the lubricant enters the raceway surface, but when the lubricating oil is discharged and the oil film thickness is properly maintained, the heat generation instantaneously converges. And stable. In this state, it can be determined that the lubrication state is normal.

  On the other hand, when the lubricating oil is poorly discharged and the lubricating oil returns to the raceway surface, the heat generation increases, the input power value detected by the detection unit 26 increases, and the temperature rise does not converge. The state in which the input power value continues to rise is detected.

  2 and 3 are tables of the time-series data display unit 26a that holds input values as time-series data when the bearing is lubricated by direct injection lubrication (super-lean lubrication) during rotation of the main shaft. It is an example. The table on the right side of each display example shows various conditions of the spindle speed, the amount of preload applied to the bearing, and the lubrication timing in each figure.

  In the display example shown in FIG. 2 (a), it can be seen that a convex is instantaneously formed only at each lubrication timing, indicating a good lubrication state. The part that goes up stepwise along the way represents the moment when the spindle speed was increased. Further, in the display example shown in FIG. 2B, the convex is instantaneously formed only at the lubrication timing, and the tendency to gradually decrease as a whole becomes a certain tendency thereafter. Yes. Therefore, it can be seen that an excessive amount of lubricating oil accumulated in the bearing is gradually discharged, the amount of lubricating oil in the bearing space becomes an appropriate amount, and the lubricating state is good. For example, in the case of grease lubrication, it is possible to determine that the initial amount of grease accumulated in the bearing is an appropriate amount and that the leveling operation has been completed.

  On the other hand, in the display example shown in FIG. 3A, the input power value does not instantaneously decrease at a part of the lubrication timing, and wide protrusions are randomly formed in the time axis direction. Therefore, at a certain lubrication timing, it can be seen that the heat generation has risen and the increase has not stopped, and the amount of lubricating oil to be replenished is excessive, or a part of the lubricating oil that could not be discharged to the outside. It can be determined that the air is flowing back into the bearing. In the display example shown in FIG. 3B, a large number of protrusions are formed at timings other than the lubrication timing, and a part of the lubricating oil that could not be discharged to the outside flows back into the bearing. Therefore, it can be determined that the lubricating oil is not discharged smoothly.

  Accordingly, the detection unit 26 detects an abnormality in the lubrication state such as an excessive supply amount or defective discharge by determining the heat generation state of the bearings 32a and 32b based on a value other than the input power value corresponding to the lubrication timing. be able to.

In addition, the detection unit 26 measures in advance an appropriate amount of bearing heat generated at each rotational speed in an external memory (not shown) and grasps the abnormality, and the abnormality detection device 10 is built in the machine tool, so that the spindle is started up. Detects abnormal heat generation under no load condition. When it is determined that an abnormality has occurred in the lubrication state, the detection unit 26 generates an alarm.
In the case of a lubrication system such as direct injection lubrication in which the fluctuation of the input value due to the discharge of the lubricant is large, it is possible to take out information on the lubrication timing from the control unit of the lubrication apparatus and ignore the data immediately after the discharge of the lubricant. Although threshold comparison is possible even if the data is moving average, there is an advantage that the detection accuracy is lowered but it is not affected by the discharge timing.

Specifically, the detection unit 26 may determine that an abnormality has occurred in the lubrication state of the bearing when the value of the input power is larger than the predetermined threshold value by comparing the input power value with a predetermined threshold value. . Or, when the time series data created from the input power value is compared with the time series data obtained in the normal time in advance, when the tendency of both time series data is different, an abnormality occurred in the lubrication state of the bearing. You may judge.
Further, the detection unit 26 detects that the tendency of the input power value is gradually increasing from the time series data, and generates an alarm when it can be determined that the lubricating oil is not smoothly discharged. May be.

  In the detection unit 26, the loss of the motor 33 is measured in advance, and the windage loss can be predicted by calculation. Therefore, by subtracting these losses from the input power value, the absolute value of the heat generation of the bearing can also be grasped. Can do. If the heat generation amount of the bearing is significantly higher than the calculated value, it can be determined that the assembly is defective such as a preload adjustment error.

  Furthermore, the detection unit 26 sends the detection result of the abnormality of the lubrication state of the bearings 32a and 32b to the control unit 23, and controls the motor 33 so as to decrease the main shaft rotation speed or stop the main shaft device body 21. Alternatively, the spindle device main body 21 can be prevented from being damaged by controlling the amount of lubricating oil and the lubrication timing of the lubrication device 11.

  Therefore, according to the present embodiment, the value of the input power supplied to the motor 33 is measured by the current measuring device 24 and the voltage measuring device 25, and the detection unit 26 detects the measured input power value or the input power. Since the heat generation state of the bearings 32a and 32b is determined based on the series data and the abnormality in the lubrication state of the bearings 32a and 32b is detected, the occurrence of the abnormality in the lubrication state of the bearings 32a and 32b can be grasped in real time. Damage to 32a and 32b can be prevented.

For example, when measuring the temperature of the conventional bearings 32a and 32b, the temperature of the bearings 32a and 32b rises as the main shaft 31 rotates, so that the heat generation of the bearings 32a and 32b is constant and normal. In addition, even in an abnormal state of increasing or decreasing, the temperature of the bearings 32a and 32b gradually increases to a temperature equilibrium state. For this reason, it is possible to monitor the lubrication state to some extent by measuring the temperature of the bearings 32a and 32b, but it is impossible to accurately grasp the abnormality of the lubrication state. In the case of a completely abnormal state, an abnormal temperature rise appears, but in this case, the bearings 32a and 32b are often damaged when it is determined to be abnormal.
On the other hand, in the case of this embodiment, since the lubrication state can be grasped in real time, damage to the bearings 32a and 32b can be prevented.

  Further, when measuring the temperature of the bearings 32a and 32b, it is necessary to incorporate a temperature sensor inside the main spindle device main body 21, and there is a problem that the structure of the main spindle device main body 21 becomes complicated. In the case of the embodiment, since the temperature sensor is not required inside the apparatus main body 21, it is not necessary to change the structure of the apparatus main body 21.

  Furthermore, the abnormality detection of the lubrication state according to the present embodiment can be used for improving the lubrication structure during the rotation test of the bearings 32a and 32b and the spindle device 20, for example, based on the value of input power in the spindle development and test stages. Thus, the lubrication conditions, preload conditions, etc. can be determined more appropriately.

In addition, this invention is not limited to embodiment mentioned above, A suitable deformation | transformation, improvement, etc. are possible.
For example, in the above-described embodiment, the built-in motor type in which the motor 33 is built in the spindle device main body 21 is exemplified, but the motor provided outside the spindle device main body may be a direct connection type or a belt drive type. good.
The detection process of the present invention is not limited to the detection unit as in the present embodiment, and includes a case of artificial detection.

1 is a configuration diagram of a spindle device abnormality detection device and a machine tool according to an embodiment of the present invention. FIG. (A) And (b) is a display example of the time series data display part of the time series data of the input power value when the lubrication state of the bearing is normal. (A) And (b) is a display example of the time series data display part of the time series data of the input power value when the lubrication state of the bearing is abnormal. It is sectional drawing which shows the conventional main axis | shaft apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Abnormality detection apparatus for spindle apparatuses 11 Lubricating apparatus 20 Spindle apparatus 21 Main spindle apparatus main body 22 Electric power supply part 23 Control part 24 Current measuring device (electric power measurement part)
25 Voltage measuring device (Power measuring unit)
26 Detection Unit 26a Time Series Data Display Unit 31 Spindle 32a, 32b Bearing 33 Motor

Claims (4)

A main spindle device body having a main shaft rotatably supported by a bearing, a motor that rotationally drives the main shaft, a power supply unit that supplies power to the motor, and a control unit that controls the power of the power supply unit An abnormality detection device for a spindle device that detects an abnormality of the bearing of the spindle device comprising:
In a lubrication method in which lubricating oil is discharged to the bearing at a lubrication timing, a value of input power supplied from the power supply unit when the main shaft rotates at a constant speed with no load is measured, and the input power A power measurement unit capable of holding time-series data of values of
When comparing the time series data measured by the power measuring unit with the time series data obtained in advance at normal time, in the measured time series data, there is a wide protrusion on a part of the lubrication timing. When the tendency of both time-series data is different due to the formation of a large number of projections at a timing other than the lubrication timing, it is determined that the bearing is abnormally heated and the lubrication state of the bearing A detection unit for detecting abnormalities of
An abnormality detection device for a spindle device, comprising: The abnormality detection device according to claim 1,
When the abnormality detection device detects an abnormality in a lubrication state, the control unit controls at least one of the main shaft device main body and a lubrication device that supplies a lubricant to the bearing.   A machine tool comprising the spindle device according to claim 2. A main spindle device body having a main shaft rotatably supported by a bearing, a motor that rotationally drives the main shaft, a power supply unit that supplies power to the motor, and a control unit that controls the power of the power supply unit An abnormality detection method for a spindle device that detects an abnormality of the bearing of the spindle device comprising:
In a lubrication method in which lubricating oil is discharged to the bearing at a lubrication timing, a step of measuring input power supplied to the motor when the main shaft rotates at a constant speed with no load by a power measuring unit;
Creating the measured value of the input power as time-series data;
The time series data is compared with time series data obtained in advance at normal times. In the measured time series data, a wide protrusion is formed at a part of the lubrication timing, or the lubrication is performed. A step of detecting an abnormality in the lubrication state of the bearing by determining that the bearing has abnormally heated when the tendency of both time series data is different due to the formation of a large number of protrusions at a timing other than the timing ; and
An abnormality detection method for a spindle apparatus, comprising:

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