JP3096821B2 - Control type magnetic bearing spindle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controllable magnetic bearing spindle used for a grinding wheel head and the like, and more particularly, learns and memorizes inertia center coordinates at high speed rotation even when the rotor shaft rotates at geometric center coordinates at low speed. The present invention relates to a control type magnetic bearing spindle that performs control so as to rotate at a speed.

[0002]

2. Description of the Related Art Conventionally, a circumferential runout tolerance of a rotor shaft (hereinafter referred to as a "tolerance") has been known.
A control-type magnetic bearing spindle capable of controlling the rotation coordinate of the rotor shaft as required) is often used. As this type of controlled magnetic bearing spindle, Japanese Patent Laid-Open No.
Japanese Patent No. 24319 discloses a synchronous disturbance compensator in a magnetic suspension rotor.

The synchronous disturbance compensating device in the magnetic suspension rotor controls the rotating shaft of the rotor shaft and controls the influence of the periodic vibration generated due to various imbalances when controlling the rotating shaft. It is configured to reduce. As described above, even with the conventional control type magnetic bearing spindle, the rotation coordinates of the rotor shaft can be controlled.

[0004]

However, the control type magnetic bearing spindle as in the conventional example described above can control only the inertia center coordinate at the time of high-speed rotation, and controls the rotation coordinate at the time of low-speed rotation. Is not taken into account. Therefore, for example, when a grindstone with a large diameter is rotated by a grindstone head, the rotation at low-speed rotation is performed at the geometric center coordinates, so that the rotational displacement around the grindstone becomes large, and there is a drawback that precision grinding work of the processed member is difficult.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an excellent control type magnetic bearing spindle that can rotate a rotor shaft at the center of inertia at the time of low-speed rotation as in the case of high-speed rotation.

[0006]

In order to achieve the above object, a controlled magnetic bearing spindle according to the present invention comprises a rotor shaft having magnetism, a plurality of electromagnets for magnetically levitating the rotor shaft, and A plurality of position detecting means for outputting detection signals indicating rotation coordinates of the rotor shaft, and a current supplied to the plurality of electromagnets for magnetic levitation so as to magnetically levitate and hold the rotor shaft at a predetermined position based on the detection signals. Control means for controlling the rotation of the rotor shaft and the inertia center coordinate at the time of high-speed rotation of the rotor shaft, and the operation instruction of the first control means such that the rotor shaft at the time of low-speed rotation is stored at the stored center coordinate of inertia. And a second control means for performing the following.

[0007]

In the control type magnetic bearing spindle of the present invention configured as described above, even at a low speed in which the rotor shaft rotates at the geometric center coordinates, the rotor shaft rotates at the learned and stored inertia center coordinates at the high speed rotation. Therefore, the rotor shaft can be rotated at the inertia center coordinate at the time of low-speed rotation as well as at the time of high-speed rotation.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the overall configuration of the embodiment. In this example, a rotor shaft 12 having magnetism is inserted into a housing 10. A high-frequency motor coil 13 for rotating the rotor shaft 12 is disposed inside the housing 10 at a central portion of the rotor shaft 12.

Further, a metal disk 14 having magnetism and used for displacement control on the Z-axis is fixed to the rotor shaft 12. A pair of electromagnets 30 are provided inside the housing 10 so as to sandwich the metal disk 14 and oppose each other to perform magnetic driving on the Z axis. Further, the rotor shaft 1
A pair of electromagnets (corresponding to electromagnets for magnetic levitation) 32 arranged on the X-axis with the rotor shaft 12 interposed therebetween on the circumference of 2
And a pair of electromagnets 34 (corresponding to magnetic levitation electromagnets) arranged on the Y-axis.

A pair of electromagnets (corresponding to magnetic levitation electromagnets) 36 arranged on the X axis and a pair of electromagnets (magnetic levitation) arranged on the X axis are separated from the electromagnet 32 and the electromagnet 34. (Corresponding to the electromagnet for use) 38 is provided.
That is, four electromagnets 32 and 34 and electromagnets 36 and 38 are arranged on the circumference around the rotor shaft 12 at 90 ° intervals.

An inductive type position sensor (corresponding to position detecting means) is provided in close proximity to each of the electromagnets 32, 34, 36, 38.
42, 44, 46, 48 are provided. These electromagnets 32, 34, 36, 38 are position sensors 42, 44,
A so-called four-axis magnetic bearing, which holds the rotor shaft 12 together with 46 and 48 by magnetically levitating and holding the rotor shaft 12 in the housing 10 by the attraction of magnetic force.

A pulse generator (PG) for measuring the number of rotations of the rotor shaft 12 is provided. The PG includes a magnetic detection type rotation sensor 50 provided inside the housing 10, and a magnet 51 on the rotor shaft 12 facing the rotation sensor 50. Rotor shaft 1
When the magnet 2 rotates, the magnetism is detected at a position where the magnet 51 and the rotation sensor 50 face each other, and a pulse signal is output from the rotation sensor 50. Further, a motor 54 is arranged inside the housing 10.

The electromagnets 30, 32, 34, 36, 3
8. The position sensors 42, 44, 46, 48 and the rotation sensor 50 are connected to a signal processing system including a magnetic levitation controller, a system controller, and the like, which will be described in detail below. Here, the electromagnets 30, 32, 3
4, 36, 38, position sensors 42, 44, 46, 48
And an arrangement state of the rotation sensor 50 will be described in detail.

In this figure, for easy understanding, the electromagnets 32, 34, 36, 38 and the position sensors 42, 4
4, 46 and 48 are shown separately. Next, the electrical configuration will be described. FIG. 3 shows the electrical configuration in the above. In this example, a system controller 70 using a microprocessor (MPU) or the like (corresponding to the second control means)
And a magnetic levitation controller 80 (corresponding to the first control means).

The system controller 70 has a CPU
70a, a ROM 70b storing a program, a working RAM 70c, and a keyboard interface (I /
F) 70d, display I / F 70e, I / O 70f, 70
g and 70h, which are the internal bus lines 70 and 70h.
j. The keyboard I / F 70d is connected to a keyboard 74 for performing an operation for storing the coordinates of the center of inertia during high-speed rotation.

The display I / F 70e is connected to a display 76 such as an LCD for displaying an operation state from the keyboard 74, a floating state, and an operation state. I /
O70f is connected to a magnetic levitation controller 80. The magnetic levitation controller 80 has PIDs 82a, 82b, 82c, 82d, 82 to which detection signals from a pair of position sensors 40, 42, 44, 46, 48 are respectively input.
e is provided.

Further, PIDs 82a, 82b, 82c, 8
Amplifiers 84a and 84e are connected to the output terminals of 2d and 82e, respectively.
b, 84c, 84d and 84e are connected. Outputs of the amplifiers 84a, 84b, 84c, 84d, 84e are respectively connected to a pair of electromagnets 30, 32, 34, 36,
38, that is, two sets of coils are connected. The magnetic levitation controller 80 controls the amplifier 82 so that the Z axis of the metal disk 14 of the rotor shaft 12 during magnetic levitation is kept constant based on a detection signal from the position sensor 40.
a Control is performed to change the current supplied to the electromagnet 30 by changing the amplification factor. When the rotor shaft 12 magnetically levitates, the coordinates of the magnetically levitated rotor shaft 12 are set in the vertical (V) direction and the horizontal (W) direction based on the detection signals from the position sensors 42, 44, 46, and 48. To keep it constant
Control is performed to change the current supplied to the electromagnets 32, 34, 36 and 38 by changing the amplification factors of the amplifiers 84b, 84c, 84d and 84e.

A rotation sensor 50 is connected to the I / O 70g, and a pulse signal from the rotation sensor 50 is read by the CPU 70a to detect the rotation speed of the rotor shaft 12. I / O 70h is a motor driver 7
6 is connected. Next, the operation of the above configuration will be described. First, a description will be given of a control operation for performing low-speed rotation at the learned and stored inertia center coordinates.

FIG. 4 is a flow chart corresponding to the control operation when rotating at a low speed with the inertia center coordinates learned and stored. After the entire operation, the magnetic levitation controller 8
The electromagnets 30, 32, 34, 36, 38 operate with a current from 0, and the rotor shaft 12 floats in the housing 10,
It is kept constant at a predetermined coordinate position (step (S) 10)
1). The CPU 70a determines whether there is any abnormality in this operation, that is, whether the operation is in a predetermined operation state (S102).

In the case of Yes for abnormal operation, S
Proceeding to step 122, after displaying the abnormality according to the content of the abnormality, the processing after S102 is repeated, or the processing for stopping the operation due to power-off is performed. In the case of this power supply cutoff, the power supply switch (not shown) is turned off and then turned on to perform the operation again. In the case of No, the rotation start is manually instructed (ON) from the keyboard 74 (S103).

The CPU 70a determines this rotation start ON (S104). When the rotation start instruction is Yes, the motor driver 76 is driven through the I / O 70h under the control of the CPU 70a, and the motor driver 76 supplies power to the high-frequency motor coil 13 to rotate the rotor shaft 12 (S105). At the same time, a pulse signal from the rotation sensor 50 is sent to the CPU 70 through the I / O 70g.
“a” is fetched by polling, interrupt processing, or the like. In the case of No, it is determined that the rotation start ON has not been performed, and S10
2 and the subsequent processing procedure is repeated.

Next, it is determined whether or not there is any abnormality in this operation (S106). In the case of Yes with an abnormality, S122
Then, a predetermined process, for example, abnormality display or power-off is performed. . In the case of No indicating no abnormality, it is determined whether a predetermined high-speed rotation has started (S107). Here, if the predetermined high-speed rotation has not been reached, the process returns to S106 to determine whether or not an abnormality has occurred. In the case of Yes in which a predetermined high-speed rotation has been reached, as described below, R
The previous inertia center coordinate information stored in the AM 70c is deleted (S108).

Further, it is determined whether or not there is any abnormality (S
109). In the case of Yes in which there is an abnormality, the process proceeds to S122, where an abnormality is displayed according to the content of the abnormality, and thereafter, processing after S102 is repeated or the operation is stopped due to power interruption. In the case of this power failure, a power switch (not shown) is turned off and then turned on.
Is instructed (ON) manually (S110).

Subsequently, it is determined whether a rotation stop is instructed from the keyboard 74 (S111). If the rotation stop is not instructed within the predetermined time, that is, if No, S10
9 and repeat the processing from here. In the case of Yes instructed to stop the rotation, the rotation stop signal instructed by the keyboard 74 is transmitted to the C through the keyboard I / F 70d.
The PU 70a takes in (S112).

Here, the CPU 70a is provided with the position sensor 4
Levitation controller 80 to which the second detection signal is supplied
2, the coordinate information Va ₁ and Va ₂ in the vertical (V) direction of the rotor shaft 12 are fetched as shown in FIG.
c (S113). Further, under the control of the CPU 70a, the magnetic levitation controller 80, to which the detection signal of the position sensor 44 is supplied, receives coordinate information Wa ₁ , Wa in the horizontal (W) direction of the rotor shaft 12 as shown in FIG.
₂ is fetched and stored in the RAM 70c (S114).
Similarly, under the control of the CPU 70a, the coordinate information Vb ₁ and Vb ₂ are fetched from the magnetic levitation controller 80 to which the detection signal of the position sensor 46 is supplied, and the RAM 7
0c (S115).

Further, similarly, under the control of the CPU 70a, the coordinate information Wb ₁ and Wb ₂ are fetched from the magnetic levitation controller 80 to which the detection signal of the position sensor 48 is supplied and stored in the RAM 70c (S116). Further, under the control of the CPU 70a, the Z-axis coordinate information Za of the rotor shaft 12 is fetched from the magnetic levitation controller 80 to which the detection signal of the position sensor 40 is supplied as shown in FIG. 2 and stored in the RAM 70c (S117).

In the processing of S113 to S117, the five-axis coordinate information of the center of inertia at the time of high-speed rotation of the rotor shaft 12 is obtained. Note that S113 to S117
May be processed in any order. After receiving the rotation stop signal in S112, the CPU 70a controls to stop the operation of the motor driver 76 through the I / O 70h. Here, it is determined whether or not a predetermined number of high-speed rotations have been completed. In the case of No, it is determined that the motor is still rotating at high speed, and the process returns to S113 to execute the processes from S113 to S117 again. In the case of Yes in which the predetermined number of high-speed rotations has been completed and the low-speed rotation has been completed, S113 to S117
5-axis information of the inertial center stored in RAM70c in, i.e., coordinate information _{Va 1, Va 2, Vb 1} , Vb 2, W
a ₁ , Wa ₂ , Wb ₁ , Wb ₂ and Za are stored in the RAM 70.
c, and reads this value from the magnetic levitation controller 8.
Supply 0. The magnetic levitation controller 80 to which this value is supplied performs control so that the rotor shaft 12 rotates with the five-axis coordinate information.

Therefore, the rotor shaft 12 rotates at the inertia center coordinate even during the low-speed rotation. Next, it is determined whether there is any abnormality in this state (S120). In the case of Yes where there is an abnormality, the process proceeds to S122 to display an abnormality according to the content of the abnormality, and then repeats the processing procedure from S102 and on or performs processing for stopping the operation due to power cutoff. In the case of this power supply cutoff, the power supply switch (not shown) is turned off and then turned on to perform the operation again. It is assumed that the rotor shaft 12 is rotating based on the 5-axis coordinate information without any abnormality.
No, the pulse signal from the rotation sensor 50 is
C in polling processing, interrupt processing, etc. through O70g
The PU 70a captures the data, and determines here that the rotation of the rotor shaft 12 has stopped. If not stopped, the process returns to S120, and S
Steps S120 and S121 are repeated until the rotation stops. When it is confirmed that the rotation has stopped, the process returns to S102 to be in a re-executable state.

Next, a case where the low-speed rotation of the rotor shaft 12 at the start of rotation is controlled based on the inertia center coordinate axis stored in the RAM 70c will be described. FIG. 5 shows a flowchart corresponding to this control operation. After the instruction of the entire operation, a current is supplied from the magnetic levitation controller 80 to operate the electromagnets 30, 32, 34, 36, and 38, and the rotor shaft 12 floats in the housing 10 and is fixed at a predetermined coordinate position. (S201).

If there is no abnormality in the floating operation,
The CPU 70a determines whether or not it is in a predetermined operation state based on a signal taken from the magnetic levitation controller 80 through the I / F 70f (S202). In the case of Yes indicating that the operation is abnormal, the process proceeds to S222. In S222, after displaying the abnormality according to the content of the abnormality, the processing after 202 is repeated, or the processing for stopping the operation due to the power-off is performed. In the case of this power supply cutoff, the power supply switch (not shown) is turned off and then turned on to perform the operation again. N
In the case of o, a rotation start is manually instructed (ON) from the keyboard 74 (S203).

The CPU 70a takes this rotation start ON and makes a determination (S204). Rotation start instruction Y
In the case of es, the motor driver 76 operates through the I / O 70h under the control of the CPU 70a, and the rotor shaft 12
Rotates (S205). At the same time, the CPU 70a captures a pulse signal from the rotation sensor 50 through the I / O 70g by polling, interrupt processing, or the like. Rotation start O
If N has not been performed, the process returns to S202, and the subsequent processing procedure is repeated.

Subsequently, it is determined whether or not there is any abnormality in this operation (S206). S22 in case of Yes with abnormality
Proceeding to step 2, a predetermined process, for example, an error display or power-off is performed. If No, there is no abnormality, the inertia center coordinate axis information stored in the RAM 70c last time is read from the RAM 70c under the control of the CPU 70a (S207). The read five-axis coordinate information of the center of inertia, that is, coordinate information Va ₁ , V
_{a 2, Vb 1, Vb 2} , Wa 1, Wa 2, Wb 1, Wb
₂ and Za are supplied to the magnetic levitation controller 80. In the magnetic levitation controller 80, the amplifying units 84a, 84b, 84c,
The electromagnets 30, 3 are changed by changing the amplification factors of 84d and 84e.
2, 34, 36, and 38 are controlled (S2
08).

Therefore, even at the time of low-speed rotation at the start of rotation, the rotor shaft 12 rotates at the inertia center coordinate. Here, the CPU 70a captures the rotation speed signal (pulse signal) from the rotation sensor 50 through the I / O 70g by polling processing, interrupt processing, and the like (S209). In this state, it is determined whether there is no abnormality (S210).

In the case of Yes in which there is an abnormality, the process proceeds to S222 and performs a predetermined process. In the case of No, which is normal, when the value of the high-speed rotation of the center of inertia reaches a preset value, the magnetic levitation controller 80 stops controlling the read 5-axis coordinate information of the center of inertia. Here, a series of processing procedures up to high-speed rotation, which is the center of inertia, ends. In this manner, the rotor shaft 12 can be rotated at the inertia center coordinate at the time of low-speed rotation as well as at the time of high-speed rotation. For example, when a large-diameter grindstone is rotated with a grindstone table to which the present embodiment is applied, Even at low speed rotation, there is no rotational displacement of the end of the grindstone, which facilitates precision grinding of the processed member.

In the above embodiment, control is performed based on coordinate information of five axes, but the present invention is not limited to this. For example, a thrust bearing other than a magnetic bearing may be used.

[0036]

As is apparent from the above description, the control type magnetic bearing spindle of the present invention can be rotated at the inertia center coordinate at the time of high speed rotation learned and stored even at a low speed where the rotor shaft rotates at the geometric center coordinate. Therefore, there is an effect that the rotor shaft can be rotated at the inertia center coordinates in the subsequent low-speed rotation as well as in the high-speed rotation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a control type magnetic bearing spindle of the present invention.

FIG. 2 is a perspective view showing an arrangement of an electromagnet and a position sensor shown in FIG.

FIG. 3 is a block diagram showing an electrical configuration of the embodiment.

FIG. 4 is a flowchart corresponding to a control operation when rotating at a low speed with inertia center coordinates learned and stored.

FIG. 5 is a flowchart corresponding to a control operation when performing low-speed rotation at the inertia center coordinate stored at the start of rotation.

[Explanation of symbols]

 12 rotor shaft 14 metal disk 30, 32, 34, 36, 38 electromagnet 40, 42, 44, 46, 48 position sensor 50 rotation sensor 70 system controller 80 magnetic levitation controller

Claims (1)

(57) [Claims] A rotor shaft having magnetism; a plurality of electromagnets for magnetically levitating the rotor shaft; a plurality of position detecting means for outputting a detection signal indicating a rotation coordinate of the rotor shaft; First control means for controlling the current supplied to the plurality of electromagnets for magnetic levitation so as to magnetically levitate and hold the rotor shaft at a predetermined position based on the detection signal; and And a second control means for storing an inertia center coordinate and instructing the operation of the first control means so that the rotor shaft rotates at a low speed at the stored inertia center coordinate. Control type magnetic bearing spindle.