JP4322494B2 - Magnetic bearing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic bearing device, and more particularly to a magnetic bearing device that facilitates support of a rotating body at a predetermined position and rotation stop positioning.
[0002]
[Prior art]
Hereinafter, a conventional magnetic bearing device will be described with reference to the drawings. FIG. 3 is a block diagram showing a schematic configuration of a conventional magnetic bearing device.
[0003]
In FIG. 3, 20 is a rotating body, and 21 is a main shaft in which a motor rotor 22, radial magnetic bearing rotors 24 and 26, and a thrust magnetic bearing rotor 28 are attached to the rotating body 20. Radial displacement sensors 30 and 31 for detecting the displacement of the radial magnetic bearing electromagnets 25 and 27, the thrust magnetic bearing electromagnet 29, and the rotating body 20 at a small distance from the radial magnetic bearing rotors 24 and 26 and the thrust magnetic bearing rotor 28. A thrust displacement sensor 32 is arranged. Reference numeral 33 denotes a protective member made up of a protective bearing, etc., and 34 denotes a variable weight portion that engages with the tool. Further, an encoder 35 is attached to the rotating body 20, and a current is passed through the motor stator 23 by the motor driving device 36. Thus, the rotating body 20 is driven to rotate.
[0004]
Next, a magnetic bearing control device for controlling the magnetic bearing of this device will be described. The magnetic bearing control device 1 includes adders 2 and 5 for subtracting the displacement signal from the radial displacement sensors 30 and 31 and the thrust displacement sensor 32 and the displacement signal and the position command value. rotating body 20 and the radial magnetic bearing electromagnets 25 and 27 on the basis of the output, and a phase compensator 3, 6, and power over amplifier 4,7 to control the magnetic attraction force acting between the thrust magnetic bearing electromagnet 29 ing. Here, the adder 2, the phase compensator 3, power over amplifier 4 constitutes a radial magnetic bearing control device 8 for controlling the radial magnetic bearings, The adder 5, a phase compensator 6, the power amplifier 7 A thrust magnetic bearing control device 9 is configured to control the thrust magnetic bearing.
[0005]
Next, the operation will be described. First, the displacement of the rotating body 20 is detected by the radial displacement sensors 30 and 31 and the thrust displacement sensor 32, and the output signal is applied to the adders 2 and 5. The adders 2 and 5 subtract the output signal from a command position (target value) that supports the rotating body 20, and the subtracted signal is input to the phase compensators 3 and 6, and output from the phase compensators 3 and 6. power amplifier 4,7 is operated by the radial magnetic bearing electromagnets 25 and 27, current flows to the thrust magnetic bearing electromagnet 29, between the radial magnetic bearing electromagnets 25, 27 and the radial magnetic bearing rotor 24, the thrust magnetic bearing electromagnet 29 And the position of the rotary body 20 in the radial direction and the thrust direction are controlled by electromagnetic attraction generated between the thrust magnetic bearing rotor 28 and the thrust magnetic bearing rotor 28. When not controlled by the thrust magnetic bearing control device 9, the rotating body 20 is supported by the protection member 33. The rotation direction of the rotating body 20 is controlled by inputting a signal from the encoder 35 to the motor driving device 36 and controlling the current flowing through the motor stator 23 by the motor driving device 36 to perform rotation driving and stop positioning.
[0006]
When performing actual machining, for example, when a magnetic bearing spindle is mounted on a machine tool and machining is performed while changing multiple types of tools, the general procedure for automatic tool change is to use the tool holder angle and rotating body angle. The tool is changed after performing an orientation operation to stop the rotating body (spindle) at a predetermined rotation angle so as to match.
[0007]
Patent Document 1 describes the configuration of a rotating device and a processing device including the rotating device.
[0008]
[Patent Document 1]
JP 2000-324755 A
[Problems to be solved by the invention]
However, in the configuration as described above, when the rotating body is rotated and positioned at an arbitrary position by the motor driving device, the rotating body is controlled to be levitated in the air. There are problems that it is remarkably less in comparison with the above, easily vibrates in the rotational direction, and it is difficult to increase the rotational positioning rigidity.
[0010]
The present invention solves the above-mentioned conventional problems, and provides a magnetic bearing device capable of increasing the rotational positioning rigidity by increasing the motion loss in the rotational direction of the rotating shaft during rotation stop positioning. The purpose is to do.
[0011]
[Means for Solving the Problems]
Magnetic bearing device of the present invention, a radial controlled fly by the control current, is supported by a thrust magnetic bearing electromagnets rotating comprises a rotary body which is stop control, when replacing a tool attached to the rotary member A bias command generator for applying a bias current to the thrust magnetic bearing electromagnet based on a rotation positioning operation signal and a zero speed signal applied from outside during rotation stop positioning is provided, and radial position control is performed during rotation stop positioning of the rotating body. The rotational positioning rigidity is increased by bringing the rotating body into contact with the thrust protection member while maintaining the rotation stop position.
[0012]
According to the present invention, the position control of the thrust magnetic bearing is stopped at the time of rotation stop positioning, and a bias current is applied to the thrust electromagnet to bring the rotating body into contact with the protective member. Attenuation increases, rotation loss when rotation stops, and rotation positioning rigidity can be increased.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol shall be used about the same part as the said conventional thing. FIG. 1 is a block diagram showing the overall configuration of an embodiment of a magnetic bearing device of the present invention, and FIG. 2 shows a specific example of a magnetic bearing spindle device to which this is applied in an embodiment of a magnetic bearing device of the present invention. It is sectional drawing.
[0014]
First, the magnetic bearing spindle device portion shown in FIGS. 1 and 2 will be described.
[0015]
In FIGS. 1 and 2, reference numeral 20 denotes a rotating body, and reference numeral 21 denotes a main shaft in which a motor rotor 22, radial magnetic bearing rotors 24 and 26, and a thrust magnetic bearing rotor 28 are attached to the rotating body 20. The radial magnetic bearing rotor 24, the radial displacement detecting the displacement of the thrust magnetic bearing rotor 28 radial magnetic axis receiving magnets 25 and 27 at a distance of small distance from, the thrust magnetic axis receiving magnet 29, rotor 20 Sensors 30 and 31 and a thrust displacement sensor 32 are disposed, and the rotating body 20 is supported in a non-contact manner at a predetermined position.
[0016]
Here, the periphery of the radial magnetic bearing electromagnets 25 and 27 rotating body 20, for example arranged One not a four on the left and right at the center angle of 90 °, also, a ring-shaped thrust magnetic bearing electromagnet 29 surrounding the rotor 20 Has been placed. Further, as the radial displacement sensors 30, 31 and the thrust displacement sensor 32, well-known eddy current sensors, capacitance sensors, optical sensors, and the like are used. Reference numeral 33 denotes a protective member made up of a protective bearing, etc., and 34 denotes a variable weight portion that engages with the tool. Further, an encoder 35 is attached to the rotating body 20, and the motor driving device 36 rotates by passing an electric current through the motor stator 23. The body 20 is rotated. Reference numeral 37 denotes a casing.
[0017]
Next, a magnetic bearing control device for controlling the magnetic bearing of this device will be described. The magnetic bearing control device 40 includes adders 2 and 5 for subtracting the displacement signal from the radial displacement sensors 30 and 31 and the thrust displacement sensor 32 and the displacement signal and the position command value. The phase compensators 3 and 6 and the power amplifiers 4 and 7 for controlling the magnetic attractive force acting between the rotating body 20, the radial magnetic bearing electromagnets 25 and 27, and the thrust magnetic bearing electromagnet 29 based on the output, and rotation from the outside Generation of a bias command for applying a bias current to the thrust magnetic bearing electromagnet 29 when two signals of a signal Sg1 indicating that the positioning operation is in progress and a zero speed signal Sg2 indicating that the motor is below a predetermined rotational speed are received. The apparatus 10 is comprised. Here, the adder 2, the phase compensator 3, and the power amplifier 4 constitute a radial magnetic bearing control device 8 for controlling the radial magnetic bearing, and the adder 5, the phase compensator 6, the bias command generator 10, the power The amplifier 7 constitutes a thrust magnetic bearing control device 9 that controls the thrust magnetic bearing.
[0018]
Next, the operation will be described. First, the displacement of the rotating body 20 is detected by the radial displacement sensors 30 and 31 and the thrust displacement sensor 32, and the output signal is applied to the adders 2 and 5. The adders 2 and 5 subtract the output signal from the command position (target position) of the rotating body 20, and the subtracted signal is input to the phase compensators 3 and 6, and the output from the phase compensators 3 and 6 The power amplifiers 4 and 7 are operated to pass current through the radial magnetic bearing electromagnets 25 and 27 and the thrust magnetic bearing electromagnet 29, and between the radial magnetic bearing electromagnets 25 and 27 and the radial magnetic bearing rotors 24 and 26, and between the thrust magnetic bearing electromagnet 29 and The position of the rotary body 20 in the radial direction and the thrust direction is controlled to fly by the electromagnetic attractive force generated between the thrust magnetic bearing rotors 28. When the position is not controlled by the thrust magnetic bearing control device 9 , the rotating body 20 is supported by the protection member 33. The rotation direction of the rotating body 20 is controlled by inputting a signal from the encoder 35 to the motor driving device 36 and controlling the current of the motor stator 23 by the motor driving device 36 to perform rotation driving and stop positioning. That although this basic levitation control operation is the same as the conventional, when the rotation stop position of the spindles (rotating member 20), is less than a predetermined rotational speed signal Sg1 and the motor is determined indicating that a rotational positioning operation A zero speed signal Sg2 is input to the magnetic bearing control device 40, an output signal of the bias command generator 10 is input to the power amplifier 7, and a bias current is applied to the thrust magnetic bearing electromagnet 29 by the power amplifier 7.
[0019]
Here, as means for switching from normal levitation control to control for applying a bias current, a signal Sg1 indicating that the rotational positioning operation is in progress and a zero speed signal Sg2 indicating that the motor is below a predetermined number of rotations are magnetic bearings. When input to the control device 40, means for switching the input of the power amplifier 7 from the output of the phase compensator 6 to the output of the bias command generator 10, or the output of the phase compensator 6 and the output of the bias command generator 10 in advance. When the signal S g 1 indicating that the rotational positioning operation is being performed and the zero speed signal Sg 2 indicating that the motor is equal to or less than a predetermined rotation speed are input to the magnetic bearing control device 40 in advance. A means for making the output of the phase compensator 6 zero can be considered. At this time, the position of the radial magnetic bearing is controlled as in the conventional case.
[0020]
When a bias current is applied to the thrust magnetic bearing electromagnet 29 in this way, for example, a thrust force in the thrust direction acts on the variable weight portion 34 engaged with the tool, and the rotating body 20 contacts the protection member 33. Pressed. When the rotating body 20 is brought into contact with the protective member 33, the friction loss and the viscous damping give a loss to the movement in the rotation direction, and this loss suppresses the vibration in the rotation direction at the time of rotation stop positioning, and the rotation stop positioning. The rigidity can be dramatically increased. In addition, in the case of a machine tool, for example, in the case of a machine tool, the rotational positioning operation in-progress signal Sg1 and the zero speed signal Sg2 can be easily input from a control device or a motor rotation driving device mounted on the processing machine.
[0021]
As described above, according to the present embodiment, by applying a bias current to the thrust electromagnet at the time of rotation stop positioning, the rotating body can be brought into contact with the protective member and the rotation loss at the time of rotation stop can be increased. Rotational positioning rigidity can be dramatically increased.
[0022]
【The invention's effect】
As described above, according to the present invention, at the time of rotation stop positioning, a bias current is applied to the thrust electromagnet, and the rotating body is brought into contact with the protective member, thereby increasing the rotation loss at the time of rotation stop and increasing the rotation positioning rigidity. The advantageous effect that it can be dramatically increased is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of an embodiment of a magnetic bearing device of the present invention. FIG. 2 is a specific example of a magnetic bearing spindle device to which the magnetic bearing device of the present invention is applied. FIG. 3 is a block diagram showing a schematic configuration of a conventional magnetic bearing device.
DESCRIPTION OF SYMBOLS 1 Magnetic bearing control apparatus 2, 5 Adder 3, 6 Phase compensator 4, 7 Power amplifier 8 Radial magnetic bearing control apparatus 9 Thrust magnetic bearing control apparatus 10 Bias command generator 20 Rotor 21 Main shaft 22 Motor rotor 23 Motor stator 24, 26 Radial magnetic bearing rotor 25, 27 Radial magnetic bearing electromagnet 28 Thrust magnetic bearing rotor 29 Thrust magnetic bearing electromagnet 30, 31 Radial displacement sensor 32 Thrust displacement sensor 33 Protective member 34 Variable weight section 35 Encoder 36 Motor drive device 37 Casing Sg1 Rotation positioning Operating signal Sg2 Zero speed signal

Claims (2)

A rotary body supported by a radial and thrust magnetic bearing electromagnet that is controlled to fly by a control current and controlled to rotate and stop. It is applied from the outside during rotation stop positioning when changing the tool attached to the rotary body. A bias command generator for applying a bias current to the thrust magnetic bearing electromagnet based on the rotational positioning operation in-progress signal and the zero speed signal, while maintaining the rotation stop position by performing radial position control during the rotation stop positioning of the rotating body A magnetic bearing device characterized in that rotational positioning rigidity is increased by bringing a rotating body into contact with a thrust protection member. A spindle in which a radial, thrust magnetic bearing electromagnet and a rotary drive motor controlled to fly by a control current are integrated, a motor drive device capable of stopping rotation of the rotary drive motor at an arbitrary rotational position, and the magnetic bearing electromagnet A magnetic bearing device comprising a magnetic bearing control device for supplying a control current to the motor, wherein a thrust is received based on reception of a motor rotation positioning operation signal and a zero speed signal applied from the outside during rotation stop positioning of the rotation drive motor. A thrust protection member comprising a bias command generator for applying a bias current to the magnetic bearing electromagnet, and performing radial position control at the time of rotation stop positioning when the tool attached to the rotating body is replaced while maintaining the rotation stop position The rotational positioning rigidity is increased by bringing the rotating body into contact with Magnetic bearing apparatus.

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