JP2002039177A - Non-contact bearing spindle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact bearing spindle device capable of preventing cutting errors by avoiding the conditions of resonance prior to machining. SOLUTION: A main spindle 4 is supported by static pressure and magnetic compound bearings 6 and 7. A signal processing means 32 is provided for analyzing the frequency of an output signal of a displacement detecting means 28 which detects the displacement of the main spindle 4. A natural frequency detecting means 34 is provided for determining the natural frequency of the main spindle 4 during mounting of a tool, based on the result of the frequency analysis by the signal processing means 32. A means 36 for treating at the time of a coincidence on the number of revolutions and the number of tool blades is provided which performs a predetermined process in case that an integer times of a formula; (the number of revolutions)×(the number of tool blades) coincide with the natural frequency with the result of detection by the natural frequency detecting means 34 indicates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact bearing spindle device provided with a hydrostatic composite bearing or a magnetic bearing.

[0002]

2. Description of the Related Art When a tool such as an end mill is mounted on a spindle of a spindle device, the number of inherent bending changes depending on the type of the tool and the length of protrusion. When an integer multiple of (number of revolutions) × (number of blades) matches the above natural frequency of bending when machining using a multi-blade tool, chattering occurs due to resonance, making it difficult to perform clean cutting. Whether or not such vibrations occur is usually determined by
There was no choice but to actually check the processing, which resulted in defective processing.

An object of the present invention is to provide a non-contact bearing spindle device capable of avoiding a resonance condition before machining and preventing a cutting defect beforehand. Another object of the present invention is
An object of the present invention is to prevent a cutting defect by avoiding a resonance condition when a resonance condition occurs during processing.

[0004]

A non-contact bearing spindle device (1) according to a first aspect of the present invention is a composite of a magnetic bearing (6B, 7B) and a hydrostatic gas bearing (6A, 7A). The main shaft (4) is supported by the hydrostatic magnetic composite bearings (6, 7), and the displacement detecting means (2) detects the displacement of the main shaft (4).
In the non-contact bearing spindle device provided with 8), a signal processing means (32) for frequency-analyzing the output signal of the displacement detecting means (28) is provided, and the natural frequency of the spindle (4) when the tool is mounted is determined by: A natural frequency detecting means (34) obtained from a frequency analysis result of the signal processing means (32);
According to the detection result of the natural frequency detecting means (34),
A countermeasure means (36) for performing a predetermined process when the integral multiple of (number of rotations) × (number of tool blades) matches the above natural frequency is provided. . According to this configuration, the natural frequency of the spindle (4) in the tool mounted state is obtained by the natural frequency detecting means (34) from the frequency analysis result of the signal processing means (32). According to the detection result of the natural frequency detecting means (34), when an integer multiple of (number of rotations) × (number of tool blades) matches the above natural frequency, a countermeasure is taken when the number of rotations and number of tool blades match. Means (36) performs a predetermined process. For this reason, it is possible to prevent cutting defects by avoiding the resonance conditions before machining. The detection of the natural frequency by the natural frequency detecting means (34) is performed, for example, at a set time after the mounting of the tool (11) and before the start of machining. When the processing machine (13) is provided with a numerical controller (14), the natural frequency is detected by the natural frequency detecting means (34) in response to a predetermined command described in the processing program. You may do it. The natural frequency detecting means (34) may start detection in response to input of a detection command from an operation panel or the like. The coping means (36) when the number of rotations and the number of tool blades match may perform predetermined processing when (number of rotations) × (number of tool blades) matches the above natural frequency.

Means for coping with the above-mentioned rotation speed / number of tool blades (3)
6) a process for generating a warning and a process for slightly shifting the spindle speed when the integral frequency of (number of revolutions) × (number of tool blades) matches the above natural frequency. Both or any one of them may be performed.
When the main shaft rotation speed is slightly shifted as a process in the case of the coincidence, the main shaft (4) rotates at a rotation speed at which resonance does not occur, so that cutting failure due to resonance is prevented beforehand. In addition, such resonance avoidance can be performed automatically. Since the change in the number of revolutions is slight, the influence on the processing speed and processing quality is small. Therefore, the extent to which the spindle speed is slightly shifted is such that the influence of resonance is negligible in terms of machining accuracy, and it is preferable that the change amount is as small as possible. If a warning is issued as a process in the case of the coincidence, the operator sees and hears the warning and performs an appropriate process such as a change in the number of revolutions.

A non-contact bearing spindle device (1) according to a second aspect of the present invention is a hydrostatic magnetic composite bearing () wherein a magnetic bearing (6B, 7B) and a hydrostatic gas bearing (6A, 7A) are combined. The main shaft (4) is supported by the main shafts (6, 7).
In a non-contact bearing spindle device provided with a displacement detecting means (28) for detecting the displacement of
8) Signal processing means (32) for frequency-analyzing the output signal
During processing of a processing machine equipped with the hydrostatic composite bearing spindle device (1), the signal processing means (32)
Monitoring the frequency analysis result, and when chatter vibration is detected that matches the set natural frequency or an integral multiple thereof, the vibration for changing the setting of the processing condition in the control device (14) of the processing machine (13) is changed. Corresponding processing condition changing means (3
5) is provided. In the case of this configuration, during the processing of the processing machine (13), when chatter vibration is detected that matches the set natural frequency or an integer multiple thereof, the processing by the vibration-compatible processing condition changing means (3) causes The setting of the processing conditions in the control device (14) of the processing machine (13) is changed. For this reason, it is possible to prevent cutting defects as early as possible by avoiding resonance conditions. When the vibration-corresponding machining condition changing means (35) detects chattering vibration that matches the set natural frequency, the processing machine (1)
The setting of the processing conditions in the control device (14) of 3) may be changed.

In the non-contact bearing spindle device according to the first or second invention, a magnetic bearing may be provided instead of the hydrostatic / magnetic composite bearing (6, 7). As described above, even in the non-contact bearing spindle device in which the main shaft is supported by the magnetic bearing, the resonance condition can be avoided before machining and the cutting failure can be prevented in advance, as in the case of the support by the hydrostatic composite bearing. In addition, when a resonance condition occurs during machining, the resonance condition can be avoided to prevent cutting defects.

[0008]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a conceptual configuration of a non-contact bearing spindle device according to this embodiment. This embodiment is an example applied to a hydrostatic magnetic composite bearing spindle device. First, the outline will be described. The spindle device 1 mainly includes a spindle device main body 2 and a spindle controller 3. The spindle device main body 2
The spindle 4 is supported by a plurality of radial type hydrostatic magnetic composite bearings 6 and 7 and axial type hydrostatic magnetic composite bearings 8 and 9 installed in a housing 5, and a spindle drive source 10 is provided. Each of the hydrostatic magnetic composite bearings 6 to 9 is a composite of the hydrostatic gas bearings 6A to 9A and the magnetic bearings 6B to 9B, and is controlled by the spindle controller 3.
The main shaft 4 has a chuck 12 at its tip for holding a tool 11. Processing machine 13 equipped with this spindle device 1
Is controlled by the processing machine control device 14. The spindle controller 3 includes a displacement sensor amplifier 31 that amplifies the detection value of the displacement detection unit 28 of the main shaft 4 and a magnetic force control unit 33 that controls the magnetic force of the magnetic bearings 6B to 9B according to the output of the displacement sensor amplifier 31. Prepare.

FIGS. 2 to 5 show the spindle device main body 2.
It is explained together with. The spindle device 1 includes a processing machine 13
The spindle drive source 10 is installed in a housing 5 in which bearings 6 to 9 are installed. The spindle drive source 10 including the motor includes a rotor 21 provided integrally with the main shaft 4 and a stator 22 provided in the housing 5. The housing 5 is formed in a substantially cylindrical shape.
The spindle drive source 10 may be provided outside the housing 5 and transmit rotation to the main shaft 4 via a transmission mechanism, instead of being built-in. In this example, the arrangement of the bearings 6 to 9 and the spindle drive source 10 is such that the front part (tool side part) and the rear part of the main shaft 4 are supported by radial type hydrostatic composite bearings 6 and 7, and the intermediate part is axial. It is configured to be supported by static pressure magnetic composite bearings 8 and 9 of a mold type, and a spindle drive source 10 is arranged at the rear end. Instead of the above arrangement, the spindle drive source 10 may be arranged between the radial bearings 6 and 7, and the axial bearings 8 and 9 may be arranged at arbitrary positions on the main shaft 4. The axial type bearings 8 and 9 may be non-contact bearings, and a single magnetic bearing or a static pressure gas bearing may be used instead of the hydrostatic / magnetic composite bearing.

Radial-type hydrostatic magnetic composite bearings 6, 7
3 have the same configuration. FIG. 3 shows a cross section of one of the bearings 6, and FIG. The hydrostatic and magnetic composite bearings 6 and 7 are each a composite of the hydrostatic gas bearings 6A and 7A and the magnetic bearings 6B and 7B. The term "combination" as used in this specification means that both types of bearings of a static pressure type and a magnetic type are combined so as to generate a common part. For example, a common part (a radial bearing) In this case, an axially overlapping portion may be generated, or at least a part of parts may be shared by both types of bearings.

In this embodiment, as shown in FIG. 4, the throttles 24a of the hydrostatic gas bearings 6A and 7A are provided on the core 23 of the electromagnets of the magnetic bearings 6B and 7B, so that the components of the bearing can be used in common. Part of the bearing surface is configured to overlap in the axial direction. The core 23 includes a pair of main cores 23a, 23a separated in the axial direction, a connection core 23b connecting the main cores 23a, 23a, and both main cores 23a, 23a.
And a pair of extending portions 23c, 23c extending from the main shaft side end to form a C-shaped vertical section. Main core part 23a
The inner diameter side surface of the extension portion 23c is a cylindrical surface forming a predetermined magnetic gap with the main shaft 4. Magnetic bearing 6B, 7
B is a coil in which a coil 25 is wound around a connecting core portion 23b of the core 23. The coil 25 is embedded in a non-magnetic body 26 such as a resin material.

The static pressure gas bearings 6A, 7A are formed on the inner diameter side surfaces of the core 23 and the non-magnetic material 26 and form a bearing gap d between the main shaft 4 and the static pressure bearing surfaces 6Aa, 7Aa. An aperture 24a is provided on each of the main cores 23a, 23a and opens on the hydrostatic bearing surfaces 6Aa, 7Aa. The throttles 24a are provided at the ends of the air supply holes 24 opened on the outer diameter side surfaces of the main core portions 23a. As shown in a stepped cross section in FIG. 3, the cores 23 are arranged at a plurality of locations (four locations in the example in the figure) in the circumferential direction around the main shaft 4 and fixed to the housing 5. The gap between the circumferentially adjacent cores 23 is filled with a non-magnetic material 27 such as a resin material. The non-magnetic body 27 is formed around the non-magnetic body 26 around the coil 25.
(FIG. 4).

The magnetic bearings 6B and 7B are composed of a main shaft 4 and a core 23.
And a displacement detecting means 28 for detecting the displacement of the magnetic gap between them. The displacement detecting means 28 may directly detect the displacement amount, but in this example, by detecting the static pressure in the static pressure bearing gap d, the detected pressure value is converted into the displacement amount. To detect the displacement of the magnetic gap. More specifically, the displacement detecting means 28 is composed of a pressure detection air passage 28a having a distal end opened in the static pressure bearing gap d, and a sensor 28b communicating with the air passage 28a.
The sensor 28b is disposed at a position axially away from the core 23 as shown in FIG. The air passage 28a is formed by a fine hole or a pipe, and the core 2
An opening is provided at the portion of the non-magnetic member 26 between the third extending portions 23c. In FIG. 3, the opening positions of the throttle 24a and the ventilation path 28a are shifted in the circumferential direction for the sake of clarity, but they are actually at the same position in the circumferential direction.

FIG. 5 is an enlarged view of the axial type hydrostatic composite bearings 8 and 9. The pair of bearings 8, 9 are opposed to both surfaces of a flange 4 a provided on the
And constitutes one double-sided axial-type hydrostatic composite bearing 30. The hydrostatic composite bearings 8 and 9 on both sides have the same configuration. These hydrostatic magnetic composite bearings 8 and 9 are respectively composed of hydrostatic gas bearings 8.
A, 9A and magnetic bearings 8B, 9B are combined. In this embodiment, the throttles 34a of the hydrostatic gas bearings 8A and 9A are provided on the electromagnet cores 33 of the magnetic bearings 8B and 9B, so that the bearing components are shared and a part of the bearing surface overlaps in the axial direction. It is like that. The core 33 has a C-shaped longitudinal section so that an opening 33d is formed on the surface facing the spindle flange 4a, and the coil 35 is accommodated therein. The opening 33d is filled with a non-magnetic material. The core 33 has an assembly configuration of an inner core portion 33a and an outer core portion 33b having an L-shaped cross section in the illustrated example, but may be an integral structure. The spacer 29 is adjacent to the core 33 in the axial direction.

Axial-type hydrostatic gas bearings 8A, 9A
Are hydrostatic bearing surfaces 8Aa, 9A formed on the side surface of the core 33 and forming a bearing gap d2 with the spindle flange 4a.
a, and hydrostatic bearing surfaces 8Aa, 9Aa provided on the core 33.
And a stop 34a which is open to the outside. The aperture 34a is
It is provided at the tip of an air supply hole 34 opened on the outer diameter side surface of the core 33.

The axial type magnetic bearings 8B and 9B have displacement detecting means 38 for detecting displacement of a magnetic gap between the spindle flange 4a and the core 33. The displacement detecting means 38 may directly detect the displacement amount, but in this example, by detecting the static pressure in the static pressure bearing gap d2, the detected pressure value is converted into the displacement amount. To detect the displacement of the magnetic gap. More specifically, the displacement detection means 38 includes a pressure detection air passage 38a having a distal end opened in the static pressure bearing gap d2, and a sensor 38b (FIG. 2) communicating with the air passage 38a.

In the air supply holes 24, 34 of the static pressure gas bearings 6A to 9A in each of the static pressure magnetic composite bearings 6 to 9, as shown in FIG. Supplies compressed air or other compressed gas.

The control system will be described with reference to FIG. The spindle controller 3 is a means for controlling the entire spindle device 1, and includes a microcomputer, electronic components,
It is composed of electric parts and the like. Spindle controller 3
Are the hydrostatic gas bearings 6A to 9A of the hydrostatic magnetic composite bearings 6 to 9.
And a function of controlling the magnetic bearings 6B to 9B as basic functions. The spindle controller 3 has the displacement sensor amplifier 31 for amplifying the detection value of the displacement detection means 28 as described above, and the magnetic force control means 33 controls each of the magnetic bearings 6B to 9B according to the output value of the displacement sensor amplifier 31. Perform magnetic force control. The magnetic force control means 33 includes a power supply, a power circuit, and means for controlling the power of the power circuit. Although one displacement sensor amplifier 31 and one magnetic force control means 33 are shown in FIG. 1 as representatives, they are provided for the individual magnetic bearings 6B to 9B. The processing machine control device 14 controls the processing machine 1 equipped with the spindle device 1.
3 and is composed of a computer-type numerical controller or the like. The processing machine 13 is a machine that performs cutting or grinding with the tool 11 mounted on the main shaft 4 of the spindle device 1, and includes the spindle device 1 and a work (not shown).
And a feeder (not shown) for relatively moving the feeder. The processing machine 13 is installed, for example, on the feed table. The processing machine control device 14 has a function of controlling the spindle drive source 10 of the processing machine 13 and the feed table, and is controlled according to a processing program (not shown).

In this embodiment, the spindle controller 3 is provided with a signal processing means 32 and a natural frequency detecting means 34, and the processing machine control unit 14 is provided with a vibration-compatible processing condition changing means 35 and a rotational speed / tool blade number matching unit. Handling means 36
Is provided. Which of the means 32 to 36 is provided in the spindle controller 3 or the processing machine control device 14 is not limited to the illustrated example, and can be arbitrarily selected.

The signal processing means 32 is means for performing frequency analysis of the vibration of the main shaft 4 from the output of the displacement detection means 28, specifically, the output of the displacement sensor amplifier 31, and as a result of the analysis, The amplitude is determined. The natural frequency detecting means 34 is a means for obtaining the natural frequency when the tool 11 of the main shaft 4 is mounted from the frequency analysis result of the signal processing means 32. Obtaining the natural frequency from the frequency analysis result is obtained from the frequency component whose amplitude increases. The timing for starting the detection process by the natural frequency detection means 34 is as follows.
After the tool is mounted, a predetermined process (for example, an advance command of the feed plate) performed by the processing machine control device 14 may be performed before the processing is started, or a processing program (not shown) executed by the processing machine control device 14 ) May be set so as to respond to a predetermined command described in (1). Further, the natural frequency detecting means 34 may start detection in response to input of a detection command from an operation panel (not shown) or the like.

The coping means 36 when the number of rotations and the number of tool blades match is
According to the detection result of the natural frequency detecting means 34, it is a means for performing a predetermined process when an integer multiple of (number of rotations) × (number of tool blades) matches the above natural frequency. The predetermined process includes a process of generating a warning and a process of slightly shifting the spindle speed. The means for generating the above-mentioned warning in the coping means 36 when the number of revolutions and the number of tool blades coincide is the alarm generating section 36a, and the means for performing processing for slightly deviating the spindle revolution number is the revolution number changing section 36b. The above-mentioned number of tool blades is generally the number of blades divided into a plurality of (for example, about 2 to 4) in the rotation direction in, for example, a drill or an end mill. is there.

The vibration-corresponding machining condition changing means 35 monitors the frequency analysis result of the signal processing means 32, and when a chatter vibration is detected which coincides with the set natural frequency or an integral multiple thereof, the processing machine control device. This is a means for changing the setting of the processing conditions in 14. The processing condition to be changed may be, for example, the number of revolutions of the main shaft 4, the feed speed of the spindle device 1, the type of the tool 11 to be used, and the like.

According to the spindle device 1 of this configuration, the natural frequency of the spindle 4 in the tool mounted state is obtained by the natural frequency detecting means 34 from the frequency analysis result of the signal processing means 32. According to the detection result of the natural frequency detecting means, if an integral multiple of (number of rotations) × (number of tool blades) matches the natural frequency, if the number of rotations matches the number of tool blades, coping means 36
Performs processing such as generation of a warning and change of the number of revolutions. For this reason, it is possible to prevent cutting defects by avoiding the resonance conditions before machining. In the spindle device 1 provided with the hydrostatic and magnetic composite bearings 6 to 9, the displacement detection means 28 of the main shaft 4 is built in, and the control microcomputer is mounted on the spindle controller 3. It is easy to ask. Therefore, as described above, at the stage when the tool 11 is mounted, the process of measuring the natural frequency, generating a warning, and changing the rotation speed is performed by:
It can be realized with a simple configuration.

If a chatter vibration is detected during the processing of the processing machine 13 which coincides with the set natural frequency or an integral multiple of the natural frequency, the processing of the vibration-compatible processing condition changing means 35 causes the control device of the processing machine 13 to operate. The setting of the processing conditions in 14 is changed. For this reason, it is possible to prevent cutting defects as early as possible by avoiding resonance conditions. The natural frequency in this case is obtained in advance by an experiment or the like, and is set in the vibration-compatible processing condition changing means 35 in advance.

In the above embodiment, the displacement detecting means 2
Although a means for detecting pressure is used as 8, a displacement sensor such as a magnetic sensor for detecting the displacement itself may be used as the displacement detecting means 28.

FIG. 6 shows another embodiment of the present invention. In this embodiment, magnetic bearings 46 to 49 are provided instead of the hydrostatic magnetic composite bearings 6 to 9 in the embodiment of FIG. Other configurations are the same as the embodiment of FIG. Thus, even when the magnetic bearings 46 to 49 are provided,
By providing the signal processing means 32, the natural frequency detecting means 34, the vibration-corresponding machining condition changing means 35, and the coping means 36 when the number of revolutions and the number of tool blades coincide, the machining conditions can be avoided before machining to prevent cutting defects. This can be prevented beforehand, and when a resonance condition occurs during machining, the resonance condition can be avoided to prevent cutting defects.

Next, a method of correcting a field balance in the non-contact bearing spindle device will be described. When the main shaft is balanced, usually an acceleration pickup or the like is attached to the housing to correct imbalance on one or two surfaces. However, when a high-precision balance adjustment is required, such as in a hydrostatic gas bearing or a hydrostatic magnetic composite bearing spindle device, a sufficient balance adjustment cannot be performed by the above method. Even if vibrations in the housing are measured, the sensitivity is low, and in the high-speed rotation specification, three to four surfaces are corrected in consideration of bending in a high frequency range, and thus the response is insufficient. Therefore, the balance is corrected by measuring the deflection of the main shaft with a high-accuracy, high-response sensor such as a capacitance sensor. However, since the vibration includes a main shaft shape error, it is necessary to subtract the error. Also, it is not easy to measure the run-out at the bearing.

Therefore, the field balance correction method of this proposed example is to perform a frequency analysis process of the spindle displacement signal in the field balance correction in the hydrostatic gas bearing spindle device or the hydrostatic magnetic composite bearing spindle device.
This is a method of extracting only the rotation synchronization component. As the displacement detecting means for detecting the displacement of the main shaft, a pressure sensor built in the bearing is used.

A hydrostatic gas bearing spindle device or a hydrostatic magnetic composite bearing spindle device provided with a displacement detecting means for measuring the gas pressure of the bearing portion and converting the gas pressure into a main shaft displacement can measure the deflection of the main shaft of the bearing with a submicron resolution. Can be measured. Furthermore, by analyzing the frequency of this signal, only the rotation synchronization component from which the shape error (initial shake) and noise have been removed is extracted, and the phase from the rotation direction origin is obtained at the same time.
Highly accurate shake detection can be performed. At low and high rotation speeds, test weights are attached to the four points on the spindle, and 4
By performing the surface correction, the run-out in the entire rotation region can be minimized. This field balance correction method is applied to, for example, the embodiment shown in FIGS. As means for detecting the displacement of the main shaft 4, the displacement detecting means 28 and 38 in the embodiment are used, and the signal processing means 32 in FIG. 1 can be used for frequency analysis.

A specific example of the field balance correction method is as follows.
This will be described with reference to FIGS. As shown in FIG. 7, in the case of four-plane correction, a set screw (not shown) is attached as a test weight to the correction surface of the main shaft 4. The measuring points of the displacement of the main shaft 4 are the measuring points (1) and (4) in FIG. 7 or the measuring points (2) and (5) in FIG. Measurement points (2) and (5) are bearing surfaces. In the case of three-sided correction, the corrected side shall be or. The measurement points can be measured points (1), (4), (6) or measurement points (2), (5), (6) or measurement points (1), (3), (4) or measurement points (1 ), (2), (5). Measuring point to be the bearing surface (2),
A pressure sensor is used for (5), and the other measurement points (1), (3),
For (4) and (6), a capacitance sensor or the like is used. In the case of these four-sided or three-sided correction, it is preferable that two-sided correction is performed by a general-purpose dynamic balance tester before the correction.

The case of four-plane correction will be described. In this case, the following (Process 1) to (Process 5) are performed. (Process 1) The main shaft 4 is rotated at a low speed (several tens of Hz) without any addition, and the roundness error at each measurement point (two points) is measured. FIG. 8A shows one cycle of the rotation pulse signal with one pulse falling, and FIG. 8B is an explanatory diagram of measured values.
N is 360 or more, and the [floor (N / 360 · i)]-th value is a roundness error ε (θ _i ) at i [deg]. Repeat several times to average.

(Process 2) The initial imbalance is measured while rotating at a low speed (200 to 300 Hz). FIG. 9 (A)
Is a rotation pulse signal, showing one cycle between pulse falling,
FIG. 3B shows the unbalance amount. Since the measured value includes a roundness error, this value is subtracted. Tn is the number of timer clocks (n _T ) between rotation pulses. Assuming that the number of timer clocks from the fall of the rotation pulse to the A / D sampling is n _S , the initial unbalance amount y _i obtained by subtracting the roundness error at i [deg] is y _i = x _i −ε (θ _i ) θ _{i = floor (360 · n S} / n T) to y _i ~y ₄₀₉₆ by frequency analysis, real part of the rotational frequency component, determine the imaginary part (gain, phase)

[0033]

(Equation 1)

(Process 3) Turn to high speed (1 KHz) and measure the initial imbalance as in (Process 2).

[0035]

(Equation 2)

(Process 4) A test weight (set screw) is attached to the correction surface 1 ().

[0037]

(Equation 3)

(Process 5) In the same manner as in Process 4, each of the corrected surfaces

[0039]

(Equation 4)

[0040]

[Table 1]

[0041]

(Equation 5)

[0042]

(Equation 6)

[0043]

According to a first aspect of the present invention, there is provided a non-contact bearing spindle device having a main shaft supported by a hydrostatic magnetic composite bearing and having displacement detecting means for detecting a displacement of the main shaft. Signal processing means for frequency-analyzing the output signal of the displacement detecting means; and natural frequency detecting means for obtaining the natural frequency of the spindle when the tool is mounted from the frequency analysis result of the signal processing means. (Rotation speed) x
Since a countermeasure is provided when the number of rotations and the number of tool blades match to perform a predetermined process when an integer multiple of (number of tool blades) matches the above natural frequency, cutting conditions can be avoided by avoiding resonance conditions before machining. It can be prevented beforehand. A non-contact bearing spindle device according to a second aspect of the present invention includes a static pressure magnetic composite bearing in which a magnetic bearing and a static pressure gas bearing are combined, the main shaft being supported, and a displacement detecting means for detecting a displacement of the main shaft. In the non-contact bearing spindle device, signal processing means for frequency-analyzing the output signal of the displacement detecting means is provided, and the frequency analysis of the signal processing means is performed during processing of a processing machine equipped with the hydrostatic composite bearing spindle device. The result is monitored, and when chatter vibration is detected that matches the set natural frequency or an integral multiple thereof, the vibration-compatible processing condition changing means for changing the setting of the processing condition in the control device of the processing machine is provided. When a resonance condition occurs during processing, it is possible to avoid the resonance condition and prevent cutting defects from occurring. These first
Alternatively, in the second invention, even when a magnetic bearing is provided instead of the hydrostatic magnetic composite bearing, resonance conditions can be avoided before machining and cutting defects can be prevented beforehand, or resonance conditions can be reduced during machining. When it occurs, it is possible to avoid the resonance condition and to prevent cutting defects before it occurs.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a conceptual configuration of a non-contact bearing spindle device according to an embodiment of the present invention.

FIG. 2 is a vertical sectional side view of the spindle device main body.

FIG. 3 is a cross-sectional front view of the spindle device main body.

FIG. 4 is an enlarged sectional view of a radial type hydrostatic composite bearing.

FIG. 5 is an enlarged sectional view of an axial type hydrostatic magnetic bearing.

FIG. 6 is a block diagram showing a conceptual configuration of a non-contact bearing spindle device according to another embodiment of the present invention.

FIG. 7 is an explanatory diagram of a correction surface of a spindle and a measurement point at the time of field balun correction.

FIG. 8 is an explanatory diagram of a measured value of a roundness error.

FIG. 9 is an explanatory diagram of a measured value of an unbalance amount.

[Description of Signs] 1 ... Spindle device 2 ... Spindle device main body 3 ... Spindle controller 4 ... Main shaft 5 ... Housing 6-9 ... Static pressure magnetic composite bearing 6A-9A ... Static pressure gas bearing 6B-9B ... Magnetic bearing 10 ... Spindle Driving source 14 Processing machine control device 28 Displacement detection means 32 Signal processing means 33 Magnetic force control means 34 Natural frequency detection means 35 Frequency-dependent machining condition changing means 36 When the number of rotations and the number of tool blades match Coping measures

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23Q 11/00 B23Q 1/26 Z F16C 32/04 1/08 Z 1/26 EF term (Reference) 3C011 AA04 3C045 FD15 FD16 3C048 BC03 CC00 CC07 3J102 AA01 AA02 BA03 BA19 CA02 CA22 DA02 DA03 DA09 DB05 DB10 DB11 DB16 DB32 DB37 EA02 EA06 EA13 GA07

Claims (4)

[Claims] In a non-contact bearing spindle device, a main shaft is supported by a hydrostatic magnetic composite bearing in which a magnetic bearing and a hydrostatic gas bearing are compounded, and a displacement detecting means for detecting a displacement of the main shaft is provided. Signal processing means for frequency-analyzing an output signal of the detection means; natural frequency detection means for obtaining a natural frequency of the spindle when the tool is mounted from the frequency analysis result of the signal processing means; According to the detection result of the means, a countermeasure means is provided for performing a predetermined process when the integral multiple of (number of rotations) × (number of tool blades) coincides with the above natural frequency, and performing a predetermined processing when the number of rotations / tool blades coincide. Non-contact bearing spindle device characterized by the above-mentioned. 2. The coping means when the number of revolutions and the number of tool blades match is equal to the natural frequency when an integral multiple of (number of revolutions) × (number of tool blades) matches the natural frequency. 2. The non-contact bearing spindle device according to claim 1, wherein at least one of a process for generating the rotation and a process for slightly shifting the spindle rotation speed is performed. 3. A non-contact bearing spindle device in which a main shaft is supported by a hydrostatic magnetic composite bearing in which a magnetic bearing and a hydrostatic gas bearing are compounded and a displacement detecting means for detecting a displacement of the main shaft is provided. A signal processing means for frequency-analyzing the output signal of the detection means is provided. During processing of a processing machine equipped with the hydrostatic magnetic composite bearing spindle device, the frequency analysis result of the signal processing means is monitored, and the set natural vibration is set. A non-contact bearing spindle device provided with a vibration-corresponding processing condition changing means for changing a setting of a processing condition in a control device of the processing machine when a chatter vibration is detected which coincides with the number or an integral multiple thereof. 4. The non-contact bearing spindle device according to claim 1, wherein a magnetic bearing is provided instead of the hydrostatic magnetic composite bearing.