JP2008298224A - Bearing structure and laser beam machine using the bearing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing structure, and a laser beam machine using the bearing structure capable of reducing the axial swing of a rotary shaft. <P>SOLUTION: This bearing structure has a noncontact type radial magnetic bearing 54 for regulating displacement in the radial direction of a freely rotating shaft 52. A bearing 55 capable of regulating displacement in both the radial direction and the thrust direction is arranged at an interval with the radial magnetic bearing 54 in the longitudinal direction of the shaft 52. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bearing structure for reducing shaft runout of a rotary shaft, and a laser processing apparatus using the bearing structure.

  Conventionally, a bearing structure using a non-contact type magnetic bearing using an electromagnet or a permanent magnet has been used in various devices. For example, one using this magnetic bearing for a turbo molecular pump is known (for example, see Patent Document 1). This turbo molecular pump includes a high-frequency motor for rotating the drive shaft, and operates the drive shaft at an ultrahigh speed of several tens of thousands to 100,000 rpm. This high-frequency motor is provided with two radial magnetic bearings and one thrust magnetic bearing along the extending direction of the drive shaft.

  In addition, one using a magnetic bearing as a bearing of a flat motor is known (for example, see Patent Document 2). This flat motor is provided with a radial magnetic bearing that supports the radial direction without contact and a thrust bearing that supports the thrust direction with one-point pressing contact.

Furthermore, a technique using these magnetic bearing techniques for an optical deflector using a polygon mirror is also known (see, for example, Patent Document 3). This optical deflector has a mechanism in which a rotor of a motor is integrated with a sheath-like rotating body that covers a cylindrical fixed shaft, and a herringbone groove provided on the cylindrical fixed shaft. It functions in the same way as a radial bearing so that stable high-speed rotation without contact can be obtained with dynamic pressure air. Moreover, the permanent magnet is arrange | positioned so that it may respectively repel at the cylindrical top part of the top top rotary body of a fixed shaft, and the floating performance of the thrust direction is acquired.
JP 2000-213539 A JP 2006-217744 A JP-A-63-259510

  However, as in Patent Document 1 described above, when the motor is relatively small and has two radial bearings and one thrust bearing in the axial direction of the drive shaft, the outer shape in the axial direction becomes large. End up. Furthermore, since it is necessary to provide a displacement sensor for suppressing shaft runout at the upper and lower portions of the radial magnetic bearing, it has been difficult to shorten the axial dimension and reduce the outer dimension. In addition, a 5-axis controller is required for controlling the shaft runout, which complicates the control system and increases the cost.

  Further, in the technique of Patent Document 2, there is no problem when used for a device such as a blower fan in which shaft shake is not regarded as important. For example, an optical device in which shaft shake is regarded as important (for example, Patent Document 3) The bearing accuracy required for use in (1) cannot be expected.

  Further, as in Patent Document 3, in an apparatus that applies laser beam deflection or scanning, such as an optical deflector or a polygon mirror, the working distances of the light source and the mirror, or the mirror and the document, such as a laser printer, are particularly great. Is relatively short, the radial stiffness by the dynamic pressure bearing and the thrust stiffness by the permanent magnet are ensured, and the influence of the shaft runout is relatively small. However, for example, remote laser welding, an optical modeling system with a relatively long working distance, and a drawing system that requires high drawing accuracy (except for those that are drawn to recognize characters such as mere manufacturing date) In equipment, slight axial displacement also affects machining accuracy. In such a device, since the swing of the rotating shaft cannot be positively controlled with the bearing structure as in Patent Document 3, it is difficult to obtain higher machining accuracy.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a bearing structure capable of reducing the axial runout of a rotating shaft and a laser processing apparatus using the same.

In the present invention, the bearing structure includes a non-contact type radial magnetic bearing that regulates the displacement of the rotatable shaft in the radial direction, and is spaced apart from the radial magnetic bearing in the longitudinal direction of the shaft. And a bearing capable of regulating displacement in both the thrust direction.
According to this structure, since the rotatable shaft can be supported by the radial magnetic bearing and the bearing, the shaft runout of the rotating shaft can be reduced without complicated control.

The bearing may be disposed at one end of the shaft in the longitudinal direction.
According to this structure, the structure which controls the displacement of both a radial direction and a thrust direction can be obtained easily.

Furthermore, the said bearing may be formed in the hollow shape which covers the side edge part and end surface of the said axis | shaft.
According to this configuration, since the shaft end portion can be supported inside the hollow shape, it is possible to more firmly support the one end portion of the rotating shaft than in the conventional case.

Further, a hemispherical hemispherical portion may be formed at one end of the shaft, and a contact surface in contact with the hemispherical portion may be formed on the bearing.
According to this configuration, displacement in both the thrust direction and the radial direction can be restricted with a simple structure.

Further, a hemispherical hemispherical portion may be formed at one end of the shaft, and the hemispherical portion may be magnetized while the bearing is magnetized to a polarity repelling the hemispherical portion.
According to this structure, since the bearing can be configured in a non-contact manner, the frictional resistance is reduced and the power consumption can be reduced.

Moreover, you may make it press the one end part of the said shaft toward the said bearing.
According to this configuration, the shaft end portion is unlikely to come out of the groove portion, so that the bearing can be more reliably supported.

Furthermore, a motor rotor may be integrated with the shaft, and a motor unit may be disposed between the radial magnetic bearing and the bearing.
According to this configuration, the motor can be further reduced in size. Moreover, since the space | interval of a magnetic bearing and a bearing is taken long, it can support firmly with a small magnetic force. Therefore, the magnetic bearing can be easily controlled with a small current.

On the other hand, a motor having a rotatable shaft and a non-contact radial magnetic bearing for restricting displacement of the shaft in the radial direction is provided, and a scanner mirror for deflecting laser light is attached to the shaft end of the motor, A laser processing device that rotates a motor to irradiate the workpiece with the laser beam, and is capable of regulating displacement in both the radial direction and the thrust direction with a gap from the radial magnetic bearing in the longitudinal direction of the shaft. A special bearing is provided.
According to this configuration, the workpiece can be irradiated with laser light with high accuracy.

  According to the present invention, there is provided a bearing structure including a non-contact type radial magnetic bearing that regulates a displacement of a rotatable shaft in a radial direction, and is spaced apart from the radial magnetic bearing in a longitudinal direction of the shaft. Since a bearing capable of restricting displacement in both the radial direction and the thrust direction is provided, compared to the case where two radial magnetic bearings and one thrust magnetic bearing are combined, the bearing structure is configured. Does not require a large space. Further, by suppressing the displacement of the shaft with the bearing, the shaft runout in the radial direction at the radial magnetic bearing portion can be reduced. Thereby, for example, even when a displacement sensor is used to measure the displacement of the radial magnetic bearing and control (feedback control) for adjusting the displacement is performed, the adjustment width (amount) is reduced and the adjustment is easily performed. be able to. Therefore, bearing accuracy can be increased.

  In addition, according to the present invention, a motor having a rotatable shaft and a non-contact radial magnetic bearing that restricts displacement of the shaft in the radial direction is provided, and the laser beam is deflected at the shaft end of the motor. A laser processing apparatus that attaches a scanner mirror and rotates the motor to irradiate the workpiece with the laser beam. The laser processing apparatus is spaced apart from the radial magnetic bearing in the longitudinal direction of the shaft, and has a radial direction and a thrust direction. Since the bearing capable of regulating both displacements is provided, the scanner mirror can be rotated with high accuracy by suppressing the shaft runout of the motor shaft to be small. Accordingly, the workpiece can be irradiated with laser light with high accuracy, and the workpiece that can be processed with the laser processing apparatus can be processed with high accuracy. Further, since the bearing can be configured in a small space, the outer shape of the motor can be reduced.

FIG. 1 is a diagram illustrating a configuration of a laser processing apparatus 1 according to the present embodiment. FIG. 2 is an enlarged view showing a state in which the scanner mirror 40A is attached to the motor 41A shown in FIG.
The laser processing apparatus 1 includes a laser oscillator 2, a scanner optical apparatus 3, and a pair of mirrors 4A and 4B, which are optical elements that guide the laser light 45 emitted from the laser oscillator 2 to the scanner optical apparatus 3. These are placed and fixed on a plate-like stone surface plate 5.

The laser oscillator 2 oscillates a laser beam 45 having a wavelength corresponding to the laser medium. The laser oscillator 2 includes a rectangular parallelepiped oscillator main body 20 including a laser resonator (not shown), and a laser emission port 21 opened at a tip portion 20A of the oscillator main body 20.
Examples of the laser oscillator 2 include a solid laser oscillator, a liquid laser oscillator, a gas laser oscillator, a semiconductor laser oscillator, and a free electron laser oscillator.

  An XYZ axis stage 22 is provided on the lower side of the oscillator body 20 on the front end portion 20A side and the rear end portion 20B side. The XYZ axis stage 22 is fixed to the stone surface plate 5 with screws. In general, the stone surface plate 5 has a very high planar accuracy, so that the optical axis of the laser oscillator 2 can be finely adjusted by adjusting the XYZ axis stage 22. Further, since the stone surface plate 5 has a very low thermal conductivity, even if the laser oscillator 2 generates heat, it is possible to minimize the thermal effect on other optical elements.

  The scanner optical device 3 deflects the laser light 45, an AOM (acousto-optic modulation element) 30 that modulates the intensity of the laser light 45 output from the laser oscillator 2, a dynamic focus lens 31 that adjusts the focus of the laser light 45, and the laser light 45. The optical element is mounted on a height adjusting stage 33 extending linearly for aligning the optical axis with the mirror 4B. This height adjustment stage 33 is provided between the dynamic focus lens 31 and the scanner head 32, and forms a light output from the dynamic focus lens 31 and inputs it to the scanner head 32 as a lens 34 as an optical element. A pair of lenses 35A and 35B as optical elements for shaping the laser light 45 incident on the AOM 30 are attached.

The scanner head 32 includes a box-shaped housing 42 having an open bottom surface, and motors 41A and 41B are provided on the top and sides of the housing 42.
A rotation shaft 52 (drive shaft) of the motor 41A extends in the left-right direction in FIG. 1, and a scanner mirror 40A for deflecting the laser beam 45 is attached to the tip of the rotation shaft 52 (drive shaft). The scanner mirror 40A can change the angle of the mirror by appropriately rotating the rotating shaft 52 of the motor 41A in the R direction (see FIG. 2).
On the other hand, the drive shaft of the motor 41B extends in the vertical direction in FIG. 1, and at its tip, a scanner mirror that deflects the laser light 45 in a direction at a predetermined angle with respect to the deflection direction of the scanner mirror 40A. 40B is attached. The scanner mirror 40B can change the angle of the mirror by rotating the drive shaft of the motor 41B.
These scanner mirrors 40A and 40B are disposed inside the casing 42, and an inlet (not shown) for guiding the laser beam 45 is formed in the side of the casing 42.

  The height adjustment stage 33 where the casing 42 is disposed is provided with an emission port 43 that emits the light deflected by the scanner mirrors 40A and 40B. Thus, the scanner head 32, the lens 34, and the emission port 43 constitute a deflection module that deflects the laser light 45 output from the laser oscillator 2. The laser beam 45 deflected by this deflection module passes through the emission port 43 and is directed to the working area 46 (workpiece, see FIG. 2).

  When the laser beam 45 is deflected by the scanner head 32 and the object is scanned with the laser beam 45, the dynamic focus lens 31 makes the irradiation spot diameter of the laser beam 45 on the scanning surface of the object substantially constant regardless of the irradiation position. The focal length of the laser beam 45 is varied so as to be maintained. The dynamic focus lens 31 is driven in the optical axis direction by a motor (not shown) to vary the focal length of the laser light 45. Further, when the object is a three-dimensional scanning surface, the dynamic focus lens 31 is controlled by the control unit 6 so that the object is focused on the scanning surface. The motor (not shown) and the motors 41A and 41B of the scanner head 32 are controlled by the control unit 6. The control unit 6 controls the motor of the dynamic focus lens 31 and the motors 41A and 41B of the scanner head 32 in synchronization with each other in order to adjust the focal length based on the irradiation position of the laser beam 45 on the scanning surface. Instead of the dynamic focus lens 31, an fθ lens may be used as the focal length adjustment unit.

As described above, the AOM 30 modulates the intensity of the continuous wave laser beam or pulse laser beam output from the laser oscillator 2 and is controlled by the control unit 6. The intensity of the laser beam 45 is adjusted according to the scanning speed of the laser beam 45 defined by the drive amount of the motors 41A and 41B of the scanner head 32 so that the processing degree such as the laser processing depth on the scanning surface of the scanner head 32 is always kept constant. Variable. That is, when the scanning speed of the laser beam 45 is high, the control unit 6 increases the intensity of the laser beam 45 or the density of the laser beam 45 because the energy per unit area decreases. If the laser beam 45 is slow, control is performed to reduce the intensity of the laser beam 45 or the density of the laser beam 45, and control to maintain the energy per unit area when the laser beam 45 is scanned substantially constant.
The density of the laser beam 45 is defined by the number of pulses per unit time of the pulse laser beam, and the energy of the laser beam 45 per unit area can be varied by varying the laser beam density.

The motors 41A and 41B of the scanner head 32 are provided with encoders 44A and 44B that output digital pulse signals SA and SB having the number of pulses corresponding to the rotation amounts of the scanner mirrors 40A and 40B to the control unit 6, respectively.
The control unit 6 counts the digital pulse signals SA and SB, specifies the rotation amounts of the scanner mirrors 40A and 40B based on the count values, and specifies the XY coordinate values of the current laser light irradiation position.
Further, the control unit 6 performs negative feedback control by outputting to each of the motors 41A and 41B so as to cancel out the deviation between the target value of the laser light irradiation position and the current XY coordinate value. Thus, in the control unit 6, the encoders 44A and 44B that output the digital pulse signals SA and SB and the control unit 6 constitute a closed loop control system, and the motors 41A and 41B are driven with high accuracy. Will be compensated for. Thereby, high-precision motor control, that is, high-precision irradiation position control on the processed surface of the workpiece is realized.

  Examples of such a laser processing apparatus 1 include, for example, remote laser welding, an optical modeling system with a relatively long working distance, a drawing system that requires high drawing accuracy (drawing to recognize characters such as mere manufacturing date) Can be used).

  FIG. 3 is a sectional view showing the motor 41A shown in FIG. 1 as a single unit. FIG. 4 is an enlarged sectional view of the bearing shown in FIG. In the following description, the motor 41A will be described, but the motor 41B is the same as the structure of the motor 41A, and the description thereof is omitted. In FIG. 3, the encoder 44A attached to the rear portion of the motor 41A is omitted. Furthermore, in the following description, the up and down and left and right directions are directions when FIG. 3 is viewed from the front.

  The motor 41A includes a bottomed cylindrical casing 51 that constitutes an outer portion of the motor 41A, a rotating shaft 52 that extends along the central axis X of the casing 51, and a motor that drives the rotating shaft 52. A portion 53, a radial magnetic bearing 54 disposed on the upper side of the motor portion 53, and a bearing 55 that supports the lower end portion of the rotating shaft 52 are provided. That is, the motor unit 53 is disposed between the radial magnetic bearing 54 and the bearing 55 as shown in FIG.

  As shown in FIG. 3, the rotating shaft 52 extends in the vertical direction along the axis X, and an upper end portion 52 a thereof protrudes from the upper opening 51 a of the housing portion 51. The rotating shaft 52 is formed using a magnetic material (for example, iron). The above-described scanner mirror 40A is attached to the upper end portion 52a of the rotating shaft 52. On the other hand, the lower end portion 52b of the rotating shaft 52 has a hemispherical shape as shown in FIGS. 3 and 4 and is supported in a manner to contact a bearing 55 described later in detail.

  The motor unit 53 includes a stator 56 (stator) fixed to the housing unit 51, and generates a fluctuating magnetic field by supplying a current to the winding 56 a of the stator 56. On the other hand, a rotor 52d (rotor) is integrally provided on the rotating shaft 52 described above at a position corresponding to the stator 56, and the rotating shaft 52 is rotated by the stator 56 and the rotor 52d. It will be.

The radial magnetic bearing 54 includes a yoke 57 fixed to the housing portion 51. The yoke 57 is arranged in a ring shape continuously in the circumferential direction of the rotating shaft 52, and a predetermined gap is provided between the outer peripheral surface of the rotating shaft 52 and the inner peripheral surface of the yoke 57. The yoke 57 is provided with a plurality of magnetic field generating coils 58 at intervals in the circumferential direction. Electric power is individually supplied to the magnetic field generating coil 58 to generate a magnetic force in each part of the yoke 57 in the circumferential direction, and the rotating shaft 52 is attracted from the outer periphery of the rotating shaft 52 to support the rotating shaft 52 in a non-contact manner. It is supposed to be. This non-contact support can prevent the non-contact support portion of the rotating shaft 52 from being worn.
The electric power supplied to each magnetic field generating coil 58 is controlled by a control system (not shown), and when an axial runout occurs in the rotating shaft 52, the magnetic force in each part of the entire circumference of the rotating shaft 52 is adjusted. Regulate runout.

  In addition, by attaching a permanent magnet (not shown) on the outer peripheral surface of the rotating shaft 52 and facing the inside of the yoke 57, and making the polarity generated in the yoke 57 the same as the polarity of this permanent magnet, The yoke 57 and the rotating shaft 52 may be repelled to support the rotating shaft 52 in a non-contact manner. Even in this structure, the non-contact support can prevent the non-contact support portion of the rotating shaft 52 from being worn.

  A displacement sensor 59 is provided on the upper side of the radial magnetic bearing 54. The displacement sensor 59 is attached to the casing 51 and detects the displacement of the rotating shaft 52 (amount of shaft runout). The displacement sensor 59 is connected to a control system (not shown) and transmits a displacement signal of the rotating shaft 52 to the control system. This displacement signal is used for feedback control to increase or decrease the magnetic force of the yoke 57, and the control system adjusts the electric power supplied to the magnetic field generating coil of the radial magnetic bearing 54 based on the displacement signal. Thereby, the shaft runout of the rotating shaft 52 can be reduced, and the rotating shaft 52 can be supported more stably.

As shown in FIGS. 3 and 4, the bearing 55 has a structure in which the lower end portion 52 b of the rotating shaft 52 can contact. More specifically, a hemispherical hemispherical portion 52c is formed at the lower end 52b, while the bearing 55 is a recess that covers the side edge S and the lower end surface T (see FIG. 4) of the hemispherical portion 52c. It is formed in a shape, and has a hemispherical contact surface 55a that contacts the hemispherical portion 52c on the surface. The bearing 55 restricts displacement of the rotating shaft 52 in the radial direction at a portion covering the side edge portion S of the hemispherical portion 52c and restricts displacement in the thrust direction at a portion covering the lower end surface T of the hemispherical portion 52c. Thus, the displacement in both the radial direction and the thrust direction can be supported. As shown in FIG. 4, it is preferable that the hemispherical surface 52c and the contact surface 55a of the bearing 55 are in contact with each other in a range that forms an angle of 90 degrees or more equally from the radial center Q of the hemispherical portion 52c. Thus, if the contact is made at an angle of 90 degrees or more, the force acting in the horizontal direction is larger than the force acting in the vertical direction in the hemispherical portion 52c, and the function as a radial bearing can be further improved.
The hemispherical surface described here does not strictly mean a half shape of a sphere, and is not limited to a complete hemisphere as long as it can support both the thrust direction and the radial direction. That is, it refers to a shape having a spherical surface, or a spherical surface formed with a radius having substantially the same dimension, and for example, a spherical shape as a whole (see FIG. 6B) may be included.

  The rotating shaft 52 is given a pressing force F toward the bearing 55 by permanent magnets 98 and 99 arranged in parallel along the extending direction of the rotating shaft 52. That is, the permanent magnet 98 fixed to the casing 51 and the permanent magnet 99 fixed to the rotating shaft 52 have the same magnetism on the opposing surfaces, and the repulsive force of these permanent magnets 98 and 99 is the same. Therefore, a pressing force F is generated. Therefore, the hemispherical surface portion 52 c of the rotating shaft 52 is always pressed against the contact surface 55 a of the bearing 55 by the pressing force F. Accordingly, since the shaft end portion is difficult to be removed from the groove portion, the fixed position of the shaft end does not change.

  A touch-down bearing 60 (auxiliary bearing) is provided in the upper opening 51a of the casing 51 for an abnormality or a power failure in the control system of the radial magnetic bearing 54. The touchdown bearing 60 is formed using a non-magnetic material (for example, aluminum) so as not to be affected by the magnetic field of the radial magnetic bearing 54, and the rotating shaft 52 is attached to the touchdown bearing 60 in an emergency. It comes to contact. The touchdown bearing 60 plays a role of protecting the permanent magnets 98 and 99 for applying the pressing force F. Even when a large thrust load is applied to the rotary shaft 52, the touchdown bearing 60 is permanent. Before the magnets 98 and 99 come into contact with each other, the step portion of the rotating shaft 52 comes into contact with the touch-down bearing 60. Further, even when the rotating shaft 52 moves in the radial direction, the touch-down bearing before the rotor 52d and the stator 56 of the motor 41A and the rotating shaft 52 and the yoke 57 of the radial magnetic bearing 54 come into contact with each other. By contacting 60, each part of the motor and the magnetic bearing is prevented from being damaged.

  Note that the touchdown bearing 60 may be composed of an electromagnet or a permanent magnet so that the displacement in the radial direction and the thrust direction can be supported. In this case, the outer peripheral surface of the rotary shaft 52 facing the inner peripheral surface of the touch-down bearing 60 is made the same as the polarity of the touch-down bearing 60, and a repulsive force is generated on the rotary shaft 52, thereby stabilizing the rotary shaft 52. It can be rotatably supported at a position. Moreover, it is only necessary to pass an electric current through the electromagnet only when the shaft swings, and an energy saving effect can be obtained.

Next, the effect | action of the bearing structure in this Embodiment is demonstrated using FIG. FIG. 5 shows a range of shake when the rotation shaft 52 (center axis X) is shaken.
When both the radial direction and thrust direction displacements act on the rotating shaft 52 and the rotating shaft 52 swings, the lower end portion 52b of the rotating shaft 52 is supported by the bearing 55 in both the radial and thrust directions. Therefore, the lower end 52b of the rotating shaft 52 is supported and fixed at one point. That is, as shown in FIG. 5, the swing range of the central axis X of the rotating shaft 52 is an inverted conical range with the bearing 55 at the apex (center) as shown in FIG.

  Further, at the position of the radial magnetic bearing 54, the displacement amount of the rotating shaft 52 is detected by a displacement sensor 59, and the magnetic force of the yoke 57 is controlled based on this displacement amount, whereby the rotating shaft 52 where the shaft runout has occurred. A supporting force P (see FIG. 5) for returning the axis to the position of the central axis X can be applied. Thereby, the displacement amount of the rotating shaft 52 can be decreased.

  On the other hand, as described in the prior art, when two or more radial magnetic bearings are disposed along the extending direction of the rotating shaft, shaft runout occurs in the portions of the two or more radial magnetic bearings, The range of shaft runout as a whole increases synergistically. That is, by supporting the lower end portion 52b of the rotating shaft 52 at one point by the bearing 55, the shaft runout of the rotating shaft 52 as a whole can be reduced. Such a bearing structure provided with the bearing 55 is suitable for the deflection motor 41A of the laser processing apparatus 1 in which the axis of the rotating shaft 52 is likely to be shaken because there are many acceleration / deceleration and forward / reverse control.

  According to the bearing structure according to the embodiment of the present invention, a non-contact type radial magnetic bearing 54 that restricts the displacement of the rotating shaft 52 in the radial direction and one point spaced from the radial magnetic bearing 54 are provided. Since the bearing 55 capable of restricting the displacement in both the radial direction and the thrust direction is provided at one end portion in the longitudinal direction of the rotary shaft 52, two radial magnetic bearings and one thrust magnetic bearing are combined. Compared to the case, a large space is not required to construct the bearing structure. Further, by suppressing the displacement of the shaft at one point of the bearing 55, the axial runout in the radial direction at the radial magnetic bearing 54 can be reduced. Thereby, for example, even when a displacement sensor is used to measure the displacement of the radial magnetic bearing 54 and control (feedback control) for adjusting the displacement is performed, the adjustment width is reduced and the adjustment is easily performed. be able to. Therefore, bearing accuracy can be increased.

  Further, the bearing 55 is formed in a hollow shape that covers the side edge S and the lower end surface T of the rotating shaft 52, and one end portion of the rotating shaft 52 is formed in a hemispherical shape, while the hemispherical portion of the rotating shaft 52 is formed in the bearing 55. Since the contact surface 55a which contacts 52c is formed, the displacement of both a thrust direction or radial direction can be controlled with a simple structure. Therefore, the cost of the bearing can be reduced.

  Furthermore, since a pressing force F for pressing one end of the rotating shaft 52 against the bearing 55 is applied, the bearing 55 can be reliably supported and can be supported at a single point with higher accuracy. .

  Further, since the motor portion 53 is provided between the radial magnetic bearing 54 and the bearing 55, a long distance of the power point (radial magnetic bearing 54) to the fulcrum (bearing 55) can be secured. The force to be applied is small. Moreover, the rotating shaft 52 can be moved largely with this small force. On the other hand, since the distance between the fulcrum (bearing 55) and the displacement sensor 59 can also be increased, the shaft deflection angle with respect to the unit detection distance of the displacement sensor 59 is reduced, and control is facilitated.

  On the other hand, since the structure provided with the bearing 55 is applied to the deflection motor 41A of the laser processing apparatus 1 that has a lot of acceleration / deceleration and forward / reverse control and is easy to shake, the shaft runout of the rotating shaft 52 of the motor 41A is reduced. By suppressing, the scanner mirror 40A can be accurately rotated. Accordingly, the working area 46 can be irradiated with laser light with high accuracy, and the working area 46 that can be processed with the laser processing apparatus 1 can be processed with high accuracy. Further, since the bearing 55 can be configured in a small space, the outer shape of the motor 41A can be reduced. Thereby, the external dimension of the laser processing apparatus 1 can also be made small compared with the past.

The best mode for carrying out the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various modifications and changes can be made based on the technical idea of the present invention. .
FIG. 6A to FIG. 6D are cross-sectional views showing modifications of the contact bearing 55.
In the present embodiment, the shape of the bearing 55 is the contact surface 55a that is in contact with the hemispherical portion 52c of the rotating shaft 52, but is recessed in a conical shape as in the bearing 61 shown in FIG. It may be a hollow shape. As a result, the hemispherical portion 52c of the rotating shaft 52 contacts the conical recess surface 62 in a circular shape, and both the thrust direction acting on the rotating shaft 52 and the radial direction are displaced by the inclination angle of the recess surface 62. Can be supported at one point. Also in this case, the pressing force F acts on the rotating shaft 52, and the hemispherical surface portion 52c of the rotating shaft 52 is pressed against the recessed surface 62. The hemispherical portion 52c and the recessed surface 62 of the bearing 61 are preferably in contact with each other at an angle of 90 degrees or more from the radius center Q (see FIG. 4) of the hemispherical portion 52c. Thus, if the contact is made at an angle of 90 degrees or more, the force acting in the horizontal direction is larger than the force acting in the vertical direction in the hemispherical portion 52c, and the function as a radial bearing can be further improved.

  Further, like the bearing 64 shown in FIG. 6B, the lower end portion of the rotating shaft 65 is made spherical to form a spherical surface 65a partially including a hemispherical surface portion (reference numeral 52c in FIG. 4). 6 (b), the four vertical wall surfaces 66a that support the left and right and the depth direction and the bottom surface 66b that supports the lower side may be used. The spherical surface 65a is in contact with the vertical wall surface 66a and the bottom surface 66b while being supported inside the bearing 64, and supports both displacement in the thrust direction and the radial direction acting on the rotating shaft 65 at one point. Can do. Also in this case, the pressing force F acts on the rotating shaft 65, and the lowermost surface of the spherical surface 65a of the rotating shaft 65 is pressed against the bottom surface 66b.

  Further, like the bearing 70 shown in FIG. 6C, the lower end portion of the rotating shaft 71 is formed in an inverted conical shape, and a round portion 72 having a rounded (curved surface) is provided on the top portion of the conical shape, and the bearing 70 is provided. It is also possible to form a concave surface 73 having an inverted conical shape, and to form a receiving surface 73 a having a roundness substantially the same as the shape of the rounded portion 72 on the lowermost surface of the concave surface 73. The rounded portion 72 and the receiving surface 73a are in contact with each other in a state where the pressing force F is applied, and can support both displacement in the thrust direction and the radial direction acting on the rotating shaft 71 at one point. . In addition, it is preferable that the round part 72 and the receiving surface 73a of the bearing 61 are in contact with each other within a range in which an angle of 90 degrees or more is formed evenly from the radial center of the round part 72. Thus, if the contact is made at an angle of 90 degrees or more, the force acting in the horizontal direction is larger than the force acting in the vertical direction in the hemispherical portion 52c, and the function as a radial bearing can be further improved.

  Moreover, you may make it support by the bearing 77 which has the self-alignment function which supports the lower end part 76b of the rotating shaft 76 like the bearing 75 shown in FIG.6 (d). The bearing 77 having the self-aligning function is a general one that can support displacement in both the radial direction and the thrust direction, and a detailed description thereof is omitted. When this bearing 77 is used, it is not necessary to apply a pressing force F to the rotating shaft 76.

  Further, like the bearing 80 shown in FIG. 6 (e), an upper edge 81 that holds the upper surface of the spherical surface 65a downward may be provided in the structure of the bearing 64 shown in FIG. 6 (b). In this structure, since the thrust load acting on the rotating shaft 65 in the upward direction can be received by the upper edge portion 81, it is not necessary to apply the pressing force F to the rotating shaft 65. Therefore, it is not necessary to attach the permanent magnets 98 and 99, the motor can be further downsized, and the cost can be reduced.

  Furthermore, in the structure shown in FIGS. 6 (a), 6 (b), 6 (c), and 6 (e), the axial end portion and the groove portion are magnetized to have different polarities and have a force for attracting each other. A force in place of F may be obtained.

On the other hand, as shown in FIG. 7A and FIG. 7B, the displacement in the thrust direction and the radial direction can be restricted by making the bearing 55 a non-contact type bearing structure.
In FIG. 7A, the lower end portion of the rotating shaft 86 is formed into a sphere partly including a hemispherical portion (reference numeral 52c in FIG. 4), and the permanent magnet 87 is embedded therein, while the concave shape of the bearing 85 is formed. It may be formed in a hemispherical shape in which a constant gap is formed in accordance with the shape of the hemispherical portion at the lower end of the rotating shaft 86, and the permanent magnet 88 may be embedded in the bearing 85. For example, as shown in FIG. 7A, the permanent magnets 87 and 88 generate a repulsive force so that the south poles face each other. Further, by generating a repulsive force in each hemisphere, it is possible to support displacement in both the radial direction and the thrust direction. In this case, a pressing force F may be applied to the rotating shaft 86 to stabilize the support portion. An electromagnet can also be used instead of a permanent magnet.

  Moreover, in FIG.7 (b), the lower end part of the rotating shaft 91 can be made into a column shape, and the hollow shape of the bearing 90 can also be made into the hollow shape that a fixed clearance gap is formed according to this column shape. A magnetic field that generates a repulsive force is generated in the lower end portion of the rotating shaft 91 and the recess portion of the bearing 90. Further, a pressing force F may be applied to the rotating shaft 91 to stabilize the support portion.

  Furthermore, in the configuration shown in FIGS. 7A and 7B, permanent magnets are embedded, but the surfaces of the bearings 85 and 90 and the rotating shafts 86 and 91 are magnetized to obtain a repulsive force. May be. Further, the magnetization may be generated using an electromagnet. Further, in addition to a permanent magnet embedded (including inside), it may be configured to be fixed to the surface. Thereby, a similar repulsive force can be obtained, and displacement in both the radial direction and the thrust direction can be supported.

On the other hand, in the present embodiment, the motor unit 53 is provided in the motor 41A and the rotating shaft 52 is rotated. However, as shown in FIG. 8, the motor unit 53 is provided outside and the rotating shaft 52 is rotated. It can also be configured.
In FIG. 8, the lower opening 101 is formed in the bottom surface portion 100 b of the housing 100, and the bearing 77 having the automatic alignment function described above is attached to the lower opening 101. The rotating shaft 102 has an upper end portion 102 a protruding from the upper opening portion 106 and a lower end portion 102 b supported by a bearing 77. Further, the lower end portion 102 b of the rotating shaft 102 protrudes slightly below the bearing 77, and is connected to the driving shaft 105 of the motor unit 104 by a coupling 103 for connecting the rotating shaft 102. In addition, as shown in FIG. 8, a radial magnetic bearing 54, a displacement sensor 59, and a touch-down bearing 60 are provided inside the housing 100 at the positions described in the present embodiment. Even in such a configuration, the lower end portion 102b of the rotating shaft 102 is supported by the bearing 77 in both the radial direction and the thrust direction, so the lower end portion 102b of the rotating shaft 102 is supported at one point. Will be. Therefore, the shaft runout of the rotating shaft 102 can be suppressed to a small value.

1 is a schematic diagram of a laser processing apparatus according to an embodiment of the present invention. It is a schematic diagram which expands and shows the state in which the scanner mirror was attached to the motor shown in FIG. It is sectional drawing of the motor shown in FIG. It is a schematic diagram which expands and shows the bearing shown in FIG. It is a schematic diagram which shows the displacement of a rotating shaft. (A)-(e) is a schematic diagram which shows the modification of a contact-type bearing. (A), (b) is a schematic diagram which shows the modification of a non-contact-type bearing. It is sectional drawing which shows the modification of the motor of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 2 Laser oscillator 3 Scanner optical apparatus 4A, 4B Mirror 5 Stone surface plate 6 Control unit 20 Oscillator main body 21 Laser output port 32 Scanner head 33 Adjustment stage 40A, 40B Scanner mirror 41A, 41B Motor 42 Case 43 Output Port 45 Laser beam 46 Working area 51 Housing portion 52 Rotating shaft 52c Hemispherical portion 52d Rotor 53 Motor portion 54 Radial magnetic bearing 55 Bearing 55a Contact surface 56 Stator 57 Yoke 58 Magnetic field generating coil 59 Displacement sensor 61 Bearing 62 Recessed surface X Center axis

Claims (10)

A bearing structure including a non-contact radial magnetic bearing that regulates a radial displacement of a rotatable shaft,
A bearing structure characterized in that a bearing is provided which is spaced apart from the radial magnetic bearing in the longitudinal direction of the shaft and can regulate displacement in both the radial direction and the thrust direction.   The bearing structure according to claim 1, wherein the bearing is disposed at one end portion in a longitudinal direction of the shaft.   The bearing structure according to claim 2, wherein the bearing is formed in a hollow shape covering a side edge and an end surface of the shaft.   The bearing structure according to claim 2 or 3, wherein a hemispherical hemispherical portion is formed at one end of the shaft, and a contact surface that contacts the hemispherical portion is formed on the bearing.   3. A hemispherical hemispherical portion is formed at one end of the shaft, and the hemispherical portion is magnetized, while the bearing is magnetized to a polarity repelling the hemispherical portion. 3. The bearing structure according to 3.   The bearing structure according to claim 4, wherein one end portion of the shaft is pressed toward the bearing.   7. The motor according to claim 1, wherein a motor rotor is integrated with the shaft, and a motor portion is disposed between the radial magnetic bearing and the bearing. Bearing structure. A motor having a rotatable shaft and a non-contact radial magnetic bearing for restricting displacement of the shaft in the radial direction; a scanner mirror for deflecting laser light is attached to the shaft end of the motor; A laser processing apparatus for rotating and irradiating the workpiece with the laser beam,
A laser processing apparatus, characterized in that a bearing capable of regulating displacement in both the radial direction and the thrust direction is provided at a distance from the radial magnetic bearing in the longitudinal direction of the shaft.   The laser processing apparatus according to claim 8, wherein the bearing is disposed at one end portion in a longitudinal direction of the shaft.   The laser processing apparatus according to claim 9, wherein the bearing is formed in a hollow shape covering a side edge portion and an end surface of the shaft.

Images