JP2008228524A - Rocking actuator and laser machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rocking actuator that suppresses variations in the torque constant, while controlling magnet temperature using a simple constitution, and to provide a laser machining device that uses such a rocking actuator. <P>SOLUTION: The rocking actuator includes a rotor, which is composed of a rotary shaft 12 and a magnet 13 arranged around the rotary shaft 12, a coil 14 arranged around the rotor, and a current supply means for supplying a current to the coil 14. The current supply means is made into a current supply means 35 that supplies a high-frequency current in addition to a current for rotating the rotor. A temperature detection means is provided so as to measure a temperature of the magnet 13. The current supply means 35 controls a temperature of the magnet 13, by superimposing a high-frequency current on a current supplied to the coil 14, on the basis of the measurement result of the temperature detection means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a swing actuator device that uses a coil as a stator, a permanent magnet as a rotor, and is fixed to a rotating shaft, and swings the rotor within a predetermined angle range, and a laser using such a swing actuator device. It relates to a processing apparatus.

  FIG. 2 is a sectional view of a general moving magnet type galvano scanner. The galvano scanner is a swing actuator device that oscillates a galvanometer mirror, and a rotor is formed by a rotary shaft 12 for driving the galvanometer mirror and a magnet 13 attached to the outside thereof. A stator is formed by a coil 14 wound around the rotor and a silicon steel plate (yoke) 18 constituting a magnetic circuit. The rotor and the stator are accommodated in the outer cylinder 19. The rotating shaft 12 is rotatably supported on the stator side by a bearing 17. A galvanometer mirror 4 is attached to one end of the rotating shaft 12. An encoder for detecting the rotation angle of the rotary shaft 12 is attached to the other end of the rotary shaft 12. The encoder includes a grating 15 attached to the rotary shaft 12 and an optical pickup 16 for reading a slit on the grating 15. And by sending an electric current through the coil 14, electromagnetic force generate | occur | produces in the magnet 13, and the axis | shaft 12 rotates with the torque.

  In recent years, with the progress of high integration of electrical products, the diameter of holes processed in a printed circuit board tends to be reduced. In order to process a small-diameter hole, it is necessary to increase the diameter of the laser, and accordingly, it is necessary to increase the size of the galvanometer mirror or the like. A large torque is required to swing the large galvanometer mirror, and the drive current also increases, so the Joule heat generated in the coil heats the coil and the structure in the vicinity thereof, and the temperature rises. Moreover, the speed of drilling holes has been increasing year by year in order to improve the processing throughput, but the larger the galvanometer mirror is moved, the greater the heat generated. When the temperature of the magnet rises with heat generation, the magnetic force of the magnet is lowered and the torque constant is reduced, the controllability is lowered and the positioning accuracy is deteriorated. In order to avoid such a problem, there is a galvano scanner in which the heat generation of the coil is averaged by adjusting the processing order (Patent Document 1).

As a high-speed spindle motor or the like, there is a spindle motor provided with a heater for heating in order to avoid an increase in bearing friction in a low temperature environment (Patent Document 2). Some galvano scanners can control the overall temperature of the galvano scanner by means of a similar technique.
JP 2003-329960 A JP 2006-115688 A

  However, when the technique of Patent Document 1 is adopted, the processing throughput may decrease. Further, when the technique of Patent Document 2 is adopted, a heater, a heater power supply, and a controller are separately required, resulting in an expensive system.

  An object of the present invention is to provide a swing actuator device capable of controlling a magnet temperature with a simple configuration and suppressing fluctuations in torque constant, and a laser processing apparatus using such a swing actuator device.

  In order to solve the above-described problem, a first means of the present invention includes a rotor including a rotating shaft and a magnet disposed around the rotating shaft, and a coil and a yoke disposed around the rotor. A stator, a housing for housing the rotor and the stator, and current supply means for supplying a current to the coil; and controlling the current supplied to the coil to determine the rotor at a predetermined angle In a swing actuator device that swings within a range, a temperature detection unit for measuring or estimating the temperature of the magnet and a high-frequency current supply unit are provided, and the current supply is performed based on a measurement result of the temperature detection unit The temperature of the magnet is controlled by superimposing the high-frequency current on the current supplied to the coil by the means.

  In this case, the frequency of the high-frequency current can be 2 MHz or more and 1 MHz or less of the frequency of the current that drives the rotor.

  The frequency of the high frequency current may be in a frequency band different from the resonance frequency of the rotor.

  And as said temperature detection means, the emitted-heat amount of the said coil can be calculated from the driving | operation information of the said rotor, and the said magnet temperature can be estimated from the obtained emitted-heat amount.

  According to a second means of the present invention, in the laser processing apparatus provided with the swing actuator device, the swing actuator device is the swing actuator device according to any one of claims 1 to 4. And

  According to the present invention, since the torque constant of the galvano scanner is constant, position controllability and positioning accuracy are improved.

  In the present invention, a high-frequency current is passed through a coil of a galvano scanner, and an eddy current is generated in the magnet by the induction, thereby heating the magnet to adjust the temperature. Hereinafter, the principle of the present invention will be described.

  FIG. 3 is a three-dimensional view of the vicinity of the magnet and the coil of the galvano scanner described in FIG. 2, and the magnet 13 and the rotary shaft 12 are cut as a whole, and the coil 14, the silicon steel plate 18 and the outer cylinder 19 are cut in half. Each has been shown. FIG. 4 is a diagram showing the rotation shaft 12 in a three-dimensional manner.

  In the galvano scanner as described above, the galvano mirror is driven at a maximum of about 2.5 kHz, but the current supplied to the coil 14 has an alternating current component of 10 kHz or less, which is several times that. When an eddy current is generated in an adjacent structure with respect to the alternating current component of the current, the torque generated by the cancellation of the magnetic field generated by the coil 14 is reduced. In addition, Joule heat generated by eddy current is also a problem. In order to prevent this, a thin silicon steel plate 18 is laminated as a magnetic material outside the coil 14, and the magnet 13 is also a structure in which a neodymium magnet having a small specific resistance is bonded to prevent an eddy current from flowing. Yes.

  However, if the frequency of the alternating current component of the coil current is further increased, the eddy current is likely to flow with a small eddy, so that the eddy current is generated particularly on the surface of the magnet 13 and the magnet 13 generates heat. The electric field generated on the surface of the magnet 13 by the current flowing through the coil 14 is as shown by an arrow 100. The eddy current generated on the surface of the magnet 13 by this electric field is divided because no current flows in the divided portion of the magnet 13, and becomes an eddy current flowing as shown by an arrow 101 in FIG. 4.

  When an alternating current exceeding 10 kHz is supplied to the coil 14, eddy current flows strongly even in the magnet 13 divided as shown in FIG. 4, and Joule heat generation (hereinafter referred to as induction heat generation) due to the eddy current occurs in the magnet 13. It becomes like this. The magnitude of the induction heat generated in the magnet 13 is roughly proportional to the square of the frequency of the alternating current, but the Joule heat generated in the coil 14 does not depend on the frequency. Will be heated.

  Thus, the magnet 13 can be directly heated by intentionally adding a high-frequency band alternating current to the current supplied to the coil 14. And the magnitude | size of the induction heat_generation | fever which heats the magnet 13 can be adjusted with the frequency and magnitude | size of a high frequency current.

  FIG. 5 is a block diagram of a galvano scanner control system suitable for the heating method according to the present invention.

  In this galvano scanner control system, the lower galvano scanner controller 32 receives the galvano scanner 10 (coil 14) from the galvano mirror position command 31 instructed by the upper controller 30 and the rotational position information 33 of the galvano mirror 4 from the galvano scanner 10. The position control current command 34 to be supplied to the current generator 35 is input to the current generator 35. The current generator 35 can supply a current for driving the rotor and a high-frequency current described later.

  The current generator 35 supplies current to the galvano scanner 10 in accordance with the position control current command 34. The process up to this point is the same as the conventional technique. In the present invention, the magnet temperature information 37 measured by the temperature measuring means is input to the magnet temperature controller 36, and the magnet temperature controller 36 inputs a high frequency current command 38 to the current generator 35 so that the target temperature of the magnet temperature is obtained. The current generator 35 supplies a current 39 obtained by adding the position control current command 34 and the high-frequency current command 38 to the galvano scanner 10. By supplying a high-frequency current for heating the magnet 13 whose magnitude is adjusted in addition to the current for position control, the magnitude of the induction heat is controlled to adjust the temperature of the magnet 13.

  Next, the frequency of the current used as the high frequency current will be described.

  FIG. 6 is a mechanical characteristic curve of the galvano scanner shown in FIG. 2, where the horizontal axis represents frequency and the vertical axis represents gain (rotation angle amplitude divided by current amplitude). It can be seen from the figure that a larger rotation angle amplitude is obtained with a smaller current amplitude as the gain is increased. There are several peaks in the mechanical characteristic curve, which indicates that resonance occurs in the rotor, and the gain increases near the resonance frequency. From this figure, if the frequency of the high frequency applied for heating the magnet is selected to be, for example, about 100 kHz, the gain can be reduced without resonance and it can be considered that the rotation hardly occurs.

  As described above, in the present invention, the induction temperature is generated in the magnet 13 by supplying the coil 14 with a high-frequency current that the rotation axis does not follow (does not rotate), and the magnet temperature is adjusted by controlling the magnitude. It is characterized by that. In this configuration, no special power source or the like is required, and the temperature of the magnet can be controlled with a simple configuration.

  FIG. 1 is a block diagram of a laser processing apparatus embodying the present invention.

  The laser beam 2 oscillated from the laser 1 is formed into a beam cross-sectional shape by a beam forming device 3, then changed in direction by a biaxial galvanometer mirror 4 and converted and condensed in a vertical direction by an fθ lens 5. Then, the light is incident on the printed circuit board 6 to make a hole in the printed circuit board 6. The printed circuit board 6 is placed on an XY stage 7 that is movable in the XY directions. The rotation angle of the galvanometer mirror 4 is adjusted by a galvanometer scanner 10 that rotates the galvanometer mirror 4.

  The lower galvano scanner controller 32 is for position control supplied to the galvano scanner 10 (coil 14) from the galvano mirror position command 31 instructed from the upper controller 30 and the rotational position information 33 of the galvano mirror 4 from the galvano scanner 10. A current command 34 is input to the current generator 35.

  On the other hand, the magnet temperature controller 37 inputs a high frequency current command 38 to the current generator 35 so that the temperature of the magnet 13 becomes the target temperature based on the magnet temperature information 137 of the magnet 13 measured by the temperature measuring means.

  The current generator 35 supplies the galvano scanner 10 with a current 39 obtained by adding the position control current command 34 and the high-frequency current command 38.

  As a result, the temperature of the magnet 13 is always kept constant (for example, 40 ° C.) regardless of the driving state of the galvanometer mirror 4, so that torque fluctuation does not occur.

  In order to prevent the rotating shaft 12 from rotating due to the high frequency current, the frequency of the high frequency current is set to be twice or more the driving frequency of the galvano scanner. Also, it is desirable not to use the galvano scanner because it resonates at frequencies near the resonance frequency inherent to the galvano scanner. Further, if the frequency of the high frequency current is increased too much, the resistance value of the coil 14 increases due to the skin effect of the wire of the coil 14, and it becomes difficult for the current to flow through the coil 14. Therefore, it is desirable to set the frequency to about 1 MHz or less.

  FIG. 7 is a flowchart for explaining a magnet temperature control method during operation. When machining is started, the temperature of the magnet is measured by the temperature measuring means (procedure S10), and the measured temperature is evaluated (procedure S20). If the magnet temperature is equal to or lower than the low temperature allowable temperature, a magnet heating high frequency current is applied to increase the magnet temperature (step S30), and if the magnet temperature is equal to or higher than a specified value, the high frequency current is stopped (step S40). ). During operation, the routine of this flowchart is repeated at regular time intervals to adjust the magnet temperature to near the low temperature allowable temperature.

  FIG. 8 is a diagram showing an example of a time waveform of a conventional position control current command when the above operation is performed, and FIG. 9 is an example of a time waveform of the magnet temperature in that case. In the conventional technique, when the galvano scanner is stopped, the position control current is also zero, so the temperature of the magnet is lowered and a large temperature change occurs.

  FIG. 10 is a diagram showing an example of a time waveform of the position control current command in the present invention when the same operation as that of FIG. 8 is performed, and FIG. 11 is an example of a time waveform of the magnet temperature in that case.

  In the case of the present invention, as shown in FIG. 11, when the magnet temperature becomes equal to or lower than the low temperature allowable temperature, a high-frequency current for heating the magnet temperature is applied, and the temperature of the magnet rises accordingly. And if it becomes more than low temperature allowable temperature, a high frequency current will be stopped and temperature will fall again. By repeatedly applying and stopping such a high-frequency current while the galvano scanner is stopped, the temperature of the magnet is controlled in the vicinity of the approximate low temperature allowable temperature.

  Next, the magnet temperature measuring means will be described.

  FIG. 12 is a front sectional view of the galvano scanner according to the present invention, and the same components as those in FIG.

  A hole 200 for passing a thin optical fiber 102 is formed in the outer cylinder 19, the silicon steel plate 18 and the coil 14. The optical fiber 102 is fixed to the hole 200 so that one end thereof faces the magnet 13, and the other end is connected to a radiation thermometer 103 in the infrared region. The radiation thermometer 103 has a better measurement accuracy as the emissivity of the measurement object is closer to 1, so that the surface of the magnet 13 is painted with, for example, a black paint so that the emissivity of the emitted light is close to 1. Is desirable.

  According to this embodiment, the surface of the magnet can be measured in a non-contact manner, so that it is not hindered from rotating at high speed.

  Next, a second embodiment of the present invention will be described.

  FIG. 13 is a block diagram of a laser processing apparatus according to the present invention.

  The galvano scanner controller 32 receives galvano scanner operation information 138 from the host controller 30 instead of the magnet temperature information 137 in FIG. The galvano scanner controller 32 calculates the amount of heat generated by the galvano scanner 10 from the galvano scanner operation information 138. The temperature of the magnet 13 is estimated from the amount of heat generated there, and the magnet temperature is controlled.

  FIG. 14 is a flowchart for explaining a magnet temperature control method in this embodiment.

  When the machining is started, the average heat value is calculated from the operation information (step S100), the magnet temperature is calculated from the obtained average heat value (step S110), and the measured temperature is evaluated (step S120). ). If the magnet temperature is equal to or lower than the low temperature allowable temperature, a magnet heating high frequency current is applied to increase the magnet temperature (step S130), and if the magnet temperature is equal to or higher than a specified value, the high frequency current is stopped (step S140). ). During operation, the routine of this flowchart is repeated at regular time intervals to adjust the magnet temperature to near the low temperature allowable temperature.

  In this embodiment, since a measuring instrument for measuring the temperature of the magnet is not required, the structure becomes simple and the apparatus cost can be reduced.

  Next, a third embodiment of the present invention will be described.

  FIG. 15 is a configuration diagram of another temperature measuring means of the magnet of the galvano scanner according to the present invention, and the same components as those in FIG.

  A hole 201 is formed at the center of the rotating shaft 12 in the axial direction. The thermistor 104 is disposed in the hole 201. Since the thermistor 104 is located at a location surrounded by the magnet 13, it corresponds to measuring the average temperature of the entire magnet. The signal of the thermistor 104 passes through the center of the grating 15 and is taken out of the galvano scanner 10 and inputted to the temperature measuring device 105 to become temperature information. At this time, it is necessary to prevent the rotation of the rotating shaft 102 from being hindered by using a thin line as much as possible as the signal line. Since the magnet 13 is heated by the eddy current on the coil 14 and the magnet surface, it is desirable to measure the temperature of the magnet surface as in the first embodiment. However, the structure is complicated such as making a hole 200 in the silicon steel plate 18. However, the present embodiment is excellent in that it can be easily installed, and is excellent in cost because a relatively inexpensive contact-type temperature measuring instrument such as a thermistor can be used.

  In the present embodiment, the temperature measurement is described using a thermistor, but a similar contact-type temperature measurement method such as a thermocouple may be employed.

It is a block diagram of the laser processing apparatus which implemented this invention. (Example 1) It is sectional drawing of the conventional general moving magnet type galvano scanner. It is a perspective view of the conventional galvano scanner. It is a perspective view of the conventional galvano scanner. It is a block diagram of a galvano scanner control system according to the present invention. It is a mechanical characteristic curve of the rotor of a galvano scanner. It is a flowchart explaining the control method of the magnet temperature which concerns on this invention. It is explanatory drawing of a prior art. It is explanatory drawing of a prior art. It is an example of the time waveform of the magnet temperature which concerns on this invention. It is an example of the time waveform of the high frequency electric current command which concerns on this invention. It is sectional drawing of the galvano scanner which concerns on this invention. It is a block diagram of the laser processing machine which concerns on this invention. It is a flowchart explaining the control method of the magnet temperature which concerns on this invention. It is sectional drawing of the galvano scanner which concerns on this invention.

Explanation of symbols

Rotating shaft 12
Magnet 13
Coil 14
35 Current generator

Claims (5)

A rotor composed of a rotating shaft and a magnet arranged around the rotating shaft;
A stator composed of a coil and a yoke disposed around the rotor;
A housing for housing the rotor and the stator;
Current supply means for supplying current to the coil;
A swing actuator device that swings the rotor within a predetermined angle range by controlling a current supplied to the coil,
Temperature detecting means for measuring or estimating the temperature of the magnet;
High-frequency current supply means;
Provided,
An oscillating actuator device, wherein the temperature of the magnet is controlled by superimposing the high-frequency current on a current supplied to the coil by the current supply unit based on a measurement result of the temperature detection unit.   2. The oscillation actuator device according to claim 1, wherein the frequency of the high-frequency current is not less than twice the frequency of the current driving the rotor and not more than 1 MHz.   The oscillation actuator device according to claim 1 or 2, wherein the frequency of the high-frequency current is set to a frequency band different from a resonance frequency of the rotor.   4. The temperature detection unit according to claim 1, wherein the temperature detection unit calculates a heat generation amount of the coil based on operation information of the rotor, and estimates the magnet temperature from the obtained heat generation amount. 5. The swing actuator device described.   A laser processing apparatus comprising the oscillating actuator device according to any one of claims 1 to 4.

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