Galvanometer drive device

Abstract

To provide a galvano motor with excellent cooling performance.SOLUTION: A galvano motor (10) includes a rotary shaft (13) to which a galvano mirror is attached, a cylindrical-shaped housing (11) that accommodates the rotary shaft (13), a coil (15) fixed to the inner surface of the housing (11), a permanent magnet (16) fixed to the rotary shaft (13) in a location facing the coil (15) with a predetermined spacing in a radial direction, and an air bearing (17) that rotatably supports the rotary shaft (13) against the housing (11). The air bearing (17) includes a bearing channel (24) through which compressed air is blown out toward the rotary shaft (13), and a cooling channel (28) that branches off from the bearing channel (24) and blows out compressed air toward the coil (15) and permanent magnet (16).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to , G a galvanometer motor drive device.

Background Art

[0002] A laser processing apparatus is a device that processes a workpiece by irradiating the workpiece with a laser emitted from a laser oscillator. Such a laser processing apparatus includes, for example, a laser oscillator, a galvanometer mirror that deflects the laser emitted from the laser oscillator toward the workpiece, and a galvanometer motor that drives the galvanometer mirror.

[0003] As described in Patent Document 1, for example, a galvanometer motor includes a rotating shaft to which a galvanometer mirror is attached, a cylindrical housing that houses the rotating shaft, a coil fixed to the inner peripheral surface of the housing, a permanent magnet fixed to the rotating shaft, and an air bearing that rotatably supports the rotating shaft with respect to the housing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, in order to improve the throughput of laser processing apparatuses, an increase in the speed of galvanometer motors has been demanded. However, when a large current is passed through the coil to obtain a large acceleration / deceleration torque, the coil generates heat due to its own resistance. Further, when the flowing current has a high-frequency component, the permanent magnet and the yoke generate heat due to eddy currents.

[0006] When the internal temperature of the galvanometer motor rises due to heat generation, the following problems occur. First, demagnetization occurs in the permanent magnet, resulting in a decrease in driving torque or a decrease in the torsional rigidity of the rotating shaft, leading to deterioration in the responsiveness of the servo mechanism. In addition, the bearings and the spindle are thermally deformed, resulting in a decrease in positioning accuracy.

[0007] Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide a galvanometer motor having excellent cooling performance Drive device thereof.

Means for Solving the Problems

[0008] In order to solve such technical problems, the present invention includes a rotating shaft to which a galvanometer mirror is attached, a cylindrical housing that houses the rotating shaft, a coil fixed to the inner peripheral surface of the housing, and a permanent magnet fixed to the rotating shaft at a position facing the coil with a predetermined interval in the radial direction, and an air bearing that rotatably supports the rotating shaft with respect to the housing. A galvanometer motor, a compressor that generates compressed air, a temperature control device that adjusts the temperature of the compressed air generated by the compressor, a temperature sensor that detects the temperature of the coil, and a controller that controls the temperature control device to lower the temperature of the compressed air as the temperature of the coil detected by the temperature sensor is higher. The air bearing includes a bearing flow path that ejects compressed air toward the rotating shaft, At a plurality of positions spaced in the circumferential direction of the rotating shaft a cooling flow path that branches from the bearing flow path and ejects the compressed air generated by the compressor and whose temperature is adjusted by the temperature control device toward the coil and the permanent magnet , and a discharge flow path for discharging the compressed air ejected from the cooling flow path. The plurality of cooling flow paths are formed only on the side opposite to the discharge flow path with the coil and the permanent magnet interposed therebetween in the extending direction of the rotating shaft characterized by that.

Effects of the Invention

[0009] According to the present invention, a galvanometer motor having excellent cooling performance Drive device can be obtained.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the laser processing apparatus 1 according to this embodiment will be described with reference to the drawings. Note that the embodiments of the present invention described below are examples when embodying the present invention, and do not limit the scope of the present invention to the scope of the description of the embodiments. Therefore, the present invention can be implemented with various modifications to the embodiments.

[0012] FIG. 1 is a schematic configuration diagram of the laser processing apparatus 1. As shown in FIG. 1, the laser processing apparatus 1 mainly includes, for example, a laser light source 2, two galvanometer scanners 3a and 3b having different deflection directions (hereinafter, these may be collectively referred to as "galvanometer scanner 3"), and an Fθ lens 4. Further, the galvanometer scanner 3 is composed of a galvanometer mirror 5, a galvanometer motor 10, and a galvanometer motor drive device 30 (see FIG. 3).

[0013] The laser emitted from the laser light source 2 is deflected by each of the galvanometer scanners 3a and 3b, and is condensed onto the printed circuit board 6 through the Fθ lens 4. Thereby, a processing hole is formed in the portion of the printed circuit board 6 where the laser light is condensed. In other words, the galvanometer scanner 3 controls the angle of the galvanometer mirror 5 so that the laser light is condensed at a desired position on the printed circuit board 6. And increasing the response speed of the galvanometer scanner 3 leads to an increase in the drilling speed.

[0014] Figure 2 is a cross-sectional view of the galvanometer motor 10 according to this embodiment. As shown in Figure 2, the galvanometer motor 10 mainly includes a housing 11, a pair of covers 12a and 12b, a rotating shaft 13, a pedestal 14, a coil 15, a permanent magnet 16, a radial bearing 17, a thrust bearing 18, and a radial thrust bearing 19. Hereinafter, the radial bearing 17, the thrust bearing 18, and the radial thrust bearing 19 are collectively referred to as "air bearings 17 to 19".

[0015] The housing 11 has a cylindrical outer shape with both ends open. The housing 11 has an internal space for accommodating the components 13 to 19 of the galvanometer motor 10. The pair of covers 12a and 12b have a disk-shaped outer shape with a through-hole formed in the center. And the pair of covers 12a and 12b are attached to both ends of the housing 11.

[0016] The rotating shaft 13 is accommodated inside the housing 11. Also, a part of the rotating shaft 13 is exposed outside the housing 11 through the through-holes of the pair of covers 12a and 12b. That is, the diameter of the through-holes of the covers 12a and 12b is set larger than the diameter of the rotating shaft 13. And the galvanometer mirror 5 is attached to the portion of the rotating shaft 13 exposed from the housing 11. Further, a disk-shaped flange portion 13a that protrudes outward in the radial direction is provided on the rotating shaft 13.

[0017] The pedestal 14 has a cylindrical outer shape. The pedestal 14 is fixed to the inner surface of the housing 11 so as to surround the rotating shaft 13. The coil 15 is fixed to the inner peripheral surface of the pedestal 14 (that is, the housing 11). The permanent magnet 16 is fixed to the rotating shaft 13 at a position facing the coil 15 with a predetermined interval in the radial direction. That is, by supplying current to the coil 15, the rotating shaft 13 integrated with the permanent magnet 16 rotates.

[0018] The air bearings 17 to 19 rotatably support the rotating shaft 13 with respect to the housing 11. The radial bearing 17 supports the radial load acting on the rotating shaft 13. The thrust bearing 18 supports the thrust load acting on the rotating shaft 13. The radial thrust bearing 19 supports the radial and thrust loads acting on the rotating shaft 13. Further, the air bearings 17 to 19 are formed of copper or the like having a high thermal conductivity.

[0019] The radial bearing 17 is disposed on one side in the thrust direction from the coil 15 and the permanent magnet 16. The thrust bearing 18 is disposed on the other side in the thrust direction from the coil 15 and the permanent magnet 16 and on one side in the thrust direction from the flange portion 13a. The radial thrust bearing 19 is disposed on the other side in the thrust direction from the flange portion 13a. In other words, the radial bearing 17 and the thrust bearing 18 are disposed on opposite sides sandwiching the coil 15 and the permanent magnet 16 in the thrust direction. Further, the thrust bearing 18 and the radial thrust bearing 19 are disposed on opposite sides sandwiching the flange portion 13a in the thrust direction.

[0020] The air bearings 17 to 19 rotatably support the rotating shaft 13 with respect to the housing 11 by jetting the compressed air generated by the compressor 34 (see FIG. 3) toward the rotating shaft 13. Therefore, flow paths for passing the compressed air are formed inside the housing 11 and the air bearings 17 to 19.

[0021] A compressed air flow path 20 is formed in the housing 11. The compressed air generated by the compressor 34 is supplied to the compressed air flow path 20. The compressed air flow path 20 branches inside the housing 11 and is connected to each of the plurality of circumferential grooves 21, 22, 23. The circumferential grooves 21, 22, 23 are formed on the outer peripheral surfaces of the air bearings 17 to 19 at positions facing the inner peripheral surface of the housing 11. Further, the circumferential grooves 21, 22, 23 are ring-shaped and continuous in the circumferential direction.

[0022] The radial bearing 17 is formed with a circumferential groove 21 and a plurality of radial bearing channels 24. The plurality of radial bearing channels 24 penetrate the radial bearing 17 in the radial direction at positions spaced apart in the circumferential direction. And the plurality of radial bearing channels 24 are connected to the circumferential groove 21 on the outer peripheral surface side, and the openings on the inner peripheral surface side face the rotating shaft 13.

[0023] The thrust bearing 18 is formed with a circumferential groove 22 and a plurality of thrust bearing channels 25. The plurality of thrust bearing channels 25 are formed inside the thrust bearing 18 at positions spaced apart in the circumferential direction. The thrust bearing channel 25 has its outer peripheral surface side connected to the circumferential groove 22, bends inside the thrust bearing 18, and the opening on the side surface side of the thrust bearing 18 faces one side surface of the flange portion 13a.

[0024] The radial thrust bearing 19 is formed with a circumferential groove 23, a plurality of radial bearing channels 26, and a plurality of thrust bearing channels 27. The plurality of radial bearing channels 26 penetrate the radial thrust bearing 19 in the radial direction at positions spaced apart in the circumferential direction. And the plurality of radial bearing channels 26 are connected to the circumferential groove 23 on the outer peripheral surface side, and the openings on the inner peripheral surface side face the rotating shaft 13. The plurality of thrust bearing channels 27 branch off from the radial bearing channels 26, and the openings on the side surface side of the radial thrust bearing 19 face the other side surface of the flange portion 13a.

[0025] As shown by the solid arrows in FIG. 2, by injecting compressed air onto the outer peripheral surface of the rotating shaft 13 through the compressed air channel 20, the circumferential grooves 21 and 23, and the radial bearing channels 24 and 26, the radial load acting on the rotating shaft 13 is supported. Also, by injecting compressed air onto both side surfaces of the flange portion 13a through the compressed air channel 20, the circumferential grooves 22 and 23, and the thrust bearing channels 25 and 27, the thrust load acting on the rotating shaft 13 is supported.

[0026] In addition, a plurality of cooling channels 28 are formed in the radial bearing 17. The plurality of cooling channels 28 branch from the radial bearing channel 24 inside the radial bearing 17 and eject compressed air toward the coil 15 and the permanent magnet 16. The pitch and the opening area of the radial bearing channel 24 and the cooling channels 28 are set to be the same, for example.

[0027] Furthermore, a discharge channel 29 is formed in the housing 11 and the pedestal 14. The discharge channel 29 penetrates the housing 11 and the pedestal 14 in the radial direction between the coil 15 and the permanent magnet 16 and the thrust bearing 18. As shown by the dashed arrow in FIG. 2, the compressed air ejected into the inside of the galvano motor 10 through the cooling channels 28 cools the coil 15 and the permanent magnet 16 and is discharged to the outside of the galvano motor 10 through the discharge channel 29.

[0028] FIG. 3 is a hardware configuration diagram of the galvano motor driving device 30. As shown in FIG. 3, the galvano motor driving device 30 includes a controller 31. The controller 31 controls the overall operation of the galvano motor 10. The controller 31 includes, for example, a CPU (Central Processing Unit) 32 and a memory 33. The controller 31 realizes the processes described below by the CPU 32 reading and executing the program code stored in the memory 33.

[0029] However, the specific configuration of the controller 31 is not limited to this, and it may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0030] The controller 31 is connected to the coil 15, the compressor 34, the temperature control device 35, and the thermistor (temperature sensor) 36. The controller 31 rotates the galvanometer motor 10 by supplying current to the coil 15. More specifically, the controller 31 adjusts the angle of the galvanometer mirror 5 by controlling the magnitude and direction of the current supplied to the coil 15.

[0031] The compressor 34 generates compressed air. The temperature control device 35 adjusts the temperature of the compressed air generated by the compressor 34. The temperature control device 35 adjusts the temperature of the compressed air, for example, in the range of 10°C to 25°C (more preferably, around 20°C). That is, the compressed air adjusted in temperature by the temperature control device 35 and generated by the compressor 34 is supplied to the compressed air flow path 20. The thermistor 36 detects the temperature of the coil 15 and outputs a temperature signal indicating the detected temperature to the controller 31.

[0032] FIG. 4 is a flowchart of the temperature setting process. The temperature setting process is a process of setting the temperature of the compressed air supplied to the galvanometer motor 10 based on the temperature of the coil 15 detected by the thermistor 36. The controller 31 repeatedly executes the temperature setting process at predetermined time intervals while driving the galvanometer motor 10.

[0033] First, the controller 31 compares the temperature T of the coil 15 detected by the thermistor 36 with a predetermined threshold value Th (S11). Then, when the temperature T of the coil 15 is less than the threshold value Th (S11: Yes), the controller 31 sets the temperature of the compressed air to T1 (S12). On the other hand, when the temperature T of the coil 15 is greater than or equal to the threshold value Th (S11: No), the controller 31 sets the temperature of the compressed air to T2 (S13). Then, the controller 31 drives the temperature control device 35 at the temperature set in steps S12 to S13 (S14).

[0034] Note that the temperatures T1 and T2 are predetermined temperatures where 10°C < T2 < T1 < 25°C. However, the temperature of the compressed air is not limited to two levels. That is, the controller 31 may lower the temperature of the compressed air as the temperature of the coil 15 detected by the thermistor 36 is higher. Also, the controller 31 may raise the temperature of the compressed air as the temperature of the coil 15 detected by the thermistor 36 is lower.

[0035] According to the above embodiment, for example, the following operational effects can be achieved.

[0036] According to the above embodiment, since a part of the compressed air for rotatably supporting the rotating shaft 13 is used to cool the coil 15 and the permanent magnet 16, the galvanometer motor 10 can be efficiently cooled with a simple configuration. As a result, it is possible to suppress a decrease in the servo responsiveness of the galvanometer motor 10 due to heat generation.

[0037] Note that in the above embodiment, an example in which the cooling channel 28 is formed in the radial bearing 17 has been described, but the cooling channel 28 may be formed in the thrust bearing 18. That is, the cooling channel 28 may branch from the bent portion of the thrust bearing channel 25 and eject compressed air toward the coil 15 and the permanent magnet 16. In this case, the discharge channel 29 is preferably formed between the coil 15 and the permanent magnet 16 and the radial bearing 17. Also, the discharge channel 29 may be omitted and the compressed air may be discharged from the through holes of the covers 12a and 12b.

[0038] Also, according to the above embodiment, since the temperature of the compressed air is adjusted based on the temperature of the coil 15, the coil 15 and the permanent magnet 16 can be efficiently cooled, and the occurrence of condensation due to overcooling can be prevented.

Description of Reference Numerals

[0039] 1 Laser processing apparatus, 2 Laser light source, 3 Galvanometer scanner, 4 Fθ lens, 5 Galvanometer mirror, 6 Printed circuit board, 10 Galvanometer motor, 11 Housing, 12a, 12b Cover, 13 Rotation axis, 13a Flange portion, 14 Pedestal, 15 Coil, 16 Permanent magnet, 17 Radial bearing, 18 Thrust bearing, 19 Radial thrust bearing, 20 Compressed air flow path, 21, 22, 23 Circumferential groove, 24, 26 Radial bearing flow path, 25, 27 Thrust bearing flow path, 28 Cooling flow path, 29 Discharge flow path, 30 Galvanometer motor drive device, 31 Controller, 32 CPU, 33 Memory, 34 Compressor, 35 Temperature control device, 36 Thermistor

Claims

1. A rotating shaft to which a galvano mirror is attached, A cylindrical housing that houses the rotating shaft, A coil fixed to the inner peripheral surface of the housing, A permanent magnet fixed to the rotating shaft at a position facing the coil with a predetermined interval in the radial direction, A galvano motor comprising an air bearing that rotatably supports the rotating shaft with respect to the housing, A compressor that generates compressed air, A temperature control device that adjusts the temperature of the compressed air generated by the compressor, A temperature sensor that detects the temperature of the coil, A controller that controls the temperature control device to lower the temperature of the compressed air as the temperature of the coil detected by the temperature sensor is higher, The air bearing, A bearing flow path that jets compressed air toward the rotating shaft, A plurality of cooling flow paths that branch from the bearing flow path at a plurality of positions spaced in the circumferential direction of the rotating shaft and jet the compressed air generated by the compressor and temperature-adjusted by the temperature control device toward the coil and the permanent magnet, An exhaust flow path that discharges the compressed air jetted from the cooling flow path, The plurality of cooling flow paths are formed only on the side opposite to the exhaust flow path with the coil and the permanent magnet interposed therebetween in the extending direction of the rotating shaft. A galvano motor driving device characterized by this.

2. In the galvano motor driving device according to Claim 1, The air bearing, A radial bearing that supports the radial load of the rotating shaft on one side in the thrust direction from the coil and the permanent magnet, A thrust bearing that supports the thrust load of the rotating shaft on the other side in the thrust direction from the coil and the permanent magnet, The cooling flow path is provided in the radial bearing. A galvano motor driving device characterized by this.

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