JPH03112181A - Turbo floor for laser and laser oscillation device using it - Google Patents

Abstract

PURPOSE:To shut off heat build-up with magnetic coupling by torque coupling first and second shafts through the magnetic coupling and arranging a turbo blade on the first shaft while a heat source motor on the second shaft. CONSTITUTION:A shaft 21 and a bearing 5 where a turbo wing 1 is mounted are stored within a housing 11, both sides are sealed by O rings 9 and 10, and they are placed under laser gas. A motor with the shaft 21, the bearings 13 and 14, a rotor 3, and a stator 4 is stored within a housing 12 and it is placed under atmospheric pressure. A water-cooling pipe 15 is provided around the stator 4. With magnetic coupling, a magnetic pole 16 is rotated according to the revolution of a cylindrical yoke 17 and rotary torque is transmitted from the axis 22 to an axis 21. An insulator barrier 18 is provided between the magnetic pole and a yoke and laser gas is airtightly sealed. Heat build-up at the rotor 3 is not transmitted to bearings 5 and 6, thus cooling the axis 22 which is heated by the rotor 3. Also, the axis 21 is not affected by the influence of heat build-up due to eddy current. With this configuration, a turbo blower which does not require replacement of grease, etc., can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a turbo blower for a laser that forcibly circulates laser gas in a processing gas laser device, etc., and a laser oscillation device using the same, and particularly relates to a turbo blower for use in a gas laser device for processing, etc., and a laser oscillation device using the same. Realize,
The present invention relates to a laser turbo blower and a laser oscillation device with improved reliability and maintainability.

[Conventional technology]

Recent carbon dioxide (Co□) gas laser oscillators can obtain high output and have good quality laser beams, and are widely used for laser processing such as cutting metal or non-metallic materials, welding metal materials, etc. In particular, CNC laser processing machines combined with CNCC numerical control devices are rapidly developing in the field of cutting complex shapes at high speed and with high precision.

A conventional carbon dioxide (CO2) gas laser oscillation device will be described below with reference to the drawings.

FIG. 4 is a diagram showing the overall configuration of a carbon dioxide (CO2) gas laser oscillation device according to the prior art. An optical resonator consisting of an output coupling mirror 32 and a total reflection mirror 33 is installed at both ends of the discharge tube 31. Metal electrodes 34 and 35 are attached to the outer periphery of the discharge tube 31. The metal electrode 34 is grounded, and the metal electrode 35 is connected to a high frequency power source 36. A high frequency voltage is applied between the metal electrodes 34 and 35 from a high frequency power supply 36. As a result, a high frequency glow discharge is generated within the discharge tube 31, and laser excitation is performed. The optical axis of the laser beam inside the discharge tube 31 is set at 43, and the output coupling mirror 3
The laser beam optical axes taken out from 2 to the outside are indicated by 44, respectively.

When starting up such a gas laser oscillation device, the vacuum pump 42 always first evacuates the entire gas inside the device. Then, the valve 41 is opened, a predetermined flow rate of laser gas is introduced from the gas cylinder 40, and the gas pressure within the apparatus reaches a predetermined value. Thereafter, the vacuum pump 42 is evacuated and the valve 41 is used to introduce supplementary gas, and a portion of the laser gas is continuously replaced with fresh gas while the gas pressure inside the device is maintained at a specified value. This prevents gas contamination within the device.

Furthermore, in FIG. 4, the laser gas is circulated within the apparatus by a blower 39. Its purpose is to cool the laser gas. In carbon dioxide (CO2) gas lasers, about 20% of the injected electrical energy is converted into laser light, and the rest is consumed for gas heating. However, according to theory, the laser oscillation gain is proportional to the -(3/2) power of the absolute temperature T, so in order to increase the oscillation efficiency, it is necessary to forcibly cool the laser gas.

In this device, the laser gas passes through the discharge tube 31 at a flow rate of about 100 m/sec, flows in the direction shown by the arrow, and passes through the cooler 38.
guided by. The cooler 38 mainly removes heating energy due to discharge from the laser gas. And the blower 39
compresses the cooled laser gas. The compressed laser gas is guided to the discharge tube 31 via the cooler 37. This is because the compression heat generated by the blower 39 is removed by the cooler 37 before being guided to the discharge tube 31 again. Since these coolers 37 and 38 are well known, detailed explanation will be omitted.

The blower 39 used includes a roots blower and a turbo blower. Figure 5 shows the structure of the turbo blower. The turbo blade 1 and the shaft 2 are mechanically coupled. A rotor 3 is attached to the shaft 2,
The rotor 3 and stator 4 constitute a high frequency motor. The turbo blade 1 is rotated at a high speed of 10,000 RPM by this high frequency motor. Therefore, compared to a Roots blower that rotates at low speed, the volume is smaller in inverse proportion to the rotation speed.

Furthermore, for supporting the shaft 2, a pair of rolling bearings 5 and 6 are used on either side of the high frequency motor. Grease lubrication is normally used to lubricate the rolling bearings 5 and 6 in order to prevent laser gas contamination by oil mist.

With this configuration, laser gas is drawn from the cooler 38 to the laser turbo blower as shown by arrow 8, and is discharged from the laser turbo blower to the cooler 37 as shown by arrow 7.

[Problem to be solved by the invention]

The conventional laser oscillation device shown in FIGS. 4 and 5 has the following problems.

In other words, in the conventional laser turbo blower, 100,000 RPM
Because the motor rotates at high speed, the motor generates a large amount of heat, causing problems such as deterioration and depletion of grease. That is,
The efficiency of the motor is about 75%, and the remaining 25% is heat loss from the motor. For example, in the case of a motor with an output of 2 kW, the heat loss is approximately 667 W. Approximately 56 of these
7W is heat generation due to iron loss and copper loss in stator 4, which is approximately 1
00W is heat generation due to copper loss of the rotor 3.

Due to this heat generation, the temperature of the rotor 3 reaches 100° C. or more. The heat generated by the stator 4 can be cooled by providing a water cooling device on the outer periphery of the stator, but since the rotor 3 rotates at high speed, it is impossible to cool it by providing a water cooling device like the stator. . Further, since only laser gas of about 0.1 atm exists inside the motor, hardly any cooling effect by air cooling can be expected.

Therefore, the heat generated by the rotor 3 is transmitted through the shaft 2,
Bearings 5 and 6 fixed to shaft 2 are heated to increase the temperature of the bearings. The bearing operates without problems up to a temperature of approximately 80°C, but when the temperature exceeds this temperature, there is a problem in that the life of the bearing is halved for every 10°C increase.

This is due to the fact that the bearing lubricant deteriorates due to high temperatures.

Therefore, if the operation is continued in this state, there is a problem that the bearing will be destroyed. Therefore, usually 1
Grease was replenished and the bearings themselves were replaced every 1,000 hours. Therefore, conventionally, a great deal of effort has been spent on such maintenance.

Furthermore, the heat transmitted to the bearings 5 and 6 causes the grease to vaporize. The vaporized grease mixes into the laser gas and contaminates optical components, causing problems such as a decrease in laser output and mode deformation.

The present invention has been made in view of these points, and an object of the present invention is to provide a laser turbo blower and a laser oscillation device using the same, which suppress the temperature rise of the bearing and have excellent reliability and maintainability. do.

[Means to solve the problem]

In order to solve the above problems, the present invention includes a shaft having a turbo blade at its tip, a bearing that supports the shaft,
A laser turbo blower comprising a motor for rotating the shaft, wherein the shaft comprises first and second shafts torque-coupled via a magnetic coupling, and the turbo blade is connected to the first shaft. Provided is a turbo blower for a laser, characterized in that the motor is provided on the second shaft.

Furthermore, the present invention provides a laser oscillation device using the above laser turbo blower.

[Effect]

The shaft is composed of a first shaft and a second shaft which are torque-coupled via a magnetic coupling, a turbo blade is provided on the first shaft, and a motor serving as a heat source is provided on the second shaft. The rotational torque of the motor is transmitted to the turbo blade side via the magnetic coupling, but the heat generated by the motor is thermally blocked by the magnetic coupling. by this,
Heat from the motor is no longer transmitted to the bearing on the first shaft side, where no air cooling effect can be expected.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram showing the configuration of a first embodiment of a laser turbo blower according to the present invention. Components that are the same as those in FIG. 5 are given the same reference numerals, so a description thereof will be omitted. Here, the turbo blade 1 is shown as a centrifugal blade, but it may be a diagonal flow blade or an axial flow blade.

The essential difference between this embodiment and the conventional one is that the shaft is connected to the first and second shafts, which are torque-coupled by magnetic coupling.
The first shaft 21 is composed of shafts 21 and 22.
Bearings 5 and 6 are provided on the second shaft 22, and the rotor 3 and stator 4 that constitute the motor are provided on the second shaft 22.

Furthermore, in this embodiment, the housing constituting the laser turbo blower is divided into two housings: a bearing housing 11 and a motor housing 12.

The bearing housing 11 accommodates a first shaft 21 to which the turbo blade 1 is attached, and bearings 5 and 6 that hold the first shaft 21. The bearing housing 11 is under the laser gas and sealed on both sides by O-rings 9 and 10.

The motor housing 12 includes a second shaft 22 and a second shaft 22 .
Bearings 13 and 14 that hold the shaft 22, and a motor consisting of a rotor 3 and a stator 4 are housed. Motor housing 12 is provided under atmospheric pressure. Stator 4
A water cooling pipe 15 for cooling the stator 4 is provided around the stator 4 .

Between the bearing housing 11 and the motor housing 12, the rotational torque of the second shaft 22 is transferred to the first shaft 2.
1 is provided.

The magnetic coupling consists of a magnetic pole 16 and a cylindrical yoke 17. The magnetic pole 16 rotates in accordance with the rotation of the cylindrical yoke 17, and the rotational torque of the motor is transferred from the second shaft 22 to the first shaft.
is transmitted to the shaft 21 of. A partition wall 18 is provided between the magnetic coupling, that is, between the magnetic pole 16 and the cylindrical yoke 17, for hermetically sealing the laser gas within the bearing housing 11.

Since the first and second shafts 21 , 22 are thus thermally isolated by the magnetic coupling, the heat generated in the rotor 3 is not transferred to the bearings 5 and 6 .

The second shaft 22 heated by the rotor 3 is cooled by forced air cooling such as compressed air. Furthermore, since there is no fear of contamination, oil lubrication such as oil mist or oil jet may be used.

Further, the magnetic coupling has a magnetic pole 16 on the first shaft 21 side, and a cylindrical yoke 17 in which an eddy current is generated on the second shaft 22 side. Therefore, the first shirt)2
1 is not affected by heat generation due to eddy currents.

FIG. 2(a) is an axial cross-sectional view showing details of the magnetic coupling, and FIG. 2(b) is a cross-sectional view taken along the line AA in FIG. 2(a).

The magnetic pole 16 consists of a hollow disk-shaped magnet 19 and disk-shaped yokes 23 and 24 that sandwich the magnet 19 from both sides. The second shaft 22 side of the magnet 19 is a north pole, and the first shaft 21 side is a south pole. The disk yokes 23 and 24 form a magnetic path, and the magnetic flux 20 from the magnet 19 is transferred to the cylindrical yoke 17.
tell to. The magnetic pole 16 is fastened to the first shaft 21 by a non-magnetic stainless steel bolt 26 so that a magnetic path is not formed along the central axis. The disc yokes 23 and 24 and the cylindrical yoke 17 are configured so that their teeth mesh with each other.

The partition wall 18 consists of a hollow disk 27, a cylinder 28, and a disk 29. Both the hollow disk 27 and the disk 29 are made of stainless steel, and the cylinder 28 is made of an insulator such as glass. cylinder 28
The reason why is made of an insulator is to prevent eddy current from being generated in the partition wall 18 due to the magnetic flux 20. This is because when an eddy current occurs, the partition wall 18 itself generates heat, reducing the cooling effect.

Here, the torque τ of the magnetic coupling can be approximately calculated using the principle of virtual work as shown in the following equation.

τ= (Ea-Eb)/dθ Ea is the energy when the external teeth and internal teeth of the magnetic coupling match, Eb is the energy when the external teeth and internal teeth of the magnetic coupling do not match, dθ is the rotor rotation angle (expressed in mechanical angle) between the two.

The above equation shows the average transmitted torque between when the teeth are aligned and when they are not aligned.

Further, the magnetic energy Em is expressed as Em=f v B−Hd v using the magnetic flux density B and the magnetic field strength H.

Now, the dimensions of the magnetic coupling shown in FIG. 2 are set as follows.

The magnet 19 has an inner diameter of 1Q mm and an outer diameter of 28 mm. The diameter of the teeth of the disc-shaped yokes 23 and 24 is 34 mm. The diameter of the tooth portion of the cylindrical yoke 17 is 38 mm,
The diameter of the slot portion is 42 mm. The outer diameter of the cylindrical yoke 17 is 44 mm. Therefore, the cylindrical yoke 1
The wall thickness of the tooth portion 7 is 3 mm, and the wall thickness of the slot portion is 1 mm. The lengths of the tooth and slot portions of the cylindrical yoke 17 are made equal. Magnet 19 and disk-shaped yoke 2
The thicknesses of 3 and 24 are each 3 mm.

Assuming such magnetic coupling, when magnetic energies Ea and Eb are analyzed using the finite element method, Ea=1.2459 (J/rad) Eb=0.86
70 (J/rad>dθ=π/4(rad). Therefore, the transmitted torque τ is 0.48248Nm
(0,04923kg fm).

The torque required for the turbo blower is approximately 0.019 k
Since g f'm, torque can be sufficiently transmitted by this magnetic coupling even if the safety factor is set to 2.5 times.

FIG. 3 is a diagram showing the configuration of a second embodiment of the laser oscillation device of the present invention. In this embodiment, an oil film damper is attached around the bearings 5, 6, 13 and 14 of the laser turbo blower shown in FIG. 1 to absorb the vibrations of the bearings.

The oil film damper consists of sleeve 51 and O-ring 5.
2 and 53, and oil filled between the bearing housing 11 and the sleeve 51.

The inner rings of the rolling bearings 5 and 6 are fixed to the first shaft 21, and the outer rings are fixed to the sleeve 51. The inner rings of the rolling bearings 13 and 14 are fixed to the second shaft 22, and the outer rings are fixed to the sleeve 51. There is a gap of 10 to 100 μm between the bearing housing 11 and the sleeve 24.
A gap is provided and filled with grease or oil.

The O-rings 52 and 53 are for blocking the laser gas from grease or oil filled in the gap.

With this configuration, vibrations caused when the turbo blade 1 and the shirt 21 rotate at high speed are attenuated by the hydrodynamic damping effect of the oil film damper.

This oil film damper may be provided only on the bearings 5 and 6 of the first shaft 21.

Although rolling bearings have been described in the above embodiments, ball bearings or roller bearings may also be used. Furthermore, a ceramic bearing using ceramic as the bearing material may be used.

As described above, according to this embodiment, since the temperature rise in the bearing part is suppressed, the life of the bearing is extended from 500 to 1,000 hours to 5,000 to 15,000 hours. Also, maintenance such as replacing bearings and grease becomes unnecessary.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to suppress the temperature rise in the bearing part, and there is no need for maintenance such as regular replenishment of grease or replacement of the bearing and grease, and reliability and maintainability are improved. It becomes possible to provide a turbo blower for lasers.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of a laser turbo blower according to the first embodiment of the present invention. FIG. 2 is a sectional view taken along the line A-A in FIG. 3 (a), FIG. 3 is a diagram showing the structure of a laser turbo blower according to the second embodiment of the present invention, and FIG. 4 is a conventional carbon dioxide (CO2) gas laser oscillation device. Figure 5 is a diagram showing the overall configuration of a conventional laser turbo blower. 1 - Turbo blade 2.21.22 ・ Shaft 3 ・ Rotor 4 --- Stator 5.6.13.14 ・ Bearing 9.10.52.53° ゛ ・ O-ring 11
Bearing housing 12 ゛ Motor housing 15 Water-cooled tube 16 Magnetic pole 17 ...-°・Cylindrical yoke 18 Partition wall 19 ... Magnet 20 ・Magnetic flux 24°・'' Disc-shaped yoke 26 Stainless steel bolt 31 ・Discharge tube 32 Output coupling mirror 33° Total reflection mirror 34. 35 --- Electrode 36 - High frequency power supply 38 ・ Cooler 39 Air blower 40 - Gas cylinder 42 ゛ Vacuum pump 43 °・° Laser beam optical axis in resonator 23. 37, °・° ° Resonator Outer laser beam optical axis

Claims (8)

[Claims] (1) In a laser turbo blower comprising a shaft having a turbo blade at the tip, a bearing that supports the shaft, and a motor for rotating the shaft, the shaft is torque-coupled via a magnetic coupling. the turbo blade is provided on the first shaft, and the motor is provided on the second shaft.
A turbo blower for lasers, characterized in that it is installed on the shaft of. (2) a first housing that accommodates the first shaft; a second housing that accommodates the second shaft and the motor;
and a partition wall provided in the gap of the magnetic coupling for air-tightly sealing the laser gas in the first housing. turbo blower for lasers. (3) The laser turbo blower according to claim 1, wherein the magnetic coupling has a magnet on the first shaft side and an eddy current plate on the second shaft side. (4) The turbo blower for a laser according to claim 1, 2, 3, or 4, characterized in that an oil film damper is provided on the bearing. (5) The laser turbo blower according to claim 1, 2, 3, or 4, wherein the bearing is a ball bearing. (6) A laser turbo blower as set forth in claim 1, 2, 3, or 4, wherein the bearing is a roller bearing. (7) The laser turbo blower according to claim 1, 2, 3, or 4, wherein the bearing is a ceramic bearing. (8) A laser oscillation device comprising a discharge tube that excites the laser by gas discharge, an optical resonator that causes laser oscillation, and a gas circulation device that forcibly cools the laser gas using a blower and a cooler, wherein the blower is A laser oscillation device comprising the laser turbo blower according to any one of claims 1 to 7.