JPH02103980A - Gas-laser oscillating apparatus - Google Patents

Abstract

PURPOSE:To make a blower compact, to absorb vibration pulsating flow and to obtain stable laser light source by forming the blower with 7 turbo blades, and using a grease-filled squeezed film dampers for the bearings for a driving shaft of the blower. CONSTITUTION:A cooling blower is formed of turbo blades 16. The blades are turned at a high speed with a shaft 17. Ball bearings are used for the bearings of the shaft 17. Inner rings 22 and 23 are fixed to the shaft 17, and outer rings 26 and 27 are fixed to sleeves 28 and 29. Specified gaps are provided between the sleeves 28 and 29 and bearing housings 34 and 35. The gaps are filled with grease, and squeezed film dampers are formed. As the damper material, grease whose vapor pressure is low is used. The dampers are shielded from the outside with O-rings 30 to 33 for preventing the splashing of the grease. In this way, the blower can be made compact, and a stable laser light source wherein resonant vibration is eliminated by the dampers can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a processing Go! The present invention relates to a high-output gas laser oscillation device such as a laser, and more particularly to a gas laser oscillation device that is an improved turbo blower used in a CO□ laser.

[Conventional technology]

FIG. 3 shows the configuration of a CO□ laser according to the prior art. In FIG. 3, an output coupling mirror 2 and a total reflection mirror 3 are installed at both ends of a discharge tube 1. Further, two metal electrodes 4 and 5 are attached to the outside of the discharge tube, and a high frequency voltage is applied between them by a high frequency type aI6. At this time, a high frequency glow discharge is generated within the discharge tube and laser excitation is performed. The optical axis of the laser beam inside the resonator is indicated by 13, and the optical axis of the laser beam taken out from the output coupling mirror 2 is indicated by 14.

When the laser oscillation device is started, the entire interior of the device is first evacuated by the vacuum pump 12. Then, the valve 11 is opened, and a predetermined flow rate of laser gas is led from the cylinder IO, and the gas pressure inside the device reaches the specified value, after which the vacuum pump 1
Since the exhaust gas and the supply gas introduced in step 2 continue, part of the laser gas is continuously replaced with fresh gas while the gas pressure is maintained at the specified value, thereby preventing gas contamination.

Furthermore, in FIG. 3, a roots blower 9 circulates the laser gas within the apparatus. Its purpose is to cool the laser gas. About 20% of the injected electrical energy in CO□ laser
One part is converted into laser light and the other part is used for gas heating. However, according to theory, the laser oscillation gain is -(3/2) of the absolute temperature T.
), so forced cooling of the laser gas is necessary to increase the oscillation efficiency. Laser gas is about 10
The gas passes through the discharge tube at a flow rate of 0 m/sec (in the direction shown by the arrow) and is guided to the cooler 8. Here, the heating energy due to the discharge is mainly removed. In the Roots blower 9, compression heat is generated, so the gas flows through the discharge tube. It passes through a cooler 7 before being redirected to 1.

Since these coolers are of the normal type, their explanation will be omitted here.

[Problem to be solved by the invention]

However, the conventional technology has the following problems.

First, since the Roots blower is a positive displacement blower that rotates at a low speed, it is excessive in size and weight, making the laser oscillator itself excessively large.

Second, there is a pulsating flow in the airflow, which affects the laser oscillation characteristics. Thirdly, there is also vibration, which affects the intensification stability of the laser beam.

On the other hand, if a turbo blower is rotated at high speed instead of a roots blower, the resonance vibration that occurs during high speed rotation will cause
There is a risk of damage to the turbo blower.

The present invention has been made in view of these points, and an object of the present invention is to provide a gas laser oscillation device that uses a turbo blower and prevents resonance vibration during high-speed rotation.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a gas laser that is composed of a discharge tube that excites the laser by gas discharge, an optical resonator that performs laser oscillation, and a gas circulation device that forcibly cools the laser gas using a blower and a cooler. Provided is a gas laser oscillation device, wherein the blower is composed of an electric motor-driven turbo blade that rotates in laser gas, and the electric motor drive bearing is a grease-filled squeezed film damper bearing. .

[Operation] The turbo blower allows the volume to be reduced in inverse proportion to the rotation speed. On the other hand, due to the braking effect due to the inelastic effect of grease etc. in the squeezed film damper bearing,
Prevent vibration.

〔Example〕

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

FIG. 1 shows an overall configuration diagram of a gas laser oscillation device according to an embodiment of the present invention. Portions common to the prior art shown in FIG. 3 are indicated by the same numerals and the operations are generally the same, so a description thereof will be omitted and only the different portions will be described. In place of the roots blower 9, a turbo blower 15 is used in FIG. Since the efficiency of the turbo blower is much higher than that of the roots blower, the heat of compression can be ignored, and the cooler 7 shown in the latter stage shown in FIG. 3 can be omitted, and although it is omitted in FIG. 1, it may of course be installed in some cases.

FIG. 2 shows an example of the configuration of a roots blower. Although centrifugal blades 16 are shown here, the turbo blades may be diagonal flow blades or axial flow blades. The turbo blades are mounted on a shaft 17 and driven by motors 19 and 20 installed in a housing 18 separate from the laser gas housing.
It rotates at a high speed of 10,000 RPM. Therefore, compared to a low-speed Roots blower, the volume is smaller in inverse proportion to the rotation speed.

The present invention is particularly characterized in that it prevents resonance vibrations that occur when the blower blades rotate at high speed. FIG. 2 shows one embodiment in which ball bearings are used. The inner rings 22, 23 of this ball bearing are fixed to the shaft 17.

24 and 25 indicate the balls of the bearing. There are actually many balls not shown in the diagram. 26.27 is the outer ring of the bearing, which is fixed to the sleeve 28.29.

A feature of the invention is that these sleeves 28,29 are not fixed to the bearing housing 34,35. If the sleeve is fixed to the housing, the following dangers arise: When the shaft 17 rotates, as the rotational speed increases, critical speeds of 1.2 and 3rd orders are sequentially encountered. If the rotational balance of a rotating body is not perfect, there is a possibility of destruction due to centrifugal force when the rotational speed passes through a critical speed. - For boat fishing, the third-order critical speed can be designed to be sufficiently high compared to the normal rotation speed, but the first and second-order vibrations must pass safely. Eliminating the need for extremely high precision rotational balancing and housing machining is an important issue.

In the present invention, the sleeve and the bearing housing are not fixed to each other, but a gap of 10 to 100 microns is provided between them, and grease is filled in the gap to damp vibrations generated in the sleeve by the inelastic effect of the grease. In FIG. 2, the grease 36 and 37 are shown with diagonal lines. In the present invention, the bearing is located in the laser gas, but contamination of the laser gas must be avoided, so a grease with low vapor pressure is used as the damper material, and the area where the grease exists is set to 0-0 to prevent the grease from scattering. Rings 30.31 and 32.
Thirty-three pairs are used to isolate it from the outside. Although an example using a ball bearing is shown here, a sliding bearing may also be used.

In addition, by adopting this type of damper structure, there is a gap of several tens of microns between the sleeve and the bearing housing, which eliminates the need for ultra-precision finishing that was previously required for housing machining, making machining extremely easy. Become. In FIG. 2, a cooling water coil 21 is provided around housings 34 and 35 for cooling the heat generated by the motor.

The present invention is particularly useful for high frequency discharge pumped COt lasers. In the case of DC discharge excitation, it is necessary to generate turbulence in the gas flow in order to obtain a uniform discharge, so the blower is required to have a high compression ratio, and a Roots blower is ideal for this purpose. On the other hand, high-frequency discharge excitation does not require turbulence, and the turbo blower's characteristics of low compression ratio and large airflow capacity are utilized.

〔Effect of the invention〕

As described above, in the present invention, a Roots blower is used and a squeezed film damper is used on the rotating shaft of the Roots blower, so that the blower and the entire device can be made smaller and lighter. In addition, vibration and pulsation are eliminated, and beam characteristics such as pointing stability and high-speed output stability are improved. Furthermore, it is possible to avoid destruction due to resonance vibration phenomena that are inevitable in high-speed rotating bodies.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a gas laser oscillation device according to an embodiment of the present invention, FIG. 2 is a diagram showing an example of the configuration of a turbo blower, and FIG. 3 is a configuration diagram of a conventional gas laser oscillation device. 4. 7, 1-・Discharge tube 2・−・−・−・・・Output coupling mirror 3−−−−−−
−1～・−・−Total reflection mirror 5・−1−−−−・・−1−−
--Electrode 6-----------1・-1----High frequency power supply 8------------Cooler 9-----Roots blower 0・−・−・
−・−・・・・−, #Sbonbeto−・−・−・・・
・-Valve■ 22.2 24.2 26, 2 28, 2 30-3 34, 3 36.3 2-・・-・−−−−−−1・Vacuum pump 3・・−・−
...--Intra-cavity laser beam optical axis 4...-
・−・・−Same laser beam optical axis 5−・−・・−−1−・−・Turbo blower 6 Turbo blade 7−・−・・−・−−−m−・・−Shaft 8・−・−
......-Drive system housing 9--...
−−・〜・Electric motor rotor 0・−・・・・・・・−・・
・・Electric motor stator ・・・・・・・・・Cooling water coil 3 −・−・−・−・−・・・・・Bearing inner ring 5
−・・・−・−・−Ball 7・−・−・・・Bearing outer ring 9・−・−・−1−−−・・−・−Sleeve 2−・・−
・−・−・−・0−Ring 5−・・−・・−・−・
−=Bearing housing 7−・−・−・−・・・Grease patent applicant Fanuc Co., Ltd. agent Patent attorney Takeshi Hattori Diagram 2 Procedural amendment (voluntary) 1゜Indication of incident 1988 Patent application No. 258055 No. 2゜Name of the invention Gas laser oscillation device 3゜Relationship with the person making the amendment case

Claims (4)

[Claims] (1) In a gas laser oscillation device consisting of a discharge tube that excites the laser by gas discharge, an optical resonator that performs laser oscillation, and a gas circulation device that forcibly cools the laser gas using a blower and a cooler, the blower is used to cool the laser gas. 1. A gas laser oscillation device comprising a turbo blade driven by an electric motor that rotates at a speed of 100 degrees, and characterized in that the bearing for driving the electric motor is a squeezed film damper bearing filled with grease. (2) The gas laser oscillation device according to claim 1, wherein the grease filling portion is sealed from the outside by an O-ring. (3) The gas laser oscillation device according to claim 1, wherein the bearing is a ball bearing. (4) The gas laser oscillation device according to claim 1, wherein the bearing is a sliding bearing.