JP2783151B2 - CO gas laser device, electrode cooling structure thereof, and electrode cooling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cooling of an electrode in a CO gas laser device, and more particularly to a cooling structure of an electrode using a laser gas in a triaxial orthogonal type subsonic flow discharge excitation type CO gas laser device. About the method.

[0002]

2. Description of the Related Art A three-axis orthogonal type subsonic flow discharge pumped CO gas laser apparatus comprises a rod-shaped pin electrode and a plate-shaped electrode which are opposed to each other with the stream line interposed therebetween in a direction orthogonal to the stream line of the laser gas. A laser beam reflected between the reverberating mirror and the output mirror facing each other with the streamline interposed between the direction of the streamline of the laser gas and the direction perpendicular to both the direction of the discharge and the direction of the streamline of the laser gas. From the output mirror.

FIG. 3 is a diagram showing an electrode cooling structure in a conventional CO gas laser apparatus of this kind. This figure is a simplified view of the one shown in Japanese Utility Model Laid-Open No. 45950/1984. A laser gas, which is a mixed gas of N ₂ , O _2, and CO, circulates at high speed through a laser gas flow path 10 composed of a laser gas pipe 9. When a DC voltage is applied between the plus terminal 13 and the minus terminal 14, a discharge occurs between the pin electrode 2 and the plate-like electrode 7, causing the reflection mirror and the output mirror facing in the direction perpendicular to the paper to resonate. As a result, laser oscillation occurs, and laser light is emitted from the output mirror. This CO
The gas laser device is capable of continuous oscillation of 2 kW, and is used for a laser processing machine for precisely processing metal.

In general, the output of the laser beam of the CO gas laser device depends on the temperature of the pin electrode 2, and the output decreases as the temperature increases due to the discharge. The cooling water channel 8 is
The pin electrode 2 is placed in an insulator 3 that insulates the pin electrode 2 from the housing.
Is a cylindrical hole formed in a direction perpendicular to the longitudinal axis of the cylinder, and is composed of two parallel holes. The pin electrode 2 is cooled by cooling water flowing through the water channel 8. In FIG. 2, only one pin electrode 2 appears, but a plurality of pin electrodes 2 are arranged at regular intervals in a direction perpendicular to the paper surface.
The plurality of pin electrodes 2 are cooled by cooling water flowing through the water channel 8.

[0005]

In the conventional electrode cooling structure shown in FIG. 3, the pin electrode 2 is cooled by flowing cooling water near the pin electrode 2. With this cooling structure, even if it is cooled most efficiently, it can only be cooled to the temperature of the cooling water. The temperature of the cooling water is at least 0 at atmospheric pressure.
℃, the conventional electrode cooling structure, 0 ℃ pin electrode
It cannot be cooled below.

The temperature of the laser gas is about 100 K (absolute temperature) which is the temperature of liquid nitrogen. Therefore, by projecting the tip of the pin electrode 2 into the laser gas flow path 10 and exposing the pin electrode 2 to a very low-temperature gas of about 100 K flowing at high speed, the temperature of the pin electrode 2 can be cooled to a very low temperature of about 100 K. However, if the temperature is cooled down to about 100 K, the temperature of the pin electrode 2 becomes too low and the discharge becomes unstable, so that a stable laser beam cannot be obtained.

As described above, in the conventional electrode structure and method of the CO laser device, the temperature of the pin electrode 2 is set to 0 ° C.
Below, it was not possible to set it in the range of 100K or more. It is experimentally clear that the temperature of the pin electrode at which the laser output is high and the discharge occurs stably is 0 ° C. or less and 100 K or more. However, there is a problem to be solved in providing a simple electrode cooling structure and a method capable of setting the temperature of the pin electrode within the temperature range.

[0008]

The present invention provides the following means for solving the above-mentioned problems.

A discharge is generated between a rod-shaped pin electrode and a plate-like electrode opposed to each other with the stream line interposed therebetween in a direction perpendicular to the stream line of the laser gas, and the direction of the line flow and the direction of the discharge are generated. In a CO gas laser device for emitting laser light reflected from the output mirror between a reflecting mirror and an output mirror facing each other with the streamline interposed therebetween in a direction orthogonal to both sides of the streamline, the laser gas circulation path A branch is provided on the upstream side of the laser gas flow from the region where the discharge occurs, and the laser gas circulation flow path is divided into a main flow path reaching the discharge area and a sub flow path narrower than the main flow path, The main flow path and the sub flow path are merged downstream from the discharge region, the thickness of a part of the insulator covering the side surface of the pin electrode is reduced, and the thinned surface of the insulator is connected to the wall surface of the sub flow path. Feature CO gas laser device.

[0010] The CO gas laser device according to the above, wherein a heater is disposed in the sub-flow passage at a position upstream of the pin electrode.

Means for detecting the temperature of the pin electrode;
The CO gas laser device according to the above, further comprising: a calorific value control unit that controls a calorific value of the heater in accordance with the temperature and suppresses a variation in the temperature of the pin electrode within a certain range.

A discharge is generated between a rod-shaped pin electrode and a plate-like electrode opposed to each other with the streamline interposed therebetween in a direction perpendicular to the streamline of the laser gas, and the direction of the linear flow and the direction of the discharge In a structure for cooling the pin electrode in a CO gas laser device that emits laser light reflected between the reflecting mirror and the output mirror facing each other with the streamline interposed therebetween from a direction orthogonal to both, from the output mirror, Dividing the circulating laser gas into a main flow path and a sub flow path, causing the discharge in the main flow path, providing a sub flow path near the pin electrode, and providing a thin insulator between the sub flow path and the pin electrode. The electrode cooling structure of the CO gas laser device, wherein the thickness of the insulator is such that the pin electrode is cooled by the laser gas in the sub-flow path.

A discharge is generated between a rod-shaped pin electrode and a plate-like electrode opposed to each other with the stream line interposed therebetween in a direction perpendicular to the stream line of the laser gas, and the direction of the line flow and the direction of the discharge are generated. A method of cooling the pin electrode in a CO gas laser device that emits laser light reflected between a reflecting mirror and an output mirror facing each other with the streamline interposed therebetween in a direction orthogonal to both, from the output mirror, In addition to the main flow path including the area where the discharge occurs, a sub-flow path that bypasses the main flow path is provided, and a laser gas flows through the main flow path and the sub-flow path. CO gas that branches off from the main flow path and joins the main flow path downstream of the discharge region, and cools the pin electrode with the laser gas flowing through the sub flow path through the insulating coating of the pin electrode. Laser equipment Electrode cooling method in.

[0014]

In the present invention, the circulating laser gas flow path is branched into a main flow path and a sub flow path, discharge for laser excitation is caused in the main flow path, and the sub flow path is passed near the pin electrode.
The thickness of the insulator is set so that the pin electrode and the sub flow path are separated by a thin insulator, and the pin electrode is cooled by a cryogenic laser gas flowing through the sub flow path. By the operation of such a configuration, the temperature of the pin electrode can be set in a range of 0 ° C. or less and 100 K or more.

By providing a heater upstream of the pin electrode in the sub flow path, the temperature of the laser gas flowing near the pin electrode is raised to a temperature higher than the laser gas temperature in the main flow path, and the temperature of the pin electrode is set to a preferable value. Set to
A stable large output laser beam can be obtained.

By detecting the temperature of the pin electrode, controlling the amount of heat generated by the heater in accordance with the detected temperature, and suppressing the temperature of the pin electrode within a certain range, the magnitude of the laser beam output and the stabilization of discharge can be improved. Thus, the temperature of the pin electrode can always be controlled optimally.

[0017]

The present invention will be described in more detail with reference to the following examples.

FIG. 1 is a sectional view of a CO gas laser apparatus according to one embodiment of the present invention, and FIG. 2 is a sectional view taken along the line aa 'in FIG.

The CO gas laser apparatus shown in FIG. 1 has a laser gas pipe 9 forming a laser gas flow path 10 made of a mixed gas of N ₂ , O ₂ and CO, and a laser gas flow path 10 connected to a main flow path 20. A rectifying plate 5 for branching the laser gas flow B in the main flow path 20 and a rectifying plate 5 for diverging the laser gas flow B into the main flow path 20; Mirror 11, output mirror 12, pin electrode 2
, Plate-like electrode 7, plus terminal 13, minus terminal 1
4 and a heater 4.

FIG. 1 is a sectional view taken along a plane passing through the axis of the pin electrode 2 and passing through the axis of the laser gas tube 9. However,
Since the pin electrode 2 has a columnar shape, it is drawn not in a cross section but in a front view. 1 and 2, the thickness of the laser gas pipe 9 is not drawn, but only the inner wall surface of the laser gas pipe 9 is drawn. 1 and 2 denote portions which appear as corners on the inner wall of the laser gas tube 9. In FIG. 1, it can be seen that the upper tube wall of the laser gas tube 9 is bent at a gentle angle at four points indicated by E1 to E4. There are five pin electrodes 2, and each pin electrode 2 is embedded in an insulator 3. An insulator 3 is provided above the pin electrode 2.
Form a quadrangular prism, and the quadrangular prisms made of the insulator 3 are arranged at an interval from each other, the interval between the quadrangular prisms forms a part of the sub-flow path 21, and the laser gas flow B Flows.

In this embodiment, as described above, the laser gas flow path 10 has the main flow path 20 and the sub flow path 21. The circulating laser gas flow splits into A and B upstream of the discharge area 1 (corresponding to the above-described discharge area) and merges again downstream.

A DC voltage is applied between the pin electrode 2 and the plate electrode 7 via the terminals 13 and 14. When a DC voltage is applied in this manner, the three-axis orthogonal subsonic flow discharge excitation type CO gas laser apparatus of the embodiment of FIG. Rod-shaped pin electrode 2 and plate-shaped electrode 7
Between the reflecting mirror 11 and the output mirror 12 which face each other with the stream line interposed therebetween in a direction perpendicular to both the direction of the stream line of the laser gas and the direction of the discharge. The laser light 6 is emitted from the output mirror 12.

In this embodiment, the insulator 3 covering the pin electrode 2 forms a quadrangular prism above the pin electrode 2, and the insulator 3 covering the pin electrode 2 is thin at the portion of the quadrangular prism. The heat of 2 is taken by the laser gas flow B in the sub-flow path via the insulator 3 by conduction, and the pin electrode 2 is cooled. The temperature of the laser gas is extremely low, about 100K, which is close to the temperature of liquid nitrogen N2.
Since the discharge becomes unstable if it is cooled down to the extent that the laser gas flow B in the sub flow path 21 is heated by the electric heater 4 in the present embodiment, the electric heater 4 is not practical.

By adjusting the temperature of the laser gas flow B, the temperature of the pin electrode 2 can be arbitrarily set, and the temperature of the pin electrode 2 is adjusted to an optimum temperature from the viewpoint of the output of the laser beam 6 and the ease of occurrence of discharge. Can control.

A temperature detecting element is buried in the insulator 3 near the pin electrode 2 to detect the temperature of the pin electrode 2, and the current flowing through the heater 4 is controlled in accordance with the detected temperature, so that the heater 4 generates heat. By controlling the amount and controlling the temperature fluctuation of the pin electrode 2 within a certain range, a stable output laser beam 6 can always be obtained.

[0026]

As described above in detail with reference to the embodiments, according to the present invention, the temperature of the pin electrode can be controlled to an arbitrary value within a range of 100 K or more at a temperature of 0 ° C. or lower, thereby stabilizing discharge. The present invention can provide a CO gas laser device capable of outputting laser light having a stable power for a long time, an electrode cooling structure thereof, and an electrode cooling method.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line a-a 'in the embodiment of FIG.

FIG. 3 is a cross-sectional view showing an electrode cooling structure in a conventional CO gas laser device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge area 2 Pin electrode 3 Insulator which supports electrode 4 Heater 5 Rectifier plate 6 Laser beam 7 Plate electrode 8 Cooling channel 9 Laser gas pipe 10 Laser gas channel 11 Reflecting mirror 12 Output mirror 13 Positive electrode 14 Minus electrode 20 Main flow path 21 Sub flow path

Claims (5)

(57) [Claims] 1. A discharge is caused between a rod-shaped pin electrode and a plate-like electrode facing each other with a streamline interposed therebetween in a direction orthogonal to a streamline of a laser gas, and the direction of the line current and the discharge In a CO gas laser device that emits laser light reflected from the output mirror and between the reflecting mirror and the output mirror facing each other with the streamline interposed therebetween in a direction orthogonal to the direction of the laser gas, Providing a branch on the upstream side of the laser gas flow from an area where the discharge occurs,
Dividing the circulation path of the laser gas into a main flow path leading to the discharge area and a sub flow path narrower than the main flow path, merging the main flow path and the sub flow path downstream from the discharge area, and forming a side surface of the pin electrode. A CO gas laser device, wherein the thickness of a part of the insulator covering the thin film is reduced, and the surface of the thinned insulator is part of the wall surface of the sub-flow path. 2. The CO gas laser device according to claim 1, wherein a heater is arranged in the sub-flow passage at a position upstream of the pin electrode. 3. A means for detecting a temperature of the pin electrode;
The CO gas laser device according to claim 2, further comprising: a heat generation amount control unit that controls a heat generation amount of the heater according to the temperature and suppresses a fluctuation in the temperature of the pin electrode within a certain range. 4. A discharge is generated between a rod-shaped pin electrode and a plate-like electrode facing each other with the streamline interposed therebetween in a direction perpendicular to the streamline of the laser gas, and the direction of the line current and the discharge A structure for cooling the pin electrode in a CO gas laser device that emits, from the output mirror, laser light reflected between a reflecting mirror and an output mirror facing each other with the streamline interposed therebetween in a direction orthogonal to the direction of In the method, the circulating laser gas is divided into a main flow path and a sub flow path, the discharge is caused in the main flow path, a sub flow path is provided near the pin electrode, and the space between the sub flow path and the pin electrode is thin. The electrode cooling structure in a CO gas laser device, wherein the thickness of the insulator is such that the pin electrode is cooled by the laser gas in the sub-flow path. 5. A discharge is generated between a rod-shaped pin electrode and a plate-like electrode facing each other with the streamline interposed therebetween in a direction perpendicular to the streamline of the laser gas, and the direction of the line current and the discharge A method of cooling the pin electrode in a CO gas laser device that emits, from the output mirror, laser light reflected between a reflecting mirror and an output mirror facing each other with the streamline interposed therebetween in a direction orthogonal to both directions In addition to the main flow path including the region where the discharge occurs, a sub flow path that bypasses the main flow path is provided, a laser gas flows through the main flow path and the sub flow path, and the sub flow path is upstream from the discharge area. At the downstream of the discharge region, the main electrode is branched from the main flow path, so as to join the main flow path, and the laser gas flowing through the sub flow path is cooled through the insulating coating of the pin electrode, thereby cooling the pin electrode. CO gas laser Electrode cooling method in location.