JPH0652813B2 - Carbon dioxide laser oscillator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon dioxide laser oscillator for processing used for welding, surface treatment and cutting.

2. Related Art FIG. 2 shows a conventional example of a gas circulation system of a high-speed axial flow type carbon dioxide gas laser oscillator using a roots blower. Reference numeral 1 is a discharge tube, 2 is a roots blower, and the laser medium gas circulates at high speed in the direction indicated by the arrow in the figure by the rotation of the rotor contained in the rotor chamber 4. An oil seal 5 seals the shaft with an intermediate chamber (gearbox) 3 that is a drive unit of the rotor. Depressurize the gas system to a constant pressure,
Use a vacuum pump 6 to maintain some fresh gas 7
Is being supplied. Solenoid valves SL1, SL2 when power is turned on
Open, the solenoid valve SL3 is closed, the system is evacuated, the solenoid valve SL4 with a needle valve is opened after a certain time (the solenoid valve SL5 with a needle valve is closed), and fresh gas is introduced into the gas system. Is maintained at a constant pressure and operation is performed. After the operation is completed, the solenoid valves SL1, SL2, SL4 are closed, and the solenoid valve SL5 is opened. The gas system is pressurized by the laser medium gas and stopped through this solenoid valve SL5, and the impure gas from the outside is introduced into the system. The mixture was prevented. For constant pressurization at this time, the solenoid valve SL3 is opened and the relief valve 8 determines the pressurization state. At the time of pressurization in the system, the inside of the roots blower 2 is also pressurized by the laser medium gas, but the pressurization into the intermediate chamber 3 is performed through the lip surface of the oil seal 5.

Problems to be Solved by the Invention At this time, in the conventional system, a pressure difference is generated between the intermediate chamber 3 and the rotor chamber 4 of the roots blower 2 in a transient state in which the medium gas pressure changes immediately after the start and stop of the operation. An unstable state is likely to occur, and oil mist mixes into the rotor chamber 4 of the roots blower 2 via the lip surface of the oil seal 5, circulates in the gas system, and discharge electrodes and mirrors incorporated in the oscillator are used. There is a problem that the laser output is reduced due to the contamination by the oil mist.

Means for Solving the Problems In order to solve the above problems, the carbon dioxide gas laser oscillator of the present invention has a flow path for introducing or decompressing a medium gas so that the rotor chamber of the roots blower and the gear box are simultaneously pressurized. The chamber and the gearbox are provided with an adjusting valve for adjusting the pressure in each of the flow paths.

By the above means, the medium gas flows in and out of the rotor chamber and the gearbox through the flow path, the medium gas pressures of the rotor chamber and the gearbox become equal, and the oil mist in the gearbox does not enter the rotor chamber.

Example An example of the present invention will be described below with reference to FIG.

In FIG. 1, the same components as those shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

At the start of operation, the system is once evacuated to a vacuum state before introducing the laser gas into the system. At this time, the total volume of the system used in this example is about 150, and the volume of the intermediate chamber 3 is about 20.
Simultaneous depressurization reduces the pressure in the intermediate chamber 3 as much as possible in the transient state, applying a large reverse pressure to the lip surface of the oil seal 5 and drying the lip surface (oilless).
Since the oil seal 5 is likely to be in an inconvenient state, when decompressing the intermediate chamber 3, the solenoid valve 8 with a needle valve is adjusted so as to reduce the exhaust speed in the intermediate chamber 3, and the difference in the system volume is adjusted. Is performed by adjusting the exhaust speed to eliminate the pressure difference between the intermediate chamber 3 and the entire system during the pressure reduction transition period. At the same time, after the operation is stopped, the inside of the system is kept under pressure by the laser medium gas to prevent the contamination of the impure gas, but this pressurized system is also filled with the laser medium gas from the conventional oil seal lip surface. In order to prevent back pressure on the lip surface and dryness of the lip surface, a total system internal volume and an intermediate chamber system internal volume are provided separately from the solenoid valve SL5 with a needle valve for filling pressurized gas into the system. The solenoid valve SL6 with a needle valve that can have a constant pressure at a constant time depending on the ratio is used for the intermediate chamber pressurizing system. Further, by using the relief valve 9 in the intermediate chamber 3 in parallel with the relief valve 8 for adjusting the pressure in the entire system, there is no pressure difference between the intermediate chamber 3 and the entire gas system even in the pressurized state. It is like that. In addition, 7 is a cylinder containing a medium gas.

Effects of the Invention As described above, according to the present invention, the following excellent effects are exhibited.

(1) When deaerating the system to a vacuum state, the difference between the total system volume and the intermediate chamber volume is adjusted by the solenoid valve with a needle valve provided in the intermediate chamber system to adjust the exhaust speed of the intermediate chamber to Even in the transient state, the pressures of both systems are always the same, and it is possible to prevent gas from flowing in and out of the oil seal.

(2) Even after pressurizing with laser medium gas after operation is stopped, the above-mentioned solenoid valve with a needle valve ensures that both the entire system and the intermediate system have the same pressure even in the transient state of pressurization. In addition, by providing a relief valve for adjusting the pressure inside the system to both systems, a pressure difference is not generated even in the pressurized state between the entire system and the intermediate chamber system, and the gas from the oil seal is prevented. By preventing entry / exit, contamination by oil mist from the lip surface of the oil seal can be prevented. Contamination by oil mist on the discharge electrodes, mirrors, etc. can be prevented, so that a reduction in laser output can be prevented and a stable oscillator can be provided. Can be provided.

[Brief description of drawings]

FIG. 1 is a gas circuit diagram of a carbon dioxide gas laser oscillator showing an embodiment of the present invention, and FIG. 2 is a gas circuit diagram of a conventional carbon dioxide gas laser oscillator. 2 ... Roots blower, 3 ... Intermediate chamber (gear box),
4 ... Rotor room.

Claims (1)

[Claims] 1. In a carbon dioxide laser oscillator for circulating a medium gas, a transient state in which the medium gas pressure changes and a steady state in which the medium gas pressure is constant, as well as a rotor chamber of a roots blower for circulating the medium gas and a gearbox are simultaneously provided. A flow path for introducing or depressurizing the medium gas to have the same pressure is provided in the rotor chamber and the gearbox, and the exhaust speed is adjusted during depressurization in consideration of the volume ratio of the entire system volume and the intermediate chamber volume. A carbon dioxide laser oscillator in which a solenoid valve with a needle valve that eliminates the pressure difference between the entire system and the intermediate chamber system and a relief valve as a pressure control valve to maintain the pressurized state are installed in both systems.