JPH09186382A - Laser gas feed control method of gas laser oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a gas laser oscillator to be lessened in laser gas consumption and to operate continuously for many hours. SOLUTION: A gas laser oscillator 1 is equipped with a laser gas feed system which feeds laser gas, a laser gas exhaust system 25, and an output sensor 12 which detects the output of laser rays, wherein a laser gas feed control method is carried out through such a manner that procedures (a) to (c) are repeatedly performed. (a): The gas laser oscillator 1 is operated keeping a laser tube 3 sealed up. (b): The feed and exhaust of laser gas are started when the oscillator 1 reaches to a discharge shutdown time that it stops operating. (c): The feed and exhaust of laser gas are stopped when the gas laser oscillator 1 recovers its initial rated output, and the laser tube 3 is sealed up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser gas supply control method for a gas laser oscillator.

[0002]

2. Description of the Related Art In a gas laser oscillator, for example, a carbon dioxide gas laser oscillator, CO ₂ , N ₂ is used as a laser gas.
And a He gas are mixed in an appropriate ratio to confine a laser gas in a laser tube, which is called a so-called shut-off method, and a part of the laser gas deteriorated by the discharge is exhausted from the laser tube to the atmosphere. There is a so-called so-called laser gas replenishment system which is used while replenishing laser gas.

[0003]

Since the above-mentioned gas replenishment system always replenishes a new laser gas, it is possible to continuously operate the laser oscillator for a long time, but there is a problem that the laser gas consumption increases. . Also,
In the case of the shut-off method, if the laser gas is used for a certain period of time, the laser output deteriorates due to deterioration of the laser gas, and laser processing such as laser cutting or laser welding cannot be performed, so it is necessary to replace all the laser gas in the laser tube. There's a problem.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a laser gas replenishment control method for a gas laser oscillator capable of reducing the consumption of laser gas and continuously operating for a long time. It is to be.

[0005]

As a means for achieving the above object, a laser gas replenishment control method for a gas laser oscillator according to the present invention as set forth in claim 1 continuously supplies a laser gas from the gas laser oscillator under the control of a control device. And an exhaust system capable of exhausting gas intermittently or intermittently, and a gas replenishment system capable of continuously or intermittently replenishing the gas laser oscillator with a laser gas mixed in an appropriate ratio under the control of the controller. A gas laser oscillator including an output sensor for detecting a light output of a laser and inputting the light output to the control device includes the following steps.

(A) A step of operating a gas laser oscillator by keeping a laser gas in a sealed state (b) A step of starting laser gas replenishment and exhaustion when a defective cutting discharge time at which defective cutting occurs is reached (c) the gas laser When the output of the oscillator is restored to the initial rated output, the steps of replenishing and exhausting the laser gas to stop the laser tube 3 are closed (d) The steps (a), (b) and (c) are performed. Therefore, it is possible to continuously operate the gas laser oscillator for a long time without stopping the operation for exchanging the laser gas of the gas laser oscillator and reduce the consumption of the laser gas. Further, there is also an advantage that the life of the exhaust device is extended because the exhaust device does not have to be continuously operated.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an example of a carbon dioxide gas laser oscillator that can be used in the laser gas replenishment control method of the present invention. Referring to FIG. 1, the gas laser oscillator 1 includes a laser tube 3 for performing resonance amplification of the laser beam LB and a laser gas in which CO ₂ , N ₂ and He gas are mixed at an appropriate ratio into the laser tube 3. It is composed of a laser gas circulation device 5 for supplying and circulating.

An anode 7 and a cathode 9 for discharging are appropriately arranged in the laser tube 3, and a rear mirror 11 and an output mirror 13 are attached to the end of the laser tube 3. The anode 7 and the cathode 9 are connected to a high voltage power supply circuit 15 in order to generate a discharge between the anode 7 and the cathode 9. Further, the laser gas circulation device 5 is provided with a heat exchange device 17 for cooling the laser gas from the laser tube and a blower 19 for feeding the laser gas to the laser tube 3, and the laser gas circulation device 5 is provided in the laser tube 3. The laser gas return path 21 and the feeding path 23 are connected.

With the above structure, the blower 19 is driven to circulate the laser gas in the laser tube 3, and a high voltage is applied between the anode 7 and the cathode 9 from the high voltage power supply circuit 15 to cause discharge. The laser beam LB can be output from the output mirror 13 side.

An exhaust system 25 such as a vacuum pump is connected to an appropriate position of the gas return passage 21 in order to discharge a part of the laser gas deteriorated by the discharge between the anode 7 and the cathode 9. There is. On the other hand, a gas mixing tank 27 for replenishing fresh laser gas is connected to an appropriate position of the gas supply path 23. As shown in detail in FIG. 3, the gas mixing tank 27 contains CO ₂ , N ₂
A gas mixing system 29 for mixing various gases such as He and He in an appropriate ratio is connected. A plurality of gas cylinders 31A, 31B, 31C, ... Filled with the various gases are properly connected to the gas mixing system 29.

Therefore, a part of the laser gas deteriorated by the discharge in the laser tube 3 can be discharged from the exhaust system 25, and at the same time, a fresh laser gas can be replenished from the gas mixing tank 27.

Further, a control device 33 for appropriately controlling the high-voltage power supply circuit 15, the exhaust system 25 and the gas mixing system 29 is provided. The control device 33 is composed of a computer, a numerical control device, or the like, and various controls are preprogrammed in a memory in the control device 33. Therefore, the high-voltage power supply circuit 15 can appropriately apply a high voltage between the anode 7 and the cathode 9 under the control of the control device 33 to perform continuous oscillation or pulse oscillation. Further, the exhaust system 25 can exhaust part of the laser gas continuously or intermittently under the control of the controller 33. Furthermore, the gas mixing system 2
In 9, the various gases can be mixed continuously or intermittently at an appropriate ratio under the control of the controller 33 to replenish the laser tube 3.

The rear mirror 11 provided at the end of the laser tube 3 is provided with an output sensor 12 for detecting the laser output in real time. This output sensor 12
The micro laser beam extracted from the rear mirror 11 is converted into an electric signal and input to the control device 33. Since the transmittance of the rear mirror 11 is known, the laser output output from the output mirror 11 can be calculated by the controller 33 based on the input signal from the output sensor 12.

Now, the details of the exhaust system 25 are shown in FIG.
This will be described below. The exhaust system 25 includes a gas return path 2
A vacuum pump 35 is provided which is driven by a motor M to discharge the laser gas inside 1. And gas return path 21
The vacuum pump 35 and the vacuum pump 35 are connected by a pipe line 37. The pipe line 37 is provided with a first solenoid valve SOL1 whose opening and closing is controlled by the control device 33, and a pipe line 38 connected in parallel with the pipe line 37. Is provided with a second solenoid valve SOL2. Further, a variable flow control valve FCV1 is provided between the first solenoid valve SOL1 and the vacuum pump 35. A pressure sensor 39 for detecting the pressure in the gas return passage 21 is provided between the first solenoid valve SOL1 and the gas return passage 21.

In the exhaust system 25 having the above-described structure, the first and second solenoid valves SOL1 and SOL2 are opened and the vacuum pump 35 is driven under the control of the control device 33, so that the gas return path 21 is opened. The laser gas in the laser tube 3 can be rapidly exhausted via the via. Further, when the first solenoid valve SOL1 is opened and the second solenoid valve SOL2 is closed to drive the vacuum pump 35, the exhausted laser gas has a limited minute flow rate set by the variable flow control valve FCV1. You can Further, by closing the first and second solenoid valves SOL1 and SOL2, the exhaust of the laser gas can be shut off and the laser gas can be closed.

In any of the above operations, the pressure in the laser tube 3 is detected by the pressure sensor 39, and the detection signal from the pressure sensor 39 is fed back to the control device 33 to feed the first and second solenoids. Valve SOL1,
By appropriately controlling SOL2, the pressure in the laser oscillator 1 can be constantly kept constant.

As shown in FIG. 3, the gas mixing system 29 includes various gas cylinders 31A, 31B, 31C, etc. for CO ₂ , N ₂ and He from the gas mixing tank 2
It is configured so as to control various flow rates flowing into 7.

That is, various gas cylinders 31A, 31
The P port of the third solenoid valve SOL3 at the 3-port 2-position controlled by the controller 33 is connected to the other end of each of the pipelines 41 connected to B, 31C, .... The A port of the third solenoid valve SOL3 is connected to the fourth solenoid valve SOL4 at the 2-port / 2-position via each pipe line 42. The communication or cutoff of the fourth solenoid valve SOL4 is similarly controlled by the control device 33. Then, this fourth solenoid valve SOL
4 and the gas mixing tank 27 are communicated with each other through each pipeline 43. Further, a pipe line 45 branched from the pipe line 42 is connected to the B port of the third solenoid valve SOL3,
A flow meter FM and a flow rate control valve FCV2 are provided in series in the conduit 45. Further, the conduit 41 is
A pressure switch PS and a pressure gauge PM for detecting whether or not the pressure is within a set value are provided. In the gas mixing system 29 having the above structure, the pressure in the pipe 41 is set to be substantially equal.

In the above structure, the third solenoid valve SO
When L3 is excited to connect the P port and the A port and the fourth solenoid valve SOL4 is connected, various gases filled in the gas cylinders 31A, 31B, 31C, ... Are stored in the gas mixing tank 27. The gas rapidly flows in and is mixed in the gas mixing tank 27 at an appropriate ratio. At this time, by controlling the communication time of each third solenoid valve SOL4, the mixing ratio of various gases can be arbitrarily changed. Further, the third solenoid valve SOL3 is de-energized as shown in FIG. 3 to connect the P port and the B port,
When the fourth solenoid valve SOL4 is set in the communication state, various gases flow into the gas mixing tank 27 and are mixed at a minute flow rate limited by the flow rate control valve FCV2. Also in this case, the mixing ratio of various gases can be arbitrarily changed by controlling the communication time of each fourth solenoid valve SOL4. Therefore, various gases are mixed in the gas mixing tank 27 and the laser tube 3 of the laser oscillator 1 is mixed.
Can be supplied appropriately.

The gas laser oscillator 1 is an example of a carbon dioxide gas laser oscillator that can be used in the laser gas replenishment control method of the present invention. Instead of the gas cylinders 31A, 31B, etc. connected to the gas mixing system 29, the gas laser oscillator 1 is already used. The gas laser oscillator 1 is not limited to the gas laser oscillator 1 shown in FIG. 1 as long as it has a gas replenishing system capable of controlling the flow rate and flow of the laser gas from a gas cylinder in which laser gas is appropriately mixed. The laser oscillator may be a triaxial orthogonal type, and the discharge method may be either AC or DC.

Now, a first embodiment of the laser gas replenishment control method according to the present invention in the gas laser oscillator 1 having the above-mentioned structure will be described with reference to FIG. In FIG. 4, the vertical axis represents the rated output (W) of the gas laser oscillator, and the horizontal axis represents the discharge time (H) of the gas laser oscillator 1.
Note that the relationship in FIG. 4 is the same when the operating time (H) is used instead of the discharging time (H), and an appropriate constant output (W) is used instead of the rated output (W).

First, a case where the gas laser oscillator 1 is operated without supplying the laser gas, that is, in a sealed state will be described. First, the gas laser oscillator is started with the laser gas closed. It should be noted that the initial initial rated output of the gas laser oscillator 1 at the discharge time T ₀ at the start of operation is Pi (W). When the gas laser oscillator 1 is operated, the deterioration of the laser gas progresses almost in proportion to the discharge time, and the initial rated output Pi (W) of the gas laser oscillator 1 also decreases with the deterioration of the laser gas. When the standard cut piece is cut at the lowered rated output of the gas laser oscillator 1 and a defective cutting occurs, the rated output is accumulated to the minimum rated output Pm (W) and the minimum rated output Pm (W). The discharge time is referred to as a disconnection failure discharge time (Tm). This disconnection failure discharge time (Tm) can be experimentally determined, and the disconnection failure discharge time (Tm) determined by the experiment is preset in the memory of the control device 33.

Next, when the above-mentioned defective discharge time (Tm) is reached, the exhaust system 25 and the gas mixing system 29 are controlled by the control unit 33 to replenish and exhaust the laser gas to the laser tube 3. To start.
By supplying and exhausting this laser gas, the minimum rated output Pm
The output that has dropped to (W) is the initial initial rated output Pi
It gradually recovers to (W), and the initial rated output is Pi
When the recovery to (W) is detected (T ₂ ), the laser gas replenishment and exhaust steps are stopped and the laser tube 3 is closed.

After that, when the initial rated output Pi drops to the minimum rated output Pm (W), laser gas is replenished and exhausted until the lowered output returns to the initial rated output Pi (W). The same cycle is repeated thereafter.

By performing the laser gas replenishment control method as described above, it is possible to perform continuous operation for a long time without stopping the operation for exchanging the laser gas of the gas laser oscillator, and reduce the consumption of the laser gas. You can Further, there is also an advantage that the life of the exhaust device is extended because the exhaust device does not have to be continuously operated.

It is possible to obtain the same effect by the following second embodiment instead of the above-mentioned laser gas supply control method. That is, when the laser output of a certain laser processing is Wn and the processing time is tn, the product of the laser output and the processing time at that time is “Wn × t”.
n ”is stored in the memory in the control device 33. Then, the cumulative product of the laser output and the processing time of a large number of times of laser processing in which the laser output and the processing time are various, Σ (Wn × t
n), (n = 1, 2, 3, ...) Is calculated by the control device 33. Also, separately from this, the control device 33
In advance, the cumulative product Σ (Wn × t
The maximum value Σ (Wn × tn) Max of the value n) is set, and it is determined for each machining whether or not Σ (Wn × tn) = Σ (Wn × tn) Max, and Σ ( Wn × tn)
= Σ (Wn × tn) Max, it is determined that the disconnection failure discharge time (Tm) has been reached. From this time, the steps of replenishing and sealing off the laser gas similar to those in the first embodiment are performed.

In the second embodiment, Σ (Wn
× tn) Max, and the disconnection failure discharge time Tm do not always match, but Σ (W
It is possible to make them substantially equal by appropriately selecting the set value of (n × tn) Max.

By carrying out the laser gas replenishment control method of the second embodiment, it is possible to continuously operate for a long time without stopping the operation for exchanging the laser gas of the gas laser oscillator and to consume the laser gas. The amount can be reduced. Further, there is also an advantage that the life of the exhaust device is extended because the exhaust device does not have to be continuously operated.

[0029]

As can be understood from the above description of the embodiments, according to the present invention, a so-called loose sealing method in which a laser gas is contained in a laser tube for use and a part of the laser gas deteriorated by discharge are used. Is often exhausted from the laser tube to the atmosphere and a so-called so-called laser gas replenishment method, which is used while replenishing new laser gas, is used to stop the operation of the expensive laser oscillator for the purpose of exchanging the laser gas. Since it does not exist, it is possible to contribute to the reduction of the production cost of the processed product and to reduce the consumption amount of the laser gas.

[Brief description of the drawings]

FIG. 1 shows an example of a carbon dioxide laser oscillator used in a laser gas supply control method of the present invention.

FIG. 2 is a detailed explanatory view of the exhaust system in FIG.

FIG. 3 is a detailed explanatory view of the gas mixing system in FIG.

FIG. 4 is a first laser gas supply control method according to the present invention.
Explanatory drawing of the embodiment of FIG.

[Explanation of symbols]

 1 Gas Laser Oscillator 3 Laser Tube 5 Laser Gas Circulation Device 11 Rear Mirror 12 Output Sensor 13 Output Mirror 15 High Voltage Power Supply Circuit 21 Gas Return Path 23 Gas Feeding Path 25 Exhaust System 27 Gas Mixing Tank 33 Controller 35 Vacuum Pump

Claims (1)

[Claims] 1. An exhaust system capable of continuously or intermittently exhausting a laser gas from a gas laser oscillator under the control of a controller, and a laser gas mixed in an appropriate ratio under the control of the controller continuously. In a gas laser oscillator including a gas replenishment system capable of replenishing the gas laser oscillator intermittently or intermittently, and an output sensor for detecting the optical output of the laser and inputting to the control device, a gas laser oscillator comprising the following steps: Laser gas supply control method. (A) A step of operating the gas laser oscillator by keeping the laser gas in a sealed state (b) A step of starting replenishment and exhaust of the laser gas when the cutting failure discharge time at which defective cutting occurs is reached (c) Output of the gas laser oscillator From the time when the initial rated output has been restored, the step of stopping the laser gas replenishment and exhaust steps to put the laser tube into a closed state (d) repeating steps (a), (b), and (c)