JP3593410B2 - Method and apparatus for detecting off-electrode discharge in laser oscillator - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and apparatus for detecting an off-electrode discharge in a laser oscillation apparatus that detects an off-electrode discharge when laser oscillation is performed by the laser oscillation apparatus.
[0002]
[Prior art]
Conventionally, in a laser oscillator such as a carbon dioxide gas, detecting discharge at a place other than an electrode is called extra-electrode discharge. Further, the discharge of the laser oscillator is roughly classified into continuous discharge and pulse discharge depending on the application such as machining and cutting conditions. Therefore, it is necessary to detect both the continuous discharge and the pulse discharge as the off-electrode discharge.
[0003]
A laser oscillator 101 as shown in FIG. 5 includes electrodes 103 and 105 facing each other, and a power supply 107 is provided in this electric circuit. Therefore, when the power supply 107 is turned on, the discharge is performed in the discharge portion 109 between the electrodes 103 and 105, and the laser gas flows as indicated by the arrow, and the laser beam oscillates in the direction orthogonal to FIG. Become.
[0004]
An off-electrode discharge sensor 111 is provided in the vicinity of the electrode 105. The output level of the sensor is compared by a comparator 113, and a signal of a certain level Vref or more is determined to be an off-electrode discharge. The CR filter 115 of the output of the comparator 113 is a filter for removing noise, and prevents malfunction due to noise.
[0005]
[Problems to be solved by the invention]
By the way, in the configuration of the conventional laser oscillator 101 described above, the continuous discharge outside the electrode can be completely detected by the external electrode discharge sensor 111 during the continuous discharge, but the signal of the discharge outside the electrode is also pulsed during the pulse discharge. When a pulse frequency close to the time constant of the CR filter 115 or a pulse discharge with a narrow duty is used, the signal may not reach the I / O and may not be detected. Further, if the CR filter 115 is used, there is a malfunction due to noise, and it cannot be removed. Therefore, the noise immunity is reduced.
[0006]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for detecting an off-electrode discharge in a laser oscillator, which can reliably detect an off-electrode discharge when pulse discharge is performed by the laser oscillator.
[0007]
[Means for Solving the Problems]
Electrodes outside the discharge detection method in the laser oscillator of the present invention according to claim 1 in order to achieve the above object, oscillating the laser beam by pulse discharge between the power supply and opposed giving pulse command from the pulse command unit to the electrodes In the laser oscillator, a synchronous counter connected to the off-electrode discharge sensor provided in the vicinity of the electrode and the pulse command section counts when there is an off-electrode discharge signal at the end of the pulse discharge , and performs the pulse command. parts connected by counting counter counts the number of pulses of the pulse discharge, while counting the number of pulses at constant intervals in the counting counter, setting count of the synchronous count is pre-set value In this case, the detection is made as an off-electrode discharge alarm.
[0008]
Electrodes outside the discharge detecting device in a laser oscillator of the present invention according to claim 2 is the laser oscillator of Ru oscillating the laser beam by pulsed discharge between electrodes facing each other pulsed command from the pulse command section to the power supply, the An external electrode discharge sensor provided in the vicinity of an electrode, a synchronous counter connected to the pulse command section and the external electrode discharge sensor, and counting when there is an external electrode discharge signal at the end of the pulse discharge; and a counting counter for counting the number of pulses of the pulse discharge is connected, a memory allowed to store the setting value set in advance, the synchronous counter, coupled to said counting counter and the memory, a constant interval by the number counter comparing said set value of the count value set in the memory of the synchronous counter while the number of pulses are counted for And cross, is characterized in that the count value and a comparison determination unit for detecting an electrode outside the discharge alarm when it becomes more than the set value.
[0009]
Therefore, in the method and apparatus for detecting an off-electrode discharge in a laser oscillator according to the present invention according to claims 1 and 2, a pulse command is applied to a power supply from a pulse command unit to cause a pulse discharge to a discharge unit between opposing electrodes, thereby causing a laser. A beam is oscillated.
[0010]
At the time of the pulse discharge, the discharge outside the electrode is counted by a synchronous counter connected to the discharge sensor outside the electrode provided near the electrode and the pulse command unit . Further, the number of pulses at fixed intervals is counted by a counting counter connected to the pulse command unit. Wherein while counting the number of pulses of fixed interval in counting counter, said count number of the synchronous counter and the setting value set in advance is stored in the memory are taken into comparison determination unit, the number of the counting Is detected as an out-of-electrode discharge alarm when is greater than or equal to the set value.
[0011]
Thus, it is possible to reliably detect the off-electrode discharge at the time of the pulse discharge and to prevent erroneous detection due to noise.
[0012]
According to a third aspect of the present invention, there is provided an off-electrode discharge detecting device for a laser oscillator according to the second aspect, further comprising a switching device for switching between continuous discharge and pulse discharge. It is assumed that.
[0013]
Therefore, since a switching device for switching between the continuous discharge and the pulse discharge is provided, the continuous discharge and the pulse discharge are selected by the switching device, and the off-electrode discharge by each can be detected.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
Referring to FIG. 1, the laser oscillator 1 includes electrodes 3 and 5 facing each other, and a power supply 7 is provided in an electric circuit of the electrodes 3 and 5. When the power supply 7 is turned on, a discharge is performed in the discharge portion 9 between the electrodes 3 and 5, and a laser gas flows as indicated by an arrow, and the laser beam is oscillated in a direction perpendicular to the plane of FIG. Will be.
[0016]
An extra-electrode discharge sensor 11 is provided near the electrode 5, and a pulse command unit 13 and a continuous command unit 15 are connected to the power supply 7. Further, a switching device 17 for switching between pulse discharge and continuous discharge is connected to the pulse command section 13 and the continuous command section 15, respectively.
[0017]
A synchronous counter 19 is connected to the off-electrode discharge sensor 11 and the pulse command unit 13, and a count counter 21 is connected to the pulse command unit 13. A comparison judging device 23 is connected to the synchronous counter 19 and the counter 21. A memory 25 for storing a set value set in advance is connected to the comparison determination device 23.
[0018]
A comparator 27 is connected to the off-electrode discharge sensor 11, and a CR filter 29 including a resistor R and a capacitor C is connected to the comparator 27.
[0019]
Before describing the operation of detecting an off-electrode discharge in the above configuration, the relationship between the pulse discharge (command) and the off-electrode discharge will be described first. As shown in FIG. Is turned on, and pulse discharge is performed to the discharge portion 9 between the electrodes 3 and 5. The pulse command and the pulse discharge are similar, and the off-electrode discharge has a delay of time T at the end of the pulse discharge.
[0020]
As described above, since the pulse discharge and the off-electrode discharge have the timings as shown in FIG. 2, the synchronous counter 19 is used, the pulse discharge (pulse command) is synchronously clocked, and the off-electrode discharge (signal) Is used for data. This principle is briefly described as shown in FIGS.
[0021]
For example, FIG. 3A shows a signal at the end of the pulse discharge, which is output to the synchronous counter 19. In FIG. 3B, since there is no signal at the end of the pulse discharge, it is not determined that the discharge is outside the electrode and is not output to the synchronous counter 19.
[0022]
Although the principle of this detection method is as shown in FIGS. 3A and 3B, noise may enter at the end of the pulse discharge and a malfunction may be considered. Therefore, a counter 21 for counting the number of pulses of pulse discharge is provided separately from the synchronous counter 19, and when an external electrode discharge signal of a specified number of times, that is, an external electrode signal of a predetermined value or more is counted at a certain interval, an external electrode alarm is generated. The malfunction is prevented by recognizing as.
[0023]
With the above configuration, the operation of detecting an off-electrode discharge will be described with reference to the flowchart shown in FIG. 4. In step S1, the count counter 21 is set to N = 0 and the synchronous counter 19 is set to ARC = 0. In step S2, a pulse discharge and a continuous discharge (CW) are selected, and when the continuous discharge is selected, the process is terminated.
[0024]
When the pulse discharge is selected, the switching device 17 is switched to the pulse discharge, a pulse command is given from the pulse command unit 13 to the power supply 7, and the pulse discharge is performed in the discharge unit 9 between the power supplies 3 and 5. That is, after the count counter 21 is set to N = N + 1 in step S3, it is determined in step S4 whether or not the out-of-electrode discharge count number ARC is input in the synchronous counter 19, and the out-of-electrode discharge count number ARC must be input. For example, the process proceeds to step S8, and if the count counter 21 does not reach N = 16 (N <16), the process returns to step S2.
[0025]
If the synchronous counter 19 has input the discharge count ARC outside the power supply in step S4, the process proceeds to step S5, where ARC = ARC + 1 is counted. In step S6, the comparison / decision device 23 compares the out-of-electrode discharge count number ARC of the synchronous counter 19 with a preset set value, for example, 3 stored in the memory 25. If ARC = 3, the process proceeds to step S6. At S7, an off-electrode discharge alarm is output. If ARC <3 in step S6, the process proceeds to step S8. If N <16, the process returns to step S2. If N = 16, the process returns to step S1 and repeats again.
[0026]
When the continuous discharge is selected in step S2, the switching device 17 is switched for continuous discharge, and a continuous command is given from the continuous command unit 15 to the power source 7, so that the continuous discharge is performed in the discharge unit 9 between the electrodes 3 and 5. Discharge is performed. In this case, similarly to the conventional case, the discharge outside the power supply 11 is detected by the discharge sensor 11 outside the power supply, and then compared with the level Vref by the comparator 27, and a signal higher than the level Vref is output to the I / O via the CR filter 29. become.
[0027]
Therefore, since the discharge outside the electrode can be detected in synchronization with the pulse discharge (pulse command), it is possible to reliably detect a pulse discharge having a particularly high frequency and a narrow duty. Further, by counting the pulses of the pulse discharge, noise can be eliminated as much as possible.
[0028]
By providing the switching device 17, it is possible to easily perform the conventional combination of detection of an external electrode discharge by continuous discharge and detection of an external electrode discharge by pulse discharge. In addition, it can be manufactured at low cost using an inexpensive digital IC. In addition, since erroneous detection due to noise can be eliminated, it is not necessary to stop the laser oscillator 1. Since the extra-electrode discharge can be detected more reliably, the laser oscillator 1 and the power supply 7 can be protected.
[0029]
The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes.
[0030]
【The invention's effect】
As understood from the above embodiments, according to the first and second aspects of the present invention, a pulse command is supplied to the power source from the pulse command unit, so that the pulse is discharged to the discharge unit between the opposed electrodes. The laser beam is oscillated.
[0031]
At the time of the pulse discharge, the discharge outside the electrode is counted by a synchronous counter connected to the discharge sensor outside the electrode provided near the electrode and the pulse command unit . Further, the number of pulses at fixed intervals is counted by a counting counter connected to the pulse command unit. Wherein while counting the number of pulses of fixed interval in counting counter, said count number of the synchronous counter and the setting value set in advance is stored in the memory are taken into comparison determination unit, the number of the counting Is detected as an out-of-electrode discharge alarm when is greater than or equal to the set value.
[0032]
Thus, it is possible to reliably detect the off-electrode discharge at the time of the pulse discharge and to prevent erroneous detection due to noise.
[0033]
According to the third aspect of the present invention, since the switching device for switching between the continuous discharge and the pulse discharge is provided, the continuous discharge and the pulse discharge by the switching device are selected, and the off-electrode discharge by each is detected. Can be.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for performing detection of off-electrode discharge in a laser oscillator according to the present invention.
FIG. 2 is an explanatory diagram showing timings of a pulse discharge and an off-electrode discharge.
FIG. 3 is a principle diagram of detection of discharge outside the electrode using a synchronous counter.
FIG. 4 is a flowchart illustrating an operation of detecting an off-electrode discharge.
FIG. 5 is an explanatory diagram for explaining detection of off-electrode discharge in a conventional laser oscillator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser oscillator 3, 5 Electrode 7 Power supply 9 Discharge part 11 Out-of-electrode discharge sensor 13 Pulse command part 17 Switching device 19 Synchronous counter 21 Count counter 23 Comparison judgment device 25 Memory

Claims (3)

In the laser oscillator by pulse discharge Ru oscillating the laser beam to the power supply from the pulse command section between electrodes opposed giving pulse command,
Synchronous counter which is connected to the electrode outside the discharge sensor provided in the vicinity and the pulse command section of the electrode, as well as counting time at a pulse discharge end there is the electrode outside the discharge signal, is connected to the pulse command unit counted number counter is the number of pulses of the pulse discharge was, while counting the number of pulses at constant intervals in the counting counter, when the count of the synchronous count is equal to or higher than a preset value And detecting an extra-electrode discharge alarm in the laser oscillator. A laser oscillator which by pulse discharge Ru oscillating the laser beam to the power supply from the pulse command section between electrodes opposed giving pulse command,
An off-electrode discharge sensor provided near the electrode,
A synchronous counter connected to the pulse command unit and the off- electrode discharge sensor and counting when there is an off-electrode discharge signal at the end of the pulse discharge ;
A counting counter that is connected to the pulse command unit and counts the number of pulses of the pulse discharge ;
A memory allowed to store the preset setting value,
The synchronous counter, coupled to said counting counter and the memory, and a set value the set in the memory and the count value of the synchronous counter while counting the number of pulses at constant intervals in the counting counter A comparison determination device that performs a comparison determination and detects as an extra-electrode discharge alarm when the count value is equal to or greater than the set value ,
Electrodes outside the discharge detecting device in a laser oscillator, comprising the. Electrodes outside the discharge detecting device in a laser oscillator according to claim 2, further comprising a switching device for switching between the continuous discharge and pulse discharge.

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