JP3496434B2 - Laser constant current power supply device and laser processing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant current power supply device for lamp excitation of a solid-state laser oscillator composed of a chopper circuit for current instantaneous value control, and a laser processing apparatus using the constant current power supply device for lamp excitation. Is.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing the structure of a conventional laser constant current power supply device for a solid-state laser oscillator. Further, FIG. 8 is a timing chart schematically showing the operation of a conventional constant current power supply device for laser of a solid-state laser oscillator. In the figure, reference numeral 1 is a DC power supply, which is usually obtained by rectifying and smoothing an AC commercial power supply using an appropriate rectifying element, a capacitor and the like (neither is shown). Reference numeral 2 is a switch circuit formed of an electronic switch formed of a switching element such as a transistor, 3 is a reactor, 4 is an excitation lamp serving as a load of this power supply device, 5 is a commutation diode, 6
Is a current detector, which outputs the detected current as a voltage proportional to the detected current. Reference numeral 7 is a current setting device that sets the threshold value of the current detected by the current detector 6, 8 is a calculator such as an operational amplifier that compares the current detected by the current detector 6 with the threshold value of the current setting device 9, and 9 is the upper and lower limits. In the comparison circuit, 9a is a first comparator, 9b is a second comparator, 9c is a positive current error (+ ΔIr) setter, and 9d is a negative current error (−ΔI).
It is the setter of r). Reference numeral 10 is a flip-flop circuit. The output terminal of the first comparator 9a is connected to the reset terminal (R) of the flip-flop circuit 10,
The output terminal of the comparator 9b is connected to the set terminal (S) of the flip-flop circuit 10. The output terminal (Q) of the flip-flop circuit 10 is connected to the switch circuit 2
It is connected to the.

Next, the operation of a conventional laser constant current power supply device for a solid-state laser oscillator will be described. A direct current supplied from the direct current power source 1 is supplied to the excitation lamp 4 via the switch circuit 2 and the reactor 3 to cause the excitation lamp 4 to emit light and excite a laser oscillator (not shown). Normally, a constant current type power source is used as the power source of the excitation lamp 4. Next, the constant current operation of the conventional laser constant current power supply device will be described. A current detector 6 arranged between the reactor 3 and the excitation lamp 4 detects the lamp current I and detects a detected current If composed of a voltage proportional to the lamp current I.
To occur. On the other hand, the current setter 7 specifies the current command value Iref composed of the voltage corresponding to the specific lamp current value corresponding to the desired laser output. The calculator 8 is the current detector 6
Is connected to the current setting device 7, and the voltage Iref corresponding to a specific lamp current value is subtracted from the detected current If proportional to the lamp current I to obtain the deviation signal Ierr. The deviation signal Ierr is input to the first comparator 9a and the second comparator 9b in the upper / lower limit comparison circuit 9. A positive current error (+ ΔIr) is applied to one input terminal of the first comparator 9a by the setting device 9c, and a negative current error (-ΔIr) is applied to one input terminal of the second comparator 9b by the setting device 9d. Are given respectively.

Here, the deviation signal Ierr is Ierr> 0.
(That is, If> Iref) and a positive current error (+
ΔIr), the first comparator 9a outputs the digital signal "1" as its output signal CMP +, resets the flip-flop circuit 10, and the output terminal (Q) of the flip-flop circuit 10 outputs the digital signal "1". 0 "is output. At this time, the flip-flop circuit 10
The switch circuit 2 connected to the output terminal (Q) is turned off, the lamp current I flows back through the commutation diode 5 and the reactor 3, and the current value decreases. On the other hand, the deviation signal Ierr is Ierr <0 (that is, If <Ire
f) and smaller than the negative current error (−ΔIr), the second comparator 9b outputs its output signal CMP−.
Since the digital signal "1" is output and the flip-flop circuit 10 is set, the flip-flop circuit 10
Outputs a digital signal "1". At this time, the switch circuit 2 connected to the output terminal (Q) of the flip-flop circuit 10 is turned on, the lamp current I flows through the DC power supply 1, the switch circuit 2, and the reactor 3, and the current value increases. . Further, the deviation signal Ierr is −ΔIr <I
If err <+ ΔIr, the first comparator 9a,
Since the second comparators 9b both output the digital signal "0", the flip-flop circuit 10 is neither set nor reset, and the output terminal (Q) of the flip-flop circuit 10 does not change.

In this way, in the laser constant current power supply device shown in the block diagram of FIG. 7, the lamp current I is maintained within the specified positive / negative deviation range with respect to the desired current value. To work. Further, a specific operation will be described in detail with reference to FIG. The current command value Iref is shown in FIG.
As described above, the current value suddenly rises, the current value increases at a predetermined rate, and the current is suddenly cut off. When the current command value Iref suddenly rises at time t0, the DC current supplied from the DC power supply 1 is followed by the response of the power supply and the like, and is detected as the detection current If as shown in FIG. 8B. It The output of the detected current If and the current command value Iref are compared by the calculator 8, and as shown in FIG.
It is output as rr. Deviation signal Ier at time t0
Since r is If <Iref, Ierr <0, and is smaller than the negative current error (−ΔIr). Therefore, the second comparator 9b outputs, as shown in FIG.
The flip-flop circuit 10 is set with the digital signal "1" as the output signal CMP-, and the switch circuit 2 connected to the output terminal (Q) of the flip-flop circuit 10
Is turned on as shown in FIG. 8 (f), the lamp current I flows through the DC power supply 1, the switch circuit 2, and the reactor 3, and the current value increases.

At time t1, the deviation signal Ierr becomes If <
When it is no longer Iref and is smaller than the negative current error (−ΔIr), the output signal CMP− of the second comparator 9b becomes a digital signal “0” as shown in FIG. Eliminate the signal of the set. However, the switch circuit 2 connected to the output terminal (Q) of the flip-flop circuit 10 continues to be turned on as shown in FIG. 8 (f), and the lamp current I causes the direct current power supply 1, the switch circuit 2, and the reactor 3 to pass. It flows through and its current value increases further. At time t2, the deviation signal Ierr changes to I
When f> Iref, Ierr> 0, and larger than the positive current error (+ ΔIr), the first comparator 9a outputs the output signal CMP as shown in FIG. 8D.
The digital signal "1" is output as + and the flip-flop circuit 10 is reset. At this time, the switch circuit 2 connected to the output terminal (Q) of the flip-flop circuit 10
Is turned off, the lamp current I flows back through the commutation diode 5 and the reactor 3, and the current value decreases.

However, when the lamp current I flows back through the commutation diode 5 and the reactor 3 and its current value decreases, when the deviation signal Ierr becomes smaller than the negative current error (-ΔIr) at time t3. , The second comparator 9b outputs its output signal CMP-, as shown in FIG.
As a digital signal “1”, the flip-flop circuit 10
And the switch circuit 2 connected to the output terminal (Q) of the flip-flop circuit 10 is turned on again as shown in FIG. 8 (f), and the lamp current I is the DC power supply 1, the switch circuit 2, and the reactor. 3 and its current value increases. By such a repeated operation, the lamp current I from the power supply device 1 operates so as to be maintained within the range of the positive / negative current error (± ΔIr) designated with respect to the desired current command value Iref, and the time t10 Then, the switch circuit 2 is turned off, the lamp current I flows back through the commutation diode 5 and the reactor 3, and the current value decreases to zero.

[0008]

In the above-mentioned conventional laser constant current power supply device, the hysteresis width of the upper and lower limit comparison circuit 9, that is, the desired current command value Iref which is the ripple width is designated. Positive and negative current error (± Δ
Ir) is constant, in other words, the current ripple of the lamp current I is constant. One of the specifications of the constant current power supply device used for this type of solid-state laser excitation is the value of the current ripple of the lamp current I. In the laser constant current power supply device including the chopper circuit by current instantaneous value control shown in the conventional example, the smaller the current ripple, the more the on / off frequency of the switching element increases. That is, it is necessary to use a switching element having a large current capacity and a high allowable switching frequency, which increases the cost. Also, for the same output current value, the smaller the current ripple, that is, the higher the switching frequency, the more the loss due to heat generation during switching, and the more the cost required for cooling the switching element increases. The power loss during operation also increases.

For this reason, the conventional laser constant current power supply device for a solid-state laser oscillator has the following problems. First, since the excitation lamp 4 maintains the lighting of the excitation lamp 4 even when the laser is not oscillating, a current smaller than the threshold value of the current for generating the laser oscillation (the current at this time is referred to as “shimmer current”, In a laser excitation flash lamp, it is usually necessary to energize 1 to 3 A). The current ripple in the simmer current needs to be small in order to maintain stable lighting. That is,
A switching element having a relatively high allowable switching frequency is required. Further, the current value when the laser is oscillated is much larger than the simmer current. For example, in the case of pulse excitation with a solid-state laser having an average output number of 100 W, the lamp current becomes several 100 A during peak output oscillation. Therefore, when the circuit is designed based on the value of the current ripple in the simmer current value, a switching element having a large current and a high switching frequency is required, and the cost of the device becomes very high.

Further, in the conventional constant current power supply device,
Since the current ripple of the output current is constant, that is, the switching frequency is constant, when a relatively large lamp current is output for a long time, the loss (heat generation) of the switch circuit during laser processing causes internal switching element In some cases, the temperature exceeded the allowable temperature, the switching element was damaged, and the device stopped. Then, the magnitude of the current ripple of the laser constant current power supply device used for exciting the laser oscillator affects the ripple of the laser beam output that is output from the laser oscillator and is used as a heat source for processing, in particular, During laser processing, the size of the ripple of laser output depends on various conditions of laser processing (for example, material, shape, processing speed, peak value of laser output, repetition frequency, duty ratio, etc.). It is necessary to select As described above, in the conventional constant current power supply device for laser, the current ripple of the output current is constant, and if the magnitude of the ripple of the laser output is not appropriate for the processing conditions during the laser processing, the processing state becomes unsatisfactory. It becomes stable, and as a result, the processing quality of the workpiece deteriorates, which cannot be corrected.

Therefore, the present invention has been made to solve the above problems, and has a constant current power supply for a laser which has a large current capacity and a suppressed current ripple without using a switching element having a high switching frequency. The first object is to provide a device. A second object is to provide a laser processing apparatus capable of changing the value of the current ripple according to the processing conditions of the workpiece and obtaining good processing quality.

[0012]

According to a first aspect of the present invention, there is provided a constant current power supply device for a laser, wherein an upper limit value and a lower limit value of a lamp current supplied to an excitation lamp are set by a current threshold value setter, and the upper limit value and the lower limit value thereof are set. the lamp current which is specified in the range of, in the laser constant-current power supply supplied to the excitation lamp through the switching circuit and the reactor from the DC power source, said excitation
The upper and lower limits of the lamp current supplied to the starting lamp and
A current that allows the upper and lower limits of simmer current to be set freely
Threshold setter and lamp set by the current threshold setter
Current or simmer current upper and lower limits and the excitation
Comparison with the output of the current detector that detects the current flowing through the pump
Comparator circuit and output of the comparator circuit
Controls the conduction of the lamp current or the simmer current with
; And a that switch circuit, the upper limit value and the lower limit value of the set lamp current at the current threshold setting device, said switch
This is changed according to the load of the switch circuit obtained as the output of the temperature detector arranged in the circuit.

[0013] Claim 2 laser constant-current power supply device according to the upper and lower limit values of the lamp current supplied to the excitation lamp set in the current threshold setting device is identified within the range of the upper limit value and the lower limit value In the constant current power supply device for laser, which supplies the lamp current from the DC power source to the pump lamp via the switch circuit and the reactor, the lamp current is supplied to the pump lamp.
Lamp current upper and lower limits and simmer current upper limit
Current threshold setting device that can freely set the lower limit value and the
The lamp current or simmer set by the current threshold setter
Upper and lower limits of current and current flowing in the excitation lamp
Comparator that compares with the output of the current detector that detects
Circuit, and the lamp current at the output of the comparator circuit
Or a switch circuit for controlling conduction of the simmer current
And an upper limit value and a lower limit value of the lamp current set by the current threshold value setting device are the power consumption of the switch circuit and
It is changed according to the load of the switch circuit obtained as described above .

In the laser processing apparatus according to the third aspect of the present invention, the upper limit value and the lower limit value of the lamp current supplied to the excitation lamp are set by the current threshold value setter, and the current specified within the upper limit value and the lower limit value is set. A direct current power supply to an excitation lamp through a switch circuit and a reactor, a laser beam is output from a laser oscillator, the output laser beam is guided to a processing machine, and the laser beam output from the processing machine is applied to the laser beam. in the laser machining apparatus for machining a workpiece, before
Upper and lower limits of the lamp current supplied to the excitation lamp
And the upper and lower limits of simmer current can be freely set
The current threshold setter and the threshold set by the current threshold setter.
Upper limit and lower limit of the pump current or simmer current and the excitation
The output of the current detector that detects the current flowing through the lamp
Comparing comparator circuit and the comparator circuit
The output controls conduction of the lamp current or the simmer current.
A switch circuit to control, the speed command of the processing machine, the peak current value of the lamp current , the repetition frequency,
The upper limit value and the lower limit value of the lamp current set by the current threshold value setting device are changed according to one or more processing conditions of a current command composed of a duty ratio, a current command of a simmer current, a material and a shape of a workpiece. It is a thing.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the figure, the same reference numerals and symbols as those of the conventional example and each embodiment indicate the same or corresponding components as those of the conventional example and each embodiment.

Embodiment 1. 1 is a block diagram showing a laser constant current power supply device for a solid-state laser oscillator according to a first embodiment of the present invention, and FIG. 2 is a laser constant current power supply for a solid-state laser oscillator used in the embodiment shown in FIG. It is a block diagram which shows the upper limit threshold setting device used for the apparatus. In the figure, 1 is a DC power source obtained by rectifying and smoothing a commercial power source by using a rectifying element and a capacitor (not shown), 2 is a switching circuit such as a transistor or a switching circuit including a switching circuit,
Reference numeral 3 is a reactor composed of an induction coil, 4 is an excitation lamp serving as a load of the DC power supply 1, 5 is a commutation diode, and 6 is a current detector, which outputs a detected current as a voltage proportional to the detected current. Reference numeral 7 is a current setting device for setting the threshold value of the current detected by the current detector 6, which may be set by a potentiometer or may be used as the output of the D / A converter of the controller. Reference numeral 8 is an arithmetic unit composed of an operational amplifier or the like for comparing the current detected by the current detector 6 with the threshold value of the current setting unit 7, 9 is an upper / lower limit comparison circuit composed of a window comparator or the like, and 9a is a first comparison circuit. The comparator 9b is a second comparator as a comparison circuit. 10A is a logic gate circuit including a gate circuit and a flip-flop circuit, and the logic gate circuit 10A is composed of a flip-flop circuit 10a, an AND gate 10b, an AND gate 10c, and an inverter 10d. Further, the switch circuit 2a, the reactor 3a, and the commutation diode 5a are connected in parallel (not in parallel connection) to the switch circuit 2, the reactor 3, and the commutation diode 5. A lamp current supply circuit 30 including these independent switch circuit 2, reactor 3 and commutation diode 5 is configured, and a simmer current supply circuit 40 including another switch circuit 2a, reactor 3a and commutation diode 5a is configured. ing.

A switch circuit 2a composed of the simmer current supply circuit 40, a reactor 3a and a commutation diode 5a.
Is operated when the simmer current Is is applied, and an element having a smaller current capacity than that of the switch circuit 2, the reactor 3 and the commutation diode 5 which constitute the lamp current supply circuit 30 is used. Similar to the switch circuit 2, the output signal (Q) of the flip-flop circuit 10a is connected to the switch circuit 2a, and the operation of the switch circuit 2 and the switch circuit 2a is reversed by the inverter 10d. Further, a current threshold value setting device 11 that sets an upper limit threshold value and a lower limit threshold value is connected to the current setting device 7, the upper limit lower limit comparison circuit 9, and the logic gate circuit 10A. In the present embodiment, as shown in FIG. 2, the current threshold value setting unit 11 includes an arithmetic unit (non-inverting operational amplifier) 11a, an arithmetic unit (inverting operational amplifier) 11b, a comparator 11d, and a reference potential corresponding to the simmer current Is. Shimmer current setting device 1 for setting Isim
1e, positive power source 11f, analog switch circuit 11g, resistor 11 for changing the potential divided by the series-parallel circuit
It is composed of h, 11i, and 11j. Incidentally, when the analog switch circuit 11g is open, the input of the calculator 11a is low, and when the analog switch circuit 11g is closed, the input of the calculator 11a is high.

Next, the operation of the constant current power supply device for laser of the solid-state laser oscillator, which is composed of the chopper circuit for controlling the instantaneous current value of the present embodiment, will be described. The current command Iref given by the current setting device 7 is input to one input of the comparator 11d in the current threshold setting device 11, and the other input corresponds to the simmer current Is set by the simmer current setting device 11e. The reference potential Isim is input.
The comparator 11d compares the two inputs, and the output of the comparator 11d, that is, the potential at the point A in the figure is Iref> I.
It is “1” in the case of sim and “0” in the case of Iref ≦ Isim. The analog switch circuit 11g turns on when the input signal is "1" and turns off when the input signal is "0". Therefore, the positive power supply 11f and the analog switch circuit 11
g, a resistor 11h, a resistor 11i, and a resistor 11j, assuming that the input of the calculator 11a, that is, the potential at the point B in the figure, V1 when Iref> Isim, and Iref ≦ Isim If the case is V0, V
1> V0. Further, the potential at the point B is non-inverted and amplified by the calculator 11a and becomes the output signal + ΔIr. This +
ΔIr has the same sign as the potential at point B, and corresponds to the positive current error 9c in FIG. 7 of the conventional example. Further, since the arithmetic unit 11b operates as an inverting operational amplifier, the signal -ΔIr is obtained at the output of the arithmetic unit 11b. Therefore, the output potential of the current threshold value setting device + ΔIr and −
ΔIr is the current command Iref given by the current setter 7.
Is small when the simmer current Is value is less than or equal to the simmer current Is value, and is larger when the simmer current Is value is exceeded. That is, when the current command value of the lamp current I is small, the current ripple is small (the switching frequency is large), and when the current command value of the lamp current is large, the current ripple is large (the switching frequency is small).

Next, the operation of the logic gate circuit 10A will be described. Flip-flop circuit 1 of logic gate circuit 10A
The operation of 0a is the same as the conventional example. The output signal (Q) of the flip-flop circuit 10a is connected to one of the inputs of the AND gates 10b and 10c. The branched output GATE of the output of the current threshold value setter 11 is the output of the comparator 11d (potential at the point A in the figure), and I
“1” when ref> Isim, Iref ≦ Isim
In this case, it becomes "0". Output G of this current threshold value setting device 11
The ATE is directly connected to the AND gate 10b and is connected to the input of the AND gate 10c via the inverter 10d. As a result, the output signal Q of the flip-flop circuit 10a passes through the AND gate 10b and outputs the signal Q through the AND gate 10b in the case of the current command at the peak output oscillation when Iref> Isim.
It is output as 1, and the switch circuit 2 is turned on / off. On the other hand, when the simmer current command is Iref ≦ Isim, the output signal Q of the flip-flop circuit 10a is
Is output as a signal Q2 through the AND gate 10c,
The switch circuit 2a is turned on / off.

As described above, in this embodiment, the upper limit value of the output potential + ΔIr of the lamp current I supplied to the excitation lamp 4 and the lower limit value of the output potential −ΔIr are set by the current threshold value setter 11, and The current specified within the upper limit and the lower limit is supplied from the DC power supply 1 to the switch circuits 2 and 2
In the constant current power supply device for laser which supplies to the excitation lamp 4 via a and the reactors 3 and 3a, the current threshold value setting device 11 for setting the upper limit value and the lower limit value of the current supplied to the excitation lamp 4 is provided in the excitation lamp 4. The upper limit value and the lower limit value of the lamp current I to be supplied and the upper limit value and the lower limit value of the simmer current Is are set freely, and the upper limit value and the lower limit value of the lamp current I or the simmer current Is set by the current threshold value setting device 11 are set. The output of the current detector 6 which detects the current flowing through the excitation lamp 4 is compared by the comparator circuit including the upper and lower limit comparison circuit 9, and the conduction of the lamp current I or the simmer current Is is switched by the output of the comparator circuit to the switch circuits 2 and 2a. It is controlled by.

In particular, in the present embodiment shown in FIG. 1, the lamp current I and the simmer current Is set by the current threshold value setting device 11 have the independent switch circuit 2 and reactor 3 respectively.
And a lamp current supply circuit 30 including a commutation diode 5
And a simmer current supply circuit 40 including another switch circuit 2a, a reactor 3a and a commutation diode 5a.

In the present embodiment, when the simmer current Is is applied, the upper limit value and the lower limit value of the simmer current Is are set to be small so that the current ripple is reduced and the switch circuit 2a having a small switching current and a high switching frequency is provided. To operate. Therefore, since the simmer current Is is smaller than the lamp current I, it is a small current even if the upper limit value and the lower limit value thereof are set small, and even if a switching element having a high switching frequency is used, the expensive switch circuit 2a does not result. On the other hand, the lamp current I has a relatively large current ripple, and the switch circuit 2a including a switching element having a large current and a relatively low allowable switching frequency is operated.

By adding a simmer current supply circuit 40 which can be realized at a low cost and switching the switch circuit 2 and the switch circuit 2a, the value of the current ripple in the value of the simmer current Is is used as a reference. The cost can be reduced as compared with the conventional device designed as described above. In the present embodiment, the lamp current I and the simmer current Is are independently supplied to the lamp current supply circuit 30 and the simmer current supply circuit 40. Therefore, the value of the reactor 3 or the reactor 3a is set according to the current value. Since it can be set, the current ripple can be set smaller.
However, in the embodiment of FIG. 1, the lamp current supply circuit 3
0 and the simmer current supply circuit 40 are provided, but the lamp current supply circuit 30 may be used alone.

Embodiment 2. FIG. 3 is a block diagram showing a laser constant current power supply device of a solid-state laser oscillator according to a second embodiment of the present invention. In the drawings, the same reference numerals and symbols as those of the conventional example and the embodiments of FIGS. 1 and 2 indicate the same or corresponding components as those of the conventional example and the first embodiment. Here, redundant description is omitted. The configuration of FIG. 3 does not include the AND gate 10b, the AND gate 10c, and the inverter 10d, and does not include the switch circuit 2a, the reactor 3a, and the commutation diode 5a. Further, the logic gate circuit 10A has only the flip-flop circuit 10a, which corresponds to the conventional flip-flop circuit 10. Flip-flop circuit 1
0 directly opens and closes the switch circuit 2.

As described above, in this embodiment, the upper limit value of the output potential + ΔIr of the lamp current I supplied to the excitation lamp 4 and the lower limit value of the output potential −ΔIr are set by the current threshold value setting unit 11, and In the constant current power supply device for laser which supplies the current specified within the range of the upper limit value and the lower limit value to the excitation lamp 4 from the DC power supply 1 via the switch circuit 2 and the reactor 3, The current threshold value setting device 11 for setting the upper limit value and the lower limit value is
The upper limit value and the lower limit value of the lamp current I supplied to the excitation lamp 4 and the upper limit value and the lower limit value of the simmer current Is are set freely, and the upper limit value of the lamp current I or the simmer current Is set by the current threshold value setting unit 11 is set. And lower limit and excitation lamp 4
The output of the current detector 6 for detecting the current flowing through the comparator circuit is compared by the comparator circuit including the upper and lower limit comparison circuit 9, and the lamp current I or the simmer current I is output by the comparator circuit.
The switch circuit 2 controls the conduction of s. In particular, in the present embodiment shown in FIG. 3, when the simmer current Is is applied, the current ripple is reduced by setting the upper limit value and the lower limit value of the simmer current Is small to increase the switching frequency with a small current. Then, the switch circuit 2 is operated. Therefore, since the simmer current Is is smaller than the lamp current I, it is a small current even if the upper limit value and the lower limit value thereof are set small, and even if a switching element having a high switching frequency is used, the expensive switch circuit 2 is not obtained. On the other hand, the lamp current I has a relatively large current ripple, and the switching frequency is lowered with a large current.

In the laser constant current power supply device for the solid-state laser oscillator according to the present embodiment, the switch circuit 2 is operated by reducing the current ripple at the simmer current Is and increasing the switching frequency with a small current. Also, the lamp current I
Then, the current ripple is made relatively large, and the switch circuit 2 is operated with a large current. By switching the current and the repetition frequency of the inexpensive switching circuit 2 in this way, the cost can be reduced as compared with the device like the conventional example designed based on the value of the current ripple in the value of the simmer current Is. There is. In particular, in this embodiment,
Since the lamp current supply circuit 30 and the simmer current supply circuit 40 are commonly used, the cost is low. In particular, it becomes impossible to select the value of the reactor 3 according to the current value, but when the simmer current Is with a small current value is used, the switching frequency is increased, so that it is possible to make it common in a predetermined current and repetition frequency range. Yes, at this time, in particular, the cost can be reduced.

Embodiment 3. FIG. 4 is a block diagram showing a laser constant current power supply device of a solid-state laser oscillator according to a third embodiment of the present invention. In the drawings, the same reference numerals and symbols as those of the conventional example or the above-described embodiment indicate the same or corresponding components as those of the conventional example or the above-described embodiment, and therefore, redundant description will be given here. Is omitted. In FIG. 4, the difference between the present embodiment and the conventional example is that a temperature detector 12 and a current threshold value setter 11A connected to the temperature detector 12 and the upper and lower limit comparison circuit 9 are provided near the switch circuit 2. It is in the configuration that it has. This temperature detector 12 is a switch circuit 2
The temperature of the switch circuit 2 is detected by being disposed on a heat dissipation fin (not shown) of the IGBT (for example, IGBT).
The current threshold value setting device 11A includes a calculator 11Aa and a calculator 1
It consists of 1 Ab. In this embodiment, the arithmetic unit 11Aa operates as a non-inverting operational amplifier, and the arithmetic unit 11Ab operates as an inverting operational amplifier.

Next, the operation of the laser constant current power supply device of the solid-state laser oscillator of the present embodiment will be described. The temperature detector 12 detects the temperature via the heat radiation fins of the switch circuit 2 and outputs an output voltage Tsw proportional to the temperature. Generally, an IGB used as a switching element
For T, MOSFET, etc.,
Also, as the switching frequency increases, the loss increases, and the amount of heat generated increases. Therefore, the temperature detector 1
The value of the output voltage Tsw of 2 increases as the current flowing increases and the switching frequency increases. The temperature detector 12 is included in the calculator 11Aa of the current threshold value setter 11A.
Output voltage Tsw is input and non-inverted and amplified by the arithmetic unit 11Aa to obtain an output signal + ΔIr. This + ΔIr is
The voltage has the same sign proportional to the output voltage Tsw of the temperature detector 12, and corresponds to the positive current error 9c in the conventional example. Further, since the computing unit 11Ab operates as an inverting operational amplifier, the output of the computing unit 11Ab is the signal -Δ.
Get Ir. This −ΔIr is a voltage of opposite sign proportional to the output voltage Tsw of the temperature detector 12, and corresponds to the negative current error 9d in the conventional example.

As described above, in this embodiment, with respect to the first comparator 9a and the second comparator 9b,
Since positive and negative current errors proportional to the output voltage Tsw of the temperature detector 12 are given respectively, as a result, when the loss (heat generation amount) of the switch circuit 2 increases, the current ripple operates to increase. That is, the switching frequency is increased to suppress the loss. When the loss (heat generation amount) of the switch circuit 2 becomes small, it operates so as to reduce the current ripple. That is, the switching frequency is increased. Therefore, in the laser constant current power supply device of the solid-state laser oscillator of the present embodiment,
When a relatively large lamp current I is being output for a long time, the current ripple is increased before the internal temperature of the switching element exceeds the allowable temperature and damages due to an increase in switching loss (heat generation amount). By lowering the switching frequency to reduce the loss and lower the internal temperature of the switching element, the reliability of the device can be improved.

In the present embodiment, the upper limit value of the output potential + ΔIr of the lamp current I supplied to the excitation lamp 4 and the lower limit value of the output potential −ΔIr are set to the current threshold value setting unit 11.
In the constant current power supply device for laser, which is set by A and supplies the lamp current I specified within the range of the upper limit value and the lower limit value to the excitation lamp 4 from the DC power supply 1 through the switch circuit 2 and the reactor 3, The upper limit value and the lower limit value of the lamp current I set by the current threshold value setting device 11A are changed according to the load on the switch circuit 2. Therefore, when a relatively large lamp current I is output for a long time,
Due to an increase in the load (loss) of the switch circuit 2, the current ripple is increased to lower the switching frequency before the internal temperature of the switching element exceeds the allowable temperature and is damaged, resulting in a smaller loss and Since the internal temperature is lowered, the reliability can be improved. Particularly, in the present embodiment, the switch circuit 2
Since the temperature detector 12 arranged in the switch circuit 2 detects the load of the above as thermal energy, it becomes possible to detect the internal temperature which is a factor of destruction of the switching element, and increase its reliability. be able to.

Fourth Embodiment FIG. 5 is a block diagram showing a laser constant current power supply device of a solid-state laser oscillator according to a fourth embodiment of the present invention. In the drawings, the same reference numerals and symbols as those of the conventional example or the above-described embodiment indicate the same or corresponding components as those of the conventional example or the above-described embodiment, and therefore, the duplicate description is omitted here. To do. In FIG. 5, the difference between the present embodiment and the conventional example is that the first power detector 13 for detecting the power on the input side connected to the input side of the switch circuit 2 is different.
And a second power detector 14 for detecting the power on the output side connected to the output side of the switch circuit 2, and a loss, that is, a switch due to the first power detector 13 and the second power detector 14. It is configured to have a circuit for detecting the load on the circuit 2 and a current threshold value setting unit 11B connected to the upper and lower limit comparison circuit 9. The current threshold value setter 11B is the calculator 11
It is provided with Ba, a computing unit 11Bb, and a computing unit 11Bc. The arithmetic unit 11Ba of the present embodiment operates as a non-inverting operational amplifier, the arithmetic unit 11Bb operates as an inverting operational amplifier, and the arithmetic unit 11Bc operates as an arithmetic unit.

Next, the operation of the laser constant current power supply device of the solid-state laser oscillator of the present embodiment will be described. The first power detector 13 is installed on the input side of the switch circuit 2 and outputs a voltage signal (Win) proportional to the detected input power of the switch circuit 2. The second power detector 14 is installed on the output side of the switch circuit 2 and outputs a voltage signal (Wout) proportional to the detected output power of the switch circuit 2. As already described in the above-described embodiment, in the switching element such as the IGBT and MOSFET used as the switch circuit 2, the loss increases as the current flowing increases and the switching frequency increases, and the heat generation amount increases. .

Therefore, the input power for obtaining the desired output power increases. In other words, the efficiency (efficiency = output power / input power, input power = output power + loss) deteriorates. The output voltage Win of the first power detector 13 and the output voltage Wout of the second power detector 14 are input to the calculator 11Bc of the current threshold value setter 11B, and the difference output Werr thereof is output. This difference output Werr
Is the difference between the input power and the output power, that is, the switch circuit 2
The loss (heating value) of the switching element is equivalent to the burden. The difference output Werr is input to the arithmetic unit 11Ba and is non-inverted and amplified to obtain the output signal + ΔIr. This output signal + ΔIr is a potential of the same sign proportional to the differential output Werr, and corresponds to the positive current error 9c in the conventional example. Moreover, since the arithmetic unit 11Bb operates as an inverting operational amplifier, an output signal -ΔIr is obtained at the output of the arithmetic unit 11Bb. The output signal −ΔI is a voltage having a different sign proportional to the difference output Werr, and corresponds to the negative current error 9d of the conventional example.

In the present embodiment, the load of the switch circuit 2 is the power consumption of the switch circuit 2, and specifically, the difference output to the first comparator 9a and the second comparator 9b is performed. Since positive and negative current errors proportional to Werr are given, as a result, when the loss (heat generation amount) of the switch circuit 2 increases, the current ripple operates to increase. That is, the switching frequency is reduced to suppress the loss. Further, when the loss (heat generation amount) of the switch circuit 2 is reduced, the current ripple is operated to be reduced. That is, the switching frequency is increased.

Therefore, in the present embodiment, when a relatively large lamp current is output for a long time, the internal temperature of the switching element exceeds the allowable temperature and is damaged due to an increase in the loss (heat generation amount) during switching. Since the current ripple can be increased and the switching frequency can be lowered before the temperature reaches, the loss can be reduced and the internal temperature of the switching element can be lowered, so that the reliability of the device can be improved.

Embodiment 5. FIG. 6 is a block diagram of a laser processing apparatus showing a usage state of a laser constant current power supply apparatus of a solid-state laser oscillator according to a fifth embodiment of the present invention. In the drawings, the same reference numerals and symbols as those of the conventional example or the above-described embodiment indicate the same or corresponding components as those of the conventional example or the above-described embodiment, and therefore, the duplicate description is omitted here. To do.
In FIG. 6, the current threshold value setter 11C is a calculator 11Ca.
And an arithmetic unit 11Cb. In this embodiment,
The arithmetic unit 11Ca is a non-inverting operational amplifier,
Cb operates as an inverting operational amplifier. 15
Is a laser oscillator that oscillates using the lamp light source 4 as an excitation source, and in the case of a solid-state laser, is composed of a solid laser medium, a resonator, and the like. Reference numeral 16 is a laser beam transmission means composed of an optical fiber or a mirror, 17 is a processing machine composed of a processing head, a driving device, a gas supply device and the like, 18 is a speed command of the driving device of the processing machine 17, and the present embodiment It is a controller for setting and controlling the processing conditions such as the current command of the constant current power supply device of the above form, the material and shape of the workpiece. As shown in FIG. 6, the controller 18 is connected to the current setting device 7 and the current setting device 11C in the constant current power supply. The current threshold value setter 11C and the current setter 7 that set the upper limit threshold value and the lower limit threshold value may output a predetermined analog value as the output of the D / A converter of the controller 18, or may be set by the output of the potentiometer. Good. Reference numeral 19 denotes a laser beam, which is emitted from the laser oscillator 15, is irradiated onto the workpiece 20 via the laser beam transmission means 16 and the processing machine 17, and is used for the intended processing.

Next, the operation of the laser processing apparatus of this embodiment will be described. Electric energy is supplied from the DC power supply 1 to the excitation lamp 4 and converted into light. The laser oscillator 15 laser-oscillates using this light energy as an excitation source to generate a laser beam 19. The laser beam 19 is applied to the work piece 20 via the laser beam transmission means 16 and the processing machine 17, and desired processing such as perforation, cutting, welding, and surface modification is performed. At this time, appropriate processing conditions are set in the controller 18 according to the purpose and type of processing, and the outputs from the processing machine 17 and the DC power source 1 are controlled based on the conditions. As illustrated, the processing conditions may be given to the controller 18 by a medium such as an FD and the processing may be automatically performed. In the present embodiment, in addition to the controller 18 and the processing machine 17 being connected, the current setting device 7 and the current threshold value setting device 11C that constitute the constant current power supply are also connected. Therefore, of the machining conditions set by the controller 18, the speed command Vre
The value of the hysteresis command Href given to the current threshold value setting unit 11C can be changed according to f. This makes it possible to reduce the current ripple as the speed increases. In other words, it is possible to reduce the ripple of the laser output. Further, of the processing conditions set by the controller 18, a hysteresis command Hre given to the current threshold value setting device 11C according to the material is used.
The value of f can be changed. Accordingly, it is possible to appropriately change and set the current ripple, that is, the laser output ripple according to the material.

Specifically, when the upper limit value of the output potential + ΔIr of the lamp current I supplied to the excitation lamp 4 and the lower limit value of the output potential −ΔIr are set by the current threshold value setting unit 11C, the speed of the processing machine 17 is set. Set by the current threshold value setting unit 11C corresponding to selection from a map storing one or more processing conditions of the command, the current command of the lamp current I, the current command of the simmer current Is, and the material and shape of the workpiece 20. The upper limit value and the lower limit value of the lamp current I to be selected may be selected.

In the case of processing using a pulsed laser beam, that is, in the case of pulse processing, processing conditions are given by a combination of peak current output, repetition frequency and duty ratio. In the present embodiment, for example, the value of the hysteresis command Href given to the current threshold value setting unit 11C can be changed according to the repetition frequency. As a result, the higher the repetition frequency, the smaller the current ripple, that is, the laser output ripple. Therefore, in the laser processing apparatus according to the present embodiment, good processing quality can be obtained by changing the ripple width according to the processing conditions of the workpiece.

As described above, the upper limit value of the output potential + ΔIr of the lamp current I supplied to the excitation lamp 4 and the lower limit value of the output potential −ΔIr are set by the current threshold value setter 11C, and the upper limit value and the lower limit value are set. The current specified within the range is supplied from the DC power supply 1 to the excitation lamp 4 via the switch circuit 2 and the reactor 3 to cause the laser oscillator 14 to output the laser beam 16, and the output laser beam 1
In the laser processing apparatus that guides 6 to the processing machine 17 and processes the workpiece 20 with the laser beam 16 output from the processing machine 17, the speed command of the processing machine 17, the current command of the lamp current I, the current of the simmer current Is. The upper limit value and the lower limit value of the lamp current I set by the current threshold value setting unit 11C are changed according to one or more processing conditions of the command and the material and shape of the workpiece 20.

Therefore, when the upper limit value of the output potential + ΔIr of the lamp current I supplied to the excitation lamp 4 and the lower limit value of the output potential −ΔIr are set by the current threshold value setter 11C, the speed command of the processing machine 17, the lamp A lamp current set by the current threshold value setting unit 11C corresponding to selection from a map storing one or more processing conditions of the current command of the current I, the current command of the simmer current Is, and the material and shape of the workpiece 20. Since the upper limit value and the lower limit value of I are selected, the lamp current I, the simmer current Is, the workpiece 2
Lamp current I that matches machining conditions such as material and shape
The upper and lower limits can be selected, and the workpiece 20 is machined using a constant current power supply device for a laser with a large current capacity and a high switching frequency, and a suppressed current ripple value. The width of the current ripple can be changed according to the conditions, and good processing quality can be obtained. Further, the current command of the lamp current I is a peak current value,
Since it consists of repetition frequency and duty ratio, it is possible to select electrical conditions that match the laser processing characteristics.
Optimal control is possible.

This embodiment has a simple structure.
By changing the width of the ripple according to the current command of the lamp current I including the peak current value, the repetition frequency, and the duty ratio, an inexpensive device can be obtained. Also,
In the constant current power supply device for laser, by changing the width of the ripple according to the temperature or loss of a certain part in the device, damage to the device can be prevented in advance. Further, in a laser processing apparatus incorporating this laser constant current power supply device, good processing quality can be obtained by changing the width of the ripple according to the processing conditions of the workpiece 20. In addition, when implementing the present invention, the current threshold value setting device 11, 11A for setting the upper limit threshold value and the lower limit threshold value,
11B, 11C and the current setting device 7 are the controller 18
A predetermined analog value may be output as the output of the D / A converter, or may be set by the output of the potentiometer or the output of the F / V converter.

By the way, the laser processing apparatus of the above-mentioned embodiment shows only the laser processing apparatus shown in FIG. 6, but as the constant current power supply device for the laser, the embodiment shown in FIGS. 1 to 5 is used. It can be carried out by substituting the form. Further, the current threshold value is set according to one or more processing conditions of the speed command of the processing machine 17 of the above-described embodiment, the current command of the lamp current I, the current command of the simmer current Is, the material and the shape of the workpiece 20. What changes the upper limit value and the lower limit value of the lamp current I set in the container 11C is, of course,
One of the speed command of the processing machine 17, the current command of the lamp current I, the current command of the simmer current Is, the material and shape of the workpiece 20, or a combination of two or more, the upper limit value and the lower limit value of the lamp current I. It is only necessary to set the value uniquely.
Of course, after obtaining the average value of the lamp current I, the upper limit value and the lower limit value may be calculated from the average value. Then, the simmer current Is can be set similarly to the lamp current I. Furthermore, the relationship between the lamp current I and the simmer current Is may be set. In addition, the current command of the lamp current I when implementing the present invention is the peak current value, the repetition frequency,
As long as the duty ratio is 1 or more, electrical conditions that match the laser processing characteristics can be selected depending on the processing conditions such as the material and shape of the workpiece 20, and optimal control can be performed.

[0044]

As described above, according to the laser constant current power supply device of claim 1, the upper and lower limits of the lamp current supplied to the excitation lamp are set by the current threshold value setter, and the upper and lower limits thereof are set. the lamp current which is specified in a range of values, in the laser constant-current power supply supplied to the excitation lamp through the switching circuit and the reactor from the DC power source, said excitation
The upper and lower limits of the lamp current supplied to the starting lamp and
A current that allows the upper and lower limits of simmer current to be set freely
Threshold setter and lamp set by the current threshold setter
Current or simmer current upper and lower limits and the excitation
Comparison with the output of the current detector that detects the current flowing through the pump
Comparator circuit and output of the comparator circuit
Controls the conduction of the lamp current or the simmer current with
; And a that switch circuit, the upper limit value and the lower limit value of the set lamp current at the current threshold setting device, said switch
This is changed according to the load of the switch circuit obtained as the output of the temperature detector arranged in the circuit. Therefore, when a relatively large lamp current is output for a long time and the load (loss) on the switch circuit increases, the internal temperature of the switching element may exceed the allowable temperature.
Before the damage, the current ripple is increased to lower the switching frequency, and as a result, the load loss of the switch circuit is reduced and the internal temperature of the switching element is lowered, so that the reliability can be improved. Therefore, a device having a large current capacity and a suppressed current ripple value can be obtained without using a switching element having a high switching frequency. Temperature detection of the load on the switch circuit
The switching element is destroyed because it is detected by the detector.
The requirement that is closely related to the internal temperature
Can be detected and its reliability can be increased.
It

[0045] Laser constant-current power supply device according to claim 2, the upper limit value and the lower limit value of the lamp current supplied to the excitation lamp set in the current threshold setting device, which is identified within the range of the upper limit value and the lower limit value In a constant current power supply device for a laser, which supplies a lamp current to a pump lamp from a DC power source through a switch circuit and a reactor, a lamp which supplies the lamp to the pump lamp.
Upper limit value and lower limit value of shunt current and upper limit value of simmer current and
A current threshold value setting device that can freely set the lower limit value, and the current
Of the lamp current or simmer current set by the threshold value setter
Detects the upper and lower limits and the current flowing through the excitation lamp
Comparator circuit that compares the output of the current detector
And the output of the comparator circuit
And a switch circuit for controlling conduction of the simmer current.
And Bei, upper and lower limits of the set lamp current at the current threshold setting device, as the power consumption of the switching circuit
It is changed according to the obtained load of the switch circuit. Therefore, when a relatively large lamp current is output for a long time and the load (loss) on the switch circuit increases,
Since the internal temperature of the switching element may exceed the allowable temperature, the current ripple is increased to reduce the switching frequency before the damage to the internal temperature of the switching element. Since it lowers the reliability, the reliability can be improved. Therefore, a device having a large current capacity and a suppressed current ripple value can be obtained without using a switching element having a high switching frequency. Burden on the switch circuit
Is the power consumption of the switch circuit?
Always check the size of the load on the switch circuit.
Can predict the temperature rise of the switching element.
It is possible to detect and increase the reliability.

The laser processing apparatus according to claim 3, direct current upper limit value and the lower limit set by the current threshold setter, current specified within the range of the upper limit value and the lower limit value of the lamp current supplied to the excitation lamp The laser beam is supplied from the power supply to the excitation lamp through the switch circuit and the reactor to output the laser beam, the output laser beam is guided to the processing machine, and the workpiece is processed by the laser beam output from the processing machine. In the laser processing device, the laser supplied to the excitation lamp
Upper limit and lower limit of pump current and upper limit of simmer current
And a current threshold value setter that can freely set the lower limit
Current or simmer current set by the current threshold setter
The upper and lower limits of the current and the current flowing through the excitation lamp.
Comparator circuit that compares the output of the output current detector
And the output of the comparator circuit
And a switch circuit for controlling conduction of the simmer current.
And Bei, the speed command of the processing machine, the peak of the lamp current
The upper limit value of the lamp current set by the current threshold value setting device according to one or more processing conditions of a current value, a repetition frequency, a current command including a duty ratio, a current command of a simmer current, a material and a shape of a workpiece. And the lower limit value is changed. Therefore, when setting the lamp current to be supplied to the excitation lamp, select one or more processing conditions of the speed command of the processing machine, the current command of the lamp current, the current command of the simmer current, the material and shape of the workpiece. The upper and lower limits of the lamp current that match the processing conditions can be selected, and the width of the current ripple can be changed according to the processing conditions of the workpiece without using a switching element with a large current capacity and a high switching frequency. It is possible to obtain good processing quality. Therefore, the value of the current ripple can be changed according to the processing conditions of the workpiece, and good processing quality can be obtained. The current command for the lamp current is the peak current value,
Since it consists of return frequency and duty ratio,
You can select the electrical conditions that match the laser processing characteristics, and
Control is possible.

[0047]

[Brief description of drawings]

FIG. 1 is a block diagram showing a laser constant current power supply device of a solid-state laser oscillator according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a current threshold value setting device used in the laser constant current power supply device of the solid-state laser oscillator used in the embodiment of FIG.

FIG. 3 is a block diagram showing a laser constant current power supply device of a solid-state laser oscillator according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a laser processing apparatus showing a usage state of a laser constant current power supply device of a solid-state laser oscillator according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing a laser constant current power supply device of a solid-state laser oscillator according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram of a laser processing apparatus showing a usage state of a laser constant current power supply device of a solid-state laser oscillator according to a fifth embodiment of the present invention.

FIG. 7 is a block diagram showing the configuration of a conventional laser constant current power supply device for a solid-state laser oscillator.

FIG. 8 is a timing chart schematically showing the operation of a laser constant current power supply device of a conventional solid-state laser oscillator.

[Explanation of symbols]

2 switch circuit, 2a switch circuit, 3 reactor, 3a reactor, 4 lamp, 5 commutation diode, 5a commutation diode, 6 current detector, 9 upper and lower limit comparison circuit, 9a first comparator, 9b second
Comparator, 10 logic gate circuit, 11 current threshold setting device, 11A current threshold setting device, 11B current threshold setting device, 11C current threshold setting device, 12 temperature detector,
13 first power detector, 14 second power detector, 1
5 laser oscillators, 17 processing machines, 20 workpieces.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-223789 (JP, A) JP-A-3-226266 (JP, A) JP-A-6-6978 (JP, A) JP-A-5- 208316 (JP, A) JP-A-8-317655 (JP, A) JP-A-63-69428 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01S 3/00-3 / 30

Claims (3)

(57) [Claims] 1. An upper limit value and a lower limit value of a lamp current supplied to an excitation lamp are set by a current threshold value setting device, and a lamp current specified within the range of the upper limit value and the lower limit value is supplied from a DC power supply to a switch circuit and In a constant current power supply device for a laser which supplies an excitation lamp via a reactor, an upper limit value and a lower limit value of a lamp current supplied to the excitation lamp
Value and simmer current upper and lower limits can be set freely
Current threshold setting device and the current threshold setting device
The upper limit and lower limit of lamp current or simmer current and the above
The output of the current detector that detects the current flowing in the excitation lamp and
And a comparator circuit for comparing
Output of the lamp current or simmer current
A switch circuit for controlling, and the upper limit value and the lower limit value of the lamp current set by the current threshold value setter are temperature detectors arranged in the switch circuit.
A constant current power supply device for a laser, which is changed according to the load of the switch circuit obtained as the output of the laser. 2. An upper limit value and a lower limit value of the lamp current supplied to the excitation lamp are set by a current threshold value setting device, and the lamp current specified within the range of the upper limit value and the lower limit value is supplied from a DC power supply to a switch circuit and In a constant current power supply device for a laser which supplies an excitation lamp via a reactor, an upper limit value and a lower limit value of a lamp current supplied to the excitation lamp
Value and simmer current upper and lower limits can be set freely
Current threshold setting device and the current threshold setting device
The upper limit and lower limit of lamp current or simmer current and the above
The output of the current detector that detects the current flowing in the excitation lamp and
And a comparator circuit for comparing
Output of the lamp current or simmer current
A switch circuit for controlling, and the upper limit value and the lower limit value of the lamp current set by the current threshold value setting device are obtained as power consumption of the switch circuit.
A constant current power supply device for a laser, which is changed according to the load of the switch circuit. 3. An upper limit value and a lower limit value of a lamp current supplied to the excitation lamp are set by a current threshold value setting device, and a current specified within the upper limit value and the lower limit value is supplied from a DC power supply to a switch circuit and a reactor. Supply to the excitation lamp via
In a laser processing apparatus that outputs a laser beam from a laser oscillator, guides the output laser beam to a processing machine, and processes a workpiece with the laser beam output from the processing machine , a lamp that supplies the excitation lamp. Upper and lower limits of current
Value and simmer current upper and lower limits can be set freely
Current threshold setting device and the current threshold setting device
The upper limit and lower limit of lamp current or simmer current and the above
The output of the current detector that detects the current flowing in the excitation lamp and
And a comparator circuit for comparing
Output of the lamp current or simmer current
A switch circuit for controlling the speed command of the processing machine, the peak current of the lamp current.
Value, repetition frequency, current command consisting of duty ratio ,
Laser machining, characterized in that the upper limit value and the lower limit value of the lamp current set by the current threshold value setting device are changed according to one or more processing conditions of the current command of the simmer current and the material and shape of the workpiece. apparatus.