JP2022030637A - Laser processing machine and laser processing method - Google Patents

Abstract

To provide a laser processing machine that is able to improve processing quality by appropriately suppressing stimulated Raman scattering.SOLUTION: A first detector (a first photodiode 136) detects a first quantity of light of a second frequency band less than a first frequency band including unnecessary light caused by stimulated Raman scattering or an overall quantity of light of a laser beam having the first and second frequency bands. A second detector (a second photodiode 137) detects a second quantity of light of a laser beam not having the second frequency band and having the first frequency band. A stimulated Raman scattering determination unit 40 outputs a status signal when the proportion of the second quantity of light to the overall quantity of light or the proportion of the second quantity of light to the first quantity of light exceeds a predetermined threshold value. When receiving a status signal, a control device (an NC device 50) controls a drive unit 21 so as to decrease a laser output of a laser oscillator (a fiber laser oscillator 10) and decrease the processing speed of a sheet metal W.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laser processing machine and a laser processing method for processing an object to be processed by a laser beam emitted from a laser oscillator.

In recent years, the laser oscillator of a laser processing machine has been increasing in output, and a laser oscillator having a laser output of 10 kW or more has been put on the market. When the laser output is increased, induced Raman scattering, which is one of the non-linear phenomena of the fiber, is likely to occur. That is, if the laser output is a low output of less than 1 kW, it is a known technique to reduce the generated induced Raman scattered light to less than 1% by a filter or the like to suppress the influence on the oscillator, but it is several kW to 10 kW. With the above laser output, the absolute amount is large when the induced Raman scattered light is reduced to less than 1%, and the effect on the oscillator is an issue that should be further investigated. According to Patent Document 1, after reducing the intensity of the induced Raman scattered light generated by the laser oscillator, the intensity of the induced Raman scattered light is further detected, and when the detected intensity exceeds the set value, the laser output is suppressed. Are listed.

Japanese Unexamined Patent Publication No. 2019-197081

In Patent Document 1, the laser output is controlled only based on the detected value obtained by detecting the intensity of the induced Raman scattered light. When the laser output of the laser oscillator is changed, the intensity of the generated induced Raman scattering light also changes. However, if the induced Raman scattered light is generated, the required laser output cannot be secured only by suppressing the laser output, it is not possible to cut a thicker plate, or the surface accuracy of the cut surface is deteriorated. In addition, if induced Raman scattered light is generated, the laser beam that can be output also decreases, but since it is a non-linear phenomenon, it is unclear how much the laser output should be changed to improve it, and the solution is unknown. Remains. Therefore, it is not possible to appropriately suppress the induced Raman scattering only by controlling the laser output based only on the detected value obtained by detecting the intensity of the induced Raman scattered light. If the induced Raman scattering cannot be suppressed properly, the processing quality may deteriorate.

The present invention provides a laser processing machine and a laser processing method capable of appropriately suppressing induced Raman scattering and improving processing quality.

According to the present invention, a laser oscillator that emits a laser beam, a processing head that processes a sheet metal using the laser beam emitted from the laser oscillator, and a drive unit that moves the processing head relative to the sheet metal. Of the laser beams traveling in the laser oscillator or in the processing head, the first light amount or the first and the first of the laser beams having a second frequency band lower than the first frequency band including unnecessary light due to induced Raman scattering. Of the first detector that detects the total amount of light of the laser beam having the second frequency band and the laser beam traveling in the laser oscillator or the processing head, the first frequency that does not have the second frequency band. The second detector that detects the second light amount of the laser beam having a band, and the total light amount obtained by adding the first light amount and the second light amount, or the second light amount with respect to the total light amount detected by the first detector. Output from the guided laser scattering determination unit and the induced laser scattering determination unit that output a status signal when the ratio of the light amount exceeds a predetermined threshold or the ratio of the second light amount to the first light amount exceeds a predetermined threshold. When the received status signal is received, an output command value is supplied to the laser oscillator so as to reduce the laser output of the laser oscillator, and the drive unit is controlled to reduce the machining speed for moving the machining head relative to the sheet metal. A laser processing machine equipped with a control device is provided.

According to the present invention, a laser oscillator that emits a laser beam of a pulse wave, a processing head that processes a sheet metal using the laser beam emitted from the laser oscillator, and a drive that moves the processing head relative to the sheet metal. The first amount of light of the laser beam having a second frequency band lower than the first frequency band including unnecessary light due to induced Raman scattering among the laser beams traveling in the laser oscillator or the processing head. Of the first detector that detects the total amount of light of the laser beam having the first and second frequency bands and the laser beam traveling in the laser oscillator or the processing head, the second frequency band is not provided. The total light amount obtained by adding the first light amount and the second light amount to the second detector that detects the second light amount of the laser beam having the first frequency band, or the total light amount detected by the first detector. When the ratio of the second light amount to the first light amount exceeds a predetermined threshold, or when the ratio of the second light amount to the first light amount exceeds a predetermined threshold, the induced Raman scattering determination unit that outputs a status signal and the induced Raman scattering Provided is a laser processing machine including a control device for controlling the laser oscillator so as to change the pulse frequency of the laser beam emitted by the laser oscillator when the status signal output from the determination unit is received.

According to the present invention, among the laser beams transmitted through the bend mirror included in the beam coupler or the processing head in the laser oscillator that emits the laser beam, the first less than the first frequency band including unnecessary light due to induced Raman scattering. The first light amount of the second frequency band or the total light amount of the laser beam including the first and second frequency bands is detected by the first detector, and the second frequency band of the laser beam transmitted through the bend mirror is detected. The second light amount of the laser beam including the first frequency band is detected by the second detector, and the total light amount obtained by adding the first light amount and the second light amount or the first detector detects the total light amount. When the ratio of the second light amount to the total light amount exceeds a predetermined threshold, or the ratio of the second light amount to the first light amount exceeds a predetermined threshold, a status signal is generated and a status signal is generated. Provided is a laser processing method in which an output command value is supplied to a laser oscillator so as to reduce the laser output of the laser oscillator, and the processing speed at which the processing head is moved relative to the sheet metal to be processed is reduced.

According to the present invention, among the laser beams transmitted through the bend mirror included in the beam coupler or the processing head in the laser oscillator that emits the laser beam of the pulse wave, the first frequency band including unnecessary light due to induced Raman scattering. The first light amount in the second frequency band less than or the total light amount of the laser beam including the first and second frequency bands is detected by the first detector, and the second of the laser beams transmitted through the bend mirror. The second light amount of the laser beam including the first frequency band without including the frequency band of is detected by the second detector, and the total light amount or the first detection obtained by adding the first light amount and the second light amount. When the ratio of the second light amount to the total light amount detected by the instrument exceeds a predetermined threshold, or when the ratio of the second light amount to the first light amount exceeds a predetermined threshold, a status signal is generated and a status signal is generated. Then, a laser processing method for changing the pulse frequency of the laser beam emitted by the laser oscillator is provided.

According to the laser processing machine and the laser processing method of the present invention, the induced Raman scattering can be appropriately suppressed and the processing quality can be improved.

It is a block diagram which shows the laser processing machine of 1st Embodiment. It is a characteristic diagram which shows the difference of the maximum cutting speed when unnecessary light due to induced Raman scattering is not generated and when it is generated when cutting stainless steel. It is a characteristic diagram which shows the difference of the maximum cutting speed when the unnecessary light due to the induced Raman scattering is not generated and when it is generated when the aluminum plate is cut. It is a characteristic diagram which shows the relationship between the wavelength and light intensity of a laser beam at the time of continuous wave oscillation and pulse wave oscillation by a laser processing machine. It is a characteristic diagram which shows the relationship between the pulse frequency at the time of pulse wave oscillation, and the amount of unnecessary light generated by induced Raman scattering. It is a characteristic diagram which shows the relationship between a pulse frequency and a laser output at the time of a pulse wave oscillation. It is a block diagram which shows the laser processing machine of 2nd Embodiment. It is a block diagram which shows the laser processing machine of 3rd Embodiment. It is a block diagram which shows the laser processing machine of 4th Embodiment. It is a block diagram which shows the laser processing machine of 5th Embodiment. It is a block diagram which shows the laser processing machine of 6th Embodiment. It is a block diagram which shows the laser processing machine of 7th Embodiment. It is a block diagram which shows the laser processing machine of 8th Embodiment. It is a block diagram which shows the laser processing machine of 9th Embodiment. It is a block diagram which shows the laser processing machine of the tenth embodiment. It is a block diagram which shows the laser processing machine of eleventh embodiment. It is a block diagram which shows the laser processing machine of the twelfth embodiment. It is a block diagram which shows the laser processing machine of 13th Embodiment. It is a block diagram which shows the laser processing machine of 14th Embodiment. It is a block diagram which shows the laser processing machine of the fifteenth embodiment. It is a block diagram which shows the laser processing machine of 16th Embodiment.

Hereinafter, the laser processing machine and the laser processing method of each embodiment will be described with reference to the attached drawings. In the laser processing machine of each embodiment, the same parts may be designated by the same reference numerals, and the description of common parts may be omitted.

<First Embodiment>
FIG. 1 is a configuration diagram showing a laser beam machine 1A of the first embodiment. The laser processing machine 1A may be a laser cutting machine that cuts a sheet metal as a processing object, or may be a laser welding machine that welds a sheet metal. The processing of the object to be processed is not limited to cutting, and may be any processing such as welding or marking. In the first embodiment and each of the embodiments described later, the laser processing machine is a laser cutting machine, and the processing of the object to be processed is cutting.

As shown in FIG. 1, the laser processing machine 1A includes a fiber laser oscillator 10 which is an example of a laser oscillator, a processing unit 20, a process fiber 30, an induced Raman scattering determination unit 40, and an NC device 50.

The fiber laser oscillator 10 comprises a laser beam oscillation source 11, a feeding fiber 12 propagating a laser beam emitted from the laser beam oscillation source 11, and a beam coupler 13 connecting the feeding fiber 12 and the process fiber 30. Be prepared. Details of the configuration and operation of the fiber laser oscillator 10 will be described later.

The process fiber 30 propagates the laser beam emitted from the beam coupler 13 and causes the laser beam to be incident on the processing head 22 of the processing unit 20. The processing unit 20 includes a processing head 22 and a driving unit 21 that drives the processing head 22.

The processing head 22 includes a collimating lens 221 and a focusing lens 223. The collimated lens 221 parallelizes the laser beam of the divergent light emitted from the emission end of the process fiber 30 and converts it into collimated light. The focusing lens 223 focuses the laser beam of the incident collimated light, converts it into convergent light, and irradiates the sheet metal W. The drive unit 21 moves the processing head 22 along the sheet metal W, but the processing head 22 is fixed and the sheet metal W may be moved. The drive unit 21 may move the processing head 22 relative to the sheet metal W so as to cut the sheet metal W.

The induced Raman scattering determination unit 40 determines the degree of induced Raman scattering generated in the laser beam oscillation source 11 as described later. The NC device 50 controls the fiber laser oscillator 10 (laser beam oscillation source 11) and the drive unit 21. The NC device 50 is an example of a control device that controls the fiber laser oscillator 10 and the drive unit 21.

Here, the configuration and operation of the fiber laser oscillator 10 will be described in detail. The laser beam oscillation source 11 emits, for example, a laser beam having a wavelength of 1080 nm. The laser beam oscillation source 11 may emit a laser beam having a wavelength of 1060 nm to 1080 nm. In the following description, a laser beam having a wavelength of 1060 nm to 1080 nm is also referred to as a fundamental wave. Since the internal configuration of the laser beam oscillation source 11 is known, the description of the internal configuration will be omitted. The fiber laser oscillator 10 may oscillate a continuous wave (CW) or a pulse wave.

The beam coupler 13 includes a collimating lens 131, a bend mirror 132, a focusing lens 133, a dichroic mirror 134, a first photodiode 136, and a second photodiode 137. The first photodiode 136 is an example of a first detector, and the second photodiode 137 is an example of a second detector.

The collimated lens 131 parallelizes the laser beam of the divergent light emitted from the emission end of the feeding fiber 12 and converts it into collimated light. The laser beam of collimated light is incident on the bend mirror 132 and reflected. In the bend mirror 132, the reflecting surface of the laser beam is arranged at an angle of, for example, 45 degrees with respect to the optical axis of the collimated light. The laser beam reflected by the bend mirror 132 is incident on the focusing lens 133. The focusing lens 133 focuses the incident collimated light, converts it into convergent light, and causes it to be incident on the core of the process fiber 30.

The laser beam emitted from the feeding fiber 12 and traveling in the fiber laser oscillator 10 (beam coupler 13) may include unnecessary light due to induced Raman scattering generated in the laser beam oscillation source 11. The unwanted light has, for example, a center wavelength of 1130 nm. Hereinafter, the induced Raman scattering may be abbreviated as SRS, and the unnecessary light caused by the induced Raman scattering will be referred to as an SRS component.

The bend mirror 132 has a property of reflecting 99% of the incident laser beam and transmitting the remainder. The laser beam transmitted through the bend mirror 132 is incident on the dichroic mirror 134. The dichroic mirror 134 transmits a laser beam having a wavelength of less than 1100 nm other than the SRS component among the laser beams transmitted through the bend mirror 132, and reflects a laser beam having a wavelength of 1100 nm or more including the wavelength of the SRS component. In the dichroic mirror 134, the reflecting surface of the SRS component is arranged at an angle of, for example, 135 degrees with respect to the optical axis of the laser beam transmitted through the bend mirror 132.

Of the laser beams transmitted through the bend mirror 132, a laser beam having a wavelength of 1100 nm or more containing an SRS component is referred to as a laser beam having a first frequency band. Of the laser beams transmitted through the bend mirror 132, a laser beam having a wavelength of less than 1100 nm that does not contain an SRS component is referred to as a laser beam having a second frequency band.

In this way, the dichroic mirror 134 separates the laser beam transmitted through the bend mirror 132 into a laser beam that does not contain the SRS component and a laser beam that contains the SRS component.

The first photodiode 136 detects the first amount of light of a laser beam having a second frequency band. The second photodiode 137 detects the second light amount of the laser beam having the first frequency band without having the second frequency band.

The inductive Raman scattering determination unit 40 calculates the total light amount by adding the first light amount detected by the first photodiode 136 and the second light amount detected by the second photodiode 137. The total light amount is the light amount of the laser beam having the first and second frequency bands, and indicates the light amount of the entire frequency band of the laser beam. Further, the induced Raman scattering determination unit 40 divides the second light amount by the total light amount to calculate the ratio of the light amount of the SRS component to the total light amount. The ratio of the amount of light of the SRS component to the total amount of light will be hereinafter referred to as the amount of SRS component generated.

When the amount of SRS component generated exceeds the amount generated in advance, the induced Raman scattering determination unit 40 generates a status signal and supplies it to the NC device 50. The predetermined amount of generation is a predetermined threshold value.

The induced Raman scattering determination unit 40 may determine whether or not to output a status signal as follows. The induced Raman scattering determination unit 40 multiplies the second light amount by N times (for example, 100 times), and when the N times the second light amount exceeds the first light amount, supplies a status signal to the NC device 50.

In this way, the induced Raman scattering determination unit 40 may determine whether or not to output the status signal by comparing the total light amount with the second light amount which is the light amount of the SRS component, or the first one. Whether or not to output the status signal may be determined by comparing the amount of light with the amount of second light. In the former case, the comparison between the total light amount and the second light amount is, in detail, to determine whether or not the ratio of the second light amount to the total light amount exceeds a predetermined threshold value. In the latter case, in order to facilitate the comparison between the first light amount and the second light amount, N is a natural number, the second light amount is multiplied by N, and the magnitude relationship is determined. It is equivalent to determining whether or not the ratio of the second light amount to the light amount exceeds a predetermined threshold value. In addition, unlike the threshold value in the former case and the latter case, it is set to an appropriate value.

When the NC device 50 receives the status signal supplied from the induction Raman scattering determination unit 40, the NC device 50 reduces the output command value supplied to the fiber laser oscillator 10 so as to reduce the laser output of the laser beam emitted from the fiber laser oscillator 10. do. The output command value is a laser output value commanded by W (watt) or kW (kilowatt). In addition to this, the NC device 50 controls the drive unit 21 so as to slow down the processing speed (cutting speed) of the sheet metal W. The NC device 50 reduces the output command value for the fiber laser oscillator 10 to the extent that the SRS component is not generated, and slows down the processing speed so that the sheet metal can be cut even if the laser output is lowered. In this case, the fiber laser oscillator 10 may oscillate a continuous wave or a pulse wave.

When the fiber laser oscillator 10 oscillates a pulse wave, the NC device 50 may change the pulse frequency instead of adjusting the output command value and the processing speed. The NC device 50 raises or lowers the pulse frequency so as to reduce the SRS component. In this case, since the average laser output does not change even if the pulse frequency is adjusted, the NC device 50 does not need to control the drive unit 21 so as to change the processing speed of the sheet metal W.

FIG. 2A shows the relationship between the output command value and the maximum cutting speed when cutting stainless steel having a plate thickness of 3.0 mm by the laser processing machine 1A. FIG. 2B shows the relationship between the output command value and the maximum cutting speed when cutting an aluminum plate having a plate thickness of 3.0 mm by the laser processing machine 1A. In FIGS. 2A and 2B, the broken line shows the relationship between the output command value and the maximum cutting speed under the condition that the SRS component does not occur. Here, when the output command is expressed as a percentage, for example, if the laser beam can output a maximum output of 10 kW at the injection end of the process fiber 30, 100% is 10 kW and 75% is 7.5 kW. show. The ratio of the maximum cutting speed is the ratio of the maximum cutting speed to the maximum cutting speed cutting speed at the maximum output in terms of the light intensity (laser output) of the laser beam output by each output command. Hereinafter, the light intensity of the laser beam will also be referred to as a laser output.

When the laser output at the injection end of the process fiber 30 output by the output command commanded by the laser machine 1A is lower than the expected laser output, the ratio of the maximum cutting speed is also the actual laser. It decreases by n% depending on the output. That is, FIGS. 2A and 2B are actually measured at the injection end of the process fiber 30 in response to the ratio (broken line) of the maximum cutting speed expected for the output command at the injection end of the process fiber 30 and the output command. It shows whether the ratio of the cutting speed according to the laser output was reduced by n% from the ratio of the maximum cutting speed.

As shown in FIGS. 2A and 2B, stainless steel and aluminum plates having a thickness of 3.0 mm can be cut at a maximum cutting speed of 100% when the output command is 100% under the condition that no SRS component is generated. Therefore, the ratio of each maximum cutting speed increases in proportion to the output command. However, under the condition that the SRS component is generated, when the output command is 100%, the ratio of the maximum cutting speed is reduced by 37% or 38% as shown by the downward arrow. That is, depending on the generation status of the SRS component, the ratio of the maximum cutting speed is reduced by 35% or more. Further, when the SRS component was generated at the output command of 97%, the maximum cutting speed decreased by 16% or 27%. It was found that the stainless steel and aluminum plates having a plate thickness of 3.0 mm generate SRS components when the output command exceeds 95% under the conditions where SRS components are generated.

As described above, even if the output command is 100% (even if the output command is 95% or more), when the SRS component is generated, the ratio of the maximum cutting speed is lower than the ratio of the maximum cutting speed of the output command of 80%. turn into.

FIG. 3 is a simplified diagram in which the light intensity of the SRS component and the light intensity of the fundamental wave are compared and arranged. In the laser processing machine 1A, when the laser beam oscillation source 11 oscillates a continuous wave and when a pulse wave is oscillated. The amount of SRS component generated is different between. It can be seen that the SRS component is remarkably generated when the pulse wave is oscillated than when the continuous wave is oscillated. The light intensity of the SRS component here refers to the light intensity of the SRS component that reduces the laser output, which affects the oscillation of the laser beam by the fiber laser oscillator 10. Although the SRS component may be generated during continuous wave oscillation, the SRS component that reduces the laser output is hardly generated, so the SRS component during continuous wave oscillation can be ignored.

4A and 4B show the amount of SRS component generated at each pulse frequency and the change in laser output. The duty ratio of the pulse wave is 50%. As shown in FIG. 4A, the amount of SRS component generated varies depending on the pulse frequency. As shown in FIG. 4B, the laser output varies with pulse frequency. In FIG. 4B, the laser output means that the laser output at the injection end of the process fiber 30 when the output command is 100% is 100% under the condition that the SRS component is not generated, and the condition is that the SRS component is generated. , The ratio of the laser output at the injection end of the process fiber 30 when the output command is 100% is shown. Further, FIGS. 4A and 4B show the transition of the laser output at the injection end of the feeding fiber 12 in addition to the laser output at the injection end of the process fiber 30.

From FIGS. 4A and 4B, it can be seen that when the pulse frequency changes, the amount of SRS component generated changes, and thereby the laser output changes. Specifically, an experiment in which the SRS component is rapidly generated on the injection end side of the process fiber 30 by setting the pulse frequency higher than 0 kHz to 2 kHz, and then gradually decreasing when the pulse frequency is set to a higher value. The result was. That is, the laser processing machine 1A can reduce the amount of SRS component generated by changing the output command value, and the amount of SRS component generated while suppressing the decrease in laser output by adjusting the pulse frequency. Can be reduced. Note that the pulse frequency of 0 kHz is continuous wave oscillation, and as described above, the laser output is hardly reduced due to the SRS component.

As described above, in the laser processing machine 1A of the first embodiment, when the amount of SRS component generated exceeds a predetermined amount, the laser output is reduced by changing the output command value as the first method. The processing conditions are adjusted to suit the reduced laser output. When the fiber laser oscillator 10 oscillates a pulse wave, the laser processing machine 1A of the first embodiment changes the pulse frequency as a second method. For example, the reduced laser output is adjusted to be recovered by making it a continuous wave or further increasing the frequency. Therefore, according to the laser processing machine 1A of the first embodiment, when the SRS component is generated, the processing quality is hardly deteriorated.

If a large amount of SRS component is generated, the fiber laser oscillator 10 may fail. According to the laser processing machine 1A of the first embodiment, it is possible to reduce the possibility that the fiber laser oscillator 10 will fail.

<Second Embodiment>
The laser beam machine 1B according to the second embodiment shown in FIG. 5 will be described. As shown in FIG. 5, the laser processing machine 1B includes a first image pickup device 138 as a first detector that receives a first light amount of a laser beam having a second frequency band in the beam coupler 13. .. The first image sensor 138 is, for example, a CCD. Hereinafter, the first image sensor 138 will be referred to as a first CCD 138. Other configurations in the beam coupler 13 are the same as those of the laser processing machine 1A. The basic operation and effect of the laser processing machine 1B are the same as those of the laser processing machine 1A described with reference to FIGS. 1 to 4.

That is, the first detector that receives the first light amount of the laser beam having the second frequency band in the beam coupler 13 does not have to be the first photodiode 136, but is the first CCD138. May be good. The first CCD138 can directly monitor the first light amount of the laser beam having the second frequency band.

<Third Embodiment>
The laser beam machine 1C according to the third embodiment shown in FIG. 6 will be described. As shown in FIG. 6, the laser beam machine 1C is used as a second detector that receives a second light amount of a laser beam having a first frequency band without having a second frequency band in the beam coupler 13. , A second image pickup element 139 is provided. The second image sensor 139 is, for example, a CCD. Hereinafter, the second image sensor 139 will be referred to as a second CCD 139. Other configurations in the beam coupler 13 are the same as those of the laser processing machine 1A. The basic operation and effect of the laser processing machine 1C are the same as those of the laser processing machine 1A.

That is, the second detector that receives the second light amount of the laser beam that does not have the second frequency band and has the first frequency band in the beam coupler 13 needs to be the second photodiode 137. Instead, it may be the second CCD139. The second CCD139 can directly monitor the second light amount of the SRS component of the laser beam having the first frequency band without having the second frequency band.

<Fourth Embodiment>
The laser beam machine 1D according to the fourth embodiment shown in FIG. 7 will be described. As shown in FIG. 7, the laser beam machine 1D includes a first CCD 138 as a first detector that receives a first light amount of a laser beam having a second frequency band in the beam coupler 13. Further, the laser beam machine 1D has a second CCD139 as a second detector that receives the second light amount of the laser beam having the first frequency band without having the second frequency band in the beam coupler 13. To prepare for. Other configurations in the beam coupler 13 are the same as those of the laser processing machine 1A. The basic operation and effect of the laser processing machine 1D are the same as those of the laser processing machine 1A.

<Fifth Embodiment>
The laser processing machine 1E according to the fifth embodiment shown in FIG. 8 will be described. As shown in FIG. 8, in the laser processing machine 1E, the laser beam transmitted through the bend mirror 132 in the beam coupler 13 is reflected by the reflection surface 13R provided on the inner wall of the beam coupler 13 and is reflected by the first photodiode 136. Incident. The first photodiode 136 receives a third amount of light from the reflected laser beam. That is, the first photodiode 136 receives the third light amount of the laser beam having the first and second frequency bands. The third amount of light in the fifth embodiment corresponds to the total amount of light in the first to fourth embodiments.

Further, the laser beam transmitted through the bend mirror 132 in the beam coupler 13 is reflected by the reflection surface 13R provided on the inner wall of the beam coupler 13 and is incident on the second photodiode 137 via the bandpass filter 135. The bandpass filter 135 transmits the first frequency band having a wavelength of 1100 nm or more in the incident frequency band. Therefore, the second photodiode 137 receives the second light amount of the laser beam that does not include the second frequency band but includes the first frequency band.

According to the fifth embodiment, it is not necessary to divide the entire wavelength band of the laser beam into a wavelength of 1100 nm or more and a wavelength of less than 1100 nm. The induced Raman scattering determination unit 40 does not need to calculate the total light amount by adding the first light amount other than the SRS component and the second light amount of the SRS component as in the first to fourth embodiments. Therefore, the step of calculating the total light amount by the guided Raman scattering determination unit 40 can be reduced.

In the fifth embodiment, the inductive Raman scattering determination unit 40 divides the second light amount received by the second photodiode 137 by the third light amount received by the first photodiode 136, and receives the entire light. The ratio of the amount of SRS component generated to the third amount of light is calculated. The basic operation and effect of the laser processing machine 1E are the same as those of the laser processing machine 1A.

<Sixth Embodiment>
The laser beam machine 1F according to the sixth embodiment shown in FIG. 9 will be described. As shown in FIG. 9, the laser beam machine 1F is a first detector as a first detector that receives a third amount of light of a laser beam transmitted through a bend mirror 132 and reflected by a reflecting surface 13R provided on an inner wall. It is equipped with a CCD 138. The third amount of light received by the first CCD138 corresponds to the total amount of light. Other configurations in the beam coupler 13 are the same as those of the laser processing machine 1E. The basic operation and effect of the laser processing machine 1F are the same as those of the laser processing machine 1E described with reference to FIG.

<7th Embodiment>
The laser beam machine 1G according to the seventh embodiment shown in FIG. 10 will be described. As shown in FIG. 10, the laser beam machine 1G includes a second CCD 139 as a second detector that receives a second light amount of the laser beam transmitted through the first frequency band by the bandpass filter 135. Other configurations in the beam coupler 13 are the same as those of the laser processing machine 1E. The basic operation and effect of the laser processing machine 1G are the same as those of the laser processing machine 1E.

<8th Embodiment>
The laser beam machine 1H according to the eighth embodiment shown in FIG. 11 will be described. As shown in FIG. 11, the laser beam machine 1H is a first detector as a first detector that receives a third amount of light of a laser beam transmitted through a bend mirror 132 and reflected by a reflecting surface 13R provided on an inner wall. It is equipped with a CCD 138. Further, the laser processing machine 1H includes a second CCD 139 as a second detector that receives a second light amount of the laser beam transmitted through the first frequency band by the bandpass filter 135. The basic operation and effect of the laser processing machine 1H are the same as those of the laser processing machine 1E.

<9th embodiment>
The laser beam machine 1J according to the ninth embodiment shown in FIG. 12 will be described. As shown in FIG. 12, in the ninth embodiment, in addition to the collimating lens 221 and the focusing lens 223, the processing head 22 includes a bend mirror 222, a dichroic mirror 224, a first photodiode 226, and a second photodiode. 227 is further provided. In the ninth embodiment, the beam coupler 13 may include only the collimating lens 131, the bend mirror 132, and the focusing lens 133. The first photodiode 226 is an example of a first detector, and the second photodiode 227 is an example of a second detector.

The laser beam of the divergent light emitted by the process fiber 30 is collimated by the collimated lens 221 and converted into collimated light, and is incident on the bend mirror 222. In the bend mirror 222, the reflecting surface of the laser beam is arranged at an angle of, for example, 135 degrees with respect to the optical axis of the laser beam emitted from the collimating lens 221. The laser beam reflected by the bend mirror 222 is incident on the focusing lens 223. The focusing lens 223 focuses the incident laser beam and irradiates the sheet metal W.

The laser beam emitted by the process fiber 30 and traveling in the processing head 22 may contain an SRS component generated in the fiber laser oscillator 10. The bend mirror 222 has a property of reflecting 99% of the incident effective laser beam and transmitting the remainder. The dichroic mirror 224 reflects a laser beam having a first frequency band containing an SRS component, and transmits a laser beam having a second frequency band other than the SRS component. In the dichroic mirror 224, the reflecting surface of the laser beam is arranged at an angle of, for example, 45 degrees with respect to the optical axis of the laser beam transmitted through the bend mirror 222.

The first photodiode 226 receives the first amount of light of the laser beam having the second frequency band transmitted through the dichroic mirror 224. The second photodiode 227 receives the second amount of light of the laser beam having the first frequency band reflected by the dichroic mirror 224.

The basic operation and effect of the laser processing machine 1J shown in FIG. 12 are the same as those of the laser processing machine 1A.

The light transmittance for each wavelength differs depending on the difference between the coating of the bend mirror 132 in the beam coupler 13 and the coating of the bend mirror 222 in the processing head 22. Therefore, although there is a difference in the intensity of the scattered light observed in the beam coupler 13 and the processing head 22, the SRS component can be measured in either the beam coupler 13 or the processing head 22.

<10th Embodiment>
The laser beam machine 1K according to the tenth embodiment shown in FIG. 13 will be described. As shown in FIG. 13, the laser processing machine 1K is a first detector as a first detector that receives a first light amount of a laser beam having a second frequency band transmitted through a dichroic mirror 224 in the processing head 22. The image pickup device 228 of the above is provided. The first image sensor 228 is, for example, a CCD. Hereinafter, the first image sensor 228 will be referred to as a first CCD and 228. Other configurations in the processing head 22 are the same as those of the laser processing machine 1J. The basic operation and effect of the laser processing machine 1K are the same as those of the laser processing machine 1J.

<11th Embodiment>
The laser processing machine 1L according to the eleventh embodiment shown in FIG. 14 will be described. As shown in FIG. 14, the laser processing machine 1L is a second detector as a second detector that receives a second amount of light of a laser beam having a first frequency band reflected by the dichroic mirror 224 in the processing head 22. The image pickup device 229 of the above is provided. The second image sensor 229, for example, a CCD. Hereinafter, the second image sensor 229 will be referred to as a second CCD 229. Other configurations in the processing head 22 are the same as those of the laser processing machine 1J. The basic operation and effect of the laser processing machine 1L are the same as those of the laser processing machine 1J.

<12th Embodiment>
The laser beam machine 1M according to the twelfth embodiment shown in FIG. 15 will be described. As shown in FIG. 15, the laser processing machine 1M is a first detector as a first detector that receives a first amount of light of a laser beam having a second frequency band transmitted through a dichroic mirror 224 in the processing head 22. The CCD 228 is provided. Further, the laser processing machine 1M includes a second CCD229 as a second detector that receives a second amount of light of a laser beam having a first frequency band reflected by the dichroic mirror 224 in the processing head 22. Other configurations in the processing head 22 are the same as those in the ninth embodiment. The basic operation and effect of the laser processing machine 1M are the same as those of the laser processing machine 1J.

<13th Embodiment>
The laser beam machine 1N according to the thirteenth embodiment shown in FIG. 16 will be described. As shown in FIG. 16, in the laser machining machine 1N, the laser beam transmitted through the bend mirror 222 in the machining head 22 is reflected by the reflection surface 22R provided on the inner wall of the machining head 22 and is reflected by the first photodiode 226. Incident. The first photodiode 226 receives a third amount of light from the reflected laser beam. That is, the first photodiode 226 receives a third amount of light from the laser beam having the first and second frequency bands. The third amount of light received by the first photodiode 226 corresponds to the total amount of light.

Further, the laser beam transmitted through the bend mirror 222 in the processing head 22 is reflected by the reflecting surface 22R and is incident on the second photodiode 227 via the bandpass filter 225. The bandpass filter 225 transmits the first frequency band having a wavelength of 1100 nm or more in the incident frequency band. Therefore, the second photodiode 227 receives the second light amount of the laser beam that does not include the second frequency band but includes the first frequency band.

According to the thirteenth embodiment, the same effect as that of the fifth embodiment is obtained. The basic operation and effect of the laser processing machine 1N are the same as those of the laser processing machine 1J.

<14th Embodiment>
The laser beam machine 1P according to the 14th embodiment shown in FIG. 17 will be described. As shown in FIG. 17, the laser processing machine 1P is a first detector that receives a third amount of light of the laser beam transmitted through the bend mirror 222 in the processing head 22 and reflected by the reflecting surface 22R provided on the inner wall. The first CCD228 is provided. The third amount of light received by the first CCD228 corresponds to the total amount of light. Other configurations in the processing head 22 are the same as those in the thirteenth embodiment. The basic operation and effect of the laser processing machine 1P are the same as those of the laser processing machine 1N.

<15th Embodiment>
The laser beam machine 1Q according to the fifteenth embodiment shown in FIG. 18 will be described. As shown in FIG. 18, the laser processing machine 1Q includes a second CCD229 as a second detector that receives a second amount of light of the laser beam transmitted through the first frequency band by the bandpass filter 225. Other configurations in the processing head 22 are the same as those of the laser processing machine 1N. The basic operation and effect of the laser processing machine 1Q are the same as those of the laser processing machine 1N.

<16th Embodiment>
The laser beam machine 1R according to the 16th embodiment shown in FIG. 19 will be described. As shown in FIG. 19, the laser processing machine 1R is a first detector that receives a third amount of light of a laser beam transmitted through a bend mirror 222 in the processing head 22 and reflected by a reflecting surface 22R provided on the inner wall. The first CCD228 is provided. Further, the laser processing machine 1R includes a second CCD 229 as a second detector that receives a second light amount of the laser beam transmitted through the first frequency band by the bandpass filter 225. The basic operation and effect of the laser processing machine 1R are the same as those of the laser processing machine 1N.

The present invention is not limited to the present embodiment described above, and various modifications can be made without departing from the gist of the present invention.

1A to 1H, 1J to 1N, 1P to 1R Laser processing machine 10 Fiber laser oscillator 11 Laser beam oscillation source 12 Feeding fiber 13 Beam coupler 20 Processing unit 21 Drive unit 22 Processing head 30 Process fiber 40 Inductive Raman scattering determination unit 50 NC Equipment 132,222 Bend mirror 134,224 Dycroic mirror 135 Bandpass filter 136,226 First photodiode (first detector)
137,227 Second photodiode (second detector)
138,228 First image sensor (first detector)
139,229 Second image sensor (second detector)

Claims (8)

A laser oscillator that emits a laser beam and
A processing head that processes sheet metal using a laser beam emitted from the laser oscillator,
A drive unit that moves the processing head relative to the sheet metal,
Among the laser beams traveling in the laser oscillator or the processing head, the first light amount of the laser beam having a second frequency band lower than the first frequency band including unnecessary light due to induced Raman scattering or the above. A first detector that detects the total amount of light of the laser beam having the first and second frequency bands, and
A second detector that detects a second amount of light of a laser beam traveling in the laser oscillator or in the processing head, which does not have the second frequency band but has the first frequency band. When,
Whether the total light amount obtained by adding the first light amount and the second light amount or the ratio of the second light amount to the total light amount detected by the first detector exceeds a predetermined threshold value, or the first light amount A guided Raman scattering determination unit that outputs a status signal when the ratio of the second light amount to the light exceeds a predetermined threshold value.
When the status signal output from the induced Raman scattering determination unit is received, an output command value is supplied to the laser oscillator so as to reduce the laser output of the laser oscillator, and the processing head is relative to the sheet metal. A control device that controls the drive unit so as to reduce the machining speed to be moved to
Laser processing machine equipped with. A laser oscillator that emits a pulsed laser beam,
A processing head that processes sheet metal using a laser beam emitted from the laser oscillator,
A drive unit that moves the processing head relative to the sheet metal,
Among the laser beams traveling in the laser oscillator or the processing head, the first light amount of the laser beam having a second frequency band lower than the first frequency band including unnecessary light due to induced Raman scattering or the above. A first detector that detects the total amount of light of the laser beam having the first and second frequency bands, and
A second detector that detects a second amount of light of a laser beam traveling in the laser oscillator or in the processing head, which does not have the second frequency band but has the first frequency band. When,
Whether the total light amount obtained by adding the first light amount and the second light amount or the ratio of the second light amount to the total light amount detected by the first detector exceeds a predetermined threshold value, or the first light amount A guided Raman scattering determination unit that outputs a status signal when the ratio of the second light amount to the light exceeds a predetermined threshold value.
A control device that controls the laser oscillator so as to change the pulse frequency of the laser beam emitted by the laser oscillator when the status signal output from the induced Raman scattering determination unit is received.
Laser processing machine equipped with. The laser oscillator or the processing head
A bend mirror that reflects the laser beam,
Of the laser beams transmitted through the bend mirror, a dichroic mirror that transmits the second frequency band and
The laser processing machine according to claim 1 or 2. The laser oscillator or the processing head
A bend mirror that reflects the laser beam,
Of the laser beams transmitted through the bend mirror, a bandpass filter that transmits the first frequency band and
The laser processing machine according to claim 1 or 2. The laser processing machine according to any one of claims 1 to 4, wherein the first detector is a first photodiode or a first image pickup device. The laser processing machine according to any one of claims 1 to 5, wherein the second detector is a second photodiode or a second image pickup device. A second frequency band lower than the first frequency band containing unnecessary light due to induced Raman scattering among the laser beams transmitted through the bend mirror included in the beam coupler or the processing head in the laser oscillator that emits the laser beam. The amount of light of 1 or the total amount of light of the laser beam including the first and second frequency bands is detected by the first detector.
Among the laser beams transmitted through the bend mirror, the second light amount of the laser beam that does not include the second frequency band but includes the first frequency band is detected by the second detector.
Whether the total light amount obtained by adding the first light amount and the second light amount or the ratio of the second light amount to the total light amount detected by the first detector exceeds a predetermined threshold value, or the first light amount When the ratio of the second light intensity to the above exceeds a predetermined threshold value, a status signal is generated.
When the status signal is generated, an output command value is supplied to the laser oscillator so as to reduce the laser output of the laser oscillator, and the machining speed for moving the machining head relative to the sheet metal to be machined is lowered. Laser processing method. Of the laser beams transmitted through the bend mirror provided in the beam coupler or processing head in the laser oscillator that emits the laser beam of the pulse wave, the second frequency below the first frequency band including unnecessary light due to induced Raman scattering. The first detector detects the first light intensity of the band or the total light intensity of the laser beam including the first and second frequency bands.
Among the laser beams transmitted through the bend mirror, the second light amount of the laser beam that does not include the second frequency band but includes the first frequency band is detected by the second detector.
Whether the total light amount obtained by adding the first light amount and the second light amount or the ratio of the second light amount to the total light amount detected by the first detector exceeds a predetermined threshold value, or the first light amount When the ratio of the second light intensity to the above exceeds a predetermined threshold value, a status signal is generated.
A laser processing method that changes the pulse frequency of a laser beam emitted by a laser oscillator when the status signal is generated.

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