JPH09108866A - Laser emission mechanism for processing having mechanism for discriminating processing defect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve processing efficiency by simultaneously deciding whether a processing condition is non-defective or defective by comparing the luminance detected by a luminance sensor with a criterion value. SOLUTION: The laser beam P sent from a laser beam machine body is made incident on a first condenser 9 and is condensed to the processing part A of a work W, by which the work is processed. At this time, a processing beam q is generated and is made into parallel beams by the condenser 9. These parallel beams are made incident on a second condenser 10. The component q1 progressing on a light axis line α is advanced in the as-it-is direction as q10 while being accompanied by some attenuation by a light diffuser 11 between the second condenser 10 and the first luminance sensor 12. The component is made incident only on the first luminance sensor 12. The component q2 except q1 is diffused by the light diffuser 11 and is made into a blurring beam q20 . The beam is made partly incident as the beam of the luminance equal to the first luminance 12 and on the second luminance sensor 13 as well. Decision is made by making comparison with the reference value by using the ratio of q10 and q20 , by which the exact decision is made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing laser emitting mechanism having a processing defect determination mechanism.

[0002]

2. Description of the Related Art Conventionally, in processing such as welding, fusing, and perforation using a laser processing machine, as a means for determining a processing defect, for example, a method of observing a processed portion with a microscope, There have been proposed methods for detecting and monitoring the processing noise that occurs, or for detecting the light emission state of the processing part during processing, but none of these are suitable for production sites and have been put to practical use. There wasn't.

For example, in observation with a microscope, after laser processing, a person looks at the processing state with a microscope to determine a defect, or an image processing apparatus determines a defect, but it takes time and costs, and the processing is also performed. At the same time, it could not be determined.

Further, for example, in the method of detecting and monitoring the processing sound, nitrogen gas or the like is often sprayed during processing, and the spraying sound, the operation sound generated by the apparatus itself and the processing sound are mixed. However, it is difficult to extract only the processed sound from them, and the judgment criteria are different depending on the processing conditions, so the versatility is poor.

On the other hand, a method of placing a sensor such as a photodiode near the processing point and estimating the processing state by observing the light emission state of the processing section during processing is used. However, since the judgment criteria differ depending on the processing conditions as in the above, the versatility is poor. Moreover, since dirt such as gas and mist generated during processing adheres to the sensor, the accuracy of determination tends to deteriorate.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present inventors have
Providing a machining defect determination mechanism that can discriminate machining defects during laser machining in real time and that can accurately discriminate machining defects under any machining conditions simply by setting certain criteria. Therefore, as a result of repeated experiments and observations to understand the behavior of the machined part during machining, surprisingly, when a machining defect occurs, the fire pillar generated from the machined part emits light that spreads around, so-called fumes. It was found that there is a luminescence shape that accompanies it, and on the other hand, when the processing condition is good, there is almost no fumes, and there is a fact that the luminescence shape is elongated vertically.

However, even if the shape of the light emitted from the processed portion is observed, any problem can be solved by using the conventional method, that is, observing near the processing point or recognizing the shape by the image processing apparatus. Not done. Therefore, the present inventors
As a result of examining whether it is possible to distinguish the light having the different shapes as different from each other without using the conventional method, the shape of the light emission is grasped as the spatial distribution of the light intensity, that is, the brightness distribution state. The present inventors have completed the present invention as a result of further knowledge based on this knowledge that the shape of light emission can be recognized by measurement.

That is, according to the present invention, it is possible to discriminate a machining defect at the time of laser machining in real time, and moreover, it is possible to accurately discriminate a machining defect even if any machining condition is used only by setting a certain criterion. It is an object of the present invention to provide a processing laser emission mechanism including a processing defect determination mechanism that can perform

[0009]

Means for Solving the Problems The present invention provides (1) a laser beam machine, which reflects a laser beam on an optical path of a laser beam emitted from a light emitting section and travels to process a workpiece. A bender mirror provided with a dielectric reflection film capable of transmitting the processing light generated from the processing portion when the laser beam is reflected is provided, and the first focus is provided on the optical path of the laser which is reflected by the bender mirror and advances. A body is arranged, a second light collector is arranged on the optical path after the processing light has passed through the bender mirror, and only the incident light of one specific angle is placed at the tip of the second light collector. A light diffuser having a function of transmitting as emitted light having a predetermined one emission angle and scattering other incident light inside to transmit as a plurality of emitted light having different emission angles is further arranged. Ahead of the above Of processing light from the center point of the section, arranged first luminance sensor position on the optical axis of the light toward the opposite direction to the direction of the laser incident to the processing unit,
Processing defect determination, characterized in that at least one second luminance sensor is arranged at a predetermined distance from the first luminance sensor in a direction perpendicular to the optical axis. The gist is a processing laser emitting mechanism provided with the mechanism.

According to the present invention, when the light emission of the fire column generated from the processed portion of the workpiece by laser processing is observed from above in the vertical direction in the height direction, the emission column planar shape of the fire column with a certain reference value as the boundary value, that is, Utilizing the knowledge obtained by the present inventors that the spatial distribution of luminance in a plan view can be binarized as a value that reflects the quality of the processed state, the light emission of the fire pillar is vertically above the height direction of the fire pillar. By detecting and binarizing the spatial distribution of the brightness in the plan view, it is possible to determine the quality of the processed state.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a conceptual diagram showing a laser processing machine in which an emitting unit is equipped with a processing laser emitting mechanism having a processing defect determination mechanism of the present invention. FIG.
FIG. 3 is an enlarged schematic vertical cross-sectional view of the laser emission mechanism 7 in FIG. 1, showing an example of the configuration of the laser emission mechanism 7. In FIG. 2, hatching showing the end face of the cut portion is omitted.

The laser processing machine 1 is usually a processing machine body 2
In order to take out the laser oscillator 3 provided therein and the laser output from the laser oscillator 3 from the processing machine main body 2 to the outside, and to enter the optical fiber 5 optically connected to propagate the laser. And an emitting unit 6 for optically emitting a laser to the outside of the processing machine 1 which is optically connected to the tip of the optical fiber 5. And usually,
The processing laser emitting mechanism (hereinafter, simply referred to as a laser emitting mechanism) 7 including the processing defect determining mechanism of the present invention is used so as to configure the inside of the injection unit 6.

In FIGS. 1 and 2, 8 is a bender mirror, 9 is a first light collector, 10 is a second light collector, 11 is a light diffuser,
Reference numerals 12 and 13 represent a first brightness sensor and a second brightness sensor, respectively. Note that FIG. 2 shows an example in which the laser emitting mechanism 7 is housed in the case body 14 of the emitting unit 6. In the case body 14, 14a is a laser emission port, and 15 is a supply port for N ₂ gas or the like to be supplied to the processing portion during processing.

The object machined by using the laser beam machine 1 is usually metal such as stainless steel, iron or steel, but is not limited to them. The types of processing are welding,
The present invention is applicable to any case, such as fusing and perforation.

As the type of laser, all of those generally used for processing such as YAG laser, CO ₂ laser and excimer laser can be applied to the present invention.

The configuration examples of the laser processing machine described above are merely examples, and the present invention is not limited to these.
Further, in the present invention, the laser emitting mechanism 7 does not necessarily have to be used in the above-described mode, and for example, the processing machine body 2
1 may be installed inside, or the laser emitting section 71 and the processing defect determining mechanism section 72 shown in FIG. 1 may be separated and the two may be optically connected by an optical fiber or the like.

In the laser emitting mechanism 7, a bender mirror 8 is arranged on the optical path of a light emitting section (not shown), that is, a laser (indicated by a solid arrow p in the figure) emitted by a laser oscillator and traveling.

The bender mirror 8 is capable of reflecting the laser p on the substrate 81 and transmitting the processing light q generated from the processing portion A when the workpiece W is processed by the laser p. A dielectric reflection film 82 is provided, and a glass plate made of BK7 or the like is usually formed from a conventionally known dielectric such as SiO ₂ , TiO ₂ or a multilayer film of these by vacuum deposition or sputtering. A dielectric reflection film 82 is thinly formed as a laser reflection film on the surface of a light-transmissive substrate 81 such as the above.

The base 81 forming the bender mirror 8 is not limited to the flat plate shape described above.
For example, the two surfaces that are phase-oriented may not be parallel to each other and may not have a twist relationship, and specifically, for example, a prism-shaped (triangular prism) shape may be used. The base 81 may be made of any material as long as it can transmit a laser beam, but the so-called optical glass such as BK7 described above is preferable.

The film structure including the components of the dielectric material constituting the dielectric reflection film 82 and the conditions such as the film thickness is appropriately selected according to the type of laser used, and a laser such as a YAG laser is used. (Wavelength λ = 1.06μ
When m) is used, the composition of the component, the film thickness, etc. is such that the light of the above wavelength is transmitted. Of course, when another laser such as a CO ₂ laser or an excimer laser is used, the laser is reflected in accordance with each of them, and the laser is generated at least from the processed portion of the workpiece processed by the laser. A component that allows processing light to pass through,
The film configuration such as the film thickness is used.

The bender mirror 8 is usually arranged in a direction in which the laser p is irradiated on the surface on the side where the dielectric reflection film is formed so as not to impair the reflection efficiency of the laser p. However, it is not limited to this. Further, as shown in FIG. 2, the bender mirror 8 is usually provided at an angle where the surface on the side where the dielectric reflection film is formed faces the direction of incidence of the laser p, and hence the reflection angle. Is about 45 °. However, the present invention is not limited to this angle.

On the optical path of the laser p which is reflected and travels by the bender mirror 8, that is, in the direction perpendicular to the traveling direction of the laser p before passing through the bender mirror 8 and entering the bender mirror 8 in FIG. A first light collector 9 is movably arranged at a predetermined position along a direction perpendicular to the traveling direction of the laser p before entering the bender mirror 8. Although a structure for making the first light collector 9 movable is omitted in the drawing, a conventionally known mechanism used for focusing in an optical system such as a microscope can be used.

The first condensing body 9 is for condensing the laser p on the processed portion A of the workpiece W, and usually a single lens or a compound lens is used. The form of the single lens may be any conventionally known form as long as it can collect light, such as a double-sided convex lens, a one-sided convex and one-sided flat lens, and a one-sided convex and one-sided concave lens. When used as a combined lens, in addition to the above, a double-sided concave lens, a one-sided concave and one-sided flat lens, a one-sided concave and one-sided convex lens, and the like are used in combination.

The distance h between the first light collector 9 and the processed portion A of the workpiece W is usually a distance corresponding to the focal length f of the first light collector 9. Therefore, in other words,
The position on the optical axis α (indicated by an alternate long and short dash line in the drawing) from the center of the first light collecting body 9 by a distance corresponding to the focal length f is the place where the machining is performed, but the workpiece is processed. Material of
Depending on the shape, the thickness, etc., the processed portion of the workpiece may not always be located at a fixed distance from the laser emission port 14a at the tip of the case body 14, so the processed portion A and the light collector 9 may be located.
It is preferable that the light collecting body 9 is configured to be movable so that the distance h between and can be matched with the above-mentioned f.

Further, it is preferable to use a lens having a small f (short focal length) as the first condensing body 9 because the laser emitting unit 6 in the laser processing machine 1 can be made small. .

The processing light q (indicated by a chain double-dashed line in the figure) generated when the processing portion A of the workpiece W is processed by the laser p focused on the processing portion A by the first light collector 9. )
On the optical path after passing through the first condensing body 9 and further through the bender mirror 8, that is, on the side opposite to the first condensing body 9 across the bender mirror 8 in FIG. Is
The second light collector 10 is provided.

The second condensing body 10 emits light of the processing light q, which is emitted from the central portion a of the processing portion A in the direction opposite to the direction of the laser p incident on the processing portion A. It is provided so that its center is located on the optical axis α of q ₁ . The optical axis α may be refracted by the bender mirror 8 when passing through the bender mirror 8 and the position may shift as shown in FIG. This second light collector 10
Also, although it may be movably provided along the optical axis α or fixedly provided, it is preferably provided movably. When the light collector 10 is movably provided, it is preferable to maintain a distance from first and second brightness sensors 12 and 13 described later. The light diffuser 1 described later
1 may be a movable type or a fixed type, but when the second light condensing body 10 is movable, it should not interfere with the movement.

The form of the second light collector 10 is also the same as that of the first light collector.
Similar to the light condensing body 9 described above, any form may be used as long as it can condense light.

Similarly to the first light collector 9, the second light collector 10 preferably has a short focal length F because the laser emitting unit 6 can be downsized.

The second condensing body 1 is provided on the tip of the second condensing body 10 and on the side opposite to the bender mirror 8.
Of the processing light q that passes through 0 and travels while being collected by the light collector 10, only the incident light of one specific angle is transmitted as the emitted light q ₁₀ having a predetermined one emission angle, and the other incident light is incident. A light diffuser 11 having a function of scattering light internally and transmitting it as a plurality of outgoing lights q ₂₀ having different outgoing angles is provided.

Only the incident light of one specific angle is transmitted as the emitted light q ₁₀ having a predetermined one emission angle, and the other incident light is internally scattered to form a plurality of emitted light q ₂₀ having different emission angles. Light diffuser 1 having a function of transmitting light
Examples of 1 include polycrystalline glass such as opal glass and crystallized glass, a plurality of optical fibers bundled along the optical axis, and a structure in which glass is multilayer-coated for multiple reflection. Can be mentioned. The light diffuser 11 has a milky white appearance, and the lighter the degree of the milky white, the more excellent the light diffusing property. The light diffuser 11 has a large thickness (approximately 0.
Those having a light diffusion layer (having a thickness of 5 mm or more) are preferable.
So-called frosted glass also has a light diffusing layer on the surface and can be applied as the light diffusing body 11 of the present invention. However, the light diffusing layer is so thin that the sufficient effect may not be obtained in some cases.

FIG. 3 is an enlarged view corresponding to the periphery of the light diffuser 11 of FIG. In the light diffuser 11, as described above, [only the incident light of one specific angle is emitted light q having a predetermined one emission angle.
₁₀ is transmitted, and other incident light is internally scattered to be transmitted as a plurality of emitted lights q ₂₀ having different emission angles. Specifically, for example, , Of the processing light q traveling through the second light collector 10 and advancing from below vertically to the lower surface 11a of the flat light diffuser 11 arranged perpendicular to the optical axis α. Only the incident light with the incident angle θ ₁₁ = 90 °, the output angle θ ₁₂ =
The incident light that is transmitted as the outgoing light q ₁₀ having an outgoing angle of 90 ° and is incident at other incident angles θ ₂₁ other than 90 ° is scattered inside the light diffuser 11 (diffuse reflection inside), and the outgoing angle is It means transmitting as outgoing light q _{20 in} an unspecified number of directions having an outgoing angle of θ ₂₂ = 0 to 360 °. When a flat opal glass is used as the light diffuser 11 so as to be disposed perpendicularly to the optical axis α, the same action as shown in the above specific example is exhibited.

In the present invention, the light diffuser 11 travels on the optical axis of the light which is generated from the center point of the processed portion and goes in the direction directly opposite to the direction of the laser incident on the processed portion A.
It is sufficient if the structure and arrangement are such that only the light incident on is emitted at a specific angle and the other light is scattered and emitted in an unspecified number of angular directions. The shape does not need to be, but may be, for example, a prism shape, and q ₁ is not necessarily 90.
It does not have to be incident at an incident angle of ° and
Also q ₁₀ does not necessarily have to be emitted at an emission angle of 90 °.

Before the light diffuser 11 and on the opposite side of the second light collector 10 with the light diffuser 11 in between,
Of the processing light q from the center point a of the processing portion A, the first brightness sensor 12 is located at the position on the optical axis α of the light that is directed in the direction opposite to the direction of the laser incident on the processing portion A.
Is arranged. The distance position where the first brightness sensor 12 is arranged is from the second light collector 10 to the first light sensor 1.
The positions are preferably separated by a distance corresponding to the focal length F of 0. However, in the present invention, the distance of the first brightness sensor 12 from the second light collector 10 is not limited to the above. Of course, the first brightness sensor 12
Is located at the focal length of the second light collector,
Since the image of the processed part A can be obtained clearly, the brightness of the processed light can be detected more accurately by the brightness sensor, but even if the image of the processed part A is not always clear, the brightness is detected by the brightness sensor. There is almost no difference in this.

As the first brightness sensor 12, a conventionally known sensor capable of detecting brightness such as a germanium (Ge) sensor or a pin-photo sensor can be used, but a germanium (Ge) sensor is preferable. The germanium (Ge) sensor not only detects light with a wavelength in the range of 2 to 3 μm, but can also detect heat, so it is possible to monitor the temperature change of the processed part and process only by the light emission state of the processed part. As compared with the case of judging a defect, the possibility of a judgment error is significantly reduced, and more accurate judgment is possible.

When monitoring the temperature change of the processing part,
The temperature change over time is monitored using a recorder or oscilloscope. This cannot be done in real time, but it can be effectively used as data for confirming the result determined by the brightness.

With respect to the first brightness sensor,
The second luminance sensor 13 is arranged at a predetermined distance d from the optical axis α of the processing light q _{1 in} the direction perpendicular to the optical axis α.
The second brightness sensor 13 is also the first brightness sensor 12
The same as described above can be used.

The number of the second brightness sensor 13 is not limited to one, but two or more may be provided. In that case, the distances d from the first luminance sensor 12 do not all have to be the same,
They may all be provided at different distance positions, or some of them may be provided at the same distance position.

The distance d (mm) between the first luminance sensor 12 and the second luminance sensor 13 is [the diameter r of the processing light q generated in the processing portion A when the processing state is good.
(Mm)] × [focal length F (m of the second light collector 10
m)] / [focal length f (mm) of the first light collector] or larger. Here, the diameter r (mm) of the processing light q in the case where the above processing is good varies slightly depending on the processing conditions and the workpiece, but within the range of the actual processing conditions, it is about 1.5 mm at the maximum. d
The minimum value of depends only on the relationship between F and f. That is, for example, if F / f = 2, then d ≧ 2 mm. d
Is smaller than the above-mentioned minimum value, it is impossible to accurately discriminate the processing defect.

The maximum value of d is not particularly limited, but if it is too large, it is not possible to accurately discriminate the processing defect. However, when the second brightness sensor 13 is provided in the emitting unit 6, the maximum value of d is within a range of 1/2 of the thickness (diameter) D of the emitting unit 6, and within this range, the second value The meaning of providing the brightness sensor 13 is not lost.

The second brightness sensor 13 is provided so that the brightness of the light detected by the second brightness sensor 13 and the brightness of the light detected by the first brightness sensor 12 will be described later. In contrast, it is necessary to determine the quality of processing of the processed portion of the workpiece based on the result. By the way, in the range where d is smaller than the above minimum value, only the processing light q ₁₀ can be obtained and the processing light q ₂₀ cannot be obtained, although both the processing lights q ₁₀ and q ₂₀ are actually present. There is. Therefore, the second brightness sensor 1
If 3 is provided at a position smaller than the minimum value of d, the first
Both the light detected by the brightness sensor 12 and the light detected by the second brightness sensor 13 are the processing light q ₁₀ , and there is no difference in the brightness of both lights, so there is actually a processing defect. It may happen that even this cannot be discriminated, and this cannot achieve the object of the present invention.

Contrary to the above, in the range where d is too large, the processing light q ₂₀ is significantly attenuated and, in some cases, it is hardly obtained. Therefore, the second brightness sensor 1
When 3 is provided at a position where d is too large, the processing light q ₂₀ detected by the second brightness sensor 13 is detected to be smaller than the actual brightness, and as a result, the processing light is defective even if it is not actually defective. Therefore, the purpose of the present invention cannot be achieved.

According to the laser emitting mechanism of the present invention, the first
Processing light reaching the brightness sensor 12 of the processing part A is processing light q ₁₀ generated from the center point a of the processing part A, and light reaching the second brightness sensor 13 is generated from a part other than the center point a of the processing part A. Processing light scattered by the light diffuser 11 and then q ₂₀
Therefore, if the processing light q is a light in a narrow range centered on the processing point a, that is, if the processing light q is a vertically long one with a small emission diameter during processing, the first brightness sensor 12 The intensity of the light reaching the second luminance sensor 13 is weaker than the intensity of the light reaching the. On the contrary, when the processing light q is a light that spreads in a wide range around the processing point a, that is, when the processing light q is a relatively flat one with a large emission diameter and a low height, the first brightness There is not much difference between the intensity of light reaching the sensor 12 and the intensity of light reaching the second brightness sensor 13.

Therefore, when the laser emitting mechanism of the present invention is used, information on the brightness obtained from the first brightness sensor 12 and the second brightness sensor 13, that is, the degree of brightness is converted into an electric signal. Can be discriminated from each other and the processing defect can be determined by the degree of the difference. Specifically, for example, when the ratio or difference between the two is taken in the above-mentioned luminance, particularly preferably when the ratio between the two is taken, it can be determined that the processing is good if the value is within a certain reference value, and a certain reference value is set. If it exceeds, there is the above-mentioned reference value that can be determined as a processing defect, and therefore it can be used to determine a processing defect by the ratio of the two in the brightness.

More specifically, on the basis of the above-mentioned principle, the electric signal has a judgment function capable of judging whether the machining state is good or bad by comparing the electric signal with a reference value which is known in advance in an experiment. For example, a computing device such as a computer is prepared, and the electric signal converted by detecting the degree of brightness by each of the brightness sensors 12 and 13 is passed through an amplifier such as an amplifier, if necessary. It is also possible to input the electric signal to the arithmetic unit and compare this electric signal with a reference value which is known in advance in the arithmetic unit to judge the quality of the processing state.

The reference value may be set as a brightness ratio or a brightness difference. Further, it may be set as the ratio of the electric signal after converting the luminance into the electric signal, or may be set as the difference between the electric signals after converting the luminance into the electric signal. When set as the ratio or difference of electric signals after conversion of luminance, the reference value is a value obtained by multiplying the value of the ratio or difference of luminance by the conversion rate.

When a computer is used as the arithmetic unit, the above reference value may be stored in a storage device in the computer, or may be outside the computer body and exchange information electromagnetically with the computer body. For example, it may be stored in an external storage device using a recording medium such as a floppy disk.

The determination result of the quality of the processed state is normally displayed on a display device such as a CRT display electrically connected to the arithmetic unit as character information or image information such as a graph. The user can recognize the quality of the processed state by visually observing this information.
However, in the present invention, the output mode of the quality determination result of the processing state is not limited to the above, and in addition to the above, any mode such as notifying the quality determination result by sound can be adopted.

[0049]

Next, the operation of the laser emitting mechanism of the present invention will be described with reference to FIG.
It will be described based on. The laser p sent from the laser processing machine body (not shown in FIG. 2) is reflected by the dielectric reflecting film surface 82 of the bender mirror 8 and travels vertically downward to reach the first condensing body 9. Incident on. The laser p is focused by the first condensing body 9 on the processing portion A of the workpiece W placed on the optical axis α of the laser p at the position of the focal length f, where the machining is performed. Done. At this time, a pillar of fire rises from the processing portion A, and processing light q is generated.
This processing light q is made into parallel light by the first light collector 9,
It then passes through the bender mirror 8, possibly with some refraction therein, and then enters the second light collector 10.

The processing light q is at the position of the focal length F thereof by the second light collector 10, and is on the optical axis α of the light q ₁ of the processing light q which goes vertically upward from the center point a of the processing portion A. Although it is about to be condensed on the placed first luminance sensor 12, the light diffuser 11 between the second condenser 10 and the first luminance sensor 12 causes the processing light q The component q ₁ traveling on the optical axis α extending vertically upward from the center travels through the light diffuser 11 while maintaining the same direction as q ₁₀ with some attenuation, and this q ₁₀ is the first It is incident only on the brightness sensor 12 of.

However, q ₂ which is a component other than the above q _{1 in the} processing light q is diffused by the light diffuser 11 and becomes a dim light q ₂₀ showing equal brightness over the entire area of the light diffuser 11. Then, a part thereof enters the first brightness sensor 12 and the second brightness sensor 13 as light having the same brightness.

Therefore, as shown in FIG. 4A, the processing light q has only a component of q ₁ , that is, the degree of spread around the processing portion center point a with a line along the laser irradiation direction as an axis. Is small light, the brightness of q ₁₀ detected by the first brightness sensor 12 is as shown in FIG.
This is extremely large compared to the brightness of a part of q ₂₀ detected by the second brightness sensor 13. On the contrary, as shown in FIG. 5A, when the processing light q has a q ₁ component as well as a q ₂ component, that is, when the processing light q has a large degree of spread around the laser irradiation direction as an axis, As shown in FIG. 5B, the brightness of q ₁₀ detected by the first brightness sensor 12 is not so large as the brightness of a part of q ₂₀ detected by the second brightness sensor 13. .

The absolute values of q ₁ and q ₂ , and hence q ₁₀ and q ₂₀ depend on the processing conditions and the kind of the workpiece. For example, if the laser output is doubled, both q ₁₀ and q ₂₀ It depends on the processing conditions, such as doubling, but q ₁₀
Because the ratio of the q ₂₀ is close to the always constant without depending on the type of machining conditions and the workpiece, it is determined in comparison with a reference value in this value with the value of the ratio of the q ₁₀ and q ₂₀ For example, even if the processing conditions are changed, it is possible to accurately judge the quality of the processing state, which is possible in the past. The processing defect determination mechanism according to the present invention makes it possible to determine a processing defect as described above.

As a guide for setting the above-mentioned reference value, see FIG.
As shown in (b), the value of the ratio of the brightnesses (δ ₁ ) and (δ ₂ ) of q ₁₀ and q ₂₀ (δ ₁ ) obtained when the processing state is good (δ ₁
/ Δ ₂ ) and the respective brightnesses (δ ₁ ) of q ₁₀ and q ₂₀ obtained when the processing state is poor, as shown in FIG.
It suffices if it is between the value (δ ₁ / δ ₂ ) of the ratio of (δ ₂ ).
There are several types of light emission (δ ₁ / δ ₂ ) when processing is defective, and among them, when the processing state is good (δ ₁
It is accurate to set the reference value by knowing the value that is closest to / δ ₂ ) in advance through experiments, etc., and setting that value as (δ ₁ / δ ₂ ) obtained when the processing state is defective. It is essential for making a judgment.

[0055]

As described above, according to the present invention, the processing laser emitting mechanism provided with the processing defect determining mechanism is on the optical path of the processing light generated from the processing part when the workpiece is processed by the laser. A first condenser lens and a second condenser lens, and transmits only an incident light of one specific angle as an emission light having a predetermined one emission angle at the tip of the second condenser lens,
A light diffuser having a function of scattering other incident light internally and transmitting it as a plurality of emitted lights having different emission angles is arranged, and further from the center point of the processed portion at the tip of the light diffuser. Of the processing light, at least two brightness sensors are arranged at a position on the optical axis of the light that is directed in the direction opposite to the direction of the laser that is incident on the processing section and at a position that is separated from it by a predetermined distance. Since it has the following configuration,
By comparing the brightness detected by two brightness sensors, for example, as a ratio or difference between them, with a certain judgment reference value, the shape of the light emission of the pillar of fire can be accurately determined without being affected by the processing conditions. Can be binarized to the value reflected in.

Therefore, by using the mechanism of the present invention, it is possible to determine whether the machining state is good or bad, even if any machining condition is used, with the determination reference value being fixed to a constant value.

Further, since the brightness of the light emission of the fire pillar generated during the processing is detected, the quality of the processed state can be determined at the same time during the processing.

If the mechanism of the present invention is adopted, the quality of the laser processing state can be determined quickly and accurately, so that the processing efficiency can be remarkably improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a laser processing machine to which a processing laser emitting mechanism having a processing defect determination mechanism of the present invention is applied.

FIG. 2 is a schematic vertical cross-sectional view of a processing laser emission mechanism including a processing defect determination mechanism of the present invention.

FIG. 3 is an enlarged view showing the periphery of the light diffuser of FIG.

FIG. 4 is a diagram showing an example of a spatial distribution of luminance in the case where a pillar of fire has a vertically elongated light emission shape.

FIG. 5 is a diagram showing an example of a spatial distribution of brightness when a pillar of fire shows a shape of light emission expanded with fumes.

[Explanation of symbols]

1 Laser Processing Machine 2 Processing Machine Main Body 3 Laser Oscillator 4 Incident Unit 5 Optical Fiber 6 Emission Unit 7 Laser Emission Mechanism Equipped with Machining Failure Detection Mechanism 8 Bender Mirror 81 Base Body 82 Dielectric Reflective Film 9 First Condenser 10 2nd Condenser 11 Light diffuser 12 First luminance sensor 13 Second luminance sensor 14 Case body p Laser light q Processing light q ₁ Processing light component going from the center of the processing part to the direction opposite to the laser incident direction q ₂ q ₁ Processed light components other than q ₁₀ q ₁ is light after passing through the light diffuser q ₂₀ q ₂ is light after passing through the light diffuser W Workpiece A Processed portion a Optical axis of the processing point α q ₁

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01S 3/101 9219-2H G02B 7/18 702

Claims (1)

[Claims] 1. In a laser processing machine, a processing light that reflects the laser and is emitted from the processing section when the workpiece is processed by the laser is provided on the optical path of the laser that is emitted from the light emitting section and travels. A bender mirror provided with a dielectric reflection film capable of transmitting light is arranged, and a first condensing body is arranged on an optical path of a laser which is reflected by the bender mirror and travels, and the processing light is the bender. A second condensing body is arranged on the optical path after passing through the mirror, and only the incident light of one specific angle is transmitted to the tip of the second condensing body as the outgoing light having a predetermined one outgoing angle. A light diffusing body having a function of scattering other incident light internally and transmitting as a plurality of outgoing light having different outgoing angles, and further, at the tip of the light diffusing body and at the center point of the processed portion. Out of the processing light from The first position is on the optical axis of the light that is directed in the direction opposite to the direction of the laser incident on the processing portion.
And a second brightness sensor at a predetermined distance from the optical axis with respect to the first brightness sensor. A laser emission mechanism for processing equipped with a processing defect determination mechanism characterized by.