JP2018202421A - Laser processing head and laser beam machine - Google Patents

Abstract

To provide a laser processing head which enables the quality monitoring of a processing state in laser processing without using a bend mirror.SOLUTION: A laser processing head comprises: a cylindrical body part (1); a connection part (1b), provided on one end side of the body part (1) to connect an optical fiber (4) for guiding a laser beam from a laser oscillator (62) into the body part (1); a nozzle part (1a), provided on the other end side of the body part (1) to emit the laser beam (L) guided by the optical fiber (4) connected with the connection part (1b); and an optical receiver (6), provided in a vicinity of the connection part (1b) by opening inside the body part (1) to receive a beam (Lf) entering the body part (1) from outside through the nozzle part (1a). The optical receiver (6) comprises a filter (6b3) which has the property of reducing or cutting a first wavelength band (fw1) including wavelengths of the laser beam (L) to make a received beam (Lf3) pass through the filter (6b3), and to emit the same toward a detector (7) that measures a luminous energy.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser processing head and a laser processing monitoring device. In particular, the present invention relates to a laser processing head and a laser processing machine that can monitor a processing state of laser processing performed by a laser processing head having an optical system that does not include a bend mirror based on reflected light from a processing portion.

It is known that when a processing defect occurs in the cutting process using laser light, the return reflected light increases remarkably as compared with a case where the processing is good.
This is because when the processing defect is a cutting defect, the light reflected by the uncut portion returns, and when the quality is poor, such as when the cutting surface is rough, the light diffusely reflected by the rough cutting surface is reflected. This is to come back.

  In view of this, a technique for monitoring the processing state in laser processing performed by a laser processing head having an optical system including a bend mirror using the return reflected light has been proposed. For example, Patent Document 1 describes a laser processing head that monitors the quality of a processing state based on reflected light from a processing site.

A laser processing head described in Patent Document 1 includes a bend mirror included in an optical system for irradiating a workpiece with laser light from a nozzle, an aperture and a band-pass filter disposed behind the mirror (opposite to the reflecting surface). A light amount sensor having
The bend mirror has an optical characteristic that reflects the light used for laser processing with high reflectivity and transmits the return reflected light that is reflected from the laser processed part of the workpiece and returns to the back light quantity sensor. Has been.
Specifically, the optical characteristics are that the reflectance is high for the wavelength band of laser light for laser processing and the wavelength band of light for alignment adjustment of the optical system, and the reflectance is low for other wavelength bands ( The transmittance is relatively high).

Japanese Patent Laid-Open No. 2006-97407

By the way, a bend mirror is used in an optical path in a laser processing head to guide a laser beam output from a laser oscillator to a nozzle by reflection on an optical element without using an optical fiber. Placed in.
However, in the case of using an optical fiber for guiding laser light from a laser oscillator to a laser processing head, which has been widespread in recent years, the optical system of the laser processing head can be configured without a bend mirror. The configuration and method using the bend mirror of the above could not be applied.
Therefore, there has been a demand for a specific device that can monitor the quality of the machining state in laser machining using a laser machining head that does not use a bend mirror.

  Therefore, the problem to be solved by the present invention is to provide a laser processing head and a laser processing machine capable of monitoring the quality of the processing state in laser processing without using a bend mirror.

In order to solve the above problems, the present invention has the following configuration.
1) A cylindrical main body,
A connecting portion that is provided on one end side of the main body portion and connects an optical fiber for guiding laser light from a laser oscillator to the main body portion;
A nozzle part that is provided on the other end side of the main body part and emits the laser light guided by the optical fiber connected to the connection part;
A light receiving portion that is provided in the vicinity of the connection portion so as to be opened inside the main body portion, and that receives light that has entered the main body portion from the outside through the nozzle portion;
With
The light receiving unit is
A laser processing head including a filter having a characteristic of reducing or cutting a first wavelength band including the wavelength of the laser light, and emitting the received light toward a detector that measures the amount of light after passing through the filter. .
2) The filter
On the one surface side, the first optical film having a first characteristic that reduces or cuts light in the first wavelength band and a second wavelength band shorter than the first wavelength band,
A second optical film having a second characteristic that transmits a third wavelength band between the first wavelength band and the second wavelength band on the other surface side;
The light receiving section is the laser processing head according to 1), in which the received light passes through the first optical film and the second optical film in this order and is emitted toward the detector.
3) a laser oscillator, a laser processing head, and an optical fiber that is connected between the laser oscillator and the laser processing head and guides the laser light output from the laser oscillator to the laser processing head,
The laser processing head is
A tubular body,
A connecting portion that is provided on one end side of the main body and connects the optical fiber;
A nozzle part that is provided on the other end side of the main body part and emits the laser light guided by the optical fiber;
A light receiving portion that is provided in the vicinity of the connection portion so as to be opened inside the main body portion, and that receives light that has entered the main body portion from the outside through the nozzle portion;
A detector for measuring the amount of the light that has passed through the light receiving unit;
With
The light receiving unit is
The laser processing machine includes a filter having a characteristic of reducing or cutting a first wavelength band including the wavelength of the laser light, and outputs the received light to the detector after passing through the filter.
4) The filter
On the one surface side, the first optical film having a first characteristic that reduces or cuts light in the first wavelength band and a second wavelength band shorter than the first wavelength band,
A filter having a second optical film having a second characteristic that transmits a third wavelength band between the first wavelength band and the second wavelength band on the other surface side;
The light receiving section is the laser processing machine according to 3), in which the incident light passes through the first optical film and the second optical film in this order and is emitted toward the detector.

  According to the present invention, it is possible to monitor the processing state in laser processing without using a bend mirror.

FIG. 1 is a longitudinal sectional view for explaining a machining head 51 which is an example of a laser machining head according to an embodiment of the present invention. FIG. 2 is a perspective view for explaining the overall configuration of the laser processing machine 61 provided with the processing head 51. FIG. 3 is a longitudinal sectional view for explaining the light receiving unit 6 attached to the processing head 51. FIG. 4 is a longitudinal sectional view for explaining a traveling path of the reflected light Lf from the laser processing site in the processing head 51. FIG. 5 is a graph for explaining the wavelength characteristics of the reflected light Lf when processing is good. FIG. 6 is a graph for explaining the wavelength characteristics of the reflected light Lf at the time of processing failure. FIG. 7 is a graph for explaining the wavelength characteristic of the reflected reflected light Lf4 that has passed through the filter member 6b of the light receiving unit 6. In FIG.

The configuration of the laser processing head and the laser processing machine according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3 by a laser processing head 51 (hereinafter, processing head 51) and a laser processing machine 61 as examples. explain.
FIG. 1 is a schematic longitudinal sectional view of the processing head 51, and FIG. 2 is a schematic perspective view for explaining the overall configuration of the laser processing machine 61. As shown in FIG. FIG. 3 is a longitudinal sectional view for explaining the light receiving unit 6 included in the machining head 51.
For convenience of explanation, the respective directions in the vertical and horizontal directions are defined by arrows in the drawings.

As shown in FIG. 1, the processing head 51 includes a main body 1 that has a cylindrical shape, and a head optical system P <b> 1 that includes a collimating lens 2 and a condenser lens 3 provided inside the main body 1. The head optical system P1 has a function of adjusting the focus of the laser light L output from the processing head 51.
That is, the condenser lens 3 is supported by a holder 3a that moves in the axial direction by a focus adjustment mechanism (not shown), and the focal position of the laser light L emitted from the processing head 51 is adjusted by the axial movement of the condenser lens 3. Is done.
One end (lower end) of the main body 1 is a nozzle portion 1a that is tapered and has an irradiation hole 1a1 at the tip, and an optical fiber connecting portion 1b is provided at the other end (upper end).

The processing head 51 is mounted on a laser processing machine 61 which is a fiber laser processing machine as shown in FIG.
FIG. 2 is a schematic perspective view showing the overall configuration of the laser beam machine 61.

The laser processing machine 61 irradiates the workpiece W, which is a workpiece, with laser light, and performs processing such as cutting and drilling on the workpiece W.
The laser processing machine 61 includes a fiber laser oscillator 62 that is a laser light source, a processing main body 63 including the processing head 51 described above that irradiates the workpiece W with laser light output from the fiber laser oscillator 62, and a laser processing machine. And an NC device 64 that is a control unit that controls the overall operation of the apparatus 61.

  The fiber laser oscillator 62 and the optical fiber connection portion 1 b of the processing head 51 are connected by the optical fiber 4, and the laser beam output from the fiber laser oscillator 62 is supplied to the processing head 51.

The processing body 63 includes a table 63a on which the workpiece W is placed, and an X-axis carriage 63b that is provided on the table 63a and moves in the X-axis direction (left-right direction).
The X-axis carriage 63b is provided with a Y-axis carriage 63c that moves in the Y-axis direction (vertical direction) orthogonal to the X-axis direction.
The Y-axis carriage 63c is provided with a Z-axis holder 63d. The Z-axis holder 63d supports the machining head 51 so as to be movable in the Z-axis direction (vertical direction).

  The configuration is not limited to the above as long as the workpiece W and the machining head 51 are relatively movable in the X-axis and Y-axis directions. For example, the machining head 51 may be moved in the Y-axis and Z-axis directions with the X-axis carriage 63b fixed, and the workpiece W may be moved in the X-axis direction by a clamper (not shown).

  The processing head 51 performs predetermined optical processing such as focus adjustment on the laser light supplied from the fiber laser oscillator 62 via the optical fiber 4 by the head optical system P1 described above. The laser beam L is irradiated from the irradiation hole 1a1 of the nozzle portion 1a toward the workpiece W.

  Therefore, the machining head 51 can move at least two-dimensionally along the workpiece W in a range facing the workpiece W by the cooperative operation of the X-axis carriage 63b and the Y-axis carriage 63c. Further, it is possible to perform processing by irradiating the desired processing portion Wp of the workpiece W with the laser beam L at a predetermined focal position.

In FIG. 1, the light beam Lt of the laser light L inside the main body 1 of the machining head 51 is indicated by a one-dot chain line, and the axis of the light beam Lt is indicated by a solid line.
As shown in FIG. 1, the laser light L diffused and emitted from the exit of the optical fiber 4 into the main body 1 is converted into a parallel light beam by the collimator lens 2.
This parallel light beam enters the condenser lens 3 and is emitted toward the workpiece W from the irradiation hole 1a1 at the tip of the nozzle portion 1a so as to be focused on the surface Ws of the workpiece W, for example.

  As described above, the in-focus position is adjusted by moving the condenser lens 3 in the direction of the optical axis CLa by a focus adjusting mechanism (not shown). This focus adjustment is controlled by the NC device 64.

The laser processing machine 61 includes a detection unit SR that detects the amount of the reflected light Lf that is returned from the laser beam L emitted from the nozzle unit 1a after being reflected by the processing portion of the workpiece W.
The detection unit SR includes a light receiving unit 6 in which a part of the reflected light Lf is received as reflected light Lf3 (see FIG. 4), a detector 7 that measures the amount of incident reflected light Lf3, and the light receiving unit 6 and the detector. 7 and an optical fiber 8 that guides the reflected light Lf incident on the light receiving unit 6 to the detector 7.
The detector 7 further outputs an electrical signal corresponding to the detected light amount to the NC device 64 as a detection signal SG1.

FIG. 3 is a longitudinal sectional view for explaining the light receiving unit 6.
The light receiving unit 6 includes an aperture 6a having an aperture hole 6a1 having a predetermined diameter, a filter member 6b having a predetermined optical characteristic, and a housing 6c that holds the aperture 6a and the filter member 6b side by side.
With this configuration, the light La that has entered the filter member 6b through the aperture hole 6a1 is output as light Lb in a specific wavelength range (a third range fw3 described later) according to the optical characteristics of the filter member 6b.

  The filter member 6b includes a base material 6b1 that transmits light without wavelength dependency, an incident side optical film 6b2 as a filter coated on the surface of the base material 6b1 on the aperture 6a side, and a surface opposite to the aperture 6a. And an output side optical film 6b3 as a coated filter.

The incident-side optical film 6b2 includes a wavelength band in the first range fw1 centered on the first wavelength λ1 and a wavelength band in the second range fw2 centered on the second wavelength λ2 shorter than the first wavelength λ1. It has the characteristic of reducing or cutting the light. Here, the term “reduction” includes a case where the light is completely removed. For example, the reduction includes a light amount in a wavelength range to be reduced to the same extent as a light amount outside the wavelength range. Hereinafter, the meaning of cut includes this reduction.
The first wavelength λ1 is set corresponding to the wavelength of laser light used for laser processing, and the second wavelength λ2 is set corresponding to the wavelength of alignment adjustment light (red).
For example,
The first wavelength λ1 = 1070 nm, and the first range fw1 is approximately ± 70 nm.
The second wavelength λ2 = 630 nm and the second range fw2 is approximately ± 100 nm.
And
In the following description, the first and second wavelengths λ1 and λ2 are assumed to be 1070 nm and 630 nm, respectively.

The emission-side optical film 6b3 has a band-pass filter characteristic that allows light having a wavelength in the third range fw3 centering on the third wavelength λ3 to pass.
For example,
The third wavelength λ3 = 675 nm and the third range fw3 is approximately ± 125 nm.
And That is, the emission side optical film 6b3 allows only light having a wavelength of 550 nm to 800 nm to pass therethrough. The setting of the third range will be described later.

The light receiving portion 6 described in detail above is attached to the upper end portion of the main body portion 1 of the processing head 51 so that the aperture 6a faces downward as shown in FIG.
The aperture hole 6a1 of the aperture 6a is opened inside the main body 1 at a position where it does not reach the light beam Lt of the laser light L.
The detector 7 is arranged at a position away from the processing head 51 or mounted on the processing head 51.

Next, the reflected light Lf will be described in detail.
When the processing head 51 shown in FIG. 1 is used and, for example, cutting (including drilling) is performed by irradiating a plate-like workpiece with the laser beam L, the reflected light Lf is compared. Low level.
On the other hand, when a defect occurs in the cutting process, a large amount of reflected light Lf is generated as described above. This will be described next with reference to FIG. FIG. 4 is a diagram corresponding to FIG. 1 and includes a description of the path of the reflected light Lf and the like.

The reflected light Lf includes the first wavelength λ1 (1070 nm) irradiated to the workpiece W and light in the visible light wavelength (400 to 800 nm) band generated by the Raman effect.
Part of the reflected light Lf passes through the irradiation hole 1a1 at the tip of the nozzle portion 1a and proceeds to the inside of the main body 1 (referred to as reflected light Lf1).
The light that has traveled into the light beam Lt as a part of the reflected light Lf1 travels so as to return inside the light beam Lt without exiting the light beam. Then, the light passes through the condenser lens 3 and the collimating lens 2 and enters the optical fiber 4 toward the fiber laser oscillator 62, and is detected as return light, for example.

On the other hand, since the scattered light with poor cutting has a wide scattering distribution, a lot of light passes through the irradiation hole 1a1 of the nozzle portion 1a and travels outside the light beam Lt.
The reflected light Lf2, which is reflected light that has traveled to the outside of the light beam Lt, is reflected by the inner surface 1c of the main body 1 and passes through the condenser lens 3 and the collimating lens 2 while partially passing through the light beam Lt obliquely. And reaches the upper part of the main body 1.
A part of the reflected light Lf2 reaching the upper part of the main body 1 reaches the aperture hole 6a1 of the light receiving unit 6 as reflected light Lf3 and enters the light receiving unit 6 (corresponding to the light La in FIG. 3). .

As described above, the amount of light of the reflected light Lf3 that has entered the light receiving unit 6 is reduced to a predetermined value by the aperture hole 6a1, and the wavelength band of the first range fw1 and the second range fw2 is reduced by the filter member 6b. After being cut, only light having a wavelength in the third range fw3 is allowed to pass.
The action of this filtering will be further described with reference to FIGS.

FIG. 5 is a graph showing the wavelength characteristics of the reflected light Lf when laser processing is satisfactory.
FIG. 6 is a graph showing the wavelength characteristics of the reflected light Lf when the laser processing is defective.
FIG. 7 is a graph showing the wavelength characteristics of the reflected reflected light Lf4 (corresponding to the light Lb in FIG. 3) that has passed through the filter member 6b of the light receiving unit 6 when the laser processing is defective.

As shown in FIG. 5, the reflected light Lf in the case where laser processing is satisfactory is light having only a wavelength corresponding to the wavelength (first wavelength λ1) used for laser processing.
As shown in FIG. 6, when a defect occurs in laser processing, the amount of light at the first wavelength λ1 increases, and reflected light that is strong in the visible light region of 400 to 550 nm is detected. That is, strong reflected light bands Pk1 and Pk2 are generated in two wavelength bands.

On the other hand, in the reflected reflected light Lf4 that has passed through the filter member 6b shown in FIG. 7, the excessive light quantity larger than the light quantity in the 600 to 900 nm band in the reflected light bands Pk1 and Pk2, for example, is cut (reduced). From there, a wavelength band of 550 to 800 nm is extracted as a stable wavelength band ARa between the reflected light bands Pk1 and Pk2 with increased light quantity and flat characteristics as compared with the case where processing is good.
For example, when the characteristic of the incident side optical film 6b2 is a characteristic that completely blocks rather than a reduction in the amount of light, light in the 530 to 730 nm band is blocked, and the passing reflected light Lf4 shown in FIG. It is obtained as light having a light amount only in the 800 nm band.

As shown in FIG. 4, the detector 7 amplifies a signal obtained by photoelectrically converting the passing reflected light Lf4, and sends it to the NC device 64 as a detection signal SG1.
The NC device 64 performs A / D conversion on the incoming detection signal SG1 and compares it with a preset pass / fail judgment threshold, and based on the result, whether or not the passing reflected light Lf4 is a reflected light in a defective state. Determine whether.

The reflected light bands Pk1 and Pk2 of the two wavelength bands shown in FIG. 6 appear with the deterioration of the machining state, but the amount of the light varies depending on the output of the laser beam L to be irradiated, the material of the workpiece, the machining mode, etc. It has been empirically understood that it is easy to change according to the item and difficult to grasp quantitatively.
On the other hand, although the stable wavelength band ARa is flat and does not have a peak, the amount of light surely increases with processing defects, and the increase is not affected by various parameters and is suitable for quantitative grasping. It has become clear.

In the filter member 6b of the embodiment, the incident side optical film 6b2 cuts off the reflected light bands Pk1 and Pk2 of two wavelength bands with a large amount of light and eliminates the influence thereof, and then the emission side optical film 6b3 which is a bandpass filter. The stable wavelength band ARa obtained by the above is extracted.
As a result, it is possible to determine whether the detected light quantity is unstable or not with high accuracy.
Moreover, two types of filtering are possible with one optical member (filter member 6b), and the light receiving unit 6 is compact and low-cost.

As described above in detail, the laser processing head 51 of the embodiment receives the reflected light from the processing part of the workpiece W during laser processing not on the light beam Lt of the laser beam L to be irradiated but on the outside of the light beam Lt. It has become.
That is, the diffuse component diffusely reflected is detected instead of the regular reflection component in the reflected light.
Since most of the diffused component of the reflected light is caused by processing defects, the laser processing head 51 accurately extracts reflected light that depends on processing defects, and is used for high-precision monitoring of processing, and laser processing. The laser processing machine 61 provided with the head 51 can monitor the quality of laser processing with higher accuracy.

  The embodiment of the present invention is not limited to the above-described configuration and procedure, and may be modified without departing from the gist of the present invention.

The light receiving unit 6 is not limited to one, and a plurality of light receiving units 6 may be provided.
In the case of providing a plurality, it is desirable to dispose them in the circumferential direction around the optical axis CLa from the viewpoint of detection efficiency of the reflected light Lf3.
The light receiving unit 6 may be provided on the inner peripheral surface of the main body unit 1.
However, since the distribution of the reflected light Lf2 is closer to the upper optical axis in the main body 1 and closer to CLa, the aperture hole 6a1 of the light receiving unit 6 is located as close as possible to the light flux Lt on the upper part. preferable. In other words, it is preferably installed in the vicinity of the optical fiber connecting portion 1b.
The first to third wavelengths λ1 to λ3 and the first to third ranges fw1 to fw3 are not limited to the above values, and may be set as appropriate.

DESCRIPTION OF SYMBOLS 1 Main-body part 1a Nozzle part, 1a1 Irradiation hole, 1b Optical fiber connection part 1c Inner surface 2 Collimating lens 3 Condensing lens, 3a Holder 4 Optical fiber 6 Light receiving part 6a Aperture, 6a1 Aperture hole, 6b Filter member 6b1 Base material, 6b2 Incident Side optical film, 6b3 emission side optical film 6c housing 7 detector 8 optical fiber 51 laser processing head (processing head)
61 Laser Processing Machine 62 Fiber Laser Oscillator 63 Processing Body 63a Table, 63b X-axis Carriage 63c Y-axis Carriage, 63d Z-axis Holder 64 NC Device (Control Unit)
ARa Stable wavelength band CLa Optical axis fw1 First range, fw2 Second range, fw3 Third range L Laser light La, Lb light, Lf, Lf1, Lf2, Lf3 Reflected light Lf4 Passed reflected light, Lt Light flux Pk1, Pk2 Reflected light band P1 Head optical system SG1 Detection signal SR Detection unit W Work Wp Processing site, Ws Surface λ1 First wavelength, λ2 Second wavelength

Claims (4)

A tubular body,
A connecting portion that is provided on one end side of the main body portion and connects an optical fiber for guiding laser light from a laser oscillator to the main body portion;
A nozzle part that is provided on the other end side of the main body part and emits the laser light guided by the optical fiber connected to the connection part;
A light receiving portion that is provided in the vicinity of the connection portion so as to be opened inside the main body portion, and that receives light that has entered the main body portion from the outside through the nozzle portion;
With
The light receiving unit is
A laser processing head comprising a filter having a characteristic of reducing or cutting a first wavelength band including the wavelength of the laser light, and emitting the received light toward a detector that measures the amount of light after passing through the filter. The filter is
On the one surface side, the first optical film having a first characteristic that reduces or cuts light in the first wavelength band and a second wavelength band shorter than the first wavelength band,
A second optical film having a second characteristic that transmits a third wavelength band between the first wavelength band and the second wavelength band on the other surface side;
2. The laser processing head according to claim 1, wherein the light receiving unit passes the received light in the order of the first optical film and the second optical film and emits the light toward the detector. A laser oscillator, a laser processing head, and an optical fiber that is connected between the laser oscillator and the laser processing head and guides the laser light output from the laser oscillator to the laser processing head,
The laser processing head is
A tubular body,
A connecting portion that is provided on one end side of the main body and connects the optical fiber;
A nozzle part that is provided on the other end side of the main body part and emits the laser light guided by the optical fiber;
A light receiving portion that is provided in the vicinity of the connection portion so as to be opened inside the main body portion, and that receives light that has entered the main body portion from the outside through the nozzle portion;
A detector for measuring the amount of the light that has passed through the light receiving unit;
With
The light receiving unit is
A laser processing machine comprising a filter having a characteristic of reducing or cutting a first wavelength band including the wavelength of the laser light, and passing the received light through the filter and then emitting the light toward the detector. The filter is
On the one surface side, the first optical film having a first characteristic that reduces or cuts light in the first wavelength band and a second wavelength band shorter than the first wavelength band,
A filter having a second optical film having a second characteristic that transmits a third wavelength band between the first wavelength band and the second wavelength band on the other surface side;
The laser beam machine according to claim 3, wherein the light receiving unit passes the incident light in the order of the first optical film and the second optical film and emits the light toward the detector.

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