Patent Application
20210023652
The present invention relates to a method for centering a laser light and to a laser processing machine capable of carrying out the centering method.
In a case where the center of a nozzle hole of a laser processing head doesn't coincide with a beam axis of a laser beam in a laser processing machine, a processing failure may occur in laser processing. Therefore, the center of the nozzle hole and the beam axis of the laser beam are made coincident with each other (see Patent Documents 1 to 3 listed below). To make the center of the nozzle hole and the beam axis of the laser beam coincident with each other is called as centering.
Patent Document 1: Japanese Patent Application Publication No. H6-328281
Patent Document 2: Japanese Patent Application Publication No. H7-144289
Patent Document 3: Japanese Patent Application Publication No. 2003-215419
Since centering is done based on an operator's visual confirmation in a prior-art centering method, the operator's technical proficiency is required. In addition, it is required to carry out a test several times for checking whether or not the center of the nozzle hole and the beam axis of the laser beam coincide with each other by irradiating a laser beam. Therefore, the centering operation takes much time.
In addition, there may be a case where a light receiving sensor for detecting an irradiation position of a laser beam is used in order to irradiate the laser beam onto a predetermined position. The irradiation position of the laser beam is controlled by controlling a galvano mirror drive device based on an output of the light receiving sensor (see Japanese Patent Application Publication No. 2000-98271). In this case, it is possible to irradiate the laser beam automatically onto the predetermined irradiation position.
The irradiation position of the laser beam is a reference position on the light receiving sensor. Therefore, it becomes possible to laser-process a processed object precisely by laser-processing the processed object while making the reference position of the light receiving sensor and a processed position of the processed object coincident with each other. The laser processing machine provided with the above-mentioned light receiving sensor cuts a sheet material (the processed object) by the laser beam while also using assist gas. However, in the laser processing machine, it is impossible to detect whether or not the center of the nozzle hole and the beam axis of the laser beam coincide with each other. Therefore, it is hard to irradiate the laser beam in a state where the center of the nozzle hole and the beam axis of the laser beam coincide with each other.
An object of the present invention is to provide a method for centering a laser beam that can carry out centering of the laser beam automatically, and a laser processing machine capable of carrying out the centering method.
A first aspect of the present invention provides a method for centering a laser beam with respect to a nozzle hole of a laser processing machine in which a beam path adjusting mechanism for giving an angle to a beam axis is installed within a laser processing head, the method comprising: (a) image-capturing a shape of a distal end face of a nozzle of the laser processing head of the laser processing machine; (b) calculating a position of a center of the nozzle hole based on the image-captured shape of the distal end face of the nozzle; (c) irradiating a small power laser beam or a test beam from the nozzle hole; (d) capturing an image of the laser beam or the test beam that is irradiated formed in a vicinity of the distal end face of the nozzle; (e) calculating a position of the laser beam or the test beam that is captured; (f) calculating a positional error between the center of the nozzle hole and the laser beam or the test beam that are calculated; and (g) making the center of the nozzle hole coincident with the laser beam or the test beam in the vicinity of the distal end face by controlling, based on the positional error, the beam path adjusting mechanism that is provide within the laser processing head and adjusts an incident angle of the laser beam or the test beam onto a collimator lens provided in the laser processing head.
A second aspect of the present invention provides a laser processing machine comprising: a laser processing head within which a beam path adjusting mechanism that gives an angle to a beam axis is installed; and an image capture unit that captures an image of a distal end face of a nozzle provided in the laser processing head; wherein the laser processing head is movable in an X axis direction, in a Y axis direction and in a Z axis direction, and a condenser lens is installed therewithin, wherein the image capture unit includes an image capture device that captures an image of a shape of a distal end face of the nozzle, wherein the laser processing machine further comprises within the laser processing head: an arithmetic device that calculates a position of a center of a nozzle hole based on the shape of the distal end face of the nozzle captured by the image capture device; an optical element that forms, when the image of the shape of the distal end face of the nozzle is captured in a state where a small power laser beam or a test beam is irradiated, an image of the laser beam or the test beam in a vicinity of the distal end face of the nozzle; a test beam position arithmetic device that calculates a position of the laser beam or the test beam that is captured; an error arithmetic device that calculates a positional error between the center of the nozzle hole and the laser beam or the test beam that are calculated; and a beam path adjusting mechanism that is capable of adjusting an incident angle of the laser beam or the test beam onto a condenser lens provided in the laser processing head, and wherein the laser processing machine comprises a beam path controller that controls operations of the beam path adjusting mechanism so as to make the center of the nozzle hole and the laser beam or the test beam coincident with each other based on the positional error between the center of the nozzle hole and the laser beam or the test beam.
A third aspect of the present invention provides a laser processing machine comprising: a laser processing head within which a beam path adjusting mechanism that gives an angle to a beam axis is installed; and an image capture unit that captures an image of a distal end face of a nozzle provided in the laser processing head, wherein the laser processing head is movable in an X axis direction, in a Y axis direction and in a Z axis direction, and a condenser lens is installed therewithin, wherein the image capture unit includes an image capture device that captures an image of a shape of the distal end face of the nozzle, and wherein the laser processing machine further comprises: an arithmetic device that calculates a position of a center of a nozzle hole based on the shape of the distal end face of the nozzle captured by the image capture device; an optical element that forms, when the image of the shape of the distal end face of the nozzle is captured in a state where a small power laser beam or a test beam is irradiated, an image of the laser beam or the test beam in a vicinity of the distal end face of the nozzle; a test beam position arithmetic device that calculates a position of the laser beam or the test beam that is captured; an error arithmetic device that calculates a positional error between the center of the nozzle hole and the laser beam or the test beam that are calculated; an adjustment drive mechanism that adjusts an incident angle of the laser beam or the test beam onto a condenser lens; and a control device that controls the adjustment drive mechanism when processing a processed material so as to cancel the positional error between the center of the nozzle hole and the laser beam or the test beam on an imaging plane in the vicinity of the distal end face of the nozzle.
A fourth aspect of the present invention provides a method for centering a laser beam with respect to a nozzle hole of a laser processing machine, the method comprising: (a) image-capturing a shape of a distal end face of a nozzle of a laser processing head of the laser processing machine, and calculating a position of a center of a nozzle hole based on the shape of the distal end face; (b) irradiating a small power laser beam or a test beam from the nozzle hole, and calculating a position of the laser beam or the test beam; (c) calculating a positional error between the center of the nozzle hole and the laser beam or the test beam that are calculated; and (d) making the center of the nozzle hole and the laser beam or the test beam coincident with each other, when processing a processed material, by controlling an adjustment drive mechanism provided within the laser processing head and capable of adjusting an incident angle of the laser beam or the test beam onto a collimator lens provided in the laser processing head so as to cancel the positional error between the center of the nozzle hole and the laser beam or the test beam on an imaging plane in the vicinity of the distal end face of the nozzle.
As shown in
The laser processing machine 1 includes a laser processing head 5 movable in XYZ axis directions. But it is enough that a processed material and the laser processing head 5 are relatively movable to each other in their motions in the X axis direction and in the Y axis direction. For example, the processed material may be movable in the X axis direction and in the Y axis direction, and the laser processing head 5 may be movable only in the Z axis direction. The laser processing head 5 includes a connector 9 that is connected with an emitting end of a process fiber 7 connected with the laser oscillator 3. A collimator lens 11 is disposed so as to be opposite to the connector 9. The collimator lens 11 has a function for collimating a laser beam LB emitted from the emitting end of the process fiber 7 as parallel rays.
A condenser lens 13 for condensing the laser beam LB and then irradiating it onto the processed material (not shown in the drawings) is provided in the laser processing head 5. A bend mirror 15 for bending the laser beam transmitting though the collimator lens 11 toward the condenser lens 13 is provided between the condenser lens 13 and the collimator lens 11. In addition, a laser light path adjusting mechanism (a beam path adjusting mechanism) 17 capable of adjusting (changing) an incident angle of the laser beam LB onto the condenser lens 13 is provided between the bend mirror 15 and the collimator lens 11. The laser beam path adjusting mechanism 17 is disposed within the laser processing head 5.
In the present embodiment, the laser beam path adjusting mechanism 17 is configured of a galvano scanner. The galvano scanner 17 is configured to be capable of scanning the laser beam LB on an XY two-dimensional plane. Therefore, the galvano scanner 17 includes an X axis scanning mirror 19 for scanning the laser beam LB transmitting though the collimator lens 11 in the X axis direction, and an X axis motor (galvano motor) 21 for rotating the X axis scanning mirror 19. Further, the galvano scanner 17 includes a Y axis scanning mirror 23 for scanning the laser beam LB reflected by the X axis scanning mirror 19 in the Y axis direction, and a Y axis motor (galvano motor) 25 for rotating the Y axis scanning mirror 23.
By controlling the X axis motor 21 and the Y axis motor 25, the laser beam LB transmitting though the collimator lens 11 is made incident into the bend mirror 15 while being scanned in the X axis direction and in the Y axis direction. Therefore, an incident path of the laser beam LB to be made incident into the condenser lens 13 can be adjusted in the X axis direction and in the Y axis direction. Namely, an irradiation position of the laser beam LB with respect to the center of a nozzle hole 27H of a nozzle 27 disposed at a distal end of the laser processing head 5, i.e. a beam axis can be adjusted.
The laser beam LB transmitting though the condenser lens 13 is image-formed on a flat plane almost identical to a distal end face 27F of the nozzle 27 (an imaging plane). Therefore, the condenser lens 13 configures an optical element for image-forming the laser beam LB in the vicinity of the distal end face of the nozzle 27.
The angle of the beam axis of the laser beam LB made incident on the bend mirror 15 is changed when the galvano scanner 17 located in advance of the bend mirror 15 is operated, and thereby the beam axis deviates from the center of the bend mirror 15. However, in
Explanations will be made for a case where the beam axis of the laser beam LB is displaced from the thin solid line L1 to a thick solid line L2 by the galvano scanner 17. The laser beam LB reflected by the bend mirror 15 inclines by an angle θ (with respect to the reference state), and thereby the irradiation position of the laser beam LB on the processed material W displaces by a distance Δs. An EFL in
If the galvano scanner 17 inclines the laser beam LB by the angle θ in an opposite direction to the direction shown in
As shown in
In order to check whether or not the center of the nozzle hole 27H of the nozzle 27 and the beam axis of the laser beam LB coincide with each other, a box-shaped image capture unit 29 for capturing an image of the distal end face 27F of the nozzle 27 is provided in the laser processing machine 1. The image capture unit 29 is disposed at a predetermined position in the laser processing machine 1. A protection glass 31 and an optical element 33 is provided at a position associating with an image capture reference position of the image capture unit 29. A luminescent spot of a visible light is formed at an irradiation position of the laser beam LB on the optical element 33. For example, glass containing nano-sized crystals Yaglass-T (registered trademark) of Sumita Optical Glass, Inc. can be used as the optical element 33.
In order to capture an image of the luminescent spot on the optical element 33, the image capture unit 29 includes a camera 35 such as a CCD camera that is installed horizontally and serves as an image capture device. A bend mirror 36 for bending a ray of light from the luminescent spot toward the camera 35 is provided beneath the optical element 33.
According to the above-explained configuration, when the laser processing head 5 is aligned at the reference position above the optical element 33 of the image capture unit 29, the distal end face 27F of the nozzle 27 can be captured by the camera 35. In addition, when a small power laser beam LB or a guide beam is irradiated from the laser processing head 5 (used as a test beam), the luminescent spot is formed on the optical element 33. Then, the camera 35 can also capture this luminescent spot concurrently. Namely, it is required that the distal end face 27F and the optical element for converting the test beam to a visible light that are captured by the camera 35 are positioned within a depth of field of the camera 35. In other words, the optical element 33 is positioned in the vicinity of the distal end face 27F.
Like as a nozzle changer for example, the camera 35 (the image capture unit 29) is evacuated to an area in which a processed material is never laid, and, as needed, is moved to a position beneath the laser processing head 5 and then set at the image capture reference position.
The camera 35 is connected with a control device 37 (see
The arithmetic device 41 has functions for calculating a shape of the distal end face 27F and calculating a position of the center of the nozzle hole 27H based on image data of the distal end face 27F captured by the camera 35 and then image-processed by the image processing device 39. Then positional data (a XY coordinate) of the calculated position of the center is recorded (stored) in a center position data memory 43.
In addition, the control device 37 sets the laser processing head 5 at a position associated with the image capture reference position of the image capture unit 29. And, the arithmetic device 41 has a function for calculating a position of the luminescent spot formed on the optical element 33 based on image data captured when irradiating the test beam on the optical element 33. Namely, the arithmetic device 41 functions as a test beam position arithmetic device that calculates the position of the luminescent spot of the test beam on the optical element 33. The calculated positional data (XY coordinate) of the luminescent spot is recorded (stored) in a luminescent spot position data memory 45.
The control device 37 also includes an error arithmetic device (unit) (comparator) 47 for calculating whether or not the center of the nozzle hole 27H and the luminescent spot coincide with each other. The control device 37 further includes a light path controller 49 for controlling operations of the X axis motor 21 and the Y axis motor 25 based on the calculation result of the error arithmetic device 47.
The beam path controller 49 controls the incident angle of the laser beam LB made incident onto the condenser lens 13 by controlling the X axis motor 21 and the Y axis motor 25 so as to make the center of the nozzle hole 27H and the luminescent spot coincident with each other (i.e. to cancel a positional error between the center of the nozzle hole 27H and the luminescent spot). For example, when the nozzle 27 has been exchanged, the center of the nozzle hole 27H of the exchanged nozzle 27 and the luminescent spot formed due to the irradiation of the test beam can be made coincident with each other easily and precisely according to the control device 37. Note that it becomes possible to process the processed material with no error by reflecting the error data of the error arithmetic device 47 to a processing command of the processed material.
In a case of visibly confirming a displacement error between the nozzle center and the test beam, the captured shape of the distal end face 27F is displayed on the display device 40 and the calculated position of the center of the nozzle hole 27H is indicated by a sign such as “x” on the display device 40. Then, the position of the luminescent spot of the test beam and the “x” sign can be made coincident with each other on the display screen of the display device 40 by controlling the X axis motor 21 and the Y axis motor 25 by use of an input device (operation device) such as a joystick. Here, it is preferable that the displayed image on the display device 40 can be magnified.
The method for centering the laser beam will be explained with reference to a flowchart shown in
The error arithmetic device 47 of the control device 37 calculates a positional error between the center of the nozzle hole 27H and the test beam (the luminescent spot) from the position of the center of the nozzle hole 27H calculated in the step S2 (or the position of the center stored in the center position data memory 43) and the position of the test beam (the luminescent spot) calculated in the step S5 (or the position stored in the luminescent spot position data memory 45) (step S6). Here, the position of the center of the nozzle hole 27H and the position of the test beam (the luminescent spot) may be displayed on the display device 40 as explained above. Note that, in the control shown in
In the above first embodiment, the galvano scanner is provided between the collimator lens 11 and the bend mirror 15 as the laser beam path adjusting mechanism 17. However, in a second embodiment shown in
The galvano scanner as the laser beam path adjusting mechanism 17 is provided between the collimator lens 11 and the condenser lens 13 within the laser processing head 5. The positions of the collimator lens 11 and the condenser lens 13 are predetermined fixed positions, and the galvano scanner is controlled so as to scan the laser light with parallel rays collimated by the collimator lens 11 in the X axis direction and in the Y axis direction. Namely, the beam path is adjusted within a segment of a short beam path length between the collimator lens 11 and the condenser lens 13. Therefore, in comparison with a case with a long beam path length, the incident angle (incident position) of the laser beam LB onto the condenser lens 13 can be adjusted more precisely.
In the above first and second embodiments, the galvano scanner is adopted as the laser beam path adjusting mechanism. However, as a configuration for making the center of the nozzle hole 27H and the beam axis of the laser beam LB coincident with each other, an adjustment drive mechanism that displaces at least one of the condenser lens 13 and the nozzle 27 in the radial direction can be adopted.
In a third embodiment shown in
According to the above configuration, the positions of the condenser lens 13 and the nozzle 27 can be adjusted in the radial direction independently from each other by adjusting the rotations of the motors M. Therefore, the beam axis of the laser beam LB and the center of the nozzle hole 27H can be automatically made coincident with each other. Note that a control almost equivalent to the control of the flowchart shown in
In the first to third embodiments, the image of the distal end face 27F is captured by the camera 35. Therefore, the state of the distal end face 27F can be confirmed visually by displaying the captured image on the display device 40. Thus, damages of the nozzle 27 and adhesions, such as spatters, on the nozzle 27 can be confirmed.
In addition, in the first to third embodiments, the beam axis can be adjusted automatically such that the center of the nozzle hole 27H and the irradiation position of the laser beam LB are made coincident with each other. Therefore, the center of the nozzle hole 27H and the irradiation position (the beam axis) of the laser beam LB can be made coincident with each other easily and quickly. Namely, the centering operation is easy. In other words, the center of the nozzle hole 27H and the laser beam can be made coincident with each other easily, and the operation for making them coincident can be automated.
The entire contents of a Japanese Patent Application No. 2018-44102 (filed on Mar. 12, 2018) are incorporated herein by reference. Although the invention has been described above by reference to a certain embodiment of the invention, the invention is not limited to the embodiment described above. Scope of the present invention is determined in the context of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-044102 | Mar 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/009402 | 3/8/2019 | WO | 00 |
