JP3746555B2 - Laser processing apparatus and laser processing method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser processing apparatus using an optical fiber, and more particularly to a laser processing apparatus and a laser processing method capable of performing laser processing while observing a processing state even on a part that cannot be directly visually observed, such as in a pipe. .
[0002]
[Prior art]
Conventionally, laser light has been used as a non-contact tool for processing various materials. As a result of the development of laser processing equipment using optical fibers as an optical system for transmitting laser light energy to the workpiece, the applicable range of laser processing has further expanded, and lasers in relatively small diameter pipes can be used. Processing is also possible.
For example, when welding or cutting is performed by a laser processing apparatus using an optical fiber, the processing laser light oscillated from the laser is guided by the optical fiber, and the laser is applied to the workpiece using a condensing optical system. Various laser processing can be performed by condensing the light.
[0003]
[Problems to be solved by the invention]
By the way, grasping of a processing position, confirmation of a processing state after processing, inspection, and the like are usually performed visually.
However, when it is impossible to visually check the processing position, for example, when the processing position is in a pipe, a device for observing the processing position such as a fiber scope is required in addition to the laser processing device. And by inserting the laser processing device and the fiberscope into the pipe at the same time, it is possible to accurately grasp the processing position, that is, the position to irradiate the laser beam, or to process while observing the processing state. If the inner diameter is small, the laser processing apparatus and the fiberscope cannot be inserted at the same time.
[0004]
If the laser processing device and the fiberscope cannot be inserted into the pipe or the like at the same time, it is impossible to perform processing while observing the processing state, and it is difficult to accurately grasp the processing position. Furthermore, in the post-processing inspection, it is difficult to confirm the processing position because the fiber scope must be inserted after the laser processing device is taken out from the pipe after the processing is completed. There was an inconvenience that became very bad.
[0005]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a laser processing apparatus and a laser processing method capable of observing a processing position simultaneously with laser processing even when the processing position is in an invisible part such as a pipe. And
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a laser processing apparatus according to claim 1 of the present invention is a composite type in which a large number of image transmission fibers are converged and integrated around a large diameter fiber for processing laser light transmission. From an optical fiber, an incident part that makes processing laser light incident on the composite optical fiber, an output part that emits processing laser light transmitted by the composite optical fiber toward the work piece, and a work piece Focusing by finely adjusting the distance between the emitting part and the work piece based on the image information obtained by the observation part that observes the visible light and the observation part that branches the visible light that emits light at the incident part Ri Na includes a focus adjustment unit that performs an operation, the image transmission fiber is not without a number of islands of the core, a sea-island structure consisting of a continuous sea shape formed by cladding around Rukoto It is characterized by.
Preferably, the cores of the large diameter fiber and the image transmission fiber are made of pure silica.
[0007]
In the laser processing method of the present invention, a visible guide light having a mask pattern is made incident on the composite optical fiber according to claim 1, and a focusing operation is performed by the focus adjustment unit in a state in which the workpiece is irradiated with the visible guide light. Then, a processing laser beam is incident on the composite optical fiber, and the workpiece is irradiated with the processing laser beam to process the workpiece.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below. FIG. 1 is a schematic configuration diagram showing an embodiment of a laser processing apparatus of the present invention. Reference numeral 1 in the figure denotes a workpiece.
The laser processing apparatus of the present embodiment includes a composite optical fiber 10, an incident part including a laser light oscillation device (not shown) and an incident lens part 3, an exit lens part (exit part) 5, an observation part 20, a focus adjustment part 30, And a guide light incident portion 40.
In this embodiment, the laser beam oscillator outputs a high-energy laser beam (processing laser beam) that can perform processing such as cutting and welding on the workpiece 1, and a YAG laser is preferable. Used.
[0009]
FIG. 2 is a cross-sectional view showing an example of the composite optical fiber 10. Reference numeral 13 in the figure denotes a large diameter fiber.
The large-diameter fiber in the present invention refers to an optical fiber having a core diameter that can transmit optical power with almost no influence of the cladding.
The large-diameter fiber 13 of this embodiment is composed of a core 11 made of pure silica and a clad 12 made of silica to which fluorine and / or boron is added. Preferably, the core 11 has a diameter of 600 to 800 μm, the cladding 12 has a diameter of about 800 to 1000 μm, and a numerical aperture (NA) of about 0.2.
[0010]
A large number of image transmission fibers 14 are focused around the large-diameter fiber 13. The multiple image transmission fibers 14 are integrated to form a sea-island structure including a large number of island-shaped cores 15 and a sea-shaped clad formed continuously around the cores 15. The core 15 is made of pure silica, the clad is made of silica to which fluorine and / or boron is added, and the diameter of the core 15 (pixel diameter) is preferably about 9 to 10 μm. Further, if the number of image transmission fibers 14 (number of pixels) to be focused is small, the resolution is deteriorated. If the number is large, the composite optical fiber 10 has a large diameter. Therefore, the number is preferably about 3000 to 10,000.
[0011]
The composite optical fiber 10 in this embodiment has a large-diameter fiber 13 rod disposed at the center of a quartz jacket tube 16, and an optical fiber to be an image transmission fiber 14 is formed around the rod to form a preform. It is manufactured by spinning a preform.
The quartz jacket tube 16 is made of pure silica, and the size thereof is appropriately set according to the number of pixels.
A resin coating layer 17 is formed on the circumference of the quartz jacket tube 16. The resin coating layer 17 is preferably formed using a UV resin, and preferably has a thickness of about 100 to 200 μm. The resin coating layer 17 is formed following the spinning of the preform.
The thickness and length of the composite optical fiber 10 having such a configuration can be set as appropriate according to the application and the like. For example, the outer diameter is preferably 1.6 to 1.8 mm and the length is preferably about 6 to 20 m. Can be formed.
[0012]
The incident lens unit 3 is configured so that processing laser light (infrared rays) oscillated from a YAG laser light oscillation device (not shown) is condensed and incident on the end face of one end side 10 a of the composite optical fiber 10. Has been.
Further, the exit lens unit 5 is configured to collect and irradiate the processing laser light emitted from the end surface of the other end side 10 b of the composite optical fiber 10 on the workpiece 1. In addition, the exit lens unit 5 includes a drive mechanism 32 that moves the lens forward and backward in the optical axis direction of the processing laser beam. As a result, the distance between the exit lens portion 5 and the workpiece 1 can be finely adjusted while keeping the distance between the composite optical fiber 10 and the workpiece 1 constant.
[0013]
The observation unit 20 includes a wavelength filter 21, an infrared cut filter 22, an imaging lens 23, an imaging device 24, and a television monitor 25.
The wavelength filter 21 is configured to transmit infrared rays and partially transmit visible light and partially reflect. The wavelength filter 21 is disposed between the laser light oscillation device and the incident lens unit 3 and transmits the processing laser light and the visible guide light described later, and the processing laser light on the same optical axis as the processing laser light. The visible light transmitted in the opposite direction is reflected and branched to an optical path different from the optical path of the processing laser light. The wavelength filter 21 can be configured using, for example, a dielectric multilayer filter.
[0014]
The infrared cut filter 22 is configured to transmit visible light branched by the wavelength filter 21 and cut infrared light, and can be configured using a dielectric multilayer filter suitably.
The imaging lens 23 is configured to focus the visible light that has passed through the infrared cut filter 22 on the light receiving surface of the imaging device 24 to form an image.
The imaging device 24 outputs the luminance distribution of the light pattern imaged on the light receiving surface as an electrical signal (image signal), and for example, a CCD camera is preferably used. The image information captured by the imaging device 24 in this way is sent to the television monitor 25 and displayed as an image.
[0015]
The focus adjustment unit 30 includes an image processing device 31 and a drive mechanism 32 provided in the exit lens unit 5.
The image processing device 31 receives the image information captured by the image capturing device 24 from the image capturing device 24 or the television monitor 25, measures the brightness distribution of the image, detects the contrast of the brightness distribution, and the contrast. It has means for outputting a signal for driving the drive mechanism 32 so that the maximum value is obtained, and an appropriate configuration can be obtained.
[0016]
The guide light incident part 40 is for making visible guide light having a mask pattern incident on the composite optical fiber 10, and includes a guide light source (not shown), a mask 41, and a mirror 42.
As long as the guide light source used here is light having a wavelength in the visible region and can oscillate light (visible guide light) that does not change the surface state even when irradiated onto the workpiece 1, it is appropriately selected. Can be used.
[0017]
The mask 41 has a portion that transmits visible guide light and a portion that does not transmit visible guide light, and is disposed between the guide light source and the mirror 42. The visible guide light has a mask pattern by passing through the mask 41. For example, when a mask 41 having a cross-shaped portion through which visible guide light is transmitted is used, visible guide light having a cross-shaped mask pattern as shown in FIG. 3 is obtained. The shape of the mask can be set as appropriate.
The mirror 42 is configured to transmit infrared light and reflect visible light. The mirror 42 is arranged between the wavelength filter 21 and the laser light oscillator, and is configured to guide light from a guide light source provided separately from the laser light oscillator on the same optical axis as the laser light. Yes.
[0018]
In the laser processing apparatus configured as described above, after the processing laser light oscillated from the YAG laser light oscillation apparatus passes through the mirror 42 and the wavelength filter 21, the incident lens unit 3 causes the composite optical fiber to pass through. 10 is collected and incident on the end face of one end side 10a. Then, the light is transmitted through the large-diameter fiber 13 of the composite optical fiber 10, emitted from the other end side 10 b of the composite optical fiber 10, and then condensed on the workpiece 1 by the exit lens unit 5. In this way, when the workpiece 1 is irradiated with the high-energy machining laser beam, the workpiece 1 melts or evaporates, so that the workpiece 1 can be processed as desired. At the same time, the workpiece 1 is heated to emit visible light.
[0019]
This visible light is condensed on the end face of the other end side 10 b of the composite optical fiber 10 by the exit lens unit 5, transmitted by the image transmission fiber 14 of the composite optical fiber 10, and then the composite optical fiber 10. The light is emitted from one end side 10a. Then, after being made parallel light by the incident lens unit 3, it is reflected by the wavelength filter 21 and branched to an optical path different from the optical path of the laser light. The branched visible light passes through the infrared cut filter 22 and is then imaged on the light receiving surface of the imaging device 24 by the imaging lens 23. The image formed here is an image in the vicinity of the processing position of the workpiece 1 and is captured by the imaging device and displayed on the television monitor 25.
[0020]
Further, the focusing operation can be performed by oscillating the visible guide light from the guide light source without oscillating the processing laser light.
That is, when the visible guide light is oscillated from the guide light source and is incident on the composite optical fiber 10 via the mask 41, the mirror 42, the wavelength filter 21, and the incident lens 3, the visible guide light having the mask pattern is combined with the composite light. It is transmitted by the image transmission fiber 14 of the fiber 10 and irradiated onto the workpiece 1. Then, the reflected light from the workpiece 1 is branched by the wavelength filter 21 in the same manner as the visible light emitted from the workpiece 1, and is imaged and imaged on the light receiving surface of the imaging device 24. The image information captured by the imaging device 24 is sent to the television monitor 25 and displayed as an image, and is also sent to the image processing device 31.
[0021]
When image information is sent, the image processing device 31 measures the luminance distribution of the image and detects the contrast of the luminance distribution.
For example, FIG. 4 shows an example of an image obtained by the television monitor 25 and its luminance distribution when the workpiece 1 is irradiated with visible guide light having the mask pattern shown in FIG. 4A to 4C show images respectively obtained when the exit lens unit 5 is moved. FIG. 4A shows the exit lens unit 5 closer to the workpiece 1 than the focal position. The state, (b) shows the state at the focal position, and (c) shows the state far from the focal position.
[0022]
As shown in FIG. 4, since the contrast of the luminance distribution is maximized in the focused state (b), the image treatment device 31 drives the drive mechanism of the exit lens unit 5 based on the result of detecting the contrast of the luminance distribution. A signal for driving 32 is output, and the exit lens 5 is moved so that the contrast of the luminance distribution is maximized. That is, the distance between the exit lens unit 5 and the workpiece 1 is finely adjusted so that the obtained image is in focus.
The distance between the exit lens portion 2 and the workpiece 1 is finely adjusted in this way only when the visible guide light is incident on the composite optical fiber 10 and the focusing operation is performed. For example, the distance between the exit lens unit 2 and the workpiece 1 is not changed by preventing the image information from being sent to the image processing device 31, for example.
[0023]
Next, an embodiment of a laser processing method using the laser processing apparatus of this embodiment will be described.
First, the exit lens portion 5 of the laser processing apparatus is arranged in the vicinity of the processing position of the workpiece 1, and the laser processing apparatus is set so that the processing laser light is emitted toward the processing position.
Next, a focusing operation is performed by oscillating visible guide light from the guide light source. That is, the visible guide light passes through the mask 41 and has a mask pattern, which is incident on the composite optical fiber 10 via the mirror 42, the wavelength filter 21, and the incident lens unit 3. The visible guide light is transmitted through the image transmission fiber 14 of the composite optical fiber 10 and is irradiated onto the workpiece 1. Since an image near the processing position is obtained by the reflected light from the workpiece 1, the focusing operation is automatically performed in the focus adjustment unit 30 based on this image information.
[0024]
After focusing in this manner, the processing position is confirmed, the oscillation of the visible guide light is stopped, and the processing laser light is oscillated instead and incident on the composite optical fiber 10 via the wavelength filter 21. .
As described above, the processing laser light is transmitted by the large-diameter fiber 13 of the composite optical fiber 10 and is emitted from the exit lens unit 5 toward the workpiece 1, so that the processing laser beam is directed toward the workpiece 1. Desired processing can be performed. At this time, as described above, an image in the vicinity of the processing position obtained by the visible light emitted from the workpiece 1 is displayed on the television monitor 25, so that the processing can be performed while observing the image.
When the surface state of the workpiece 1 reaches a desired processing state, the oscillation of the laser beam is stopped and the processing ends.
After this, if further confirmation of the processing state is required, the visible guide light is incident on the composite optical fiber 10 in the same manner as the above focusing operation to obtain an image of the processing position, and by observing this, The processing state can be confirmed.
[0025]
As described above, according to the laser processing apparatus of the present embodiment, the large-diameter fiber 13 that transmits the processing laser light and the image transmission fiber 14 that transmits the image information of the processing position are integrated into a small-diameter fiber. Therefore, even if the processing position is not visible, such as in the pipe, the processing laser can be used as long as the inner diameter of the pipe or the like is large enough to insert the composite optical fiber 10 and the exit lens portion 5. An image of the processing position can be obtained simultaneously with the light irradiation. Therefore, laser processing can be performed while observing the processing state from this image.
[0026]
Further, the laser processing apparatus of the present embodiment includes a focus adjusting unit 30 that performs a focusing operation based on image information obtained by the observation unit 20, and the focusing operation is automatically performed thereby, so that the operation is simple. In addition, work efficiency can be improved.
In this embodiment, the output lens unit 5 has a drive mechanism 32 that can finely adjust the distance between the output lens unit 5 and the workpiece 1 while keeping the distance between the composite optical fiber 10 and the workpiece 1 constant. It has. Therefore, the focusing operation can be performed without moving the composite optical fiber 10. In this configuration, when the distance from the hand to the workpiece 1 is long, or when the composite optical fiber 10 is inserted into a curved pipe or the like, the composite optical fiber 10 is moved in the length direction. It is particularly suitable when it is difficult to do so.
[0027]
Furthermore, since the guide light incident part 40 for allowing the visible guide light having the mask pattern to enter the composite optical fiber 10 is provided, switching between the focusing operation and the laser processing operation can be easily performed. Further, since the visible guide light has a mask pattern, the automatic focusing operation by the focus adjustment unit 30 is performed accurately.
Further, the laser processing apparatus of this embodiment has excellent radiation resistance because the cores of the large-diameter fiber 13 and the image transmission fiber 14 constituting the composite optical fiber 10 are both made of pure silica. And can be suitably used for laser processing in a radiation atmosphere.
[0028]
According to the laser processing method of the present embodiment, prior to processing with laser light, guide light having a mask pattern is incident on the composite optical fiber 10 so that an image of the processing position is reflected by reflected light from the workpiece. The focus adjustment unit 30 finely adjusts the distance between the exit lens unit 5 and the workpiece 1 based on the change in the contrast ratio of the luminance distribution of the image. In addition, it is possible to reliably obtain an in-focus image. Therefore, laser processing while observing the processing position can be performed easily and efficiently.
Note that the mechanism of the focus adjustment unit 30 is not limited to that of the present embodiment, and any mechanism that automatically performs a focusing operation based on image information obtained by the observation unit 20 can be changed as appropriate. For example, the exit lens unit 5 is fixed to the end surface of the other end side 10b of the composite optical fiber 10, and the end of the other end side 10b of the composite optical fiber 10 is attached to a robot that can be moved in a pipe by remote control. The robot can also be configured to move based on image information obtained by the observation unit 20, and in this case, the entire composite optical fiber 10 can be advanced and retracted to perform a focusing operation.
[0029]
【The invention's effect】
As described above, the laser processing apparatus according to claim 1 of the present invention includes a composite optical fiber in which a large number of image transmission fibers are converged and integrated around a large diameter fiber for processing laser light transmission. , An incident portion for entering the processing laser light into the composite optical fiber, an exit portion for emitting the processing laser light transmitted by the composite optical fiber toward the workpiece, and a visible light emitted from the workpiece A focusing operation is performed by finely adjusting the distance between the emitting part and the work piece based on image information obtained by the observation part that observes the visible light and the observation part that branches the light at the incident part. A focus adjustment unit is provided.
Therefore, even if the machining position is not visible, such as in the pipe, the composite optical fiber and the emission part can be inserted into the pipe, etc., and an image of the machining position can be obtained simultaneously with the laser irradiation. Laser processing can be performed.
[0030]
In addition, a focus adjustment unit for performing a focusing operation based on image information obtained by the observation unit is provided, and the focusing operation is automatically performed by this, so that the operation is simple and the work efficiency can be improved. it can.
Furthermore, since the laser processing apparatus in which the cores of the large-diameter fiber and the image transmission fiber are made of pure silica are excellent in radiation resistance, it can be suitably used for laser processing in a radiation atmosphere.
[0031]
In the laser processing method of the present invention, a visible guide light having a mask pattern is incident on the composite optical fiber according to claim 1, and a focusing operation is performed by the focus adjusting unit in a state where the visible guide light is irradiated onto the workpiece. Thereafter, a processing laser beam is incident on the composite optical fiber, and the workpiece is irradiated with the processing laser beam to process the workpiece.
Therefore, it is possible to obtain an image in a focused state automatically and reliably. Therefore, laser processing while observing the processing position can be performed easily and efficiently.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a laser processing apparatus of the present invention.
FIG. 2 is a cross-sectional view showing an example of a composite optical fiber that is preferably used in the laser processing apparatus of the present invention.
FIG. 3 is an explanatory view showing an example of visible guide light having a mask pattern according to the present invention.
4 is an explanatory diagram showing an example of an image obtained by irradiating the workpiece with the visible guide light of FIG. 3 and a luminance distribution thereof; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Workpiece, 3 ... Incident lens part, 5 ... Output lens part (output part),
10 ... composite optical fiber, 13 ... large diameter fiber,
14 ... Fiber for image transmission, 20 ... Observation section, 30 ... Focus adjustment section.

Claims (3)

A composite optical fiber in which a large number of image transmission fibers are focused and integrated around a large-diameter fiber for processing laser light transmission;
An incident portion for injecting a processing laser beam into the composite optical fiber;
An emission unit for emitting the processing laser beam transmitted by the composite optical fiber toward the workpiece;
An observation unit that branches visible light emitted from the workpiece at the incident part and observes the visible light;
On the basis of image information obtained by the observation unit, Ri the distance between the emitting portion and the workpiece name includes a focus adjustment unit that performs a fine adjustment to focus operations,
The image transmission fiber comprises a plurality of island-like core, these laser processing apparatus characterized that you have no sea-island structure composed of a continuous sea shape formed by cladding the periphery.   2. The laser processing apparatus according to claim 1, wherein the core of the large-diameter fiber and the image transmission fiber is made of pure silica.   A visible guide light having a mask pattern is incident on the composite optical fiber according to claim 1, and a focusing operation is performed by the focus adjustment unit in a state where the visible guide light is irradiated to the workpiece. 2. A laser processing method using a laser processing apparatus according to claim 1, wherein a laser beam for processing is incident and the workpiece is irradiated with the laser beam for processing to process the workpiece.

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