JP2000263267A - Fiber optical system of incidence for laser beam machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a focal depth by providing a fiber optical system of incidence for laser beam machining capable of easily changing a beam cone angle without causing the weight increase of an emitting optical system and without changing the spot diameter of a laser beam at a focal point. SOLUTION: A fiber optical system of incidence is arranged between a laser beam oscillator 11 and an optical fiber 13 and has a fixed aperture 22 and a movable aperture 24. Part of a laser beam converged with an incident side focusing lens 14 is reflected by the movable aperture, is reflected in multiplex between the fixed aperture and the movable aperture and is guided outward. As a result, the laser beam passed the movable aperture has a reduced beam diameter. By this method, the beam diameter which is made incident to a machining head through a collimating lens 26, an emitting side focus lens 27 and the optical fiber 13 is reduced, and the beam cone angle of the laser beam which is emitted from the machining head conducting collimating/converging is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber incidence optical system for a laser processing device.

[0002]

2. Description of the Related Art A laser processing apparatus is an apparatus for cutting, drilling, or welding a workpiece by using a laser beam. In such a laser processing apparatus, a laser beam from a laser oscillator is guided to the vicinity of a workpiece using an optical fiber, and the workpiece is processed through an emission optical system (processing head) attached to an emission end of the optical fiber. There is a type of irradiation.

In a conventional laser processing apparatus, a laser oscillator and an emission optical system are directly connected by an optical fiber. The output optical system includes a collimator lens that converts the laser light emitted from the output end of the optical fiber into parallel light, and a processing lens that collects the parallel laser light emitted from the collimator lens and irradiates the workpiece with the collimated lens. And

In such a laser processing apparatus, in an emission optical system, laser light emitted from an emission end of an optical fiber is converted into parallel light by a collimator lens, condensed by a processing lens, and formed on a workpiece. Irradiated. The workpiece is locally heated by laser light irradiation.
As a result, ablation or the like occurs in a region irradiated with the laser light, and the workpiece is subjected to processing such as cutting.

[0005]

In a conventional laser processing apparatus, the beam cone angle of a laser beam irradiated on a workpiece is determined by the focal length of a collimator lens and a processing lens of an emission optical system, an optical fiber, and a collimator lens. , And the processing lens and the beam diameter of the laser beam incident on the processing lens. That is, in the conventional laser processing apparatus, the beam cone angle is fixed, and there is a problem that the beam cone angle cannot be changed according to the shape of the workpiece.

When a workpiece is cut using a laser processing apparatus, the height direction (the direction of laser beam irradiation) is used.
The cutting allowance for (1) largely depends on the depth of focus at the processing point, and the deeper the depth of focus, the wider the cutting allowance. This depth of focus can be increased by increasing the focal length of the processing lens. However, when the focal length of the processing lens is increased, the spot diameter of the laser beam at the focal point becomes large, and there is a problem that the energy density required for processing cannot be obtained.

Here, it is conceivable to incorporate a beam cone angle adjusting mechanism capable of changing the beam cone angle into the emission optical system. However, it is necessary to increase the size and weight of the emission optical system, which is desired to be small and lightweight. This causes a problem that the movement control of the emission optical system becomes difficult.

The present invention provides a fiber input optical system for a laser processing apparatus capable of easily changing a beam cone angle, and thereby does not increase the weight of an output optical system, and provides a laser beam at a focal point. It is an object to adjust the depth of focus without changing the spot diameter of light.

[0009]

According to the present invention, there is provided a laser processing apparatus including a laser oscillator, a processing head, and a first optical fiber for transmitting laser light from the laser oscillator to the processing head. A fiber incident optical system for a laser processing apparatus, which is disposed between the laser oscillator and the first optical fiber, wherein the collimating lens converts incident laser light into parallel laser light; A first focusing lens for condensing and converging the converged laser light to the first optical fiber; and a first focusing lens disposed before the collimating lens to pass a part of the incident laser light and reflect the rest. A first aperture means for changing the beam diameter of the incident laser light, and a first aperture means disposed before the first aperture means for allowing the incident laser light to pass therethrough. And second aperture means for causing the reflected laser light reflected by the first aperture means to undergo multiple reflections between the first aperture means and guiding the reflected laser light to the outside. Thus, a fiber incidence optical system for a laser processing apparatus is obtained.

Here, it is desirable that the first aperture means is provided so as to be movable along the optical axis of the incident laser light.

Further, according to the present invention, there is provided a laser light absorbing means for absorbing reflected laser light guided outward by the first aperture means and the second aperture means. An emission optical system for a laser processing device is obtained.

The laser beam absorbing means is, for example, a first cooling block and a second cooling block attached to the first aperture means and the second aperture means, respectively.

Further, grooves may be formed on the surfaces of the first cooling block and the second cooling block.

The fiber incident optical system for a laser processing apparatus according to the present invention is used together with a second focusing lens for condensing a laser beam emitted from a laser oscillator, or a tip of an optical fiber for emitting the incident laser beam. It is used by being attached to.

Further, according to the present invention, a laser oscillator for generating a laser beam, a processing head for condensing the laser beam and irradiating the laser beam to an object to be processed, and transmitting the laser beam from the laser oscillator to the processing head In a laser processing apparatus having an optical fiber to propagate, between the laser oscillator and the optical fiber, or in the middle of the optical fiber,
There is provided a laser processing apparatus provided with a fiber incident optical system for adjusting a beam cone angle of laser light emitted from the processing head.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a fiber incident optical system according to the present invention.
As shown in (a) and (b), respectively, a laser oscillator 11 that generates laser light, an emission optical system (processing head) 12 that irradiates a laser beam from the laser oscillator 11 to a processing target, and And an optical fiber 13 (or 13a and 13b) for transmitting a laser beam from the laser oscillator 11 to the emission optical system 12.

In the laser processing apparatus shown in FIG. 1A, a fiber incident optical system is provided between a laser oscillator 11 and an optical fiber 13. In this case, the fiber incidence optical system is directly attached to the laser oscillator 11. Further, it has an incident-side focusing lens 14 for condensing laser light, which is parallel light from the laser oscillator 11. This laser processing apparatus has a relatively high optical fiber 13
Is suitable, for example, when the length is 10 m or less.
In the laser processing apparatus shown in FIG. 1B, a fiber incident optical system is inserted between the optical fibers 13a and 13b. In this case, since the laser beam emitted from the optical fiber 13a diverges, the incident side focusing lens as shown in FIG. 1A is unnecessary. This laser processing device is suitable when the total of the optical fibers 13a and 13b is relatively long, for example, when the total length is 10 m or more. The length of the optical fiber 13b is preferably 5 m or less in consideration of the influence of the NA of the optical fiber.

Next, a fiber incident optical system for a laser processing apparatus according to an embodiment of the present invention will be described in detail with reference to FIG. The fiber incident optical system shown in FIG.
Since it is of a type fixed to the laser oscillator 11, it has an incident-side focusing lens 14.
In the case where the optical fiber is connected between two optical fibers as shown in FIG. 1B, the incident side focusing lens 14 is unnecessary. Also, when the laser oscillator 11 includes a focusing lens for condensing the emitted light, the incident-side focusing lens 14 is unnecessary.

The fiber incidence optical system shown in FIG. 2 is housed in a case 21 fixed to the laser oscillator 11. The fiber incident optical system includes an incident side focusing lens 1 for condensing laser light from a laser oscillator 11.
4, a fixed aperture 22 having an opening through which the divergent laser light condensed by the incident-side focusing lens 14 passes, a fixed cooling block 23 for fixing the fixed aperture 22 to the case 21, and an opening of the fixed aperture 22. A movable aperture 24 having an opening for further passing the laser light passing therethrough, a movable cooling block 25 supporting the movable aperture 24 so as to be movable along the optical axis of the laser light from the incident side focusing lens 14, a movable aperture The collimating lens 26 collimates (converts into parallel light) the laser light passing through the opening 24, and the emission-side focusing lens 27 that collects the laser light collimated by the collimating lens 26 and makes the collimated laser light enter the optical fiber 13. are doing.

As shown in FIG. 2, the laser beam condensed at the point A by the incident side focusing lens 14 then enters the fixed aperture 22 while diverging. The size of the opening of the fixed aperture 22 is a size that allows all the incident laser light to pass therethrough at the installation position, and a size that blocks the passage of the laser light reflected by the movable aperture 24. The size of the opening of the movable aperture 24 is such that
When the movable aperture 24 is located farther from the fixed aperture 22 and is closer to the collimating lens 26 when the movable aperture 24 is located closer to the collimator lens 26, a part of the laser light is transmitted. To a size that blocks

Fixed aperture 22 and movable aperture 2
The surfaces facing each other are reflection surfaces that reflect laser light. As a result, the laser beam cut by the movable aperture 24 is
The light is guided outward while being multiple-reflected between and the movable aperture 24.

Grooves 28 are respectively formed on the surfaces of the fixed cooling block 23 and the movable cooling block 25 so as to absorb all the laser beams multiple-reflected between the fixed aperture 22 and the movable aperture 24. Cooling water is circulated inside the fixed cooling block 23 and the movable cooling block 25. Further, a height adjusting screw 29 for moving the movable cooling block 25 in the vertical direction in the figure is fixed to the movable cooling block 25, and the height adjusting screw 29 is attached to the outside of the case 21. The part is exposed.

The operation of the output optical system will be described below with reference to FIGS.

First, referring to FIG.
To move the movable aperture 24 to the fixed aperture 2
2 will be described. In this case, the laser beam transmitted through the incident side focusing lens 14 is
All of the light passes through the openings of the fixed aperture 22 and the movable aperture 24 and enters the collimator lens 26. Then, the laser beam incident on the collimating lens 26 is collimated there,
7, the light is condensed there, and is incident on the optical fiber 13.

The laser light that has propagated to the emission optical system 12 through the optical fiber 13 is collimated by a collimating lens 31, condensed by a processing lens 32, and irradiated on a processing target. In this case, the beam cone angle of the laser light emitted from the emission optical system 12 to the object to be processed is equal to the beam cone angle when the fiber incidence optical system does not exist.

Next, referring to FIG.
To move the movable aperture 24 to the collimating lens 2
The case of approaching 6 will be described. in this case,
A part of the laser light that has passed through the opening of the fixed aperture 22 passes through the opening of the movable aperture 24 as it is, and the rest is reflected by the movable aperture 24. The ratio of the laser beam reflected by the movable aperture 24 increases as the movable aperture 24 approaches the collimator lens 26. Further, the beam diameter of the laser light incident on the collimator lens 26 decreases as the movable aperture 24 approaches the collimator lens 26.

The laser beam incident on the collimating lens 26 is collimated by the collimating lens 26 and then condensed by the focusing lens 27 on the outgoing side, as in the case of FIG. The laser light that has propagated through the optical fiber 13 is collimated by the collimating lens 31 in the emission optical system 12, condensed by the processing lens 32, and irradiated on the workpiece.

Here, the laser beam cone angle of the laser beam applied to the workpiece becomes smaller as the beam diameter of the laser beam incident on the collimator lens 17 of the fiber incident optical system becomes smaller. That is, the closer the movable aperture 24 is to the collimating lens 26, the smaller the laser beam cone angle becomes. In FIG. 4, the laser light when the movable aperture 24 allows all of the laser light to pass is indicated by a broken line, and the laser light when the laser light is partially reflected is indicated by a two-dot chain line. Also, as the laser beam cone angle decreases, the depth of focus also increases.

On the other hand, the laser light reflected by the movable aperture 24 travels outward while being repeatedly reflected (multiple reflection) between the fixed aperture 22 and the movable aperture 24, and travels outward. 25
Incident on. The fixed cooling block 23 and the movable cooling block 25 cooperate to almost completely absorb the incident laser light. That is, the fixed cooling block 23 and the movable cooling block 25 absorb the incident laser light almost completely, so that the laser light reflected on the surface is again incident on the fixed cooling block 23 or the movable cooling block 25. The cross section has a substantially U shape and arrangement, and a groove 28 is formed in a part of the surface. The laser light that has entered the groove 28 cannot go out of the groove unless it is reflected a plurality of times on the side and bottom surfaces of the groove 28 and is absorbed during that time. The fixed cooling block 23 and the movable cooling block 25 generate heat by absorbing a laser beam. This heat is discharged outside by the cooling water flowing into the fixed cooling block 23 and the movable cooling block 25, respectively.

As described above, the fiber incident optical system according to the present embodiment can arbitrarily change the beam cone angle applied to the workpiece by adjusting the position of the movable aperture 24. Similarly, FIG.
As shown in (b), even when the fiber incident optical system according to the present embodiment is inserted between the two optical fibers, the position of the movable aperture 24 is adjusted so that the beam cone irradiated on the workpiece is adjusted. The angle can be changed arbitrarily.

In a state where the beam is not cut by the movable aperture 24 (the state shown in FIG. 3), the collimator lens 3
The beam diameter of the laser beam incident on the laser beam 1 is Do, and the beam is cut by the movable aperture 24 (the state of FIG. 4).
, The beam diameter of the laser beam incident on the collimating lens 31 is Da, the beam cone angles in each case are θo and θa, and the outputs at the processing points are Po and P
a, the beam diameter ratio (Da / Do) incident on the collimating lens 31 and the cone angle ratio (θa / θ)
FIG. 5 shows the relationship between the beam diameter and the beam diameter ratio (Da / D).
FIG. 6 shows the relationship between o) and the output ratio (Pa / Po).

In the above embodiment, the beam diameter of the laser beam incident on the collimator lens 26 is changed by moving the movable aperture 24 in the direction of the optical axis. Can be.

[0034]

According to the present invention, by providing a fiber incident optical system provided between the laser oscillator and the optical fiber or in the middle of the optical fiber, the size and weight of the processing head are increased. Instead, the beam cone angle of the laser light emitted from the processing head can be adjusted arbitrarily. This makes it possible to select a beam cone angle suitable for various processes, from processing requiring a relatively high laser beam output to processing in a narrow recess. Further, when cutting a workpiece, it is possible to increase the depth of focus without changing the spot diameter and to provide a processing margin in the height direction.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a laser processing apparatus including a fiber incident optical system according to an embodiment of the present invention,
(A) shows an example in which the fiber incident optical system is attached to the laser oscillator, and (b) shows an example in which the fiber incident optical system is provided in the middle of the optical fiber.

FIG. 2 is a configuration diagram showing a configuration of a fiber incident optical system in FIG.

FIG. 3 is a diagram for explaining the operation of the fiber incident optical system of FIG. 2;

FIG. 4 is a diagram for explaining the operation of the fiber incident optical system of FIG. 2;

FIG. 5 is a graph showing a relationship between a beam diameter ratio and a beam cone angle ratio in the emission optical system of FIG.

FIG. 6 is a graph showing a relationship between a beam diameter ratio and an output ratio in the emission optical system of FIG.

[Explanation of symbols]

 Reference Signs List 11 laser oscillator 12 emission optical system 13, 13a, 13b optical fiber 14 incident side focusing lens 21 case 22 fixed aperture 23 fixed cooling block 24 movable aperture 25 movable cooling block 26 collimating lens 27 emission side focusing lens 28 groove 29 height adjusting screw 31 Collimating lens 32 Processing lens

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H037 AA04 BA06 DA02 DA06 DA35 DA38 4E068 CA07 CB05 CB06 CD01 CD10 CE08 CH08

Claims (8)

[Claims] 1. A laser processing apparatus comprising: a laser oscillator; a processing head; and a first optical fiber for transmitting laser light from the laser oscillator to the processing head. A collimating lens for converting incident laser light into parallel laser light; and a collimated laser light for condensing the parallel laser light. A first focusing lens that causes the incident light to enter the first optical fiber, and is disposed in front of the collimating lens, passes a part of the incident laser light and reflects the remainder to reduce the beam diameter of the incident laser light. A first aperture means for changing; and a first aperture means disposed before the first aperture means for passing the incident laser beam and reaching the first aperture means. And second aperture means for guiding the reflected laser light reflected by the first aperture means to the outside through multiple reflection between the first laser and the first aperture means. Characteristic fiber incident optical system for laser processing equipment. 2. A fiber incident optical system for a laser processing apparatus according to claim 1, wherein said first aperture means is provided so as to be movable along an optical axis of said incident laser light. 3. The first aperture means and the second aperture means.
3. A fiber incident optical system for a laser processing apparatus according to claim 1, further comprising a laser light absorbing means for absorbing the reflected laser light guided outward by said aperture means. 4. The apparatus according to claim 1, wherein said laser beam absorbing means is a first cooling block and a second cooling block attached to said first aperture means and said second aperture means, respectively. 3. Fiber incident optical system for laser processing equipment. 5. A fiber incident optical system for a laser processing apparatus according to claim 4, wherein grooves are formed on the surfaces of said first cooling block and said second cooling block. 6. A focusing lens according to claim 1, further comprising a second focusing lens for condensing the laser light emitted from said laser oscillator to be said incident laser light.
3, 4, or 5, a fiber incident optical system for a laser processing apparatus. 7. A fiber incident optical system for a laser processing apparatus according to claim 1, wherein said optical fiber is attached to a tip of a second optical fiber for emitting said incident laser light. . 8. A laser oscillator that generates laser light, a processing head that focuses the laser light and irradiates the processing target, and an optical fiber that propagates the laser light from the laser oscillator to the processing head. In the provided laser processing apparatus, a fiber incident optical system for adjusting a beam cone angle of laser light emitted from the processing head is provided between the laser oscillator and the optical fiber or in the middle of the optical fiber. A laser processing apparatus characterized by the above-mentioned.