JPH08267261A - Laser beam machine provided with fiber damage monitor - Google Patents

Abstract

PURPOSE: To prevent the emitting end face of optical fiber from damage by detecting energy of laser beam reflected with part to be machined and returned to emitting optical system and comparing it with set value. CONSTITUTION: Part of the laser beam emitted from optical fiber reaches to an energy monitor 32 through a mirror 33. The detected value of an energy monitor 32 is monitored by a comparator 35, in the case the detected value exceeds the set upper limit value and set lower limit value, an alarm signal is released so as to display in a display 36. Further, part of the laser beam reflected from machining point reaches an energy monitor 31. In case the detected value of energy monitor 31 exceeds the upper limit of comparator 33, a first abnormality detected signal is outputted and then a shutter control circuit 34 is actuated, the laser beam radiation to outside is stopped. In the case the ratio of detected values of energy monitor 31 and 32 exceeds the upper limit value, a third abnormality detected signal is outputted and then the shutter control circuit 34 is actuated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus for guiding a laser beam from a laser light source to an emission optical system through an optical fiber, and irradiating a laser beam to a work (work) from the emission optical system for processing. In particular, the present invention relates to a laser processing apparatus provided with a fiber damage monitor for preventing the laser light reflected by the processed portion from returning to the inside of the emission optical system and damaging the emission end face of the optical fiber.

[0002]

2. Description of the Related Art An example of a laser processing apparatus will be schematically described with reference to FIG. In FIG. 6, the workpiece mounting table 65 is moved in one direction (here, x by the first ball screw mechanism 61).
Gate-shaped movable frame 60 that can travel in the axial direction)
In addition, a movable frame 64 that is movable in the y-axis direction and the z-axis direction by the second ball screw mechanism 62 and the third ball screw mechanism 63 is attached. Below the movable frame 64, a laser irradiation unit 1 including an emission optical system for laser light irradiation and a drive mechanism for driving the emission optical system in three axial directions of x, y, and z.
00 is attached. A cable-shaped optical fiber 67 is led out from a drive unit 66 having a built-in laser oscillation source and the like, and the optical fiber 67 is laser-irradiated in a deformable state in association with the movement of the movable frame 64 and the laser irradiation unit 100. It is connected to the section 100. Reference numeral 68 denotes an operation box in which a switch for starting and stopping the apparatus, a button for remote control operation, and the like are mounted, and is attached to the movable frame 60. 69 is for inputting setting values for laser processing the work by numerical control or the like,
It is an operation panel for displaying various data. For example, a YAG laser device is used as the laser oscillation source.

The emission optical system focuses the laser light emitted from the emission end of the optical fiber to a processing point of a portion to be processed through a recollimating lens, a processing lens, etc., and performs processing such as cutting and welding.

By the way, when processing a portion having a high reflectance for laser light, most of the laser light focused at the processing point may be reflected depending on the laser conditions. Then, this reflected laser light travels in the opposite direction in the emission optical system and returns to the vicinity of the emission end face of the optical fiber, which may damage the optical fiber.

Several methods have been proposed to prevent damage to the optical fiber due to such reflected laser light, which will be described below. In the first method, FIG.
As shown in FIG.
A reflector 71 is installed in the vicinity of the emission end face of the. The reflector 71 is a beam-like reflected laser light 72 shown by a broken line.
Is diffused when it returns to the vicinity of the emitting end face of the optical fiber 67. The beam-shaped laser light emitted from the optical fiber 67 is shown by a solid line 73.

In the second method, as shown in FIG. 8, the positions of the re-collimating lens 74 and the processing lens 75 in the emission optical system are adjusted so that the condensing point of the laser light 73 is the processing point of the processed portion 76. It's moving away. In this way, when the reflected laser light 72 returns to the vicinity of the emission end face of the optical fiber 67, it becomes in a diffused state.

In the third method, as shown in FIG. 9, the attitude of the emission optical system is adjusted so that the optical axis of the laser beam 73 with respect to the processed surface of the processed portion 76 is 90 ° from the fixed angle θ.
Only tilt. In this way, the reflected laser light 72 from the processing point does not enter the emission optical system.

[0008]

However, with the above first and second methods, it is not possible to know the degree of damage to the emission end face of the optical fiber 67 during laser processing. For this reason,
After the laser processing is completed, it is necessary to measure the energy of the laser beam emitted from the emission optical system or to take a measure to replace the optical fiber 67 after the optical fiber 67 is damaged. Moreover, it is difficult to prevent damage to the optical fiber 67 when an inappropriate laser condition with a large amount of reflection is selected or the material of the processed portion having a high reflectance is mishandled.

On the other hand, in the third method, in order to obtain deep penetration, the inclination angle of the emission optical system is naturally limited, and the return of the reflected laser light cannot be completely eliminated. Further, in the cutting process, the inclination angle of the emission optical system must be constantly kept constant with respect to the traveling direction so that the cutting surface is not tapered. To realize this, the control system becomes complicated, and the inclination angle cannot always be maintained depending on the shape of the processed portion 76.

In view of the above problems, the main problem of the present invention is that the laser light introduced from the optical fiber into the emission optical system or the reflected laser reflected from the portion to be processed and returned to the emission optical system. It is an object of the present invention to provide a laser processing apparatus equipped with a fiber damage monitor capable of monitoring the energy of light and preventing damage to the emitting end face of an optical fiber due to reflected laser light.

[0011]

The present invention guides laser light from a laser light source to an emission optical system through an optical fiber,
It is applied to a laser processing apparatus that irradiates a processed portion with laser from the emission optical system to perform processing, and in the first invention, energy of laser light reflected by the processed portion and returned to the emission optical system. Comparing the first detection value of the first monitor and the first detection value of the first monitor with a predetermined first upper limit value, and the first detection value exceeds the first upper limit value. A fiber damage monitor including a first comparator that outputs a first abnormality detection signal.

In the second invention, the first monitor for detecting the energy of the laser beam reflected by the processed portion and returned to the emitting optical system, and the laser beam introduced into the emitting optical system. A second monitor for detecting the energy of the second monitor and a ratio of the first detection value of the first monitor to the second detection value of the second monitor, and the ratio exceeds a predetermined value. And a fiber damage monitor including a ratio determination unit that outputs a second abnormality detection signal.

In the third invention, the first monitor for detecting the energy of the laser light reflected by the processed portion and returned to the emission optical system, and the laser light introduced into the emission optical system. Of the second monitor for detecting the energy of the first monitor and the first detection value of the first monitor are compared with a predetermined first upper limit value, and the first detection value compares the first upper limit value with the first upper limit value. A first comparator that outputs a first abnormality detection signal when it exceeds and a ratio of the first detection value to the second detection value of the second monitor are calculated, and the ratio is a predetermined value. The fiber damage monitor includes a ratio determination unit that outputs a second abnormality detection signal when the value exceeds the above.

In a fourth aspect of the invention, a second monitor for detecting the energy of the laser beam introduced into the emission optical system,
If the second detection value of the second monitor is within a range between a predetermined lower limit value and a predetermined upper limit value, the second detection value is outside the range. And a second comparator for outputting the abnormality detection signal of No. 3, and a fiber damage monitor.

As a first modification of the fourth invention, the fiber damage monitor further detects the energy of the laser beam reflected by the processed portion and returned to the emission optical system. And comparing the first detection value of the first monitor with a predetermined first upper limit value,
May include a first comparator that outputs a first abnormality detection signal when the detection value of 1 exceeds the first upper limit value.

As a second modification of the fourth invention, the fiber damage monitor further detects the energy of the laser beam reflected by the processed portion and returned to the emission optical system. And a ratio determination unit that calculates a ratio of the first detection value of the first monitor to the second detection value and outputs a second abnormality detection signal when the ratio exceeds a predetermined value. May be included.

As a third modified example of the fourth invention, the fiber damage monitor further detects the energy of the laser beam reflected by the processed portion and returned to the emission optical system. And comparing the first detection value of the first monitor with a predetermined first upper limit value, and when the first detection value exceeds the first upper limit value, a first abnormality detection signal is output. A first comparator for outputting and a ratio determination for calculating a ratio of the first detection value to the second detection value and outputting a second abnormality detection signal when the ratio exceeds a predetermined value. May be included.

[0018]

In the fiber damage monitor according to the first aspect of the present invention, when the energy of the reflected laser light returning into the emission optical system exceeds a certain value, it is determined that the emission end face of the optical fiber is damaged. An abnormality detection signal is output and an alarm is displayed by this first abnormality detection signal, or the laser shutter in the laser light source is closed.

A fiber damage monitor according to another invention detects the output of the laser light emitted from the optical fiber and the output of the reflected laser light in order to monitor the damage of the fiber emitting end face by the reflected laser light. The output decrease and the abnormal increase of the reflected beam due to the fiber damage can be monitored at the same time, and when the respective values exceed a certain value, an alarm is generated.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an emission optical system to which the present invention is applied. Referring also to FIG. 2, which is an enlarged view of part A of FIG.
A fiber conduit 10 containing an optical fiber 11 is connected to an output optics 20 into which a laser beam is introduced. A reflector 12 is attached near the emitting end of the optical fiber 11 and is used to diffuse the reflected laser light. Furthermore, in order to protect the optical fiber by the reflected laser light, a regulation member 21 having an aperture is installed in the emission optical system 20 to limit the amount of the reflected laser light.

The exiting optical system 20 has a recollimating lens 2
2, the mirrors 23 and 24, the processing lens 25, and the slide glass 26 are installed to focus the laser beam on the processing point P. In addition to the above-described components, an observation optical system 29 including a half mirror 27 and a total reflection mirror 28 is provided for photographing and monitoring the area of the processing point P and for performing focusing control. ing. It should be noted that it is desirable to use a lens through which the laser beam passes and a slide glass with an antireflection coating.

In order to detect the energy of the laser beam (emitted beam) introduced into the emission optical system 20 and the energy of the reflected laser light (reflected beam) returned to the emission optical system 20, an energy monitor 31 (first Monitor) and energy monitor 32 (second monitor), respectively.
It is installed so as to be at a position of about 45 degrees.
The energy monitors 31 and 32 detect the energies of the outgoing beam and the reflected beam transmitted through the mirror 23, respectively.
Each energy monitor includes optical parts such as a light receiving part, a filter, and a diffuser, and has an offset and sensitivity correction function.

Next, the fiber damage monitor according to the present invention will be described with reference to FIG. The fiber damage monitor performs alarm determination and shutter closing of the laser light source by performing a determination operation described later using the detection values of the energy monitors 31 and 32. Therefore, the energy monitor 31 is connected to a shutter control circuit 34 of the laser light source via a comparator 33 (first comparator). The comparator 33 compares the detection value of the energy monitor 31 (hereinafter, referred to as a first detection value) with a predetermined first upper limit value (EM1 upper limit value), and the detection value is equal to the first upper limit value. If it exceeds, an abnormality detection signal (first abnormality detection signal) is output. This first upper limit value can be set arbitrarily.

The energy monitor 32 has a comparator 35 (second
The display 36 is connected via the comparator of FIG. In the comparator 35, the detection value of the energy monitor 32 (hereinafter referred to as the second detection value) is a predetermined lower limit value (EM2).
(Lower limit value) and a predetermined upper limit value (EM2 upper limit value) are compared, and if the second detection value is out of the range, an abnormality detection signal (third abnormality detection signal) is detected. Output as an alarm signal. Of course, the upper limit and the lower limit can be set arbitrarily.

On the other hand, both the energy monitors 31 and 32 are connected to a ratio judging section consisting of an arithmetic circuit 37 and a comparator 38, and the output of this ratio judging section is the shutter control circuit 3.
4 is connected. The arithmetic circuit 37 uses the first value of the energy monitor 31 for the second detection value of the energy monitor 32.
The ratio of the detection values of (hereinafter, referred to as EM ratio) is calculated. The comparator 38 compares the EM ratio with a predetermined value, and outputs an abnormality detection signal (second abnormality detection signal) when the EM ratio exceeds a predetermined ratio upper limit value. The upper limit of the ratio in the comparator 38 can be set arbitrarily.

Next, the operation will be described. The laser beam emitted from the optical fiber 11 is guided to the emission optical system 20, passes through the aperture of the regulation member 21, becomes parallel light by the recollimator lens 22, and is reflected by the mirrors 23 and 24.
It is bent once, passes through the processing lens 25 and the slide glass 26, and is focused on the processing point P.

During the laser processing, a part of the laser beam emitted from the optical fiber 11 reaches the energy monitor 32 via the mirror 23. As a result, by monitoring the second detection value of the energy monitor 32 with the comparator 35, it is possible to monitor whether or not the output decrease due to the optical fiber damage has occurred. When the upper limit value and the lower limit value set by the comparator 35 are exceeded, the comparator 35 generates an alarm signal and displays it on the display 36. For example, when the output of the incident laser beam is reduced and exceeds a predetermined lower limit value (EM2 lower limit value) as shown in FIG. 4, an alarm signal is turned on and an abnormality is displayed.

The reflected laser light reflected from the processing point P passes through the mirror 24 and a part of the reflected laser light reaches the energy monitor 31. The level of the reflected laser light is monitored by the following two methods. When the level exceeds the first upper limit value (EM1 upper limit value) or exceeds the EM ratio, the shutter control circuit 34 of the laser light source operates to the outside. Stop the laser irradiation of.

That is, when the first detection value of the energy monitor 31 exceeds the first upper limit value (EM1 upper limit value) of the comparator 33, the first abnormality detection signal is output and the shutter control circuit 34 operates. . When the ratio between the detection values of the energy monitor 31 and the energy monitor 32 exceeds the upper limit value (EM ratio), the third abnormality detection signal is output and the shutter control circuit 34 operates.

FIG. 5 shows an operation example of the shutter control circuit 34 when the level of the reflected laser light is high. As the pattern of the reflected laser light, there are C1 when it gradually increases and C2 when it rapidly increases. In either case, when the respective upper limit values (EM1 upper limit value or EM ratio) are exceeded, the shutter of the laser light source is closed by the shutter control circuit 34.

The monitor operation as described above prevents damage to the optical fiber, and the reflected laser light reflected by the mirror 23 is scattered toward the recollimator lens 22.
Part of the light is guided to the vicinity of the emission end of the optical fiber 11 by the recollimator lens 22, but the regulating member 21 and the reflector 1
Since it is limited by 2, the effect of preventing damage to the optical fiber 11 is high.

In addition, by disposing the energy monitors 31 and 32 at an angle of 45 degrees with respect to the mirror 23 arranged in the exit optical system 20, the mirror 23 is provided.
The change due to the temperature change or the like can be canceled by calculating the output ratio of the energy monitors 31 and 32.

The configuration of FIG. 3 is the most preferable example, and only one of the energy monitors may be used. A possible configuration example in this case is as follows.

A combination of the energy monitor 31, the comparator 33 and the shutter control circuit 34.

Energy monitors 31, 32 and arithmetic circuit 3
7 in combination with the comparator 38 and the shutter control circuit 34.

Energy monitors 31, 32 and comparator 33
, Arithmetic circuit 37, comparator 38, and shutter control circuit 34
In combination with.

A combination of the energy monitor 32 with the comparator 35 and the display 36.

Energy monitors 31, 32 and comparator 33
And a combination of the shutter control circuit 34, the comparator 35, and the display 36.

Energy monitors 31, 32 and comparator 35
And a combination of the display device 36, the arithmetic circuit 37, the comparator 38, and the shutter control circuit 34.

Energy monitors 31, 32 and comparator 35
And the display 36, the comparator 33, the arithmetic circuit 37, and the comparator 3.
8 and the shutter control circuit 34.

[0041]

The following effects can be obtained by installing the fiber damage prevention monitor according to the present invention.

1) In the work material having a high reflectance, the selection of the laser conditions is inappropriate (including the deviation between the converging point and the processing point), and most of the irradiated laser light returns to the emitting end face of the optical fiber. Even if the output of the reflected laser light is monitored and an output exceeds a certain value, an alarm is generated instantly, or the shutter of the laser light source is closed to prevent major damage to the optical fiber. it can.

2) By monitoring the output of the laser light introduced from the optical fiber to the emission optical system, even if the optical fiber deteriorates over time, it can be monitored, and the output can be greatly reduced at the processing point. It can be prevented.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an emission optical system of a laser processing apparatus to which the present invention has been applied.

FIG. 2 is an enlarged view of part A of FIG.

FIG. 3 is a block diagram showing a configuration of a fiber damage prevention monitor according to the present invention.

FIG. 4 is a signal waveform diagram for explaining the operation of the comparator 35 of FIG.

5 is a signal waveform diagram for explaining the operation of the comparators 33 and 38 of FIG.

FIG. 6 is a perspective view showing a schematic configuration of a laser processing apparatus.

FIG. 7 is a diagram for explaining a first method for preventing damage to an optical fiber in the related art.

FIG. 8 is a view for explaining a second conventional method of preventing damage to an optical fiber.

FIG. 9 is a diagram for explaining a third conventional method of preventing damage to an optical fiber.

[Explanation of symbols]

 10 Fiber Composite 11,67 Optical Fiber 12,71 Reflector 21 Controlling Member 22,74 Recollimating Lens 23,24 Mirror 25,75 Processing Lens 26 Slide Glass 31,32 Energy Monitor

Claims (7)

[Claims] 1. A laser processing apparatus for guiding a laser beam from a laser light source to an emission optical system through an optical fiber, and irradiating the processed portion with laser from the emission optical system to perform processing.
A first monitor for detecting the energy of the laser beam reflected by the processed portion and returning to the emission optical system, and a first monitor for which a first detection value of the first monitor is predetermined.
Laser processing apparatus including a fiber damage monitor including a first comparator that outputs a first abnormality detection signal when the first detection value exceeds the first upper limit value as compared with the first upper limit value. 2. A laser processing apparatus for guiding a laser beam from a laser light source to an emission optical system through an optical fiber, and irradiating the processed portion with laser from the emission optical system to perform processing.
A first monitor that detects the energy of the laser light reflected by the processed portion and returned to the emission optical system, and a second monitor that detects the energy of the laser light introduced into the emission optical system. And calculating a ratio of the first detection value of the first monitor to the second detection value of the second monitor, and outputting a second abnormality detection signal when the ratio exceeds a predetermined value. Laser processing apparatus provided with a fiber damage monitor including a ratio determining unit. 3. A laser processing apparatus for guiding a laser beam from a laser light source to an emission optical system through an optical fiber, and irradiating a laser beam to a processed portion from the emission optical system for processing.
A first monitor for detecting energy of laser light reflected by the processed portion and returning to the emission optical system, and a second monitor for detecting energy of laser light introduced into the emission optical system. And comparing the first detection value of the first monitor with a predetermined first upper limit value, and
When the detected value exceeds the first upper limit value, the ratio of the first detected value to the second detected value of the second monitor and the first comparator which outputs a first abnormality detection signal is calculated. A laser processing apparatus provided with a fiber damage monitor including a ratio determination unit that outputs a second abnormality detection signal when the calculated ratio exceeds a predetermined value. 4. A laser processing apparatus that guides laser light from a laser light source to an emission optical system through an optical fiber, and irradiates a laser beam onto a processed portion from the emission optical system to perform processing.
A second monitor for detecting energy of the laser light introduced into the emission optical system, and a second detection value of the second monitor in a range of a predetermined lower limit value and a predetermined upper limit value. A laser processing apparatus provided with a fiber damage monitor including a second comparator that outputs a third abnormality detection signal when the second detection value deviates from the range by comparing whether or not it is within the range. 5. The laser processing apparatus according to claim 4, further comprising: a first monitor for detecting energy of laser light reflected by the processed portion and returned to the emission optical system, and the first monitor. Comparing the first detection value of the monitor with a predetermined first upper limit value and outputting a first abnormality detection signal when the first detection value exceeds the first upper limit value. A laser processing apparatus having a fiber damage monitor including a comparator. 6. The laser processing apparatus according to claim 4, further comprising: a first monitor for detecting energy of laser light reflected by the processed portion and returning to the emission optical system; and the second monitor. A fiber damage monitor including a ratio determining unit that calculates a ratio of the first detection value of the first monitor to the detection value of the first monitor and outputs a second abnormality detection signal when the ratio exceeds a predetermined value. Laser processing equipment equipped with. 7. The laser processing apparatus according to claim 4, further comprising: a first monitor for detecting energy of laser light reflected by the processed portion and returned to the emission optical system; and the first monitor. Comparing the first detection value of the monitor with a predetermined first upper limit value and outputting a first abnormality detection signal when the first detection value exceeds the first upper limit value. A comparator and the first detection value for the second detection value
A laser processing apparatus including a fiber damage monitor including a ratio determination unit that calculates a ratio of the detected values and outputs a second abnormality detection signal when the ratio exceeds a predetermined value.