JP2002273592A - Method and apparatus for laser beam machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of the generation of a debrits and the readhesion thereof to a machining part and its vicinity in a laser beam machining. SOLUTION: The apparatus is provided with a modulator 112 with which the direction of polarization of a laser beam emitted from an oscillator 110 is switched, a polarizer plate 113 which branches the laser beam, a collimator 117 which enlarges one of the branched laser beams, a prism 118 which refracts the enlarged laser beam and the other laser beam branched and not enlarged, respectively, and emits both of the laser beams on the same optical axis, and a condenser lens 119 which condenses the emitted laser beams.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method and an apparatus using a pulse laser, and more particularly to a processing method and an apparatus for cleaning adhered matter generated by laser processing.

[0002]

2. Description of the Related Art Laser processing enables metal cutting, precision processing, and the like, and is widely used in industrial applications. However, there is a problem that the substances decomposed and evaporated during processing become fine particles called debris and adhere again, thereby contaminating the processed part and the surroundings.

Conventionally, as a method of removing this debris,
Laser cleaning has been proposed, and among the removal modes, there are cleaning of a very surface portion of the base material and cleaning of the base material surface.

At present, a CO ₂ laser, a YAG laser, an excimer laser and the like are used for cleaning by a laser, and the use of the laser is generally summarized as follows. Due to the small penetration depth into the surface material, there is an example of application to surface cleaning of fine arts, which requires fine adjustment of the amount of peeling. Since the YAG laser can perform fiber transmission, cleaning of an inner wall of a thin pipe or the like is being studied. In contrast to these lasers, CO ₂ lasers that can be removed in large quantities by deep light penetration into surface adherents are
This laser is suitable for cleaning large-area surfaces such as structural materials.

[0005] There are two types of laser oscillation modes, pulse oscillation and CW oscillation.
CW lasers are suitable for welding and cutting metal materials.

When the surface of the base material is scraped by a pulsed laser, the surface is evaporated before thermal diffusion to the base material occurs, that is, during a thermally non-equilibrium state. Further penetration into the can be reduced.

[0007] Surface cleaning with a pulse laser
This is a method of selectively removing the very surface of the material.

On the other hand, in a CW laser, the surface is thermally melted and the melted surface is removed by evaporation. C
The W method can be used for both cutting and surface cleaning by adjusting the laser output, but there is also the problem of re-melting into the molten layer on the surface.

FIG. 2 shows conventional laser processing and cleaning, in which processing is performed by irradiating a processing laser 212 to a workpiece 210 via a processing laser condenser lens 211. Thereafter, the workpiece 210 is irradiated with the cleaning laser 214 via the cleaning condenser lens 215 to remove debris 216 attached to the workpiece 210.

[0010]

However, in the cleaning method after laser processing as described above, the cost of a cleaning apparatus other than the laser processing apparatus is increased, and the total throughput is increased.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and a processing method capable of forming a high-definition and clean processing on a workpiece by cleaning the workpiece at the same time as processing by a pulse laser. It is an object to provide a processing device.

[0012]

In order to achieve this object, the present invention switches the polarization direction of a pulse laser oscillated from an oscillator, splits the switched laser beam with a polarizing plate, and splits the laser beam. One laser light is expanded by a collimator, the expanded laser light and the other branched laser light are refracted, respectively, emitted on the same optical axis, and the emitted laser light is collected. The workpiece is processed by the other laser beam, and the surface of the workpiece is cleaned by the one laser beam.

[0013]

FIG. 1 is a schematic diagram of a laser processing apparatus according to an embodiment of the present invention. In FIG. 1, laser light 111 emitted from laser oscillator 110 is linearly polarized light, and modulator 112 can arbitrarily change the polarization direction of laser light 111. Further, by installing the wave plate 113 so that the reflection angle with respect to the laser light emitted from the modulator 112 becomes a Brewster angle (56 °), the output of the branched laser light can be adjusted by an electro-optic modulator or an acoustic wave. It can be arbitrarily changed by adjusting the optical modulator 112. In other words, the polarization direction is linearly polarized light of P polarization,
When the laser beam 111 is incident on the wave plate 113, all of the laser light 111 is transmitted. By adjusting the polarization direction of the laser light by the modulator 112, the ratio of the transmitted light and the reflected light of the wave plate 113 can be adjusted. . Therefore, the laser light 1
11 can be split into high-power light 114 and low-power light 115. The low output light 115 is arbitrarily expanded by a collimator 117 whose magnification can be changed. The high-power light 1 refracted on the same optical axis by the prism 118
14 and the low output light 115 are condensed by the same condensing lens 119. The condensing position of the high-power light 114 is constant, and the workpiece 120 is conveyed by the conveying stage 121 to this position and processed.

On the other hand, the condensing position of the low-output light 115 is applied to the workpiece 120 in a defocused state by changing the aperture ratio by adjusting the enlargement ratio by the collimator 117, so that the workpiece 120 is defocused. Is irradiated at a low energy density, and is used for removing debris on the workpiece 120.

Immediately after the workpiece 120 is laser-processed, decomposition products are released, and the laser beam is absorbed to form a high-temperature plasma plume. The atmosphere gas is displaced by the expansion of the plume, and a shock wave called a blast wave is generated. The attachment radius of debris is proportional to the maximum radius Rmax of the blast wave. Then, the visible light laser of the visible light laser oscillator 124 is received, and the maximum radius Rmax of the blast wave is recognized by using the CCD camera 125 for recognizing the blast wave generated when the workpiece 120 is processed. Then, the output data is sent to the image analysis / control device 127.

When the output of the low-output light 115 exceeds the processing threshold value of the workpiece 120, portions other than the processed portion are processed. When the debris is below the threshold value for removing debris attached to the surface of the workpiece 120, a residual residue is generated. Therefore, a recognition laser oscillator 122 that oscillates a visible light laser for recognition,
A laser for processing and cleaning is all transmitted, and a laser for recognition is half-transmitted and half-reflected. CCD camera 123 for recognizing the surface state after processing
By recognizing the processing section, the image analysis / control device 12
Send to 7. Image processing / control device 1 based on the above data
According to 27, the output of the laser oscillator 110 and the modulator 112 are adjusted to change the output of the low-output light 115 while keeping the output of the high-output laser light 114 for processing constant. Also,
Increasing the beam diameter incident on the condenser lens 119 increases the beam diameter of the low-output light 115 applied to the workpiece and increases the removal area.
Adjustment of magnification.

[0017]

As described above, according to the present invention, the polarization direction of the pulse laser oscillated from the oscillator is switched, the switched laser light is branched by the polarizing plate, and one of the branched laser lights is separated. Enlarged by a collimator, the expanded laser light and the other split laser light are refracted, respectively, emitted on the same optical axis, and the emitted laser light is condensed, and the other laser light is condensed. By processing the workpiece and cleaning the surface of the workpiece with the one laser beam, it is possible to perform high-definition and clean processing on the workpiece, and even for a minute material in a short time. Can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a laser processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic view of a conventional laser cleaning.

[Explanation of symbols]

 Reference Signs List 110 pulse laser oscillator 112 modulator 113 polarizing plate 117 collimator 118 prism 119 condenser lens 120 workpiece 123 CCD camera 125 CCD camera 126 controller

Claims (7)

[Claims] 1. A step of switching the polarization direction of a pulse laser emitted from an oscillator, a step of splitting the switched laser light by a polarizing plate, and a step of enlarging one of the split laser lights by a collimator. A step of refracting the expanded laser light and the other split laser light and emitting the same on the same optical axis, condensing the emitted laser light, and processing the workpiece with the other laser light. And cleaning the surface of the workpiece with the one laser beam. 2. The laser processing method according to claim 1, wherein the magnification of the laser beam by the collimator is adjusted to control the surface cleaning area of the workpiece. 3. A method for controlling a laser output of one of the branched laser beams to be between a processing threshold value of a workpiece and a threshold value for removing an adhered substance on a workpiece to be cleaned. The laser processing method according to claim 1, wherein: 4. A step of image-analyzing a processed portion of a workpiece, analyzing a required output of the other split laser beam based on a result of the analysis, and converting a laser output using an oscillator and a modulator. The laser processing method according to claim 1, further comprising an adjusting step. 5. A pulse laser oscillator for oscillating a pulse laser having linear polarization, a modulator for switching the polarization direction of laser light emitted from the pulse laser oscillator, and a Brewster for the laser light emitted from the modulator. It is installed at an angle, a polarizing plate that branches the laser light, a collimator that enlarges one of the branched laser lights, and can change the magnification, and another laser light that is branched from the expanded laser light. A laser beam processing apparatus, comprising: a prism that causes each of the light beams to enter and emits light on the same optical axis; and condensing means for condensing light emitted from the prism. 6. An analysis means for image-analyzing a processed portion of a workpiece, and analyzing a required output of one of the lasers branched to the workpiece based on a result of the analysis, and adjusting an oscillator and a modulator. A laser processing apparatus comprising: 7. The laser processing apparatus according to claim 6, wherein the control device also controls a collimator magnification.