JP2011177738A - Laser beam machining apparatus and laser beam machining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus and a laser beam machining method, capable of removing any machining removal stuff, suppressing pollution of a laser beam system with a liquid, and efficiently irradiating with a laser beam. <P>SOLUTION: This invention relates to an apparatus for machining by irradiating a workpiece W with the laser beam L, including a laser beam irradiation mechanism 2 for irradiating the workpiece W with the laser beam L, and a fluid supplying mechanism 3 in which the laser beam L allows a transparent fluid F to flow on a machining surface of the workpiece W in a laminar flow state along the machining surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus and a laser processing method suitable for processing ultra-hard materials, for example.

  In general, a mechanical method such as grinding with a grindstone is used to shape a member or a tool using an ultra-hard material such as a cubic boron nitride sintered body (hereinafter referred to as a CBN sintered body) or a diamond sintered body. The shaping is done. However, CBN sintered bodies and diamond sintered bodies are mechanically strong, and it has been difficult to perform micron-order precision processing with a grindstone that deforms with each processing. Also known is a method of performing processing such as cutting by irradiating a member having a surface made of a CBN sintered body or a diamond sintered body with a laser beam and repeatedly scanning in order to obtain desired processing properties. Yes. In this method, when the next laser beam is scanned due to the deposition of a work removal material such as a melt generated by the laser light irradiation, the laser light is inhibited and absorbed by the deposited work removal material and processed. The speed was reduced, and efficient and precise surface processing was difficult.

  For this reason, as a method for preventing the accumulation of the processed removed material, conventionally, a method of blowing the processed removed material with an assist gas or a method of spraying water at a high pressure as described in Patent Document 1, for example, has been proposed. In this method, the processed part is cooled by spraying water at a high pressure, but it is considered that the processed removal can also be blown away. Patent Document 2 proposes a technique of storing a liquid such as distilled water in a processing housing in which a workpiece is held and irradiating the workpiece with laser light through the liquid. In this method, the processing housing is formed of a transparent plate of transparent glass or transparent resin in order to transmit laser light.

JP 2006-96051 A JP 2009-66657 A

The following problems remain in the conventional technology.
In other words, it is difficult to blow off all the processed removal by the processing method using the conventional assist gas, and the conventional method of spraying water has a disadvantage that the water pressure is high and the optical system of the laser beam is contaminated by rebounding. there were. In the technique described in Patent Document 2, since the liquid is accommodated in the processing housing, laser light is incident from the outside of the processing housing through the processing housing. Therefore, the processing housing is formed of a transparent plate. However, there is a problem that the laser beam is attenuated during transmission and the processing housing itself is damaged by the laser beam.

  The present invention has been made in view of the above-described problems, and can provide a laser processing apparatus and a laser that can remove a workpiece and can prevent contamination of a laser optical system with a liquid and can irradiate laser light more efficiently. An object is to provide a processing method.

  The present invention employs the following configuration in order to solve the above problems. That is, the laser processing apparatus of the present invention is an apparatus that processes a workpiece by irradiating the workpiece with a laser beam, the laser beam irradiation mechanism that irradiates the workpiece with the laser beam, and the processing of the workpiece. And a liquid supply mechanism for flowing a liquid in which the laser beam is transparent on the surface in a laminar flow state along the processing surface.

  The laser processing method of the present invention is a method of processing by irradiating a processing target with laser light, wherein the laser light is transparent on the processing surface of the processing target, and the laminar flow along the processing surface is performed. And a step of irradiating the workpiece with the laser light through the laminar liquid.

  In these laser processing apparatuses and laser processing methods, a transparent liquid is caused to flow on the processing surface of the processing object in a laminar flow state along the processing surface, so that it is transmitted through the transparent liquid that becomes a film on the processing surface. The laser beam processes the object to be processed, and the generated processed removal object is steadily discharged without being scattered from the vicinity of the processing point by the liquid as the deposit removing liquid. At this time, if the liquid is simply flowed to the processing surface, the liquid may be in a turbulent state and rippling, and the condensing of the transmitted laser light may be disturbed, and the image formation (focus) may not be accurately adjusted. In the present invention, since the liquid is flowed in an optically stable laminar flow state, the laser beam can be accurately focused on the processing surface. In addition, when the liquid is in a turbulent state, the flowed work removal may return to the vicinity of the processing point again, whereas in the present invention, the liquid is flowed in a laminar state, so that the processing is performed near the processing point. The removed material will not return. Therefore, it is possible to remove all the processed removal by the laminar liquid, and there is no rebound of the liquid, and contamination of the laser optical system can be suppressed. Furthermore, since the laser beam is irradiated through the liquid in a laminar flow state that does not transmit the laser beam to the transparent plate or the like and does not easily affect the focusing of the laser beam, efficient processing can be performed.

In the laser processing apparatus of the present invention, the laser light irradiation mechanism makes the laser light incident obliquely toward the downstream side of the liquid with respect to the liquid flowing on the processing surface.
That is, in this laser processing apparatus, the laser beam irradiation mechanism causes the laser beam to enter the liquid flowing on the processing surface obliquely toward the downstream side of the liquid, so that the processed removal object is directed toward the downstream direction of the liquid. It becomes easy to come out and the removal efficiency by the liquid becomes high.

Further, in the laser processing apparatus of the present invention, the liquid supply mechanism includes a supply nozzle for supplying the liquid onto the processing surface, and the supply nozzle has a long and long opening end along the processing surface. It is characterized by having.
That is, in this laser processing apparatus, since the supply nozzle has a long and long opening end along the processing surface, the liquid is widely supplied to the processing surface from the supply nozzle having a flat opening end. Even if the supply nozzle and the processing point are relatively close to each other, a laminar flow state can be easily obtained, and it can be applied to a small processing object.

Further, in the laser processing apparatus of the present invention, the liquid supply mechanism includes a plurality of supply nozzles for supplying the liquid onto the processing surface, and the plurality of supply nozzles have the opening ends directed in the same direction. It is characterized by being arranged side by side along the processed surface.
That is, in this laser processing apparatus, since the plurality of supply nozzles are arranged with the respective open ends directed in the same direction arranged adjacent to each other along the processing surface, the liquid from each adjacent supply nozzle is integrated. Therefore, it is possible to easily obtain a wide laminar flow state by suppressing the flow rate as compared with the case of one supply nozzle.

The present invention has the following effects.
That is, according to the laser processing apparatus and the laser processing method according to the present invention, the liquid with transparent laser light flows on the processing surface of the processing object in a laminar state along the processing surface, so that the laser transmitting the liquid is transmitted. It is possible to accurately focus the light and to efficiently and efficiently discharge the processed removed material. Therefore, efficient processing can be performed in processing of a substrate, a cutting tool, and a mold.

BRIEF DESCRIPTION OF THE DRAWINGS In 1st Embodiment of the laser processing apparatus and laser processing method which concern on this invention, it is the simple whole block diagram which shows a laser processing apparatus. In 1st Embodiment, it is a top view which shows the supply nozzle which supplies a liquid on a workpiece. In 1st Embodiment, it is an expanded sectional view of the principal part for demonstrating the state at the time of laser processing. In 1st Embodiment, it is a perspective view which shows the front-end | tip part of a supply nozzle. It is a graph which shows the relationship between the incident angle of a laser beam, and the reflectance with respect to water. In 2nd Embodiment of the laser processing apparatus and laser processing method which concern on this invention, it is a top view which shows a supply nozzle.

  Hereinafter, a first embodiment of a laser processing apparatus and a laser processing method according to the present invention will be described with reference to FIGS. 1 to 5. In each drawing used for the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

  As shown in FIGS. 1 to 3, the laser processing apparatus 1 of the present embodiment is an apparatus that processes a workpiece W by irradiating the workpiece W with the laser light L, and irradiates the workpiece W with the laser light L. The laser beam irradiation mechanism 2, the liquid supply mechanism 3 for flowing the liquid F in which the laser beam L is transparent on the processing surface of the processing object W in a laminar state along the processing surface, and the processing object W are held. A movable moving mechanism 4 and a control unit 5 for controlling them are provided.

The workpiece W is, for example, a substrate, a cutting tool, or a mold, and a substrate such as a SiC substrate, or a surface to be processed is formed into a film by a sintered diamond sintered body, a CBN sintered body, or vapor phase synthesis. It is composed of a diamond film or the like.
The moving mechanism 4 includes an X-axis stage portion 4x that can move in the X direction parallel to the horizontal plane, and a moving direction in the Y direction that is provided on the X-axis stage portion 4x and that is perpendicular to the X direction and parallel to the horizontal plane. A Y-axis stage unit 4y and a Z-axis stage unit 4z provided on the Y-axis stage unit 4y and capable of holding the workpiece W and movable in a direction perpendicular to the horizontal plane.

The laser beam irradiation mechanism 2 includes a laser light source 6 having an optical system that oscillates a laser beam L in response to a trigger signal of a Q switch and collects it in a spot shape, a galvano scanner 7 that scans the irradiated laser beam L, and a holding unit. And a CCD camera 8 that captures an image to confirm the processing position of the processed object W.
The laser light source 6 can use laser light with a wavelength of 190 to 550 nm. For example, in the present embodiment, a laser light source that oscillates laser light L with a wavelength of 355 nm is used.

The galvano scanner 7 is disposed immediately above the moving mechanism 4. The CCD camera 8 is installed adjacent to the galvano scanner 7.
As shown in FIG. 3, the laser light irradiation mechanism 2 includes an optical system and a galvano scanner 7 so that the laser light L is incident on the liquid F flowing on the processing surface obliquely toward the downstream side of the liquid F. Is set.
Note that the incident angle θ of the oblique laser beam L is set so that the reflectance of the laser beam on the surface of the liquid F is within 20%. That is, when the laser beam L is incident on the liquid F obliquely, the reflectivity varies depending on the incident angle θ and affects the processing quality. When the reflectivity is set to an angle exceeding 20%, a uniform processing is performed. This is because it becomes difficult. For example, when the liquid F is water, the range of the incident angle θ (an angle at which the reflectance is 20% or less) is 0 to 66 degrees, and when the liquid F is ethanol, the range is 0 to 65 degrees. The relationship between the incident angle θ of the laser light L and the reflectance with respect to water is shown in FIG. The incident angle θ is calculated by setting the angle θ when the laser beam L is irradiated perpendicularly to the processing surface of the workpiece W as 0 degree.

The liquid supply mechanism 3 includes a supply nozzle 9 for supplying the liquid F onto the processing surface. The supply nozzle 9 is connected to a supply source (not shown) of the liquid F and is installed on the workpiece W, and the axis of the nozzle is parallel to the machining surface so that the liquid F flows horizontally on the machining surface. It is arranged in.
The supply nozzle 9 may adopt a single tube having a circular opening end, but as shown in FIGS. 2 and 4, a supply of a rectangular tube having a long long opening end along the processing surface. Nozzle 9 is preferred.
The liquid F is a liquid transparent to the laser light L, and for example, alcohol or pure water is employed.

  In the case where actual processing is performed by the laser processing apparatus 1 of the present embodiment, for example, a case where a SiC substrate is processed as the processing target W will be described.

First, pure water is supplied as liquid F from the supply nozzle 9 at a rate of 10 ml / sec to the processed surface of the SiC substrate. At this time, a pure water film having a laminar flow of 1 mm is generated on the substrate surface. Next, while flowing the liquid F, a laser beam L having a wavelength of 355 nm, an output of 6 W, and a repetition frequency of 60 kHz is scanned at 300 mm / sec. In addition, the incident angle θ of the laser beam L at this time is configured such that the angle formed by the substrate plane and the laser beam L is 33 degrees (the reflectance of the laser beam L is less than 5%).
As a result, conventionally, when processing is repeated in the depth direction, the laser beam is absorbed by scattering of the processed removed material and the processing speed is reduced. In this embodiment, as shown in FIG. Then, the processing removal material is constantly discharged to the downstream side by the liquid F in the laminar flow state, and efficient processing becomes possible.

  Thus, in the laser processing apparatus 1 of this embodiment, since the transparent liquid F flows on the processing surface of the workpiece W in a laminar state along the processing surface, the transparent liquid F that forms a film on the processing surface. The laser beam L that has been transmitted through the workpiece processes the workpiece W, and the generated workpiece removal is steadily discharged from the vicinity of the machining point k by the liquid F serving as the deposit removing liquid. At this time, when the liquid F is simply made to flow on the processing surface, the liquid F becomes a turbulent state and undulates, the condensing of the transmitted laser light L is disturbed, and the image formation (focus) is not accurately aligned. However, in this embodiment, since the liquid F is flowed in an optically stable laminar flow state, the laser beam L can be accurately focused on the processing surface.

  In addition, when the liquid F is in a turbulent state, the flowed work removal may return to the vicinity of the processing point k again, whereas in the present embodiment, the liquid F is flowed in a laminar flow state. The processed removed object does not return near the point k. Therefore, it is possible to remove all the processed removal by the laminar flow state liquid F, and there is no rebound of the liquid F, and contamination of the laser optical system can be suppressed. Furthermore, since the laser beam L is irradiated through the liquid F in a laminar flow state that does not transmit the laser beam L to the transparent plate or the like and does not easily affect the focusing of the laser beam L, efficient processing can be performed. .

Further, since the laser beam irradiation mechanism 2 causes the laser beam L to be incident obliquely toward the downstream side of the liquid F with respect to the liquid F flowing on the processing surface, the processed removal object exits in the downstream direction of the liquid F. It becomes easy and the removal efficiency by the liquid F becomes high.
Further, since the supply nozzle 9 has a long and long opening end along the processing surface, the liquid F is widely supplied to the processing surface from the supply nozzle 9 having a flat opening end, and the supply nozzle 9. Even if the machining point k is relatively close to each other, a laminar flow state can be easily obtained and can be applied to a small workpiece W.

  Next, a second embodiment of the laser processing apparatus and the laser processing method according to the present invention will be described below with reference to FIG. Note that, in the following description of the embodiment, the same components described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that, in the first embodiment, the supply nozzle 9 which is a single rectangular tube is adopted, whereas in the laser processing apparatus of the second embodiment, FIG. 6, the liquid supply mechanism 23 includes a plurality of supply nozzles 29 that supply the liquid F onto the processing surface, and the plurality of supply nozzles 29 have respective opening ends directed in the same direction along the processing surface. It is a point arranged side by side in an adjacent state.

That is, in the second embodiment, the multi-pipe supply nozzles 29 arranged in the same direction are provided, and the liquid F supplied from each supply nozzle 29 merges at the processing point k to form one layer. Make up the flow.
In the laser processing apparatus according to the second embodiment, the plurality of supply nozzles 29 are arranged in such a manner that the respective open ends directed in the same direction are arranged adjacent to each other along the processing surface. A wider laminar flow state can be easily obtained by controlling the flow rate as compared with the case of the single supply nozzle 29 in which the liquid F is integrated.

  In the liquid supply mechanism of each of the above embodiments, the condition for supplying the liquid to the processing surface in a laminar flow state does not exceed the Reynolds number (critical Reynolds number) when the laminar flow transitions to turbulent flow. Is set as follows.

First, in the case of a single tube supply nozzle having a circular opening end, the minimum flow rate required to flow the processed material is 5 ml / min, and the tube inner diameter in this case is a laminar flow of 0.07 mm or more. Is the lower limit. When the pipe inner diameter is increased beyond 5 mmφ, the distance between the processing point k and the supply nozzle must be increased in order to equalize the liquid layer thickness at the processing point k. In practical terms, the maximum pipe inner diameter is 5 mmφ. It becomes. When the inner diameter of the tube is 5 mmφ, the flow rate is proportional to the inner diameter of the tube, and the flow rate can be increased up to 370 ml / min.
The laminar flow conditions at this single tube supply nozzle are shown in Table 1 below.

Next, in the case of a rectangular tube supply nozzle as in the first embodiment, a condition equivalent to the laminar flow condition of a single tube can be applied by setting a circumference equivalent to the cross-sectional area of the single tube. . The advantages of using a rectangular tube are that laminar flow can be applied over a wide range and at an appropriate thickness, the supply nozzle and the processing point k can be relatively close to each other, even for small processing objects. It is mentioned that it is applicable. In addition, when the thickness at the opening of the supply nozzle is d and the width is w, the ratio of d: w is 1:20 and d = 0.1 to 1 mm as conditions. As long as the circumference is equivalent to the above, the present invention is not limited to this and is applicable.
The laminar flow conditions at the supply nozzle of this rectangular tube are shown in Table 2 below.

Further, in the case of a double-tube supply nozzle as in the second embodiment, it is considered as a combination of single tubes, and conditions equivalent to the laminar flow conditions of single tubes can be applied. Advantages of using double pipes include that laminar flow can flow over a wide range with a minimum flow rate, and that the flow rate can be increased by the number of tubes when the pipe inner diameter is optimized. . However, it is necessary to keep a certain distance between the supply nozzle and the processing point k.
The laminar flow conditions at the double-tube supply nozzle are shown in Table 3 below.

  The laser processing apparatus and laser processing method of the present invention are particularly suitable for processing a substrate, a cutting tool, a mold, or the like.

  DESCRIPTION OF SYMBOLS 1 ... Laser processing apparatus, 2 ... Laser beam irradiation mechanism, 3, 23 ... Liquid supply mechanism, 9, 29 ... Supply nozzle, F ... Liquid, L ... Laser beam, W ... Work object

Claims (5)

An apparatus for irradiating a processing object with laser light,
A laser beam irradiation mechanism for irradiating the workpiece with the laser beam;
A laser processing apparatus comprising: a liquid supply mechanism configured to flow a liquid in which the laser light is transparent on a processing surface of the processing object in a laminar state along the processing surface. In the laser processing apparatus of Claim 1,
The laser processing apparatus, wherein the laser beam irradiation mechanism causes the laser beam to be incident obliquely toward the downstream side of the liquid flowing on the processing surface. In the laser processing apparatus according to claim 1 or 2,
The liquid supply mechanism includes a supply nozzle for supplying the liquid onto the processing surface;
The laser processing apparatus, wherein the supply nozzle has an elongated long opening end along the processing surface. In the laser processing apparatus as described in any one of Claim 1 to 3,
The liquid supply mechanism includes a plurality of supply nozzles for supplying the liquid onto the processing surface;
The laser processing apparatus, wherein the plurality of supply nozzles are arranged such that respective open ends directed in the same direction are arranged adjacent to each other along the processing surface. A method of processing by irradiating a processing object with laser light,
Flowing the liquid in which the laser beam is transparent on the processing surface of the processing object in a laminar state along the processing surface;
Irradiating the workpiece with the laser light through the liquid in the laminar flow state.