JP2009119480A - Laser beam machining method and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining method and an apparatus therefor which are suitable to when forming a grooves on a material to be machined and to such a working as the removal of a coating film coated on a material to be machined by making so that uniform strength distribution is obtained in a liquid column while preventing energy loss as small as possible. <P>SOLUTION: This laser beam machining apparatus is made so that required machining is performed to the material to be machined by jetting liquid toward the material 2 to be machined from a jetting nozzle by making the liquid into the liquid column W and emitting a laser beam L by introducing the laser beam into the liquid column by taking the liquid column as a light guide. The optical axis of the laser beam L is set by shifting within the range D of 1/5 to 1/10 of the nozzle diameter from the center line O of the jetting nozzle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser processing method and an apparatus therefor, and more specifically, ejects a liquid column from a spray nozzle toward a workpiece, and uses the liquid column as a light guide to pass laser light to the workpiece. The present invention relates to a laser processing method and an apparatus for irradiating and performing a required processing on a workpiece.

As a conventional laser processing apparatus, a liquid supply means that ejects liquid from an ejection nozzle as a liquid column, a laser oscillator that oscillates laser light, and guides the laser light from the laser oscillator into the liquid column as a light guide. An optical guide means for ejecting the liquid from the spray nozzle toward the work piece as a liquid column and irradiating the work piece with laser light that has passed through the liquid column. The thing which performed the process of this is known (patent document 1, patent document 2).
In the conventional laser processing apparatus, the center line of the spray nozzle, that is, the axis of the liquid column ejected from the spray nozzle is aligned with the optical axis of the laser beam passing through the liquid column. That is, by aligning the axial center of the liquid flow with the optical axis of the laser light, the amount of leakage of laser light from the liquid flow to the outside is minimized to suppress energy loss.
JP 2005-288472 A JP 2006-255768 A

As shown in FIG. 8, when the axial center of the liquid column W and the optical axis of the laser beam L coincide with each other, energy loss can be minimized, but the laser in the liquid column W at that time can be minimized. The intensity distribution of the light L is a mountain-shaped intensity distribution with a strong central part and a weak peripheral part.
Such an intensity distribution is suitable for cutting the workpiece 2 because the peak in the intensity distribution of the laser beam L is large. However, when a groove is formed in the workpiece 2 or in the workpiece 2. It was unsuitable for processing that removes the coated film (not shown).
In view of such circumstances, the present invention provides a uniform strength distribution in the liquid column while preventing energy loss as much as possible, thereby forming a groove on the workpiece or covering the workpiece. The present invention provides a laser processing method and apparatus suitable for processing that removes a coating film coated on a workpiece.

That is, in the processing method of claim 1, the liquid is ejected from the ejection nozzle toward the workpiece as a liquid column, and laser light is introduced into the liquid column using the liquid column as a light guide path. In the laser processing method that irradiates the workpiece and performs the required processing on the workpiece,
The optical axis of the laser beam is set to be shifted from the center line of the injection nozzle within a range of 1/5 to 1/10 of the nozzle diameter.
According to a second aspect of the present invention, there is provided a processing apparatus comprising: a liquid supply means that ejects liquid from an ejection nozzle as a liquid column; a laser oscillator that oscillates laser light; and the liquid column that uses the laser light from the laser oscillator as a light guide. And an optical guide means for guiding the workpiece to the workpiece by jetting the liquid from the jet nozzle toward the workpiece as a liquid column and irradiating the workpiece with laser light that has passed through the liquid column. In the laser processing equipment that performs the required processing on
The optical guiding means is characterized in that the optical axis of the laser beam is set so as to be shifted within a range of 1/5 to 1/10 of the nozzle diameter from the center line of the injection nozzle.

  According to the present invention, the optical axis of the laser beam is set so as to be shifted within the range of 1/5 to 1/10 of the nozzle diameter from the center line of the injection nozzle. Energy loss can be prevented as much as possible, and a uniform strength distribution can be obtained in the liquid column, so that processing to form grooves in the workpiece and removal of the coating film on the workpiece are removed. Such processing can be performed efficiently.

The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a laser processing apparatus 1 guides a laser beam L to a liquid column W formed by jetting a liquid, thereby performing a required processing on a workpiece 2. Be able to.
The laser processing apparatus 1 includes a processing table 3 that supports the workpiece 2, a laser oscillator 4 that oscillates laser light L, a high-pressure pump 5 that serves as a liquid supply unit that supplies a liquid such as water, and a workpiece. A processing head 6 for injecting a liquid as a liquid column W toward the object 2 and guiding the laser beam L to the liquid column W is provided.
The processing table 3 is conventionally known and will not be described in detail. However, the workpiece 2 is moved in the horizontal direction with respect to the processing head 6, and the processing head 6 is not shown. It is intended to move vertically.
In the present embodiment, the laser oscillator 4 is a YAG laser, can perform CW oscillation or pulse oscillation according to processing, and can appropriately adjust its output and pulse oscillation period.
In addition to this, a semiconductor laser, a CO ₂ laser, or the like can be used as the laser oscillator 4. However, when the laser light L irradiated has a wavelength that is easily absorbed by water, such as a CO ₂ laser. The liquid ejected from the processing head 6 may be a liquid that does not absorb the laser light L.

Next, the processing head 6 will be described. The processing head 6 is supplied from a flat frame 11 fixed to a lifting means (not shown), a condensing lens 12 for condensing the laser light L, and the high-pressure pump 5. In addition to ejecting the liquid as a liquid column W, the ejection nozzle 13 that guides the laser light L to the liquid column W, and the optical guide means 14 that adjusts the relative position and angle of the condenser lens 12 and the ejection nozzle 13. And.
In FIG. 1, a cross-sectional view on the lower side of the drawing (below a sixth plate 41 described later) is a cross-sectional view taken along the line II in FIG.
The frame 11 is provided on the optical axis of the laser beam L oscillated by the laser oscillator 4, and a circular through hole 11a is formed at a position where the optical axis of the laser beam L passes.
The condenser lens 12 is disposed on the optical axis of the laser beam L, and is held at the lower end of a cylindrical lens holder 21. The lens holder 21 is attached via a substantially cross-shaped (see FIG. 2) mounting stay 22. Are fixed to the lower surface of the frame 11.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, but for the sake of explanation, the following second holding cylinder 28 b is not shown.
The ejection nozzle 13 is also arranged on the optical axis of the laser beam L. The ejection nozzle 13 is held at the lower end of a cylindrical nozzle holder 23 and the nozzle holder 23 is moved by the optical guide means 14. It has come to be.

FIG. 3 is an enlarged view of the injection nozzle 13 and the nozzle holder 23. A small diameter portion 23a, a medium diameter portion 23b, and a large diameter portion 23c are formed on the nozzle holder 23 in this order from the workpiece 2 side. The nozzle 13 is fixed to the lower end of the small diameter portion 23a using a ring-shaped holding member 24.
The injection nozzle 13 is made of stainless steel, and an injection hole 13 a is formed at the center of the injection nozzle 13. The injection hole 13 a has a first inclined surface 13 b that decreases in diameter toward the workpiece 2, and the first A second inclined surface 13c that is formed closer to the workpiece 2 than the inclined surface 13b and expands toward the workpiece 2 is formed.
The first inclined surface 13b and the second inclined surface 13c are connected by a minimum diameter portion 13d (FIG. 6), and the first inclined surface 13b is subjected to mirror finishing for reflecting the laser light L. Has been.
The angle of the first inclined surface 13b is set to be larger than the cone angle of the laser light L condensed by the condenser lens 12.

A glass plate 26 is fitted into the middle diameter portion 23b of the injection nozzle holder 23 via a seal member 25, and this glass plate 26 is screwed into a screw portion processed on the inner peripheral surface of the middle diameter portion 23b. It is fixed by a nut 27.
Further, at the position of the small diameter portion 23a, four connection ports 23d are formed at equal intervals on a concentric circle centering on the small diameter portion 23a, and the connection ports 23d communicate with the small diameter portion 23a through the liquid passage 23e. The liquid fed by the high-pressure pump 5 is supplied into the small-diameter portion 23 a below the glass plate 26.
A through hole having a diameter larger than that of the second inclined surface 13c is provided in the center of the holding member 24. The through hole is a liquid column ejected from the injection nozzle 13 together with the second inclined surface 13c. An air pocket P surrounding W is formed.

The optical guiding means 14 includes a holding cylinder 28 that holds the nozzle holder 23, an XY axis stage 29 that moves the holding cylinder 28 in the horizontal direction, and a Z axis stage 30 that moves the XY axis stage 29 in the vertical direction. And an angle adjustment stage 31 for changing the angle of the Z-axis stage 30.
The holding cylinder 28 includes a cylindrical first holding cylinder 28a and a second holding cylinder 28b. The first holding cylinder 28a is fixed to the XY axis stage 29, and the lower end of the second holding cylinder 28b The nozzle holder 23 is fixed. The central axis of the injection hole 13a in the injection nozzle 13 and the central axes of the first and second holding cylinders 28a and 28b are made to coincide with each other.
The lens holder 21 is accommodated inside the second holding cylinder 28b so as not to contact each other. The first holding cylinder 28a and the second holding cylinder 28b fix the lens holder 21 to the frame 11. The four connecting members 32 (see FIG. 2) are connected so as not to interfere with the mounting stays 22.

The XY axis stage 29 includes a first plate 33 that fixes the first holding cylinder 28a, a second plate 34 that holds the first plate 33 from below, and a third plate 35 that holds the second plate 34 from below. And micrometers 36 and 37 for moving the first holding cylinder 28a in the X-axis direction in the horizontal direction in the figure and the Y-axis direction in the depth direction in the figure.
Through holes 33a to 35a are formed at the centers of the first to third plates 33 to 35, respectively, and the through holes 33a of the first plate 33 are fixed by fixing members 33b fixed to the upper surface of the first plate 33. The first holding cylinder 28a is fixed so as to hang down.
As shown in FIG. 4, the first to third plates 33 to 35 have a substantially square shape in plan view, and are disposed so that the side surfaces thereof face the X-axis direction and the Y-axis direction, respectively.
Further, the first plate 33 and the second plate 34 are moved relative to each other in the X-axis direction by a rail (not shown) formed in the X-axis direction, and the second plate 34 and the third plate 35 are moved in the Y-axis direction. The rail 35b (see FIG. 1) formed on the Y-axis moves relative to each other.
The micrometers 36 and 37 are fixed to the side surfaces of the second plate 34 in the X-axis direction and the Y-axis direction, respectively, and the projections 33c are formed on the side surfaces of the first plate 33 at positions that can be pressed by the micrometer 36. On the side surface of the third plate 35, a projection 35c is provided at a position that can be pressed by the tip of the micrometer 37.
With such a configuration, the nozzle holder 23 can be moved together with the holding cylinder 28 and the first plate 33 in the X-axis direction by pressing the projection 33c with the micrometer 36 facing the X-axis direction. By operating the micrometer 37 facing the axial direction, the nozzle holder 23 can be moved in the Y-axis direction together with the holding cylinder 28 and the first and second plates 33 and 34.

The Z-axis stage 30 has a fourth plate 38 for fixing the third plate 35 on its upper surface, a fifth plate 39 fixed on the upper surface of the angle adjusting stage 31, and fourth and fifth plates 38, 39. There are two handles 40 provided between them, and through holes 38a and 39a are formed in the center of the fourth and fifth plates 38 and 39 in a range not contacting the moving first holding cylinder 28a.
Here, the handle 40 raises and lowers the fourth plate 38 by a conventionally known jack screw system, and detailed description of the configuration is omitted.
According to the Z-axis stage 30, the fourth plate 38 is moved up and down while maintaining parallel to the fifth plate 39 by operating any one of the handles 40, and the nozzle holder 23 is held in the holding cylinder 28. The XY axis stage 29 can be moved up and down.

The angle adjustment stage 31 has a sixth plate 41 that fixes the Z-axis stage 30 on the upper surface thereof, a fulcrum bolt 42 that passes through the frame 11 and holds the sixth plate 41 from below at the tip thereof, 6 plate 41 is provided with two adjusting bolts 43 (see FIG. 5) for holding from below.
As shown in FIG. 2, the sixth plate 41 has a substantially square shape, and the fulcrum bolt 42 supports any one of the four corners of the sixth plate 41 from the lower surface. The adjustment bolt 43 is configured to support a corner portion at a position sandwiching the fulcrum bolt 42 from the lower surface.
As shown in FIG. 5, the distal ends of the fulcrum bolt 42 and the adjustment bolt 43 are processed into a hemispherical shape, and the distal ends thereof are accommodated in the recesses 44 a of the receiving member 44 embedded in the sixth plate 41. .
The adjustment bolt 43 can be moved up and down by a dial 43 a located on the lower surface side of the frame 11. By using these two adjustment bolts 43, the sixth plate 41 can be moved. Can be changed with respect to the frame 11.
That is, the tilt of the nozzle holder 23 with respect to the frame 11 can be adjusted by the two adjusting bolts 43 together with the holding cylinder 28, the XY axis stage 29, and the Z axis stage 30.
According to the optical guide means 14 having such a configuration, the XY axis stage 29 and the angle adjustment stage 31 are used to inject from the injection nozzle 13 with respect to the optical axis of the laser light L irradiated from the laser oscillator 4. The position and angle of the liquid column W can be adjusted, and by using the Z-axis stage 30, the focal position of the laser light L condensed by the condenser lens 12 can be adjusted along the direction of the liquid column W. Can be moved.

FIG. 6 shows an enlarged view of the injection nozzle 13. In this figure, the optical axis of the laser light L is injected from the injection nozzle 13 by the XY axis stage 29 and the angle adjustment stage 31 of the optical guide means 14. It is set so as to be shifted within a range D of 1/5 to 1/10 of the nozzle diameter from the central axis of the liquid column W, that is, the center line O of the injection nozzle 13.
When a liquid is supplied into the nozzle holder 23 by the high-pressure pump 5 in this state, the liquid passes through the small-diameter portion 23a (FIG. 3) of the nozzle holder 23 and enters the workpiece 2 from the injection hole 13a of the injection nozzle 13. It is injected towards.
At this time, since the air pocket P is formed in the lower part of the first inclined surface 13b by the second inclined surface 13c and the through hole of the holding member 24, the injected liquid does not diffuse and the first inclined surface The liquid column W having the same diameter as that of the minimum diameter portion 13d of 13b is ejected.
Next, when the laser light L is oscillated from the laser oscillator 4, the laser light L is condensed by the condenser lens 12, and then the liquid filling the small diameter portion 23 a of the glass plate 26 and the nozzle holder 23. Is transmitted to the spray nozzle 13.
In the present embodiment, by adjusting the Z-axis stage 30, the focal point of the laser beam L is located in the liquid column W beyond the minimum diameter portion 13d of the first inclined surface 13b, and the laser beam L is The light is condensed smaller than the maximum diameter portion 13e of the injection hole 13a.
FIG. 6 shows the focal point f of the laser light L when there is no ejection nozzle 13 by a broken line.
The laser beam L thus collected is shielded by the first inclined surface 13b at a portion outside the minimum diameter portion 13d, and the portion is reflected by the first inclined surface 13b. The light is guided to the workpiece 2 using the liquid column W as a light guide path while repeating reflection at an incident angle larger than the critical angle at the boundary surface with the outside air at W.

Incidentally, as described above, conventionally, as shown in FIG. 8, since the axis of the liquid column W and the optical axis of the laser beam L coincide with each other, the intensity distribution of the laser beam L in the liquid column W has a central portion. However, the intensity distribution of the cross-sectional mountain shape was weak and the periphery was weak.
However, in this embodiment, as shown in FIG. 6, the optical axis of the laser beam L is set to be shifted from the center line O of the injection nozzle 13 within a range D of 1/5 to 1/10 of the nozzle diameter. Therefore, as shown in FIG. 7, the intensity distribution of the laser beam L in the liquid column can be obtained as a trapezoidal uniform intensity distribution from the center to the periphery. Therefore, this makes it possible to efficiently perform a process for forming a groove in the work piece 2 and a process for removing the film coated on the work piece.
On the other hand, when the optical axis of the laser beam L is largely shifted from the center line O of the injection nozzle 13 by more than 1/5 of the nozzle diameter, as shown in FIG. 9, the laser beam L in the liquid column The intensity distribution is disturbed, and the energy loss of laser light increases.
In this way, by displacing the optical axis of the laser beam L within the range of 1/5 to 1/10 of the nozzle diameter from the center line of the injection nozzle 13, the energy loss of the laser beam is prevented as much as possible. At the same time, a uniform intensity distribution can be obtained in the liquid column W.
As a specific example, when the diameter of the minimum diameter portion 13d of the injection nozzle 13 is 100 μm, the range D to be shifted is preferably 10 to 20 μm. When the range to be shifted is less than 10 μm, a uniform intensity distribution is obtained. It becomes difficult to obtain, and when it exceeds 20 μm, energy loss increases.

Sectional drawing of the laser processing apparatus in this invention. The top view in the II-II cross section of FIG. Sectional drawing about an injection nozzle and a nozzle holder. The top view about an XY-axis stage. Sectional drawing in the VV cross section of FIG. The expanded sectional view about an injection nozzle. Explanatory drawing explaining the intensity distribution of energy at the time of setting the optical axis of the laser beam L by shifting within the range D of 1/5 to 1/10 of the nozzle diameter from the center line O of the injection nozzle. Explanatory drawing explaining the intensity distribution of energy at the time of making the optical axis of the laser beam L correspond to the centerline O of an injection nozzle. Explanatory drawing explaining the intensity distribution of energy at the time of setting the optical axis of the laser beam L shifted from the centerline O of an injection nozzle over 1/5 of a nozzle diameter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 2 Workpiece 4 Laser oscillator 5 High pressure pump (liquid supply apparatus)
6 Processing Head 13 Injection Nozzle 13a Injection Hole 13d Minimum Diameter Part 14 Optical Guide Means D Setting Range L Laser Light O Center Line of Injection Nozzle W Liquid Column

Claims (2)

The liquid is ejected from the ejection nozzle toward the workpiece as a liquid column, and the liquid column is guided to the workpiece by irradiating the workpiece with a laser beam. In the laser processing method in which the processing of
A laser processing method, wherein the optical axis of the laser beam is set to be shifted within a range of 1/5 to 1/10 of the nozzle diameter from the center line of the injection nozzle. Liquid supply means for ejecting liquid from the ejection nozzle as a liquid column, a laser oscillator for oscillating laser light, and optical guide means for guiding laser light from the laser oscillator into the liquid column as a light guide A laser processing apparatus that performs a required processing on a workpiece by irradiating the workpiece with a laser beam that is sprayed from the spray nozzle toward the workpiece as a liquid column and passes through the liquid column. In
The laser processing apparatus, wherein the optical guiding means is set by shifting the optical axis of the laser beam within a range of 1/5 to 1/10 of the nozzle diameter from the center line of the injection nozzle.

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