JP3926503B2 - Laser processing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser beam machine in which a laser beam emitted from a laser oscillator is limited to the size of the window by an aperture having a window.
[0002]
[Prior art]
For example, in a laser drilling machine that drills a printed circuit board with a laser, the diameter of a laser beam emitted from a laser oscillator is adjusted to a predetermined size by an aperture in order to improve processing accuracy and workability. The aperture of such a laser beam machine will be described with reference to FIGS.
FIG. 6 is an overall configuration diagram of an optical system of a conventional laser drilling machine, and FIG. 7 is a cross-sectional view of section A in FIG. In the figure, reference numeral 1 denotes a laser oscillator which outputs a laser beam 2. Reference numerals 3a to 3c denote mirrors. Reference numeral 4 denotes an aperture, which is made of a material such as copper that does not transmit the laser beam 2 and has high thermal conductivity. The aperture 4 includes a window 4a (in this case, a circular through hole having a diameter of about 1 to 8 mm) at a predetermined position, and the side surface 4b on the incident side of the laser beam 2 is formed in a conical surface. The aperture 4 is disposed so that the axis of the window 4 a coincides with the axis of the beam diameter of the laser beam 2. Reference numeral 5 denotes an optical unit composed of a lens or the like, and 6 denotes a printed circuit board.
[0003]
Next, the operation of the conventional laser beam machine will be described.
The laser beam 2 emitted from the laser oscillator 1 is bent at a right angle by the mirrors 3 a and 3 b and enters the aperture 4. The passing beam 2a that has passed through the window 4a is bent at a right angle by the mirror 3c and then condensed by the optical unit 5 to process a hole in the printed circuit board 6. Further, the reflected beam 2b reflected by the side surface 4b is reflected to a place other than the laser oscillator 1 to prevent the laser oscillator from being damaged by the reflected beam 2b. Since the entire laser beam machine is shielded from the surroundings by a cover (not shown), the reflected beam 2b does not leak outside the laser beam machine.
[0004]
Thus, when the beam diameter of the laser beam 2 is adjusted in advance, the height of the optical unit 5 from the surface of the printed circuit board 6 can be fixed even when processing different hole diameters. As a result, not only the hole machining accuracy is improved, but also the workability is improved.
[0005]
[Problems to be solved by the invention]
However, when the aperture 4 is made of copper, most of the reflected beam 2b is reflected by the side surface 4b, and the power does not decay. Further, the reflected beam 2b has high directivity. For this reason, although it depends on the laser output, the portion of the laser beam machine where the reflected beam 2b is incident is gradually heated and may reach 150 degrees C locally. For example, if the heated part is the holding part of the mirror 3b, the position of the mirror 3b is shifted due to thermal deformation of the holding part, the optical axis of the laser beam 2 is inclined, and the processing energy supplied to the processing part is increased. As a result, the desired processing cannot be performed.
[0006]
An object of the present invention is to solve the above-described problems in the prior art and provide a laser beam machine capable of appropriately processing a laser beam reflected by an aperture.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a laser beam machine in which a laser beam emitted from a laser oscillator is limited to a size of the window by an aperture having a window, and the laser beam of the aperture is provided. A side surface on the incident side is formed in a conical surface inclined at an angle θ (90 °> θ ≧ 45 °) from the outer edge of the window toward the outer peripheral direction toward the downstream side in the laser beam incident direction. It is cylindrical, and its inner surface is made of a blackened material with low reflectivity, and when the aperture is mounted in the cover, the window of the aperture from the end on the most upstream side in the laser beam incident direction of the cover The length along the optical axis of the laser beam at the position of L is L, the inner diameter of the cover is D, the diameter of the incident laser beam is K, and the minimum diameter of the window is d. When,
D> K
Where L> (D−d) / 2 tan 2θ expressed by the angle θ.
The laser beam reflected by the aperture is irradiated onto the inner surface of the cover so that the center of the window coincides with the center of the laser beam.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiments.
1 is an overall configuration diagram of an optical system of a laser beam machine according to the present invention, FIG. 2 is a view as viewed from B in FIG. 1, FIG. 3 is a cross-sectional view taken along a line CC in FIG. 6 having the same function or the same function as those in FIGS. In the figure, reference numerals 10 and 11 denote apertures. As shown in FIG. 4, the side surface 10b on the incident side of the laser beam 2 is formed as a conical surface at an angle θ (θ = 75 degrees in the figure) from the outer edge of the window 10a. Is formed. The apertures 10 and 11 are different in the axial lengths of the windows 10a and 11a and the side surfaces 10b and 11b, but the other dimensions (the outer diameter, the length of the male screw 12, the angle θ, etc.) are the same. Reference numeral 13 denotes a cylindrical cover, which is formed of a material having a low reflectivity, for example, carbon, and has an internal thread 14 that is engaged with the external thread 12 at one inner end. The cover 13 is inserted from one side of the holder 15 so as to be in close contact with the holder 15, and is fixed to the holder 15 by means not shown. Reference numeral 16 denotes a cooling water passage penetrating the holder 15, and is connected via a connection terminal 17 to a cooling water circulation device (not shown). Reference numeral 18 denotes a support which is integral with the holder 15 and is fixed to the piston 21 of the air cylinder 20 by a bolt 19.
[0010]
Next, the dimension of each part is demonstrated.
The covering length L of the cover 13, that is, the distance from the end M of the cover 13 to the end N of the window 10 a when the aperture 10 is screwed to the cover 13, the inner diameter D of the cover 13, and the diameter of the laser beam 2. There is a relationship of the following formulas 1-3 between K, the minimum diameter d of the window 10a, and the angle θ.
(1) D> K Formula 1
(2) L> (D−d) / 2 · tan 2θ Equation 2
(3) 90> θ ≧ 45 Equation 3
Next, the operation of the present embodiment will be described.
The air cylinder 20 is operated in advance, and the center of one of the window 10a and the window 11a (here, the window 10a) is positioned so as to coincide with the center of the laser beam 2. The laser beam 2 emitted from the laser oscillator 1 is bent at right angles by the mirrors 3 a and 3 b and enters the aperture 10. The passing beam 2a that has passed through the window 10a is bent at a right angle by the mirror 3c and then condensed by the optical unit 5 to process a hole in the printed circuit board 6.
[0011]
On the other hand, as shown in FIG. 4, the reflected beam 2b is also incident on the inner surface of the cover 13 as reflected by the end N of the window 10a which is the most central side, as shown in FIG. It is absorbed by the cover 13 and turns into heat. Since the cover 13 is fixed in close contact with the water-cooled holder 15, the temperature hardly rises. Further, since the aperture 10 is also cooled through the female screw 14, the temperature rise value is small, and the diameter of the window 10a does not expand due to heat.
[0012]
In the above description, the entire cover 13 is made of carbon. However, for example, the holder 15 may be made of copper, and cylindrical carbon may be press-fitted or bonded to a portion irradiated with the reflected beam 2b. Further, the cover 13 and the holder 15 may be made of integral copper, and the inner surface may be blackened, or the inner surface may be made of iron and the iron trioxide film may be treated.
[0013]
In the above embodiment, the number of apertures is two. However, a large number of apertures having different window diameters are prepared and held by the switching means, and the center of the window is aligned with the axis of the laser beam. Then, the kind of hole diameter which can be processed can be increased further.
[0014]
Further, the angle θ is set to 90> θ ≧ 45. However, when the covering length L can be increased, the aperture 10 can be increased by increasing θ as much as possible to increase the axial thickness of the window 10a. Can extend the lifetime of
[0015]
FIG. 5 is a diagram showing another embodiment of the present invention and corresponds to FIG. 4 described above. In the figure, reference numeral 30 denotes an air nozzle, which is fixed to the cover 13, and the end 30a is connected to a compressed air source (not shown). In this embodiment, since the cover 13 and the aperture 10 are cooled by air, the apparatus configuration is simplified.
[0016]
【The invention's effect】
As described above, according to the present invention, since the record Zabimu reflected by the aperture so as to irradiate the cover all the cylindrical inner surface, it is possible to reliably absorb the reflected beam, this result, the laser beam It is possible to prevent the occurrence of the optical axis deviation and the deformation of the components in the laser processing machine.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an optical system of a laser beam machine according to the present invention.
FIG. 2 is a view as seen from B in FIG.
FIG. 3 is a cross-sectional view taken along the line CC of FIG.
4 is an enlarged view of a portion D in FIG. 3;
FIG. 5 is a diagram showing another embodiment of the present invention.
FIG. 6 is an overall configuration diagram of an optical system of a conventional laser drilling machine.
7 is an enlarged view of a part A in FIG. 6;
[Explanation of symbols]
2 Laser beam 2b Reflected beam 10 Aperture 10b Side surface 13 Cover

Claims (1)

In a laser processing machine in which a laser beam emitted from a laser oscillator is limited to the size of the window by an aperture having a window,
The side surface of the aperture on the laser beam incident side is formed as a conical surface inclined at an angle θ (90 °> θ ≧ 45 °) with respect to the downstream side of the laser beam incident direction from the outer edge of the window toward the outer periphery.
The cover containing the aperture has a cylindrical shape, and its inner surface is made of a blackened material with a low reflectivity, and when the aperture is mounted in the cover, the laser beam incident direction most upstream side of the cover L is the length along the optical axis of the laser beam from the end of the aperture along the optical axis of the laser beam, D is the inner diameter of the cover, K is the diameter of the incident laser beam, and d is the minimum diameter of the window. When
D> K
Where L> (D−d) / 2 tan 2θ expressed by the angle θ.
The laser processing machine is characterized in that the laser beam is formed to have a size satisfying the above condition, coincides with the center of the window and the center of the laser beam, and irradiates the inner surface of the cover with the laser beam reflected by the aperture.

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