JP2604001Y2 - Laser light absorption device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam absorbing device for absorbing a high-energy laser beam in the processing optical path.

[0002]

2. Description of the Related Art Generally, in a laser processing apparatus,
In order to check the oscillation state of the laser beam and the processing state,
In some cases, the user does not want the laser light to enter the processing optical path for a desired time. To cope with this, a laser light absorbing device for absorbing the laser light in the optical path from the laser oscillator to the processing position is used. Conventionally, as this type of laser light absorbing device, for example, Japanese Utility Model Publication No. 60-3072
There is an absorption device described in Japanese Patent Publication No.

That is, as shown in FIG. 3, a cylindrical body 2 whose inner peripheral surface is made into an absorbing surface for absorbing laser light, for example, a black alumite-treated absorbing surface 2a for absorbing laser light L, Cooling water passages 6a to 6f formed in the peripheral wall of the body 2 along the axial direction; a plate-shaped body 3 provided at one open end of the cylindrical body 2 so as to close the opening; A conical body 9 is provided on one plate surface of the body 3 so as to protrude into the cylindrical body 2 and has a surface formed on a reflecting surface 9a for reflecting a laser beam, for example, made of copper or the like, and has a mirror-finished surface 9a. The laser beam absorbing device 1 is constituted by the conical body 9 formed at an acute angle at the tip.

In this laser beam absorbing device, when the laser beam L is made incident on the absorbing device 1, the laser beam L is reflected by the reflecting surface 9a of the conical body 9 and is formed on the inner peripheral surface of the cylindrical body 2. Absorbed at 2a. And this absorbing surface 2
A part of the laser light L reflected without being completely absorbed by a is reflected by the reflection surface 9a again and absorbed by the absorption surface 2a. This state is repeated, and almost all of the laser light L is absorbed. Further, it is disclosed that since the cylindrical body 2 is cooled by the cooling water, the cylindrical body 2 is not melted by red heat even when the laser beam L is absorbed by the absorbing surface 2a.

[0005]

[Problem to be solved by the invention]
As shown in FIG. 3, the laser beam absorbing device disclosed in Japanese Patent No. 30721 uses a cone 9 made of copper or the like, having a mirror-finished surface 9a, and having an apex angle of 45 degrees or less.
In the case where the apex angle of the cone is an acute angle, the laser beam X is reflected by the reflection surface 9a of the cone 9 and the absorption by the absorption surface 2a on the inner periphery of the cylinder 2 a plurality of times as shown in FIG. Proceeding in _two directions, the energy of the laser light is absorbed. When the mirror surface 9a of the cone 9 is new, the reflectance of the laser beam is as high as 99% or more and the heat absorption to the cone 9 is small, so that there is almost no problem.

However, as the laser light absorbing operation is repeatedly performed, the mirror surface 9a that reflects the laser light L is gradually oxidized, and the reflectance of the laser light L decreases.
That is, the absorptance of the laser beam L to the cone 9 increases. Further, since the laser beam is applied to the cone 9 a plurality of times, the temperature of the cone 9 increases more and more, the oxidation of copper is further promoted, and the absorptivity of the laser light to the cone 9 further increases.

Since the heat radiation by heat conduction is insufficient in the vicinity of the top of the cone 9, the vicinity of the top of the cone 9 becomes high temperature and deteriorates as the absorptance of the laser light to the cone 9 increases. You. For this reason, in order to make the work of absorbing laser light into a desired state, it was necessary to replace the cone 9 with a new one at a relatively short cycle.

Further, as shown in FIG. 4, if the top of the cone 9 is located slightly inside the open end 2b of the cylindrical body, the laser beam L is depleted as the vicinity of the top of the cone 9 deteriorates.
There was a possibility that the light was irregularly reflected near the top and leaked out of the apparatus. To prevent this, it is necessary to lengthen the cylindrical body 2 in the X ₁ direction, apparatus becomes large in size, and has been a high cost.

Furthermore, since the laser beam travels in the direction of the bottom of the cone 9, that is, in the X ₂ direction while repeating reflection and absorption, the outer shape of the bottom of the cone 9 is made substantially equal to the inner diameter of the cylinder 2. As a result, the cone 9 was large and costly.

Generally, as the energy of the laser beam increases, the number of times that the laser beam reaches the absorption surface 2a of the cylindrical body 2, that is, the number of times of reflection of the cone 9 by the reflection surface 9a, needs to be increased. For this reason, in order to increase the number of reflections as the energy becomes higher, the conical body 9 and the cylindrical body 2 must be formed longer in the long axis direction, and it is particularly difficult to manufacture the conical body 9 having a long reflecting mirror surface. And the cost was high.

The present invention has been made in view of the above-mentioned problem, and has as its object that the cone is hardly deteriorated even with high-energy laser light, and can be used for a long time with desired performance. Another object of the present invention is to provide an inexpensive and small laser light absorbing device.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a cylindrical member having an absorbing surface formed on an inner peripheral surface thereof is provided with a member for absorbing a laser beam, and one opening of the cylindrical member is closed. And a conical body having a laser light reflecting surface on the surface. The feature is that, on the cone, a reflective coating layer is formed by applying a non-oxidizable reflective coating layer, and the apex angle of the reflective surface is made obtuse, and the cylindrical body is formed to be long, The distance between the top of the cone and the open end of the cylinder is made as long as possible, and a cooling passage for cooling the cone and the cylinder is provided.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. In FIG. 1, 21 is made of, for example, aluminum, copper, or the like, and the inner peripheral surface thereof is subjected to a laser light absorbing member, for example, black alumite treatment,
The inner peripheral surface is a cylindrical body formed on the absorption surface 21a, and the cylindrical body 21 is provided with a cooling passage 24 along the peripheral wall of the inner peripheral surface.

For example, the cylindrical body 21 is formed by coaxially fitting an inner cylindrical member 22 and an outer cylindrical member 23 having a spiral cooling passage 24b on the inner surface. and in X ₁ direction of the end portion of the outer tubular member 22 are integrally formed by a fixed or brazing or welding through the sealing agent.

The cooling passage 24 of the cylindrical body 21
A passage 24a that opens in _two directions and a spiral passage 24b
And the fluid connection port 24c are formed so as to communicate with each other. 31 is a coaxially projecting been apex angle obtuse cone toward the X ₁ direction from the X ₂ direction to the cylindrical body 21, the flame oxidation of the reflective coating layer on the conical surface, for example, a coating layer of gold To form the reflection surface 31a. Further, the top of the cone 31 is provided sufficiently intruded located X ₂ direction with respect to the open end of the cylindrical body 21. The cone 31 has a cooling passage 34 along the conical surface.
Are arranged.

For example, the conical body 31 includes an inner conical body 32 having a helical cooling passage 34d on a conical surface,
It is formed by a cap-shaped conical body 33 formed of, for example, aluminum or copper or the like, which is perfectly fitted to the outer side of the inner conical body 32 to form a conical surface similar to that of the inner conical body 32. This cone 31 is, for example,
5, 35 ... are integrally supported by the cylindrical body 21. The cooling passage 34 of the conical body 31 is formed by connecting a fluid connection port 34a, a passage 34b, a top passage 34c, and a spiral passage 34d. The conical body 31 and the cylindrical body 21 are supported in a liquid-tight manner with respect to a cooling fluid, for example, cooling water via an appropriate sealing member, for example, an O-ring. The cooling passage 24 of the cylindrical body 21 is in fluid communication with the cooling passage 24. The laser beam absorbing device 40 is constituted by the cylindrical body 21, the conical body 31, and the cooling passages 24 and 34 for cooling the cylindrical body 21 and the conical body 31, respectively.

In the laser light absorbing device 40, for example, a cooling water hose is connected to the connection ports 34a and 24c,
The laser light is absorbed while flowing through the cooling passages 34 and 24. That is, when a high-energy laser beam L having a cross section having a diameter D is incident on the absorption device 40, the laser beam is reflected by the reflection surface 31 a of the cone 31.

In FIG. 2, the apex angle of the cone is α, the vertex is A ₀ , the incident line (= horizontal line) of the laser beam is L, the reflection surface of the conical surface of the cone 31 is A ₁ , and the cylindrical body 21 is The reflection points on the inner surface of B ₁ , B ₂ , B ₃ ,.
…, The moving distance of the reflection point in the X direction B ₁ B ₂ = B ₂ B ₃ =…
..., F is the diameter of the laser beam, and E is the inner diameter of the cylindrical body 21. Here, since α> 90 degrees, the cone 31
The laser light reflected by the laser beam travels from A _{1 to} B ₁ . That is, the light is reflected from the point A _{1 in the} X ₁ direction. In this case, if the inner diameter E is selected to an appropriate value, the laser light reflected on the inner peripheral surface of the cylindrical body 21 does not hit the cone 31, so that B ₁ → B ₂ → B ₃ →. Going forward, the following relationship holds.

Angle A ₁ B ₁ B ₂ = angle B ₁ B ₂ B ₃ =... = 2 × (α−90 °) (1) F = E × tan (angle A ₁ B ₁ B ₂ / 2) = E × tan (angle _{B 1 B 2 B 3/2} ) = ......... = E × tan (α over 90 °) .......................................... (2)

Of course, in equation (2), the apex angle α of the cone
As much as possible, the number of reflections on the absorbing surface, that is, the number of laser light absorptions, can be increased for a cylinder of a fixed length by reducing the inner diameter E to as close as possible to 90 degrees. In other words, when the number of times of absorption of laser light is set to a desired number, the length of the cylindrical body 21 can be made as short as possible. Thus, the laser beam points B ₁ sequentially reflected while absorbing surface 21a to the inner peripheral surface side of the X ₁ direction of the cylindrical body 21, B _2, B _3, is absorbed in the vicinity of ....

By the way, the reflection surface 31a is set at 1 to the axis.
Although a flat plate inclined in the direction can be considered, it is not preferable for the following reasons. That is, the reflection surface 31a is
If the conical shape is applied, the laser power per unit area, that is, the power density, is lower than that of a flat reflecting surface. For example, output 1000 W, beam diameter 20
When a laser beam having a vertex angle of 100 mm is applied to the reflecting surface, the power density of the cone having a vertex angle of 100 degrees is 2.44.
W / mm ² , whereas 3.1 for the inclined flat plate
8 W / mm ² . Since the power density of the flat plate with the inclined reflecting surface is 30% higher than that of the conical one, the coating on the reflecting surface will peel off and the reflecting surface will deteriorate due to high temperature. I do.

Further, the laser light reflected by the cone 31 is applied to the entire circumference of the inner peripheral surface of the cylindrical body 21 (that is, 360 degrees).
, The power density at the circumferential surface is significantly reduced. However, in the case of a flat plate with an inclined reflecting surface, the reflected laser light is concentrated at a single point on the circumference without being dispersed, so that the processing applied to the inner peripheral surface, for example, black alumite processing Peeling and deterioration of the inner peripheral surface due to high temperature occur.

As described above, a flat plate having an inclined reflecting surface cannot be used. However, a conical reflecting surface having a conical shape allows the reflecting surface 31a even if a high-energy laser beam is incident for a long time. And the absorption surface 21a is used without being substantially different from the initial state.

By the way, since the reflective surface 31a is provided with a hard-to-oxidize reflective coating layer, deterioration of the reflective surface 31a due to oxidation hardly occurs.

Further, since the cone 31 is irradiated only once with the laser beam, the heat input to the cone 31 is restricted as compared with the conventional case. Of course, since the cone 31 is cooled including the top, the temperature near the top does not rise. That is, since the reflection surface 31a is hardly deteriorated due to the oxidation of the reflection surface 31a and the high temperature near the top of the cone 31, even if the high-energy laser light is incident for a long time, The cone 31 is used with little change from the initial state.

Furthermore, since the bottom outer diameter of the conical reflecting surface of the conical body 31 may be slightly larger than the diameter D of the laser beam L, the conical body 31 provided with the conical reflecting surface can be made small and inexpensive. Can be manufactured.

Of course, as described above, according to the present invention, the vicinity of the top of the cone 31 does not deteriorate, but even if it deteriorates and the laser beam L is irregularly reflected near the top,
Since the top is provided at a position sufficiently penetrating from the opening end of the cylindrical body 21, the irregularly reflected light is absorbed by the inner peripheral absorbing surface 21 a of the cylindrical body 21. That is, since the distance between the top of the cone and the open end of the cylinder is configured as long as possible, the cylinder in the present invention has the same effect as the conventionally used diffuse reflection preventing cylinder. Is to do so.

[0028]

As is apparent from the above description, the laser light absorbing device according to the present invention forms a reflection surface by applying a non-oxidizable reflection coating layer to a cone, and forms a top surface of the reflection surface. The angle is an obtuse angle, the cylinder is formed to be long, the interval between the top of the cone and the opening end of the cylinder is made as long as possible, and the cone and the cylinder are Since the cooling passage for cooling is provided, the laser beam is only reflected once for the cone, and the oxidation of the reflection surface and the high temperature near the top of the cone are suppressed, and the oxidation is reduced. The reflecting surface is hardly deteriorated due to the increase in temperature, and therefore, even if a high-energy laser beam is incident for a long time, the reflecting surface is used without being substantially different from the initial state.

Also, since the conical reflecting surface can be made a small conical body, the conical body can be manufactured at low cost.

Further, since the space between the top of the cone and the open end of the cylinder is made as long as possible, the cylindrical body in the present invention absorbs laser light in a steady state and uses the conventional light. It has the same effect as the cylindrical body for preventing diffused reflection light. Therefore, the laser light absorbing device according to the present invention can be a small device that is shorter in the long axis direction than a conventional device having a cylinder for preventing diffused reflection light.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a state in FIG. 1;

FIG. 3 is a longitudinal sectional view showing a conventional example.

FIG. 4 is an explanatory diagram of a state in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Cylindrical body 21a Absorbing surface 24 Cooling passage 31 Cone with obtuse angle 31a Reflecting surface 34 Cooling passage 40 Laser light absorbing device

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 5/00 B23K 26/06

Claims (1)

(57) [Scope of request for utility model registration] A cylindrical member having an absorbing surface formed on an inner peripheral surface thereof, and one of the openings of the cylindrical member being closed, and being coaxially protruded into the cylindrical member. A conical body having a laser light reflecting surface on the surface, wherein the reflection angle of the cone is obtuse.
And the bottom profile is slightly larger than the incident beam diameter of the laser beam.
And the diameter of the cylinder is reflected by the cone
The laser beam so that it does not reach the cone again.
In addition, the laser beam that has entered the length of the cylinder
Until a damped beam that does not damage the peripheral members at the ends
A laser light absorbing device having a length for reflecting the same number of times and a cooling passage for cooling the conical body and the cylindrical body.