JPH09225668A - Laser beam machining head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reflect laser beams made incident on the end face of a sleeve. SOLUTION: In this laser beam machining head 1 having a copper sleeve 6 which is provided inside with a passage 7 for transmitting a laser beam 4, which is connected to an optical fiber 3 at one end face 6a in the passage opening, and which emits a laser beam 4 at the other end face 6b from the passage opening, and having a condensing lens 8 which is provided on the other end face 6b side of this sleeve 6 and which converges the laser beam 4 for emitting to an object 5 to be machined, the reflectance at the other end face 6b of the sleeve 6 is made higher than at the opposite face of the sleeve 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam processing head, and more particularly to a structure of an end surface of a sleeve which receives reflected light from an object to be processed.

[0002]

2. Description of the Related Art A processing head for irradiating a processing object 5 with a laser beam includes an optical fiber 3 for transmitting the laser beam and a sleeve 6 for linearly shaping the laser beam of the optical fiber 3 as shown in FIG. It is composed of a condenser lens 8 which condenses the laser light from the sleeve 6 and irradiates the object 5 to be processed.

[0003]

A part of the laser beam applied to the object 5 is reflected and passes through the condenser lens 8,
Some are absorbed by the end face 6b of the sleeve 6.
Conventionally, when the output of the laser light generator is 1-2 kw,
Although the end face 6b was not melted by the absorbed energy, when the laser processing with the output of 3 to 4 kw has recently been performed, the end face 6b is melted, and the laser light emission port is deformed as the melting progresses. However, there is a problem in that proper laser light cannot be emitted or the sleeve 6 cannot be detached from the holder 9 that holds and cools the sleeve 6. For this reason, the sleeve 6 must be replaced frequently without melting progressing.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a structure in which the laser light can be reflected on the end surface of the sleeve which is reflected by the reflected light of the laser light.

[0005]

In order to achieve the above object, the invention of claim 1 has a passage for transmitting a laser beam therein, one end face of which has a passage opening connected to an optical fiber and the other end. A laser beam processing head comprising a metal sleeve for irradiating a laser beam from a passage opening at an end face, and an optical system provided on the other end face side of the sleeve for condensing the laser beam and irradiating the object to be processed. The other end surface of the sleeve has a higher reflectance than the other surface of the sleeve.

By making the reflectance of the other end surface of the sleeve higher than that of the other surface of the sleeve, absorption of reflected laser light from the object to be processed is reduced and melting is reduced.

In the invention of claim 2, the other end surface of the sleeve is mirror-finished. If the other end surface of the sleeve is mirror-finished, the reflected light of the laser is reflected again so that it is not absorbed by the sleeve and melting of the sleeve is prevented.

In the third aspect of the invention, the mirror surface processing is processed to have an arithmetic average roughness equal to or less than the wavelength of the laser light used. Finishing to an arithmetic average roughness similar to the laser wavelength used will increase the reflectance, and if finishing is smoother than this, the reflectance will increase accordingly and the energy absorbed will decrease. Therefore, the possibility of melting of the other end surface of the sleeve is reduced.

In the invention of claim 4, the other end surface of the sleeve is coated with a material having a higher reflectance than the material of the sleeve.

By coating the other end surface of the sleeve with a material having a higher reflectivity than the material of the sleeve,
The energy of the laser light absorbed from this end face is reduced, and the melting of the end face is reduced.

According to the invention of claim 5, the other end surface of the sleeve is provided with a mirror made of a material having a higher reflectance than the material of the sleeve.

By providing the other end face with a mirror made of a material having a higher reflectance than the sleeve material, the energy of the laser light absorbed from this end face is reduced and the melting is also reduced.

According to a sixth aspect of the present invention, in the fourth or fifth aspect, the material is any one of gold, silver, molybdenum, aluminum, chromium, MgF ₂ , and S _i O ₂ .

Gold, silver, molybdenum, aluminum and chromium are all metals having a high reflectance. In addition, MgF
₂ and SiO ₂ are also compounds with high reflectance. By using any of these, absorption of laser light from the other end face is reduced, and melting is also reduced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the configuration of the laser beam processing head according to the embodiment. The laser beam processing head 1 is a device that condenses a laser beam 4 generated by a laser generator 2 and transmitted by an optical fiber 3 and irradiates the laser beam 4 to a workpiece 5. In the laser beam processing head 1, the sleeve 6 has a cylindrical shape made of copper, and a passage 7 for the laser beam is provided at the axis. The sleeve 6 has a function of fixing the optical fiber 3 and adjusting the optical axis of the laser beam 4 incident from the optical fiber 3 in the cylindrical axis direction. One end face 6 of the sleeve 6
a is connected to the optical fiber 3 and emits the laser light 4 from the opening of the passage 7 of the other end face 6b. A plurality of condenser lenses 8 are provided on the other end surface 6b side of the sleeve 6, and collect the laser light 4 emitted from the end surface 6b and irradiate the processing object 5. The sleeve 6 is held by a cylindrical holder 9 that fits around the outer circumference. The holder 9 is also made of copper and has a cooling water channel 10 inside.
And is supplied with cooling water by a cooling water pipe (not shown),
Cool the sleeve 6. The condenser lens 8 and the holder 9 are housed in a casing 11.

In the first embodiment, the other end surface 6b of the sleeve 6 is mirror-finished. Since copper itself is a material having a high reflectance, the laser beam 4 reflected by the object 5 to be processed, condensed by the condenser lens 8 and hitting the other end face 6b is a mirror surface by subjecting this to mirror finishing. Is reflected. This prevents heating of the sleeve 6. The arithmetic mean roughness Ra (JIS B0601) of mirror surface processing is determined according to the wavelength of the laser light 4 used, and the arithmetic mean roughness Ra is in the range of 0.1λ to λ, where the wavelength of the laser light 4 is λ. Desirably, centering on 0.2λ, 0.1λ to 0.
A range of 3λ is preferable. It should be noted that the reflectance is larger when the thickness is smaller than 0.1λ, but the cost increases, so the value is set to 0.1λ from the balance with the cost. In terms of performance, 0.1λ or less is better. In the case where a unit other than the arithmetic average roughness is used, the same roughness is used.

In the second embodiment, the other end surface 6b of the sleeve 6 is coated with a highly reflective material. Metal coating is performed using any of gold, silver, molybdenum, aluminum, and chromium as a highly reflective material. Also the MgF ₂ or S _i O ₂ used as the highly reflective material, performing dielectric coating. By this coating, the light is reflected by the object to be processed 5 and is condensed by the condenser lens 8 to form the other end surface 6
Most of the laser beam 4 which hits b is reflected. This prevents heating of the sleeve 6.

In the third embodiment, a mirror made of a high reflectance material is attached to the other end surface 6b of the sleeve 6. The high-reflectance material is the same as that shown in the case of coating, and when the metal alone is gold, silver, molybdenum,
Either aluminum or chromium, or MgF _{2 as} a compound
Alternatively, S _i O ₂ or the like is used. In the manufacture of a mirror, these metals or compounds are mirror-finished. The processing roughness is similar to that of the first embodiment. In addition, a mirror is manufactured by subjecting glass or the like to metal coating of the above metal or dielectric coating of the compound. The mirror thus manufactured is attached to the other end surface 6b of the sleeve 6 with an adhesive or the like. The laser light 4 reflected by the object 5 to be processed by the mirror, condensed by the condenser lens 8 and impinging on the other end face 6b is largely reflected. This prevents heating of the sleeve 6.

In the first to third embodiments, the other end surface 6b of the sleeve 6 is flat. As a result, a part of the reflected light is again irradiated onto the object to be processed 5 by the condenser lens 8, but most of the reflected light is diffused to the surroundings. Since the diffused reflected light is not condensed by the condenser lens, its energy is small, and even if the reflected light hits, the degree of heating is small. The shape of the end face 6b may be concave, and the reflected light may be returned to the workpiece 5 by the condenser lens 8 again.

[0020]

As is apparent from the above description, according to the present invention, the end surface of the sleeve is mirror-finished or coated with a high-reflectance material, or a mirror is attached to the end surface of the sleeve so that the end-face is reflected and returned. Since the incoming laser light is reflected, heating of the sleeve is reduced and melting can be prevented. This extends the life of the sleeve and improves its reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an embodiment of the present invention.

[Explanation of symbols]

 1 Laser Light Processing Head 2 Laser Light Generation Device 3 Optical Fiber 4 Laser Light 5 Object to be Processed 6 Sleeve 6a One End Face 6b Other End Face 7 Passage 8 Condenser Lens 9 Holder 10 Cooling Water Passage 11 Casing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Nishimi 3-1-15-1 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Toji Technical Center (72) Inventor Keinosuke Maeda Shinagawa-ku, Tokyo 1-17 Osaki Ishikawajima System Technology Co., Ltd. (72) Inventor Yutaka Kanazawa 3-15-15 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Toji Technical Center

Claims (6)

[Claims] A path for transmitting laser light therein;
A metal sleeve in which the passage opening is connected to the optical fiber at one end face, and the other end face irradiates the laser light from the passage opening, and the laser light is provided on the other end face side of this sleeve to condense the laser light for processing. A laser beam processing head having an optical system for irradiating an object, wherein the other end surface of the sleeve has a higher reflectance than the other surface of the sleeve. 2. The laser beam processing head according to claim 1, wherein the other end surface of the sleeve is mirror-finished. 3. The laser beam processing head according to claim 2, wherein the mirror surface processing is processed to have an arithmetic average roughness equal to or less than a wavelength of a laser beam to be used. 4. The laser beam machining head according to claim 1, wherein the other end surface of the sleeve is coated with a material having a reflectance higher than that of the material of the sleeve. 5. The laser beam machining head according to claim 1, wherein a mirror made of a material having a reflectance higher than that of the sleeve is provided on the other end surface of the sleeve. Wherein said material is gold, silver, molybdenum, aluminum, chromium, MgF _2, a laser beam machining head according to claim 4 or 5, wherein the at S _i either O _2.