JPS6224193B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an optical head for laser processing, which constitutes a part of a laser processing machine.

As a conventional device of this type, the one shown in FIG. 1 is known. In FIG. 1, reference numeral 1 indicates a laser oscillator, and the laser oscillator 1 is provided with a partial reflection mirror 3 on the laser extraction side, and a total reflection mirror 4 is provided opposite to this partial reflection mirror 3. . A cylindrical body ₆ constituting an optical head H1 for laser processing is connected to the laser outlet 5 of the laser oscillator 1, and forms a path through which the laser beam 7 passes.
The cylindrical body 6 is bent at a right angle at approximately the center thereof, and a reflecting mirror 8 is provided at this bent portion to bend the laser beam 7 taken out from the oscillator 1 by 90 degrees. It is made to advance along the bending direction. A condenser lens 9 is disposed near the tip of the cylinder 6 so as to be orthogonal to the axis of the cylinder 6, and a nozzle 10 is attached to the tip of the cylinder 6. The laser beam 7 passing through the cylinder 6 is focused by the focusing lens 9, exits from the nozzle 10, and is irradiated onto the workpiece 11.

An auxiliary port 12 is provided at the tip of the cylindrical body 6 on the nozzle 10 side of the condensing lens 9, and auxiliary gas flows from the auxiliary port 12 through the cylindrical body 6 and the nozzle 10 to the workpiece. It is designed to be sprayed on 11.

Optical head for laser processing with the above configuration
At H ₁ , a part of the light 2 generated by the laser oscillator 1 passes through the partial reflecting mirror 3 and enters the cylinder 6 constituting the optical head H ₁ as a laser beam 7, and the light 2 is transmitted through the bent portion of the cylinder 6. The traveling direction of the light is bent by 90 degrees by a reflecting mirror 8 disposed at the front, and the light travels straight to reach a condenser lens 9. The laser beam 7 that has reached the condensing lens 9 is focused here, passes through the nozzle 10, is supplied as high-density energy onto the workpiece 11, and is used for cutting, welding, heat treatment, etc. of the workpiece 11. Ru. At this time, at the same time as the laser beam 7 is irradiated, auxiliary gas is supplied from the auxiliary port 12 and blown onto the surface of the workpiece 11, but this auxiliary gas causes an oxidation reaction with the workpiece 11, and the reaction heat causes the workpiece to be processed. The object 11 is heated to an increasingly high temperature, and processing such as cutting of the object 11 is effectively carried out. In addition, this auxiliary gas is blown onto the generated oxide to remove it, or protects the molten metal from impurities in the external atmosphere. It also has the function of effectively protecting the

Now, as mentioned above, when the workpiece 11 is welded or the like, the part to be irradiated with the laser beam 6 reaches a high temperature,
The laser beam 7 is diffusely reflected from this part, and this diffusely reflected light enters the optical head H1 through the nozzle ₁₀ , passes through the condensing lens 9, is bent by the reflecting mirror 8, and is reflected inside the laser oscillator 1. enter. Then, the light inside the oscillator 1 is further amplified by this incident light, and its optical energy becomes higher than the desired reference value, putting an excessive load on the partial reflection mirror 3 and the total reflection mirror 4, which causes Reflector 3, 4
This had the disadvantage that the lifespan of the device was shortened.

The present invention has been made in view of the above points, and includes a first lens for condensing a laser beam taken out from the above-mentioned outlet, and a first lens between the above-mentioned outlet and the condenser lens. A shielding plate arranged at a focal position and provided with a pore through which the laser beam focused by the first lens passes, and a second lens that returns the laser beam that has passed through the shielding plate into a parallel beam bundle are interposed. This makes it possible to prevent diffusely reflected light from entering the laser oscillator from the workpiece.

Hereinafter, based on the illustrated embodiment, the present invention will be explained with reference to FIG. 2, in which the same or equivalent parts as in FIG. 1 are denoted by the same reference numerals. This is a first lens that focuses a laser beam 7 that is tilted and parallel to the axis of the cylinder 6, and the laser beam 7 that has passed through this first lens 13 is provided at a focal length position of the first lens 13. Pinhole 14a of shielding plate 14
pass through. This pinhole 14a is bored in the shielding plate 14 so as to be located at the focal point of the first lens 13. The laser beam 7 that has passed through the shielding plate 14 passes through a second lens 15 located apart from the position of the shielding plate 14 by the focal length,
The laser beam is translated in the same direction as the laser beam 7 before passing through the first lens 13. FIG. 2 shows the direction in which this laser beam 7 travels. The laser beam 7 that has passed through the second lens 15 in this manner is irradiated onto the workpiece through a reflecting mirror 8 and a condensing lens 9, as in the conventional case, and is used for processing operations such as welding and cutting.

Since the optical head H ₂ for laser processing according to this embodiment has the above configuration, the laser beam 7 emitted from the oscillator 1 is focused by the first lens 13 and the shielding plate 1
The laser beam 7 passes through the pinhole 14a of No. 4, is focused by the action of the second lens 15, returns to a parallel laser beam 7, and enters the reflecting mirror 8. This laser beam 7 is 90
The workpiece 11 is bent and transmitted through the condensing lens 9 as a laser beam 7 with high density energy.
The surface is irradiated, and the workpiece 11 is cut or the like.

However, when welding the workpiece 11, a part of the laser beam 7 is diffusely reflected and travels back into the optical head _H2 through the nozzle 10, but this diffusely reflected light is
When the light passes through the second lens 15 and reaches the shielding plate 14, it hardly passes through the pinhole 14a of the shielding plate 14, and is reflected by the shielding plate 14, which is made of aluminum or copper, and has low light absorption. The Rukoto. Therefore, there is almost no diffusely reflected light of the laser beam 7 that travels back to the laser oscillator 1, and the reference value of energy within the oscillator 1 can be stably maintained, thereby preventing overload on the partial reflection mirror 3 and the total reflection mirror 4. You can extend the lifespan of these products without having to worry about them.

Note that in this embodiment, the first and second lenses 13 and 15
In addition, the shielding plate 14 is arranged between the laser beam extraction port 5 and the reflecting mirror 8.
Needless to say, the same effect can be achieved even if it is disposed between the reflecting mirror 8 and the condensing lens 9. Further, the cylinder 6 does not need to be bent as in this embodiment, and it goes without saying that it can be made straight with the same effect, depending on the purpose of use of the device.

According to the present invention, it is possible to prevent diffusely reflected light from the workpiece from entering the laser oscillator, to stabilize the energy value of the oscillator, and to extend the life of the oscillator itself.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main parts of a conventional optical head for laser processing, and FIG. 2 is a sectional view showing the main parts of an optical head for laser processing according to an embodiment of the present invention. 6... Cylindrical body, 7... Laser beam, 8... Reflector, 9
... Condensing lens, 11... Workpiece, 13... First lens, 14... Shielding plate, 15... Second lens.

Claims (1)

[Claims] 1. In an optical head for laser processing equipped with a laser beam extraction port and a condensing lens that focuses the laser beam and applies high-density energy to it, there is a space between the extraction port and the condenser lens, a first lens that focuses the laser beam taken out from the extraction port; and a shielding plate that is arranged at the focal point of the first lens and has a pore that allows the laser beam focused by the first lens to pass through. An optical head for laser processing, characterized in that a second lens for returning the laser beam that has passed through the shielding plate into a parallel beam is interposed therebetween.