JPH0318494A - Laser processing head - Google Patents

Abstract

PURPOSE:To lower the transmission loss of a laser beam by providing a paraboloidal mirror which is disposed freely oscillatably around the optical axis of the laser beam and movably back and forth along the optical axis and a driving mean for driving this mirror on the optical axis of the laser beam. CONSTITUTION:This processing head has a reflecting mirror 2 which is fixed on the optical axis of the laser beam 1 and the paraboloidal mirror 3 which is on the optical axis y the reflected light beam of the mirror 2 and is pivoted freely rotatably around this optical axis. The head has the driving means 4 to drive the paraboloidal mirror 3 so as to oscillate the mirror within a prescribed angle range. The driving means oscillates the paraboloidal mirror 3 to the prescribed angle range via a pinion 41 and a gear 42 by running a motor 40 forward and backward. Since the paraboloidal mirror 3 has the function to condense the reflected light together with the function to reflect the light, the exit light progresses while reducing the beam diameter and is condensed onto the prescribed spot S on the surface of a work. This light scans back and forth approximately straight. The size and weight of the processing head are reduced in this way and the decrease of the light energy is minimized.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a laser processing head used for welding, heat treatment, etc. using the energy possessed by a laser. The present invention relates to a laser processing head that includes a built-in optical scanning mechanism that enables linear scanning of an irradiation position.

[Conventional technology]

The laser processing head focuses the laser light introduced into it from the laser oscillator and emits it to the outside.
Welding that uses the optical energy possessed by a laser. Used when performing various processing such as heat treatment.

For example, in laser welding, a laser processing head that faces the workpiece at a predetermined distance is moved along a predetermined welding line, and the area near the welding line is exposed to the energy of the laser beam. Heating the welded object? 8. It is done by melting. In this welding, the laser beam is irradiated extremely locally, so while it is possible to perform highly precise welding, it has the disadvantage that the release of bubbles from the molten part is inhibited and the molten part is rapidly cooled. In the weld bead that appears as a result of welding,
There is a possibility that welding defects such as cavities (porosity) caused by the remaining air bubbles and cracks caused by the rapid cooling may occur. Therefore, conventionally, a built-in optical scanning mechanism that can reciprocate the irradiation position of the laser beam on the workpiece in a direction substantially perpendicular to the welding line is built in, which promotes the release of air bubbles by stirring the molten part. In addition to preventing the occurrence of volocity within the bead, a fusion zone of a predetermined width is generated near the weld line, and the fusion zone is slowly cooled to prevent the occurrence of cracks. Laser processing heads have been put into practical use for some time.

Also during the heat treatment, a laser processing head having a built-in optical scanning mechanism as described above is conveniently used to continuously produce a heat treatment portion having a predetermined width.

FIG. 2 is a schematic perspective view showing the structure of a conventional laser processing head incorporating an optical scanning mechanism.

Laser light 1 oscillated by a laser oscillator (not shown) is
The light is introduced into the laser processing head through a suitable optical system, and is focused by the condenser lens 5. The conventional optical scanning mechanism 6 includes a first reflecting mirror 61 fixedly installed downstream of a condensing lens 5 at a predetermined inclination with respect to the optical axis of the laser beam 1, and a light beam reflected by the first reflecting mirror 61. A second plate arranged at a predetermined inclination with respect to the axis.
and a driving means 63 for swinging the reflecting mirror 62 at high speed within a small angular range around the optical axis of the reflected light. After passing through the condensing lens 5, the laser beam 1 reaches the first reflecting mirror 61 while reducing the beam diameter, and is reflected by the reflecting mirror 61 toward the second reflecting mirror 62. Next, the light is reflected by the second reflecting mirror 62 in substantially the same direction as the introduced light, is emitted to the outside, and is focused on a predetermined spot S on the surface of the workpiece (not shown). At this time, the second reflecting mirror 62 is oscillating due to the operation of the drive stage 63, and with this oscillation, the direction of reflection by the second reflecting mirror 62 changes within a small angular range. , the spot}S is reciprocated approximately linearly within a minute width corresponding to the swing angle.

[Problem to be solved by the invention]

Since laser processing heads perform laser irradiation while moving over the workpiece, there is a strong need for a smaller and lighter overall shape, but in conventional laser processing heads that are capable of optical scanning, the laser beam A condensing lens 5 for condensing light, a first and second reflecting mirror 6L62 for realizing optical scanning, and a driving means 63 are arranged so as to maintain a predetermined positional relationship with each other. Small size, as needed
There was a problem in that it could not fully meet the demand for weight reduction.

Further, the laser beam l introduced into the conventional laser processing head suffers at least a transmission loss due to transmission through the condenser lens 5 and the first and second reflecting mirrors 61 . There is a problem that there is a transmission loss due to reflection at 62, and there is a limit to the reduction of the overall transmission loss, resulting in a reduction in the optical energy that can be used for processing.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a laser processing head capable of optical scanning, which is compact and lightweight, and reduces internal transmission loss.

[Means to solve the problem]

The laser processing head according to the present invention is provided with a parabolic mirror that swings close to the optical axis or reciprocates along the optical axis on the optical axis of the laser beam introduced into the head. be.

[Effect]

In the present invention, the laser beam introduced into the laser processing head is focused by reflection on a parabolic mirror, and
By swinging or reciprocating the parabolic mirror, the reflection direction is changed and the light is emitted to the outside, producing a minute spot on the workpiece that is reciprocated within a predetermined width.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof. FIG. 1 is a schematic vertical cross-sectional view of a laser processing head according to the present invention.

In the figure, reference numeral 1 indicates a laser beam oscillated by a laser oscillator (not shown), and the laser beam 1 is introduced into the interior of the laser processing head via an appropriate optical system.

The laser processing head according to the present invention includes a reflecting mirror 2 fixed on the optical axis of the laser beam 1 introduced in this way and having a predetermined inclination with respect to the optical axis, and the reflecting mirror 2. A parabolic mirror 3 is located on the optical axis of the reflected light and is rotatably supported around the optical axis, and the parabolic mirror 3 is swung within a predetermined angular range. 1,000 drive stages 4 to be driven as desired. The driving means 4 is, for example, a motor 40 serving as a driving source.
A small gear 41 fitted to the end of the rotating shaft is meshed with a large gear 42 fitted to the axial center position of the parabolic mirror 3, and by rotating the motor 40 forward and backward in short cycles, The parabolic mirror 3, to which this rotation is transmitted via the small gear 41 and the large gear 42, is configured to swing within a predetermined angular range. It should be noted that since the }2 motion angle of the parabolic mirror 3 is a minute angle, the small gear 4l and the large gear 42 do not need to be full gears as shown in the figure, which have teeth over the entire circumference.
It may also be a partial gear in which teeth are formed only in the portion corresponding to the drawing angle. Further, instead of the motor 40, another electric actuator, for example, a solenoid, can be used as the drive source. In this case, a movement conversion mechanism such as a rank and pinion is used to change the forward and backward movement of the solenoid into a parabolic shape. It is sufficient to adopt a structure in which the movement is converted into the rocking motion of the mirror 3.

In the laser processing head according to the present invention constructed as described above, the laser beam 1 introduced as described above is reflected by the reflecting mirror 2, changes direction approximately at right angles, and reaches the parabolic mirror 3. , the light is counterattacked by the parabolic mirror 3, and the direction is changed again at a substantially right angle, and the light is emitted in substantially the same direction as the direction of introduction. Since the parabolic mirror 3 has a light reflecting function and a reflected light condensing function, the emitted light travels while reducing the beam diameter and is arranged opposite to the emitting end. The light is focused on a predetermined spot +-S on the surface of the workpiece (not shown). At this time, the parabolic mirror 3 is oscillated by the above-described operation of the driving means 4, and the direction of reflection by the parabolic mirror 3 changes in a small angular range due to this oscillation. The spot S is reciprocated approximately linearly within a minute width corresponding to the swing angle of the parabolic mirror 3, as shown by arrows in the figure.

That is, in the laser processing hesode according to the present invention, the parabolic mirror 3, which is oscillated by the operation of the driving means 4, receives the laser beam 1.
The functions of the condensing lens 5 and the second reflecting mirror 62 in the conventional laser processing head shown in FIG. simultaneously. Therefore, irradiating the laser beam l onto a minute spot S on the workpiece and scanning the spot S in a straight line are performed using two optical elements, namely the reflecting mirror 2 and the parabolic mirror. It is clear that by reducing the number of elements, it is possible to realize a smaller size and lighter weight, and also to reduce the transmission loss of the laser beam l inside.

In this embodiment, a case has been described in which the parabolic mirror 3 is swung; It is also possible to perform optical scanning by reciprocating at a high speed. However, the direction of light scanning in this case is perpendicular to that in the case of swinging the parabolic mirror 3 on the surface of the workpiece.

〔Effect of the invention〕

As described in detail above, in the laser processing chamber according to the present invention, the laser beam introduced into the interior is focused by reflection on the parabolic mirror arranged on the optical axis of the laser beam, and this radiation Since scanning is performed by swinging the object mirror around the optical axis or reciprocating along the optical axis, the number of optical elements required for focusing and scanning the light is small, and it is easy to secure their placement positions. Therefore, the present invention has excellent effects, such as realizing a smaller size and lighter weight, reducing internal transmission loss of laser light, and minimizing a decrease in optical energy that can be used for processing.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical sectional view of a laser processing head according to the present invention, and FIG. 2 is a schematic perspective view showing the structure of a conventional laser processing head. DESCRIPTION OF SYMBOLS 1... Laser light 3... Parabolic mirror 4... Driving means Note that in the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A laser processing head that includes a built-in optical scanning mechanism that linearly scans the irradiation position on the workpiece when condensing the laser light introduced into the workpiece and irradiating the workpiece, The scanning mechanism includes: a parabolic mirror disposed on the optical axis of the laser beam so as to be able to swing around the optical axis or reciprocate along the optical axis; A laser processing head characterized by comprising: a driving means for driving to swing or reciprocate.