JPH04182086A - Condensing device for laser beam machining - Google Patents

Abstract

PURPOSE:To prevent unnecessary power density from reducing by assembling a total reflection mirror and a semicylindrical mirror as a laser beam system from a laser beam oscillator. CONSTITUTION:In a laser beam system, laser beam from a laser reflector is bent by the total reflection mirror 1 first, then, reflected by the semicylindrical mirror 2. When the beam bent by the total reflection mirror 1 is condensed by using a semicylindrical mirror 2, it is converged in the direction of a machining line at the focal position and a beam intensity pattern expanded in the direction vertical to this direction is obtained. Therefore, since an optional non-circular beam intensity pattern is obtained in the focal position, reduction of unnecessary power density is prevented and a complicated scanning device for scanning with the beam is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a condensing device for laser processing, and particularly to a condensing device for laser processing suitable for laser welding.

(Prior art and problems to be solved) Conventionally, laser heat sources have been used for various processing applications such as welding and surface modification, and CO2 lasers, YA
Various types such as G laser are used.

Conventionally, spherical or parabolic mirrors and lenses such as Zn5e have been used in the condensing systems of high-power lasers such as CO2 lasers, which narrow down the laser beam and perform welding with increased power density. It was used for such things.

By the way, in butt welding, if there is a gap in the butt part or when welding using filler wire, day focusing (defocusing) is performed to lower the power density, or scanning of the laser beam is performed. It is necessary to do so. This is because it is necessary to apply the laser beam to a fairly wide range.

However, in the above-mentioned spherical or parabolic condensing device, the beam pattern unique to the laser oscillator such as single mode, multimode, or ring mode can be directly used with a spherical lens, parabolic lens, spherical mirror, parabolic mirror, etc. Since this is a beam system that focuses the light at a distance, the beam spot spreads out in a circular shape, resulting in an unnecessary reduction in power density. That is, since the beam spot has the same distribution (circular shape) in the processing line direction (X-axis direction) and in the direction perpendicular thereto (y-axis direction), the power density can only be adjusted by day focusing. However, there is a problem in that day focusing causes an unnecessary reduction in power density. Also, because the beam spot is circular.

A beam spot with the desired shape could not be obtained.

Yet again. Another problem was that a complicated driving device (scanning mechanism) was required to scan the beam.

The present invention solves the above-mentioned problems of the prior art, prevents unnecessary reduction in power density, provides a beam spot with a desired shape, and does not require a complicated device for scanning the beam. The purpose of this invention is to provide an inexpensive condensing device for laser processing.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present inventors have conducted extensive research on laser beam systems, and have hereby accomplished the present invention.

That is, the present invention provides a laser beam system in which a laser beam from a laser oscillator is bent by a total reflection mirror, and further reflected by another mirror to be focused on a processing part. The gist of this invention is a condensing device for laser processing characterized by using a semi-cylindrical mirror.

Further, the present invention is characterized in that a sputter adhesion prevention device is provided, if necessary, for flowing gas in a direction coaxial with or intersecting with the direction of the laser beam.

The present invention will be explained in more detail below.

(Function) As mentioned above, the conventional laser focusing device collects the laser beam from the laser oscillator using a single lens (spherical lens, parabolic lens) or mirror (spherical mirror, parabolic mirror). Since it is a focused beam system, it causes an unnecessary drop in power density, requires complicated and expensive scanning equipment, or has durability problems such as welding spatter adhering to the lens and damaging the lens. Ta. Moreover, the overall cost was high.

On the other hand, in the present invention, instead of one lens or mirror,
By using a beam system that combines a total reflection mirror and a semi-cylindrical mirror, or by further providing a sputter adhesion prevention device, the above-mentioned problems can be solved.

FIG. 1 shows a laser beam system of the present invention, in which a laser beam from a laser oscillator is first bent by a total reflection mirror and then reflected by a semi-cylindrical mirror 2.

Here, the cylindrical mirror refers to a mirror that also has curvature in a direction orthogonal to the curvature direction of a normal cylindrical mirror. In other words, the entire mirror is shaped as shown in Figure 2, and its cross-section A has a cylindrical surface (cylindrical side surface) with a curvature f as shown in Figure 3, and the cross-section B has a curve as shown in Figure 4. As shown, the cylindrical surface is a
It has a curvature of Xf (1<a). The larger the value of a is, the wider the beam width in the B cross-sectional direction (Cy-axis direction) can be (see FIG. 5). The surface of the semi-cylindrical mirror is coated with a noble metal such as Cu or Au, making it an inexpensive and durable mirror.

When such a semi-cylindrical mirror is used to focus a beam bent by a total reflection mirror, the beam is focused in the processing line direction (X-axis direction) at the focal position, as shown in Fig. A beam intensity pattern spread in the orthogonal direction (y-axis direction) is obtained.

In the X-axis direction, it is possible to narrow down the light to the limit of light condensing theory. For example, 0.2) width in the X direction, 2 to 3 m in the X direction
A pattern of m width is obtained.

Note that semi-cylindrical mirrors are usually arranged so that the A cross-sectional direction coincides with the processing line direction (X-axis direction), and in this case, a beam intensity pattern as shown in FIG. 5 is obtained, but B When arranged so that the cross-sectional direction matches the machining line direction.

A beam intensity pattern with the y-axis and the y-axis reversed is obtained.

FIG. 6 shows a sputter adhesion prevention device provided in the above-mentioned beam system. In this device, a gas distribution member 3 is arranged around a condensed beam from a semi-cylindrical mirror. When the flow is coaxial with the direction of the laser beam, the outlet of the annular member is oriented coaxially with the beam. On the other hand, when flowing in a direction that intersects the laser beam direction, a pair of gas outlet ports and a gas suction port are placed opposite to each other around the beam in the intersecting direction, and the gas is ejected from the gas outlet port, and then the gas is Configure the device to attract air. Since welding spatter is scattered almost upward from the processed area, it is preferable to flow the gas in the same axis direction as the laser beam. As the gas, an inert gas such as N2, A, He, etc. is used. The gas flow rate is determined as appropriate.

(Effects of the Invention) As detailed above, according to the present invention, an arbitrary non-circular beam intensity pattern can be obtained at the focal position.
Unnecessary reduction in power density can be prevented, and a complicated scanning device for scanning the beam is not required. Furthermore, since it is possible to prevent adhesion of spatter, the durability of the mirror can be improved and it is economical.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the configuration of the laser beam system of the present invention, Figures 2 to 4 are diagrams explaining a semi-cylindrical mirror, Figure 2 is a perspective view, and Figure 3 is A of Figure 2. 4 is a sectional view taken along B in FIG. 2, and FIG. 5 is an explanatory diagram showing a beam intensity pattern obtained by the present invention. FIGS. 6(a) and 6(b) are explanatory diagrams showing a sputter adhesion prevention device. 1... Total reflection mirror, 2... Semi-cylindrical mirror, 3... Gas distribution member. Patent applicant: Kobe Steel, Ltd. Patent attorney Hisashi Nakamura 6 (b) I l \ I 3 ° 3

Claims (2)

[Claims] (1) In a laser beam system in which a laser beam from a laser oscillator is bent by a total reflection mirror, then reflected by another mirror and focused on the processing area, a semi-cylindrical mirror is used as the other mirror of the latter. A condensing device for laser processing characterized by using. (2) The condensing device for laser processing according to claim 1, further comprising a sputter adhesion prevention device that causes gas to flow in a direction coaxial or perpendicular to the direction of the laser beam.