JPS6054838B2 - Laser processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser processing device that processes a workpiece by irradiating it with a laser beam, and is capable of obtaining a laser beam having a uniform energy density distribution, particularly when performing heat treatment processing. This invention relates to laser processing equipment.

The energy density of laser light extracted from a laser oscillator has a distribution according to various modes depending on the characteristics of the oscillator.

Taking the case of a TEMOO (Gaussian) laser beam as an example, as shown in Figure 1, the energy density is high at the center of the beam cross section 10, and the energy density increases exponentially as you move away from the center. descend. As shown in FIG. 2, once such laser light 9 is focused by the condensing lens 12, it is irradiated onto the workpiece 14 at a position shifted from the converging surface 13, which is enlarged as shown in FIG. As shown, isothermal line 1
6 extends from the center of the irradiation part as a group of concentric circular arc parts. The temperatures T1 to T4 of this isothermal line are lower toward the periphery (T1 < T2 * T3 * T4), and it is not possible to uniformly heat a certain area of the surface to a constant temperature. For example, in hardening processing, if T2 is the hardening temperature, only the center part can be hardened, but the hardening depth is not uniform, and the energy of the laser beam in the peripheral part 18 does not contribute to hardening, so the heat treatment efficiency is (Quenching volume/(output x time)
It has the disadvantage of decreasing. As a method to eliminate the drawbacks of the heat treatment process described above, as shown in Figure 4A, the laser beam is divided into two, and each laser beam is focused using a cylindrical concave mirror so that the energy density distribution is uniform in the X direction. The present inventors have proposed a method for
No. 3-23525).

The illustrated device includes a reflecting mirror 43 that divides the laser beam into two parts and reflects them in different directions, and reflects each of these divided laser beams. It consists of cylindrical concave mirrors 41 and 42, and split laser beams 100 and 101 reflected from the concave mirrors 41 and 42 are focused on a predetermined location 52 on the workpiece 14 for processing. The energy density distribution in this case is shown in FIG. 4B, and the energy density distribution is the X direction energy density distribution 1 of each divided laser beam.
This is the sum of 00A and 100B, which is uniform in the X direction. In addition, the isothermal lines 16 are also parallel to the surface of the workpiece 14, so that uniform hardening is possible and the heat treatment efficiency is also improved. However, such a device
In order to divide the laser beam, a reflecting mirror is required for each divided laser beam, which requires a relatively large space. For this reason, it has the disadvantage that it is difficult to use when there are spatial restrictions, such as the inner surface of a thin vibrator or the inner surface of a cylinder that makes sliding contact with a piston. An object of the present invention is to provide a laser processing device that can obtain a laser beam having as uniform an energy density distribution as possible using a small number of reflecting mirrors and has a spatially compact configuration. It is in.

The present invention provides a laser processing apparatus that processes a workpiece by irradiating it with a laser beam, without dividing the laser beam into multiple parts.
The above object is achieved by inverting and synthesizing the energy density distribution using one or two reflecting mirrors and shaping the laser beam into a laser beam having a uniform energy density distribution in at least one direction. That is, according to a typical example of the present invention, in a laser processing apparatus that focuses laser light onto a workpiece through a reflecting mirror, the reflecting mirror is configured to form a fold line that intersects at a predetermined angle with the fold line. A laser processing device characterized by having, as a reflective surface, a concave surface (hereinafter referred to as a crossed quadratic curve) that is formed when parallel movement is made along a quadratic curve that intersects perpendicularly and is concave to the concave side of the broken line. is provided. Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 5 is a perspective view showing one embodiment of a reflecting mirror used in the present invention. This reflecting mirror has a concave curved surface (referred to as a crossed quadratic curved reflecting mirror) that is formed when the polygonal line COID is translated along a curve 0102 that is a part of a circle or an ellipse. As shown in FIG. 6, if the reflecting mirror 51 is tilted at a certain angle from the horizontal plane and the TEMOO mode laser beam 9 is vertically incident thereon, an elongated condensing section 52 can be obtained. Arrow A1 Arrow B shows how this light is focused.
Figures 7 and 8 show views from this direction. In the condensing section 52, the center part of the incident beam with high energy luminous intensity is guided to both ends of the condensing section, and at the same time, since the reflecting surface has a circular or elliptical curvature in the Y1-Y2 direction, it is narrowed in the Y and -Y2 directions. Thus, it is possible to obtain laser light having a substantially uniform energy density distribution in the X direction, similar to the energy density distribution 102 of the conventional example (FIG. 4). In such a device,
When a workpiece is placed in the condensing section 52 and moved, it is possible to perform heat treatment with a uniform depth and high thermal efficiency. Next, FIG. 9 shows another embodiment of the present invention, in which the laser beam 9 is crossed by a quadratic curved reflecting mirror 51 as in the embodiment of FIG.
After the light is reflected by the plane mirror 53, the light is reflected by the condenser
is guided onto the workpiece 14.

Thermal processing of the workpiece 14 is performed by moving the condensing section 52 onto the workpiece. In this case, the workpiece 14 may be moved, or the entire laser beam irradiation device may be moved. Good too. In this embodiment as well, it is possible to obtain a condensing portion 52 having a substantially uniform energy density distribution, and therefore it is possible to perform heat treatment with a uniform processing depth and high thermal efficiency. FIG. 10 shows still another embodiment of the present invention, in which a condensing surface 52 is obtained using a crossed linearly curved plane mirror 54 and a cylindrical (or elliptical cylindrical concave mirror) 55.

In the figure, vertically incident light 9 is reflected by a reflecting mirror 54 placed at an angle α with respect to the horizontal plane, and guided to the concave reflecting mirror 55 . The crossed linear curved reflector 54 is the 11th
As shown in the figure, it has a ■-shaped concave surface that appears when the broken line COID is translated in parallel along the straight line 0102. Also,
The concave reflecting mirror 55 is a reflecting mirror that has an inner surface cut out from a portion of a cylinder or an elliptical cylinder as a reflecting surface, and has a curvature in the Y1-Y2 direction. When the incident light is a TEMOO mode laser beam, the central part with high energy density is a crossed linear curved reflector 5.
4 to both ends of the concave reflecting mirror 55, but since the reflecting mirror 55 has a curvature in the Y1-Y2 direction,
The light is focused on a curved surface in the direction, and a light focusing portion 52 having a substantially uniform energy density distribution in the X direction on the workpiece 14 is provided as in the previous embodiment. This light condensing part 52 is connected to the workpiece 14
By moving upward in the Y direction, a hardened surface with a substantially uniform machining depth can be obtained. The present invention is limited to the embodiments shown in FIGS. 5 to 11 above, but various modifications may be considered. For example, Fig. 6, Fig. 9, Fig. 1
In the embodiment shown in FIG.
2 can be vibrated in the Y direction, and a wide area of the machining surface 52A can be obtained. As the vibration applying means, ordinary mechanical means can be used. Furthermore, the cross quadratic curved surface shown in FIG. 5 may also have a concave or convex curvature in the 01C101D direction, thereby reducing or expanding the x-direction width of the condensing section 52 in FIG. 6 or 9. I can do it. Moreover, 01C of the crossed linear curved surface shown in FIG. ．． 01
By giving curvature (concave or convex) also in the D direction,
The x-direction width of the condensing section 52 in FIG. 9 can be reduced or expanded. Furthermore, by making at least one direction of the reflecting mirror 53 in FIG. 9 a concave or convex surface, the width of the light condensing section 52 in the X direction can be reduced or expanded.

Similarly, in FIG. 10, the reflecting mirror 55 is also provided with a curvature (concave or convex) in the X1-X2 direction, so that the width of the condensing portion 52 in the X direction can be reduced or expanded. Next, an example of use of the device of the present invention will be explained based on the drawings.

FIG. 12 is an explanatory diagram showing the state of hardening of the inner surface of the thin tube 15 when the diameter of the incident laser beam 9 is larger than the tube diameter. In the figure, the laser beam 9 is transmitted to the beam expander 5.
6 into a parallel laser beam 9A having a diameter smaller than the tube diameter, and the crossed secondary surface reflecting mirror 51 according to the present invention in the thin tube 15
By moving the crossed quadratic curved reflecting mirror 51 at a speed of 1, the inner surface of the tube can be continuously hardened. Although the drawing shows a case in which the reflecting mirror 51 is moved in the direction of the arrow, the reflecting mirror 51 may be fixed and the thin tube 15 may be moved. In this embodiment, since the laser beam 9A incident on the tube is parallel to the length direction of the tube, there is an advantage that even if the tube length is long, any position on the inner surface of the tube can be hardened. Further, since the cross quadratic curved reflecting mirror 51 may have a size approximately equal to the diameter of the laser beam 9A, it is possible to harden any part of the inner surface of the small diameter tube. FIG. 13 shows the cross-sectional shape of the hardened portion 15A of the thin tube 15, and a hardened portion cross-sectional shape 59 having a uniform hardening depth can be obtained. FIG. 14 is a sectional view showing an example of the use of the laser processing apparatus shown in FIG. 10 to cut a workpiece (rubber) 14.

This processing apparatus is equipped with a gas spraying device 60, which sprays an inert gas 61 such as argon (in the direction of the arrow) onto the laser beam condensing section. Using such a device, the beam output of laser light is 2KW1, and the scanning speed is 10W1, Imin.
So 3? When cutting the thick synthetic rubber, a good cut surface was obtained. As described above, according to the present invention, it is possible to easily obtain a laser condensing section with uniform energy density in at least one direction using one or two reflecting mirrors, and since the main component of the device is composed of the reflecting mirrors, Unlike lenses, there is no risk of damage, and it is possible to increase the output of laser light.

Furthermore, since the structure is compact, it is easy to handle, and laser processing can be performed even in narrow processing areas, which has been difficult in the past.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the cross-sectional shape and energy density distribution of a laser beam having a Gaussian energy density distribution, Fig. 2 is a schematic diagram showing the principle of a conventional laser processing method, and Fig. 3 is a diagram showing the energy density distribution. 2 is a cross-sectional view showing the heating situation according to the method, FIG. 4A is a schematic configuration diagram showing the principle of the conventional laser processing method, FIG. 4B is a cross-sectional view of the heating situation, and FIG. FIG. 6 is a perspective view of a reflecting mirror used in an embodiment of the invention; FIG. 6 is a schematic explanatory diagram illustrating an embodiment of a laser processing method according to the invention; The figure is B in Figure 5.
9 is a schematic configuration diagram of a laser processing device illustrating another embodiment of the present invention, and FIG. 10 is a schematic configuration diagram of a laser processing device illustrating still another embodiment of the present invention. , FIG. 11 is a perspective view of another reflecting mirror used in the embodiment of the present invention, FIG. 12 is a diagram showing an example of use of the device of the present invention, and FIG. 13 is a perspective view of another reflecting mirror used in the embodiment of the present invention. FIG. 14, a cross-sectional view showing the hardened state of the inner surface of the hardened tube, is a diagram illustrating another usage example of the apparatus of the present invention. 9,9A... Loser light, 10... Loser light cross-sectional shape, 11... Energy density distribution, 12.
... Convex lens, 13 ... Focal plane, 14.
...Workpiece member, 15...Pipe inner surface, 16
...Isothermal line, 18 ... Laser light that does not contribute to loser hardening, 41, 42 ... Cylindrical concave mirror, 43 ... Two-split reflecting mirror, 51・・・・・・
・Cross quadratic curved reflector, 52...Condensing section, 53
...Flat reflecting mirror, 54... Cross linear curved reflecting mirror, 55... Cylindrical or elliptic cylindrical concave mirror, 56... Beam expander, 59...
...Hardened part, 100, 101... Divided laser beam.

Claims (1)

[Scope of Claims] 1. In a laser processing device that focuses a laser beam having a substantially circular beam cross section onto a workpiece through a reflecting mirror, the reflecting mirror converts a folded line that intersects at a predetermined angle into the folded line. It has a concave surface (hereinafter referred to as a crossed quadratic curve) that is formed when parallel movement is made along a quadratic curve that is orthogonal to the curve and is concave to the concave side of the broken line (hereinafter referred to as a crossed quadratic curve) as a reflecting surface, and the luminous flux of the laser beam The center of the cross section is positioned on the bending line of the concave surface, and each light beam with a semicircular cross section is divided and reflected thereby, so that the arcuate parts of the semicircular cross section intersect each other and the straight parts are almost parallel. A laser processing device characterized by condensing light so as to overlap each other. 2. A laser processing apparatus according to claim 1, characterized in that the laser beam from the reflecting mirror is further condensed onto a workpiece via a plane reflecting mirror. 3. In claim 1, at least one of the reflecting mirrors is used to vibrate the laser beam on the workpiece.
A laser processing device characterized in that a vibration imparting means is provided in the laser processing device. 4. In a laser processing device that focuses a laser beam having a substantially circular beam cross section onto a workpiece via a reflecting mirror, the reflecting mirror converts a folded line that intersects at a predetermined angle into a straight line perpendicular to the intersection of the folded lines. a concave reflective surface (hereinafter referred to as a crossed linear curved surface) formed when the laser beam is moved in parallel along the curve; At least one direction in which each of the light beams having a semicircular cross section that is divided and reflected is focused such that the arc parts of the semicircular cross section of the light beam cross each other and the linear parts are substantially parallel to each other and are superimposed. A laser processing device comprising a concave mirror having a quadratic curvature. 5. A laser processing apparatus according to claim 4, characterized in that at least one of the reflecting mirrors is provided with a vibration imparting means in order to vibrate the laser beam on the workpiece.