JPH02108484A - Method for forming hole by laser beam - Google Patents

Abstract

PURPOSE:To form a hole having an smooth inner peripheral surface and a surface parallel with the optical axis of a laser beam by moving the laser beam to form a hole on a material to be worked, continuously, moving the laser beam while cutting down the cutting plane of the hole with the laser beam and forming a hole having a prescribed diameter. CONSTITUTION:A cutting-starting position A of the material 2 to be worked is irradiated and cut with the laser beam. The laser beam is moved continuously until it comes again to the starting position A to make a hole 8 on the material 2 to be worked. Successively the laser beam is moved while cutting down the surface of the hole 8 until the laser beam comes from the starting position A again to the starting position A to form a hole 6 of a prescribed diameter. Thus, it is possible to form a hole having a smooth inner peripheral surface and a plane parallel to the optical axis of the laser beam.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method of laser processing a workpiece using a laser beam, and more particularly to a method of forming a hole in a workpiece using a laser beam.

"Prior Art" Conventionally, it has been widely used to form holes in a workpiece using a carbon dioxide gas laser processing machine. When forming a hole in a workpiece, the workpiece is usually placed on a processing table, and then a laser beam is irradiated onto the workpiece while injecting assist gas from a focus head. A through hole is drilled inside the virtual circle to be cut.

Next, while irradiating the laser beam, the focus head and the workpiece are moved relative to each other to move the laser beam to a predetermined cutting start position on the virtual circle, and then continue to move the laser beam along the virtual circle. Then, the laser beam is continuously moved until it reaches the starting position again to form a hole in the workpiece.

``Problem to be Solved by the Invention'' However, for example, when forming a hole in a thick piece of wood using a laser beam, a small protrusion protruding toward the larger side is created at the cutting end position that is connected to the initial cutting start position. Sometimes it remained.

In other words, generally when cutting a workpiece with a laser beam, the focal position of the condensing lens built into the focus head is brought approximately to the surface of the workpiece, and the energy density of the laser beam at that part is adjusted. I'm trying to make it bigger.

As a result, the laser beam spreads out from the front side of the workpiece, which is the focus position of the condensing lens, to the back side, so the cutting width on the back side of the workpiece is larger than the cutting width on the front side of the workpiece. . However, the cut surface when forming a circular hole is
The lower part becomes a conical surface that expands.

In this case, the six small protrusions mentioned above will not remain on the conical surface, but if the wood is a die board used for cutting out cardboard etc., and the holes are If the die board has a round hole for fitting a cylindrical cutting blade, the cylindrical cutting blade will fit into the round hole with a conical surface, making it easy for the cutting blade to wobble. , undesirable.

In order to cut the inner circumferential surface of the round hole to be as cylindrical as possible, the workpiece may be cut at a relatively high speed. In other words, even in this case, the laser beam spreads out from the front side to the back side of the workpiece, but the cut surface is greatly affected by the flow of assist gas injected toward the cutting part, so the assist Gas is applied to the back side of the workpiece,
By setting the relative movement speed so that the laser beam moves relative to the workpiece when it penetrates with a cutting width similar to the cutting width on the surface side, the inner peripheral surface of the round hole can be cut as much as possible. It can be a cylindrical surface.

However, in this case, the cutting on the back side of the workpiece is delayed than the cutting on the front side, so the moment the cutting position on the front side returns to the starting position, the cutting position on the back side will be at a position just before the starting position. Become. The assist gas flows from the cutting end side to the cutting start side at the moment when the cutting on the back side continues to the original starting position, so that the assist gas pressure at the cutting ending position becomes insufficient and the combustion efficiency decreases. As a result, the cutting width at that portion on the back side becomes narrower, resulting in the formation of the above-mentioned small protrusion, and such a protrusion also causes the cutting blade to wobble.

The small protrusion formed on the inner circumferential surface of the hole can be scraped off with a laser beam, but if only the protrusion is scraped off, the scraped part and the other A slight step is formed at the boundary between the parts, which is not desirable.

On the other hand, by making the laser beam go around twice on the virtual circle of the hole, it is also possible to shave off the convex portion formed in the first round in the second round. In this case, the inner circumferential surface of the hole can be formed smoothly, but since the laser beam follows the same trajectory, the hole can be formed smoothly in the same way as when the laser beam is moved at a relatively low speed. The disadvantage is that the cut surface becomes a conical surface that is widened at the bottom.

"Means for Solving the Problems" In view of the above-mentioned circumstances, the present invention is directed to cutting the workpiece by irradiating a laser beam to the cutting start position of the workpiece, and returning the laser beam to the above-mentioned start position. The laser beam is continuously moved until it reaches the starting position to form a hole in the workpiece, and the laser beam is then moved from the starting position to the starting position again while scraping off the cut surface of the hole to make the hole a desired size. It was designed to be molded into a hole.

"Operation" According to the above configuration, the small convexity that is generated on the inner peripheral surface of the hole by cutting the workpiece at a relatively high speed is simultaneously removed by scraping off the six cut surfaces with a laser beam. Moreover, since the laser beam is used to scrape down the cut surface of the hole and form the hole into a hole of the required size, the inner circumferential surface of the hole is smooth and continuous. , it is possible to make the inner circumferential surface of the hole as flat as possible parallel to the optical axis of the laser beam.

``Example'' The present invention will be described below with reference to an illustrated example. In FIG. 3, a carbon dioxide laser processing machine 1 having a conventionally well-known configuration is configured to place a workpiece 2 on a horizontal surface in the X direction and A work table 3 is provided that is movable in the orthogonal Y direction, and a focus head 4 that is movable in the vertical Z direction is provided above the work table 3.

The movement of the work table 3 in the X-Y direction and the movement of the focus head 4 in the Z direction are each controlled by a control device 5.
The upper workpiece 2 is placed on the horizontal plane with respect to the laser beam.
It is relatively moved in the Y direction, and as shown in FIG. 1, a circular hole 6 having a desired diameter is formed.

When forming the hole 6, first, a laser beam is irradiated at a predetermined position inside the hole 6 to be formed to form a through hole 7, and then a laser beam is radiated onto the hole 6 to be formed. After moving to the predetermined cutting start position A, from there, cut the hole 6 in a circular shape with a slightly smaller diameter than the hole 6 until it reaches the start position A again.
It is moved circumferentially, thereby forming a small diameter 68.

At this time, by moving the laser beam at a high speed relative to the workpiece 2, as shown in FIG.
Although the laser beam originally spreads out from near the surface of the workpiece 2, which is the focal point of the condensing lens (not shown), to the back surface (see imaginary line), the flow of the assist gas causes the laser beam to spread out within 68 degrees. The circumferential surface can be made into a cylindrical surface as much as possible.

However, on the other hand, as shown in FIG. The convex portion 9 will remain.

Next, once the hole 8 is formed by making the laser beam go around once from the starting position A to the starting position A again, continue from the starting position A in the opposite direction to that in which the hole 8 was formed, i.e. The laser beam is moved counterclockwise in FIG. 1, and the cut surface of the hole 8 and the convex portion 9 are scraped off until the laser beam reaches the starting position A again. Shape into 6 pieces.

Therefore, the cutting start position A of the hole 8 and the cutting start position A of the hole 6 are at the same position, and the six 8 comes to be inscribed in the hole 6 at the cutting start position A.

The inner circumferential surface of the hole 6 thus formed becomes a smooth surface without the above-mentioned convex part 9 by continuous movement of the laser beam along the virtual circle of the hole 6, and the cut surface of the hole 68 is shaved off. Since it is formed in this way, 2
The inner circumferential surface can be formed into a cylindrical surface as much as possible without forming a conical surface unlike in the case where it is circumferential.

Furthermore, the width W of the inner circumferential surface of the hole 8 needs to be large enough to prevent the inner circumferential surface of the hole 6 from becoming a conical surface.
If the inner peripheral surface of the 68 is made so large that it cannot be scraped off, when the cutting line continues with the inner periphery of the 68, the continuous part will not continue smoothly, so set it in a range that will not cause such a problem. There is a need to. - As an example, if the workpiece is 180
In the case of a die board with a thickness of 1 [+1], the cutting width W is approximately 0.2 m.
m was suitable.

In addition, FIG. 4 shows a second embodiment of the present invention. In this second embodiment, after moving the laser beam clockwise to form 68, the laser beam is further moved in the same direction. The inner peripheral surface of the hole 8 is scraped off by moving in the direction, thereby scraping off the protrusion 9 and forming the hole 6.

This second embodiment also provides the same effects as the first embodiment.

"Effects of the Invention" As described above, according to the present invention, even if the workpiece is a thick wooden board, the inner peripheral surface is smooth and the optical axis of the laser beam is as close as possible to the workpiece. This provides the advantage of being able to form holes with parallel planes.

[Brief explanation of drawings]

Fig. 1 is a plan view showing one embodiment of the present invention, and Fig. 2 is a plan view showing an embodiment of the present invention.
FIG. 3 is a perspective view showing a conventionally known carbon dioxide laser processing machine, and FIG. 4 is a plan view showing another embodiment of the present invention. 1... Carbon dioxide laser processing machine 2... Workpiece 6.
8... Hole 9... Protrusion A... Cutting start position L... Laser beam W... Cutting width

Claims (1)

[Claims] The laser beam is irradiated to the cutting start position of the workpiece to cut the workpiece, and the laser beam is continuously moved again until the cutting start position is reached to form a hole in the workpiece, and then the A method for forming a hole using a laser beam, characterized in that the laser beam is moved from the starting position to the starting position again while scraping off the cut surface of the hole, thereby forming the hole into a hole of a desired size. .