JPH03216288A - Laser processing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a method of condensing laser light and performing laser processing such as cutting and drilling into a ring shape.

``Conventional technology'' In conventional conventional laser processing machines, parallel laser beams with a cylindrical beam intensity distribution are focused into a spot (single point) using a lens, and the workpiece is irradiated and cut. , performs laser processing such as welding and surface treatment.

By the way, when performing ring-shaped laser processing, that is, cutting, welding, and surface treatment, the workpiece is placed on a stage and rotated around a point away from a fixed spot, or the entire processing head is rotated in a circular shape. The focusing spot can be moved over the workpiece in a ring shape, or a special optical component called an axicon lens that has the function of focusing a cylindrical parallel beam of light into a ring shape can be used. It was being processed.

In response to this, the present inventor invented and filed an application for a method of rotating an eccentric lens around the optical axis, that is, a lens having a spherical surface with one side inclined to a plane perpendicular to the optical axis or an axis inclined to the optical axis. .

``Problems to be solved by the invention'' However, creating a mechanism to place the workpiece on a stage and rotate it, or to move the entire processing head in a circumferential manner, requires a large amount of space and weight, which increases cost. There is a problem.

On the other hand, when using an axicon lens or a lens whose one side is inclined with respect to a plane perpendicular to the optical axis, there is a problem that the shape of the lens is complicated, making it difficult to manufacture and increasing the cost of the lens.

"Means for Solving the Problem" This invention provides a lens and a prism that are placed close to each other and focuses a light spot at a position displaced from the optical axis, without rotating the workpiece or moving the entire processing head in a ring shape. This is a processing method characterized by moving the focused spot of the laser beam on the workpiece in a ring shape by rotating the prism or the lens and the prism together around the optical axis. , which eliminates the drawbacks of the conventional method.

Specific examples of the present invention will be explained below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a processing head for the present invention, and FIG. 3 is a drawing showing the principle thereof.

As shown in FIG. 1, the lens (1) is fixed to the processing head body (3) with its optical axis aligned. a prism (2) close to the lens (1) with planes on both sides inclined to each other;
is attached to a prism mount (4), and the prism mount (4) is rotatably held around the processing head body (3). This prism mount is meshed. When the pinion gear (5) is driven and rotated by the shaft (6), the prism mount 4) and the prism (2) rotate around the optical axis. The axis of the processing head body (3) is aligned with the incident axis of light, that is, the optical axis, and the lens (
1) is formed from a spherical surface and a plane whose center of curvature is a point on the optical axis.

The principle of this lens+prism optical system is shown in FIG. As shown in the figure, a laser beam (7
) is focused by the lens (1), but the focused light beam is slightly biased by the prism (2), and the optical axis and displacement r
The light is focused at a position shifted by the amount, that is, the focal point F. In this case, the focal length of the lens is f, the declination angle of both sides of the pnosm is θ,
If the distance from the prism to the focal point of the lens is fp1 and the refractive index of the material of the prism is n, then the focal spot of this optical system has a displacement r, r approximately expressed by the following formula when 0 is small.
The light is focused on a focal point F at a position shifted from the optical axis by =(n-1)θfp. The shorter the distance between the lens and prism, the larger the fp value.
This means that a smaller deflection angle θ is sufficient to obtain the same r.

Also, by adjusting this interval, the deviation r of the focal point F from the optical axis can be adjusted.

In this optical system, when the pinion gear (5) is driven to rotate the prism (2) around the optical axis, the condensed spot draws a circle with a radius r.

FIG. 2 shows another specific example. In this case, lens (1) and prism (2) have the same prism mount (
4), and is rotatable within the processing head body (3). With this structure, the focal point F of the laser beam is also displaced from the optical axis, and the effect does not change even if the lens is rotated. Therefore, when the prism mount (4) on which the lens and prism are attached is rotated, the focal point F is displaced from the optical axis. can be drawn.

"Operation" When the processing head of the present invention is used, the laser beam is focused at a position displaced by r from the optical axis, so the prism alone is rotated about the optical axis using a pinion, or the lens and When the prism combination is rotated together, the spot of laser light on the surface of the workpiece placed in the plane of focus can be fixed with a radius r around the optical axis without moving the entire processing head or moving the workpiece. It can be moved around the circumference. Therefore, a workpiece can be processed into a ring shape using this method.

Although the case where a plano-convex lens is used as the lens is illustrated above, a normal lens having spherical surfaces on both sides may be used. Furthermore, although a case has been described in which the prism mount is rotated by coupling a gear and a pinion, in short, it is sufficient to rotate the lens around the optical axis, and it goes without saying that any rotation mechanism for this purpose may be used.

"Effects of the Invention" As explained in detail above, the present invention uses an optical system that combines a lens and a prism to create a laser beam spot at a position off the optical axis, and uses the prism alone or the lens and prism together. The spot can be moved in a ring shape simply by rotating the beam around the optical axis, so it is extremely effective when used for laser processing such as cutting the workpiece into a ring shape and surface treatment. It is something.

Furthermore, it is convenient because it is possible to adjust the deviation of the focused spot of the laser beam from the optical axis simply by adjusting the distance between the lens and the prism.

[Brief explanation of drawings]

1 and 2 are sectional views of a specific example of the present invention, and FIG. 3 is a principle diagram showing the principle thereof. 1: Lens 2: Prism 3: υ mouth part body 4: Prism mount 5: Pinion axis 6: Axis 7: Laser beam θ: Inclination angle F: Focus f: Focal length fp: Distance between prism and focal point r: Focal shift

Claims (1)

[Claims] 1. Ring the workpiece with a laser beam spot
A laser processing method for processing a lens and a prism in close proximity to each other, and processing by rotating the prism alone or both together to move a focused spot displaced from the optical axis in a ring shape. Laser processing method 2, the laser processing method according to claim 1, characterized in that the distance between the lens and the prism is adjusted to adjust the amount of displacement of the condensed spot from the optical axis.