JPS6046892A - Irradiating method of laser light - Google Patents

Abstract

PURPOSE:To form a satisfactory temp. distribution to a work and to improve working efficiency by compressing laser light of an annular mode in one direction to form a flat spot and irradiating such light to the work. CONSTITUTION:Laser light 1 of an annular mode oscillated by a laser oscillator 2 is condensed to a spot 4 of a slender shape by a cylindrical lens 3 having a semi-circular cylindrical shape so that the energy distribution thereof is made into a saddle shape having a peak on the outside. When such spot 4 is irradiated to a work 5, the surface temp. distribution of the work 5 has a trapezoidal shape indicating a uniform temp. distribution on account of thermal diffusion outside the irradiating area of the work 5, thereby expanding the max. tem. width. A stable heat treatment is thus accomplished.

Description

[Detailed description of the invention] The present invention relates to a laser beam irradiation method.

For example, when laser light is focused using a convex lens and irradiated onto a workpiece, the energy distribution of the spot irradiated onto the workpiece is similar to that when the laser beam is emitted from a laser oscillator. In other words, the energy distribution of the spot is bell-shaped, with the center being high and the periphery being low. Laser light with such an energy distribution has the following problems in heat treatment. As is well known, heat treatment is performed at a specific temperature that exceeds the transformation point of the processed metal, but if the heat treatment width of the above spot is widened, the temperature difference between the transformation point temperature boundary part and the center part of the above spot becomes large. Become,
The central portion reaches a melting temperature, making it unsuitable for heat treatment. Also, if the temperature at the center is brought closer to the transformation point temperature,
Due to the bell-shaped nature of the energy distribution, the effective heat treatment range becomes narrow.

This invention was developed in order to solve the above-mentioned drawbacks, and the laser beam in the ring mode is made into a flat and compressed spot, and the workpiece is irradiated with the focused spot with a good energy distribution, thereby achieving a good temperature distribution. is formed on the workpiece to improve processing efficiency.

The present invention will be explained below with reference to Examples.

FIG. 1 shows the configuration of an apparatus suitable for carrying out the present invention. 1 It has an oscillator (2) that oscillates a ring-mode laser beam (1) obtained from an unstable resonator, for example,
This oscillator (1) also serves as a condensing lens (3) that condenses the oscillated laser beam (1). The above condensing lens (
3) is a so-called cylindrical lens having a semi-cylindrical shape formed by longitudinally cutting a cylindrical material.

In the above device, the ring-shaped laser beam (1,) is focused on a long and narrow spot (4) by a condensing lens (3),
The energy distribution becomes branch-like with peaks on the outside as shown in FIG. When the workpiece (5) is irradiated with this spot (4), the temperature distribution on the surface of the workpiece (5) is changed by the solid line (a) in Figure 3 due to heat diffusion outside the irradiation area of the spot (4).
) with a trapezoidal shape showing a uniform temperature distribution, and the maximum temperature range is extremely expanded. In the prior art, the irradiation spot focuses on the temperature distribution shown by the broken line (b) in FIG. Therefore, in the above two temperature distributions, if the dot-dash line (C) in Fig. 3 is taken as the transformation point of the workpiece, the temperature distribution ('b) is the same. Since the temperature difference between the center of the irradiation point on the object surface and the above transformation point is small, stable heat treatment can be performed. Furthermore, in the invention, the boundary between the heat-treated portion and the non-heat-treated portion is made clear, and sharp heat treatment can be performed.

Although a cylindrical lens is used in the above embodiment, the same effect as described above can be obtained by using an optical system or a reflecting mirror having the same function as the cylindrical lens.

Furthermore, this invention can not only be used for heat treatment, but also for drilling by using the output of a laser oscillator.

Needless to say, it can be applied to processes such as bevel cutting and cutting.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the main parts of a device suitable for carrying out the present invention, Fig. 2 is an energy distribution diagram of the laser beam focused by the above device, and Fig. 3 is a laser spot irradiated onto the surface of the workpiece. FIG. (1)... Laser light (2)... Laser oscillator (3
)...Cylindrical lens agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2 Yuzu diagram

Claims (1)

[Claims] A laser beam irradiation method characterized by irradiating a workpiece with a ring-shaped laser beam in a flat spot using an optical system that compresses it in one direction.