JPS60257986A - Optical device for laser beam machining - Google Patents

Abstract

PURPOSE:To make the shape of a cutting part good and to prevent the generation of dross by constituting the titled device with a condenser lens of laser beam and a rotary plate and by specifying the relation among the refractive index and thickness of a rotary plate and the plate thickness of a body to be worked. CONSTITUTION:A rotary plate 18 is rotated with the condition of intersecting at right angles with an optical axis 9 of laser beam 1, which passes through alternately the member 11 of the rotary plate 18 and a space 15. The constitution is made in order that the relation of (n-1)t/n T is established, in case the refractive index of a plate shaped-member as (n), the plate thickness as (t) and the plate thickness of a body to be worked as T. The laser machining is thus performed with forming the spot of laser beam alternately on the positions of upper face and lower face of the body to be worked. Accordingly the temp. on the lower face of the body to be worked is raised enough and the cut width of a working part becomes uniform and the dross as well is hardly caused.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical device for laser processing in the field of laser processing using carbon dioxide lasers, YAG lasers, and the like.

Conventional configuration and its problems In laser processing, a laser beam with excellent directivity and focusing properties is focused onto a minute spot with high energy density using a focusing lens, and this spot is then This is thermal processing performed by irradiating the workpiece. Therefore, it is possible to cut a wide range of materials, including not only metals but also ceramics and glass, and has recently been increasingly introduced.

There are various parameters in laser cutting processing, but among them, the positional relationship between the laser spot and the workpiece has a great influence on the quality and ability of laser processing.
well known.

In Fig. 1, 1 is a laser beam emitted from a laser oscillator (not shown), 2 is a condensing lens for condensing this laser beam onto a minute spot, and 3 is a laser beam formed by this condensing lens. It is a laser spot. 4 is a plate-shaped workpiece.

According to experiments, when the position of the laser spot 3 is above or below the surface 6 of the workpiece 40, the processing quality of the cutting process is as follows: When the position of the laser spot 3 is above the surface 6 In both cases, the laser spot 3 is located exactly on the surface 6 of the workpiece 4 during processing.

The cross section of the processed part of the workpiece 4 at that time is shown in FIG. 2. As shown in FIG. It gets narrower towards 6. Further, on the lower surface 6, adhesion of dross 7 is observed.

The reason why the shape of the cut portion becomes tapered in this way is thought to be due to the temperature distribution of the cut portion. That is,
This is considered to be because the temperature inside the workpiece 4 during laser processing decreases as it approaches the lower surface 6 of the workpiece 4 due to heat conduction. Also, the reason why dross 7 adheres is
This is considered to be because the workpiece is not sufficiently evaporated at the cut portion near the lower surface 6, and a portion of the workpiece solidifies from a molten state.

On the other hand, from the viewpoint of processing, the tapered shape of the cut portion and the adhesion of dross are extremely inconvenient in order to maintain good dimensional accuracy and processing quality.

Conventionally, various studies have been made to solve these various disadvantages.

For example, it has been found that the adhesion of dross can be considerably reduced by performing laser processing with another plate material in close contact with the lower surface 6 of the workpiece, but this requires extra material. It's not realistic.

OBJECTS OF THE INVENTION The present invention has been made to solve these inconveniences, and for this purpose, it is an object of the present invention to provide a simple optical device for laser processing.

Structure of the Invention The present invention is composed of a lens for condensing a laser beam and one rotating plate, and this rotating plate is a plate-shaped member made of a substantially transparent material with respect to laser beam=1. Instead of the center of rotation of the rotary plate, they are arranged side by side in the direction of rotation.

61\Description of an Embodiment As shown in the figure, the turning plate 18 is arranged approximately perpendicular to the optical axis 9. FIG. 4 is a view of the rotary plate 18 in the direction of arrow A, in which a plate-shaped member 11 made of a material that is almost transparent to the laser beam is arranged around the rotation center 10 in the rotation direction 12.
are arranged in the direction of The material of the member 11 may be any material as long as it is substantially transparent to the laser beam and has a refractive index different from that of air; for example, glass may be used for a YAG laser, and Zn5e may be used for a carbon dioxide laser. 13.14 is a ring and a disk connecting the outer periphery of each plate member 11, and each member 11 is connected to the ring 13.
9 is fixed to the disc 14 with an adhesive. A space 16 is provided between each member 11.

Now, as shown in FIG. 3, as a result of the rotating plate 18 configured as described above being rotated in a state substantially perpendicular to the optical axis 9 of the laser beam, the laser beam 1 is The laser beam 16 when passing through the member 11 and the space 16 alternately has a laser spot position of -(n-1) compared to the laser beam 17 when passing through the space 16.
It comes down by t. Therefore, if the thickness of the workpiece is T, then by setting the thickness of the member 11 to nT-, the interval between the spot positions of the laser beam 1617-1 becomes exactly T. In other words, by using this optical device, the laser beam spot is formed alternately on the upper and lower surfaces of the workpiece, and as a result, the temperature on the lower surface of the workpiece increases sufficiently. However, the cutting width of the processed part' is more uniform than in the past, and almost no dross is generated.

The table below shows a comparison between conventional processing and processing using the optical system of this example. As can be seen from this, this device has great effects and is of great benefit in industry.

Material SPCto, 5mm As a result of the invention, the temperature at the bottom of the workpiece increases sufficiently, the cutting width of the processed part becomes more uniform than before, and there is less dross. Almost never occurs.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of a conventional laser processing optical device, Fig. 2 is a new side view of a workpiece processed with the same device, and Fig. 3 is a laser processing optical device according to an embodiment of the present invention. 4 is a view seen from the entrance direction of FIG. 3, and FIG. 6 is a diagram for explaining the device. 18... Rotating plate, 8... mark motor, 9...
...Optical axis, 10... Center of rotation, 11 Old...
Plate member, 13・River...Ring, 14...Disc. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 3 Figure 4

Claims (1)

[Claims] Between a condensing lens for condensing a laser beam emitted from a laser oscillator and a laser spot formed by this condensing lens, the lens is driven by a motor or the like so as to be substantially perpendicular to the optical axis of the laser beam. A rotary plate is disposed, and the rotary plate holds a plurality of plate-shaped members made of a material that is substantially transparent to the laser beam and has a refractive index different from that of air, at a center of rotation of the rotary plate. around,
They are arranged so as to be spaced apart from each other by a certain distance in the rotational direction, and further, the refractive index n and the plate thickness t of the plate-shaped member are such that the plate thickness T of the workpiece is (n- 1) An optical device for laser processing configured so that the relationship of T is established.