JPH03221287A - Method and device for laser beam machining - Google Patents

Abstract

PURPOSE:To reduce the whole time of a cutting process by setting a laser beam irradiating mode to a single mode to pierce a hole in a piercing process time and changing the irradiating mode into a multi-mode to cut a work piece after the piercing process is completed. CONSTITUTION:The laser beam 1 generated in a laser beam oscillator is introduced as far as a material to be machined. The surface of the material to be machined is irradiated with the laser beam 1 to be cut-off. The cutting process is composed of a piercing process and a cutting-off process. In the piercing process time, the irradiating mode of the laser beam 1 is changed to a single mode with a mode changing plate 2 to pierce the hole. After the piercing process, the irradiating mode is changed by the mode changing plate 2 to the multi-mode to perform cutting-off. In this way, the productivity can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laser processing method and a laser processing apparatus for cutting a workpiece using laser light.

Conventional technology: When cutting a workpiece by irradiating it with laser light,
First, the first step is to drill a hole in the specified position of the workpiece.
Cutting then begins at the perforated area according to the cutting pattern. The hole-making step at this time is called piercing, and although it depends on the cutting pattern, it is not uncommon for it to occupy about half of the total time of the cutting process. In particular, as the plate thickness increases, the ratio of piercing time to cutting process increases, and piercing time comes to dominate most of the cutting process time. Therefore, shortening the viasing time greatly contributes to shortening the time of the cutting process and improves the efficiency of the cutting process.

Problems to be Solved by the Invention However, conventional laser processing methods and laser processing apparatuses do not have effective means for shortening the piercing time when the plate thickness becomes thick. In addition, as the thickness of the plate increases, a wider cutting radius is required, so the focal position of the laser beam is intentionally shifted from the surface of the workpiece to increase the spot diameter of the laser beam. There was a problem in that the piercing time decreased and the piercing time took longer.

The present invention solves such conventional problems, and aims to provide an excellent laser processing method and laser processing apparatus that can effectively shorten piercing time.

Means for Solving the Problems In order to achieve the above object, the present invention divides the cutting process into a drilling process and a cutting process, and in the drilling process, performs the drilling process by setting the laser beam irradiation mode to a single mode, After the drilling process is completed, the laser beam irradiation mode is switched to multimode to perform cutting.

Effects The present invention has the following effects due to the above structure. In other words, during the drilling process, a single mode laser beam with a small spot diameter is irradiated onto the surface of the workpiece.
The depth that can be drilled with one pulse of laser light increases,
The time for the drilling process is reduced. Further, during the cutting process, since the cutting process is performed using a multi-mode laser beam with a large spot diameter, the cutting radius necessary for cutting the workpiece can be obtained. Due to this, the piercing time, that is, the time for the drilling process can be effectively shortened, and the time for the entire cutting process can be shortened.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention, FIG. 1(a) shows the laser light irradiation mode during the drilling process, and FIG. 1(b) shows the laser light irradiation mode during the cutting process. ing. 1st
In Figure (a), a laser beam 1 is focused to have a spot diameter d by a mode switching aperture plate 2, and its intensity distribution becomes a single mode with one peak on the optical axis 3. In addition, in FIG. 1(b), the laser beam 1 is emitted with the spot diameter unchanged without being subjected to the aperture effect by the mode switching aperture plate 2, and its intensity distribution has two peaks on both sides of the optical axis 3. It has multi-mode. In this way, the spot diameter of the laser beam l is adjusted during the drilling process (a)
By making the time and the time of the cutting process different (b), it is possible to shorten the overall time of the cutting process using a laser beam.

Next, the operation of the above embodiment will be explained. As mentioned above, as the plate thickness increases, the ratio of piercing time to cutting process increases, and piercing time comes to dominate most of the cutting process time. Furthermore, as the plate thickness increases, a wider cutting width is required.

FIG. 2 shows the relationship between the cutting radius and plate thickness required for SPC cutting. The cutting radius is determined by the thermal conductivity coefficient of the material, the plate thickness, and the mobility of the molten material due to the assist gas. Since the assist gas conditions are limited by the oxidation reaction rate of the material, the cutting width is almost uniquely determined by specifying the material and plate thickness.

In this way, as the plate thickness increases, not only does the drilling process take up a larger proportion of the board, but a wider cutting width is required.
Conventionally, the spot diameter of the laser beam during the drilling process is often increased.

However, as shown in Figure 3, as the spot diameter of the laser beam increases, the depth of the hole that can be drilled per pulse of the laser beam becomes shallower. , the piercing time will take longer. Therefore, as in the above embodiment, during the drilling process, drilling is performed in a single mode with a small spot diameter, and after the drilling process is completed, the laser beam irradiation mode is switched to multimode and cutting is performed with a large spot diameter. As shown in Figure 4, for example, when drilling a 15 mm circular hole in a 4.5 mm thick steel plate (SPC), the cutting time is reduced by approximately 20% or more compared to the conventional method using laser light. be able to. This tendency becomes more pronounced as the plate thickness increases; for example, in the case of a 9 mm thick steel plate (SPC), the cutting process time is reduced by about 50% or more.

FIG. 5 shows an example of the switching timing of the laser beam irradiation mode in the embodiment. In this example, the laser beam irradiation mode is switched after the drilling process is completed.

The switching timing of this laser beam irradiation mode is determined by the material and thickness of the workpiece. Therefore, if there is information on the material and thickness of the workpiece, the switching timing can be uniquely determined.

FIG. 6 shows an example of a laser processing apparatus equipped with a database for generating such timing and means for automatically switching the laser beam irradiation mode. In FIG. 6, 11 is a laser beam, 1
2 is a condensing lens; 13 is a workpiece; 14 is a laser oscillator; 15 is a mode switcher equipped with an aperture plate for switching the irradiation mode of the laser beam 11 from the laser oscillator 14;
16 is a beam bender for guiding the laser beam 11 to the condensing lens 12; 17 is a beam nozzle axis for holding the condensing lens 12 and directing the laser beam 11 toward the workpiece 13; 18 is the workpiece 13, a servo motor for driving the table 18; 20, a numerical control device for controlling the servo motor 19 and the mode switch 15; 21, a workpiece 13 is a mode switching database for determining the aperture plate cutting amount in the mode switching device 15 based on information on the material and plate thickness; 22 is a CA D/CA for controlling the numerical controller 20 and the mode switching database 21;
This is the M system.

Next, the operation of the laser processing apparatus will be explained. Pulsed laser light 11 emitted from a laser oscillator 14
The irradiation mode is controlled by the irradiation mode switch 15, and the surface of the workpiece 13 is irradiated in a spot shape. The workpiece 13 is heated and melted by the thermal energy of the irradiated laser beam 11 to form a hole. The laser beam 11 focused on the surface of the workpiece 13 has the highest energy density at its focal position, and the energy is proportional to the square of the spot diameter of the laser beam 11. When a hole is made in the workpiece 13, the table 18 moves according to the cutting pattern to perform cutting.

This control is controlled by the OFF1! stored within the CAD/CAM system 22. Based on the Jr figure pattern, the numerical control device 20
This is done by driving the servo motor 19 via the servo motor 19. In addition, the laser beam 1 during the drilling process and the cutting process
The switching of the first irradiation mode is performed by the mode switching device 15 via the numerical control device 20 based on the material and plate thickness information of the workpiece 13 stored in the mode switching database 21.
This is done by driving the . In this way, laser processing is performed in which the cutting process time is reduced by at least 20% compared to the conventional method.

The mode switching database 21 in the embodiment is C
It is also possible to provide it in a program input support device attached to a laser processing device such as the AD/CAM system 22. When the mode switching database is provided in such a program input support device, the advantage of the present invention of shortening the time of the laser cutting process can be enjoyed even when a conventional laser processing device is used.

Effects of the Invention As is clear from the above explanation, according to the laser processing method and laser processing apparatus of the present invention, the cutting process is divided into a drilling process and a cutting process, and the laser beam irradiation mode is changed in the drilling process. Drilling is performed with a small spot diameter in single mode, and after the drilling process is completed, the laser beam irradiation mode is switched to multimode and cutting is performed with a spot diameter that corresponds to the cutting width required to cut the workpiece. Since the time during the drilling process can be effectively shortened, the time for the entire cutting process can be significantly shortened, thereby dramatically improving productivity.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are explanatory diagrams showing the relationship between the laser beam spot diameter and the intensity distribution during the drilling process and cutting process in an embodiment of the laser processing method of the present invention, and FIG. A graph showing the relationship between the thickness of the workpiece and the required cutting width in the laser processing method, Figure @3 shows the relationship between the spot diameter of the laser beam and the depth of the hole drilled with one pulse of laser light in the laser processing method. FIG. 4 is a graph showing the relationship between the thickness of the workpiece and the time reduction rate of the present invention (compared to conventional technology), and FIG. 5 is the timing of the drilling process and cutting process in one embodiment of the present invention. Timing chart showing
FIG. 6 is an illumination block diagram showing the system configuration of an embodiment of the laser processing apparatus of the present invention. 1...Laser beam, 2...Mode switching aperture plate, 3...
・Light ψ#, 11... Laser light, 12... Condensing lens, 13... Workpiece, 14... Laser oscillator, 15
...Mode switch, 16...Beam bender 17
...Beam nozzle axis, 18...Table, 19...
・Servo motor, 20... Numerical control device, 21...
Mode switching database, 22... CAD/CAM system, 1... Spot diameter.

Claims (2)

[Claims] (1) It has a cutting process in which a laser beam generated by a laser oscillator is guided to a workpiece and the surface of the workpiece is cut by irradiating the laser beam, and the cutting process is a drilling process and a cutting process. A laser processing method that consists of several steps: during the drilling process, the laser beam irradiation mode is set to single mode to perform drilling, and after the drilling process is completed, the irradiation mode is switched to multimode to perform cutting. (2) A means for guiding a laser beam generated by a laser oscillator to a workpiece and irradiating the surface of the workpiece with the laser beam, and changing the irradiation mode of the laser beam to a single mode during the drilling process in the cutting process. A laser processing device is provided with a means for performing hole-drilling and switching to perform cutting in a multi-mode after the hole-drilling process is completed.