JPH03221286A - Method and device for laser beam machining - Google Patents

Abstract

PURPOSE:To effectually reduce the time of a piercing process by setting the focus of laser beam to the surface of a material to be machined and making holes in a piercing process and moving the focus of the laser beam in a cutting process after holes are made and cutting the material to be machined. CONSTITUTION:The laser beam 1 generated in a laser beam oscillator is introduced as far as the material 3 to be machined. The surface of the material 3 to be machined is irradiated with the laser beam 1 and cut. The cutting process is composed of a piercing process and a cutting process. The focus F of the laser beam 1 is set to the surface of the material 3 to be machined and the holes are made on the way to the piercing process time or before the piercing process is completed. On the way to the piercing process or after it is completed, the focus F of the laser beam 1 is moved to the focal position of the laser beam 1 in a cutting process and cutting work is executed. In this way, the total hours of the laser beam machining process can be reduced drastically.

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 piercing 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 plate thickness increases, not only is a wider cutting width required, but the tolerance range for the laser beam focal position becomes narrower, so it is necessary to delicately adjust the laser beam focal position during cutting. The focal position of the laser beam during the drilling process and the focal position of the laser beam during cutting J8 are no longer compatible,
There is a problem with the piercing time being longer.

The present invention consists of 1. It is an object of the present invention to provide an excellent laser processing method and laser processing apparatus that can solve such conventional problems and 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 focuses the laser beam on the workpiece during or until the end of the drilling process. The structure is such that drilling is performed in accordance with the surface, and during or after the drilling process, the focal point of the laser beam is moved to the focal position of the laser beam during the cutting process to perform the cutting process.

Effects The present invention has the following effects due to the above structure. In other words, when the laser beam is focused on the surface of the workpiece, the depth that can be drilled with one pulse of the laser beam is deep, and the time for the drilling process is shortened. To effectively shorten the piercing time, that is, the time for the drilling process, by performing the drilling while focusing and moving the focal point of the laser beam to the focal position during the cutting process during or after the drilling process. I can do it.

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 focal position of the laser beam during the drilling process, and Fig. 1(b) shows the focal position of the laser beam during the cutting process. ing. Figure 1 (
In a), the laser beam 1 is focused F on the surface of the workpiece 3 by the condenser lens 2. In addition, in FIG. 1(b), the laser beam 1 moves its focal point F away from the surface of the workpiece 3 by moving the condensing lens 2.
They are aligned at a distance of r. In this way, the focus F of the laser beam 1 is adjusted during the drilling process (a) and during the cutting process (b).
By making these different, the time required for the cutting process using laser light can be shortened.

Next, the operation of the above embodiment will be explained. As mentioned above, as the plate thickness increases, the ratio of via sinking time to the cutting process increases, and the 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 width and plate thickness required for cutting in the case of SPC. The cutting width is determined by the thermal conductivity coefficient of the material, the plate thickness, and the mobility of the molten material by 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.
In the past, the focal position of laser light during the drilling process was often focused on the inside or outside of the workpiece. However, as shown in FIG. 3, as the focus of the laser beam moves away from its fixed focal position, the
Since the depth of the hole drilled per pulse becomes shallower, if the focal point is set inside or outside the workpiece, the piercing time will take longer. Therefore, as in the above embodiment, drilling is performed by focusing the laser beam on the surface of the workpiece, and after the drilling is completed, the focus of the laser beam is moved to a focal position corresponding to the cutting radius during the cutting process. 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 process is faster than the conventional method using a laser beam. The time can be reduced by about 10% or more. This tendency becomes more pronounced as the plate thickness increases; for example, in the case of a 9 mm thick iron plate (5PC), the cutting process time is reduced by about 30% or more.

FIG. 5 shows an example of the movement timing of the focal position of the laser beam in the embodiment. In this example, the focal position of the laser beam is moved after the drilling process is completed, but if the material is a material that allows the focal position of the laser beam to be moved during the drilling process, the time for the laser cutting process can be further shortened. I can do it.

The timing of movement of the focal position of the laser beam is determined by the material and thickness of the workpiece. therefore,
If there is information on the material and thickness of the workpiece, the movement 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 adjusting the focal position of the laser beam.

In FIG. 6, 1 is a laser beam, 2 is a condensing lens, 3 is a workpiece, 4 is a laser oscillator, 5 is a beam bender for guiding the laser beam 1 from the laser oscillator 4 to the condensing lens 2, 6 7 is a laser nozzle axis for holding the condensing lens 2 and guiding the laser beam 1 to the surface of the workpiece 3; 7 is a servo motor for moving the laser nozzle #I6 and adjusting the focal position of the condensing lens 2; , 8 holds the workpiece 3 and
A table for moving in the Y direction, 9 a servo motor for driving the table 8, 10 a numerical controller for controlling the servo motors 7 and 9, 11 a control system based on information on the material and thickness of the workpiece 3 12 is a CAD/CAM system for controlling the numerical controller 10 and the focus position database 11.

Next, the operation of the laser processing apparatus will be explained. The pulsed laser beam l emitted from the laser oscillator 4 is
The beam passes through a beam bender 5 and is focused into a spot by a condensing lens 2, and irradiates the surface of a workpiece 3. Workpiece 3
is heated and melted by the thermal energy of the focused laser beam 1 to form a hole. The laser beam 1 focused on the surface of the workpiece 3 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 1. When a hole is made in the workpiece 3, the table 8 moves according to the cutting pattern to perform cutting. This control is performed by the numerical control device 1 based on the cutting figure pattern stored in the CAD/C/\M system 12.
This is done by driving the servo motor 9 via 0. In addition, the adjustment of the black spot position of the condenser lens 2 during the drilling process and during the cutting process is performed by the number + If controller based on the material and plate thickness information of the workpiece 3 stored in the data mousse 11 at the focal position. This is done by driving the servo motor 7 via the motor 10. In this way, laser processing is performed in which the cutting process time is reduced by at least 10% compared to the conventional method. The focal position database 11 in the embodiment is stored in the CAD/CAM system 12.
It is also possible to provide it in a program manual support device attached to a laser processing device such as a laser processing device. If a database of focus positions is provided in such a programmable human assistance device, the benefits 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 the drilling process and the cutting process, and the laser beam is not used during or until the end of the drilling process. Drilling is performed by aligning the focus of the laser beam with the surface of the workpiece, and during or after the drilling process, the focus of the laser beam is moved to the focal position of the laser beam during the cutting process to perform cutting. Since the time during the drilling process can be effectively shortened, the overall time of the laser machining process can be significantly shortened, thereby dramatically improving productivity.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are conceptual diagrams showing the relationship between the focal position of the laser beam and the workpiece during the drilling process and cutting process in an embodiment of the laser processing method of the present invention, and FIG. Figure 3 is a graph showing the relationship between the thickness of the workpiece and the required cutting width in the laser processing method, and Figure 3 shows the distance between the workpiece/focal position and the depth of the hole drilled with one pulse of laser light in the laser processing method. Figure 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), Figure 5 is the drilling process and cutting in one embodiment of the present invention. A timing chart showing the timing of the process, and FIG. 6 is a schematic block diagram showing the system configuration in an embodiment of the laser processing method of the present invention. DESCRIPTION OF SYMBOLS 1...Laser beam, 2...Condenser lens, 3...Workpiece, 4...Laser oscillator, 5...Beam bender, 6...Beam nozzle axis, 7...Servo motor, 8
...Table, 9...Servo motor, 10...Numerical controller,...Focus position data, 12...CAD, / CAM system, F...Focus.

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. During or after the drilling process, the laser beam is focused on the surface of the workpiece to perform drilling, and during or after the drilling process, the laser beam is focused on the surface of the workpiece during the cutting process. A laser processing method that performs cutting by moving to the focal position of the laser beam. (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, a means for adjusting the focal position of the laser beam, and a hole drilling process in the cutting process. During the drilling process, the focus of the laser beam is aligned with the surface of the workpiece to perform drilling, and during or after the drilling process, the focus of the laser beam is moved to the focal position of the laser beam during the cutting process for cutting. A laser processing device comprising a control means for controlling each of the means to perform processing.