JPH07164179A - Laser beam processing method and laser beam machine - Google Patents

Abstract

PURPOSE:To provide a laser beam processing method and laser beam machine capable of supplying a sufficient assist gas even to the molten part in the lower layer area of a work. CONSTITUTION:A gas cylinder 90 is connected to a processing head 1 and the assist gas is supplied at the time of processing. Oxygen (O2) is used for the assist gas. The nozzle of the processing head 1 has an assist gas injection port widely opened in one way from the beam center. A CPU 40 interprets a processing program and calculates the moving direction of the processing head 1. The CPU commands an axial control circuit 50 in such a manner that the widely opened part of the assist gas injection port exists backward of a progressing direction at all times. This axial control circuit 50 controls the rotation of a servo motor via a servo amplifier 51. As a result, the much assist gas is blown backward the progressing direction, by which the sufficient assist gas is supplied even to the molten part in the lower layer area of the work and the melting by oxidation heat is accelerated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-dimensional laser processing method and a laser processing apparatus for focusing a laser beam to process a work, and more particularly to a laser processing method and a laser processing apparatus in which an assist gas injection method is improved.

[0002]

2. Description of the Related Art Laser processing involves irradiating a very small portion of a work with a laser beam having a high-density energy obtained by generating monochromatic light with extremely aligned phases and condensing it with a condenser lens. Then, it is a processing method of evaporating and melting the work. Since the laser beam has good controllability, by controlling the laser processing with a numerical controller,
It is possible to process complicated shapes and perform precision fine processing. Then, as a method of more efficiently performing laser processing, there is a method of using oxygen as an assist gas for promoting melting of the work. That is, the melting of the work is promoted by the heat of the laser and the heat of oxidation. Laser processing has come to be used in a wide range of fields, and along with it,
There is a demand for cutting thicker plates and cutting at higher speeds.

FIG. 7 is a view showing cutting processing by a conventional laser processing apparatus. In the figure, the processing head 10a is moving in the direction of the arrow. A condensing lens 12a is fixed to the processing head 10a, and a perfect circular assist gas injection port 19a which also serves as an irradiation path of the laser beam 11a is provided at the tip of the nozzle. Input laser beam 11
a is condensed by the condenser lens 12a, and the work 20a
Is irradiated. The shaded portion of the work 20a is an uncut portion, and 21a is a cut portion. The black-painted portion 22a is being cut. That is, the work is melted in the area 22a. By blowing the assist gas 13a to the molten part of the work, the melting due to the heat of oxidation is promoted to improve the cutting speed, or it is possible to process a thicker work.

[0004]

However, when the work becomes a thick plate, the melting in the lower layer region of the work is significantly delayed as compared with the upper layer, but the assist gas injection port at the tip of the conventional laser processing apparatus is a perfect circle. The assist gas is injected concentrically around the laser beam and is always sprayed in the same way regardless of the processing direction, and the assist gas does not reach the lower layer. Therefore, the assist gas can accelerate the melting only in the portion irradiated with the laser beam and the vicinity thereof. Then, the thicker the plate of the work, the less the effect of promoting the melting of the oxidation heat by the assist gas in the lower layer region. That has been an obstacle to cutting planks. Also, in the case of cutting a work having a normal thickness, the melting of the lower layer portion is slower than that of the upper layer portion. Then, when cutting at high speed, the delay of melting becomes remarkable. Therefore, there is a problem that it is difficult to increase the cutting speed.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a laser processing method capable of supplying a sufficient assist gas to a molten portion in a lower layer region of a work. .

Another object of the present invention is to provide a laser processing apparatus capable of supplying a sufficient assist gas to the molten portion in the lower layer region of the work.

[0007]

In order to solve the above problems, the present invention provides a laser machining method for machining a workpiece using a nozzle for ejecting an assist gas together with a laser beam from the same opening. Laser which is characterized in that an assist gas injection port which is wide open in a direction is used and the nozzle is rotated so that the wide open part of the assist gas injection port is always located rearward with respect to the traveling direction of processing. A processing method is provided.

Further, in a laser processing apparatus for processing a workpiece by using a nozzle for ejecting an assist gas together with a laser beam from the same opening, a nozzle provided with an assist gas injection port wide open in one direction from the beam center. A pre-processing means for decoding the machining program, an interpolation means for outputting the movement of each axis of the machining program as a pulse, a traveling direction of the machining based on the moving direction of each axis, and rotating the nozzle to perform the assist. There is provided a laser processing device comprising: a rotation control unit that always positions a wide opening portion of the gas injection port rearward with respect to a traveling direction of processing.

[0009]

In the laser processing method in which the workpiece is processed using the nozzle that ejects the assist gas together with the laser beam from the same opening, the assist gas injection port that is wide open in one direction from the beam center is used. Then, the rotation control is performed so that the wide opening portion of the assist gas injection port is always located rearward with respect to the traveling direction of the processing. As a result, a large amount of assist gas can be blown backward in the traveling direction, sufficient assist gas is supplied to the molten portion in the lower layer region of the work, and more heat of oxidation is generated to promote melting.

Further, in a laser machining apparatus for machining a workpiece by using a nozzle for ejecting an assist gas together with a laser beam from the same opening, the nozzle is provided with an assist gas jet opening wide in one direction from the beam center. . The preprocessing means decodes the machining program. And
The interpolation means outputs the movement of each axis of the machining program as a pulse. The rotation of the servo motor for each axis is controlled by the pulse output. Further, the processing head is provided with a servo motor for rotating the nozzle. The rotation control means determines the traveling direction of the machining from the moving direction of each of the axes, rotates the servomotor provided in the machining head, and causes the widely opened portion of the assist gas injection port to move in the traveling direction of the machining. Always be in the rear. As a result, a large amount of assist gas can be blown backward in the traveling direction,
Sufficient assist gas is also supplied to the melted portion in the lower region of the work to generate more heat of oxidation and promote melting.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an NC laser device according to an embodiment of the present invention. In the figure, a processor (CPU) 40 reads a machining program stored in a random access memory (RAM) 42 based on a control program stored in a read-only memory (ROM) 41, and operates the entire NC laser device. Control. The output control circuit 60 has a built-in D / A converter, and converts the output command value output from the processor 40 into a current command value and outputs the current command value. The excitation power supply 61 rectifies the commercial power supply and then performs a switching operation to generate a high frequency voltage, and supplies a high frequency current according to the current command value to the discharge tube 66.

The laser gas 65 circulates inside the discharge tube 66, and when a high frequency voltage is applied from the excitation power source 61, a discharge is generated and the laser gas 65 is excited. The rear mirror 64 is a germanium (Ge) mirror having a reflectance of 99.5%, and the output mirror 67 is zinc selenium (ZnS) having a reflectance of 65%.
e) mirrors, which form a Fabry-Perot resonator and are emitted from the excited laser gas molecules 1
The 0.6 μm light is amplified and a part of the light is output from the output mirror 67 to the outside as the laser light 11.

The output laser beam 11 is changed in direction by a bender mirror 68, and is focused on a spot of 0.2 mm or less by a focusing lens inside the processing head 1 to be worked 20.
Is irradiated on the surface of.

The axis control circuit 70 controls the rotation of the servomotor 72 via the servo amplifier 71 in response to a command from the CPU 40, the movement of the table 75 by the ball screw 74 and the nut 73, and the position of the work 20. In the figure, only the x-axis is displayed, but in reality y, z
There is also a control axis. A CRT, a liquid crystal display device, or the like is used as the display device 80.

The power sensor 63 is composed of a thermoelectric or photoelectric conversion element or the like, and inputs the laser light partially transmitted from the rear mirror 64 and outputs it, and measures the output power of the laser light 11. The A / D converter 62 converts the output of the power sensor 63 into a digital value and inputs it to the CPU 40.

A gas cylinder 90 is connected to the processing head 1, and an assist gas is supplied during processing. Oxygen (O ₂ ) is used as this assist gas. The nozzle of the processing head 1 has an assist gas injection port that is wide open in one direction from the beam center, and the assist gas injection port also serves as the laser beam output port. The CPU 40 calculates the moving direction of the processing head 1 by decoding the processing program. Then, the axis control circuit 50 is instructed so that the wide open portion of the assist gas injection port is always positioned rearward in the traveling direction. The axis control circuit 50 controls the rotation of the servo motor 30 via the servo amplifier 51. In this way, the wide open portion of the assist gas injection port is always located rearward in the traveling direction, and the assist gas can be blown to the lower layer portion.

FIG. 2 is a schematic block diagram of the laser processing apparatus of the present invention. Processing contents to be executed by the laser processing apparatus, such as the output of the laser beam and the processing path, are programmed in the processing program 80. The preprocessing means 81 decodes the machining program 80 and determines the output of the laser beam and the movement path to the machining point for machining according to the command. The interpolating means 82 interpolates in the x-axis, y-axis, and z-axis directions to move the machining head so as to perform the desired machining, and sends a pulse signal for movement to the axis control circuits 70a, 70b, 70c. Axis control circuits 70a, 70b, 70c
Servo motors 72a, 72b, and 72c are connected to the motors via servo amplifiers 71a, 71b, and 71c, respectively, and control movement in the x-axis, y-axis, and z-axis directions.

The rotation control means 83 calculates the moving direction of the machining head on the two-dimensional plane from the moving directions of the respective axes.
Then, a pulse signal is sent to the axis control circuit 50 so that the wide open portion of the assist gas injection port is always positioned rearward in the moving direction of the processing head. The axis control circuit 50 controls the rotation of the servo motor 30 via the servo amplifier 51. The servo motor 30 is connected to the nozzle of the processing head. Then, by rotating the nozzle, the wide opening portion of the assist gas injection port can always be positioned rearward with respect to the traveling direction.

FIG. 3 is a view showing a processing situation by the laser processing apparatus of the present invention. In the figure, the processing head 10 is moving in the direction of the arrow. The shaded portion of the work 20 is an unprocessed portion, and 21 is a cut portion. The blackened portion 22 is being processed. That is, the work is melted in the area 22. A condensing lens 12 is provided inside the processing head 10 and condenses the laser beam 11. The nozzle at the tip of the processing head 10 has an assist gas injection port 19
There is. The assist gas injection port 19 is widened to the rear side in the traveling direction. Therefore, oxygen (O ₂ ) as the assist gas 13 can be sufficiently blown to the lower region of the melting region 22. Then, it promotes oxidation of the lower layer region during melting.

FIG. 4 is a view showing the first shape of the assist gas injection port. The figure is a plan view of the processing head 10a as seen from directly below. The traveling direction of the processing head 10a is indicated by an arrow. An assist gas injection port 19a is provided at the center of the processing head 10a. The laser beam 11 is emitted toward the work from between the assist gas injection ports 19a. In this example, the assist gas injection port 19a is an elongated hole. This long hole is designed so that the assist gas 13 can be supplied to the laser beam 11 by opening a wide opening on the side opposite to the traveling direction from the beam center which is the center of the laser beam 11 passing through the hole.
More can be sprayed behind the irradiation point of. Then, the generation of oxidation heat in the work melting portion is promoted.

FIG. 5 is a view showing a second shape of the assist gas injection port. The figure is a plan view of the processing head 10b as seen from directly below. The traveling direction of the processing head 10b is indicated by an arrow. An assist gas injection port 19b is provided at the center of the processing head 10b. The laser beam 11 is emitted toward the work from between the assist gas injection ports 19b. In this example, the assist gas injection port is a triangle whose corners are arcs. In this way, by making the rear side of the beam center wider, the assist gas 13 can be blown more backward than the irradiation point of the laser beam. In this example,
Since the spread in the rear part is larger than that in the example shown in FIG. 4, more assist gas is blown rearward. Then, the generation of oxidation heat in the work melting portion is further promoted, and a thicker plate than before can be cut.

The shape of the assist gas injection port 19 is not limited to that shown in FIGS. Various shapes can be formed according to the application of the laser processing. For example, when the laser beam 11 has a sufficient output and the assist gas 13 assists the cutting at a higher speed. Further, there is a case where a thick plate that cannot be cut only by the output of the laser beam 11 is cut with the assistance of the assist gas 13. The assist gas blown rearward by determining the shape of the assist gas injection port 19 in consideration of factors such as the processing speed of each processing, the output of the laser beam 11, the material of the work 20, the injection amount of the assist gas 13, and the like. A ratio of 13 can be adjusted.

FIG. 6 is a view showing a processing head of the laser processing apparatus of the present invention. A condenser lens 12 for condensing the laser beam 11 is fixed inside the processing head 10. An assist gas intake port 18 is provided on the side surface of the processing head 10. Oxygen (O ₂ ) is supplied to the assist gas intake port 18 as an assist gas 13 from a gas cylinder 90 (not shown).
An assist gas injection port 19 is provided at the tip of the nozzle 14.
As shown in the examples of FIGS. 4 and 5, the assist gas injection port 19 has a wide opening in one direction. The laser beam 11 passes between the assist gas injection ports 19 and the work 20.
Is irradiated.

The rotation of the rotary shaft 31 of the servomotor 30 is
It is transmitted to the rotating shaft 32 of the gear 34 by the belt 33. The gear 34 is meshed with the gear 15 provided on the nozzle 14. And the nozzle 14 is the bearing 1.
It is rotatably held by the presence of the six and seventeen.

When the work 20 is processed by such a laser processing apparatus, the laser beam is generated by the condenser lens 12.
It is focused by and is irradiated to the work. At the same time, the assist gas 13 supplied from the assist gas intake port 18 is blown toward the work 20 from the assist gas injection port 19. Then, the CNC 91 calculates the moving direction of the processing head 10, and the servo motor 3 is arranged so that the widened opening of the assist gas injection port 19 is always on the rear side in the traveling direction.
Control 0. The rotation of the servomotor 30 causes the nozzle 1 to rotate.
4 to direct the nozzle 14 in the desired direction.

By performing the laser processing as described above, the following effects can be obtained when cutting a thick plate work. More assist gas is blown to the back side of the cutting direction. Therefore, sufficient assist gas can be blown to the lower layer portion in which the melting reaction is occurring significantly later than the upper layer portion of the work. Then, the oxidation reaction at the time of melting in the lower layer portion is promoted, the heat of oxidation is increased, and it is possible to cut a plate thicker than the conventional one.

As an example, a hot rolled steel material (S
In the cutting of S400), it was possible to cut up to a thickness of 22 mm in the past, but according to the present invention, it is possible to cut up to a thickness of 25 mm. That is, the thickness of the plate that can be cut is increased by about 1.14.

Also, when cutting a work at high speed,
The lower layer of the work causes a melting reaction significantly later than the upper layer of the work. This delay of the melting reaction becomes more remarkable as the cutting speed increases. Therefore, by implementing the present invention, sufficient assist gas can be blown to the lower layer portion in which the melting reaction has been delayed. And, there is an effect that the cutting speed can be increased.

As an example, in the case of cutting a cold rolled plate (SPCC), a plate which could only be cut at a speed of 7 m / min in the past can be cut at a speed of 8 m / min by the present invention. That is, the cutting speed is about 1.14 times.

[0030]

As described above, in the present invention, since more assist gas is blown to the rear of the working direction, it is possible to promote the oxidation reaction when the lower layer portion of the work is melted. It becomes possible to cut thicker plates than before. Further, it becomes possible to speed up the cutting process for plates having the same thickness.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an NC laser device according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a laser processing apparatus of the present invention.

FIG. 3 is a diagram showing a processing situation by the laser processing apparatus of the present invention.

FIG. 4 is a diagram showing a first shape of an assist gas injection port.

FIG. 5 is a diagram showing a second shape of the assist gas injection port.

FIG. 6 is a diagram showing a processing head of the laser processing apparatus of the present invention.

FIG. 7 is a diagram showing a processing situation by a conventional laser processing apparatus.

[Explanation of symbols]

 10 Processing Head 13 Assist Gas 14 Nozzle 19 Assist Gas Injection Port 81 Pretreatment Means 82 Interpolation Means 83 Rotation Control Means

Claims (4)

[Claims] 1. A laser machining method for machining a workpiece using a nozzle for ejecting an assist gas together with a laser beam from the same opening, wherein an assist gas jet opening wide in one direction from the beam center is used, A laser processing method characterized in that a nozzle is rotated so that a wide opening portion of the assist gas injection port is always positioned rearward with respect to a traveling direction of processing. 2. A laser processing apparatus for processing a workpiece by using a nozzle for ejecting an assist gas together with a laser beam from the same opening, the nozzle having an assist gas injection port wide open in one direction from the beam center. A preprocessing means for decoding the machining program; an interpolation means for outputting the movement of each axis of the machining program in a pulse; a traveling direction of the machining is judged from the moving direction of each axis, and the nozzle is rotated to perform the assist. A laser processing device comprising: a rotation control unit that always positions a wide opening portion of the gas injection port rearward with respect to a traveling direction of processing. 3. The laser processing apparatus according to claim 2, wherein the assist gas injection port of the nozzle is an elongated hole. 4. The laser processing apparatus according to claim 2, wherein the assist gas injection port of the nozzle is a triangular hole whose corner is an arc.