JPH0825077A - Device and method for laser beam machining - Google Patents

Abstract

PURPOSE:To improve the scatter efficiency of a molted metal at the time of laser machining. CONSTITUTION:A working program 80 is decoded by a pre-processing means 81. An interpolation is performed by an interpolation means 82, and a pulse signal for moving is sent to axis controlling circuits 70a, 70b, and 70c. Movements in x axis, y axis, and z axis directions are controlled respectively by axis controlling circuits 70a, 70b, and 70c. A movement direction on the two-dimensional plane of a working head is calculated from the movement direction of each axis. And, a pulse signal is sent to an axis controlling circuit 50 so that assist gas is always spouted out toward the rear of a movement direction. The rotation of a servomotor 30 is controlled by the axis controlling circuit 50 through a servoamplifier 51. The servomotor 30 is connected to the nozzle of the working head. This nozzle is equipped with an assist gas jetting path with an inclined angle to the laser beam. The assist gas can be always injected toward an oblique rear to a proceeding direction by rotating the nozzle like this.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus and a laser processing method for converging a laser beam to process a work, and more particularly to a laser processing apparatus and a laser processing method with an improved assist gas injection method.

[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. The assist gas has an action of promoting the melting of the work by the heat of oxidation in addition to the heat of the laser, and an action of scattering and removing the molten metal from the processed portion.

A chemical reaction by an assist gas using oxygen is represented by the following thermochemical reaction formula.

[0004]

Embedded image Fe + O ₂ ⇒ (1/2) FeO + 38 KJ / cm ³ (1)

[0005]

Embedded image Fe + (2/3) O ₂ ⇒ (1/3) Fe ₃ O ₄ + 52KJ / cm ³ (2) When cutting a mild steel plate, a turret punch press or a plasma cutting machine is used. For example, it is possible to process at a higher speed than laser processing. However, the turret punch press requires a die and causes a burr on the cut surface.
Further, although the cutting by the plasma cutting machine is very fast, the environment is deteriorated and various parts are worn out severely. As described above, the turret punch press and the plasma cutting machine have their respective problems. Therefore, there is a demand for high-speed cutting by laser processing, which does not adversely affect the environment, causes less wear of parts, and is excellent in fine processing.

FIG. 5 is a view showing a processing situation by a conventional laser processing apparatus. In the figure, the processing head 10a is moving in the direction of the arrow. A condenser lens 12a is fixed to the processing head 10a, and an assist gas injection path 19a for the laser beam 11a is provided at the tip of the nozzle. The assist gas 13a is ejected from the assist gas injection path 19a. 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 the uncut portion 2
2a, and the other part is the cut part 21a. The assist gas 13a ejected from the assist gas ejection path 19a is ejected in parallel with the laser beam 11a,
It is sprayed on the edge 23a in front of the cutting groove.

As described above, the assist gas injection path 19a is provided so that the flow of the assist gas 13a is parallel to the beam axis of the laser beam 11a. Since the assist gas injection port at the tip of the nozzle is a perfect circle, the assist gas 13a is blown perpendicularly to the work 20a in a concentric shape centered on the laser beam 11a.

[0008]

However, when the cutting speed becomes high, the melting in the lower layer region of the work is significantly delayed, and the flow of the assist gas blown perpendicularly to the workpiece is obstructed in the lower layer region of the work. I will be lost. As a result,
The scattering removal of molten iron by the assist gas cannot keep up with the cutting speed. The molten iron remaining in the vicinity of the processed portion without being removed hinders the irradiation of the work with the laser beam and reduces the cutting efficiency of the laser processing.

Here, a method of increasing the pressure of the assist gas can be considered in order to increase the efficiency of scattering and removal of the molten metal, but in this case, the oxidation reaction at the cutting portion of the work becomes too vigorous and the cutting surface is poor. Become. Therefore, the pressure of the assist gas cannot be increased above a certain limit value.

As described above, if the scattered iron is not sufficiently removed by scattering, even if the output of the laser beam is increased, the cutting speed corresponding to the increase cannot be increased. .

The present invention has been made in view of the above points, and an object of the present invention is to provide a laser processing apparatus with improved molten metal scattering efficiency. Another object of the present invention is to provide a laser processing method in which the scattering efficiency of molten metal is improved.

[0012]

In order to solve the above-mentioned problems, the present invention provides a laser processing apparatus for injecting an assist gas together with a laser beam from the same opening to process a work, and has an inclination angle with respect to the beam axis. A nozzle having an assist gas injection path, preprocessing means for decoding the movement amount of each axis from a machining program, interpolation means for outputting the movement amount of each axis in pulses, and machining progress from the pulse output of each axis. There is provided a laser processing device, comprising: a rotation control unit that determines a direction, rotates a nozzle, and constantly ejects the assist gas in a diagonally rearward direction with respect to a traveling direction of the processing.

Further, in a laser processing method for processing a workpiece by injecting an assist gas together with a laser beam from the same opening, by rotating a nozzle having an assist gas injection path having an inclination angle with respect to the beam axis,
There is provided a laser processing method characterized in that the assist gas is always jetted obliquely rearward with respect to the traveling direction of processing.

[0014]

In the laser processing apparatus, the nozzle has an assist gas injection path having an inclination angle with respect to the beam axis.
With this inclination angle, the assist gas can be jetted obliquely. The preprocessing means decodes the movement amount of each axis from the machining program. The interpolation means outputs the movement amount of each axis as a pulse. The rotation control means determines the traveling direction of the processing from the pulse output of each axis, rotates the nozzle, and always injects the assist gas obliquely rearward with respect to the traveling direction of the processing.

With this, since the assist gas can be ejected along the inclination of the edge in front of the cutting groove, the molten metal can be efficiently scattered and removed. Further, by rotating a nozzle having an assist gas injection path having an inclination angle with respect to the beam axis, a laser processing method of always injecting the assist gas obliquely rearward with respect to the traveling direction of the processing is performed. Scattering can be efficiently removed.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a 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 pre-processing unit 81 decodes the machining program 80, outputs a laser beam for performing machining according to the command, and a movement path to a machining point,
And decipher the amount of movement. The interpolating means 82 moves the machining head so as to perform the desired machining.
Interpolation in the axial direction is performed, and the axis control circuits 70a, 70b, 70
A pulse signal for movement is sent to c. Axis control circuit 70
a, 70b, 70c are respectively provided with servo amplifiers 71
servo motors 72a, 72 via a, 71b, 71c.
b and 72c are connected to 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 assist gas is always injected rearward in the moving direction.
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. This nozzle has an assist gas injection path having an inclination angle with respect to the laser beam. By rotating such a nozzle,
The assist gas can always be jetted obliquely rearward with respect to the traveling direction.

FIG. 2 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 is a read-only memory (ROM) 4
The machining program stored in the random access memory (RAM) 42 is read out based on the control program stored in No. 1 to control the operation of the entire NC laser device.
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 a commercial power supply, then performs a switching operation to generate a high frequency voltage, and generates a high frequency current according to the current command value by the discharge tube 66.
Supply to.

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 as the laser beam 11 to the outside.

The output laser beam 11 changes its direction by the bender mirror 68, and is converged into a spot of 0.2 mm or less by a condenser lens inside the processing head 10 and irradiated on the surface of the work 20.

The axis control circuit 70 controls the rotation of the servo motor 72 via the servo amplifier 71 according to the command of 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 beam partially transmitted from the rear mirror 64 and outputs it, and measures the output power of the laser beam 11. The A / D converter 62 is a power sensor 63.
Is converted into a digital value and input to the CPU 40.

A gas cylinder 90 is connected to the processing head 10, and an assist gas is supplied during processing. Oxygen (O ₂ ) is used as this assist gas. Processing head 10
The nozzle has an assist gas injection path having an inclination angle with respect to the beam axis, and the assist gas injection path also serves as the output port of the laser beam 11. The CPU 40 deciphers the machining program so that the machining head 10
Calculate the moving direction of. Then, the axis control circuit 50 is configured so that the assist gas is always injected rearward in the traveling direction.
Command. The axis control circuit 50 controls the rotation of the servo motor 30 via the servo amplifier 51. In this way, the assist gas can be ejected at an angle along the inclination of the cutting groove of the work to enhance the effect of scattering the molten metal.

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 area of the work 20 is the unprocessed portion 22, and the other area is the cut portion 21. Inside the processing head 10, there is a condenser lens 12,
The laser beam 11 is focused. The nozzle at the tip of the processing head 10 has an assist gas injection path 19 through which the assist gas 13 is injected. Assist gas injection path 19
Are tilted with respect to the beam axis. The inclination angle is set to be approximately the same as the inclination of the edge 23 in front of the cutting groove when cutting the work 20 in consideration of the material of the work, the plate thickness, and the like. That is, the flow direction of the injected assist gas 13 and the edge 23 in front of the cutting groove are substantially parallel to each other.

In this way, the assist gas 13 is always jetted obliquely rearward in the traveling direction. Therefore, the flow of the assist gas 13 is always the front edge 23 of the cutting groove of the workpiece.
The direction of the assist gas is in the lower direction and the flow velocity of the assist gas in the lower region of the work can be maintained at a high speed. Therefore, the molten metal is efficiently scattered even in the lower layer region of the work. As a result, the energy of the laser beam is efficiently used as heat energy for cutting, and the cutting speed can be accelerated.

Even if the angle of inclination of the assist gas injection path 19 is less than the angle of the edge 23 in front of the cutting groove, if it has an angle of inclination to some extent, it may be parallel to the beam axis. In comparison, it goes without saying that the molten metal is efficiently scattered.

FIG. 4 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 path 19 is provided at the tip of the nozzle 14. The assist gas injection path 19 has an inclination with respect to the beam axis. The laser beam 11 passes through the assist gas injection path 19 and is applied to the work 20.

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 path 19. Then, the numerical control device calculates the moving direction of the processing head 10 and controls the servo motor 30 so that the assist gas is always sprayed to the rear side in the traveling direction. The rotation of the servo motor 30 is transmitted to the nozzle 14 so that the nozzle 14 can be directed in a target direction.

As described above, when cutting is performed by the laser processing apparatus, the assist gas is always jetted rearward in the traveling direction, so that the molten metal can be efficiently scattered and removed. Therefore, the laser energy is applied to the work without being hindered by the molten metal, and the cutting speed can be increased. This is particularly effective when cutting a thick plate work. This is because the thicker the plate pressure of the work, the more noticeable the delay of melting in the lower layer region of the work.

For example, when cutting a 12 mm thick mild steel plate, the maximum cutting speed in the conventional laser processing apparatus is 1.
It was m / min. At this speed, the laser output is 3 kW
But 6kw is the same. However, by always injecting the assist gas obliquely backward in the traveling direction, a cutting speed of 1.7 m / min is obtained when the laser output is 3 kw, and 2.5 m when the laser output is 6 kw.
A cutting speed of / min is obtained. That is, since the molten metal is efficiently scattered and removed, if a high-power laser processing device is used, the cutting speed can be improved according to the laser output. When cutting a work having such a large plate thickness, the inclination of the assist gas with respect to the beam axis, which is effective in removing the scattered molten metal efficiently, is about 10 °.

[0032]

As described above, according to the present invention, when the work is cut, the assist gas is always jetted rearward in the traveling direction, so that the molten metal can be efficiently scattered and removed. It can be done and the cutting speed can be increased.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a laser processing apparatus of the present invention.

FIG. 2 is a block diagram showing a configuration of an NC laser device according to an embodiment 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 processing head of a laser processing apparatus.

FIG. 5 is a diagram showing a processing situation by a conventional laser processing apparatus.

[Explanation of symbols]

 10 Processing Head 11 Laser Beam 12 Condensing Lens 13 Assist Gas 14 Nozzle 19 Assist Gas Injection Path 81 Pre-Processing Means 82 Interpolating Means 83 Rotation Control Means

Claims (3)

[Claims] 1. A laser processing apparatus for processing a workpiece by injecting an assist gas together with a laser beam from the same opening, wherein a nozzle having an assist gas injection path having an inclination angle with respect to the beam axis and each axis from a processing program. Pre-processing means for decoding the movement amount of each axis, an interpolating means for outputting the movement amount of each axis in a pulsed manner, judging the progress direction of the machining from the pulse output of each axis, rotating the nozzle, the assist gas A laser processing apparatus comprising: a rotation control unit configured to always eject obliquely rearward with respect to a traveling direction of processing. 2. The nozzle is about 10 ° with respect to the beam axis.
The laser processing apparatus according to claim 1, further comprising an assist gas injection path having an inclination angle of. 3. A laser processing method for injecting an assist gas together with a laser beam from the same opening to process a work, by rotating a nozzle having an assist gas injection path having an inclination angle with respect to the beam axis, A laser processing method characterized in that an assist gas is always sprayed obliquely rearward with respect to a processing progressing direction.