JPH037477B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a mechanism for optically controlling a laser beam in a laser device, particularly in a processing device that performs processing using a laser beam.

FIG. 1 shows a block diagram of this type of processing apparatus that has been commonly used in the past. In the figure, high voltage power generated in a power supply device 1 is supplied to a laser oscillator 3 via a cable 2. As a result, the laser oscillator 3 causes laser oscillation, and the generated laser beam 4 is guided to the processing optical device 5, where the beam diameter is expanded by two beam expander lenses 6 and 7 provided therein. Further, after the light is focused by a converging lens 8 to increase the energy density, thermal energy is supplied to the processing point p according to the processing conditions of the workpiece 9, and processing such as welding and cutting is performed.

In such a laser processing apparatus, starting and stopping of the laser beam is normally performed by controlling the beam oscillation of the laser oscillator on and off using an electric signal or the like. However, as shown in FIG. 2, for example, when the laser beam 4 of one laser oscillator 3 is divided into 4a and 4b by a half mirror 10 to process a plurality of workpieces 9a and 9b, There may arise a case where it is desired to selectively stop irradiation of only one of the laser beams 4a and 4b depending on the situation of each workpiece. For this reason, a laser beam shielding mechanism 11 is provided in each optical path, and a signal is applied from the outside to open and close the laser beam optical path depending on whether or not processing is possible.

FIG. 3 shows a conventionally used shielding mechanism 11.
An example is shown below. In the figure, the output shaft 14 of the rotary solenoid 13 attached to the bracket 12
The lever 15 is fastened with a screw 16q. A beam shielding plate 17 is further fixed to the tip of this lever 15. When a beam shielding command is given from the outside, the output shaft 14 swings and rotates the beam shielding plate 17 in the direction of arrow θ via the lever 15, thereby blocking the optical path of the laser beam 4.

When using the shielding mechanism 11 as described above,
The laser output is several watts for continuous oscillation, less than 1 joule for pulse oscillation, and the beam spot diameter is 10
There is relatively no problem in a small laser processing device of mm or less, but in the case of a larger device, the beam shielding plate 17 absorbs the laser beam 4 with high energy density when shielding, and is heated significantly. for example,
A black metal plate (absorption rate 0.8) with an outer diameter of 20 mm and a plate thickness of 1 mm was used as the beam shielding plate 17, and a laser beam 4 with a rated output of 500 watts (efficiency 10%) was applied to this for 10 minutes.
When irradiated for seconds, the temperature rises by about 300℃.
If the irradiation time and laser power are increased, this heating temperature will further increase. In addition, since this type of shielding mechanism 11 is often used in repeated normal ON-OFF operations, the life of the shielding plate 17 is extremely shortened due to heat accumulation, and the time required to replace it reduces the operating time of the device. This is a contributing factor to the decline. Further, the laser beam 4 reflected without being absorbed by the shielding plate 17 is attenuated while repeating reflection and absorption within the optical path, but there is also a risk that a part of it may leak out to the outside, which poses a problem in terms of safety management.

The present invention has been made in view of the above circumstances, and its purpose is to provide a laser device equipped with a shielding mechanism that can safely and reliably perform high-output, long-term beam shielding. .

In order to achieve such an object, the laser device according to the present invention uses a reflector as a beam shielding mechanism and is provided with an attenuator that receives and attenuates the laser beam reflected by the reflector. Hereinafter, the laser device according to the present invention will be explained in detail using Examples.

FIG. 4 is a configuration diagram showing an embodiment of a laser device according to the present invention, and the same parts as in FIG. 1 or 2 use the same signals, and detailed explanation thereof will be omitted. In FIG. 4, a reflecting plate 20 attached to the output shaft 19 of the cylinder 18 is provided between the beam expander lenses 6, 7 and the converging lens 8 inside the processing optical device 5c. This movable reflector 20
The cylinder 18 reciprocates in the direction of the output shaft 19 in accordance with a signal given from the outside, and opens and closes the laser beam control optical path from the beam expander lenses 6 and 7 to the converging lens 8. It is arranged so that the control optical path can be branched. Furthermore, an attenuator 21 for receiving the laser beam 4c reflected by the movable reflector 20 is provided in the direction of the reflected optical path when the movable reflector 20 is shielded. The attenuator 21 includes an attenuation block 22 made of a heat-resistant material with a high beam absorption rate, and includes an attenuation chamber 23 having a concave spherical shape. Examples of such materials include carbon, brick, concrete, and the like. Further, the inner wall of the attenuation chamber 23 is processed into an uneven shape to enhance the beam absorption effect.
At the laser beam 4c input port of this attenuation chamber 23,
A translucent shield glass plate 24 is provided to shield the inside of the attenuation chamber 23 from the atmosphere on the control optical path side for external processing, and a diffusion lens 25 is provided to diffuse the laser beam 4c and reduce its energy density. There is. Above, only one side 4a of the laser beam divided by the half mirror 10 will be explained,
The other laser beam 4b is also provided with the same shielding mechanism and attenuator as described above.

In the laser device having the above configuration, when the movable reflection plate 20 is at the position shown by the chain line, the laser beam 4 emitted from the laser oscillator 3 is introduced into the processing optical device 5c, and the half mirror 10
b. Thereafter, these laser beams 4a and 4b are expanded and focused by expander lenses 6 and 7 and converging lens 8 as in the conventional case, and are focused on workpieces 9a and 9b (not shown), respectively.
The beam is irradiated to processing points Pa and Pb (not shown) to perform processing such as welding, cutting, and drilling.

Here, for example, a defect occurs in the workpiece 9a,
When it is desired to block only the laser beam 4a, a beam shielding command is given to move the movable reflector 20 to shield the laser beam control optical path between the expander lens 7 and the converging lens 8, as shown by the solid line in FIG. . The laser beam 4c whose processing control optical path is blocked and is reflected by the movable reflection plate 20 is
It heads toward the attenuator 21 , passes through a light-transmitting shield glass plate 24 , and enters the attenuation chamber 23 . The laser beam 4c entering the attenuation chamber 23 is expanded in beam diameter by the diffusing lens 25. The laser energy density of the laser beam 4c decreases in proportion to the expanded beam diameter. The laser beam 4c, whose energy density has been reduced in this way, is irradiated onto the inner wall of the attenuation chamber 23 and is absorbed, and the light that is partially unabsorbed is repeatedly diffused and attenuated. In this case, the optimal shape of the attenuation chamber 23 is determined by setting conditions such as laser power, efficiency, beam shielding time repetition frequency, beam expansion rate by the expander lenses 6 and 7, and beam expansion rate and attenuation by the diffusion lens 25 on the attenuator side. It can be easily set based on various conditions such as the beam absorption rate of the material constituting the block 22. Further, as described above, by providing unevenness on the inner wall of the damping chamber 23 to increase the surface roughness, the damping effect can be further enhanced.

In this way, the conventional shielding mechanism irradiates the laser beam onto a flat shielding plate inserted into the control optical path and causes it to be directly absorbed, and the part of the beam that is not absorbed there is absorbed by optical components and attenuated. In contrast, in the present invention, the optical path is branched by a reflector inserted into the control optical path to provide a bypass optical path, and the beam of this bypass optical path is guided to an attenuator to ensure that the beam is A method is used to attenuate and annihilate the light. Therefore, leakage of the beam can be reliably prevented, and it is also possible to eliminate the inconvenience that the shielding beam heats the optical components to be processed. In Figure 4, the rated output is 500W.
The laser beam is continuously oscillated for 1 minute, and the attenuator 2
As a result of measuring the temperature of 1 and optical components, it was approximately 50℃.
It was confirmed that the component parts of the processing optical device 5c were effectively protected from the temperature increase during beam shielding.

In addition, in the embodiment described above, the damping chamber 23
is formed into a concave spherical shape, but the present invention is not limited to this, and as described above, this shape can be optimized depending on the conditions on the control optical path side and the attenuator side for processing. can be determined.

Furthermore, in the above-described embodiment, the diffusing lens 25 was provided at the laser beam ₄₀ input port of the attenuation chamber 23 to reduce the energy density of the beam entering the attenuation chamber 23, but especially when the laser power is small,
This diffusion lens 25 may be omitted.

Furthermore, in the embodiments described above, only the case where the beam of one laser oscillator 3 is divided into a plurality of beams and each beam is controlled according to the situation of each workpiece has been described. It goes without saying that the present invention is particularly effective in the above situations, but it is not limited thereto. For example, even if the beam is not split, by keeping it in a shielded state except during laser processing,
Of course, even if oscillation is started due to a malfunction of the power supply device, it can be used as a mechanism that can prevent abnormal irradiation of the laser beam.

As explained above, according to the laser device according to the present invention, a movable reflector that can branch the control optical path of a laser beam and an attenuator that receives the laser beam reflected by the reflector are provided. ,
It has the excellent effect of shielding the laser beam safely and reliably, and is extremely useful as a laser device that uses the thermal energy of the laser beam to perform processing in all fields, such as welding, drilling, cutting, and peeling. It has high utility value.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing an example of a conventional laser device, 3 is a block diagram showing a beam shielding mechanism in the laser device of FIG. 2, and 4 is a block diagram showing an example of a conventional laser device.
The figure is a configuration diagram showing an embodiment of a laser device according to the present invention. 3... Laser oscillator, 4, 4a, 4b, 4c...
...Laser beam, 20...Movable reflector, 21...
Attenuator, 23... Attenuation chamber, 24... Shield glass plate, 25... Diffusion lens.

Claims (1)

[Scope of Claims] 1. A movable reflector that can branch the control optical path by a shielding operation is disposed in the laser beam control optical path, and receives the laser beam reflected by the reflector during the shielding operation. an attenuator is provided, the attenuator comprising a diffusing lens for diffusing the reflected laser beam to reduce its energy density;
A laser device comprising: an attenuation chamber that receives a laser beam diffused by the diffusion lens. 2. The laser device according to claim 1, wherein the attenuator is provided with a light-transmitting shield glass plate at the laser beam input port of the attenuation chamber to shield the inside of the attenuation chamber from the outside atmosphere.