Electric heating – Metal heating – By arc
Patent
1989-06-01
1990-08-28
Albritton, C. L.
Electric heating
Metal heating
By arc
21912177, 21912172, 21912184, 21912178, 21912182, B23K 2600
Patent
active
049527703
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to processing methods and systems using laser beam and, more particularly, to a processing method and system which are suitable to cut materials having high melting points and high reflection factors with use of a suitable laser beam.
BACKGROUND ART
When it is desired to cut a steel plate or the like with use of a laser-beam processing machine, it has been conventionally common practice to converge a laser beam upon or in the vicinity of the front surface of a material to be cut and to set the pressure of an assist gas at such a relatively low level that does not exceed 6 Kg/cm.sup.2.
In the case of cutting the steel plate or the like using the conventional laser-beam processing apparatus, there has not occured no special problem; whereas, in the case of cutting such a material having a high melting point and a high relfection factor as aluminum or copper using the same apparatus, it has been impossible to obtain good cut results.
More specifically, when it is desired to cut such a high melting-point and reflection-factor material as aluminum or copper with use of the conventional laser-beam processing machine, there has occurred such a disadvantage that a part or so called dross of the cutting material melted during the cutting operation will be abruptly cooled during its flow from the front side of the material to the rear side thereof and accordingly be increased in viscocity, which results in that the dross adheres to the rear face of the cutting material, thus disadvantageously involving the imcompleted cutting of the material or providing a rough cut surface thereto due to the dross.
In addition, the prior art laser-beam processing machine has had such a problem that, when it is desired to process a material of a high reflection factor with use of such a prior art machine, part of a laser beam reflected on the high-reflection-factor material enters a laser oscillator part, which sometimes causes the damage of the laser oscillator.
In view of such defects in the prior art as mentioned above, it is an object of the present invention to provide a laser-beam cutting method and system which can sharply and finely cut such materials having high melting points and high reflection factors such as aluminum or copper with use of a laser beam.
DISCLOSURE OF INVENTION
In accordance with the present invention, a laser beam is arranged to be converged upon or in the vicinity of the rear surface of a material to be processed while the pressure of an assist gas is set to be higher than a conventional one.
More specifically, the present invention is directed to providing a laser beam processing method in which a laser beam is irradiated at a portion of a material to be cut while an assist gas is blown against the laser-beam irradiating portion to thereby cut the cutting material off, and which is characterized in that the laser beam is converged upon or in the vicinity of the rear surface of the cutting material and the pressure of the assist gas is set to be higher than 6 Kg/cm.sup.2.
Since the laser beam is converged upon or in the vicinity of the rear surface of the cutting material, the dross flowing from the front side of the cutting material to the rear side thereof can be prevented from being abruptly cooed. Further, since the pressure of the assist gas is set to be higer than 6 Kg/cm.sup.2 and thus the dross can be effectively blown away, the cutting operation can be prevented from becoming incompleted and the cutting face can be also prevented from becoming rough.
The present invention is arranged so that light reflected on the cutting material is partly extracted through a beam splitter and so that, when the extracted reflected light exceeds a predetermined level, the power of the irradiating laser beam is reduced or the feeding movement of the cutting material relative to the laser beam is stopped.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a shematic diagram for explaining the cutting principle of a laser processing machine;
FIG. 2, (a) and (b) show dia
REFERENCES:
patent: 4550240 (1985-10-01), Toida et al.
patent: 4720621 (1988-01-01), Langen
patent: 4774393 (1988-09-01), Tarumoto et al.
Albritton C. L.
Kabushiki Kaisha Komatsu Seisakusho
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