JP2016030264A - Laser machining head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser machining head which makes the prevention of dross adhesion and plasma suppression compatible, and carries out machining excellent in productivity and quality.SOLUTION: A laser machining head includes: a condenser lens which condenses laser beams; and nozzles which introduce assist gas, and make the assist gas pass through in injection shaft directions of the collected laser beams. The nozzles are coaxially disposed, and have at least triple or more independent gas channels. The third or outer gas channels from a center, make the gas flow in a slanting direction toward the center, to the second or inner gas channels.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser processing head used in a laser apparatus mainly used for sheet metal cutting.

  FIG. 4 is a block diagram showing an example of a conventional sheet metal cutting laser processing machine using a laser processing head.

  In this figure, the laser beam 8 emitted from the laser oscillator 1 is reflected by the reflecting mirror 15 and guided to the vicinity of the workpiece 16. The laser beam 8 is condensed into a high-density energy beam by a condensing lens 18 provided in the laser processing head 17 and irradiated onto the workpiece 16 to be cut. The workpiece 16 is fixed on the machining table 19, and the X-axis motor 20 or the Y-axis motor 21 moves the laser machining head 17 relative to the workpiece 16 to perform machining of a predetermined shape. .

  In laser cutting, processing is performed by blowing a gas called assist gas 22 onto the workpiece through a nozzle 24 provided at the tip of the laser processing head coaxially with the laser beam irradiated to the workpiece via the condenser lens. By blowing off the metal melted by the laser beam with a high-pressure assist gas, a good cut surface without adhesion of the molten metal can be obtained. In particular, in the CO2 laser cutting of the kilowatt class, the assist gas flow is very important for realizing good cutting.

  Conventionally, the nozzle generally used is a single nozzle constituted by only the first nozzle or a double nozzle constituted by the first and second nozzles. A conventional example of a double nozzle is shown in FIG. 5 (see FIG. 1 of Patent Document 1). The aim of the double nozzle is to realize a gas flow that efficiently discharges dross by the balance of the gas flow ejected from the first nozzle and the second nozzle.

JP-A-6-190582 JP 2011-177788 A

  However, the laser processing head according to the prior art has a problem that it is difficult to cut well when cutting a stainless steel plate of 20 mm or more with a CO2 laser of 5 to 6 kW or more. Usually, in the case of cutting a stainless steel plate, a high pressure nitrogen gas of 2 MPa or more is used as an assist gas, and a metal melted by laser light (hereinafter referred to as dross) is blown off by the assist gas for cutting. However, as the plate thickness of the workpiece increases, it becomes more difficult to blow off the dross.

  The assist gas flows along the cutting surface from the upper end to the lower end of the workpiece, but the flow velocity decreases due to pressure loss while flowing through a gap with a cutting width of about 1 mm. The flow rate cannot be obtained.

  As a result, the dross solidifies and adheres to the lower end of the workpiece, so that good cutting cannot be established. It is an important issue to prevent dross adhesion and achieve good cutting in thick plates, particularly stainless steel. In addition, there is an adverse effect of the vaporization of vaporized dross within the cutting width.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a laser processing head capable of processing with excellent productivity and quality that achieves both prevention of dross adhesion and plasma suppression.

  In order to solve the above problems, a laser processing head according to the present invention introduces a condensing lens for condensing a laser beam and an assist gas, and passes the assist gas in the direction of the emission axis of the condensing laser beam. The nozzles are arranged concentrically, have at least three or more independent gas flow paths, and the gas flow paths on the third and higher outer sides are the gas flow paths on the inner second and lower gas flow paths. On the other hand, the gas flows in an oblique direction toward the center.

  With the above-described configuration, in the laser processing head according to the present invention, the gas flow from the third or more nozzles flows in an oblique direction toward the center, so that the flow velocity and distribution of the assist gas can be appropriate. It is possible to perform processing with excellent productivity and quality that achieves both prevention of dross adhesion and plasma suppression.

It is sectional drawing which shows an example of a structure of the laser processing head of this invention, and the figure which showed the structure of the triple nozzle It is sectional drawing which shows the example of a different structure of the laser processing head of this invention, and the figure which showed the structure of the quadruple nozzle The figure which showed the assist gas flow velocity distribution of the laser processing head front-end | tip part of this invention Configuration diagram showing an example of a conventional sheet metal cutting laser processing machine using a laser processing head It is sectional drawing which shows the structure of the nozzle part of the conventional laser processing head, and the figure which showed the structure of the double nozzle

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same components are denoted by the same reference numerals, and the description thereof may be omitted.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing an example of the configuration of the laser processing head of the present invention. In this example, triple nozzles are arranged concentrically. Here, the first nozzle, the second nozzle, and the third nozzle are referred to from the inside. The assist gas supplied from the side of the laser processing head is branched in the laser processing head and is branched to the first to third nozzles.

  Two or more gas flow paths are separated by concentric partition walls 25. A gas introduction hole 26 is provided in each flow path, and assist gas flows. The partition wall 25 is formed such that the gas flow ejected from the third or more nozzles is inclined toward the center.

  The aim of increasing the number of nozzles that eject the assist gas to triple or more is a gas that efficiently discharges dross by the balance between the gas flow ejected from the first and second nozzles and the gas flow ejected from the third or more nozzles. Is to realize the flow.

  In particular, as the plate thickness of stainless steel increases, it is necessary to improve the gas flow, and when it is configured with up to double nozzles, efforts have been made to optimize the diameters of the first nozzle and the second nozzle. It was not enough.

  In the present invention, the point of optimization is how to flow the work gas in the vertical direction within the cutting width of the work piece without reducing the flow rate of the assist gas.

  For example, the cutting width of a 20 mm thick workpiece is about 1 mm with respect to a vertical thickness direction of 20 mm. In order to increase the flow velocity of the assist gas flowing through the cutting width, it is not necessary to simply increase the pressure of the assist gas supplied to the nozzle.

  In the present invention, the gas flow from the third nozzle flows in an oblique direction toward the center, so that it is synergistic with the gas flow formed by the first and second nozzles and is necessary to cover the cutting width. A sufficiently high flow rate can be realized within the width and within the cutting width. Thereby, dross adhesion can be reduced and good cutting can be realized.

  Further, in laser cutting, other adverse effects of dross may occur. If the dross is clogged within the cutting width, the dross vaporized by the irradiation of the laser beam absorbs the laser beam to be turned into plasma, and the cut surface is eroded by the plasma, resulting in a problem of cutting failure.

  In order to achieve both prevention of dross adhesion and plasma suppression, it is necessary to optimize the flow velocity distribution. In particular, it is necessary to give particular importance to stable cutting of stainless steel of 20 mm or more with a 6 kW class CO2 laser oscillator.

  In the present invention, the gas flow from the third nozzle flows in an oblique direction toward the center, so that the gas flow formed by the first and second nozzles is shielded from the external atmosphere, thereby stabilizing the gas flow. As a result, dross adhesion can be reduced and good cutting can be realized.

  FIG. 2 is a cross-sectional view showing an example of a different configuration of the laser processing head of the present invention. In this example, it is a quadruple nozzle composed of first to fourth nozzles.

  The first to fourth nozzles are concentrically arranged, and the gas flow paths outside the third and third are configured to flow gas in an oblique direction toward the center with respect to the gas flow paths inside and below the second doing.

  By further increasing the gas flow path, the flow velocity of the assist gas is increased, and a sufficiently high flow velocity can be realized at the center of the gas flow while ensuring the width necessary to cover the cutting width.

  FIG. 3 shows the assist gas flow velocity distribution in the case where the number of nozzle channels is a conventional double nozzle, the triple and quadruple nozzles in the embodiment of the present invention, and the five-fold and six-fold nozzles further increased in number. Are schematically represented and compared.

  As shown in this figure, with a double nozzle, the flow velocity is high in a narrow range of just the jetting portion directly below, but the width is narrow and not sufficient to cover the cutting width.

  Compared to double nozzles, the configuration of more than triple nozzles increases the assist gas flow velocity at the center and forms a flow velocity distribution with a width in the plane direction perpendicular to the flow direction. Recognize. It can be seen that by using at least a triple nozzle, the assist gas flow rate can be remarkably stabilized and good cutting can be realized.

  The function of each nozzle is that the first and second nozzles form a basic gas flow, and the outside of the third nozzle has a shielding effect that stabilizes the basic gas flow formed by the first and second nozzles. large. In the case of a five-fold structure or more, the degree of the effect does not change greatly even though the structure is complicated. From this point, it is considered that the triple structure and the quadruple structure are the most practical areas.

  In the laser processing head introduced in this embodiment, the flow rate of the assist gas flowing through the gas flow path can be made different for each nozzle by adjusting the diameter and number of the gas introduction holes 26. For example, the flow rate of the third nozzle can be set to be a sufficiently large flow rate within the cutting width, and the flow rate of the nozzles higher than that can be changed asymptotically to obtain an ideal flow rate distribution.

  As described above, according to the laser processing head of the present embodiment, the gas flow from the third or more nozzles flows in an oblique direction toward the center, so that the flow velocity and distribution of the assist gas are appropriately adjusted. Therefore, it is possible to perform processing with excellent productivity and quality that achieves both prevention of dross adhesion and plasma suppression.

  In addition, regarding a multiple nozzle shape of three or more nozzles, there is an invention described in Patent Document 2 as a conventional example. This is based on a completely different aim and configuration of flowing water, and is different from the present invention.

  The laser processing head according to the present invention is capable of processing with excellent productivity and quality that achieves both prevention of dross adhesion and plasma suppression, and is mainly used for laser processing used in sheet metal cutting applications. Useful in heads and the like.

DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Beam exit 7 Total reflection mirror 8 Laser beam 9 Laser control device 16 Work 18 Condensing lens 17 Laser processing head 19 Processing table 20 X-axis motor 21 Y-axis motor 22 Assist gas 23 Work 24 Nozzle 25 Bulkhead 26 Gas introduction Hole

Claims (3)

A laser processing head comprising: a condensing lens for condensing a laser beam; and a nozzle that introduces an assist gas and passes the assist gas in an emission axis direction of the condensed laser beam,
The nozzles are arranged concentrically and have at least three or more independent gas flow paths,
The laser processing head characterized in that the gas flow path on the outer side of the triple or more flows gas in an oblique direction toward the center with respect to the gas flow path on the inner or lower side.   2. The laser processing head according to claim 1, wherein the assist gases flowing through the third or more independent gas flow paths have different flow rates. 3. The laser processing head according to claim 1, wherein each of the third or more independent gas flow paths is separated by a partition wall. 4.

Images