GAS GUIDE, LASER CUTTING HEAD AND LASER CUTTING MACHINE

Abstract

The invention relates to a gas guide (11, 11a, 11b, 11c) for a laser cutting head (10) having a nozzle (19), having a central flow axis (S), comprising a base part having a pressure chamber (24) concentrically surrounding the flow axis (S), configured for the reception of a gas flow (20a, 20b, 20c), wherein the base part has at least four gas conduits (26a, 26b, 26c), which extend from the pressure chamber (24) in the direction of the flow axis (S), and wherein the cross-sections of the pressure chamber (24) and the gas conduits (26a, 26b, 26c) are dimensioned such that the gas has a maximum flow rate when it exits the gas conduits.

Claims

1. A gas guide for a laser cutting head having a nozzle, having a central flow axis, comprising a base part having a pressure chamber concentrically surrounding the flow axis, configured for the reception of a gas flow, wherein the base part has at least four gas conduits, which extend from the pressure chamber in the direction of the flow axis, and wherein the cross-sections of the pressure chamber and the gas conduits are dimensioned such that the gas has a maximum flow rate when it exits the gas conduits, wherein the gas conduits each extend at a decreasing angle with respect to the flow axis in the flow direction of the gas flow.

2. The gas guide according to claim 1, characterised in that at least two gas flow channels are provided between the pressure chamber and at least one gas inlet, wherein the at least two gas flow channels open tangentially and/or radially into the pressure chamber.

3. The gas guide according to claim 2, characterised in that a gas-conducting element is provided between the at least two gas flow channels.

4. The gas guide according to claim 2, characterised in that the cross-sections of the at least two gas flow channels, of the gas inlet, of the pressure chamber and of the gas conduits are dimensioned such that the gas has a maximum flow rate when it exits the gas conduits.

5. The gas guide according to claim 1, characterised in that the pressure chamber comprises a continuous recess, two recesses comprising areas connected with an equalisation port, or four mutually separate recesses.

6. The gas guide according claim 2, characterised in that at least two gas flow channels open into each recess.

7. The gas guide according to claim 1, characterised in that at least four to twenty-four, preferably twenty-two, gas conduits are provided.

8. The gas guide according to claim 1, characterised in that the gas conduits are arranged concentrically around the flow axis.

9. The gas guide according to claim 1, characterised in that a concentrically circumferential equalising channel adjoins the gas conduits.

10. The gas guide according to claim 9, characterised in that an outer contour of the equalising channel remote from the flow axis extends at a decreasing angle with respect to the flow axis in the flow direction of the gas flow.

11. The gas guide according to claim 9, characterised in that the cross-sections of the at least two gas flow channels, of the pressure chamber, of the gas conduits and of the equalising channel or of the pressure chamber, the gas conduits and of the equalising channel are dimensioned such that the gas has a maximum flow rate in the area of the outflow port.

12. The gas guide according to claim 1, characterised in that the gas guide has an upper part and a lower part, wherein the pressure chamber, the gas conduits and/or the equalising channel are formed between the upper part and the lower part.

13. A laser cutting head for a laser cutting machine, characterised in that a laser feed, a nozzle and a gas guide according to claim 1 are provided.

14. A laser cutting machine having a laser cutting head according to claim 13 and/or a gas guide according to claim 1.

Description

[0025] The invention will be explained below in exemplary embodiments with reference to the accompanying drawings. In the figures:

[0026] FIG. 1 shows a sectional view of a laser cutting head having a gas guide,

[0027] FIG. 2 shows a further sectional view of a gas guide according to a first embodiment,

[0028] FIG. 3 shows a sectional view of a gas guide according to a second embodiment,

[0029] FIG. 4 shows a sectional view of a gas guide,

[0030] FIG. 5 shows an enlarged detail of FIG. 4, and

[0031] FIG. 6 a schematic perspective view of a laser cutting machine having a laser cutting head.

[0032] FIG. 1 shows a sectional view of a laser cutting head 10 having a gas guide 11. Such laser cutting heads 10 are used, for example, in laser cutting machines.

[0033] The laser cutting head 10 has a base body 12 with an interior 14, which is designed as a clean room. A laser source 16, for example, a fibre laser, is attached to the outside of the base body 12 and produces a laser beam 18 directed into the interior 14. Alternatively, reference numeral 16 can denote a coupling member, with which a laser beam of an external laser source exits. The coupling member may be, for example, a fibre plug having an end cap.

[0034] The laser beam 18 enters the interior 14 via a fibre bushing 13. The laser beam 18 further extends to a deflecting element 15 such as a mirror. The deflected laser beam 18 passes through a lens 17. Finally, the laser beam 18 leaves the interior 14 through the base body 12. The laser beam 18 then enters the gas guide 11, where it meets a gas flow 20. The laser beam 18 leaves the gas guide 11 and thus the laser cutting head 10 through the nozzle or nozzle electrode 19.

[0035] The gas guide 11 here consists of a plurality of parts, consisting at least of one upper part 21, one or a plurality of gas inlets 23a and 23b, at least one pressure chamber 24 and at least one lower part 22. By changing the geometry of the upper part 21 and the lower part 22 and the position and number of the gas inlets 23a and 23b, the gas flow 20 can be positively influenced for the cutting process. The pressure chamber 24, which can be divided into a plurality of recesses or areas, can be formed by the upper part 21 and the lower part 22.

[0036] The gas guide 11 is axissymmetrical and/or rotationally symmetrical with respect to a flow axis S. The flow axis S corresponds to the optical axis of the laser beam 18 in the area of the lower part and indicates the central axis of the gas flow in the direction of the nozzle electrode 19. The two gas inlets 23a and 23b are arranged concentrically with respect to flow axis S. In the gas guide 11, the gas flow, which is initially radial in the gas inlets 23a and 23b, is deflected into an axial gas flow.

[0037] FIG. 2 shows a sectional view of a gas guide 11a according to a first exemplary embodiment. The sectional view is perpendicular to the sectional view of FIG. 1, so that the flow axis is a surface normal to the sheet plane.

[0038] Here, the upper part 21a and the lower part 22a as well as the gas flow channels 25a and 25b are shaped such that the gas flow 20a, which flows through the gas inlets 23c and 23d, does not strike a surface frontally, but rather flows, in a flow-optimised manner, into a pressure chamber or into at least two areas or recesses 24a and 24b of the pressure chamber. The gas flow 20a can calm down in the pressure chamber, ensuring fewer eddies. The gas is guided to the nozzle 19 along the wall in the downward-oriented manner via at least four gas conduits 26a—ten gas conduits 26a in the example shown—and at least one equalising channel 27a. The equalising channel 27a is formed concentrically around the flow axis.

[0039] FIG. 3 shows a sectional view of a gas guide 11b according to a second exemplary embodiment. Here, the upper part 21b and the lower part 22b as well as the gas flow channels 25c and 25d are shaped such that the gas flow 20b, which flows through the gas inlets 23e and 23f, does not strike a surface frontally, but rather flows, in a flow-optimised manner, into, in this case four, pressure chambers 24c, 24d, 24e and 24f, where the gas flow 20b is able to calm down, thus ensuring fewer eddies. The gas flow channels 25c and 25d here each comprise four subchannels, between which a gas-conducting element is provided in the form of a flow divider. The gas is guided to the nozzle 19 along the wall in the downward-oriented manner via at least four gas conduits 26b—eight gas conduits 26b in the example shown—and at least one equalising channel 27b. A plurality of gas conduits 26b thus open or merge into an equalising channel 27b.

[0040] FIG. 4 shows a sectional view of the gas guide 11c according to the first and second exemplary embodiments, having the upper part 21c and the lower part 22c.

[0041] FIG. 5 shows an enlarged detail of area X of FIG. 4. The function of the gas flow 20c, which flows from the pressure chamber 24g into the equalising channel 27c via the gas conduit 26c, is described with reference to FIG. 5. Directed in this way, the gas flow 20c flows to the nozzle 19 along the wall of the lower part.

[0042] The gas flow 20c is first guided into the pressure chamber 24g via a plurality of gas inlets (not shown here). This feed can extend perpendicular, that is to say radially, or essentially perpendicular to flow axis S. The gas inlets can also run into the pressure chamber 24g at an angle. The gas flow 20c extends into the gas conduit 26c starting from the pressure chamber 24g. At least four gas conduits are provided, one gas conduit 26c of which is shown.

[0043] The gas conduits can each be formed between two ribs. The ribs and the gas conduits first extend in a radial direction and then in an increasingly axial direction towards the nozzle or towards a workpiece.

[0044] The gas conduits 26c then merge into the equalising channel 27c, which is formed concentrically around flow axis S. The equalising channel 27c comprises an outflow port 28 at its lower edge in the flow direction. The gas conduits 26c and the equalising channel 27c, or its outer contour remote from flow axis S, extend at a, preferably continuously, changing angle with respect to flow axis S. The angle with respect to flow axis S decreases in flow direction, that is from top to bottom. In other words, the angle gets increasingly shallower. This design results in no torsion being generated with respect to flow axis S. If there is no equalising channel, the gas conduits each have a corresponding outflow port. The outflow port 28 is formed in a convex manner for the gas flow 20c on the radially outer side.

[0045] This design of the equalising channel 27c or the outflow port 28 leads to the formation of the Coanda effect, which favours the flow guide, since the gas flow 20c is basically drawn further along the contour of the equalising channel 27c or along the contour of the gas conduit 26c.

[0046] The cross-sections of the at least two gas flow channels 25a, 25b, 25c, 25d, of the connection and the gas inlets 23a and 23b, respectively, of the pressure chamber 24, the gas conduits 26a, 26b and of the equalising channel 27c are dimensioned such that the gas or gas flow 20d has a maximum flow rate at the outflow port 28 from the equalising channel 27c and the gas conduits 26a, 26b, respectively.

[0047] The cross-sections are not considered individually, for example, per gas conduit, but as a whole, that is for all gas conduits. Accordingly, the cross-section of the gas conduits is derived by multiplying the number of gas conduits with the respective individual cross-sections. The smallest cross-section is in the area of the outflow port 28.

[0048] FIG. 6 shows a schematic perspective view of a laser cutting machine 200 having a laser cutting head 10. The laser cutting head 10 is arranged on a movable bridge 202, so that it can be moved in at least the x and y directions. A laser source 204 generates laser light and feeds it to the laser cutting head 10 via an optical fibre. A workpiece 208, for example a sheet, is cut by the laser beam.

[0049] The gas guide 11 presented here, or the laser cutting head 10 equipped therewith, or the laser cutting machine 200 equipped therewith, allows flow-mechanically optimised gas flow, as a result of which gas consumption can be reduced, and cutting quality and/or cutting rate improved.