WO2015144399A1

WO2015144399A1 - Method and device for laser beam cutting

Info

Publication number: WO2015144399A1
Application number: PCT/EP2015/054459
Authority: WO
Inventors: Florian OEFELE; Christian Roos
Original assignee: Bayerische Motoren Werke Aktiengesellschaft
Priority date: 2014-03-24
Filing date: 2015-03-04
Publication date: 2015-10-01
Also published as: DE102014205387A1; EP3122511A1

Abstract

The invention relates to a method for the laser beam cutting of a workpiece in which a laser beam (L) is directed at the workpiece (200) by means of a scanner-based remote laser beam welding device and a molten bath is produced at a machining point (220), a cutting gas stream (S) is directed at the machining point (220) for blowing molten material out of the machining point (220), and the machining point (220) and the workpiece (200) make a relative movement along a cutting contour. The invention also relates to a device for laser beam cutting.

Description

description

Method and apparatus for laser beam cutting

The invention relates to a method and a device for

Laser beam cutting, in particular for laser beam cutting using a scanner-based remote laser beam welding apparatus.

In remote laser beam machining, a laser beam becomes large

Working distance directed to a workpiece. Typically, this is

Working distance between the workpiece surface and exit point of the laser beam from the optics in remote laser beam machining more than 300 mm and can, for. up to 1600 mm. Scanner-based remote laser beam devices have scanner optics for beam deflection. The scanner optics directs the laser beam via highly dynamically adjustable mirrors (or via a two-axis adjustable mirror) within the working range of the scanner optics. Furthermore, the scanner optics comprise beam shaping means for focusing the laser beam, e.g. a plan field optics or an optical system with translationally movable lens.

Basically, both can be welded and cut with a laser beam. However, these two methods make different demands on the parameters of the laser beam provided. For example, cutting processes require laser beams of significantly higher beam quality. For example, for cutting, higher power density, smaller laser beams are used

Focus diameter and higher depth of field used than for welding. These requirements are implemented by the system by the use of beam guiding and shaping means, which are optimized for the respective requirements, such as. Laser light lines with a suitable diameter, optics with corresponding focal lengths (ranges) and integrated gas nozzle and

Laser beam sources with suitable wavelengths, preferably C02 laser.

In material processing, however, it is often necessary to be able to carry out both a cutting process and a welding process on a workpiece.

For this purpose, previously separate devices, a welding device and a cutting device used or the Strahlführungs- and / or Beam shaping elements of the device must be replaced depending on the type of processing.

It is therefore an object of the invention a method and an apparatus

specify what is possible with simple and inexpensive means a combination of remote laser beam welding and laser beam cutting.

In particular, a combination of remote laser beam welding and laser beam cutting should be possible without additional expensive components and special system technology and a quick change between the two methods.

This object is achieved by a method according to claim 1 and a device according to claim 8.

With regard to the method, the object of the invention is achieved by a method for laser beam cutting of a workpiece in which a laser beam is directed onto the workpiece by means of a scanner-based remote laser beam welding device and generates a molten bath at a processing point. A cutting gas stream is directed to the processing site for blowing out the molten material from the processing site. There is a

Relative movement between the machining point and the workpiece along a cutting contour.

The laser beam provided by the remote laser beam welding apparatus is designed for welding requirements. Thus, the laser beam can preferably be used for applications in body construction, e.g. have a focus diameter of 600 microns ± 200 microns when using a solid state laser, diode or C02 laser.

The cutting process is a laser beam fusion cutting. The laser beam of the remote laser beam welding apparatus generates in the workpiece

Weld pool. Preferably, the laser beam causes the formation of a vapor capillary in the workpiece, which is surrounded by molten bath similar to the deep welding. In the method according to the invention is now prevented by the use of the cutting gas flow that the molten material solidifies behind the laser beam again. Rather, the molten material is blown out and a cutting joint or cutting notch is formed in the workpiece. Due to the relative movement between the processing point and the workpiece, the cutting groove or notch moves through the workpiece.

Advantageously, no changes to the laser beam guide or optics are necessary. It can be worked with the designed for welding laser beam.

The relative movement between the processing point and the workpiece can be realized by a movement of the workpiece or by a movement of the laser beam and the cutting gas flow or by a combined movement of both the workpiece and the laser beam and the cutting gas flow. The relative movement can be determined by a movement of the scanner optics and the

Cutting gas nozzle or by a combined movement of both the scanner optics and the cutting gas nozzle and the workpiece done.

The cutting contour may have a web-shaped course, e.g. straight or winding tracks. The cutting contour may also be a closed structure, such as e.g. be a circle, quadrilateral or polygonal or any other geometric figure. Several cutting contours may also be formed in the workpiece, e.g. may be spatially spaced or adjacent to each other.

The workpiece may consist of a single component or comprise a plurality of components connected to an assembly. The components may e.g. Be sheets, three-dimensional moldings or profiles. In particular, it may be vehicle body components. The components or at least one component can e.g. consist of a metal or a metal alloy, such as e.g.

Aluminum, steel or steel or aluminum alloys. Other materials are possible. The components may e.g. have a thickness in the range of 0.5 mm to 4 mm, preferably in the range of 0.7 mm to 1, 5 mm.

Particularly uniform conditions for the blowing out of the molten material result when the laser beam and the cutting gas stream are arranged stationary relative to each other during cutting. Preferably, for this purpose, the laser beam can be positioned by means of the scanner optics for cutting gas flow and for the duration of the cutting process, the scanner axes can be made rigid. To avoid unwanted back reflection, the laser beam is eg

preferably directed stinging on the workpiece. For example, the laser beam between 0 and 5 degrees with respect to the perpendicular to the

Be inclined workpiece surface.

The discharge of the molten material from the processing station can be improved by supplying the cutting gas stream sluggishly.

For example, the cutting gas flow may be at an angle to the incident laser beam in the range of greater than 0 degrees to a maximum of 45 degrees, preferably in the range of 5 degrees to 45 degrees. The cutting gas thus pushes the melt back down out of the kerf, whereby the quality of the

Cutting edges can be improved.

As the cutting gas, e.g. Compressed air or an inert gas, e.g. Nitrogen, alternatively, other gases may be used. In order to obtain an optimum discharge of the molten material from the kerf, the cutting gas may be e.g. at a pressure of 300 kPa or more, preferably at a pressure of 300 kPa to 3000 kPa, or from 500 kPa to 2000 kPa, to the processing station.

To increase the flexibility with regard to possible cutting geometries, the movement of the machining point relative to the workpiece is preferably effected by means of a multi-axis industrial robot, e.g. a gantry robot or articulated robot with e.g. five, six or more axes.

Advantageously, with the provided laser beam not only

cut, but also a weld can be formed in the workpiece. For this purpose, it is only necessary to interrupt the cutting gas flow for the duration of the weld.

The inventive device for laser beam cutting has a scanner-based remote laser beam welding device, the at least one laser source, a beam guiding device, and a scanner optics for

Positioning and focusing of a laser beam on a processing point of a workpiece includes. Furthermore, the device for Laser cutting a cutting gas nozzle, which is set up for

Blowing out molten material from the processing station.

The scanner-based remote laser beam welding apparatus is configured to provide a laser beam optimized for welding. The laser beam generated by the laser source is coupled into the scanner optics via the beam guiding device, which may have one or more optical fibers and / or a mirror system depending on the laser source used. Within the scanner optics, the beam shaping and focusing takes place, as well as the positioning of the laser beam on the workpiece.

Preferably, the remote laser beam welding apparatus is designed for welding the workpiece. The scanner optics and the beam guiding device are set up accordingly to provide a laser beam suitable for this application.

By integrating a cutting gas nozzle to the remote laser beam welding device, it is possible to discharge molten material from the processing point and thus not only to weld, but also to form notches or cuts in the workpiece. This is a

Cutting gas flow directed through the cutting gas nozzle to the processing site. The cutting gas stream drives or blows the molten material generated by the laser beam from the processing point.

The cutting gas nozzle is e.g. via a gas supply line with a

Schneidgaszuführeinrichtung connected so that the cutting gas stream can be provided with the required pressure and the desired volume flow.

Preferably, the cutting gas nozzle is arranged in the working field of the scanner optics. As a result, the cutting gas nozzle can be arranged both close to the workpiece to reduce the necessary cutting gas volume flow, as well as be arranged at an acute angle to the laser beam, whereby the

Blowout conditions of the melt can be improved. An arrangement of the cutting gas nozzle optimized in terms of gas consumption results if the outlet opening of the cutting gas nozzle is arranged in a range of 1 cm to 3 cm apart from the processing location.

The apparatus may further comprise a multi-axis industrial robot, e.g. a gantry robot or a Gelenkarmroboter, on which the scanner optics is arranged. Preferably, the articulated arm robot has five, six or more axes. The multi-axis industrial robot allows additional

Movements of the scanner optics and thus greater freedom of movement during workpiece machining, especially in cutting contour processing. If the cutting gas nozzle is arranged stationary relative to the scanner optics, then scanner optics and cutting gas nozzle are preferably moved together by the industrial robot.

Preferably, the cutting gas nozzle and the scanner optics are arranged stationary relative to each other. For example, the cutting gas nozzle on the

Scanner optics attached or cutting gas nozzle and scanner optics can be attached to a common bracket. This allows a particularly simple movement of the cutting gas nozzle along the cutting contour.

In particular, the cutting gas nozzle and scanner optics may be co-located on the industrial robot, e.g. be attached to the same hand axis.

The cutting gas nozzle may be formed around the laser beam so that the cutting gas flow exits around the laser beam. Alternatively, the

Cutting gas nozzle to be arranged next to the laser beam. Preferably, the cutting gas nozzle is arranged in the cutting direction in front of the laser beam.

The cutting gas stream is preferably guided sluggishly to the laser beam, so that the cutting gas stream can blow out the melt counter to the cutting direction. For this, e.g. the longitudinal axis of the cutting gas nozzle may be arranged at an angle to the longitudinal axis of the laser beam impinging on the workpiece, which is in a range of more than 0 degrees and at most 45 degrees, preferably in a range of 15 degrees to 45 degrees.

Furthermore, the device can have a control device that is set up to rigidly set the scanner axes during the cutting process. As a result, the laser beam during the cutting process relative be arranged stationarily to the cutting gas stream, resulting in particularly consistent conditions at the processing site. The

Control device may preferably also control the laser source and focusing optics and the movement of the industrial robot. Likewise, the cutting gas supply can be controlled by the control device.

The laser source preferably has a solid-state laser, in particular a disk or fiber laser, which results in a low reflection of the radiation on metallic components and an improved energy input. The

Beam guiding device preferably has one or more laser light cables. These allow flexible guidance of the laser light to the scanner optics.

The device according to the invention is also suitable for welding and can be used to form a weld in the workpiece. For this purpose, the cutting gas nozzle can be switched out of operation for the duration of the weld. Alternatively, the cutting gas nozzle can be dismantled, this may be e.g. releasably attached to the device or to the scanner optics.

In other words, by integrating a cutting gas nozzle to the

Scanner optics of a remote laser beam welding device

Combination method for remote laser welding and

Laser beam cutting provided. The cutting gas jet is over the

Scanner optics aimed at the point of impact of the laser beam and the

Scanner axes are set rigid. The cutting movement can be realized via the six axes of a robot system.

Advantageously, the scanner optics of the remote laser beam welding apparatus can be used. Except for the cutting gas nozzle no additional system technology is necessary. A combination of cutting and welding is possible without further additional effort. Thus, a generation of variants without special complex special system technology and without additional cost and without additional space requirement is possible.

Further advantageous embodiments of the invention will become apparent from the

Dependent claims. The above-described characteristics, features and advantages of this invention as well as the manner in which they are achieved will become clearer and more clearly understood in connection with the following description of the invention

Embodiments. If the term "can" is used in this application, it is both the technical possibility and the actual technical implementation.

In the following is en embodiment with reference to the accompanying

Drawings explained. It shows:

Figure 1 is a schematic diagram of a device according to the invention 0 according to one embodiment.

FIG. 2 shows an enlarged view of the scanner optics with a cutting gas nozzle of the device from FIG. 1 arranged thereon.

The apparatus 10 comprises a remote laser beam welding apparatus having a laser source 00 with a solid-state laser. The laser radiation generated by the laser source 00 is guided by means of a beam guiding device 1 10 in the form of one or more optical fibers to a scanner optics 120 and coupled there. The scanner optics 120 includes mirrors, not shown, for steering the

Laser beam and beam shaping agent. By means of the scanner optics 120, the laser beam L is directed onto the workpiece 200 and focused. The scanner optics 120 is arranged on the hand axis of an articulated arm robot 130. Of the

Articulated arm robot 130 has six axes of movement, indicated by the double arrows in FIG. 1. By means of robot 130, scanner optics 120 can be guided over a workpiece 200. The workpiece 200 is on a

Workpiece holder 210 arranged and by means not shown

Fixed clamping elements.

Furthermore, a cutting gas nozzle 140 is attached to the scanner optics 120 by means of a holder 150. The cutting gas nozzle 140 is connected to a gas supply device 170 via a gas line 160. From the cutting gas nozzle 140, a cutting gas stream S impinges on the workpiece 200 at a processing point 220.

For forming a cutting line in the workpiece 200, the laser beam L provided by the remote welding apparatus is also applied to the Machining point 220 directed on the workpiece 200. For this purpose, the

Laser beam L by means of the scanner device 120 by movement of the

Scanner mirror positioned. Laser beam L and cutting gas flow S then impinge on the same processing point 220. Since the laser beam L is provided by a system designed for welding, it has typical beam parameters for welding, in particular a typical one

Beam spot diameter. The laser beam causes the formation of a

Steam capillary and an adjacent molten bath in the workpiece 200. The cutting gas stream S blows the molten material from the processing point 220, so that a cutting groove or cutting notch in the workpiece is formed.

After positioning the laser beam L in relation to the cutting gas flow S or to the cutting gas nozzle 140, the scanner axes of the scanner optics 120 are set rigidly. This can be done by a control device 180 of the remote laser beam welding device, which can also control or regulate, for example, the movements of the robot 30 and / or the laser source 00.

Laser beam L and cutting gas flow S are then arranged stationary relative to each other.

To form a cutting line along a cutting contour, the

Scanner optics 120 along with cutting gas nozzle 140 of the robot 130 over the workpiece 200 moves.

FIG. 2 shows a detailed view of the scanner optics 120 with a cutting gas nozzle 140 attached thereto. The cutting gas nozzle 140 is arranged within the working field 122 of the scanner optics 120. The laser beam can thus hit the workpiece at an angle close to 90 degrees, and at the same time the cutting gas nozzle can be arranged in close proximity to the machining point 220.

The laser beam L can not be positioned perpendicular to the workpiece to avoid a back reflection, but can be inclined by an angle α relative to the vertical. The angle α is preferably in a range between 0 and 5 degrees.

To improve the material discharge from the cutting joint is the

Cutting gas nozzle 140 arranged sluggish. The cutting gas flow S is arranged at an angle β in the range of greater than 0 degrees to 45 degrees to the laser beam L. The cutting gas stream may be separated from the control device of the remote Laser beam welding device to be controlled or alternatively by a separate control device.

The embodiment is not to scale and not limiting.

Modifications in the context of expert action are possible.

LIST OF REFERENCE NUMBERS

10 Apparatus for laser beam cutting

100 laser source

110 aerial guidance

120 scanner optics

130 articulated robot

140 cutting gas nozzle

150 bracket

160 gas line

170 Gas supply device

180 control device

200 workpiece

210 workpiece holder

220 processing point

L laser beam

S cutting gas flow

α, ß angle

Claims

claims

1. A method for laser beam cutting a workpiece in the

a laser beam (L) is directed onto the workpiece (200) by means of a scanner-based remote laser beam welding device and generates a molten bath at a processing point (220),

a cutting gas stream (S) is directed to the processing site (220) for blowing molten material from the processing site (220),

a relative movement between the machining point (220) and the workpiece (200) takes place along a cutting contour.

2. The method according to claim 1, wherein

the laser beam (L) and the cutting gas stream (S) are arranged stationary relative to each other during cutting.

3. The method according to claim 1 or 2, wherein

the laser beam (L) is directed sharply toward the workpiece (200), in particular at an angle between 0 degrees and 5 degrees.

4. The method according to any one of claims 1 to 3, wherein

the cutting gas stream (S) is supplied sluggishly, in particular at an angle to the incident laser beam (L) in the range of more than 0 degrees to a maximum of 45 degrees, or of 15 degrees to 45 degrees.

5. The method according to any one of claims 1 to 4, wherein the

Cutting gas with a pressure of 300 kPa or more, in particular with a pressure of 300 kPa to 3000 kPa or 500 kPa to 2000 kPa

Processing point (220) is supplied.

6. The method according to any one of claims 1 to 5, wherein the movement of the machining point (220) relative to the workpiece (200) by means of a multi-axis industrial robot (130).

7. The method according to any one of claims 1 to 6,

wherein a weld is further formed in the workpiece (200) with the laser beam (L).

8. Apparatus for laser beam cutting with:

a scanner-based remote laser beam welding apparatus, the at least one laser source (100), a beam guiding device (110) and a

Scanner optics (120) for positioning and focusing a laser beam (L) on a processing point (220) of a workpiece (200) includes, and

a cutting gas nozzle (140) adapted for blowing molten material from the processing station (220).

9. Device according to claim 8, wherein

the cutting gas nozzle (220) in the working field (122) of the scanner optics (120) is arranged.

10. Device according to one of the claims 8 or 9, wherein

a gas outlet opening of the cutting nozzle (140) in a range of 1 cm to 3 cm spaced from the processing point is arranged.

11. Device according to one of the claims 8 to 10, further comprising a multi-axis industrial robot (130) on which the scanner optics (120) is arranged.

12. Device according to one of the claims 8 to 11, wherein

the cutting gas nozzle (140) and the scanner optics (120) are arranged stationary relative to one another.

13. Device according to one of the claims 8 to 12, wherein

the cutting gas nozzle (40) is arranged in the cutting direction in front of the laser beam (L).

14. Device according to one of the claims 8 to 13, with a

Control device (180) adapted to rigidly set the scanner axes during the cutting process.

15. Device according to one of the claims 8 to 14, wherein

the laser source (100) has a solid-state laser, in particular a disk or fiber laser.