WO2006072550A1

WO2006072550A1 - Device for laser beam welding on surfaces of rotationally symmetrical components comprising a device for displacing the laser beam along the workpiece

Info

Publication number: WO2006072550A1
Application number: PCT/EP2005/057025
Authority: WO
Inventors: Friedrich Lupp
Original assignee: Siemens Aktiengesellschaft
Priority date: 2005-01-03
Filing date: 2005-12-21
Publication date: 2006-07-13
Also published as: DE102005000631A1

Abstract

The invention relates to a device for welding, by means of a pulsed laser beam, rotationally symmetrical workpieces, in particular, in fine work and microsystem technology components, the electrical and car industry, comprising a device for positioning and displacing the workpiece, a device for producing at least one pulsed laser beam and a device for positioning the laser beam on a surface of the workpiece. The inventive welding device is characterised in that it comprises a device for displacing the laser beam along the surface of the fixed workpiece.

Description

DEVICE FOR LASER RADIATION WELDING ON COATINGS OF ROTATION SYMMETRIC COMPONENTS WITH A DEVICE FOR MOVING THE LASER RADIATION ALONG THE WORKPIECE

The invention relates to a device and its use for welding workpieces with pulsed laser radiation, in particular for components of Feinwerk- and microsystem technology, the electrical and automotive industry according to the preamble of the main claim.

WO 03/013779 A1 discloses a method in which with a single laser pulse a complete weld with high quality and cost-effectiveness is produced. For this purpose, the laser beam must be guided within this one laser pulse at a very high speed over the entire weld seam to be produced. In this case, either the laser beam or the workpiece is moved. The method is advantageous if the weld seam is completely accessible from above and the laser beam is positioned and moved via a scanner system.

However, if the procedure is such that the component for producing the weld is rotated about an axis perpendicular to the laser beam in a plane of the drawing, then centrifugal forces generated by the necessary high rotational speeds cause ejection of the melt and thus defects in the weld seam. This could be proven by experiments. According to WO03 / 01377 Al, this problem has not yet been recognized.

It is an object of the invention to provide a device according to the main claim such that an ejection of melt and thus a generation of imperfections in the weld are avoided, wherein the created weld seam is to be generated very homogeneous. It is also intended to provide a corresponding use of the device. The object is achieved by a device according to the main claim and a use according to the independent claim. Advantageous embodiments can be found in the subclaims.

The device for moving the laser beam along the surface of the workpiece functions in such a way that when welding or. during a laser pulse, the workpiece is fixed in place and only the laser beam is moved in space. By fixing the workpiece, an ejection of melt and the generation of defects in the weld are prevented by acting on the stationary workpiece no centrifugal forces. The workpiece is moved only outside a laser pulse.

Fixing means that the workpiece is arranged stationary. Positioning means that the workpiece or a laser beam is provided stationary.

Particularly advantageous is a mirror for generating a homogeneous weld, in particular such shaped or displaceable, that in a plane perpendicular to the rotational axis of symmetry of the workpiece, the course of the deflection points of the laser beam relative to the course of the positioning of the laser beam along the lateral surface of the workpiece is generated in parallel , The distance between a respective deflection point of the laser radiation and the respective positioning point of the laser radiation on the lateral surface of the workpiece thus remains constant. In this way, the energy input at the respective positioning points of the laser radiation on the lateral surface of the workpiece is also constant. The weld is thus formed very homogeneously under constant conditions.

The deflection points of the laser beam are those points on the mirror surface onto which a laser beam is incident at a certain angle and from which the laser beam is emitted. is reflected speaking. By moving the laser beam or by moving the mirror, the coordinates of the deflection points change with respect to the mantle surface. This creates a course of the deflection points. Positioning points of the laser beam are the points where the deflected laser beam impinges on the lateral surface of the workpiece. The course of the positioning points is generated by the movement of the laser beam relative to the lateral surface.

According to an advantageous embodiment of the mirror is fixed, the parallelism generated by the shape of the mirror and thus associated with the mirror only the means for positioning the laser beam.

According to an alternative embodiment, the mirror is movable, the parallelism generated by the path of movement of the mirror and thus associated with the mirror of the means for positioning and in addition to the means for moving the laser beam.

According to an advantageous embodiment, the mirror in the said plane has an annular or rectangular shape parallel to the positioning points of the laser beam.

According to an alternative advantageous embodiment, the mirror moves in said plane along an annular or rectangular movement path parallel to the positioning points of the laser beam.

According to an advantageous embodiment, a device rotating around the rotational symmetry axis of the generated laser beam and the identical axis of rotational symmetry of the workpiece for deflecting, positioning and moving the laser beam is provided. This device is particularly advantageous by means of a deflection prism, an optical wedge and / or at least one mirror or the like Optics provided. By rotating this device, the laser beam moves on the mantle surface of the workpiece. Further optional optical units direct the laser beam onto the mantle surface.

According to a further advantageous embodiment, the rotating device additionally splits the laser beam into a plurality of laser beams, in particular by means of mirrored prisms. Such prisms have the shape of a prism, in a bipartite. In a tripartite division, a rotating tetrahedron is proposed, in a quartering a rotating pyramid is proposed. Accordingly, any number of laser beams can be generated.

A device which generates a widened laser beam is advantageous, since the laser beam splitting is simplified or used with it. the number of practically producible laser beams is increased.

According to an advantageous embodiment, a device for changing the intensity distribution of a laser beam on the workpiece is also provided. With this negative effects of high-speed welding, such as so-called "humping effects" or inhomogeneities in welding, can be compensated.

According to an advantageous embodiment, the positioning and the movement of the laser beam are generated along the surface of the workpiece by means of a conventional scanner system which is already provided in a highly adaptable manner.

According to an advantageous embodiment, a plurality of parallel scanner systems for the simultaneous generation of multiple laser beams can be provided on the workpiece. According to an advantageous use of a device according to one or more of the device claims, a workpiece is moved only outside a laser pulse. Also in this way, ejection of melt is prevented.

The invention will be described with reference to embodiments in conjunction with FIGS. described in more detail. Show it :

Fig. 1 shows a first embodiment of a mirror according to the invention;

Fig. 2 shows a cross section to the first embodiment;

Fig. 3 shows a second embodiment of a mirror according to the invention;

Fig. 4 shows an exemplary embodiment of a device for deflecting, positioning and moving a laser beam;

Fig. 5 shows an exemplary embodiment of a device for splitting, deflecting, positioning and moving a laser beam;

Fig. 6 shows another embodiment of a device for deflecting, positioning and moving a laser beam;

Fig. 7 shows a further embodiment of a device for splitting, deflection, positioning and loading movement of a laser beam.

According to an embodiment of FIG. 1, with the aid of a specially shaped mirror, a weld seam located on the face of a round workpiece is also completely accessible from above. The necessary mirror blank has the form of a ring whose inside is conically shaped. On this formation, a reflective layer is applied. This is shown in FIG. 1st Fig. FIG. 2 shows a corresponding cross section of the arrangement according to FIG. Second

For welding rectangular workpieces, a mirror arrangement according to FIG. 3 are used.

The in Fig. 1 and FIG. The mirror assemblies shown in FIG. 3 can be simultaneously irradiated from above with one or more laser beams to be positioned in each case in such a way that the desired weld seam results within a laser pulse. If only one laser beam is used, then for example a conventional scanner system is available. For cross-sectionally round workpieces, the removal of a circle required for producing a seam on the lateral surface can also be effected by a deflection prism, in particular by an optical wedge or alternatively by means of a grazing mirror, which is rotated about the axis of the incident laser beam , This is shown in FIG. 4. This can be done with the required high rotational speeds. If several laser beams are to be used simultaneously, a plurality of scanner systems which are suitably arranged are to be used accordingly.

Alternatively, again for round workpieces a rotating prism according to FIG. 5 are used for generating the circular path and at the same time for splitting a laser beam into two. If splitting into three beams is required, then a rotating tetrahedron made of optical material is used, at four a rotating pyramid, etc. , It is advantageous for the splitting into two or more beams when these optical arrangements are used together with an expanded laser beam.

Alternatively, an arrangement of a plurality of mirrors, which are generally rotated about the same axis as the workpiece can be used. The mirrors are then arranged so that the beam can hit the cylinder surface laterally. In Fig. Figure 6 shows a device with 3 mirrors, a device with 2 mirrors or more than 2 mirrors is also usable.

Again, it is possible to divide the beam with corresponding mirrored prisms in several beams. This is shown in FIG. 7. Correspondingly adapted tetrahedrons, pyramids, etc. be used . This alternative arrangement is rotated at extremely high speeds, typically in a range of 10 to 50 revolutions per second. This embodiment is particularly advantageous since the laser beam is not additionally deformed, as in an arrangement according to FIG. 1. On the other hand, this can

Deformation also prove to be an advantage when it is used to realize a linear beam distribution on a workpiece.

Negative effects in high-speed welding, such as humping effects or other inhomogeneity-producing effects, can be influenced by changing the intensity distribution of the laser beam on the workpiece.

Claims

claims

1. A device for welding with a pulsed laser beam of rotationally symmetrical workpieces, in particular of components of precision engineering and microsystem technology, the electrical and automotive industries, with

a device for positioning and moving the workpiece,

a device for generating at least one laser beam,

a device for positioning the laser beam on a lateral surface of the workpiece,

- A device for moving the laser beam along the surface of the fixed or positioned workpiece.

2. Device according to claim 1, with

- A mirror for deflecting the first along a rotational axis of symmetry of the workpiece extending laser beam in a direction perpendicular to the lateral surface of the workpiece, characterized in that

- The mirror is provided such that in a plane perpendicular to the axis of rotational symmetry of the workpiece, the course of the deflection points of the laser beam relative to the course of the positioning points of the laser beam along the lateral surface of the workpiece is generated in parallel.

3. Apparatus according to claim 2, characterized in that the mirror is stationary, the parallelism generated by its shape and thus associated with the means for positioning the laser beam.

4. Apparatus according to claim 2, characterized in that the mirror is movable, the parallelism generated by a movement path and thus associated with the means for positioning and movement of the laser beam.

5. Apparatus according to claim 3, characterized by an annular or rectangular shape of the mirror parallel to the positioning points of the laser beam.

6. Apparatus according to claim 4, characterized by an annular or rectangular movement path of the mirror gel parallel to the positioning points of the laser beam.

7. Device according to one or more of claims 1 to 6, characterized by a rotating about the axis of rotational symmetry of the laser beam generated and the workpiece means for deflection, positioning and movement of the laser beam.

8. Apparatus according to claim 7, characterized by a means of a deflection prism, an optical wedge and / or at least one mirror or similar optics generated rotating means.

9. Device according to claim 7 or 8, characterized by the rotating device additionally divides the laser beam into a plurality of laser beams, in particular by means of mirrored prisms.

10. Apparatus according to claim 9, characterized by an expanded laser beam generating means.

11. The device according to one or more of claims 1 to 10, characterized by means for changing the intensity distribution of a laser beam on the workpiece.

12. Device according to one of the preceding claims 1 to

11, characterized by a positioning and movement of the laser beam along the surface of the workpiece generating scanner system.

13. The apparatus according to claim 12, characterized by a plurality of parallel scanner systems for simultaneously generating a plurality of laser beams on the workpiece.

14. Use of a device according to one or more of claims 1 to 13, for welding with a pulsed laser beam welding of rotationally symmetrical workpieces, in particular components of Feinwerk- and Mikrosystemtech- nik, the electrical and automotive industry, in which the laser beam to the fixed or positioned workpiece is moved at a speed and a weld with a single laser pulse of a pulse duration is generated, and the length of the weld relative to the welding feed direction is determined mainly by the product of feed rate and pulse duration.

15. Use according to claim 14, characterized in that the workpiece is moved in time outside a laser pulse.