Method for welding components

Abstract

A method for welding components includes the following steps: providing a first component and a second component; bringing together the two components; welding the two components by use of a laser beam, wherein a plurality of welding impulses are generated through the repeated activation and deactivation of the laser beam, with each welding pulse being interrupted by welding-free rest intervals in which the laser beam is deactivated, wherein a local welding area is generated by each welding pulse, in which material of the two components is melted and fused in a locally limited manner, wherein individual welding areas of those generated by the welding pulses overlap.

Claims

1. A method for welding components, the method comprising the steps of: providing a first component and a second component; placing the two components on each other; and welding the two components together by a laser beam, wherein the welding comprises the steps of: switching on the laser beam for a first pulse duration, during which the laser beam is stationary, so as to generate a first welding pulse at a first position that melts and fuses the two components and thereby produces a first local welding area at the first position; switching off the laser beam for a welding-free pause interval, during which the first local welding area solidifies and the laser beam is moved relative to the two components from the first position to a second position; and after the welding-free pause interval, switching on the laser beam for a second pulse duration, during which the laser beam is stationary, so as to generate a second welding pulse that melts and fuses the two components at the second position and thereby produces a second local welding area at the second position, the second position overlapping the first position, wherein the welding-free pause interval is of different duration than at least one of: the first pulse duration and the second pulse duration, and wherein the first component is a ball made from steel, aluminum or thermoplastic, which is welded onto the second component that is a body component of a vehicle body to be produced.

2. The method as claimed in claim 1, wherein the first local welding area and the second local welding area overlap within a series of local welding areas to form a cohesive, fluid-tight weld seam.

3. The method as claimed in claim 1, wherein the second welding pulse directly follows the welding-free pause interval, which directly follows the first welding pulse.

4. The method as claimed in claim 1, wherein the first pulse duration and the second pulse duration are each respectively within: 0.1 ms to 100 ms, 0.1 ms to 50 ms, 0.1 ms to 20 ms, 1 ms to 20 ms, or 1 ms to 10 ms.

5. The method as claimed in claim 1, wherein the first pulse duration is of identical duration to the second pulse duration.

6. The method as claimed in claim 1, wherein the first pulse duration is of different duration than the second pulse duration.

7. The method as claimed in claim 1, wherein the laser beam has a power density between 10.sup.4 watt/cm.sup.2 and 10.sup.10 watt/cm.sup.2.

8. The method as claimed in claim 7, wherein the first welding pulse has an identical power density to the second welding pulse.

9. The method as claimed in claim 7, wherein the first welding pulse has a different power density than the second welding pulse.

10. The method as claimed in claim 7, wherein the laser beam has a beam diameter or a beam width between 40 μm and 4 mm.

11. The method as claimed in claim 10, wherein the first welding pulse has an identical beam diameter or beam width to the second welding pulse.

12. The method as claimed in claim 1, wherein the laser beam has a circular beam cross section.

13. The method as claimed in claim 1, wherein the first welding pulse has a different beam diameter or beam width than the second welding pulse.

14. The method as claimed in claim 1, wherein the welding is carried out with a repetition rate within a range of between 200 Hz and 10 kHz.

15. The method as claimed in claim 1, further comprising: producing via the welding, a weld seam extending around the ball in a contact region of the ball on the second component.

16. The method as claimed in claim 1, wherein a power density of the first welding pulse and/or the second welding pulse is changed by: changing the laser power with the beam cross section being kept constant, changing the beam cross section with the laser power being kept constant, or changing the laser power and the beam cross section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the welding of two sheet metal components in a schematic illustration.

(2) FIG. 2 shows the welding of a ball onto a sheet metal component.

(3) FIG. 3 shows the sequential production of a weld seam from a multiplicity of welding areas.

(4) FIG. 4 is a diagram which describes the laser power over time.

(5) FIGS. 5-9 show exemplary embodiments with different seam shapes.

DETAILED DESCRIPTION OF THE DRAWINGS

(6) FIG. 1 shows two metal sheets 1, 2 lying one on the other, wherein the thickness of the metal sheet 1 is s.sub.1 and the thickness of the metal sheet 2 is s.sub.2. For example, s.sub.1 and s.sub.2 can lie within the range of between 0.3 mm and 3 mm. In the edge region of the metal sheet 1, the two metal sheets 1, 2 have already been welded to each other here by means of a fillet weld 3. However, previous welding by means of the fillet weld 3 is not necessarily required.

(7) The two metal sheets 1, 2 are additionally welded to each other by means of a butt weld 6 using a laser welding device 4 which produces a laser beam 5.

(8) The laser welding device 4 is operated in a pulsed manner here, i.e., by periodic switching on and off of the laser beam 5, a multiplicity of welding pulses are produced one after another and are each interrupted by welding-free pause intervals.

(9) By way of pulsed welding of this type, a ball 7 can also be welded onto a component 1. The ball 7 can be connected to the component 1 by a multiplicity of welding points. Entirely analogously as above, the laser welding device is operated in a pulsed manner here. The laser welding device can be guided here around the contact region of the ball 7. This makes it possible to produce a multiplicity of mutually overlapping welding points or welding areas, as a result of which a very high-quality “encircling” weld seam 8 can be produced.

(10) FIG. 3 shows two metal sheets 1, 2 which lie one on the other and are connected to each other by a weld seam 10 which is just being produced. The weld seam 10 is constructed sequentially here by individual welding areas overlapping in a scale-like manner. In order to limit the admission of heat, which is produced by the laser beam 5, into the metal sheets 1, 2 to a local extent as far as possible, it can be provided that the individual welding areas are not all produced next to one another or following one another. For example, it can be provided that the welding areas are produced one after another in the sequence specified by the reference signs 11-22. After the production of the welding area 11, the latter can cool. The welding area 12 produced following the welding area 11 is at a sufficiently large distance from the welding area 11 that the admission of heat into the welding area 12 leaves the cooling of the welding area 11 substantially unaffected, etc.

(11) FIG. 4 describes the pulsed welding according to the invention with reference to a diagram in which the laser power P.sub.laser is plotted over the time t. A first welding pulse extends from point in time 0 to point in time t.sub.1. This is followed by a pause interval of length [t.sub.1, t.sub.2].

(12) This is followed by a further welding pulse of length [t.sub.2, t.sub.3], which is followed again by a pause interval of length [t.sub.3, t.sub.4]. The period duration, i.e. the length of a welding pulse and a pause interval following the latter, is therefore T=[t.sub.2, t.sub.4].

(13) FIGS. 5-9 clarify that the invention is not restricted to the production of the seam shapes shown in FIGS. 1 to 3 but also can be used in the production of all other seam shapes, e.g. in the production of fillet welds (FIG. 6), for example at the lap joint (end fillet weld), at the T joint (FIG. 7), at the flared joint, in the production of classic I seams at the lap joint, etc.

(14) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.