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; welding the two components by a laser beam, wherein, by repeated switching on and off of the laser beam, a multiplicity of welding pulses are produced which are each interrupted by welding-free pause intervals, in which the laser beam is switched off, wherein each welding pulse produces a local welding area in which material of the two components is melted and fused to a locally limited extent, and individual welding areas of the welding areas produced by the welding pulses overlap.

2. The method as claimed in claim 1, wherein the laser beam remains stationary relative to the components during the individual welding pulses, whereby, during a welding pulse, the respective welding area is irradiated continuously with laser light.

3. The method as claimed in claim 1, wherein individual welding areas of the welding areas produced by the welding pulses overlap to form a cohesive, fluid-tight weld seam.

4. The method as claimed in claim 1, wherein the laser beam is positioned such that a currently produced welding area overlaps with an already welded welding area.

5. The method as claimed in claim 4, wherein a currently produced welding area overlapping with an already produced welding area is produced only when the already produced welding area has already solidified or substantially solidified.

6. The method as claimed in claim 1, wherein a currently produced welding area overlaps with a welding area which was produced directly before the last pause interval.

7. The method as claimed in claim 1, wherein a currently produced welding area is at a distance from a welding area which was produced directly before the last pause interval and is therefore free from overlapping with respect to the welding area produced directly before the last pause interval.

8. The method as claimed in claim 1, wherein the pulse durations of the multiplicity of welding pulses lie within the range of between: 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.

9. The method as claimed in claim 1, wherein the pulse durations of the multiplicity of welding pulses are identical in length.

10. The method as claimed in claim 1, wherein the pulse durations of the multiplicity of welding pulses are different in length.

11. The method as claimed in claim 1, wherein a power density of the laser beam lies within the range of between 104 watt/cm2 and 1010 watt/cm2.

12. The method as claimed in claim 11, wherein the power density of the multiplicity of welding pulses is identical in size.

13. The method as claimed in claim 11, wherein the power density of the multiplicity of welding pulses is different in size.

14. The method as claimed in claim 11, wherein the laser beam has a beam diameter or a beam width which lies within the range of between 40 m and 4 mm.

15. The method as claimed in claim 14, wherein the beam diameter or the beam width of the laser beam is in each case identical for the multiplicity of welding pulses.

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

17. The method as claimed in claim 1, wherein the beam diameter or the beam width of the laser beam is different for individual welding pulses of the multiplicity of welding pulses.

18. 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.

19. The method as claimed in claim 1, wherein metal components are used as the first and second components.

20. The method as claimed in claim 1, wherein plastics components are used as the first and second components.

21. The method as claimed in claim 1, wherein at least one of the components is a component which is partially or completely coated with a coating.

22. The method as claimed in claim 21, wherein use is made of a component with a coating, the melting point or vaporization temperature of which is lower than the melting point or vaporization temperature of the component material to which the coating is applied.

23. The method as claimed in claim 1, wherein a stainless steel sheet-metal, an aluminum, or an aluminum alloy, is used as at least one of the components.

24. The method as claimed in claim 1, wherein a galvanized component is used as at least one of the components.

25. The method as claimed in claim 1, wherein the first component is a cast component and the second component is a component made from a different material which is welded onto the cast component or is welded into the cast component.

26. The method as claimed in claim 1, wherein the first component is a ball made from steel, aluminum or thermoplastic, which is welded onto the second component.

27. The method as claimed in claim 26, wherein by way of the multiplicity of welding areas in a contact region of the ball on the second component, a weld seam extending around the ball in the contact region is produced.

28. The method as claimed in claim 1, wherein a thickness of the first component and/or a thickness of the second component lies within a range of between 0.3 mm to 5 mm.

29. The method as claimed in claim 1, wherein at least one of the two components is a body component of a vehicle body to be produced.

30. The method as claimed in claim 1, wherein during a welding pulse, a power density of the 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

[0034] FIG. 1 shows the welding of two sheet metal components in a schematic illustration.

[0035] FIG. 2 shows the welding of a ball onto a sheet metal component.

[0036] FIG. 3 shows the sequential production of a weld seam from a multiplicity of welding areas.

[0037] FIG. 4 is a diagram which describes the laser power over time.

[0038] FIGS. 5-9 show exemplary embodiments with different seam shapes.

DETAILED DESCRIPTION OF THE DRAWINGS

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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].

[0045] 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].

[0046] 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.

[0047] 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.