Method for Welding Components

Abstract

A method for welding components includes providing a first component and a second component, bringing the two components together, welding the two components by a laser beam, wherein a multiplicity of welding pulses 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. Each welding pulse creates a local welding area, 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 first and second components together, the method comprising the acts of: placing the first and second components next to one another; welding the first and second components using a laser beam, wherein a large number of welding pulses that are in each case interrupted by weld-free rest intervals in which the laser beam is switched off are produced by repeatedly turning the laser beam on and off, wherein a slit is produced in the first component that runs through the first component, the laser beam is directed into a region of the slit during the welding, each welding pulse produces a local welding area in which material of the first and second components is melted and melted together in a locally delimited fashion, wherein individual ones of the welding areas produced by the welding pulses overlap.

2. The method according to claim 1, wherein the laser beam remains stationary relative to the first and second components during the individual welding pulses such that the respective welding area is irradiated with laser light permanently throughout during a welding pulse.

3. The method according to claim 1, wherein individual ones of the welding areas produced by the welding pulses overlap one another to form a contiguous, fluid-tight weld seam.

4. The method according to claim 1, wherein the laser beam is positioned such that a welding area currently being produced overlaps with a welding area already welded.

5. The method according to claim 4, wherein a welding area currently being produced that overlaps with a welding area already produced is produced only when the welding area already produced has already solidified or has largely solidified.

6. The method according to claim 4, wherein a welding area currently being produced overlaps with a welding area that was produced immediately before the last rest interval.

7. The method according to claim 1, wherein a welding area currently being produced is located at a distance from a welding area that was produced immediately before the last rest interval, and is thus overlap-free with respect to the welding area that was produced immediately before the last rest interval.

8. The method according to claim 1, wherein the pulse durations of the large number of welding pulses lie in the range 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 according to claim 1, wherein the pulse durations of the large number of welding pulses are of equal length.

10. The method according to claim 1, wherein the pulse durations of the large number of welding pulses are of different length.

11. The method according to claim 1, wherein a power density of the laser beam lies in the range between 10.sup.4 Watt/cm.sup.2 and 10.sup.10 Watt/cm.sup.2.

12. The method according to claim 11, wherein the power density of the large number of welding pulses is of the same magnitude.

13. The method according to claim 11, wherein the power density of the large number of welding pulses is of different magnitude.

14. The method according to claim 1, wherein the laser beam has a beam diameter or a beam width that lies in the range between 40 m and 4 mm.

15. The method according to claim 14, wherein the beam diameter or the beam width of the laser beam is in each case the same in the case of the large number of welding pulses.

16. The method according to claim 14, wherein a laser beam is used that has a circular beam cross section.

17. The method according to claim 14, wherein the beam diameter or the beam width of the laser beam differs in the case of individual welding pulses of the large number of welding pulses.

18. The method according to claim 1, wherein the welding is performed with a repetition rate in a range between 200 Hz and 10 kHz.

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

20. The method according to claim 1, wherein plastics components made of a thermoplastic material are used as the first and second components.

21. The method according to claim 1, wherein at least one of the first and second components is a component that is partially or completely coated with a coating.

22. The method according to claim 21, wherein a component with a coating having a melting or evaporation temperature that is lower than the melting or evaporation temperature of the component material onto which the coating is applied is used.

23. The method according to claim 1, wherein a steel sheet component or an aluminum component or a component made of an aluminum alloy is used as at least one of the first and second components.

24. The method according to claim 1, wherein a zinc-plated component is used as at least one of the first and second components.

25. The method according to claim 1, wherein the first component is a cast component, and the second component is a component made of a different material, which is welded onto the cast component or is welded into the cast component.

26. The method according to claim 1, wherein the first component is a sphere made of steel, aluminum or a thermoplastic material, which is welded onto the second component.

27. The method according to claim 26, wherein in a placement region of the sphere on the second component, a weld seam extending in the placement region around the sphere is produced by the large number of welding areas.

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

29. The method according to claim 1, wherein at least one of the first and second components is a chassis component of a vehicle to be produced.

30. The method according to claim 1, wherein a power density of a welding pulse is changed during the welding pulse by way of: (i) changing the laser power with constant beam cross section, (ii) changing the beam cross section with constant laser power, or (iii) changing the laser power and the beam cross section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 shows the welding of two sheet metal components in a schematic representation.

[0037] FIG. 2 shows the sequential production of a weld seam from a large number of welding areas.

[0038] FIG. 3 is a diagram describing the laser power over time.

DETAILED DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 shows two metal sheets 1, 2 which are located one next to the other, wherein the thickness of the sheet 1 is s.sub.1 and the thickness of the sheet 2 is s.sub.2. s.sub.1 and s.sub.2 may for example lie in the range between 0.3 mm and 3 mm. In the peripheral region of the sheet 1, the two sheets 1, 2 have already been welded together here using a fillet weld 3. Prior welding together by using the fillet weld 3 is not absolutely necessary, however.

[0040] In the first sheet 1, a slit 1a is provided that runs through the first component 1. The slit 1a can have a width of a few tenths of a millimeter up to a few millimeters.

[0041] Using a laser welding device 4 that produces a laser beam 5, the two metal sheets 1, 2 are welded together additionally using a (butt) weld 6. The laser beam 5 is directed here such that it penetrates the slit 1a and melts material of the two components 1, 2 and welds them together.

[0042] The laser welding device 4 is here operated in pulsed fashion, that is to say by periodically switching the laser beam 5 on and off, a large number of welding pulses are produced successively that are interrupted in each case by weld-free rest intervals.

[0043] FIG. 2 shows two metal sheets 1, 2 located one on top of the other, which are connected together using a weld seam 10 which is currently being produced. The slit 1a provided in the first component 1 can be clearly seen.

[0044] The weld seam 10 is here sequentially built up by way of individual welding areas that overlap one another in a scale-like manner. In order to locally delimit the introduction of heat produced by the laser beam 5 into the metal sheets 1, 2 as much as possible, the individual welding arms are possibly not all produced one next to the other or in succession. For example, the welding areas can be produced successively in the order given by the reference signs 11-22. After the welding area 11 has been produced, it can cool. The welding area 12 that is produced after the welding area 11 has a sufficiently large distance from the welding area 11 such that the heat introduction into the welding area 12 substantially does not influence the cooling of the welding area 11, etc.

[0045] FIG. 3 describes the pulsed welding according to the invention using a diagram, in which the laser power P.sub.Laser is plotted over time t. A first welding pulse extends from the time point 0 up to the time point t.sub.1. This is followed by a rest interval of the length [t.sub.1, t.sub.2].

[0046] This is followed by a further welding pulse of the length [t.sub.2, t.sub.3], which in turn is followed by a rest interval of the length [t.sub.3, t.sub.4]. The period duration, that is to say the length of a welding pulse and a subsequent rest interval, is thus T=[t.sub.2, t.sub.4].

[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.