DE10113471B4 - Method for hybrid welding by means of a laser double focus - Google Patents

Abstract

method for welding of materials by means of a single laser beam and a coupled one welder as a laser hybrid welding process, at the at least two laser focussing points (12, 13) generates the laser beam and in the welding point (20) or in the area the resulting melt are directed around the welding point (20), characterized in that the respective laser parameters, in particular the distances the focusing points (12, 13) relative to each other and the welding point and the intensities the focusing points (12, 13), based on the measurement of individual parameters of the welding process, in particular the welding speed and goodness, ongoing and independent be varied from each other.

Description

The The invention relates to a method and a device for welding or Soldering from Materials by means of a single laser beam and a coupled welder or a coupled soldering device.

The coupling of different welding processes, in particular by means of a conventional welding process and a laser beam is called laser hybrid welding process. These methods are mainly used in manufacturing technology to combine the advantages of the respective methods and to apply to specific problems. In an arc welding process, the welding heat is transmitted to the welding surface by a high electric current. However, the focal spot of the arc does not achieve a large welding depth into the material. Also variations of certain welding parameters, such as the time-dependent change of the welding current ( DE 198 08 383 A1 ), this welding characteristic can not change significantly.

The use of a high-energy laser beam for the treatment, in particular welding, of surfaces is state of the art (eg DE 197 51 195 C1 ). The heat-affected zone of the high-energy laser beam, in contrast, with a conventional arc welding arrangement is substantially smaller than the area of the focal spot. However, the welding depths are significantly lower compared to the conventional welding process. The combination of these two methods leads to a cup-shaped weld, with which also gap bridges between workpieces can be welded.

The EP1020249A2 describes a laser processing head, which is particularly suitable for welding by means of an additional wire or for laser cutting. Here, a laser beam is split into two separate laser beams by a convex roof edge mirror, a subsequent concave roof edge mirror and a subsequent lens system. In this case, the ratio of the intensities of the separate laser beams to each other can be adjusted in the laser processing head. The distance of the separate laser beams from each other is influenced by a change in the mirror arrangement relative to the optical axis. However, a disadvantage is that only the distance of the laser beams from each other can be adjusted, not a free continuous positioning of the separate laser beams.

In the DE 199 16 831 A1 A method for laser TIG welding of coated steel sheets is described. The combination of a Tungsten Inert Gas (TIG) welding process with a Nd: YAG solid-state laser allows welding of coated steel sheets through a higher weld quality than conventional welding processes. However, this possibility is only possible in a very narrow configuration range, in which the parameters of the welding and laser properties are precisely specified.

From the DE 198 49 117 A1 For example, a method and apparatus for coupled laser GMA welding is known. Gas shielded metal arc welding (GMAW) combined with a high-energy laser, such as a CO ₂ laser or an Nd: YAG laser, is being extended as a conventional hybrid welding process by a further welding process. An additional, coupled MSG welding process improves the welding performance of the conventional hybrid process and improves the seam quality, especially when welding gap gaps.

The Single welding process, As arc or laser beam welding process, or their combinations as a hybrid welding process have the major disadvantages that certain shortcomings the single or hybrid welding process partly or not considered become. In the melt around the welding point forms due to the high temperatures, a so-called steam capillary. Stiffens the melt too fast, so this forms enclosed steam capillary cavities and pores, which are the mechanical strength of the workpiece and the weld to a high degree adversely affect (e.g., "online process monitoring in laser beam deep welding ", G. Müller; Magazine 6/2000, page 20ff.). In conjunction with an unregulated Laser radiation can cause a larger expansion of the melt to an interruption of the electric current and thus the arc come. A continuous, in particular automated, welding becomes This prevents and reduces the quality of welding. The welding of gap spaces with only one laser focussing point leads to an asymmetric one Temperature distribution over the gap across and thus reduces the weld quality. Furthermore, the uncontrolled Energy distribution within the melt for heterogeneous workpieces too a detachment individual components, e.g. Lead carbon compounds, the the material properties of individual regions, e.g. a coating, or the entire workpiece negatively influence and can change uncontrollably.

outgoing From this prior art, it is the object of the present Invention the quality the weld to improve and when welding non-locking workpieces an asymmetric Weld to prevent.

in the For the purposes of the present invention, the term "melt" in a homogeneous workpiece or at two conclusive final workpieces the spatial Extension of the reduced strength of the workpiece surfaces around the high-energy WeldingSpot Understood. For the weld together of two workpieces over a gap The "viscous" weld metal is melted away Gap and through the welding process directly thermally influenced edges and sides of the workpieces to be welded understood.

Is solved this object is achieved by the features of claim 1. that the laser beam has at least two focus points in the spot weld or in space small distance to the welding point has. By the freely selectable change the distances the focussing points to each other or to the spot weld and / or the intensities the respective focus points may vary depending on the hybrid welding process the introduced energy into the welding spot and the environment very much be influenced exactly. This allows the temperature distribution and development of the melt in the weld or the weld seam controlled become.

With Help a constant Temperature measuring device can, dependent on from the measurement data, the adjustment parameters of the laser, e.g. Number, distances and intensities the focussing points, and the welding arrangement, such as. e.g. Wire feed, so changed be that the above disadvantages are not or only in one very small dimensions occur. The quality the welding points or the weld is thereby increased and the surrounding workpiece changed very little in its material properties by the welding process.

This Procedure thus offers the possibility the temperature distribution and the cooling process of the melt through to control the focal points of the laser radiation so that the Formation of cavities and pores due to rapidly solidified vapor capillaries strong reduces and the strength of the weld or the surrounding workpiece not being affected.

Also the laser hybrid welding of materials over a gap away, can do a lot better with this method carried out become and prevents an asymmetrical formation of the weld. By the inventive method may be a focusing point of the laser beam on the edge of the first workpiece and the second focus point on the edge to be welded of the second workpiece be placed. This leads to, at the same chosen intensities the focal points, to a homogeneous heating of the entire welding zone and improves the quality of Weld, guaranteed a complete replenishment of the entire gap gap with the melt and prevents one-sided melting of only one workpiece and thus the training an asymmetric weld.

Further advantageous measures are in the rest dependent claims described; The invention is based on embodiments and the following Figures closer described; it shows:

1 a schematic side view of the hybrid welding process according to the invention with a laser double focus;

2 a plan view of two overlapping Laserfokussierungspunkte relative to the position of the welding wire along a weld;

3 a plan view of a gap between two sheets, wherein on each sheet a Fokussie tion point is positioned and this relative to the position of the welding wire along the gap gap are displaced.

In the 1 a schematic side view of the hybrid welding process is shown with a laser double focus. In conjunction with a conventional welding torch 15 becomes the welding wire 14 directly onto the workpiece to be welded (sheet metal) 10 guided. The resulting melt 20 is irradiated directly or in the region of the resulting melt by a laser beam. The laser beam is processed by a processing optics 16 using a double-focus shaping module 19 in two laser beams with different focus points ( 12 . 13 ) divided up. An embodiment of the double-focus forming module is shown in FIG DE 199 61 918 A1 disclosed. The double-focus forming module ensures this 19 in that the intensities and / or distances of the focusing points can be selected independently of one another. The double-focus forming module 19 for example, between a collimating lens system 17 and a focusing lens system 18 a processing optics 16 be arranged when the laser beam through a - not shown - fiber optic cable to the factory piece 10 to be led. Through the processing optics 16 becomes an accurate positioning and intensity assignment of the focus points 12 . 13 in the melt 20 achieved and the thermal behavior of the melt 20 controlled influences.

In the 2 is a plan view of the processing points of the double-focused laser beam 12 . 13 and the melting point 20 the welding arrangement (as the piercing point of the welding wire 14 through the sheets to be welded 10 . 11 ) applied. Due to the free positioning and assignment of suitable intensities of the focus points 12 . 13 relative to each other and relative to the welding point, the temperature behavior in the weld and in the surrounding sheets 10 . 11 to be controlled. The focus points 12 . 13 can with the help of the double-focus module 19 even be positioned overlapping. The void and pore formation due to the formation of the vapor capillary is thus prevented.

The 3 illustrates the advantage of the hybrid welding process by means of a laser double focus. Between two sheets 10 . 11 there is a gap to be welded, being on the edge to be welded of a sheet 10 a focus point 12 is positioned and on the edge of the counter plate 11 another focus point 13 , The positions of the focus points 12 . 13 can relative to the welding wire 14 be moved along the gap gap. This prevents uneven heating of the sheets 10 . 11 and improves the quality of welding. Laser systems of conventional laser hybrid welding processes can only irradiate one sheet edge or the already welded gap and thus produce asymmetrical weld seams or weld seams with cavities and pores and thus reduced strengths.

10

sheet 1

11

sheet 2

12

first Laser beam focusing point

13

second Laser beam focusing point

14

welding wire

15

welding torch

16

processing optics

17

collimating lens

18

Focusing lens system

19

Double focus forming module

20

melt

Claims (4)

Method for welding materials by means of a single laser beam and a coupled welding device as a laser hybrid welding method, wherein at least two laser focusing points ( 12 . 13 ) generated by the laser beam and in the welding point ( 20 ) or in the region of the resulting melt around the welding point ( 20 ), characterized in that the respective laser parameters, in particular the distances of the focusing points ( 12 . 13 ) relative to each other and to the welding point and the intensities of the focusing points ( 12 . 13 ), on the basis of the measurement of individual parameters of the welding process, in particular the welding speed and quality, are continuously and independently varied. Method according to claim 1, characterized in that a double-focus forming module ( 19 ) between a collimating lens system ( 17 ) and a focusing lens system ( 18 ) the beam path of a laser beam into two focus points ( 12 . 13 ). Method according to one of the preceding claims, characterized in that, instead of a welding device, a soldering device used with internal or external solder wire guide becomes. Method according to one of the preceding claims, characterized in that by a continuous temperature measurement of the melt ( 20 ) the parameters of the laser and / or the welding arrangement ( 14 . 15 ) for an optimum welding temperature.