Abstract: A method for welding two metal parts from aluminum alloys with the steps: melting of the metal parts to be joined in a weld region through an energy input by means of a laser beam with the formation of a weld seam, smoothing the surface of the weld seam through a further energy input with partial melting of the weld seam in the region of the surface, wherein the further energy input is a defocused laser beam, of which the focal point is positioned in the beam direction in front of or behind the surface of the weld seam, wherein the defocused laser beam and the surface normal of a surface of the two metal parts to which the laser beam is applied, incorporate an angle of greater than or equal to 5 degrees, and a connecting arrangement welded with this method.

Abstract: A method for welding two metal parts from aluminium alloys with the steps: melting of the metal parts to be joined in a weld region through an energy input by means of a laser beam with the formation of a weld seam, smoothing the surface of the weld seam through a further energy input with partial melting of the weld seam in the region of the surface, wherein the further energy input is a defocused laser beam, of which the focal point is positioned in the beam direction in front of or behind the surface of the weld seam, wherein the defocused laser beam and the surface normal of a surface of the two metal parts to which the laser beam is applied, incorporate an angle of greater than or equal to 5 degrees, and a connecting arrangement welded with this method.

Abstract: With many coated sheets, in particular zinc-coated sheets as used in the automobile industry, the coating material has a much lower boiling point than the material of the sheet. On welding said sheets together the above leads to explosive evaporation of coating material which seriously affects the quality of the connection. In order to improve the quality of the connection it has already been disclosed that narrow gaps between the sheets can be produced by means of spacers, through which the coating material can escape. The spacers can be produced for example, by means of laser bombardment of the sheets. A disadvantage is the relatively long time necessary for machining, which causes large costs in particular for serial production. The aim of the invention is to reduce the time necessary for machining the sheets whilst at least maintaining, preferably improving the quality of the machining.

Abstract: In many cases, the coating material of coated sheet metal has a significantly lower boiling point than the sheet metal material. Thus, an explosive vaporization of coating material can occur when sheet metal of this type is joined by welding, negatively affecting the quality of the connection. To improve the connection quality, narrow gaps are created by means of spacers, allowing the vaporized coating material to escape through said gaps. The spacers are created e.g. by the laser radiation of the sheet metal. The aim of the invention is to reduce the variations in distance between the sheet metal sheets by the appropriate shaping of the spacers. This is achieved by a method, in which the laser beam executes a movement comprising transverse and longitudinal components through and/or around the center of its processing surface. This creates a topographical modification with a spherical form, i.e. with an apex radius that is greater than the height of said topographical modification.

Abstract: In many cases, the coating material of coated sheet metal has a significantly lower boiling point than the sheet metal material. Thus, an explosive vaporization of coating material can occur when sheet metal of this type is joined by welding, negatively affecting the quality of the connection. To improve the connection quality, narrow gaps are created by means of spacers, allowing the vaporized coating material to escape through said gaps. The spacers are created e.g. by the laser radiation of the sheet metal. The aim of the invention is to reduce the variations in distance between the sheet metal sheets by the appropriate shaping of the spacers. This is achieved by a method, in which the laser beam executes a movement comprising transverse and longitudinal components through and/or around the center of its processing surface. This creates a topographical modification with a spherical form, i.e. with an apex radius that is greater than the height of said topographical modification.

Abstract: The application of anti-corrosion base coating by cataphoretic painting (KTL) is well known in manufacturing automobile body parts. However, the cataphoretic paint can penetrate only incompletely or possibly not at all into the gap in the contact areas of the components joined to each other. This type of gap is conventionally sealed following cataphoretic painting, in order to ensure corrosion protection for the entire assembly. The present invention makes it possible to dispense with the sealing in the production of an assembly of joined conductive components and nevertheless to ensure a sufficient corrosion protection. By introducing topographic changes in the components projecting from their surface in the known contact areas and then joining these components, they are spaced apart by the projecting topographic changes in such a manner that during cataphoretic painting the paint wets the entire surface of the assembly.

Abstract: The application of anti-corrosion base coating by cataphoretic painting (KTL) is well known in manufacturing automobile body parts. However the cataphoretic paint can penetrate only incompletely or possibly not at all into the gap in the contact areas of the components joined to each other. This type of gap is conventionally scaled following cataphoretic painting, in order to ensure corrosion protection for the entire assembly. The present invention makes it possible to dispense with the sealing in the production of an assembly of joined conductive components and nevertheless to ensure a sufficient corrosion protection. By introducing topographic changes in the components projecting from their surface in the known contact areas and then joining these components, they are spaced apart by the projecting topographic changes in such a manner that during cataphoretic painting the paint wets the entire surface of the assembly.

Abstract: During laser beam welding a so-called end crater forms at the end of the weld seam. The end crater is formed by the volume shrinkage of the solidifying melt after the laser beam reaches the seam end and is switched off or repositioned. The end crater acts as a geometric notch or groove and deteriorates the mechanical properties of the weld seam, so that holes or tears in the area of the end crater can occur. The task of the present invention as comprised therein, of providing a laser weld seam with reduced end crater and a process for production thereof. The task is solved thereby, that the seam end is provided at a location, which exhibits a excessive material relative to the surrounding surface or thereby, that the seam towards the seam end exhibits a counter-running direction change of its preferred direction, which is designed in such a manner, that as a consequence of the interaction between cooling forward and counter-running seam a backfill of the melt towards the seam end occurs.

Abstract: During laser beam welding a so-called end crater forms at the end of the weld seam. The end crater is formed by the volume shrinkage of the solidifying melt after the laser beam reaches the seam end and is switched off or repositioned. The end crater acts as a geometric notch and decreases the mechanical characteristics, in particular the operational stability, of the weld seam so that holes or tears in the area of the end crater can occur. The task of the present invention is thus comprised of providing a process for reducing end crater formation. The task is solved in that towards the seam end the focus of the laser beam is distanced from the surface to be welded and/or a transverse movement of the beam occurs.

Abstract: With many coated plates, in particular zinc (galvanized) and organic coated sheet metal as are employed in the automobile industry, the coating material has a significantly lower boiling point than the melting point of the sheet metal material. Therefore in the case of laser welding of this type of sheet metal with zero gap in the overlap abutment area to a explosion like vaporization of coating material, which take along or entrain molten sheet metal material and strongly damage the quality of the joint. For improving the connection it has already been proposed that no gap be provided between the sheets, but rather these are positioned directly over each other and then first by means of first laser beam to warm until vaporization of the coating and subsequently to weld the uncoated sheets by means of a second laser beam. The disadvantage therein is above all the elaborate apparatus set up or complexity for the two required optical systems.

Abstract: With many coated sheets, in particular zinc-coated sheets as used in the automobile industry, the coating material has a much lower boiling point than the material of the sheet. On welding said sheets together the above leads to explosive evaporation of coating material which seriously affects the quality of the connection. In order to improve the quality of the connection it has already been disclosed that narrow gaps between the sheets can be produced by means of spacers, through which the coating material can escape. The spacers can be produced for example, by means of laser bombardment of the sheets. A disadvantage is the relatively long time necessary for machining, which causes large costs in particular for serial production. The aim of the invention is to reduce the time necessary for machining the sheets whilst at least maintaining, preferably improving the quality of the machining.

Abstract: The invention concerns a process for pretreatment of a workpiece to be processed with a laser beam, as well as a device for carrying out the process. It is the task of the invention to develop a process and a device, which with small expenditure of material and expense, and with few process steps, makes possible an improved weld seam formation for joining workpieces. The invention is comprised therein, that for the pretreatment of a workpiece to be treated with a laser beam, in which on at least one surface of the workpiece with application of a thermal effect of at least one laser beam emitted by a laser source, rises such as knurls are formed, for the positionally correct and undistorted formation of the rises the time and spatial sequence of a relative movement between workpiece and laser beam and the output over time of the laser source are coordinated to each other via a control computer.

Abstract: For increasing the load bearing capacity of spot-like weld seams for producing a durable joint between at least two components, it is known to lengthen this linearly, that is, to weld with a longitudinal orientation extending more than 30 mm. Such linear weld seams, however, do not endure high loads. The task of the present invention comprises providing linear weld seams with increased load bearing capacity and a process for their production. This task is solved by a process specifically for increasing the load bearing capacity of a linear weld seam for producing a durable joint between at least two components, wherein the location with the highest probability of a weld seam break is determined and then, at this location, a discontinuity is introduced into the weld seam, in such a manner that the tangent of the connecting line exhibits an angle of 15° or more.

Abstract: In the manufacture of automobile body parts the application of anti-corrosion base coating by means of cataphoretic painting (KTL) is well known. However a gap occurs in particular in the contact areas of the components joined to each other, into which the cataphoretic paint can penetrate only incompletely or possibly not at all. Thus, this type of gap is conventionally sealed following cataphoretic painting, in order to ensure corrosion protection for the entire assembly. The present invention makes it possible to dispense with the sealing in the production of an assembly of joined conductive components and nevertheless to ensure a sufficient corrosion protection. This is achieved by introducing topographic changes in the components projecting from their surface in the known contact areas and then joining these components such that they are spaced apart by the projecting topographic changes in such a manner that during cataphoretic painting the paint wets the entire surface of the assembly.

Abstract: During welding of higher stiffness steels there is significant tendency towards hardening in the area of the weld seam, which introduces a loss in ductility and thus strongly reduces the durability and quality of the construction components.

Abstract: During laser beam welding a so-called end crater forms at the end of the weld seam. The end crater is formed by the volume shrinkage of the solidifying melt after the laser beam reaches the seam end and is switched off or repositioned. The end crater acts as a geometric notch and decreases the mechanical characteristics, in particular the operational stability, of the weld seam so that holes or tears in the area of the end crater can occur. The task of the present invention is thus comprised of providing a process for reducing end crater formation. The task is solved in that towards the seam end the focus of the laser beam is distanced from the surface to be welded and/or a transverse movement of the beam occurs.