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 a method for controlling a laser body shell welding system, in which a scanning head is attached to a machine arm or is operated as an external tool of the machine arm, the scanning head having at least one scanning mirror for positioning a laser beam on a workpiece to be welded, and the operation of the laser welding system including time-critical functions for controlling the time-critical functions, an embedded control system or a memory-programmable control system is used.

Abstract: During welding with high output power, the gaps between the pieces being joined may not exceed a maximal gap width. A process for laser beam welding is provided, which on the one hand ensures maintaining (not exceeding) a maximal gap width between the sheets and on the other hand makes possible a maximal utilization of the achievable welding speed. The sheets, prior to welding, are first spot welded, wherein they are clamped only during this spot welding in order to ensure the maintenance of a maximum gap width.

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: In coated sheets the coating material often has a significantly lower melting point than the material of the sheet. Accordingly, when welding together this type of sheets, there may occur explosion-like evaporation of coating material, which significantly compromises the quality of the joint. For improving the joining quality it has already been proposed to provide a narrow gap between the sheets, through which the vaporized coating material can escape. The present invention provides a process and a device for simple and reliable checking the spacing of the sheets.

Abstract: During welding with high output power, the gaps between the pieces being joined may not exceed a maximal gap width. It is the task of the present invention to provide a process for laser beam welding, which on the one hand ensures maintaining (not exceeding) a maximal gap width between the sheets and on the other hand makes possible a maximal utilization of the achievable welding speed. This task is solved in that the sheets, prior to welding, are first spot welded, wherein they are clamped only during this spot welding in order to ensure the maintenance of a maximum gap width.

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.