Patent DE-102012010475-A1 (DE)
Title: Coating a substrate using a laser, comprises melting the substrate using a laser beam produced along a gauge to be melted, providing powder to substrate, and partially providing powder into melted substrate for producing coating
Inventor: KIRSTE THOMAS DIPL ING
IPC: B23K26/34
Filed: 2012-05-26
Abstract: The method comprises melting a substrate using a laser beam produced by a laser along a gauge to be melted, providing a powder to the substrate, partially providing the powder into the melted substrate for producing a coating, and partially preheating the substrate in a process direction at which the powder impinges on the substrate. The substrate is moved into the process direction relative to the laser and to the powder along the gauge. The step of preheating the substrate in the process direction is carried out by the laser beam. The method comprises melting a substrate using a laser beam produced by a laser along a gauge to be melted, providing a powder to the substrate, partially providing the powder into the melted substrate for producing a coating, and partially preheating the substrate in a process direction at which the powder impinges on the substrate. The substrate is moved into the process direction relative to the laser and to the powder along the gauge. The step of preheating the substrate in the process direction is carried out by the laser beam, and takes place before an initial coating. An efficiency of the preheating step is adjusted to generate a molten bath on the substrate without the powder and to produce the coating with a small proportion of powder mass flow (dm) on the substrate. The method further comprises varying the powder mass flow and a laser power at the initial coating and/or a final coating similar to a given function, where a maximum local displacement (S) is determined between the function of the laser power and the function of powder mass flow with respect to a gauge route (LS1) in dependence of a substrate material and a powder material. The laser power (PL) is determined for preheating the substrate according to powder mass flow portion. The maximum displacement takes place by: determining a maximum distance between the function of powder mass flow and the function of the laser power, where the maximum distance corresponds to the maximal displacement; measuring a time interval for the displacement of the powder from a powder conveyer system to the melted substrate, where a standard deviation of the time interval is determined and then converted in dependence of a process speed into the distance and the distance corresponds to the maximum displacement; adjusting a target powder function at the powder conveyer system, where an actual function of the powder mass flow is measured shortly at the place of the melted substrate or in direction of the powder mass flow before the target powder function and a determined maximum target actual deviation corresponds to the maximum displacement; and/or determining a molten bath size and their maximum deviation of a diameter of the laser beam in a direction opposite to the process direction, where the maximum deviation corresponds to the maximal displacement.