Data processing: structural design – modeling – simulation – and em – Modeling by mathematical expression
Reexamination Certificate
1998-07-10
2001-07-03
Teska, Kevin (Department: 2123)
Data processing: structural design, modeling, simulation, and em
Modeling by mathematical expression
C703S007000, C703S022000, C700S283000, C901S043000
Reexamination Certificate
active
06256597
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to spray coating and more specifically to a three dimensional spray coating method and simulation.
A significant problem associated with spray coating processes has been the difficulty in achieving a specified deposit thickness on a substrate surface. The following factors contribute to the difficulties in achieving the specified deposit thickness distribution: the three-dimensional part geometry; the changing characteristics of the spray gun due in part to changes in the process conditions and in part to gun aging with time; and the non-optimized robot motion spray path associated with such coating processes. At present there is no prediction tool available for designing the spray pattern or the gun motion path to accommodate a new three-dimensional part geometry.
As a particular example of a coating process, a plasma spray process involves extremely high temperatures with metal or ceramic powder being directed at a substrate surface. A vacuum plasma spray (VPS) process is used, for example, on turbine buckets to produce coatings that serve as oxidation barriers. The relative motion paths of the turbine bucket and the robot that controls the plasma spray gun are determined based on experience with previously made buckets of similar styles. Excessive experiments to verify the coating thickness distribution, however, cost both time and money.
Currently, the coating thickness distribution on turbine buckets is evaluated by a destructive technique, whereby a certain number of buckets are cut into sections, mounted, polished, and examined under a microscope to determine if their respective thickness distributions are within specified limits. If the thickness distributions are not acceptable, then the robot program or the process conditions are adjusted and the procedure is repeated. This trial-and-error approach is often repeated many times during the process development cycle, especially for new products. In new products, difficulties arise in determining optimum process conditions due to a lack of understanding concerning the interactions of the process variables, the part geometry, and the final coating quality.
Accordingly, there is a need in the art for improved evaluation and control in three dimensional coating processes.
SUMMARY OF THE INVENTION
A spray coating simulation for a robotic spray gun assembly imports a discretized model of an object geometry. Next, the simulator imports a numerically characterized spray pattern file and a robot motion file having a plurality of motion positions, dwell times and orientations defining a motion path of the spray gun. The individual motion positions within the motion file are read and a determination is made as to which portions of the object geometry are visible at each motion position. Next, a coating thickness at each visible portion of the object geometry is computed, based on the specified spray pattern data, the dwell time and the orientation of the robot motion path, for each motion position. Finally, the total coating thickness over the object geometry is calculated.
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E. Goodman et al., A Method for Accurate Simulation of Robotic Spray Application Using Empirical Parameterization, Proceedings of the 1991 IEEE international Conference on Robotics and Automation, Apr. 1991, pp. 1357-1368.*
S.-H. Suh et al., Development of an Automatic Trajectory Planning System (ATPS) for Spray Painting Robots, Proceedings of the 1991 IEEE International Conference on Robotics and Automation, Apr. 1991, pp. 1948-1955.*
W. Mallener et al., Plasma-Sprayed Coatings for Plasma-Facing Components, Fusion Engineering, 17th IEEE/NPSS Symposium, vol. 2, 1998, pp. 884-887, Jul. 1998.*
K. Adamiak et al., Simulation of Particle Trajectories in Tribo-Powder Coating, Conference Record of the 1995 IEEE Industry Applications Conference, 30th IAS Annual Meeting, IAS ′95, vol. 2, pp. 1273-1279, Apr. 1991.
Ostrowski Michael Charles
Perry Erin Marie
Swede Sharon Trombly
Wang Hsin-Pang
Worsey Andrew James
Frejd Russell W.
General Electric Company
Ingraham Donald S.
Patnode Patrick K.
Teska Kevin
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