Process planning for rapid manufacturing of parts with complex geometries and functionally graded composition.

摘要

Most of the engineering products have a wide range of features. Features attributed to a part include the geometry of the part, the material composition of the part, and the microstructure of the part. The material composition finds special significance for a class of parts that have material composition variation based on the functionality. The geometry of the part is a result of the relative motion of the additive/subtractive end effectors and the substrate. The material composition is governed by the efficiency of the material delivery method; whereas, the microstructure is governed by the energy input and the time dependence of the energy input.;The traditional manufacturing techniques are based on a tight form-tool relationship; therefore, in order to add a feature onto the part, a feature-specific manufacturing setup is required. This setup makes the manufacturing process complex, time consuming, and expensive. Integration of a range of additive-subtractive manufacturing techniques can be applied to fabricate a varying range of parts on a single platform, and the development of the process planning for the technique is the subject of this research.;In this research, a new method for fabricating geometric features by support elimination, reordering the order of layer manufacturing to avoid collision, corresponding machine kinematics, and an expert system based implementation is suggested. Also, a path planning method that allows the path-segments to be directed along the direction of minimum composition variation. The path planning is based on the determination of different components of the desired material field. The method to control the energy input is guided by developing a correlation between the local volume and geometry of the heat sink, and the rate of heat input. Errors are introduced despite the control of input process-parameters; therefore, a state space model of the mechanism of error induction and error propagation was developed.;The suggested methods are verified by extensive experiments and are reported. The framework suggested in the research has evolved with Laser-Based Direct Metal Deposition as the additive process applied on the platform MultiFab, under development at the Research Center for Advanced Manufacturing at SMU; however, it can be applied to other additive methods such as welding or microplasma based metal deposition.;Slender structures and the missing regions of a part can have unique geometries. While slender structures are identified by the large aspect ratios, highly complex geometry can be attributed with the repair process. Fabrication of slender structures and part repair are reported as the special application of the Laser-Based Direct Metal Deposition technique.