A general framework for automated CAD-guided optimal tool planning in surface manufacturing.

摘要

This dissertation develops a general framework for automated CAD-guided optimal tool planning in surface manufacturing. Surface manufacturing is a process to add material to or remove material from the surface of parts. Spray painting, spray forming, indirect rapid tooling, spray coating and polishing are typical applications of surface manufacturing. Industrial robots are used to implement these processes. Tool planning of these processes, which builds a bridge between product design and manufacturing, is crucial for the product quality. Typical teaching methods are not feasible any more because products are subject to a shorter product life, frequent design changes, small lot sizes, small in-process inventory restrictions and quality issues. An automated tool planning process (ATPP) is desirable for the tool planning of industrial robots.; In surface manufacturing, automated tool planning develops a tool trajectory for a free-form surface based on a tool model such that the given constraints are satisfied. According to the material distribution constraints, the processes in surface manufacturing can be categorized into two groups: material uniformity and coverage. Based on a tool model and material distribution constraints, a free-form surface is divided into patches. The parameters (the spray width and tool velocity) used for automated tool planning are determined by optimizing the material distribution on a plane. Since different material deposition patterns are used in automated tool planning, comparison between the raster and spiral material deposition patterns are performed. The raster material deposition pattern is better than the spiral one for continuous material deposition. After the spray width is determined, an improved bounding box method is developed to generate a path for a patch using the raster pattern. The tool orientation is determined using the local geometry of a free-form surface. Since the material deposited on the free-form surface is less than the desired material thickness, a suboptimal velocity algorithm is developed to optimize the material thickness deviation. For a free-form surface with multiple patches, an integration algorithm is developed to integrate the trajectories of the patches. To verify if a trajectory satisfies the given constraints, a verification model is developed. The implementation and simulation results show that the developed automated tool planning algorithm can be applied to generate trajectories for different processes in surface manufacturing such that the given constraints are satisfied. (Abstract shortened by UMI.)