Study On The Approaches To Automated Parts Manufacturability Evaluation For Concurrent Engineering

It is the final objective pursued by manufacturing industry and research community that to improve product quality and reduce lead-time and cost of product, and is the mainly factor of the enterprise in global marketplace to achieve the success and the development. In order to achieve such objectives, increasing research attention is being given to concurrent engineering and the integration of engineering design and manufacturing during the last decades. In this thesis, a systematic approach to computer-aided manufacturability evaluation of machined parts has been developed. This approach combines the incremental evaluation used during the detailed design process and the entireness evaluation used after the design. The final goal of this research present a decision-making support tool, which can be used during design stages to improve the products quality from the manufacturing point view.Evaluating the manufacturability of a proposed design involves determining whether or not it is manufacturable with a given set of manufacture resource during its whole manufacturing process. If a part is manufacturable, then finding the associated manufacturing efficiency, if a part is not manufacturableor, then pointing out the problems. The manufacturability includes many aspects, such as geometry structure of parts, the rationality of the tolerance specification, fixturability and the assemblability etc. In the research, the main research topics are focused on the following aspects: the study on the incremental evaluation approach during the detailed design process, the study on the entireness evaluation after the design has completed and the study on the fixturability evaluation of the machined parts for modular fixture.In this research, design is represented as a B_rep solid model. The tolerance and surface roughness information is represented as attributes of various faces of the solid. The manufacturing feature model of part design is established by automatic manufacturing feature recognition method. Manufacturing features are used to model the available machining operations of the part design. The manufacturing feature of the part design is taken as a basic element to carry outvarious evaluation tasks in all evaluation objectives.The proposed incremental evaluation approach can effectively performs manufacturability evaluation on any intermediate product model during the design process. The function of the incremental evaluation is to find out the feature with manufacturability problem by determining the feasibility of the operations of various type of manufacturing feature. It makes the design model evolvement from one state to another state by performing the manufacturability evaluation alternatively. Moreover it is incremental, i.e. it conducts the evaluation on current product model based on the evaluation results on the previous model. In order to maintain the coherence and the speed of the evaluation process, the status change of the feature in design progress is investigated, and as a result, the feature set that must be evaluated at current evaluation is established.The proposed entireness evaluation approach can effectively performs manufacturability evaluation on completed product model, which is based on the simplified process planning. In order to obtain the simplified process plan automatically and efficiently, a novel approach to automatic setup planning and operation sequencing of a part is proposed, meanwhile, an approach to establishment of feature sequence constraints based on the intersecting boundary is proposed. In this approach, according to geometric precedence and tolerance precedence among features, the reasonable machining operations of features with multiple machining operations are determined, and the conflicts between geometric precedence and tolerance precedence of features are disposed. The approach can generate the process plan by which the part can be machined to satisfy the required tolerances, and the approach also has high efficiency. The entireness manufacturabilit...