Papers by Keyword: Operation Sequencing

Abstract: The determination of process route is a complex process and one of key techniques of computer-aided process planning. workpiece surfaces are classified. The machining element is determined and ranked according to rules of technological design. Finally, all the machining elements are reorganized and ranked with the comprehensive consideration of freedom constraints of workpiecesand technological equipment. The operation sequence is generated automatically.

Abstract: Operation sequencing is one of the most important tasks in process planning. The sequencing procedures associate manufacturing features from 3D CAD models and machining methods together to satisfy certain manufacturing process constraints. In order to simplify process constraint aggregations, two types of constraint matrixes, feature constraint matrix and the operation constraint matrix, are proposed in this paper, which take into account of the compulsive constraints, such as geometric topology constraints, manufacturing process knowledge criteria, custom compulsive constraints and so forth. Accordingly, an iterative genetic algorithm is proposed, which is naturally used in the manufacturing feature level and operation level. In the manufacturing feature level, feasible feature sequences are generated based on the analysis of feature constraint matrix. In the operation level, the information that is contained in the machining operation such as machine tools, set-ups and cutting tools is considered to optimize the operation sequences based on the results acquired in the feature level. Compared with the traditional simple genetic algorithm, the iterative genetic algorithm is proved to be superior in shortening the operation sequencing time.

Abstract: Two graphs are introduced to describe the precedence and cluster constraints among stamping operations, i.e., operation precedence graph and operation adjacency graph. A graph colouring algorithm clusters the operations based on both the precedence and adjacency graphs to form joint operations. A joint operation matrix is then generated. A matrix based algorithm is presented to iteratively order the joint operations to generate the final sequence according to the index of priority for each operation. The algorithm is implemented in C++ and is fully integrated with SolidWorks CAD system. A case study is presented to illustrate the algorithm.

Abstract: A Progressive die is used to transform flat strips of sheet metal into a formed part. This transformation is performed progressively by a series of stations that cut and bend the material into a desired shape. The progressive dies reduce the time and cost of producing complex sheet metal components. The design and manufacture of these dies are difficult. CAD/CAM systems have been proved very useful tools for this task. In this paper, a new system for design of the piercing and bending progressive die is described. In this system, piercing and bending operation are separated and the sequencing of each type is done individually. In this system first sequence of the piercing stations are determined then bending operations are sequenced based on a classification and fuzzy algorithm. Also, neural network systems are used to determine final angle of bends and die parameters. The capability of the system is shown using a sheet metal component.