Automated Synthesis of Sheet Metal Parts by Optimizing a Fabrication Based Graph Topology

The goal of this research project is to investigate the automatic construction of sheet metal components. While automated synthesis may alleviate this time-consuming process, it is difficult to envision how optimization algorithms, which require a fixed set of variables in order to function, could be used to represent the wealth of modifications that can be made to a part. The technique presented in this paper represents candidate solutions as a graph of nodes and arcs where each node is a rectangular patch of sheet metal, and modifications are progressively made to the sheet to maintain the parts manufacturability. Currently, seventeen modification rules have been developed for four basic sheet metal operations: slitting, notching, shearing, and bending. Given the complex design process of sheet metal components, evaluating candidates is a mixture of several different objectives. These include: 1) minimizing spatial requirements, 2) minimizing fabrication time, 3) minimizing fabrication energy, 4) minimizing part volume, 5) minimizing part deflection under applied loads, and 6) minimizing stress. Currently, only the first four have been implemented, but preliminary results show that solutions can be found that are similar to current solutions created by hand. HE increasing popularity of sheet metal in modern artifacts is due to the fact that it is inexpensive both as a raw material and as to form into components. The automobile industry is the largest single user of sheet metal where sheet metal components comprise approximately 33 % of the weight of an automobile. So the improvements made in the efficiency of metal forming operations and design could have a large impact on the US economy. In comparison to forging or machining components, sheet metal can produce lightweight and inexpensive design solutions. The main shortcomings of sheet metal design are that resulting components have a limited rigidity and the feasibility of the parts is constrained by the inherent two-dimensionality of the initial sheet. Smart solutions to the design of sheet metal components can reduce both manufacturing time and energy, and result in high quality components. Good design is also based on how the design engineers manage the trade-offs between the manufacturing process and the design specifications. The concurrent efforts between the manufacturing engineers and the design engineers are complicated for even the simplest sheet metal components, resulting in an iterative and time-consuming design process. Due to the extensive use of the sheet metal parts, designing sheet metal component is perhaps one of the most challenging issues for the design and manufacturing engineers. To ease this process, a method has been developed to encapsulate the spatial constraints of sheet metal parts at the same time avoiding certain locations that would impinge upon other parts. The automated synthesis of sheet metal parts is a new computational approach that represents candidate solutions as a graph of nodes and arcs where each node is a rectangular patch of sheet metal, and modifications are progressively made to the sheet in order to maintain the part’s manufacturability. A search process is established that can produce the designs that are optimal in both design and manufacturing specifications.