| Sheet metal is a large branch of mechanical products. In past designing and manufacture to sheet metal, from calculating and unfolding to nesting, had been finished by handwork. Though manual nesting adopted in production results in less trim loss, it is inefficient and manpower exhausting. Along with broad applications of the CAD technology, the paper makes use of it to designing CAD module, using the method of software engineering and contraposing frequent sheet metal in practice.Based on the analysis of sheet metal technology, the paper summarizes the advantages and disadvantages of diagrammatic method. The problems of automatic unfold-calculation and unfold-drawing are analyzed by modern information technology on the basis of calculation method. According to practical production, all kinds of sheet metal are classified. We select the most representative penetration component and establish its mathematical modeling, using parameter method. The solving method is also provided.Based on the review of research and application status of nesting problem, the paper discusses the related theory and technology. Through comparing and analyzing the needs of CAD module, including efficiency and practicability, paper focuses on rectangular nesting. In this paper simulated annealing algoritlim and genetic algorithm arc combined and integrated, and they are applied in LFB[30] algorithm successfully. when their optimizing and searching abilities in nesting are applied, we can get a better layout than LFB algorithm. Meanwhile, we discuss several iniluential parameters in the two algorithms and nesting algorithm of irregular parts, providing useful algorithm for CAD packing system.The CAD module's software structure is constructed reasonably, and OpenGL graphics standard is integrated in it, realizing dynamic display of sheet metal.
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