Research And Development On The CAD System For Unfold Of Typical Sheet Metal

There are many productions made of metal plate in daily life and industry departments, proper unfolding is very important working procedure. For the development of intersecting curve, the traditional method is the geometry drawing scheme, which is not only complex but also time consuming, in addition, the precision of the developed curve is low. The CAD system for unfolding of typical sheet metal can be developed automatically,exactly,rapidly by the usage of electronic computer technology .Base on the theory of analytical spatial geometry and the classification of sheet metal products, the typical sheet metal's unfolding methods are analyzed and the mathematical models are built. The mathematical models of cutting groove for thicker sheet metal are deduced too.This paper discusses how the welding groove and the plate thickness affect the sheet metal manufacture processes, and how to design with reasonable methods. The policy of welding groove angle is adopted in the system, leading to an improved welding quality and efficiency, and thus saving the welding materials.We can convert the unfolded curve into the DXF format document to drive the numerical controlled cutting device directly as to cutting out the material more quickly and precision.The code of this system is programmed on the AutoCAD2005 platform by using of VisuaLISP language. By this software, the coordinates of discrete points on the developed curve are calculated; further, these points are connected continuously so as to obtain a developed intersecting curve, which can satisfy the required precision.In this system, different kind of sheet metal product corresponds to different menu item and tool button. The interface between computer and operator is developed with DCL, and the meaning of every inputed parameters is illustracted with sketch map. In this way, data can be input easily and visually.The successful application of this system has demonstrated that the new system has increased the accuracy and reliability of sheet metal components cutting process and the producing efficiency has been improved greatly.