Direct Manipulation of Planar Geometry

Most of the presently available CAD systems are oriented toward generating the geometry of a whole product. But if we consider the problem of manufacturing, we sometimes wish to have such a CAD system that permits us to decompose the geometry of a final product so that we may make adequate decisions how to assemble pieces into the final shape. For example, if we consider welding, the decision where to weld does not necessarily reflect the welding engineers’ knowledge and experience. Rather, it is determined from other considerations such as design, mechanical machining, etc. But if we could take some portion of welding engineer’s knowledge and experience at the earlier stages of design, designers might change this design to make welding much easier to perform or to permit larger degree of allowances for mechanical machining, since large amount of heat will be inputted there later on by welding. Thus, a CAD system that permits such a decomposition of geometry is desired in order to integrate design and manufacturing and to achieve true concurrent engineering. In this work, a preliminary system has been developed which allows direct manipulation of only planer geomtry. But to consider that we do not have adequate systems which allow such decomposition for planer geometries and we still use CAD systems to work on a final geometry and different systems to determine the optimum plate cutting out of a large plate and further some other different systems to verify that the section to be welded will have enough strength, such a system would provide a first step toward realizing real concurrent engineering. Because there are many cases in welding where only planer geometries are used and if a final geometry can be decomposed into planer geometries, we would know that where it would be better to weld or how we can put them together.