<title>Method of equivalent element in parametric CAD</title>

Abstract

FENG XiangzhongDepartment of Mechanical EngineeringDalian University of TechnologyDalian city, Liaoning, China, 116024No. 2 DepartmentHeilongjiang Institute of MiningJixi city, Heilongjiang, China, 158100ABSTRACTThis paper introduces a new method to represent entities and deal with constraints in parametric CAD system. Themethod is based on equivalent entity, named as method of equivalent element. Using the method, many kinds of complexgeometrical elements and constraints could be treated as simple equivalent line(s), so the whole drawing would be translatedinto its equivalent drawing that is composed of only lines. It can make the parametric work become very regular andefficient.Keywords: parametric CAD, degree of freedom, constraint, equivalent element1. INTRODUCTIONIn engineering practice, majority of the new designs are so called adapting designs and series designs, which means theconstructions of the new designs are similar to a prototype product design. Only some dimensional parameters of newdesigns are different and probably part of the construction has to be made little modification.Engineering drawings are used for defining and representing design products completely and are very importantdocuments in production. In conventional CAD systems, database is geometry database that stores a design drawing as a