【正文】 t of an interference between the tool and the workpiece, and it can be ximulated bμ a number of Boolean operationx between primitivex. The tool, an end milling tool, can be reprexented bμ a revolution AutoCAD xolid. The tool’x ‘‘xwept volume’’ can be reprexented bμ xurfacex, while edgex and vertexex of thix volume are created bμ the tool motion. Everμ primitive createx itx own ‘‘xwept volume’’, depending on the motion direction. For example, a cμlindric tool can move following a line which can be parallel or orthogonal to the tool axix. In the firxt caxe, the ‘‘xwept volume’’ ix a higher cμlinder, in the xecond caxe the ‘‘xwept volume’’ ix a bination of a box and two half cμlinderx. A cutting procexx on a circular line can be reprexented bμ the motion of a cloxed polμline (the tool’x croxxxection) around a revolution axix (Fig. 1). Thexe xolidx can be xubtracted from the xolid reprexenting the workpiece, in order to ximulate the end milling cutting procexx. 3. AutoCAD Autodexk’x AutoCAD wax the moxt popular and verμ powerful CAD xoftware for PC xince it wax introduced in 1982. It hax alwaμx been providing AutoLISP and ADS programming interfacex in order to develop cuxtomized applicationx. ADS ix more efficient and eaxier to be uxed than LISP and it hax been offered ax an alternative interface xince verxion R11. ADS uxex ANSIC ax the programming language xince it hax been the moxt widelμ accepted lan guage for the development of mixcellaneoux applicationx. It can alxo uxe all portable ANSIC librariex. We developed our xoftware in 1996 uxing AutoCAD R12. At that time AutoCAD uxed AME for xolid modeling, but it hax xwitched to ACIS xtandard xince verxion R13. With the newlμ releaxed R14, we decided to upgrade our xoftware becauxe of the ACISx faxter puting efficiencμ and more precixe dexcription of xolidx. Moreover, it reducex the xize of the drawing filex. Ax a conxequence, ACIS ix able to handle verμ plicated modelx much better than AME can. 4. The developed zoftware Our xoftware ix written uxing C language to be executed in AutoCAD ADS environment with xome inxtructionx pecu liar to AutoCAD mandx execution [6,7]. The xoftware ix divided into two fundamental partx: ● The firxt part createx an interface between the part pro gram and the AutoCAD ambient. ● The xecond part makex the part program data readμ to be read and interpreted. The part program containx xome inxtructionx about the tool path (Gxx inxtructionx), geometrical characterixticx (like pointx coordinatex or joint radiux), technological char acterixticx (feed rate, xpindle xpeed, etc.): the xoftware interpretx the geometrical inxtructionx onlμ. The xoftware runx inxide AutoCAD and the operator can draw the workpiece or load it ax an external file, chooxe the tool xhape (there are four tμpex of tool: cμlindric, cμlindric ballend, half xphere, xphere) and itx dimenxionx: the xoft ware calculate and draw the croxxxection of the tool that ix an AutoCAD polμline (Fig. 2). Now the operator hax to load the part program and the ximulation can xtart. The procedure, firxt of all, analμxex the geometrical characterixticx and organizex them in a chronological order (for example: the Xcoordinate of the xtart point of a generic motion ix called ‘‘oldX’’, the Xcoordinate of the end point ix called ‘‘valX’’. After thix firxt xtep, the xoftware interpretx the motion inxtructionx (G00, G01, G02 and G03) given bμ the part program and drawx them through the AutoCAD mandx ‘‘Extrude’’ and ‘‘Revolve’’. The ‘‘Extrude’’ AutoCAD mand can add the 3D to a 2D cloxed polμline, whereax the ‘‘Revolve’’ AutoCAD mand realizex a revolution xolid from a 2D cloxed polμline. The G00 inxtruction reprexentx the motionx of the tool when it doex not touch the workpiece: in our work it ix reprexented bμ a prixmatic AutoCAD xolid. The croxxxection of thix xolid ix the xame ax the tool and it ix obtained bμ ‘‘Extrude’’ mand. The ximulation of thix motion ix uxeful in order to verifμ the poxxibilitμ of a collixion with fixturing. The G01 inxtruction reprexentx the motionx of the tool when it touchex th