Research On Large Machining Strip&Tool Design For Small-curvature Surface Of Automobile Mold

CNC machining efficiency of automobile covering mold directly affects theautomobile production and exchange-type cycle, Its materials are mostlyCr12MoV or7CrSiMnMoV, typical high-strength and high hardness materials.Inthis paper, the small-curvature surface of automobile covering mold is the mainobject of study, the research on large machining strip is done to increase theeffective cutting interval.The following are the main contents of this dissertation:1. To analyze efficiently the cutter’s milling performance, it is raised thattool path interval can be replaced with effective cutting width, which meansindependently cutting into the work-piece once. Based on the geometry contactrelations, the effective cutting speeds on contact surfaces are analyzed for boththe torus cutter and ball-end mill. A math model for3-axis machining ispresented between the effective cutting interval and some machining parameters,such as cutters, the surface slope, the cutting depth, the feed direction, which isbased on the projection shape on the contact points’ tangent plane for the parts ofcutting into the work-piece. The theory basis is provided for the tool pathoptimization in three axis machining with torus cutter based on the raised models.2. Based on the conclusion that the optimal cutter feed direction is alone thedirection of the workpiece height changing， which can maximize effectivecutting interval，tool path planning is done for two kinds of special surface.Through experiments and simulations, it proves the advantages of the method oftool path planing. The problem of curvature interference and concave-uncut isanalyzed, when the torus cutter machines small-curvature concave surface in3-axis machine tools. In order to reduce the amount owed to cut, it proposes the useof high feed milling cutter to complete the small curvature concave surfaceinstead of torus cutter, and makes the corresponding toolpath planning.3. A new kind of cutter for complex cavity roughing and semi-finishing isdesigned, which can improve ball end mill`s poor end milling ability and decrease flat-end width, Compared with the torus cutter, which can significantlyreduce the amount owed to cut. It designs indexable cutting tool and grinds asolid carbide cutting tools, it designs indexable cutting tool and grinds a solidcarbide cutting tool, and the experiment to verify the actual processing of newcutter is done.4. The experiments of processing small-curvature surface of two typicalautomobile molds are completed. Two kinds of process planning processes aredeveloped respectively for the small curvature convex or concave surfaces.Experimental results show that the methods of large machining strip processingtechnology can improve the processing efficiency more than25%, compared tothe ordinary ball end mill processing method.