几何作图课件.ppt

*Equilateralpolygon正多边形Slopeandtaper斜度和锥度Arcconnection圆弧连接Techniquesfordrawing2Dobjects平面图形的画法Exercise练习题GeometricConstruction几何作图请点击相应标题显示其内容Equilateralpolygon正多边形请点击标题显示其内容1.Regularhexagons正六边形的画法2.Equilateralpolygon正n边形的画法1)Constructregularhexagon(DIA40mm=A/CofHEX).作正六边形(其外接圆直径d为40mm=正六边形对角距)。Constructtworegularhexagons(DIA40mm=A/CorA/FofHEX作两个正六边形(其外切或内接圆直径d为40mm=正六边形对角距或对边距)。1)Giventhediameterofcircumcircle,drawapositivepentagon(n=5).已知其外接圆直径,作正五边形（n=5）。2)Giventhediameterofcircumcircle,drawaregularpolygon(n=7).已知其外接圆直径,作正多边形（n=7）。10Slopeandtaper斜度和锥度1.Slope斜度HL5801000请点击鼠标左键显示后面内容Theslopesymbol(斜度符号):slope(斜度)=tanα=H/LWhendimensioning,theobliquedirectionoftheslopesymbolshouldbeinaccordancewiththeactualslopedirection.标注时要注意符号斜线方向与斜度方向一致Example:Drawingofslope(?1∶8,uponpointO5mm?left100mm).过O点左100mm、上5mm之点作斜度为1∶8的斜线。Example:Drawingoftaper1∶7(H=30mm,?=40mm).已知H=30mm,?=40mm,求作锥度为1∶7的图形。d2.Taper锥度HL?304070taper(锥度)=2tan(?/2)=H/L=(H-d)/?10请点击鼠标左键显示后面内容Slopeandtaper斜度和锥度Thetapersymbol(锥度符号):Whendimensioning,theorientationofthetapersymbolshouldbeinaccordancewiththeorientationoftheactualcone.标注时要注意符号斜线方向与锥度方向一致。R1OR1Constructprinciple:Thekeyintangencyprincipleistofindthecenterofthearcandthetangentpositionofthecorrespondinglines,lineandarc,andarcsrespectively.作图原理圆弧连接作图的关键在于,找出连接弧的圆心位置及与两被连接线段连接处的切点位置。Arcconnection圆弧连接请点击例题显示其内容Theso-calledarcconnectionisoftenusedforsmoothconnectionbetweenlinesandcirclesusingarcs.所谓圆弧连