攻螺纹前底孔直径的确定.doc

攻螺纹前底孔直径的确定表1.普通螺纹钻底孔用钻头直径尺寸（单位：mm）计算公式：P1mm时 D0=d-PP1mm时 D0=d-(11.1)P式中 P螺距（mm）D0攻螺纹前钻头直径（mm）d螺纹公称直径（mm）公称直径d螺距P钻头直径D01粗0.250.75细0.20.82粗0.41.6细0.251.753粗0.52.5细0.352.654粗0.73.3细0.53.55粗0.84.2细0.54.56粗15细0.755.28粗1.256.7细10.7577.210粗1.58.5细1.2510.758.799.212粗1.7510.2细1.51.25110.510.71114粗211.9细1.51.25112.512.71316粗213.9细1.5114.51518粗2.515.4细21.5115.916.51720粗2.517.4细21.5117.918.51922粗2.519.4细21.5119.920.52124粗320.9细21.5121.922.52327粗323.9细21.5124.925.52630粗3.526.3细321.5126.927.928.52933粗3.529.3细321.529.930.931.536粗431.8细321.532.933.934.539粗434.8细321.535.936.937.542粗4.537.3细4321.537.838.939.940.545粗4.540.3细4321.540.841.942.943.548粗542.7细4321.543.844.945.946.552粗546.7细4321.547.848.949.950.5表2.英寸制螺纹钻底孔用钻头直径尺寸计算公式：螺纹公称直径 铸铁与青铜 铜与青铜3/16in5/8in D0=25(d-1/n) D0=25(d-1/n)+0.13/4in11/2in D0=25(d-1/n) D0=25(d-1/n)+0.2式中 D0攻螺纹前钻头直径（mm）d螺纹公称直径（in）n每英寸牙数公称直径/in每英寸牙数钻头直径/mm铸铁、青铜钢、黄铜3/161/45/163/87/161/29/165/83/47/8111/811/411/215/813/417/82242018161412121110987765541/241/23.75.06.47.89.110.41213.316.319.121.924.627.833.435.738.941.444.63.75.16.57.99.310.512.113.516.419.32224.727.933.535.83941.544.7表3.圆柱管螺纹钻底孔用钻头直径尺寸公称直径/in每英寸牙数钻头直径/mm1/81/43/81/25/83/47/8111/811/413/811/213/4228191914141414111111111111118.811.715.218.920.824.328.130.535.239.241.645.15157表4.圆锥管螺纹钻底孔用钻头直径尺寸55圆锥管螺纹公称直径/in每英寸牙数钻头直径/mm1/81/43/81/23/4111/411/222819191414111111118.411.214.718.323.629.738.344.155.860圆锥管螺纹公称直径/in每英寸牙数钻头直径/mm1/81/43/81/23/