螺纹底孔标准.pdf

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1、螺纹底孔直径一、螺纹底孔直径计算式螺纹底孔直径可参照表1、表2的公式计算，也可查表3至表11。表1加工米制普通螺纹底孔钻头直径D的计算公式适用范围D=d–t（1）螺距t<1；1式中d：螺纹的公称直径（2）工件材料塑性较大；t：螺距（3）孔扩张量适中。（1）螺距t<1；2D=d–(1.04～1.08)t（2）工件材料塑性较小；（3）孔扩张量较小。表2加工英制螺纹底孔钻头直径的计算公式(mm)螺纹公称直径铸铁与青铜钢与黄铜(英寸)3/16"～5/8"D=25.4·(d-1/n)D=25.4·(d-1/n)+0

2、.13/4"～11/2"D=25.4·(d-1/n)D=25.4·(d-1/n)+0.2注：n—每英寸牙数·2·二、螺纹底孔直径表表3米制粗牙螺纹攻丝前用的钻头直径(mm)螺纹小直径级别钻头公称直径螺距5H6H7H5H、6H、7H直径maxmaxmaxmin10.250.7850.7290.751.20.250.9850.9290.951.60.351.3011.3211.2211.2520.41.6571.6791.5611.602.50.452.1122.1382.0132.0530.52.5712.

3、5992.6392.4592.5040.73.3823.4223.4663.2423.3050.84.2944.3344.3844.1344.20615.0075.1535.2174.9175.0081.256.8596.9126.9826.6476.80101.58.6128.6768.7518.3768.50121.7510.37110.44110.53110.10610.214212.13512.21012.31011.83512.016214.13514.21014.31013.83514.018

4、2.515.64915.74415.85415.29415.5202.517.64917.74417.85417.29417.5222.519.64919.74419.85419.29419.524321.15221.25221.38220.75421.0·3·表4米制细牙螺纹攻丝前用的钻头直径(mm)螺纹小直径级别钻头公称直径螺距5H6H7H5H、6H、7H直径maxmaxmaxmin2.52.2012.2212.1212.150.3532.7012.7212.6212.6543.5713.5993.6

5、393.4593.500.554.5714.5994.6394.4594.5065.3385.3785.4245.1885.7080.757.3387.3787.4247.1887.20109.3389.3789.4249.1889.2087.1077.2177.2176.9177.00109.1079.2179.2178.9179.001211.10711.21711.21710.91711.01413.10713.21713.21712.91713.016115.10715.21715.21714.9

6、1715.01817.10717.21717.21716.91717.02019.10719.21719.21718.91719.02221.10721.21721.21720.91721.02423.10723.21723.21722.91723.0108.8598.9128.9828.6478.80121.2510.85910.91210.98210.64710.81412.85912.91212.98212.64712.81210.61210.67610.75110.37610.51412.6121

7、2.67612.75112.37612.51513.61213.67613.75113.37613.5161.514.61214.67614.75114.37614.51816.61216.67616.75116.37616.52018.61218.67618.75118.37618.52220.61220.67620.75120.37620.5·4·螺纹小直径级别钻头公称直径螺距5H6H7H5H、6H、7H直径maxmaxmaxmin2422.61222.67622.75122.37622.51.525

8、23.61223.67623.75123.37623.51816.13516.21016.31015.83516.02018.13518.21018.31017.83518.022220.13520.21020.31019.83520.02422.13522.21022.31021.83522.02523.13523.21023.31022.83523.0表5英国标准粗牙惠氏螺纹Ｂ、Ｓ、Ｗ攻丝前用的钻头直径(mm)公称直径钻头