公英制螺纹对照表

英制、公制对照英寸制统一螺纹，在英寸制国家广泛采用，该类螺纹分三个系列：粗牙系列UNC细牙系列UNF特细牙系列UNFF外加一个定螺距系列UN标注方法：螺纹直径一每英寸牙数系列代号一精度等级示例：粗牙系列3/8—16UN—2A细牙系列3/8—24UN—2A特细牙系列3/8—32UNF—2A定螺距系列3/8—20UN-2A第一位数字3/8表示螺纹外径，单位为英寸，转换为米制单位mn要乘以25.4，即3/8X25.4=9.525mm；第二、三位数字16、24、32、20为每英寸牙数（在25.4mm长度上的牙数）；第三位以后的文字代号UNCUNFUNFFUN为系列代号，最后两位2A为精度等级。在统一螺纹中规定，一个公称尺寸可有不同的螺距，如1/2就有13牙、16牙、20牙、32牙之分，标准规定13牙为粗牙，20牙为细牙，28牙为超细牙；16牙和32牙都称为恒定螺距，与粗牙、细牙没什么不同。英制螺纹外径公制对照表英制公制英制公制英制公制4#|2.9「1-5/841.2754-5/8117.4755#3.21-3/444.454-3/4120.656#3.51-7/847.6254-7/8123.8257#3.92:50.851278#「4.2「2-1/853.9755-1/4133.35「10#4.8「2-1/457.155-3/8136.52512#5.5:I,12-3/860.3255-1/2139.714#/1/46.35、1.12-1/263.55-5/8142.8751/83.1752-5/866.6755-3/4146.051/46.352-3/469.855-7/8149.2255/167.936J.12-7/8[73.0256「152.43/89.525376.26-1/4158.757/1611.1133-1/879.3756-3/8161.9251/212.73-1/482.556-1/2:168.2759/1614.2883-3/8[85.7256-5/8:171.455/815.8753-1/288.96-3/4174.6253/419.053-5/892.0256-7/8177.87/822.2253-3/4P95.257「184.15125.43-7/898.1257-1/4187.3251-1/828.5754101.67-3/8190.51-1/431.754-1/4[107.957-1/2:193.6751-3/834.9254-3/8111.1257-5/8196.851-1/238.14-1/2114.37-3/4200.025精心整理英美联合公制规格底孔①规格底孔①1-64UNC1.55M1.0*0.250.752-56UNC”1.8M1.1*0.250.853-48UNC2.1M1.2*0.250.954-40UNC2.3M1.4*0.31.15-40UNC2.6M1.6*0.351.256-32UNC2.8[M1.7*0.351.358-32UNC3.4M1.8*0.351.4510-32UNC4.1M2.0*0.41.610-24UNC3.9M2.2*0.451.7512-24UNCJ4.5「M2.3*0.41.91\4-20UNC5.1M2.5*0.452.15\16-18unc6.6M2.6*0.452.2「:：：3\8-16UNC8M3.0*0.52.57\16-14UNC9.4「M3.0*0.62.41\2-13UNC10.8M3.5*0.62.99\16-12UNC12.2M4.0*0.73.35\8-11UNC13.6M4.0*0.753.253\4-10UNC116.5M4.5*0.73.87\8-9UNC19.5M5*0.84.21--8UNC22.2M5*0.94.111\8-7UNC25M6*1.0511\4-7UNC28.2M7*1.0613\8-6UNC130.8M8*1.256.811\2-6UNC34M9*1.257.813\4-5UNC39.5M10*1.58.52-41\2UNC45.2M11*1.59.5M12*1.7510.3hX.1；=i=rrtL丄_Li=t―-H-M14*2.012英美联合螺纹螺距恨据每一英寸长度上拥有的牙数来计算外径根据螺纹牌号的第一个代号来计算（4#，5#，6#，7#，8#，10#，12#为特殊外径详见表1）M16*2.014M18*2.515M20*2.517M22*2.519例：1/4-20UNCM24*3.0211/4*25.4=6.35（螺纹外径）M27*3.02425.4/20=1.27（螺距）M30*3.526.5螺纹电极外径，螺距参照表精心整理英美联合公制规格外径①规格外径①1-64UNC1.45M1.0*0.250.652-56UNC1.7M1.1*0.250.753-48UNC2.0M1.2*0.250.854-40UNC2.2M1.4*0.31.05-40UNC2.5M1.6*0.351.156-32UNC2.7「M1.7*0.351.258-32UNC3.3M1.8*0.351.3510-32UNC4.0M2.0*0.41.510-24UNC3.8M2.2*0.451.6512-24UNC4.4M2.3*0.41.81\4-20UNC5.0M2.5*0.45、2.05\16-18unc6.5M2.6*0.452.1「:：：3\8-16UNC7.9M3.0*0.52.47\16-14UNC9.3:M3.0*0.62.31\2-13UNC10.7M3.5*0.62.89\16-12UNC12.1M4.0*0.7|3.3|5\8-11UNC13.5M4.0*0.753.153\4-10UNC16.4:M4.5*0.73.77\8-9UNC19.4M5*0.84.11--8UNC22.1M5*0.94.011\8-7UNC24.9M6*1.04.911\4-7UNC2>8.1M7*1.05.913\8-6UNC30.7M8*1.256.7|11\2-6UNC33.9M9*1.257.713\4-5UNC39.4M10*1.58.42-41\2UNC45.1M11*1.59.4M12*1.7510.2hX.1；M14*2.011.9半Wi人由田厶？rrhSI口匚士1=（壬戸侍.M16*2.013.9央美联合骡纹骡距根据母央寸长度上拥有的牙数来计算例:1/4_20UNCM18*2.514.9M20*2.516.91/4*25.4=6.35（螺纹外径）（螺距）M22*2.518.925.4/20=1.27M24*3.020.9阴影部为英制和公制粗牙常M27*3.023.9用螺纹M30*3.526.5