英制螺纹规格直径表
英制螺纹标准对照表
英制,公制螺纹对照表.尺寸代号每英寸牙数螺距螺纹直径（in) n p 大径D、d 小径D1、d1 1/16 28 0.907 7.723 6.5611/8 28 0.907 9.728 8.5661/4 19 1.337 13.157 11.4453/8 19 1.337 16.662 14.951/2 14 1.814 20.955 18.6315/8 14 1.814 22.911 20.5873/4 14 1.814 26.441 24.1177/8 14 1.814 30.201 27.8771 11 2.309 33.249 30.2911-1/8 11 2.309 37.897 34.9391-1/4 11 2.309 41.91 38.9521-1/2 11 2.309 47.803 44.8451-3/4 11 2.309 53.746 50.7882 11 2.309 59.614 56.6562-1/4 11 2.309 65.71 62.7522-1/2 11 2.309 75.184 72.2262-3/4 11 2.309 81.534 78.5783 11 2.309 87.884 84.9263-1/2 11 2.309 100.33 97.3724 11 2.309 113.03 110.0725 11 2.309 138.43 135.4726 11 2.309 163.83 160.872 注：1in=25.4mm1、用螺纹密封的管螺纹其标记及各种螺纹的特征代号规定如下：Rc—圆锥内螺纹55度Rp—与圆锥外螺纹配合的圆柱内螺纹R—圆锥外螺纹标准规定将螺纹尺寸代号写在特征代号之后，若螺纹为械旋应再加写左旋代号LH，具体示例如下：圆锥内螺纹：Rc1/2左旋圆柱内螺纹：Rp1/2—LH圆柱内螺纹与圆锥外螺纹的配合：Rp2/R2左旋B级外螺纹：G1/2B—LH螺纹副G1/2G1/2A内螺纹：G1/2英制螺纹标准JIS B 0203,JIS B 2301(mm)#0 1.52#1 1.85#2 2.18#3 2.51#4 2.84#5 3.18#6 3.51#7 3.84#8 4.17#10 4.83#12 5.481/4 6.35UNS 是英制普通粗牙螺纹; UNF 是英制航空标示皆将分母为8, 再直接称分子之番号.Ex: 1/8 x 0.50 –PPB: 1 分牙螺丝x 0.50”长, PPBEx: 5/16 x 0.50 –PPB = 2.5/8 x 0.50-PPB : 2 分半牙螺丝x 0. 50”长, PPBEx: 5/32 x 0.50 –PPB =1.25/8 x 0.50-PPB: 1 分2 厘半螺丝x 0. 50”长, PPBEx: 1/4 x 0.50-PPB= 2/8 x 0.50-PPB: 2 分牙螺丝x 0.50”长, PP B注: 有时会标示粗牙或细牙.UNF: 细牙:电子业较常用.UNC:粗牙: 重机械结构较常用.Ex: 3/8 x 0.50 ,UNF –PPB: 3 分细牙螺丝x 0.50”长, PPB.C-2: Length Code:为英寸标示, 须乘以25.40 换算为mm.用扣规量，与公制牙型吻合是公制螺纹，与英制螺纹吻合是英制螺纹。
螺纹规格表英制螺纹规格表
螺纹规格表英制螺纹规格表螺纹规格表篇(1):螺纹标准大全螺纹标准大全螺纹，做机械的天天打交道，尤其是做液压气动的，时间一长国内的国外的，公制的英制的，直的锥的，密封的非密封的，内的外的，55度的60度的。
总之常常被搞乱，用一次从头到尾查一次，我这里也算是归纳总结一下，希望有所帮助，我的做法是常用的打印出来放在桌边，用时随时拿来查看，时间长了就自然记住了。
一NPT是一般用途的美国标准锥管螺纹，牙型角为60°PT牙为英制锥螺纹，牙型角为55°，密封中最常用。
英制管螺纹是细牙螺纹，因为粗牙螺纹的牙深大，会严重的降低所切螺纹外径管子的强度。
PF牙是管用平行螺纹。
G是55度非螺纹密封管螺纹，属惠氏螺纹家族．标记为G代表圆柱螺纹，G是管螺纹的统称(Guan)，55、60度的划分属于功能性的ZG俗称管锥，即螺纹由一圆锥面加工而成，一般的水管接头都是这样的，老国标标注为Rc公制螺纹用螺距来表示，美英制螺纹用每英寸内的螺纹牙数来表示，这是它们最大的区别，公制螺纹是60度等边牙型，英制螺纹是等腰55度牙型，美制螺纹60度。
公制螺纹用公制单位，美英制螺纹用英制单位。
管螺纹主要用来进行管道的连接，其内外螺纹的配合紧密，有直管与锥管两种。
公称直径是指所连接的管道直径，显然螺纹大径比公称直径大。
1/4，1/2，1/8是英制螺纹的公称直径，单位是英寸。
二1、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—每英寸牙数系列代号—精度等级示例：粗牙系列3/8—16UNC—2A细牙系列3/8—24UNF—2A特细牙系列3/8—32UNFF—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mm要乘以25.4，即3/8×25.4=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UNC、UNF、UNFF、UN为系列代号，最后两位2A为精度等级。
公制螺纹英制螺纹规格一览表
公制螺纹/英制螺纹规格一览表发布时间：10-06-21 来源：点击量：5424 字段选择：大中小2009-10-9外螺纹大径（单位mm）－－－－－－－－－－－－－－－－-内螺纹小径（单位mm）－－－－－－－－－－－－－－－－-序号规格型号最大最小公差最大最小公差1M10*19.9749.7940.1809.1578.9170.240 2M12*1.511.96811.7320.23610.67610.3760.300 3M14*1.513.96813.7320.23612.67612.3760.300 4M16*1.515.96815.7320.23614.67614.3760.300 5M18*1.517.96817.7320.23616.67616.3760.300 6M20*1.519.96819.7320.23618.67618.3760.300 7M22*1.521.96821.7320.23620.67620.3760.300 8M24*1.523.96823.7320.23622.67622.3760.300 9M26*1.525.96825.7320.23624.67624.3760.300 10M27*1.526.96826.7320.23625.67625.3760.300 11M30*1.529.96829.7320.23628.67628.3760.300 12M27*226.96226.6820.28025.21024.8350.375 13M30*229.96229.6820.28028.21027.8350.375 14M33*232.96232.6820.28031.21030.8350.375 15M36*235.96235.6820.28034.21033.8350.375 16M42*241.96241.6820.28040.21039.8350.375英制螺纹规格一览表外螺纹大径（单位mm）内螺纹小径（单位mm）序号规格型号最大最小公差最大最小公差1G1/8-289.7289.5140.2148.8488.5660.282 2G1/4-1913.15712.9070.25011.89011.4450.445 3G3/8-1916.66216.4120.25015.39514.9500.445 4G1/2-1420.95520.6710.28419.17218.6310.541 5G3/4-1426.44126.1570.28424.65824.1170.541 6G1-1133.24932.8890.36030.93130.2910.640 7G11/4-1141.91041.5500.36039.59238.9520.640 8G11/2-1147.80347.4430.36045.48544.8450.640类别标准名称标准号普通螺纹普通螺纹基本牙型GB/T192 —1981普通螺纹直径与螺距系列GB/T193 —1981普通螺纹基本尺寸GB/T196 —1981普通螺纹公差与配合GB/T197 —1981普通螺纹偏差表GB/T2516 —1981商品紧固件的普通螺纹选用系列JB/T7912 —1999商品紧固件的中等精度普通螺纹极限尺寸GB/T9145 —1988光学螺纹光学仪器特种细牙螺纹ZBN30006—1988光学仪器用目镜螺纹JB/T8204—1995光学仪器用短牙螺纹JB/T5450-1991紧配合螺纹过渡配合螺纹GB/T1167—1996过盈配合螺纹GB/T1181—1998小螺纹小螺纹牙型GB/T1505 4.1—1994 小螺纹直径与螺距系列GB/T1505 4.2—1994小螺纹基本尺寸GB/T1505 4.3—1994小螺纹公差GB/T15054.4-1994小螺纹极限尺寸GB/T15054.5-1994MJ螺纹MJ螺纹基本牙型GJB/T3.1 —1982 MJ螺纹螺栓与螺母螺纹的尺寸与公差GJB/T3.2 —1982MJ螺纹管路件螺纹的尺寸与公差GJB/T3.3 —1985MJ螺纹结构件的尺寸与公差GJB/T3.4 —1985MJ螺纹计算公式GJB/T3.5 —1985MJ螺纹首尾GJB52-1985梯形螺纹梯形螺纹牙型GB/T5796 .1—1986 梯形螺纹直径与螺距系列GB/T5796 .2—1986梯形螺纹基本尺寸GB/T5796 .3—1986梯形螺纹公差GB/T5796 .4—1986梯形螺纹极限尺寸GB/T12359—1990机床梯形螺纹丝杠、螺母技术条件JB/T2886—1992锻钢阀门用短牙梯形螺纹JB/TQ374—1985锯齿形螺纹锯齿形(3 °、30°)螺纹牙型GB/T13576.1—1992锯齿形(3 °、30°)螺纹直径与螺距系列GB/T13576.2—1992锯齿形(3 °、30°)螺纹基本尺寸GB/T13576.3—1992锯齿形(3 °、30°)螺纹公差GB/T13576.4—1992水压机45 °锯齿形螺纹牙型与基本尺寸JB2076—1984管螺纹用螺纹密封的管螺纹GB/T7306 —1987 非螺纹密封的管螺纹GB/T7307 —198760°圆锥管螺纹GB/T12716—1991米制锥螺纹GB/T1415—1992管路旋入端用普通螺纹尺寸系列GB/T1414—1978气瓶专用螺纹GB/T8335-1998通用基准螺纹术语GB/T1479 1—1993公制粗螺纹标准公制细螺纹标准规格标准径最大最小规格标准径最大最小规格标准径最大最小M1.0*0.25 0.75 0.785 0.729 M1.0*0.2 0.8 0.821 0.783 M15*1.0 14 14.353 13.917 M1.1*0.25 0.85 0.885 0.829 M1.1*0.2 0.9 0.921 0.883 M16*1.5 14.5 14.676 14.376 M1.2*0.25 0.95 0.985 0.929 M1.2*0.2 1 1.021 0.983 M16*1.0 15 15.153 14.917 M1.4*0.3 1.1 1.142 1.075 M1.4*0.2 1.2 1.221 1.183 M17*1.5 15.5 15.676 15.376 M1.6*0.35 1.25 1.321 1.221 M1.6*0.2 1.4 1.421 1.383 M17*1.0 16 16.153 15.917 M1.7*0.35 1.35 1.421 1.321 M1.7*0.2 1.45 1.5 1.46 M18*2.0 16 16.21 15.835 M1.8*0.35 1.45 1.521 1.421 M1.8*0.2 1.6 1.621 1.583 M18*1.5 16.5 16.676 16.376 M2.0*0.4 1.6 1.679 1.567 M2.0*0.25 1.75 1.785 1.729 M18*1.0 17 17.153 16.917 M2.2*0.45 1.75 1.888 1.713 M2.2*0.25 1.95 1.985 1.929 M20*2.0 18 18.21 17.835 M2.3*0.4 1.9 1.979 1.867 M2.3*0.25 2.05 2.061 2.001 M20*1.5 18.5 18.676 18.376 M2.5*0.45 2.1 2.138 2.013 M2.5*0.35 2.2 2.221 2.121 M20*1.0 19 19.153 18.917 M2.6*0.45 2.2 2.238 2.113 M2.5*0.35 2.2 2.246 2.186 M22*2.0 20 20.21 19.835 M3.0*0.5 2.5 2.599 2.459 M3.0*0.35 2.7 2.721 2.621 M22*1.5 20.5 20.676 20.376 M3.0*0.6 2.4 2.44 2.28 M3.5*0.35 3.2 3.221 3.121 22*1.0 21 21.153 20.917 M3.5*0.6 2.9 3.01 2.85 M4.0*0.5 3.5 3.599 3.459 M24*2.0 22 22.21 21.835 M4.0*0.7 3.8 3.422 3.242 M4.5*0.5 4 4.099 3.959 M24*1.5 22.5 22.676 22.376M4.0*0.75 3.25 3.326 3.106 M5.0*0.5 4.5 4.599 4.459 M24*1.0 23 23.153 22.917 M4.5*0.7 3.8 3.878 3.688 M5.5*0.5 5 5.099 4.959 M25*2.0 23 23.21 22.835 M5*0.8 4.2 4.334 4.134 M6.0*0.75 5.3 5.378 5.188 M25*1.5 23.5 23.676 23.376 M5*0.9 4.1 4.17 3.98 M6.0*0.5 5.5 5.55 5.4 M25*1.0 24 24.153 23.917 M6*1.0 5 5.153 4.917 M7.0*0.75 6.3 6.378 6.188 M26*1.5 24.5 24.676 24.876 M7*1.0 6 6.153 5.917 M7.0*0.5 6.5 6.55 6.4 M27*2.0 25 25.21 24.735 M8*1.25 6.8 6.912 6.647 M8.0*1 7 7.153 6.917 M27*1.5 25.5 25.676 25.376 M9*1.25 7.8 7.912 7.647 M8.0*0.75 7.3 7.378 7.188 M27*1.0 26 26.153 25.735 M10*1.5 8.5 8.676 8.376 M8.0*0.5 7.5 7.52 7.4 M28*2.0 26 26.21 25.835 M11*1.5 9.5 9.676 9.376 M9.0*1 8 8.153 7.917 M28*1.5 26 26.676 26.376 M12*1.75 10.3 10.24 10.11 M9.0*0.75 8.3 8.378 8.188 M28*1.0 27 27.153 26.917 M14*2.0 12 12.21 11.84 M10*1.25 8.8 8.912 8.647 M30*3.0 27 27.252 26.752 M16*2.0 14 14.21 13.84 M10*1.0 9 9.153 8.917 M30*2.0 28 28.21 27.835 M18*2.5 15.5 15.744 15.29 M10*0.75 9.3 9.378 9.188 M30*1.0 28 28.676 28.376 M20*2.5 17.5 17.744 17.29 M10*0.5 9.5 9.52 9.4 M32*2.0 30 29.153 28.917 M22*2.5 19.5 19.744 19.29 M11*1.0 10 10.15 9.917 M32*1.5 30 30.21 29.835 M24*3.0 21 21.252 20.75 M11*0.75 10.3 10.38 10.19 M33*3.0 30 30.676 30.376 M27*3.0 24 24.252 23.75 M12*1.5 10.5 10.68 10.38 M33*2.0 31 30.252 29.752 M30*3.5 26.5 26.771 26.21 M12*1.25 10.8 10.91 10.65 M33*1.5 31.5 31.21 30.835M12*1 11 11.15 10.92 M35*1.5 33.5 33.676 31.376M12*0.5 11.5 11.52 11.4 M36*3.0 33 33.252 32.752M14*0.5 12.5 12.68 12.38 M36*2.0 34 34.21 33.835M14*1.0 13 13.15 12.92 M36*1.5 34 34.676 34.376M15*1.50 13.5 13.68 13.38美制细螺纹标准公制迫牙丝攻钻孔径规格(丝牙外径）标准径最大最小规格精度等级7－G8 1.25 1.305 1.182 G4－G6 G7－G8 G9 NO.1-72(1.854) 1.55 1.612 1.474 M1.0*0.25 0.86 0.88 NO.2-64(2.134) 1.85 1.912 1.756 M1.1*0.25 0.96 0.98 NO.3-56(2.515) 2.1 2.197 2.025 M1.2*0.25 1.06 1.08 NO.4-48(2.345) 2.4 2.456 2.271 M1.4*0.3 1.24 1.25 NO.5-44(3.175) 2.7 2.74 2.551 M1.6*0.35 1.41 1.43 NO.6-40(3.505) 2.9 3.022 2.82 M1.7*0.35 1.51 1.53 NO.8-36(4.166) 3.5 3.606 3.404 M1.8*0.35 1.61 1.63NO.10-32(4.326) 4.1 4.165 3.963 M2.0*0.4 1.78 1.8NO.12-28(5.846) 4.6 4.724 4.496 M2.2*0.45 1.95 1.981\4-28 5.5 5.588 5.36 M2.3*0.4 2.08 2.15\16-24 6.9 7.035 6.782 M2.5*0.45 2.25 2.283\8-24 8.5 8.636 8.382 M2.6*0.45 2.35 2.387\16-20 9.9 10.033 9.729 M3.0*0.5 2.73 2.751\2-20 11.5 11.607 11.329 M3.5*0.6 3.17 3.29\16-18 12.9 13.081 12.751 M4.0*0.7 3.62 3.65 3.69 5\8-18 14.5 14.681 14.351 M5.0*0.8 4.56 4.6 4.64 3\4-16 17.5 17.678 17.323 M6.0*1.0 5.45 5.5 5.55 7\8-14 20.5 20.675 20.27 M7.0*1.0 6.45 6.5 6.55 1\8-12 23.2 23.571 23.114 M8.0*1.25 7.31 7.38 7.44 1-1\8-12 26.5 26.746 26.289 M10*1.5 9.18 9.25 9.32 1-1\4-12 29.5 29.921 29.464 M10*1.25 9.31 9.38 9.44 1-3\8-12 32 33.096 32.639 M12*1.75 11.04 11.12 11.21 1-1\2-12 36 36.271 35.814 M12*1.25 11.31 11.38 11.44英美联合螺纹标准英美联细螺纹标准规格钻头径2B螺纹径规格钻头径下孔径上限下限上限下限NO.1-64UNC 1.55 1.582 1.425 no.0-80unf 1.25 1.305 1.182 NO.2-56UNC 1.8 1.871 1.695 no.1-72unf 1.55 1.612 1.474 NO.3-48UNC 2.1 2.146 1.941 no.2-64-unf 1.85 1.912 1.756 NO.4-40UNC 2.3 2.385 2.157 no.3-565unf 2.1 2.197 2.025 NO.5-40UNC 2.6 2.679 2.487 no.4-48unf 2.4 2.458 2.271 NO.6-32UNC 2.8 2.895 2.642 no.5-44unf 2.7 2.74 2.551 NO.832UNC 3.4 3.53 3.302 no.6-40unf 2.9 3.022 2.82 NO.10-24UNC 3.9 3.926 3.683 no.8-36unf 3.5 3.606 3.404 NO.12-24UNC 4.5 4.597 4.344 no.10-32unf 4.1 4.165 3.963 1\4-20UNC 5.1 5.257 4..979 no.12-28unf 4.6 4.724 4.496 5\16-18unc 6.6 6.731 6.401 1\4-28unf 5.5 5.588 5.363\8-16UNC 8 8.153 7.798 5\16-24unf 6.9 7.035 6.782 7\16-14UNC 9.4 9.55 9.144 3\8-24unf 8.5 8.636 8.382 1\2-13UNC 10.8 11.023 10.599 7\16-20unf 9.9 10.033 9.729 9\16-12UNC 12.2 12.446 11.989 1\2-unf 11.5 11.607 11.3295\8-11UNC 13.6 13.868 13.386 9\16-unf 12.9 13.081 12.75 3\4-10UNC 16.5 16.84 16.307 5\8-18unf 14.5 14.681 14.35 7\8-9UNC 19.5 19.761 19.177 3\4-16unf 17.5 17.678 17.32 1--8UNC 22.2 22.606 21.971 7\8-14unf 20.5 20.675 20.27 11\8-7UNC 25 25.349 24.813 1--12unf 23.2 23.571 23.11 11\4-7UNC 28.2 28.524 27.813 11\8-12unf 26.5 26.746 26.28 13\8-6UNC 30.8 31.115 30.353 11\4-12unf 29.5 29.921 29.46 11\2-6UNC 34 34.29 33.528 13\8-12unf 32.8 33.096 32.63 13\4-5UNC 39.5 39.827 38.964 11\2-12unf 36 36.271 35.81 2-41\2UNC 45.2 45.593 44.679惠式螺纹标准（旧英制牙）山数节距换算表规格钻头径A例B例山数(25.4) 节数*W1\8-40 2.65 2.6 100 0.254*W5\32-32 3.25 3.2 880 0.317 5*w3\16-24 3..75 3.7 772 0.351 8W1\4-20 5.1 5 64 0.396 9W5\16-18 6.6 5 60 0.423 3W3\8-16 8 6.5 56 0.453 6W7\16-14 9.4 7.9 48 0.529 2W1\2-12 10.7 9.310.5 44 0.577 3W9\16-12 12.3 12 40 0.635W5\8-11 13.7 13.5 36 0.705 6W3\4-10 16.7 16.5 32 0.793 8W7\8-9 19.5 19.3 28 0.907 1W1-8 22.4 22 24 1.058 3W1\8-7 25 24.8 20 1.27W11\4 28.3 28 18 1.411 1W13\8-6 30.5 30.3 16 1.587 5W11\2-6 33.8 33.5 14 1.814 3W15\8-5 36 35.7 13 1.953 8W13\4-5 39.2 39 12 2.116 7W11\8-5 41.8 41.5 11 2.309 1W2-41\2 45 44.7 10 2.54牙套螺纹攻用标准9 2.8222规格钻头径下孔径8 3.175上限下限7 3.6286M3*0.5 3.1 3.2 3.12 6 4.2333M4*0.7 4.2 4.3 4.17 5 5.08M5*0.8 5.2 5.33 5.16 41\2 5.6444M6*1 6.3 6.42 6.25 4 6.35M8*1.25 8.4 8.52 8.31 31\2 7.2571M10*1.5 10.5 10.62 10.37 31\2 7.8154M10*1.25 10.4 10.52 10.31 3 8.4667M10*1 10.3 10.42 10.25 27\8 8.8348M12*1.75 12.5 12.73 12.43 23\4 9.2364M12*1.5 12.5 12.62 12.37 25\8 9.6762M12*1.25 12.5 12.52 12.31 21\2 10.16M14*2 14.5 14.83 14349M14*1.5 14.5 14.62 14.37M16*2 16.5 16.83 16.49M16*1.5 16.5 16.62 16.37M18*2.5 19 19.04 18.58M18*1.5 18.5 18.62 18.37M20*2.5 21 21.04 20.58M20*1.5 20.5 20.62 20.37公制、美制和英制螺纹标准NPT，PT，G 都是管螺纹．NPT 是National (American) Pipe Thread 的缩写，属於美国标准的60 度锥管螺纹，用於北美地区．国家标准可查阅GB/T12716-1991 PT 是Pipe Thread 的缩写，是5 5 度密封圆锥管螺纹，属惠氏螺纹家族，多用於欧洲及英联邦国家．常用於水及煤气管行业，锥度规定为1:16．国家标准可查阅GB/T7306-2000 G 是55 度非螺纹密封管螺纹，属惠氏螺纹家族．标记为G 代表圆柱螺纹．国家标准可查阅GB/T7307-2001 另外螺纹中的1/4、1/2、1/8 标记是指螺纹尺寸的直径，单位是英吋．行内人通常用分来称呼螺纹尺寸，一吋等於8分，1/4 吋就是2分，如此类推．G 好像就是管螺纹的统称(Guan)，55，60度的划分属于功能性的，俗称管圆。
英制螺纹标准规格表
英制螺纹标准规格表转速(Rotational Speed):做圆周运动的物体单位时间内沿圆周绕圆心转过的圈数，叫做转速，(与频率不同)。
用符号"n"表示;其国际标准单位为r/S (转/秒)或 r/min (转/分)，也有表示为RPM (转/分，主要为日本和欧洲采用，我国采用国际标准)。
当单位为r/S 时，数值上与频率相等，即n=f=1/T，T为作圆周运动的周期。
圆周上某点对应的线速度为:v=2π*R*n，R为该点对应的旋转半径。
常见的转速有:额定转速和最大转速等。
离心机的国际单位是g转速r/min变为g的公式:RCF=1.12*10^(-5)*r*(r/min)^2在匀速圆周运动中，线速度的大小等于运动质点通过的弧长(S)和通过这段弧长所用的时间(?t)的值。
即v=S/?t，也是V=2πR/t，在匀速圆周运动中，线速度的大小虽不改变，但它的方向时刻在改变。
它和角速度的关系是v=ω*r v=ωr=2πrf=2πnr=2πr/T当运动质点做圆周运动的同时也做另一种平动时，例如汽车车轮上的某一定点，此时该质点的线速度为做圆周运动的线速度(w*r)与平动运动的速度(v')的矢量之和:v=w*r+v' v=Δl/Δt扭矩是使物体发生转动的力。
发动机的扭矩就是指发动机从曲轴端输出的力矩。
在功率固定的条件下它与发动机转速成反比关系，转速越快扭矩越小，反之越大，它反映了汽车在一定范围内的负载能力。
扭矩说白了就是扭转所需要的力矩。
外部的扭矩叫转矩或者叫外力偶矩，内部的叫内力偶矩或者叫扭矩。
扭矩(Torque，也称为转矩)在物理学中就是力矩的大小，等于力和力臂的乘积，国际单位是牛米Nm，此外还可以看见kgm、lb-ft这样的扭矩单位，由于G=mg，当g=9.8的时候，1kg的重量为9.8N，所以1kgm=9.8Nm为什么引擎的功率能由扭矩计算出来,功率P=功W?时间t功W=力F×距离s所以，P=F×s/t=F×速度v这里的v是线速度，而在引擎里，曲轴的线速度=曲轴的角速度ω×曲轴半径r，代入上式得:功率P=力F×半径r×角速度ω;而力F×半径r=扭矩得出:功率P=扭矩×角速度ω所以引擎的功率能从扭矩和转速中算出来角速度的单位是弧度/秒，在弧度制中一个π代表180度马力其实也不是一种力，而是一种功率(Power)的单位，定义为单位时间内所能做功的大小。
英制螺纹尺寸公差表
英制螺纹尺寸公差表单位：毫米规格代号系列代号等级螺距外螺纹内螺纹名义直径每英寸牙数外径中径内径小径中径大径1 0.060—80 （0#—80）UNF2 0.3175 1.5113 –0.08128 1.30556 –0.04572 1.12268 1.1811+0.12446 1.3182 +0.05842 1.5243 0.3175 1.5240 –0.08128 1.3182 –0.03302 1.13538 1.1811 +0.12446 1.3182 +0.04318 1.5242 0.073—64 （1#—64）UNC 2 0.396875 1.83896 –0.09652 1.58242 –0.0508 1.35128 1.42494+0.15748 1.59766 +0.06604 1.8542 3 0.396875 1.8542 –0.09652 1.59766 –0.0381 1.36652 1.42494+0.15748 1.59766 +0.04826 1.85423 0.073—72 （1#—72）UNF 2 0.352777 1.83896 –0.0889 1.61036 –0.04826 1.40716 1.4732 +0.1397 1.6256 +0.0635 1.85423 0.352777 1.8542 –0.0889 1.6256 –0.03556 1.4224 1.4732 +0.1397 1.6256 +0.04826 1.85424 0.086—56 （2#—56）UNC 2 0.453571 2.16916 –0.10414 1.87452 –0.05334 1.6129 1.69418 +0.1778 1.88976 +0.07112 2.18443 0.453571 2.1844 –0.10414 1.88976 –0.04064 1.62814 1.69418 +0.1778 1.88976 +0.05334 2.18445 0.086—64 （2#—64）UNF 2 0.396875 2.16916 –0.09652 1.91262 –0.0508 1.68148 1.75514 +0.15748 1.92786 +0.06858 2.18443 0.396875 2.1844 –0.09652 1.92786 –0.0381 1.69672 1.75514 +0.15748 1.92786 +0.0508 2.18446 0.099—48 （3#—48）UNC 2 0.529166 2.49682 –0.1143 2.15392 –0.05842 1.84658 1.94056 +0.20574 2.1717 +0.07620 2.51463 0.529166 2.5146 –0.1143 2.1717 –0.04318 1.86436 1.94056 +0.20574 2.1717 +0.05588 2.51467 0.099—56 （3#—56）UNF 2 0.453571 2.49682 –0.10414 2.20218 –0.05588 1.94056 2.02438 +0.17272 2.21996 +0.07112 2.51463 0.453571 2.5146 –0.10414 2.21996 –0.04064 1.95834 2.02438 +0.17272 2.21996 +0.05334 2.51468 0.112—40 （4#—40）UNC 2 0.635 2.82448 –0.12954 2.413 –0.0635 2.0447 2.15646 +0.2286 2.43332 +0.08382 2.84483 0.635 2.8448 –0.12954 2.43332 –0.04826 2.06502 2.15646 +0.2286 2.43332 +0.06096 2.84489 0.112—48 （4#—48）UNF 2 0.529166 2.82702 –0.1143 2.48412 –0.06096 2.17678 2.27076 +0.18796 2.5019 +0.07874 2.84483 0.529166 2.8448 –0.1143 2.5019 –0.04572 2.19456 2.27076 +0.18796 2.5019 +0.05842 2.844810 0.125—40 （5#—40）UNC 2 0.635 3.15468 –0.12954 2.7432 –0.06604 2.3749 2.48666 +0.21082 2.76352 +0.08382 3.1753 0.635 3.175 –0.12954 2.76352 –0.04826 2.39522 2.48666 +0.21082 2.76352 +0.0635 3.17511 0.125—44 （5#—44）UNF 2 0.577273 3.15722 –0.12192 2.7813 –0.0635 2.44856 2.55016 +0.1905 2.79908 +0.08128 3.1753 0.577273 3.175 –0.12192 2.79908 –0.04826 2.46634 2.55016 +0.1905 2.79908 +0.06096 3.17512 0.138—32 （6#—32）UNC 2 0.79375 3.48488 –0.1524 2.96926 –0.07112 2.51206 2.6416+0.254 2.98958 +0.09398 3.50523 0.79375 3.5052 –0.1524 2.98958 –0.05334 2.53238 2.6416+0.254 2.98958 +0.06858 3.505213 0.138—40 （6#—40）UNF 2 0.635 3.48488 –0.12954 3.0734 –0.06604 2.7051 2.8194+0.2032 3.09372 +0.08636 3.50523 0.635 3.5052 –0.12954 3.09372 –0.0508 2.72542 2.8194 +0.19304 3.09372 +0.0635 3.5052序号 规格代号系列 代号 等级 螺距 外螺纹 内螺纹 名义直径 每英寸牙数外径 中径 内径 小径 中径 大径 14 0.164—32 （8#—32）UNC 2 0.79375 4.14274 –0.1524 3.62712 –0.07366 3.16992 3.302 +0.2286 3.64998 +0.09652 4.1656 3 0.79375 4.1656 –0.1524 3.64998 –0.05588 3.19278 3.302 +0.22606 3.64998 +0.07112 4.1656 15 0.164—36 （8#—36）UNF 2 0.70555 4.14528 –0.1397 3.68808 –0.07112 3.27914 3.4036 +0.2032 3.7084 +0.09144 4.1656 3 0.70555 4.1656 –0.1397 3.7084 –0.05334 3.29946 3.4036 +0.19304 3.7084 +0.06858 4.1656 16 0.190—24 （10#—24）UNC 2 1.05833 4.8006 –0.18288 4.11226 –0.08382 3.50266 3.683 +0.2794 4.13766 +0.10922 4.826 3 1.05833 4.826 –0.18288 4.13766 –0.0635 3.52806 3.683 +0.2667 4.13766 +0.08128 4.826 17 0.190—32（10#—32）UNF 2 0.79375 4.80314 –0.1524 4.28752 –0.0762 3.83032 3.9624 +0.20324.31038 +0.09906 4.826 3 0.79375 4.826 –0.1524 4.31038 –0.05842 3.85318 3.9624 +0.205744.31038 +0.07366 4.826 18 0.216—24 UNC 2 1.058335.461 –0.18288 4.77266 –0.08636 4.16306 4.3434 +0.2544.79806 +0.111765.4864 3 1.05833 5.4864 –0.18288 4.79806 –0.06604 4.18846 4.3434 +0.246384.79806 +0.83825.4864 19 0.216—28 UNF 2 0.90714 5.461 –0.1651 4.87172 –0.08128 4.34848 4.4958 +0.22864.89712 +0.106685.4864 3 0.90714 5.4864 –0.1651 4.89712 –0.06096 4.37388 4.4958 +0.220984.89712 +0.078745.4864 20 0.216—32 UNEF 2 0.79375 5.46354 –0.1524 4.94792 –0.07874 4.49072 4.6228 +0.20324.97078 +0.104145.4864 3 0.79375 5.4864 –0.1524 4.97078 –0.06096 4.51358 4.6228 +0.19054.97078 +0.078745.4864 21 0.250—20 1/4—20 UNC 1 1.276.32206 –0.30988 5.49656 –0.14224 4.76504 4.9784 +0.27945.5245 +0.185426.35 2 1.27 6.32206 –0.20574 5.49656 –0.09398 4.76504 4.9784 +0.27945.5245 +0.124466.35 3 1.27 6.35 –0.20574 5.5245 –0.07112 4.79298 4.9784 +0.271785.5245 +0.091446.35 22 0.250—28 1/4—28UNF 1 0.90714 6.3246 –0.24892 5.73532 –0.127 5.21208 5.3594 +0.22865.76072 +0.16516.35 2 0.90714 6.3246 –0.1651 5.73532 –0.08382 5.21208 5.3594 +0.22865.76072 +0.109226.35 3 0.90714 6.35 –0.1651 5.76072 –0.0635 5.23748 5.3594 +0.20325.76072 +0.081286.35 23 0.250—32 1/4—32UNEF 2 0.79375 6.3246 –0.1524 5.80898 –0.8128 5.35178 5.4864 +0.20325.83438 +0.106686.35 3 0.79375 6.35 –0.1524 5.83438 –0.6096 5.37718 5.4864 +0.175265.83438 +0.078746.35 24 .3125－18 5/16－18UNC 1 1.411117.90702 –0.33274 6.99008 –0.15494 6.17474 6.4008 +0.33027.02056 +0.200667.9375 2 1.411117.90702 –0.22098 6.99008 –0.1016 6.17474 6.4008 +0.33027.02056 +0.134627.9375 3 1.411117.9375 –0.220987.02056 –0.0762 6.20522 6.4008 +0.27947.02056 +0.099067.9375序号 规格代号系列 代号 等级 螺距 外螺纹 内螺纹 名义直径 每英寸牙数外径 中径 内径 小径 中径 大径 25 .3125—20 5/16—20UN 21.27 7.90702 –0.205747.08152 –0.1016 6.35 6.5532 +0.30487.112 +0.132087.9375 31.27 7.9375 –0.205747.112 –0.0762 6.38048 6.5532 +0.2547.112 +0.099067.9375 26 .3125—24 5/16—24UNF 11.0583337.90956 –0.274327.22122 –0.1397 6.61162 6.7818 +0.2547.24916 +0.180347.9375 21.0583337.90956 –0.182887.22122 –0.09398 6.61162 6.7818 +0.2547.24916 +0.121927.9375 31.0583337.9375 –0.182887.24916 –0.6858 6.63956 6.7818 +0.21336 7.24916 +0.091447.9375 27 .3125—28 5/16—28UN 20.90714 7.9121 –0.16517.32282 –0.8636 6.79958 6.9596 +0.20327.34822 +0.111767.9375 30.90714 7.9375 –0.16517.34822 –0.06604 6.82498 6.9596 +0.17018 7.34822 +0.083827.9375 28 .3125—32 5/16—32UNEF 20.79375 7.9121 –0.15247.39648 –0.08128 6.93928 7.0866 +0.17787.42188 +0.106687.9375 30.79375 7.9375 –0.15247.42188 –0.06096 6.96468 7.0866 +0.14478 7.42188 +0.78747.9375 29 0.375—16 3/8—16 UNC 11.5875 9.49198 –0.360688.46074 –0.1651 7.5438 7.7978 +0.35568.49376 +0.21599.525 21.5875 9.49198 –0.238768.46074 –0.11176 7.5438 7.7978 +0.35568.49376 +0.144789.525 31.5875 9.525 –0.238768.49376 –0.08382 7.57682 7.7978 +0.28448 8.49376 +0.109229.525 30 0.375—20 3/8—20UN 21.27 9.49452 –0.205748.66902 –0.10414 7.9375 8.1534 +0.27948.6995 +0.137169.525 31.27 9.525 –0.205748.6995 –0.07874 7.96798 8.1534 +0.22098 8.6995 +0.10169.525 31 0.375—24 3/8—24UNF 11.0583339.49706 –0.274328.80872 –0.14478 8.19912 8.382 +0.2548.83666 +0.18796 9.525 21.0583339.49706 –0.182888.80872 –0.09652 8.19912 8.382 +0.2548.83666 +0.12466 9.525 31.0583339.525 –0.182888.83666 –0.07366 8.22706 8.382 +0.182888.83666 +0.09398 9.525 32 0.375—28 3/8—28UN 20.90714 9.49706 –0.16518.90778 –0.09144 8.38454 8.5344 +0.22868.93572 +0.116849.525 30.90714 9.525 –0.16518.93572 –0.06858 8.41248 8.5344 +0.16764 8.93572 +0.08899.525 33 0.375—32 3/8—32UNEF 20.79375 9.4996 –0.15248.98398 –0.08636 8.52678 8.6614 +0.20329.00938 +0.111769.525 30.79375 9.525 –0.15249.00938 –0.0635 8.55218 8.6614 +0.14986 9.00938 +0.083829.525 34 0.4375—14 UNC 11.81428611.07694 –0.39379.89838 –0.18034 8.8519 9.144 +0.40649.93394 +0.2336811.1125 2 1.81428611.07694 –0.261629.89838 –0.11938 8.8519 9.144 +0.40649.93394 +0.1549411.1125 3 1.81428611.1125 –0.261629.93394 –0.0889 8.88746 9.144 +0.297189.93394 +0.1168411.1125 35 0.4375—16 UN 2 1.5875 11.07694 –0.2387610.0457 –0.11684 9.12876 9.398 +0.355610.08126 +0.1498611.1125 3 1.5875 11.1125 –0.2387610.08126 –0.08636 9.16432 9.398 +0.25410.08126 +0.114311.1125号 代号 级名义直径 每英寸牙数 外径 中径 内径 小径 中径 大径 36 0.4375—20 UNF 11.27 11.07948 –0.3098810.25398 –0.160029.52246 9.7282 +0.304810.287 +0.2057411.1125 2 1.27 11.07948 –0.2057410.25398 –0.106689.52246 9.7282 +0.304810.287 +0.1371611.1125 3 1.27 11.1125 –0.2057410.287 –0.078749.55548 9.7282 +0.21844 10.287 +0.1041411.1125 37 0.4375—28 UNEF 2 0.90714311.08456 –0.165110.49528 –0.091449.97204 10.1346 +0.203210.52322 +0.1168411.1125 3 0.90714311.1125 –0.165110.52322 –0.068589.99998 10.1346 +0.154910.52322 +0.0889 11.1125 38 0.4375—32 UN 2 0.79375 11.0871 –0.152410.57148 –0.0863610.11248 10.2616 +0.177810.59688 +0.1117611.1125 3 0.79375 11.1125 –0.152410.59688 –0.0635 10.1396810.2616 +0.137210.59688 +0.0838211.1125 39 0.500—13 UNC 1 1.95384612.6619 –0.4140211.3919 –0.1879610.2641410.5918 +0.431811.43 +0.2463812.7 2 1.95384612.6619 –0.2768611.3919 –0.12710.2641410.5918 +0.431811.43 +0.165112.7 3 1.95384612.700 –0.2768611.43 –0.0939810.3022410.5918 +0.289611.43 +0.1219212.7 40 0.500—16 UN 2 1.5875 12.66444 –0.2387611.6332 –0.1193810.7162610.9728 +0.355611.66876 +0.1549412.7 3 1.5875 12.700 –0.2387611.66876 –0.088910.7518210.9728 +0.251511.66876 +0.1168412.7 41 0.500—20 UNF 1 1.27 12.66698 –0.3098811.84148 –0.1625611.10996 11.3284 +0.431811.8745 +0.2133612.7 2 1.27 12.66698 –0.2057411.84148 –0.1092211.10996 11.3284 +0.431811.8745 +0.1422412.7 3 1.27 12.700 –0.2057411.8745 –0.0812811.14298 11.3284 +0.195611.8745 +0.1066812.7 42 0.500—28 UNEF 2 0.90714312.67206 –0.165112.08278 –0.0939811.55954 11.7094 +0.228612.11072 +0.1219212.7 3 0.90714312.700 –0.165112.11072 –0.0711211.58748 11.7094 +0.167612.11072 +0.0914412.7 43 0.500—32 UN 2 0.79375 12.6746 –0.152412.15898 –0.0889 11.70178 11.8364 +0.203212.18438 +0.114312.7 3 0.79375 12.700 –0.152412.18438 –0.0660411.72718 11.8364 +0.149812.18438 +0.0863612.7 44 0.5625—12 UNC 1 2.11666714.24686 –0.4368812.87272 –0.1981211.65098 11.9888 +0.457212.91336 +0.2590814.2875 2 2.11666714.24686 –0.2895612.87272 –0.1320811.65098 11.9888 +0.457212.91336 +0.1727214.2875 3 2.11666714.2875 –0.2895612.91336 –0.0990611.70178 11.9888 +0.312412.91336 +0.1295414.2875 45 0.5625—16 UN 2 1.5875 14.25194 –0.2387613.2207 –0.1193812.3037612.573 +0.355613.25626 +0.1549414.2875 3 1.5875 14.2875 –0.2387613.25626 –0.0889 12.3393212.573 +0.228613.25626 +0.1168414.2875号 代号 级名义直径 每英寸牙数 外径 中径 内径 小径 中径 大径 46 0.5625—18 UNF 11.41111 14.25194 –0.3327413.335 –0.17272 12.5196612.7508 +0.330213.37056 +0.2260614.2875 2 1.41111 14.25194 –0.2209813.335 –0.1143 12.5196612.7508 +0.330213.37056 +0.1498614.2875 3 1.41111 14.2875 –0.2209813.37056 –0.8636 12.5552212.7508 +0.218413.37056 +0.1117614.2875 47 0.5625—20 UN 2 1.27 14.25448 –0.2057413.42898 –0.10668 12.6974612.9032 +0.304813.462 +0.139714.2875 3 1.27 14.2875 –0.2057413.462 –0.08128 12.7304812.9032 +0.208313.462 +0.1041414.2875 48 0.5625—24 UNEF 2 1.05833 14.25702 –0.1828813.56868 –0.09906 12.9590813.1318 +0.25413.59916 +0.1295414.2875 3 1.05833 1402875 –0.1828813.59916 –0.07366 12.9895613.1318 +0.187913.59916 +0.0965214.2875 49 0.5625—28 UN 2 0.90714 14.25956 –0.165113.67028 –0.09398 13.1470413.3096 +0.203213.69822 +0.1168414.2875 3 0.90714 14.2875 –0.165113.69822 –0.07112 13.1749813.3096 +0.154913.69822 +0.0914414.2875 50 0.5625—32 UN 2 0.79375 14.2621 –0.152413.74648 –0.0889 13.2892813.4366 +0.177813.77188 +0.114314.2875 3 0.79375 14.2875 –0.152413.77188 –0.06604 13.3146813.4366 +0.137213.77188 +0.0863614.2875 51 0.625—11 UNC 1 2.30909 15.83436 –0.4622814.33576 –0.21082 13.0022613.3858 +0.482614.3764 +0.2717815.875 2 2.30909 15.83436 –0.3073414.33576 –0.1397 13.0022613.3858 +0.482614.3764 +0.1828815.875 3 2.30909 15.875 –0.3073414.3764 –0.10414 13.0429 13.3858 +0.307314.3764 +0.1371615.875 52 0.625—12 UN 2 2.11666715.83436 –0.2895614.46022 –0.13716 12.9844813.589 +0.457214.50086 +0.1803415.875 3 2.11666715.875 –0.2895614.50086 –0.10414 13.2791213.589 +0.2870214.50086 +0.1346215.875 53 0.625—16 UN 2 1.5875 15.83944 –0.2387614.8082 –0.12192 13.8912614.1478 +0.355614.84376 +0.1574815.875 3 1.5875 15.875 –0.2387614.84376 –0.09144 13.9268214.1478 +0.233714.84376 +0.1168415.875 54 0.625—18 UNF 1 1.41111115.83944 –0.3327414.9225 –0.1778 14.1071614.351 +0.330214.95806 +0.2311415.875 2 1.41111115.83944 –0.2209814.9225 –0.11938 14.1071614.351 +0.330214.95806 +0.152415.875 3 1.41111115.875 –0.2209814.95806 –0.0889 14.1427214.351 +0.203214.95806 +0.114315.875 55 0.625—20 UN 2 1.27 15.84198 –0.2057415.01648 –0.10922 14.2849614.5034 +0.279415.0495 +0.1422415.875 3 1.27 15.875 –0.2057415.0495 –0.08128 14.3179814.5034 +0.195615.0495 +0.1066815.875 56 0.625—24 UNEF 2 1.05833 15.84452 –0.1828815.15618 –0.1016 14.5465814.732 +0.25415.18666 +0.1320815.875 3 1.05833 15.875 –0.1828815.18666 –0.0762 14.5770614.732 +0.1752615.18666 +0.0990615.875序号 规格代号系列 代号 等级 螺距 外螺纹内螺纹 名义直径 每英寸牙数 外径中径 内径 小径 中径 大径 57 0.625—28 UN 2 0.90714315.84706 –0.165115.25778 –0.09652 14.7345414.8844 +0.228615.28572 +0.1244615.875 3 0.90714315.875 –0.165115.28572 –0.0711214.7624814.8844 +0.167615.28572 +0.0939815.875 58 0.625—32 UN 2 0.79375 15.84706 –0.152415.33144 –0.0914414.8742415.0114 +0.203215.35938 +0.1168415.875 3 0.79375 15.875 –0.152415.35938 –0.0685814.9021815.0114 +0.149915.35938 +0.088915.875 59 0.6875—12 UN 2 2.11667 17.42186 –0.2895616.04772 –0.1371614.8259815.1638 +0.457216.08836 +0.1803417.4625 3 2.11667 17.4625 –0.2895616.08836 –0.1041414.8666215.1638 +0.292116.08836 +0.1346217.4625 60 0.6875—16 UN 2 1.5875 17.42694 –0.2387616.3957 –0.12192 15.4787615.748 +0.355616.43126 +0.1574817.4625 3 1.5875 17.4625 –0.2387616.43126 –0.0914415.5143215.748 +0.21336 16.43126 +0.1168417.4625 61 0.6875—20 UN 2 1.27 17.42948 –0.2057416.60398 –0.1092 15.8724616.0782 +0.304816.637 +0.1422417.4625 3 1.27 17.4625 –0.2057416.637 –0.08128 15.9054816.0782 +0.208316.637 +0.1066817.4625 62 0.6875—24 UNEF 2 1.05833317.43202 –0.1828816.74368 –0.1016 16.1340816.3068 +0.25416.77416 +0.1320817.4625 3 1.05833317.4625 –0.1828816.77416 –0.0762 16.1645616.3068 +0.188016.77416 +0.0990617.4625 63 0.6875—28 UN 2 0.90714317.43456 –0.165116.84528 –0.09652 16.3220416.4846 +0.203216.87322 +0.1246617.4625 3 0.90714317.4625 –0.165116.87322 –0.07112 16.3499816.4846 +0.154916.87322 +0.0939817.4625 64 0.6875—32 UN 2 0.79375 17.43456 –0.152416.91894 –0.09144 16.4617416.6116 +0.177816.94688 +0.1168417.4625 3 0.79375 17.4625 –0.152416.94688 –0.06858 16.4896816.6116 +0.137216.94688 +0.088917.4625 65 0.750—10 UNC 1 2.54 19.00428 –0.4927617.35328 –0.22352 15.8877 16.3068 +0.533417.399 +0.292119.05 2 2.54 19.00428 –0.3276617.35328 –0.14986 15.8877 16.3068 +0.533417.399 +0.1955819.05 3 2.54 19.05 –0.3276617.399 –0.11176 15.9334216.3068 +0.317517.399 +0.1447819.05 66 0.750—12 UN 2 2.11666719.00682 –0.2895617.63268 –0.1397 16.4109416.764 +0.457217.67586 +0.1828819.05 3 2.11666719.05 –0.2895617.67586 –0.10414 16.4541216.764 +0.27178 17.67586 +0.1371619.05 67 0.750—16 UNF 1 1.5875 19.0119 –0.3606817.98066 –0.1905 17.0637217.3228 +0.355618.01876 +0.2489219.05 2 1.5875 19.0119 –0.2387617.98066 –0.127 17.0637217.3228 +0.355618.01876 +0.165119.05 3 1.5875 19.05 –0.2387618.01876 –0.09652 17.1018217.3228 +0.223518.01876 +0.1244619.05 68 0.750—20 UNEF 2 1.27 19.01698 –0.2057418.19148 –0.11176 17.4599617.6784 +0.279418.2245 +0.1447819.05 3 1.27 19.05 –0.2057418.2245 –0.08382 17.4929817.6784 +0.195618.2245 +0.1092219.05序号 规格代号系列 代号 等级 螺距 外螺纹内螺纹 名义直径 每英寸牙数 外径中径 内径 小径 中径 大径 69 0.750—28 UN 2 0.90714319.0195 –0.165118.43024 –0.09652 17.907 18.0594 +0.228618.46072 +0.127 19.05 3 0.90714319.05 –0.165118.46072 –0.0736617.9374818.0594 +0.167618.46072 +0.0939819.05 70 0.750—32 UN 2 0.79375 19.02206 –0.152418.50644 –0.0914418.0492418.1864 +0.203218.53438 +0.1193819.05 3 0.79375 19.05 –0.152418.53438 –0.0685818.0771818.1864 +0.149918.53438 +0.0914419.05 71 0.8125—12 UN 2 2.11666720.59432 –0.2895619.22018 –0.1397 17.9984418.3388 +0.457219.26336 +0.1828820.6375 3 2.11666720.6375 –0.2895619.26336 –0.1041418.0416218.3388 +0.276919.26336 +0.1371620.6375 72 0.8125—16 UN 2 1.5875 20.5994 –0.2387619.56816 –0.1244618.6512218.923 +0.355619.60626 +0.1600220.6375 3 1.5875 20.6375 –0.2387619.60626 –0.0914418.6893218.923 +0.21082 19.60626 +0.1193820.6375 73 0.8125—20 UNEF 2 1.27 20.60448 –0.2057419.77898 –0.1117619.0474619.2532 +0.304819.812 +0.1447820.6375 3 1.27 20.6375 –0.2057419.812 –0.8382 19.0804819.2532 +0.208319.812 +0.1092220.6375 74 0.8125—28 UN 2 0.90714320.607 –0.165120.01774 –0.0965219.4945 19.6596 +0.203220.04822 +0.12720.6375 3 0.90714320.6375 –0.165120.04822 –0.0736619.5249819.6596 +0.154920.04822 +0.0939820.6375 75 0.8125—32 UN 2 0.79375 20.60956 –0.152420.09394 –0.0914419.6367419.7866 +0.177820.12188 +0.1193820.6375 3 0.79375 20.6375 –0.152420.12188 –0.0685819.6646819.7866 +0.137220.12188 +0.0914420.6375 76 0.875—9 UNC 1 2.82222222.17674 –0.5283220.34286 –0.2413 18.7147219.177 +0.5842 20.39112 +0.3124222.225 2 2.82222222.17674 –0.3530620.34286 –0.1600218.7147219.177 +0.5842 20.39112 +0.2082822.225 3 2.82222222.225 –0.3530620.39112 –0.1193818.7629819.177 +0.33274 20.39112 +0.1549422.225 77 0.875—12 UN 2 2.11666722.18182 –0.2895620.80768 –0.1397 19.5859419.939 +0.457220.85086 +0.1828822.225 3 2.11666722.225 –0.2895620.85086 –0.10414 19.6291219.939 +0.2590820.85086 +0.1371622.225 78 0.875—14 UNF 1 1.81428622.18436 –0.393721.0058 –0.20574 19.9593220.2692 +0.406421.04644 +0.2692422.225 2 1.81428622.18436 –0.2616221.0058 –0.13716 19.9593220.2692 +0.406421.04644 +0.177822.225 3 1.81428622.225 –0.2616221.04644 –0.10414 19.9999620.2692 +0.223521.04644 +0.1346222.225 79 0.875—16 UN 2 1.5875 22.1869 –0.2387621.15566 –0.12446 20.2387220.4978 +0.355621.19376 +0.1600222.225 3 1.5875 22.225 –0.2387621.19376 –0.09144 20.2768220.4978 +0.223521.19376 +0.1193822.225 80 0.875—20 UNEF 2 1.27 22.19198 –0.2057421.36648 –0.11176 20.6349620.8534 +0.279421.3995 +0.1447822.225 3 1.27 22.225 –0.2057421.3995 –0.08382 20.6679820.8534 +0.195621.3995 +0.1092222.225。
英、美制螺纹标准直径、螺距参照表
d——螺纹公称直径（英寸）n——每英寸牙数
【转载】螺纹底孔直径表
英制锥度管用螺纹
管用螺纹规格
JIS B0203
JIS B0203
JIS B 2301
锥度内螺纹Rc(PT)
平行管内螺纹Rp(PS)
锥度管内螺纹
计算数值
底孔直径
计算数值
底孔直径
计算数值
底孔直径
1/16‐28
48
/
/
5#,(1/8”)
3.18
40
44
40
/
6#
3.51
32
40
/
/
8#
4.17
32
36
/
/
10#(3/16”)
4.83
24
32
24
32
12#(7/32”)
5.49
24
28
/
28
1/4”
6.35
20
28
20
26
5/16”
7.94
18
24
18
22
3/8”
9.53
16
20
16
20
7/16”
11.11
18
3/4‐14
23.349
23
23.975
24
23.305
23
1‐11
19.423
29
30.111
30
29.353
29
1 1/4‐11
37.940
38
38.772
39
37.890
38
1 1/2‐11
43.833
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1.概念：
英制螺纹是螺纹尺寸用英制标注，按外形分圆柱、圆锥两种；按牙型角分55°、60°两种。
螺纹中的1/4、1/2、1/8 标记是指螺纹尺寸的直径，单位是英寸。
一英寸等于8分，1/4 英寸就是2分，如此类推。
2螺纹标准
NPT，PT，G 都是管螺纹．
NPT 是National (American) Pipe Thread 的缩写，属于美国标准的60 度锥管螺纹，用于北美地区．国家标准可查阅GB/T12716-1991
PT 是Pipe Thread 的缩写，是55 度密封圆锥管螺纹，属惠氏螺纹家族，多用于欧洲及英联邦国家．常用于水及煤气管行业，锥度规定为1:16．国家标准可查阅GB/T7306-2000
G 是55 度非螺纹密封管螺纹，属惠氏螺纹家族．标记为G 代表圆柱螺纹．国家标准可查阅GB/T7307-2001
另外螺纹中的1/4、1/2、1/8 标记是指管子的通径，单位是英寸．
行内人通常用分来称呼螺纹尺寸，一英寸等于8分，1/4 英寸就是2分，如此类推．
G 好像就是管螺纹的统称(Guan)，55，60度的划分属于功能性的，俗称管圆。
即螺纹由一圆柱面加工而成。
ZG俗称管锥，即螺纹由一圆锥面加工而成，一般的水管接头都
是这样的
Rc表示圆锥内螺纹
ZG表示锥管螺纹，3/4"表示英寸的标注,就是3/4寸圆锥管螺纹，《五金手册》上有。
现在的国标规定ZG 3/4〃螺纹大径是26.44毫米。
可参考《公制、美制和英制螺纹标准手册(第三版)》。
它的表示方法应该是：ZG 3/4〃。
其中（〃）是英寸的代表符号。
一英寸等于8英分。
3/4的来历是6/8=3/4。
俗称6分。
同样ZG 1/2〃螺纹大径≈21毫米。
俗称4分。
ZG 1〃螺纹大径≈33毫米。
俗称1寸。
ZG 1 1/2〃螺纹的管子内径≈48毫米。
俗称1寸半。
锥管螺纹只用于液压系统连接；而管螺纹G3/4〃只用于水管连接。
锥管螺纹与管螺纹极为相似，区别只在锥度上。
注意区分管螺纹和普通螺纹的基本尺寸不同。
DN是公称直径
3.新旧标准
我国的管螺纹基本延用国际标准，采用英寸制。
因为英国标准与美国标准斗法，所以国外标准分为了两种55度60度的。
以前我国只是将管螺纹分两类：G和Z，一些工厂里仍然延用这种用法，将一些配管接头的孔标G或Z或ZG，如G1/2表示55度圆柱管螺纹，Z1/2或ZG1/2表示55度圆锥管螺纹，Z1/2(60度)或ZG1/2(60度)
表示60度圆锥管螺纹。
现在的分法是55度非密封管螺纹为G，55密封管螺纹有两种：Rp圆柱内螺纹配圆锥外螺纹R1和Rc圆锥内螺纹配圆锥外螺纹R2，60度圆锥管螺纹即NPT管螺纹标为如NPT1/2
4.检测系统
①硬件系统螺纹参数自动检测系统基于PC架构，主要由照明系统、CCD相机和光路成像系统、、图像采集卡、图像处理系统、机械检测系统以及电控系统等组成。
测量时，经照明系统照明后，通过CCD相机和光路成像系统采集紧固件的螺纹图像，然后经过图像采集卡，将数字化图像传到计算机，计算机对该数字图像按相应算法处理后，计算出螺纹的牙型角、螺距和中径等参数，并与标准进行比较，计算出偏差。
②软件系统螺纹参数自动检测的软件系统主要包括系统控制模块图像处理模块等。
系统控制模块：初始化；完成系统图像接口卡及标准参数的初始化配置。
图像操作；采集并保存8位的灰色图像，捕获图像到内存。
图像处理模块：图像处理模块包括减少噪声、突出螺纹轮廓边缘信息的图像预处理算法，检测和提取轮廓边缘信息的边缘检测和提取算法，测量数字图像实际尺寸的系统标定算法，以及用于计算螺纹参数的算法等。