1、 美制内螺纹（2B）常用规格极限尺寸表（粗牙） UNC公称尺寸和每英寸牙数小径极限最小 最大中径极限最小 最大大径 min 底孔直径 最小 最大 8-32 UNC(0.164-32)0.1300 0.13903.3020 3.53060.1437 0.14753.6500 3.74650.16404.16563.40 3.50 10-24(0.190-24)0.1450 0.15603.6830 3.96240.1629 0.16724.1377 4.24690.19004.8260 3.75 3.90 12-24(0.216-24)0.1710 0.18104.3434 4.59740.18
2、89 0.19334.7981 4.90980.21605.48644.40 4.55 1/4-20(0.250-20)0.1960 0.20704.9784 5.25780.2175 0.22245.5245 5.64900.25006.35005.05 5.20 5/16-18(0.3175-18)0.2520 0.26506.4008 6.73100.2764 0.28177.0206 7.15520.31257.93756.45 6.60 3/8-16(0.375-16)0.3070 0.32107.7978 8.15340.3344 0.34018.4938 8.63850.3750
3、9.52507.85 8.00 7/16-14(0.4375-14)0.3600 0.37609.1440 9.55040.3911 0.39729.9339 10.08890.437511.11259.20 9.40 1/2-13(0.50-13)0.4170 0.434010.5918 11.02360.4500 0.456511.4300 11.59510.500012.700010.65 10.90 9/16-12(0.5625-12)0.4720 0.490011.9888 12.44600.5084 0.515212.9134 13.08610.562514.287512.05 1
4、2.30 5/8-11(0.625-11)0.5270 0.546013.3858 3.86840.5660 0.573214.3764 14.55930.625015.875013.45 13.70 3/4-10(0.750-10)0.6420 0.663016.3068 16.84020.6850 0.692717.3990 17.59460.750019.050016.40 16.70 7/8-9(0.875-9)0.7550 0.778019.1770 19.76120.8028 0.811020.3911 20.59940.875022.2250 19.30 19.60 1“-8(1
5、.000-8)0.8650 0.890021.9710 22.60600.9188 0.927623.3375 23.56101.000025.400022.10 22.40 1.底孔直径指攻丝前钻孔直径，铸铁、黄铜等较软料取小值，钢、青铜等较硬料取大值。2.标记示例：10-24UNC-2B(或 0.190-24UNC-2B)、3/8-16UNC-2B(或 0.375-16UNC-2B) 美制内螺纹（2B）常用规格极限尺寸表（细牙）UNF 公称尺寸和 小径极限 中径极限 大径 min 底孔直径每英寸牙数 最小 最大 最小 最大 最小 最大8-36 UNF 0.1340 0.1420 0.146
6、0 0.1496 0.1640 3.45 3.67 (0.164-36) 3.4036 3.6068 3.7084 3.7998 4.1656 10-32 0.1560 0.1640 0.1697 0.1736 0.1900 4.00 4.27 (0.190-32) 3.9624 4.1656 4.3104 4.4094 4.8260 12-28 0.1770 0.1860 0.1928 0.1970 0.2160 4.55 4.85 (0.216-28) 4.4958 4.7244 4.8971 5.0038 5.4864 1/4-28 0.2110 0.2200 0.2268 0.2311
7、 0.2500 5.40 5.71 (0.250-28) 5.3594 5.5880 5.7607 5.8699 6.3500 5/16-24 0.2670 0.2770 0.2854 0.2902 0.3125 6.85 7.20 (0.3175-24) 6.7818 7.0358 7.2492 7.3711 7.9375 3/8-24 0.3300 0.3400 0.3479 0.3528 0.3750 8.45 8.78 (0.375-24) 8.3820 8.6360 8.8367 8.9611 9.5250 7/16-20 0.3830 0.3950 0.4050 0.4104 0.
8、4375 9.85 10.23 (0.4375-20) 9.7282 10.0330 10.2870 10.4242 11.1125 1/2-20 0.4460 0.4570 0.4675 0.4731 0.5000 11.40 11.82 (0.50-20) 11.3284 11.6078 11.8745 12.0167 12.7000 9/16-18 0.5020 0.5150 0.5264 0.5323 0.5625 12.85 13.31 (0.5625-18) 12.7508 13.0810 13.3706 13.5204 14.2875 5/8-18 0.5650 0.5780 0
9、.5889 0.5949 0.6250 14.45 14.89 (0.625-18) 14.3510 14.6812 14.9581 15.1105 15.8750 3/4-16 0.6820 0.6960 0.7094 0.7159 0.7500 17.40 17.95 (0.750-16) 17.3228 17.6784 18.0188 18.1839 19.0500 7/8-14 0.7980 0.8140 0.8286 0.8356 0.8750 20.35 20.97 (0.875-14) 20.2692 20.6756 21.0464 21.2242 22.2250 1“-12 0
10、.9100 0.9280 0.9459 0.9535 1.0000 23.90 23.95 (1.000-12) 23.1140 23.5712 24.0259 24.2189 25.4000 1.底孔直径指攻丝前钻孔直径，铸铁、黄铜等较软料取小值，钢、青铜等较硬料取大值。2.标记示例：10-32UNF-2B(或 0.190-32UNF-2B)、3/8-24UNF-2B(或 0.375-24UNF-2B) 美制外螺纹（2A）常用规格极限尺寸表（粗牙） UNC 公称尺寸/ 大径极限 中径极限 小径 max 螺胚直径每英寸牙数 最小 最大 最小 最大 最小 最大8-32 UNC 0.1571 0.
11、1631 0.1399 0.1428 0.1248 3.58 3.61 (0.164-32) 3.9903 4.1427 3.5535 3.6271 3.1699 10-24 0.1818 0.1890 0.1586 0.1619 0.1379 4.07 4.10 (0.190-24) 4.6177 4.8006 4.0284 4.1123 3.5027 12-24 0.2078 0.2150 0.1845 0.1879 0.1639 4.72 4.75 (0.216-24) 5.2781 5.4610 4.6863 4.7727 4.1631 1/4-20 0.2408 0.2489 0.2
12、127 0.2164 0.1876 5.45 5.48 (0.250-20) 6.1163 6.3221 5.4026 5.4966 4.7650 5/16-18 0.3026 0.3113 0.2712 0.2752 0.2431 6.94 6.98 (0.3175-18) 7.6860 7.9070 6.8885 6.9901 6.1747 3/8-16 0.3643 0.3737 0.3287 0.3331 0.2970 8.40 8.44 (0.375-16) 9.2532 9.4920 8.3490 8.4607 7.5438 7/16-14 0.4258 0.4361 0.3850
13、 0.3897 0.3485 9.83 9.87 (0.4375-14) 10.8153 11.0769 9.7790 9.8984 8.8519 1/2-13 0.4876 0.4985 0.4435 0.4485 0.4041 11.34 11.38 (0.50-13) 12.3850 12.6619 11.2649 11.3919 10.2641 9/16-12 0.5495 0.5609 0.5016 0.5068 0.4587 12.80 12.84 (0.5625-12) 13.9573 14.2469 12.7406 12.8727 11.6510 5/8-11 0.6113 0
14、.6234 0.5589 0.5644 0.5119 14.27 14.32 (0.625-11) 15.5270 15.8344 14.1961 14.3358 13.0023 3/4-10 0.7353 0.7482 0.6773 0.6832 0.6255 17.28 17.33 (0.750-10) 18.6766 19.0043 17.2034 17.3533 15.8877 7/8-9 0.8592 0.8731 0.7946 0.8009 0.7368 20.27 20.32 (0.875-9) 21.8237 22.1767 20.1828 20.3429 18.7147 1“
15、-8 0.9830 0.9980 0.9100 0.9168 0.8446 23.22 23.27 (1.000-8) 24.9682 25.3492 23.1140 23.2867 21.4528 1.螺胚直径指滚丝前的尺寸，数值为依经验公式计算而得，在实践中需验证。 2.标记示例：10-24UNC-2A(或 0.190-24UNC-2A)、3/8-16UNC-2A(或 0.375-16UNC-2A)（注：表中上行斜体数值单位为英寸，下行为毫米）美制外螺纹（2A）常用规格极限尺寸表（细牙）UNF 公称尺寸和每英寸牙数 螺纹系列代号 大径极限 中径极限 小径 max 螺胚直径最小 最大 最小
16、最大 最小 最大8-36 UNF 0.1577 0.1632 0.1424 0.1452 0.1291 3.65 3.67 (0.164-36) 4.0056 4.1453 3.6170 3.6881 3.2791 10-32 0.1831 0.1891 0.1658 0.1688 0.1508 4.24 4.27 (0.190-32) 4.6507 4.8031 4.2113 4.2875 3.8303 12-28 0.2085 0.2150 0.1886 0.1918 0.1712 4.82 4.85 (0.216-28) 5.2959 5.4610 4.7904 4.8717 4.348
17、5 1/4-28 0.2425 0.2490 0.2225 0.2258 0.2052 5.69 5.71 (0.250-28) 6.1595 6.3246 5.6515 5.7353 5.2121 5/16-24 0.3042 0.3114 0.2806 0.2843 0.2603 7.17 7.20 (0.3175-24) 7.7267 7.9096 7.1272 7.2212 6.6116 3/8-24 0.3667 0.3739 0.3430 0.3468 0.3228 8.75 8.78 (0.375-24) 9.3142 9.4971 8.7122 8.8087 8.1991 7/
18、16-20 0.4281 0.4362 0.3995 0.4037 0.3749 10.19 10.23 (0.4375-20) 10.8737 11.0795 10.1473 10.2540 9.5225 1/2-20 0.4906 0.4987 0.4619 0.4662 0.4374 11.78 11.82 (0.50-20) 12.4612 12.6670 11.7323 11.8415 11.1100 9/16-18 0.5524 0.5611 0.5205 0.5250 0.4929 13.27 13.31 (0.5625-18) 14.0310 14.2519 13.2207 1
19、3.3350 12.5197 5/8-18 0.6149 0.6236 0.5828 0.5875 0.5554 14.85 14.89 (0.625-18) 15.6185 15.8394 14.8031 14.9225 14.1072 3/4-16 0.7391 0.7485 0.7029 0.7079 0.6718 17.91 17.95 (0.750-16) 18.7731 19.0119 17.8537 17.9807 17.0637 7/8-14 0.8631 0.8734 0.8216 0.8270 0.7858 20.93 20.97 (0.875-14) 21.9227 22
20、.1844 20.8686 21.0058 19.9593 1“-12 0.9868 0.9982 0.9382 0.9441 0.8960 23.90 23.95 (1.000-12) 25.0647 25.3543 23.8303 23.9801 22.7584 1.螺胚直径指滚丝前的尺寸，数值为依经验公式计算而得，在实践中需验证。 2.标记示例：10-32UNF-2A(或 0.190-32UNF-2A)、3/8-24UNF-2A(或 0.375-24UNF-2A)螺纹代号 Thread Code一、英制螺纹（螺纹牙型角 55 度）Thread of British standard (
21、Thread pitch shape angle 55)BSW英国标准惠氏螺纹（粗牙）British Standard Whitworth Thread ( Coarse )BSF英国标准惠氏螺纹（细牙）British Standard Whitworth Thread ( Fine )G直管螺纹（外螺纹分 A、B 两面级、丝锥分 G、GD）Straight pipe thread ( Outside ) thread in AB: taps in G、GD )R锥管外螺纹（旧代号 ZG;KG）Outside paper pipe thread ( Old thread code ZG,KG
22、)RC锥管内螺纹（旧代号 ZG;KG）Inside taper pipe thread ( Old thread code ZG,KG )二、美制螺纹（螺纹牙型角 60 度）Thread of American standard ( Thread pitch shape angle 60UNC统一制粗牙螺纹（代替 NC）Unified coarse pitch thread ( Instead of NC )UNF统一制细牙螺纹（代替 NF）Unified fine pitch thread ( Instead of NF )UNEF统一制超细牙螺纹 Unified superfine pit
23、ch threadUN统一制不变螺距螺纹 Unified threadUNS统一制特殊螺纹 Unified Special threadNPT一般用途锥管螺纹（旧代号 Z;K）Taper pipe thread for general purpose ( Old thread code Z,K )NPSC管接头直管内螺纹 Internal straight pipe thread for connectionNPSM设备上自由配合，机械连接用直管螺纹 Straight pipe thread for general purposeNPTF干密封锥管螺纹 Dryseal taper pipe t
24、hreadNPSF干密封燃油直管螺纹 Dryseal straight pipe internal threadNGT气瓶用锥螺纹 Special thread for gas cylinder三、米制螺纹 Metric threadZM米制锥管螺纹 Metric taper pipe thread螺纹代号说明示例：Explanation of thread code. e. g.1/420UNC1/4公称直径 1/4“ nominal dia. 1/4“20每寸 20 牙 twenty teeth per inchUNC美标统一制粗牙螺纹 unified coarse pitch thread ( American standard
