美制螺纹标准（粗细牙螺纹）

发布时间：2015-06-03 09:47:03 来源：文档文库

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美制内螺纹（2B）常用规格极限尺寸表（粗牙） UNC

美制内螺纹（2B）常用规格极限尺寸表（细牙）UNF

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 0.1631 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 0.2127 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 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 0.6234 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"-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 4.3485
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
7/16-20 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 13.3350 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 22.1844 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 ( 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、G－D）Straight pipe thread ( Outside )
thread in A\B: taps in G、G－D )
R－－－－锥管外螺纹（旧代号ZG;KG）Outside paper pipe thread ( Old thread code ZG,KG )
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 60°
UNC－－－－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 pitch thread
UN－－－－－统一制不变螺距螺纹Unified thread
UNS－－－－统一制特殊螺纹Unified Special thread
NPT－－－－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 connection

NPSM－－－－设备上自由配合，机械连接用直管螺纹Straight pipe thread for general purpose
NPTF－－－－干密封锥管螺纹Dryseal taper pipe thread

NPSF－－－－干密封燃油直管螺纹Dryseal straight pipe internal thread
NGT－－－－气瓶用锥螺纹Special thread for gas cylinder
三、米制螺纹Metric thread
ZM－－－－－米制锥管螺纹 Metric taper pipe thread

螺纹代号说明示例：Explanation of thread code. e. g.
1/4－20UNC
1/4－公称直径1/4" nominal dia. 1/4"
20－每寸20牙twenty teeth per inch
UNC－美标统一制粗牙螺纹unified coarse pitch thread ( American standard