[摘要]对标准系列、标准旋合长度和标准公差的统一螺纹,其标记包含五项基本内容。它们是公称直径牙数、螺纹系列代号、公差带代号和 检验体系代号。
美制螺纹标准对照表
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美制外螺纹(2A)常用规格极限尺寸表(粗牙)
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公称尺寸和每英寸牙数
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螺纹系列代号
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大径极限
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中径极限
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小径max
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螺胚直径
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最小
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最大
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最小
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最大
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最小
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最大
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8-32
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UNC
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0.1571
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0.1631
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0.1399
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0.1428
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0.1248
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3.58
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3.61
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(0.164-32)
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3.9903
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4.1427
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3.5535
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3.6271
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3.1699
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10-24
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0.1818
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0.1890
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0.1586
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0.1619
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0.1379
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4.07
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4.10
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(0.190-24)
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4.6177
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4.8006
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4.0284
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4.1123
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3.5027
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12-24
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0.2078
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0.2150
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0.1845
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0.1879
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0.1639
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4.72
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4.75
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(0.216-24)
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5.2781
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5.4610
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4.6863
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4.7727
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4.1631
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1/4-20
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0.2408
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0.2489
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0.2127
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0.2164
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0.1876
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5.45
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5.48
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(0.250-20)
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6.1163
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6.3221
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5.4026
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5.4966
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4.7650
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5/16-18
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0.3026
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0.3113
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0.2712
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0.2752
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0.2431
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6.94
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6.98
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(0.3175-18)
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7.6860
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7.9070
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6.8885
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6.9901
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6.1747
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3/8-16
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0.3643
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0.3737
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0.3287
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0.3331
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0.2970
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8.40
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8.44
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(0.375-16)
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9.2532
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9.4920
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8.3490
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8.4607
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7.5438
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7/16-14
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0.4258
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0.4361
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0.3850
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0.3897
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0.3485
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9.83
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9.87
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(0.4375-14)
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10.8153
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11.0769
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9.7790
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9.8984
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8.8519
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1/2-13
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0.4876
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0.4985
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0.4435
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0.4485
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0.4041
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11.34
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11.38
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(0.50-13)
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12.3850
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12.6619
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11.2649
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11.3919
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10.2641
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9/16-12
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0.5495
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0.5609
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0.5016
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0.5068
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0.4587
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12.80
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12.84
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(0.5625-12)
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13.9573
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14.2469
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12.7406
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12.8727
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11.6510
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5/8-11
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0.6113
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0.6234
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0.5589
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0.5644
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0.5119
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14.27
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14.32
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(0.625-11)
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15.5270
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15.8344
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14.1961
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14.3358
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13.0023
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3/4-10
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0.7353
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0.7482
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0.6773
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0.6832
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0.6255
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17.28
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17.33
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(0.750-10)
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18.6766
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19.0043
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17.2034
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17.3533
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15.8877
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7/8-9
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0.8592
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0.8731
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0.7946
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0.8009
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0.7368
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20.27
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20.32
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(0.875-9)
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21.8237
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22.1767
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20.1828
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20.3429
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18.7147
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1"-8
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0.9830
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0.9980
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0.9100
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0.9168
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0.8446
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23.22
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23.27
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(1.000-8)
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24.9682
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25.3492
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23.1140
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23.2867
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21.4528
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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。
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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)
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