美制UN系列螺纹标准.pdf

Machinerys Handbook 27th Edition UNIFIED SCREW THREADS 1735 Table 2. Diameter-Pitch Combinations for Standard Series of Threads (UN/UNR) Basic Threads per Inch Sizesa Major Series with Graded Pitches Series with Uniform (Constant) Pitches No. or Dia. Coarse Fineb Extra finec Inches Inches UNC UNF UNEF 4-UN 6-UN 8-UN 12-UN 16-UN 20-UN 28-UN 32-UN 0 0.0600 … 80 (1) 0.0730 64 72 Series designation shown indicates the UN thread form; however, the UNR 2 0.0860 56 64 thread form may be specified by substituting UNR in place of UN in all (3) 0.0990 48 56 designations for external threads. 4 0.1120 40 48 5 0.1250 40 44 … … … … … … … … … 6 0.1380 32 40 … … … … … … … … UNC 8 0.1640 32 36 … … … … … … … … UNC 10 0.1900 24 32 … … … … … … … … UNF (12) 0.2160 24 28 32 … … … … … … UNF UNEF 1 ⁄4 0.2500 20 28 32 … … … …