1, nominal diameter (external threads of the nominal large diameter) and pitch is not calculated, but the standard provisions down to them as the base according to a certain formula so as to determine some other parameters.
(1) American thread (uniform standard thread)?
Tooth depth = ?0.6495*(25.4/teeth per inch); ? (tooth angle 60 degrees)?3/4-10UNC-2A?(UNC coarse thread)(UNF fine thread)?
(1A 2A 3A external teeth tolerance fit class)? (1B 2B 3B internal teeth tolerance class)?
UNC American Standard Coarse threads: 3/4 inch OD, 10 teeth per inch; Class 2 tolerance for external threads?
(2) Pipe Threads (Imperial PT)?
Tooth depth=?0.6403*(25.4/number of teeth per inch); (tooth angle 55 degrees)?
PT 3/4-14 (Taper Pipe Thread) Taper Pipe Thread: Taper ratio 1/16?3/4 inch pipe; 14 teeth per inch.
(3) Pipe Threads? (PS straight thread)(PF fine thread)?
Tooth depth=?0.6403*(25.4/number of teeth per inch); (tooth angle 55 degrees)?
PS 3/4-14 (straight pipe thread)?PF1 1/8-16 (straight pipe thread)
2. In terms of common triangular thread. The so-called British thread and British BS Whitworth thread (55 ° tooth angle) and the United States standard inch unit based on the uniform thread UN series (60 ° tooth angle) two kinds of points.
Theoretically, the metric system (metric), unified thread of the original triangle height H for 0.866p (p - pitch), Wyeth 0.9605p; design tooth height of 5/8H, Wyeth 2/3H; the theoretical median diameter hypothetical circle in the design of the tooth under the top of 3/8H.
In fact, due to the difference between the accuracy of the standard provisions and the reality of the production accuracy differences, is not consistent with the design of the tooth shape, you only familiar with the relevant commonly used standards, in order to compare the data to quickly judge.
3. The basic tooth shape and basic size of conical pipe thread: