most threads are single-start, forming a single helix here the pitch equals the lead.
most common is right-handed thread, RH, considered default when not specified explicitly LH or left stands for left-handed thread, usually used where direction of rotation would tend to unscrew RH.
pipe threads often exist in straight and tapered forms - BSPP vs BSPT/BSPTr (G vs R), NPS vs NPT.
flat crest/root are more friendly to manufacture, cheaper, the edges can accommodate some rounding of the tools by wear.
flat crest, round root for UNJ and MJ forms, "flavors" of standards.
flat for metric and US and for translation screws, for truncated Whitworth for fasteners the root is usually slightly round or radiused to avoid stress concentration.
crest/root forms (flat and how wide, or round and with what radius).
for translation screws, 29° for ASME, 30° for trapezoid, 60° for truncated 60°.
typically 60° for metric and US series, 55° for Whitworth, 47.5° for BA.
Thread form defines the shape of the thread: UNC,UNF,UNEF,UNS: like metric, but dia/pitch imperialīSF: British Standard Fine, like Whitworth but finer pitchīSC: British Standard Cycle, CEI Thread angle 60°, fine pitch, 1/4" and above all at 26 tpi, or 20 tpi ("CEI20")īSP,G,R: British Standard Pipe, like Whitworth but for pipe diameters, dia for inner pipe dia! TABLE OF DIMENSIONS, STANDARDS AND EXAMPLES Conference for unification report, vol.73, small screws:
0 kommentar(er)
