ASME B1.1:2019 pdf free download

ASME B1.1:2019 pdf free download.Unified Inch Screw Threads (UN, UNR, and UNJ Thread Forms).
2.3.1 Design ProfiLes of ExternaL Threads
2.3.1.1 UN and UNR. The design profiles of external uN and UNK screw threads are included in Figures 5 through 8. A fiat root contour Is specified for UN threads: however, it is permissible to provide for some threading tool crest wear. Therefore, a rounded root contour cleared beyond the 0.2500P flat width of the basic profile is optional. The rounded root also reduces the rate of threading tool crest wear and improves fatigue strength over that of a flat root thread,
(a) At the least material condition (LMC), the root form of the UNR external thread shall be a lull root radius of not less than 0.10825318P. At maximum material condition (MMC), the root form of the UNR external thread may be one of the following types:
(1) a lull root radius of not more than O.14433757P, which makes the point oltangency between the radius and the flanks at a point 054126581W below the basic major diameter (the equivalent of a 0.2500P width of flat).
(2) a rounded [onn” consisting Dl a combination oF flats and radii not less than 0.10825318P, as shown in Figures 7 and 8. When the root is the rounded form. the radii may exceed 0.14433757P so long as the point of tangency between the radii and the flanks Is no less than 0.54 126581W below the basic ma)or diameter (the equivalent of a 0.2500P width of flat).
(b) The design profiles of external UN and UNR screw threads have flat crests. However. in practice, product thread crests may be flat, partially rounded, or fully rounded. A rounded crest tangent at a 0,12500P flat is shown as an option in Figures 5 through 8.
2.3.1.2 UNJ. The design profile of the external UNI screw thread specifies that the actual root of the thread shall lie within the root radius tolerance zone shown In Figures 4 and 9. The limit dimensions of the root radius, r, are shown In Figures 10 and 11 and their values are specified In Table 2A. The profile shall be a continuous smoothly blended non-reversing curve, no part of which shall have a radius of less than 0.15011107P and which Is tangent to the thread flanks at not less than O.48713929P basic thread depth. The profile may comprise tangent flank circular arcs that are tangent to the flanks and a flat at the minor diameter provided that the minor diameter, d3., is within the zone established In Figures 10 and 11. Unless otherwise specified, the runout or incomplete LJNJ threads on externally threaded parts shall be no less than 1 pitch nor more than 2 pitches in length. The threads shall runout onto the shank without any abrupt change in cross-sectional area. The root radius shall be no less than the minimum radius of the full thread section.
2.3.2 Design ProfiLe of InternaL Threads. The design profiles of the internal UN and UNJ screw threads are included in Figures 2. 5 through 8, and 10 through 12 (there is no internal UNR screw thread).