ASME B1.13M-2001 pdf download

ASME B1.13M-2001 pdf download.METRIC SCREWTHREADS: M PROFLE .
1.6 General Symbols The general symbols used to describe the metric screw thread forms are shown in Table 1. 1.7 Units All dimensions and all values in the formulas are expressed in millimeters unless otherwise noted. Values in terms of sharp vee-thread height (height of fundamen- tal triangle), H, are used to be consistent with IS0 Standards, but actual formulations and calculations are based on values of pitch, P. See Table 2. 1.8 Federal Government Use When this Standard is approved by the Department of Defense and Federal Agencies and is incorporated into FED-STD-H28/21, Screw Thread Standards for Federal Services Section 21, the use of this Standard by the Federal Government is subject to all the require- ments and limitations of FED-STD-H28/21. 2 TERMINOLOGY 2.1 Definitions allowance: the prescribed difference between the de- sign (maximum material) size and the basic size. It is numerically equal to the absolute value of the IS0 term fundamental deviation. NOTE: Allowance is not an IS0 metric screw thread term but will be used together with the IS0 term fundamental deviation. basic thread profle: the cyclic outline, in an axial plane, of the permanently established boundary between the provinces of the external and internal threads. All deviations are with respect to this boundary. See Figs. 1 and 4. bolt thread (exteml thread): the term used in IS0 metric thread standards to describe all extemal threads. All symbols associated with external threads are desig- nated with lowercase letters. This Standard will refer only to external threads in accordance with U.S. practice.
crest diameter: the major diameter of an external thread and the minor diameter of an internal thread. design prufiles: the maximum material profiles permit- ted for external and internal threads for a specified tolerance class. See Figs. 2 and 3. deviation: in IS0 usage, the algebraic difference be- tween a size (actual, maximum, minimum, etc.) and the corresponding basic size. The term deviation does not necessady indicate an error. fit: the general term used to signify range of tightness or looseness that results from application of a specific combination of allowances and tolerances in mating parts. fundamental deviation: for standard threads, the devia- tion (upper or lower) closer to the basic size. It is the upper deviation, es, for an external thread and the lower deviation, EI, for an internal thread. See Fig. 4; also see allowance and tolerance position. NOTE: The U.S. term allowance will be used as a primary term in this Standard, where applicable. lower deviation: the algebraic difference between the minimum limit of size and the corresponding basic size. See para. 5.1.4. nut thread (internul thread): a term used in IS0 memc thread standards to describe all internal threads. All symbols associated with internal threads are desig- nated with uppercase letters. This Standard will refer to the term internal thread in accordance with U.S. practice.
tolerance: the total amount of variation permitted for the size of a dimension. It is the difference between the maximum limit of size and the minimum limit of size (i.e., algebraical difference between the upper deviation and the lower deviation). The tolerance is an absolute value without sign. Tolerance for threads is applied to the design size in the direction of minimum material. Therefore, tolerances are applied as negative values on external threads and as positive values on internal threads. tolerance class: the combination of a tolerance posi- tion with a tolerance grade. It specifies the allowance (fundamental deviation) and tolerance for the pitch and major diameters of external threads and the pitch and minor diameters of internal threads. tolerance grade: a numerical symbol that designates the tolerances of crest diameters and pitch diameters applied to the design profiles. tolerance position: a letter symbol that designates the position of the tolerance zone in relation to the basic size. This position provides the allowance (fundamental deviation). upper deviation: the algebraic difference between the maximum limit of size and the corresponding basic size. See para. 5.1.3. 3 SCREW THREAD PROFILE 3.1 Basic M Thread Profile The basic M thread profile also known as the IS0 68-1 Basic Profile for metric screw threads is depicted in Fig. 1 with the associated dimensions listed in Table 2. 3.2 Design M Profiles 3.2.1 Internal Thread. The design M profile for the internal thread at the no allowance maximum material condition is the basic IS0 68-1 profile. See Fig. 2 and thread data in Table 2. 3.2.2 External Thread. The design M profile for the external thread at the no allowance maximum material condition is the basic IS0 68-1 profile except where a rounded root is required. For the standard 0.125P min. radius, the IS0 68-1 profile is modified at the root with a 0.177838 truncation blending into two arcs with radii of 0.125P tangent to the thread flanks. See Fig. 3 and thread data in Table 2.