1、Errata MARCH 1997 to ASME Bl.15-1995 Unified Inch Screw Threads (UNJ Thread Form) The Errata corrections listed below and appearing herein apply to ASME B 1.15-1 995, Unified Inch Screw Threads (UNJ Thread Form). Corrections are incorporated directly into the affected pages and are indicated by a ma
2、rgin note, (E). The pages show the corrections given below. The pages not listed are the reverse sides of the listed pages and contain no changes. Page Location Change I 1.1 In fourth line. 0.600 changed to 0.060 4 Fig. 2 (I) Dl rnax. changed to D2 max. (2) Dl min. = D2 bsc changed to D2 min. = D2 b
3、sc (3) TD1/2 changed to TD212 5 Fig. 3 (I) dl max. = dl bsc changed to d2 max. = d2 bsc (2) dl min. changed to d2 min. (3) Td112 changed to Td212 (4) In General Note. “(See para. 5.3)“ changed to read: “(See para. 2.3)“ Fig. 4 Sentence added to Note (I) reading: “X equal or greater than 0.1501 1 P.“
4、 In fourth line, “length“ changed to read: “lengths“ In second line, delete (7) In second Example, fourth line, Lead tolerance of 0.009 . in. changed to 0.0009 in. In Example, fourth line, 0.009 changed to 0.0009 Under MINOR DIAMETER: (I) “dl basic minor diameter“ changed to “dl bsc basic minor diam
5、eter“ (2) “dl maximum minor diameter“ changed to “dl max maximum minor diameter“ THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS 345 East 47th Street, New York, NY 10017 (El 1.1 Scope UNIFIED INCH SCREW THREADS (UNJ THREAD FORM) SECTION 1 GENERAL 1 This Standard establishesthe basic triangular pro- fil
6、e for the UNJ thread form, provides a system of designations, lists the standard series of diameter- pitch combinations for diameters from 0.060 to 6.000 in., and specifies limiting dimensions and tolerances. It specifies the characteristics of the UNJ inch series of threads having 0.1501 1P to 0.18
7、042P designed ra- dius at the root of the external thread, and also having the minor diameter of the external and internal threads increased above the ASME B1.l UN and UNR thread forms to accommodate the external thread maximum root radius. 1 1.2 Field of Application The UNJ screw thread is designed
8、 for aerospace inch threaded parts, or for use on other highly stressed applications requiring high fatigue strength. For aero- space applications, only Classes 3A and 3B should be used. 1.4 Federal Government Use When this Standard is approved by the Department of Defense and federal agencies and i
9、s incorporated into FED-STD-H28/4, Screw Thread Standards for Federal Services, Section 4, the use of this Standard by the federal government is subject to all the re- quirements and limitations of FED-STD-H28/4. 1.5 References The latest issues of the following documents form a part of this Standar
10、d to the extent specified herein. American National Standards ASME B1.l, Unified Inch Screw Threads (UN and UNR Thread Form) ASME B1.3M, Screw Thread Gaging Systems for Dimensional Acceptability ANSI/ASME B1.7M, Nomenclature, Definitions, and Letter Symbols for Screw Threads ASME B1.23, Gages and Ga
11、ging for Unified Inch J Series Screw Threads 1.3 Assembly ASME B1.30M, Screw Threads - Standard Prac- Threads conforming to the UN profile (ASME B1 tice for Calculating and Rounding Dimensions - - and the UNJ profile are not interchangeable because of possible interference between the UNJ external I
12、 thread minor diameter and the UN internal thread minor diameter. However, the UNJ internal thread Proposed ASME Standard under development by The Amer- will assemble with the UN external thread. ican Society of Mechanical Engineers. UNIFIED INCH SCREW THREADS (UNJ THREAD FORM) SECTION 2 PROFILE OF
13、THREAD 2.1 Basic Profile The basic profile is the theoretical profile corre- I sponding to the basic dimensions of the thread major diameter, pitch diameter, and minor diameter. Profile applies to an axial plane. The basic profile is shown in Fig. 1. 2.2 Basic Thread Profile Symbols The symbols used
14、 in the basic profile shown in Fig. 1 represent the following: D bsc = basic major diameter of internal thread D2 bsc = basic pitch diameter of internal thread Dl bsc = basic minor diameter of internal thread d bsc = basic major diameter of external thread d2 bsc = basic pitch diameter of external t
15、hread dl bsc = basic minor diameter of external thread H = height of fundamental triangle P = pitch Appendix A provides a complete list of symbols applicable to the UNJ thread form. 2.3 Design Profiles The design profile for the internal thread at max- imum-material conditions is the same as the bas
16、ic profile, except in practice, the root is cleared above the basic major diameter, D bsc. See Fig. 2. The design profile for the external thread at max- imum-material condition for Class 3A is the basic profile with a radiused minor diameter tangent to the flanks for the upper limit profile. For Cl
17、ass 2A, an allowance is applied to the basic profile. The external thread crest may be flat, partially or corner rounded, tangent to the 0.125P flat. See Fig. 3. 2.4 Root Radius of the Thread 2.4.1 Internal Thread. For internal threads, the profile of the actual root of the thread shall at no point
18、be below the basic profile. No root radius is specified. 2.4.2 External Thread. For external threads, the profile of the actual root of the thread shall lie within the root radius tolerance zone shown in Fig. 4. The limit dimensions of the root radius R as shown in Fig. 4 and their values are specif
19、ied in Table 4. The profile shall be a continuous smoothly blended nonreversing curve, no part of which shall have a radius of less than 0.15011P and which is tangent to the thread flanks at not less than 0.56258 basic thread depth. The profile may comprise tangent flank circular arcs that are tange
20、nt to the flanks and a flat at the minor diameter provided that the minor diameter, d3, is within the zone established in Fig. 4. 2.4.3 Incomplete Threads. Unless otherwise specified, the runout threads on externally threaded parts shall be no less than 1, nor more than 2 pitches in length. The thre
21、ads shall run-out 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. UNIFIED INCH SCREW THREADS (UNJ THREAD FORM) FIG. 1 BASIC PROFILE (El FIG. 2 INTERNAL UNJ THREAD DESIGN PROFILE AND TOLERANCES UNIF
22、IED INCH SCREW THREADS (UNJ THREAD FORM) FIG. 3 EXTERNAL UNJ THREAD DESIGN PROFILE AND TOLERANCES Basic limit profile Maximum material limit I -Basic UNJ profile . . I- - 2 R max. = 0.18042P z 5 m o rn 0 5 (XI 0 2 CV 0 oz, R rnin. = 0.15011P I Lower limit INote rofile (“I 3 f NOTES: (1) Optional pro
23、file comprising two circular arcs IX) tangent to the flanks and flat at the root. X equal or greater than 0.15011P. (2) Min. truncation (3) Max. truncation (4) Tangent flank radii (minor dia.) FIG. 4 ROOT RADIUS OF EXTERNAL THREAD UNIFIED INCH SCREW THREADS (UNJ THREAD FORM) SECTION 4 THREAD CHARACT
24、ERISTICS (E) 4.1 Length of Thread Engagement, LE Tolerances specified in Table 5 are based on a length of engagement equal to the basic major diameter for the UNJC, UNJF, and 8-UNJ series and are appli- cable for lengths of engagement up to 1.5 diameters; and a length of engagement of 9 pitches for
25、the UN- JEF, lZUNJ, and 16-UNJ series, and are applicable for lengths of engagement of 5 to 15 pitches. For lengths of engagement over 1.5 (to and in- cluding 3 diameters) or over 15 (to and including 30 pitches), the pitch diameter tolerances are 1.25 times the tabulated values. For lengths of enga
26、gement over 3 diameters or 30 pitches, the pitch diameter toler- ances are 1.5 times the tabulated values. In addition to increasing pitch diameter tolerances for long lengths of engagement, maximum-material gages (GO) used for acceptance shall be equal in length to the design length of engagement.
27、4.2 Tolerance System The system of tolerances and allowances is based on ASME B1.l inch screw thread system of tolerance classes. Tolerances and allowances are applied plus for internal threads and minus for external threads. I (El 4.3 Limits of Size The basic profile dimensions are given in Table 1
28、. The profile dimensions and tolerances shown in Figs. 2 and 3 and their values for the standard series are specified in Table 5. For special threads for which there are no tabulated values, use the formulas in paras. 4.3.1 through 4.3.4, together with the tolerance table in Appendix B. Constants fo
29、r the special thread formulas are given in Table 3. NOTE: The dimensions and tolerances listed in Table 5 have been calculated and rounded to the procedures specified in ASME B1.30. As a consequence, a few of the values listed vary from 0.0001 in. to 0.0002 in. from listed values in previously issue
30、d standards for UN and UNJ inch threads. 4.3.1 External Threads - Class 3A d max.=d bsc dmin.=dmax.-Td 7d = 0.060 d2 ma. = d max. - 0.649519P see Table 31 d2 min. = d2 ma. - Td2 Td2=0.750 (0.15 -+0.0015 +0.015 ) NOTE: Figures within parentheses are rounded to six decimal places before multiplying by
31、 0.750. d3 ma. = d2 max. - 0.50518P see Table 31 d3 min. = d2 min. - 0.56580P see Table 31 Td3 = d3 max. - d, min. R max. = O.18042P see Table 41 R min. = 0.1501 1P see Table 41 4.3.2 Internal Threads - Class 3B D min. = D bsc D ma. = D2 max. +0.79386P see Table 31 D2 min. = D bsc - 0.6495 19P see T
32、able 31 D2 max. = D2 min. + TD, TD2=0.975 (0.0015 +0.0015 lead and angle control required. No lead and angle tolerances were specified nor do default values appear in Tables 6 and 7. Values are calculated as follows: Lead tolerance= 0.57735 x 0.5 Td2 Pitch diameter tolerance Td2= 0.0050 Lead toleran
33、ce=0.57735 x 0.5 x 0.0050=0.0014 in. Angle tolerance (for coarser than 32 tpi) = 30 + (1 375 x tpi) Angle tolerance= 30+ (1.875 x 8.5) =45.94 minutes = 45 minutes when rounded to nearest 5 minutes EXAMPLE: (E) 0.500-41 UNJS-3B; lead and angle control required. Lead tolerance=0.57735 x0.5 Td2 Pitch d
34、iameter tolerance Td2 = 0.0031 Lead tolerance= 0.57735 x 0.5 x 0.0031 = 0.0009 in. Angle tolerance (for finer than 32 tpi) = 62 + (0.775 x tpi) Angle tolerance = 62 + (0.775 x 41) = 93.78 minutes = 1 degree and 35 minutes when rounded to near- est 5 minutes (c) If lead and angle tolerances are speci
35、fied as a NOTE: TD, may not exceed 0.259809P or be less than 0.135315P. pitch diameter equivalent in terms of pitch diameter For threads with 12 threads per inch or coarser: tolerance, tolerances in accordance with para. 4.4.2(a) or para. 4.4.2(b) may be adjusted proportionately TD, =0.120P using 0.
36、5 times pitch diameter tolerance as a basis. UNIFIED INCH SCREW THREADS (UNJ THREAD FORM) (El EXAMPLE: 0.5000-20 UNJF-3A (22s); lead and angle control required - 0.4 PD tolerance. From Table 6, allowable lead variation is 0.0009 in. This would be adjusted to 0.4m.5 times 0.0009 which is 0.0007 in. F
37、rom Table 7, allowable angle variation is 1 degree 10 minutes or 70 minutes. This would be adjusted to 0.4/0.5 times 70 which is 56 minutes or 55 minutes when rounded. (d) For requirements of (a) and (b) above, lead variation values tabulated or calculated are the max- imum variations from specified
38、 lead between any two points not farther apart than the length of the max- imum-material (GO) thread gage. Flank angle vari- ation values are maximum variations from the basic 30 deg angle between thread flanks and perpendicu- lars to the thread axis. (e) Allowable variations in lead and flank angle
39、s are maximum values. Maximum variation in these and pitch diameter tolerance cannot be taken simul- taneously. 4.4.3 Runout of Major Diameter and Minor Di- ameter to Pitch Cylinders. When measurement is specified, maximum circular runout shall be limited to a full indicator movement equal to the pi
40、tch di- ameter tolerance. 4.4.4 Taper. If the pitch cylinder is conical, the difference in pitch diameters between the ends of the thread are an indication of taper. When measurement is required, it shall be specified. If not specified, al- lowable taper is no greater than the pitch diameter toleran
41、ce. . (1) Threads Per in., n 80 72 64 56 48 44 40 36 32 28 24 20 18 16 14 13 12 11 10 9 8 7 6 5 4.5 4 R - h) (21 Pitch 1 p=- n 0.012500 0.01 3889 0.01 5625 0.017857 0.020833 0.022727 0.025000 0.027778 0.031250 0.035714 0.041667 0.050000 0.055556 0.062500 0.071429 0.076923 0.083333 0.090909 0.1 00000
42、 0.111111 0.125000 0.142857 0.1 66667 0.200000 0.222222 0.250000 TABLE 1 BASIC (31 Pitch Line 0.5 P 0.006250 0.006944 0.007812 0.008928 0.01 041 6 0.01 1363 0.01 2500 0.01 3889 0.015625 0.01 7857 0.020833 0.025000 0.027778 0.031250 0.035714 0.038461 0.041 666 0.045454 0.050000 0.055555 0.062500 0.07
43、1428 0.083333 0.1 00000 0.111111 0.1 25000 PROFILE (61 Height of Sharp V Thread H 0.866025 P 0.01 0825 0.01 2028 0.01 3532 0.01 5465 0.018042 0.01 9682 0.021651 0.024056 0.027063 0.030929 0.036084 0.043301 0.0481 13 0.054127 0.061 859 0.066617 0.072169 0.078730 0.086603 0.096225 0.108253 0.123718 0.
44、1 44338 0.173205 0.1 92450 0.21 6506 (41 Flat at Internal Thread Crest 0.3125 P 0.00391 0.00434 0.00488 0.00558 0.00651 0.0071 0 0.00781 0.00868 0.00977 0.01 116 0.01302 0.01 562 0.01 736 0.01953 0.02232 0.02404 0.02604 0.02841 0.03125 0.03472 0.03906 0.04464 0.05208 0.06250 0.06944 0.0781 2 (51 Fla
45、t at Internal Thread Root and External Thread Crest 0.125 P 0.001 56 0.001 74 0.001 95 0.00223 0.00260 0.00284 0.00312 0.00347 0.00391 0.00446 0.00521 0.00625 0.00694 0.00781 0.00893 0.00962 0.01042 0.01 136 0.01 250 0.01 389 0.01 562 0.01786 0.02083 0.02500 0.02778 0.03125 DIMENSIONS (7) Height of
46、Internal Thread and Depth of Thread Engagement 0.5625 H= 0.487139 P 0.00609 0.00677 0.00761 0.00870 0.01015 0.01 107 0.01218 0.01353 0.01 522 0.01740 0.02030 0.02436 0.02706 0.03045 0.03480 0.03747 0.04059 0.04429 0.04871 0.0541 3 0.06089 0.06959 0.081 19 0.09743 0.10825 0.12178 5 2 4 Y A w w fn C ,
47、z 9 0“ 1 e p z Cn 2 nxm rn z 2 nW B F 3 z (8) Addendum of External Thread 0.375 H= 0.324760 P 0.00406 0.00451 0.00507 0.00580 0.00677 0.00738 0.0081 2 0.00902 0.01015 0.01 160 0.01353 0.01624 0.01 804 0.02030 0.02320 0.02498 0.02706 0.02952 0.03248 0.03608 0.04059 0.04639 0.05413 0.06495 0.0721 7 0.
48、081 19 (9) Truncation of Internal Thread Crest 0.3125 H= 0.270633 P 0.00338 0.00376 0.00423 0.00083 0.00564 0.0061 5 0.00677 0.00752 0.00846 0.00967 0.01 128 0.01353 0.01 504 0.01691 0.01 933 0.02082 0.02255 0.02460 0.02706 0.03007 0.03383 0.03866 0.04510 0.0541 3 0.0601 4 0.06766 no) Truncation of
49、Internal Thread Root and External Thread Crest 0.125 H= 0.108253 P 0.001 35 0.001 50 0.00169 0.001 93 0.00226 0.00246 0.00271 0.00301 0.00338 0.00387 0.00451 0.00541 0.00601 0.00677 0.00773 0.00833 0.00902 0.00984 0.01 083 0.01203 0.01 353 0.01546 0.01 804 0.021 65 0.02406 0.02706 (111 Half Addendum of External Thread. REFERENCE ONLY 0.1875 H= 0.16238 P 0.00203 0.00226 0.00254 0.00290 0.00338 0.00369 0.00406 0.00451 0.00507 0.00580 0.00677 0.00812 0.00902 0.01 01 5 0.01 160 0.01249 0.01353 0.01476 0.01 624 0.01804 0.02030 0.02320 0.02706 0.03248 0.03608 0.04059 APPE
