1、 Intentionally left blank AN AMERICAN NATIONAL STANDARD STUB ACME SCREW THREADS ASME/ANSI B1.8-1988 (REVISION OF ANSI B1.8-1977) The American Society of Mechanical Engineers 345 East 47th Street, New York, N.Y. 1001 7 Date of Issuance: April 30,1988 This Standard will be revised when the Society app
2、roves the issuance of a new edition. There will. be no addenda or written interpretations of the requirements of this Standard issued to this edition. This code or standard was developed under procedures accredited as meeting the criteria for American National Standards. The Consensus Committee that
3、 approved the code or standard was balanced to assure that individuals from competent and concerned interests have had an opportunity to participate. The proposed code or standard was made available for public review and comment which provides an opportunity for additional public input from industry
4、, academia, regulatory agencies, and the public-at-large. ASME does not “approve,“ “rate,“ or “endorse“ any item, construction, proprietary device, or activity. ASME does not take any position with respect to the validity of any patent rights asserted in connection with any items mentioned in this d
5、ocument, and does not undertake to insure anyone utilizing a standard against liability for infringement of any applicable Letters Patent, nor assume any such liability. Users of a code or standard are expressly advised that determination of the validity of any such patent rights, and the risk of in
6、fringement of such rights, is entirely their own responsibility. Participation by federal agency representative(s1 or person(s) affiliated with industry is not to be interpreted as government or industry endorsement of this code or standard. ASME accepts responsibility for only those interpretations
7、 issued in accordance with governing ASME procedures and policies which preclude the issuance of interpretations by individual volunteers. No part of this document may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. Co
8、pyright 0 1988 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved Printed in U.S.A. FOREWORD (This Foreword is not part of ASMElANSl 61.8-1 988.) The Standards Committee on the Standardization and Unification of Screw Threads, B1, was organized in June 1921 with the Society of Autom
9、otive Engineers and the American Society of Mechanical Engineers as joint sponsors under the procedures of the American Standards Association (ASA), now the American National Standards Institute (ANSI). This Committee was reorganized in May 1929, and its work was divided among five sub- committees a
10、s follows: No. 1 - Scope and Arrangement of American Standard No. 2 - Terminology and Form Threads, Except Gages No. 3 - Special Threads and Twelve Pitch Series, Except Gages No. 4 - Acme Threads, Except Gages No. 5 - Screw Thread Gages National standardization of Acme screw threads in the United St
11、ates began in 1932 when Subcommittee No. 4 on Acme Threads of Sectional Committee B1 held its first meeting in New York. A report was presented on the types of Acme threads and the range of sizes and pitches in use in this country. It was prepared by C. W. Bettcher with the assistance of F. L. Woodc
12、ock. This report developed into a draft standard. When it was finally approved as an American Standard with the designation ASA B1.3-1941, it contained a section of introduc- tory notes and tables covering general purpose screws and general purpose nuts, basic di- mensions of general purpose Acme th
13、reads with special and standard pitches, basic dimensions of 29 deg. stub threads, measurements over three wires for Acme threads, basic dimensions of 60 deg. stub threads, and basic proportions for modified square threads. In December 1942, to meet the war emergency, the National Aircraft Standards
14、 Commit- tee of the Aeronautical Chamber of Commerce requested the ASA to consider establishing an American war standard for special Acme screw threads for use in aircraft construction. Recognizing the vital importance of aircraft production to the war effort, the ASA at once initiated this project
15、and organized a special committee to develop the standard. At the London Conference on the unification of screw threads held in the summer of 1944, it was proposed that a war standard on Stub Acme threads also be drawn up. Early in March 1945, therefore, the work on this proposed standard was begun
16、and a draft prepared as a result of the discussion with the British and Canadian experts at the Ottawa Conference in October 1945. This draft was dated March 1946 and was submitted to the ASA War Committee on Acme Threads and the ASA War Committee on Screw Threads in April 1946 for approval by lette
17、r ballot. However, a Stub Acme war standard was never issued. In April 1946, the Subcommittees of Standards Committee B1 were reorganized to in- clude the responsibility of the ASA War Committee. Subcommittee No. 2 on Acme and Stub Acme Threads revised the March 1946 draft on Stub Acme screw threads
18、 and on March 31, 1948, distributed the January 1948 draft to industry for criticism and comment. The final draft of the proposed standard on Stub Acme screw threads was completed in June 195 1 and was submitted to Sectional Committee B1 for letter ballot on September 17, 1951; it was approved with
19、minor amendments. Following approval by the sponsor 111 . organizations, the proposed standard was submitted to the ASA for approval and designa- tion as an American Standard. This was granted on May 7, 1952. The next revisions were approved by ANSI as American National Standards on May 14, 1973, an
20、d May 11, 1977, respectively. Revisions were minor. On September 2,1981, the B1 Committee was reorganized as an ASME Standards Com- mittee. The B1.8 Subcommittee developed this edition, which was subsequently approved by the ASME B1 Committee, submitted to ANSI, and adopted as an American National S
21、tandard on January 11, 1988. iv ASME STANDARDS COMMITTEE B1 Standardization and Unification of Screw Threads (The following is the roster of the Committee at the time of approval of this Standard.) OFFICERS D. J. Ernanuelli, Chairman H. W. Ellison, Vice Chairman C. E. Lynch, Secretary COMMITTEE PERS
22、ONNEL AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC. G. G. Gerber, McDonnell Douglas Corp., St. Louis, Missouri H. Borrrnan. Alternate, Sperry Defense Electronics, Great Neck, New York AMERICAN MEASURING TOOL MANUFACTURERS ASSOCIATION R. Dodge, Pennoyer-Dodge Co., Glendale, California C. W. Jatho
23、, Alternate, American Measuring Tool Manufacturers Association, Birmingham, Michigan AMERICAN PIPE FITTINGS ASSOCIATION W. C. Farrell, Jr., Stockham Valves and Fittings, Inc., Birmingham, Alabama DEFENSE INDUSTRIAL SUPPLY CENTER E. Schwartz, Defense Industrial Supply Center, Philadelphia, Pennsylvan
24、ia F. S. Ciccarone, Alternate, Defense Industrial Supply Center, Philadelphia, Pennsylvania ENGINE MANUFACTURERS ASSOCIATION G. A. Russ, Cummins Engine Co., Columbus, Indiana INDUSTRIAL FASTENERS INSTITUTE R. M. Harris, Bethlehem Steel Corp., Lebanon, Pennsylvania K. E. McCullough, SPS Technologies,
25、 Inc., Newton, Pennsylvania J. C. McMurray, Russell, Burdsall right-hand threads are assumed unless LH GAGES, SUCH AS THREAD SNAP is specified. GAGES, OR VARIABLE TYPE LIMIT AND Example 0.500-10 Stub Acme SIZE INDICATING THREADED GAGES FOR BOTH DIMENSIONAL CONFOR- MANCE AND IN-PROCESS CONTROL. Threa
26、d series Both GO and NOT GO gages, which represent the Number of threaddin. product limits or adequate gaging instruments for Nominal size thread elements, are necessary for the proper inspec- tion of Stub Acme threads. The dimensions of GO and NOT GO gages should be in accordance with the fol- lowi
27、ng principles: 1.750-0.250P-0.5L-Stub Acme-3G-LH (a) the GO gage should check simultaneously as Nominal size/ I/ many effectively elements check as but possible, one element; and a NOT GO gage can Pitch (b) permissible variations in the gages be kept Example Lead, double-start thread Stub Acme threa
28、d form within the extreme product limits. Class 3G (see para. 1.8) Left-hand 2 GAGES FOR STUB ACME SCREW THREADS SPECIAL NO TE: Work is in progress to write an ASME/ANSI B1 standard for screw thread gaging systems suitable for determining the acceptability of Acme/Stub Acme screw threads on external
29、 and internal threaded prod- ucts. The draft of ASME B1.24, Gages and Gaging for General Purpose Acme, Centralizing Acme, and Stub Acme Threads, uses the guidelines as noted in ANSI/ ASME B1.3M, which have been established for uni- form inch and metric screw threads. This standard will establish the
30、 criteria for product screw thread acceptance when a specified gaging sys- tem is used for both in-process control and final di- mensional conformance. The format for this standard will follow that already established by ANWASME B1.3M, Unified Inch and Metric Screw Threads. A screw thread gaging sys
31、tem for external/internal Acme/Stub Acme screw threads comprises a listing of those screw thread characteristics that must be in- spected for each specified system and the gage, gages, or gaging systems which shall be used when inspecting those characteristics. In the interim, until this standard ha
32、s been com- pleted and released, the following clarifying statement shall apply. 2.1 Gage Tolerances Tolerances for the thread elements of GO and NOT GO gages for Stub Acme threads are given in Table 9. (a) Tolerances on Pitch Diameter. The pitch diameter tolerances for gages for external and intern
33、al threads are given in Table 9, column 2. (b) Tolerances on Major and Minor Diameters. The major and minor diameter tolerances for Stub Acme thread gages are given in Table 9, column 3. (c) Tolerances on Lead. The variation in lead of all Stub Acme thread gages shall not exceed 0.0003 in. be- tween
34、 any two threads not farther apart than l in. However, the cumulative variation in lead shall not exceed the following: (I) 0.0004 in., for gages with a length over 1 in. to 3 in., inclusive; (2) 0.0005 in., for gages with a length over 3 in. to 5 in., inclusive; (3) 0.0007 in., for gages with a len
35、gth over 5 in. to 10 in., inclusive. For multiple threads, the cumulative tolerance for any length of gage shall be obtained by multiplying by 1.5 the above tolerance applicable to that length. (d) Tolerances on Angle of Gage Threads. The tol- erances on angle of thread, as specified in Table 9, col
36、umn 4 for the various pitches, are tolerances on one-half of the included angle. This ensures that the bisector of the included angle will be perpendicular to the axis of the thread within proper limits. The 5 ASME/ANSI 61.8-1 988 STUB ACME SCREW THREADS deviation from the true thread form caused by
37、 such ir- regularities as convex or concave flanks of the thread, or slight projections on the thread form, should not exceed the tolerances permitted on the angle of thread. 2.1.1 Gages for External Threads (a) GO Thread Ring, Thread Snap, or Indicating Gage (I) Major Diameter. The major diameter o
38、f the GO thread ring, thread snap, or indicating gage shall clear a diameter greater than the maximum major diameter of the external thread by 0.01 in. (2) Pitch Diameter. The size of a GO thread gage is determined by its fit or setting on the maximum- material-limit thread setting plug gage. (3) Mi
39、nor Diameter. The minor diameter shall be the same as the maximum minor diameter of the exter- nal thread plus 0.005 in. for pitches finer than 10 threaddin., and plus 0.010 in. for 10 threaddin. and coarser. The tolerance shall be minus. (4) Length. The length shall approximate the length of engage
40、ment, but shall not exceed the length specified in Table 10, column 3. (b) Maximum-Material-Limit Thread Setting Plug for GO Thread Ring, Thread Snap, or Indicating Gages (I) Major Diameter. The major diameter of the maximum-material-limit thread setting plug shall be the same as the maximum major d
41、iameter of the exter- nal thread. The gage tolerance shall be plus. (2) Pitch Diameter. The pitch diameter shall be the same as the maximum pitch diameter of the exter- nal thread, except when modified in accordance with Table 10. The tolerance shall be minus. (3) MinorDiameter. The minor diameter s
42、hall be cleared below the minimum minor diameter of the GO thread ring, thread snap, or indicating gage. (4) Length. The length should approximate the length of the GO gage. See ASME/ANSI B47.1. (c) NOT GO Thread Ring, Thread Snap, or Indica- ting Gage (I) Major Diameter. The major diameter of the N
43、OT GO thread ring, thread snap, or indicating gage shall clear a diameter greater than the maximum major diameter of the external thread by 0.010 in. (2) Pitch Diameter. The size of a NOT GO thread gage shall be determined by its fit or setting on the minimum-material-limit thread setting plug gage.
44、 (3) MinorDiameter. The minor diameter shall be the basic minor diameter of the internal thread plus 0.15 with tolerance plus. If this results in a minor diameter greater than the gage P.D. size, the gage P.D. size shall be used for the minor diameter with the tolerance minus. (4) Length. The length
45、 shall approximate three pitches except that, for multiple threads, the length shall provide at least one full turn of thread (see para. 2.1.4). (d) Minimum-Material Thread Setting Plug for NOT GO Thread Gage (I) Major Diameter. The major diameter of the minimum-material-limit thread setting plug sh
46、all be the same as the maximum major diameter of the exter- nal thread. The gage tolerance shall be plus. (2) Pitch Diameter. The pitch diameter shall be the same as the minimum pitch diameter of the exter- nal thread with the tolerance plus. (3) MinorDiameter. The minor diameter shall be cleared be
47、low the minimum minor diameter of the NOT GO thread gage. (4) Length. The length shall be at least equal to the length of the NOT GO thread gage (see ASME/ ANSI B47.1). (e) GO Plain Ring, Snap, or Indicating Gage for Major Diameter. The diameter of the GO plain ring gage or the gaging dimension of t
48、he GO plain snap gage shall be the same as the maximum major diame- ter of the external thread. Tolerances are shown in Table 8 and shall be minus. (f) NOT GO Plain Ring, Snap, or Indicating Gage for Major Diameter. The gaging dimension of the NOT GO plain snap gage shall be the same as the mini- mu
49、m major diameter of the external thread. Toler- ances are shown in Table 8 and shall be plus. 2.1.2 Gages for Internal Thread (a) GO Thread Plug or Indicating Gage (I) Major Diameter. The major diameter of the GO thread.plug gage or indicating gage shall be equal to the minimum major diameter of the internal thread minus 0.005 in. for pitches finer than 10 threaddin., and minus 0.010 in. for 10 threaddin. and coarser. The tolerance shall be plus. (2) Pitch Diameter. The pitch diameter shall be equal to the mini
