美国联邦螺丝标准手册FED-STD-H28（可编辑）

美国联邦螺丝标准手册 FED-STD-H28
FED-STD-H28 31 March 1978 Superseding NBS Handbook H28PART I 1969 PART II 1957 PART III 1957 FEDERAL STANDARDSCREW-THREAD STANDARDS FOR FEDERAL SERVICES
This standard was approved by the Commissioner, Federal Supply Service,
General Services Administration, for the use of all Federal agenciesU.S. GOVERNMENT PRINTING OFFICE : 1978 - 261-423/1075 Orders for this publication are to be placed with General Services Administration, acting as an agent for the Superintendent of Documents.
Single copies of this standard are available at the GSA Business Service
Centers in Boston, New York, Philadelphia, Atlanta, Chicago, Kansas City, MO,
Fort Worth, Houston, Denver, San Francisco, Los Angeles, and Seattle, WA. or
from the General Services Administration, Specification and Consumer Information Distribution Branch, Bldg. 197, Washington Navy Yard, Washington,
DC 20407Price 2.50 cents each FSC THDS
//.FED-STD-H28
31 March 1978 INFORMATION SHEET ON FEDERAL STANDARDS This Federal
Standard is issued in loose leaf form to permit the insertion or removal of new or revised pages and sections All Users of Federal Standards should keep them up to date by inserting
revised or new pages as issued and removing superseded and cancelled pages New and revised pages will be issued under Change Notices which will be
numbered consecutively and will bear the date of issuanceChange Notices
should be retained and filed in front of the Standard until such time as they
are superseded by a reissue of the entire StandardNOTICE From 1939, the Interdepartmental Screw-Thread Committee ISTC, under the Chairmanship of the National Bureau of Standards NBS, Department of Commerce had developed and published NBS Handbook H28, Screw-Thread Standards
for Federal Services Section 487 of Title 40 of the U.S. Code states that the authority for
development of Federal Standards for procurement purposes rests with the
General Services Administration GSA In November 1976, the ISTC was terminated, and the General Services
Administration GSA accepted the responsibility for NBS Handbook H28 and
agreed to convert it and maintain it as a Federal Standard The standards which had been published as NBS Handbook H28, Part 1, Part
II and Part III will now be promulgated as a fully coordinated FED-STD-H28,
maintaining the existing sections and identifying them with slant lines. For
example, NBS Handbook H28, Part 1, Section 3 will be detailed standard FED-S-TD-H28/3 which must be procured individually.
Military Custodians Preparing Activity
ARMY - AR DLA-IS
NAVY - AS
AIR FORCE - 11 Project No. THDS-0003
Civil Agency Coordinating Activity
ACOFPIMSF
AFSFRANBS
BPAFSSPCD
FHWJFKRDS
FISLRCTCS ii
//.FED-STD-H28 31 March 1978 CONTENTS Page
1 PURPOSE AND SCOPE1
1.1PURPOSE1
1.2SCOPE. 1
2 APPLICATION. 1
3 DETAILED STANDARDS 1
4 APPENDIX. 2
5 COMPARABLE INDUSTRY STANDARDS. 3 The text of this section is reprinted from the NBS HANDBOOK H28 with? minor editorial
correctionsPages 44, 48, 55 thru 63, 65 thru 68, 71, 72, 73, 74. 75 and 80 thru 86 contain corrections indicated by an asteriskReorganization of the document from NBS HANDBOOK H28 to FED-STD-H28creates an editorial inconvenience, when maintaining continuity of crossreferences amongst the pages, paragraphs, tables and figures of the? different sectionsFor this standard individual sections will benumbered sequentially starting with 1 oneIf the reprinted text? refers to another page, such as Page 6.3, this will be understood to mean? section 6 page 3All figures and tables will maintain the establisheddesignations, prefixed with the section; e.g. Table 3.1 and Figure 2.5 to? identify their location in this standardAll appendices will be incorporated in the basic document FED-STD-H28 with other general information and will continue to be identified with the prefix A iii
//0>. FED-STD-H2831 March 19781PURPOSE AND SCOPE
1.1 Purpose.
This standard establishes complete dimensional data requirements for screw
threads including, as necessary, recommendations on gages, dies and taps and
other items associated with the purchase/use of interchangeable threaded
parts by Federal Government Agencies. So far as practicable, these data are
intended to conform to generally accepted commercial practice, although
certain special requirements of the Federal Services necessitate the inclusion
of some standards not generally applicable outside the Government. References
are cited throughout the text to the standards promulgated by The American
Standards Association ASA and the United States of America Standards Institute USASI, now called The American National Standards Institute ANSI
and to such other published standards as are in agreement with the specifications herein.
1.2 Scope.
This standard includes the basic dimensional requirements for assembly,
interchangeability, tensile strength, shear strength, fatigue strength and
installation and removal torque of threaded products. Specific requirements
for particular Screw-Thread Standards are covered by the Detail Standards
see Para 3. Supplements to the Detail Standards are covered in the Appendix
of this document. See Para 4.
2APPLICATION
This standard is for use by all Federal Agencies for procurement of
threaded
parts.
3. DETAILED STANDARDS. Detailed Standards for Screw-Threads
are identified as: FED-STD-H28/1 - Nomenclature, Definitions, and Letter Symbols for Screw Threads FED-STD-H28/2 - Unified Thread Form and Thread Series for Bolts, Screws, Nuts, Tapped Holes and General Applications FED-STD-H28/3 - Unified Threads of Special Diameter, Pitches, and Lengths of Engagement FED-STD-H28/4 - Controlled Radius Root Screw Threads, UNJ Symbol1
//.FED-STD-H28
31 March 1978FED-STD-H28/5 - Unified Miniature Screw ThreadsFED-STD-H28/6 - Gages and Gaging for Unified Screw ThreadsFED-STD-H28/7 - American Standard Pipe Threads except Dryseal and Hose Coupling TypesFED-STD-H28/8 - Dryseal American Standard Pipe ThreadsFED-STD-H28/9 - Gas Cylinder Valve Outlet and Inlet ThreadsFED-STD-H28/10 - American National Hose Coupling and Fire-Hose Coupling ThreadsFED-STD-H28/11 - Hose Connections For Welding and Cutting EquipmentFED-STD-H28/12 - Acme ThreadsFED-STD-H28/13 - Stub Acme ThreadsFED-STD-H28/14 - National Buttress ThreadsFED-STD-H28/15 - American Standard Rolled Threads For Screw Shells of Electric Lamp Holders and For Screw Shells of Unassembled Lamp BasesFED-STD-H28/16 - Microscope Objective and Nosepiece Threads, 0.800 - 36AMOFED-STD-H28/17 - Surveying Instrument Mounting ThreadsFED-STD-H28/18 - Photographic Equipment ThreadsFED-STD-H28/19 - Miscellaneous Threads
a FED-STD-H28/20 -Inspection Methods For Acceptability of UN, UNR,
UNJ,
M and MJ Screw-Threads
b FED-STD-H28/21 -Metri
c Screw-Threads
a FED-STD-H28/22 -Metric Screw-Thread Gages
4APPENDIX - The following supplements to the detailed
standards are included
in this documentA1 - American National Form of Thread Series for Bolts, Machine Screws, Nuts, Tapped Holes and General Applications Inactive for new design
a Not issued as of 31 March 1978
b Initial release as INTERIM FED-STD-00H28/21 DLA-IS dated 31 May 19772
//.FED-STD-H28 31 March 1978 A2 - American National Screw Threads of Special Diameters, Pitches, and Lengths of Engagement Deleted from 1969 issue of Hand book H28 A3 - Recommended Hole Size Limits Before Threading and Tap Drill Sizes A4 - Methods of Wire Measurements of Pitch Diameter of 600 Threads A5 - Design of Special Threads A6 - References Deleted from 1969 issue of Handbook H28 A7 - Supplementary Pipe Threads Information A8 - Geometry of Taper Screw Threads A9 - Extent of Usage of the American National Fire-Hose Coupling Threadson Couplings and Nipples used with 211 inch nominal Size Fire-Hose A10 - Wrench Openings A11 - Class 5 Interference - Fit Threads A12 - The Tightening of Threaded Fasteners to Proper Tension A13 - Three Wire method of measurement of Pitch Diameter of 290 Acme, 29 Stub Acme, and Buttress Threads A14 - Metric Screw Thread Standards Superseded by
FED-STD-00H28/21DLA-IS
5COMPARABLE INDUSTRY STANDARDS: but not Identical FED-STD-H28/1 - ANSI B1.7 FED-STD-H28/2 - ANSI B1.1 FED-STD-H28/3 - ANSI B1.1 a FED-STD-H28/4 - ANSIB1.15 FED-STD-H28/5 - ANSIB1.10 FED-STD-H28/6 - ANSI B1.23
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31 March 1978 FED-STD-H28/7- ANSI B2.1 FED-STD-H28/8- ANSI B1.20.3/B1.20.5 FED-STD-H28/9- ANSI 85.7.1/AGA Std V-1 FED-STD-H28/10 - ANSI B2.4/B1.81.1 or NFPA No. 194 FED-STD-H28/11 - CGA FED-STD-H28/12 - ANSI B1-5 FED-STD-H28/13 - ANSI B1.8 FED-STD-H28/14 - ANSI B1-9 FED-STD-H28/15 - ANSI C8.1 FED-STD-H28/16 - ANSI B1.11 FED-STD-H28/17 - FED-STD-H28/18 - ANSI PH3-7, 10, 12, 24 FED-STD-H28/19 - FED-STD-H28/20 - ANSI B1.3 a a FED-STD-H28/21 - ANSI B1.13, B1.22 Appendix A4 - ANSI B1.2 Appendix A7 - ANSI B1.3, B1.5, B2.1 Appendix A10 - ANSI B18.2 Appendix A11 - ANSI B1.12 Appendix A13 - ANSI B1.5, B1.8, B1.9 a Not Issued as of 31 March 19784
//. FED-STD-H28 31 March 1978 ANSI, USASI, ASA, NFPA Publications American National Standards Institute 1430 Broadway New York, NY 10018 National Fire Protection Association 470 Atlantic Avenue Boston, MA 02210 CGA Publications Compressed Gas Association, Inc500 5th Avenue New York, NY 100365
//.FED-STD-H28
31 March 1978
APPENDIX A1American National Form of Thread and Thread Series for
Bolts, Machine
Screws, Nuts, Tapped Holes and General ApplicationsSince the American National threads have been superseded by the Unified
threads, most of appendix 1, as shown in the previous 1957 issue of Part 1,
has been deleted. Shown herein is data on the class 3 internal threads in the
Coarse Thread Series in nominal sizes from 0.25 to one inch as there is still a
need for this informationData shown is from tables 1.2, 1.8, 1.16, and 1.17
of the 1957 issue. Appendix number and table numbers now preceded by an A.6
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31 March 19788
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31 March 1978 APPENDIX A2 AMERICAN NATIONAL SCREW THREADS OF SPECIAL DIAMETERS, PITCHES, AND LENGTHS OF ENGAGEMENT APPENDIX A2 DELETED FROM 1969 ISSUE OF HANDBOOK H2812
//. FED-STD-H28 31 March 1978
APPENDIX A3 Tap Drill Sizes for Unified Screw Threads and Recommended Hole Size Limits Before Threading.
1TAP DRILL SIZES FOR UNIFIED SCREW THREADS When it is important that the minor diameter of an internal thread conform
to specified limits it may be necessary to use a reamer to finish the holeHowever, a drill often can be made to cut with a sufficient accuracy for this
requirement. A variety of factors enter into the production of a clean,
round, straight hole of the correct diameter. For a discussion of these and
other data on drilling and tapping, reference should be made to "Drilled
Holes for Tapping," published by the Drill and Reamer Division and the Tap
and Die Division of the Metal Cutting Tool Institute, 405 Lexington Avenue,
New York, N.Y. 10017 Table A3.1, gives minor diameter limits and corresponding percentages of
basic thread height, 0.75H, for all standard series threads up to and including 3.75 inch-diameter for classes 1B and 2BTable A3.2 is a similar
table for class 3B. These tables also list sizes of drills that may be expected
to drill holes within or near the specified minor diameter limits.
The diameter
of the drill, the probable hole size, and the corresponding percentages of
basic thread height are tabulated As a drill may normally be expected to cut oversize, probable hole sizes
are tabulated that are derived from probable mean oversizes, also tabulatedThe following is quoted from the above-mentioned report: "These oversizes
were determined from a series of tests conducted by a number of drill manufacturers. Using six sizes of drills ranging from 1/16 to 1 in.
a total
of 2,808 holes were drilled in cast iron and steel. Commercial high speed
drills were used and the drilling equipment was of the same type and condition that is normally encountered in metal working shops. The average
depth of hole drilled was equal to 1.5 times the drill diameter and the
measurement of the hole was made at, the midpoint of the depth drilledWith good drilling practices and with reasonable care in the resharpening of
drills the average user may expect to drill oversize in the same manner."
2RECOMMENDED HOLE SIZE LIMITS BEFORE THREADING Recommended hole size limits before threading and the corresponding
tolerances are derived from the minimum and imum minor diameters of the
internal thread to provide for optimum strength of fastenings and tapping
conditions. The following rules as illustrated in figure A3.3 are used For the range to and including 0.33D, the minimum hole size is equal to the minimum minor diameter of the internal thread and the imum hole size
is larger by half the minor diameter tolerance For the range from 0.33D to 0.67D, the minimum and imum hole sizes an
each one quarter of the minor diameter tolerance larger than the corresponding limits for the length of engagement to and including 0.33DFor the range from 0.67D to 1.5D, the minimum hole size is larger than the
minimum minor diameter of the internal thread by half the minor diameter
tolerance and the imum hole size is equal to the imum minor diameter For the range from 1.5D to 3D, the minimum and imum hole sizes are each one quarter of the minor diameter tolerance of the internal thread larger
than the corresponding limits for the 0.67D to 1.5D length of engagement From the foregoing it will be seen that the difference between limits in
each range is the same and equal to half of the minor diameter toleranceThis is a general rule. However, the minimum differences for
sizes below 0.25
in are equal to the minor diameter tolerances given in tables 3.9 and 3.10
for lengths of engagement to and including 0.33D. For lengths of engagement
//.greater than 0.33D for sizes 0.25 in and larger the values are adjusted so
that the difference between limits is never less than 0.0040 in 2.1RECOMMENDED HOLE SiZE LIMITS FOR STANDARD UNIFIED THREADS AND SOME
UNS THREADS ARE GIVEN IN TABLES A3.5 AND A3.6.-For diameter-pitch combinations other than those given in these tables, the tolerances given in
table 2.21 or the tolerance derived from the formula, should be similarly
applied to determine the hole size limits Internal threads requiring modified minor diameters for lengths of
engagement less than 0.67D to develop the optimum strength of the fastening,
or longer than 1.5D to reduce tapping difficulties, should be designated as
specified in section 2. See under "Designating threads having modified
crests" in that section.
2.2. FOR UNIFIED Miniature threads, the distribution of hole size limits,
differs, from the above, to accord with conditions peculiar to miniature
threads and is shown in figure A3.4. The imum limits are based on providing a functionally adequate fastening for the most common applications,
where the material of the externally threaded member is of a strength essentially equal to or greater than that of its mating part. In applications
where, because of considerations other than the fastening, the screw is made
of an appreciably weaker material, the use of smaller hole sizes is usually
necessary to extend thread engagement to a greater depth on the external
threadHowever, hole sizes down to the minimum limit of the minor diameters
must be avoided to allow for the spin-up developed as the result of the
negative rake with which these small taps are ground Recommended hole size limits, for these threads are tabulated in table A3.713 //.FED-STD-H28
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APPENDIX A4 Methods of Wire Measurements of Pitch Diameter of 600 deg. Threads On a straight thread, the pitch diameter is the diameter of the cylinder
whose surface passes through the thread profiles at such points as to make
the widths of thread groove arid thread ridge equal Oil a taper thread, the pitch diameter at a given position oil the thread axis is the diameter of the pitch cone at that position The degree of accuracy, to which the pitch diameter call be measured will depend on the accuracy of lead, helix, and form of thread. As, thread plug
gages and thread setting plug gages have highly accurate threads, their pitch
diameters, may be measured to a correspondingly high degree of accuracy by
applying the methods described in this appendix. In turn, the virtual diameters
or effective si。