ASME_B18.2.1-2010-六角方型美制螺栓螺钉最新标准

A N A M E R I C A N N A T I O N A L S T A N D A R D ASME B18.2.1-2010 [Revision of ASME B18.2.1-1996 (R2005)] Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series) INTENTIONALLY LEFT BLANK ASME B18.2.1-2010 [Revision of ASME B18.2.1-1996 (R2005)] Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series) A N A M E R I C A N N AT I O N A L S TA N D A R D Three Park Avenue • New York, NY • 10016 USA Date of Issuance: October 13, 2010 This Standard will be revised when the Society approves the issuance of a new edition. There will be no addenda issued to this edition. ASME issues written replies to inquiries concerning interpretations of technical aspects of this Standard. Interpretations are published on the ASME Web site under the Committee Pages at http://cstools.asme.org as they are issued. 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CONTENTS Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv Committee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii Correspondence With the B18 Committee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 General Data for Both Bolts and Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5 Lag Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Figures 1 Underhead Fillet for Long Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2 Underhead Fillet for Short Screws Threaded Full Length . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3 LG, Maximum and LB, Minimum for Short Screws Threaded Full Length . . . . . . . . . . . 15 Tables 1 Dimensions of Square Head Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Dimensions of Hex Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 Dimensions of Heavy Hex Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4 Dimensions of Askew Head Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5 Length Tolerances for Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6 Dimensions of Hex Cap Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7 Dimensions of Heavy Hex Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8 Dimensions of Hex Flange Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 9 Dimensions of Lobe Head Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 10 Dimensions of Underhead Fillets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 11 LG, Maximum and LB, Minimum Limitations for Short Screws Threaded Full Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 12 Maximum Grip Gaging Lengths, LG, and Minimum Body Lengths, LB, for Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 13 Length Tolerances for Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 14 Dimensions of Square Lag Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 15 Dimensions of Hex Lag Screws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 16 Dimensions of Lag Screw Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Mandatory Appendix I Gage and Gaging Practices for External Lobed Head Drive System . . . . . . . . . . . . . . . . 23 Nonmandatory Appendices A Formulas for Bolt and Screw Head Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 B Weight in Pounds of 100 Steel Hex Cap Screws for Given Diameter/Length Combination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 C Countersunk Center Holes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 iii FOREWORD American National Standards Committee B18 for the standardization of bolts, screws, nuts, rivets, and similar fasteners was organized in March 1922, as Sectional Committee B18, under the aegis of the American Engineering Standards Committee (later the American Standards Association, then the United States of America Standards Institute, and, as of October 6, 1969, the American National Standards Institute, Inc.), with the Society of Automotive Engineers and The American Society of Mechanical Engineers as joint sponsors. Subcommittee 2 was subse- quently established and chargedwith the responsibility for technical content of standards covering wrench head bolts and nuts. Subcommittee 2, after appraisal of the requirements of industry, developed a proposed standard series of bolt head and nut dimensions. This proposal was finally approved and designated a tentative American Standard in February 1927. A first revision of the document was designated as an American Standard in March 1933 and was followed by a second revision that was granted approval as an American Standard in January 1941. Following reorganization of the B18 Committee in 1947, Subcommittee 2 was asked to expand the standard on head proportions into a complete product standard. A proposal covering square and hexagon head bolts and nuts, hexagon head cap screws, and automotive hexagon head bolts was prepared and submitted to the B18 Committee in April 1950. While this draft was under consideration, the B18 Committee received a proposal from the British Standards Institution for unification of dimensions on products incorporating Unified screw threads. The Committee welcomed the opportunity of discussing the proposals and an American-British-Canadian Conference was held in New York, June 1 and 2, 1950. It was agreed in the conference that the essentials of unification could be accomplished by selection of mutually satisfactory across-the-flats dimensions, since this would permit the use of the same wrenches and because other features would rarely affect interchangeability. After due consideration, suitable existing across-the-flats dimensionswere selected for the hexagon products affected. In its meeting of October 13, 1950, Subcommittee 2 agreed to incorporate in the proposed standard the conference recommendations on 1⁄4-in. hexagon head bolts, 5⁄8-in. hexagon head cap screws and automotive hexagon head bolts, 5⁄16-in. and 3⁄8-in. regular hexagon and square nuts, and 7⁄16-in. light and regular hexagon and square nuts. At a subsequent meeting of Subcommittee 2, further changes were adopted in order to combine the light and regular series of nuts and to combine the automotive hexagon head bolt, hexagon head cap screw, and regular hexagon head close tolerance bolt. In view of the progress made in the United States and the urgency of standardization for mutual defense, the British Standards Institution sponsored a second conference in London in April 1951, to complete the unification of certain hexagon bolts and nuts. At a meeting on June 8, 1951, Subcommittee 2 reaffirmed its acceptance of the unified dimen- sions, which corresponded with those in the March 1951 draft, but attempted to select better nomenclature for the unified products. A final draft incorporating the nomenclature “Finished Hexagon Bolts and Nuts” and containing numerous editorial changes was submitted for letter ballot in September 1951. Following approval by the B18 Committee and the sponsors, the proposal was presented to the American Standards Association for approval and designation as an American Standard. This was granted on March 24, 1952. Recognizing the Standardwas in need of additional refinements, Subcommittee 2 began immedi- ately to revise it, removing inconsistencies with respect to fillets, improving the length tolerances on heavy hexagon bolts, and incorporating numerous other corrections and clarifications. The most noteworthy editorial change was a decision to combine the coverage for hexagon cap screws and square head set screws from the B18.2 Standard with the coverage for slotted head cap screws and slotted headless set screws from the B18.6 Standard and publish them in a separate iv document. The requirements for the unified hexagon cap screws and finished hexagon bolts being identical in the overlapping sizes, these data would now be available in two publications. Following approvals by the B18Committee and sponsor organizations, the proposalwas submitted to the American Standards Association and declared an American Standard on February 2, 1955. A revision of this document comprised of numerous editorial corrections, and inclusion of an appendix for grade markings was duly approved and designated an American Standard on April 18, 1960. At a meeting in February 1960, Subcommittee 2 approved a recommendation to reduce the head heights for heavy, heavy semifinished, and heavy finished hexagon bolts that was subsequently approved by letter ballot of the B18 Committee on August 16, 1960. A proposed Standard for heavy hexagon structural bolts submitted and accepted by Subcommittee 2 at its October 17, 1960 meeting was approved by letter ballot of the B18 Committee on May 9, 1961. To meet the urgent needs of the steel construction industry, it was considered necessary to publish the Standard for the structural bolts immediately. Consequently, Appendix IV to ASA B18.2-1960 containing coverage for the revised heavy hexagon bolts and the new heavy hexagon structural bolts was released in 1962. In October of 1961, Subcommittee 2 appointed a subgroup to review all product standards for square and hexagon bolts, screws, and nuts and to recommend simplifications that would be compatible with technical, production, and distribution advances that had occurred over the prior several years. The subgroup presented its recommendations at a meeting of Subcommittee 2 in October of 1962. It was agreed that the internally and externally threaded products should be published in separate documents as suggested, and draft proposals for each were completed. The proposed revision for square and hex bolts and screws incorporated the following subgroup recommendations: consolidation of hexagon head cap screws and finished hexagon bolts into a single product, consolidation of heavy semifinished hexagon bolts and heavy finished hexagon bolts into a single product, elimination of regular semifinished hexagon bolts, a new length tolerancing pattern for all bolts and screws, documentation of a positive identification procedure for determining whether an externally threaded product should properly be designated a bolt or a screw, and an abbreviated and purified set of product nomenclature reflecting application of the identification procedure. Letter ballot of this proposal to the B18 Committee in March, 1964 resulted in several comments that were resolved to the satisfaction of the committee in June of 1964. Following acceptance by the sponsor organizations, the revision was submitted to the American Standards Association and was designated American Standard ASA B18.2.1 on September 8, 1965. Subcommittee 2 continued to further develop refinements initiated by the simplification sub- group and revisions reflecting changes in manufacturing practices and consumer requirements. This work culminated in Subcommittee acceptance of a 1970 proposal incorporating, in addition to numerous editorial changes, revisions in the following significant areas: addition of coverage for askew head bolts and hex head lag screws, addition of straightness requirements to applicable products, addition of minimum fillet to square and hex bolts and lag screws, application of UNR threads and new concepts for controlling thread length on products having Unified threads, and clarification of grade markings, thread runout gages, and formulas for dimensions. Also included were refinements to hex cap screw and heavy hex screw requirements consisting of the addition of wrenching height and revision of underhead fillets, washer face thicknesses, and controls on angularity of bearing face. The proposed revision, after approval by letter ballot of the B18 Committee in March 1970, was subsequently approved by the sponsors and submitted to the American National Standards Institute for designation as an American National Standard. This was granted on January 18, 1972. Numerous user complaints on interference of the elliptical fillet added in the 1972 revision resulted in the appointment of a subcommittee to study the problem. They recommended reverting back to the max./min. radius fillet specified in the 1965 version with the elliptical fillet retained for use when specified by the user. Further refinements in the definition of the fillet for short length screws were added to “Hex Cap and Heavy Hex Screws.” Geometric tolerancing was updated to conform to American National Standard Y14.5, Dimensioning and Tolerancing. The transition length of the hex cap screw was changed to equal 5 coarse (UNC) threads. Few, if any, users accepted the 1972 values that were designed to reduce tooling by providing the same body v length for adjacent lengths. On screws, separate straightness requirements have been deleted, and the combination thread runout and straightness gage described in Appendix I is specified. Straightness as a variable based on length has been applied to bolts with gaging described in Appendix 11. Acceptability of screw threads based on gaging systems established by American National Standard B1.3-1979 has been added to each type of screw or bolt, except lag screws. This proposal was approved by letter ballot of the Subcommittee and B18 in January 1980. Following acceptance by the secretariat organizations, the revision was referred to the American National Standards Institute and granted recognition as an American National Standard on June 24, 1981. In 1991, it was recognized that B18.2.1 required extensive revision to better meet the needs of conformance with Public Law 101-592. Included in these considerations were improved definition of a full body versus a reduced body and those dimensions that should be certified to ensure product fit, form, and function. Other dimensions given for each product would only be examined in the event of a dispute. Also, the term “finished hex bolt,” which is today’s cap screw, should be dropped. Additionally, a weight table has been included to assist users. Furthermore, it was felt that the heavy hex structural bolt, heavy hex nut, hardened steel washers, and compressible washer-type direct tension indicators should be included in a new standard for fasteners intended for use in structural applications. For this reason, the heavy hex structural bolt was removed from this Standard. The new table for maximum grip gaging lengths and minimum body lengths for cap screws and heavy hex screws was included for the first time in the 1996 edition to assist users and is similar to the pattern used for metric bolts and screws. The Subcommittee 2 agreed to undertake the revision of B18.2.1 during the first quarter of 2008. The Standard was updated to incorporate the new format and additional sections as refined in ASME B18.12.1. The notes that had followed every table were reorganized into the body of the Standard to eliminate the redundancy created by repeating the same table notes under numerous tables. This revision adds flange head and lobed head screws and extends the size range of heavy hex head cap screws from 3 in. to 6 in. in diameter. The thread details for lag screws were redefined to align with the way all other spaced threads are defined. Designated inspection characteristics were eliminated from each product type, and a general section on quality assurance was created stating that all products must meet the requirements in the Standard according to ASME B18.18.2. The title of the Standard was revised to indicate that the flange head and lobed head screws have been added to the Standard. Suggestions for improvement of this Standard will be welcomed. They should be sent to The American Society of Mechanical Engineers, Secretary, B18 Main Committee, 3 Park Avenue, New York, NY 10016-5990. This revision was approved as an American National Standard on July 8, 2010. vi ASME B18 COMMITTEE Standardization of Bolts, Nuts, Rivets, Screws, Washers, and Similar Fasteners (The following is the roster of