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1、BRITISH STANDARD BS 768:1958 Specification for Slotted grub screws Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 768:1958 This British Standard, having been approved by the Mechanical Engineering Industry
2、Standards Committee and endorsed by the Chairman of the Engineering Divisional Council, was published under the authority of the General Council on 28 November 1958 BSI 03-2000 First published January 1938 First revision November 1958 The following BSI references relate to the work on this standard:
3、 Committee reference MEE/60 Draft for comment CX (MEE) 9099 ISBN 0 580 35818 6 Co-operating organizations The Mechanical Engineering Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and sci
4、entific and industrial organizations: Admiralty*High Commission of India* Air MinistryInstitute of Marine Engineers Associated Officers Technical CommitteeInstitute of Petroleum Association of Consulting Engineers Institution of Civil Engineers (Incorporated)Institution of Gas Engineers British Chem
5、ical Plant Manufacturers Institution of Heating and Ventilating AssociationEngineers British Compressed Air SocietyInstitution of Mechanical Engineers British Electrical and Allied ManufacturersInstitution of Mechanical Engineers Association*(Automobile Division) British Engineers Association*Instit
6、ution of Production Engineers* British Gear Manufacturers AssociationLocomotive and Allied Manufacturers British Internal Combustion EngineAssociation of Great Britain* Manufacturers Association*Machine Tool Trades Association* British Iron and Steel Federation*Ministry of Labour and National Servic
7、e British Railways, The British Transport (Factory Inspectorate) Commission*Ministry of Power Crown Agents for Oversea Governments and Ministry of Supply* Administrations*Ministry of Transport and Civil Aviation D.S.I.R. Mechanical Engineering ResearchMinistry of Works LaboratoryNational Coal Board
8、Electricity Council, the Generating Board and National Physical Laboratory (D.S.I.R.)* the Area Boards in England and WalesRadio Industry Council* Engineering Equipment Users AssociationWar Office Gas Council The organizations marked with an asterisk in the above list, together with the following, w
9、ere directly represented on the Committee entrusted with the preparation of this standard: Agricultural Engineers AssociationInstitute of Iron and Steel Wire Manufacturers Bright Bolt and Nut ManufacturersInstitution of Naval Architects AssociationPost Office Bright Steel Bar AssociationRadio Commun
10、ication and Electronic British Constructional Steelwork AssociationEngineering Association British Cycle and Motor Cycle Industries Rolled Thread Screw Association Association Ltd.Screw Manufacturers Association Cold Headed Heat Treated Bolt AssociationSociety of Motor Manufacturers and Council of B
11、ritish Manufacturers of Petroleum Traders Ltd. EquipmentWasher Manufacturers Association Electronic Engineering Association Amendments issued since publication Amd. No.Date of issueComments 1878January 1976Indicated by a side line in the margin Licensed Copy: London South Bank University, London Sou
12、th Bank University, Fri Dec 08 11:01:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 768:1958 BSI 03-2000i Contents Page Co-operating organizationsInside front cover Forewordii 1Scope1 2Material1 3Terminology1 4Dimensions1 5Slots1 6Length of screw1 7Slotted end2 8Types of point2 9Screw threads3 App
13、endix A Standard lengths of steel and brass grub screws5 Appendix B Dimensions of grub screws with non-preferred B.S.W. threads6 Appendix C7 Figure 1 Alternative types of slotted end2 Figure 2 Alternative types of point3 Figure 3 Steel grub screws with cup points7 Table 1 Grub screws with UNC or UNF
14、 threads4 Table 2 Grub screws with B.A. threads4 Table 3 Grub screws with B.S.W. or B.S.F. threads4 Table 4 Standard lengths of steel and brass grub screws with unified threads5 Table 5 Standard lengths of steel and brass grub screws with B.A. threads5 Table 6 Standard lengths of steel and brass gru
15、b screws with Whitworth threads6 Table 76 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 768:1958 ii BSI 03-2000 Foreword This standard makes reference to the following British Standards: BS 84, Parallel sc
16、rew threads of Whitworth form. BS 93, B.A. screw threads. BS 1580, Unified screw threads. This British Standard has been prepared under the authority of the Mechanical Engineering Industry Standards Committee and forms one of a series for screwed fasteners. When first issued in 1938, the standard re
17、ferred only to dimensions, and related to screws with B.S.W., B.S.F., B.A. and B.S.P.F. (formerly B.S.P.) threads. In revising it to include screws with UNC and UNF threads, the opportunity has also been taken to add provisions for a number of general requirements in accordance with recent British S
18、tandards for screwed fasteners. Screws with B.S.P.F. threads have been omitted as there does not appear to be sufficient demand to warrant their inclusion, and hexagon socket set screws are not included as they are now covered by BS 2470, “Hexagon socket screws and wrench keys.” In view of the fact
19、that this standard now provides for grub screws with Unified threads, every effort has been made to ensure that the dimensions and standard types of points do not conflict with those specified in the American Standard ASA. B18.6.21), although more types of points are included in the latter; there ar
20、e, however, certain differences in terminology and these are explained in Clause 3 of the present standard. In accordance with BSI policy concerning the introduction of metric standards, this imperial standard has been declared obsolescent. It will be made obsolete in due course. A British Standard
21、does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an i
22、nside front cover, pages i and ii, pages 1 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. 1) ASA B18.6.2. “Hexagon head cap screws, slo
23、tted head cap screws, square head set screws and slotted headless set screws.” Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 768:1958 BSI 03-20001 1 Scope This British Standard relates to ferrous and non-f
24、errous slotted grub screws, having UNC, UNF, B.A., B.S.W. or B.S.F. threads. General dimensions and requirements for material, finish, slots and types of point are given, and tables of standard lengths are also included in Appendix A. 2 Material The material from which grub screws are manufactured s
25、hall have a tensile strength of not less than the following: If the purchaser requires grub screws to be case-hardened or to be manufactured from steel or brass of a higher tensile strength, or of another material, he shall specify his requirements. NOTEUnless otherwise required by the purchaser, st
26、eel grub screws with cup points (see Appendix C) will be supplied case-hardened. 3 Terminology The designations used in this standard are in accordance with those in common use in British engineering practice. It is American practice to use the term “headless set screw,” but the descriptive term “gr
27、ub screw” is so well established in British engineering that it has been retained for this standard. Radiused points (see Clause 8) are shown in the American Standard as “oval” or “round” points. 4 Dimensions The dimensions and tolerances for grub screws shall be as specified in Table 1Table 3 inclu
28、sive and Clauses 59 inclusive. Point dimensions for grub screws with cup points are given in Appendix C. 5 Slots The slots shall be clean and reasonably free from burrs, and, on visual inspection, shall appear to pass through the centre point of the surface plane of the top of screw. The depth of sl
29、ot (Dimension B, Figure 1) shall be measured from the extreme end of the screw to the point at which the slot breaks through. 6 Length of screw For the purposes of this standard the “length” shall be the distance between the extreme ends of the screw, whatever the type of point. The permissible tole
30、rance on length shall be as follows: NOTE 1Attention is drawn to the fact that the tolerances on length are expressed in a negative direction. NOTE 2Standard lengths are given in Table 4, Table 5 and Table 6 in Appendix A. Steel25 tons/sq. in. Brass20 tons/sq. in. Length Major diameter of thread Tol
31、erance on length in.in.in. Up to and including 1/8All diameters+ 0 0.01 Above 1/8 up to and including 1/2 Below 1/4 1/4 and over + 0 0.02 + 0 1/32 Above 1/2up to and including 1All diameters+ 0 1/32 Above 1 up to and including 2All diameters+ 0 1/16 Over 2All diameters+ 0 3/32 Licensed Copy: London
32、South Bank University, London South Bank University, Fri Dec 08 11:01:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 768:1958 2 BSI 03-2000 7 Slotted end The slotted end may, at the option of the manufacturer, be finished with either a flat chamfer with a 90 included angle to a depth slightly exce
33、eding the depth of thread, or with a radius approximately equal to the nominal diameter of the screw thread D (see Figure 1). This option shall apply unless the purchaser in his enquiry and order specifically states that he requires screws with “flat chamfered” or “radiused” slotted ends. NOTEAttent
34、ion is drawn to the fact that these alternative slotted ends are associated with the particular method of manufacture. A request by the purchaser for a specific type of slotted end limits the manufacturing processes available, and it is therefore recommended that the purchaser avoids making such a r
35、equest unless circumstances fully justify it. 8 Types of point a) General. The standard types of points at the unslotted end shall be the cone point and the radiused point, as shown in Figure 2. The cup point, which is shown in Appendix C is not normally used and will be supplied only when specially
36、 ordered. The preferred type of point for steel grub screws with B.S.W., B.S.F., UNC or UNF threads is the cone point. The preferred type of point for brass grub screws with any of the standard thread forms, and for steel grub screws with B.A. threads is the radiused point. Unless otherwise specifie
37、d by the purchaser, these preferred types of points shall be supplied. b) Cone points. For grub screws with a length equal to or less than the basic major diameter of the thread, the cone point shall have an included angle of 120. For grub screws with a length greater than the basic major diameter o
38、f the thread, the cone point shall have an included angle of 90. c) Radiused points. Radiused points shall have a radius approximately 0.75 times the basic major diameter of the thread. Figure 1 Alternative types of slotted end Licensed Copy: London South Bank University, London South Bank Universit
39、y, Fri Dec 08 11:01:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 768:1958 BSI 03-20003 9 Screw threads Grub screws shall, for their full screwed length, have their screw threads in accordance with the limits and tolerances laid down in the appropriate British Standard as follows: Other classes o
40、f fit are not normally supplied. They should be ordered only in exceptional circumstances and, if required, shall be specified by the purchaser in his enquiry and order. Figure 2 Alternative types of point BS 1580“Unified screw threads”Class 2A BS 93“B.A. screw threads”Normal class BS 84“Parallel sc
41、rew threads of Whitworth form”Medium class Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 768:1958 4 BSI 03-2000 Table 1 Grub screws with UNC or UNF threads Table 2 Grub screws with B.A. threads Table 3 Gru
42、b screws with B.S.W. or B.S.F. threads NOTEDimensions for grub screws of 5/32 in. nominal size are given in Appendix B. 12345 Nominal size Basic major diameter of thread D Width of slot A (Figure 1) Depth of slot B (Figure 1) Max.Min.Nom. in.in.in.in.in. 1/4 5/16 3/8 0.250 0 0.312 5 0.375 0 0.056 0.
43、063 0.077 0.045 0.051 0.064 0.063 0.078 0.094 7/16 1/2 9/16 0.437 5 0.500 0 0.562 5 0.085 0.096 0.107 0.072 0.081 0.091 0.109 0.125 0.141 5/8 3/4 0.625 0 0.750 0 0.119 0.147 0.102 0.129 0.156 0.188 123456 Nominal size Basic major diameter of thread D Width of slot A (Figure 1) Depth of slot B (Figur
44、e 1) Max.Min.Nom. mmin.in.in.in. 0 1 2 6.0 5.3 4.7 0.236 2 0.208 7 0.185 0 0.048 0.044 0.040 0.040 0.036 0.032 0.063 0.059 0.055 3 4 5 4.1 3.6 3.2 0.161 4 0.141 7 0.126 0 0.036 0.032 0.029 0.029 0.025 0.023 0.051 0.047 0.043 6 7 8 2.8 2.5 2.2 0.110 2 0.098 4 0.086 6 0.026 0.023 0.021 0.020 0.017 0.0
45、15 0.039 0.036 0.033 9 10 12 1.9 1.7 1.3 0.074 8 0.066 9 0.051 2 0.019 0.017 0.015 0.013 0.012 0.010 0.030 0.027 0.024 12345 Nominal size Basic major diameter of thread D Width of slot A (Figure 1) Depth of slot B (Figure 1) Max.Min.Nom. in.in.in.in.in. a1/8 3/16 1/4 0.125 0 0.187 5 0.250 0 0.029 0.
46、040 0.056 0.023 0.032 0.045 0.043 0.055 0.063 5/16 3/8 7/16 0.312 5 0.375 0 0.437 5 0.063 0.077 0.085 0.051 0.064 0.072 0.078 0.094 0.109 1/2 9/16 5/8 0.500 0 0.562 5 0.625 0 0.096 0.107 0.119 0.081 0.091 0.102 0.125 0.141 0.156 3/4 0.750 00.1470.1290.188 a Standard with B.S.W. threads only. License
47、d Copy: London South Bank University, London South Bank University, Fri Dec 08 11:01:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 768:1958 BSI 03-20005 Appendix A Standard lengths of steel and brass grub screws The sizes listed in Table 4, Table 5 and Table 6 are those which are expected to be i
48、n greatest demand, and include those preferred sizes (marked P) which are most likely to be stocked in steel when the standard comes into general use. It is therefore recommended that purchasers should order these sizes whenever possible. Sizes marked X will not normally be stocked. Intermediate len
49、gths not shown in these tables should be avoided. Table 4 Standard lengths of steel and brass grub screws with unified threads NOTE 1Steel grub screws with UNF threads are not expected to be normally stocked, but should be ordered to the standard lengths given above. NOTE 2Brass grub screws with UNC and UNF threads are not expected to be normally stocked except in the shorter lengths of 1/4in. diameter UNC but should be ordered to the standard lengths given above. NOTE 3Unless otherwise specified by the purchas
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