BS-5590-1978.pdf
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1、BRITISH STANDARD BS 5590:1978 Incorporating Amendment No. 1 Specification for Screw thread metric series measuring cylinders UDC 621.882.082.1:531.717.15 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:24:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5590:1978 This British Standard, hav
2、ing been prepared under the direction of the Mechanical Engineering Standards Committee, was published under the authority of the Executive Board on 31 May 1978 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference MEE/59 Draft for comment 73/33654 DC ISBN
3、 0 580 35087 8 Cooperating organizations The Mechanical Engineering Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee
4、Department of Trade (Marine Division) Association of Consulting EngineersDepartment of Transport Association of Hydraulic Equipment Electricity Supply Industry in England Manufacturersand Wales Association of Mining Electrical andEngineering Equipment Users Association Mechanical EngineersFederation
5、 of Manufacturers of British Compressed Air SocietyConstruction Equipment and Cranes British Electrical and Allied ManufacturersHealth and Safety Executive Association (BEAMA)Institution of Gas Engineers British Gas CorporationInstitution of Mechanical Engineers British Gear Manufacturers Associatio
6、nInstitution of Plant Engineers British Internal Combustion Engine Institution of Production Engineers* Manufacturers AssociationLondon Transport Executive British Pump Manufacturers AssociationMachine Tool Trades Association British Steel CorporationMinistry of Defence* British Steel IndustryNation
7、al Coal Board Chartered Institution of Building ServicesProcess Plant Association Crown Agents for Oversea Governments and Railway Industry Association of AdministrationsGreat Britain Department of the EnvironmentSociety of Motor Manufacturers and Department of IndustryTraders Limited (Mechanical En
8、gineering)Telecommunication Engineering the mean measured diameter of each cylinder; the designation (see Table 2 and Table 4); the P value, or values, corresponding to the use of the pair or set to the thread forms and pitches of screw threads listed in Table 2, Table 3 and Table 4 as appropriate.
9、10 Replacement cylinders When a cylinder is lost, broken or otherwise damaged, an appropriate replacement cylinder may be substituted, provided that the P value is recalculated according to the mean diameter of the cylinders in the reconstituted pair or set. 11 Use of designated cylinders for other
10、thread forms The application of the cylinders listed in Table 2 for measuring the pitch diameter of Unified, Whitworth and B.A. screw threads, is given in Appendix C , Table 3. Additional cylinders required for such screw threads not included in Table 3 are given in Table 4. Figure 2 Testing straigh
11、tness of cylinders Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:24:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5590:1978 4 BSI 07-1999 Appendix A Definitions of pitch, pitch diameter and pitch line A.1 pitch the distance measured parallel to the axis between corresponding points on
12、 adjacent thread forms A.2 pitch diameter the diameter of an imaginary cylinder which intersects the surface of the thread in such a manner that the intercept on a generator of the cylinder between the points where it meets the opposite flanks of the thread groove is equal to one half of the nominal
13、 pitch of the thread (see Figure 3) A.3 pitch line the line of the generator making the intercepts with the flanks defining pitch diameter (see Figure 3) Appendix B Derivation of P value Note 3 to 3.1 refers to a full description of the method of measuring the pitch diameter of a screw thread, but f
14、or convenience of reference brief details are given below. B.1 Dimension T. A micrometer reading is obtained over cylinders contacting a plain setting plug of known diameter after which readings are taken over the same cylinders contacting the flanks of the screw thread. Thus, dimension T is obtaine
15、d, see Figure 4. Figure 3 Pitch diameter and pitch line of a screw thread Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:24:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5590:1978 BSI 07-19995 Figure 4 Use of two cylinders to measure a screw thread to obtain dimension T Figure 5 Cylind
16、er contact and relationship to E, T and P values Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:24:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5590:1978 6 BSI 07-1999 B.2 E, T and P value (see Figure 5) If E = measured pitch diameter T = measured dimension under the cylinders p = nom
17、inal pitch of thread w = mean measured diameter of cylinders used ! = flank angle of thread. Then E = T + w w cosec ! +cot ! Since the nominal values of p, cosec ! and cot !, together with the value of w are known before measurement, they can be gathered into a single value called the P value, i.e.
18、for a given diameter of cylinder, w, in a given thread form of flank angle ! and pitch p P value = p cot ! (cosec ! 1) w and E = T + P value By substituting the appropriate values of cosec ! and cot ! in the equation for P value, a general expression can be obtained for the P value of each thread fo
19、rm as follows. Appendix C Use of designated cylinders for various thread forms C.1 Designated cylinders in Table 2 can also be used for certain pitches of Unified, Whitworth and B.A. thread forms as shown in Table 3. In these additional applications the designated cylinders do not contact the pitch
20、line. However, the P value ascribed to a pair of cylinders for the different threads concerned may be used to measure threads having errors of included flank angle of up to the amounts specified below without thereby introducing an error greater than 0.0005 mm. Where the included angle of a thread e
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