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1、BRITISH STANDARD BS 978-5: 1965 Specification for Fine pitch gears Part 5: Hobs and Cutters Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 978-5:1965 This British Standard, having been approved by the Mecha
2、nical Engineering Industry Standards Committee and endorsed by the Chairman of the Engineering Divisional Council, was published under the authority of the General Council on 22 November 1965 BSI 01-2000 The following BSI references relate to the work on this standard: Committee references MEE/17, M
3、EE/17/4 Draft for comment D 62/7139 ISBN 0 580 34079 1 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 scientific and industrial o
4、rganizations: The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: Associated Offices Technical CommitteeInsti
5、tution of Gas Engineers Association of Consulting Engineers*Institution of Heating and Ventilating Association of Mining Electrical and Engineers Mechanical Engineers*Institution of Mechanical Engineers Board of TradeInstitution of Mechanical Engineers British Chemical Plant Manufacturers (Automobil
6、e Division) AssociationInstitution of Production Engineers* British Compressed Air SocietyLocomotive and Allied Manufacturers British Electrical and Allied Manufacturers Association of Great Britain Association*London Transport Board British Gear Manufacturers Association*Machine Tool Trades Associa
7、tion* British Internal Combustion Engine Ministry of Defence, Army Department* Manufacturers AssociationMinistry of Defence, Navy Department* British Iron and Steel FederationMinistry of Labour (H.M. Factory Inspectorate) British Mechanical Engineering Federation*Ministry of Power British Railways B
8、oard*Ministry of Public Building and Works Crown Agents for Oversea Governments and Ministry of Technology National AdministrationsEngineering Laboratory* Electricity Council, the Generating Board and Ministry of Transport the Area Boards in England and WalesNational Coal Board Engineering Equipment
9、 Users AssociationNational Physical Laboratory (Ministry of Gas CouncilTechnology) Institute of Marine EngineersRadio Industry Council Institution of Civil EngineersRoyal Institute of British Architects British Horological InstituteSociety of Motor Manufacturers and Traders Electronic Engineering As
10、sociationLtd. Institution of Engineering InspectionUniversity of Sheffield Milling Cutter and Reamer AssociationManufacturers of fine pitch gears Ministry of Aviation North-East Coast Institution of Engineers and Shipbuilders Amendments issued since publication Amd. No.DateComments Licensed Copy: Lo
11、ndon South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 978-5:1965 BSI 01-2000i Contents Page Co-operating organizationsInside front cover Forewordiii Section 1. Hobs for fine pitch gears 1.1Scope1 1.2Terminology1 1.3Tooth form1 1.4
12、Gashes1 1.5Bores1 1.6Dimensions2 1.7Tolerances3 1.8Marking5 1.9Purchasing recommendation5 Section 2. Rotary form-relieved gear cutters for fine pitch gears 2.1Scope6 2.2Terminology6 2.3Tooth form6 2.4Cutter groups6 2.5Dimensions7 2.6Tolerances7 2.7Circumferential form relief11 2.8Arbor tolerances11
13、2.9Marking11 2.10 Purchasing recommendation11 Section 3. Pinion type cutters for fine pitch gears 3.1Scope12 3.2Terminology12 3.3Tooth form12 3.4Dimensions13 3.5Cutting rake18 3.6Bore18 3.7Provision of datum cylinder18 3.8Tolerances18 3.9Marking18 3.10 Purchasing recommendation18 Appendix A Marking
14、code for cutters for fine pitch gears21 Appendix B Basic rack tooth profiles (BS 978-1)22 Appendix C Basic rack tooth profile (gear and cutter) BS 978-2 addendum No. 123 Figure 1 Terminology applied to a typical gear hob1 Figure 2 Section of hob teeth on a developed helix5 Figure 3 Terminology of ro
15、tary form-relieved gear cutter6 Figure 4 Dimensions of cutter elements8 Figure 5 Terminology of pinion type cutter12 Figure 6 Basic rack tooth profile for unit normal diametral pitch22 Figure 7 Basic rack tooth profile for unit normal diametral pitch with backlash allowance22 Figure 8 Basic rack too
16、th profile for unit normal module23 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 978-5:1965 ii BSI 01-2000 Page Figure 9 Recommended profile of milling cutter for pinions of six to twelve teeth for unit n
17、ormal module23 Table 1 General dimensions of hobs2 Table 2 Tolerances3 Table 3 General dimensions of rotary form-relieved cutters7 Table 4 Unit pitch dimensions of cutter profiles for involute teeth to Figures 1 and 2 of BS 978-17 Table 5 Tolerances9 Table 6 Disc type gear cutter dimensions13 Table
18、7 Extended hub gear cutter dimensions14 Table 8 Screwed hub gear cutter dimensions15 Table 9 Parallel shank gear cutter dimensions16 Table 10 Taper shank gear cutter dimensions17 Table 11 Tolerances19 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+
19、00:00 2006, Uncontrolled Copy, (c) BSI BS 978-5:1965 BSI 01-2000iii Foreword This standard makes reference to the following British Standards: BS 978, Fine pitch gears. BS 978-1, Involute spur and helical gears. BS 978-2, Cycloidal type gears. PD 3376, BS 978-2:Addendum No. 1, Double circular are ty
20、pe gears. BS 978-3, Bevel gears. BS 2062, Gear hobs, Part 1: Hobs for general purposes. 1 d.p. to 20 d.p. inclusive. BS 2518, Rotary form-relieved gear cutters. BS 2887, Pinion type cutters for spur gears 4 D.P. to 20 D.P. This British Standard has been prepared under the authority of the Mechanical
21、 Engineering Industry Standards Committee and is one of a series for fine pitch gears and cutters. Other standards in this series are: BS 978-1, Involute spur and helical gears. BS 978-2, Cycloidal type gears. BS 978-2:Addendum No. 1, Double circular arc type gears. BS 978-3, Bevel gears. BS 978-4,
22、Worm gears (in course of preparation). The grades of cutters specified are related to similar grades in other British Standards as follows: Grade A corresponds to Grade AA in BS 2062-11) and in BS 28872). Grade B corresponds to Grade A in BS 2062-11) and in BS 28872). Grade C corresponds to Grade B
23、in BS 2062-11). This standard is divided into three sections viz.: Section 1: Gear hobs for fine pitch gears; Section 2: Rotary form-relieved gear cutters for fine pitch gears; Section 3: Pinion type cutters for fine pitch gears. The general terms used, common to gears and cutters are taken from BS
24、25193). A British Standard 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 co
25、mprises a front cover, an inside front cover, pages i to iv, pages 1 to 23 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) BS 2062, “Gear hobs”, Part 1, “Hobs f
26、or general purposes 1 d.p. to 20 d.p. inclusive”. 2) BS 2887, “Pinion type cutters for spur gears 4 D.P. to 20 D.P.”. 3) BS 2519, “Glossary of terms and notation for toothed gearing”. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncon
27、trolled Copy, (c) BSI iv blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 978-5:1965 BSI 01-20001 Section 1. Hobs for fine pitch gears 1.1 Scope This section of the standard relates to single-start, top
28、ping and non-topping, right- and left-hand hobs for the production of spur and helical gears in the pitch ranges 24 D.P. to 200 D.P. and 1 mm to 0.127 mm module inclusive. Three grades of hobs are given, viz. Grade A for the production of precision gears, Grade B for gears for high class work and Gr
29、ade C for general engineering. 1.2 Terminology The terminology of Figure 1 shall be used in all statements relating to gear hobs. 1.3 Tooth form The hob teeth shall be such as will generate gear teeth corresponding to the following basic rack tooth shapes: a) Involute i) as Figure 1 of BS 978-14) (s
30、ee Appendix B) ii) as Figure 2 of BS 978-14) (see Appendix B) b) Cycloidal as specified in BS 978-25). c) Double circular arc as in the addendum to Part 2 of BS 9786) (see Appendix C). NOTEOne hob will cut gears with any number of teeth of the forms given in a) and c) above. 1.4 Gashes The hobs shal
31、l be gashed parallel to the axis. 1.5 Bores The bores shall be parallel and may be recessed in the centre portion. Figure 1 Terminology applied to a typical gear hob 4) BS 978, “Fine pitch gears”, Part 1, “Involute spur and helical gears”. 5) BS 978-2, “Cycloidal type gears”. 6) PD 3376, BS 978-2:Ad
32、dendum No. 1, “Double circular arc type gears”. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 978-5:1965 2 BSI 01-2000 1.6 Dimensions The dimensions of the hobs shall be as in Table 1. Table 1 General dime
33、nsions of hobs 123456789101112 Pitch Outside diameterBore Minimum overall length Hub (see Notes 1 to 4) D.P. series Module series Diameter (approx.) Length mminmminmminmminmminmm 241.058317/8 15/8 32 3/4 1/2 1011/4 11/4 2011/4 13/16 22 3/32 3/32 1.5 280.907117/8 15/8 32 3/4 1/2 1011/4 11/4 2011/4 13
34、/16 22 3/32 3/32 1.5 320.793817/8 15/8 32 24 3/4 1/2 10 8 11/4 11/4 20 11 11/4 13/16 22 17.5 3/32 3/32 1.5 1.5 360.705617/8 11/8 32 24 3/4 1/2 10 8 11/4 11/8 15 11 11/4 13/16 22 17.5 3/32 3/32 1.5 1.5 400.63517/8 11/8 32 24 3/4 1/2 10 8 11/4 11/8 15 11 11/4 13/16 22 17.5 3/32 3/32 1.5 1.5 480.529217
35、/8 11/8 32 24 3/4 1/2 10 8 11/4 1 15 11 11/4 13/16 22 17.5 3/32 3/32 1.5 1.5 640.396915/8 11/8 32 24 3/4 1/2 10 8 11/4 7/8 15 11 11/4 13/16 22 17.5 3/32 3/32 1.5 1.5 800.317515/8 11/8 32 24 3/4 1/2 10 8 11/4 3/4 15 11 11/4 13/16 22 17.5 3/32 3/32 1.5 1.5 1000.25415/8 11/8 32 24 3/4 1/2 10 8 1 3/4 15
36、 11 11/4 13/16 22 17.5 3/32 3/32 1.5 1.5 1200.2177 15/8 11/8 32 24 18 3/4 1/2 10 8 8 1 5/8 15 11 11 1 13/16 22 17.5 13 3/32 1/16 1.5 1.5 1.5 1400.181415/8 11/8 32 18 3/4 1/2 10 8 1 1/2 15 11 1 13/16 22 13 3/32 1/16 1.5 1.5 1600.158815/8 11/8 32 18 3/4 1/2 10 8 1 1/2 15 11 1 13/16 22 13 3/32 1/16 1.5
37、 1.5 1800.141115/8 11/8 32 18 3/4 1/2 10 8 1 1/2 15 11 1 13/16 22 13 3/32 1/16 1.5 1.5 2000.127 15/8 11/8 11/8 32 18 18 3/4 1/2 1/2 10 8 8 1 1/2 1a 15 11 11 1 13/16 13/16 22 13 13 3/32 1/16 1/16 1.5 1.5 1.5 NOTE 1Although dimensions for the hub diameter are given this feature should be as large as p
38、ossible. NOTE 2The hub periphery is the datum surface for reference. NOTE 3Hubs need not be provided on Grades B and C hobs and in such cases the length of the hob may be reduced by twice the hub length. NOTE 4For Grade A hobs, single or double hubs may be provided depending upon the purchasers requ
39、irements. a Non-preferred length Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 978-5:1965 BSI 01-20003 1.7 Tolerances The tolerances to be applied to each grade of hob shall be as given in Table 2. Table 2
40、 Tolerances (In 0.0001 inch units) 1234567 ItemTypical illustrationTest Diametral pitch Grade 24 to 48 inc. Over 48 to 100 inc. Over 100 to 200 inc. Hub reference datum surfaces and periphery a Axial run-out of datum face A B C 1 2 3 1 2 3 1 2 Radial run-out of datum cylinder A B C 1 2 3 1 2 3 1 2 P
41、eriphery b Radial run-out A B C 3 6 10 3 5 10 3 3 Tooth lead variation Variation along tooth helix from tooth to tooth A B C 11/2 2 3 1 2 21/2 1 2 Variation along tooth helix in one convolution (cyclic pitch error) A B C 2 3 5 11/2 3 4 11/2 21/2 Variation along tooth helix in any three consecutive c
42、onvolutions (cumulative pitch error) A B C 21/2 5 7 2 4 6 2 3 Tooth Tooth thickness a) Minus only for non-topping hobs. For non-topping hobs the distance from the datum line to the top of the hob tooth is assumed to be the nominal value. b) Plus only for topping hobs. For topping hobs the distance f
43、rom the datum line to the root of the hob tooth is assumed to be the nominal value. A Non-topping543 Topping211/21 B Non-topping853 Topping432 C Non-topping 1310 Topping65 Tooth flank Profile Involute tooth form hobs only, plus only at tip and cutting depth A B C 11/2 2 3 1 11/2 2 1 11/2 a Where an
44、accessible datum face is provided. b For the finer pitches this test is usually performed on an optical projector. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 978-5:1965 4 BSI 01-2000 Table 2 Tolerances
45、(In 0.0001 inch units) 1234567 ItemTypical illustrationTest Diametral pitch Grade 24 to 48 inc. Over 48 to 100 inc. Over 100 to 200 inc. Cutting faces of gashes Adjacent spacing error A B C 6 10 16 6 10 16 6 10 Maximum cumulative spacing error A B C 10 16 25 10 16 25 10 16 Radial alignment of gash o
46、ver cutting depth A B C 5 5 5 Bore 3/4 in bore 1/2 in, 10 in and 8 mm bore Diameter (plus only) A B C 2 3 4 2 2 3 Standard bores shall be finished straight and parallel, within the tolerances given, for 75 per cent of each bearing length for Grades A and B hobs to 80 per cent for Grade C hobs Tooth
47、relief (These tolerances apply to new and re-sharpened hobs) A B and C The accuracy of the flank and circumferential form relief shall be such that the maximum tolerances will not be exceeded when the cutting faces are reground to the above tolerances. Licensed Copy: London South Bank University, Lo
48、ndon South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 978-5:1965 BSI 01-20005 1.8 Marking Each hob shall be marked in accordance with Appendix A. 1.9 Purchasing recommendation It is recommended that the purchaser should state: NOTEWhen a tapered “lead in” is r
49、equired, it should be stated on which end of the hob this should be formed. Figure 2 Section of hob teeth on a developed helix Quantity required.Hand (right or left). Number of this British Standard and section.Diameter and length. Tooth form.Topping or non-topping. Diametral pitch or millimetre module.Bore. Grade.Material of hob. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 01:54:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 97
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