1、BRITISH STANDARD BS 2518-2: 1977 Specification for Rotary form relieved gear cutters Part 2: Metric module UDC 621.914.2:621.833BS2518-2:1977 This British Standard, having been prepared under the directionof the Mechanical Engineering Standards Committee, was published underthe authority of the Exec
2、utive Board on 29 April 1977 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference MEE/127 Draft for comment 75/76567 DC ISBN 0 580 09682 3 Cooperating organizations The Mechanical Engineering Industry Standards Committee, under whose supervision this Brit
3、ish Standard was prepared, consists of representatives from the following Government departments and professional and industrial organizations: The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly
4、 represented on the committee entrusted with the preparation of this British Standard: Associated Offices Technical Committee Electricity Supply Industry in England and Association of Consulting Engineers Wales Association of Hydraulic Equipment Engineering Equipment Users Association Manufacturers
5、Ltd. Federation of Manufacturers of Construction Association of Mining Electrical and Equipment and Cranes Mechanical Engineers Health and Safety Executive (HM Factory British Compressed Air Society Inspectorate) British Electrical and Allied Manufacturers Institution of Gas Engineers Association In
6、stitution of Heating and Ventilating British Gas Corporation Engineers British Gear Manufacturers Association* Institution of Mechanical Engineers British Internal Combustion Engine Institution of Plant Engineers Manufacturers Association Institution of Production Engineers* British Mechanical Engin
7、eering Confederation London Transport Executive British Pump Manufacturers Association Machine Tool Trades Association* British Steel Corporation Ministry of Defence* British Steel Industry National Coal Board Crown Agents for Oversea Governments and Process Plant Association Administrations Railway
8、 Industry Association of Great Britain Department of the Environment Royal Institute of British Architects Department of Industry Mechanical Society of Motor Manufacturers and Traders Engineering Ltd. Department of Industry National Telecommunication Engineering and Engineering Laboratory* Manufactu
9、ring Association Department of Trade Water-tube Boilermakers Association Gauge and Toolmakers Association Navy and Vickers Gearing Research Milling Cutter and Reamers Association Association National Federation of Engineers Tool North East Coast Institution of Engineering Manufacturers and Shipbuild
10、ers Amendments issued since publication Amd. No. Date of issue CommentsBS2518-2:1977 BSI 12-1999 i Contents Page Cooperating organizations Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 Gear tooth form 1 5 Cutter groups 1 6 Cutter dimensions 1 7 Cutter keyways 1 8 Arbors a
11、nd keys 1 9 Marking 1 10 Ordering instructions 2 Appendix A Milled gears intended to mesh with generated gears 8 Appendix B Form relief 8 Figure 1 Rotary form relieved gear cutters 2 Figure 2 20 pressure angle composite basic rack tooth profile for unit module pitch 4 Figure 3 Cutter tooth profile 5
12、 Figure 4 Keyway 6 Figure 5 Key for arbor 6 Table 1 Standard group (eight cutters) 2 Table 2 Dimensions of module pitch 20 pressure angle gear cutters 3 Table 3 Profile dimensions for unit module 20 pressure angle rotary gear cutters 5 Table 4 Tolerance on tooth thickness 6 Table 5 Dimensions of key
13、ways 6 Table 6 Dimensions of keys for arbors 7 Table 7 Reduction of tooth thickness of milled gear teeth for cutters of unit module 8 Publications referred to Inside back coverBS2518-2:1977 ii BSI 12-1999 Foreword This British Standard has been prepared under the authority of the Mechanical Engineer
14、ing Standards Committee and is based upon a draft submitted by the Milling Cutter and Reamer Association. It forms part of a series of standards for gear forming tools. Part 1:1954 of this standard deals with DP cutters and it will be retained in parallel with Part2 as it is considered DP cutters wi
15、ll be required for repair work for some years to come. The composite basic rack tooth profile adopted (Figure 2) is designed to avoid undercutting in gears having a small number of teeth, and it provides also suitable tip relief in the teeth cut. A tooth profile diagram with table of dimensions for
16、unit module cutters is provided for the setting out of the respective profiles of the full range of cutters used for standard uncorrected gears with no backlash ranging from a 12tooth pinion to a rack. Dimensions for bores, keys and keyways are selected from BS122-3 and ISO240. A British Standard do
17、es 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 ins
18、ide front cover, pages i and ii, pages1 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.BS2518-2:1977 BSI 12-1999 1 1 Scope This Part of
19、BS2518 specifies certain dimensions for rotary form relieved gear cutters for milling spur and helical gears within the range1 to25metric module. Such cutters are deemed satisfactory for cutting gears intended to mesh together under conditions of service which are not critical. NOTEIt is not recomme
20、nded that cutters designed in accordance with this standard be used for milling gears intended to mesh with generated gears. Where, however, it is found necessary to do this, a reduction in chordal thickness of the gear teeth is essential. (SeeAppendix A.) 2 References The titles of the publications
21、 referred to in this standard are given on the inside back cover. 3 Definitions For the purposes of this Part of BS2518 the following definitions apply. rotary form relieved gear cutter a circular milling cutter having on its periphery teeth of such a form that it will cut out a single tooth space i
22、n a gear form relief the provision of a cutting clearance between the cutter teeth and the work. (SeeFigure 1 and Appendix B.) the terms used in describing parts of rotary form relieved gear cutters are illustrated inFigure 1. General terms and notation relating to gears are given in BS2519 4 Gear t
23、ooth form Cutters shall be designed to cut gears corresponding to the20 composite basic rack tooth profile shown inFigure 2. It should be noted that the form of teeth obtained with any cutter is strictly correct only when the number of teeth of the gear is the smallest specified for the cutter. A to
24、oth profile layout diagram (Figure 3) for standard 20 pressure angle cutters is included to enable the profile of each cutter in the standard group to be accurately set out. The dimensions inTable 3 are calculated for unit module cutters. For any other module, the dimensions have to be multiplied by
25、 the corresponding value of the module. 5 Cutter groups In accordance with rotary gear cutter practice, the standard group for any given pitch shall consist of eight cutters, numbered one to eight inclusive, for milling gears having the numbers of teeth specified inTable 1. For helical gears, the vi
26、rtual number of teeth, calculated as z sec 3 should be used to select a cutter number, z being the actual number of teeth and the helix angle of the gear. 6 Cutter dimensions 6.1 The cutter profiles shall be set out using the co-ordinates and radii inTable 3 multiplied by the module. 6.2 The tooth t
27、hickness s at depth shall be as specified inTable 3, multiplied by the module. The tolerances on the tooth thickness shall be as specified inTable 4. 6.3 The diameters, bores and widths shall be as specified inTable 2. 6.4 The number of cutting teeth and the amount of cutting relief shall be at the
28、discretion of the manufacturer. 7 Cutter keyways Dimensions of keyways shall be as specified inTable 5. 8 Arbors and keys Arbors and keys shall conform to the dimensions given inTable 6. 9 Marking Cutters shall be marked with the following information where applicable. For convenience the symbols sh
29、ould be used. The makers identification mark or number, and material, may also be added if desired. a) Normal module xm n b) Normal pressure angle at referencecylinder 20! n c) Cutter number N x d) Range of teeth xz to x 2 z e) Cutting depth x mm CD f) The number of this British Standard, i.e.BS2518
30、-2. h aBS2518-2:1977 2 BSI 12-1999 10 Ordering instructions It is recommended that the purchaser should state a) the number and Part of this British Standard; b) quantity of cutters required; c) module; d) normal pressure angle at reference cylinder; e) cutter number; f) diameter and width of cutter
31、; g) size of bore and keyway; h) material of cutter. Table 1 Standard group (eight cutters) NOTEThe use of the shouldered type of cutter is at the makers discretion. Figure 1 Rotary form relieved gear cutters Cutter number For number of teeth inspur gear 1 2 3 4 5 6 7 8 135 to rack 55 to 134 35 to 5
32、4 26 to 34 21 to 25 17 to 20 14 to 16 12 and 13BS2518-2:1977 BSI 12-1999 3 Table 2 Dimensions of module pitch 20 pressure angle gear cutters (seeFigure 1) All dimensions are in mm. Module Outside diameter D Bore diameter d Width of cutter Tolerance u 25 25 m n Tolerance H7 a No. 1 No. 2 No. 3 No. 4
33、No. 5 No. 6 No. 7 No. 8 1.0 63 22 5.0 1.25 1.50 63 22 6.0 6.0 6.5 6.5 1.75 6.5 6.5 7.0 7.0 2.00 63 22 7.0 7.0 8.0 8.0 2.25 7.5 7.5 8.5 8.5 2.50 71 27 8.0 8.5 9.0 9.5 2.75 9.0 9.5 10.0 10.5 3.0 80 27 9.5 10.0 11.0 11.5 3.5 11.0 11.5 12.5 13.0 4.0 12.5 13.5 14.0 15.0 4.5 90 27 13.5 14.5 15.5 16.5 5.0
34、14.5 15.5 17.0 18.0 5.5 16.0 17.0 18.5 20.0 6.0 112 32 18.0 19.0 20.0 21.5 7.0 20.0 21.5 23.0 25.0 8.0 125 32 23.0 25.0 26.5 29.0 9.0 26.0 27.0 29.0 31.0 10.0 140 40 27 28 29 30 31 32 33 34 11.0 30 31 32 33 34 35 36 38 12.0 160 40 33 34 35 36 38 39 40 42 14.0 38 39 40 42 43 45 46 47 16.0 180 50 43 4
35、5 47 48 50 52 54 55 18.0 200 50 48 50 52 53 54 57 59 60 20.0 52 54 55 58 60 62 64 65 25.0 224 50 64 66 68 71 74 77 79 81 a See BS 4500-1 +0.25 0 +0.38 0BS2518-2:1977 4 BSI 12-1999 Form of rack between points A and B is straight at 20 with centreline. This basic rack has been derived from the British
36、 Standard rack (BS436-2) with modifications to allow cutters to be used over a range of teeth when the cutter is designed to produce a standard uncorrected gear having the smallest number of teeth in the range which the cutter is intended to cut. Figure 2 20 pressure angle composite basic rack tooth
37、 profile for unit module pitchBS 2518-2:1977 BSI 12-1999 5 Table 3 Profile dimensions for unit module 20 pressure angle rotary gear cutters (seeFigure 3) NOTEIn setting out the profile, s is marked on the reference line and the centre of the arc of radius R1 is located by the coordinates A1 and B1.
38、R1 itself does not necessarily pass through the intersection of the profile with the reference line. (See also6.1.) Figure 3 Cutter tooth profile All dimensions are in mm. Cutter number R1 A1 B1 R2 A2 R3 A3 R4 A4 R5 A5 B5 R6 R7 A7 s 1 23.209 8.188 21.716 2.966 0.598 0.250 5.331 1.271 1.571 1.246 2 9
39、.425 3.462 8.766 2.884 0.686 0.250 6.011 1.413 1.571 1.239 3 6.826 2.635 6.297 2.820 0.769 5.424 2.085 0.250 6.870 1.582 1.570 1.232 4 7.850 3.349 7.094 2.435 0.654 4.446 1.770 3.114 1.299 0.250 9.222 2.181 1.570 1.226 5 7.101 3.203 6.329 2.302 0.655 3.591 1.477 2.264 1.003 0.250 12.218 2.856 1.569
40、1.221 6 3.716 1.615 3.347 2.650 0.981 2.202 0.960 0.250 15.145 3.264 1.569 1.214 7 3.200 1.468 2.843 1.700 0.790 Join R3 and R5 by a common tangent 0.900 0.520 1.100 0.434 1.567 1.206 8 1.830 0.849 1.621 2.920 1.407 1.094 0.579 4.742 1.357 0.860 0.518 1.038 0.480 1.566 1.199 h aBS2518-2:1977 6 BSI 1
41、2-1999 Table 4 Tolerance on tooth thickness (seeFigure 3) Table 5 Dimensions of keyways All dimensions are in mm. Cutter module Tolerance Cutter module Tolerance Up to and including 1.25 + 0.050 + 0.010 over 4 to 5 + 0.150 + 0.025 over 1.25 to 2.75 + 0.075 + 0.025 over 5 to 7.25 + 0.175 + 0.050 over
42、 2.75 to 3.50 + 0.100 + 0.025 over 7.25 to 14 + 0.250 + 0.130 over 3.50 to 4.0 + 0.125 + 0.025 over 14 + 0.300 + 0.150 NOTEThe tolerances for cutters over7.25 module include an allowance for extra side relief. (SeeAppendix B.) Figure 4 Keyway All dimensions are in mm. Diameter of bore d Tolerance H7
43、 a Width of keyway b Tolerance C11 a Diameter plus height of keyway c Tolerance on c Corner radii of keyway r Tolerance on r 22 6 24.1 +0.1 0 1.0 0 0.3 27 7 29.8 +0.2 0 1.2 32 8 34.8 40 10 43.5 50 12 53.5 1.6 0 0.5 a See BS 4500-1. Figure 5 Key for arborBS2518-2:1977 BSI 12-1999 7 Table 6 Dimensions
44、 of keys for arbors All dimensions are in mm. Diameter of arbor Nominal size of key Diameter plus height of key Tolerance on Chamfer Tolerance on d Tolerance h6 b b Tolerance h9 b h Tolerance h11 b c c s s 22 6 23.6 0 0.1 0.25 +0.15 0 27 7 29.0 0 0.2 32 8 7 34.0 40 10 8 42.5 +0.20 0 50 12 8 52.5 0.4
45、0 NOTE 1Tolerance on b for keyway in arbor: for free keying H9 b ; for close keying N9 b b See BS 4500-1.BS2518-2:1977 8 BSI 12-1999 Appendix A Milled gears intended to mesh with generated gears When gears milled by standard rotary form relieved gear cutters are required to mesh with gears generated
46、 in accordance with BS 436-2, it is necessary to side-cut the gear teeth in order to reduce their thickness. This may only be done by indexing the gear blank on its own axis. Table 7 gives the appropriate reduction of tooth thickness for a gear side-cut for this purpose. Table 7 Reduction of tooth t
47、hickness of milled gear teeth for cutters of unit module For a gear milled to mesh with a generated gear of more than140 teeth, the amount of reduction in the chordal tooth thickness is equal to the difference between the crest width of the generated gear tooth and 0.7885mm. NOTEThe above correction
48、s are for cutters of unit module: for any other module, the values given must be multiplied by the module. Appendix B Form relief (see Figure 1) When the cutting edges of form-relieved milling cutters make an angle less than 7“ with a perpendicular to the axis of rotation, normal circumferential rel
49、ief fails to produce sufficient side clearance to avoid rubbing. Since excessive circumferential relief tends to weaken the cutting edges at the periphery, it is advantageous to provide a certain amount of side relief on cutters where the above conditions apply. On cutters numbers6 to8 inclusive for pitches over7.25 module, the tolerances on tooth thickness have been increased to permit extra side relief. Sufficien
