1、BRITISH STANDARD BS 4656-26: 1980 Specification for The accuracy of machine tools and methods of test Part 26: Gear shaping machines UDC 621.9.01187.001.4:621.833.002.2:621.912.3BS4656-26:1980 This British Standard, having been prepared under the directionof the Mechanical Engineering Standards Comm
2、ittee, was published underthe authority of the Executive Board and comesintoeffect on 30June1980 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference MEE/6 Draft for comment78/80897 DC ISBN 0 580 11438 4 Cooperating organizations The Mechanical Engineerin
3、g 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 Department of the Environment Association of Consulting Engineers
4、 Department of Trade (Marine Division) Association of Hydraulic Equipment Engineering Equipment Users Association Manufacturers Federation of Manufacturers of Construction Association of Mining Electrical and Equipment and Cranes Mechanical Engineers Health and Safety Executive British Compressed Ai
5、r Society Institution of Gas Engineers British Electrical and Allied Manufacturers Institution of Mechanical Engineers* Association (BEAMA) Institution of Plant Engineers British Gas Corporation Institution of Production Engineers* British Gear Manufacturers Association London Transport Executive Br
6、itish Internal Combustion Engine Machine Tool Industry Research Association* Manufacturers Association Ministry of Defence* British Pump Manufacturers Association National Coal Board British Steel Corporation Oil Companies Materials Association British Steel Industry Process Plant Association Charte
7、red Institution of Building Services Railway Industry Association of Great Britain Crown Agents for Oversea Governments and Society of Motor Manufacturers and Traders Administrations Limited Department of Industry (Mechanical Telecommunication Engineering and Engineering)* Manufacturing Association
8、(TEMA) Department of Industry (National Water-tube Boilermakers Association Engineering Laboratory) The 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: Ball and R
9、oller Bearing Manufacturers University of Aston in Birmingham Association University of Manchester (Institute of Science Department of the Environment (PSA) and Technology) Federation of British Engineers Tool Individual experts Manufacturers Amendments issued since publication Amd. No. Date of issu
10、e CommentsBS4656-26:1980 BSI 10-1999 i Contents Page Cooperating organizations Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Application of test methods 1 4 Abbreviations 1 5 Diagrams 1 6 Practical test 1 7 Accuracy of cutter and workspindle indexing worms and wormwheels 2 8 Cutter regis
11、ter diameter 3 Table 1 Tolerances on test gear blanks 2 Table 2 Geometrical tests and accuracy requirements for gear shaping machines 4 Publications referred to Inside back coverBS4656-26:1980 ii BSI 10-1999 Foreword This Part of this British Standard has been prepared under the direction of the Mec
12、hanical Engineering Standards Committee. It has been developed following consideration of an initial proposal prepared by the Machine Tool Trades Association for the revision of BS3329:1961 “Specification for gear planing and shaping machines”. For convenience it was decided to produce the revision
13、of BS3329 in two Parts, one dealing with gear planing machines and one dealing with gear shaping machines. BS3329:1961 is now withdrawn. The format of this standard has been revised to accord with that now used for the general series of standards dealing with machine tool tests known as the BS4656 s
14、eries. 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 com
15、prises a front cover, an inside front cover, pagesi andii, pages1 to8, 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.BS4656-26:1980 BSI 10-19
16、99 1 1 Scope This Part of this British Standard specifies, with reference to BS3800, both geometrical and practical tests for gear shaping machines, horizontal and vertical spindle types, having a workpiece diameter capacity of up to1600mm, used for the production of external and internal spur and h
17、elical gears, and gives the corresponding permissible deviations which apply. It applies only to machines which use pinion type cutters. These cutters have a rotary motion. This standard is applicable to machines of high accuracy and to machines of general purpose use and normal accuracy. It deals o
18、nly with the verification of accuracy of the machine. It does not apply to the testing of the running of the machine (vibrations, abnormal noises, stick-slip motion of components, etc.), nor to its characteristics (speeds, feeds, etc.) which should generally be checked before testing accuracy. 2 Ref
19、erences The titles of the publications referred to in this standard are listed on the inside back cover. 3 Application of test methods 3.1 In applying the tests detailed in Table 2, reference should be made to BS3800, especially concerning the installation of the machine before testing, warming up o
20、f spindles and other moving parts, the description of measuring methods and the recommended accuracy of testing equipment. Levelling of the machine should be carried out in accordance with the manufacturers instructions before testing accuracy. 3.2 The tests may be applied in any order that is pract
21、icable and that makes for ease of mounting of instruments or gauging. The sequence in which the geometrical tests are listed in Table 2 is related to the sub-assemblies of the machine and it is not intended to impose the practical order in which the tests are to be done. 3.3 When inspecting a gear s
22、haping machine, it is necessary to carry out all the tests specified in this standard where applicable. 3.4 When establishing the tolerance for a measuring range different from that given in this standard (see2.311 of BS3800:1964), it should be taken into consideration that the minimum value of tole
23、rance is0.001mm for geometrical and practical tests. 4 Abbreviations For the purposes of this standard, various methods of expressing permissible deviations are employed, each having a particular type of application. The methods employed are as follows. 5 Diagrams For reasons of simplicity, the diag
24、rams in this standard illustrate only one type of machine. 6 Practical test 6.1 General 6.1.1 Object of test. The object of this test is to verify the geometry of the machine by cutting a test piece under lightly loaded conditions. 6.1.2 Spur gears. A test spur gear shall be cut for one specified di
25、rection of rotation of the table or work spindle and measured for pitch and tooth alignment errors. If cutting in both directions is required, this is subject to special arrangement between purchaser and manufacturer. 6.1.3 Helical gears. If the machine is required for cutting helical gears, an addi
26、tional test gear with helical teeth shall be cut for one specified direction of rotation and measured for helix angle, lead, or axial pitch. If cutting in both directions is required, this is subject to special arrangements between purchaser and manufacturer. 6.1.4 Diameter of test gear. The diamete
27、r of the test gear shall be equivalent to at least60%, unless otherwise agreed, of the capacity of the machine and the face width of the test gear blank shall be equivalent to at least20% of the capacity of the machine for width or20mm whichever is the greater. - - -/- - - This type of expression ap
28、plies to deviations of perpendicularity that are ratios. - - - for any length of - - - This type of expression applies to deviations of straightness and parallelism, and is used in fact for local permissible deviations, the measurement length being obligatory. - - - per - - - This type of expression
29、 applies to deviations of straightness and parallelism, and is used to recommend a measurement length, but in this case the proportionality rule comes into operation if the measurement length differs from that indicated.BS4656-26:1980 2 BSI 10-1999 6.1.5 Accuracy requirements for test gears. Test ge
30、ars shall comply with the following requirements of BS436-2. Tolerances on tooth alignment are related to a proportion or to the whole of the face width b (in mm) of the gear and apply up to a maximum of b=150mm. NOTEThere is only limited data available on which to base tolerances for gears of great
31、er face width than150mm, for which (as with all gears) the ultimate test is accuracy of meshing. 6.1.6 Tooth helix. The mean permissible deviation in the lead of tooth helix shall be calculated by averaging the error of four teeth equispaced around the gear. 6.1.7 Tooth weave. The difference between
32、 any two alignments checked on similar gear tooth flanks over the entire face width of the gear shall be within the mean alignment tolerances allowed in6.1.5. 6.1.8 Tooth taper. The difference between any two alignments checked on opposing flanks of the same gear tooth or gear tooth space shall be w
33、ithin the mean alignment tolerances allowed in6.1.5. 6.2 Blank requirements and cutting requirements. The manufacturer shall select the test gear material, cutter and cutting data in such a manner that the surface texture generated is satisfactory for measuring purposes. The test gear shall, at the
34、discretion of the manufacturer, be produced employing light finishing cuts. For normal accuracy machines it is recommended that a cutter complying with the requirements of grade AA of BS5246 be used. For helical cutters and for all cutters outside the scope of BS5246, the requisite cutter quality is
35、 left to the machine manufacturers discretion. The accuracy of the test gear blank shall be consistent with the grade of gear as specified in BS436-2 and as reproduced in Table 1. Table 1 Tolerances on test gear blanks 7 Accuracy of cutter and workspindle indexing worms and wormwheels 7.1 Normal acc
36、uracy machines. The workspindle worm and wormwheel should comply with the following requirements. a) Wormwheel. Adjacent and cumulative pitch tolerance: 1.25+3.34m where l is any selected length of arc (in millimetres) not greater than;d/2. b) Worm. Adjacent pitch tolerance:0.010mm. Cumulative pitch
37、 tolerance over any five pitches:0.025mm. c) Cyclic error. The average cyclic error for each separate flank shall not exceed0.008. Local departures from uniformity within any convolution shall not exceed a total range of0.010. The cyclic error of the main worm is the total range of difference in any
38、 convolution in a direction parallel to the axis between the position of the actual helix and a true helix having a lead equal to the lead of that convolution. Characteristic High accuracy machines Normal accuracy machines Adjacent and cumulative pitch tolerance: spur gears helical gears Grade6, 2.5
39、 + 6.3 4m Grade7, 3.55 + 9.0 4m Grade7, 3.55 + 9.0 4m Grade8, 5.0 + 12.5 4m Alignment of teeth tolerance: spur gears helical gears Grade6, 1.0 + 5.0 4m Grade7, 1.25 + 6.3 4m Grade7, 1.25 + 6.3 4m Grade8, 2.0 + 10.0 4m Where l=any selected length of arc (in mm) not greater than ;d/2.llllbbbb All valu
40、es in micrometres (4m) except tip diameter d ain millimetres. Characteristic High accuracy machines Normal accuracy machines Tolerances for grade5 gear Tolerances for grade7 gear Bore size tolerance a IT5 b IT7 b Shaft size tolerance a IT5 b IT6 b Radial runout of tip cylinder 0.16d a +10 0.25d a +1
41、5 Radial runout of reference surface Axial runout of reference surface Blank diameter IT7 b IT8 b a Where the tip cylinder (blank diameter) is used as a datum for a checking instrument. b The IT values are the internationally agreed fundamental tolerances of BS4500-1, to which reference should be ma
42、de.lBS4656-26:1980 BSI 10-1999 3 7.2 High precision machines. The workspindle worm and wormwheel should comply with the following recommendations. a) Wormwheel. Adjacent and cumulative pitch tolerance: 0.65+1.6 4m where l is any selected length of arc (in millimetres) not greater than;d/2. b) Worm.
43、Adjacent pitch tolerance:0.004mm. Cumulative pitch tolerance over any five pitches:0.008mm. c) Cyclic error. The average cyclic error for each separate flank shall not exceed0.004. Local departures from uniformity within any convolution shall not exceed a total range of0.005. The cyclic error of the
44、 main worm is the total range of difference in any convolution in a direction parallel to the axis between the position of the actual helix and a true helix having a lead equal to the lead of that convolution. 7.3 General procedure for measurement of cyclic error. Readings shall be taken on each fla
45、nk separately at approximately mid-depth and continued for at least three convolutions of the worm near the middle of the worm face and for not less than six equally spaced angular positions in each of these convolutions. 7.4 Testing the assembly of the worms and wormwheels in the machine 7.4.1 Rela
46、tive motion errors. It is recommended that, whenever practicable, the relative circumferential motion errors in the assembled transmissions of the cutter index and work table drive units be tested. On machines in which the axes of the cutter spindle and the work table can be co-axially aligned, this
47、 test may be accomplished by attaching to the cutter spindle an appropriate indicator or recording device and registering on a datum surface attached to the work table. The cutter spindle and work table are then rotated simultaneously at a ratio of unity at least through360 . After the initial test,
48、 the procedure should be repeated three times with one of the units being displaced through90 each time. NOTEThis test is optional and should not replace the conventional cutting tests. 7.4.2 Tolerances on relative motion errors. The maximum error revealed by the four tests in7.4.1 shall be within t
49、he following. a) Normal accuracy machines For normal accuracy machines the tolerances on relative motion errors between cutter index and work table shall be within 2 (1.25 +3.3)+204m =2.5 +26.64m where r = work wormwheel radius at which the measurement is taken in millimetres. b) High precision machines For high precision machines the tolerances on relative motion errors between cutter index and work table shall be within 2 (0.65 +1.6)+204m =1.3 +23.24m where r = work wormwheel radius at which the measurement is taken in millimetres. 8 Cutter register diameter
