1、406060End face End face grindinggrinding 15153535Super-lappingSuper-lapping0.20.20.30.3 End surface finish End surface finish turningturning 30304040Surface grindingSurface grinding20203030polishingpolishing2 25 5 drillingdrilling40406060Rough planingRough planing40405050 The The tolerance tolerance
2、 of of includes includes the the geometrical geometrical shape shape error, error, such such as as the the degree degree of of coning, coning, ellipsing ellipsing and and surface surface flatness. flatness. The The size size of of can can be be decided decided according according to to the the toler
3、ance tolerance of of the the selected selected machining machining method, method, which which can can be be found found in in handbooks handbooks and and in in information information booklets booklets provided provided by by metal metal cutting cutting manufacturers. manufacturers. The The relatio
4、nship relationship between between metal metal removal removal and and operation operation dimensional tolerance is shown in Fig.3-9-2.dimensional tolerance is shown in Fig.3-9-2. * * 5 5 SCUTSCUT 3.9.2.2 It is affected by the tolerance Ta of the accurate operation3.9.2.2 It is affected by the toler
5、ance Ta of the accurate operation Fig 3.44 the relationship between metal removal and operational toleranceFig 3.44 the relationship between metal removal and operational tolerance Fig.(a) shows the operation on an external cylindrical surface ( here called surrounded Fig.(a) shows the operation on
6、an external cylindrical surface ( here called surrounded Surface Surface 被包容面被包容面). the current metal removal Zb is). the current metal removal Zb is： （a) a) moviemovie(b)(b)moviemovie * * 6 6 SCUTSCUT The maximum metal removal: The maximum metal removal: Z Zbmax bmax=L =Lamax amax-L -Lbmin bmin The
7、 minimum metal removal: The minimum metal removal: Z Zbmin bmin=L =Lamin amin-L -Lbmax bmax For the surrounding surfaces, the maximum metal removal and minimum For the surrounding surfaces, the maximum metal removal and minimum metal removal are:metal removal are: Z Zbmax bmax=L =Lbmax bmax-L -Lamin
8、 amin Z Zbmin bmin=L =Lbmin bmin-L -Lamax amax It is obvious that the preceding operational tolerance will influence the size of It is obvious that the preceding operational tolerance will influence the size of the current operation, since the tolerance of the metal removal is the current operation,
9、 since the tolerance of the metal removal is Z=Z Z=Zmax max-Z -Zmin min=T =T a a +T+T b b * * 7 7 SCUTSCUT 3.9.2.3 It is affected by the relative position error 3.9.2.3 It is affected by the relative position error （ ）betweenbetween the preceding machined surfaces the preceding machined surfaces The
10、 The error error of of includes includes the the degree degree of of the the linearity, linearity, the the parallelism parallelism between between axes, axes, the the perpendicularity perpendicularity between between axis axis and and surface, surface, coaxiality coaxiality between between inner inn
11、er and and external external surfaces, surfaces, and and flatness flatness of of surface. surface. These These kinds kinds of of error error should should be be corrected corrected in in the the current current operation operation so so as as to to ensure ensure the the machining quality.machining q
12、uality. * * 8 8 SCUTSCUT 3.9.2.4 It is affected by the current clamping error 3.9.2.4 It is affected by the current clamping error（ ） The The error error includes includes both both the the positioning positioning and and clamping clamping error, error, as as well well as as the the manufacturing ma
13、nufacturing error error of of the the fixture.fixture. Its Its value value is is the the vector vector sum sum of of the the above above three three variables. variables. It It will will directly directly affect affect the the relative relative position position between between the the surface surfa
14、ce and cutting tool.and cutting tool. A A vector vector sum sum should should be be used used to to evaluate evaluate their their resultant resultant influence influence on on metal metal removal. removal. The The influence influence of of various various factors factors on on metal metal removal re
15、moval is is schematically schematically shown inshown in Fig.3.45Fig.3.45 * * 9 9 SCUTSCUT Fig.Fig.3.45 Factors influencing the metal removal3.45 Factors influencing the metal removal moviemovie Rotating axisRotating axis the workpiece the workpiece Axis Axis After machiningAfter machining Before Be
16、fore machiningmachining * * 1010SCUTSCUT 3.9.3 Method of planning the metal removal3.9.3 Method of planning the metal removal 3.9.3.1 calculation method3.9.3.1 calculation method The The following following formula formula can can be be obtained obtained based based on on the the analysis analysis o
17、f of the the above above factors factors according according to to Fig.5-1Fig.5-13, 3,The The basic basic bilateral bilateral metal metal removal removal ( (双边余量）双边余量）for for a a symmetrical symmetrical surface, such as a hole or axis, is:surface, such as a hole or axis, is: or or The The basic basi
18、c unilateral unilateral metal metal removalremoval（单边余量）（单边余量） for for an an unsymmetrical unsymmetrical surface surface (such as a plane) is:(such as a plane) is: * * 1111SCUTSCUT 3.9.3.2 Method of looking up tables3.9.3.2 Method of looking up tables This This method method is is widely widely used
19、 used in in factories. factories. The The table table is is prepared prepared according according to to the the production production practice practice and and experimental experimental research research work work of of the the factory, factory, as as well well as as modification modification after
20、after considering considering the the specific specific machining machining condition.condition. The The appropriate appropriate rate rate of of metal metal removal removal can can be be found found in in handbooks handbooks and and in in information booklets provided by metal cutting manufacturers.
21、information booklets provided by metal cutting manufacturers. * * 1212SCUTSCUT This This method method is is mainly mainly used used in in single single or or small small batch batch type type production, production, and and the the metal metal removal removal rate rate is is estimated estimated by
22、by experience, experience, thus thus It It is is not not very very accurate. It causes high reject ratesaccurate. It causes high reject rates（废品率）（废品率）. . * * 1313SCUTSCUT 3.9.3.3 3.9.3.3 Experiential method Experiential method 3.9.4 Dimensional Chains3.9.4 Dimensional Chains 3.9.4.1 The concept of a dimensional chain 3.9.4.1 The concept of a dimensional chain In In mechanical mechanical design design and and technical
