(3) resultant motion and velocityWhenthemain motion and thefeed motiontakepart incuttingsimultaneously,the velocityin one pointof thecuttingedge relativetotheworkpieceis calledresultantcuttingmotion,its sizeanddirectioncanberepresentedwithavectorVe,shownasFigl3,anditequalsthevectorsum ofthetwomotions(1.1)Ve=Ve+Vf上页下页退出址
When the main motion and the feed motion take part in cutting simultaneously, the velocity in one point of the cutting edge relative to the workpiece is called resultant cutting motion, its size and direction can be represented with a vector ve, shown as Fig.1.3, and it equals the vector sum of the two motions ve=vc+vf (1.1) （3）resultant motion and velocity
Fig.1.3 The resultantvelocity in cutting上页下页退出S返回
Fig.1.3 The resultant velocity in cutting
1.1.1.2 Three elements in cuttingVefapare calledthethreeelements incutting(1)CuttingspeedMost ofthe main cutting motions are rotational motion.Thevelocityinonepointoftherotatingbody(cuttingtoolorworkpiece)canbecalculatedusingthefollowingformuladn m/s or m/min(1.2)Vc=1000where d-the rotational diameter of one point in the workpiece or the cutting tool (mm)nnumberofrevolutionpersecondorperminute(r/sorr/min).(r/sorr/min)上页下页退出
1.1.1.2 Three elements in cutting ve、f 、 ap are called the three elements in cutting 1000 dn （1）Cutting speed Most of the main cutting motions are rotational motion.The velocity in one point of the rotating body(cutting tool or workpiece) can be calculated using the following formula vc= m/s or m/min (1.2) where d－the rotational diameter of one point in the workpiece or the cutting tool（mm) n－number of revolution per second or per minute (r/s or r/min). （r/s or r/min)
(2)Feedingspeed,feedandfeedpertoothFeeding speed y,isthefeed inaunittime (m/s orm/min)Feed is the relative displacement between the workpiece and the cutter along thedirectionoffeedingmotionperrevolutionorperstock(mm/r)。For multipleteeth cutting tools, such as milling cutter,reamer, broach, gear hob etcfeedfzmaybemeasured inmillimeters pertooltooth (mm/z).Obviously,(1.3)v-fn=fzznmm/s or mm/min上页下页退出式
Feeding speed vf is the feed in a unit time (m/s or m/min) Feed is the relative displacement between the workpiece and the cutter along the direction of feeding motion per revolution or per stock (mm/r)。 For multiple teeth cutting tools, such as milling cutter, reamer, broach, gear hob etc. feed fz may be measured in millimeters per tool tooth (mm/z). Obviously， vf=f·n=fz·z·n mm/s or mm/min （1.3） （2） Feeding speed, feed and feed per tooth
(3) Back engagement of the cutting edgeFor turningand planing,the back engagement ofthecuttingedge a,isequal to the normal distancebetween the machined surface and the workpiecesurfacetobecut(mm).Forcylindrical turning,(1.4)ap=（dw-dm）/2mmFordrillingap=dm/2(1.5)mmwheredmdiameter of machined surface (mm)dwdiameterofworkpiece surfacetobecut (mm)上页下页退出
（3）Back engagement of the cutting edge For turning and planing, the back engagement of the cutting edge ap is equal to the normal distance between the machined surface and the workpiece surface to be cut(mm). For cylindrical turning, ap =（dw-dm）/2 mm (1.4) For drilling ap =dm/2 mm (1.5) where dm——diameter of machined surface（mm） dw——diameter of workpiece surface to be cut（mm）