切削用量与生产率的关系

切削用量与生产率的关系切削加工生产率P为30101pppmwwnfavfaPAvfathLdLZ(2-23)刀具耐用度一定时，切削用量之间的关系vvxypCvaf(2-24)硬质合金车刀干切碳素钢时，xv=0.15，yv=0.35。代入上式得0.150.35pCvaf(2-25)(1)当f不变，ap增至3ap时vfaCfaCvppap85.085.0335.015.035.015.03即v降低了15%，根据(2-23)，其生产率为PafvAPpap6.2385.003即生产率提高至2.6倍。(2)当ap不变，f增至3f时vfaCfaCvppf68.068.03335.015.035.015.03即v降低了32％，根据(2-23)，其生产率为PfvaAPpf2368.003即生产率提高至2倍。由此可见，增大ap比增大f更有利于提高生产率。但是ap的选择常受到工序余量的限制，一旦确定之后，ap=常数，则式（2-23）可表达为0PAvf(A)式中A0=A0ap式（2-24）变为vyCvf(B)11vvyyCfv(C)式中vxpCCa故1101vvyyPACfCf(D)式中C1=A0C或者111021vvvyyyvPACCvv(E)式中120vyCAC。xv=0.15，yv=0.35。f增大至3倍时，由式(D)得10.353132.04fPCfP(G)当v增大到3倍时，由式(E)得PvCvCPv13.013.0335.0/11235.0/1123(H)由上式可知，当f增大至3倍时，生产率增大到2.04倍；v增大至3倍时，生产率反而下降到0.13倍。陈日曜《金属切削原理》补充题：ap=常数时，分别计算f和v增大至3倍时的生产率变化。但是ap的选择常受到工序余量的限制，一旦确定之后，ap=常数，则式（11-3）可表达为0PAvf(A)式中A0=A0ap式（11-4）变为23Cvf(B)3232Cfv(C)式中13vpCCa故131301PACfCf(D)式中C1=A0C或者32121202PACvCv(E)式中3220CAC。f增大至3倍时，由式(D)得131331131.441.44fPCfCfP(G)当v增大到3倍时，由式(E)得1/21/232230.580.58vPCvCvP(H)由上式可知，当f增大至3倍时，生产率增大到1.44倍；v增大至3倍时，生产率反而下降到0.58倍。184页第5题vvvvxympCvkTafvvvvxympCvkTaf0.650.651.440.45MvbkkSv=1ktv=1kkrv=1.13kkrv=0.97krv=0.97kBv=1kv=1.53xv=0.15yv=0.2Cv=291m=0.20.20.150.22911.53191.25m/min6030.5vvvvxympCvkTaf1vvmvvxypCTkvafkkrv=0.81kv=1.1150.150.22911.111.52min191.2530.5vvmvvxypCTkvaf184页第6题xv=0.15yv=0.2Cv=291m=0.20.20.150.2291180m/min601.50.3vvvvvxympCvkkTaf得kv=1.17f=0.6mm/r150.150.352421.1717.37min1801.50.6vvmvvxypCTkvaff=0.9mm/r150.150.452351.177.78min1801.50.9vvmvvxypCTkvaff=1.2mm/r150.150.452351.174.07min1801.51.2vvmvvxypCTkvafap=3mm150.150.22911.1735.41min18030.3vvmvvxypCTkvafap=4.5mm150.150.22911.1726.12min1804.50.3vvmvvxypCTkvafap=6mm150.150.22911.1721.05min18060.3vvmvvxypCTkvaf184页第7题设kv=1甲工人：xv=0.15yv=0.2Cv=291m=0.20.20.150.2291125.33m/min60100.2vvvvxympCvkTaf000125.330.210250.66pPAvfaAA甲乙工人：xv=0.15yv=0.35Cv=242m=0.20.20.150.35242115.5m/min6050.4vvvvxympCvkTaf000115.50.45231pPAvfaAA乙丙工人：xv=0.15yv=0.35Cv=242m=0.20.20.150.35242104.1m/min60100.4vvvvxympCvkTaf000104.10.410416.4pPAvfaAA丙生产率顺序：丙工人甲工人乙工人甲工人比乙工人生产率高的原因是：v高于乙工人；丙工人比甲工人生产率高的原因是：虽然v有所降低，但f增大了1倍；丙工人比乙工人生产率高的原因是：虽然v有所降低，但ap增大了1倍；所以，在刀具寿命相同的情况下，对提高生产率作用的顺序是：apfv。