机械5

摘要 本设计是车床拨叉零件的加工工艺及专用夹具设计。从零件的结构外型分析，它的外型复杂，且不易加工，因此该零件选用是铸造件。它的主要加工面是孔、拨叉叉口两端面和槽，在加工中由于面的加工精度要比孔的加工精度容易保证。因此，在设计中采用先面后孔的原则，并将孔与平面的加工划分为粗加工和精加工阶段，以保证加工精度。在本设计中，先以一个面加工出一个基准面，然后，再以该基准面加工相应的孔。在后面的工序中，均以该孔为定位基准，加工拨叉叉口两端面、孔、底平面、槽和斜平面，在整个加工过程中，分别采用了铣床、钻床和镗床。并设计了铣侧面、镗孔和铣槽等的专用夹具，并对它们的定位都采用了一面两销定位。由于该零件的尺寸不大，所需的夹紧力不大。因此，夹紧方式都采用手动夹紧，它的夹紧简单，机构的设计更为方便，满足夹紧要求。 关键词拨叉零件，加工工艺，专用夹具，定位，夹紧 ABSTRACT This desig
n is a lather plectrum parts processi
ng a
nd special fixture desig
ns. Parts from the appeara
nce of the structure, its appeara
nce complex a
nd difficult process, so the selectio
n of parts is casti
ng.The parts are cast parts. I
n the processi
ng, it is easier to e
nsure the processi
ng accuracy of pla
ne tha
n the hole. So the parts’ mai
n pla
nes are hole, two blades of the Plectrum a
nd groove. Therefore, i
n the desig
n, it adopts the pri
nciple of pla
ne first a
nd hole seco
nd a
nd divides the hole a
nd pla
ne’s worki
ng i
nto exte
nsive a
nd i
nte
nsive processi
ng stages so as to e
nsure the accuracy. I
n this desig
n, firstly, it uses the pla
ne to work a datum; seco
ndly, it uses the datum to work accordi
ng hole. A
nd i
n the latter process of worki
ng, it also takes hole as the poiso
ni
ng base a
nd works the two bales of Plectrum, hole, bottom pla
ne, groove a
nd i
ncli
ned pla
ne. I
n the e
ntire machi
ni
ng process, it uses separately the milli
ng machi
ne, driller a
nd bori
ng machi
ne. A
nd the desig
n aspect of milli
ng, bori
ng a
nd milli
ng ducts special fixture. They also have adopted the positio
ni
ng of a two marketi
ng positio
ni
ng. Accordi
ng to the requireme
nt, it desig
ns the special fixture. For the size of parts is
not very big, it does
n’t require stro
ng clampi
ng force. Therefore, methods of clampi
ng are ma
nual clampi
ng; that is because it is simple a
nd the desig
n is more co
nve
nie
nt to meet the requireme
nts of clampi
ng. Keywords Plectrum Parts, Processi
ng, Special Fixture, Positio
ni
ng, Clampi
ng 目录 摘要I ABSTRACT II 1绪论1 2零件的分析2 2.1零件的作用2 2.2拨叉831006的工艺分析2 2.3拨叉831006的工艺2 2.3.1加工要求2 2.3.2平面的加工3 2.3.3大头孔的加工3 2.3.4小头孔的加工3 2.4本章小结3 3工艺规程设计5 3.1确定毛坯的制造形式5 3.2加工工艺过程5 3.3基面的选择5 3.3.1粗基准的选择5 3.3.2精基准的选择6 3.4工艺路线的拟订6 3.4.1确定工序的原则6 3.4.2工序的特点7 3.4.3加工精度的划分8 3.4.4制定工艺路线8 3.5本章小结10 4工序参数选择、计算11 4.1毛坯的确定11 4.1.1毛坯的工艺要求11 4.1.2毛坯形状、尺寸要求11 4.2拨叉831006的偏差计算12 4.2.1拨叉平面的偏差及加工余量计算12 4.2.2大小头孔的偏差及加工余量计算13 4.2.3粗、精铣槽14 4.3确定切削用量及基本工时（机动时间） 14 4.3.1工序1：粗、精铣孔上平面14 4.3.2工序2：加工孔到要求尺寸16 4.3.4工序4粗、精镗孔21 4.3.5工序5：粗、精铣下平面22 4.3.6工序6：粗、精铣槽24 4.3.7工序7粗铣斜平面25 4.3.8工序8铣断26 4.4时间定额计算及生产安排27 4.4.1粗、精铣孔上平面27 4.4.2钻、扩、铰孔27 4.4.3粗、精铣两侧面28 4.4.4粗、精镗孔28 4.4.5粗、精铣下平面29 4.4.6粗、精铣槽29 4.4.7粗铣斜平面29 4.4.8铣断29 4.5本章小结30 5钻φ25孔夹具设计31 5.1问题的提出31 5.2定位基准的选择31 5.3切削力和卡紧力计算31 5.4定位误差分析31 5.5卡具设计及操作的简要说明31 结论32 参考文献33 致谢34