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Φ40外圆端面夹具，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 the processi
ng tech
nology a
nd special fixture desig
n of lathe fork parts. Accordi
ng to the a
nalysis of the structural shape of the part, its shape is complex, a
nd it is
not easy to process, so the part is cast. Its mai
n machi
ni
ng surface is the two e
nd faces a
nd grooves of the hole a
nd the fork. I
n the machi
ni
ng process, the machi
ni
ng accuracy of the surface is easier to guara
ntee tha
n that of the hole. Therefore, the pri
nciple of "face before hole" is adopted i
n the desig
n, a
nd the machi
ni
ng of hole a
nd pla
ne is divided i
nto rough machi
ni
ng a
nd fi
nish machi
ni
ng to e
nsure the machi
ni
ng accuracy. I
n this desig
n, a datum pla
ne is machi
ned first, a
nd the
n the correspo
ndi
ng holes are machi
ned with the datum pla
ne. I
n the later process, the hole is used as the positio
ni
ng refere
nce to process the two e
nd faces, holes, bottom pla
nes, grooves a
nd i
ncli
ned pla
nes of the fork. I
n the whole process, milli
ng machi
ne, drilli
ng machi
ne a
nd bori
ng machi
ne are used respectively. The jigs for milli
ng Φ 40 outer circle e
nd face are desig
ned, a
nd o
ne side a
nd two pi
ns are used for their positio
ni
ng. Due to the small size of the part, the required clampi
ng force is
not large. Therefore, ma
nual clampi
ng is adopted i
n the clampi
ng mode, which is simple i
n clampi
ng, more co
nve
nie
nt i
n mecha
nism desig
n a
nd meets the clampi
ng requireme
nts. Key words： shift fork parts, processi
ng tech
nology, 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.专用夹具设计31 5.1机床夹具介绍31 5.2现代夹具的发展方向31 5.3机床夹具的定位及夹紧31 5.3.1概述31 5.3.2机床夹具的组成32 5.3.3机床夹具的分类32 5.3.4机床夹具在机械加工中的作用33 5.4工件的装夹方式33 5.5基准及其分类34 5.6工件的定位35 5.7铣床上加工40外圆端面夹具设计35 5.7.1.定位基准的选择35 5.7.2.切削力及夹紧力的计算35 5.7.3.定位误差的分析36 结论37 参考文献38 致谢39