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，设计了铣断的专用夹具。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 lathe fork parts processi
ng tech
nology a
nd special fixture desig
n. From the a
nalysis of the structure a
nd appeara
nce of the part, its appeara
nce is complex a
nd difficult to process, so the part is cast. Its mai
n machi
ni
ng surfaces are the hole, the two e
nd faces of the fork a
nd the groove. I
n the machi
ni
ng process, the machi
ni
ng accuracy of the surface is easier to e
nsure 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 holes a
nd pla
nes is divided i
nto rough machi
ni
ng a
nd fi
nish machi
ni
ng stages to e
nsure the machi
ni
ng accuracy. I
n this desig
n, a datum pla
ne is machi
ned from o
ne surface, a
nd the
n the correspo
ndi
ng holes are machi
ned from this datum pla
ne. I
n the followi
ng process, the two e
nd faces, holes, bottom pla
nes, grooves a
nd i
ncli
ned pla
nes of the fork are machi
ned with the hole as the positio
ni
ng be
nchmark. I
n the whole machi
ni
ng process, a special fixture for milli
ng is desig
ned. Due to the small size of the part, the clampi
ng force required is
not large. Therefore, the clampi
ng mode is ma
nual clampi
ng, which is simple to clamp, a
nd the mecha
nism desig
n is more co
nve
nie
nt to meet 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铣断夹具设计31 5.1问题的提出31 5.2夹具体设计31 5.2.1定位基准的选择31 5.2.2切削力及夹紧力的计算31 5.2.3定位误差分析32 5.2.4夹具设计及操作的简要说明32 设计小结34 参考文献35 致谢36