机械5

摘要 本次设计是车床变速箱中拔叉零件的加工工艺规程及一些工序的专用夹具设计。此拔叉零件的结构较为复杂，其加工的地方主要是孔和平面。本设计先加工孔后加工面。将孔与平面的加工明确划分成粗加工和精加工阶段以保证它们的加工精度。基准选择以拔叉右面的最大的平面作为粗基准，来加工中间的通孔，然后以此加工过的孔作为精基准。主要加工工序安排是先以中心孔定位加工出顶平面和右侧平面以及下面的大孔的两平面，再以中心孔定位加工出下端的大孔。加工时是用镗床镗孔。最后以这两个孔为基准，分别加工右侧的槽和顶面的螺纹底孔。整个加工过程选用了钻床、铣床和镗床。工件在机床上定位夹紧选用专用夹具，夹紧方式为手动夹紧，夹紧可靠，操作方便。因此生产效率较高，适用于大批量、流水线上加工。能够满足设计要求。 关键词加工工艺，定位，夹紧，专用夹具 ] ABSTRACT This desig
n is a lather to become soo
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nd defi
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ness processes to processwith the
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ntee their process the precise degree.The basis choice to pull out rough basis of co
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nd actio
ns of the biggest flat surface of the right i
n fork,process the i
n the ce
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n be used as the precise basiswith the bore that processed.Processi
ng primarilywork preface arra
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nt is first to process a flat surfacewith the ce
nter bore fixed positio
nwith the right side flat surface a
nd belowbig bore of two flat surface,agai
nwith ce
nter bore the fixed positio
n processes the big bore that carrydow
n.While processi
ng is to use the bori
ng machi
ne bori
ng bore.Regard these two bores as the basis fi
nally,process the right-ha
nd slot respectivelywith the thread bottom bore of the a.Whole processes the process chose to use to the drill machi
ne,millerwith the bori
ng machi
ne.The to
ngs chooses to use the appropriatio
n to
ngs,clippi
ng tightwayas to move to clip tight,clip tight a
nd depe
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n co
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nie
nce.Therefore produce the efficie
ncyhigher,be applicable to the large qua
ntitymeasures,the flowi
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ne to process.Ca
n satisfythe desig
n request. Keywords Process the craft，Fixed positio
n，Clip tight，Appropriatio
n to
ngs 目录 1绪论1 1.1课题背景1 1.2夹具的发展史1 1.3小结2 2拨叉的加工工艺规程设计3 2.1零件的分析3 2.1.1零件的作用3 2.1.2零件的工艺分析3 2.2确定生产类型3 2.3确定毛坯3 2.3.1确定毛坯种类3 2.3.2确定铸件加工余量及形状3 2.3.3绘制铸件零件图4 2.4工艺规程设计4 2.4.1选择定位基准4 2.4.2制定工艺路线4 2.4.3选择加工设备和工艺设备6 2.4.4机械加工余量、工序尺寸及公差的确定6 2.5确定切削用量及基本工时8 2.5.1工序1：粗铣Φ25H7的两侧面8 2.5.3工序3：钻Φ25H7的通孔9 2.5.4工序4：扩Φ25H7的通孔11 2.5.5工序5：铰Φ25H7的通孔12 2.5.6工序6：粗铣a、b面12 2.5.7工序7：粗铣Φ60H12孔的两面14 2.5.8工序8：精铣Φ60H12孔的两面14 2.5.9工序9：粗镗下端Φ60H12的孔15 2.5.10工序10：半精镗下端孔到Φ60H12 16 2.5.11工序11：粗铣16H11的槽16 2.5.12工序12：半精铣16H11的槽17 2.5.13工序13：钻Φ20.50的孔18 2.5.14工序14：攻M22×1.5的螺纹19 2.5.15工序15：铣开Φ60H12的孔20 2.6本章小结21 3专用夹具设计22 3.1设计要求22 3.2夹具设计22 3.3切削力和夹紧力计算22 3.4定位误差分析24 结论25 参考文献26