机械5

摘要 此次设计任务是对拨叉C零件的加工工艺、夹具以及拉刀设计，该工件由于上端面和底槽均与花键孔中心有位置关系，因此在工序安排上，先加工花键孔，再通过花键孔定位加工底槽和上端面，最后攻螺纹孔，其中各种夹具均采用专用夹具，由于该零件的尺寸小，所需的夹紧力不大，因此都采用手动夹紧，它的机构设计简单、方便，且满足夹紧要求。在设计拉刀时，根据零件材料、切削余量等，选择并计算拉刀的各种参数，如拉刀的容屑槽、拉刀齿升量、拉刀齿型及齿数等并根据这些参数画出拉刀工作图。 关键词拨叉C，加工工艺，定位，夹紧，拉刀 ABSTRACT This desig
n is to a
nalyze the processi
ng of plectrum C,to
ngs desig
ns,a
nd pulli
ng k
nife desig
ns,Because duri
ng the machi
ni
ng process,the top e
nd a
nd bottom slot of the workpiece are related to the core positio
n of the key bore.the
n passes to spe
nd key bore fixed positio
n process the bottom slot with top e
nd,offe
nd the chread bore fi
nally.A
nd every ki
nd of to
ngs adopt the appropriatio
n to
ngs.Because such workpiece is small i
n its size a
nd calls for a little clip tight,therefore all to
ngs adopt movi
ng to clip tight.Its arga
nizatio
n desig
n is simple,co
nve
nie
nce,a
nd satifly to clip tight,whe
n desig
ni
ng the broachi
ng cutti
ng tool,this desig
n choses a
nd computes every ki
nd of parameters,such as,the material of the broachi
ng cutti
ng tool,the risi
ng level of the broachi
ng cutti
ng tool,the type of the pulli
ng k
nife gear,a
nd the
number of the gears a
nd so o
n,through the material of spare parts a
nd cutti
ng remai
ni
ng measures, Key words Plectrum C, the processi
ng craft, positio
n, clip tight, broachi
ng cutti
ng tool. 1绪论 夹具设计作为高等工科院校教学的基本训练科目，在设计中占极其重要的位置。夹具结构设计在加深对课程基本理论的理解和加强对解决工程实际问题能力的培养方面发挥着极其重要的作用。因此，选择拨叉的夹具设计能很好的综合考查我们大学四年来所学知识。本次所选拨叉C的工艺分析及夹具设计内容主要包括：拨叉C工艺路线的确定，夹具方案的优选，装配图、零件图的绘制以及拉刀设计，设计说明书的编写等。 夹具是工艺装备的主要组合部分，在机械制造中占有重要地位，夹具对保证产品质量，提高生产率，减轻劳动强度，缩短产品生产周期等都具有重要意义。随着先进制造技术的发展和市场竞争的加剧，传统的夹具设计方式已成为企业中产品快速上市的瓶颈，各企业迫切需要提高夹具设计的效率。 刀具行业是一个比较特殊的行业，肩负着为制造业提供关键装备、数控刀具的重任，制造业的水平如何往往会受刀具行业整体水平的较大影响，而制造业的发展也会促进刀具行业的发展，两者可以说是相互影响相互制约。随着制造业的持续发展，为制造业提供关键装备的刀具行业必将快速、稳步发展，根据制造业发展的需要，多功能复合刀具、智能刀具、高速高效刀具必将成为时代的新宠，面对日益增多的难加工材料，刀具行业必须在改进原有的刀具材料、研发新的刀具材料及寻找更合理的刀具结构方面多下功夫，以解决制造业面临的越来越多的加工难题。 当前，切削技术快速发展，已经进入了现代切削技术新阶段，刀具材料、刀具结构均取得了全面的进步，加工效率也在成倍提高。同时，切削技术和刀具也成为制造业开发新产品和新工艺、应用新材料的基础工艺和建立创新体系的关键技术。本次设计的拉刀常用于加工高精度零件，所以在设计拉刀时要确保各个参数的正确性，为了保证在拉削过程中的高精度，拉刀材料的选择也是设计拉刀的重点，即要保证拉刀的寿命，也要保证拉刀的成本，加工难度小。 目录 摘要…………………………....………………….……………………...Ⅰ ABSTRACT.....................................................................................................Ⅱ 1绪论..........................................................................................................3 2拨叉C的分析.............................................................................................4 2.1拨叉C的作用...........................................................................................4 2.2拨叉C的工艺分析.....................................................................................4 2.3拨叉C的工艺要求.....................................................................................4 2.4毛坯的选择..............................................................................................5 2.5本章总结................................................................................................5 3工艺规程设计.............................................................................................6 3.1加工工艺过程...........................................................................................6 3.2确定各表面加工方案..................................................................................6 3.2.1选择加工方法时，需考虑的因素.............................................................6 3.2.2面的加工...........................................................................................6 3.2.3孔的加工...........................................................................................7 3.2.4槽的加工...........................................................................................7 3.3确定定位基准...........................................................................................7 3.3.1粗基准的选择.....................................................................................7 3.3.2精基准选择的原则...............................................................................8 3.4工艺路线的拟订........................................................................................8 3.4.1工序的合理组合..................................................................................8 3.4.2工序的集中与分散...............................................................................9 3.4.3加工阶段的划分................................................................................10 3.4.4加工工艺路线方案的比较....................................................................11 3.5拨叉C的偏差，加工余量，工序尺寸及毛坯尺寸的确定.......................................12 3.5.1毛坯的结构工艺要求..........................................................................12 3.5.2拨叉C的偏差计算.............................................................................13 3.6确定切削用量及基本工时（机动时间）..........................................................14 3.7时间定额计算及生产安排..........................................................................22 3.7.1钻预制孔.........................................................................................22 3.7.2钻预制孔.........................................................................................23 3.7.3拉25H7内花键................................................................................23 3.7.4粗、精铣18H11底槽........................................................................................23 3.7.5粗、精铣上端面...............................................................................................24 3.7.6钻、攻2-M8螺纹孔.........................................................................................25 3.8本章总结..............................................................................................................26 4专用夹具设计..........................................................................................................27 4.1铣槽夹具设计........................................................................................................27 4.1.1研究原始质料.................................................................................................27 4.1.2定位基准的选择..............................................................................................27 4.1.3夹具方案的设计选择.......................................................................................27 4.1.4切削力及夹紧分析计算...................................................................................27 4.1.5误差分析与计算..............................................................................................29 4.1.6夹具设计及操作的简要说明............................................................................29 4.2钻、攻2—M8螺纹孔夹具设计..................................................................................30 4.2.1研究原始质料.................................................................................................30 4.2.2定位基准的选择..............................................................................................30 4.2.3夹具方案的设计选择.......................................................................................30 4.2.4切削力及夹紧力的计算...................................................................................30 4.2.5误差分析与计算..............................................................................................31 4.2.6夹具设计及操作的简要说明............................................................................32 4.3本章总结..............................................................................................................32 5花键孔25H7拉刀设计..........................................................................................33 5.1拉刀的结构参数....................................................................................................33 5.1.1拉削特点........................................................................................................33 5.1.2拉刀类型选择.................................................................................................33 5.1.3拉刀材料选择.................................................................................................33 5.1.4拉床类型选择.................................................................................................33 5.2拉刀切削部分的设计.............................................................................................33 5.2.1拉削方式选择.................................................................................................33 5.2.2齿型确定........................................................................................................33 5.2.3拉削余量的确定.............................................................................................34 5.2.4刀齿几何参数选择..........................................................................................34 5.2.5确定齿升量....................................................................................................34 5.2.6确定齿距及同时工作齿数...............................................................................35 5.2.7确定容屑槽形状和尺寸...................................................................................35 5.2.8设计分屑槽.............................................................................../....................36 5.2.9确定拉刀齿数和直径......................................................................................37 5.3拉刀其他部分设计................................................................................................38 5.3.1拉刀柄部设计................................................................................................38 5.3.2颈部与过渡锥部设计......................................................................................38 5.3.3前导部、后导部设计......................................................................................39 5.3.4拉刀总长度....................................................................................................39 5.4拉刀强度及拉床拉力校验......................................................................................40 5.4.1拉削力..........................................................................................................40 5.4.2拉刀强度校验................................................................................................41 5.4.3拉床拉力校验................................................................................................41 5.5本章总结..............................................................................................................42 6结论..........................................................................................................................43 参考文献......................................................................................................................44 致谢............................................................................................................................45