张紧轮支架加工工艺及夹具设计说明书

太原理工大学现代科技学院课程设计张紧轮支架加工工艺及夹具设计说明书II目录1绪论···········································································································12张紧轮支架的分析···························································································22.1张紧轮支架的工艺分析···················································································22.2张紧轮支架的工艺要求···················································································23工艺规程设计··································································································43.1加工工艺过程······························································································43.2确定各表面加工方案······················································································43.2.1影响加工方法的因素················································································43.2.2加工方案的选择·····················································································53.3确定定位基准······························································································53.2.1粗基准的选择························································································53.2.1精基准选择的原则··················································································63.4工艺路线的拟订····························································································73.4.1工序的合理组合·····················································································73.4.2工序的集中与分散··················································································73.4.3加工阶段的划分·····················································································83.5张紧轮支架的偏差，加工余量，工序尺寸及毛坯尺寸的确定···································93.5.1毛坯的结构工艺要求················································································93.5.2张紧轮支架的偏差计算············································································103.4.4加工工艺路线方案的比较·········································································103.6确定切削用量及基本工时（机动时间）·····························································124铣35MM和28MM平面夹具设计············································································224.1问题的提出································································································224.2切削力和夹紧力计算····················································································224.3定位误差分析·····························································································244.4夹具设计及操作的简要说明··········································································25结论···············································································································26参考文献············································································································2711绪论机械设计制造及其夹具设计是我们融会贯通所学的知识，将理论与实践相结合，对专业知识的综合运用训练，为我们即将走向自己的工作岗位打下良好的基础。机械加工工艺是规定产品或零件机械加工工艺过程和操作方法，是指导生产的重要的技术性文件。它直接关系到产品的质量、生产率及其加工产品的经济效益，生产规模的大小、工艺水平的高低以及解决各种工艺问题的方法和手段都要通过机械加工工艺来体现，因此工艺规程的编制的好坏是生产该产品的质量的重要保证的重要依据。在编制工艺时须保证其合理性、科学性、完善性。而机床夹具是为了保证产品的质量的同时提高生产的效率、改善工人的劳动强度、降低生产成本而在机床上用以装夹工件的一种装置，其作用是使工件相对于机床或刀具有个正确的位置，并在加工过程中保持这个位置不变。而本次对于张紧轮支架加工工艺及夹具设计的主要任务是：完成张紧轮支架零件加工工艺规程的制定22张紧轮支架的分析2.1张紧轮支架的工艺分析张紧轮支架是一个很重要的零件，因为其零件尺寸比较小，结构形状较复杂，但其加工孔和底面的精度要求较高，此外还有小头孔端要求加工，对精度要求也很高。张紧轮支架的底面、大头孔上平面和小头孔粗糙度要求都是Ra6.3，所以都要求精加工。其小头孔与底平面有垂直度的公差要求，张紧轮支架底面与大头孔上平面有平行度公差要求，所要加工的槽，在其槽边有平行度公差和对称度公差要求等。因为其尺寸精度、几何形状精度和相互位置精度，以及各表面的表面质量均影响机器或部件的装配质量，进而影响其性能与工作寿命，因此它们的加工是非常关键和重要的。2.2张紧轮支架的工艺要求一个好的结构不但要应该达到设计要求，而且要有好的机械加工工艺性，也就是要有加工的可能性，要便于加工，要能够保证加工质量，同时使加工的劳动量最小。而设计和工艺是密切相关的，又是相辅相成的。设计者要考虑加工工艺问题。工艺师要考虑如何从工艺上保证设计的要求。3图2.1张紧轮支架零件图该加工加工表面：平面加工包括张紧轮支架底面、支架底面反面台阶面；两支脚的两个端面。孔系加工包括φ13孔；腰形孔。以平面为主有：①张紧轮支架底面的粗、精铣加工，其粗糙度要求是；Ra=6.3②两支脚端面的粗、精铣加工，其粗糙度要求是Ra=6.3。⑵孔系加工有：①φ13孔的钻、铰孔加工，其表面粗糙度为6.3Ra；②腰形孔铣加工，其表面粗糙度要求Ra=25；张紧轮支架毛坯的选择铸造，因为生产率很高，所以可以免去每次造型。单边余量一般在1~3mm，结构细密，能承受较大的压力，占用生产的面积较小。因其年产量是4000件，由[3]表2.1～3可知是小批量生产。上面主要是对张紧轮支架零件的结构、加工精度和主要加工表面进行了分析，选择了其毛坯的的制造方法为铸造和中批的批量生产方式，从而为工艺规程设计提供了必要的准备。43工艺规程设计3.1加工工艺过程由以上分析可知，该张紧轮支架零件的主要加工表面是平面、孔系。一般来说，保证平面的加工精度要比保证孔系的加工精度容易。因此，对于张紧轮支架来说，加工过程中的主要问题是保证孔的尺寸精度及位置精度，处理好孔和平面之间的相互关系以及各尺寸精度。由上面的一些技术条件分析得知：张紧轮支架的尺寸精度，形状精度以及位置关系精度要求都不是很高，这样对加工要求也就不是很高。3.2确定各表面加工方案一个好的结构不但应该达到设计要求，而且要有好的机械加工工艺性，也就是要有加工的可能性，要便于加工，要能保证加工的质量，同时使加工的劳动量最小。设计和工艺是密切相关的，又是相辅相成的。对于我们设计张紧轮支架的加工工艺来说，应选择能够满足平面和孔加工精度要求的加工方法及设备。除了从加工精度和加工效率两方面考虑以外，也要适当考虑经济因素。在满足精度要求及生产率的条件下，应选择价格较底的机床。3.2.1影响加工方法的因素⑴要考虑加工表面的精度和表面质量要求，根据各加工表面的技术要求，选择加工方法及分几次加工。⑵根据生产类型选择，在大批量生产中可专用的高效率的设备。在单件小批量生产中则常用通用设备和一般的加工方法。如、柴油机连杆小头孔的加工，在小批量生产时，采用钻、扩、铰加工方法；而在大批量生产时采用拉削加工。⑶要考虑被加工材料的性质，例如：淬火钢必须采用磨削或电加工；而有色金属由于磨削时容易堵塞砂轮，一般都采用精细车削，高速精铣等。5⑷要考虑工厂或车间的实际情况，同时也应考虑不断改进现有加工方法和设备，推广新技术，提高工艺水平。⑸此外，还要考虑一些其它因素，如加工表面物理机械性能的特殊要求，工件形状和重量等。选择加工方法一般先按这个零件主要表面的技术要求来选定最终加工方法。再选择前面各工序的加工方法，如加工某一轴的主要外圆面，要求公差为IT6，表面粗糙度为Ra0.63μm，并要求淬硬时，其最终工序选用精度，前面准备工序可为粗车——半精车——淬火——粗磨。3.2.2加工方案的选择⑴由参考文献[3]表2.1～12可以确定，平面的加工方案为：粗铣——精铣（79ITIT），粗糙度为aR6.3～0.8，一般不淬硬的平面，精铣的粗糙度可以较小。⑵由参考文献[3]表2.1～11确定，φ13孔的表面粗糙度要求为6.3，则选择孔的加方案序为：钻——铰。⑶腰形孔铣加工加工方法3.3确定定位基准3.2.1粗基准的选择选择粗基准时，考虑的重点是如何保证各加工表面有足