车床主轴箱齿轮的几何精度设计12221106

1、车床主轴箱齿轮的几何精度设计学院：机电学院专业：机械工程及自动化姓名：吕荣（ 12221106）指导教师：宋志坤目录一问题提出二专题研究的目的三研究内容四设计过程1.齿轮内孔的技术要求与精度设计2.齿顶圆柱面的技术要求与精度设计3.端面的技术要求与精度设计4.齿面的技术要求与精度设计5.齿轮的零件图研究性训练载体1-2：车床主轴箱齿轮的几何精度设计一问题提出：零件的几何精度直接影响零件的使用性能， 而零件的配合表面和非配合表面的精度要求高低各不相同； 即便是配合表面， 其工作性质不同， 提出进度要求及公差项目也不相同，针对车床主轴箱齿轮进行几何精度设计。二专题研究的目的：1）理解零件几何精度对

2、其使用性能的影响；2）根据零件不同表面的工作性质及要求提出相应的公差要求；3）掌握正确的零件公差标注方法；4）掌握零件的几何精度设计方法；三研究内容：完成图 1 所示齿轮零件的几何精度设计。1）对零件各表面主要部分的技术要求进行分析研究；2）根据零件不同表面的工作性质及要求，提出相应的公差项目及公差值；包括齿轮的尺寸精度设计、形状精度设计、位置精度设计及表面粗糙度。3）把公差正确的标注在零件图上。四设计过程：Design process:1. The technical requirements and accuracy design of gear internal boreTechnica

3、l requirements:Since the gear is located at the spindle box, itneeds tobe interferencefitwith theshaft.Hence weshouldsatisfythetolerance requirements of interference fit. In order to reduce the incidence ofwear during the force transmission, we should also need a low roughness onthe internal bore su

4、rface. Take Ra1.6m.The accuray design: Since the internal bore is interferencefit withtheshaft, we generally pick the hole basis, select H7 / p6 and choose accuracygrade IT7. From the table in our book, we can get the width of tolerance bandis 0.025mm. Since it s hole basis, the upper deviation is +

5、0.025 and thelowerdeviation is 0.2.Technical requirements and geometric accuracy design of the tooth surface.Technical requirements:The tooth surface contact two tooth surface, which will produce sliding inthe process of transmissionand lead totoothsurfacewear. It willincreasebacklash in circular to

6、oth and cause the instability of transmission and impactin serioussituation, ifthe roughness is too high.To ensure thestability oftransmission, and reduce friction, small surface roughness should be adopted.Take Ra2.5 m.3. Technical requirements and accuracy of tip cylinderTechnical requirements:The

7、tip cylinder participatesgear meshing,sometimesaddendumcircleisthe benchmarkfor measurementthickness, so the cylinder size tolerance is also needed. In order to ensure thebottom clearance when gear meshes, we should ensure the run-out toleranceof addendum circle and require the surface roughness. Ta

8、ke Ra 6.3m.Accuracy design: We choose the level of accuracy IT7, and checkingITtable to get the width of the tolerance zone which is 0.22 mm. By the chart tochoose size tolerance for h11, looking up table we can get: the upper deviationis 0,the lower deviation is 0.22 mm.4. Technical requirements an

9、d geometric design of end face.Technical requirements: End face is a thrust surface, which palys a roll ofpositioning. It s not a surface for fit or has a relative movment with other parts.Hence we get to choose a middle roughness which is not too big or too small.Take Ra3.2 m.Accuracy design: Select precision grade for IT6, check IT (internat