车床主轴箱齿轮的几何精度设计12221106(共5页)

1、 车床主轴箱齿轮的几何(j h)精度设计 学院(xuyun)：机电学院 专业(zhuny)：机械工程及自动化 姓名：吕荣（12221106） 指导教师：宋志坤 目录(ml)问题(wnt)提出专题研究的目的(md)研究内容设计过程 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(j h)精度设计一问题(wnt)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(biomin)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

2、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:The technical requ

3、irements and accuracy design of gear internal boreTechnical requirements: Since the gear is located at the spindle box, it needs to be interference fit with the shaft. Hence we should satisfy the tolerance requirements of interference fit. In order to reduce the incidence of wear during the force tr

4、ansmission, we should also need a low roughness on the internal bore surface. Take Ra1.6m.The accuray design: Since the internal bore is interference fit with the shaft, we generally pick the hole basis, select H7 / p6 and choose accuracy grade IT7. From the table in our book, we can get the width o

5、f tolerance band is 0.025mm. Since its hole basis, the upper deviation is +0.025 and the lower deviation 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 in the process of

6、transmission and lead to tooth surface wear. It will increase backlash in circular tooth and cause the instability of transmission and impact in serious situation, if the roughness is too high. To ensure the stability of transmission, and reduce friction, small surface roughness should be adopted. T

7、ake Ra2.5m.3. Technical requirements and accuracy of tip cylinder Technical requirements: The tip cylinderparticipates gear meshing, and sometimes addendum circle is the benchmark for measurement of tooth thickness, so the cylinder size tolerance is also needed.In order to ensure the bottom clearanc

8、e when gear meshes, we should ensure the run-out tolerance of addendum circle and require the surface roughness. Take Ra 6.3m.Accuracy design: We choose the level of accuracy IT7, and checking IT table to get the width of the tolerance zone which is 0.22 mm. By the chart to choose size tolerance for

9、 h11, looking up table we can get: the upper deviation is 0,the lower deviation is 0.22 mm.4. Technical requirements and geometric design of end face. Technical requirements: End face is a thrust surface, which palys a roll of positioning. Its 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 Ra3.2m.Accuracy design: Select precision grade for IT6, check IT (internat