车床传动轴的几何精度设计

一．问题提出

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：***

目录

二．专题研究的目的

三．研究内容

四．设计过程

1.轴上各部分作用及技术要求分析

2.轴基本尺寸设计

3.表面粗糙度设计

4.形状位置精度设计

5.传动轴的零件图

研究性训练载体1-1：车床传动轴的几何精度设计

1．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，针对车床传动轴进行几何精度设计。

2．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；

3．研究内容：

完成图1所示传动轴零件的几何精度设计。

（1）对轴上各部分的作用进行分析研究；

（2）对零件各表面主要部分的技术要求进行分析研究；

（3）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；

包括传动轴的尺寸精度设计、形状精度设计、位置精度设计及表面粗糙度。

（4）把公差正确的标注在零件图上。

4．设计过程：

图1 传动轴

Design process:

1. Analysis for the effect and technical requirements of the various parts of the shaft

(1).The shaft is used for power transmission, it’ the key part of torque transmission. Hence we need to ensure the concentricity of the shaft.

(2). Scince the cylindrical surface on both sides fits with the bearing inner race, we need to ensure the stability of each matching part. Hence we get to choose a small roughness.

(3). Shaft shoulder is a thrust surface, which palys a roll of positioning. It’s not a surface for fit or has a relative movment with other parts. Hence we get to choose a middle roughness.

(4). Keyway achieves the transmission of the torque by assembling with the key, and make sure they are well-connected.

2. Basic size design of the shaft

(1). Cylindrical surface with the diameter of 17 transition fit with the bearings. Adopting the basic hole system, we get the upper deviation is +0.012 and the lower deviation is +0.001.

(2).The cylindrical surface with the diameter of 24 is transition fit, and the upper deviation is +0.015 and the lower deviation is +0.002.

(3). Cylindrical surface with the diameter of 17 on both ends have the chamfer C1.

(4). The keyway’s upper deviation is 0 and lower deviation is -0.036.

3. The design of the surface roughness

(1)The surface roughness of Ф17 is required to be 1.6(IT 6) fot fitting with the bearing.

(2)The cylindrical surface of keyway is a working plane, which is fit with the key and the hole. Thus the surface roughness is required to be 3.2(IT 8).

(3)Since it might have movement of the anschaften, the surface roughness of

Ф32 shaft is 3.2(IT 8).

(4) The surface roughness of the shaft shoulder is designed to be 1.6(IT 8). Hence the disassembling could be easier.

4. The precision design of form and position

(1).In order to get better fit between the two cylindrical surfaces and the bearings, and obey the envelope requirement, the cylindricity tolerance should be 0.008mm(IT 8).

(2).The two keyways are used to achieve the transmission of the torque, so its symmetry tolerance for the two reference planes A&B is 0.030mm(IT 9).

(3). Cylindrical surface on both sides and shaft shoulder has the circular runout requirement for the cylindrical surface that with keyways, in order to detect the adoption of radial run-out 0.015mm(IT 7).

(4). The total run-out tolerance of Ф24 which reference plane is A&B is 0.025mm(IT 8).