Bearings(轴承)

Two types of bearings are used to support a shaft, i.e., sliding and rolling bearings. With small friction, high rotation flexibility and easy to maintain, rolling bearings are widely used standard components of mechanical equipment. This chapter illustrates their codes, specified and simplified representation. 

轴承分为滑动轴承和滚动轴承,用于支撑轴。滚动轴承的摩擦阻力小,转动灵活,维修方便,是机械设备中广泛应用的一种标准件。本节主要介绍滚动轴承的代号、规定画法和简化画法。

 Structureof rolling bearings(滚动轴承的结构)

The structure of rolling bearings consists of four components, shown in Fig. 7-47.

(1) Inner race   Tightly mounted on the shaft and rotating with it.

(2) Outer race   Mounted on the bearing's bracket hole and fastened.

(3) Rolling elements   Located between the inner and outer rings. They include balls, columns, and cones.

(4) Cage   Used to isolate the rolling element.

滚动轴承的结构一般由四个元件组成,如图7-47所示。

(1)内圈   紧密套装在轴上,随轴转;

(2)外圈   装在轴承座的孔内,固定不动;

(3)滚动体   形式有圆球、圆柱、圆锥等,排列在内、外圈之间;

(4)保持架   用来把滚动体隔开。

Types of rolling bearings(滚动轴承的分类)

(1) Radialbearing   Used to bear the radial load. See deep groove ball bearingsin Fig.7-47a.

(2) Thrust bearing   It only bears the axial load. See thrust bearings in Fig.7-47b.

(3) Radial thrust bearing  It bears both the radial and axial loads. See the tapered roller bearing in Fig. 7-47c.

(1)向心轴承  主要用于承受径向载荷,如图7-47a中的深沟球轴承。

(2)推力轴承  只承受轴向载荷,如图7-47 b中的推力球轴承。

(3)向心推力轴承   能同时承受径向载荷和轴向载荷,如图7-47 c中的圆锥滚子轴承。

 Rolling bearing codes(GB/T 272—1993)(滚动轴承的代号)

According to national standards, structure, dimension,tolerance degree and technical requirements are represented by the codes of the rolling bearing.Codes are composed of pre-code, base code, and post-code. These quence is the following:

 Pre-code   Base code   Post-code

The base code is essential. The pre-code and post-code are supplementary codes and are added before and after the base code, respectively, when the structure, dimension, tolerance and techn ical requirements of the bearing change.If necessary, consult the relevant national standard. 

基本代号是轴承代号的基础,前置代号、后置代号是补充代号。前置代号和后置代号是轴承在结构形状、尺寸、公差、技术要求等有改变时,在其基本代号的左、右填加的补充代号。需要时可查阅有关国家标准。

Some common basic codes arelisted below. The basic code consists of the bearing type code, dimension series code and inner diameter code (The dimension series code consists of width or height series). Code meanings are explained below:

下面介绍常用基本代号。基本代号由轴承类型代号、尺寸系列代号和内径代号构成(尺寸系列代号由轴承的宽或高度系列代号组合而成)。其所代表的意义举例如下:

Example 1  Bearing6206    (例1 轴承6206)

Rolling bearing marks should include the name, its code and the national standard number. The mark symbol of the above-mentioned deep groove ball bearing is the following: 

滚动轴承的标记内容:名称、 代号和国标号,所以上述深沟球轴承的规定标记为:

Roll bearing 6206  GB/T 276—1994       滚动轴承6206   GB/T 276—1994

Example 2  Bearing51210   (例2  轴承51210)

Specifiedsymbol: Rollingbearing 51210   GB/T 301—1995

The last two digits represent a 2-digit number of the inside diameter of the bearing. Multiply the number from 04 by 5, the result of which is the inside diameter of the bearing. Therefore, the inside diameter of the bearing is d=10×5=50mm.

规定标记为:滚动轴承51210   GB/T  301—1995

表示轴承内径的两位数字,从“04”开始用这组数字乘以5,即为轴承内径的尺寸,故在此例中d=10×5mm=50mm,即为轴承内径尺寸。

If the 2-digit number representing the inside diameter is below “04”, the standard specifies:

表示轴承内径的两位数字,在“04”以下时,标准规定:

00 represents d=10mm,      00表示d=10mm;

01 represents d=12mm,      01表示d=12mm;

02 represents d=15mm,      02表示d=15mm;

03 represents d=17mm.      03表示d=17mm

Representation of rollingbearings(GB/T 4459.7—1998)(滚动轴承的画法)

There is no need to draw the part drawing for rolling bearing as it is a standard component. Therefore the specified representation and simplified representation that are specified by national standard can be used to represent the rolling bearing in the assembly drawing. In the drawing, the main dimensions of the bearing should be referenced from the national standards according to corresponding bearing code in terms of the external diameter D, inner diameter d, and width B. And then use these main dimensions as references, draw the dimensions of rest parts with the proportion of the main dimensions. The specified and simplified representations of rolling bearings are shown in Table 7-8. 

滚动轴承是标准件,不需要画零件图。在画装配图时可根据国家标准所规定的规定画法或简化画法表示。画图时,应根据轴承代号由国家标准中查出轴承的外径D、内径d、宽度B等几个主要尺寸;然后,将其他部分的尺寸,按与主要尺寸的比例关系画出。常用滚动轴承的规定画法和简化画法如表7-8所示。

If the primary structure of the rolling bearing needs to be represented in a more detailed way, a specified representation can be adopted when drawing the assembly. If the primary structure of the rolling bearing needs to be represented in a simple way, the simplified representation, namely, the feature representation (table 7-8) or conventional representation (shown in Fig. 7-48) can be used. 

装配图中,需要较详细地表达滚动轴承的主要结构时,可采用规定画法;在装配图中,仅需要简单地表达滚动轴承的主要结构时,可采用简化画法中的特征画法(表7-8)或通用画法(图7-48)表达即可。