公差与互换性国际标准08_Chapter 5 Rolling bearing tolerance and fits

82 Chapter5 Rolling Bearing Tolerance and Fits

Chapter 5

Rolling Bearing Tolerance and Fits

Chapter5 Rolling Bearing Tolerance and Fits 83 5.1 Introduction

•Since everything in industry turns on bearings, it is necessary for those persons responsible for keeping equipment running to fully understand bearings. There are two types of bearings; namely, sliding bearings and rolling bearings. The majority of bearings used are rolling bearings and the subject of this article will concentrate only on rolling bearings.

•Practically all rolling bearings consist of four basic parts; namely: inner ring, outer ring, rolling elements, and cage or separator, as shown in Figure 5-1. Three of these parts the inner ring, outer ring, and rolling elements - support the bearing load. The fourth part - the cage or separator - provides positive separation of adjacent rolling elements.

Figure 5-1 rolling bearings basic parts

•Depending on the internal design, rolling bearings may be classified as radial bearings

or thrust bearings. A radial bearing is designed primarily for carrying a radial load. Radial load is a pressing force at right angles to the shaft (Figure 5-2). Thrust load is a pushing force against the bearing parallel to the shaft (Figure 5-3).

Figure 5-2 radial bearings basic parts Figure 5-3 rolling bearings basic parts

84 Chapter5 Rolling Bearing Tolerance and Fits

5.2 Bearing types and applicable tolerance classes

Chapter5 Rolling Bearing Tolerance and Fits 85 5.3 the tolerance about the inner ring and the outer ring

•The △dmp is the deviation of mean bore diameter in a single plane of shaft washer, double-direction bearing

•The V dp is the variation of bore diameter in a single plane of shaft washer, single-direction bearing

•The V dmp is the variation of mean bore diameter (this applies only to a basically cylindrical bore)

86 Chapter5 Rolling Bearing Tolerance and Fits

The ⊿Dmp is the deviation of mean outside diameter in a single plane

•

•The V Dp is the variation of outside diameter in a single radial plane of housing washer •The V Dmp is the variation of mean outside diameter

5.4 Rolling Bearing Fits

•The purpose of fit is to prevent harmful sliding between two mating bodies, by securely fastening a bearing ring, which rotates under loads, on the shaft or housing.

•The purpose of fit is to prevent harmful sliding between two mating bodies, by securely fastening a bearing ring, which rotates under loads, on the shaft or housing.

•This harmful sliding is called creep. It may induce excessive heating, wear in the contact area of the mating surfaces, ingress of wear debris into the bearing, vibration, and other unwanted phenomena.