Diameter/axial clearance and contact angle of NSK deep groove ball bearings

The relationship between radial clearance and axial clearance of deep groove ball bearings in Fig. 5 r and a The codes in Fig. 5 are as follows. Oa Ball center Oe Outer ring groove curvature center Oi Inner ring groove curvature center Dw Ball diameter ( mm )ree Outer ring groove radius ( mm )ri Inner ring groove radius ( mm ) Contact angle ( )r Radial clearance ( mm )a Axial clearance (mm) In addition, in Fig. 5, r u003d rrra + ri u003d cot (3) u003d sin ( ) (6) Radial clearance Fig. 6 Radial clearance and axial clearance table of deep groove ball bearings 3 Radial and axial clearance conversion constant K value Inner diameter code K60 series 62 series 63 series Technical information The amount that can be displaced in the radial direction without loading is called radial clearance, and the amount that can be displaced in the axial direction is called axial clearance. The relationship between radial and axial clearance is shown in Figure 5, which can be obtained from its geometric relationship. For bearings, since (re+ri-Dw) is a constant, r, a and a are related to each other. As mentioned above, the clearance of deep groove ball bearings generally refers to the radial clearance, and sometimes it is necessary to know the axial clearance depending on the location of use. The relationship between the radial clearance and the axial clearance of deep groove ball bearings is determined by formula (4), which can be rewritten as formula (7). FIG. 6 is an example thereof. In addition, the K values u200bu200bof various types of bearings are shown in Table 3. Calculation example When the radial clearance of ball bearing 6312 is 0.017 mm, it is known from the table that Ku003d2.09, so the axial clearance is au003d2.09 0.017u003d2.090.13u003d0.27 (mm). (2) Radial clearance and contact angle Single row deep groove ball bearings can also be used as thrust bearings. At that time, it is advisable to increase the contact angle as much as possible. The contact angle of the ball bearing is determined geometrically by the radial clearance and the curvature radius of the inner and outer ring grooves. Using the relationship between equations 1) and (6), Figure 7 illustrates the radial clearance and contact for the 62 and 63 series. The relationship between the angles; the initial contact angle ao is the angle of the axial load, and once the load is applied, the contact angle will change. zero-hour contact. When ao exceeds 20, it is necessary to consider whether the contact area between the steel ball and the raceway surface exceeds the raceway when the bearing is under axial load (see page A81). Table 4 C3, C4 Clearance initial contact angle ao For deep groove ball bearings that only work under axial load conditions, in order to increase their contact angle, the radial clearance usually adopts a larger clearance than the standard clearance , Several bearings use C3 clearance, the initial contact angle of C4 clearance, as shown in Table 4. (3) Angular clearance of single-row deep groove ball bearings u003d Ko・1/2 In the formula, : Radial clearance (mm) Outer ring groove radius (mm) Inner ring groove radius (mm) Ball diameter (mm) Ball joint Circle diameter (mm) constant 2{ ( )}1/2Dpwtan ≒ u003d bearing code 60 series 62 series 63 series Table 5 Radial clearance angle clearance conversion constant Ko value Figure 8 Radial clearance and angular clearance μm are considered When the load applied to the bearing is generally a radial load, an axial load or a combined load; under such load conditions, the inner and outer rings are usually regarded as parallel displacements. In fact, due to the eccentricity of the bearing seat, the shaft is deflected during loading, or the bearing is installed skewed, etc., the bearing sometimes works in a state where the inner and outer rings are not parallel. In this case, when the inclination angle of the inner and outer rings exceeds 1/2 of the bearing angular clearance described below, abnormal stress will be generated, which will become the cause of temperature rise and early peeling. As for the load distribution and the calculation method of equivalent load under moment load, there have been detailed reports, but first of all, it is very important to understand the angular clearance of various types of bearings for the use of bearings. The angular clearance refers to the angle formed by the two ferrules, one is fixed and the other is not fixed and is inclined to the left and right sides at will, which is closely related to the radial clearance. The angular clearance o can be approximated by equation (1). The constant K0 is constant according to various types of bearings. The values u200bu200bof single row deep groove ball bearings 60, 62 and 63 series are shown in Table 5. In addition, the relationship between the radial clearance r and the angular clearance o is shown in FIG. 8 . The inclination angle of the inner and outer rings is about o/2.