Calculation Method of Equivalent Dynamic Load of Motor Bearing

Motor bearings are mostly subjected to radial load or a composite load of radial load and axial load, and the load conditions are varied, such as changes in size. Therefore, it is impossible to directly compare the actual load of the bearing with the basic dynamic load rating. At this time, the actual load is converted into an imaginary load passing through the center of the bearing with a certain magnitude and direction for analysis and comparison. Under the imaginary load, the bearing has the same life as the actual load and speed. The imaginary load converted in this way is called the equivalent dynamic load, denoted by P. Calculation of equivalent dynamic load: (1) Calculation of equivalent dynamic load of deep groove ball bearing: Pu003dXFr+YFa［KN］ (9) where Fr: radial load KN Fa: axial load KN Fa/Co basic group tour Clearance Fa/Fr≤e Fa/Fr >eX YXY e Fa/Fr≤e Fa/Fr >e XYXY e Fa/Fr≤e Fa/Fr >e XYXY e X.Y coefficient see Table 7 (2) Cylindrical roller Calculation of equivalent dynamic load of bearing: Pu003dFr [KN] (10) (3) Calculation of equivalent dynamic load of spherical roller bearing When Fa/Fr≤e, Pu003dFr+Y1Fa (11) When Fa/Fr> When e, Pru003d0.67Fr+Y2Fa (12), KN Pr: equivalent dynamic load, KN Pr: radial equivalent dynamic load, Fr: radial load, Fa KN: axial load Y1, Y2 e, Y1 and Y2 values u200bu200bcan be found in the bearing gauge table. e represents the limit value Fr Fa. (4) Calculation of equivalent dynamic load of angular contact ball bearings ①Single row angular contact ball bearings with a contact angle of 15° Single bearing or tandem configuration Pu003dFr [kN] When Fa/Fr≤e (13) Pu003d0.44Fr+YFa [kN] When Fa/Fr>e (14) Back-to-back, face-to-face configuration Pu003dFr + Y1Fa [kN] When Fa/Fr≤e (15) Pu003d0.72Fr+Y2Fa [kN] When Fa/Fr>e (16 ) ② Single row angular contact ball bearings with a contact angle of 25° Single bearing or series configuration Pu003dFr [kN] When Fa/Fr≤0.68 (17) Pu003d0.41Fr+0.87Fa [kN] When Fa/Fr>0.68 ( 18) Back-to-back, face-to-face configuration Pu003dFr+0.92Fa [kN] when Fa/Fr≤0.68 (19) Pu003d0.67Fr+1.41Fa [kN] when Fa/Fr>0.68 (20). ③ Single row angular contact ball bearings with a contact angle of 4 Single bearing or series configuration Pu003dFr [kN] When Fa/Fr≤1.14 (21) P＝0.35Fr+0.57Fa [kN] When Fa/Fr>1.14 (22) Back-to-back, face-to-face configuration Pu003dFr+0.55Fa [kN] when Fa/Fr≤1.14 (23) Pu003d0.57Fr+0.93Fa [kN] when Fa/Fr>1.14 (24). Special attention: For single row angular contact ball bearings and tapered roller bearings, as shown in Figure 1, the axial component force (Fac) will be generated when the radial load is applied. Therefore, the front or back of the two bearings are configured for use. Acting point Fac Fr Fr Acting point α Fac [The position of the acting point is shown in the bearing size table] Figure 1 Axial force component table 9 Two single row angular contact ball bearings or tapered roller bearings are equipped with the equivalent dynamic load on the front or back side. The calculation method of equivalent dynamic load when this type of bearing is subjected to radial load and external axial load (Ka) is shown in Table 9. The axial component force can be calculated by the following formula: Facu003d (25)Fr 2Y Bearing configuration back configuration front configuration load condition Equivalent dynamic load + Ka u003d ＞ F rB2Y BF rA2Y A+K aF rA2Y A＜F rB2Y B+ K a ＝ ＜ F rA2Y AF rB2YB> +F rB2Y BF rA2YAK aA BFrAFrBK aB AFrBK aFrAKaFrA FrBA BB AKaFrA FrB bearing distinguishing axial load bearing B PB u003d F rB bearing APA