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The composition and influencing factors of friction and temperature rise of machine tool spindle bearings

by:JNSN     2021-12-27
The friction of the machine tool spindle bearing and the friction of the temperature rise friction rolling bearing are composed of several parts, please refer to the table. Due to many influencing factors, such as changes in speed and dynamic load, misalignment and deflection caused by assembly, the actual friction torque and friction values u200bu200bmay deviate greatly from the calculated values. If friction torque is an important design factor, please contact the Schaeffler Group Engineering Service. The composition and influencing factors of friction The idling friction depends on the quantity, speed, working viscosity of the lubricant, the sealing and running-in conditions of the bearing. The heat dissipation friction will be converted into heat energy. The heat must be dissipated from the bearing. At low speeds, the adjacent structures can effectively dissipate heat. High-speed working conditions or long operating cycles must be lubricated for heat dissipation. The lubricating oil dissipates heat. The lubricating oil takes away part of the heat. Circulating oil lubrication with cooling device has good heat dissipation effect. Grease lubrication cannot dissipate heat. Heat dissipation through the shaft and bearing housing The effect of heat dissipation through the shaft and ASAHI housing depends on the temperature difference between the bearing and the surrounding structure, see Figure 1. The heat source or heat radiation source of the adjacent structure must be considered. Friction composition influencing factors: rolling friction ■ load size sliding friction of rolling elements, sliding friction of cage ■ load size and direction ■ speed and lubrication, running-in situation fluid friction (flow resistance) ■ bearing type and speed ■ type of lubricant , Quantity and Working Viscosity Seal Friction ■ Seal type and seal preload Figure 1 Temperature distribution between bearing, shaft and bearing seat. In addition to knowing the speed and load for friction calculation, the type of lubrication, the method of lubrication and the viscosity of the lubricant at the working temperature are important factors for further calculations. Total friction torque MR: friction power NR: friction torque is a function of speed. For cylindrical roller bearings, friction torque is a function of load: for ball bearings, tapered roller bearings and spherical roller bearings, friction torque is a function of load: MR Nmm total friction torque M0 Nmm friction torque is a function of speed M1 Nmm friction torque is a function of load NR W friction power n min1 working speed f0 speed parameter of bearing friction torque, see page 15, table mm2s1 lubrication at working temperature Kinematic viscosity of the agent. The viscosity of the grease depends on the viscosity of the base oil at the working temperature. dM mm Average bearing diameter (d + D)/2f1 Load factor of bearing friction torque, see page 15, table Fr, Fa N is the diameter for TORRINGTON radial bearings For thrust bearing, the axial load P1 N friction torque determines the load. For ball bearings, tapered roller bearings and spherical roller bearings, see page 16, table. Bearing factors The bearing factors f0 and f1 are average values u200bu200bbased on a series of tests and corresponding data in accordance with the ISO 15312 standard. Refer to the table for the bearing factor f0 for oil injection lubrication. Using oil injection lubrication, the bearing factor f0 will increase, even for the same average bearing diameter dM, the same size of steel ball or roller length, and the same bearing section size. The wide series bearings in the table have a larger bearing factor f0 than the narrow series bearings. If radial bearings are used on a vertical shaft, the actual value must be twice the value in the table. This also applies to the use of large-flow cooling oil lubrication or excessive grease filling (exceeding the amount of grease that can be injected on one side). In the start-up phase, the bearing factor f0 of the bearing filled with fresh grease is equal to the bearing factor using oil bath lubrication. After the grease is evenly distributed, the bearing factor f0 is halved. Bearing factor of cylindrical roller bearing with cage Bearing factor of thrust roller bearing Bearing factor of tapered roller bearing Bearing factor of angular contact ball bearing Bearing factor series Bearing factor f0 Bearing factor f1 Grease lubrication, oil mist lubrication, injection lubrication, circulating oil Lubrication NN30..-K 1.7 3 0.0002 0.0004 NNU49..-K 1.7 3 series bearing factor f0 bearing factor f1 grease lubrication, oil mist lubrication, spray lubrication, circulating oil lubrication 811, K811 2 3 0.0015 812, K812 893, K893 894 , K894 series bearing factor f0 bearing factor f1 grease lubrication, oil mist lubrication, oil spray lubrication, circulating oil lubrication 302, 303, 320, 329, 330 2 3 0.0004 313, 322, 323, 331, 3323 4.5 series bearing factor f0 bearing factor f1 Grease lubrication, oil mist lubrication, oil spray lubrication, oil lubrication 70..-B 1.3 2 0.001 · (P0/C0)0.33 719..-B 73..-B 2 3.
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