Experimental Evaluation of the Cross Roller Bearing Resistance Moment in Vacuum

Abstract—

Roller bearings with crossed rollers are actively used in the swivel mechanisms of manipulators and other units due to the combination of high rigidity and increased load capacity. When designing new mechanisms, an important characteristic is the resistance moment, the value of which can be significantly influenced by operating conditions, such as the environment, the amount and type of lubricant, load, etc. In the presented study, the resistance moment and the friction coefficient of a cross-roller bearing were investigated at various temperatures, pressure in the chamber, load, and amount of lubricant. To test a bearing with crossed rollers of size RA 6008 in the temperature range from –40 to +100°C in vacuum conditions, technological equipment was designed and manufactured, a method for measuring the resistance moment was developed, and a full factorial experiment was carried out to assess the degree of influence of various factors on the resistance moment at a fixed VNIINP-284 (AMETHYST) grease amount. The test results showed that the moment of resistance and the coefficient of friction decrease with an increase in the grease amount from 60 to 230 mg, a decrease in air pressure in the test chamber from 10⁵ Pa to 1.33 × 10^–3 Pa leads to an increase in the friction coefficient and the resistance moment of the bearing, while an increase in temperature operation of a bearing with grease from 25 to 100°С leads to a decrease in the resistance moment and friction coefficient, and a decrease in temperature to –40°C leads to their increase.