CALCULATION OF A FLEXIBLE NUT OF A PLANETARY ROLLER SCREW FOR A SPACE TECHNOLOGY PRODUCT POSITIONING SYSTEM

Linear drives based on the most promising planetary roller screws (PRS) are widely used in space technology products. The object of the research is PRS in the drive of positioning systems. PRS meet the requirements for space technology products if they are gas-free and have very small mass. It can be achieved by using a backlash-free screw with a flexible nut made in the form of a “short” cylindrical shell and developed ends. A calculation scheme where the nut is conditionally divided into a “short” cylindrical shell and flat rings has been developed to prove the possibility of selection of gaps between the threaded parts of the PRS with a flexible nut and determining its dimensions. Methods of structural mechanics of machines are used to determine unknown internal force factors at the mating points of the shell and rings. Due to the complexity of mathematical dependencies and a lot of calculations, a special computer program has been invented. It allows to enter and monitor initial data, identify unknown internal factors and calculate the required parameters of a flexible nut, for instance, radial movements of the points of the median surface of the shell, the values of which assess the possibility of sampling the gaps between the threaded parts of the PRS. The program determines the rational dimensions of a flexible nut for a backlash-free PRS, which is going to be calculated according to static and dynamic load capacities.