An inverted planetary roller screw mechanism for converting rotary motion into linear
An inverted planetary roller screw mechanism (PRSM) is applied in various drives, such as machine tools, aircraft flap drives, oil and gas valve drives, mechanisms to stabilize tank barrels, etc. Currently, these mechanisms are widely used in manufacturing electric cylinders supplied as individual units and can be implemented in various automated production systems, such as welding manipulators. Since PRSMs as well as electric cylinders using them find expanding applications, methods for their design and analysis need to be developed. Most of the methods described in the literature are advisory by nature and do not comply with the production requirements. Thus, the development of a unified method for the design and calculation of PRSMs is an urgent task. This paper describes the design of a PRSM with a long nut, that is, the so-called inverted mechanism. The advantages and disadvantages of this PRSM are evaluated. The kinematics of the mechanism is analyzed and the basic geometric parameters influencing the speed of the screw and rollers relative to the nut are considered. The speed of the axial movement of the screw relative to the nut is determined as a function of the frequency of rotation of the nut, the pitch and entries of the nut, rollers and screw. The results obtained in the study are part of the method of PRSM design but, even at this stage, they can be applied for the initial design and pilot production of PRSMs.