Calculation Model for Multi-Roller Load Distribution of Planetary Threaded Roller Bearings Considering Machining Errors

Load-bearing capacity is critical in planetary threaded roller bearings (PTRBs). Machining errors cause uneven load distribution coefficients (LDC) among the rollers and the threaded teeth. The limited literature explores the influence of machining errors on PTRB’s load-bearing performance. A computational model that considers multiple machining errors when determining the load distribution among the rollers and the threaded teeth is proposed in this paper. The PTRB is discretized into a multi-roller spring system. Moreover, a set of nonlinear equations is established based on deformation coordination and force balance. The theoretical model is verified against the finite element simulation results and previous studies. The influence of machining errors on the LDC among the rollers and the threaded teeth is investigated. Results indicate that pitch errors do not significantly impact the LDC among the rollers. However, pitch errors directly affect the LDC among the threaded teeth. Errors in roller nominal diameter and the eccentricity of the inner and outer ring axes cause uneven LDC among the rollers; axis misalignment has a complex effect on the LDC. The proposed computational model can guide the parameter design, component processing, and assembly method of PTRB.