Search Results (3)

(1) Background: To better understand the dynamic characteristics of a ball bearing with an elastic ring squeeze film damper (ERSFD) under sudden unbalance, a novel dynamic model was established by fully considering the coupling between the ERSFD, bearing outer ring (the journal), rotor, and disc (loading bearing); (2) Methods: An improved secant method was developed to determine the initial eccentricity values of the bearing’s outer ring and the disc. The dynamic response of the outer ring under different speed ratios, damping ratios, and mass ratios was solved using the variable-step Runge–Kutta method; (3) Results: In comparison, a low-speed ratio, high damping ratio, and low mass ratio were more conducive to suppressing the bearing vibration. When the imbalance was suddenly introduced, the displacement amplitude of the eccentricity, transmissibility, amplitude–frequency response, and the radius of the outer ring center locus increased; (4) Conclusions: This work provides a reference for further studying the nonlinear vibration of rolling bearings coupled with an ERSFD. Full article

Various industries, including mechanical engineering, utilize steel rings featuring variable cross-sectional profiles, such as eccentric rings. Presently employed methods for producing eccentric rings possess drawbacks like restricted geometries, significant material wastage or uneven microstructures. The radial–axial ring rolling process serves to create seamless rolled steel rings with near-net-shaped cross-sections. A novel technique involves achieving eccentricity by dynamically adjusting the mandrel’s position during the ring rolling process. This method’s fundamental feasibility has previously been showcased using a blend of oil clay and a labor test bench. Transferring the possibility of manufacturing eccentric rings on industrial radial–axial ring rolling mills would expand the product range of ring manufacturers without encountering drawbacks associated with existing manufacturing processes. The objective of this paper is to demonstrate the basic feasibility of the concept of an industrial radial–axial ring rolling mill. In the first step, FEA simulation studies were carried out to develop the rolling strategy and estimate the achievable eccentricity on the institute’s radial–axial ring mill. Subsequently, the rolling strategy was implemented on an industrial ring rolling mill with the help of a unique technology module programmed in C++. Finally, an eccentric ring was ring rolled and compared with the FEA simulation, and the reproducibility was demonstrated to be successful. Full article

Due to the large wall thickness difference and serious instability in the large-scale ring rolling process, most studies on the feed curve are not suitable for a large-scale ring. The production cost of the large-scale ring is high, and if plastic instability occurs, it will cause a great waste of resources. Therefore, in this study, a staged feed strategy based on the evolution of ring instability is proposed with the objective of controlling the rolling stability of a large-scale ring. Firstly, based on the law of rolling instability evolution, the rolling stage during the rolling process is divided. Secondly, the coordination of all rolling stages is proposed as a factor to design the feed curve. The feed scheme is determined using the central composite design (CCD) method, and then the established mathematical model is applied to obtain the radial feed curves of a large-scale flat ring with a 5 m diameter for different schemes. Next, the designed feed curve was submitted to finite element method (FEM) simulation. According to the FE simulation results, a rolling map for controlling roundness error, eccentricity and vibration is established. Finally, the feed curve in the stable region is input to the FE simulation and the production trial to obtain the results of roundness error, eccentricity and vibration. A comparison of the simulation and production trial results shows that they are in good agreement, which proves the reliability of the feed curve designed based on the stable rolling region in the roll map. Moreover, the machining amount for both the simulation and production trial is below the maximum machined value. Full article