Optimizing profiled ring preforms for enhanced deformation uniformity using the isothermal field method

Research Status and Developing Trends on the Ring Rolling Process of Profile Ring Parts

Design of Profile Ring Rolling by Backward Simulation Using Upper Bound Element Technique (UBET)

The accurate geometry and effective control during the ring rolling process are the prerequisites for the ring products’ precise forming. In this paper, the interaction modes and rules between ring and rolls in vertical hot ring rolling (VHRR) process are analyzed, and the change laws of the ring’s geometry are studied. Based on the ABAQUS/Explicit software and its subroutine VUAMP, the finite element (FE) model of the VHRR process with measurement and control is established. Then, the ring rolling process of a groove-section profile ring is simulated. During the simulation, the ring’s outer diameter, roundness error, and the stability of the rolling process are detected in time, and the close-loop control of feed plan of the drive roll and measuring roll are also employed. The results obtained show the following: (1) Four feed stages are divided by means of a step-down feed movement, that is, bite stage, main rolling stage, precise forming stage, and sizing stage. (2) At bite and main rolling stages of the VHRR process, the ring’s center swings in a spiral line, and the rolling process is unstable, the ring’s roundness becomes worse, while the process is entering the precise forming stage, by means of the guide roll, the rolling process becomes steady and the ring’s roundness tends to be better. (3) The measuring roll contacts with the ring at the main rolling stage, afterwards, it is pushed back at the precise forming stage by ring’s growth. When the measuring roll meets the desired displacement value, a stop feeding command will be fed back, and the ring rolling process enters the sizing stage. At the sizing stage, the ring’s outer diameter still increases a little. (4) A series of VHRR experiments are conducted, and FE results are in good agreement with experimental results. The absolute errors of the ring’s outer diameter and the roundness are within 1 mm. The research results of this paper have practical significance to guide the VHRR production.

Simulation of T-section profile ring rolling by the 3-D rigid-plastic finite element method

Cold profiled ring rolling (CPRR) is an advanced local incremental forming process with complexity and high nonlinearity. In this process, the feed rate of mandrel is a key factor affecting the expanding speed of ring outer radius and the filling behavior; thus, it is very significant to rationally design the feed rate for precise controlling the deformation process. Aimed at the CPRR process, the problem of feed rate planning under two variable feed patterns, which are constant expanding speed of ring outer radius (P CES) and constant feed amount per ring revolution (P CFA), has been solved successfully by using the hypothesis-testing approach in this paper. First, according to the relation between the ring outer radius R and the ring reduction ΔH, a novel mathematical solution for planning the feed rates under P CES and P CFA has been proposed, in which a series of points of (R, ΔH) under constant feed rate (P CFR) pattern have been taken into consideration. Second, two differential equations obtaining variable feed rate curves under P CES and P CFA have been built and their solving processes have also been given, and subsequently a new quantitative planning flow of variable feed rates has been presented. Third, an example of three feed rates planning under P CFR, P CES, and P CFA for a practical closed cold T-shaped ring rolling process in the design phase has been realized, and their validity has been proven by three-dimensional finite element numerical simulation. The achievements can provide a guideline for planning the feed rates of the relevant complex profiled ring rolling processes to improve efficiency and reduce cost.

The paper presents a brief history of ring rolling development at the Dresden University of Technology (DUT) from the 70s to the present. The technological scope covers the techniques explored at the DUT: Tangential profile ring rolling, axial profile tube rolling/roll plunging and the TRENPRO® method to produce shaped rings. Starting from the state of the art, technological principle, range of application and machine‐oriented implementation of these techniques are described. Furthermore, other common ring rolling variants, such as axial profile ring rolling, skew‐rolling and radial‐axial ring rolling, are taken into consideration. Finally, the authors provide a summary of problems still to be solved and ways to refine and disseminate the “ring rolling” discipline, assessing the rolling methods’ potential as extremely forward‐looking.

Although cold ring rolling (CRR) process is largely used in the manufacturing of profiled rings like bearing races, research on this purpose has been scant. In this study, based on a validated finite element (FE) model, CRR process is simulated regarding the variable and constant feed speeds of the mandrel roll which lead to constant and variable values of the ring's diameter growth rates respectively using a 3D rigid-plastic finite element method (FEM). Major technological problems involved in the process including plastic deformation behavior, strain distribution and its uniformity, Cockcroft and Latham damage field and final outer diameter of ring are fully investigated. The results of simulations would provide a good basis for process control especially feed speed controlled mills and guiding the design and optimization of both cold and hot ring rolling process.

One of the main challenges for profile ring rolling process is to guarantee the filling of ring cross section, which is closely related to the design of ring billet and feeding strategy. In this paper, a conical ring with flange is taken as example. The electric field method was applied to present the preliminary design of cross section for ring billet in the qualitative manner. Through central composite experimental design and FEM, a response surface using dimensions of ring billet cross section as control variables and filling map were obtained to determine the dimensional range of reasonable billet. The flow behavior and forming defects in the conical ring rolling process were analyzed, based on which the under-filling distribution map was generated. Besides the parametric design of ring billet, the feeding strategy was also taken into consideration. The effect of feeding rate on the cross section filling, the deform uniformity, and the temperature distribution uniformity were analyzed. Based on the parametric design of ring billet and feeding strategy design, the practical conical ring rolling process was carried out in a stable manner without macroscopic or microscopic defects, which indicates the design methodology for the profile ring rolling process is reasonable.

A new method of adaptive movement control of guide and conical rolls is proposed in three-dimension finite element (3D FE) simulation of ring rolling. The movement mathematical models of guide and conical rolls are established with combining with the node track method in an FE model. By means of the user subroutine VUAMP interface of ABAQUS, an adaptive roll motion subroutine is written by FORTRAN software, which carried out the adaptive movement control of guide and conical rolls. The simulation results show that the ring can always keep a good circular degree and ensure final deformation quality in ring rolling process. The effectiveness of FE simulation has been verified by practical experiments. It overcomes some shortcomings of the traditional method, such as the large amount of computation, low universality, ubiquitous error, time consuming, and lack of universality and so on. And, it guarantees the balance of ring rolling and the roundness of the rolled ring.

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.

Residual stresses induced in the component by previous thermal/mechanical processes are compressive or tensile stresses having a zero resultant. In particular, they arise as consequence of thermo-mechanical processes (e.g. ring-rolling process), casting and heat treatments. When machining stressed components, volume removal leads to a re-arrangement of residual stresses, which inevitably causes distortions in the workpiece. If distortions are excessive, they can lead to a large number of scrap parts. This paper describes the development of a numerical procedure for the analysis of the distortions on a waspaloy turbine case, obtained by ring rolling process. A 3D model of ring rolling process has been set in the commercial software DEFORM 3D. Three different ring rolling strategies have been analyzed, in order to find the combination of process parameters which allows to obtain the best component in terms of geometrical precision. Then, the heat treatments (air cooling, solubilization, stabilization and aging) have been simulated to predict the bulk residual stresses distributions. Finally, the numerical distortions induced by machining have been simulated considering the material removal in some machining operations.

Research on dynamic measurement of hot ring rolling dimension based on machine vision

Based on the platform ABAQUS, 3-D FEA model for ring rolling has been constructed to investigate the effect of drive roll rotation speed on the metal flow in the ring rolling process. It can be seen clearly that the axial metal flow in the outside diameter of the rolled ring increases with the increasing of drive roll rotation speed and with the decreasing of the feeding magnitude per revolution , which causes the increasing of fishtail coefficient FT and maximum spread coefficient and in turn makes the quality deterioration of end-plane in the rolled ring. The rolling force and rolling torque necessary to execute the rolling process are reduced when the drive roll rotation speed is elevated, which results in the lower requirement for the characteristic of force and energy in the rolling machine. Besides that, average equivalent plastic strain PEEQ also increases, which indicates the enhancement of plastic deformation and is beneficial to the improvement of the mechanical property of the formed ring. But one point that we should pay attention is that uneven deformation and possibility of the inner defects in the rolled ring might be increased with the increasing of the drive roll rotation speed.

Control of strain and temperature distribution in the ring rolling process

Manufacturing large-tapered profile rings by combination of flaring and Confined Axial Ring Rolling processes