| Ring rolling is a metal forming operation that reduces the thickness (cross section) and enlarges the diameter (circumference) of the workpiece by a squeezing action as it passes between two rotating rolls. The ring rolling process is widely used to produce seamless rings with outer diameters ranging from 100 mm up to 8 m with cold or hot workpieces. These rings are commonly used as flanges, pipe flanges, ring gears, structural rings, gas-turbine rings, and so on. The ring rolling process has significant advantages over other processes, such as closed die forging, casting and welding, in providing significant material savings while reducing the machining time and maintaining high quality of the product.; The upper bound element technique (UBET) is used to simulate the profile ring rolling by forward simulation, and to determine the optimum intermediate shape for profile ring rolling using backward simulation. The lowest energy rate is the key issue in achieving the optimal intermediate shape as well as the backward simulation of the process. The plastic flow of material in ring rolling is assumed to be a sequence of successive closed-die forging processes. The ring is divided into features, which provide an approximated profile consisting of a number of rectangular elements. The simulations of the profile ring rolling of both forward and backward simulation were tested with different profiles of rolls, and these were presented in this work. The present method was validated using an experimental radial ring rolling mill designed and fabricated in the Dept. of ME at Ohio University for the investigation of both cold and hot rolling. This radial ring rolling mill was also instrumented to improve its efficiency and performance. Experiments were performed using lead at room temperature and various aluminum alloys at elevated temperatures. As the experimental results indicate, this ring rolling mill is capable of rolling circular rings with fairly good results. The results also indicate that the proposed method is capable of solving geometrically complex ring-rolling problems using a relatively small number of simple UBET elements.; The modeling of the UBET results is computer simulation of the profile ring rolling process. It helps engineers to design the profile ring rolling process before they are tried on the “shop floor”. This saves time and money while improving the quality and profitability of the final product. Therefore, one of the objectives of this research is to develop a simulation software tool for the ring rolling process based on UBET. The simulation software tool was developed using C++ and a visualization/animation module using Java to make it Web-ready. The simulation software tool was tested with different profiles. As results show, this technique is capable of solving ring-rolling problems that are geometrically complex, within a shorter period of time compared to that required by FEM. Moreover, as an engineering tool, this approach can be applied effectively to the profile ring rolling process and can serve as a powerful tool in industrial applications. |
