Most of products used in the real life are made by a plastic forming. One of the plastic works, rolling process, has the improved characteristic to make the homogeneous structure property. Also, compared to casting or forging, the rolling process has an advantage to be far superior production speed. Especially, this process utilized in various field such as automotive, aerospace and industrial machinery etc. can produce a high quality seamless ring product.
Ring rolling process is one of the most efficient methods to produce circular products. Despite value for practical use in various industry field, selecting a forming condition of this process is complicated by non-linearity and instability. So, in the industry, ring products are being produced by using inefficient forming conditions. These are given cause for poor quality of ring products. In order to reducing dynamic contact between ring workpiece and tools, a model called CGVC which method is to expand an outer radius of the ring constantly was suggested. However, this condition model wasn''t verified yet. In this paper, the workability is evaluated by combining with a processing map for aluminum 7050 alloy and results for FE analysis.
Through the study, the following conclusions are drawing;
(1) RPM of the main roll became known to the important variable in existing model, however, the speed of revolution is irrelevant to a prime variable for CGVC model through this study. Though RPM of the main roll influences on the thickness reduction of the ring, this factor should be considered seriously.
(2) The upper and lower limit value of growth rate of the ring are proposed according to the geometric constraint. The limit values and median value are used in this study. When the supremum growth rate is used, the process ceases because of the biting condition. While when the median and lower growth rate are used, the ring rolling process is completed stably.
(3) A comparison with the flow instability of the CGVC model and the real condition which is not considered to expanding of the ring, they aren''t much difference in the productivity when using the lower limit in CGVC model. However, in respect of the instability, the forming difficulty decreases nearly 68%. Consequentially, the workability is superior when using the CGVC model.
(4) Using the median value of the growth rate in the CGVC model, the flow instability increase by 0.7% than the case of the lower limit value of growth rate. However, this condition can decrease to halve the production time.
(5) Consequently, using the median value of growth rate according to the constraint, the ring production has a high quality as well as the productivity.