Optimization of bending condition for dieless U-bending process: development of dieless bending process for precision-bent tube II

摘要

The present paper follows a previous paper by the same authors, in which the dieless bending process was proposed. In this process, compared to the conventional draw-bending process, the bending die is not necessary and high productivity can be realized. Although in the previous study the bending radius was well simulated by theoretical analysis under various bending conditions, a constant bending radius within the whole bending region had still not been realized. In the present study, the effects of bending condition control during bending on the bending radius distribution were clarified by numerical analyses and experiments. Moreover, the optimum conditions for realizing a constant bending radius distribution were calculated by inverse analysis. Finally, the calculated results were verified by experiments for various bending radii in the range of 300-1700 mm. As a result, the dieless bending process was successfully applied to the production of stainless steel tubes and nickel-based alloy tubes installed in nuclear and thermal power plants.