In order to secure the precise straightness, the steel bars is reformed by bender. Up to this time, this bender has been operated by experts. However, the number of experts has been decreasing year by year. Automatic reformation is required.
This paper presents a reformation scheme to cope with variations in physical characteristics of the steel bars, and an estimation method of the stress required to reform the steel bars using a fuzzy clustering method. The results of simulations are highly satisfactory. The precision of reform experiment also satisfies the target.