It`s suitable for the bend and deformation of the metal plates and it can roll the round and arcshapes and the cone ones within its specified ranges. It has the function of prebending the plate at both ends. The two lower rollers are the driving ones and can make the horizontal movement; And the upper is a driven one and can make the up and down movement. The moving manner includes the mechanical and industry, boilers, shipbuilding, metal structure, machine manufacture and other trades, especially for the roll the steel trunks with smaller diameter and longer length in power transmission and trandform and other trades.