A winding device for formation of fibrous rolls includes: a first conveyor and a second conveyor; a movable compression roller which delimits a winding area with guide surfaces of the conveyors; a movable pre-compression conveyor including an upstream roller, a downstream assembly with a curved downstream end, and a belt wound around the upstream roller and the downstream assembly. The belt is held under tension against the downstream assembly and forms, facing the guide surface of the first conveyor, a circulating pre-compression surface for pre-compression of a fibrous mat to be wound, the pre-compression surface being a pre-compression element closest to the winding area.