Device for applying a protective coating to the weld or solder seam of a can body

A device for applying a protective coating to the weld or solder seams of can bodies, said device comprising an application roller which serves to apply a coating material over the region covering the seam at the inside surface of the can body, said roller having a profile defining laterally opposed convex shaped supporting edges which serve to support the can body on the roller and a generally convex shaped middle portion lying between said supporting edges which serves to entrain and apply said coating material, the profile of said middle portion having at least two maxima substantially equal in height and which are situated relatively close to one another and project a greater distance from the axis of rotation of said roller than the laterally opposed supporting edges, said maxima further defining the outer limits of a middle region of said middle portion, said middle region having at least one depression lying between said maxima and defining within said region a minimum distance between the axis of rotation of said roller and the surface of said roller, the distance from the surface of said roller to the axis of rotation of said roller at the laterally opposed outer ends of said middle portion being less than the distance from the surface of said roller at the nearest maxima associated with each of said ends to the axis of rotation of said roller, the distance from the surface of said roller to the axis of rotation of said roller increasing continuously from the end points of said middle portion to the nearest maxima, respectively, and the distance from the surface of each of said laterally opposed supporting edges to the axis of rotation of said roller being less than the distance from the surface of the nearest maxima associated with each of said supporting edges to the axis of rotation of said roller.