VERFAHREN UND VORRICHTUNG ZUM ERZEUGEN EINES GLEICHFOERMIGEN DUENNEN UEBERZUGES AUF DER GESAMTEN INNENFLAECHE VON ROHRFOERMIGEN KOERPERN

摘要

A method and apparatus for coating the inside of tubular members, more specifically can bodies, which are open at opposite ends. The apparatus includes a supply tube and a return tube which are spaced apart to have received therebetween the tubular member to be coated. In each of the supply tube and the return tube there is positioned a corona electrode, the corona electrodes being in alignment wherein powder supplied to the interior of the tubular member is both initially charged as it passes through the supply tube and is further charged within the tubular member by an electrical field which exists between the two corona electrodes and the tubular member. Powder is supplied to the supply tube through a small diameter passage as compared to the diameter of the supply tube and there is provided a diverter which effects radially outward flow of incoming powder so that the powder is concentrated substantially adjacent the inner surface of the supply tube so that the powder delivered to the tubular member flows substantially entirely along the inner surface of the tubular member. The method and apparatus permits the provision of a thin coating on the tubular member which is uniform in thickness even at opposite ends thereof.