Plugs for use in piercing and elongating mills
AssigneeNippon Kokan Kabushiki Kaisha
InventorsManabu Tamura, Yoshiki Kamemura, Masao Handa
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Abstract
A plug for use in a piercing and elongating mill characterizing in that an adherent durable surface layer consisting essentially of iron oxides, i.e. FeO, Fe.sub.3 O.sub.4, Fe.sub.2 O.sub.3 or mixtures thereof is formed on the surface of the plug by spraying said molten iron oxide powder onto the plug surface to form said layer. The powder may also contain oxides of chromium, nickel, cobalt, copper, manganese and alloys thereof. The plug is preferably coated with a layer of nickel aluminum before the iron oxide powder is sprayed thereon.
Claims15
A plug for use in a piercing and elongating mill to manufacture seamless steel pipes having its surface coated with a highly adherent durable heat insulating layer consisting essentially of iron oxides comprising at least one oxide selected from the group consisting of FeO, Fe.sub.3 O.sub.4, and Fe.sub.2 O.sub.3 which had been formed on the surface of said plug by spraying molten powder consisting essentially of iron oxide onto the surface of the plug to form said layer, said iron oxide molten powder which is sprayed onto the surface of said plug also contains at least one metal or oxide selected from the group consisting of the oxides of chromium, nickel, copper and manganese, and the metals iron, chromium, nickel, cobalt, copper and manganese.
The plug of claim 3, wherein said insulating layer has a thickness of between 0.05 and 2 mm.
A plug for use in a piercing and elongating mill to manufacture seamless steel pipes having its surface coated with a highly adherent durable heat insulating layer consisting essentially of iron oxides comprising at least one oxide selected from the group consisting of FeO, Fe.sub.3 O.sub.4, and Fe.sub.2 O.sub.3 which had been formed on the surface of said plug by spraying a molten mixture of nickel and aluminum powders on the surface of said plug and then by spraying molten powder consisting essentially of iron oxide onto said layer formed by said spraying of nickel and aluminum to form said heat insulating layer with said layer formed by said spraying of nickel and aluminum being between the surface of the plug and said insulating layer and being integral with said surface of the plug and said insulating layer.
Dependencies are inferred from the claim text.