Tube pump for removing dross during galvanizing

Abstract

A tube pump includes a tube having a closed off lower end portion and an open upper end portion. The upper end portion of the tube is adapted to be fastened to support structure. The lower end portion is adapted to be submerged in molten metal. The tube includes an inlet opening and an outlet opening. A pump shaft is adapted to be connected to a motor driven drive shaft and has upper and lower end portions. The pump shaft extends inside the tube. An impeller is fastened to the lower end portion of the pump shaft and disposed near a lower end portion of the tube. Inlet and outlet conduits are connected to the tube inlet and outlet openings adjacent to a top or bottom of the impeller so that a conduit inlet opening is disposed near the surface of the bath and a conduit outlet opening is disposed remote from the conduit inlet opening. The tube pump removes dross from the galvanizing bath to produce galvanized parts having improved properties.

What is claimed is: 
     
         1 . A tube pump that is suitable for use in removing dross during galvanizing, comprising
 a tube having a closed lower end portion and an open upper end portion, said lower end portion being adapted to be submerged in molten metal, said upper end portion of said tube being adapted to be fastened to support structure outside of a molten metal bath, said tube including an inlet opening and an outlet opening;   a pump shaft having upper and lower end portions, said upper end portion of said pump shaft being adapted to be connected to a motor drive shaft, and said pump shaft extending inside said tube;   an impeller fastened to the lower end portion of said pump shaft and disposed near a lower end portion of said tube;   an inlet conduit having one end portion connected to the inlet opening of said tube adjacent to a top or bottom of said impeller and an inlet end portion with an inlet opening disposed near a surface of the bath;   an outlet conduit having one end portion connected to the outlet opening of said tube adjacent to a top or bottom of said impeller and an outlet end portion remote from the inlet opening of said inlet conduit.   
     
     
         2 . The tube pump of  claim 1  wherein said impeller has an auger or screw shape. 
     
     
         3 . The tube pump of  claim 1  wherein said inlet conduit is disposed above said impeller and said outlet conduit is disposed below said impeller, and said pump shaft is rotated and its screw threads have a twist direction such that molten metal travels downward upon rotation of said impeller in said refractory tube, which causes molten metal to be drawn from said inlet opening into said impeller and down to said outlet conduit and transferred to the outlet opening, thereby causing the molten metal to have lesser surface dross in a region near the inlet opening. 
     
     
         4 . The tube pump of  claim 1  wherein said tube, said pump shaft, said inlet conduit, said outlet conduit and said impeller are comprised of graphite or a ceramic material. 
     
     
         5 . The tube pump of  claim 1  wherein said outlet conduit extends out of the molten metal bath into another vessel for removal of the dross from the molten metal bath. 
     
     
         6 . The tube pump of  claim 1  wherein said inlet conduit and said outlet conduit are so close to said impeller that said pump effectively operates with zero head increasing pumping efficiency. 
     
     
         7 . A tube pump that is suitable for use in removing dross during galvanizing, comprising
 a tube including a closed lower end portion and an open upper end portion, the lower end portion being adapted to be submerged in molten metal and the upper end portion adapted to be fastened to support structure, and an inlet opening and an outlet opening;   a pump shaft having upper and lower end portions, the upper end portion of said pump shaft being connected to a motor driven drive shaft, and said pump shaft extends inside said tube;   an impeller fastened to the lower end portion of said pump shaft and disposed near a lower end portion of said tube, wherein said impeller has an auger or screw shape;   an inlet conduit having one end portion connected to the inlet opening of said tube adjacent to a top or bottom of said impeller and an inlet end portion with an inlet opening disposed near a surface of the bath;   an outlet conduit having one end portion connected to the outlet opening of said tube adjacent to a top or bottom of said impeller and an outlet end portion remote from the inlet opening of said inlet conduit;   wherein said tube, said impeller, said pump shaft, said inlet conduit, and said outlet conduit are comprised of graphite or a ceramic material;   wherein said inlet conduit is disposed above said impeller and said outlet conduit is disposed below said impeller, and said pump shaft is rotated in a direction and its screw threads have a twist direction such that molten metal travels downward upon rotation of said impeller in said tube, which causes molten metal to be drawn from said inlet opening into said impeller and down to said outlet conduit and transferred to the outlet opening, thereby causing the molten metal to have lesser surface dross in a region near the inlet opening.   
     
     
         8 . A system for galvanizing metal parts comprising:
 a degreasing bath;   an optional rinse station after said degreasing bath;   a pickling bath;   an optional rinse station after said picking bath;   a fluxing bath;   a drying station; and   a galvanizing bath containing molten metal and said tube pump of  claim 1  disposed in said galvanizing bath, wherein operation of said tube pump clears a region of the molten metal near the inlet opening so as to have reduced dross;   a mechanism for placing said parts inside said galvanizing bath in the clear region of the molten metal and for removing said parts from said molten metal bath,   wherein said tube pump operation produces metal galvanized parts with reduced defects, lesser corrosion and/or higher strength.