Method and apparatus for manufacture of a squirrel cage rotor

Claim 1

A method of manufacturing a squirrel cage rotor for fabricating conductor bar windings interconnected at each end by conductive end rings to a rotor core having a circumferential series of axial winding slots, the steps comprising: positioning said rotor core in an extrusion press having extrusion chambers communicating with opposite ends of said axial winding slots; placing hollow cylindrical slugs having predetermined heights and made of an electrically conductive material in said extrusion chambers with one slug adjacent to and abutting each end of said rotor core; heating said slugs to a temperature below the melting point of said electrically conductive material to reduce the flow resistance of said slug; extruding said slugs from said extrusion chambers axially into said axial winding slots; terminating said extruding when the extruded materials of said slugs are bonded together in said winding slots to form said conductor bar windings; and providing predetermined unextruded terminal portions in each of said slugs thereby forming said conductive end rings integrally connected with the ends of said conductor bar windings at the ends of said rotor core.

Claim 2

A method of manufacturing a squirrel cage rotor for fabricating conductor bar windings interconnected at each end by conductive end rings to a rotor core having a circumferential series of axial winding slots, the steps comprising: positioning said rotor core in an extrusion press having extrusion chambers communicating with opposite ends of said axial winding slots; placing hollow cylindrical slugs having predetermined heights and made of an electrically conductive material in said extrusion chambers with one slug adjacent to and abutting each end of said rotor core; heating said slugs to a temperature below the melting point of said electrically conductive material to reduce the flow resistance of said slug; extruding said slugs from said extrusion chambers axially into said axial winding slots; terminating said extruding when the extruded materials of said slugs are bonded together in said winding slots to form said conductor bar windings; and providing predetermined unextruded terminal portions in each of said slugs thereby forming said conductive end rings integrally connected with the ends of said conductor bar windings at the ends of said rotor core.

Claim 3

A method of manufacturing a squirrel cage rotor for fabricating conductor bar windings interconnected at each end by conductive end rings to a rotor core having a circumferential series of axial winding slots, the steps comprising: assembling a stack of laminations having circumferentially spaced slot openings aligned at a predetermined skew angle to form a rotor core having a circumferential series of axial winding slots; positioning said rotor core in an extrusion press having extrusion chambers communicating with opposite ends of said axial winding slots; providing a pair of hollow cylindrical slugs made of aluminum and having predetermined sizes for filling said axial winding slots and for forming said conductive end rings from terminal portions thereof; placing one of said pair of slugs in each of said extrusion chambers adjacent to and abutting each end of said rotor core; heating said pair of slugs to a predetermined temperature range below the melting point of said aluminum material to reduce the flow resistance of said slug; extruding said pair of slugs from said extrusion chambers axially into said axial winding slots; terminating said extruding when the extruded aluminum materials of said pair of slugs are bonded together in said axial winding slots to form said conductor bar windings; and providing said terminal portions by unextruded ends of each of said pair of slugs thereby forming said conductive end rings integrally connected with the ends of said conductor bar windings at the ends of said rotor core.

Claim 4

A method of manufacturing a squirrel cage rotor for fabricating conductor bar windings interconnected at each end by conductive end rings to a rotor core having a circumferential series of axial winding slots, the steps comprising: assembling a stack of laminations having circumferentially spaced slot openings aligned at a predetermined skew angle to form a rotor core having a circumferential series of axial winding slots; positioning said rotor core in an extrusion press having extrusion chambers communicating with opposite ends of said axial winding slots; providing a pair of hollow cylindrical slugs made of aluminum and having predetermined sizes for filling said axial winding slots and for forming said conductive end rings from terminal portions thereof; placing one of said pair of slugs in each of said extrusion chambers adjacent to and abutting each end of said rotor core; heating said pair of slugs to a predetermined temperature range below the melting point of said aluminum material to reduce the flow resistance of said slug; extruding said pair of slugs from said extrusion chambers axially into said axial winding slots; terminating said extruding when the extruded aluminum materials of said pair of slugs are bonded together in said axial winding slots to form said conductor bar windings; and providing said terminal portions by unextruded ends of each of said pair of slugs thereby forming said conductive end rings integrally connected with the ends of said conductor bar windings at the ends of said rotor core.