Method and apparatus for manufacturing a squirrel cage rotor

Claim 1

A method of manufacturing a squirrel cage winding assembly employing an extrusion press for fabricating a plurality of conductor bar windings interconnected at each end by conductive end rings to a rotor core having a circumferential series of axial slots, the steps comprising: positioning said rotor core in an extrusion press including a die plate having an annular die cavity communicating with said axial slots at one rotor core end, positioning the other end of said rotor core adjacent an extrusion chamber communicating with said axial slots; placing a hollow slug of electrically conductive material in said extrusion chamber adjacent to and abutting said other end of said rotor core; heating said slug to a temperature below the melting point of said electrically conductive material to reduce the flow resistance of said slug; extruding said slug from said extrusion chamber axiallY into said axial slots to form conductor bars therein; forming a continuously bonded end ring portion in said annular die cavity from said electrically conductive material extruded into said die plate from said axial slots; and terminating said extruding when a predetermined unextruded terminal portion of said slug extends from said other end of said rotor core, whereby said conductive end rings are formed to integrally interconnect the ends of said conductor bar windings at each end of said rotor core.

Claim 2

A method of manufacturing a squirrel cage winding assembly employing an extrusion press for fabricating a plurality of conductor bar windings interconnected at each end by conductive end rings to a rotor core having a circumferential series of axial slots, the steps comprising: positioning said rotor core in an extrusion press including a die plate having an annular die cavity communicating with said axial slots at one rotor core end, positioning the other end of said rotor core adjacent an extrusion chamber communicating with said axial slots; placing a hollow slug of electrically conductive material in said extrusion chamber adjacent to and abutting said other end of said rotor core; heating said slug to a temperature below the melting point of said electrically conductive material to reduce the flow resistance of said slug; extruding said slug from said extrusion chamber axiallY into said axial slots to form conductor bars therein; forming a continuously bonded end ring portion in said annular die cavity from said electrically conductive material extruded into said die plate from said axial slots; and terminating said extruding when a predetermined unextruded terminal portion of said slug extends from said other end of said rotor core, whereby said conductive end rings are formed to integrally interconnect the ends of said conductor bar windings at each end of said rotor core.

Claim 3

A method of manufacturing a squirrel cage rotor employing an extrusion press for fabricating a squirrel cage winding assembly including a plurality of conductor bar windings interconnected at each end by conductive end rings, the steps comprising: assembling a stack of laminations having circumferentially spaced openings to form a rotor core having said openings aligned at a predetermined skew angle for providing a circumferential series of axial slots; mounting said rotor core in said extrusion press with the openings of said axial slots at one end of said rotor core positioned adjacent a die plate including an end ring die cavity communicating with said axial slots; positioning the other end of said rotor core adjacent an annular extrusion chamber formed by parallel extending cylindrical walls communicating with openings of said axial slots at said other end of said rotor core; providing a hollow cylindrical slug made of aluminum and having a predetermined size for being contained in said annular extrusion chamber; inserting said hollow cylindrical slug in said annular extrusion chamber adjacent to and abutting said other end of said rotor core; heating said hollow cylindrical slug within a temperature range which is below the melting point of said aluminum material so as to reduce the uniaxial flow resistance of said hollow cylindrical slug; applying force to said hollow cylindrical slug to extrude the slug from said annular extrusion chamber axially into said axial slots to provide conductor bar windings therein; forming said aluminum material exited from said one end of said rotor core and into said end ring die cavity so as to form a unitary conductive end ring which is integral with said conductor bar windings at said one end of said rotor core; terminating the applying force when a predetermined unextruded terminal portion of said hollow cylindrical slug extends from said other end of said rotor core to provide a conductive end ring which is integral with said conductor bar windings at said other end of said rotor core.

Claim 4

A method of manufacturing a squirrel cage rotor employing an extrusion press for fabricating a squirrel cage winding assembly including a plurality of conductor bar windings interconnected at each end by conductive end rings, the steps comprising: assembling a stack of laminations having circumferentially spaced openings to form a rotor core having said openings aligned at a predetermined skew angle for providing a circumferential series of axial slots; mounting said rotor core in said extrusion press with the openings of said axial slots at one end of said rotor core positioned adjacent a die plate including an end ring die cavity communicating with said axial slots; positioning the other end of said rotor core adjacent an annular extrusion chamber formed by parallel extending cylindrical walls communicating with openings of said axial slots at said other end of said rotor core; providing a hollow cylindrical slug made of aluminum and having a predetermined size for being contained in said annular extrusion chamber; inserting said hollow cylindrical slug in said annular extrusion chamber adjacent to and abutting said other end of said rotor core; heating said hollow cylindrical slug within a temperature range which is below the melting point of said aluminum material so as to reduce the uniaxial flow resistance of said hollow cylindrical slug; applying force to said hollow cylindrical slug to extrude the slug from said annular extrusion chamber axially into said axial slots to provide conductor bar windings therein; forming said aluminum material exited from said one end of said rotor core and into said end ring die cavity so as to form a unitary conductive end ring which is integral with said conductor bar windings at said one end of said rotor core; terminating the applying force when a predetermined unextruded terminal portion of said hollow cylindrical slug extends from said other end of said rotor core to provide a conductive end ring which is integral with said conductor bar windings at said other end of said rotor core.