Apparatus and method for cold extrusion of gears

Claim 2

A process for extruding gears with fully formed gear teeth comprising the steps of inserting a first hollow blank within a die having internal teeth, said internal teeth comprising a full depth portion extending axially for a small part of the axial dimension of said die and a relatively long portion that is relieved to provide guiding action with minimum friction as the blank progresses through said die and to provide support for the full depth portion of the die teeth, the blank having received therethrough a mandrel with a precise diametrical fit within the central opening in the blank, a sleeve surrounding the mandrel and forming therewith a mandrel and sleeve assembly, advancing the mandrel and sleeve assembly and applying thereby an axial extruding force on the blank whereby the blank is partially extruded through the die tooth spaces, retracting the mandrel and sleeve assembly and placing a second hollow blank adjacent the first blank, and advancing the mandrel and sleeve assembly into engagement with the second blank whereby final extrusion of the first blank to form a finished gear occurs as the second blank is partially extruded, the outside diameter of each blank being substantially equal to the outside diameter of the corresponding gear.

Claim 3

The method steps set forth in claim 1 wherein the mandrel provides radial support for the hollow blank as the blank is forced through the die tooth spaces thereby controlling the blank material flow so that fully formed teeth are extruded as radial material flow of blank material is resisted.

Claim 4

The method steps set forth in claim 2 wherein the mandrel is provided with a cylindrical portion of predetermined diameter adjacent one end of the sleeve whereby the internal diameter of the hollow extruded blank is controlled.

Claim 5

A process for extruding gears comprising the steps of inserting a cylindrical workpiece in an extrusion die, said die having a central opening within which the workpiece is fitted, a backup punch located on one side of said die and an extrusion punch adapted to advance into the workpiece from the other side thereof, said extrusion punch causing axial flow of the material of said workpiece in a direction opposite to the direction of motion of said extrusion punch, transferring said workpiece to a piercing die that surrounds said workpiece, moving a piercing punch through the workpiece thereby shearing the material from the center of said workpiece to provide a bore therethrough, transferring the finished workpiece to a gear extrusion die that surrounds the workpiece, said die having internal helical teeth formed therein, inserting a mandrel through the extrusion die and through the workpiece, said mandrel having on one end thereof a calibrated inside diameter forming portion, applying an extrusion force to said workpiece by a mandrel sleeve thereby moving the workpiece through the internal teeth cavity of the extrusion die, retracting the mandrel whereby the inside diameter of said workpiece is precisely maintained at a desired value and mounting another pierced workpiece adjacent the aforesaid workpiece and applying an extrusion force, the first mentioned workpiece being pushed from the extrusion die by the second mentioned workpiece.

Claim 6

A process for extruding gears comprising the steps of inserting a cylindrical workpiece in an extrusion die, said die having a central opening within which the workpiece is fitted, a backup punch located on one side of said die and an extrusion punch adapted to advance into the workpiece from the other side thereof, said extrusion punch causing axial flow of the material of said workpiece in a direction opposite to the direction of motion of said extrusion punch, transferring said workpiece to a piercing die that surrounds said workpiece, moving a piercing punch through the workpiece thereby shearing the material from the center of said workpiece to provide a bore therethrough, transferring the finished workpiece to a gear extrusion die that surrounds the workpiece, said die having internal helical teeth formed therein, inserting a mandrel through the extrusion die and through the workpiece, said mandrel having on one end thereof a calibrated inside diameter forming portion, applying an extrusion force to said workpiece by a mandrel sleeve thereby moving the workpiece through the internal teeth cavity of the extrusion die, retracting the mandrel whereby the inside diameter of said workpiece is precisely maintained at a desired value and mounting another pierced workpiece adjacent the aforesaid workpiece and applying an extrusion force, the first mentioned workpiece being pushed from the extrusion die by the second mentioned workpiece.

Claim 7

The combination as set forth in claim 4 wherein the piercing operation includes entry of a punch through the workpiece, said punch being surrounded by a punch sleeve that maintains the workpiece in position, said punch shearing the material from the center of the extruded workpiece thereby forming a relatively uniform hole through the said workpiece.

Claim 8

The extrusion process as set forth in claim 4 wherein the extrusion step is preceded by a squaring step whereby the workpiece which is generally cylindrical in shape is inserted in a squaring die, a backup punch located in said squaring die adjacent said blank, said squaring die surrounding said workpiece and restraining radially outward flow of material of the workpiece and advancing a squaring punch into said squaring die to form the workpiece to provide a controlled surface configuration on either axial side of said workpiece and to form a uniform outside diameter on said workpiece.

Claim 9

The extrusion process as set forth in claim 5 wherein the extrusion step is preceded by a sizing step whereby the workpiece which is generally cylindrical in shape is inserted in a sizing die, a backup punch located in said sizing die adjacent to said blank, said sizing die surrounding said workpiece and restraining radially outward flow of material of the workpiece and advancing a sizing punch into said sizing die to the workpiece to provide a controlled surface configuration on either axial side of said workpiece and to form a uniform outside diameter on said workpiece.

Claim 10

The extrusion process as set forth in claim 4 wherein the extrusion step is preceded by a sizing step whereby the workpiece which is generally cylindrical in shape is inserted in a sizing die, a backup punch located in said sizing die adjacent said blank, said sizing die surrounding said workpiece and restraining radially outward flow of material of the workpiece and advancing a sizing punch into said sizing die to form the workpiece to provide a controlled surface configuration on either axial side of said workpiece and to form a uniform outside diameter on said workpiece.

Claim 11

The extrusion process as set forth in claim 5 wherein the extrusion step is preceded by a sizing step whereby the workpiece which is generally cylindrical in shape is inserted in a sizing die, a backup punch located in said sizing die adjacent said blank, and sizing die surrounding said workpiece and restraining radially outward flow of material of the workpiece and advancing a sizing punch into said sizing die to form the workpiece to provide a controlled surface configuration on either axial side of said workpiece and to form a uniform outside diameter on said workpiece.

Claim 12

A gear extrusion process comprising the steps of inserting a first hollow blank within a die having internal teeth, the blank having received therethrough a mandrel with a precise diametrical fit within the central opening in the blank, a sleeve surrounding the mandrel and forming therewith a mandrel and sleeve assembly, advancing the mandrel and sleeve assembly and applying thereby an axial extruding force on the blank whereby the blank is partially extruded through the die tooth spaces, retracting the mandrel and sleeve assembly and placing a second hollow blank adjacent the first blank, and advancing the mandrel and sleeve assembly into engagement with the second blank whereby final extrusion of the first blank occurs as the second blank is partially extruded, said mandrel having a straight shaft portion and a circular land portion of larger diameter than the shaft portion, including the step of withdrawing said mandrel following extrusion whereby the land portion precisely sizes the inside diameter of the finished extruded part.

Claim 13

A gear extrusion process comprising the steps of inserting a first hollow blank within a die having internal teeth, the blank having received therethrough a mandrel with a precise diametrical fit within the central opening in the blank, a sleeve surrounding the mandrel and forming therewith a mandrel and sleeve assembly, advancing the mandrel and sleeve assembly and applying thereby an axial extruding force on the blank whereby the blank is partially extruded through the die tooth spaces, retracting the mandrel and sleeve assembly and placing a second hollow blank adjacent the first blank, and advancing the mandrel and sleeve assembly into engagement with the second blank whereby final extrusion of the first blank occurs as the second blank is partially extruded, said mandrel having a straight shaft portion and a circular land portion of larger diameter than the shaft portion, including the step of withdrawing said mandrel following extrusion whereby the land portion precisely sizes the inside diameter of the finished extruded part.

Claim 14

An extrusion die assembly comprising a circular extrusion die with internal teeth, a die holder supporting said die, a mandrel with a circular shaft portion of predetermined diameter, and a central opening in said holder receiving said die, said mandrel extending through said central opening and aDapted to be received through a hollow gear blank, a sleeve punch surrounding said mandrel and forming therewith a mandrel and sleeve assembly, said sleeve being adapted to engage one axial side of said blank as said mandrel and sleeve assembly is advanced thereby extruding said blank through said die, the shaft portion of said mandrel providing radial support for the material of said blank thereby controlling the blank material displacement during extrusion which results in full, precise tooth development during extrusion, said mandrel having formed thereon a land portion of larger diameter than said shaft portion whereby the inside diameter of said hollow blank, following extrusion, is precisely controlled upon withdrawl of said mandrel and sleeve assembly in a direction opposite to the direction of the advance thereof during extrusion.

Claim 15

An extrusion die assembly comprising a circular extrusion die with internal teeth, a die holder supporting said die, a mandrel with a circular shaft portion of predetermined diameter, and a central opening in said holder receiving said die, said mandrel extending through said central opening and aDapted to be received through a hollow gear blank, a sleeve punch surrounding said mandrel and forming therewith a mandrel and sleeve assembly, said sleeve being adapted to engage one axial side of said blank as said mandrel and sleeve assembly is advanced thereby extruding said blank through said die, the shaft portion of said mandrel providing radial support for the material of said blank thereby controlling the blank material displacement during extrusion which results in full, precise tooth development during extrusion, said mandrel having formed thereon a land portion of larger diameter than said shaft portion whereby the inside diameter of said hollow blank, following extrusion, is precisely controlled upon withdrawl of said mandrel and sleeve assembly in a direction opposite to the direction of the advance thereof during extrusion.

Claim 16

An extrusion die assembly comprising a circular extrusion die with internal teeth, a die holder supporting said die, a mandrel with a circular shaft portion of predetermined diameter, and a central opening in said holder receiving said die, said mandrel extending through said central opening and adapted to be received through a hollow gear blank, a sleeve punch surrounding said mandrel and forming therewith a mandrel and sleeve assembly, said sleeve being adapted to engage one axial side of said blank as said mandrel and sleeve assembly is advanced thereby extruding said blank through said die, the shaft portion of said mandrel providing radial support for the material of said blank thereby controlling the blank material displacement during extrusion which results in full, precise tooth development during extrusion, said die assembly including a die stress ring in said holder surrounding said circular die, said stress ring providing radial support for said die.

Claim 17

An extrusion die assembly comprising a circular extrusion die with internal teeth, a die holder supporting said die, a mandrel with a circular shaft portion of predetermined diameter, and a central opening in said holder receiving said die, said mandrel extending through said central opening and adapted to be received through a hollow gear blank, a sleeve punch surrounding said mandrel and forming therewith a mandrel and sleeve assembly, said sleeve being adapted to engage one axial side of said blank as said mandrel and sleeve assembly is advanced thereby extruding said blank through said die, the shaft portion of said mandrel providing radial support for the material of said blank thereby controlling the blank material displacement during extrusion which results in full, precise tooth development during extrusion, said die assembly including a die stress ring in said holder surrounding said circular die, said stress ring providing radial support for said die.

Claim 18

The method steps set forth in claim 10 wherein the mandrel provides radial support for the hollow blank as the blank is forced through the die tooth spaces thereby controlling the blank material flow so that fully formed teeth are extruded as radial material flow of blank material is resisted.

Claim 19

The method steps set forth in claim 13 wherein the mandrel is provided with a cylindrical portion of predetermined diameter adjacent one end of the sleeve whereby the internal diameter of the hollow extruded blank is controlled.

Claim 20

An extrusion die assembly for extruding a hollow blank comprising a circular extrusion die with internal teeth, comprising a full depth portion extending axially for a small part of the axial dimension of said die and a relatively long portion that is relieved to provide guiding action with minimum friction as the blank progresses through said die and to provide support for the full depth portion of the die teeth, a die holder supporting said die, a mandrel with a circular shaft portion of predetermined diameter, and a central opening in said holder receiving said die, said mandrel extending through said central opening and adapted to be received through said hollow gear blank, a sleeve punch surrounding said mandrel and forming therewith a mandrel and sleeve assembly, said sleeve being adapted to engage one axial side of said blank as said mandrel and sleeve assembly is advanced thereby extruding said blank through said die, the shaft portion of said mandrel providing radial support for the material of said blank thereby controlling the blank material displacement during extrusion which results in full, precise tooth development during extrusion, the outside diameter of the final extrusion being substantially equal to the outside diameter of said blank.

Claim 21

An extrusion die assembly for extruding a hollow blank comprising a circular extrusion die with internal teeth, comprising a full depth portion extending axially for a small part of the axial dimension of said die and a relatively long portion that is relieved to provide guiding action with minimum friction as the blank progresses through said die and to provide support for the full depth portion of the die teeth, a die holder supporting said die, a mandrel with a circular shaft portion of predetermined diameter, and a central opening in said holder receiving said die, said mandrel extending through said central opening and adapted to be received through said hollow gear blank, a sleeve punch surrounding said mandrel and forming therewith a mandrel and sleeve assembly, said sleeve being adapted to engage one axial side of said blank as said mandrel and sleeve assembly is advanced thereby extruding said blank through said die, the shaft portion of said mandrel providing radial support for the material of said blank thereby controlling the blank material displacement during extrusion which results in full, precise tooth development during extrusion, the outside diameter of the final extrusion being substantially equal to the outside diameter of said blank.