Method and apparatus for heat treating camshafts

Claim 1

An apparatus for heat treating a plurality of unhardened cam lobes on a camshaft, comprising: support means for supporting the camshaft for rotation about a longitudinal axis; means for selectively rotating said camshaft about said axis; inductor means adapted to encircle the cam lobes in inductive heating relationship therewith; drive means for locating said inductor means sequentially at the unhardened cam lobes; shield means movable to an operative position closely encircling the camshaft between successive cam lobes including the cam lobes then located at said inductor means; means for energizing said inductor means when said shield means is in said operative position to inductively heat the unhardened cam lobe to a predetermined heat treating temperature; first cooling means operative subsequent to said energizing for delivering liquid media on the cam lobe at said heat treating temperature and cool such cam lobe at a controlled rate to provide a predetermined surface hardness; second cooling means for delivering liquid media on the hardened cam lobe adjacent said shield means after said shield means is in said operative position concurrent with said inductor means and said first cooling means, said second cooling means providing sufficient cooling of said hardened cam lobe to prevent tempering thereof.

Claim 2

An apparatus for heat treating a plurality of unhardened cam lobes on a camshaft, comprising: support means for supporting the camshaft for rotation about a longitudinal axis; means for selectively rotating said camshaft about said axis; inductor means adapted to encircle the cam lobes in inductive heating relationship therewith; drive means for locating said inductor means sequentially at the unhardened cam lobes; shield means movable to an operative position closely encircling the camshaft between successive cam lobes including the cam lobes then located at said inductor means; means for energizing said inductor means when said shield means is in said operative position to inductively heat the unhardened cam lobe to a predetermined heat treating temperature; first cooling means operative subsequent to said energizing for delivering liquid media on the cam lobe at said heat treating temperature and cool such cam lobe at a controlled rate to provide a predetermined surface hardness; second cooling means for delivering liquid media on the hardened cam lobe adjacent said shield means after said shield means is in said operative position concurrent with said inductor means and said first cooling means, said second cooling means providing sufficient cooling of said hardened cam lobe to prevent tempering thereof.

Claim 3

An apparatus for heat treating the cam lobes of a camshaft, said cam lobes being axially separated by cylindrical body sections, comprising: support means for rotatably supporting the camshaft for rotation about a longitudinal axis; means for selectively rotating said camshaft about said axis; a circular inductor coil adapted to encircle the cam lobes in coaxial and inductive heating relationship therewith; drive means for sequentially locating said inductor coil at each of said cam lobes; shield means movable between a transfer position spaced from the camshaft and an operative position closely encircling the body sections between a first cam lobe located at said inductor coil and a second cam lobe previously heated at said inductor coil; power supply means for energizing said inductor coil when said shield means is in said operative position; and, a first cooling device for delivering liquid media on said second cam lobe when said shield means is in said operative position and said inductor coil is energized, said liquid media providing sufficient cooling of said cam lobe to prevent tempering thereof.

Claim 4

An apparatus for heat treating the cam lobes of a camshaft, said cam lobes being axially separated by cylindrical body sections, comprising: support means for rotatably supporting the camshaft for rotation about a longitudinal axis; means for selectively rotating said camshaft about said axis; a circular inductor coil adapted to encircle the cam lobes in coaxial and inductive heating relationship therewith; drive means for sequentially locating said inductor coil at each of said cam lobes; shield means movable between a transfer position spaced from the camshaft and an operative position closely encircling the body sections between a first cam lobe located at said inductor coil and a second cam lobe previously heated at said inductor coil; power supply means for energizing said inductor coil when said shield means is in said operative position; and, a first cooling device for delivering liquid media on said second cam lobe when said shield means is in said operative position and said inductor coil is energized, said liquid media providing sufficient cooling of said cam lobe to prevent tempering thereof.

Claim 13

A method of inductively heat treating a camshaft having an elongated cylindrical body including a plurality of closely axially spaced unhardened surfaces mutually separated by cylindrical body portions comprising the steps of: (a) providing inductor means for inductively heating discrete unhardened surfaces to a predetermined elevated heat treating temperature; (b) indexing said inductor means with respect to said camshaft with sequential heat treating positions adjacent a discrete unhardened surface and in inductively coupled relationship thereto; (c) energizing said inductor means during a heating cycle at said heating position to inductively heat said discrete unhardened surface to a predetermined temperature; (d) providing a first quenching device with respect to said inductor means at the previously inductively heated surface adjacent said heating position for delivering coolant onto said previously inductively heated surface; (e) prior to said energizing of step (c), physically and fluidly isolating the surface at said heating position from the adjacent previously heated surface by interposing a shield therebetween in close conformity with the body portion of the camshaft therebetween; (f) during said energizing of step (c), delivering coolant to said first quenching device under conditions effective for maintaining the temperature of said previously inductively heated surface below the tempering temperature thereof; and, (g) spacing said shield from said body portion and reindexing said first quenching device and said inductor means with respect to said camshaft to present an unhardened surface adjacent said inductor means and a previously inductively heated surface adjacent said first quenching device.

Claim 14

A method of inductively heat treating a camshaft having an elongated cylindrical body including a plurality of closely axially spaced unhardened surfaces mutually separated by cylindrical body portions comprising the steps of: (a) providing inductor means for inductively heating discrete unhardened surfaces to a predetermined elevated heat treating temperature; (b) indexing said inductor means with respect to said camshaft with sequential heat treating positions adjacent a discrete unhardened surface and in inductively coupled relationship thereto; (c) energizing said inductor means during a heating cycle at said heating position to inductively heat said discrete unhardened surface to a predetermined temperature; (d) providing a first quenching device with respect to said inductor means at the previously inductively heated surface adjacent said heating position for delivering coolant onto said previously inductively heated surface; (e) prior to said energizing of step (c), physically and fluidly isolating the surface at said heating position from the adjacent previously heated surface by interposing a shield therebetween in close conformity with the body portion of the camshaft therebetween; (f) during said energizing of step (c), delivering coolant to said first quenching device under conditions effective for maintaining the temperature of said previously inductively heated surface below the tempering temperature thereof; and, (g) spacing said shield from said body portion and reindexing said first quenching device and said inductor means with respect to said camshaft to present an unhardened surface adjacent said inductor means and a previously inductively heated surface adjacent said first quenching device.

Claim 16

The method as recited in claim uding the step (h) of providing a second quenching device at said heating position for delivering coolant onto the inductively heated surface thereat.

Claim 24

An apparatus for hardening a plurality of axially spaced cams on an elongated camshaft, said apparatus comprising: means for selectively rotating said camshaft about a generally vertical axis; an induction heating coil having an inner wall surrounding said axis, a gap in said inner wall and quench liquid openings in said inner wall and directed toward said axis; a supplemental cooling assembly below said induction heating coil and having cooling liquid openings directed toward said axis; means for indexing said camshaft axially to a position with one cam within said induction heating coil and an adjacent one of said cam within said cooling assembly; means for energizing said induction heating coil with a relatively high power for a heating cycle of 0.5 to 3.0 seconds; means for forcing quenching liquid through said quench liquid openings in said inner wall after said heating cycle; means for forcing liquid through said cooling liquid openings during said heating cycle; means for preventing said cooling fluid from impinging upon said one cam as it is being inductively heated by said induction heating coil during said heating cycle; and, means for indexing said camshaft axially downwardly with respect to said coil and cooling assembly until said one cam is within said cooling assembly and a third unhardened cam is in said induction heating coil.

Claim 25

An apparatus for hardening a plurality of axially spaced cams on an elongated camshaft, said apparatus comprising: means for selectively rotating said camshaft about a generally vertical axis; an induction heating coil having an inner wall surrounding said axis, a gap in said inner wall and quench liquid openings in said inner wall and directed toward said axis; a supplemental cooling assembly below said induction heating coil and having cooling liquid openings directed toward said axis; means for indexing said camshaft axially to a position with one cam within said induction heating coil and an adjacent one of said cam within said cooling assembly; means for energizing said induction heating coil with a relatively high power for a heating cycle of 0.5 to 3.0 seconds; means for forcing quenching liquid through said quench liquid openings in said inner wall after said heating cycle; means for forcing liquid through said cooling liquid openings during said heating cycle; means for preventing said cooling fluid from impinging upon said one cam as it is being inductively heated by said induction heating coil during said heating cycle; and, means for indexing said camshaft axially downwardly with respect to said coil and cooling assembly until said one cam is within said cooling assembly and a third unhardened cam is in said induction heating coil.

Claim 29

A method of hardening a plurality of axially spaced cams on an elongated camshaft with a central axis, said method comprising the steps of: (a) providing an upper induction heating coil and a vertically aligned, lower cooling assembly with a vertical passageway through said coil and said cooling assembly; (b) mounting said camshaft vertically with said axis extending through said vertical passageway; (c) indexing said camshaft axially with respect to said coil and cooling assembly until one cam is within said coil; (d) indexing said camshaft circumferentially into a desired indexed position; (e) energizing said coil with a high power and for a heating cycle of 0.5 to 2.0 seconds; (f) forcing a quenching liquid through said coil onto said heated one cam; (g) then indexing said camshaft vertically downwardly with respect to said passageway unit said one cam is within said cooling assembly and another cam above said one cam is in said induction heating coil; (h) repeating said heating cycle while cooling said one cam with liquid from said cooling assembly and (i) preventing cooling liquid from interfering with said heating of said another cam in said induction heating coil.

Claim 30

A method of hardening a plurality of axially spaced cams on an elongated camshaft with a central axis, said method comprising the steps of: (a) providing an upper induction heating coil and a vertically aligned, lower cooling assembly with a vertical passageway through said coil and said cooling assembly; (b) mounting said camshaft vertically with said axis extending through said vertical passageway; (c) indexing said camshaft axially with respect to said coil and cooling assembly until one cam is within said coil; (d) indexing said camshaft circumferentially into a desired indexed position; (e) energizing said coil with a high power and for a heating cycle of 0.5 to 2.0 seconds; (f) forcing a quenching liquid through said coil onto said heated one cam; (g) then indexing said camshaft vertically downwardly with respect to said passageway unit said one cam is within said cooling assembly and another cam above said one cam is in said induction heating coil; (h) repeating said heating cycle while cooling said one cam with liquid from said cooling assembly and (i) preventing cooling liquid from interfering with said heating of said another cam in said induction heating coil.

Claim 31

A method as refined in 25 wherein said preventing step includes the step of: (j) moving shields between said coil and said cooling assembly during said heating cycle.

Claim 32

A method as refined in 25 wherein said preventing step includes the step of: (j) moving shields between said coil and said cooling assembly during said heating cycle.