Tocco, Inc.

Park-ohio Industries

George M Mucha

George D Pfaffmann

Donald E Novorsky

Norbert R Balzer

Paul L Day

Jonathan W Alexander

Richard H McKelvey

John R Laughlin

William Z Nelson

Robert C Johnson

A method of monitoring a heating cycle of an induction heating system wherein an inductor encircles a metal workpiece and an alternating current is applied through the inductor from a power supply during the heating cycle. This method comprising the steps of generating an analog signal representative of the voltage across the inductor, as the voltage varies during the heating cycle by changes in the electromagnetic characteristics of the workpiece as the workpiece is being heated; digitizing the voltage representative analog signal; creating a trace of the digitized voltage representative analog signal, with the trace being indicative of the electromagnetic characteristic of the workpiece as sensed by the inductor voltage during the heating cycle; and, comparing the created trace with a preselected pattern. This method can be performed with the workpiece moving through the inductor during said heating cycle and when the heating cycle includes a number of sub-cycles when the power supply is energizing the inductor separated by periods when the power supply is not energizing the inductor.

Method of monitoring induction heating cycle

A method and apparatus for induction heating and quench hardening of an undulating cylindrical surface, such as that defined by gear or sprocket teeth, provide a hardness pattern uniformly distributed to a controlled depth across and between the teeth surfaces by means of axial scanning of the workpiece relative to a single induction heating coil. A distinct final heating scanning process follows a preheating scanning process whereby preheating and final heating can be conducted at differing controlled axial velocities. Axial scanning of the workpiece repeatedly past a single inductor coil enables preheating and final heating of workpieces which cannot be axially shifted directly between separate inductor coils, such as internal planetary ring gears having a closed end or external gears having a flange or shoulder protruding radially from the cylindrical gear teeth surface.

Method and apparatus for induction heating of gear teeth

Method and apparatus for hardening the outwardly facing teeth surfaces of a gear is disclosed. First and second induction heating coils with power sources controlled by an appropriate microprocessor preheat the gear when in the first coil at precisely controlled cycles to generate an unstable circular band of high temperature positioned radially inwardly from the tips of the gear. Before the band can dissipate, the microprocessor actuates an appropriate drive to locate the gear in the second coil energized by an appropriate power source to impart a high skin temperature to the teeth. A liquid spray quench in the second coil is immediately actuated to effectively quench the gear. By sizing the cycles, the gear teeth are rapidly hardened at minimal power levels.

Method and apparatus for hardening gears

A method and apparatus for progressively hardening an elongated workpiece having an outer generally cylindrical surface concentric with the central axis including the concept of providing closely spaced first and second induction heating coils each having workpiece receiving openings generally concentric with the axis of the workpiece; energizing the first coil with a low frequency such as a frequency less than about 50 KHz; energizing the second coil with a high radio frequency, such as the frequency exceeding 100 KHz; causing relatively axial and progressive motion between the workpiece and the first and second closely spaced coils in a direction entering the first coil and exiting the second coil whereby the cylindrical surface is progressively first preheated by the first coil and then immediately final heated by the second coil; and, then immediately quenching the cylindrical surface as it passes from the second coil whereby the cylindrical surface is progressively preheated, heated and quench hardened as the workpiece is moved through the induction heating coil.

Method and apparatus for hardening gears and similar workpieces

A method of monitoring a heating cycle of an induction heating system wherein an inductor encircles a metal workpiece and an alternating current is applied through the inductor from a power supply during the heating cycle. This method comprising the steps of generating an analog signal representative of the voltage across said inductor, as the voltage varies during said heating cycle by changes in the electromagnetic characteristics of the workpiece as the workpiece is being heated; digitizing the voltage representative analog signal; creating a trace of the digitized voltage representative analog signal, with the trace being indicative of the electromagnetic characteristic of the workpiece as sensed by the inductor voltage during the heating cycle; and, comparing the created trace with a preselected pattern. This method can be performed with the workpiece moving through the inductor during said heating cycle and when the heating cycle includes a number of sub-cycles when the power supply is energizing the inductor separated by periods when the power supply is not energizing the inductor.

An apparatus for hardening the outwardly facing teeth surfaces of a gear is disclosed. First and second induction heating coils with power sources controlled by an appropriate microprocessor heat the gear when in the first coil at a precisely controlled cycle to generate an unstable, circular band of high temperature positioned radially inwardly from the tips of the gear. Before the band can dissipate, the microprocessor actuates an appropriate drive to locate the gear in the second coil energized by an appropriate power source to impart a high skin temperature to the teeth. A liquid spray quench in the second coil is immediately actuated to effectively quench the gear. By sizing the cycles, the apparatus is thus able to rapidly harden the gear teeth at minimal power levels.

System for hardening gears by induction heating

A method and apparatus for progressively hardening an elongated workpiece having an outer generally cylindrical surface concentric with the central axis including the concept of providing closely spaced first and second induction heating coils each having workpiece receiving openings generally concentric with the axis of the workpiece; energizing the first coil with a low frequency such as a frequency less than about 50 KHz; energizing the second coil with a high radio frequency, such as the frequency exceeding 100 KHz; causing relatively axial and progessive motion between the workpiece and the first and second closely spaced coils in a direction entering the first coil and exiting the second coil whereby the cylindrical surface is progressively first preheated by the first coil and then immediately final heated by the second coil; and, then immediately quenching the cylindrical surface as it passes from the second coil whereby the cylindrical surface is progressively preheated, heated and quench hardened as the workpiece is moved through the induction heating coil.

Method and apparatus for induction heating gears and similar workpieces

A method of hardening the radially, outwardly facing surfaces of a generally circular, toothed workpiece adapted to rotate about a central axis generally concentric with the outwardly facing surfaces whereby the extremities of the surfaces define an outer circle by the tips of the teeth of the workpiece. This type of workpiece is generally a gear. The method comprises the steps of providing first and second induction heating coils, locating the workpiece concentric in the first induction heating coil, energizing the first induction heating coil with a first alternating frequency current for a first time period, deenergizing the first coil with the workpiece therein for a first time delay period, again energizing this first induction heating coil with a second alternating frequency current for a second time period substantially less than the first time period, immediately transferring the workpiece concentrically into the second induction heating coil in a second delay time, then energizing the second induction heating coil with a radio frequency current for a third time period and immediately quenching the outer surfaces by quenching liquid sprayed against the surfaces while the workpiece is in the second induction heating coil. This process can be employed for hardening various convoluted surfaces where the area to be hardened, compared to the mass adjacent thereto, is substantially less than the area compared to adjacent mass at the protruding convolution, i.e. generally gear teeth.

Method and apparatus of hardening gears by induction heating

Method and apparatus for inductively heating and quench hardening axially spaced cams on a steel camshaft having a longitudinally extending rotational axis concentric with a plurality of axially spaced bearings, which method and apparatus utilizes an induction heating coil having an inner surface surrounding the rotational axis of the camshaft with an insulating gap and integral quench openings for directing quenching liquid inwardly from the heating coil for the workpiece, and a high frequency power supply for selectively energizing the heating coil with a power density within the heating coil of about 20KW/in.sup.2 and an auxiliary cooling assembly fixed with respect to the heating coil and including an arrangement for spraying a cooling liquid toward the camshaft. In accordance with the method and apparatus, a camshaft is indexed axially through the opening of the coil and cooling assembly to a first position with a cam within the coil, at which position the camshaft is indexed to have the lobe of the cam facing the gap in the induction heating coil and a hardening cycle is then employed including induction heating of the surface of the camshaft while the cam is stationary and then quench hardening by directing a quenching fluid through the induction heating coil toward the previously heated cam surface. After this heating cycle, the camshaft is then moved until the next cam is within the heating coil and the previously hardened cam is in the cooling assembly. Thereafter, another hardening cycle occurs. This process is repeated until all cams have been hardened.

Method and apparatus for hardening axially spaced cams on a camshaft

A method of hardening the radially, outwardly facing surfaces of a generally circular, toothed workpiece adapted to rotate about a central axis generally concentric with the outwardly facing surfaces whereby the extremities of the surfaces define an outer circle by the tips of the teeth of the workpiece. This type of workpiece is generally a gear. The method comprises the steps of providing first and second induction heating coil, locating the workpiece concentric in the first induction heating coil, energizing the first induction heating coil with a first alternating frequency current for a first time period, deenergizing the first coil with the workpiece therein for a first time delay period, again energizing this first induction heating coil with a second alternating frequency current for a second time period substantially less than the first time period, immediately transferring the workpiece concentrically into the second induction heating coil in a second delay time, then energizing the second induction heating coil with a radio frequency current for a third time period and immediately quenching the outer surfaces by quenching liquid sprayed against the surfaces while the workpiece is in the second induction heating coil. This process can be employed for hardening various convoluted surfaces where the area to be hardened, compared to the mass adjacent thereto, is substantially less than the area compared to adjacent mass at the protruding convolution, i.e. generally gear teeth.

Method for hardening gears by induction heating

A method and apparatus of quench hardening to a desired depth the full axial extent of the wall surface, or selected portions of the wall surface, of an axially extending bore in an elongated workpiece wherein the bore has a selected uniform cross-sectional shape throughout the length thereof and is closed at one end, which method and apparatus involves providing an inductor with an outer shape generally matching but smaller than the cross-sectional shape of the bore to permit passage of the inductor through the bore, supporting the workpiece with the axis of the bore extending vertically and the open end facing downward, electrically energizing the inductor with a known frequency and at a selected power level, passing the energized inductor upwardly through the bore to inductively heat the wall surface of the bore progressively upwardly from the lower end thereof while progressively liquid quenching the wall surface immediately below the inductor during the upward passage thereof through the bore, and directing additional liquid quenching medium from the top of the inductor for impingement against the innermost end regions of the wall surface of the bore, at the limit of the upward passage of the inductor into the bore, to quench the innermost end regions of the bore wall surface above the reach of the progressive liquid quenching of such wall surface below the inductor when located in its limiting upward position in the bore.

Apparatus for inductively heat treating workpiece bore walls

A method and apparatus for heat treating camshafts includes a retractable shield positioned between a previously hardened surface and a surface being heat treated. During the induction heating and quenching cycle, a coolant is delivered to the hardened surface to maintain the temperature thereof below the tempering temperature. The shield prevents the coolant from contacting the unhardened surface and interfering with the heating and quenching thereof.

Method and apparatus for heat treating camshafts

Method for inductively heat treating workpiece bore walls

A device for heating an elongated workpiece having a central axis which device comprises first and second axially spaced and axially aligned multiturn induction heating coils, each of which has a workpiece receiving passage extending therethrough. Means are provided for indexing a workpiece axially first into the passage of the first coil and then, after a time delay, axially into the passage of the second coil. There is also provided a quenching device used with the heating device for the previously heated workpieces which involves moving the workpiece to a first location above the liquid level of a quenching liquid in a tank with the axis of the workpiece extending in a given direction, shifting the heated workpiece transversely to a second position still above the liquid level, shifting the workpiece vertically downwardly into the quenching liquid of the tank at the second location, rotating the workpiece under the liquid level at a second location, shifting the workpiece transversely to a third location while still under the liquid level, lifting the workpiece vertically upwardly from the quenching liquid to a position above the liquid level, shifting the workpiece transversely to a fourth position still above the liquid level and then moving the workpiece from the tank.

Method and apparatus of inductively heating elongated workpieces

In a device for resistance heating of an elongated, generally cylindrical metal workpiece preparatory to quench hardening wherein the workpiece has a central, elongated axis and axially spaced first and second ends. The heating device includes first and second axially spaced electrode means for directing electrical current through the workpiece and between the spaced ends as the workpiece is supported in a selected, generally horizontal heating position. The improved feeding arrangement includes a transfer element with first and second separate nest means for supporting a workpiece with its axis generally parallel to the heating position. The second nest means is spaced horizontally from the loading position. This transfer element is reciprocally mounted for movement between a first location with a workpiece in the first nest means at the heating position and a second location with the first nest means being spaced from the heating position. Means are provided for shifting the workpiece from the loading position on the second nest means as the transfer element moves toward its first location and means for transferring a workpiece from the second nest means to the first nest means upon movement of the transfer element from the first location toward the second location to provide easy movement of the workpiece from the loading position, to the second nest means, to the first nest means and, then, to the resistance heating position.

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Parma Heights, OH, United States of America

George M Mucha