Park-ohio Industries

John C Lewis

A method and apparatus for hardening a small internal passage in a workpiece wherein the workpiece is indexed into coaxial alignment between axially spaced inductor coils and an actuator telescopically inserts a magnetically permeable flux concentrating rod through the passage, and coextensive with the coils and in inductive relationship with the interior surface, such that upon energization of the coils, flux is concentrated in the concentrating rod and effectively inductively delivered to the surface to raise the temperature thereof to a heat treating temperature, the actuator being extended to another position wherein a quenching ring is disposed adjacent to the surface for delivering coolant thereto to quench harden the surface, the actuator being finally retracted to allow sequential indexing of workpieces.

Apparatus and method for inductively hardening small bores

Method and apparatus for uniformly heating a workpiece such as a sucker rod or the like having a uniform cross-section over a major portion of its length and an enlargement adjacent each end thereof. A multi-turn inductor is coaxially disposed around a portion of an elongated workpath with the rod being longitudinally moved at some preselected rate of travel along the workpath toward the inductor entrance end. The inductor is normally at a first level of energization adapted to inductively heat the rod major portion to some predetermined temperature as it passes through the inductor. Sensing a preselected power absorption level by the rod as the enlargement adjacent the leading end is inductively coupled with the inductor causes the inductor to be automatically placed at a second, higher level of energization for heating the enlargement to the predetermined temperature. The inductor then automatically returns to the normal level of energization after some predetermined time interval for inductively heating the rod major portion. As the enlargement adjacent the rod trailing end is placed in an inductively coupled relationship with the inductor, the predetermined power absorption level increase is again sensed and the inductor is automatically switched to the higher level of energization. The inductor energization levels and the power absorption level sensing capabilities are adjustable to accommodate different rod and feed characteristics.

Method and apparatus for uniform induction heating of an elongated

A device for inductively heating simultaneously and alike a plurality of identical elongated workpieces each having at least two axially spaced portions, to produce identical predetermined heat profiles in the workpiece throughout their longitudinal extents. The workpieces are conveyed at a predetermined uniform speed along work paths extending in a linear direction. A plurality of like multi-turn induction heating coils are coaxially disposed along the work paths and connected to a two-level power source. A reciprocal stop aligns the leading ends of the workpieces along the feed paths relative to the heating coils. The coils are at a first level of energization adapted to inductively heat the first axial portion of the respective workpieces identically to the same predetermined temperature as they pass through the coils. After a predetermined time interval during the heating cycle, triggered by the action of the stop, the coils are automatically placed at the other level of energization to inductively heat the second axial portion of the respective workpieces identically.

Apparatus for simultaneously heating a plurality of elongated workpieces

Elongated workpieces having an extended intermediate portion of substantially uniform cross-section and axially spaced end or other portions of enlarged cross-section are inductively heated to a desired surface temperature by axially moving them at a continuous rate of speed coaxially of and sequentially through a succession of three axially aligned multiturn induction heating coils and energizing selective ones of the heating coils, during the passage therethrough of selected ones of the workpiece portions to inductively heat the same to the desired surface temperature. The coils have separate power supply circuits for energizing the coils, and suitable control means are provided for activating the power supply circuits to energize the coils in succession and during the travel of the selected portions of the workpiece through selected ones of the heating coils.

Induction heating method and apparatus for elongated workpieces

A method for uniformly heating an elongated workpiece having a first portion with uniform cross-section over a major portion of the workpiece length and a second portion having a larger cross-section than the first portion. A multi-turn inductor is operatively mounted on a carriage or the like and is coaxially disposed about an elongated workpath. The carriage is selectively movable axially of the workpath from a first or home position. As the workpiece first portion is fed along the workpath at some preselected rate of travel into and through the inductor, it is heated to a desired temperature over the length thereof. The inductor carriage is energized as the enlarged workpiece second portion enters the inductor so that the inductor will travel along the workpath with the workpiece. Such travel increases the heating time for the second portion so that it too is heated to the desired temperature. After a predetermined time interval, the carriage movement is reversed back toward the first or home position. The method is adapted to use with workpieces having plural enlarged areas spaced therealong and is adaptable to simultaneous heating of a plurality of workpieces with plural inductors.

Method and apparatus of uniform induction heating of an elongated

A device for controlling the heat generated by induction coils in a multiple induction heating coil furnace. Multiple induction coils provide parallel cylindrical passages having axial lengths and fixed diameters through which elongated workpieces are movable in the axial direction. The axial length of one induction coil is fixed while the other coils have variable lengths as a result of an arrangement for altering the distance between first and second ends of the induction coils. Sensors detect the temperatures of workpieces within each induction coil and a comparison of the detected temperature reveals the difference between the variable and fixed axial length induction coils. The axial length of the coils are shortened in the event that the detected temperature is greater than that of the workpiece in the fixed axial length coil, and conversely, lengthened in the event that the detected temperature is less than that of a workpiece in the fixed axial length coil. Altering of the axial length of the induction coil may be accomplished either manually or by a motor-drive arrangement automatically responsive to the comparison of the temperature sensors and comprises moving a first end of the variable axial length induction coil relative to a fixed second end.

Control device for parallel induction heating coils

An auxiliary electrical test circuit is provided which is adapted to assist in matching the resonant frequency of an induction heating load with the rated frequency range of a solid state high frequency power source coupled to the load circuit. The load circuit includes an inductor, power factor correction capacitors, and a given workpiece to be inductively heated. The test circuit includes an audio frequency oscillator of low output power having an output frequency which may be adjusted in a range extending below and above the rated frequency range of the solid state power source. The oscillator output is coupled to the load circuit independent of the solid state power source, and the output frequency of the oscillator is adjusted to coincide with the resonant frequency of the load circuit, which coincidence is determined by observing the peak voltage obtained during adjustment of the oscillator output frequency. The oscillator frequency is then compared to the rated frequency range for the solid state power supply. If the resonant frequency of the load circuit is outside the rated frequency range for the solid state power supply, power factor correction capacitors are added or subtracted until the load circuit frequency is determined to be within the rated frequency range of the power supply.

Growing community of inventors

Dundas, Canada

John C Lewis