Abstract: 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.

Abstract: A method and apparatus for quenching heated elongated workpieces by rotatably mounting the heated workpiece in a quench tank and subsequently rapidly flooding the tank with a quenching liquid. The heated workpiece is mounted within the quench tank by engaging opposite axial ends of the elongated workpiece. Transverse deflection of the workpiece is prevented by paired restraints located adjacent the top and bottom of the workpiece near the opposite ends. As the quenching liquid is flooded into the quench tank from a storage tank, the heated elongated workpiece is rotated about its central axis at a fixed speed.

Abstract: 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.

Abstract: A method and apparatus of quench hardening to a desired depth the inner surface of an axially extending bore in an elongated, thin-walled workpiece having an outer, axially extending surface wherein the bore has a selected, uniform cross-sectional shape, which method and apparatus involves providing an inductor with an outer shape generally matching, but smaller than, the cross-sectional shape of the bore, supporting the workpiece with the axis extending vertically, energizing the inductor with a known frequency and at a selected power level, moving the energized inductor downwardly through the bore to inductively heat the inner surface progressively while applying no fluid quench to the inner surface, letting the workpiece cool and then moving the inductor upwardly through the bore to progressively heat the inner surface while progressively liquid quenching the inner surface immediately below and after the progressive heating operation.

Abstract: A method and inductor are provided for annealing the corners of an elongate hollow structural beam in which the corners become work hardened when the beam is produced by cold working initially flat metal plate to the hollow beam configuration. The corners of the beam are inductively heated progressively along the length of the beam in a manner which concentrates heat in the corners and controls the spreading of heat into the sides of the beam from the corners so that the work hardened areas are annealed to provide for the corners and walls to be more uniform in hardness and strength in connection with use of the beam as a structural member.

Abstract: There is provided an improvement in a power inverter for converting D.C. voltage into an alternating voltage by alternating gating D.C. current across a load. This type of inverter employs a gating circuit for providing gating signals in two sets of switches at a frequency which controls the power factor of the voltage and current applied to the load, means for detecting the power factor, means for comparing the detected power factor with a reference signal indicative of a desired operating power factor and means for adjusting the frequency in accordance with the comparison whereby the power factor tends to be at the desired power factor level. The improvement in this type of inverter is the provision of means for changing the reference signal during the operation of the inverter in accordance with a control signal so that the desired power factor can be changed during start up of the inverter.

Abstract: A plurality of SCR diamond bridge circuits are coupled in series to generate frequencies higher than the individual operating frequencies of the SCR's. The series chain of diamond circuits is preferably coupled in parallel with the series combination of a DC blocking capacitor and an inductive load. The chain is provided with current from a substantially ripple-free constant current source, and the firing times of individual SCR's can be controlled to minimize the di/dt in each SCR.

Abstract: A method and apparatus for quenching heated elongated workpieces by rotatably mounting the heated workpiece in a quench tank and subsequently rapidly flooding the tank with a quenching liquid. The heated workpiece is mounted within the quench tank by engaging opposite axial ends of the elongated workpiece. Transverse deflection of the workpiece is prevented by paired restraints located adjacent the top and bottom of the workpiece near the opposite ends. As the quenching liquid is flooded into the quench tank from a storage tank, the heated elongated workpiece is rotated about its central axis at a fixed speed.

Abstract: An induction heating system for heating an end length of a forging bar following the cut-off therefrom of a previously heated and forged end length is arranged to bring the end length to be heated to a uniform temperature despite the existence of a residual hot end portion from the previous heat. The heating system has an induction heating coil with a longitudinally extending axial passageway therethrough for receiving the bar length to be heated by insertion into a feed-in end of the coil passageway. A stop member is positioned adjacent the open other end of the passageway to abut the forward end of the inserted bar so as to locate it wholly within the passageway.

Abstract: 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.

Abstract: A floating inductor assembly for use in heating a generally conical valve seat formed concentrically around a central bore in an engine component, wherein the assembly is adapted to be moved toward and away from the valve seat by a selectively movable element. This floating inductor assembly comprises a carrier, an inductor having a shape generally matching the valve seat and mounted on the carrier, an aligning nose member extending from the carrier in a given direction and generally concentric with the inductor, and first and second flange portions supported on the carrier and extending radially outwardly in a direction perpendicular to the given direction of the nose member, whereby each flange portion is adapted to engage a coupling member for supporting the assembly onto the movable element in a manner to allow floating in the radial direction only.

Abstract: An induction heating inductor is provided for use in a slot type of furnace to heat axially spaced portions of an elongated workpiece. This inductor includes first and second generally rigid, elongated input members normally fixed with respect to each other and extending generally parallel to the workpiece and a conductor unit extending between the input members to define one of the heating portions and adjustable for changing the position of this heating portion on the workpiece.

Abstract: An inductor for heating the circumferentially opposed working surfaces and the root surface between adjacent gear teeth includes a nose portion received between the adjacent teeth and having a profile corresponding to that of the working and root surfaces. The nose portion is comprised of a flux concentrator having axially opposite ends and radially inner and outer ends, a generally V-shaped conductor plate having ends attached to the radial inner end of the concentrator and defining a coolant passageway therewith, and tubular conductors at the axially opposite ends of the flux concentrator and plate to provide for the circulation of coolant through the nose portion. A portion of the tubular conductor extends axially adjacent the radially outer side of the flux concentrator.

Abstract: An inductor coil is provided for inductively heating a hollow automotive front wheel spindle which has axially extending outer surface areas of different radial thickness. The coil has a single loop between the terminal ends thereof defined by circumferentially extending arcuate inductor portions which are axially spaced apart and connected with one another by means of axially extending inductor portions. The arcuate inductor portions are circumferentially progressive with respect to one another in the direction from one of the terminal ends of the inductor toward the other, and each arcuate portion is associated with a different one of the axially extending surface portions of the workpiece. Each arcuate portion has a circumferential extent different from the other two.

Abstract: An induction heating unit is disclosed which is operable to inductively heat and harden teeth on circumferentially extending radially thin flange segments of a gear. The unit includes an inductor conforming in circumferential contour and length to the flange segment and having radially and axially offset conductor leg portions to control heating of the gear teeth during relative axial scanning movement between the gear and inductor so as to prevent distortion of the gear flange. The unit further includes an arrangement for quenching the gear teeth and cooling the end portions of the flange segment during scanning movements.

Abstract: Feeding means for successively advancing elongated workpieces step-by-step, through the central workpiece receiving passage in a multiturn induction heating coil with a workpiece supporting slide track extending therethrough, has an elongated workpiece pusher member extending longitudinally through the passage and provided with workpiece engaging driving lugs spaced therealong. Combined transport and elevating means reciprocate the pusher member axially of the passage between a retracted and an extended position to advance the workpiece into and subsequently out of the heating coil passage and shift the pusher member between two different elevational positions in which its driving lugs are respectively located in the path of travel of the workpiece along the slide track during the advance stroke of the pusher member and out of the path of travel during the return stroke of the pusher member.

Abstract: A device for directing quench fluid onto the top of an inductively heated surface portion of a rotating workpiece has a supply means having an outlet end spaced horizontally from said surface portion for directing a jet of quench fluid therefrom and a deflector for intercepting and guiding the quench fluid jet onto the top of the heated surface portion of the workpiece. The spacing of the outlet end horizontally from the heated workpiece surface portion prevents the falling thereonto and contacting therewith of any drippage of residual quench fluid from the outlet end following shut-off of the supply of quench fluid thereto and during subsequent inductive reheating of the quench hardened surface portion to temper it.

Abstract: Apparatus is provided for simultaneously rotating and axially feeding an elongated workpiece past an induction heating inductor. The apparatus includes a collet having a passageway therethrough defined in part by radially displaceable fingers normally providing an opening of a diameter smaller than the smallest diameter of the workpiece. A workpiece is pushed through the collet and the collet is simultaneously rotated for the fingers to rotate the workpiece as the latter slides axially along the fingers.

Abstract: A device for inductively heating a cylindrical metal surface on an elongated workpiece having a central rotational axis, wherein the cylindrical surface is generally concentric with the axis. The device comprises an inductor having a generally cylindrical coupling surface matching the metal surface, a main support for carrying the inductor, the main support movable between a first position with the inductor spaced substantially from the cylindrical metal surface and a second position with the inductor in its heating position, and an intermediate frame for mounting the inductor onto the support.

Abstract: An apparatus for heating an elongated workpiece having an elongated axis and moving along a heating path in a selected linear direction, the path having opposite sides defining a workpiece passage therebetween. This apparatus comprises a plurality of high permeability flux directing elements, each of the elements having a generally flat surface spaced from and generally parallel to the heating path, means for mounting the elements along at least one side of the path at selected, mutually spaced locations, separate coil means encircling each of said elements and alternating current power means for causing separate, spaced magnetic flux fields extending from said surfaces and into said passage in a direction generally perpendicular to said path.