HK1216549B - Inductor for single-shot induction heating of complex workpieces - Google Patents

Description

Inductor for single shot induction heating of complex workpieces

Cross Reference to Related Applications

This application claims the benefit of U.S. provisional application No. 61/838,249, filed on.6/22/2013.

Technical Field

The present application relates to electric induction single shot heat treatment of complex workpieces having an at least partially cylindrical component with a central axis coincident with a central axis of a circular component and connected at one end to the circular component having a diameter larger than the diameter of the at least partially cylindrical component.

Background

Right cylindrical workpieces, such as solid or hollow shafts, may be metallurgically heat treated (hardened) to withstand the forces applied to the workpiece in the desired application. For example, the workpiece may be a variety of cylindrical automotive components that are metallurgically hardened for use in automotive vehicle power systems.

More complex workpieces are formed by combining multiple cylindrical components having different diameters, fillets, shoulders, holes, and other geometric irregularities. Examples of such complex geometries are shown in fig. 5.28 (left panel) and fig. 5.36 of Handbook of indication Heating (valry Rudnev et al, 2003, Marcel Dekker, inc., New York, NY). FIG. 1(a) illustrates another embodiment of a complex workpiece. In general, these complex workpieces may be characterized as having an at least partially cylindrical component with a central axis coincident with a central axis of the circular component and connected at one end to the circular component having a diameter larger than the diameter of the at least partially cylindrical component, and such workpieces are referred to herein as "complex workpieces" for convenience. For example, for the complex workpiece 90 shown in fig. 1(a), the workpiece assembly within the dashed box 90a is an at least partially cylindrical assembly, and the workpiece assembly within the dashed box 90b is a circular assembly having a diameter larger than the diameter of the at least partially cylindrical assembly, and the two workpiece regions are oriented such that the at least partially cylindrical assembly 90a has a central axis C_LCoincides with the central axis of the circular component 90b and is connected at one end to a circular component having an outer diameter d₂Is larger than the outer diameter d of the at least partially cylindrical component 90a₁The large circular component 90 b.

Electric induction heating is used in a variety of heat treatment procedures, such as annealing, normalizing, case hardening, through hardening, tempering, and stress relief. One of the most popular applications of induction heating is the hardening of steel, cast iron, and powder metallurgy components. In some cases, it is desirable to heat treat the entire workpiece, however, in other cases, it is desirable to heat treat only selected regions of the workpiece.

A typical induction hardening procedure involves heating the workpiece or region of the workpiece that needs to be strengthened to an austenitizing (austenitizing) temperature; the workpiece or region is maintained, if necessary, at the austenizing temperature for a sufficient period of time to complete austenization, and then the workpiece or region is rapidly cooled to a temperature below that at which the desired martensitic structure begins to form. Rapid cooling or quenching allows the diffusion-dependent transformation process to be replaced by a shear-type transformation, which forms a harder component (called martensite). Martensite may be formed and hardening may be accomplished on the surface or area of the workpiece or throughout the entire cross-section of the workpiece or area. The workpiece is induction hardened for different reasons. For example, hardening may be accomplished to increase torsional strength and/or torsional fatigue life, to extend bending strength and/or bending fatigue life, or to improve wear resistance or contact strength.

Various types of heat inductors may be used to induction harden cylindrical or complex workpieces. Because inductive heating of a workpiece depends on magnetic flux coupled with a region of the workpiece to induce eddy current heating in the workpiece, it is difficult to achieve uniform induction heating processing within complex geometric regions (such as fillets between adjacent cylindrical components) with typical induction coil configurations. The induction heating process is further complicated by the fact that heat penetration into the interior of the workpiece is a combination of inward induction eddy current heating and subsequent conduction of heat from the eddy current region (controlled by the depth of the induction current penetration) to the central region of the workpiece (this conduction heating process is referred to in the art as thermal "soak").

The configuration of the inductor depends on the parameters of the particular application, which include the geometry of the workpiece, the composition of the material being heated, the available space for installation of the inductor, the heating pattern (e.g., scanning, single shot, progressive or static heating pattern), the productivity of the workpiece, the heating pattern required, and the details of the workpiece processing (i.e., how the workpiece is loaded and unloaded).

Inductors used for induction hardening are typically made of copper or copper alloys due to the high electrical and thermal conductivity of copper, its inherent corrosion resistance, and excellent cold and hot workability.

Channel-type (also known as single shot or slot) inductors are one type of inductor most suitable for penetration and case hardening of cylindrical and complex workpieces. With the channel inductor, neither the workpiece nor the induction coil move relative to each other, except that the workpiece may rotate. The channel inductor may be a single turn or multi-turn inductor. Multi-turn channel inductors are commonly used to through-heat the ends of small steel rings or bars, for example, prior to hot forming in an article forging procedure. Single turn channel inductors are commonly used for Induction hardening cylindrical or complex components, which are representatively shown in fig. 5.28 (right side view) and fig. 5.36 in the Handbook of Induction Heating (Handbook of Induction Heating). A typical application of single turn channel inductors is the hardening of hardened carbon steel shafts such as output shafts, flange shafts, yoke shafts, intermediate shafts, and drive shafts.

A single turn channel inductor consists of two longitudinal legs and two intersecting segments (also called bridges or horseshoe-type half rings). The cross-over section does not encircle the entire circumference of the workpiece to be heated, but generally only a portion of half the circumference. When a longitudinal region of the tool needs to be heated, induced eddy currents flow primarily along the length of the workpiece. The exception is that the eddy currents are half-circular over the cross section of the channel inductor. As an example, FIG. 5.33 in the Handbook of Induction Heating shows a channel inductor for Induction hardening of half shafts. The instantaneous alternating current in each of the two longitudinal struts and each of the intersecting segments is in opposite directions relative to each other.

The length of the heated region can be controlled by fabricating the channel inductor with longitudinal strut sections of different lengths. Fig. 1(b) shows one example of a prior art single turn channel inductor 100. The first (upper) crossover section 102 includes crossover half-sections 102a and 102 a', longitudinal strut sections 104a and 104b, and a second (lower) crossover section 106. The complex workpiece 90 is inserted into a single turn saddle inductor 100 as shown in fig. 1 (c). The crossed half-sections 102a and 102a '(fig. 1(b)) are electrically isolated from each other by, for example, a dielectric slot 112 so that the crossed half-sections 102a and 102 a' can be connected to the output of an alternating current power source 114. Since the cross sections and longitudinal leg sections of the inductor 100 only partially surround the circumference of the complex workpiece 90, the workpiece when loaded in the heat treatment position shown in fig. 1(C) surrounds its central axis C_LAnd (4) rotating.

The channel inductor 100 in fig. 1(b) and 1(c) is oriented in a vertical direction for loading or removing a single shot workpiece in a vertical or horizontal direction.

The longitudinal strut sections of the single turn channel inductor may be contoured by convex shaping selected regions of the longitudinal strut to accommodate specific geometric features of the heat treated workpiece, such as variations in workpiece diameter. Similarly, one or both of the intersecting sections of the single turn channel inductor may be contoured or curved for generating the desired magnetic field area coupling with the appropriate area of the workpiece to achieve the desired temperature profile. Manufacturing (all) desired sections of the channel inductor with a narrower heating surface facing the workpiece may increase the density of the induced power in (all) desired areas.

Fig. 2(a) to 2(c) illustrate three typical examples of profiled cross sections of a prior art single shot channel inductor near the fillet area.

Fig. 2(a) shows the lower half crossover section 106' of a single shot, single turn prior art channel inductor heating apparatus for heat treating a solid complex workpiece 92. Fig. 2(a) shows only the right half of a lower crossover section 106 '(similar to crossover section 106 in fig. 1(b)) of a vertically oriented channel inductor, with internal cooling channels 106 a' for inducing a flow of a cooling medium. A separate quenching apparatus 116 is provided in this embodiment for quenching when the workpiece reaches the desired thermal conditions after being heated in the channel inductor. Alternative quenching methods include: the workpiece is heated and unloaded from the channel inductor and quenched. Vertical symmetry axis C_LIndicates the core of the solid cylindrical component 92a of the complex workpiece 92. Thus, for a complex workpiece 92, the at least partially cylindrical component is a solid shaft cylindrical component 92a, and the circular component having a diameter greater than the diameter of the at least partially cylindrical component is component 92b (with the hatching opposite that of component 92 a). Thus, as shown in fig. 2(a), the central axis of the at least partially cylindrical component 92a coincides with the central axis of the circular component 92b and is connected at one end to the circular component 92b having a diameter larger than the diameter of the at least partially cylindrical component 92 a. The outside diameter 92c and the fillet area 92d of the complex workpiece 92 are included in the area for induction hardening and are shown as spot areas. The outer diameter 92c is heated due to induced eddy currents generated by current flowing in the longitudinal leg sections 104a and 104b (not shown in fig. 2 (a)) of the channel inductor. The induction heating in the fillet region 92d is primarily generated by the channel inductor current flowing in the lower crossover section 106' of the channel inductor.

Fig. 2(b) (right half view only) shows a lower crossover section 106 "of a single shot, single turn prior art channel inductor for heat treating a hollow complex workpiece 90 (also shown in fig. 1 (a)). Fig. 2(b) shows only half of the lower crossover section 106 "(similar to crossover section 106 in fig. 1(b)) of a vertically oriented channel inductor, with internal cooling channels 106 a" for inductor cooling medium flow. Fig. 2(b) does not show a separate quenching apparatus. Vertical symmetry axis C_LIndicated as the core of the hollow cylindrical components (90a and 90c) of the complex workpiece 90, with the depicted hollow interior core region hatched. Thus, for a complex workpiece 90, as also described with reference to fig. 1(a) above, the at least partially cylindrical component is a hollow cylindrical component 90a and the circular component having a diameter larger than the diameter of the at least partially cylindrical component 90a is designated in the figure as component 90b, such that the at least partially cylindrical component 90a has a central axis that coincides with the central axis of the circular component 90b and is connected at one end to the circular component 90b having a diameter larger than the diameter of the at least partially cylindrical component 90a, as shown in fig. 2 (b).

When the workpiece has a hardened region including the region of the fillet in fig. 2(a) and 2(b), it is often desirable to substantially increase the induction heating density of the fillet region, since the fillet region has a substantially larger metal mass to heat. Furthermore, there is significantly more workpiece mass near the heated fillet and behind the hardened region, which creates a substantial "cold" heat sink effect that extracts heat from the heated fillet due to thermal conductivity. Therefore, the cooling effect of the cold sink effect must be compensated by the inductive additional heating energy in the fillet region. The required energy surplus is usually taken from the current carrying surface of the appropriate area of the narrowed channel inductor to increase the power density in the appropriate area. For example, if the current carrying portion of the heating surface of the inductor section is halved, the current density of the inductor section and, respectively, the induced eddy current density in the region will increase accordingly. According to the joule effect, if the induced eddy current density is doubled, the induced power density is increased by four times.

For the configuration in fig. 2(a), and in particular in both fig. 2(b), the heating surfaces of the inductor in the intersection section facing the fillet area have been profiled to concentrate the induced eddy currents and heat generation within the fillet area.

Fig. 2(c) shows a detailed view of the lower half crossover region 106 "that can replace the prior art single shot single turn channel inductor heating apparatus, wherein in addition to crossover region inductor profiling, magnetic flux concentrators 80a and 80b are provided to further concentrate thermal energy in the fillet region 94c of the complex workpiece 94. The localized current density of the inductor can be significantly increased when a flux concentrator is utilized.

A magnetic flux concentrator (also known as a flux booster, flux controller, shunt diverter, or magnetic core) affects the electromagnetic coupling between the workpiece and the magnetic field of the channel inductor. The flux concentrator has several conventional functions in induction hardening: (a) providing selective heating of a particular region of a workpiece; (b) the electrical efficiency of the inductor is improved; (c) as well as serving as an electromagnetic shield and inhibiting unwanted heating of adjacent areas. The flux concentrator is made of a high permeability soft magnetic material with low electrical conductivity. The soft magnetic material of the flux concentrators means that they are only magnetic when an external magnetic field is applied. These materials, once exposed to an alternating electromagnetic field, rapidly change their magnetization without requiring too much friction. Small area narrow hysteresis loops are typical for these materials. The concentrator provides a low reluctance path and promotes concentration of the flux lines in the desired area. If a magnetic flux concentrator is introduced into the inductor field, it provides a low reluctance path for the magnetic flux, reduces stray flux and concentrates the virtual flux lines of the magnetic field. Without the flux concentrators, the magnetic field would be distributed around the inductor and associated with a conductive environment (e.g., no heated auxiliary equipment, metal supports, tools, fixtures, work piece area). The concentrators form magnetic paths to direct the magnetic field of the inductor in a desired region. The above-mentioned factors have a potentially positive effect on the selected area of induction heating. However, localized circuit density of the inductor in a particular region may substantially increase and potentially cause localized inductor overheating and/or accelerate the onset of stress cracking of the inductor (e.g., by work hardening of the inductor).

One of the major drawbacks of conventional single turn channel inductors is their short lifetime. The requirement to produce sufficient heat generation in selected areas of the workpiece (such as the fillet areas) leads to the necessity of having a significantly narrow inductor heating surface used in conjunction with the flux concentrator, which is associated with excessive coil current density and premature failure of the inductor heating. Premature inductor failure (cracking, stress corrosion, or stress fatigue) typically occurs in the areas of highest current density and typically in the crossover areas 106 of the single turn channel inductor that provide fillet heating. The crossover section also experiences inductor deflection due to the presence of electromagnetic forces. Therefore, in order to extend the life of the hardened inductor, attempts should be made to reduce the current density in this region.

Another disadvantage of conventional single turn channel inductors is associated with excessive process sensitivity, which has a negative impact on the quality and heating repeatability of the hardened component. Excessive sensitivity is associated with electromagnetic proximity effects. If the positioning of the workpiece inside the channel inductor changes (e.g., wear of bearings associated with equipment used to rotate the workpiece within the inductor, mis-loading of the workpiece in the inductor), there will be an immediate change in the heating intensity, particularly in the fillet area. This often results in insufficient temperature and the small hardness depth associated therewith.

It is an object of the present invention to provide an improved inductor for single shot induction heating of complex workpieces, wherein an at least partially cylindrical component has a central axis coinciding with the central axis of a circular component and is connected at one end to a circular component having a larger diameter than the diameter of the at least partially cylindrical component, with an extended inductor lifetime, an improved robustness and a reduced heating sensitivity for positioning of the workpiece within the inductor.

The above and other aspects of the invention are set out in the present description and in the appended claims.

Disclosure of Invention

One aspect of the present invention is an apparatus and method for inductively heat treating complex workpieces using a single-shot inductor. The complex workpiece has an at least partially cylindrical component with a central axis coinciding with the central axis of the circular component and connected at one end to the circular component having a diameter larger than the diameter of the at least partially cylindrical component. The single-shot single-turn inductor has a single cross-inductor section connected to first ends of two longitudinal leg inductor sections, wherein second ends of the two longitudinal leg inductor sections are connected to a ring inductor section that surrounds the entire circumference of at least a portion of the cylindrical assembly of the complex workpiece when loaded into the single-shot single-turn inductor for inductor heating applications. The cross inductor section along with the loop inductor section and the longitudinal leg inductor section are electrically connected in series to form a completed circuit.

Another aspect of the invention is an apparatus and method for single shot inductor induction heat treatment of complex workpieces. The complex workpiece has an at least partially cylindrical component with a central axis coincident with a central axis of the circular component and connected at one end to the circular component having a diameter larger than the diameter of the at least partially cylindrical component. The single shot, single turn inductor has a first loop inductor section connected to first ends of two longitudinal leg inductor sections, wherein second ends of the two longitudinal leg inductor sections are connected to a second loop inductor section. When the complex workpiece is loaded into a single shot single turn inductor for inductor heating applications, the first and second ring inductor sections surround the entire circumference of the at least partially cylindrical assembly of the complex workpiece. One of the two longitudinal leg inductor sections is configured to supply alternating current to a single shot inductor.

The single shot inductor of the present invention may also be used to heat treat cylindrical workpieces wherein the axial length of the cylindrical workpiece is inserted into the single shot inductor of the present invention.

The above and other aspects of the invention are set out in the present description and appended claims.

Drawings

The drawings, which are briefly summarized below, are provided for illustrative understanding of the present invention and are not limited to the invention as further set forth in the specification and appended claims.

Fig. 1(a) is an example of a complex workpiece, wherein at least a partially cylindrical component of the complex workpiece has a central axis that coincides with a central axis of a circular component and is connected at one end to the circular component having a diameter that is larger than the diameter of the at least partially cylindrical component.

FIG. 1(b) is an isometric view of one example of a prior art channel inductor that may be used to heat treat the complex workpiece of FIG. 1 (a).

FIG. 1(c) depicts the complex workpiece of FIG. 1(a) loaded into the prior art channel sensor of FIG. 1 (b).

Fig. 2(a), 2(b) and 2(c) illustrate a prior art arrangement for heat treating a complex workpiece having a single turn channel inductor, in which only the right half section of the lower cross section of the inductor is shown.

Fig. 3 is an isometric view of one example of a single-shot inductor of the present invention, with arrows indicating the instantaneous current flowing through the inductor.

Fig. 4(a) and 4(b) are single shot inductors of fig. 3, depicted with a 90 degree central axis rotation between fig. 4(a) and 4(b) to illustrate one example of inductor step areas positioned in the ring inductor segment to accommodate the hardness pattern of the desired workpiece and workpiece geometry, such as the change in diameter for the particular workpiece being heated.

Fig. 5(a) and 5(b) are single shot inductors of fig. 4(a) and 4(b) partially hollowed out to show internal cooling medium flow passages through the inductor.

Fig. 6 depicts in cross-sectional elevation a complex workpiece prior to loading into the single shot inductor shown in fig. 3.

Fig. 7 depicts a complex workpiece after loading into the single shot inductor shown in fig. 3 in a cross-sectional elevation view of a flat interface through a longitudinal pillar section.

Figure 8 diagrammatically illustrates another example of a single-shot inductor of the present invention.

Fig. 9(a) and 9(b) are isometric views of another example of a single shot inductor of the present invention, with the arrows indicating the instantaneous current flowing through the inductor.

Detailed Description

Fig. 3 to 5(b) show an example of the single-shot inductor 10 of the present invention. Referring to fig. 3, the single-shot inductor 10 includes a cross inductor section 12, longitudinal leg sections 14a and 14b, and a loop inductor section 16. The crossover section 12 includes crossover half-sections 12a and 12 a'. The crossover half-sections 12a and 12a 'are electrically isolated from each other, for example by a dielectric tank 22, so that the crossover half-sections 12a and 12 a' can be connected to the output of an ac power source 24. The dielectric slots 22 may be gas filled dielectric or filled with an electrically insulating material such as mica sheets. The loop inductor section 16 includes continuous loop half sections 16a and 16b that form continuous electrical conductors that are electrically connected to the longitudinal strut sections 14a and 14 b. The two half-sections 16a and 16b of the ring inductor section 16 are electrically connected in parallel with respect to each other. Each of the half-sections 16a and 16b of the loop inductor 16 is in this example contoured to have high-order-like regions (16a 'and 16 b') and low-order-like regions (16a "and 16 b") connected by slanted interconnection regions (16a '"and 16 b'") as shown in fig. 3. In all embodiments of the present invention, contouring may be accomplished by selected regions of the raised profile ring inductor section, as may be required to accommodate the geometry of the particular complex workpiece being heat treated. Alternatively, the cross inductor section or the longitudinal strut inductor section may also be profiled.

The instantaneous ac current flowing through the single-shot inductor 10 is depicted by the arrows in fig. 3. Thus, transient currents flow from one of the crossover half-sections into one of the two longitudinal leg sections, to the loop inductor section 16, then through the parallel loop half-sections 16a and 16b, and out of the loop inductor section 16 to the other longitudinal leg section for return to the other crossover half-section. This configuration reduces the current magnitude of each of the loop half-sections required as compared to the prior art single-shot single turn channel inductor described above having two intersecting sections, while maintaining the same required thermal energy in the workpiece as compared to the prior art partial wrap-around described above by wrapping around the entire circumference of the workpiece. A reduction in the magnitude of the current in the loop half-section reduces the current density and electromagnetic forces, which results in an increase in the lifetime of the single-shot inductor 10 over that of the prior art single-shot single turn channel inductor.

For purposes of explanation and not limitation, the crossover half-section 12a may be referred to as a supply crossover section, the longitudinal leg inductor section 14a may be referred to as a supply longitudinal leg inductor section, the longitudinal leg inductor section 14b may be referred to as a return longitudinal leg inductor section, and the crossover half-section 12 a' may be referred to as a return crossover section. The supply crossover section has a power supply end 13a and an opposite supply strut crossover section end 13 b. The return crossover section has a power return end 13c and an opposite return strut crossover section end 13 d. The first ring section 16a has opposed first ring section supply strut end 17b and first ring section return strut end 17a, and the second ring section 16b has opposed second ring section supply strut end 17c (see fig. 4(b)) and second ring section return strut end 17 d. Dashed lines are used to refer to the ends of each of the first and second ring segments 16a, 16b, and the ring inductor segment 16 (formed by the first and second ring segments 16a, 16 b) is typically fabricated as a continuous generally annular cylindrical component. The supply longitudinal strut sensor section 14a has a supply strut cross end 14 a' and a supply strut ring end 14a ". The supply strut crossover end 14 a' is connected to the supply strut crossover section end 13b, and the supply strut ring end 14a "is connected between the first ring section supply strut end 17b and the second ring section supply strut end 17 c. The return longitudinal leg inductor section 14b has a return leg cross end 14 b' and a return leg loop end 14b ". The return leg crossover end 14 b' is connected to the return leg crossover section end 13d and the return leg ring end 14b "is connected between the first ring section return leg end 17a and the second ring section return leg end 17d to form a continuous electrical conductor from the first ring section and the second ring section surrounding the supply leg ring end and the return leg ring end of the supply longitudinal leg inductor section and the return longitudinal leg inductor section such that when at least a partially cylindrical assembly of the complex workpiece is positioned between the supply longitudinal leg inductor section and the return longitudinal leg inductor section, the circular assembly of the complex workpiece is positioned adjacent the outer face 16c of the ring inductor section and an alternating current power source is connected between the power supply end of the supply crossover section and the power return end of the return crossover section, the complex workpiece being inductively heat treated.

Fig. 4(a) and 4(b) divide the continuous loop inductor segment 16 into contoured regions 16 'and 16a "(see fig. 3) of a first loop segment 16a, and 16 b' and 16 b" of a second loop segment 16b (see fig. 3) to illustrate one example of contouring the continuous loop inductor segment 16 formed by the first and second loop segments. As described above, this contouring of the ring into the inductor step region accommodates desired workpiece hardness patterns and workpiece geometry, such as diameter variations or wall thickness variations (e.g., when at least a portion of the cylindrical component of the complex workpiece being heated is hollow). Two or more step regions are required in each ring half-section, and all or some of the ring steps may not be equal in volume to one another. Furthermore, the arc (bow) lengths of each of the angled interconnected regions (16a "'and 16 b"') may differ from one another and be fabricated to have different effects on the energy induced in a particular region of the complex workpiece, such as the shaft region or the fillet region between the at least partially cylindrical and circular components of the complex workpiece.

Fig. 5(a) and 5(b) depict the inlet and outlet on a single shot inductor 10 for supplying and returning a fluid cooling medium for cooling the inductor 10 caused by joule effect heating as alternating current flows through the inductor. In this embodiment, two separate cooling circuits are provided, referred to as a cooling circuit "flow" (shown with solid arrows) and a cooling circuit "in" (shown with dashed arrows). As shown in fig. 5(a) and 5(b), the supply inlet ("shown) cooling path passes through, in sequence: ring half segments 16a (16 a' and 16a "); longitudinal strut inductor section 14b and crossover half section 12a 'to return outlet ("return outlet ()), and supply inlet (", and supply cooling path pass sequentially through ring half sections 16b (16 b' and 16b "),. longitudinal strut inductor section 14a and crossover half section 12a to return outlet (" return outlet () ". the advantage of separate dual cooling loops for different sections of inductor 10 is that it allows different cooling parameters to compensate for asymmetric features in the fabrication of inductor 10. furthermore, each separate supply inlet enters and cools first a separate ring half section, which will generate the most heat, and then continues to flow through a separate longitudinal strut inductor section and a separate crossover half section. And is used with the particular complex workpiece of the present invention.

In fig. 3-5 (b), the cross induction section is generally (i.e., without contouring) semi-cylindrical in shape and is divided into generally quarter-cylindrical cross half sections by dielectric slots 22. In other embodiments of the invention, the cross inductor section may be substantially larger or smaller in shape than the half cylinder, and the cross half section may be substantially larger or smaller than the quarter cylinder half section of an equal mirror image shape, or an unequal shape for the particular complex workpiece being heat treated. In fig. 3-5 (b), each longitudinal strut inductor segment turn is generally (i.e., without contouring) a rectangular strip in shape andand is substantially (i.e., without contouring) perpendicular to a radial cross-sectional plane intersecting the inductor and ring inductor sections, which plane is perpendicular to the central axis C_LAnd may be additionally shaped or oriented in other embodiments of the invention for the particular complex workpiece being heat treated. In fig. 3-5 (b), the ring inductor section is generally (i.e., without contouring) in the shape of an annular cylindrical ring having ring half sections of annular semi-cylindrical rings of equal arcuate length, with opposing longitudinal strut inductor sections connected to adjacent ends of the two ring half sections as shown in the figures, in other examples of the invention, the ring half sections may be of unequal arcuate length for the particular workpiece being heat treated.

Fig. 6 illustrates a complex workpiece 90 prior to loading into the single shot inductor 10. Fig. 7 illustrates a complex workpiece 10 loaded into a single shot inductor 10 for an induction heat treatment process. Suitable apparatus may be provided for loading the complex workpiece 90 to surround the central axis C during at least part of the heat treatment procedure_LAnd (4) rotating. Since the ring section 16 surrounds the entire circumference of the loaded complex workpiece 90, the heating energy in the fillet region 90d is increased without unduly reducing the current carrying surface of the inductor and without unduly increasing the magnitude of the coil current.

If the complex workpiece is located asymmetrically within inductor 10 (i.e., the axis of symmetry (A) of ring inductor segment 16_collar) And the axis of symmetry (C) of the complex workpiece 90 within the inductor 10_L) Misaligned), then a reduced induction heating effect will be produced in one of the two half-ring sections having an increased inductor-to-tool gap, which is offset by an increased induction heating effect produced by the other of the two half-ring sections having a reduced inductor-to-tool gap. Thus, the induction heat treatment program sensitivity associated with the positioning of the complex workpiece 90 within the inductor 10 is reduced over the program sensitivity described above for the prior art single turn channel inductors.

Fig. 8 shows another example of the single-shot inductor 11 of the present invention. In this example, unlike the single shot inductor 10, the longitudinal strut inductionThe longitudinal lengths of sections 15a and 15b are not equal such that the crossing half sections 13a and 13 a' of crossing inductor section 13 are positioned about the central axis of the workpiece loaded in single shot inductor 11. When the longitudinal strut sections differ in longitudinal length, the supply and return crossover sections will be separated by a plane z between the crossover half-sections 13a and 13a₁Relative to a central axis C perpendicular to the central axis C illustrated in FIG. 8_LThe respective cross-sectional radial planes of the supply and return crossover sections of (a) are not coplanar with each other. Furthermore, the contouring of the faces 13aa and 13aa '(shown hatched) of the intersecting half-sections 13a and 13 a' may be different. In fig. 8, the loop inductor section 16 may be similar to the loop inductor section 16 for the single shot inductor 10.

Fig. 9(a) and 9(b) illustrate another example of a single-shot inductor 30 of the present invention. In this embodiment, the second loop inductor segment replaces the crossed inductor segments in other embodiments of the invention, and one of the two longitudinal leg segments is divided into two electrically isolated longitudinal half-leg segments so that the power source 24 can be connected between the longitudinal half-leg segments, and the two loop inductor segments at the opposite ends of the longitudinal leg segment of the single shot induction 30 are connected together in series by an undivided central leg segment 34 b. For convenience, in fig. 9(a) and 9(b), the two ring inductor sections are referred to as top ring inductor section 32 and bottom ring inductor section 36 without limiting the top and bottom spatial orientation of the two ring inductor sections. The top ring inductor section 32 includes a top ring first section 32a and a top ring second section 32b electrically connected in parallel. Dashed lines are used to refer to the ends of each ring segment, and the top ring 32 is typically fabricated as a continuous generally annular cylindrical component. The top ring first section has opposing top ring first section first strut ends 32a 'and top ring first section second strut ends 32a ", and the top ring second section has opposing top ring second section first strut ends 32 b' and top ring second section second strut ends 32 b". The bottom ring inductor section 36 includes a bottom ring first section 36a and a bottom ring second section 36 b. The bottom ring first section 36a has opposing bottom ring first section first strut ends 37a and bottom ring first section second strut ends 37b, and the bottom ring second section 36b has opposing bottom ring second section first strut ends 37c and bottom ring second section second strut ends 37 d. The power supply longitudinal strut inductor section 34a has a power supply longitudinal strut top ring section end 34 a' and a power supply longitudinal strut bottom ring section end 34a ". The power supply terminal 35a and the power return terminal 35b are located between the power supply longitudinal pillar top ring section end and the power supply longitudinal pillar bottom ring section end. The terms "supply" and "return" are used for convenience and do not limit the orientation of the single-shot inductor 30, and the arrows show the instantaneous direction of alternating current flow through the single-shot inductor 30. The electrical isolation between the power supply terminals and the power return terminals is provided by a dielectrically gas-chargeable space 35 or a dielectric material (such as a mica sheet) between the terminals. The power supply longitudinal strut top ring section end 34a ' is connected to the top ring first section first strut end 32a ' and the second section first strut end 32b ', and the power supply longitudinal strut bottom ring section end 34a "is connected to the bottom ring first section first strut end 37a and the bottom ring second section first strut end 37 c. The return longitudinal strut inductor section 34b has a return longitudinal strut top ring section end 34 b' and a return longitudinal strut bottom ring section end 34b ". The return longitudinal leg top ring section end 34 b' is connected to the top ring first section second leg end 32a "and the top ring second section second leg end 32 b", and the return longitudinal leg bottom ring section end 34b "is connected to the bottom ring first section second leg end 37b and the bottom ring second section second leg end 37d, such that when the complex workpiece is loaded in the single shot inductor 30, at least a partially cylindrical assembly of the complex workpiece being heat treated is located between the power supply longitudinal leg inductor section 34a and the power supply return longitudinal leg inductor section 34b, and the circular assembly of the complex workpiece is located adjacent the outer face 36c of the bottom ring 36, and an ac power supply is connected between the power supply terminal 35a and the power return terminal 35b, the complex workpiece being induction heat treated. The outer face 36c of the bottom ring inductor section is the face facing away from the bottom coil of the top ring inductor section. In the present example, the contoured regions 36a ', 36a ", and 36 a'" in the bottom ring first section 36 and the contoured regions 36b ', 36b ", and 36 b'" in the bottom ring second section 36b are similar to the contoured regions 16a ', 16a ", and 16 a'" in the bottom ring first section 16a and the contoured regions 16b ', 16b ", and 16 b'" in the bottom ring second section 16b, respectively, of the single shot inductor 10.

In fig. 9(a) and 9(b), the top and bottom ring inductor sections are each generally (i.e., without contouring) in the shape of an annular cylindrical ring, with the ring half sections being annular semi-cylindrical rings of equal arcuate length and the opposing longitudinal strut sections connected to adjacent ends of the two ring half sections, which in other examples of the invention may be of different arcuate lengths for the particular workpiece being heat treated. In fig. 9(a) and 9(b), the separated and unseparated longitudinal leg inductor segments are each generally (i.e., without contouring) rectangular strips in shape and are generally (i.e., without contouring) perpendicular to the top ring inductor segment cross-sectional radial plane and the bottom ring inductor segment cross-sectional radial plane, the cross-sectional radial planes being perpendicular to the central axis C_LAnd may be additionally shaped or oriented in other embodiments of the invention for the particular complex workpiece being heat treated.

One preferred dual, single cooling loop configuration for the single shot inductor 30 in fig. 9(a) and 9(b) is a dual, isolated cooling loop configuration, wherein, for example, a first isolated cooling loop flows through the top ring 32 and a second isolated cooling loop flows through the bottom ring 36. In other embodiments of the invention, a single or multiple isolated cooling circuits may be used for the single-shot inductor 30 in fig. 9(a) and 9 (b).

In other examples of the invention, the single-shot inductor 10 or 11 of the invention may be a single-shot multi-turn inductor, e.g., a single-shot two-turn inductor having two loop inductor sections and a pair of separate longitudinal leg sections connected to each loop inductor section.

Complex workpiece features having at least partially cylindrical components with central axes coincident with the central axes of the circular components comprise complex workpieces in which the central axes of the at least partially cylindrical components are non-coincident and can still be inserted (loaded) between the longitudinal leg inductor sections of the single shot inductor of the present invention while maintaining a minimum radial air gap between the at least partially cylindrical components and the longitudinal leg inductor sections.

The single shot inductor of the present invention may also optionally be used for induction heat treating cylindrical workpieces, such as shafts.

While the above example of a single shot inductor incorporates an inductor and workpiece oriented in a vertical direction, other orientations may be used in other embodiments of the invention. The terms "top" and "bottom" as well as "supply" and "return" are used for explanation only and do not limit the scope of the invention, as other orientations of the single-shot inductor are also acceptable.

Quenching of the workpiece heated in the single-shot inductor of the present invention may be accomplished after the workpiece is heated and removed from the single-shot inductor, or in other examples of the present invention a quenching channel may be provided inside the single-shot inductor of the present invention, and quenchant from a suitable source may quench the workpiece through the internal quenching channel while the workpiece is not yet unloaded from the single-shot inductor.

Any single-shot inductor of the present invention can be fabricated from a copper block as a monolithic inductor, for example, by computer-aided manufacturing (CAM).

In the description above, for purposes of explanation, numerous specific requirements and several specific details have been set forth in order to provide a thorough understanding of the examples and embodiments. It will be apparent, however, to one skilled in the art that one or more examples or embodiments may be practiced without these specific details. The particular embodiments described are not provided to limit the invention but to illustrate it.

Reference throughout this specification to "one example or embodiment," "an example or embodiment," "one or more examples or embodiments," or "a different example or embodiment," for example, means that a particular feature may be included in the practice of the invention. In the description, various features are sometimes grouped together in a single example, embodiment, figure, or description for the purpose of streamlining the disclosure and aiding in the understanding of various inventive concepts.

The invention has been described with reference to preferred examples or embodiments. Equivalents, alternatives, and modifications are possible, except where expressly stated, and are within the scope of the invention.

Claims (17)

1. A single-shot inductor for induction heat treatment of a complex workpiece, the complex workpiece comprising an at least partially cylindrical component having a central axis coincident with a central axis of a circular component, the at least partially cylindrical component being connected to the circular component at one end thereof, and the circular component having a circular component diameter greater than a cylindrical component diameter of the at least partially cylindrical component, the single-shot inductor comprising:

a cross-inductor section comprising a supply cross-section having a power supply end and a supply leg cross-section end opposite the power supply end, and a return cross-section having a power return end and a return leg cross-section end opposite the power return end, the supply cross-section and the return cross-section being electrically isolated from each other between the power supply end and the power return section, the power supply end and the power return end being positioned adjacent to each other and separated by a dielectric;

a ring inductor section comprising a first ring section having a first ring section supply leg end opposite the first ring section supply leg end and a first ring section return leg end opposite the second ring section supply leg end and a second ring section return leg end opposite the second ring section supply leg end;

a supply longitudinal leg inductor section having a supply leg cross end and a supply leg loop end, the supply leg loop end opposite the supply leg cross end, the supply leg cross end connected to the supply leg cross section end, and the supply leg loop end connected between the first and second loop section supply leg ends; and

a return longitudinal leg inductor section having a return leg cross end and a return leg loop end, the return leg loop end opposite the return leg cross end, the return leg cross end connected to the return leg cross section end, and the return leg loop end connected between the first loop section return leg end and the second loop section return leg end to form a continuous electrical conductor from the first loop section and the second loop section surrounding the supply leg loop end of the supply longitudinal leg inductor section and the return leg loop end of the return longitudinal leg inductor section, whereby when the at least partially cylindrical assembly of the complex workpiece is positioned between the supply longitudinal leg inductor section and the return longitudinal leg inductor section, and the circular assembly is positioned adjacent to an outer face of the loop inductor section, and an alternating current power source is connected between the power supply terminal of the supply cross section and the power return terminal of the return cross section, the complex workpiece is induction heat treated.

2. The single-shot inductor of claim 1,

the crossover inductor section is semi-cylindrical in shape, and the supply crossover section and the return crossover section are each quarter-cylindrical in shape;

the ring inductor segment is an annular cylindrical ring in shape, and the first ring segment and the second ring segment are each annular semi-cylindrical rings in shape and are the same arcuate length; and

the supply longitudinal leg inductor section and the return longitudinal leg inductor section are oriented perpendicular in length to a radial plane of the cross inductor section and the loop inductor section.

3. The single-shot inductor of claim 1 or 2, wherein the supply crossover section and the return crossover section are not coplanar with one another.

4. The single-shot inductor of claim 1 or 2, further comprising at least one profiled region in at least one of the supply crossover section, the return crossover section, the supply longitudinal leg inductor section, the return longitudinal leg inductor section, the first loop section, or the second loop section.

5. The single-shot inductor of claim 4 wherein the at least one profiled region comprises a stepped profile region.

6. The single-shot inductor of claim 1 or 2 further comprising at least one internal cooling loop formed within the cross inductor section, the supply longitudinal leg inductor section, the return longitudinal leg inductor section, and the loop inductor section for flowing a cooling medium within the at least one internal cooling loop.

7. The single-shot inductor of claim 1 or 2, further comprising:

a first cooling circuit comprising:

a first cooling circuit supply inlet port in communication with a first ring section internal cooling passage in the first ring section;

a return longitudinal strut inductor section internal cooling passage in the return longitudinal strut inductor section in communication with the first ring section internal cooling passage;

a return crossover section internal cooling passage in the return crossover section in communication with the return longitudinal strut inductor section internal cooling passage; and

a first cooling loop return outlet port in communication with the return crossover section internal cooling passage whereby a cooling medium flows sequentially through the first ring section, the return longitudinal leg inductor section, and the return crossover section;

and

a second cooling circuit comprising:

a second cooling circuit supply inlet port in communication with a second ring section internal cooling passage in the first ring section;

a supply longitudinal strut inductor section internal cooling channel in the supply longitudinal strut inductor section in communication with the second ring section internal cooling passage;

a supply cross section internal cooling passage in the supply cross section in communication with the supply longitudinal strut inductor section internal cooling passage; and

a second cooling loop return outlet port in communication with the supply crossover section internal cooling passage, whereby the cooling medium flows sequentially through the second ring section, the supply longitudinal leg inductor section, and the supply crossover section.

8. A single shot inductor for inductor heat treatment of a complex workpiece, the complex workpiece comprising an at least partially cylindrical component having a central axis coincident with a central axis of a circular component, the at least partially cylindrical component being connected to the circular component at one end and the circular component having a circular component diameter greater than a cylindrical component diameter of the at least partially cylindrical component, the single shot inductor comprising:

a top ring inductor section comprising a top ring first section and a top ring second section, the top ring first section having a top ring first section first leg end and a top ring first section second leg end, the top ring first section second leg end opposite the top ring first section first leg end, the top ring second section having a top ring second section first leg end and a top ring second section second leg end, the top ring second section second leg end opposite the top ring second section first leg end;

a bottom ring inductor section comprising a bottom ring first section having a bottom ring first section first leg end opposite the bottom ring first section first leg end and a bottom ring first section second leg end opposite the bottom ring second section first leg end;

a power supply longitudinal strut inductor section having a power supply longitudinal strut top ring section end and a power supply longitudinal strut bottom ring section end, a power supply terminal and a power return terminal located between the power supply longitudinal strut top ring section end and the power supply longitudinal strut bottom ring section end, the power supply terminal and the power return terminal being electrically isolated from each other, the power supply longitudinal strut top ring section end connected to the top ring first section first strut end and the top ring second section first strut end, and the power supply longitudinal strut bottom ring section end connected to the bottom ring first section first strut end and the bottom ring second section first strut end; and

a return longitudinal strut inductor section having a return longitudinal strut top ring section end and a return longitudinal strut bottom ring section end, the return longitudinal strut bottom ring section end opposite the return longitudinal strut top ring section end, the return longitudinal strut top ring section end connected to the top ring first section second strut end and the top ring second section second strut end, and the return longitudinal strut bottom ring section end connected to the bottom ring first section second strut end and the bottom ring second section second strut end, whereby when the complex workpiece is loaded into the single shot inductor, the at least partially cylindrical component is positioned between the power supply longitudinal strut inductor section and the return longitudinal strut inductor section and the circular component is positioned adjacent to an exterior face of the bottom ring inductor section, and an alternating current power source is connected between the power supply terminal and the power return terminal, the complex workpiece is heat-treated by an induced current.

9. The single-shot inductor of claim 8 wherein:

each of the top ring inductor section and the bottom ring inductor section is an annular cylindrical ring in shape; the top ring first section and the top ring second section are each annular semi-cylindrical rings in shape and of the same arcuate length; and the bottom ring first section and the bottom ring second section are each annular semi-cylindrical rings in shape and of the same arcuate length; and

the power supply longitudinal leg inductor section and the return longitudinal leg inductor section are vertically oriented in length to radial planes of the top and bottom ring inductor sections.

10. The single-shot inductor of claim 8 or 9 wherein the distance between the power supply terminal and the power supply longitudinal strut top loop section end is not equal to the distance between the power return terminal and the power supply longitudinal strut bottom loop section end.

11. The single-shot inductor of claim 8 or 9 further comprising at least one profiled region of at least one of the top loop inductor section, the bottom loop inductor section, the power supply longitudinal leg inductor section, or the return longitudinal leg inductor section.

12. The single-shot inductor of claim 11 wherein the at least one profiled region comprises a stepped profile region.

13. The single-shot inductor defined in claim 8 or claim 9 further comprising at least one or more internal cooling loops formed in the top ring inductor section, the power supply longitudinal leg inductor section, the return longitudinal leg inductor section and the bottom ring inductor section for flowing a cooling medium within the at least one or more internal cooling loops.

14. A method of single shot induction heat treatment of a complex workpiece comprising an at least partially cylindrical component having a central axis coincident with a central axis of a circular component, the at least partially cylindrical component being connected at one end to the circular component and the circular component having a circular component diameter greater than the cylindrical component diameter of the at least partially cylindrical component, wherein the heat treatment inductor comprises: a cross-inductor section comprising a supply cross-section having a power supply end and a supply leg cross-section end opposite the power supply end, and a return cross-section having a power return end and a return leg cross-section end opposite the power return end, the supply cross-section and the return cross-section being electrically isolated from each other between the power supply end and the power return section, the power supply end and the power return end being positioned adjacent to each other and separated by a dielectric; a ring inductor section comprising a first ring section having a first ring section supply leg end opposite the first ring section supply leg end and a first ring section return leg end opposite the second ring section supply leg end and a second ring section return leg end opposite the second ring section supply leg end; a supply longitudinal leg inductor section having a supply leg cross end and a supply leg loop end, the supply leg loop end opposite the supply leg cross end, the supply leg cross end connected to the supply leg cross section end, and the supply leg loop end connected between the first and second loop section supply leg ends; and a return longitudinal leg inductor section having a return leg cross end and a return leg loop end, the return leg loop end opposite the return leg cross end, the return leg cross end connected to the return leg cross section end, and the return leg loop end connected between the first loop section return leg end and the second loop section return leg end to form a continuous electrical conductor from the first loop section and the second loop section around the supply leg loop end of the supply longitudinal leg inductor section and the return leg loop end of the return longitudinal leg inductor section, the method comprising:

loading the at least partially cylindrical assembly of the complex workpiece positioned between the supply longitudinal leg inductor section and the return longitudinal leg inductor section such that the circular assembly is positioned adjacent to an exterior face of the ring inductor section of the heat treatment inductor;

providing an alternating current between the power supply terminal of the supply crossover section and the power return terminal of the return crossover section to inductively heat treat the complex workpiece;

unloading the complex workpiece from the thermal processing inductor.

15. The method of claim 14, further comprising rotating the complex workpiece about the central axis of the complex workpiece while supplying alternating current between a power supply end of the supply crossover section and a power return end of the return crossover section for at least a portion of a time period.

16. A method of single shot induction heat treatment of a complex workpiece comprising an at least partially cylindrical component having a central axis coincident with a central axis of a circular component, the at least partially cylindrical component being connected to the circular component at one end thereof, and the circular component having a circular component diameter greater than the cylindrical component diameter of the at least partially cylindrical component, wherein the heat treatment inductor comprises:

a top ring inductor section comprising a top ring first section and a top ring second section, the top ring first section having a top ring first section first leg end and a top ring first section second leg end, the top ring first section second leg end opposite the top ring first section first leg end, the top ring second section having a top ring second section first leg end and a top ring second section second leg end, the top ring second section second leg end opposite the top ring second section first leg end;

a bottom ring inductor section comprising a bottom ring first section having a bottom ring first section first leg end opposite the bottom ring first section first leg end and a bottom ring first section second leg end opposite the bottom ring second section first leg end;

a power supply longitudinal strut inductor section having a power supply longitudinal strut top ring section end and a power supply longitudinal strut bottom ring section end, a power supply terminal and a power return terminal located between the power supply longitudinal strut top ring section end and the power supply longitudinal strut bottom ring section end, the power supply terminal and the power return terminal being electrically isolated from each other, the power supply longitudinal strut top ring section end connected to the top ring first section first strut end and the top ring second section first strut end, and the power supply longitudinal strut bottom ring section end connected to the bottom ring first section first strut end and the bottom ring second section first strut end;

a return longitudinal strut inductor section having a return longitudinal strut top ring section end and a return longitudinal strut bottom ring section end, the return longitudinal strut bottom ring section end opposite the return longitudinal strut top ring section end, the return longitudinal strut top ring section end connected to the top ring first section second strut end and the top ring second section second strut end, and the return longitudinal strut bottom ring section end connected to the bottom ring first section second strut end and the bottom ring second section second strut end,

the method comprises the following steps:

loading the at least partially cylindrical assembly of the complex workpiece between the power supply longitudinal leg inductor section and the return longitudinal leg inductor section such that the circular assembly is positioned adjacent to an exterior face of the bottom ring inductor section of the heat treatment inductor;

providing alternating current between the power supply terminal and the power return terminal to inductively heat the complex workpiece;

unloading the complex workpiece from the thermal processing inductor.

17. The method of claim 16, further comprising rotating the complex workpiece about the central axis of the complex workpiece while providing an alternating current between the power supply and power return for at least a portion of the time period to inductively heat treat the complex workpiece.