The disclosure relates generally to induction heating, and more particularly to heating bored parts using induction heating.
A bored part can be connected to a shaft via an interference fit where the diameter of the shaft is slightly larger than the diameter of the bore. In order to establish such interference fit, a shrink-fitting technique may be employed where the bored part is heated in order to thermally expand the size of the bore before inserting the shaft, which is at a lower temperature than the bored part, into the bore. Subsequent cooling of the bored part with the shaft inserted in the bore causes the bore to contract and become engaged with the shaft via an interference fit.
Obtaining a relatively uniform temperature distribution in the region of the bore of the bored part without having to heat the entire bored part prior to shrink-fitting can be challenging. Improvement is desirable.
In one aspect, the disclosure describes a method of heating a part having a bore formed therein using induction heating. The part is oriented so that a central axis of the bore of the part is oriented between 0 and 45 degrees of horizontal. The method comprises:
mounting an induction heating fixture including an induction heating coil to the part so that:
one or more locators of the induction heating fixture are engaged with the part;
the induction heating coil is disposed inside the bore of the part;
the induction heating coil is disposed eccentrically relative to the bore of the part so that the induction heating coil is disposed closer to a lower surface portion of the bore than to an upper surface portion of the bore; and
the induction heating coil is inductively coupled to the part; and
after mounting the induction heating fixture to the part, driving alternating electric current into the induction heating coil to heat the part.
In another aspect, the disclosure describes a method of heating a part having a non-vertical bore using induction heating. The method comprises:
installing an induction heating coil inside the bore of the part so that the induction heating coil is inductively coupled to at least a majority of a circumferential surface of the bore of the part, the bore of the part having a central bore axis, the induction heating coil being wound about a coil axis, the coil axis and the bore axis being non-coaxial, the part being oriented so that the bore axis is non-vertical; and
after installing the induction heating coil inside the bore of the part, driving alternating electric current into the induction heating coil to heat the part.
In a further aspect, the disclosure describes an induction heating assembly comprising:
a part having a bore, the bore having a central bore axis; and
a fixture mounted to the part, the fixture including:
a base including one or more locators engaged with the part and locating the base relative to the part; and
an induction heating coil supported by the base, the induction heating coil being disposed inside the bore of the part and being inductively coupled to the part, the induction heating coil being wound about a coil axis, the coil axis and the bore axis being non-coaxial.
Further details of these and other aspects of the subject matter of this application will be apparent from the detailed description included below and the drawings.
Reference is now made to the accompanying drawings, in which:
This disclosure describes fixtures and methods to facilitate induction heating of bored parts. In some embodiments, the fixtures and methods described herein may promote a relatively uniform heat distribution within a bored region of a bored part without having to heat the entire part, and also without having to rotate the part. Induction heating of a bored part using a fixture and method described herein may be used to establish an interference fit (via shrink fitting) between a bored part and a counterpart component such as a shaft for example. In some embodiments, the fixtures and methods described herein may be used to heat a bored region (e.g., bored hub) of a rotor disk such as a turbine rotor disk, or a compressor rotor disk of a gas turbine engine. The heating of the rotor disk may be part of a shrink-fitting procedure for establishing an interference fit between the rotor disk and a shaft of the gas turbine engine for example. The fixtures and methods described herein may also be used to establish shrink fits between other types of parts, including for the installation of bearings and seals for example.
In some embodiments, the fixtures and methods described herein may be used to heat a bored part that may be oriented so that the bore is substantially horizontal. In the horizontal orientation, such bore may be susceptible to convective heat transfer where an upper portion of the bore may become hotter than a lower portion of the bore due to heat tending to rise. During a shrink-fitting procedure, uneven heating of the part in the region of the bore may increase the risk of misalignment between the bored part and the shaft after the shrink fit has been established. In order to counter the problem of uneven heating due to convective heat transfer, the fixtures and methods described herein may position an induction coil eccentrically within the bore so that the induction coil may be disposed closer to a bottom surface portion of the bore than to an upper surface portion of the bore. The eccentric positioning of the induction coil may partially compensate for the convective heat transfer by inducing a higher flux density in the lower portion of the bore than in the upper portion of the bore and thereby promote a more uniform temperature distribution around the bore of the part.
Aspects of various embodiments are described through reference to the drawings.
The terms “attached”, “engaged” or “coupled” may include both direct attachment/engagement/coupling (in which two elements contact each other) and indirect coupling attachment/engagement/coupling (in which at least one additional element is disposed between the two elements).
The term “substantially” as used herein may be applied to modify any quantitative representation which could permissibly vary without resulting in a change in the basic function to which it is related.
Fixture 10 may be configured to be mounted to part 12 as shown by arrows A1 in
Base 16 may define any structure suitable to facilitate a relative secure attachment of fixture 10 to part 12. In some embodiments, base 16 may include (e.g., three) legs 22 extending radially outwardly from coil axis A. Legs 22 may each have one or more locators and/or one or more clamps for engagement with part 12 as shown in
Fixture 10 may include carriage 24 adjustably attached to base 16. Coil 18 may be attached to carriage 24 and be adjustable with carriage 24 relative to base 16. A (e.g., vertical) position of carriage 24 may be adjustable along arrow A2 relative to base 16 via one or more actuators 26. Actuators 26 may be manually or electrically actuatable. In some embodiments, actuators 26 may each include a screw to impart relative movement between base 16 and carriage 24.
It is understood that, in some embodiments, a suitable fixture without such adjustability may be used to support coil 18 at a fixed (i.e., non-adjustable, built-in) amount of eccentricity relative to bore 14. Such fixed amount of eccentricity may be predetermined based on empirical information and/or based on modeling/simulation information associated with heating a specific part and an expected uneven temperature distribution that is to be compensated by way of eccentric positioning of coil 18 relative to bore 14.
Even though bore axis BA is shown as being parallel with horizontal orientation H in
Coil 18 may be attached to suitable support and bracing structure, which may include stud board(s) and which may serve to attach (e.g., fasten, bond) coil 18 to carriage 24 in a suitable manner. In reference to
During heating of part 12 by induction heating, coil 18 may be disposed inside bore 14 and be inductively coupled to part 12. Inductive coupling between coil 18 and part 12 may occur when coil 18 is sufficient close to a surface of part 12 so that the alternating electric current in coil 18 induces an alternating electric current in part 12. In some embodiments, coil 18 may be inductively coupled with at least a majority of a circumferential surface of bore 14. For example, in cases where coil 18 has a multi-turn configuration, coil 18 may be inductively coupled to an entire circumference of bore 14 at least for some of the axial span of bore 14. As explained below, the eccentric positioning of coil 18 within bore 14 may result in a non-uniform inductive coupling distance between coil 18 and bore 14 around the circumference of bore 14. Such non-uniform coupling distance may consequently cause a non-uniform flux density around the circumference of bore 14 to compensate for convective heat transfer, and thereby promote a more uniform temperature distribution around bore 14.
In some embodiments, one or more temperature sensors 30 (e.g., thermocouple, infrared sensor) may be used during heating of part 12 to monitor and control the heating process. In some embodiments, temperature sensor 30 may be operatively connected to power supply 20 so that power supply 20 may supply current to coil 18 in a feedback control loop based on a desired set point temperature for example. Temperature sensor 30 may be operatively installed to measure a temperature of part 12 or other suitable component that may provide a feedback temperature suitable for controlling the operation of coil 18.
In order to determine a suitable amount of eccentricity between bore 14 and coil 18, two or more temperature sensors 30 may be used to monitor temperatures at different locations around bore 14 during induction heating. These temperatures may then be used to adjust the vertical position of coil 18 relative to bore 14 via actuators 26 to obtain the desired temperature distribution (e.g., uniformity) around bore 14.
The eccentricity of coil 18 relative to bore 14 may be expressed in terms of different (i.e., non-uniform) coupling distances D1, D2 between coil 18 and bore 14 around the circumference of bore 14. For example, upper coupling distance D1 may be greater than lower coupling distance D2 (i.e., D1>D2). In some embodiments, upper coupling distance D1 between coil 18 and top 14T of bore 14 may be between two and three times greater than lower coupling distance D2 between coil 18 and bottom 14B of bore 14. In some embodiments, upper coupling distance D1 between coil 18 and top 14T of bore 14 may be between 1.2 and six times greater than lower coupling distance D2 between coil 18 and bottom 14B of bore 14. Coupling distances D1 and D2 may be selected based on the orientation of bore axis BA, which may affect the influence of convective heat transfer on the temperature distribution. Coupling distances D1, D2 may be selected so that coil 18 is still inductively coupled with top 14T of bore 14 and with bottom 14B of bore 14 but that the flux density inducted by coil 18 may be greater at bottom 14B of bore 14 than at top of bore 14. For example, coupling distances D1, D2 may be between 0.06 inch (1.5 mm) and 0.4 inch (10 mm) in some embodiments. In various embodiments, coil 18 may be inductively coupled to at least a majority (or to an entirety) of a circumference of bore 14 when part 12 is being heated via coil 18.
Reasons for positioning coil 18 in an eccentric manner within bore 14 could be different than compensating for convective heat transfer. For example, such eccentric positioning could be done to compensate for a non-uniform wall thickness around bore 14. Another reason could be for compensating for a non-uniform distribution of mass around bore 14 due to the presence of holes that are not evenly distributed outside and along a circumference of bore 14 for example. Accordingly, fixture 10 may be used for eccentric positioning of coil 18 inside bores 14 having vertical, horizontal and/or other orientations.
The eccentricity of coil 18 relative to bore 14 may be expressed in terms of offset distance O between coil axis CA and bore axis BA. As shown in
In some embodiments, fixture 10 may be adjustable to permit positional adjustment of coil 18 relative to base 16. Positional adjustment of coil 18 may be achieved by adjustment of ring-shaped carriage 24 relative to base 16. In some embodiments, carriage 24 may be releasably attached to base 16 via one or more threaded fasteners 32 (e.g., bolts, screws) (referred hereinafter in the singular). Fastener 32 may extend through carriage 24 via slotted hole 34 and be threadingly engaged with base 16. Loosening of fastener 32 may permit movement of carriage 24 along arrow A2 by a travel amount afforded by slotted hole 34 and by actuator 26. Slotted hole 34 may be oriented so that a longer (major) axis of slotted hole 34 may be substantially parallel to vertical orientation V (shown in
In various embodiments, guiding of the movement of carriage 24 relative to base 16 may be achieve by any suitable means such as a screw or bolt inside a slot, a pin inside a slot, and/or a rail and a linear bearing system for example. In various embodiments, carriage 24 may be movable (e.g., translatable and/or rotatable) relative to base 16 in one or more degrees of freedom. In some embodiments, carriage 24 may be translatable only along a single direction (e.g., along arrow A2). In some embodiments, carriage 24 may be translatable along two orthogonal directions. In some embodiments, carriage 24 may be rotatable about coil axis CA.
As shown in
As shown in
installing coil 18 inside bore 14 of part 12 so that coil 18 is inductively coupled to part 12, bore 14 of part having a central bore axis BA, coil 18 being wound about coil axis CA, coil axis CA and bore axis BA being non-coaxial, part 12 being oriented so that bore axis BA is non-vertical (block 102); and
after installing coil 18 inside of bore 14 of part 12, driving alternating electric current into coil 18 to heat part 12 (block 104).
In some embodiments of method 100, coil 18 may be inductively coupled to at least a majority of a circumferential surface of bore 14 of part 12.
In some embodiments of method 100, part 12 may be oriented so that bore axis BA is between 0 and 45 degrees of horizontal orientation H.
Installing coil 18 inside of bore 14 may include mounting fixture 10 to part 12. Fixture 10 may include coil 18 and be mounted to part 12 so that one or more locators of fixture 10 are engaged with part 12. Coil 18 may be disposed eccentrically relative to bore 14 of part 12 so that coil 18 is disposed closer to a lower surface portion of bore 14 than to an upper surface portion of bore 14 to compensate for convective heat transfer and promote a more uniform temperature distribution around a circumference of bore 14.
The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology.