The present invention generally relates to an induction coil through which a workpiece is passed so that the workpiece can be inductively heated, and in particular, to such an induction coil that can be opened to allow maintenance to be performed with minimal disturbance of an electromagnetic shield assembly in which the induction coil can be enclosed to form an electromagnetically shielded inductor assembly.
A closed solenoidal induction coil can be used to inductively heat a material by passing the material through the coil while alternating current of a suitable frequency is supplied to the coil. Closed induction coils can be difficult to maintain. Electromagnetic shielding of induction coils is typically required to meet industrial and personal standards.
U.S. Pat. No. 4,761,530 discloses a box-like inductor assembly having an openable side door so that the inductor assembly can be laterally moved away from a continuous metal strip surrounded by the inductor assembly when the side door is closed. U.S. Pat. No. 5,317,121 discloses an induction coil having a gap through which through which a continuous metal strip can move laterally through so that it is either surrounded by the coil or moved out of the coil. U.S. Pat. No. 5,495,094 discloses various induction coils having a gap through which a continuous metal strip can move laterally through. U.S. Pat. No. 5,837,976 (“the '976 patent”) discloses various arrangements of induction coils having a gap through which a continuous metal strip can move laterally through. In some embodiments, the '976 patent discloses flexible interconnecting member(s) of the induction coil so that the flexible interconnecting member(s) can be spread apart to increase the size of the gap as shown in
International Publication No. WO 2005/004559 A2 discloses an electromagnetic shield for use with induction coils incorporating a gap as described, for example, in the above patents. The electromagnetic shield also incorporates at least one gap so that a continuous metal strip can move laterally in and out of the induction coil and surrounding electromagnetic shield through the gaps in the induction coil and electromagnetic shield.
International Publication No. WO 2007/081918 A2 discloses an electromagnetically shielded induction heating apparatus that includes a substantially gas tight enclosure and electromagnetic shield material. The induction heating apparatus/coil surrounding the gas tight enclosure is not openable.
Japanese patent publication JP 63-4873 (published 1988 and now in the public domain) discloses a method of blowing hot air through a non-openable induction furnace to prevent the formation of dew from vapors released by a coating material in the furnace.
It is one object of the present invention to provide an electromagnetically shielded openable induction coil that can be conveniently opened for maintenance with minimal disturbance of a surrounding electromagnetic shield structure that forms an inductor assembly with the coil.
It is another object of the present invention to provide an electromagnetically shielded inductor assembly having an openable induction coil that can be easily inserted or removed from the electromagnetically shielded enclosure, and can be opened while the induction coil is in the electromagnetically shielded enclosure without complete disassembly of the enclosure.
It is another object of the present invention to provide an electromagnetically shielded inductor assembly having an openable induction coil that can be provided with a static or dynamic seal between the interface regions of the openable induction coil and the electromagnetically shielded inductor assembly so that a gastight seal can easily be maintained between the induction coil and the electromagnetic shield inductor assembly when the induction coil is in the closed position while maintaining an efficient method of opening and re-closing the induction coil without resealing of the seal.
It is another object to the present invention to provide apparatus and a method of injecting a gas into an induction furnace having an openable induction coil as an improvement to the disclosure of Japanese patent publication JP 63-4873.
In one aspect the present invention is an openable induction coil that can be swung open to allow maintenance of the induction coil.
In another aspect the present invention is an electromagnetically shielded inductor assembly comprising an openable induction coil removably inserted into an electromagnetically shielding enclosure. The coil can be pivoted open while in the shielding enclosure with only partial disassembly of the shielding enclosure. In some examples of the invention, a dynamic “curtain” of a gas is injected through spaces between opening portions of the coil and adjacent sections of the shielding enclosure into the interior of the induction furnace formed by the openable induction coil when it is in the closed position.
The above and other aspects of the invention are set forth in this specification and the appended claims.
For the purpose of illustrating the invention, there is shown in the drawings a form that is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
a) is a cross sectional view of the openable induction coil shown in
b) is a cross sectional view of the openable induction coil shown in
a) is an isometric view of one example of an electromagnetically shielded inductor assembly of the present invention.
b) is an isometric view of the electromagnetically shielded inductor assembly shown in
c) is an isometric view of the electromagnetically shielded enclosure shown in
d) is a cross sectional view of the electromagnetically shielded enclosure shown in
a) is a cross sectional view of the electromagnetically shielded inductor assembly shown in
b) is a cross sectional view of the electromagnetically shielded inductor assembly shown in
a) is a cross sectional view of the electromagnetically shielded inductor assembly shown in
b) is a cross sectional view of the electromagnetically shielded inductor assembly shown in
a) is a partial top plan view of one example of a gas (air) curtain used with the electromagnetically shielded inductor assembly shown in
b) is a partial cross sectional side elevation of the example of the air curtain arrangement shown in
c) is a partial cross sectional side elevation of another example of an air curtain arrangement used with the electromagnetically shielded inductor assembly shown in
d) is a side elevation view of the air curtain gas distribution plenum shown in
e) is a cross sectional elevation view of another air curtain distribution plenum used with the electromagnetically shielded inductor assembly shown in
a) is a partial top plan view of one example of a gas (air) curtain used with the electromagnetically shielded inductor assembly shown in
b) is a partial cross sectional side elevation of the example of the air curtain arrangement shown in
c) is a partial cross sectional side elevation of another example of an air curtain arrangement used with the electromagnetically shielded assembly in
d) is a side elevation view of the air curtain gas distribution plenum shown in
e) is a cross sectional elevation view of another air curtain distribution plenum used with the electromagnetically shielded inductor assembly shown in
a) is an isometric view of one example of an electromagnetically shielded inductor assembly of the present invention oriented for induction heating of a strip material moving in the vertical direction through the openable induction coil.
b) is a cross sectional view of the electromagnetically shielded inductor assembly through line G-G in
a) is one example of an arrangement of multiple openable induction coils of the present invention and the supply of alternating current to the multiple openable induction coils.
b) illustrates one example of the use of distributed tank capacitive elements with an openable induction coil of the present invention.
c) is one example of an arrangement of an electromagnetically shielded inductor assembly of the present invention and the supply of alternating current to the multiple openable induction coils used in the electromagnetically shielded inductor assembly.
a) and
As shown in
In this example induction coil section 12c, which effectively represents the height, zh, (
One non-limiting method of providing the pivoting axes is illustrated in
One example of supplying alternating current to induction coil 12 is shown in
a) illustrates one example of the electromagnetically shielded inductor assembly 10 of the present invention wherein openable box-like induction coil 12 is disposed within box-like electromagnetically shielded enclosure 14. In accompanying
In this example of the invention electromagnetically shielded enclosure 14 comprises box-like outer electrically conducting structure formed from longitudinal (relative to orientation of workpiece W) sides 14a, 14b, 14c and 14d; transverse (relative to orientation of workpiece W) entry 14e and exit 14f sides; and box-like inner workpiece entry passage 14g and workpiece exit passage 14h. In a particular oriented example of the present invention, side 14a may be referred to as the bottom of enclosure 14; side 14b may be referred to as the top of the enclosure; side 14c may be referred to as the right side of the enclosure; and side 14d may be referred to as the left side of the enclosure. Side 14a through 14f are formed from any suitable electrically conductive material either in solid or other form, such as a mesh. Box-like inner workpiece entry passage 14g and exit passage 14h form a closed entry path to, and closed exit path from, the interior of the induction furnace to the exterior of the electromagnetically shield enclosure and may be formed from a suitable non-electrically conductive material. While workpiece entry passage 14g and workpiece exit passage 14h are shown as closed rectangularly box structures, in other examples of the invention they may be of other shapes as long as they provide a closed workpiece entry passage from entry side 14e of enclosure 14 to the entrance of the induction furnace, and a closed workpiece exit passage from the exit of the induction furnace to exit side 14f of enclosure 14, except for spaces, S, as further described below.
As seen for example in
Workpiece W moves through electromagnetically shielded inductor assembly 10 in an interior volume defined by the interior of the induction furnace and the interiors of workpiece entry and exit passages 14g and 14h of enclosure 14. Assembly 10 comprises openable induction coil 12 and enclosure 14. With this configuration the enclosure forms an electromagnetically shielding box structure around the openable induction coil.
As shown in
Suitable locking apparatus can be provided so that when induction coil 12 is in the closed position sufficient contact is maintained between the opposing edges of coil subsections 12a′ and 12b′ so that electrical continuity is maintained across the opposing edges of the two coil subsections at joint 12j as shown, for example, in
As shown in the above examples of the invention, when the openable induction coil is in the closed position, an open space S, or gap, exists at least between the inner perimeters of fixed top section and bottom sections of inner workpiece entry passage 14g and exit passage 14h, and the respective opposing outer perimeters of top section 12b and bottom section 12a of the openable induction coil in
Alternatively a flow of gas may be injected through each space S into the interior of the induction furnace from a dynamic gaseous (air) curtain across each space S when the openable induction coil is in the closed position.
Similarly for the example of the invention utilizing non-magnetic and non-electrically conductive refractory 16a, 16b, and 16c as shown in
a) and
In some applications a longer length, L, of the openable induction coil is preferred to ensure that the strip material is gradually heated over a longer longitudinal distance of the strip, as opposed to rapid heating with a shorter length of an openable induction coil.
c) illustrates another example of the present invention where the two openable coils 12′ and 12″ are installed in a common electromagnetically shielded enclosure 14 as previously described above.
While two inverters are shown in
In other examples of the invention, at least one induction coil section, such as section 14a and/or 14b shown in the above examples, can be formed from a flexible material and attached to actuators 68 for flexing the coils as disclosed in US Patent Publication No. 2007/0187395 A1 and as shown in
While the induction coil utilized in the above examples of the invention is a single turn coil, other different configurations of induction coils may be used may be used in other examples of the invention.
While top, bottom and side terminology is used in some of the above examples of the invention, other orientations of the electromagnetically shielded inductor assembly of the present invention can be used, and such terminology is not limiting to application of the invention.
The present invention has been described in terms of preferred examples and embodiments. Equivalents, alternatives and modifications, aside from those expressly stated, are possible and within the scope of the invention.
This application claims the benefit of U.S. Provisional Application No. 61/100,739, filed Sep. 28, 2008, hereby incorporated by reference in its entirety.
Number | Date | Country | |
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61100739 | Sep 2008 | US |