Electric heating – Inductive heating – Specific heating application
Reexamination Certificate
2000-05-15
2001-07-03
Leung, Philip H. (Department: 3742)
Electric heating
Inductive heating
Specific heating application
C219S645000, C219S670000, C219S672000, C219S677000, C148S568000, C266S129000
Reexamination Certificate
active
06255634
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to inductive heating, and more particularly, to a transverse flux heating coil having a single loop conductive heating element for heating a continuous run of wire therethrough.
The concept of transverse flux induction heating is well known. Typically, such heaters are used to heat strips of thin metal and have two inductor elements, each containing induction coils are arranged in a spaced, parallel relation. The metal strip to be heated is positioned between the two elements and on energizing the coils, magnetic flux is generated from current passing through the two inductor elements and passes through the strip perpendicular to its flat surfaces. This causes induced currents to circulate in the plane of the metal strip material to be heated and thereby causes the temperature in the metal strip to rise. Uniform heating is achieved when the strip is moved at a given speed between the two elements. Transverse flux induction heating operates at relatively high electrical frequencies which are chosen based on the thickness and properties of the metal strip to provide more efficient heating. Transverse flux-type induction coils are commonly used to heat such thin metal strips. Typically, in this type of an arrangement, a plurality of coils are placed adjacent one or both sides of the strip to be heated, and the strip is heated as it is conveyed past the coils. However, these types of induction heaters use an inordinate number of components, are difficult to impedance match with the power supply, and are therefore generally more costly to manufacture.
Where the work piece is a continuous run of wire, the prior art induction heaters use a plurality of coils wrapped around a heating area in which the wire is run through. To create a heating area of sufficient length to heat a wire run adequately at high speeds, the coil is wound about the heating area a number of times until a sufficient length is achieved. The current flowing through these solenoid-type coils causes flux generation in all directions around each turn of the coil. That is, as current travels through the turns of the inductor, flux is generated along the current path in a direction according to the well known right-hand rule. Using multiple turns of a coil thereby causes flux generation outwardly about the entire circumference of each turn of the coil, which results in a majority of the flux generated being other than transverse to the work piece, which in turn greatly reduces the efficiency of such solenoid coils.
It would therefore be advantageous and desirable to create a more efficient induction heating coil in which an increased amount of flux is directed into the heating area, and it would be additionally advantageous to provide therewith a means for simultaneously cooling the conductors of the heating coil.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for inductively heating a continuous run of wire and a method of using the apparatus that overcomes the aforementioned problems.
In accordance with one aspect of the invention, a transverse flux heating coil is disclosed that includes a single loop conductive element having a pair of termination ends extending from the single loop and connectable to a power supply to supply current to the conductive element. The single loop conductive element is constructed to distribute a majority of the current from the power supply across a width of the conductive element that defines the side walls of an internal heating area, wherein the continuous run of wire is fed therethrough at relatively high speeds. The current is relatively evenly distributed across the width of the conductive element and creates a flux that is transverse to the direction of travel of the continuous run of wire to evenly heat the wire as it travels through the internal heating area.
In accordance with another aspect of the invention, a transverse flux heating coil is disclosed having first and second conductors that are comprised of substantially planar bar stock, which in a preferred embodiment, is a relatively thin piece of solid copper material, but is thick enough to absorb and transfer heat without warping. The first and second conductors therefore have a width that is substantially greater than a thickness and are arranged parallel to one another to form the sides of an internal heating area. A third conductor is provided to connect the first and second conductors to form a continuous conductive path. However, the third conductor is arranged at one end of the transverse flux heating coil to provide travel of the work piece parallel with the first and second conductors through the transverse flux heating coil.
In a preferred embodiment, the third conductor also serves as a coolant path. In this manner, a coolant tube is attached to the first and second conductors to transfer heat from the transverse flux heating coil through a coolant medium while simultaneously conducting current from one of the first and second conductors to the other. Alternatively, the first, second, and third conductors could include a contiguous section of planar stock material provided with an opening to allow travel of the work piece therethrough, with an alternative cooling means.
In accordance with yet another aspect of the invention, an inductive heater for efficiently heating a continuous run of wire includes a single-turn transverse flux heating coil having a pair of planar conductors substantially parallel with one another and a conductive cooling tube attached to each of the pair of planar conductors to transfer heat from the single-turn transverse flux heating coil and also simultaneously conduct current from one of the conductors to the other. A power supply is provided to supply current to the single-turn transverse flux heating coil and an induction heating control is connected to the power supply to inductively heat the continuous run of wire. When in operation, current from the power supply travels through the single-turn transverse flux heating coil and causes flux generation that is transverse to a direction of travel of a continuous run of wire through the inductive heater.
The present invention has been simulated with finite element magnetic field software and found to provide efficiency greater than 50%, and upwards of 60%. This level of efficiency is achieved by using a solid planar surface as the conductive medium in the heating area to evenly distribute current across side walls of the heating area. By keeping the current evenly distributed across a relatively thin solid, planar conductor, the flux generated can be more focused into the heating area and heat the traveling work piece faster and more efficiently than prior art systems and methods.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.
REFERENCES:
patent: 2935589 (1960-05-01), Baer et al.
patent: 3251976 (1966-05-01), McBrien
patent: 3631524 (1971-12-01), Denner
patent: 3665138 (1972-05-01), Edge et al.
patent: 3689727 (1972-09-01), Morris
patent: 3699302 (1972-10-01), Griffith
patent: 3842234 (1974-10-01), Seyfried
patent: 4054770 (1977-10-01), Jackson et al.
patent: 4258241 (1981-03-01), Soworowski
patent: 4300031 (1981-11-01), Reboux et al.
patent: 4554966 (1985-11-01), Vasiliev et al.
patent: 4585916 (1986-04-01), Rich
patent: 4751360 (1988-06-01), Ross
patent: 4788396 (1988-11-01), Maugein et al.
patent: 4853510 (1989-08-01), Mohr et al.
patent: 4972042 (1990-11-01), Seabourne et al.
patent: 5214258 (1993-05-01), Akers
patent: 5317121 (1994-05-01), Katayama et al.
patent: 5345065 (1994-09-01), Reinke et al.
patent: 5378879 (1995-01-01), Monovoukas
patent: 5403994 (1995-04-01), Havas et al.
patent: 5495094 (1996-02-01), Rowan et al.
patent: 5630958 (1997-05-01), Stewart, Jr. et al.
patent: 5837976 (1998-11-01), Loveless et al.
Cook & Franke S.C.
Leung Philip H.
Pillar Industries
Ziolkowski Timothy J.
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