AU2013407780A1

AU2013407780A1 - Induction heater

Info

Publication number: AU2013407780A1
Application number: AU2013407780A
Authority: AU
Inventors: Tetsuji Doizaki
Original assignee: Toshiba Mitsubishi Electric Industrial Systems Corp
Current assignee: Toshiba Mitsubishi Electric Industrial Systems Corp
Priority date: 2013-12-13
Filing date: 2013-12-13
Publication date: 2016-06-30
Anticipated expiration: 2033-12-13
Also published as: KR101864974B1; KR20160089416A; WO2015087373A1; JP6077676B2; TWI592060B; TW201524270A; JPWO2015087373A1; CN105745993B; AU2013407780B2; CN105745993A

Abstract

An induction heater in which a pair of fixed U-shaped inductors are laid out on the widthwise ends of a target material being heated. Each of said fixed U-shaped inductors comprises two inductor heads and a U-shaped core structure, and each inductor head comprises the following: a main core structure comprising a main core and non-magnetic main-core backing plates that support said main core from the sides, protruding core structures each comprising a protruding core and non-magnetic protruding-core backing plates that support said protruding core, and a heating coil that heats the abovementioned target material by linking magnetic flux thereto. The width of each protruding core in the direction in which the target material is conveyed is enough to ensure, for materials having a range of widths from narrow to wide, an overlap width greater than or equal to an edge heating width. The U-shaped core structure comprises a U-shaped core and non-magnetic U-shaped-core backing plates that support said U-shaped core from the sides.

Description

DESCRIPTION

INDUCTION HEATING DEVICE

TECHNICAL FIELD

[0001]

The present invention relates to an induction heating device of a C-shaped inductor type.

BACKGROUND ART

[0002]

In order to heat a rolled material on a hot rolling line or any other to-be-heated material, an induction heating device has been used. One pair of C-shaped inductors have been used to heat both end portions of the to-be-heated material whose temperatures are lower than a central portion of the to-be-heated material.

[0003]

The C-shaped inductor-type induction heating device employs an inductor shape of a heating width with a short iron core depth so that only narrow areas of the end portions of the to-be-heated material are heated. A movable C-shaped inductor of this type includes one pair of C-shaped inductor movable carriers, a motor control device, a position detector, and a control device in order to align the heating position with positions of the end portion with various kinds of plate width.

[0004]

The movable C-shaped inductor induction heating device cannot heat when the carrier is moving, because the movable carrier of the C-shaped inductor moves each time the width of material changes. Accordingly, in the case of a continuous material, there is concern that an unheated portion could appear on the to-be-heated material when the carrier is moving.

[0005]

Moreover, at a time when the to-be-heated material is being transferred, the material could shift laterally. Depending on the amount of shift of the to-be-heated material, the heating lap width of the C-shaped inductor changes. This causes a difference between the left and right inductors in terms of electric power for heating, possibly leading to an abnormal heating that leaves temperatures of the left and right end portions of the to-be-heated material uneven.

[0006]

Moreover, an accident could occur in which the transport material hit and damage heating coils and open-leg iron cores.

CITATION LIST PATENT LITERATURE

[0007]

Patent Literature 1: Japanese Patent No. 4,739,792 Patent Literature 2: Japanese Patent No. 3,156,746 Patent Literature 3: Japanese Utility Model Registration No. 2,576,932

SUMMARY OF INVENTION TECHNICAL PROBLEM

[0008]

In the conventional movable C-shaped inductor, an opening through which the to-be-heated material passes is narrow.

Therefore, there is no space for replacement of the heating coils and open-leg iron cores. As a result, the entire movable C-shaped inductor is replaced. The costs of replacement parts, as well as labor costs, are expensive, and a long time is required for the replacement. Furthermore, a movable mechanism, a control device, and adjustment expenses are required, and the prices of devices are high.

[0009]

The present invention therefore has been made to solve the above problems, and is intended to provide a highly efficient, inexpensive induction heating device that: does not cause an unheated portion even if the width of material has changed; does not cause an abnormal heating that leaves the left and right end portions of the material uneven in temperature even if the material has shifted; can reduce the time needed to replace the inductor; and can lower the prices of devices such as the movable mechanism and the control device.

SOLUTION TO PROBLEM

[0010]

According to one aspect of the present invention, in an induction heating device in which a pair of fixed C-shaped inductors are disposed in both width-direction end portions of a to-be-heated material, the fixed C-shaped inductor includes two inductor heads and one C-shaped iron core structure; the inductor head includes a body iron core structure that includes a body iron core and a non-magnetic body iron core back plate, which supports the body iron core from a side face, an open-leg iron core structure that includes an open-leg iron core, which has an iron core width to secure an iron core lap width that is equal to or greater than an end-portion heat width that covers a narrow material and a wide material along a transport direction of the to-be-heated material, and a non-magnetic open-leg iron core back plate, which supports the open-leg iron core, and a heating coil that heats the to-be-heated material by interlinking a magnetic flux with the to-be-heated material; and the C-shaped iron core structure includes a C-shaped iron core and a non-magnetic metal C-shaped iron core back plate, which supports the C-shaped iron core from a side face.

ADVANTAGEOUS EFFECTS OF INVENTION

[0011]

The present invention can realize a highly efficient, inexpensive induction heating device that: does not cause an unheated portion even if the width of material has changed; does not cause an abnormal heating that leaves the left and right end portions of the material uneven in temperature even if the material has shifted; can reduce the time needed to replace the inductor; and can lower the prices of devices such as the movable mechanism and the control device.

BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1 is a schematic diagram showing the overall configuration of an induction heating device according to an embodiment of the present invention. FIG. 2 is a diagram for explaining dimensional relations between parts of an open-leg iron core. FIG. 3 is a schematic diagram showing the overall configuration of an induction heating device according to a second embodiment. FIG. 4 is a schematic diagram showing the overall configuration of an induction heating device according to a third embodiment. FIG. 5 is a diagram for explaining a comparison between a heating temperature distribution of a conventional movable C-shaped inductor and that of a fixed C-shaped inductor 12 of the third embodiment.

DESCRIPTION OF EMBODIMENTS

[0013]

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Incidentally, in each diagram, the same parts are denoted by the same reference symbols.

[0014] (First Embodiment) FIG. 1 is a schematic diagram showing the overall configuration of an induction heating device according to an embodiment of the present invention. The induction heating device of the present embodiment includes two pairs of fixed C-shaped inductors 12, which each are placed on the left and right sides in such a way as to secure an installation space of depth width WC3 of one pair of open-leg iron cores. As shown in FIG. 1, the induction heating device of the embodiment of the present invention mainly includes a body iron core structure 1, an open-leg iron core structure 2, and fixed C-shaped inductors 12.

[0015]

The body iron core structure 1 includes a body iron core 1A; and a non-magnetic body iron core back plate IB, which supports the body iron core 1A from a side face thereof.

[0016]

The open-leg iron core structure 2 includes an open-leg iron core 2A, which can heat a range of materials from a narrow material 7 to a wide material 8; and a non-magnetic open-leg iron core back plate 2B, which supports the open-leg iron core 2A. The open-leg iron core 2A and the open-leg iron core back plate 2B are stacked in a direction perpendicular to a heating coil 3, and a heating loss of the heating coil 3 and open-leg iron core 2A is reduced. The non-magnetic open-leg iron core back plate 2B is disposed on the outer side of a side face of the open-leg iron core 2A, which is parallel to the heating coil 3. The non-magnetic open-leg iron core back plate 2B supports the iron core, while preventing an area near the open-leg iron core 2A from being heated. As shown in FIG. 1, the open-leg iron core 2A has an open-leg iron core depth width WC1 to secure an iron core lap width that is greater than or equal to an end portion heating width WH1, from the narrow material 7 to the wide material 8.

[0017]

The fixed C-shaped inductor 12 includes two inductor heads 12A and one C-shaped iron core structure 4.

[0018] A pair of the C-shaped inductors 12 of the present embodiment are disposed in both width-direction end portions of a to-be-heated material; magnetic flux φ generated from the heating coil 3 is interlinked with the to-be-heated material, causing eddy current I to flow. In response, Joule heat is generated due to the resistance of the to-be-heated material, and heats both end portions of the to-be-heated material. According to the present embodiment, without the need to move the C-shaped inductor 12 in the width direction of the to-be-heated material, the end portions of a range of to-be-heated materials, from a narrow one to a wide one, can be heated.

[0019]

The inductor head 12A includes the body iron core structure 1, the open-leg iron core structure 2, and the heating coil 3.

[0020]

The C-shaped iron core structure 4 includes a C-shaped iron core 4A and a non-magnetic C-shaped iron core back plate 4B, which supports the C-shaped iron core 4A from a side face thereof. The C-shaped iron core back plate 4B holds the C-shaped iron core 4A and secures insulation. The C-shaped iron core back plate 4B is preferably made of stainless steel or copper, for example. The stainless steel is high in strength and has a shielding effect, while copper itself engages in induction heating.

[0021] FIG. 2 is a diagram for explaining dimensional relations between parts of an open-leg iron core. As shown in FIGS. 1 and 2, without the need to move the inductor heads 12A, the end portions of a range of materials, from a narrow to a wide one, can be heated. The heating width of the end portions are determined based on users' specifications. For example, the temperature rise range is of about 25 degrees Celsius to 100 degrees Celsius.

[0022]

The open-leg iron core depth width WC1 and a pair of iron core space widths WC2 are determined based on narrow material plate width Wl, wide material plate width W2, and end portion heating width WH1, as described below.

[0023] (1) Open-leg iron core depth width WC1 = (Pair of open-leg iron core depth widths WC3 - Pair of open-leg iron core space widths WC2)/2 (2) Narrow material lap size WW1 = (Narrow material plate width Wl - Pair of open-leg iron core depth widths WC3)/2 > End portion heating width WH1 (3) Wide material lap size WW2 = (Wide material plate width W2 - Pair of open-leg iron core depth widths WC3)/2 > End portion heating width WH1

Moreover, the C-shaped inductor 12 of the present embodiment includes the open-leg iron core 2A and the open-leg iron core back plate 2B, which are stacked in a direction perpendicular to the heating coil 3 . This structure reduces a heating loss of the heating coil 3 and open-leg iron cores 2A.

[0024]

As described above, in the case of the present embodiment, for the maximum plate width and minimum plate width of the to-be-heated materials, the dimensions of the iron cores are managed to give some leeway.

[0025]

According to the present embodiment, even when the width of the material has changed, an unheated portion does not emerge . Even if the material has shifted, an abnormal heating that leaves the left and right end portions of the material uneven in temperature does not occur. Furthermore, the open-leg iron core structure 2, body iron core structure 1 and heating coil 3, which are frequently replaced, are bundled together into a structure of the inductor head 12A. Furthermore, the fixed C-shaped inductor 12 includes the two inductor heads 12A and one C-shaped iron core structure 4, which are frequently replaced. The present embodiment employs a configuration that makes it easier to replace a damaged portion. Therefore, the time needed to replace the inductors can be reduced.

[0026] (Second Embodiment) A second embodiment will be described. According to the second embodiment, a fixed C-shaped inductor can be separated.

[0027] FIG. 3 is a schematic diagram showing the overall configuration of an induction heating device according to the second embodiment. As shown in FIG. 3, a fixed C-shaped inductor 12 of the second embodiment includes a body iron core separation mechanism 5 in which an inductor head 12A with a L-shaped iron core back plate and a C-shaped iron core structure 4 with a L-shaped iron core back plate are put together and the L-shaped portions are fastened with bolts 14 and nuts 15 in a separable manner. The position where the above members are put together, or where the above members can be separated, is preferably at a point where the magnetic flux flowing through a C-shaped inductor 12 is constant.

[0028]

In the fixed C-shaped inductor 12 of the second embodiment, the inductor head 12A can be easily replaced by loosening the bolts 14 of the L-shaped portions and removing the inductor head 12A from the fixed C-shaped inductor 12. Therefore, it is possible to drastically reduce the time and costs for maintenance.

[0029]

According to the second embodiment, a to-be-replaced portion of the inductor can be replaced more easily for a short period of time .

[0030] (Third Embodiment) A third embodiment will be described. According to the third embodiment, two sets of fixed inductors are disposed in parallel in such a way that the direction of the magnetic flux of a left inductor is aligned with the direction of the magnetic flux of a right inductor, and are connected to one AC induction heating power source .

[0031] FIG. 4 is a schematic diagram showing the overall configuration of an induction heating device according to the third embodiment. As shown in FIG. 4, in a fixed C-shaped inductor 12 of the third embodiment, to an AC induction heating power source 9, four heating coils 3 are connected through wires, and are connected in such a way that current 10 flows in the same direction.

[0032]

The material lap size varies from narrow material lap size WW1 to wide material lap size WW2. The narrow material lap size WW1 is designed to be larger than end-portion heating width WH1.

[0033]

The directions of magnetic fluxes 11 generated from the four heating coils 3, or from the upper, lower, left and right heating coils, are aligned in the same direction. Accordingly, induced current 16, which flows through a to-be-heated material, flows across the entire plate width direction, and especially creates one large flow of current, which mainly flows through both ends of the to-be-heated material.

[0034] FIG. 5 is a diagram for explaining a comparison between a heating temperature distribution of a conventional movable C-shaped inductor and that of a fixed C-shaped inductor 12 of the third embodiment. As shown in FIG. 5, in the case of a temperature rise curve of the conventional movable C-shaped inductor, since the to-be-heated material and the lap size are constant, the central portion of the to-be-heated material is not heated, and only the end portions of the to-be-heated material are heated. Moreover, the heating width W1 of the end portions are constant.

[0035]

Meanwhile, in the case of the fixed C-shaped inductor 12 of the third embodiment, if the width is changed from narrow material width W1 to wide material width W2, the end portions of the material are intensively heated with narrow material lap size WW1, because induced current 9 is of sufficiently-long open-leg iron core depth width WC1; and it is possible to secure end-portion heating width WH1 by which the central portion of the material, too, is heated.

[0036]

The fixed C-shaped inductor 12 of the third embodiment aligns, in the same direction, the magnetic fluxes 11 generated from the four heating coils 3, or from the upper, lower, left and right heating coils. Therefore, the induced current 16 flows across the entire plate width direction of the to-be-heated material, and intensively flows through both ends of the to-be-heated material in particular, and realizes a gentle temperature rise curve by which end-portion heating width WH1 is secured while the central portion of the to-be-heated material is being heated, thereby resulting in an improvement in heating efficiency. Moreover, even if the material has shifted, the heating lap width of the C-shaped inductor 12 does not change significantly. Therefore, no significant difference emerges in the heating power for the left and right inductors. As a result, this configuration reduces the occurrence of an abnormal heating stemming from uneven temperatures in the left and right end portions of the to-be-heated material.

[0037]

According to the embodiment of the present invention, even if the width of the material has changed, an unheated portion does not emerge. Even if the material has shifted, an abnormal heating stemming from uneven temperatures in the left and right material end portions does not occur, and the time needed to replace inductors is reduced, and a highly-efficient, inexpensive induction heating device that keeps low the prices of such devices as the movable mechanism and the control device can be realized.

[0038]

While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. The novel embodiments described herein may be embodied in a variety of other forms; various omissions, substitutions and changes may be made without departing from the spirit of the invention. The above-described embodiments and variants thereof are within the scope and spirit of the invention, and are within the scope of the invention defined in the appended claims and the range of equivalency thereof.

REFERENCE SIGNS LIST

[0039] 1: Body iron core structure 1A: Body iron core IB: Body iron core back plate 2: Open-leg iron core structure 2A: Open-leg iron core 2B: Open-leg iron core back plate 3: Heating coil 4: C-shaped iron core structure 4A: C-shaped iron core 4B: C-shaped iron core back plate 5: Body iron core separation mechanism 6: Bus bar 7: Wide plate material 8: Narrow plate material 9: AC induction heating power source 10: Current 11: Magnetic flux W1: Narrow material plate width W2: Wide material plate width WW1: Narrow material lap size WW2: Wide material lap size WC1: Open-leg iron core depth width WC2: One-pair open-leg iron core space width WC3: One-pair open-leg iron core depth width WH1: End-portion heating width 12: Fixed C-shaped inductor 12A: Inductor head 13: Movable C-shaped inductor 14: Bolt 15: Nut

Claims

1. An induction heating device in which a pair of fixed C-shaped inductors are disposed in both width-direction end portions of a to-be-heated material, characterized in that: the fixed C-shaped inductor includes two inductor heads and one C-shaped iron core structure; the inductor head includes a body iron core structure that includes a body iron core and a non-magnetic body iron core back plate, which supports the body iron core from a side face, an open-leg iron core structure that includes an open-leg iron core, which has an iron core width to secure an iron core lap width that is equal to or greater than an end-portion heat width that covers a narrow material and a wide material along a transport direction of the to-be-heated material, and a non-magnetic open-leg iron core back plate, which supports the open-leg iron core, and a heating coil that heats the to-be-heated material by interlinking a magnetic flux with the to-be-heated material; and the C-shaped iron core structure includes a C-shaped iron core and a non-magnetic metal C-shaped iron core back plate, which supports the C-shaped iron core from a side face.

2. The induction heating device according to claim 1, characterized in that dimensional relations between parts of the open-leg iron core are set in such a way that, without moving the inductor head, end portions of the to-be-heated materials, ranging from a narrow to a wide material, can be heated.

3. The induction heating device according to claim 1 or 2, characterized in that the non-magnetic body iron core back plate is made of stainless steel or copper.

4. The induction heating device according to any one of claims 1 to 3, characterized in that the non-magnetic open-leg iron core back plate is made of stainless steel or copper.

5. The induction heating device according to any one of claims 1 to 4, characterized in that the open-leg iron core and the open-leg iron core back pate are stacked in a direction perpendicular to the heating coil.

6. The induction heating device according to claim 1, characterized in that: a body iron core back plate of the inductor head is a L-shaped body iron core back plate; a C-shaped iron core back plate of the C-shaped iron core structure is a L-shaped back plate for the C-shaped iron core; and what is provided is a body iron core separation mechanism in which the certain inductor head and the C-shaped iron core structure are put together with the L-shaped portions being fixed and can be separated.

7. The induction heating device according to claim 6, characterized in that a position where the parts are put together and can be separated is at a point where a magnetic flux flowing through the fixed C-shaped inductor 12 is constant.

8. The induction heating device according to claim 6, characterized in that the L-shaped portions are fixed with bolts and nuts.

9. The induction heating device according to claim 1, characterized in that two sets of the fixed C-shaped inductors, in which the pair of heating coils are wound in the same direction and magnetic fluxes of the pair of inductors are aligned in the same direction, are disposed in parallel, and are connected to one AC induction heating power source.