JP6623555B2 - Induction heating device - Google Patents

Description

  The present invention relates to an induction heating device.

  For example, as disclosed in Patent Document 1, an induction heating device (induction heater, IH) for induction heating a steel pipe is known. Such an induction heating device includes a coil for induction heating a steel pipe. Then, the induction heating device generates an induction current in the steel pipe by flowing an alternating current to the coil when the steel pipe passes through the coil. Thereby, the steel pipe is heated.

JP 2010-255031 A

  By the way, the induction heating apparatus has a problem that the heating efficiency of the steel pipe is reduced when the gap (air gap) between the coil and the steel pipe is increased. For this reason, in the related art, when the outer diameter of the steel pipe changes, the operation is temporarily stopped, and the coil in the induction heating device is replaced with a coil corresponding to the outer diameter of the steel pipe. However, in this method, it is necessary to temporarily stop the operation, so that there is a problem that the production amount of the steel pipe is reduced. Further, there is a problem that the labor required for the coil replacement operation increases because the coil replacement operation frequently occurs. Further, it was necessary to prepare a plurality of types of replacement coils. Therefore, there is also a problem that operation costs (for example, labor costs required for coil replacement work, costs required for preparation and management of replacement coils, etc.) are increased.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to suppress the decrease in the production amount and the increase in operating costs of a tubular body (for example, a steel pipe) while heating the tubular body. An object of the present invention is to provide a new and improved induction heating device capable of improving efficiency.

According to an embodiment of the present invention, there is provided a plurality of ring-shaped coils for induction-heating a tubular body capable of induction heating, wherein each of the ring-shaped coils passes through a center point of the ring-shaped coil. And, it is rotatable about an axis perpendicular to the central axis of the tubular body as a rotation axis, the ring-shaped coil is movable in a direction along the rotation axis, and the plurality of ring-shaped coils are arranged along a rotation axis. A first ring-shaped coil movable in a first direction, and a second ring-shaped coil movable in a second direction opposite to the first direction, the first ring-shaped coil; The two ring-shaped coils are arranged alternately along the central axis of the tubular body, and a first air gap generated between the first ring-shaped coil and the tubular body in a direction along the rotation axis; Formed between the second ring-shaped coil in the axial direction and the tubular body The second air gap is substantially the same as a third air gap generated between a position where the first ring-shaped coil and the second ring-shaped coil intersect in the central axis direction of the tubular body and the tubular body. An induction heating device is further provided, further comprising a driving device for bringing the first ring-shaped coil and the second ring-shaped coil close to the tubular body .

  Further, the number of the first ring-shaped coils may correspond to the number of the second ring-shaped coils.

  Further, the tubular body may be a steel pipe.

  According to the above aspect, by rotating the ring-shaped coil, the air gap between the ring-shaped coil and the tubular body can be reduced. Therefore, the heating efficiency of the tubular body is improved. Further, according to the above aspect, since the rotation angle of the ring-shaped coil can be adjusted according to the outer diameter of the tubular body, the outer diameter range of the tubular body that can be accommodated by the ring-shaped coil is greatly expanded. Therefore, the number of times of replacing the ring-shaped coil can be greatly reduced, and the number of times of stopping the operation using the induction heating device can be significantly reduced. Further, the labor cost required for replacing the ring-shaped coil is greatly reduced. Further, the number of replacement ring-shaped coils is greatly reduced. Therefore, it is possible to suppress a decrease in the production amount of the tubular body and an increase in the operating cost.

  As described above, according to the present invention, it is possible to improve the heating efficiency of the tubular body while suppressing a decrease in the production amount of the tubular body and an increase in the operating cost.

It is a perspective view showing signs that a steel pipe passes inside a ring-shaped coil concerning an embodiment of the present invention. It is a perspective view showing the state where the opening face of the ring-shaped coil was perpendicular to the central axis of the steel pipe. It is a perspective view showing the state where the opening face of the ring-shaped coil was inclined to the central axis of the steel pipe. It is a front view which shows the positional relationship of the ring-shaped coil and the steel pipe which passes through the said ring-shaped coil. It is a front view which shows the positional relationship of the ring-shaped coil and the steel pipe which passes through the said ring-shaped coil. It is a perspective view which shows a mode that a steel pipe passes through the inside of the ring-shaped coil from which the connection position of a coil terminal differs mutually. It is a front view which shows the positional relationship of the ring-shaped coil which concerns on the 1st modification of this embodiment, and the steel pipe which passes through the said ring-shaped coil. It is a front view which shows the positional relationship of the ring-shaped coil which concerns on the 2nd modification of this embodiment, and the steel pipe which passes through the said ring-shaped coil. It is a front view which shows the positional relationship of the ring-shaped coil which concerns on the 3rd modification of this embodiment, and the steel pipe which passes through the said ring-shaped coil.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<1. Configuration of induction heating device>
First, the configuration of the induction heating device according to the present embodiment will be described with reference to FIGS. As shown in FIG. 1, the induction heating device 10 includes a plurality of ring-shaped coils 21, a coil terminal 22 connected to each ring-shaped coil 21, a power supply device, and a driving device. The illustration of the power supply device and the drive device is omitted.

  The plurality of ring-shaped coils 21 heat the steel pipe P by induction. The ring-shaped coil 21 is a coil manufactured by winding, for example, about 1 to 3 turns of a coil wire. The number of turns of the coil wire may be larger. However, if the number of windings is too large, the variation in the upper and lower air gaps L4 (see FIG. 4) when the ring-shaped coil 21 is rotated may increase. For example, at both ends in the width direction of the ring-shaped coil 21, the air gap L4 generated above the steel pipe P may be much larger (or smaller) than the air gap L4 generated below the steel pipe P. If the variation in the upper and lower air gaps L4 is large, uneven heating may occur. From such a viewpoint, the number of turns of the coil wire is preferably less than 10, more preferably 3 or less. In addition, what is necessary is just to use the same thing as the coil wire used for the coil of the conventional induction heating apparatus.

  The ring-shaped coils 21 are arranged such that the center points Q are aligned on the same straight line. Further, the opening surfaces are parallel to each other. The steel pipe P is transported in the transport direction P1 along the central axis L1 of the steel pipe P. Then, the steel pipe P passes through the inside of the ring-shaped coil 21. Here, the central axis L1 of the steel pipe P passes through the central point Q of the ring-shaped coil P. Then, the power supply device supplies an alternating current to the ring-shaped coil 21 when the steel pipe P passes through the inside of the ring-shaped coil 21. As a result, an induced current is generated in the steel pipe P, and the steel pipe P is heated. In addition, the size of the steel pipe P, for example, the outer diameter or the like is not particularly limited. However, when the outer diameter of the steel pipe P is 100 mm or more, a decrease in the heating efficiency due to an increase in the air gap increases. Therefore, when the outer diameter of the steel pipe P is 100 mm or more, the effect of the present embodiment is further enhanced. Here, the “heating efficiency” means a heating amount with respect to the input power.

  Further, as shown in FIG. 1 to FIG. 3, the ring-shaped coil 21 passes through the center point Q of the ring-shaped coil 21 and uses the axis L2 perpendicular to the center axis L1 of the steel pipe P as a rotation axis in the directions of arrows L31 and L32. It is rotatable. The rotation of the ring-shaped coil 21 is performed by a driving device described later. In FIG. 2, the opening surface of each ring-shaped coil 21 is perpendicular to the central axis L1 of the steel pipe P. When the ring-shaped coil 21 rotates in the L31 direction from this state, the opening surface of the ring-shaped coil 21 is inclined with respect to the central axis L1 of the steel pipe P as shown in FIG. Thereby, the air gap is reduced. Hereinafter, the reason will be described with reference to FIGS.

  4 and 5 are front views showing the positional relationship between the ring-shaped coil 21 and the steel pipe P passing through the ring-shaped coil 21. Here, the “front view” in the present embodiment means a drawing obtained by projecting the ring-shaped coil 21 and the steel pipe P onto a plane perpendicular to the central axis L1 of the steel pipe P. 4, the opening surface of the ring-shaped coil 21 is perpendicular to the central axis L1 of the steel pipe P. Air gaps L4 to L6 are formed between the ring-shaped coil 21 and the steel pipe P. The air gap L4 is an air gap generated in a direction perpendicular to both the center axis L1 of the steel pipe P and the rotation axis L2 of the ring-shaped coil 21. The air gaps L5 and L6 are air gaps generated in the direction of the rotation axis L2.

  In FIG. 5, the opening surface of the ring-shaped coil 21 is inclined with respect to the central axis L1 of the steel pipe P. That is, the ring-shaped coil 21 has been rotated from the state illustrated in FIG. 4 in the direction of the arrow L31. The air gap L4 shown in FIG. 5 is smaller than the air gap L4 shown in FIG. Thus, the induction heating device 10 according to the present embodiment can reduce the air gap L4 by rotating the ring-shaped coil 21 in the direction of the arrow L31. Therefore, the induction heating device 10 can improve the heating efficiency of the steel pipe P.

  In the present embodiment, the opening surface of the ring-shaped coil 21 and the cross section perpendicular to the central axis L1 of the steel pipe P are all circular, but these shapes are not limited to circular. For example, these shapes may be rectangular. Further, these shapes may be different from each other. However, from the viewpoint of uniformity of heating efficiency and heating amount, it is preferable that these shapes are the same.

  The coil terminal 22 extends from the ring-shaped coil 21 in a direction along the rotation axis L2, and is connected to a power supply device and a driving device. In FIG. 1, the coil terminals 22 of each ring-shaped coil 21 extend in the first direction A along the rotation axis L2. Of course, the coil terminal 22 may extend from the ring-shaped coil 21 in the second direction B along the rotation axis L2. The direction in which the coil terminals 22 extend may be different for each ring-shaped coil 21. For example, as shown in FIG. 6, even if the ring-shaped coils 21 whose coil terminals 22 extend in the first direction A and the ring-shaped coils 21 whose coil terminals 22 extend in the second direction B are arranged alternately. Good. In this example, the angle between the rotation axis L2 of the ring-shaped coil 21 and the rotation axis L2 of the ring-shaped coil 21 adjacent to the ring-shaped coil 21 is 180 °. Of course, the arrangement of the ring-shaped coils 21 is not limited to this example. For example, the ring-shaped coil 21 may be arranged as follows. That is, the ring-shaped coil 21 having the rotation axis L2 shown in FIG. 1 is arranged. Next, a plurality of ring-shaped coils 21 having the rotation axis L2 having the rotation axis L2 as a reference axis and the angles with respect to the reference axis being θ1, θ2,..., Θn are arranged. Here, n is an integer of 1 or more, but is preferably 2 or more. , θn satisfy the relationship of 0 <θ1 <θ2 <... <θn. θn is 180 °. However, θn may be less than 180 °. When n is 2 or more, four or more closest contacts (points at which the air gap with the ring-shaped coil 21 becomes minimum when the ring-shaped coil 21 is inclined) are formed in the circumferential direction of the steel pipe P. Can be. For example, a plurality of ring-shaped coils 21 having a rotation axis L2 having angles of 30 °, 60 °, 90 °, 120 °, 150 °, and 180 ° with respect to the reference axis may be arranged. In this case, n = 6, and the number of closest contacts is 12. Therefore, the heating efficiency of the steel pipe P can be further improved, and the steel pipe P can be more uniformly heated. In addition, from the viewpoint of uniformly heating the steel pipe P, the value of n is preferably as large as possible in an operable range, and the rotation axes L2 are arranged at equal intervals along the circumferential direction of the steel pipe P. Is preferred.

  The power supply device is electrically connected to a coil terminal 22 of each ring-shaped coil 21, and supplies an alternating current to each ring-shaped coil 21 via the coil terminal 22. Here, a power supply device may be prepared for each ring-shaped coil 21. However, an electric circuit is formed by sequentially connecting the coil terminals 22 of each ring-shaped coil 21 with a flexible conductive wire, and the electric circuit is formed. A power supply may be connected. That is, a specific method for supplying an alternating current from the power supply device to each of the ring-shaped coils 21 is not particularly limited.

  The drive device rotates each ring-shaped coil 21 in the direction by rotating the coil terminal 22 of each ring-shaped coil 21 in the directions of arrows L31 and L32. Here, a driving device may be prepared for each ring-shaped coil 21, but the coil terminals 22 of each ring-shaped coil 21 are connected by a driving force transmission mechanism such as a gear, and the driving device is connected to the driving force transmission mechanism. May be connected. That is, a specific method for supplying a driving force from the driving device to each of the ring-shaped coils 21 is not particularly limited.

<2. Induction heating method using induction heating device>
Next, an induction heating method using an induction heating device will be described. First, the rotation angle of each ring-shaped coil 21 is determined according to the outer diameter of the steel pipe P. Then, the driving device is driven to rotate each ring-shaped coil 21 by the determined rotation angle. Here, the rotation angle is preferably determined so that the above-described air gap L4 is reduced as much as possible, but may be determined in consideration of other various operating conditions. Further, the determination of the rotation angle and the driving of the driving device may be performed artificially (that is, by the operator of the induction heating device 10) or may be performed automatically. That is, a control device including a CPU, a ROM, a RAM, and the like may be incorporated in the induction heating device 10, and the control device may determine the rotation angle and drive the driving device. Here, the ROM stores data (for example, a program, a table indicating a correspondence relationship between the outer diameter of the steel pipe P and the rotation angle of each ring-shaped coil 21) necessary for determining the rotation angle and driving the driving device. You. The CPU reads out and executes a program stored in the ROM. The RAM is used as a work area by the CPU.

  Thereafter, the steel pipe P is transported into the ring-shaped coil 21. The transfer of the steel pipe P is performed by a transfer device (not shown). Then, an alternating current is supplied into each ring-shaped coil 21 from the power supply device. Thereby, the steel pipe P is induction-heated. Here, the driving of the power supply device may be performed manually or automatically.

  As described above, according to the present embodiment, the air gap L4 can be reduced by rotating the ring-shaped coil 21. Therefore, the heating efficiency of the steel pipe P is improved. Further, according to the present embodiment, since the rotation angle of the ring-shaped coil 21 can be adjusted according to the outer diameter of the steel pipe P, the outer diameter range of the steel pipe P that the ring-shaped coil 21 can cope with is greatly expanded. I do. According to the embodiment described below, the ring-shaped coil 21 having an inner diameter of 490 mm can induction-heat a steel pipe P having an outer diameter of 150 to 450 mm with high heating efficiency. Therefore, the number of times of replacing the ring-shaped coil 21 can be greatly reduced, and thus the number of times of stopping the operation using the induction heating device 10 can be significantly reduced. Further, the labor cost required for replacing the ring-shaped coil 21 is greatly reduced. Further, the number of replacement ring-shaped coils 21 is greatly reduced. Therefore, it is possible to suppress a decrease in the production amount of the steel pipe P and an increase in the operating cost.

<3. First Modification>
Next, a first modified example will be described. In the above-described embodiment, as shown in FIG. 5, the air gap L4 can be reduced, but the air gaps L5 and L6 in the direction of the rotation axis L2 cannot be reduced. Therefore, in the first modified example, as shown in FIG. 7, the ring-shaped coil 21 moves in the first direction A along the rotation axis L2. Here, the first direction A is a right direction with respect to the transport direction P1 of the steel pipe P, as shown in FIG. The movement of the ring-shaped coil 21 may be performed by the above-described driving device, but a driving device for moving the ring-shaped coil 21 may be separately prepared. Thereby, the air gap L5 becomes smaller. That is, of the air gaps L5 and L6, the air gap existing in the direction opposite to the first direction A with respect to the steel pipe P becomes smaller. Further, since the steel pipe P approaches the inner diameter surface of the ring-shaped coil 21, the air gap L4 is further reduced.

  Here, the amount of movement of the ring-shaped coil 21 in the first direction A is not particularly limited, but is preferably such that the air gap L5 is substantially equal to the air gap L4. In this case, the bias of the heating amount is reduced. It is preferable that the amount of movement of the ring-shaped coil 21 in the first direction A is as large as possible in an operable range (that is, the ring-shaped coil 21 is as close as possible to the steel pipe P in an operable range). In this case, the heating efficiency of the steel pipe P can be further improved, and the steel pipe P can be more uniformly heated. Further, the ring-shaped coil 21 may move in a direction opposite to the first direction A (a second direction B shown in FIG. 1). In this case, the air gap L6 becomes small. The preferred range of the moving amount is the same as described above. According to the first modification, in addition to the air gap L4, one of the air gaps L5 and L6 is further reduced, so that the heating efficiency of the steel pipe P is further improved.

<4. Second modification>
In the first modified example described above, only one of the air gaps L5 and L6 in the direction of the rotation axis L2 can be reduced. Thus, in the second modification, as shown in FIG. 8, the plurality of ring-shaped coils 21 are divided into a first ring-shaped coil 21a and a second ring-shaped coil 21b. The first ring-shaped coil 21a moves in the first direction A, and the second ring-shaped coil 21b moves in the second direction B. The movement of the first and second ring-shaped coils 21a and 21b may be performed in the same manner as in the first modification. Although the movement amount of the first and second ring-shaped coils 21a and 21b is not particularly limited, it is preferable that the air gaps L5 and L6 have the same movement amount as the air gap L4. In this case, the bias of the heating amount is reduced. The amount of movement of the first ring-shaped coil 21a in the first direction A and the amount of movement of the second ring-shaped coil 21b in the second direction B are as large as possible within an operable range (that is, operation). It is preferable that the first and second ring-shaped coils 21a and 21b are brought as close as possible to the steel pipe P as far as possible. In this case, the heating efficiency of the steel pipe P can be further improved, and the steel pipe P can be more uniformly heated. According to the second modification, both the air gaps L5 and L6 are reduced. More specifically, the air gap L5 between the first ring-shaped coil 21a and the steel pipe P is reduced, and the air gap L6 between the second ring-shaped coil 21b and the steel pipe P is reduced. According to the second modification, since the air gaps L4 to L6 are all small, the heating efficiency of the steel pipe P is further improved.

  Here, it is preferable that the number of the first ring-shaped coils 21a is equal to the number of the second ring-shaped coils 21b. In this case, the deviation of the heating amount to the steel pipe P can be further reduced.

<5. Third Modification>
Next, a third modification will be described with reference to FIG. As shown in FIG. 9, the third modification is almost the same as the second modification. However, the coil terminal 22 connected to the first ring-shaped coil 21a extends in the first direction A, and the coil terminal 22 connected to the second ring-shaped coil 21b extends in the second direction B. I have. In the third modification, the same effect as in the second modification can be obtained.

  In addition, in the above-mentioned embodiment and each modification, induction heating may be performed while rotating the steel pipe P. In this case, the rotation axis of the steel pipe P is the central axis L1. In this case, the bias of the heating amount becomes smaller.

  Next, an example of the present embodiment will be described. In this example, the following experiment was performed in order to verify the effects of the above-described embodiment. That is, a plurality of types of steel pipes P having different outer diameters in the range of 150 mm to 450 mm were prepared. Further, a plurality of ring-shaped coils 21 having an inner diameter of 490 mm were prepared as the ring-shaped coils 21. The number of turns of each ring-shaped coil 21 (the number of turns of the coil wire) was one.

  And the steel pipe P was induction-heated using these ring-shaped coils 21. Here, by adjusting the rotation angle of the ring-shaped coil 21 according to the outer diameter of the steel pipe P, the air gap L4 was maintained at about 20 mm (as shown in FIG. 5, there are two air gaps L4). , Each of which was maintained at 20 mm). In addition, the electric energy for induction heating each steel pipe P was fixed. As a result, all the steel pipes P could be heated to almost the same temperature. That is, regardless of the outer diameter of the steel pipe P, the steel pipe P could be heated with substantially the same heating efficiency. Further, when all the ring-shaped coils 21 were moved in the first direction A, the heating efficiency was further improved. Further, when half of the ring-shaped coils 21 were moved in the first direction A and half of the ring-shaped coils 21 were moved in the second direction B, the heating efficiency was further improved.

  The following experiment was performed as a comparative example. That is, the same processing as that of the example was performed except that the opening surface of the ring-shaped coil 21 was maintained perpendicular to the central axis L1 of the steel pipe P. That is, in the comparative example, the rotation of the ring-shaped coil 21 was not performed. As a result, induction heating could be performed on the steel pipe P having an outer diameter of 400 to 450 mm with substantially the same heating efficiency. However, when the steel pipe P having an outer diameter of less than 400 mm was induction heated, the heating efficiency was significantly reduced. That is, when these steel pipes P were induction-heated with the same electric energy as described above, the rate of temperature rise of the steel pipes P was significantly reduced. Therefore, in the comparative example, if the outer diameter of the steel pipe P is less than 400 mm, it is necessary to replace the ring-shaped coil 21 with a smaller inner diameter. As a result, it was confirmed that the heating efficiency of the steel pipe P was increased by the present embodiment.

  Specifically, when the heating efficiency when the steel pipe P having an outer diameter of 450 mm is induction-heated by the operation of the comparative example is set to “1”, in the operation of the example, the heating efficiency when the steel pipe P having an outer diameter of 150 mm is induction-heated is set. The heating efficiency was about “0.75 to 0.9”. That is, the decrease in the heating efficiency was suppressed to 0.25 or less. On the other hand, in the operation of the comparative example, the heating efficiency when the steel pipe P having an outer diameter of 150 mm was induction-heated was about “0.5 to 0.7”. That is, the amount of decrease in the heating efficiency was a very large value of 0.3 or more.

  As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. It is apparent that those skilled in the art to which the present invention pertains can conceive various changes or modifications within the scope of the technical idea described in the appended claims. It is understood that these also belong to the technical scope of the present invention. For example, the induction heating device 10 may induction heat a tubular body other than the steel pipe P. That is, in the present embodiment, any tubular body capable of induction heating can be subjected to induction heating.

Reference Signs List 10 induction heating device 21, 21a, 21b ring-shaped coil 22 coil terminal P steel pipe

Claims (3)

With a plurality of ring-shaped coils for induction heating a tubular body capable of induction heating,
Each of the ring-shaped coils is rotatable about an axis passing through a center point of the ring-shaped coil and perpendicular to a central axis of the tubular body as a rotation axis,
The ring-shaped coil is movable in a direction along the rotation axis,
The plurality of ring-shaped coils are a first ring-shaped coil movable in a first direction along the rotation axis, and a second ring-shaped coil movable in a second direction opposite to the first direction. Including a ring-shaped coil,
The first ring-shaped coil and the second ring-shaped coil are alternately arranged along a central axis of the tubular body,
A first air gap formed between the first ring-shaped coil and the tubular body in a direction along the rotation axis; and a second air-gap and the tubular body in a direction along the rotation axis. Between the position where the first ring-shaped coil and the second ring-shaped coil intersect in the central axis direction of the tubular body and the tubular body. An induction heating device, further comprising a driving device for bringing the first ring-shaped coil and the second ring-shaped coil close to the tubular body so as to be approximately the same as the generated third air gap. . The number of the first ring-shaped coil, characterized in that matches the number of the second ring-shaped coil, the induction heating apparatus according to claim 1. The said tubular body is a steel pipe, The induction heating apparatus of Claim 1 or 2 characterized by the above-mentioned.

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