JPH0459367B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field) The present invention relates to an induction heating device, and more particularly to an induction heating device that continuously heats an end portion of a material to be heated, which has a round or flat cross-sectional shape and has a predetermined length. (Prior Art) An induction heating device is used as a means for heating the end of a material to be heated having a predetermined length and cross section, such as a round metal material or a flat metal plate. The conveyor device for heating is complicated,
There were disadvantages of increased costs and poor coil effect. A conventional induction heating device will be explained with reference to FIGS. 1 to 3 as follows. In each figure,
1 is a coil for induction heating, and 2 is a material to be heated having a predetermined length, such as a round metal bar. The arrow shown in the figure indicates the direction in which the heated material 2 is being fed while moving. The induction heating device shown in Fig. 1 is of a so-called open type, and as shown in A and B of the figure, a coil 1 is disposed vertically in parallel with a material to be heated 2 in between, and parallel to the axial direction of the material to be heated. They are arranged orthogonally. According to this open type, as can be seen from the figure, the coil 1 is arranged so as not to obstruct the continuous movement of the heated material 2 in one direction, so the conveyance device for the heated material 2 is simple and inexpensive. However, the space factor of the heated material 2 located inside the coil 1 becomes small, which has the disadvantage that the coil effect is poor. Figure 2 shows what is called a semi-open type, and in this case as well, not only is the coil effect as poor as that of the open type in Figure 1, but also
As can be seen from the figure, a part of the coil 1 is located in a place that prevents the heated material 2 from moving in one direction.
As shown in the figure, it is necessary to move the heated material 2 not only in the lateral direction but also in the axial direction, which has the disadvantage that the conveying device becomes complicated and costly. In order to simplify the above-mentioned conveying device and increase the coil efficiency, a configuration as shown in Fig. 3 is adopted, but in this case, while the heated material 2 is flowing horizontally on the line, the An extra moving mechanism is required to move each induction heating coil 1 in and out of the position to the end of the heated material 2, and the overall structure cannot be said to be simple.
As described above, all of the conventional induction heating devices have their own advantages and disadvantages, and are not necessarily satisfactory. (Objective of the Invention) The present invention improves the above-mentioned conventional drawbacks.The conveying mechanism for the heated material is a simple one-way feeding mechanism similar to the conventional open type, and the coil efficiency is higher than that of the conventional one. It is an object of the present invention to provide an induction heating device that can use medium frequency waves, which are significantly expensive and whose equipment costs and running costs are lower than those of high frequencies. (Summary of the Invention) In order to achieve the above object, an induction heating device according to the present invention sandwiches the ends of a material to be heated having a predetermined length and an appropriate cross-sectional shape from the upper and lower sides, and Induction heating coils consisting of coil conductor portions parallel to each other are provided facing each other, and by making the direction of current flowing through each of the opposing coil conductors the same, a magnetic flux perpendicular to the axial direction of the heated material is formed, The first feature is that the end portion of the material to be heated is heated by induction. In addition, the above-mentioned positional relationship between the heated material and the coil is such that a magnetic pole is formed in the center of the cross section of the heated material, and an induced secondary current path is formed at both ends of the heated material that sandwich the magnetic pole. The second feature is that it generates heat. Furthermore, the position of the heated material and the coil is such that a plurality of magnetic poles are formed in the cross section of the heated material, and each induced secondary current path is formed in a portion sandwiching each magnetic pole at the end of the heated material. The third feature is that it generates heat. (Example) Examples of the present invention will be described below with reference to FIGS. 4 to 7. In the figure, a coil 1 has a flat rectangular cylindrical shape, has a cooling water hole 3 inside, and has a connecting part and a part in which an iron core 1b with a U-shaped cross section is laminated on the outside of a conductor 1a parallel to the axial direction of the heated material. It is composed of a conductor 1c. As shown in the figure, this coil 1 consists of two coils 1 and 1 disposed in parallel and facing each other, sandwiching both sides of a heated material 2. Each coil 1, 1 is arranged on a plane, and therefore there is no coil conductor that blocks the heated material 2 from being continuously transferred in one direction. The material 2 can be transported continuously in one direction. Furthermore, the coil 1 is provided parallel to the axial direction of the heated material 2, and has coil conductors 1 facing each other.
By making the direction of the current flowing through a and 1a the same, a magnetic flux is formed that is perpendicular to the axial direction of the heated material 2 having an arbitrary length. In FIGS. 4 and 5, two types of heated materials 2, 2, round and flat, respectively, are made to have the same pitch and ball pitch S, so that the heated material 2 is placed in the center of the cross section of the heated material 2. The diagram shows the arrangement relationship between a coil 1 and a heated material 2, which form magnetic poles perpendicular to the axial direction of the coil 1 and generate heat by forming current paths at both ends sandwiching the magnetic poles, and the direction in which the current flows. The coil conductors 1a, 1a, which are arranged facing each other with the material to be heated 2 in between, may be arranged in arbitrary plural rows, while the material to be heated 2 is arranged in plural numbers at intervals equal to the ball pitch S. The plurality of heated materials 2 are heat-treated as they form one set and are continuously transferred intermittently at every ball pitch of the coil conductor 1a or every integral multiple thereof. be. The relationship between the heated material 2 and the coil conductor 1a is such that a magnetic pole is formed in the center of the heated material 2 as described above, which provides the best coil effect, but the present invention is not limited to this. Of course, if the magnetic pole covers a part of the material 2 to be heated, induction heating will occur. Next, FIG. 7 shows, as an example of the irregularly shaped heated material 2, the arrangement relationship between a flat material whose center part is a protruding thick part and a coil conductor 1a. That is, in this case, the center of the magnetic pole is placed at the irregular position, that is, shifted from the thick part. The above relationship can be achieved by arranging the coil conductors 1a with different widths as shown in FIGS. 7A and B, or by appropriately selecting the arrangement between the coil conductors 1a as shown in FIG. 7C. This can be realized by In the case of FIG. 7 above, the pitch of the heated material 2 is twice the pitch of the ball, and in order to effectively provide a path for the induced current in the heated material, the thick part and the magnetic pole center should be arranged as much as possible. ≧Δ/2 (however, is the distance between the center of the thick part and the center of the magnetic pole, Δ
is the current penetration depth. ) is desirable. When the heated material 2 and the coil conductor 1a are arranged in this way, the coil current and the secondary current induced in the heated material 2 are as shown in Fig. 7B and C.
As can be seen from the figure, the irregularly shaped heated material 2
More current flows through the thicker part of the tube, so the thicker part is heated equally with the thinner parts on both sides. In addition, in the above, as an example of the irregularly shaped heated material 2, an example was shown in which the central part of the flat metal material became a thick part, and an example of the arrangement of the coil conductor 1a corresponding to this was shown. The material 2 is not limited to the structure described above, and may have a cross-sectional shape in which the thick part is located away from the center. The arrangement interval of the coil conductors 1a is changed to ensure that the thick portions are evenly heated. For example, when comparing the total efficiency of the conventional open type induction heating device shown in FIG. 2 and the device according to the present invention, the results are as follows. In other words, when the material to be heated 2 is a flat bar with width b and thickness a or a round bar with width a, according to the above conventional heating method, the induced current flows through the cross section of the material to be heated. a≧2.5Δ ≧158ρ/μa ² (lx, μ (magnetic permeability) = 1, ρ (specific resistance value) = 100,
a = 0.6 cm (frequency) ≧ 43889 Hz), resulting in a high frequency, and total efficiency = 0.336 (conversion efficiency = 0.6, transmission efficiency = 0.8, coil efficiency = 0.7). On the other hand, in the case of the induction heating device of the present invention, the induced current flows along the axial direction of the material to be heated, so the frequency for heating is an intermediate wave (e.g.
50 to 20000Hz), the conversion efficiency and transmission efficiency are much improved, so the total efficiency = 0.737 (conversion efficiency = 0.97, transmission efficiency =
0.95, coil efficiency = 0.8), the running cost can be reduced to less than half that of conventional equipment using high frequencies. (Effects of the Invention) As described above, according to the induction heating device according to the present invention, the coils facing each other with the material to be heated between them are separated into upper and lower sides, and the material to be heated is continuously heated. Since there are no coils located to obstruct the transfer in the direction of transfer, the transfer mechanism for the material to be heated can be a simple mechanism that only aligns the edges of the material with a lateral feed mechanism. Cost reduction can be achieved. Further, since the opposing coils are separated from each other, the interval between them can be adjusted freely, and it is possible to easily adapt to changes in the diameter of the heated material. Moreover, since the above-mentioned coil is arranged parallel to the axial direction of the material to be heated so as to form orthogonal magnetic flux, it is possible to perform induction heating using medium frequency instead of high frequency as mentioned above. , the total efficiency of the coil is improved compared to the conventional one, and therefore the equipment cost and running cost can be significantly reduced compared to the conventional high frequency. Incidentally, a comparison example between the device of the present invention and the conventional device is shown in the table below.

[Table] The present invention has the above-mentioned effects compared to conventional devices.

[Brief explanation of the drawing]

Figures 1A and B, Figures 2A and B, and Figures 3A and B are respectively a plan view and a perspective view of a conventional induction heating device.
4A and 5 are explanatory diagrams of the induction heating device according to the present invention, FIG. 4B is a perspective view, FIG. 6 is a perspective view showing details of the coil conductor, and FIGS. 7A and B are other illustrations. Explanatory drawings and perspective views of the embodiment, FIG. 7C is a perspective view of yet another embodiment. 1... Coil, 1a... Coil conductor, 2... Heated material.

Claims (1)

[Scope of Claims] 1. An induction heating coil that sandwiches the ends of a material to be heated, such as a bar or strip, having a predetermined length from above and below, and is comprised of a coil conductor portion parallel to the axial direction of the material to be heated. An induction heating device characterized in that the coil conductors facing each other face each other, and the direction of current flowing through the facing coil conductors is the same to form a magnetic flux perpendicular to the axial direction of the heated material. 2. The induction heating device according to claim 1, wherein the coil conductors are arranged at predetermined intervals so that a magnetic pole is formed in the center of the cross section of the material to be heated. 3. The induction heating device according to claim 1, wherein the coil conductors are arranged at predetermined intervals so that a plurality of magnetic poles are formed in the cross section of the material to be heated.