JPH01304685A - Induction heater - Google Patents

Abstract

PURPOSE:To make it possible to heat uniformly and easily by installing auxiliary coils, whose positions, electric power, and frequency can be controlled independently, on both sides of a metal plate to be heated besides a transverse-type main coil. CONSTITUTION:The center part of a metal plate 2 movable to the direction of the arrow 5 is induction heated by at least one pair of transverse-type main coils 1. A plurality of auxiliary coils 7 are installed both sides of both surfaces of the metal plate 2 and driven to work as well as the main coils 1. The auxiliary coils 7 are driven by an electric power source 10 or 11, and the position control, the electric power control, and the frequency control of each auxiliary coil are carried out independently of the main coil 1. The temperature of induction heating can be different according to the positions of the auxiliary coils 7 and furthermore a desired induction heating temperature can be attained by the change of the electric power and the frequency. The temperature of heating pattern of the main coils 1 can thus be corrected easily by the auxiliary coils 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an induction heating apparatus for uniformly heating a metal plate for heat treatment.

(Prior art) There are two methods for heating a metal plate by induction heating: the solenoid coil method and the transverse magnetic flux heating method.The transverse magnetic flux heating method is advantageous in terms of efficiency, but it is disadvantageous in terms of temperature distribution. It is well known that practical application has been delayed.

Although various proposals have been made to put the transverse system into practical use, a temperature distribution that meets the purpose of heating has not yet been achieved.

Heating corresponding to the top and bottom of the metal plate 2 heated as shown in Fig. 8(!L) is a plan view of the transverse type, and Fig. 8(a) is a sectional view taken along A-A' in Fig. 8(a). A set of coils (inductors) is arranged to allow magnetic flux to pass perpendicularly through the metal plate, thereby inducing eddy currents in the metal plate, and this induced current generates Joule heat in the metal plate.

FIG. 9 shows a positional relationship diagram (a) of the heating coil and the metal plate and a heating temperature/data turn (b) when the centers of the heating coil and the metal plate are aligned. The temperature pattern shown by four curves shows a temperature distribution/9 turns. Qualitatively, the temperature at both edges becomes higher at the # middle where the ratio W 1 /W 2 of the heating coil width W1 and the metal plate width W2 increases. The smaller the inverse K W J /W 2 is, the lower the temperature of both edges becomes. Therefore, the optimal W 1 /
Temperature i4 turn is flat only when W 2.

A good temperature/arm turn can be obtained. Since the W1/W2 width is small, a heating coil that corresponds to the width of the metal plate is required, and there are disadvantages such as it takes time to replace the heating coil and increases equipment cost.

Furthermore, depending on the conditions, the temperature in the vicinity of 50 to 100 nm from the edge may drop, which is difficult to correct.

From this point of view, various proposals regarding improvement of heating coils have been made, but none have been satisfactory. The prior art can be broadly classified as follows.

FIG. 10(1) shows a method of attaching a magnetic flux adjusting member 3 made of a magnetic or conductive material whose position can be changed near the edges of the heating coil 1 and the metal plate 2. Special Publication No. Sho 55-36250, Special Publication No. Sho 61-29114, Japanese Patent Publication No. Sho 60-17539
No. 0, etc. are well known.

Figure 10(b) shows a method in which the iron core that forms a part of the heating coil 1 and the subdivided iron core segments 1 are moved, the gap between them and the metal plate 2 is changed, and the segment positions are adjusted so that the optimum temperature is achieved. be. It is known from Japanese Patent Publication No. 59-205183.

FIG. 10(c) shows a method of correcting the temperature at the edge by providing an auxiliary heating device that is integrated with the output side of the main heating coil 1 and is adjustable in 9-part energization. This is known from Japanese Patent Application Laid-Open No. 60-221986.

FIG. 10(d) shows a method in which a plurality of transverse coils are arranged non-concentrically in the longitudinal direction to achieve uniform heating. It is known from Japanese Patent Application Laid-Open No. 60-25179.

(Problems to be Solved by the Invention) None of the above conventional techniques satisfies the temperature distribution in practical terms. The method classified in FIG. 10(a) is not definitive and has little effect even when a magnetic flux adjusting material is used nearby. It is impossible to arbitrarily change the magnetic flux distribution of the transverse magnetic flux coil. Furthermore, since the magnetic flux adjustment material itself becomes overheated, cooling is required.
This method has drawbacks such as the need for delicate position control to adjust the temperature distribution, making it practically impossible.

Fig. 1O (b) Methods classified as K are difficult to fix the core segments and generate large noise and vibration, the segment position adjustment mechanism is complicated, and the heating coil itself needs to be installed near the heating coil. It is also impractical because it is thick, extremely difficult to install and maintain, and there is a risk that the segment position adjustment mechanism may overheat.

In the method shown in Figure 10(c), since the auxiliary heating coil is integrated, it is not possible to adjust the temperature distribution of each edge individually. Therefore, if the coil and the plate are not on a concentric line, adjustment may not be possible. It is possible. It is common knowledge that a metal plate is misaligned in the width direction during transportation, and it is obvious that this causes the temperature distribution to become asymmetric on both sides. Therefore, this method cannot perform sufficient temperature compensation.

Considering the heating characteristics of transverse coils, the method shown in Figure 10(d) is designed to raise the temperature uniformly in the width direction at the exit of the final coil even if multiple coils are arranged in series (in the flow direction of the metal plate). It is impossible to do so.

In other words, the temperature and 9 turns as shown in Figure 9 can be obtained when the coil and plate are on a concentric line, but when the coil and plate are on a non-concentric line, the temperature and 9 turns shown in Figure 11 are obtained when the coil 1 and metal plate 2 are on a non-concentric line.
The positional relationship (, ) and temperature pattern (b) result in the following, and uniform heating is difficult even if such nogulators are stacked one on top of the other.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide an induction heating device that can heat a metal plate sufficiently uniformly and easily to achieve the purpose of heating for heat treatment.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides one or more sets of transverse main coils, and arbitrarily performs position control, power control, and one frequency control before and after the main coils. An induction heating device characterized by having auxiliary coils arranged independently on both sides of a metal plate.

(Function) By configuring as described above, it becomes possible to control the temperature of both edges and edges, which cannot be controlled by the main coil, using the auxiliary coil, making it possible to uniformly control the temperature of the entire metal plate. I can do it.

(Example) FIG. 1 shows the configuration of the present invention. A plurality of main coils 1 that mainly heat the central part of the metal plate 2 moving in the direction of the arrow 5 are arranged in the moving direction of the metal plate 2, and the edge parts of the metal plate 2 are placed at the outlet and inlet of each main coil. Auxiliary coil 7 that mainly heats
are placed independently for each edge. Main coil 1. The auxiliary coils 7 each have a mechanism for independently controlling the position (arrow 8), but this is not shown.

Further, each of the main coils 1 has a power source 9 for independently adjusting the power and frequency of the main coil 1. The auxiliary coil 7 likewise has a power source 10.11.

The heating temperature pattern of the metal plate in the configuration shown in FIG. 1 of the present invention is shown in FIG. 2 (al). The main coil has a temperature pattern shown in FIG. The ratio of W 1 /W 2 is selected as follows.

The temperature rise at the edge of the inlet auxiliary coil is ΔT1. The temperature rise at the edge of the central auxiliary coil is (ΔT2 + ΔT3).

The temperature rise at the edge of the outlet auxiliary coil is Δ4.

Therefore, the maximum temperature difference in the temperature distribution in the width direction of the metal plate is ΔT4. ΔT2. ΔT3. Either ΔT4.

If the temperature difference in the width direction of the metal plate is large, the bending of the plate will be large, causing trouble in conveying the plate and causing scratches due to contact with the heating coil.

Figure 2 (b) shows that when one set of main coils and two sets of auxiliary coils are used, the maximum temperature difference is ΔT, '~ΔT2', which is about twice that of the case in Figure 2 (a). A temperature difference occurs.

Figure 3 shows the temperature increase effect of the auxiliary coil. That is, temperature increase curves 1, 2, and 3.4 show typical ones.

Temperature rise curves 1 and 2.3 are shown in Figure 4 (JL) (b) (1
This figure shows the change due to the relative position of the auxiliary coil and the plate edge shown in Figure 3. Further, the heating cars f3 and f4 show changes in the relative positions of the auxiliary coil and the plate edge shown in FIG. 4(c) depending on the frequency. Although not shown, it goes without saying that the temperature increase value can be arbitrarily varied by further changing the electric power.

In FIG. 5, when the main coil and the metal plate are non-concentric, the temperature/turn pattern becomes T, -T, -T2.

By controlling the position and power of each auxiliary coil, each edge can be adjusted to heat up by (T, -T, ) + (T372).

Above, (1) the main coil and the auxiliary coil are arranged separately.

Figure 6 shows that the main coil 1 is rotated to an arbitrary angle θ0 while remaining parallel to the metal plate 2, and the auxiliary coil is used in combination to uniformly heat the plate width W2 which is less than the regular target plate width W1. Here is an example.

FIG. 7 shows the temperature detected by a device 12 (for example, a scanning radiation thermometer using an image sensor) that continuously measures the temperature in the width direction on the exit side of the heating coil, and compared with each set temperature.
An example of automatically controlling the heating power of the main coil and auxiliary coil is shown.

〔Effect of the invention〕

As explained above, according to the present invention, (1) Uniform heating can be performed in the width direction of the plate at the outlet, so transverse magnetic flux heating can be put to practical use. Therefore, efficient heating can be performed and quality improvement can be achieved through rapid heat treatment.

(2) Furthermore, by dividing the heating coil in the longitudinal direction, it is possible to reduce the temperature difference in the width direction even during the heating process to the exit temperature (heating temperature).
Reduces board bending and distortion.

It is easy to transport and prevents damage caused by contact between the coil and the plate.

(3) By using individually controllable auxiliary coils, it is possible to uniformly heat the same width with fewer heating coils than in the prior art. It is possible to reduce equipment costs and shorten coil replacement time.

(4) Walking during metal plate transportation can be automatically tracked and power can be controlled at the same time, resulting in a uniform temperature.

[Brief explanation of the drawing]

Figure 3 is a diagram showing the relationship between the self-position and temperature, Figure 3 is a diagram showing the relationship between the position of the displacement part of the auxiliary coil used in the present invention and temperature, and Figure 4 is an auxiliary diagram for explaining the characteristics of Figure 3. A diagram showing the relationship between the relative positions of the coil and the edge portion, Figure 5 (a)
is a diagram showing another embodiment of the present invention, and FIG. 5(b) is a diagram showing another embodiment of the present invention.
Figure (a) is a temperature characteristic diagram, Figures 6 and 7 are configuration diagrams showing other different embodiments of the present invention, Figure 8 is a diagram showing a conventional device, and (a) is a plan view. 9(b) is a sectional view, and FIG. 9 is a diagram illustrating the function of FIG. 8, and a diagram showing the positional relationship between the metal plate and the heating coil of the conventional device shown in FIG. 10(d), as well as a temperature characteristic diagram. 1... Main heating coil, 2... Metal plate, 7... Auxiliary coil, 9, 10.11... Power supply, 12... Temperature detector. Applicant's agent Patent attorney Takehiko Suzue 5 Figure 1 (a) (b) Figure 2 Engineer/Shion paX'
Figure 3 Figure 4 ÷ 5 Figure 5 Figure 6) 7 Figure (b) Figure 9 Figure 8 (b) Figure 11

Claims (1)

[Claims] It is characterized by having one or more sets of transverse main coils and auxiliary coils that can arbitrarily perform position control, power control, and frequency control before and after the main coils, independently arranged on both sides of the heated metal plate. heating device.