JPH088050A - Induction heating method for rolled material - Google Patents

Abstract

(57) [Abstract] [Purpose] A method for induction heating of rolled material with excellent heating efficiency that efficiently heats rolled material and prevents overheating due to leakage flux of the edge heater body to obtain the required temperature rise curve. It is provided. In the induction heating method for a rolled material, in which both ends of the rolled material 5 are heated by the edge heaters 1 by continuously running the rolling line, the width of the rolled material 5 protruding from the end portion of the edge heater 1 to both sides is set. As the lap amount L, the lap amount L is 0
When the required temperature rising temperature of the rolled material 5 is obtained in the above range, the lapping amount L is adjusted to perform heating, and when the necessary temperature rising temperature is obtained when the lapping amount L is less than 0, the lapping amount is adjusted. It is characterized in that heating is performed by frequency control in which L is 0 and the frequency f is adjusted by the variable capacitor 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating method for a rolled material which is continuously conveyed by heating an end portion of the rolled material with an edge heater.

[0002]

2. Description of the Related Art Generally, a rolled material such as an iron and steel rolling line is continuously run, passed through a plurality of rolling rollers, and sequentially rolled to produce a rolled material having a predetermined thickness. However, since the rolled material is thin, the amount of heat radiation on both ends is larger than that on the central part, and the temperature drop is large as shown in FIG. Therefore, immediately before entering the rolling mill, if the temperature distribution in the width direction of the plate is made uniform and then rolling occurs, there is a problem that cracks occur or it becomes impossible to roll to a predetermined plate thickness. Therefore, just before entering the rolling mill,
In order to compensate for the temperature drop portion, the temperature is raised as indicated by the alternate long and short dash line in FIG. 3 to make the temperature distribution in the strip width direction uniform before rolling.

The edge heater of the induction heating device for locally heating the end portion side of the rolled material whose temperature has dropped in this way is conventionally constructed as shown in FIG. 4, for example. An edge heater 1 of this induction heating device is one in which a water-cooled copper pipe is wound around the groove portions 2 of a laminated iron core 3 having a plurality of groove portions 2 to form a heating coil 4, and the edge heater 1 is
Installed so that both ends of the rolled material 5 are sandwiched from above and below,
The rolling material 5 which is running is induction-heated to locally heat both ends having a large temperature drop.

In this case, it is considered that the temperature drop of the rolled material 5 changes depending on the plate thickness, and the edge heater 1 according to the plate thickness.
In order to change the temperature rising ratio of the rolled material 5, the relative position between the edge heater 1 and the rolled material 5, that is, the width of the rolled material 5 protruding from the end of the edge heater 1 to both sides is set as the lapping amount L, and the lapping amount L is changed. Then, the desired temperature rising curve was obtained.
The temperature rising curve characteristic of the normal edge heater is as shown in FIG. 5, and this relationship is expressed by the following equation. Where ΔT is the temperature rise value, A is a constant, EXP is an exponential function, and K is the lap amount L.
X is a distance from the end surface of the rolled material 5.

[0005]

[Equation 1] ΔT = A · EXP (-Kx)

As described above, conventionally, the value of K is changed by changing the lap amount L as shown in FIG. 6 and FIG.
The end portion side of the rolled material 5 having the temperature lowered was heated by the intended temperature rising curve. In this case, in order to rapidly increase the temperature rising ratio of the end portion, it is necessary to decrease the lapping amount L of the rolled material 5 and increase the value of K. However, as shown in FIG. 7, when the lap amount L is set to a negative value, the value of K increases, but the leakage magnetic flux 6 increases and the effective magnetic flux interlinking with the rolled material 5 decreases, and the water-cooled copper pipe is wound. There is a problem that the temperature of the heating coil 4 rises and is overheated, and the heating efficiency of the edge heater 1 as a whole decreases as shown in FIG.

[0007]

DISCLOSURE OF THE INVENTION The present invention eliminates the above-mentioned drawbacks, efficiently heats a rolled material, prevents overheating due to leakage flux of the edge heater main body, and obtains a required temperature rising curve, thereby improving heating efficiency. An excellent method for induction heating of rolled material is provided.

[0008]

DISCLOSURE OF THE INVENTION The present invention is an induction heating method for a rolled material, in which both ends of the rolled material are heated by edge heaters by continuously running a rolling line. The width of the rolled material is used as the lap amount, and when the required temperature rise temperature of the rolled material is obtained in the range where the lap amount is 0 or more, lap control is performed to adjust the lap amount and heating is performed. In order to obtain the temperature rise temperature, heating is performed by frequency control in which the lap amount is set to 0 and the frequency is adjusted.

[0009]

The method of induction heating of rolled material according to the present invention is based on the equation
= A · EXP (−Kx), the lapping amount L that provides the required temperature rise can be efficiently heated by performing the lapping control. In addition, in the relational expression represented by ΔT = A · EXP (−Kx) in Equation 1, when the lapping amount L at which the required temperature rise is obtained is less than 0,
By aligning the end portion of the edge heater and the end portion of the rolled material to set the wrap amount L to 0, adjusting the condenser capacity of the variable condenser, and performing frequency control to change the frequency f, the heating efficiency is not reduced. It can be heated with the required temperature rise temperature curve.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail. FIG. 1 shows a circuit of an induction heating apparatus for rolled material according to the present invention, in which a power factor improving capacitor 9 is connected from a high frequency power source 7 through a matching transformer 8 and further to a heating coil 4 of an edge heater 1. In the meantime, via the switch 10 the variable capacitor 11
Is connected. As a result of an experiment, it was found that the relationship between the frequency and the temperature rising characteristic has the following relationship. However, in the formula, A, B, C, and D are constants, EXP is an exponential function, and f
Is the frequency, L is the lapping amount, and x is the distance from the end face of the rolled material.

[0011]

[Equation 2]

Therefore, in the case where both ends of the rolled material 5 are heated by the edge heaters 1 and 1 while the rolling line is continuously run, the relation expressed by ΔT = A · EXP (−Kx) in the above mathematical expression 1 As shown in FIG. 6, the lap control is performed when the lap amount L at which the required temperature rise is obtained by the equation is 0 or more. This is because heating can be performed efficiently when the lap amount L is 0 or more as shown in FIG.

Further, in the case where the lap amount L for obtaining the required temperature rise is less than 0 as shown in FIG. 7 in the relational expression represented by ΔT = A · EXP (−Kx) in the equation 1, it is negative. As shown in FIG. 2, the end portion of the edge heater 1 and the end portion of the rolled material 5 are aligned to set the lap amount L to 0, and the condenser of the variable condenser 11 is set based on the relational expression shown in Formula 2. Frequency f by adjusting the capacity and inserting switch 10.
Heating is performed by controlling the frequency. In this case, since the lap amount L is 0, the relationship between the frequency and the temperature rising characteristic is the following expression.

[0014]

(Equation 3)

Therefore, in the range where the lapping amount L is less than 0 in the relational expression of Equation 1, the lapping amount L is set to 0 to reduce the leakage magnetic flux 6 to increase the effective magnetic flux interlinking with the rolled material 5, and As a whole, the heating coil 4 is prevented from being overheated, and the heating coil 4 shown in FIG.
As shown in, the heating can be performed efficiently. Further, the required temperature rising curve on the end side of the rolled material 5 can be easily obtained by adjusting the frequency f.

[0016]

As described above, according to the induction heating method for rolled material according to the present invention, the lapping amount L with good heating efficiency is 0.
In the above range, lap control for adjusting the lap amount L is performed, and when the lap amount is less than 0, the rolled material is heated by switching to two stages of frequency control in which the lap amount is 0 and the frequency is adjusted. It is possible to efficiently heat the heating coil with the required temperature rising curve, and prevent the heating coil from overheating due to the leakage magnetic flux, thereby extending the life of the coil.

[Brief description of drawings]

FIG. 1 is a single-line circuit diagram showing an induction heating circuit for rolled material according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which the end of the rolled material is aligned with the end of an edge heater and induction heating is performed.

FIG. 3 is a graph showing a temperature distribution in the plate width direction on the end side of the rolled material.

FIG. 4 is a perspective view showing a state in which an end portion of the rolled material is passed between the edge heaters and the end portion is induction-heated.

FIG. 5 is a graph showing a change in a temperature rise value depending on a distance from an end surface of a rolled material.

FIG. 6 is a cross-sectional view showing a state in which an end portion of a rolled material is projected from an end portion of an edge heater and induction heating is performed in a range where a lapping amount L exceeds 0.

FIG. 7 is a cross-sectional view showing a state in which an end portion of a rolled material is made to travel inward from an end portion of an edge heater and induction heating is performed in a range where a lapping amount L is less than 0.

FIG. 8 is a graph showing a relationship between a lapping amount L and heating efficiency.

[Description of sign]

 1 Edge Heater 2 Groove 3 Laminated Iron Core 4 Heating Coil 5 Rolled Material 6 Magnetic Flux 7 High Frequency Power Supply 8 Matching Transformer 9 Power Factor Improvement Capacitor 10 Switch 11 Variable Capacitor

Claims (1)

[Claims] 1. In an induction heating method for a rolled material, in which both ends of the rolled material are heated by edge heaters by continuously running on a rolling line, the width of the rolled material protruding from the end of the edge heater to both sides is wrapped. When the required temperature rising temperature of the rolled material is obtained in the range where the lapping amount is 0 or more, heating is performed by performing the lapping control for adjusting the lapping amount, and when the necessary heating temperature is obtained when the lapping amount is less than 0, The method for induction heating of a rolled material is characterized in that heating is performed by frequency control in which the lap amount is set to 0 and the frequency is adjusted.