JPS6011091B2 - Heating control method for metal end - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating control method for an end of a metal piece, and more specifically, the present invention relates to a heating control method for an end of a metal piece, and more specifically, even if the positional relationship between the inductor of an induction heating device and the end of the metal piece changes, the end of the metal piece can be heated to a predetermined temperature. The present invention relates to a heating control method for adjusting power supplied to an inductor so as to

During hot rolling, the temperature at the ends (edges) of the rolled material decreases by approximately 100° C. from the rough rolling mill to the finish rolling mill, compared to the center portion in the middle direction.

Therefore, depending on the type of steel, defects such as edge cracks and roughness may occur in the rolled material during rolling, causing problems in terms of product quality and production efficiency. For this reason, recently the ends of the metal pieces are electrically heated by induction using an inductor.

In the conventional method of heating the end of a metal piece, when the end of the metal piece is displaced from the expected passing position, an inductor is placed in advance at a position where the end of the metal piece is expected to pass. - A tracing roll is used to detect the edge of the metal piece and move it accordingly to follow the edge of the metal piece, and a constant force is supplied to the inductor to heat the end of the metal piece of a predetermined width to the required temperature. It is something to do. However, making the inductor follow the passing position of the metal piece in this way is problematic because the structure of the device becomes complicated. In addition, pressing a roll with considerable pressure along the side surface of a metal piece in order to improve the followability of the walk causes problems such as deflection, especially when the piece is thin or hot. In view of these problems, the present invention provides a heating device having a simple structure and a method for heating the end of a metal piece, which heats the end of a metal piece having a predetermined width to a required temperature.

The gist of this method is to inductively heat the end of a metal piece by passing the end of the metal piece between opposed inductors.The current or power of the inductor is detected and the end heating temperature is set in advance in the control device. The heating control method for the end of a metal piece is characterized in that the voltage of the inductor is controlled using the difference signal between the two, so that the difference becomes zero. The present invention will be described in detail below with reference to an illustrative embodiment.

FIG. 1 is a block diagram of one embodiment of the present invention.

A metal piece 2 to be heated is transferred by a roller conveyor 1.

3a and 3b are inductors of a conductive heating device, which are bifurcated across the expected passing position of the end of the metal piece. 4 is a matching capacitor, 5 is a high frequency converter, and an inductor 3
6 is a transformer, 7 is a shunt that detects the current flowing through the inductor 3a, and 8 is an inverter that controls the voltage of the inverter 5 so that the current change caused by the walk of the metal piece remains constant. It is a control device that controls.

Note that the capacitor 4, inverter 5, transformer 6, shunt 7, and control device 8 are similarly connected to the other inductor 3b (not shown). Figure 2 shows the walking amount of the metal piece 2 and the inductor 3 in the above device.
Figure 2 shows the positional relationship between a and 3b.
is a sectional view showing the normal positional relationship of the metal piece 2;
FIG. b is a sectional view when the metal piece 2 is biased towards the right side guide 9b.

The set width of the side guides 9a, 9b is usually the width W of the metal piece 2 plus the margin length 1 (for example, 1=5 lengths). Therefore, the metal piece 2 walks along these side guides 9a, 9b.
The setting W changes within the range of 121. For example, when the metal piece 2 is biased toward the side guide 9b as shown in FIG. 2b, the impedance Z of the inductor 3b is smaller than the zero walk amount position as shown in FIG. 3, and the impedance Z of the other inductor 3a is On the contrary, it becomes larger. Fourth
The figure shows an example of heating bran at the end of metal piece 2. Compared to the temperature rise curve with zero walk amount (1=0), the temperature rise curve of inductor 3b with a walk amount of 11 +1 is higher. As a result, the temperature increase curve of the inductor 3a with a walking amount of - becomes low. Therefore, when the metal piece 2 walks, the current 1 flowing through the inductors 3a and 3b changes, and if the supply voltage V is constant as in the conventional case, the end of the metal piece cannot be heated to the required temperature. Figure 5 shows the walking amount of the metal piece 2 and the inductors 3a, 3b when the end of the metal piece is heated to a temperature increase of 50q○, 10p○, and 150°C, respectively.
This shows the relationship between the supply voltage V to the

From this figure, it can be seen that the combined voltage V to the inductor 3b with a walk amount of 11 may be smaller than that of the inductor 3b with a walk amount of zero, and the voltage V to be supplied to the other inductor 3a is required to be large. Therefore, in the present invention, even if the amount of walking of the metal piece 2 changes to -1, the heating is done as follows so that the amount of temperature increase is the same as when the amount of walking is zero.

That is, the current flowing through the inductors 3a and 3b is detected by the shunt 7, and is inputted to the control device 8 in which the current value at zero walk amount determined for each end heating temperature (amount of temperature rise) is set in advance. When compared with the current value, the control device 8 outputs the deviation signal between the two to the inverter 5 to control the voltage supplied to the inductors 3a and 3b so that the deviation becomes zero. By controlling the supply voltage of the inductors 3a and 3b, even if the amount of walking occurs in the metal piece 2, the inductors 3a and 3
Since the current flowing through b is always constant, the end of the metal piece 1 is heated to the required temperature. For example, if you want the amount of temperature rise at the end of the metal piece 2 to be 10,000, the voltage V2 of the inductor 3a with the walk amount -1 is 240V', so that the temperature rise of the inductors 3a and 3b is constant. The voltage V2 of the inductor 3b with the amount +1 is controlled to 160V, respectively.

Therefore, even if the metal piece 2 is walked, the amount of temperature rise becomes a temperature rise curve that is almost the same as when the amount of walk is zero. Further, when increasing the temperature of the end portion of the metal piece 2 to 50 qo, or when heating to a required temperature, the metal piece 2 is heated in the same manner. Even if a method other than the method described above is used in which electric power is detected and voltage is controlled, the end of the metal piece 2 is heated in the same way.

In this manner, the present invention electrically detects the walking amount of the metal piece, thereby eliminating the need for a conventional copying device or detecting the walking position of the metal piece, and enables efficient metal piece end heating control with a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 shows the walking amount of a metal piece and the positional relationship of an inductor. FIG. 3 shows the amount of change in inductor impedance and current with respect to the amount of walking. FIG. 4 shows the temperature rise curve of the end of the metal piece, and FIG. 5 shows the relationship between the target temperature rise amount and the combined power of the inductor. 1...roller conveyor, 2...metal piece, 3a, 3b...inductor, 4...capacitor, 5...inverter, 6...transformer, 7...shunt, 8... ····Control device,
9a, 9b...Side guide. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. When the end of a metal piece is passed between facing inductors to inductively heat the end of the metal piece, the current or power of the inductor is detected and the amount of walk is zero at each end heating temperature set in advance in the control device. A heating control method for an end of a metal piece, characterized in that the voltage applied to the inductor is controlled using a deviation signal between the two, so that the deviation becomes zero.