JPS6319571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Prior Art] For example, steel materials such as slabs, blooms, and billets are heated to a predetermined temperature in a heating furnace, and then hot worked by hot rolling or the like. As a heating means at this time, a combustion heating furnace using fuel such as LNG, coke oven gas, or furnace oil as a heating source is used. In addition, recently, electrical heating, which allows for faster and more uniform heating and relatively easier control of atmospheric gas than the heating furnace, is being considered.
31477. In electrical heating, electrodes are brought into contact with both lengthwise ends of a steel material to be heated, such as a slab, and electricity is applied to heat the steel material by Joule heat.

[Problems to be Solved by the Invention] As mentioned above, in the current heating device, the steel material to be heated is heated by directly passing current through the current heating electrodes that are in contact with both end surfaces of the steel material. Since both end faces of the electrode are not necessarily flat, but rather have some unevenness or curvature, the contact between the electrodes is not good, and the current density during electrical heating is high (for example, 500 to 1500 A/ ^cm2 )
Therefore, both end faces are overheated. The area to be overheated is, for example, 200 mm from the end surface in contact with the electrode.
In some cases, it may reach the inside of the steel material to be heated.

This overheated area has a negative impact on quality, so for example, in the case of heated steel materials that require strict product quality, it may be necessary to cut them out, resulting in a decrease in yield. .

Furthermore, once the specified heating is completed by electrical heating, the electrodes must be separated from both end surfaces of the steel material to be heated, but since the electrodes may be adhered to the end surfaces, it is necessary to apply a certain external force to separate them. The need may arise. In this case, it is necessary to separate the electrodes without causing flaws on the end or bottom surface of the heated steel material, or without pulling and displacing the heated steel material. Until now, little consideration has been given to these measures.

The present invention enables uniform heating without causing overheating on both end surfaces of the steel material to be heated in contact with the electrodes, and also prevents the occurrence of flaws when the electrodes are separated from the both end surfaces after heating is completed. The purpose of the present invention is to provide an energized heating furnace that eliminates the troubles of the above.

[Means for solving problems]

The gist is that a heating device is provided inside, which is connected to a hollow electrode that is connected to an electrode advance/retreat drive device and can freely move forward and backward with respect to the material to be heated, and a fuel flow pipe and a combustion air flow pipe. The energized heating electrode is characterized by comprising a cooling device provided in a hollow portion of the electrode so as to be freely advanced and retractable, and a cooling device advancement/retraction driving device connected to the cooling device.

〔Example〕

The present invention will be described in detail below based on one embodiment with reference to the drawings.

In the drawings, reference numeral 1 denotes an electric heating furnace, and a plurality of electrodes 2 are provided on both sides of the furnace, and in this embodiment, four electrodes are provided on one side. An electrode advance/retreat drive device 3, such as a cylinder, is connected to the electrode 2 via a connecting rod 4, and is movable relative to the heated steel material 5. Further, each of the electrodes 2 is provided with an electrode advance/retreat drive device 3, so that each electrode 2 can independently advance or retreat.

The electrode 2 has a hollow portion 6 formed therein, making it a hollow electrode.

Reference numeral 7 denotes a heating device 8, for example, a cooling device equipped with a burner, which is provided in the hollow portion 6 of the electrode 2 so as to be able to move forward and backward. Reference numeral 9 denotes a cooling device advancement/retraction drive device.

The cooling device 7 will be further explained with reference to FIG. 2. A cooling header 10 is provided at the tip of the cooling device 7. A refrigerant flow pipe 11 supplies a refrigerant such as cooling water, cooling air water, or cooling gas to the cooling header 10. Reference numeral 12 designates a heating device, such as a burner, provided in a hollow portion within the cooling header 10, and is connected to a fuel flow pipe 13 and a combustion air flow pipe 14.

By the way, the cooling device 7 provided with the heating device 8 operates as follows. When the electrode 2 is brought into contact with both end faces of the steel material 5 to be heated and electrically heated, the contact surface and its vicinity are locally heated due to contact resistance, local irregularities in the contact state, etc. In this case, a refrigerant is passed through the cooling header 10 of the cooling device 7 to cool the heated steel material 1 through the cooling header 10.
0 to eliminate local overheating and equalize the temperature. Further, when it is necessary to preheat the electrode 2, such as when starting up the energized heating furnace or restarting the heating operation, the burner 12 is activated to heat the electrode 2. When the electrode 2 is preheated in this manner and electrically heated, no heat is transferred from the heated steel material 5 side to the electrode 2, and there is no temperature deviation, and uniform heating can be performed.

Reference numeral 15 denotes a temperature measuring device, which in this embodiment is provided at the center and both sides of the energized heating furnace 1 in the width direction, and measures the temperature of the center portion of the steel material 5 to be heated and both end surfaces in contact with the electrodes 2.

Reference numeral 16 denotes an electrode pressing force control device, into which a temperature signal from the temperature measuring device 15 is input, and the electrode 2 is brought into contact with the end surface of the heated steel material 5 with a pressing force corresponding to the temperature. For this purpose, the electrode pressing force control device 16 outputs an advancement/retraction control signal to the electrode advancement/retraction drive device 3 to control the electrode pressing force.

17 is a temperature control device, and temperature measuring device 15
A temperature signal is inputted via the electrode pressing force control device 16, and if, for example, both end surfaces of the heated steel material 5 are hotter than the center, the cooling device 7 is activated to lower the temperature of both end surfaces. Prevents local overheating and heats without temperature deviation. When the temperature deviation is eliminated, the cooling device advancement/retraction driving device 9 is operated to move the cooling device 7 back from the end surface of the steel material 2 to be heated.

As described above, the steel material 5 to be heated is heated without any temperature deviation, especially without locally overheating both end surfaces of the steel material 5 to be heated.

Note that 18 is a skid on which the heated steel material 5 is placed.

When heating is completed, the electrodes 2 are separated from both end surfaces of the steel material 5 to be heated, but since the electrodes 2 are adhered to the end surfaces of the steel material 5 to be heated, conventionally it has not been possible to separate them easily. However, in the present invention, since each electrode 2 is connected to its own electrode advance/retreat drive device 3, when performing the separation, for example, the electrodes 2-1, 2-3 on both sides are connected to the advance/retreat drive device 3-1. ，
3-3 is kept in contact with the end surface of the heated steel material 5 without being operated, while the intermediate electrode 2-2 is operated by the advancing/retracting drive device 3-3.
-2 is pulled away from the end face of the heated steel material 5 by applying a retreating force to the steel material 5. At this time, since the electrodes 2-1 and 2-3 on both sides support the steel material 5 to be heated, the electrode 2-2 on the intermediate side does not displace the steel material 5 to be heated and does not cause any flaws. Easily heated steel material 5
be separated from Once separated, the electrode 2-2 will not adhere to the end surface of the heated steel material 5 even if it is immediately brought into contact again.

When separating the electrodes 2-1, 2-3 on both sides, bring the intermediate electrode 2-2 into contact with the end face of the heated steel material 5, hold the heated steel material 5, and separate the electrodes 2-1, 2. ―
2 is moved backward by the electrode advance/retreat drive devices 3-1, 3-3 and separated from the heated steel material 5 in the same manner as described above.

〔Effect of the invention〕

Since the present invention is as described above, uniform heating is performed without overheating both end faces of the steel material 5 to be heated that come into contact with the electrode 2 and the vicinity thereof. Further, even when the electrode 2 is separated from the both end faces, the steel material 5 to be heated is removed without any scratches such as scratches or the like, and without being displaced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a heating furnace and its peripheral equipment showing an embodiment of the present invention, FIG. 2 is an enlarged view of a cooling device in an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 3 is a plan view showing the arrangement of electrodes in an example. DESCRIPTION OF SYMBOLS 1... Current heating furnace, 2... Electrode, 3... Electrode advance/retreat drive device, 5... Steel material to be heated, 7... Cooling device, 9... Cooling device advance/retreat drive device, 10... Cooling header, 11 ... Refrigerant flow pipe, 12 ... Heating device, 15 ... Temperature measuring device, 16 ... Electrode pressing force control device, 17 ... Temperature control device.

Claims (1)

[Claims] 1. A heating device is provided inside, in which hollow electrodes each connected to an electrode advance/retreat drive device and capable of moving forward and backward with respect to the material to be heated, and a fuel flow pipe and a combustion air flow pipe are connected; 1. A current-carrying heating electrode comprising: a cooling device provided in a hollow portion of the electrode so as to be freely advanced and retractable; and a cooling device advancement/retraction driving device connected to the cooling device.