KR100568327B1 - Method For Heating Steel Material Using Walking Hearth Type Furnace - Google Patents

Abstract

The present invention relates to a method of heating a rolled material such as a billet, using a working hearth type heating furnace that can minimize the temperature difference of the material by heating while varying the working distance of the material in the heating furnace To provide a method of heating the material, the purpose is.

The present invention relates to a method of heating a material using a working hearth type heating furnace including a moving beam and a fixed beam and having a burner installed thereon,

When working the material in the heating furnace at least in a section of the heating furnace, the working hearth type heating furnace for heating the material while working in the heating furnace by varying the stroke distance of the material so as not to be placed in the same position. The material heating method used is made into the summary.

Walking Hurs, Furnace, Stroke, Moving Beam, Fixed Beam

Description

Method for Heating Steel Material Using Walking Hearth Type Furnace}

1 is a schematic diagram of a moving beam and a fixed beam having a material placed thereon in a conventional working hearth type furnace.

Figure 2 is a schematic diagram showing that the material is transported by the conveying beam in a conventional working hearth type furnace.

Figure 3 is a schematic diagram showing the position where the material is placed when heating the material according to the conventional method

Figure 4 is a schematic diagram showing the position where the material is placed when heating the material in accordance with an example of the present invention

5 is a schematic diagram showing an example of an apparatus for controlling the stroke distance according to the present invention;

6 is a circuit diagram showing an example of a circuit for controlling a stroke distance according to the present invention.

                  Explanation of symbols on the main parts of the drawings

One . . . Material 2. . . Moving beam 3. . . Fixed beam

31a-d. . . First limit switch 32. . . Second limit switch

38d, 38b, 38f, 38u. . . Solenoid valve

The present invention relates to a method of heating a rolled material such as a billet, and more particularly, to a method of heating a material using a walking hearth type (Walking Hearth Type) heating furnace.

The heating furnace of wire rod rolling includes moving beam and fixed beam, and is divided into walking beam type and walking heart type according to the installation method of burner.

While the burner beam heating furnace is provided with a burner in the upper and lower portions, the working hearth type heating furnace is provided only in the upper portion.

In the case of the heating beam type furnace, the temperature difference of the material to be heated (billet, etc.) is small, whereas in the case of the working hearth type furnace, the bottom temperature of the material to which the flames of the burner are not directly touched is because the burner is only at the top. The temperature difference of the material is large because it is much lower than other surfaces.

As described above, when the temperature difference of the material is large, the partial diameter difference (hard tolerance value) increases in the product due to the difference between the stretching of the low temperature part and the high part, thereby lowering the quality.

Therefore, when the material is heated using the working hearth type heating furnace, the heating temperature is raised for uniform heating of the material.

For example, when wire rods of 160 angles of high quality steel are rolled, the heating temperature of the billet is controlled to within 1000 ° C, and when the billet is rolled to 120 degrees, the heating temperature is raised to 1130 ° C.

As such, when the heating temperature of the billet is increased, not only the thermal efficiency decreases a lot, but also a lot of scale occurs, so that a real rate decreases significantly, and furthermore, there is a problem in that high-grade steel rolling that needs to be heated at low temperature is impossible.

Accordingly, the present inventors have conducted research to improve the overall problems of the method of heating the material using a working hearth type heating furnace, and based on the results, the present invention proposes the present invention. It is to provide a material heating method using a working hearth type heating furnace that can minimize the temperature difference of the material by heating while wicking the material by varying the stroke distance of the material, the purpose is.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention relates to a method of heating a material using a working hearth type heating furnace including a moving beam and a fixed beam and having a burner installed thereon,

When working the material in the heating furnace at least in a section of the heating furnace, the working hearth type heating furnace for heating the material while working in the heating furnace by varying the stroke distance of the material so as not to be placed in the same position. It relates to a material heating method used.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The working hearth type heating furnace applied to the present invention includes a moving beam 2 and a fixed beam 3 made of refractory as shown in FIGS. 1 to 2, and a burner (not shown) is provided on the upper portion thereof. It is.

In the furnace, the material 1 is walked at a certain stroke by the moving beam 2 made of refractory material, and at this time, the bottom of the material 1 is always shaded and radiated because the flame of the burner does not directly touch it. Because of poor convection, the heat of the upper part of the material (billet) conducts to the bottom and becomes cracked, so the heating temperature must be increased.

In the working method of the working hearth type heating furnace, the moving beam 2 has a standard stroke distance as shown in FIG. 2 when the material (billet) is charged into the heating furnace and placed at the correct position on the charging roller by driving the feed roller. As soon as you lift the billet will walk.

As the material is charged in the above manner and the material is walked as much as the standard stroke distance, the working material is always in the place where the previous material was placed. The higher the temperature difference, the lower the temperature at the bottom of the billet.

That is, as shown in Figure 3, the working distance (L) of the working material is constant, so the second material (billet) (1) is placed in the place where the first billet was placed and the third billet is the part where the second billet was placed. As the material is charged into the furnace and placed only 62 consecutive times, the temperature drops.

As described above, in the conventional method of heating a material using a working hearth type heating furnace, the bottom temperature of the material is lower than that of the other surface, so that the billet is not heated uniformly, so that rolling is difficult. By doing so, the thermal efficiency is much lowered.

Therefore, in the present invention, in order to improve the problem that the material generated when heating the material using a conventional working hearth type heating furnace is always placed in a shaded area, the administration length is changed to maintain a constant working distance of the billet. This is to ensure that the material on the back that is being worked does not lie where the material on the front is located, which is a feature.

In the present invention, as shown in FIG. 4, it is preferable to walk the material in a walking manner in which the positive stroke is made three times, and then the 1/2 stroke is made once, and the positive stroke is made three times again.

When the material is worked in the above manner, the materials are placed three by three, and then fall further by half a stroke, so that the materials are placed in the shade once every three times, thereby reducing the temperature deviation of the floor, thereby minimizing the temperature difference of the materials.

An example of an apparatus for controlling a working method of a material according to the present invention is shown in FIGS. 5 and 6, and a method of controlling the working method of a material according to the present invention as in FIG. 4 with reference to FIGS. 5 and 6. An example of the following is described.

As shown in Fig. 5, the first reverse completion limit switch 31a, the first forward completion limit switch 31b, the first falling completion limit switch 31c, and the first rising completion provided to adjust the conventional working distance. In addition to the limit switch 31d, the second limit switch 32 is additionally installed so that the three normal strokes are operated by the first forward completion limit switch 31b. When the third limit is continuously operated, the first limit switch 31b is operated. It is automatically turned off and the second limit switch 32 is automatically turned on so that the billet walking length becomes shorter than normal so that one more billet width is widened.

In this process, the first limit switch is connected to the operation by the circulation relays R1, R2, R3, and R4, and the up and down operation of the walking beam is performed by the first falling completion limit switch 31c and the first rising completion limit switch 31d. D) and descent are repeated and the power for the operation up to all the limit switches is by solenoid valves 38f, 38b, 38c, 38d.

In FIG. 5, reference numeral 33 denotes a transfer cylinder, 34 denotes a piston, 35 denotes a cylinder stand, and 36 denotes a link.

In the above operation, the place where the billet is placed is placed at the zero part (the raised place). After that, the same way, the billet is placed in the shade once every three times, the temperature difference of the floor is greatly reduced.

Referring to Fig. 6 showing the circuit diagram in which the billets are walking in groups of three, the limit switch is provided in duplicate, as follows.

As shown in Figure 6, when describing the operation of the AUTO operation PLC (Programmable Logic Controller), when the conditions of 31b and 31d is satisfied, the solenoid 38d is operated until the 31c is detected, and the working beam is lowered. If the condition of 31c is satisfied, the solenoid 38b is operated backward until 31a is detected. If the conditions of 31c and 31a are satisfied, the solenoid 38u is operated until the 31d is detected. If the condition is satisfied, forward movement is performed by operating the solenoid 38f until 31b is detected. At this time, the number of advances is counted as C1 to stop the forward movement under the condition of the second limit switch 32 three times, and the next cyclic relay is performed. To connect.

Anti-stroke walking allows the switch to run in the positive stroke direction without counting.

In Fig. 6, R1-R4 represent cyclic relays.

As described above, if one continuous stroke is performed after three continuous stroke walking cycles, the billet is maintained by three intervals as shown in FIG.

When the billet walking stroke is shortened, the front billet is placed so that the walking is done in a raised place rather than in a shaded place, thereby reducing the billet floor temperature difference.

As described above, the present invention in the conventional method of heating the material using a working hearth type furnace, the billet is placed in a raised place where the temperature is restored to what was always placed in the shade until the billet is charged and extracted. Since the bottom temperature difference can be reduced, the billet extraction temperature is 70-100 ℃ lower than the conventional one, and thermal efficiency is greatly improved.High billet heating temperature enables high carbon steel and high-grade steel rolling, which cannot be rolled due to the decarburization problem, and the heating temperature. Since the amount of scale generated is low, the rolling yield is improved.

Claims (2)

In the method of heating the material using a working hearth type heating furnace comprising a moving beam and a fixed beam, the burner is installed on the upper part, When working the material in the furnace, at least a portion of the heating furnace, the heating heart while heating the material in the furnace by varying the stroke distance of the material so as not to be placed in the same position. Material heating method using type heating furnace The method of claim 1, wherein the workpiece is worked in a walking manner in which the positive stroke is repeated three times, after the 1/2 stroke is made once, and then again the third stroke is made. Material heating method using walking hearth type furnace

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