JPS61136614A - Billet extracting method in walking type heating furnace - Google Patents

Abstract

PURPOSE:To execute efficient heat treatment of many billets under different heating conditions by dividing a walking type heating furnace in the longitudinal direction, providing an intermediate extracting port thereto, charging respectively the billets from the front and rear part of the furnace body and conveying the billets separately in the furnace. CONSTITUTION:A hot material charging port 4 and a cold material charging port 5 are provided respectively to the front and rear part of a furnace body 3 and the intermediate extracting port 21 is provided near the divided hearth part bisected in the longitudinal direction in the walking hearth furnace provided with the furnace body 3 having a soaking area 6 and a holding area 7 and is provided with movable hearths 11, 12 and stationary hearths 20 respectively thereto. The hot billets in the high temp. state in the previous stage are charged through the port 4 of such heating furnace and while the billets are conveyed by the hearth 11 operated by a driving mechanism 13, the billets are heat-treated in the area 6. On the other hand, the once cooled cold billets are charged through the port 5 and are heat-treated in the area 7. The heat-treated billets are extracted from the port 21 by the operation of an extraction machine (not shown in fig.) in the comb-shaped part 20 where the hearths 11, 12 face each other.

Description

Detailed Description of the Invention (Industrial Application Field) This invention is a walking type heating furnace that continuously heat-treats a large number of steel billets. This relates to a method of extracting from an intermediate position.

(Prior art) In a conventional walking hearth furnace, a billet charging inlet is provided at one end of the furnace body, a billet extraction port is provided at the other end, and at least a heating zone and a soaking zone are formed inside the furnace body. At the bottom, fixed hearths are arranged in the longitudinal direction of the furnace body, and movable hearth bodies are arranged alternately between the fixed hearths, and the movable hearths are moved parallel to the fixed hearth and rectangularly in the vertical direction by a drive mechanism. The steel billet charged from the billet loading inlet is alternately transferred to a movable hearth and a fixed hearth while being transported to the extraction port side, during which time it is heated to the desired temperature by a burner. .

In the case of a cold treatment furnace that focuses on cold treatment by heating the cold steel billets, which have been turned into cold billets, to a target temperature during the furnace shutdown, the cold billets are placed at one end of the furnace body. Generally, the length of the furnace becomes longer because the steel pieces are charged through the charging inlet provided at the end and heated while reaching the extraction port at the other end.

Therefore, if a heating furnace with a long furnace length, which is constructed with the main focus on cold material treatment as described above, is used to treat hot steel billets that have been charged into the heating furnace at a high temperature in the previous process, ,
The furnace is thermally uneconomical, and conversely, if you try to process cold billets in a short furnace length heat material processing furnace that is designed with the main focus on heat material processing, you will end up with a furnace that does not have sufficient heating capacity. Become.

In addition, when using a hot material processing furnace and a cold material processing furnace in combination, the operator must operate two furnaces with different systems at the same time, and in these processing furnaces, the refractories in the furnace In order to protect the furnace temperature, rapid ON-OFF operation of the furnace temperature is not possible, and when a tunnel furnace is used as a heating material processing furnace, it is difficult to eliminate the temperature difference between the front and rear ends of hot steel billets in the furnace. This is considered difficult.

On the other hand, if the billet to be charged into the heating furnace is a hot steel billet that has been in a high temperature state in the previous process, it is preferable to charge the billet into the heating furnace as it is from the viewpoint of energy saving. An intermediate-charging type heating furnace has been proposed in which a steel billet charging inlet is provided in a section to enable intermediate charging of billets.

For example, in the intermediate charging furnace shown in JP-A No. 58-171523, the billets are charged into the furnace by being pushed by the charging machine on a flat surface without a guide. are doing.

For this reason, there is a risk that the steel billet cannot be charged to the furnace core within a certain allowable angle that does not interfere with the conveyance of the steel billet in the furnace, and if there is sag at the tip of the steel billet, There is also the risk of it getting stuck in the gap.

Compared to the above-mentioned JP-A-59-171,523, the method of intermediate value charging seen in JP-A No. 58-157918 adopts a method that allows the billet to be safely charged into the furnace. Although it can be used in a walking beam furnace that requires space below the hearth level, it cannot be used in a walking hearth furnace.

In addition, when the billets charged to the heating furnace are thin steel billets such as billets, the above-mentioned intermediate charging method is used, and the sliding oak beam furnace requires a large number of skid rows, which is thermally uneconomical. It is a furnace type.

(Object of the invention) This invention has been made in view of the above points, and is applicable to heating furnaces such as walking hearth furnaces, and is used in direct rolling, which has rapidly developed in recent years. This system is designed to efficiently heat hot steel billets to a warm temperature, and simultaneously has a function to stock billets in case of rolling troubles and a heating function to raise the temperature of cold billets to a temperature at which they can be rolled.

(Structure of the Invention) To achieve this object, the present invention provides a walking hearth furnace, etc., in which the hearth is divided into two or more parts in the longitudinal direction, and steel piece charging inlets are provided at the front and rear parts of the furnace body. In a heating furnace, an intermediate extraction port is provided in the vicinity of at least one hearth division part, and by vertically moving the hearth, one of the hearths is first raised, and then the other hearth is raised by the steel pieces. A method for extracting steel pieces in a walking heating furnace, characterized in that the steel pieces are transferred until they come into contact with the raised hearth end face, and then stopped at a predetermined position, and the steel pieces are extracted by operating an extractor. This is the summary.

(First Embodiment) Fig. 1 is a vertical sectional view showing a schematic configuration of a walking hearth furnace to which the present invention is applied, Fig. 2 is a plan view of main parts, and Fig.
The figure is an explanatory diagram of the operation.

In the figure, 1 is a concrete foundation, 2 is a recess formed on the concrete foundation, and 3 is a furnace body with a rectangular cross section provided on the recess 2. A material charging inlet 4 and a cold material charging inlet 5 are provided.

Inside the furnace body, approximately 1/3 of the furnace length from one heating material charging port 4 side.
A soaking area 6 is formed over the range of , and the remaining coolant charging port 5 is
A heat retention area 7 is formed between the two. A burner 8a is arranged on the top wall of the heat soaking area 6, and a burner 8b and a flue 9 for discharging combustion exhaust gas are provided in the heat retention area 7.

10 is a fixed hearth disposed in the longitudinal direction of the furnace body at the bottom of the furnace body; 11.12 is a movable hearth with a two-part structure arranged alternately between the fixed hearths 10; The first movable hearth 1 of
1 corresponds to the soaking area 6, and the other second movable hearth 12 corresponds to the heat retaining area 7.

13.14 is the 1st. A drive mechanism for the second removable hearth 11.12, each of which is disposed on the bottom surface of the recess 2 and supported on a plurality of bases 15 each having an inclined surface 15a on its upper surface, Base 18.1 placed separately on the same bottom surface
a lifting hydraulic cylinder 18a supported on 9;
It consists of a horizontal motion fluid pressure cylinder 19a.

1st. The opposing end of the second removable hearth 11.12 is provided with a comb-shaped opposing end 20 that is uneven and interdigitated as shown in FIG. An intermediate extraction port 21 is provided in the side wall of the furnace body 3 corresponding to the portion 20 .

In the above configuration, heating of the hot steel billets conveyed from the continuous casting machine is carried out by charging them through the heating material charging port 4.

The hot steel billet is carried into the furnace by the hot billet charging roller 22, and transferred to the first movable hearth 1 by the crossbutcher 23.
1 and is positioned, the first movable hearth 11 is sequentially moved toward the extraction port 21 by a rectangular movement, that is, a conveyance cycle, depending on the rolling capacity, and during this time, the burner 8a is used to Heating takes place up to temperature.

In order to extract the steel pieces that have been heated to a predetermined temperature and have reached the intermediate extraction port 21 from the soaking area side, the second movable hearth 12 is first raised. Next, the first moving hearth 11 transports the steel pieces to the extraction position by rectangular movement and then stops at the level of the fixed hearth. Thereafter, an extractor (ejector) pushes one end of the steel piece to extract it from the intermediate extraction port 21 and feed it to the rolling side. (See FIG. 3(a)) At this time, if the extractor pushes the heat material charging roller 22 side slightly from the center of the steel billet, the steel billet will naturally move to the end face of the second movable hearth 12. Since it slides into contact with and is guided, reliable extraction work can be achieved.

When charging cold steel billets from the cold material charging port 5 and heating them, or charging surplus material, that is, hot steel billets from the hot material charging port 4 and heating them, temporarily If the hot steel slabs are sequentially conveyed from the continuous casting machine to the heating furnace side, the steel slabs in the furnace pass through the intermediate extraction port 21 and are heat-retained from the first moving hearth 11. It is transferred to the second movable hearth 12 in area 7, and when it is extracted again, it is extracted from the heat retention area side.

In this extraction operation, contrary to the above, the first moving hearth 11 is raised, and extraction is performed from the heat retention area side using the end face of the first moving hearth 11 as a guide. (See Fig. 3, mountain) At this time, the ejector shifts to the left in Fig. 1 from the position at the time of extraction from the soaking area side, and its pressing force acts on the guide surface. Do it like this.

When extracting steel billets from the soaking zone side, when the heat retention zone side is operating and taking in cold billets from the cold material charging port 5, first. As shown in FIG. 9, both the second removable hearths 11 and 12 move back and up from their operating origins, and then the second removable hearths 12 move forward to transfer the billets. The first movable hearth 11 is adjusted so that its forward movement is completed with a slight delay after the second movable hearth 12 completes its forward movement.

After the above operation is completed, the first moving hearth 11 is lowered to the level of the fixed hearth, and the steel pieces are extracted.

In addition, if the soaking area side is operating while extracting from the heat retaining area side, the first. The operation of the second removable hearth 11,12 replaces the operation described above.

Next, a method of using the comb-shaped facing portion 20 of the movable hearth when extracting steel pieces will be described.

FIG. 4 is an explanatory diagram of the use of the comb-shaped opposing end surfaces of the moving hearth.

In the figure, the tip surface T2 of the second moving hearth 12 is at its origin position, as shown in FIG. When piece A is placed at the extraction position, it is set to match one end surface of piece A, so when extracting pieces of steel, the second movable hearth 12 only moves up and serves as a guide for piece A. You get it.

If the end surface T1 of the first movable hearth 11 is set at a position apart from the end surface T2 of the second movable hearth 12 by the steel piece gap S, then the first movable hearth 11 will move from the second movable hearth When extracting the steel pieces B sent to the steel plate 12, the end surface T1 can serve as a guide for the steel pieces B when the first movable hearth 11 moves only upward.

That is, the mutual distance I in the furnace length direction between the end surface T1 and the end surface T2
If T, −T21≠S, when extracting the steel piece B, one of the first moving hearth or the second moving hearth is placed so that the end face of this steel piece comes into contact with the end face T2 of the first moving hearth 11. must first move back and forth, and then the first movable hearth 11 must perform an upward movement, which not only complicates the control system but also causes a delay in the extraction timing.

(Second Embodiment) FIG. 5 is a plan view of essential parts when the present invention is applied to a walking beam furnace.

As shown in the figure, on the central wall 24, the moving skid 25
．． By forming the ends of 28 in a staggered manner, the same effect as in the first embodiment can be expected.

Therefore, the operation of the first and second re-transfer skids 25 and 26 during heating of the billet in the furnace is similar to that of the first and second re-transfer skids 25 and 26 of the walking hearth furnace of the first embodiment. Second relocation hearth 11.12
Do the same as in the case of .

In order to extract the steel pieces, as shown in the figure, the first step is to extract the steel pieces. At the origin position of the second removable skid 25, 26, the distance IT between the end faces of the removable skid mentioned above, -T21-
If S is set, both the steel billet A and the steel billet B can be extracted while using the guide function without a complicated control system or time lag.

(Third Embodiment) As shown by the broken line in FIG. 1, a second flue 9a is provided in the soaking area.

In the heating furnace, the exhaust gas from the soaking zone 6 is used to preheat the air with a heat exchanger. However, if there is no material in the heat retention zone 7, the heat retention zone 7 has the same function as the flue, dissipating the sensible heat of the exhaust gas. There is.

That is, the exhaust gas temperature at the inlet of the heat exchanger decreases, and heat exchange deteriorates. In this case, if the second flue 9a is used, heat dissipation in the heat retention area 7 will be eliminated, and more efficient exhaust gas heat recovery can be expected.

Incidentally, if there is material in the heat retention area 7, naturally the flue 9 shown in the first embodiment is used.

(Other Examples) (al) The first movable hearth in the first embodiment on the soaking area side is divided into two or more divided configurations.

Here, the movable hearth on the side of the heating material charging port works in accordance with the operation of the continuous casting machine, and the movable hearth on the side of the extraction port can adjust the deviation in the operating timing of the rolling mill.

(bl In the soaking area, as shown in FIG. 6, a steel strip extraction port 21a is provided in the furnace wall opposite to the heating material charging port 4.

The temperature of the steel billet at the beginning of casting in a continuous casting machine is usually higher than that of other steel billets in the -charged portion. A steel billet extraction port 21a is provided for a bypass conveyance circuit for the hot steel billet.

That is, the hot steel billets sent from the continuous caster pass through the furnace from the charging port by hot material conveying rollers, are conveyed from the billet extraction port 21a, and are supplied to the rolling mill via a transfer or the like.

If this transportation is possible, ideal direct rolling with zero fuel consumption in the heating furnace is possible.

(C)゛ As shown in FIG. 7, a steel piece charging inlet 27 is provided only at one end of the furnace, and an intermediate extraction port 21 is provided in the middle of the furnace.

Both hot steel strips and cold steel strips are charged from one steel billet charging inlet 27, and if an imbalance occurs in the continuous caster-rolling function, the strips are passed through the soaking zone 6 once and then transferred to the heat retention zone. -7 and keep it in a heat insulated stock. When the rolling mill recovers, the moving hearth is operated in reverse and extraction is carried out from the heat retention area side through the intermediate extraction port 21.

Since there is only one charging port, operation and billet flow are
The equipment is simple.

(d) As shown in Figure 8, a steel piece loading inlet 27 is provided only at one end of the furnace, an intermediate extraction port 21 is provided in the middle of the furnace, and a steel piece extraction port is provided at the other end of the furnace. 21a is provided.

The material on the heat retention area side can be extracted from the steel billet extraction port 21a, thereby simplifying the flow of steel billets and simplifying drive control.

(Effects of the Invention) According to this invention, the hearth is divided into two or more places in the longitudinal direction, an intermediate extraction port is provided near one of the hearth divisions, and an intermediate extraction port is provided at the front and rear parts of the furnace. When extracting the steel billet charged from the billet charging inlet from the intermediate extraction port after heating, first raise one of the hearths, and then the billet rises to the end surface of the raised hearth. The steel piece is transferred until it touches the steel plate, and then stopped at a predetermined position, and the extractor is operated to extract the steel piece using the rising hearth end face as a guide.This ensures reliable extraction regardless of the type or size of the steel piece. This has made it possible to simplify operation control and improve the efficiency of ζ heat utilization.It has been implemented in direct rolling, which has rapidly developed in recent years, to efficiently convert hot steel billets produced by continuous casting machines. This is a remarkable invention that will be of great benefit to the industry, as it has a function of heating cold steel billets well at a warm temperature, stocking the billets in case of rolling troubles, and a heating function of raising the temperature of cold billets to a temperature at which they can be rolled.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a walking hearth furnace to which this invention can be applied, Fig. 2 is a plan view of the main parts, Fig. 3 (a), (bl
4 is an explanatory diagram of the operation, FIG. 5 is a plan view of the main parts of the application of the present invention to a walking beam furnace, and FIGS.
The figure is a schematic plan view of a furnace showing another embodiment, and FIG. 9 is an explanatory diagram showing the origin position of each movable hearth when divided into two. l... Concrete foundation, 2... Recess, 3... Furnace body, 4... Heat material charging port, 5... Cold material charging port, 6...
・Soaking area, 7... Heat retention area, 8a... Soaking area burner,
8b... Heat retention area burner, 9... Flue, 10... Fixed hearth, 11.12... Movable hearth, 13.14...
Drive mechanism, 15... Base, 15a... Inclined surface, 16
...Roller body, 17... Support, 18... Base, 1
8a...Fluid pressure cylinder for lifting, 19...Base,
19a... Horizontal dynamic fluid pressure cylinder, 20... Comb-shaped opposing portion, 21... Intermediate extraction port, 21a... Steel billet extraction port, 22... Hot billet charging roller, 23... - Crossbutton shear 124...Central wall, 25.26...Movement skid, 27...Steel shingle loading inlet. f, 4 Illustrations 6 Illustrations 5 Illustrations 11 lla

Claims (1)

[Claims] In a heating furnace such as a walking hearth furnace in which the hearth is divided into two or more places in the longitudinal direction and steel shingle charging inlets are provided at the front and rear parts of the furnace body, there is an intermediate space near at least one hearth division. An extraction port is provided, one of the hearths is first raised by vertical movement of the hearth, and then the other hearth is transferred until the steel pieces come into contact with the end face of the raised hearth. A method for extracting steel pieces in a walking type heating furnace, which comprises stopping at a predetermined position and extracting steel pieces by operating an extractor.