JPH02247328A - Walking beam-type heating furnace for material to be rolled - Google Patents

Abstract

PURPOSE:To prevent the nonuniform hating of a billet and to obviate the inverting of the billet when decarburized and transported in the walking-type heating furnace for the billet consisting of a preheating zone, a heating zone and a soaking zone by providing an upper-zone axial burner above a billet transporting beam in the heating zone and soaking zone. CONSTITUTION:A steel material 18 to be rolled (billet) is continuously heated to a rolling temp. by the walking beam-type heating furnace 1. The furnace 1 is comprised of a preheating zone 4, heating zone 5 and soaking zone 6 for the billet 18. Plural billets 18 are successively sent to the preheating zone 4 by a feeder 2, transported by walking beams 7 and 8 from the preheating zone 4 through the heating zone 5 separated by a partition wall 19 and the soaking zone 6 separated by a nose part 22, and discharged. In this case, the upper burner 12 is provided respectively to the heating zone 5 and the soaking zone 6, and the lower burner 13 is further provided to the soaking zone 6. Consequently, the billet 18 is uniformly heated and not inverted during the surface decarburization and transportation, and the billet is uniformly heated to the desired temp. and supplied to a hot rolling machine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a walking beam type (hereinafter referred to as VIB type) rolled material heating furnace.

Specifically, the present invention focuses on rolling material (hereinafter referred to as
For convenience of explanation, a heating furnace is capable of eliminating uneven heat of a billet (as an example, referred to as a billet), preventing billet bending or overturning during transportation due to the occurrence of bending, and preventing decarburization of the billet. In addition to these, it is an object of the present invention to provide a heating furnace which can actively promote thermal diffusion of the billet, eliminate the temperature difference between the outer surface and the inside, and also improve the quality of inclusions.

Hereinafter, for convenience, the present invention will be described with reference to a case in which wire rod rolling is performed by heating a billet, as an example.

[Prior Art] When performing hot rolling, it is well known that heating is performed in a heating furnace unless rolling can be performed using sensible heat in the previous step.

This heating furnace includes a type 18 heating furnace, a heating furnace that combines a WB and a WH (walking hearth), a butcher type heating furnace,
There are other methods, and it is well known that the billet is heated to a desired temperature by passing through a preheating zone, a heating zone, and a soaking zone in this order, without citing any publications.

There is no need to cite publications, but in order to prevent billet decarburization, it is necessary to make the atmosphere in the furnace difficult to decarburize, or to rotate the billet at a predetermined location and heat unevenly. It has also been proposed to solve this problem and prevent billets from falling during transportation due to bending in the longitudinal direction.

[Problems to be Solved by the Invention] However, at present, there is no conventional type 18 billet heating furnace that can achieve the following items.

■ Eliminate uneven heat generation during billet heating, prevent billet bending, and prevent billets from tipping over during the process of transporting them in the furnace using movable girders. ■ Reliably prevent billet surface decarburization. and based on this, it is possible to prevent deterioration of the surface quality of rolled products such as wire rods; ■ The temperature difference between the surface and the inside of the billet can be eliminated over the entire length of the billet in the cross-sectional direction of the billet immediately before rolling; ■ The above billet The internal quality of the material, for example, inclusions can be modified to make them harmless during plastic processing. ■ All of these ■ to ■ can be achieved.

Nowadays, the quality of products and finished goods has become even more sophisticated, and this has become a factor in determining the fashion (differentiation) of products and finished goods, so this is an issue that must be resolved.

In view of this background, the present invention solves the above-mentioned problems of the conventional technology.
It is an object of the present invention to provide a Type 18 billet heating furnace that can solve all of the problems.

In other words, the present invention aims to provide a type 118 rolled material heating furnace that exhibits the extremely remarkable unique effects listed below.

l) The billet can be heated while suppressing or preventing uneven heat.

2) Due to the above 1), the billet does not fall over during transportation in the furnace. Therefore, the surface properties (quality) of the billet are good, and the occurrence of troubles during furnace operation can be suppressed or prevented.

3) Billet can be heated while preventing or suppressing surface decarburization. Therefore, even in the case of a high carbon steel wire rod, for example, surface decarburization does not occur, so that the desired quality can be stably obtained even when the wire is drawn.

4) The heated billet further promotes thermal diffusion through heat retention, so temperature differences in the cross-sectional and/or longitudinal directions of the billet can be eliminated. It has excellent quality and internal quality, and can be produced stably.

5) According to 4) above, depending on the steel type (type based on quality standards), low melting point inclusions may be softened (transformed, modified) and rendered harmless during plastic working, improving wire drawability,
The quality after wire drawing can also be improved.

6) Since the heating furnace does not have a lower zone axial flow burner installed in the lower zone of the front zone consisting of the pre-heating zone and the heating zone, the equipment investment cost and furnace operating unit can be significantly reduced.

7) Since the movable girder in the front stage area consisting of the pre-heating zone and the heating zone can be of a non-cooled type, the so-called dry beam type, the drive mechanism can be small-scale, which contributes to a significant reduction in equipment investment costs and reduces maintenance of the heating furnace. Inspection becomes easier.

8) Based on 7) above, it is easy to achieve slow heating in the front stage region consisting of the pre-heating zone and the heating zone, and the prevention of surface decarburization of the billet can be stabilized.

[Means for Solving the Problems] In order to achieve these problems, the present invention is characterized by having the following configuration. Specifically, the first characteristic configuration of the present invention is a type 18 billet heating furnace. The pre-heating zone and the heating zone are separated by a movable partition wall, and a circulation fan is installed on the ceiling of the heating zone.
An upper belt axial flow firing burner is installed through the wall of the nose part above the movable girder, and the heating zone and soaking zone are distinguished by the nose part, and the furnace wall in the vertical direction centered on the movable girder is installed. It is constructed by providing an upper belt axial flow firing burner through it.

Further, the second feature of the present invention is that a heat retention furnace having a scale discharge port below the burner and the conveying means is provided in an area near the outlet of the soaking zone and the inlet of the rough rolling mill. That's a thing.

Furthermore, the third feature of the present invention is that the movable girders and fixed girders of the preheating zone and the heating zone are not cooled.

In the configuration of the present invention, the first characteristic configuration solves at least one of the above-mentioned specific technical problems.
, 2), 3), and 6) are necessary.

Further, the second characteristic configuration is necessary to achieve at least 4) and 5) of the specific technical problems described above.

Furthermore, the third feature of the configuration is at least one of the specific technical problems mentioned above. ), 8) is necessary.

Therefore, to achieve all the specific technical problems of l) to 8) above, it can be achieved by combining the configurations defined as the first feature, second feature, and third feature of the present invention. It is possible.

Therefore, the Type 18 billet heating furnace according to the present invention has a work standard that has been studied and determined based on, for example, JIS standards (Japanese Industrial Standards) for billets. Heating to 650-750℃ or less,
In the soaking zone, which is the latter stage, it is rapidly heated to 1050 to 1090°C. During these heatings, the top surface of the billet and
The surface in contact with the movable girder is heated to a temperature below 35°C, so no uneven heat generation is observed. Therefore, bending of the billet in the longitudinal direction rarely occurs.

In addition, the billet from the soaking zone is thermally diffused in a heat retention furnace to eliminate temperature differences in the cross section and/or longitudinal direction of the billet, and in some cases is modified so that low melting point inclusions become harmless to plastic processing. The wire rod is then supplied to a rough rolling mill via pinch rolls, and the wire rod can be rolled.

[Examples] The present invention will be described in detail below based on Examples. This example is
An example of an attempt at wire rod rolling is shown.

FIG. 1 is a schematic explanatory diagram cut in the furnace length direction of the heating furnace I according to the present invention, in which 2 is a charging device, 3 is a roller table, 4 is a preheating zone, 5 is a heating zone, and 6 is a soaking zone. , 7 is the t W
a (movable girder), 8 is the second W8 (movable girder) (the girder 8 is based on Japanese Patent Publication No. 50-31085), 9 is the extraction roller table, IO is the extraction straightening device, 11 is the fan, 12 is the 1 part band The axial burner 13 is a lower zone axial burner, and as shown in FIG. 2, a heat retention furnace 14 is provided through the extraction port 23 of the soaking zone 6.

FIG. 2 is a bird's-eye view of the heating furnace 1 in FIG. 1 viewed from the direction of the pinch rolls 15 in front of the rough rolling mill, and
A heat retaining burner 17 is attached to a cover 16 of the billet conveying means 20.
They are placed above and below the center. As shown in FIG. 3, which is an outline diagram cut in the furnace length direction, the inside of the billet conveying means 20, for example, a heat-resistant roller table, is provided, and a scale discharge port 21 is provided below the billet conveying means 20. 8 is a billet, 19 is a movable partition wall, 22 is a nose portion, and 24 is an opening/closing door.

Therefore, the temperature, atmosphere, etc. of the heating furnace 1 are maintained by the interaction of the upper zone axial flow burner 12, the lower zone axial flow burner 13, the fan 11, the movable partition wall 19, and other components.

Further, the heat retention temperature of the heat retention furnace 14 is maintained by the heat retention burner 17, and the atmosphere inside the furnace is maintained through interaction with other elements.

By the way, the extraction straightening device 10 in FIG. 1 is, for example, shown in FIG.
The section is shown in an enlarged cross-sectional plan view, and Fig. 4 (b)
It is constructed as shown in the cross-sectional view taken along the line 1-1' in FIG. 4(A).

That is, between the rolls of the extraction roller table 9, a plurality of extra cranes 25 each having a protrusion at the tip and performing rectangular movement, and a correction stopper 28 that can move forward and backward are individually arranged, and when the billet 18 is extracted, The billet 18 is compressed between the inner surface of the protruding portion of the extractor 25 and the front end surface of the correction stopper 26 which is not moving forward, and is then transferred onto the extraction roller table 9.

In addition, 27 is a fixed girder, 28 is a V-groove for placing billet I8, 29 is a traveling frame, 30 is a bearing, 31 is a driving sprocket, 32 is a guide rail, 33 is a movable cart, and 34a.

34b is a frame, 35 is a weight, 36 is a lifting cylinder attached to the extractor body 25, and 37 is a moving cart 3.
3 is a cylinder for forward and backward movement attached, and 38 is a pedestal erected on the traveling pedestal 29.

Such a heating furnace 1 is controlled at a temperature shown in the graph of FIG. 5, although it varies depending on the type of billet 18. In addition, the atmosphere inside the furnace is controlled to an atmosphere that does not affect decarburization.

In such a situation, the billet 18 is transferred to the charging device 2 in the preheating zone 4.
and is transported to the heating zone 5, which constitutes the front stage area, by the action of the first WB 7. At this time, the temperature inside the furnace in the front stage area is 750~
The temperature is 850°C. Further, the billet transferred to the soaking zone 6 in the subsequent stage area is soaked to 1050 to 1090°C by the action of No. 21B8.

The upper surface of the billet 18 in these front stage areas and rear stage areas,
Preheating → heating → soaking is performed while maintaining the temperature difference between the lower surface in contact with the conveying means (first WB, second WB) at 35 deg, t: or below.

Therefore, since uneven heat is not generated in the billet 18, the billet 18 does not bend in the longitudinal direction, and therefore does not fall over due to interaction with the movement of the 1118th and second WBs, and can move smoothly in the furnace. Further, since the billet 18 is heated slowly in the first stage region consisting of preheating and heating, and rapidly heated in the second stage region by soaking, decarburization near the surface layer of the billet 18 can be prevented.

The billet 18 in a soaked state with both internal and external quality maintained in this way is extracted from the extraction roller table 9 through the extraction roller table 9 by the action of the extraction straightening device 10. At this time, if a slight bend occurs in the longitudinal direction of the billet 18, the extraction straightening device lO
A plurality of extractors 25 protrude and adjust the distance,
The billet 18 is corrected by interacting with the correction stopper 26 to straighten the billet 18.

That is, a specific method for extracting and straightening the billet 18 from the heating furnace 1 using the extraction roller table 9, the extractor 25, and the straightening stopper 26 constructed as described above is as follows.

First, based on the extraction command, the traveling platform 29 is navigated,
The V groove 39 of each extraction roller of the extraction roller table 9,
For example, the V 28 of the extractor 25 is positioned at the first strand position and at the lower rear position of the billet 18 to be extracted by the forward/backward cylinder 37 of the movable trolley 33, and then the tip protrusion is positioned by the lifting cylinder 36. part 4o and positioned at the rear of the billet 18. At the same time, the correction stopper 26 is advanced a predetermined distance, and the billet! 8 to the protrusion 4o of the extractor 25
The correction stopper 26 is positioned between the inner surface and the front surface of the correction stopper 26.

In this state, the extractor 25 is moved backward by the cylinder 37 for forward and backward movement, pinching the billet 18, and
That is, the billet 18 is connected to the protrusion 40 and the correction stopper 26.
By pressurizing the billet 18 from both sides, the heated surface or skew of the billet 18 is corrected.

Note that in this state, the billet 18 is placed on the fixed beam 27. Then, the straightening stopper 26 returns to its original position, and the extractor 25 further rises, picks up the billet 18 onto the V-groove 28, and retreats until the billet 18 is above the first strand position. By descending, the billet +8 is transferred onto the V-groove 28 of the extraction roller table 9.

Furthermore, when the extractor 25 descends and retreats,
Each extraction roller of the extraction roller table 9 rotates at high speed to extract the billet 18 out of the furnace. When the billet 18 is extracted outside the furnace, the extraction roller table 9 switches to low speed rotation, the traveling frame 29 retreats, and the extraction roller table 9, extractor 25 and straightening stopper 2
6 retreats to the standby position (inside openings H, , H7, and H3),
Prepare for the next extraction command.

Then, in response to the next extraction command, the billet 18 is extracted outside the furnace in the same manner as described above, but at this time, if the extraction command is for the second strand, the extraction roller table 9 is located at the second strand position, and the extractor 25 is Correction stopper 26
The extractor 25 straightens the billet 18 in the same manner as described above, and after receiving the billet 18, the extractor 25 retreats to above the second strand position and repeats the same process five times or more to straighten and extract the billet 18 out of the furnace. The billet 18 is conveyed from the extraction port of the soaking zone 6 onto a conveyance means in the heat retention furnace 14 by the extraction roller table 9 and guided into the furnace.

The temperature inside the heat retention furnace 14 is maintained within the range shown in the graph of FIG.
Or eliminate the temperature difference in the longitudinal direction.

Also, depending on the billet 1B quality standard (JIS),
Low melting point inclusions may be modified (transformed) into harmless inclusions during plastic processing.

The heat-retained billet 18 is supplied from the outlet of the heat-retaining furnace 14, which opens and closes at a minimum, to a plurality of rolling mill rows via pinch rolls 15, and is rolled into a wire rod. What was attempted in such an embodiment will be described below.

(1) Test material wire steel type Japanese Industrial Standards (JIS) G component (weight%) (: : 0.82, Mn: 0.52, Si
: 0.20, s: o, ooa, P: 0.0
15 Cross-sectional dimension 0.5m/m Rolling amount 10t (2) Test results The temperature inside the furnace in the front stage area is 750-850℃, the temperature inside the furnace in the latter area is 1150-1190℃, and the heat retention temperature is 1170-11
The temperature was 90°C. As a result, the surface decarburization of the rolled wire rod was significantly improved, and when the wire rod was drawn, it was good and the wire breakage rate was significantly improved.

[Effects of the Invention] As described above, the present invention achieves the technical problems of the present invention described above, and exhibits the extremely remarkable unique effects listed below.

1) Billets can be heated while suppressing or preventing uneven heat.

2) Due to the above 1), the billet does not fall over during transportation in the furnace. Therefore, the surface properties (quality) of the billet are good, and the occurrence of troubles during furnace operation can be suppressed or prevented.

3) Billet can be heated while preventing or suppressing surface decarburization. Therefore, even in the case of a high carbon steel wire rod, for example, surface decarburization does not occur, so that the desired quality can be stably obtained even when the wire is drawn.

4) The heated billet further promotes thermal diffusion through heat retention, so temperature differences in the billet's cross-sectional direction and/or longitudinal direction can be eliminated. It has excellent quality and internal quality, and can be produced stably.

5) According to 4) above, the steel type (type based on quality standards)
In some cases, the low melting point inclusions can be softened (transformed, modified) and rendered harmless during plastic processing, and wire drawability and quality after wire drawing can also be improved.

6) Since the heating furnace does not have a lower zone axial flow burner installed in the lower zone of the front zone consisting of the pre-heating zone and the heating zone, the equipment investment cost and furnace operating unit can be significantly reduced.

7) Since the movable girder in the front stage area consisting of the preheating zone and the heating zone can be made into a non-cooled type, the so-called dry beam type, the drive mechanism can be small-scale, contributing to a significant reduction in equipment investment costs, and
Maintenance and inspection of the heating furnace will also become easier.

8) Based on the above 7), it is easy to achieve slow heating of the front stage region consisting of the pre-heating zone and the heating zone, and the prevention of surface layer decarburization of the billet can be stabilized.

[Brief explanation of drawings]

Each of the drawings shows one embodiment of the present invention.
The figure shows an overview of the heating furnace cut in the furnace length direction, Figure 2 is a perspective view of the heating furnace seen from the rough rolling mill side, and Figure 3 shows the heating furnace cut in the furnace length direction. Explanatory diagram showing the outline, Part 4
Figure (a) is an enlarged cross-sectional plan view of the extraction straightening device, Figure 4 (b) is a sectional view taken along arrow I-1' in Figure 4 (a), and Figure 5 is a heating furnace operating temperature. This is a graph showing. DESCRIPTION OF SYMBOLS 1...Heating furnace, 2...Charging device, 3...Roller table, 4...Pre-heating zone, 5...Heating zone, 6...
Soaking zone, 7...1st WB (movable digit), 8-...2nd WB (movable digit), 9...Extraction roller table, 1
0...Extraction straightening device, Il...Fan, 12...
Upper zone axial flow burner, 13...Lower zone axial flow burner, 14
- Heat retention furnace, 15... Pinch roll, 16... Cover, 17... Heat retention burner, 18... Billet, 1
9--Movable wall, 20--Billet conveyance means, 2
1-...Scale discharge port, 22...Nose part, 23-
...Exit, 24--Opening/closing door, 25--Extractor, 26--Correction stopper, 27--Fixed girder, 28
-... V groove for billet placement, 29... Traveling frame, 3
0 - Bearing, 31... Drive sprocket, 32...
・Guide rail, 33-...Movable trolley, 34a, 34b
- Frame, 35... Weight, 36... Cylinder for lifting and lowering, 37... Cylinder for forward and backward movement, 38-... Frame, 3
9-... V groove of extraction roller, 40... Tip protrusion of extractor L

Claims (1)

[Claims] 1. In a walking beam type rolling material heating furnace, a pre-heating zone (4) and a heating zone (5) are separated by a movable partition wall (19), and circulation is provided on the ceiling of the heating zone (5). A fan (11) is provided, and a nose part (2) is provided above the movable girders (7) and (8).
The upper zone axial flow burning burner (12) is installed through the wall of 2), and the heating zone (5) and the soaking zone (6) are connected to the nose section (2).
22), and the upper band axial flow burner (1
2) A walking beam type rolling material heating furnace characterized by being configured by providing the following. 2. A heat retention furnace (14) having a scale discharge port (21) below the burner (17) and the conveying means (20) is installed near the outlet (23) of the soaking zone (6) and the inlet of the rough rolling mill. The walking beam type rolling material heating furnace according to claim 1, characterized in that the walking beam type rolling material heating furnace is provided in a section. 3. The walking beam type rolling material heating furnace according to claim 1 or 2, characterized in that the movable girders (7) and fixed girders of the preheating zone (4) and the heating zone (5) are not cooled.