JP3182820B2 - Hot rolling equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot strip rolling plant, and more particularly to a hot rolling plant having a rough rolling mill having a small material temperature drop and a short installation space.

[0002]

2. Description of the Related Art Conventionally, regarding the arrangement of a rough rolling mill, various studies have been made in addition to the existing hot strip mill arrangement drawings, and many publications and patent applications based thereon have been made.
The hot strip mill equipment arrangement in Japan is described in “Recent Hot Strip Manufacturing Technology in Japan” published on August 10, 1987 by the Iron and Steel Institute of Japan.
According to 87-P190 (Mill Layout), the equipment where the distance between the coarse rolling mills is the shortest is 11m between R3 and R4 of Nippon Steel Oita. The material is rolled in only one direction in an arrangement called. However, in many cases, R3 and R4
It is not possible to obtain a rough bar of a desired thickness from a slab of a predetermined thickness in the rolling at one time. In the case of Oita, two rough rolling mills R1 and R2 are arranged upstream of the rolling mills R3 and R4. In fact, R2 is a reversible rolling mill, which usually performs three passes of rolling, and a total of six passes of rough rolling to roll to a predetermined coarse bar thickness. Therefore, even if two rough rolling mills are arranged close to each other, it is necessary to install other rough rolling mills unless the reversible type is used, and the effect of shortening the entire installation space is small.

An example in which two rough rolling mills are arranged close to each other to perform reversible rolling is described in a US journal "IRONAND STEEL ENGINEE".
R "May 1976, pp. 48-52, reports the results of desk studies and studies based on simulation results. According to this known example, in the conventional perfect continuous type, six horizontal rough rolling mills are arranged, and the distance between R5 and R6 is about 11 m.
As a separated closed couple type, the arrangement length between the heating furnace and the crop shear was 350 m, and the two furnaces were reversibly rolled with two quadruple rough rolling mills at an interval of 26 m. Arrangement length between crops 277m
It is reported that the total cost, including mechanical, electrical and construction costs, can be reduced by about 20% to 77% of the conventional cost. According to the same paper, the advantage of adopting this method is that, compared to equipment that performs reversible rolling with one roughing mill, another roughing mill is additionally installed close to the existing roughing mill. Simplifies expansion to increase production volume.

[0004]

As a result of the study by the inventors of the present invention, the above-mentioned known examples have the following problems, and the objects of the present invention corresponding to the respective problems will be described.

First, descaling will be described. In general, an iron oxide film is formed on the surface of a steel sheet to be hot-rolled, and when rolled as it is, a hard oxide scale is embedded in the base material and becomes a flaw on the surface of the steel sheet. Therefore, descaling is usually performed by spraying high-pressure water before the material is caught in the horizontal roll. However, in order to sufficiently obtain the descaling effect, it is necessary to spray high-pressure water of a certain amount or more, which causes a decrease in the temperature of the material. The above-mentioned known example also describes that it is necessary to provide a descaling device before and after each pass of two rough rolling mills arranged close to each other and to spray high-pressure water at the entrance of each horizontal pass or the width rolling performed immediately before the horizontal pass. There is.
That is, in the case where the pressure is reduced six times by two changes of direction, it is necessary to spray the descaling water six times, and it is necessary to extract the material from the heating furnace at a high temperature in anticipation of the temperature decrease of the material caused thereby. There is a problem. A common object of all claims of the present invention is to shorten the distance between two rough rolling mills and omit spraying of descaling water between the rolling mills.

[0006] Second, the problem of bending of the material will be described. In a normal rolling mill in which material is independently rolled at each stand, guiding of the rough bar to the center of the rolling mill with a side guide at the entry side of each pass allows the coarse bar to be bent within a certain allowable range. In the above-mentioned known example in which rolling is performed on two stands at the same time, as shown in FIG. Center deviation (dc), which further promotes the bending of the coarse bar. Large bends caused by this cause problems such as impairment of productivity such as drawing in a finishing mill and deterioration of product quality. A common object of all claims of the present invention is to suppress the bending caused by the two rough rolling mills.

Generally, in the case of a rough rolling mill, the side guide on the material entry side of the rolling mill is set to be about 100 mm to 140 mm wider than the sheet width. Ideally, this should be set equal to the plate width for the purpose of allowing the material to bite into the center of the mill, but if the gap is small and the friction between the side guide and the plate is large, This is an empirically determined set amount for reasons such as slippage between the table roller and the plate. Conversely, the off-center of the plate is allowed up to about 1/2 mm = 70 mm of the side guide width margin maximum setting value of 140 mm, but if it is larger than that, the bending of the plate becomes large, and there is a problem in the quality of the product in operation. This is because many things are known empirically.

On the other hand, when tandem rolling is performed in a rough mill, the material is caught in the front stand before the material comes out of the rear stand. Centering is difficult because it is rolled by the work roll described above, and after all, it has to be rolled off-center by the amount of plate bending generated at the front stand.

In other words, in the case of tandem rough rolling, it is preferable to suppress the bending at the rear stand to within 70 mm. However, for the reason described later, a conventional 4H mill is arranged at an interval of about 11 m. In some cases, it may be difficult depending on the rolling conditions. The purpose of the present invention is
A hot rolling facility that can house two rough rolling mills in a short space, omit descaling between the rough rolling mill stands, and reduce the meandering amount of the plate to 70 mm or less even in the final pass of rough rolling. To provide.

[0010]

The hot rolling equipment according to the present invention is a hot rolling equipment comprising at least a rough rolling mill group and a finishing rolling mill group .
It is composed of two double roughing mills or two double reversible roughing mills for continuously rough rolling the rolling material, and the distance between the two rough rolling mills is within 6 m. It is characterized by the following. Or, at least, in the hot rolling mill composed of mill group finish the rough rolling mill group, a part of the rough rolling mill group, two 2-high to rough rolling a continuously rolling material
Consists of two rough rolling mills or two reversible rolling mills,
The two rough rolling mills are configured by storing two sets of work rolls in one mill housing. The technical means employed to achieve the above object will be described in accordance with the above object commonly stated in each claim.

First, in order to omit de-scaling between stands, the distance between the stands is made as short as possible, and the scales formed between these stands are formed in such a short time that they do not interfere with rolling. Achieved by starting rolling on the stand.

Further, by storing two work rolls in one mill housing as described in claims 3 and 4, the interval between rolling can be further reduced. Further, by using a double rolling mill, two work rolls can be easily housed in one housing.

Secondly, even in the case of a tandem type rough rolling mill, the above-mentioned object of suppressing the bending of the rough bar to be rolled by the rolling mill is achieved by making the rolling mill a double rolling mill which hardly bends. You.

Here, the concept of the parallel rigidity of the mill is introduced to explain that the bending of the plate in the double rolling mill is smaller than that in the quadruple rolling mill. This will be described with reference to the schematic diagrams of the mill shown in FIGS. Rolling position difference S _df = S _OP −S _DR on the operation side and driving side, rolling force difference P _df = P _OP −P _DR
The ratio of

[0015]

(Equation 1)

[0016] and represents a parameter representing a tortuous difficulty mil referred to as parallel stiffness mil K _l. Also,
Each parallel stiffness K _l of a double rolling mill, quadruple rolling mill with a spring constant of the mill of each part

[0017]

(Equation 2)

## EQU1 ##

[0019] Here, K _h: housing the spring constant K _R: the value of a typical hot mill the value of each K _l of a material - the work roll between the spring constants of these formulas: spring constant per roll between unit width K _RO When calculated with a double rolling mill K _l = 220ton / mm 4 double rolling mill K _l = 70ton / mm, and the double rolling mill to have a 3-fold or more parallel rigid quadruple rolling mill Understand. FIG. 8 shows the result of calculating the bending of the plate using this value. As the disturbance, the off center of the plate on the entry side was assumed to be 50 mm. This corresponds to a case where the side guide is set to have a plate width plus 100 mm. As described above, in the case of rough tandem rolling, it is difficult to center the plate using the entry side guide at the rear stand due to the restraint of the front stand. It is preferable that the guide set value to be taken is 1/2 of the plate width plus 140 mm, that is, 70 mm or less, in terms of the passing property. In order to satisfy this condition even in a rough final pass where a large bend occurs, it is necessary to use a double rolling mill as shown in FIG. 8 and to set the distance between the stands within 6 m.

[0020]

By arranging two rough rolling mills at a short interval from each other, it is possible to bite into a succeeding stand in a time in which no oxide scale is generated on the material surface after rolling in the preceding stand. I have. In order to arrange these two rolling mills at a short distance, each rolling mill is made into a double type and housed in a space shorter than a quadruple type. Alternatively, they can be arranged closer to each other by implementing the contents of the claims of the present invention, such as storing two work rolls in one mill housing. Further, the double rolling mill has a higher parallel rigidity of the mill than the quadruple rolling mill, and is based on the effect that the bending can be suppressed to a small value even in a closed couple type rough mill in which the bending of the material is originally likely to occur.

[0021]

FIG. 1 shows an embodiment of the present invention. Two double reversible rough rolling mills 2 and 3 are provided on the downstream side of the heating furnace 1, and side guides 5 and 6 are provided on the upstream side of the upstream side 2 and the downstream side of the downstream side 3 of the rough rolling mill, respectively. Deploy. Further, on the downstream side, a crop shear 7, a bar joining machine 8, a bar looper 9, a finishing mill group 10, a divided flying shear 11, and a down coiler 12 are further disposed on the downstream side. The slab 16 heated to about 1200 ° C. in the heating furnace 1 guides the material 13 to the center position in the width direction of the work roll 4 of the rough rolling mill 2 by the side guide 5 on the upstream side, and forms a coating of iron oxide on the surface of the material. To high-pressure water (usually about 150 kg / cm ² )
After being removed by the spray 13 described above, the material is rolled by the rough rolling mill 2 and then by the rough rolling mill 3, and once the material passes through the rolling mill 3, the material is temporarily stopped. Then, after the center of the material is again aligned with the center of the rolling mill 3 by the side guide 6, the oxide film that has grown again after the descaling operation is removed again by the high-pressure water spray 14, and then the direction opposite to the rolling step is reversed. Are rolled in the order of rolling mills 3 and 2 while feeding the material. Further, after the same process, the rolling is performed in the order of the rolling mills 2 and 3, and after rough rolling of 6 passes is convenient,
A coarse bar having a predetermined thickness (usually around 30 mm) is obtained. afterwards,
After the material sent further downstream is sheared by the crop shear 7 at the front and rear end irregular portions (generally called fish tail and tongue), after the leading end of the material reaches the joining machine 8, the material has already been passed through the finishing mill 10. After joining the tail end of the preceding material from which rolling has begun and continuously removing the oxide film once again through the looper 9 by the high-pressure water spray 15, the finishing mill group 1
It is sent to 0. After finish rolling, the material is cut to an appropriate length by the split flying shear 11 and the down coiler 1
It is wound up at 2. This embodiment is particularly suitable when the equipment length is desired to be reduced, but the production amount is not so required.

FIG. 2 shows an embodiment in which the rough rolling mills 2 and 3 of this embodiment are housed in one housing. Two sets of work rolls 23 and 24 are housed in the housing 20, and a lowering force is applied by a piston 22 disposed in a hydraulic jack 21 through a work roll chock 25 and 26, and a lower side by a pass line adjusting device 27. Adjust the height. Material 16
Is fed into the mill by a feed roll 28 from the right side of the figure, and is first rolled by a pair of work rolls 23 and then by a work roll 24. If further reverse rolling is required, the material 16 once stopped on the left side of the drawing is transferred to the work rolls 24,2.
3. Roll in the order of 3.

Another embodiment having the structure shown in FIG. 1 will be described.
In the present embodiment, the material 16 heated in the heating furnace 1 is rolled only once in each of the rolling mills 2 and 3, and a rough bar is obtained through two rough rollings for convenience. This embodiment is particularly suitable for obtaining a coarse bar in a short time without significantly lowering the temperature of the material, when the coarse bar thickness is large and a large number of rough rollings are not required.

In another embodiment according to the configuration of FIG.
The material 16 is rolled by reciprocating the mills 2 and 3 for 2.5 times in a method that can be adopted in the case where a rough bar having a desired thickness cannot be obtained even by the rough rolling of 6 passes as described above. Rough rolling of the pass is usually unnecessary, and the temperature of the material is greatly reduced. Therefore, the first two passes, that is, the first pass of each of the rolling mills 2 and 3, are not reduced and no descaling is performed as a dummy pass. This is effective when the material 16 can be reduced by the remaining eight passes to obtain a coarse bar having a desired thickness. Another embodiment will be described with reference to FIG. This embodiment is an example in which a rough mill 17 is disposed upstream of the crop shear 7 in addition to the configuration of the embodiment described in FIG. A rough bar is obtained after rolling by a rolling mill 17. The present embodiment is particularly suitable for a facility where it is desired to increase the production amount even if the facility length is increased to some extent.

Further, in the configuration of FIG. 6, an embodiment using various paths as described with reference to FIG. 1 can be considered, and a combination of the above-described coarse mills shown in FIG. Is also possible. According to the present embodiment, the following effects are obtained.
There is fruit. First, the effect of maintaining the temperature of the rolled material is described.
You. FIG. 7 shows an example of the simulation results of the present inventors.
It is shown. In the present invention, between two rough mills
The distance between the stands as close as possible
After the rough rolling of 6 passes by omitting the spray
A heat retention effect of about 80 ° C. is obtained. This allows the heating furnace to exit.
Reduce furnace temperature (1150 ° C in this simulation)
Not only saves energy, but also
Saving ring water can save power for descaling pumps
There are many merit in energy saving aspects such as lengthening. Second, double
By configuring a rough mill with a rolling mill,
Simulates the effect of suppressing bending
Explanation will be made quantitatively using the result of the operation. Figure as described above
8 is a simulation assuming the first rough mill.
You. Considering the coarse first pass as a representative, the board width is 1500 mm ,
Pass schedule with entrance side thickness 293mm and exit side thickness 240mm
And the rolling load is 2124 tons. Initial plate as disturbance
Deviation (off center distance from mill center to plate center) 50mm
And investigate how the meandering amount increases when
It was done. As shown in the above formula, a quadruple rolling mill
Then the spring between the work roll and the backup roll is
Therefore, the parallel rigidity KL is small and the amount of meandering is further increased.
It's easy to do. In the example of FIG. 8, the position of the subsequent stand is temporarily
6H, 4H when biting into the following stand
In a mill, the meandering amount is about 63 mm, whereas in a 2H mill,
Is about 54mm, a slight increase from the initial off-center amount of 50mm
Stays on. As you can see, the 2H mill is inherently meandering
The direction is small and a rough rolling mill is constructed with two 2H mills as in the present invention.
The effect of suppressing the bending of the coarse bar
is there. In addition, this effect allows the subsequent bar joining machine to join
Productivity, such as improvement in the reliability of drawing and reduction of drawing in the finishing mill
The effect that contributes to operational stability is significant.

[0026]

According to the present invention, the following effects can be obtained.

According to the present invention, two rough rolling mills
It is possible to reduce the meandering amount of the plate to 70 mm or less even in the final pass of the rough rolling , by storing it in a pace and eliminating the descaling between the rough rolling mill stands.

[0028]

[0029]

[Brief description of the drawings]

FIG. 1 is a layout view of equipment of a hot rolling equipment according to one embodiment of the present invention.

FIG. 2 is an explanatory view of a rough rolling mill according to another embodiment of the present invention.

FIG. 3 is a plan view and a side view schematically showing bending of a plate in a conventional rough rolling mill.

FIG. 4 is a front view of the quadruple rolling mill as viewed from an entrance side (or an exit side).

FIG. 5 is a front view of the double rolling mill as viewed from an entry side (or an exit side).

FIG. 6 is a layout plan of a hot rolling facility according to an embodiment of the present invention.

FIG. 7 is a characteristic diagram of a simulation result showing the effect of maintaining the temperature of the material of the present invention.

FIG. 8 is an explanatory diagram of a simulation result on a bending suppressing effect of the material of the present invention.

[Explanation of symbols]

1 ... Heating furnace, 2,3 ... Rough rolling mill, 7 ... Crop shear,
8 joining machine, 10 finishing mill, 11 split shear, 1
2 ... down coiler, 13-15 ... descaling spray header, 23, 24 ... work roll.

Continuation of the front page (56) References JP-A-60-170518 (JP, A) JP-A-60-154809 (JP, A) JP-A-3-23006 (JP, A) JP-A-52-54648 (JP) JP-A-58-25802 (JP, A) JP-A-50-152958 (JP, A) Japanese Patent Publication No. 49-2272 (JP, B1) Edited and published by The Iron and Steel Institute of Japan Hot Strip Manufacturing Technology ”(August 10, 1987), pp. 187-190, especially“ Nippon Steel Yawata ”and“ Shinko Kakogawa ”lines. (58) Fields surveyed (Int. Cl. ⁷ , (DB name) B21B 1/26 B21B 13/00-13/02

Claims (2)

(57) [Claims] 1. A least, in the hot rolling mill composed of mill group finish the rough rolling mill group, a part of the rough rolling mill group, the 2-high to rough rolling a continuously rolling material 2 Of
Roughing mill or constitute a double reversible two rough rolling machine, hot rolling equipment, characterized in that within 6m the distance of the two rough rolling mills each other. 2. at least, in the hot rolling mill composed of mill group finish the rough rolling mill group, a part of the rough rolling mill group, the 2-high to rough rolling a continuously rolling material 2 Of
It is characterized by comprising a rough rolling mill or two rough reversing mills of a double reversible type , wherein the two rough rolling mills are constructed by storing two sets of work rolls in one mill housing. Hot rolling equipment.