RU2768955C1 - Method of producing strip metal and apparatus for implementing said method - Google Patents

Abstract

FIELD: metallurgy.SUBSTANCE: invention relates to metallurgy and can be used for production of strip metal. Casting is cast in a casting machine equipped with a crystallizer to obtain a workpiece and a rolling device with rollers located behind the crystallizer, and a pulling unit located behind said rolling device, which are selectively adjusted when the thickness of the strip metal is changed to provide a controlled action to reduce the thickness of the casting coming out of the crystallizer.EFFECT: invention makes it possible to modulate and control the reduction of thickness depending on the final thickness of the strip, making it possible to balance the reduction in thickness depending on the final thickness of the strip, allowing to balance the reduction of thickness partially in the casting machine and in the rolling mill, as well as to reduce rolling forces in the rolling stands.12 cl, 22 dwg

Description

The field of technology to which the invention belongs

The present invention relates to a method for the production of strip metal and to a plant for implementing this method.

The proposed method allows, in particular, to determine the modes for producing strip metal and the layout of the installation for the production of hot-rolled strip metal.

Prerequisites for the creation of the invention

Plants for the production of strip metal are known in the metallurgical industry, which usually have a mold capable of casting blanks in it, extracting devices configured to remove the blanks from the mold, and a rolling line, which is located behind the extracting devices and is made with the ability to reduce the overall thickness of the workpiece to obtain strip metal of the desired thickness.

It is known that, depending on the thickness of the strip metal to be produced and on the overall productivity to be achieved by the plant, the entire plant is suitably configured to meet the required parameters, at least in terms of plant output and strip thickness values.

It is known that, in accordance with the above requirements, the customer is supplied with continuous plants, semi-continuous plants, for example coil-to-coil and/or semi-continuous, or combined continuous and semi-continuous plants.

Continuous machines ensure that the casting is fed directly from the mold and fed to the rolling line without cutting it up to the last turn.

In semi-continuous installations, the casting is cut to size behind the casting machine or roughing stands and placed in a heating and/or holding furnace, which is also used as a casting store, for example, when it is necessary to suspend subsequent rolling in the event of minor malfunctions or a planned change of rolls .

If, behind the casting machine or the roughing stands, the casting is cut to such a length that at the end of the rolling process one coil is obtained, then such a process is called ''coil to coil''. And if the casting is cut to such a length behind the casting machine or roughing stands that at the end of the rolling process several, usually from two to five, turns are obtained, then such a process is called semi-continuous.

It is also known that, by suitable non-standard techniques, a semi-continuous plant can be modified in such a way that it will operate in a continuous mode, providing the advantages of this solution.

The choice of plant type and the number of components required, such as the number of rolling mill stands, or the choice of the number of roughing stands and finishing stands, is usually based on the experience of those skilled in the art.

However, this choice, i.e. the preparation of a strip production plant, does not always lead to an optimal compromise between capital investment and operating costs. Therefore, there are situations when the investment in the construction of the installation is too large compared to the income, and therefore the installation is delivered with a capacity greater than the customer needs, or there are situations when the installation is undersized and therefore cannot provide the performance desired by the client.

Some known methods and plants for the production of strip metal, which, however, have the problems described above, are described in documents WO 92/00815 A1, JP S62 248542 A and WO 02/40201 A2.

Therefore, the object of the present invention is to provide a properly sized plant to suit the needs of a customer who is carrying out a process for producing hot-rolled strip metal, such as steel, so that the performance of the strip production plant is optimized with as few stands as possible while maintaining maximum casting speed. machine (casting speed) in relation to different types of steel.

Another object of the invention is to provide a plant for the production of hot rolled strip metal, requiring limited capital investment and low operating costs compared to known plants for the production of strip metal of the same thickness.

Yet another object of the present invention is to provide a plant and improvement of a corresponding method for the production of hot-rolled strip metal, with the possibility to selectively vary the thickness of the cast billet relative to the final thickness of the strip.

Yet another object of the present invention is to provide a method for the production of strip metal, which makes it possible to obtain a plant which is very flexible and suits the specific requirements of the customer.

Yet another object of the present invention is to provide a strip production plant that is competitive in the market.

To overcome the shortcomings of the prior art and to achieve the above and other objects and advantages, the applicant has developed, tested and implemented the present invention.

Brief description of the invention

The present invention is set forth and characterized in independent claims, while dependent claims describe other characteristics of the invention or variants of the main inventive idea.

In accordance with the above objects of the invention, the proposed method for the production of strip metal includes the step of casting metal using a casting machine equipped with a mold to obtain a billet, and the step of hot rolling this billet in a rolling mill to obtain strip metal of various thicknesses.

During the casting stage, the casting machine acts on the casting by reducing its thickness as it exits the mold.

According to one aspect of the invention, the casting machine is optionally adjusted each time the thickness of the strip changes in order to change the effect of the machine on the casting as its thickness decreases.

In particular, the proposed method includes, with the same dimensions of the mold, at least the first stage, in which the first strip having the first thickness is produced, while using the casting machine, the first degree of reduction in the thickness of the casting is provided and at least the second stage, in which producing a second strip having a second thickness less than said first thickness, wherein the casting machine provides a second casting thickness reduction degree different from the first casting thickness reduction degree; the casting thickness reduction ratio is defined as the difference between the thickness of the casting exiting the mold and the thickness of the billet exiting the casting machine, relative to the thickness of the casting exiting the mold.

This solution makes it possible to modulate the thickness of the blank leaving the casting machine as a function of the final thickness of the strip, which increases the efficiency of the strip production plant and the quality of the resulting strip.

The present invention in some applications makes it possible, while maintaining the same productivity as the known plant, to reduce the number of rolling mill stands by at least one unit. This determines the economic advantages of the entire installation.

The reduction in the thickness of the strip obtained in each case is carried out partly in the casting machine and partly in the rolling mill, thereby increasing the efficiency and quality of the strip produced.

If, at the same productivity, the number of rolling stands is essentially the same as that of the known plant, then the invention in any case makes it possible to reduce the number of compressions during rolling, since the reduction in thickness is partially carried out directly in the casting machine, and not completely in the rolling mill, as is the case in the state of the art.

By reducing the compression pressure of the rolled workpiece, this technique saves energy and produces a higher quality strip, because, for example, its profile and flatness are improved and the risk of scale being pressed into the surface of the strip is reduced.

In addition, the present invention makes it possible to reduce the frequency of maintenance, at least in relation to the rolling mill.

Brief Description of Attached Graphics

These and other characteristics of the invention will become clear from the further description of some embodiments of its implementation, without limiting the scope of the invention, with reference to the attached drawings (drawings).

In the accompanying drawings of FIG. 1 in FIG. 9 illustrates several possible embodiments of a plant for the production of strip metal according to the proposed method.

In FIG. 10 shows curves plotted for the thickness H of the casting exiting the mould; shows the change in the degree of reduction in the thickness of the casting provided by the casting machine, depending on the thickness of the strip.

In FIG. 11 shows curves plotted for the thickness H of the casting exiting the mould; shows the change in the degree of reduction in the thickness of the casting provided in the pull unit, depending on the thickness of the strip.

In FIG. 12 graphically shows the selection criteria for rolling conditions.

In FIG. 13 graphically illustrates other criteria for selecting rolling conditions with respect to strip thickness and throughput of the flow chart in order to decide in favor of one and/or other rolling conditions.

In FIG. 14 and FIG. 15 shows correlation curves between nominal billet thickness and machine productivity and casting speed; both schedules refer to the operation of the installation in the amount of 7200 hours/year.

In FIG. 16 is a graphical representation of the correlation between the degree of thickness reduction and the number of rolling stands.

In the accompanying figures of FIG. 17 in FIG. 22 shows two exemplary embodiments of the present invention.

To facilitate understanding, the same reference signs have been used for identical common elements in the figures to the extent possible. It should be clear that the elements and characteristics of one option can be introduced into other options without further explanation.

Detailed description of some embodiments of the present invention

The following describes in detail various embodiments of the present invention, some of which are shown in the accompanying figures. Each of these options is illustrative and does not limit the scope of the invention. In particular, features shown or described for one embodiment may also be used in other embodiments. It should be understood that all such variations and modifications are to be included within the scope of the present invention.

Embodiments of the present invention relate to a method for producing N strip metal in a plant 10.

In the accompanying drawings of FIG. 2 in FIG. 9 illustrates possible layouts of the equipment of installations 10 for the production of strip metal with the embodiment of the principles of the present invention.

The following will be described with reference to FIGS. 1, which shows the components of the plant located in the production line. The components shown in Fig. 1 may be combined with each other to form one or more equipment layouts, which can be seen in the accompanying figures of FIG. 2 in FIG. 9. Therefore, in the embodiments of plant 10 depicted in the accompanying drawings of FIG. 2 in FIG. 9, reference is made to the components of the plant described with reference to FIG. one.

The installation 10 for the production of strip N contains at least one casting machine 11, into which liquid metal is poured to solidify and obtain a billet B.

According to one aspect of the invention, the installation 10 also includes a rolling mill 19 located behind the casting machine 11 and configured to hot-roll the billet B and produce strip N.

The casting machine 11 comprises at least one casting mold 15 provided with a mold 15a in which a casting P is formed which passes through the entire casting machine 11.

The mold 15a may comprise at least two wide plates facing each other and spaced apart, at least in a finite area, by a certain amount corresponding to the thickness H of the casting P exiting the mold 15a.

In addition, the width of said mold plates 15a is matched to the width of the resulting strip N.

At the outlet of the mold 15a, the casting P is covered with a hardened shell capable of retaining liquid metal even outside the mold 15a.

In some embodiments, the casting machine 11 is equipped with thickness reduction means which are located downstream of the mold and can be adjusted selectively whenever the strip thickness changes to change the effect on the casting P exiting the mold 15a.

These thickness reduction means may comprise a rolling device and/or a roller assembly, for example of a pulling type, as described below.

In some embodiments, the casting machine 11 includes a rolling device 16 with rolls, hereinafter also referred to as a roll assembly, located behind the mold 15 and configured to reduce the thickness of the casting P exiting the mold 15a, while the core of this casting is still liquid or partially liquid.

In some embodiments, the rolls of the roll assembly 16 are grouped into sections located opposite each other and oriented along the casting axis.

In order to have a selective effect on reducing the thickness of the casting, these rolls can optionally be moved closer to each other or further away from each other.

To move the rolls of the roll assembly 16 to approach each other or to move away from each other and to reduce the thickness of the casting P leaving the mold 15a, control devices 17 are connected to the said sections.

The overall reduction in thickness that the casting P undergoes as it exits the mold 15a in the roll assembly 16 is to reduce the liquid core, so it does not cause elongation of the material.

At the exit from the roll assembly 16, the billet B is completely solidified and has a thickness of SB1.

The thickness SB1 of the billet upon completion of the rolling of the liquid core determines the performance of the casting machine 11, and hence the plant as a whole.

The compression carried out in the roll assembly 16 makes it possible to connect the two half-shells at the butt point KR, where the casting is completely solidified. Point KP is also considered as the end vertex of the liquid cone emerging from the liquid metal meniscus in the mold 15a.

According to one aspect of the invention, the position of the CR point can be varied along the longitudinal strike of the roller assembly 16, affecting the rate of reduction in the thickness of the liquid core, provided by the regulation of the sections of the roller assembly 16, and the intensity of the secondary cooling. The position of the KP point also depends on the casting speed. The thickness of the casting in accordance with the point KP is equal to the thickness SB1 of the billet coming out of the roller assembly 16.

According to one aspect of the invention, the blank thickness SB1 is optionally set depending on the final strip thickness N, in particular depending on the finished product range produced by the plant, as will be explained below.

Solutions are possible when known types of recooling devices are associated with the roller assembly 16 and are configured to cool the outer surfaces of the workpiece, thereby contributing to the solidification of the latter. Cooling devices can be equipped with nozzles that spray water or a water-air mixture. The operation of the cooling devices also affects the position of the CR point.

In some embodiments, the casting machine 11 includes a pull unit 18, which is located behind the roll unit 16 and is configured to pull the billet B towards the rolling mill 19.

Pulling unit 18 contains from one to six pairs of pulling rollers.

The rollers of each pair are located opposite each other on both sides of the drawn workpiece B.

In some embodiments, the pulling unit 18 is configured to roll the workpiece B passing through it.

In order to bring the rollers closer together and away from each other, as well as to regulate the pressure on the fully hardened workpiece B, as described below, the rollers of each pair or at least one of them can be associated with moving devices, for example, with hydraulic cylinders of the known type (not shown).

Solutions are possible when the pull unit 18 includes a first pull unit 18a located just behind the roll unit 16, that is, in the vertical section of the casting machine 11. A solution, presumably combined with the previous solution, is possible, when the pull unit 18 includes a second pull unit 18b located immediately behind the curved section of the casting machine 11.

The presence of the first pulling device 18a is provided only in the case of casting in a mold with a vertical cavity.

The presence of the second pulling device 18b is provided only in the case of casting into a vertical cavity mold and into a vertically curved cavity mold.

The first puller 18a and/or the second puller 18b may comprise one to three pairs of rollers.

As mentioned above, the rollers of the pulling unit 18 are configured to slightly reduce the thickness of the liquid core in the billet B of thickness SB1 and therefore perform actual rolling, albeit a small amount, which causes elongation of the material. This light rolling performed by the pulling unit 18 causes a further reduction in the thickness of the workpiece B, which takes on an SB2 value smaller than SB1, which makes it possible to achieve even thinner thicknesses with the downstream rolling mill 19. The pull unit 18 is located at the end of the casting machine 11, so the thickness SB2 of the workpiece B at the exit of the pull unit 18 corresponds to the thickness of the workpiece B at the exit of the casting machine 11.

The pulling assembly 18, together with the roller assembly 16 and the mold 15a, is an integral part of the casting machine 11, which, due to the rolling performed by the rollers, can be characterized as a rolling casting machine. A casting machine is understood to mean a casting machine 11 capable of both casting and rolling a casting partly with a liquid core and partly with a solid core.

The overall thickness reduction that the casting P leaving the mold 15a undergoes inside the casting machine 11 is partly liquid-core and partly solid-core.

According to one aspect of the invention, the distribution of reduction in the thickness of the workpiece in the casting machine 11 is advantageously modulated between the liquid core and the solid core according to specific production requirements.

Variants are possible in which the rolling mill 19 includes a rough rolling unit 12 configured to roll the billet B.

This rough rolling assembly 12 may include one or more roughing stands 20.

In other embodiments, the rolling mill 19 includes a finishing rolling unit 13 configured to roll the billet B and give it its final size, i.e., to delimit the metal strip N.

The finishing rolling unit 13 is located behind the rough rolling unit 12.

The finishing rolling unit 13 may comprise one or more finishing stands 21, each of which is configured to roll the billet and limit the strip thickness SN.

Solutions are possible when, immediately after the rough rolling unit 12, a cutting device 26 is installed, which is configured to cut the rough-rolled workpiece B and cut out the rolled metal intended for further rolling in order to obtain a strip N.

The plant 10 may include at least one induction heating device, in this case one, two or three induction heating devices 22, 23 and 34, configured to heat the workpiece B.

A solution is possible when the installation 10 contains the first induction heating device 22 located behind the casting machine 11, in this case in front of the rough rolling unit 12, and configured to restore the temperature of the billet before it is fed into the rolling mill 19.

A solution is possible when the installation 10 contains a second induction heating device 23 located in front of the finishing rolling unit 13, for example, between the rough rolling unit 12 and the finishing rolling unit 13, and configured to increase the temperature of rolled metal before it is fed into the finishing rolling unit 13.

A solution is possible when the second induction heating device 23 is located immediately after the rough rolling unit 12.

According to another solution, the plant 10 has a third induction heating device 34 located between two finishing stands 21 and configured to restore the temperature of the rolled metal during the finishing rolling process.

According to another variant, the installation 10 contains at least one heating and/or maintenance unit, in this case two heating and/or maintenance units 32 and 33, configured to heat or maintain the temperature of rolled metal segments.

The heating and/or holding unit 32 and 33 has a heating and/or holding tunnel furnace, which also serves as a store for rolled metal in case of interruption of the rolling process in the event of minor malfunctions or a planned change of rolls, thereby avoiding material and energy losses and not interrupting the process. pouring.

A solution is possible when plant 10 has a first heating and/or maintenance unit 32 located just before rolling mill 19.

In yet another embodiment, plant 10 has a second heating and/or maintenance unit 33 located between the rough rolling unit 12 and the finishing rolling unit 13.

This embodiment has the advantage that the plant 10 is equipped with a cutting device 35 which is located between the casting machine 11 and the rolling mill 19 and is configured to cut the billet B produced by the casting machine 11 into lengths. In the event of an emergency or if maintenance is required, for example, changing the rolls of the rolling mill 19, the said segments can be stored, maintaining their temperature, in the first heating and/or maintaining unit 32.

In some embodiments, the installation 10 has an intermediate winding-unwinding device 29 located between the cutting device 26 and the finishing rolling unit 13 and configured to wind rolled metal cut by the cutting device 26 and feed rolled metal, cut and wound before that, to the finishing rolling unit 13.

Options are possible in which the installation 10 includes both the second heating and/or maintaining unit 33 and the intermediate winding-unwinding device 29 located behind the first heating and/or maintaining 32.

As an intermediate winding-unwinding device 29, for example, the device described in the international patent application WO-A-2011/080300 in the name of the applicant of this application can be used.

According to some solutions, the intermediate winding-unwinding device 29 has a first node 30 and a second node 31, which alternate in winding the rolled metal obtained from the rough rolling unit 12 and unwinding the rolled metal, wound before, to feed it to the finishing rolling unit 13.

Namely, while one of the two units 30, 31 is winding rolled metal, the other unit 31, 30 is unwinding the other rough rolled rolled metal, feeding it further along the production line. The intermediate winder-unwinder 29 can also serve as a temporary storage to compensate for the difference in the speed of the casting machine 11 and the finish rolling unit 13. In this case, the intermediate winder-unwinder 29 "absorbs" the time the rolling mill is stopped for minor repairs or a scheduled replacement rolls, or in the event of minor malfunctions/blockages, without the need to interrupt the casting process and therefore without loss of productivity and without interfering with the previous stages of the production process.

Solutions are possible when the intermediate winding-unwinding device 29 incorporates heaters (not shown) for heating or maintaining the temperature of the rolled metal contained therein.

According to another solution, the installation 10 includes a cutting device 28 located between the rough rolling unit 12 and the finishing rolling unit 13 and is configured to cut off the head or tail end of the rolled metal coming out of the rough rolling unit 12, in this case from the intermediate winding device - unwinding 29, and supplied to the finishing rolling unit 13.

According to another solution, between the rolling mill 19 and the final winding unit 14, a cooling unit 24 is installed, configured to cool the strip N leaving the rolling mill 19, and to allow the strip to be collected in the final winding unit 14.

In another embodiment, the installation 10 includes a final winding unit 14 for the strip N.

This final winder 14 has a winder 25 suitable for winding the strip in N turns.

In some embodiments, the plant 10 is provided with a cutter 27 which is located in front of the final winder 14 and is configured to cut the strip N to size as soon as the weight of the turn of the strip N reaches a predetermined value. The cutting device 27 may be located between the cooling unit 24 and the final winding unit 14.

In FIG. 2 shows one of the embodiments of the installation 10, which has in its composition sequentially placed the casting machine 11, which was described above, the cutting device 35, the first induction heating device 22 and/or the first heating and/or maintaining unit 32, the finishing rolling unit 13 , cooling unit 24 and final winding unit 14.

In FIG. 3 shows another embodiment of the plant 10 which, in addition to the components of the plant 10 shown in FIG. 2, the rolling mill 19 also has a rough rolling unit 12, a second induction heating device 23, a second heating and/or maintenance unit 33, and a cutting device 28 located in front of the finishing rolling unit 13.

In FIG. 4 shows another embodiment of the installation 10, which has in its composition sequentially placed casting machine 11, which was described above, a cutting device 26, a second induction heating device 23, an intermediate winding-unwinding device 29, a cutting device 28, a finishing rolling unit 13 , cooling unit 24 and final winding unit 14.

Installation 10 shown in FIG. 5, has in its composition successively placed casting machine 11, which was described above, a rolling mill 19, equipped with a rough rolling unit 12, a cutting device 26, a second induction heating device 23, a second heating and/or maintaining unit 33, a cooling unit 24 and final winding unit 14.

The installations 10 described with reference to the accompanying figures of FIG. 2 in FIG. 5 may optionally be operated in a coil-to-coil mode.

Installation 10 shown in FIG. 6, has in its composition sequentially placed casting machine 11, which was described above, a rolling mill 19 equipped with a cutting device 35, a second induction heating device 23, a second heating and/or maintaining unit 33, a finishing rolling unit 13, a cooling unit 24, cutting device 27 and final winding unit 14.

Installation 10 shown in FIG. 6 can be adapted to operate in a coil-to-coil or semi-continuous mode.

In FIG. 7 shows an installation 10 comprising successively placed casting machine 11, which was described above, a rolling mill 19 equipped with a rough rolling unit 12, a cutting device 26, a second induction heating device 23, a finishing rolling unit 13, a third induction heating device 34 , which is located between the finishing stands 21, the cooling unit 24, the cutting device 27 and the final winding unit 14.

Installation 10 shown in FIG. 7 can be adapted for continuous operation.

In FIG. 8 shows a plant 10 comprising successively placed casting machine 11, which was described above, a rolling mill 19 equipped with a rough rolling unit 12, a cutting device 26, a second induction heating device 23, an intermediate winding-unwinding device 29, a cutting device 28 , the finishing rolling unit 13, the third induction heating device 34 located between the finishing stands 21, the cooling unit 24, the cutting device 27 and the final winding unit 14.

Installation 10 shown in FIG. 8 can be adapted to operate in a coil-to-coil or continuous mode.

In FIG. 8 shows a plant 10 comprising in series a casting machine 11 as described above, a rolling mill 19 equipped with a cutting device 35, a first induction heating device 22, a first heating and/or maintaining unit 32, a rough rolling unit 12, a cutting device 26, the second induction heating device 23, the finishing rolling unit 13, the third induction heating device 34, which is located between the finishing stands 21, the cooling unit 24, the cutting device 27 and the final winding unit 14.

Installation 10 shown in FIG. 9 can be adapted to operate in a coil-to-coil mode, semi-continuous mode, or continuous mode.

Installation options 10 shown in the attached figures of FIG. 2 in FIG. 9 can be offered to the customer to choose from, so that the optimum is achieved taking into account productivity, product mix and types of steel produced.

According to one aspect of the invention, a method for producing strip metal N includes at least the steps of casting a casting P with a casting machine 11 to obtain a billet B and hot rolling a billet B in a rolling mill 19 to produce a strip of metal N.

According to another aspect of the invention, with the help of the casting machine 11, during the casting process, the metal is affected in such a way as to reduce the thickness of the casting P leaving the mold 15a.

According to another aspect of the invention, for each value of the thickness of the produced strip metal N, the casting machine of choice is adjusted to provide the appropriate effect to reduce the thickness of the casting P leaving the mold 15a.

In particular, it is provided that the thickness of the blank B at the outlet of the casting machine 11 is adjusted each time, depending on at least the final thickness N of the strip metal to be produced, and possibly also on the range of finished products to be obtained.

This solution makes it possible to reduce the pressure developed in the rolling mill 19, reduce the required power, reduce the wear of the rolling rolls, and in some cases also reduce, at least by one unit, the number of rolling mill stands compared to known installations of the same capacity.

A solution is possible when, with the same dimensions of the mold 15a, the method has a first stage in which a first strip having a first thickness SN' is produced, while the casting machine 11 provides a first degree of reduction in the thickness TAUA' of the casting P exiting the mold 15a, and the second stage on which a second strip is produced having a second thickness SN'' less than said first thickness, wherein the casting machine 11 provides a second degree of thickness reduction TAUA'' of the casting P exiting the mold 15a, wherein the first degree of thickness reduction TAUA' differs from the second degree of reduction in the thickness of TAU A''.

According to one solution, the first degree of reduction in thickness TAU A is less than the second degree of reduction in thickness TAUA''.

The thickness reduction ratio TAUA is defined as the difference between the thickness H of the casting P exiting the mold 15a and the thickness SB2 of the billet exiting the casting machine 11 relative to the thickness H of the casting P exiting the mold 15a.

In implementing one of the possible solutions, the Applicant has determined that the casting machine 11 can be adjusted in such a way that it provides a reduction in the thickness of the casting P according to the following formula: TAUA=K⋅A⋅H ^-l ⋅e ^a⋅SN

where

K is a variable parameter ranging from 0.8 to 1.1,

A is a coefficient equal to approximately 4689,

H is the thickness of the casting P coming out of the mold 15a, i.e. the thickness of the mold 15a,

a - coefficient equal to -0.37,

SN is the thickness of the strip N obtained at the end of rolling.

The value of TAUA, which is determined by the above formula, is expressed as a percentage and is usually in the range from 2% to 75%.

In FIG. 10 shows several curves plotted for the thickness H of the casting P, which show the change in the value of TAUA as a function of the thickness SN of the strip metal.

This formula makes it possible to optimize the setting of the casting machine 11 depending on the thickness of the mold 15a and the thickness SN of the strip metal to be produced, for the efficient operation of the entire plant as defined above.

A solution is possible when the casting machine 11 is configured to

i) provide a reduction in the thickness of the casting P by rolling the liquid core with the help of a roll assembly 16 to achieve the degree of reduction in thickness TAU 1,

ii) reduce the casting thickness P by means of the pulling unit 18 to achieve a thickness reduction ratio TAU of 2.

Reducing the thickness of the casting using the pulling unit 18 is not a mandatory operation of the proposed method.

Therefore, the TAU thickness reduction ratio A is given as a combination of the TAU 1 and TAU 2 reduction ratios.

The degree of thickness reduction TAU 1 provided by the rolling device is determined by the difference between the thickness H of the casting P leaving the mold 15a and the thickness SB1 of the billet leaving the roll assembly 16, correlated with the thickness H of the casting P leaving the mold 15a.

The degree of thickness reduction TAU 2 provided by the pull unit 18 is defined as the difference between the thickness SB1 of the workpiece leaving the roll unit 16 and the thickness SB2 of the workpiece leaving the pull unit 18, correlated with the thickness SB1 of the workpiece leaving the roll unit 16.

In implementing one of the possible solutions, the Applicant has determined that the pull unit 18 can be adjusted in such a way that it provides a reduction in the thickness SB1 of the solid core of the casting P according to the following formula:

TAU2=Q⋅(-B⋅H ^b ⋅lnSN+C⋅Н ^s )

where

Q - variable parameter ranging from 0.8 to 1.1,

B - the first coefficient equal to 10928,

H is the thickness of the casting P leaving the mold 15a, as defined above,

b - second coefficient equal to -1.659,

SN - strip metal thickness,

C is the third coefficient equal to 10648, c is the fourth coefficient equal to -1.596.

A solution is possible when the hard core thickness reduction effect P is applied to strip metal thicknesses SN from 0.6 mm to 3.5 mm. In fact, for these SN values, the action on the liquid core gives a relatively high result in terms of reducing, from the very beginning, the thickness of the original workpiece to a maximum, and therefore the subsequent action of the pulling unit 18 to reduce the thickness of the solid core is advantageous.

In addition, the impact on the hard core by rolling in the pulling unit 18 allows to increase productivity, which is of particular advantage in the case of small thicknesses of the strip metal.

In FIG. 11 shows several curves plotted for the thickness H of the casting P leaving the mold, which show the change in the value of TAU 2 as a function of the thickness SN of the strip metal.

The degree of thickness reduction in the rough rolling unit 12 is designated TAU 3 and is defined as the difference between the thickness SB2 of the workpiece B in front of the rough rolling unit 12 and the thickness of the workpiece B behind the rough rolling unit 12, correlated with the thickness SB2 of the workpiece B in front of the rough rolling unit 12.

The degree of thickness reduction in the finishing unit 21 is designated TAU 4 and is defined as the difference between the thickness of the billet B in front of the finishing unit 21 and the thickness SN of the resulting strip metal, correlated with the thickness of the billet B in front of the finish rolling unit 21.

The degree of overall thickness reduction provided by the rolling mill 19 is referred to as TAU B and is defined as the difference between the thickness SB2 of the billet leaving the casting machine 11 and the thickness of the resulting strip metal N, correlated with the thickness SB2 of the billet exiting the casting machine 11. The degree of total The thickness reduction TAU B provided by the rolling mill 19 can also be defined as a combination of the thickness reduction rates TAU 3 and TAU 4 provided by the rough rolling unit 12 and the finishing rolling unit 13, respectively.

According to another aspect of the invention, the method for producing strip metal comprises the step of providing the customer with at least the following design data:

- PR performance, e.g. annual capacity of the plant 10,

- the range of thicknesses RS and the average width LN of the strip metal to be produced by plant 10,

- distribution of productivity values depending on the thickness of the produced strip metal N,

- the range of finished products provided by the casting machine, i.e. steel grades,

- distribution of performance values depending on the types of casting.

The above set of parameters determines the range of finished products of the installation, that is, the variety of products produced by the installation 10, according to which its configuration is selected to achieve the objectives of the invention.

From the provided thickness range RS, the minimum thickness SMIN and the maximum thickness SMAX of the resulting strip metal can be determined.

In some embodiments, the rolling method makes it possible to determine the optimal rolling mode of billet B relative to the finished product mix requested by the customer.

The billet rolling mode B is selected from the following: continuous, semi-continuous and "coil to coil".

In FIG. 12 graphically illustrates the criteria for selecting the rolling conditions mentioned above, at least in relation to the thicknesses SN of the strip metal and the steel grades used.

In order to create a plant 10 operating in several modes, the rolling mode to be provided each time will be determined by optimizing the operating parameters of the plant based on economic estimates (energy consumption and process efficiency based on product output) and requirements for the quality of the finished product ( dimensional tolerances and mechanical properties of strip metal).

If thin strips predominate in the finished product mix and it is not required to cast specific grades of steel, such as peritectic steels, which are difficult to cast and require low casting speeds, it may be possible to select a continuous rolling mode and therefore one of the the schemes shown in Fig. 7, fig. 8 or FIG. nine.

If the range of finished products is dominated by strips with small thicknesses, but it is also required to cast steel of specific grades, then semi-continuous and coil-to-coil modes are usually chosen for rolling, and therefore one of the schemes shown in Fig. 6 or FIG. 9. Both semi-continuous and coil-to-coil modes allow specific grades of steel to be cast at low speeds because the rolling process does not limit the casting process. For strips N thin and ultrathin, for example from 0.8 mm to 1.4 mm, the semi-continuous mode is preferred.

In FIG. 13 is a graphical representation of yet another criterion for selecting rolling conditions with respect to the thickness of the strip metal and the throughput of a plant layout selected to use one and/or another of the rolling conditions listed above.

For example, with reference to FIG. 13 if the installation according to the diagrams shown in the attached figures from FIG. 2 in FIG. 5, coil-to-coil operation is envisaged for strip thicknesses from about 1.2 mm to about 12 mm, and if the circuit shown in FIG. 9, continuous operation is provided for strip thicknesses from about 0.6 mm to about 1 mm, semi-continuous mode for strip thicknesses from about 1 mm to about 2 mm, and coil-to-coil mode for strip thicknesses from about 2 mm. mm to approximately 12 mm.

According to another solution, the proposed method provides for the possibility of adjusting the casting speed VC, the value of which is selected from the range from 4.5 m/min to 6 m/min.

For steels that are difficult to pour, such as API (American Petroleum Institute specification), peritectic and Corten steels, low casting speeds, for example, from 4.5 m/min to 5 m/min, are successfully used. For easier casting steels, such as low carbon, medium carbon, high strength alloy, duplex, complex phase, high carbon and manganese-boron steels, set a higher casting speed, for example, from 5 m/mm to 6 m/mm.

In the same way, the casting speed VC can also be selected for the selected rolling conditions, i.e., relatively low rolling speeds for coil-to-coil and semi-continuous modes and higher rolling speeds for continuous mode.

The proposed method also provides for the determination of the nominal thickness SBN of the workpiece, which, in relation to the casting speed VC and the average strip width LN, makes it possible to achieve the productivity PR.

The concept of the nominal thickness SBN of the billet can also be interpreted as a constant thickness of the equivalent billet, which for the same volume of products with the same assortment of finished products corresponds to the weighted average of the thicknesses of the billets after reducing the thickness of the liquid core (on average) according to the corresponding hourly productivity values.

A solution is possible when the nominal thickness SBN of the workpiece is determined by the following formula:

SBN=PR / OPENING HOURS / (VC*LN*PS)

WORKING HOURS here and in the following description, as well as in the claims, means the working time of the installation (in hours) during the calendar year, minus the time of stops for maintenance, due to malfunctions, etc.

Here PS is the density of the steel, which is usually about 7.8 kg/dm ³ .

In FIG. 14 and FIG. 15 graphically illustrates the correlation of the nominal billet thickness SBN with the annual capacity PR of the plant and with the casting speed VC.

Fig. 14 refers to a workpiece width of approximately 1300 mm, and Fig. 15 - to the width of the workpiece approximately 1400 mm.

In one of the embodiments, the proposed method includes the step of determining the thickness H of the casting P leaving the mold 15a, that is, determining the distance between the plates of the mold 15a in accordance with the exit section of the latter. Casting thickness H P is accepted for the entire range of finished products specified by the client.

It is possible that the thickness H of the casting P exiting the mold 15a exceeds the nominal billet thickness SBN by 10 mm to 15 mm.

Then, an operation is provided to determine the thickness ratio RSP provided by the rolling mill 19 and calculated as the ratio between the thickness SB2 of the billet entering the rolling mill 19 when processing the strip N of the minimum thickness SMIN and the minimum thickness SMIN of the resulting strip N.

The thickness SB2 of the billet entering the rolling mill 19 when processing a strip N of minimum thickness SMIN is calculated as the thickness H of the casting P leaving the mold 15a minus the maximum thickness reduction provided by the casting machine. It is possible that this maximum thickness reduction provided by the casting machine 11 is at least 31 mm.

Further, the proposed method provides for determining the number of stands of the rolling mill 19 based on the ratio of thicknesses.

For a thickness ratio of 4 to 12, four rolling stands are provided.

For a thickness ratio of 12 to 21, five rolling stands are provided.

For a thickness ratio of 21 to 52, six rolling stands are provided.

For thickness ratios from 52 to 101, seven rolling stands are provided.

The correlation between the number of rolling stands and the thickness ratio is illustrated in FIG. 16.

The number of rolling mill stands 19 is the sum of the number of finishing stands 21 and the number of roughing stands 20.

Further, the proposed method provides for setting the mode of distribution of thickness reduction due to the liquid core in the casting machine 11, carried out by the roller assembly 16, and the pulling assembly 18, in relation to the billet B leaving the mold 15a, relative to the final thickness of the strip N.

This mode of distribution of reduction in casting thickness P can be determined from the formulas for TAU A and TAU 2 above.

It is also possible that the casting machine 11 is adjusted so that it reduces the casting thickness P by 5 mm for a strip thickness equal to the maximum thickness SMAX and by 25 mm to 31 mm for a strip thickness equal to the minimum thickness SMIN.

A solution is possible where the roll assembly 16 achieves a maximum thickness reduction of RCLMAX due to the liquid core of approximately 25 mm. A solution is possible where the roll assembly 16 provides a minimum reduction in thickness RCLMIN due to the liquid core of approximately 5 mm. This reduction in thickness makes it possible to improve the casting quality P.

A solution is possible where the pulling assembly 18 provides a maximum hard core reduction of at least 7 mm with zero minimum reduction.

In particular, each pair of rollers of the pulling unit 18, if necessary, can develop a pressure that reduces the thickness by a value of from 0.5 mm to 1.5 mm.

Variants are possible in which, when setting the “coil to coil” mode and using the winding-unwinding device 29, the number of rough stands 20 is determined in such a way that rolled metal with a thickness of 8 mm to 25 mm enters the winding-unwinding device 29. When the thickness of rolled metal is less than 8 mm, problems arise with the transportation and introduction of rolled metal into the winding-unwinding device 29, and when the thickness of rolled metal is more than 25 mm, difficulties arise in operation and/or sizing, and surface defects are also possible.

Variants are possible in which, when setting the "coil to coil" mode and using the heating and/or maintenance unit 33, the number of roughing stands 20 is determined in such a way that rolled metal with a thickness of at least 30 mm is supplied to the input of the heating and/or maintenance unit. With a smaller thickness, it would be necessary to use a heating and/or maintaining a very large length, which is difficult to operate and not economical.

A solution is possible when there are at least two finishing stands 21. Examples

In the accompanying figures of FIG. 17 to FIG. 22 illustrates two examples of implementation of the ideas of the present invention.

In the accompanying figures of FIG. 17 to FIG. 19 shows a first example requiring a PR production of approximately 1.1 Mt/yr, a thickness range of RS from 1.2 mm to 8 mm, and an average strip width LN of approximately 1300 mm.

In FIG. 20, fig. 21 and FIG. 22 shows a second example requiring a PR production of approximately 1.4 Mt/yr, a thickness range of RS from 0.8 mm to 3 mm, and an average strip width LN of approximately 1400 mm.

In the last four columns of the tables shown in Figs. 17 and FIG. 20, one can see a comparison of the productivity distribution for the finished product mix in the case of conventional casting and in the case of thin casting according to the present invention.

The finished product mix and annual output values (see columns 11 and 12 of the tables) are parameters required by the customer and set according to how the customer intends to operate the plant.

In addition, in column 6 of the tables shown in FIG. 17 and FIG. 20, it can be seen that the thickness SB2 of the billet exiting the casting machine 11 does not remain constant with the change in the thickness of the strip, but decreases along with the decrease in the thickness of the strip. And in the known methods, the thickness SBN of the billet exiting the casting machine remains unchanged when the thickness of the strip changes, as can be seen in column 2. This is also illustrated graphically in FIG. 18 and FIG. 21.

This change in the thickness of the preform with the change in the thickness of the finished strip is obtained due to the fact that the casting machine 11 acts on the liquid core of the preform, reducing the thickness of the RCL of the latter, which can be seen in column 3 of the tables in FIG. 17 and FIG. twenty.

These tables also show the reduction in thickness provided by the pulling unit 18 (column 5), the black rolling unit 12 (column 7) and the finishing unit 13 (column 9), and it can also be seen how these effects are distributed over the thicknesses of the finished strips obtained.

In FIG. 19 and FIG. 22 shows the distribution of the hourly output of the plant as a function of the strip thickness obtained, illustrated graphically for the case of the known casting method and for casting with a variable degree of thickness reduction according to the invention.

In particular, in FIG. 19 and FIG. 22 it can be seen that in the case of the known method the hourly output remains the same regardless of the thickness of the strip to be obtained, while in casting according to the invention the hourly output varies depending on the thickness of the strip to be obtained.

As can be seen in FIG. 19 and FIG. 22, in the case of small strip thicknesses, the proposed method provides lower productivity than known methods, but for large strip thicknesses, the proposed method provides higher productivity than known methods. In general, however, the annual productivity provided by the known methods and the proposed method is the same, and the proposed method provides advantages over the known methods.

Next, with reference to the accompanying figures of FIG. 17 to FIG. 19 relating to the first case, the selection mode of the plant type and the number of stands of the rolling mill 19 will be described.

Based on the thickness range from 1.2 mm to 8 mm and the graphical illustration of the rolling condition selection criteria shown in FIG. 12 advantageously adopts a plant pattern capable of realizing the coil-to-coil rolling mode.

A casting speed of approximately 5.5 m/min is then provided, which, with an average strip width LN of 1300 mm and a production rate of 1.1 Mt/yr, corresponds to a nominal billet thickness SBN of approximately 45 mm, as can be deduced graphically from FIG. fourteen.

Based on this value SBN, it is possible to determine the thickness H of the casting P, which is between 10 mm and 15 mm greater than the nominal thickness SBN of the billet, in this case 55 mm, as can be seen in the table shown in FIG. 17.

The degree of thickness reduction to be achieved by the rolling mill 19 is then determined.

The thickness SB2 of the billet entering the rolling mill 19 when the minimum thickness is processed is 24 mm.

Therefore, the thickness ratio RSP provided by the rolling mill 19 is generally 24: 1.2=20.

In FIG. 16 it can be seen that this ratio of thicknesses corresponds to the number of stands equal to five.

As far as the prior art is concerned, in this case the thickness ratio as the ratio of the nominal billet thickness SBN to the minimum strip thickness SMIN is 45:1.2=37.5. As can be seen in FIG. 16, this ratio of thicknesses corresponds to the number of stands equal to six. From this example, it can be seen how, with the same annual throughput of the plant, it is possible to reduce the number of rolling mill stands by one compared to the prior art.

Next, with reference to the accompanying figures of FIG. 20 in FIG. 22 relating to the second case, another mode for selecting the type of plant and the number of stands of the rolling mill 19 will be described.

Based on the thickness range from 0.8 mm to 3.0 mm and the graphical illustration of the rolling condition selection criteria shown in FIG. 12 advantageously adopts a plant pattern capable of realizing a continuous rolling mode.

A casting speed of approximately 6.0 m/min is then provided which, with an average strip width LN of 1400 mm and a production rate of 1.4 Mt/yr, corresponds to a nominal billet thickness SBN of approximately 50 mm, as can be deduced graphically from FIG. 15.

Based on this value SBN, it is possible to determine the thickness H of the casting P, which is between 10 mm and 15 mm greater than the nominal thickness SBN of the blank, in this case 65 mm, as can be seen in the table shown in FIG. twenty.

The degree of thickness reduction to be achieved by the rolling mill 19 is then determined.

The thickness SB2 of the billet entering the rolling mill 19 when the minimum thickness is processed is 34 mm.

Therefore, the thickness ratio RSP provided by the rolling mill 19 is generally 34: 0.8=42.5.

In FIG. 16 it can be seen that this ratio of thicknesses corresponds to the number of stands equal to six.

As far as the prior art is concerned, in this case the thickness ratio as the ratio of the nominal billet thickness SBN to the minimum strip thickness SMIN is 50: 0.8=62.5. As can be seen in FIG. 16, this ratio of thicknesses corresponds to the number of stands equal to seven. From this example it can be seen how, with the same annual throughput of the plant, it is possible to reduce the number of rolling mill stands by one compared to the prior art.

It should be clear that the proposed method and the previously described installation for implementing this method can be modified and/or supplemented without departing from the essence and scope of the invention.

It should also be understood that although the present invention has been described with reference to some specific examples of its implementation, the person skilled in the relevant field is able to create many other equivalent variants of the method and installation for the production of strip metal, having the features set forth in the attached claims and, therefore, covered by the scope of the proposed inventions.

In the appended claims, reference signs in parentheses are given for the sole purpose of facilitating reading and should not be construed as limiting the scope of the invention claimed in the claims.

Claims (32)

1. A method for producing strip metal (N), in which casting (P) is cast in a casting machine (11) equipped with a mold (15a) to obtain a billet (B), and hot rolling of the billet (B) is performed in a rolling mill (19) to obtain strip metal (N) of different thicknesses (SN), and in the process of casting with the help of a casting machine (11), the thickness of the casting (P) coming out of the mold (15a) is reduced, characterized in that said casting machine (11) is equipped with a device rolling (16) with rolls located behind the mold (15a) and a pulling unit (18) located behind the said rolling device (16), which are selectively adjusted when changing the thickness (SN) of the strip metal to provide a controlled action to reduce the thickness of the casting ( P), while with the same dimensions of the mold (15a) perform at least the first stage, which produces the first strip having a first thickness (SN'), while using the casting machine (11) to provide a first degree of thickness reduction (TAU A') of the casting (P) exiting the mold (15a) is carried out, and a second stage in which a second strip is produced having a second thickness (SN'') smaller than the first thickness (SN'), wherein the casting machine (11) provides a second degree of thickness reduction (TAU A'') of the casting (P) different from the first degree of thickness reduction (TAU A'), wherein the degree of thickness reduction is defined as the difference between the thickness (H) of the casting ( P) leaving the mold (15a) and the thickness (SB2) of the billet leaving the casting machine (11) correlated with the thickness (H) of the casting (P) leaving the mold (15a). 2. The method according to claim 1, characterized in that the first degree of thickness reduction (TAU A') is less than the second degree of thickness reduction (TAU A''). 3. The method according to any one of paragraphs. 1 or 2, characterized in that the casting machine (11) is optionally adjusted to reduce the thickness of the casting (P) emerging from the mold (15a) according to the following formula:

, where K is a variable parameter ranging from 0.8 to 1.1, A is a coefficient equal to approximately 4689, H is the thickness of the casting (P) leaving the mold (15a), that is, the thickness of the mold (15a), a - coefficient equal to 0.37, SN is the thickness of the strip obtained at the end of rolling. 4. The method according to any one of paragraphs. 1-3, characterized in that the casting machine (11) contains a rolling device (16) with rolls, configured to reduce the thickness of the casting (P) exiting the mold (15a) by rolling this casting with a liquid core. 5. The method according to claim 4, characterized in that the rolling device (16) is equipped with rolls located opposite each other, between which a casting (P) is passed, and to select the degree of reduction in the thickness of the casting (P) due to its liquid core, the said rolls approach each other or move away from each other. 6. The method according to any one of paragraphs. 4 or 5, characterized in that the casting machine (11) contains a pull unit (18) configured to reduce the thickness of the casting (P) leaving the rolling device (16) with rolls by rolling the solid core of the casting (P). 7. The method according to claim 6, characterized in that the pulling unit (18) is optionally adjusted so that it provides a reduction in the thickness of the solid core of the casting (P) according to the following formula:

, where Q - variable parameter ranging from 0.8 and 1.1, B - the first coefficient equal to 10928, H is the thickness of the casting (P) leaving the mold (15a), b - second coefficient equal to 1.659, SN - strip metal thickness, C - the third coefficient, equal to 10648, c is the fourth coefficient, equal to 1.596. 8. The method according to any one of paragraphs. 6 or 7, characterized in that the thickness of the solid core of the casting (P) is reduced in relation to the thicknesses (SN) of the strip metal from 0.6 to 3.5 mm. 9. The method according to any one of paragraphs. 1-8, characterized in that the thickness (H) of the casting (P) emerging from the mold (15a) is determined by 10 to 15 mm in excess of the nominal thickness (SBN) of the workpiece, determined by the formula SBN=PR/WORKING HOURS /(VC*LN*PS) where PR is the productivity of the plant, VC is the casting speed, the value of which is chosen in the range from 4.5 to 6 m/min, LN is the average strip width, and PS is the steel density. 10. The method according to any one of paragraphs. 1-9, characterized in that the ratio of thicknesses (RSP) provided by the rolling mill (19) is determined and calculated as the ratio between the thickness (SB2) of the workpiece entering the rolling mill (19) when processing the strip (N), the minimum thickness (SMIN ) and the minimum thickness (SMIN) of the resulting strip (N). 11. The method according to claim 10, characterized in that, based on the ratio of thicknesses, the number of rolling mill stands (19) is determined, while - with a ratio of thicknesses from 4 to 12, four stands of the rolling mill are provided, - with a ratio of thicknesses from 12 to 21, five stands of the rolling mill are provided, - with a ratio of thicknesses from 21 to 52, six stands of the rolling mill are provided, - with a ratio of thicknesses from 52 to 101, seven stands of the rolling mill are provided. 12. Installation for the production of strip metal (N), containing a casting machine (11) equipped with a mold (15a) and configured to cast a casting (P) and receive a billet (B), and a rolling mill (19) for rolling a billet (B ) to obtain strip metal (N) of different thicknesses (SN), while the casting machine (11) is configured to reduce the thickness of the casting (P) leaving the mold (15a) during the casting process, characterized in that the casting machine (11) equipped with a rolling device (16) with rolls located behind the mold (15a) and a pulling unit (18) located behind the said rolling device (16), which are selectively adjustable when changing the thickness (SN) of the strip metal to provide a controlled action to reduce the thickness casting (P), so that with the same dimensions of the mold (15a) to provide at least the first stage of production of the first strip having a first thickness (SN'), while the casting machine (11) is made and with the ability to provide the first degree of reduction in thickness (TAU A') of the casting (P) and the second stage of production of the second strip having a second thickness (SN'') less than the first thickness (SNT), and the casting machine (11) is configured to provide a second thickness reduction degree (TAU A'') of the casting (P) different from the first thickness reduction degree (TAU A'), wherein the thickness reduction degree is defined as the difference between the thickness (H) of the casting (P) at the outlet of the mold (15a ) and the thickness (SB2) of the billet at the outlet of the casting machine (11), correlated with the thickness (H) of the casting (P) at the outlet of the mold (15a).

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