RU2735643C1 - Method and device for production of flat rolled metal products - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method of making flat metal products, in particular rolls from a strip, in endless or semi-infinite mode, in which metal product is continuously supplied to rolling mill, which contains, in general, at least 4 stands, in which rolling mill stands are successively rough draft stands and finishing stands. Provided is variation of thickness on the move. At least rollers speed of the first stand of rolling mill and their gap are not changed during thickness change on the move. Transition from current thickness to subsequent thickness is performed by application of new adjustment of parameters, for example gap between rolls, speed of rolls and interstand tension, to all rolling stands involved in change of thickness on the move. Number of stands involved in change of thickness on the move, starting from the last stand of finishing stands, is obtained taking into account distribution of rolling force of each stand, so that new distribution of forces caused by thickness variation does not lead to any output of the rolling force of any stand from acceptable tolerance range.

EFFECT: higher reliability, stability of process, simplified control of stands, reduced wear and improved quality of finished strip.

10 cl, 11 dwg

Description

The technical field to which the invention relates

The present invention relates to a method and device for the manufacture of flat products, in particular for the production of rolls from a strip.

In particular, the present invention relates to modes of varying the final thickness of a metal strip, produced mainly, but not only, in an infinite and / or semi-infinite mode.

State of the art

Devices for hot strip production are known, starting with continuous casting of thin slabs. The strip making device can operate in several modes, separately or also simultaneously, that is, in endless, semi-endless and roll-to-roll mode.

Now, for the sake of clarity, we briefly outline the characteristics of the above three modes.

Endless: the process is continuous between the casting machine and the rolling mill. The cast slab is fed directly to the rolling mill without interruption. When the device is at full speed, material enters all machines simultaneously, from the outlet of the upstream mold to the downstream / downstream coiler / coilers. Thus, rolls are produced without interruption. Individual rolls are prepared by cutting with high speed shears in front of the coilers. There is only one entrance to the rolling mill at the beginning of the process.

Semi-endless: the process is interrupted between the casting machine and the rolling mill. A super-slab, equivalent to "n" (eg 2 to 5) normal slabs, where by "rate" we mean the amount of product required to make one roll, is obtained at the exit of the filling machine by pendulum shear cutting. From the corresponding super-slab, "n" coils are made at a time during rolling. Individual rolls are prepared by cutting with high speed shears in front of the coilers. For each sequence of "n" coils produced, there is one entrance to the rolling mill.

Roll-to-roll: from the casting machine to the rolling mill, the process is intermittent. At the exit from the casting machine, a separate slab is obtained by shearing with pendulum shears. One coil is made from the corresponding initial slab during rolling. There is one entrance to the rolling mill for each coil produced.

The rolling mill used can have several stands, usually in the range from 4 to 12. It is known, for example, from EP 2.569.104, that in an intermediate position along the mill, a rapid heating system is provided, which, at least in endless mode, determines the temperature recovery of the rolled product before the last rolling passes.

The position of the rapid heating system can generally determine the breakdown of the rolling mill into roughing stands upstream of the heating system and finishing stands downstream.

Thus, for roughing stands, which are the first stands of the rolling mill and perform the first reduction in thickness of the product at the entrance, and finishing stands, which complete reduction in thickness to the final value, the breakdown of the rolling mill can be represented, for example, as 2 + 4 , 2 + 5, 3 + 5.

It is known that, depending on production plans, during the rolling process, it may be necessary to change the thickness of the resulting finished strip. This change in thickness, at least in infinite and / or semi-infinite modes, can be performed without interrupting the rolling process, that is, during the passage of the material through the rolling stands, and is known as "thickness change on the go" (hereinafter FGC, from the English. Flying Gauge Change). Changing the thickness on the fly can take place by progressively changing the gap between the work rolls of the stands, for example, from the inlet to the outlet, until all the stands have been adapted to their operating parameters to obtain a new final thickness. With regard to the change in the gap, a coordinated change in the rotation speed of the rolls of each stand or part of the stands and the position of the tensioners or loop holders located between the stands can be provided.

Depending on the difference between the final thickness and the initial thickness, a change in thickness may affect all stands or only a part of them.

In the prior art there is document EP 1.010.478, disclosing a method for changing the thickness on the fly in a tandem cold rolling mill, using measurements of the thickness of the product at the exit from the stand (stand "i") to adjust the gap in the subsequent stand "i + 1", and adjusting rolling speed in the stand "i" to maintain a constant mass flow rate (thickness x speed) of the rolled product from the front of the material to the entrance of the stand "i + 1".

In addition, document EP 2.346.625 is known, in which, in order to carry out a thickness change on the fly (FGC) on a continuous rolling mill in an endless mode, it is provided that the transition from the first output thickness to the second output thickness occurs at the feed rate of the metal product into the first rolling stand mill, which is regulated depending on the rate of exit of the metal product from the casting machine located upstream of the rolling mill.

With the development of endless rolling processes, it has been confirmed that FGC processes during rolling can be improved in terms of product reliability and quality.

In particular, the control of changes in the downstream mass flow rate (as set forth in EP 2.346.625) requires that the timing between the casting process and the rolling process be controlled by the rolling speed as a function of the casting speed; therefore, every minimum change in mass flow rate of the casting process has consequences for the rolling process, creating a speed variance that is superimposed on them due to the change in thickness on the move (FGC). The presence of a possible reheating furnace between the casting machine and the rolling mill introduces another potential disturbance to the synchronization between the casting machine and the rolling mill due to temperature transitions in the slab within the furnace and due to the elasticity of the slab itself.

Thus, one of the objectives of the invention is to provide a method and associated apparatus for the manufacture of flat products that make the FGC for the strip being produced more efficient in terms of reliability, process stability, simplified stand control, reduced wear, improved quality. obtained finished strip and much more.

Applicant has developed, tested and implemented the present invention to overcome the disadvantages of the prior art and to achieve these and other objects and advantages.

The essence of the invention

The present invention is set forth and characterized in the independent claims. The dependent claims disclose other features of the invention or variations of the basic inventive idea.

According to the present invention, in the device for manufacturing products of flat metal products, the supply of metal products to a rolling mill is provided, which contains at least 4 stands, preferably 8 or more.

In particular, the device provides casting of thin slabs with a thickness of 60 mm to 140 mm and is designed to obtain final strip thicknesses from 0.7 mm to 20 mm in one of the following three operating modes:

a) endless, for final strip thicknesses from 0.7 mm to 6.0 mm;

b) "semi-infinite", for final strip thicknesses from 0.7 mm to 6.0 mm;

(c) “roll-to-roll”, for final strip thicknesses from 1.2 mm to 20 mm.

Preferably, the device control system allows automatic switching from one mode to another using the most convenient mode in each case.

The choice for operation in accordance with one of the three above modes is made:

- depending on the grade of the steel obtained (for example, low carbon steel, medium carbon steel, HSLA, two-phase, API class);

- to obtain different classes of final strip thicknesses, optimizing the manufacturing process;

- to optimize the speed, rolling temperatures and associated energy consumption;

- to adapt the casting speed to the existing liquid steel production so as not to interrupt the casting sequence.

Thus, in each case, the most suitable operating mode can be selected, optimizing energy saving, output and plant utilization for each mode.

Thus, the device takes advantage of all the prerogatives of the infinite mode (the ability to obtain ultra-thin thicknesses and energy savings), which retains its advantages while overcoming its limitations, and therefore can be defined as “universal infinite mode”.

Preferably, endless mode is used for all steel grades that can be cast at high speeds, typically in excess of 4.5 m / min.

To achieve the foregoing, the device essentially contains five main elements, located relative to each other in the sequence shown below:

- continuous casting machine;

- tunnel oven for possible heating and temperature maintenance / equalization;

- a roughing mill containing from 1 to 4 rolling stands;

- rapid heating unit with elements that can be selectively activated and removed from the line;

- finishing mill, containing from 3 to 7 stands;

- loopers, or tensioners, installed in all intermediate stands, from the first roughing stand to the last finishing stand, preferably driven by hydraulic drives to maintain a constant tension between two successive stands and to control mass flow.

According to a characterizing aspect of the apparatus, a tunnel oven for optional heating and temperature maintenance, located between the continuous casting machine and the roughing stand, has a length many times longer than the length of the slab for semi-endless rolling, resulting in 2 to 5 coils.

Thanks to this size of the tunnel kiln, the device can be easily converted from “endless” mode to “semi-infinite” or “roll-to-roll” mode, in particular when it is required to produce steel grades that cannot be produced in an infinite mode, as they must be cast at low casting speeds.

Thus, the tunnel kiln allows the casting machine to be disconnected from the rolling mill when the cast steel grade requires the casting speed to be reduced to values that make the endless process impracticable.

In addition, the potential of the tunnel kiln to accommodate slabs of multiple lengths up to 5 rolls is guaranteed by a storage device, with which it is possible to control possible stops during the roll-to-roll rolling process, without significant consequences for the casting process, which can thus continue to function in for a certain time. In this way, the productivity of the melting plant that feeds the continuous casting machine is optimized.

The temperature of the slab exiting the tunnel kiln ranges from about 1050 ° C to about 1150 ° C in roll and semi-infinite modes, and from about 1150 ° C to 1180 ° C in endless mode, depending on the steel grade and final strip thickness.

As mentioned above, the length of the tunnel kiln also determines the buffer time obtained in roll-to-roll mode during scheduled roll changes and / or during unexpected rolling mill shutdowns due to scrap or minor abnormalities.

The buffer time allows to increase the utilization rate of the installation, and also allows to increase the production of the installation, since the number of casting restarts is eliminated or at least reduced, with a subsequent reduction in scrap at the beginning and at the end of the casting process, and also allows avoiding the transformation into scrap steel, which at the moment the abnormal situation is in the tundish at the beginning of the rolling mill, as well as remaining in the casting ladle, which is often impossible to return to its original state.

At the end of the tunnel kiln, a module (last or penultimate) is provided, which is transversely movable for laterally dumping slabs in case of an accident. This module, or switching unit, also makes it possible to connect a possible second casting line parallel to the first.

The rapid heating unit consists of an inductor with modular C-shaped elements that can be removed individually (automatically or manually) from the rolling line when not required.

The rapid heating device is always used in endless mode and can also be used in semi-endless mode.

According to its heating parameters and dimensions, it is made so that the strip in endless and / or semi-endless modes leaves the last rolling stand of the finishing mill with a temperature of at least 830-850 ° C.

The heating power supplied by the inductor unit is automatically controlled by a control unit, in which the calculation program takes into account the temperatures measured along the rolling mill, the intended rolling speeds, the thickness of the finished profile and therefore the calculated temperature losses.

In this way, the heating is optimized and rolling at a uniform temperature is achieved, starting right from the first coil.

In addition, the invention makes it possible to perform a change in thickness (FGC) of the metal product exiting the rolling mill during the rolling process.

In particular, FGC is used during endless and / or semi-endless rolling to change the thickness of a coil following one that has already been completed, or even in the same coil. Depending on the required thickness difference, changes in thickness may affect the finishing stands or only parts of them.

Roughing stands, the change in thickness affects only when it is required to change the thickness of the product leaving the roughing stands (rolled slab), which is fed into the finishing stands.

In accordance with the invention, the first stand of the rolling mill, that is, the one that the material supplied, for example, from continuous casting, meets first, acts as the main stand, while the process of changing the strip thickness does not affect any of its parameters. In particular, the rotation speed of the rolls of the first stand and their gap do not change.

The advantages that result from the absence of a change in the operating parameters of the first rolling stand are as follows.

The power of the first rolling stand is much higher than the total power of the roller motors of the extractor downstream of the casting machine; this makes it more advantageous, in terms of the efficiency of adjusting the synchronization between the casting speed and the rolling mill speed in endless mode, to use the first rolling stand in the main mode (set speed) and to use the extractor casting in slave mode (variable speed).

For this reason, the invention provides for the use of the first rolling stand as the main drive, which determines the speed of the entire casting and rolling line.

The speed of the material entering the rolling stand is determined by the rotation speed of the rolling rolls and the position of the so-called neutral opening angle of the mill rolls. While the first value (roller speed) can be adjusted independently of the rolling process (endless and / or semi-infinite), the second value (neutral angle position) depends on the type of rolling process being performed (force / reduction).

In the case of an endless rolling process according to the present invention, a change in thickness (the difference between the thickness at the entrance and the thickness at the exit of the rolling mill) results in a change in the speed at the entrance to the stand, which is propagated to the casting machine.

In order to prevent disruptions in the casting process with negative consequences for product quality, the invention provides a constant reduction in the first rolling stand and therefore does not change even during the FGC process.

Thus, by combining the use of the first rolling stand as a speed controller during endless rolling with the operational practice of maintaining a constant reduction in said first rolling stand of the mill, separation of mass flow deviations due to rolling mill synchronization is preferably achieved. These deviations can be compensated upstream with respect to mass flow deviations due to changes in thickness on the fly, which are instead compensated downstream.

Regarding the calculation of rolling forces / torques, speed cones of stands, inter-stand tension of stand deflection and strategies for determining the correct installation of profiles and flatness drives, we refer to what is already known from the literature, for example, from the book by Vladimir B. Ginzburg (Vladimir V. Ginzburg) "Steel Rolling Technology, theory and practice"

In accordance with one aspect of the invention, the main drives used during thickness changing on the fly are hydraulic compression drives and rolling stand motors, inter-stand loop holders and drives for controlling the profile and flatness of the strip, i.e., switching drives and bending (or counter-bending) drives. ...

By means of these drives, the operating parameters of each individual rolling stand are set, hereinafter referred to as "settings" for brevity, which include: the rotation speed of the rolls or rolls of the stand (or simply the speed of the stand), the distance between the rolls (or gap), which determines the strip thickness at the exit from the stand, the rolling or compression force, bending (or counter-bending force) applied to the rolls and their displacement to control the flatness and profile of the strip, tension of the strip between two adjacent stands.

In order to change the thickness on the fly (FGC), the main set operating parameters are mainly the following three: speed (rolls) of the stand, the gap between the rolls / rolls, inter-stand tension.

The number of stands involved in the change in thickness on the fly (FGC) is determined based on the difference in absolute value between the current thickness and the new final thickness in accordance with the capabilities of the rolling stands (power, speed, torques) and process parameters (rolling temperature, profile / flatness and mechanical properties of the strip).

To ensure that good profile / flatness is maintained, even in the strip portion of the strip that is involved in a thickness change (FGC), the force distribution of the current setting and the new setting must match the base distribution with a tolerance interval.

Suppose that by changing the thickness on the fly (FGC), the final thickness of the strip is changed and, in particular, its reduction is performed.

To maintain a constant strip thickness (rolled slab) at the exit from the roughing stand, that is, at the entrance to the first rolling stand of the finishing mill, the total rolling force (that is, the sum of the individual rolling forces on all finishing stands) must be increased.

If this increase in force can only be absorbed by the last finishing stands, for example the last two, while remaining within an acceptable tolerance, then the FGC can only be applied to these two stands.

If this increase in force cannot be absorbed by only the last two stands, because at least one of them the force will be outside the acceptable tolerance, then the change in thickness on the move (FGC) will have to be applied to a larger number of stands, possibly to all finishing mill, and possibly, if necessary, to the last stands of the roughing mill.

In this case, the new distribution of forces will follow a trend similar to the basic one, but with a force value slightly higher in each rolling stand compared to the previous rolling map.

In addition, it should be noted that with each final thickness is associated a corresponding range of thicknesses of the rolled slab, that is, the product leaving the last roughing stand.

The thicknesses of the rolled slab are a finite number calculated so that a set of final thicknesses with the following characteristics correspond to each rolled slab:

- all final thicknesses must be rolled with the same number of finishing stands;

- the thickness of the rolled slab must be obtained from the thickness of the slab in accordance with the capabilities of the roughing stands and technological limitations (rolling temperature, profile / flatness of the rolled slab, mechanical properties of the rolled slab).

In some solutions of the invention, the change in thickness on the fly (FGC) can occur in two modes.

The first embodiment, according to the present invention, for performing the change in thickness on the fly (FGC), provides for the execution of the final change in thickness in two stages. This two-stage mode has the advantage of minimizing the over-gauge segment of the strip and is mainly used when more than two stands are used to change the thickness on the fly (FGC).

In particular, the application of a new setting for the roll gap, stand speed and inter-stand tension for rolling stands participating in the change in thickness is as follows:

- at the first stage, a new target thickness is applied, as well as a new speed cone, that is, the base value for the rotation speed of the work rolls of the rolling stands, and

- at the second stage, a new inter-stand tension is applied by means of loop holders or tensioners.

In more detail, when the section of the strip that undergoes a change in thickness reaches a certain stand (n-th stand), the gap of that stand changes from the current gap to a new gap calculated to obtain the next thickness with the current inter-stand tension. At the same time, the rotation speed of the rolls is increased or decreased, depending on the new thickness, to keep the mass flow rate (thickness x speed) constant.

The upstream stands and casting do not participate in any tuning changes.

The inter-stand tension between the stand (n-th) and stand (n + 1-th) changes only when the section of the strip participating in the change in thickness reaches the next stand (n + 1-th).

Simultaneously with the change in the inter-stand tension, the gap and the speed of the n-th stand are additionally adjusted depending on the new value of the inter-stand tension, completing the transition to a new setting for the n-th stand.

Regarding the new setting for strip flatness and profile (with bend and shear drives), this is applied when the section of the strip involved in the change in thickness reaches the nth stand.

This two-stage FGC mode is then applied to all subsequent stands as soon as the strip section involved in the thickness change reaches each of the stands.

The rolling mill control system provides a tracking function to update in real time the exact position of the strip section / sections involved in the thickness change along the entire rolling mill.

All changes from the current to the new setting are linear, the slope of the linear characteristic is calculated taking into account the dynamic characteristics of the drives used: the dynamics of change is determined by the slowest drive.

In a second embodiment of the present invention, in order to perform the on-the-fly thickness change (FGC), it is provided that the final thickness change is performed by means of stands at the same time. This simultaneous operation has the advantage of simplifying the adjustment of the rolling stands and is therefore advantageous from the point of view of reliability.

This mode is mainly used when up to two stands are involved in the on-the-fly thickness change (FGC).

The transition from the current thickness to the next thickness occurs by simultaneously applying a new setting to all stands participating in the thickness change.

If there are more than two stands involved in changing the thickness on the fly (FGC), then the setting change can be successfully applied successively in the first stands and simultaneously in the last two or more stands. This is done to reduce the length of the transition strip segment from current thickness to new thickness while maintaining good stability of the rolling process.

More specifically, taking into account the new setting, the following parameters are simultaneously applied to all involved stands: rotation speed, clearance, inter-stand tension, flatness and profile.

In simultaneous mode, the inter-stand tension adjusters (loop holders or tensioners) perform the function of maintaining the correct mass flow during the transition from the current thickness to the new thickness. Inter-stand tension regulators for stand speed downstream. In addition, the speed of the first stand to participate in the FGC is controlled by adjusting the upstream inter-stand adjuster.

The roll gap adjuster of the first stand participating in the on-the-fly thickness change (FGC) is simultaneously maintained in a position control state. The roll gap adjuster of all other downstream stands participating in the change of thickness on the fly is switched from position control to force control before applying the new setting.

In the simultaneous mode, the purpose of switching to force control is to make it possible for each stand to apply a new reduction setting, starting from the calculated force for the new output thickness, without knowing the exact input thickness.

As soon as the end of the transition strip segment reaches the roll gap of the stand, the roll gap adjuster is switched to position control to ensure proper strip thickness at the exit of each stand.

The application of the new parameter setting is coordinated by a dedicated tracking function.

In the simultaneous mode, all changes from the current setting to the new setting are linear, the ramp angle is calculated in relation to the dynamic characteristics of the drives used, the dynamics of change is determined by the slowest drive.

As noted, in some situations where only finishing stands are not sufficient to change the thickness, some roughing stands may also be involved, in particular one or more stands after the first roughing stand.

Also in this case, according to the invention, the speed of the first roughing stand does not change. To determine how many roughing stands, starting with the last one, must be used when changing the thickness on the go, you can use the same criterion as described above for finishing stands, that is, to estimate how many roughing stands should participate in changing the thickness based on the maximum allowable compressive force ...

As already mentioned, the material feed rate, in this case the casting rate, remains constant, as is the case for all operating parameters of the first roughing stand.

Brief Description of Drawings

These and other characteristics of the present invention will become apparent from the following description of some embodiments, given by way of non-limiting example with reference to the accompanying drawings, in which:

- in Fig. 1 is a schematic illustration of an example of a device for producing flat products in accordance with some of the characteristics of the present invention;

- in Fig. 2-6 are schematic diagrams of embodiments of a method for changing thickness on the fly, used in a method for producing flat products in accordance with some of the characteristics of the present invention;

- in Fig. 7 shows a table relating to an example of changing parameters when changing from one thickness to another;

- in Fig. 8-11 show exemplary plots of defining criteria for stands involved in thickness variation.

To facilitate understanding, the same reference numbers have been used where possible to denote identical common elements in the drawings. It is understood that elements and characteristics from one embodiment can be successfully incorporated into other embodiments without further explanation.

Implementation of the invention

We will now consider in detail various embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. Each example is presented to illustrate the invention and should not be construed as limiting it. For example, characteristics shown or described insofar as they are part of one embodiment may be adopted in or in connection with other embodiments to provide another embodiment. It is understood that the present invention should include all such modifications and variations.

FIG. 1 generally and schematically shows an example of an apparatus 10 for producing flat products, in which the on-the-fly thickness changing method disclosed below can be applied. It will be understood that the embodiment shown in FIG. 1 is only an example to simplify the understanding of the invention, which is not mandatory for the application of the concepts presented below.

It will also be understood that not all of the components shown are necessary and essential for the proper functioning of the device.

For example, the device 10 contains a control system suitable for receiving instructions regarding cards related to certain casting processes, as well as for certain changes in the thickness of the final product to be manufactured, and for adjusting the operating parameters of all rolling stands as a result of changes in thickness by go as indicated above.

In general, the device 10 contains as constituent elements:

- machine 11 continuous casting, containing the mold 12;

a possible first descaling device 13;

- pendulum scissors 14;

- a tunnel kiln 15 having at least one last module 115a-115b, made with the possibility of lateral movement;

- oxygen-acetylene cutting device 16;

a possible second descaling device 113;

- possible vertical or edging stand 17;

- the third device 213 descaling;

- three roughing rolling stands 18a, 18b, 18c;

- trimming shears 19 for trimming the front and rear ends of the strip to facilitate entry of the strip into the first stand of the finishing mill; they can also be used for emergency cutting in the event of a blockage in the finishing mill at endless operation;

- modular device 20 fast induction heating;

- an intensive cooling system (not shown), located downstream of the rapid heating device, used if it is necessary to implement a thermomechanical rolling process or a ferrite field rolling process in a finishing stand;

- the fourth device 313 descaling;

- finishing rolling mill, containing in this case five stands, respectively - 21a, 21b, 21c, 21d and 21e;

- shower-type devices 22 for laminar cooling;

- high speed flying shears 23 for cutting the strip to size in order to divide the strip, when it directly interacts with the coilers, into rolls of the required weight; and

- a pair of coilers, respectively a first coiler 24a and a second coiler 24b.

The casting and rolling process carried out by the device 10 can take place in endless, semi-endless and roll-to-roll modes.

FIG. 2-6 are graphs showing, by changing the specified specific parameters, the modes of changing the thickness on the move for a strip of the type that is applicable in the device 10 described above, in particular, in the above-mentioned infinite and / or semi-infinite modes.

In the first embodiment shown in FIG. 2, only the finishing stands 21a-21e, designated F1-F5, participate in the thickness change, which occurs in a two-stage mode.

As can be seen from the graphs, when observing lines running from top to bottom, when it is necessary to change the final thickness of the rolled strip on the fly, the set value of the new thickness is determined in the first finishing stand F1. In this case, the new thickness is less than the previous one (thickness reduction).

At the first stage, a new gap is set between the rolls corresponding to the new thickness of the first finishing mill F1, while the speed of the rolls of the same stand F1 is simultaneously increased until it reaches the new set value.

The second step involves applying a new inter-stand tension setting, in which case the strip tension is increased.

All subsequent stands F2-F5 progressively adjust their speed, both depending on each change in the speed of the previous stand, and depending on the moment when the final end of the transition segment reaches the stand itself.

As can be seen from the trend of the last line, the material feed rate, in this case the casting speed, remains constant, as well as the speed of all stands upstream of stand F1, that is, all roughing stands.

In the second embodiment shown in FIG. 3, only the finishing stands 21a-21e, designated F1-F5, participate in the change in thickness, which, however, unlike previously observed, occurs simultaneously.

As you can see, the speed control of all stands F1-F5 takes place at the same time, while the thickness is adapted sequentially, stand by stand, from the previous value to the final target value.

The feed rate of the material, in this case the casting speed, remains constant, as does the speed of all stands upstream of stand F1, that is, all roughing stands.

In another embodiment, shown in FIG. 4, some roughing stands are also involved, in this case stands 18b, 18c, located downstream of the first stand 18a. Roughing stands 18a-18c are designated on the graphs as Н0-Н2.

According to the invention, as can be seen, the speed of the first stand H0 does not change, as well as other operating parameters of the same stand H0. The first stand involved in changing the thickness is the (second) stand H1, with the rotation speed of the rolls being controlled in two stages. The same applies to the (third) stand H2.

The material feed rate, in this case the casting speed, remains constant, as does the speed of the first roughing stand Н0.

FIG. 5 shows in more detail a first embodiment of a two-stage thickness variation for a single stand (nth); in particular, it can be observed when new settings for inter-stand tension and new settings for profile size and flatness are activated.

FIG. 6 shows in more detail a second embodiment of the simultaneous thickness variation for a single stand (nth); in particular, you can observe how all settings are activated at the same time: applying a new force setting (in this case an increase in compression / compression, the penultimate line on the graph) entails the simultaneous application of a new gap setting (that is, reduction in thickness); the settings of the inter-stand tension, as well as the profile and flatness drives, are changed simultaneously.

The new speed setting is calculated from the previous setting to keep the mass flow rate unchanged.

In particular, the formula for calculating the new setting can be expressed as follows:

Subsequent roll speed = (current roll speed) * (thickness in stand (n-th) - subsequent) / (thickness in stand (n-th) - current).

FIG. 7 (Table 1) shows, by way of example only, an example of changing the parameter setting, from the current setting to the next setting, in the case of changing the final strip thickness of approximately 3 mm to the final strip thickness of approximately 2.3 mm.

As you can see, in this case, changing the parameter setting only affects the finishing stands F1-F5. A decrease in the final strip thickness is accompanied by an increase in the roll speed of the stands, as well as an increase in the compressive force. The inter-stand tension also increases depending on the thickness reduction to be obtained.

FIG. 8-11 describe modes in which another embodiment of the invention calculates the number of stands participating in the FGC. In particular, consider as an example the case where there is no need to change the thickness of the rolled slab, and the finishing mill contains 5 finishing stands, in relation to the scheme shown in FIG. 1.

A typical distribution of the rolling force across the various stands is shown in FIG. eight.

The central solid line represents the distribution of base forces, while the two dashed lines above and below define the upper and lower tolerance limits in which the rolling force can be varied without compromising the quality of the finished product. Suppose that the final strip thickness is changed by the FGC, and in particular that it is reduced.

Maintaining a constant thickness of the rolled stock (rolled slab) entering the first rolling stand of the finishing mill, the total rolling force (that is, the sum of the individual rolling forces on 5 stands) must be increased. As can be seen in FIG. 9, the effective rolling force in the last two stands increases, but remains within the permissible upper tolerance limit. Therefore, the change in thickness can be carried out by the last two stands of the finishing mill, without involving other stands located upstream.

If, on the other hand, the new distribution of forces causes the rolling force even in one of the stands to be outside the acceptable tolerance, as shown in FIG. 10, then the FGC cannot only be applied to the last two stands, but at least one more stand upstream must be used.

FIG. 11 shows how the new force distribution in the finishing mill results in a trend similar to the original trend in FIG. 8, but with a large force value in all stands, that is, the force curve in all 5 finishing stands has the same trend, but with an increased value compared to the initial one.

It will be understood that modifications and / or additions to the elements of the apparatus 10 and the method for making the strip disclosed earlier can be made without departing from the scope and scope of the present invention.

Claims (12)

1. A method of manufacturing products of flat metal products, in particular coils from a strip, in an endless or semi-endless mode with the possibility of changing the thickness of the products on the fly, comprising continuously feeding a metal product to a rolling mill containing, in general, at least 4 stands, in which rolling The stands are sequentially roughing stands (18a, 18b, 18c) and finishing stands (21a, 21b, 21c, 21d, 21e), characterized in that at least the rotation speed of the rolls of the first stand (18a) of the rolling mill and their gap do not change during the time of changing the strip thickness on the fly, and the transition from the current thickness to the next thickness occurs by applying a new setting of parameters, for example, the gap between the rolls, the speed of the rolls and the inter-stand tension, to all rolling stands involved in changing the thickness on the go, while the number of stands, involved in changing the thickness on the go, starting from the last stand (21e) from the finishing stands, are obtained taking into account the distribution the rolling force of each stand, so that the new distribution of forces due to the change in thickness does not lead to any output of the rolling force of any stand from the acceptable tolerance range. 2. The method according to claim 1, characterized in that the change in thickness on the fly is applied without changing the speed of the material supplied to the rolling mill. 3. The method according to claim 1 or 2, characterized in that the application of a new setting of the gap between the rolls, the speed of rotation of the rolls and the inter-stand tension to the stands involved in changing the thickness on the fly is as follows: - at the first stage, a new target thickness and a new speed cone are applied, that is, the base value of the rotation speed for the work rolls of the rolling stands, and - at the second stage, a new inter-stand tension is applied by means of loop holders or tensioners. 4. The method according to claim. 3, characterized in that when the section of the strip subject to the change in thickness reaches a certain stand (n-th stand), the gap of this stand is changed from the current gap to a new gap calculated to obtain the next thickness with the current inter-stand tension, with the stand speed increasing or decreasing depending on the new thickness to keep the mass flow rate (thickness x speed) constant. 5. The method according to claim 4, characterized in that the inter-stand tension is changed only when the section involved in changing the thickness reaches the next stand (n + 1-st), while simultaneously with the change in the inter-stand tension, the gap and the speed n- stand, completing the transition to the new setting for the n-th stand. 6. A method according to claim 1 or 2, characterized in that the transition from the current thickness to the next thickness occurs by applying a new setting to the active rolling stands, while the application of the new setting occurs simultaneously for all involved stands. 7. The method according to claim 6, characterized in that if there are more than two stands involved in changing the thickness on the fly, then the setting change is applied sequentially in the first stands and simultaneously in the last two or more stands. 8. The method according to any one of claims. 1-7, characterized in that all changes from the old to the new setting are performed linearly. 9. The method according to any one of claims. 1-8, characterized in that in the case when a new distribution of rolling forces due to a change on the run causes a departure from the acceptable tolerance range, then in the process of changing the thickness at least a new rolling stand located upstream of the already provided stands. 10. A device for the production of flat products in an endless mode, comprising at least one continuous casting machine (11) containing a mold (12), a rolling mill containing roughing stands (18a, 18b, 18c) and finishing rolling stands (21a 21b, 21c, 21d and 21e), high speed flying strip shears (23) for cutting the strip to size, intended for use in endless rolling to divide the strip interacting with the coilers into coils of the desired weight; and a pair of coilers (24a, 24b), and a control system is provided that is suitable for applying the method of manufacturing flat metal products according to any one of claims. 1-9.

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