EP2595768B1 - Method for determining wear on a roll for rolling metal stock - Google Patents

Description

The present invention relates to a determination method for a wear of a roll for rolling of rolling stock.

The present invention further relates to a computer program which comprises machine code which can be processed directly by a computer and whose execution by the computer causes the computer to carry out such a determination method.

The present invention further relates to a computer adapted to carry out such a determination method.

The present invention further relates to a rolling mill for rolling of rolling stock, which is equipped with such a computer.

When rolling metals occurs on the rollers wear. The extent to which wear occurs depends on various parameters. For example, the amount of wear depends on the type of rollers (work roll, backup roll,...), The type of rolling (cold rolling or hot rolling), the arrangement of the rolls in the rolling mill (first, second, third rolling stand of the rolling mill, etc.), the material of the rolling stock (steel, aluminum, copper, ...), the material of the rolls (cast iron, cast steel, high speed steel, ...) etc.

The wear has an impact on the quality of the rolled stock. In particular, the wear must be taken into account and, if possible, compensated for by appropriate adjustments to the setting - if necessary also with regard to profile and flatness - for flat rolled stock. Continue to have The rollers are changed from time to time and reground.

A direct measurement of the roller wear is only possible if the relevant roller is removed from the rolling stand and can be measured. In the ongoing rolling process, however, a direct measurement of the roller wear is not possible. However, it is known to detect process variables of the rolling process and to account for the roll wear by means of a wear model in real time. By means of the wear model, the wear of the respective roller is determined as a function of the rolled section of the rolling stock, the course of the rolling force over this distance, etc. The wear model makes the determined wear available to other control systems, for example for the corresponding correction of the employment.

It is also known to carry out similar calculations offline. The process variables used in this case may be, for example, model-based expected expected quantities.

As a rule, the determination of the wear takes place according to the relationship $$d=c\cdot \mathrm{\Phi }\cdot \alpha \cdot l$$

Here, d is the expected wear, c a constant coefficient of wear, Φ the pressure distribution in the roll gap, α the contact angle and l the rolled length.

The wear coefficient c is set appropriately. It may depend on the above parameters.

When rolling, a thermal crown must also be determined as part of the determination of manipulated variables for profile and flatness actuators. This is done in the prior art, characterized in that during operation continuously a volume temperature distribution of the roller on the basis of a surface the roll occurring heat flow distribution is updated by means of a temperature model of the roller. The volume temperature distribution is in this case spatially resolved at least in the axial direction and in the radial direction of the roller, the heat flow distribution in the axial direction and in the tangential direction of the roller.

The terms "axial direction", "radial direction" and "tangential direction" are always referenced above and also to the axis of rotation of the roller The axial direction is parallel to the axis of rotation The radial direction is orthogonal to the axis of rotation The tangential direction is at a constant distance from the axis of rotation around the axis of rotation.

By way of example, with regard to the prior art procedure, reference is made to the technical article " An Investigation into the Control of Thermal Camber by Hot Rolling Aluminum "by PA Atack et al., Modeling of Metal Rolling Processes Symposium 7, Cooling in rolling mills, June 7, 1995 in London on, directed. The determination of the thermal crown takes place within the scope of the cited technical article using a volume temperature distribution which is not spatially resolved in the tangential direction. The heat flux distribution is averaged in the tangential direction. Using the averaged heat flux distribution, the volume temperature distribution is updated and tracked.

From the technical paper " Increasing work-roll life by improved roll-cooling practice "by PG Stevens et al., Journal of Iron and Steel Institute, January 1971, pages 1 to 11 , it is known that the wear of rollers can also include a thermal wear component and that the thermal wear component to a first approximation by various rolling and rolling parameters and by the variables "maximum surface temperature", "minimum surface temperature" and "temperature inside the roller" is determined.

From the JP 4 197 507 It is known to determine the wear of a roll on the basis of an axial temperature profile in the roll.

The object of the present invention is to provide opportunities to determine the wear of the roller in a reliable model-based manner.

The object is achieved by a preliminary investigation with the features of claim 1. Advantageous embodiments of the investigation process are the subject of the dependent claims 2 to 13.

• dass eine Volumentemperaturverteilung der Walze anhand einer an der Oberfläche der Walze auftretenden Wärmeflussverteilung mittels eines Temperaturmodells der Walze aktualisiert wird,
• dass die Volumentemperaturverteilung zumindest in Axialrichtung und in Radialrichtung der Walze ortsaufgelöst ist,
• dass die Wärmeflussverteilung in Axialrichtung und in Tangentialrichtung der Walze ortsaufgelöst ist,
• dass der Verschleiß der Walze mittels eines Verschleißmodells ermittelt wird,
• dass im Rahmen des Verschleißmodells
  • -- anhand der aktualisierten Volumentemperaturverteilung und/oder der Wärmeflussverteilung mindestens eine obere Oberflächentemperatur ermittelt wird, welche an bestimmten Punkten der Oberfläche der Walze auftritt, während der jeweilige Punkt mit dem Walzgut in Kontakt ist, und
  • -- der Verschleiß der Walze unter Berücksichtigung der oberen Oberflächentemperatur der Walze ermittelt wird.

According to the invention, it is provided to design a preliminary method of the type mentioned in the introduction,

• that a volume temperature distribution of the roll is updated by means of a heat flow distribution occurring at the surface of the roll by means of a temperature model of the roll,
• the volume temperature distribution is spatially resolved at least in the axial direction and in the radial direction of the roller,
• the heat flow distribution is spatially resolved in the axial direction and in the tangential direction of the roll,
• that the wear of the roller is determined by means of a wear model,
• that under the wear model
  • - Based on the updated volume temperature distribution and / or the heat flow distribution at least an upper surface temperature is determined, which occurs at certain points of the surface of the roller, while the respective point is in contact with the rolling stock, and
  • - The wear of the roller is determined taking into account the upper surface temperature of the roller.

In order to determine the upper surface temperature from the data of the temperature model, ie the updated volume temperature distribution and the heat flow distribution, there are two possibilities.

• dass anhand von auf das Walzen des Walzguts durch die Walze bezogenen Prozessgrößen in Axialrichtung ortsaufgelöst jeweilige Kontaktzeiten ermittelt werden, die dafür charakteristisch sind, wie lange der jeweilige Punkt der Walze während eines Umlaufs der Walze mit dem Walzgut in Kontakt ist, und
• dass die obere Oberflächentemperatur anhand der durchschnittlichen Oberflächentemperaturverteilung der Walze, desjenigen Teils der Wärmeflussverteilung, der während des Kontakts der Walze mit dem Walzgut auftritt, und der Kontaktzeiten ermittelt wird.

On the one hand, it is possible that the volume temperature distribution in the tangential direction of the roller is not spatially resolved. In this case, the updated volume temperature distribution defines an axially resolved average surface temperature distribution characteristic of an average surface temperature of the roll. In this case, the upper surface temperature can be determined by

• in that spatially resolved respective contact times are determined on the basis of process variables relating to the rolling of the rolling stock by the roll, which characteristic how long the respective point of the roll is in contact with the rolling stock during one revolution of the roll, and
• in that the upper surface temperature is determined on the basis of the average surface temperature distribution of the roll, that part of the heat flow distribution which occurs during the contact of the roll with the rolling stock, and the contact times.

On the other hand, it is possible that the volume temperature distribution is also spatially resolved in the tangential direction of the roller. In this case, it is possible to determine the upper surface temperature only from the updated volume temperature distribution.

The wear preferably comprises a thermal wear component. The determination of the thermal wear component can be carried out, for example, by using the upper surface temperature and at least one further surface temperature of the roller related to the surface of the roller. As an alternative to drawing on the further surface temperature related to the surface of the roll, an internal temperature distribution given inside the roll can be used.

The wear preferably further comprises an abrasive wear portion. The determination of the abrasive wear component is preferably carried out using a surface hardness of the roller. The surface hardness of the roll in this case becomes using the upper surface temperature the roller determined. The determination of the abrasive wear portion can be carried out with additional use of a temperature and / or the material composition of the rolling stock.

It is possible that the heat flow distribution is given as such. However, the heat flow distribution is preferably determined on the basis of process variables related to the rolling of the rolling stock by the roll and an initial surface temperature distribution of the roll defined by the not yet updated volume temperature distribution.

It is possible that the process variables are (at least partially) model-based expected expected quantities. Alternatively, it is possible that the process variables are (at least partially) actual variables which are detected during rolling of the rolling stock by the roll. Also mixed forms are possible. For example, based on actual variables detected during rolling, a first wear value can be determined which is currently expected. Based on the currently expected wear value, a prognosis of the later occurring wear can then be made on the basis of future expected corresponding process variables.

The determination process can be performed in real time during rolling of the rolling stock by the roll. Alternatively, it may be performed by the roller before rolling the stock. An execution after rolling of the rolling stock by the roller is possible.

It is possible to determine the wear only and output, for example, to an operator of the mill. Preferably, however, the determined wear is taken into account as part of the determination of manipulated variables, which influence the rolling of the rolling stock.

The object of the invention is further achieved by a computer program of the type mentioned. The computer program is configured in this case such that the computer carries out a determination process with all steps of a determination method according to the invention.

The object is further achieved by a computer which is designed such that it carries out such an operating method.

The object is further achieved by a rolling mill for rolling flat rolling stock, which is equipped with such a computer.

FIG 1

schematisch ein Walzwerk zum Walzen eines Walzguts,

FIG 2

ein Ablaufdiagramm,

FIG 3

eine mögliche Volumentemperaturverteilung,

FIG 4

eine Scheibe einer weiteren möglichen Volumentemperaturverteilung,

FIG 5

Oberflächentemperaturverteilungen,

FIG 6 und 7

Ablaufdiagramme,

FIG 8 und 9

Formeln,

FIG 10

ein Ablaufdiagramm,

FIG 11

eine Formel und

FIG 12 bis 14

Ablaufdiagramme.

Further advantages and details will become apparent from the following description of exemplary embodiments in conjunction with the drawings. In a schematic representation:

FIG. 1

schematically a rolling mill for rolling a rolling stock,

FIG. 2

a flow chart,

FIG. 3

a possible volume temperature distribution,

FIG. 4

a slice of another possible volume temperature distribution,

FIG. 5

Surface temperature distributions,

FIGS. 6 and 7

Flowcharts,

FIGS. 8 and 9

formulas

FIG. 10

a flow chart,

FIG. 11

a formula and

FIGS. 12 to 14

Flowcharts.

The present invention will be explained in more detail below in connection with the rolling of a flat rolled stock 1. This embodiment represents by far the most common application of the present invention. In principle, however, the present invention is applicable to any rolling stock 1, for example rod-shaped rolling, tubular rolling or profiled rolling.

According to FIG. 1 For example, a rolling mill for rolling the flat rolling stock 1 has a plurality of rolling stands 2. The rolling stands 2 are run through by the flat rolling stock 1 in succession. Each rolling stand 2 of the rolling mill has rollers 3. The rollers 3 comprise at least work rolls, often also other rolls, for example support rolls or - in addition to back-up rolls - intermediate rolls.

The number of rolling mills 2 of the rolling mill shown is purely exemplary. Minimal is only a single stand 2 available. Furthermore, it is not mandatory that a strip running direction x, as in FIG. 1 represented, is always the same. Alternatively, a reversing rolling could take place, in particular if the rolling mill has only one single rolling stand 2 or only two rolling stands 2.

The flat rolled stock 1, which is rolled in the rolling mill, as shown in FIG FIG. 1 a band. Alternatively, however, it may be another flat rolled stock 1, for example a plate or a heavy plate.

The rolling mill is equipped with a computer 4. The computer 4 is designed as a control computer that controls the rolling mill. The computer 4 is therefore subsequently - at least in the rule - referred to as the control computer 4. In principle, however, the computer 4 could be another computer which does not control the rolling mill but is otherwise connected to the rolling mill or is not connected to the rolling mill at all.

The control computer 4 is usually designed as a software programmable device. The operation of the control computer 4 is determined by a computer program 5, which is the control computer 4 via a computer-computer connection (not shown) or a storage medium 6 is supplied. Also, the storage medium 6, the computer program 5 in machine-readable form - usually in electronic form - stored. The storage medium 6 is according to FIG. 1 as a USB memory stick educated. However, this embodiment is purely exemplary. Any other configurations of the storage medium 6 are possible, for example as a CD-ROM or as an SD memory card.

The control computer 4 is programmed with the computer program 5. The computer program 5 includes machine code 7, which is directly executable by the control computer 4. The execution of the machine code 7 determines the operation of the control computer 4. The execution of the machine code 7 by the control computer 4 causes the control computer 4 to carry out a determination process, which is described below in connection with FIG FIG. 2 is explained in more detail. The programming of the control computer 4 with the computer program 5 effects the corresponding design of the control computer 4.

The present invention is in principle applicable to all rolls 3 of the rolling stands 2. Of particular importance is the application to the work rolls of the rolling stands 2. The present invention will be further described below in connection with the upper work roll 3 of the in FIG. 1 third rolling stand 2 explained. However, this definition is purely arbitrary. The present invention is analogously applicable to any other roll 3 of each roll stand 2.

According to FIG. 2 In a step S1, the control computer 4 initially initializes a volume temperature distribution VT of the roller 3 under consideration. In step S1, each node of the volume temperature distribution - see, for example, in FIG FIG. 3 plotted points - the considered roller 3 initialized with an initial temperature. For example, the initial temperature may be the same for all nodes and corresponding to the ambient temperature, ie between 0 ° C and 40 ° C, for example.

The nodes of the volume temperature distribution VT can, as in FIG. 3 shown, may be arranged such that the volume temperature distribution VT Although in the axial direction (ie in the direction the rotational axis of the roller 3) and in the radial direction (ie, a direction which is orthogonal to the axis of rotation of the roller 3) is spatially resolved in the tangential direction (ie, at a radial distance about the axis of rotation of the roller 3 around) but not spatially resolved. Alternatively, the volume temperature distribution VT may be spatially resolved in all three directions (axial, radial, tangential). FIG. 4 shows purely by way of example a disc of such a three-dimensionally spatially resolved volume temperature distribution VT of the roller 3.

FIG. 4 additionally shows a support roller 8 and its modeling and the flat rolling stock 1 and its modeling. The modeling of the back-up roll 8 and the flat rolled stock 1 are of minor importance in the context of the present invention. Of importance, however, are the heat fluxes j, which are essentially determined by the contact of the considered roll 3 with the flat rolled stock 1, the cooling by cooling devices 9 and, if present, the contact with the support roll 8. To a small extent, there is still a heat flow through radiation. However, this heat flow can usually be neglected.

The heat fluxes j in their entirety define a heat flux distribution WT, which is spatially resolved in the axial direction and the tangential direction. Even in the case of a volume temperature distribution VT not spatially resolved in the tangential direction, the heat flux distribution WT is also spatially resolved in the tangential direction. This is in FIG. 3 For example, indicated by one of the axial zones of the volume temperature distribution VT is divided on its surface in tangential direction into individual fields 10. For each individual field 10, a separate heat flow j can be specified.

The spatial resolution of the volume temperature distribution VT need not be uniform everywhere. For example, with respect to the radial resolution, it is possible to provide a finer resolution in the vicinity of the surface of the roller 3 than in the vicinity of the rotation axis of the roller 3. If the volume temperature distribution VT is also spatially resolved in the tangential direction, the spatial resolution in the tangential direction can be increasingly coarser in a similar way, the closer one approaches the axis of rotation of the roller 3. An example: In the three outermost layers (= rings) of the volume temperature distribution VT there is a spatial resolution of 64 elements in the tangential direction. In the next three layers there is a spatial resolution in the tangential direction of 32 elements each. In the next three layers, there is a tangential spatial resolution of 16 elements, etc. The said spatial resolutions and also the number of layers for which this spatial resolution applies in each case can of course be varied as required.

If the volume temperature distribution VT - in addition to the axial and radial direction - is also spatially resolved in the tangential direction, the surface temperature distribution, ie. H. the temperature in the radially outermost layer of the roll 3, as a two-dimensional spatially resolved function, d. H. the respective local surface temperature is a function of both the axial position z and the tangential position φ. If the volume temperature distribution VT is not spatially resolved in the tangential direction, the surface temperature distribution is a function only spatially resolved in the axial direction. The surface temperature distribution T 'in this case corresponds to the average surface temperature distribution T' of the roller 3 as a function of its axial position z.

The roller 3 is not in thermal equilibrium during rolling operation. The volume temperature distribution VT must therefore be continuously updated. For updating the volume temperature distribution VT, on the one hand, the volume temperature distribution VT itself is needed, on the other hand, the heat flow distribution WT, which occurs at the surface of the roller 3. Thus, the individual heat flows j (z, φ) are required, which are fed to the roller 3 at a specific axial position z and tangential position φ or over the surface the roller 3 at this point flow out of her. In the context of the present invention, it is not sufficient in this case if the heat flows j are averaged in the tangential direction. Rather, it is required that the heat flux distribution WT be spatially resolved both in the axial direction and in the tangential direction.

It is possible to define the heat flow distribution WT as such and to specify the control computer 4. Preferably, however, the in FIG. 2 illustrated steps S2 to S4 available.

In step S2, the control computer 4 receives process variables I. The process variables I are related to the rolling of the rolling stock 1 by the roller 3. On the one hand, the process variables I are parameters such as, for example, a width of the rolling stock 1, the "chemistry" of the rolling stock 1 (ie its material composition) and the diameter of the roll 3. On the other hand, variables such as the temperature T of the rolling stock 1, the rolling speed v, the rolling force F, the rolling speed n, etc.

In a step S3, the control computer 4 determines the surface temperature distribution on the basis of the volume temperature distribution VT. The surface temperature distribution is - depending on whether the volume temperature distribution VT is spatially resolved in the tangential direction or not - spatially resolved only in the axial direction or both in the axial direction and in the tangential direction. In the case of a cylindrical roll 3 for rolling flat rolled stock 1, the step S3 consists, for example, essentially of a selection of the radially outermost layer of the volume temperature distribution VT. The temperature determined for the radially outermost layer corresponds, in the case where the volume temperature distribution VT is not spatially resolved in the tangential direction, to the average spatially resolved average temperature in the axial direction. An example of such a temperature profile is in FIG. 5 shown. In a step S4, the control computer 4 determines the heat flow distribution WT on the basis of the process variables I and the surface temperature distribution of the step S3. The heat flow distribution WT is, as already mentioned, spatially resolved both in the axial direction and in the tangential direction.

In a step S5, the control computer 4 updates the volume temperature distribution VT on the basis of the heat flow distribution WT and the volume temperature distribution VT by means of a temperature model of the roller 3. If the volume temperature distribution VT (also) is spatially resolved in the tangential direction, a release of a three-dimensional heat equation takes place in step S5. If the volume temperature distribution VT is not spatially resolved in the tangential direction, the sum of the heat flows j (z, φ) at the respective axial position z is first determined in the tangential direction for each axial zone. Then, a two-dimensional heat equation is solved. Both approaches are known and familiar to those skilled in the art.

The updating of the volume temperature distribution VT of the roll 3 takes place in the prior art in order to be able to determine the thermal crowning of a roll 3 for rolling flat rolled stock 1. This is also possible within the scope of the present invention and is optionally carried out in a step S6. However, the determination of the thermal crowning is not a core subject of the present invention.

In a step S7, the control computer 4 determines at least one upper surface temperature T ". The control computer 4 preferably determines the upper surface temperature T" such that it is spatially resolved in the axial direction. In this case - see FIG. 5 a respective upper temperature is determined for the respective axial position z, which occurs at the points of the roller 3 determined by the respective axial position z, while the respective points are in contact with the rolling stock 3. The upper surface temperature T "is therefore - possibly for the respective axial position z - the maximum temperature the roller 3 at. Alternatively, a corresponding temperature can be specified which is slightly lower.

In the following, only the case where the upper surface temperature T "is a spatially resolved distribution in the axial direction is dealt with, giving better results, but it is basically sufficient to use a single upper surface temperature, for example, in the middle of the roll.

It is possible for the control computer 4 to determine the upper surface temperature distribution T "exclusively on the basis of the updated volume temperature distribution VT. This will be described later in connection with FIG FIG. 6 be explained in more detail. Alternatively, it is possible for the control computer 4 to determine the upper surface temperature distribution T "from the updated volume temperature distribution VT and the heat flow distribution WT FIG. 7 be explained in more detail.

In a step S8, the control computer 5 determines a wear d of the roller 3 by means of a wear model 11. The control computer 4 determines the wear d in the course of step S8 taking into account the upper surface temperature distribution T "determined in step S7.

In a step S9, the control computer 4 takes further measures. For example, in the course of step S9, the control computer 4 can output the determined wear d to an operator 12 of the rolling mill. It is also possible that the control computer 4, as in FIG. 2 represented the determined wear d in the context of the determination of manipulated variables S taken into account, which influence the rolling of the rolling stock 1. The determined manipulated variables S can act on the rolling stand 2 in which the roller 3 is installed. Alternatively or additionally, the determined manipulated variables S can act on other facilities of the rolling mill, for example other rolling stands 2. Other measures are also possible. This will be explained in more detail below.

In a step S10, the control computer 4 checks whether it should terminate the investigation procedure. Depending on the result of the check of step S10, the control computer 4 returns to step S2 or not.

If the volume temperature distribution VT is also spatially resolved in the tangential direction, the determination of the upper surface temperature distribution T "can be determined exclusively on the basis of the volume temperature distribution VT FIG. 6 explained in more detail.

According to FIG. 6 the control computer 4 selects an axial position z in a step S11. In a step S12, the control computer 4 selects for the selected axial position z the radially outermost elements of the volume temperature distribution VT. In a step S13, the control computer 4 determines, for example, the highest temperature which occurs in the elements of the volume temperature distribution VT selected in step S12. Alternatively, the control computer 4 can determine, for example, the average value of those local temperatures which occur between the beginning of the contact of the roller 3 with the rolling stock 1 and the end of the contact of the roller 3 with the rolling stock 1. Other approaches are possible. It is crucial that the determined temperature is at least close to the maximum temperature. In a step S14, the control computer 4 assigns the temperature determined in step S13 to the upper surface temperature profile T "as the corresponding temperature value for the selected axial position z. In a step S15, the control computer 4 checks whether it has already carried out the corresponding temperature determination for all axial positions z If this is not the case, the control computer 4 returns to step S11, in which it selects another, previously untreated, axial position Z. Otherwise, the procedure of FIG FIG. 6 completed.

If the volume temperature distribution VT is not spatially resolved in the tangential direction, both the volume temperature distribution VT and the heat flow distribution WT must be used to determine the upper surface temperature distribution T " FIG. 7 explained in more detail.

According to FIG. 7 are the steps S12 and S13 of FIG. 6 replaced by steps S21 to S24. Steps S11, S14 and S15 of FIG FIG. 6 are retained.

In step S21, the control computer 4 determines a contact angle α for the selected axial position z. The contact angle α corresponds - see for explanation FIG. 4 - The angle through which the roller 3 is in contact with the rolling stock 1 at the selected axial position z. The determination of the contact angle α takes place as a function of process variables such as, for example, the diameter of the roll 3, the reduction of the stock, the rolling stock dimensions, etc.

eine korrespondierende Kontaktzeit t. ω ist die Winkelgeschwindigkeit der Walze 3. Die Kontaktzeit t entspricht somit der Zeit, während derer ein an dieser Axialposition z befindlicher Punkt der Walze 3 während einer Umdrehung der Walze 3 mit dem Walzgut 1 in Kontakt ist.In step S22, the control computer 4 determines - preferably based on the relationship $$t=\alpha /\omega$$

a corresponding contact time t. ω is the angular velocity of the roller 3. The contact time t thus corresponds to the time during which a point of the roller 3 located at this axial position z is in contact with the rolling stock 1 during one revolution of the roller 3.

In step S23, the control computer 4 determines at least one heat flow j, which occurs during the contact of the roller 3 with the rolling stock 1. For example, the control computer 4 can determine the maximum, the minimum, the average or another value of the heat flows j occurring during this time.

ermitteln. k ist in obiger Beziehung ein Anpassungsfaktor. Er kann beispielsweise den Wert $$k=\frac{1}{\sqrt{\pi \rho \lambda c_p}}$$

aufweisen. p, λ und c_p sind die Dichte, die Wärmeleitfähigkeit und die Wärmekapazität des Materials der Walze 3. Der Term max_ϕ (j(z,ϕ)) entspricht dem im Schritt S23 ermittelten Wärmefluss für den Fall, dass der maximal auftretende Wärmefluss j herangezogen wird.In step S24, the control computer 4 determines for the selected axial position z the upper surface temperature occurring at this axial position z, ie the corresponding value of the upper surface temperature distribution T " For example, the control computer 4 may determine the upper surface temperature for the selected axial position z in accordance with the contact time t determined in step S22 and the heat flux j determined in step S23 FIG. 8 based on the relationship $$\mathit{T"}\left(z\right)=\mathit{T\; \text{'}}\left(z\right)+k\cdot {\mathrm{Max}}_{\phi }\left(j\left(z,\phi \right)\right)\cdot \sqrt{t\left(z\right)}$$

determine. k is an adjustment factor in the above relationship. He can, for example, the value $$k=\frac{1}{\sqrt{\pi \rho \lambda c_p}}$$

exhibit. p, λ and c _{p is} the density, thermal conductivity and heat capacity of the material of the roller 3. The term max _φ (j (z, φ)) is the determined in step S23 heat flow for the case that the maximum occurring heat flow j is used.

To implement step S8 of FIG. 2 , ie the determination of the wear d, there are also different possibilities. These are discussed below in connection with the FIGS. 9 to 11 explained in more detail.

ermittelt werden. Hierbei ist ε_P die plastische Dehnung der Oberfläche der Walze 3, die während einer einzelnen Umdrehung der Walze 3 auftritt. Der thermische Verschleiß dT ist im Wesentlichen proportional zur plastischen Dehnung ε_P, proportional zur gewalzten Länge 1 und indirekt proportional zum Radius R der Walze 3. Der Radius R kann alternativ der abgeplattete oder der unbelastete Radius der Walze 3 sein.The wear d usually includes a thermal wear component dT. The thermal wear component dT can - for example - according to FIG. 9 based on the relationship $$dT\left(z\right)=\mathit{dT}\left({\epsilon }_P\left(\mathit{T"}\left(z\right).\mathit{T}Z\left(z\right)\right).R.l\right)$$

be determined. Here, ε _{P is} the plastic strain of the surface of the roller 3 which occurs during a single revolution of the roller 3. The thermal wear dT is substantially proportional to the plastic strain ε _P , proportional to the rolled length 1 and indirectly proportional to the radius R of the roll 3. The radius R may alternatively be the flattened or the unloaded radius of the roll 3.

The determination of the plastic strain ε _P is made on the basis of the corresponding upper surface temperature T "(z) and a further temperature TZ, preferably spatially resolved in the axial direction, ie for the respective axial position z.Also here - analogous to the upper surface temperature T" - below the case is treated that the further temperature TZ is spatially resolved in the axial direction.

The (at least one) further temperature TZ may be a temperature related to the surface of the roll 3. It may, for example, be the average temperature T '(z) at the relevant axial position z. Preferably, it is a minimum occurring at the respective axial position z at the surface of the roller 3 temperature. Alternatively, the further temperature TZ may be a temperature which occurs at the relevant axial position z in the interior of the roller 3. In this case, alternatively, a temperature from a relatively near-edge layer or a temperature from the core of the roller 3 can be used.

A temperature at the surface of the roller 3 is preferably used when the volume temperature distribution VT is also spatially resolved in the tangential direction. However, the procedure is also possible if the volume temperature distribution VT is not spatially resolved in the tangential direction. A use of a temperature occurring inside the roller 3 is also possible in both cases.

The determination of the plastic strain ε _P based on the two temperatures is well known to those skilled in the art and, for example in the technical paper by PG Stevens et al. explained in more detail.

ermittelt. Gegebenenfalls kann in dieser Beziehung indirekt eine thermische Abhängigkeit berücksichtigt werden. In diesem Fall ist der Verschleißkoeffizient c nicht eine Konstante, sondern proportional zur Wurzel aus der Kontaktzeit t.The wear also often includes an abrasive wear share dA. The abrasive wear portion dA is often in the prior art according to the above-mentioned relationship $$d=c\cdot \phi \cdot \alpha \cdot l$$

determined. Optionally, a thermal dependency may indirectly be taken into account in this respect. In this case, the wear coefficient c is not a constant, but proportional to the root of the contact time t.

Although the latter approach leads to an improvement over a determination of the abrasive wear portion dA over the prior art. The procedure is not yet optimal. To significantly better results leads a procedure, as in connection with FIG. 10 is explained in more detail.

According to FIG. 10 determines the control computer 4 in a step S31, the thermal wear component dT. The determination of the thermal wear component dT can be carried out, for example, as already explained above.

In a step S32, the control computer 4 determines a surface hardness H of the roller 3, if necessary spatially resolved in the axial direction. The surface hardness H is determined on the one hand as a function of the material properties of the surface of the roller 3 and on the other hand as a function of the upper surface temperature distribution T. ".

In a step S33, the control computer 4 determines the abrasive wear component dA using the surface hardness H of the roller 3 determined in step S32. In a step S34, the control computer 4 determines the wear d by summing the thermal wear component dT and the abrasive wear component dA.

To determine the abrasive wear portion dA (= step S33), the control computer 4, for example, according to FIG. 11 Use a functional relationship in which the surface hardness H, the rolled length l and the contact angle α enter.

bei der Ermittlung des abrasiven Verschleißanteils dA berücksichtigen. Der abrasive Verschleißanteil dA ist in diesem Fall proportional zur Fließspannung σ, der gewalzten Länge l und dem Kontaktwinkel α und indirekt proportional zur ermittelten Oberflächenhärte H. Auch können die Temperatur T und/oder die "Chemie" des Walzgutes 1 im Rahmen von Zundermodellen berücksichtigt werden, deren Ergebnis Einfluss auf die Modellierung des abrasiven Verschließanteils dA hat.Preferably, as in FIG. 11 shown in the determination of the abrasive wear portion dA additionally the temperature T and / or the material composition of the rolling stock 1 a. For example, the control computer 4, as in FIG. 11 represented, on the basis of the temperature T and the material composition of the rolling stock 1 determine a maximum yield stress σ and the yield stress σ according to the relationship $$dA=\left(\sigma \left(T\right).H\left(\mathit{T"}\left(z\right)\right).l.\alpha \right)$$

take into account when determining the abrasive wear component dA. The abrasive wear component dA in this case is proportional to the yield stress σ, the rolled length l and the contact angle α and indirectly proportional to the determined surface hardness H. Also, the temperature T and / or the "chemistry" of the rolling stock 1 can be taken into account in the context of scale models whose result has an influence on the modeling of the abrasive closing portion dA.

As already mentioned, the determination of the heat flow distribution WT preferably takes place on the basis of process variables I, which relate to the rolling of the rolling stock 1 through the roll 3, in cooperation with the initial surface temperature distribution T '. It is possible that the process variables I are model-supported expected expected quantities, which are supplied to the computer 4 from the outside, see FIG. 1 , Alternatively, it is possible for the process variables I to be actual variables which are detected by the roller 3 during the rolling of the rolling stock 1, see also FIG FIG. 1 , Also mixed forms are possible. By way of example, it is possible to predefine expected process variables I determined model-based to the control computer 4 up to a time in the future. In this case, calculated actual variables can be calculated for the past and, starting from the thus determined wear d, a forecast for the future expected wear d can be drawn up on the basis of the expected process variables I directed in the future. This is described in detail in the application filed at the same time as this application "Operating Procedure for a Rolling Mill for Rolling Flat Rolling Material with Rolling Wear Prediction" (internal file number of the Applicant: 201013425). The procedure is roughly described below in connection with FIG. 12 explained.

According to FIG. 12 the control computer 4 initializes the volume temperature distribution VT in a step S41. The step S41 corresponds to the step S1 of FIG FIG. 2 ,

In a step S42, the control computer receives 4 stitch plan data SP (or determines this itself). The stitch plan data SP define - among other things - the mentioned model-based ascertained, future expected process variables I. The step S42 corresponds to a partial embodiment of the step S2 of FIG FIG. 2 ,

In a step S43, the control computer 4 receives actual variables of the rolling process which describe the rolling of the rolling stock 1 by the roller 3 under consideration. The step S43 corresponds to another partial embodiment of the step S2 of FIG FIG. 2 ,

In a step S44, the control computer 4 uses the actual variables of step S43 to determine an actual crowning and the instantaneous wear d. The step S44 substantially corresponds to a summary of the steps S3 to S8 of FIG FIG. 2 , related to the utilization of the actual quantities of step S43.

In a step S45, the control computer 4 determines the manipulated variables S, which influence the rolling of the rolling stock 1. The manipulated variables S can, as already mentioned, act on the roller 3 under consideration and / or on other rollers 3 of other rolling stands 2.

It is possible that the control computer 4, the procedure of FIG. 12 in real time during the rolling of the rolling stock 1 performs. In this case, there is a step S46, in which the control computer 4 controls the rolling mill in accordance with the determined manipulated variables S. Alternatively, the control computer 4, the procedure of FIG. 12 Of course, even after rolling of the rolling 1 perform. In this case, step S46 may be omitted.

In a step S47, the control computer 4 determines a prognosis for the thermal crowning and the wear d. The step S47 corresponds essentially to an implementation of the step S44, but in contrast to the step S44, not the detected actual variables of the rolling process are evaluated, but the stitch plan data SP. In a step S48, further measures can be taken depending on the expected future wear d determined in step S47. For example, a roll change can be initiated. The determined wear prognosis can also be output, for example, to the operator 12 of the rolling mill.

In a step S49, the control computer 4 checks whether the procedure of FIG. 12 should be terminated. Depending on the result of the test of step S49, the control computer 4 proceeds to a step S50 or terminates the procedure of FIG. 12 ,

In step S50, the control computer 4 checks whether it has specified further stitch plan data SP or has been determined by it. Depending on the result of the check of step S50, the control computer 4 returns to step S42 or step S43.

In the foregoing, a procedure explained in real time during rolling of the rolling stock 1 by the roller 3 has been explained. However, this is not mandatory. As already mentioned, the procedure can also be carried out after the rolling of the rolling stock 1. In this case, according to FIG. 13 Steps S42 and S45 to S48 and step S50 are omitted. Instead, there is a step S51, in which the respective determined wear d - possibly broken down by thermal wear dT and abrasive wear dA - is output to the operator 12 of the rolling mill.

Likewise it is possible the procedure of FIG. 12 adapted to be performed by the roller 3 before rolling the rolling stock 1. In this case, steps S43 to S46 may be omitted. Steps S56 and S57 are further preferably followed by step S47 in this case. In step S56, the control computer 4 determines the required manipulated variables S on the basis of the wear d determined in step S47. In step S57, the control computer 4 stores the manipulated variables S so that they are available for later activation of the rolling mill. Step S48 may still be present. Alternatively, it can be omitted. It may alternatively be upstream or downstream of steps S56 and S57.

The present invention has many advantages. In particular, the roller life, ie the time between installation and removal of the rollers 3, can be optimized. Also, often the quality of rolled rolled stock 1 can be optimized.

The above description is only for explanation of the present invention. The scope of the present invention, however, is intended to be determined solely by the appended claims.

Claims (16)

1. Method for determining wear (d) of a roll (3) for rolling metal stock (1),

   - wherein a volume temperature distribution (VT) of the roll (3) is updated on the basis of a heat flow distribution (WZ) occurring on the surface of the roll (3) using a temperature model of the roll (3),

   - wherein the volume temperature distribution (VT) is spatially resolved at least in the axial direction and in the radial direction of the roll (3),

   - wherein the heat flow distribution (WT) is spatially resolved in the axial direction and in the tangential direction of the roll (3),

   - wherein the wear (d) of the roll (3) is determined using a wear model (11),

   - wherein as part of the wear model (11)

   -- on the basis of the updated volume temperature distribution (VT) and/or the heat flow distribution (WT), at least one upper surface temperature (T") occurring at particular points of the surface of the roll (3) while the respective point is in contact with the metal stock (1) is determined, and

   -- the wear (d) of the roll (3) is determined taking into account the upper surface temperature (T") of the roll (3).
2. Determining method according to claim 1,
   characterised in that

   - the volume temperature distribution (VT) is not spatially resolved in the tangential direction of the roll (3),

   - the updated volume temperature distribution (VT) defines an average surface temperature distribution (T') spatially resolved in the axial direction that is characteristic of an average surface temperature of the roll (3),

   - on the basis of process variables (I) relating to the rolling of the metal stock (1) by the roll (3), respective contact times (t) are determined, spatially resolved in the axial direction, which are characteristic of how long the roll (3) is in contact with the metal stock (1) during one revolution of the roll (3), and

   - that the upper surface temperature (T") is determined on the basis of the average surface temperature (T') of the roll (3), the part of the heat flow distribution (WT) occurring while the roll (3) is in contact with the metal stock (1), and the contact times (t).
3. Determining method according to claim 1,
   characterised in that
   the volume temperature distribution (VT) is also spatially resolved in the tangential direction of the roll (3) and that the upper surface temperature (T") is determined solely on the basis of the updated volume temperature distribution (VT).
4. Determining method according to claim 1, 2 or 3,
   characterised in that
   the wear (d) includes a thermal wear component (dT) and the thermal wear component (dT) is determined using the upper surface temperature (T") and at least one other surface temperature (T') of the roll (3) relating to the surface of the roll (3).
5. Determining method according to claim 1, 2 or 3,
   characterised in that
   the wear (d) includes a thermal wear component (dT) and that the thermal wear component (dT) is determined using the upper surface temperature (T") of the roll (3) and an internal temperature obtaining inside the roll (3).
6. Determining method according to one of the above claims,
   characterised in that
   the wear (d) includes an abrasive wear component (dA), the abrasive wear component (dA) is determined using a surface hardness (H) of the roll (3) and that the surface hardness (H) of the roll (3) is determined using the upper surface temperature (T") of the roll (3).
7. Determining method according to claim 6,
   characterised in that
   the abrasive wear component (dA) is determined using additionally a temperature (T) and/or the material composition of the metal stock (1).
8. Determining method according to one of the above claims,
   characterised in that
   the heat flow distribution (WT) is determined on the basis of process variables (I) relating to the rolling of the metal stock (1) by the roll (3) and an initial surface temperature distribution (T') of the roll (3) defined by the not yet updated volume temperature distribution (VT).
9. Determining method according to claim 8,
   characterised in that
   at least some of the process variables (I) are expected variables determined in a model-based manner.
10. Determining method according to claim 8 or 9,
    characterised in that
    at least some of the process variables (I) are actual values measured during rolling of the metal stock (1) by the roll (3).
11. Determining method according to claim 8, 9 or 10,
    characterised in that
    it is carried out in real time during rolling of the metal stock (1) by the roll (3).
12. Determining method according to claim 8 or 9,
    characterised in that
    it is carried out prior to rolling of the metal stock (1) by the roll (3).
13. Determining method according to one of the above claims,
    characterised in that
    the wear (d) determined is taken into account for determining manipulated variables (S) affecting the rolling of the metal stock (1).
14. Computer program comprising machine code (7) which can be directly executed by a computer (4) and whose execution by the computer (4) causes the computer (4) to carry out a determining method having all the steps of a determining method according to one of the above claims.
15. Computer,
    characterised in that
    the computer is designed such that it carries out a determining method having all the steps of a determining method according to one of claims 1 to 13.
16. Rolling mill for rolling metal stock (1),
    characterised in that
    the rolling mill is equipped with a computer (4) according to claim 15.

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