EP2010348A1

EP2010348A1 - Process and device for determining the distance between the rollers of support rollers and the strand guider structure of a continuous strand casting facility

Info

Publication number: EP2010348A1
Application number: EP07723964A
Authority: EP
Inventors: Hans Streubel; Axel Weyer; Christoph Tischner
Original assignee: SMS Demag AG
Current assignee: SMS Siemag AG
Priority date: 2006-04-22
Filing date: 2007-04-04
Publication date: 2009-01-07
Also published as: WO2007121838A1; DE102006018757A1; CN101426603A; CN101426603B

Abstract

A process for determining the distance between rollers (4) of support rollers (5) and the corresponding strand guider framework (3) of a continuous strand casting facility (1) for the casting of liquid metals, especially liquid steel materials, is based on the effects of bulging (9) at bath level and suggests that those varying roller distances (4c) that have a total length profile (F) resulting from the individual frequency of each supporting roller (5) be combined, from which an optimal value for a maximum damping of all bulging effects (9) such as, for example, bath level fluctuations (10) is determined, upon which optimal roller distance (4c) is calibrated.

Description

METHOD AND DEVICE FOR DETERMINING THE ROLLING DEPARTMENTS OF SUPPORTING ROLLERS AND STRUCTURING EQUIPMENT OF A CONTINUOUS CASTING INSTALLATION

The invention relates to a method for determining the roll spacings of support rollers in a strand guide framework of a continuous casting plant for the casting of liquid metals, in particular of liquid steel materials, in which the formed in a stationary, oscillating continuous casting mold, in the interior still liquid cast strand is pulled out and the extraction force in pairs, individually driven or idler support rollers is transmitted, wherein the respective jaw width is continuously adjusted to the thickness of the further solidifying Gießstrangs, the distances of the roller pairs or roller segments in the casting direction are set to a transient, moving with variable casting speed bulge and Badspiegelschwankungen be reduced in the continuous casting mold by influencing the resulting individual frequency.

A method for determining the roller distances in a strand guiding framework of a continuous casting plant is known from DE 199 51 262 C1. The oppositely arranged rollers of the respective rows of at least one support roller segment have such spacings that, for a transient, moving with casting speed bulge of the casting strand, they have a phase shift delta with respect to a sinusoidal wave length with the roll distance. This changes the base roll distance of Δl. As a result, a rocking of the casting mirror in the stationary continuous casting mold is to be avoided. According to the rolling plan, a defined frequency is established in a continuous casting plant. This frequency is caused by a non-uniformity of the strand shell when passing through the roller distances. The roll spacings can take on positive as well as negative values during roll shifting. Therefore, the proposal seeks to eliminate pouring mirror variations that occur through the described string-shaped bulges in many places between the rollers and hereby lead to excessive Gießspiegelschwankungen by which a certain and thus a targeted number of phase shifts to fix. This is a special way of designing the role plan to compensate for irregularities.

The invention is based on the object, starting from the present on a continuous casting geometric shapes, the Gießstrangbreite, the strand thickness and the possible casting speeds and possibly other Gießparametem from the actual bulges occur at Sisrollenabständen and thereby primarily the effects on the Bad- Mirror as the starting point of the considerations to choose.

The object is achieved according to the invention in that such different roller distances are combined, the result of the base roller spacing and the casting speed of several or all Einzelfrequen- zen the respective support roller a total distance profile (F) of the strand guide framework, from which an optimum for maximum damping of all Bumping effects is determined, due to which optimal roll distances are divided. The advantages are a stronger attenuation of the Badspiegelschwankungen and the bulges at different casting conditions. This optimum of low initial amplitude, a continuous decay, a fast damping and a high overall time constant causes a small change in volume Kokillenbadspiegel. The susceptibility to failure or the swinging behavior of the mold bath mirror during process-related parameter changes, such as, for example, changes in the casting speed, the steel quality, thickness or width changes, cooling changes, and the like. Like. cause less bulge effects.

One embodiment provides that the optimum of the maximum attenuation of bath level fluctuations is determined from a graph of all vertices of the oscillations by an envelope that largely affects the vertices. The measurement of the vibrations of the bath level can, for example. In the Continuous casting mold depending on the passage of the casting strand between a pair of rollers performed by optical means or calculated by a computer program depending on Gießparametern.

According to the further embodiment, a logarithmic curve is determined for the envelope.

It is provided that the total distance profile (F) from the individual frequencies according to the function

is calculated, in which mean

V = sum of the volume units on the considered casting length

/ = Roll index, starting with 1 for the 1st roll below the continuous casting mold, up to the last roll position of the strand guide n = number of all rolls in the support roll stand C, = valence of the roll "/" (effect parameter at the nth roll position) dj = Distance of the roll "/" to the lower edge of the continuous casting mold in mm

Vgi _eß = casting speed in [mm / sec] t = time in [sec]

Another embodiment provides that the logarithmic envelope determined by the vertex "1" and the respective vertex "n" is determined according to the following factors:

B) and where: a "= attenuation factor for a curve through the vertex

"b ⁿ _n ^" = turn ^[ for the curve through the vertex n []

U = time of the first vertex [sec] t _n = time of the nth vertex [sec] di = depression value of the first vertex value [mm] d _n = depression value of the nth vertex value [mm]

Furthermore, it is proposed that the enveloping logarithm curve is selected as a geometrically exact curve, which includes all vertices, according to the function, / ':

D) Aθ = a • hl t + b

where a = attenuation factor [] b = inflection point [] t = time [sec]

Further measures are that by optimally combining different support roller distances an optimization compared to the same size support roller distances is set to a large extent approximation that

E) ß opt ≤ 0, 9 • ßvorher

where β _opt = bulge index after optimization [m / sec] β before = bulge index before optimization [m / sec] The device for supporting and transporting a cast strand in a strand guide framework of a continuous casting during the casting of liquid metals, in particular of liquid steel materials, in the strand withdrawal direction to a stationary, oscillatable continuous casting mold subsequent Stützrollenseg- elements or support roller groups whose paired support rollers with their respective mouth width on the Thickness of the solidifying Gießstrangs are adjustable and the support roller distances from pair of rollers to pair of rollers are tuned to a non-stationary moving with casting speed bulge in the sense that Badspiegelschwankungen in the continuous casting mold and the strand guide frame are reduced by changing the base roll spacing.

Such a strand guide framework is formed in the design of the device of the invention from support roller segments or groups whose pairs of rollers are provided with optimally adjusted intervals in the casting direction, ie with mutually unequal distances, such that several or all individual frequencies of the respective support role to a summarized Total track profile of the strand guide framework, an optimum for a maximum attenuation of all bulge effects arise, due to which the roll distances are set optimally. The advantages are greater attenuation of bath level fluctuations and bulges under different casting conditions. The volume changes in the bath level range of the continuous casting mold and thus the Badspiegelschwankungen are lower. The design of the roll carpet is based on the segment design of a continuous casting plant. The replacement of the support roller segments can be considered here. The optimization of the support roll distances in the casting direction also takes into account the geometric parameters of the strand guide elements, such as roll diameter, roll distances, grid lengths, solidification values (strand shell thickness, solidification length) and a variable casting speed. An embodiment of the device consists in the fact that the base roller spacing is reduced in the course of individual sections of the strand guide frame to an optimally set roller spacing between 5 - 40 mm.

Analogous to the above measure is still provided that the base roll spacing is increased in the course of individual sections of the strand guide framework to an optimally set roll spacing between 10-50 mm.

In the drawing, embodiments of the invention are shown, which are described in more detail below.

Show it:

1 is a side view of a sheet continuous casting with continuous casting mold and strand guide frame,

Fig. 1A shows a detail of Figure 1 on an enlarged scale, Fig. 2 is a graph of the vibrations on the bath mirror of

Continuous casting mold occur, and

Fig. 3 is a further graph of the vibrations which act on the bath level after the roll pitch has been changed according to the invention.

In a continuous casting plant 1 with a continuous casting mold 2, a strand guiding framework 3 for supporting, transporting and further cooling a casting strand 6 is provided, wherein the supporting roll spacings 4 in the casting direction 8 are influenced by the frequency of the driving and supporting forces on the supporting rolls 5. In general, below the continuous casting mold 2, each roller pair 4 a has a base roller spacing 4 b to the lower edge of the continuous casting mold 2. The cast strand 6 formed in the stationary, oscillated continuous casting mold 2 is still liquid in the interior and the pull-out force is transmitted to the strand shell by pairs, individually driven or idle support rollers 5, wherein the respective mouth width 5a to the thickness 6a of the further solidifying cast strand. 6 is adjusted continuously. The pairs of rollers 4a and the support roll 5 or whole roller segments 7 or support roller groups 7a effect in the casting 8 transient, moving with variable casting speed bulges 9, whereby the harmful Badspiegelschwankungen 10 are caused.

On the basis of the invention, a method is described for determining the roller spacings 4 of the support rollers 5, the roller pairs 4a or the support roller segments 7 or the support roller group 7a through an optimally adjusted roller spacing 4c. In this case, different roller spacings 4c are combined, wherein from a roller spacing 4 and the casting speed several or all individual frequencies of the respective support roller 5 are combined to form a total section profile F of the strand guide frame 3, from which an optimum for maximum damping of all bulge effects 9 is determined the support roller spacings 4 are set in optimum roller spacings 4c. It should be noted that the thickness and the width of the casting strand 6 are not shown with their change in different casting strands 6 in the plane, but must be taken into account in each individual case with:

in which mean V = sum of the volume units on the considered cast strand length

/ = Roll index, starting with 1 for the 1st roll below the continuous casting mold, up to the last roll position of the strand guide n = number of all rolls in the backing roll stand

Ci = valence of the roll "/" (effect parameter at the nth roll position) d / = distance of the roll "/" to the bottom edge of the continuous casting mold in mm

Casting _β = casting speed in [mm / sec] t = time in [sec]

The optimized roller spacings 4c according to FIG. 1A (d1, d2, d3, d4) can be enlarged or reduced in an irregular sequence and conversely also reduced or enlarged, whereby due to the succession of constantly changing support roller distances, the bath level fluctuation can be minimized or completely avoided. The invention is for example. For slabs in the thickness range 150 - 300 mm at casting speed up to 4 m / min, for medium casting strands in the thickness range 100 mm to 180 mm with casting speed of up to 6 m / min and for thin casting strands in the thickness range of 40 mm 100 mm with casting speeds of 2 to 12 m / min particularly favorable use.

The optimum of the maximum attenuation of the Badspiegelschwankungen 10 can be taken from a graph 11 of all vertices 12, which are visible through small crosses 12a in Fig. 2. At this time, the envelope 13a determined by the mathematical relationship described in Equation A) is formed from the plurality of vertices 12. The vertices 12 are shown in their absolute magnitude so that the associated negative vertices find themselves in the positive part of the xy coordinate system. From Fig. 2 thus the envelope 13a can be seen before the optimization of the support roller spacings 4 in the casting 8. In FIG. 3, the graph 11 from FIG. 2 shows in a modified form: In addition to the envelope 13a before the optimization, formed by the crosses 12a and inflection points 14, the envelope 13b is produced after the optimization. For the envelope 13b, a logarithmic curve 13c can be calculated.

In this case, the envelope 13c determined by the vertex "1" and the respective vertex "n" is calculated according to the following factors:

and

in which mean:

a _n = damping factor for a curve through the vertex

"N" [] b _n = turn for the curve through the vertex n

[] ti = time of first vertex [sec] t _n = time of nth vertex [sec] di = depression value of first vertex [mm]

Of _n = depression value of the nth peak [mm]

As a geometrically accurate curve, which includes all vertices 12, the enveloping logarithm curve 13c is determined with the function "f:

in which mean a = attenuation factor [] b = inflection point [] t time [sec]

(In = logarithm naturalis, base e = 2.7 ...)

The gray shaded area enclosed by the envelope 13b after optimization is a measure of the effect of the strand guide on the bath level in the continuous casting mold 2 and is referred to below as the bulge index β. The envelope 13b, which includes the shaded area, is represented by the optimized logarithmic envelope 13c according to formula D). If this determined curve lies below the original envelope curve 13a, a low bulging index β is achieved and the effect on the bath level is already improved. The optimization is achieved if the following condition is met:

E) ß opt ≤ 0, 9 • ß before

where: ß _Opt = bulge index after optimization [m / sec] ß before = bulge index before optimization [m / sec]

The device for supporting and transporting a casting strand 6 in a strand guiding framework 3 of the continuous casting plant 1 is based on a continuous casting mold 2, from which all reference variables in the strand withdrawal direction 8 are measured. To the continuous casting mold 2 close the roller pairs 4a with their support roller spacing 4 at. The calculated and / or determined on the basis of measured variables (Figure 2) optimally set roll spacing 4c (on one side, for example, the lot side of the strand guide) generates a single frequency (roller spacing linked to the casting speed) with one of the amplitudes shown. The respective amplitude is dependent on the roll diameter and the roll position and the respectively present solidification of the casting strand 6 at these corresponding position. The sum of the given individual amplitudes produces the total line profile "F" as shown in FIGS. 2 and 3.

The design of the roll carpet is based on the support roll segment construction of the continuous casting plant 1. An exchange of support roller segments 7 can be considered.

The functions of the formulas A) to E) are part of an optimization program in the computer program of the casting process. The optimization program includes the geometric parameters of the strand guide elements, such as roll diameter, support roller distances (4), grid lengths, as well as the solidification values, such as strand shell thickness, solidification length, and also detects variable casting speeds.

The device with the strand guide frame 3 forms an optimized roller conveyor (from roller pairs 4a, support roller segments 7 or support roller groups 7a) and has correspondingly adapted bearings and traverses.

LIST OF REFERENCE NUMBERS

1 continuous casting plant

2 continuous casting mold

3 strand guide frame

4 Support roller distance in casting direction 4a Roller pair 4b Base roller distance

4c optimally set roll distance

5 support roller 5a jaw width

6 Casting strand 6a Thickness of the cast strand

7 support roller segment 7a support roller group

8 casting direction, strand withdrawal direction

9 Bulge, bulge effect 10 Badspiegelschwankung

11 graphic

12 vertex 12a cross

13a Envelope before optimization 13b Envelope after optimization

13c logarithmic envelope

14 turning point

F Total distance profile dd ₄ Combination of unequal support roller distances

Claims

claims:

1. A method for determining the roll spacings (4) of support rollers (5) in a strand guide framework (3) of a continuous casting plant (1) for casting of liquid metals, in particular of liquid steel materials, in which the in a stationary, oscillating continuous casting mold ( 2) formed, in the interior still liquid cast strand (6) is pulled out and the pull-out by pairs, individually driven or idle support rollers (5) is transmitted, wherein the respective jaw width (5a) to the thickness (6a) of the further solidifying casting strand (6 ) is set continuously, the distances (4) of the roller pairs (4a) or the roller segments (7) in the casting direction (8) on a transient, moving with variable casting speed bulge (9) are adjusted and Badspiegelschwankungen (10) in the continuous casting mold ( 2) are reduced by influencing the single frequency, characterized in that such different roller spacings 4) and the casting speed of several or all individual frequencies of the respective support roller (5) give an overall profile (F) of the strand guide frame (3), from which an optimum for a maximum damping Effects (9) is determined, due to the optimal role intervals (4c) are divided.

2. The method according to claim 1, characterized in that the optimum of the maximum attenuation of Badspiegelschwankungen (10) from a graph (11) of all vertices (12) of the oscillations by the apexes (12) largely tangent envelope curve (13b) determined becomes.

3. The method according to claim 2, characterized in that for the envelope (13b) a logarithmic curve (13c) is determined.

4. The method according to claim 1, characterized in that the total distance profile (F) from the individual frequencies according to the function

is calculated, in which mean

V = sum of the volume units on the considered casting length

/ = Roll index, starting with 1 for the 1st roll below the continuous casting mold, up to the last roll position of the strand guide n = number of all rolls in the supporting roll stand Ci = valence of the roll "/" (effect parameter at the nth roll position) αf _/ = Distance of the roll "/" to the lower edge of the continuous casting mold in mm

Vgi _eß = casting speed in [mm / sec] t = time in [sec]

5. The method according to claims 1, 3 and 4, characterized in that the determined by the vertex "1" and the respective vertex "n" logarithmic envelope (13c) is determined according to the following factors: B)

and

where: a "= attenuation factor for a curve through the vertex" n "[] b _n = turn for the curve through the vertex n []

U = time of the first vertex [sec] t _n = time of the nth vertex [sec] d) = depression value of the first vertex value [mm] d _n = depression value of the nth vertex value [mm]

6. The method according to claim 5, characterized in that as a geometrically accurate curve, which includes all vertices (12), the enveloping logarithm curve according to the function, / 'is chosen:

D) Λθ = a • \ n t + b

where a = attenuation factor [] b = inflection point [] t = time [sec]

(In = logarithm naturalis, base e = 2.7 ...)

7. The method according to claims 1 to 3, characterized in that by a targeted combination of different support roller spacings (4c) an optimization over the same size support roller distances (4b) is set in a largely approximation, the

E) ß opt <0, 9 • ß before

where β _opt = bulge index after optimization [m / sec] β before = bulge index before optimization [m / sec]

8. Device for supporting and transporting a cast strand (6) in a strand guide frame (3) of a continuous casting plant (1) during the casting of liquid metals, in particular of liquid steel materials, with in strand withdrawal direction (8) to a stationary, oscillatable continuous casting mold (2) Support roller segments (7) or support roller groups (7a) whose paired support rollers (5) with their respective mouth width (5a) to the thickness (6a) of the solidifying Gießstrangs (6) are adjustable and the support roller spacings (4) of roller pair (4a ) are tuned to pair of rollers (4a) to a transient moving with casting speed bulge (9) in the sense that Badspiegelschwankun- gene (10) in the continuous casting mold (2) and the strand guide frame (3) by changing the base roll spacing (4b) reduced are characterized in that the strand guiding framework (3) is formed of support roller segments (7) or groups (7a) whose roll pairs (4a) with optimally adjusted spacings (4c) in the casting direction (8), ie with mutually unequal distances (4c) are provided, such that several or all Single frequencies of the respective support roller (5) to give a zusammengefassensten total section profile (F) of the strand guide frame (3) an optimum for a maximum attenuation of all bulge effects (9), due to which the roller spacings (4c) are optimally divided.

9. Device according to claim 8, characterized in that the base roller spacing (4b) in the course of individual sections of the strand guide frame (3) is reduced to an optimally set roller spacing (4c) between 5-40 mm.

10. Device according to claim 8, characterized in that the base roller distance (4b) in the course of individual sections of the strand guide frame (3) to an optimally set roller spacing (4c) between 10 - 50 mm is increased.