EP1694447A1

EP1694447A1 - Optimised shift strategy as a function of strip width

Info

Publication number: EP1694447A1
Application number: EP04797824A
Authority: EP
Inventors: Andreas Ritter; Rüdiger Holz
Original assignee: SMS Demag AG
Current assignee: SMS Siemag AG
Priority date: 2003-12-18
Filing date: 2004-11-11
Publication date: 2006-08-30
Anticipated expiration: 2024-11-11
Also published as: CA2545071A1; ATE432130T1; TW200523045A; BRPI0417704B1; DE10359402A1; CN1894054A; UA90255C2; US20070101792A1; WO2005058517A1; KR20060107744A; CA2545071C; RU2006125728A; ZA200600992B; DE502004009541D1; ES2324916T3; KR101187363B1; JP2007514546A; RU2367531C2; EP1694447B1; CN1894054B

Abstract

The invention relates to a method for the optimization of shift strategies, as a function of the strip width, for best possible usage of the advantages of CVC/CVC<SUP>Plus </SUP>technology in operation of strip-edge oriented shifts in 4-/6-roller stands, comprising a pair of working rollers and a pair of support rollers for a 4-roller stand and, in addition, a pair of intermediate rollers for a 6-roller stand, whereby at least the working rollers and the intermediate rollers cooperate with devices for axial shifting, characterized in that selection of the shift position (VP), for the shifting working/intermediate rollers, is made as a function of strip width. The working/intermediate rollers are then positioned in various positions (P), relative to the strip edge and, within differing strip width ranges (B), the shift position (VP) of each roller is given by an incremental linear progressive function.

Description

Optimized shift strategies as a function of bandwidth

The invention relates to a method for optimizing displacement strategies as a function of the bandwidth in order to make the best possible use of the advantages of the CVC / CVC ^plus technology in the operation of belt edge-oriented displacement in 4- / 6-roll stands, each comprising a pair of work rolls and backup rolls and an additional one Pair of intermediate rolls in 6-roll stands, at least the work rolls and the intermediate rolls interacting with devices for axial displacement, and each work / intermediate roll having a bale extended by the CVC displacement stroke with one-sided regrinding in the region of the bale edge.

In the past, the requirements for the quality of cold-rolled strip with regard to thickness tolerances, achievable final thicknesses, strip profile, strip flatness, surfaces etc. have risen steadily. The variety of products on the market for cold-rolled sheet metal also leads to an ever more diverse range of products in terms of material properties and geometric dimensions. As a result of this development, the desire for more flexible system designs and operating methods in cold tandem mills - optimally adapted to the end product to be rolled - is becoming ever stronger.

The achievement of a desired final thickness as well as the realization of certain acceptance distributions (stitch plan design), especially with higher strength grades, is significantly influenced by the work roll diameter. As the work roll diameter decreases, the required rolling force is reduced due to more favorable flattening behavior. The reduction in diameter is limited both by the transmission of the torques and with regard to the roll deflection. If the pin cross-sections are not sufficient to transmit the drive torque, the work rolls can over

sesTÄneuNGβKDPiE Friction are driven by the adjacent roller. In the case of a 4-roll stand, however, heavy drive elements (motor, pinion gear, spindles) are required to implement a backup roll drive, which make the system more expensive. Here it makes sense to design individual stands (usually the front ones) as 6-roll stands with an intermediate roll drive.

In addition to the vertical deflection, the horizontal deflection of the work rolls and intermediate rolls also plays an important role in the flatness of the strip. By horizontally shifting the work / intermediate rolls from the center plane of the stand, the roll set is supported, which leads to a substantial reduction in the horizontal deflection.

In addition, the 6-roll stand in the intermediate roll bend has an additional, fast actuator. In combination with the work roll bending, the 6-roll stand thus has two actuators that are independent of the effect on the roll gap. In the first stand, rapid adaptation of the roll gap to the incoming strip profile is thus ensured to avoid flatness defects. In the last stand, both actuators can be used effectively in the flatness control.

For the classic 4-High and 6-High stand designs, in addition to basic concepts with bending systems and fixed roll crowns as actuators influencing the roll gap, there are essentially two further stand designs that additionally influence the roll gap by shifting work rolls or intermediate rolls based on different working principles:

• CVC / CVC ^plus technology

• Technology of belt edge oriented shifting These are separate stand concepts because different roller geometries are required.

In classic CVC technology, as described in EP 0 049 798 B1, the bale lengths of the displaceable rollers are always longer by the axial displacement stroke than the fixed, non-displaced rollers. This ensures that the sliding roller cannot be pushed with its bale edge under the fixed roller bale. This prevents surface damage / markings. The work rolls are generally supported over their entire length on the intermediate or backup rolls. As a result, the rolling force exerted by the support rolls is transmitted to the entire length of the work rolls. This has the consequence that the ends of the work rolls projecting laterally over the rolling stock and thus not participating in the rolling process are bent in the direction of the rolling stock by the rolling force exerted on them. This harmful deflection of the work rolls results in the middle roll sections being bent. It causes the central strip area to be rolled out too little and the strip edges to be rolled out heavily. These effects are particularly noticeable when the rolling conditions change during operation and when rolling strips of different widths.

In contrast, in the technology of belt edge-oriented displacement, as disclosed in DE 22 06 912 C3, rolls with the same bale lengths are used in the entire set of rolls. The displaceable rollers are geometrically designed on one side in the bale edge area and provided with a relief in order to reduce locally occurring load peaks. The principle of action is based on the belt edge-oriented pushing of the bale edge, either in front of, on or even behind the belt edge. In the case of 6-roll stands in particular, moving the intermediate roll under the back-up roll specifically influences the effectiveness of the positive work roll bending. However, this method has the disadvantage that the axial displacement of the rollers on the load distribution in the respective contact feet gen out. As the bandwidth becomes smaller, the maximum peak load of the contact force distribution increases significantly. ^

In the patent specification DE 36 24 241 C2 (method for operating a rolling mill for producing a rolled strip), both methods are combined with one another. The aim is to even out the disadvantageous deflection of the work rolls under rolling force across the entire range of bandwidths and to increase the effectiveness of the roll bending systems by shortening the displacement distances without having to interrupt the continuous rolling operation. This goal is achieved by shifting the intermediate or work rolls with an applied CVC-grinding. The bale edges of the CVC rollers are positioned in the area of the belt edge. As in the case of the technology of belt edge-oriented displacement, the roller set consists of rollers of the same bale length.

The technologies discussed are separate stand concepts, as different roll geometries are required. There is an effort to implement these technologies / operating methods by means of a scaffolding concept with a geometrically identical set of rollers. The basic procedure for realizing a belt edge-oriented shift strategy exclusively for the intermediate rolls and exclusively in a 6-roll stand using a geometrically identical set of rolls has been described in detail in DE 100 37 004 A1.

The object of the invention is to extend the strip edge-oriented shifting strategy known from DE 100 37 004 A1 to the work rolls in such a way that a stand design with a geometrically identical set of rolls is realized.

The task is achieved by the characterizing features of claim 1 by specifying the displacement position of the movable work

/ Intermediate roller depending on the bandwidth at which the working / The intermediate roller is positioned in different positions relative to the strip edge, the displacement position of the respective roller being specified by piecewise linear attachment function within different strip width ranges.

Depending on the material properties, the free parameters of the attachment function are selected so that they can be preset so that the specified positions are set relative to the strip edge. The strip edge-oriented shifting of the work / intermediate rolls is carried out in such a way that they are shifted symmetrically relative to the neutral shift position (szw = 0 or SAW = 0) in the center of the stand by the same amount in each case in the direction of their axis.

The roll configuration from the CVC / CVC ^plus technology for a 6-roll or 4-roll stand is used as the basis for the stand concept. The displaceable intermediate or work roll has a bale that is longer by the CVC displacement stroke and is symmetrically located in the center of the stand for the neutral displacement position szw = 0 or SAW = 0.

The work / intermediate roll with a longer and symmetrical bale is used either with a cylindrical, crowned or superimposed CVC / C \ / C ^ ^US cut during the belt edge-oriented shifting. The deformation behavior of the roll set and the effectiveness of the positive work roll bending (6-roll stand) can be specifically influenced by suitable execution of a one-sided back grinding in combination with the superimposed roll grinding and the bandwidth-dependent optimization of the axial displacement position. The roll gap can thus be optimally adjusted.

A curved contour (e.g. CVC / CVC ^plus grinding) can also be superimposed on the cylindrical bale of the work / intermediate roll. In the case of a CVC / CVC ^plus cut, the curved contour is given by the equation R (x) = R ₀ + aι * x + a ₂ * x ² ... + a _n * x ⁿ

described.

The superimposed, curved contour of the work / intermediate roll enables the required displacement stroke to be reduced, since the beginning of the grinding back of the work / intermediate roll is positioned clearly in front of the belt edge. Firstly, the load distribution is reduced due to the longer contact length. On the other hand, the maximum of the load distribution due to the CVC / CVC ^plus grinding increasingly shifts towards the center of the scaffolding with decreasing bandwidth.

When the work / intermediate roll is moved axially, the start of the regrinding is positioned outside, on or within the belt edge, i.e. within the belt width. The positioning depends on the bandwidth and the material properties, whereby the elastic behavior of the roll set and the effectiveness of the positive work roll bending (6-roll stand) can be set.

By optimizing the shift position of the work / intermediate rolls, bale areas within the set of rolls are specifically hidden from the force flow. The resulting negative deformations are reduced because the principle of the "ideal framework" is approximated. However, the load distributions that occur in the respective contact joints increase due to the reduced contact lengths.

Moving the CVC / CVC ^plus rollers in opposite directions also results in the possibility of specifically influencing the strip profile in the sense of a preset actuator. If the curved contour is selected in such a way that it generates no or a minimal crown in the maximally negative displacement position and a maximum crown in the maximally positive displacement position, the bandwidth-dependent framework deformation can be partially compensated for. The remaining part is compensated for by the increasing effect of the positive work roll bend as the bandwidth decreases.

Further advantages, details and features of the invention result from the following explanations of some exemplary embodiments schematically represented in the drawing figures. For better clarity, the same rollers are provided with the same reference symbols.

Show it:

FFiigg .. 11 the one-sided regrinding in the area of the bale edge of a work / intermediate roll,

2 scaffold design for belt edge-oriented shifting with superimposed CVC / CVC ^plus grinding of the intermediate rolls,

3 scaffolding concept for belt edge-oriented shifting with superimposed CVC / CVC ^plus grinding of the work rolls,

4a-4c positioning of the intermediate roll relief,

5a-5c positioning of the work roll back grinding,

Fig. 6 specification of the shift position depending on the bandwidth.

In Figure 1, the appearance and the geometric arrangement of a one-sided back grinding d in the region of the bale edge of a work / intermediate roller 10, 11 is shown schematically. DE 100 37 004 A1 describes a one-sided regrinding, as used here, in detail and shown in a drawing figure.

The length I of the one-sided relief grinding d in the area of a bale edge of the work / intermediate roll 10, 11 is divided into two areas a and b placed one against the other. In the first inner area a, starting at point do, the regrind y (x) follows the circular equation (I - x) ² + y ² = R ² with R for the roll radius. With the coordinates x and y drawn in, a regrinding y (x) of region a results from: Range a: = (R ² - (R - d) ² ) ^1/2 = y (x) = R - (R ² - (I - x) ² ) ^1/2

If a minimum necessary diameter reduction 2d is reached depending on the external boundary conditions (rolling force and the resulting roll deformation), then the relief grinding y (x) runs linearly to the edge of the bale, which results in area b.

Range b: = 1 - a => y (x) = d = const.

The transition between areas a and b can be carried out with or without a continuously differentiable transition. Furthermore, this transition of the regrinding can also be carried out with a sequential reduction of the dimension d resulting from the flattening according to a table previously determined. The loopback y (x) is then, for example, flatter in the transition area than a radius and in the end much steeper. For reasons of grinding technology, the transition to the cylindrical part has to be made via a correspondingly larger shoulder in the transition between a and b (approx. 2d).

The reduction in diameter 2d by the relief grinding y (x) is specified in such a way that the work roll 10 in a 6-roll stand can bend freely around the relief grinding y (x) of the intermediate roller 11 without fear of contact in the region b. In the 4-roll stand, the regrinding y (x) only serves to locally reduce the load peaks that occur.

Normally, the one-sided back grinding is on the upper work / intermediate roll 10, 11 on the operating side BS and on the lower work / intermediate roll 10, 11 on the drive side AS, as shown in FIGS. 2 and 3. The principle of operation does not change, however, if the reverse grinding is reversed on the upper work / intermediate roll 10, 11 on the drive side AS and on the lower work / intermediate roll 10, 11 on the operating side BS.

FIG. 2 shows the set of rolls of a 6-roll stand, consisting of the work rolls 10, the intermediate rolls 11 with extended bales and the support rolls 12. The roll band 14 is arranged symmetrically in the center of the stand. The illustrated displacement of the intermediate roller 11 by the amount szw = “+” means that it has been displaced in the direction of the drive side AS. (Positive displacement means that the upper work / intermediate roller 10, 11 in the direction of the drive side AS and the lower one Work / intermediate roll 10, 11 is moved in the direction of the operating side BS.)

FIG. 3 shows the set of rolls of a 4-roll stand, consisting of the work rolls 10 with extended bales and the support rolls 12. Here, too, a positive shift was carried out, namely the work rolls 10 by the amount SAW = .. + "■

In Figures 4a-4c and 5a-5c, the axial displacement of the work / intermediate roll 10, 11 by a displacement stroke m is shown again in detail. 4a and 5a, the start d _{0 of} the relief y (x) outside the band edge (m = +), in FIGS. 4b and 5b on the band edge (m = 0) and in FIGS. 4c and 5c within the Band edge (m = -), i.e. already positioned within the bandwidth.

In different bandwidth ranges, depending on the bandwidth, the shift position is specified by piecewise linear approach functions, which are based on different positions of the start d _{0 of} the loopback relative to the band edge. The displaceable work / intermediate roller is not positioned in front of the belt edge with a fixed dimension m as shown in FIGS. 4 and 5, as is conventional, but in dependence on the belt width in different positions P (α, ß, χ , see table 1) relative to the band edge. Within different bandwidth ranges B (a, b, c, d, e, see table 1), the shift position VP (w, x, y, z, see table 1) of the respective roller is specified by piecewise linear attachment function. The free parameters of the attachment function are selected so that the positions P specified in Table 1 are set relative to the belt edge. This also results in the displacement position VP of the roller. Depending on the material properties, the parameters can be specified variably.

In FIG. 6, an example of the specification of the bandwidth-dependent shift position of the intermediate roller in a 6-roll stand is shown in the form of a diagram. The specified displacement position VP in mm is plotted on the ordinate and the bandwidth range B is plotted on the abscissa. In the upper part of the diagram, the maximum displacement position VPm _a x is parallel to the abscissa. and in the lower part the minimum shift position VPmin. drawn in dashed form.

From this diagram, the displacement positions VP obtained for various positions P can be tapped as follows using Table 1:

• When starting to grind back on the intermediate roller at a distance P = α in mm outside the belt edge B = a in mm, a displacement position VP of w in mm results.

• When starting to grind back on the intermediate roller at a distance P = ß in mm outside the strip edge b <B <d in mm, a displacement position VP between x to z in mm results. • If the grinding back begins d ₀ on the intermediate roller at a distance P = χ in mm within the strip edge B = e in mm, this results in a displacement position VP of z in mm.

A major advantage of the stand design described is that the CVC / CVC ^plus technology and technology can be used with only one geometrically identical set of rolls the technology of band edge oriented shifting can be implemented in the manner set out above. Different types of rollers are no longer necessary. The only differences are in the applied roller grinding or a regrinding upwards. It is also possible to combine the two technologies and to optimize the deformation behavior of the roll stand and the load distribution in the contact joints using different shifting strategies (ESS technology = Enhanced Shifting Strategies).

LIST OF REFERENCE NUMBERS

10 work roll

11 intermediate roller

12 backup roller

14 Rolling strip a first, inner section length of d b second, outer section length of d d regrinding (corresponds to a diameter reduction of 2d) do start of d I length of d m displacement stroke

SAW shift amount of a work roll

Szw shift amount of an intermediate roller x. y Cartesian coordinates

AS drive side

B bandwidth

BS operating side

P position of 10, 11 relative to the band edge

R roll radius

Ro exit roller radius

VP shift position

Claims

claims

1. A method for optimizing displacement strategies as a function of the bandwidth in order to make the best possible use of the advantages of the CVC / CVC ^plus technology in the operation of belt edge-oriented displacement in 4- / 6-roll stands, each comprising a pair of work rolls (10) and backup rolls (12) and additionally a pair of intermediate rolls (11) in 6-roll stands, at least the work rolls (10) and the intermediate rolls (11) cooperating with devices for axial displacement, and each work / intermediate roll (10, 11) one by the CVC shift stroke has elongated bales with one-sided relief grinding y (x) in the area of the bale edge, characterized by specifying the displacement position (VP) of the displaceable work / intermediate roller (10, 11) as a function of the bandwidth, after which the work / intermediate roller (10, 11) is positioned in different positions (P) relative to the band edge (14) and the Ver. Within different band width ranges (B) sliding position (VP) of the respective roller is specified by piecewise linear approach function.

2. The method according to claim 1, characterized in that, depending on the material properties, the free parameters of the attachment function are chosen so that they can be predetermined so that the predetermined positions (P) are set relative to the strip edge (14).

3. The method according to claim 2, characterized in that the strip edge-oriented shifting of the work / intermediate rolls (10, 11) relative to the neutral shift position (szw = 0 or SAW = 0) is carried out symmetrically in the center of the stand by the same amount in each case in the direction of their axis.

4. Rolling mill comprising 4-16-roll stands in CVC design, each with a pair of work rolls (10) and backup rolls (12) with 4-roll stands and additionally a pair of intermediate rolls (11) with 6-roll stands, with at least the work rolls ( 10) and the intermediate rollers (11) cooperate with devices for axial displacement, for carrying out the method according to one or more of claims 1 to 3, characterized in that the displaceable work / intermediate rollers (10, 11) of the roll stands each have one have longer and symmetrical bales around the axial CVC displacement stroke, which is overlaid with a curved roller contour with (CVC / CVC ^plus grinding) and is provided with a one-sided back grinding (d).

5. Rolling mill according to claim 4, characterized in that the curved roll contour (CVC / CVC ^plus grinding) by the equation R (x) = Ro + ai * x + a ₂ * x ² ... + a _n * x ⁿ where Ro is the radius of the exit bale.

6. Rolling mill according to claim 5, characterized in that the length (I) of the one-sided relief grinding y (x) of the work / intermediate rolls (10, 11) is separated into two adjacent areas (a) and (b), where the first region (a), beginning with the radius (Ro), follows the circular equation (I - x) ² + y ² = R ² and the region (b) linearly runs, which results in the following regrind y (x) or the following diameter reduction 2 • y (x) for these areas as a result of the dimension resulting from the roll flattening: Area (a): = (R ² - (R - d) ² ) ^{1 / 2} = y (x) = d = R - (R ² - (I - x) ² ) ^1/2 range (b): = I - a = y (x) = d = const.

7. Rolling mill according to claim 4 and 5, characterized in that the transition of the relief grinding y (x) between the areas (a) and (b) with a sequential withdrawal of the dimension (d) resulting from the roll flattening according to a determined table is made.

8. Rolling mill according to one or more of claims 4 to 7, characterized in that the rolling stands have a geometrically identical set of rolls.