WO2005063417A1

WO2005063417A1 - Combined operating modes and frame types in tandem cold rolling mills

Info

Publication number: WO2005063417A1
Application number: PCT/EP2004/013623
Authority: WO
Inventors: Andreas Ritter; Rüdiger Holz; Horst Oemkes
Original assignee: Sms Demag Ag
Priority date: 2003-12-19
Filing date: 2004-12-01
Publication date: 2005-07-14
Also published as: RU2006126054A; US20070095121A1; RU2358819C2; ATE426469T1; TWI324093B; DE102004020131A1; DE502004009244D1; CN1894053A; EP1699573B1; BRPI0417703A; EP1699573A1; JP2007514548A; KR101224940B1; KR20060130582A; CA2548777C; TW200529944A; ES2322365T3; CA2548777A1

Abstract

The invention relates to a method for combining the operating modes of individual rolling frames in a tandem cold rolling mill comprising respective pairs of working rolls (10) and back-up rolls (12) in 4-roll frames and in addition a pair of intermediate rolls (11) in 6-roll frames, at least the working rolls (10) and the intermediate rolls (11) interacting with devices for axial displacement. Said method is characterised by a combination of the following technologies: use of CVC/CVCplus technology with CVC roll contours of a higher order, where each working/intermediate roll (10, 11) comprises a roll surface that is extended by the amount of the travel displacement; use of Pair Cross (PC) technology, whereby each working/intermediate roll (10, 11) can be pivoted parallel to the strip plane; use of strip-edge oriented displacement of the working/intermediate rolls (10, 11), each of the latter (10, 11) having a roll surface that is extended by the amount of the travel displacement, with a cylindrical or spherical section and said rolls being displaced symmetrically against one another relative to the neutral displacement position (sZW = 0 and sAW = 0) in the centre of the frame (Y-Y) by an identical amount in the direction of their rotational axes (X-X). The method is also characterised in that the CVC/CVCplus technology, the strip-edge oriented displacement technology and optionally the PC technology can be achieved using a suitable plant concept with a single geometrically identical set of rolls.

Description

Combined driving styles and scaffolding types in cold tandem lines

The invention relates to a method for the combined operation of individual roll stands within a cold tandem mill, each comprising a pair of work rolls and backup rolls in 4-roll stands and additionally a pair of intermediate rolls in 6-roll stands, at least the work rolls and the intermediate rolls interacting with devices for axial displacement.

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 classic system concept of a cold tandem mill consists of lining up several 4-roll stands. The number of scaffolds required is largely determined by the total acceptance and the final thickness to be achieved. In addition to the basic concepts with bending systems and fixed roll crowns as actuators influencing the roll gap, ^" there are essentially three further stand designs that additionally influence the roll gap either by moving or swiveling the work rolls based on different working principles.

These are: • Technology of band-oriented shifting • CVC / CVC ^plus technology • PC technology (per cross - swiveling the work rolls)

Due to different technological criteria, it can make sense to deviate from the classic system concept (consisting exclusively of 4-roll stands) and to design individual stands as 6-roll stands.

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 torques, the work rolls can be driven by the adjacent roll via frictional engagement. 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 middle level of the stand, the set of rolls is supported, which leads to a significant reduction in the horizontal deflection.

An additional influencing of the rolling process with regard to the flatness and the roll gap consists in pivoting the work rolls, whereby, as is described in JP 57 190 704 A for 4-roll stands, the work / intermediate rolls around a common pivot point in the roll axis center parallel to the strip - Plane can be pivoted against each other by the same amount at the same time. 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 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.

Another criterion for the quality of the end product is the surface quality of the sliver that runs out. Textured (roughened) and chrome-plated rollers allow the surface of the belt to be preset. In order to avoid markings on the end product by shifting wear edges or shading on the belt surface due to the occurrence of relative speed differences across the width of the sliver, it makes sense to design the last stand of a cold tandem mill as a 6-roll stand. The work rolls are cylindrical or have a slight crown. They are not shifted in the rolling process.

The principles of action described above are separate stand concepts, since 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 movable roller cannot be pushed with its bale edge under the stationary roller bale. This prevents surface damage / markings. The work rolls are generally supported on the intermediate or backup rolls over their entire length. As a result, the rolling force exerted by the support rolls is transmitted to the entire length of the work rolls. The result of this is that the ends of the work rolls which protrude laterally beyond the rolling stock and are therefore not involved in the rolling process are bent in the direction of the rolling stock by the rolling force exerted on them. the. 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 shifting, 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 back cut 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 particular with 6-roll stands, moving the intermediate roll under the backup roll has a targeted influence on 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 joints. As the bandwidth becomes smaller, the maximum peak load of the contact force distribution increases significantly.

The patent specification DE 36 24241 C2 (method for operating a rolling mill for producing a rolled strip) combines both methods with one another. The aim is to even out the disadvantageous deflection of the work rolls under rolling force over the entire range of bandwidths and to increase the effectiveness of the roll bending systems by shortening the displacement paths without having to interrupt the continuous rolling operation. This goal is achieved by shifting intermediate or work rolls with an applied CVC cut. 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. For reasons of economy, efforts are made to design all scaffolding equally if possible in order to reduce the costs for maintenance and spare parts. In the past, cold tandem lines were therefore designed in the classic system layout or consistently in the technologies described.

The object of the invention is to implement these technologies / modes of operation by means of a stand design with a geometrically identical set of rolls, which is not only limited to a 6-roll stand and not only to the intermediate rolls.

In terms of process, the task is solved by the characterizing features of claim 1 by a combined use of the following technologies within the multi-stand cold tandem mill:

• Use of the CVC / CVC ^plus technology with CVC rolling contours of higher order, whereby each work / intermediate roll has a bale extended by the displacement stroke;

• Use of Per Cross (PC) technology, whereby each work / intermediate roll can be swiveled parallel to the belt level; • Use of the belt edge-oriented shifting of the work / intermediate rolls, each work / intermediate roll having a bale extended by the shift stroke with a cylindrical or spherical cut and shifting it symmetrically relative to the neutral shift position in the center of the stand by the same amount in the direction of its axis of rotation become.

A system for carrying out the method is characterized by the features of claim 5. 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.

The work / intermediate roll with a longer and symmetrical bale is used either with a cylindrical or spherical cut during belt edge-oriented displacement. By suitably performing a regrinding in the area of the beam edge in combination with the overlaid roller grinding and the bandwidth-dependent optimization of the axial displacement position, the deformation behavior of the roller set and the effectiveness of the positive work roll bending (6-roll stand) can be specifically influenced and the roll gap can be optimally adjusted ,

Furthermore, by optimizing the shift position of the work / intermediate rolls, bale areas within the set of rolls are selectively 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.

The stand designs described are modified in accordance with the invention in such a way that the roll gap is influenced either by the displacement or the pivoting of the work / intermediate roll. A 6-roll stand is imperative in any case if an additional actuator influencing the edge drop of the strip is to be implemented in the stand. This requires two independent sliding systems for profile and flatness. The plant layout is largely determined by these criteria. Depending on the requirements placed on the rolling process, the range of system configurations ranges from classic cold tandem mills, consisting of 4-roll stands, to combined plants, consisting of 4- / 6-roll stands, right up to cold tandem mills. esse, which consists exclusively of 6-roll stands. The basic procedure for realizing a belt edge-oriented shifting strategy exclusively for the intermediate rolls and exclusively in a 6-roll stand using a geometrically identical set of rolls is described in detail in DE 100 37 004 A1.

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:

1 shows the geometry of the intermediate roll without roll grinding in a 6-roll stand,

2 the geometry of the work roll without roll grinding in a 4-roll stand,

Fig. 3 shows the one-sided setback in the area of the barrel edge of a work ^■ roll / intermediate roll, Fig. 4 stand conceptual with elongated intermediate roll barrel,

5 scaffolding concept with extended work roll bale,

6a-6c positioning of the intermediate roll relief,

Fig. 7a-7c positioning of the work roll relief.

In Figures 1 and 2, the geometry of the intermediate / work roll 11, 10 is shown without grinding. 1, the displaceable intermediate roller 11 provided with an elongated bale is located symmetrically in the stand center YY between the work roller 10 and the support roller 12 in the neutral displacement position szw ^" = 0. In FIG. 2, the work roller 10 has an elongated bale . You too is in the neutral shift position SAW = 0 symmetrically in the center of the frame YY.

FIG. 3 shows schematically the appearance and the geometrical arrangement of a one-sided backward d in the area of the bale edge of a work / intermediate roll 10, 11. 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 against one another. In the first inner area a, starting at point d ₀ , the regrind d follows the circular equation (I - x) ² + y ² = R ² with R for the roll radius. An area d (x) of the regrind d then results for area a of: Area a: = (R ² - (R- d) ² ) ^1/2 => d = d (x) = R- (R ² - (l -x) ² ) ^1/2

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

Range b: = I - a = d = d (x) = 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 regrind d is then, for example, flatter than a radius in the transition area and is much steeper at the end. The transition is due to grinding reasons to the cylindrical part via a correspondingly larger shoulder in the transition between a and b (approx. 2d).

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

Normally, the one-sided relief grinding d is located 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. 4 and 5. The principle of operation does not change, however, if the reverse grinding d 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.

6a to 6c show the axial displacement of the intermediate roller 11 by a displacement stroke m. In FIG. 6a the beginning d _{0 of} the loopback d is positioned outside (m = +), in FIG. 6b on (m = 0) and in FIG. 6c inside (m = -) the band edge, that is to say already within the band width. The positioning depends on the bandwidth and the material properties, which means that the elastic behavior of the roll set and the effectiveness of the positive work roll bending (6-roll stand) can be set.

Finally, FIGS. 7a to 7c show the strip edge-oriented displacements of the work roll 10 which are carried out in the same way as for the intermediate roll 11 in FIGS. 6a to 6c.

In different bandwidth ranges, the shift position is specified by piecewise linear approach functions, which are based on different positions of the beginning do of the regrinding d relative to the band edge. A major advantage of the stand design described is that the CVC / CVC ^plus technology and the technology of belt edge-oriented displacement can be realized with only one geometrically identical set of rolls. Different types of rollers are no longer necessary. The only differences are in the applied roller grinding or a regrinding upwards. It is possible to combine both technologies with a swiveling of the work / intermediate rolls in the strip level.

LIST OF REFERENCE NUMBERS

10 work roll

11 intermediate roller

12 backup roller

14 rolled strip a first inner section length of d b second outer section length of d d regrinding do start of d d (x) of x dependent amount 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

BS operating side

R roll radius

Ro exit roller radius

X-X axis of rotation

Y-Y scaffold center

Claims

claims

1. Method for driving the roll stands of a cold tandem mill, each comprising 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, at least the work rolls (10) and the intermediate rolls (11) From the ^'chtungen cooperate for axial displacement, characterized by the combined use of the following technologies within the mehrgerustigen tandem cold rolling mill: • use of the CVC / CVC ^plus - technology with CVC roll contours of higher order, wherein each working / intermediate roll (10, 11 ) has a bale extended by the shifting stroke; • Use of Per Cross (PC) technology, whereby each work / intermediate roll (10, 11) can be swiveled parallel to the belt level; • Use of the belt edge-oriented displacement of the work / intermediate rolls (10, 11), each work / intermediate roll (10, 11) having a bale extended by the displacement stroke with a cylindrical or crowned cut and this relative to the neutral displacement position (szw = 0 or SAW = 0) in the center of the scaffold (YY) can be shifted symmetrically by the same amount in the direction of their axis of rotation (XX).

2. The method according to claim 1, characterized in that for the use of the belt edge-oriented displacement, the work / intermediate rolls (10, 11) are provided with a one-sided back grinding (d), wherein when moving each work / intermediate roll (10, 11) beginning (d ₀ ) of the loopback (d) is positioned outside or on or within the band edge, ie within the band width of the band (14).

3. The method according to claim 1 or 2, characterized in that the displacement position of the work / intermediate roll (10, 11) is specified in different bandwidth ranges by piecewise linear approach functions, which different positions of the start (do) of the backfeed (d) relative to Band edge (14) are based.

4. The method according to claim 1, 2 or 3, characterized in that the best possible use of the technology combination within the multi-pitch cold cold tandem mill takes place by optimized shift strategies as a function of the bandwidth.

5. Cold tandem mill, comprising 4- / 6-roll stands, each with a pair of work rolls (10) and backup rolls (12) in 4-roll stands and additionally a pair of intermediate rolls (11) in 6-roll stands, at least the work rolls (10) and the intermediate rollers (11) cooperate with devices for axial displacement, characterized in that the work / intermediate rollers (10, 11) of the roll stands each have a symmetrical bale, which is extended by the axial displacement stroke and has a cylindrical or crowned ground shape for the neutral shift position (szw = 0 or SAW = 0) is located symmetrically in the center of the scaffold (YY).

6. Cold tandem mill according to claim 5, characterized in that the bale of the work / intermediate rolls (10, 11) is provided with a one-sided relief (d), the length (I) of which adjoins in two Areas (a) and (b) are separated, the first area (a), beginning with the radius (R ₀ ), following the circular equation (l - x) ² + y ² = R ² and the area (b) linear runs, which results in the following regrind (d) or the following diameter reduction (2d) for these areas: Area (a): = (R ² - (R - d) ² ) ^1/2 => d = d (x) = R - (R ² - (l - x) ² ) ^1/2 range (b): = I - a => d = d (x) = const.

7. Cold tandem mill according to claim 5 or 6, characterized in that the transition of the relief (d) between the areas (a) and (b) is carried out with a sequential reduction of the dimension resulting from the roll flattening (d) according to a determined table.

8. Cold tandem mill according to claim 5, 6 or 7, characterized in that a combination of the different technologies by appropriate choice of the roll stands: • the belt edge-oriented displacement of the work / intermediate rolls (10, 11), • the CVC technology, and • the Swiveling of the work rolls (10), the PC technology (Per Cross), is made possible within the multi-stand cold tandem mill.

9. The method according to claim 8, characterized in that the CVC / CVC ^plus technology and the technology of the belt edge-oriented displacement and, if appropriate, the PC technology is realized with only one geometrically identical set of rollers by appropriate system design.