EP0102013B1 - Method of rolling off metallic materials, particularly strip material, and rolling mill for carrying out the method - Google Patents

Abstract

1. Method for the rolling-down of metallic materials, in strip material (3), by means of at least a respective upper and lower working roll (1 and 2), in which the speed of the rolled stock is guided or determined (7, 8, 9 ; 10, 11, 12 ; 13, 14, 15, 16) from outside the stand (1, 2) or the stands (1, 2), characterized thereby, that the peripheral roll speeds (Vo , Vu ) of at least one working roll (1, 2) are set to values which exceed the rolled stock speed (VA ) at the rolled stock exit (6) and/or fall below the rolled stock speed (VE ) at the rolled stock entry (5).

Description

The invention relates to a method for rolling out metallic materials, in particular strip material, by means of at least one upper and one lower work roll, in which the rolling stock speed is guided or determined from outside the stand or the stands.

Such a method is already known from US-A-3 823 593.

In this known method, the rolling stock speed on the inlet side of the stand is guided or determined by the peripheral speed of one work roll and the rolling stock speed on the outlet side of the stand by the other work roll of the pair of work rolls, in a ratio that corresponds to the desired reduction of the rolling stock is fixed.

In the most widespread methods for rolling out metallic materials, in particular strip material, the two work rolls acting on the rolling stock are driven in such a way that they have corresponding circumferential roller speeds, that is to say they have a speed ratio of 1: 1 to one another.

These known rolling processes are carried out in such a way that the so-called flow separators lie within the roll gap, which is delimited on the inlet side by a normal plane for the rolling stock passage determined by the rolling stock inlet and on the outlet side by a normal plane determined by the rolling barrel outlet.

Through these flow separations, a synchronization point is determined in the roll gap at which a relative speed occurs between the rolling stock and the circumference of the work roll. The position of the flow sheath in the roll gap is adjusted in accordance with the forces acting on the rolling stock, for example the forward and backward pull, the horizontal component of the rolling forces and the frictional forces between the rolling stock and the work roll. As long as there is a flow sheath in the area of the roll gap, the stand is able to guide the rolling stock with the help of the work rolls, but if no flow sheath occurs in the roll gap, it is no longer possible to guide the rolling stock through the work rolls. because the pull-through reserve of the roll stand is exhausted. In such an operating state, the rolling stock speed is no longer determined by the work rolls, because the roller circumferential speed and the rolling stock speed do not match at any point in the roll gap.

Rolling with a position of the flow edges near the rolling stock entry or exit is also problematic because an unstable condition can easily arise even with slight changes in the rolling conditions, for example the strip tension, which causes vibration phenomena, in particular rotational vibrations of the work rolls, and the like resulting slide on the rolling stock.

When cold rolling metallic materials, in particular strip material, the aim today is to work with the lowest possible power and power requirements. This is achieved by improving the lubrication and reducing friction. However, this also has the disadvantage of reducing the pull-through reserve of the scaffolding, i. H. a floating edge position close to the rolled material outlet, with otherwise the same rolling conditions with regard to work roll diameter, removal and strip tension.

Since special emphasis is placed on energy savings when hot-rolling metallic materials, in particular strip material, and in the subsequent pickling lines, there is a need to use larger hot-strip thicknesses for cold rolling mills and to operate them with higher passes, especially in the first stands. However, an increase in the number of passes under otherwise identical rolling conditions also reduces the pull-through reserve of the stands.

In order to avoid these disadvantages, US-A-3 823 593 has disclosed a rolling method of the type specified at the outset, the so-called push-rolling method, which is characterized in that the working rollers, which interact in pairs, are at a circumferential speed ratio which deviates from 1. In this case, the peripheral speed ratio between the work rolls interacting in pairs is set so that there are always two different positions of the flow sheaths for the faster and the slower work roll within the roll gap.

Due to the different roller circumferential speeds of the two working rollers working together, it is necessary with this push rolling method to guide or determine the rolling stock speed from outside the stand. For this purpose, according to the state of the art, drivers or reels act on the rolling stock on the inlet side and the outlet side of the stand, the drive speed for the inlet-side rolling stock driver or rolling stock reel in a fixed relationship to a work roll and the driving speed of the outlet-side rolling stock driver or Rolled goods reel has a fixed relationship of dependency on the other work roll of the work roll pair, in order thereby to ensure the maintenance of the two floating edges within the roll gap.

A rolling mill known from US Pat. No. 3,823,593 for performing the method specified at the outset works with at least one work pair of rollers and devices associated therewith for varying the rolling stock speed relative to the circumferential circumferential speed of the pair of work rolls, the drive speeds of the two work rolls of the pair of work rolls being variable relative to one another, but fixedly specified during the rolling operation, and a rolling stock driver or a rolling stock reel being arranged upstream of this pair of work rolls. The object of the invention is to provide a method for rolling out metallic materials, in particular strip material, of the generic type and a rolling mill for exercising the same, which, taking advantage of the advantages resulting from better lubrication and the higher pass reduction during cold rolling, ensures adequate stability of the rolling process at all times guaranteed.

In terms of process technology, this object is achieved by the characterizing features of claim 1.

Here it proves to be advantageous that even with fluctuations in the rolling parameters, namely the rolling stock thickness, the trains, the friction or the like, no flow sheath occurs within the roll gap, because there is no synchronous point anywhere between the rolling stock speed and the circumferential roll speed and therefore with negative pull-through reserve is rolled.

According to the invention, in the simplest case it is possible to carry out the method either according to the features of claim 2 or else according to the features of claim 3.

However, a type of method with the features of the invention according to claim 4 or 5 has proven particularly useful. Of course, it is also possible to operate the method according to claim 6, because this particularly promotes the operation of the push-rolling method.

In terms of process technology, it is particularly recommended according to the invention to maintain a safety distance between the respective roller circumferential speed and the speed of the rolling stock, which prevents the formation of flowing sheaths in the area of the roll gap even with small rotational vibrations of the work rolls. In this context, the method features of claim 7 have proven successful. As practical tests have shown, this goal can be achieved if the rolling stock speed is set larger and / or smaller deviating from the respective peripheral roll speed by approximately 5%.

If a constant pass reduction on the rolling stock is to be achieved, it is advantageous according to the invention to use the method features of claim 8. However, it is also possible to use the procedural measures according to claim 9 for the purpose of a variable pass inspection on the rolling stock.

A rolling mill for practicing the method is distinguished from the prior art based on US Pat. No. 3,823,593 by the characterizing features of claim 10 and can be further developed according to the features of claims 11 to 13.

From DE-A-2345463 a rolling mill is known to be known which, in addition to three rolling stands connected in series, each also has an inlet-side and an outlet-side reel. In this case, the two outer roll stands can each be operated at the peripheral speeds of their rolls, which deviate from the rolling stock speed determined by the peripheral speed of the work rolls of the middle roll stand.

However, the known rolling mill is not designed so that the drive speeds of the two work rolls of the middle roll stand can be varied relative to one another, but are predefined during the rolling operation.

It is therefore not possible in the known rolling mill to set the drive speed on the upstream and / or downstream rolling stand in such a way that the relative speed of the rolled strip to the two work rolls of the middle one. Roll stand is different in each case.

Further features, details and advantages of the invention are explained in detail below with reference to a drawing.

• Figuren 1 bis 5 in schematisch vereinfachter Darstellung verschiedene Verwirklichungsmöglichkeiten für das erfindungsgemäße Walzverfahren,
• Figur 6 in schematischer Darstellung ein Walzwerk zur Ausübung des Walzverfahrens nach Fig. 1,
• Figur 7 schematisch dargestellt, ein Walzwerk zur Ausübung des Walzverfahrens nach Fig. 2, 3 und 5 und
• Figur 8 in schematischer Darstellung ein Walzwerk zur Ausübung des Walzverfahrens nach Fig. 4.

The show

• FIGS. 1 to 5, in a schematically simplified representation, different implementation options for the rolling method according to the invention,
• 6 shows a schematic representation of a rolling mill for carrying out the rolling process according to FIG. 1,
• FIG. 7 shows schematically a rolling mill for carrying out the rolling process according to FIGS. 2, 3 and 5 and
• 8 shows a schematic illustration of a rolling mill for carrying out the rolling process according to FIG. 4.

In all the figures of the drawing, the upper work roll 1 and the lower work roll 2 of a rolling mill are shown, between which, for example, metallic strip material is passed as the rolling stock 3. The length of the roll gap 4 between the two work rolls 1 and 2 is determined, on the one hand from the entry plane 5 which is normal to the direction of passage of the rolling stock 3, on the other hand from the exit plane 6 thereof which is also normal to the direction of passage of the rolling stock 3, as shown in FIGS. 1 to 5 clearly shows.

1 to 5 of the drawing, the centering angles α1 and a2 are indicated, which are determined by the entry plane 5 and the exit plane 6 of the rolling stock 3 to the axes of rotation of the work rolls 1 and 2, which in each case the contact surfaces of the work rolls 1 and 2 determine with the rolling stock 3 over the length of the roll gap 4.

The centering angles a1 and a2 are each shown in the same size in FIGS. 1 to 5.

The diagrams according to FIGS. 1a and 1b belong to FIG. 1. 1a and 1b are the Ge speed ratios, which result from the rolling process according to FIG. 1, clarified. Along the length of the roll gap 4 are, on the one hand, the roll peripheral speed V _o or V _u and, on the other hand, the rolling stock speed V _w - at the entry 5 of the rolling stock 3 into the roll gap 4 with V _E and at the exit 6 of the rolling stock 3 from the roll gap 4 V _A designated - plotted. The respective vertical distance between V _o and V _{w represents} the relative speed between work roll 1 or 2 and rolling stock 3. 1a and 1b illustrate that the circumferential speeds V _o and V _{u of} both work rolls 1 and 2 are greater than the rolling stock speed V _w over the entire roll gap 4 and thus there is no flow sheath within the roll gap.

2, the work rolls 1 and 2 are operated at peripheral speeds V _o and V _u which are lower than the rolling stock speed V _w . The curves V _w and V _o and V _u do not intersect (see FIGS. 2a and 2b), so that there is no flow divide here either.

3, the speed ratios for the upper work roll 1 are as explained in connection with FIG. 1, ie the peripheral speed V _{o of} the work roll 1 is greater than the rolling stock speed V _w (cf. FIG. 3a). The lower work roll 2, on the other hand, is operated according to FIG. 2 with a circumferential speed V _u below the rolling stock speed V _w (cf. FIG. 3b).

The rolling process according to FIG. 4 corresponds to the rolling process according to FIG. 1 with regard to the speed relationships between the upper work roll 1 and the rolling stock 3 (cf. FIG. 4a). As can be seen in FIG. 4b, on the other hand, the lower work roll 2 and the rolling stock 3 have identical speeds in the floating separation point F, that is to say the relative speed is 0 in the floating separation point F, and the rolling stock speed V _w is lower before the point F in the direction of the entry plane 5 the point F in the direction of the exit plane 6, it is greater than the circumferential roller speed V _{u of} the lower work roll 2.

5, mixing ratios similar to those in the method according to FIG. 4 occur. The speed ratios in the area of the lower work roll 2 correspond to those according to FIG. 2, ie the rolling stock speed V _w is always higher than the peripheral speed V _{u of} the work roll 2. The speed ratios in the area of the upper work roll 1 are such that here, as in FIG. 4b forms a floating shear point F.

The fact that, according to FIG. 4b, the flow separation point F is close to the entry level 5 and according to FIG. 5a, the flow separation point F is close to the exit level 6 is particularly advantageous and therefore practical. However, it is conceivable for the flow separation points F to be displaced within the roll gap 4 in the direction of the exit plane 6 or the entry plane 5.

It is readily apparent that in the rolling processes shown in FIGS. 1 to 3, the work rolls 1, 2 of the rolling stand no longer have any guiding properties for the rolling stock 3 and therefore the rolling stock speed V _w must be guided or determined from outside the stand .

For example, if the outlet speed V _{A of} the rolling stock 3 in the exit plane 6 of the roll gap is to be lower than the peripheral speed V _o , V _{u of} the two work rolls 1 and 2, as indicated in FIG. 1, then it proves to be expedient that 6 from the infeed side of the rolling stand by determining the infeed speed V _{E of} the rolling stock 3 either through a decoiler 7 or through a driver 8 arranged between it and the rolling stand in the form of a pair of S-rollers. The take-up reel 9 arranged downstream of the roll stand, however, runs at a speed adapted to the outlet speed V _{A of} the rolling stock 3.

If the circumferential speeds V _o and V _{u of} the work rolls 1 and 2 are to be kept lower than the running speed of the rolling stock 3 in the entry plane 5 of the roll gap 4 according to FIG. 2, then it is advantageous to guide the rolling stock 3 using an arrangement according to FIG. 7 to be used, in which either a take-up reel 11 arranged downstream of the roll stand or a driver 12 arranged between it and the roll stand, designed as an S-roll pair, determines the outlet speed V _A for the rolling stock 3. The decoiler 10 then runs here in accordance with the rolling stock inlet speed V _E, which is higher than the peripheral speed of the rolls.

. The arrangement according to FIG. 7 is also used when the method according to FIG. 3 is carried out, because here too it is necessary to work with increased forward pull. With this method, the frictional forces cancel each other out, but the horizontally acting components of the rolling forces must be compensated for by forward pulling.

With reference to FIGS. 1, 2, 3, 6 and 7 it was explained how conventional Bendwalzenverfahren can be improved while ensuring sufficient stability of the rolling process by avoiding the formation of floating shafts within the roll gap so that a reduced despite optimal lubrication and the associated reduction in friction Power and power requirements occur as well as increased passes can be achieved under otherwise identical rolling conditions.

An arrangement according to FIG. 7 is expediently also used to operate the method according to FIG. 5, where a flow sheath F (on the upper work roll 1) is formed.

In the method according to FIG. 4 it can happen that horizontal forces occur which almost correspond to those in the method according to FIG. 1. For this reason, it is advisable to do both before and also to provide drivers 14 and 16 according to FIG. 8 behind the roll stand.

It has already been mentioned that in the rolling processes described with reference to FIGS. 1 to 5, the pair of work rolls 1, 2 have pre-and / or post-rolled material drivers 8; 12; 14, 16 or the rolled goods reel 7, 9; 10, 11; 13, 15 are set to a drive speed that deviates from the circumferential roller speed or must be adjustable.

The speed ratio required for the respective rolling process between the circumferential roll speed and the drive speed for the driver or reel can be determined on the basis of a speed which is fixed for the work rolls 1 and 2. By a between the drive for the work rolls 1 and 2- and the drive for the drivers 8; 12; 14, 16 and / or the drives for the reel 7, 9; 10, 11; 13, 15 provided (electronic) control and / or regulating devices, the rolling stock inlet and the rolling stock outlet speeds can then be preset in a ratio corresponding to the respective pass reduction. However, it is also possible to design the (electronic) control and / or regulating device in such a way that the rolling stock inlet or outlet speed and the roller peripheral speed can be controlled and / or regulated in a mutually dependent manner.

It has proven useful to set the rolling stock (infeed and outfeed) speed by up to 20% from the respective circumferential roller speed - larger and / or smaller - if optimum stability of the rolling process is to be guaranteed. Deviations of 5 to 8%, however, already ensure sufficient stability of the rolling process.

Claims (13)

1. Method for the rolling-down of metallic materials, in particular strip material (3), by means of at least a respective upper and lower working roll (1 and 2), in which the speed of the rolled stock is guided or determined (7, 8, 9 ; 10, 11, 12 ; 13, 14, 15, 16) from outside the stand (1, 2) or the stands (1, 2), characterised thereby, that the peripheral roll speeds (V_o, V_u) of at least one working roll (1, 2) are set to values which exceed the rolled stock speed (V_A) at the rolled stock exit (6) and/or fall below the rolled stock speed (V_E) at the rolled stock entry (5).

2. Method according to claim 1, characterised thereby, that the peripheral roll speeds (V_o and V_u) of both working rolls (1, 2) are set to be greater than the rolled stock speed (V_A) at the rolled stock exit (6 ; Fig. 1).

3. Method according to claim 1, characterised thereby, that the peripheral roll speeds (V_o and V_u) of both working rolls (1, 2) are set to be smaller than the rolled stock speed (V_E) at the rolled stock entry (5 ; Fig. 2).

4. Method according to claim 1, characterised thereby, that the peripheral speed (V_o) of the one working roll (1) is set to be greater than the rolled stock speed (V_A) at the rolled stock exit (6) and the peripheral speed (V_u) at the other working roll (2) is set to be smaller than the rolled stock speed (V_e) at the rolled stock entry (5) (Fig. 3).

5. Method according to claim 1, characterised thereby, that the peripheral speed (V_o) of only one working roll (1) is set to be greater than the rolled stock speed (V_A) at the rolled stock exit (6), whilst the peripheral speed (V_u) of the other working roll (2) is kept greater than the rolled stock speed (V_E) at the rolled stock entry (5), but smaller than the rolled stock speed (V_A) at the rolled stock exit (6) (Fig. 4).

6. Method according to claim 1, characterised thereby, that the peripheral speed (V_u) of only one working roll (2) is set to be smaller than the rolled stock speed (V_E) at the rolled stock entry (5), whilst the peripheral speed (V_o) of the other working roll (1) is kept smaller than the rolled stock speed (V_A) at the rolled stock exit (6), but greater than the rolled stock speed (V_E) at the rolled stock entry (5, Fig. 5).

7. Method according to one of the claims 1 to 6, characterised thereby, that the rolled stock speed (V_A or V_E) is set to be deviating by up to 20 % - up or down - from the respective peripheral roll speed (V_o or V_u).

8. Method according to one of the claims 1 to 7, characterised thereby, that rolled stock entry speed (V_E) and rolled stock exit speed (V_A) are fixedly preset each relative to the other in a ratio corresponding to the respective reduction per pass.

9. Method according to one of the claims 1 to 7, characterised thereby, that rolled stock (entry and exit) speed and peripheral roll speed are controlled and/or regulated in mutual dependence.

10. Rolling mill for the performance of the method according to one of the claims 1 to 9, with at least one working roll pair (1, 2), in which the rotational drive speeds of both the working rolls (1 and 2) are variable each relative to the other, but fixedly preset during the rolling operation (Figs. 1a and 1b to Figs. 5 and 5b) and wherein a rolled stock reel (7 or 11 or 13, 15) is arranged upstream and/or downstream of this working roll pair (1, 2) as devices for the variation of the rolled stock speed (V_w) relative to the peripheral roll speed (V_o and V_u) of the working roll pair (1, 2), characterised thereby, that the driving speed of at least one of the rolled stock drivers (8 or 12 or 14, 15) or the rolled stock reels (7 or 11 or 13, 15), that are connected upstream and/or downstream ; are so set or settable that the corresponding peripheral speed lies outside a range which comprises the two peripheral rool speeds as well as all peripheral speeds lying therebetween.

11. Rolling mill according to claim 10, characterised by a control and/or regulating device, which stands in connection with the drive for working roll pair (1, 2), for the driving speed of the upstream driver (8 ; Fig. 6) or downstream driver (12 ; Fig. 7).

12: Rolling mill according to the claim 11, characterised thereby, that the control and/or regulating device stands in connection with the rolled stock driver (14) or rolled stock reel (13) arranged upstream of the working roll pair (1, 2) as well as also with the rolled stock driver (16) or rolled stock reel (13) downstream thereof and is designed for the setting of a ratio of the driven speed of each driver (14 and 16) or each rolled stock reel (13 and 15) to the peripheral roll speeds (Vo and Vu ) greater or smaller than unity.

13. Rolling mill according to the claim 11, characterised thereby, that the control and/or regulating device for the rolled stock driver (14) or rolled stock reel (13) at the inlet side stands in connection with the one working roll (1), but for the rolled stock driver (16) or rolled stock reel (13) stands in connection with the other working roll (2).

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