Metal deforming – By use of roller or roller-like tool-element – With carrier for roller-couple or tool-couple
Reexamination Certificate
2001-02-16
2002-06-25
Larson, Lowell A. (Department: 3725)
Metal deforming
By use of roller or roller-like tool-element
With carrier for roller-couple or tool-couple
C492S002000
Reexamination Certificate
active
06408668
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a supporting or intermediate roll in rolling mills for rolling flat rolling stock, in particular strip material. Such a roll comprises a cylindrical roll core and a tubular sleeve which is connected in a rotationally fixed manner to said roll core, engages coaxially around the same and between which and the roll core there are arranged hydraulically axially displaceable supporting bodies which support the roll sleeve against the roll core.
2. Discussion of the Prior Art
The profile and flatness control plays an important roll in modern hot strip mills. In this case, the negative and positive working-roll bending is the “classic” adjusting means, which allows a change in the roll gap even under load. Since, however, the conditions under which flat rolling stock is rolled are very different and width, thickness, profile and material change as well as the rolling speed and the rolling temperature, it is necessary, with the small batch sizes which are customary nowadays, to have profile- and flatness-control systems which have a large adjustment range. For this reason, in recent years, use has increasingly been made of further adjusting means in new mills, the use of ground-profile axially displaceable rolls and rolls which can be pivoted toward one another being the most well-known.
Although these known systems meet the demand of the customers of new rolling mills, who would like, in addition to the working-roll bending, at least one further adjusting means for influencing the profile, the two systems are not suitable for being adjusted under load as well.
Ground-profile rollers are also disadvantageous because, in order to achieve the desired contours, high-outlay grinding is necessary, and the geometry of this grinding also has to be very precise. Added to this is the fact that, under certain conditions, the rolling stock is deformed differently at the border and in the center; in each roll stand it is necessary to have a roll with a defined contour, which is different in each stand.
Crossing of the rolls results in the disadvantage that the crossing angle of the rolls requires particular measures for a uniform angular speed, which rules out the use of normal cross-journal universal joint shafts for driving the rolls. Moreover, the crossing produces very high axial forces, which may reach up to 10% of the radial rolling force. Added to this is the fact that the rolling-stock guidance poses problems; the rolling stock twists.
German Patent 34 14 242 has proposed a roll having the features of the generic type. In the-known sleeved roll, wedge-shaped rings are inserted between the roll core and roll sleeve, it being possible for said rings to be displaced in the longitudinal direction of the roll by pressure fluid being supplied. The wedge-shaped rings are paired with correspondingly wedge-shaped mating surfaces on the inner surface of the roll sleeve and, by virtue of a correspondingly high hydraulic pressure being applied, allow the crown of the roll to be changed and thus allow the latter to be adapted to different rolling forces and different widths of the rolling stock. The wedges with a relatively small slope, however, tend to wedge in between roll core and roll sleeve, i.e. self-locking of said wedges occurs, and this self-locking is difficult to release under rolling force. Since the wedges in the previously known solution have the function of widening the roll sleeve, it is necessary to have very high hydraulic pressures, which are to be converted into widening forces for the roll sleeve via the wedge surfaces.
SUMMARY OF THE INVENTION
The object of the present invention is, by improving a known sleeved roll, to provide an adjusting means, for profile and flatness regulation, which can be used, in particular, under rolling load, avoids the disadvantages of the prior art and makes possible, by virtue of the roll-barrel profile being changed within wide limits, adaptation to the different conditions during the rolling of flat material.
In order to achieve the object, the invention proposes to form the supporting bodies on at least two annular pistons which are arranged symmetrically in relation to the roll center and are sealed in relation to the roll core and the inside of the roll sleeve. The supporting bodies comprise a plurality of annular supporting bearings which are arranged on the outer circumference of the annular pistons, are spaced apart from one another in the longitudinal direction of the roll and against the cylindrical outer surface of which the inner surface of the roll sleeve can be positioned.
Whereas, in the known solutions, it is usual for the borders to be widened, it is possible for the proposed solution to narrow the barrel in the central region. The proposed solution is suitable for being adjusted under load because there is no widening of the roll sleeve, as with the above-described prior art. By virtue of the annular pistons, which bear the supporting bearings, being displaced axially, there is a change in the position of these pistons in relation to the length of the roll, this resulting, depending on the adjustment position and thus the supporting action of the roll sleeve, in a “hard” or a “soft” configuration of the roll. In the simplest conceivable form, the annular pistons with the supporting bearings are each moved into their axial end positions, where they can be fixed, if appropriate, by fixed stops. One end position, in which the annular pistons are positioned in the region of the roll center, produces the “hard” supported roll. The end position in which the annular pistons are positioned in the vicinity of the border region of the roll: produces the “soft” roll. The annular pistons are moved by means of pressure oil which is introduced through the roll core via rotary connections.
A further embodiment of the invention provides that the annular pistons are formed in the manner of telescopic pistons and bear axially displaceable annular pistons which can be controlled independently and on which further spaced-apart annular supporting bearings are formed. It is possible to change the spacings of the supporting bearings in relation to the supporting bearings arranged on other annular pistons, and the position of said supporting bearings in relation to the longitudinal extent of the roll, by displacement of the annular pistons.
In this way, for example with a hard-adjusted roll for a strip width of 2000 mm, the roll sleeve is supported on the roll core via ten or twelve supporting bearings which are set such that the approximately identical spacing of the supporting bearings in the center between two supports is approximately 110 mm. With corresponding dimensioning of the roll sleeve, it is possible, with a load of 4000 t, to achieve a deflection of 2 mm in the barrel center.
In the “soft” position of the same roll, a supporting distance of approximately 1350 mm is set between the supporting bearings. With corresponding dimensioning, the deflection in the barrel center of the roll, with a load of 4000 t, is approximately 6 mm. It can be seen from this example that the different deflections of the roll with the same load and different positions of the annular pistons make it possible to set at least two different crowns, it being possible for the precise regulation to take place via the working-roll bending used hitherto. Widening the invention by way of independently controllable annular pistons which can be displaced axially on the first-mentioned annular pistons allows any desired number of intermediate positions in which it is also possible to set the annular pistons, and thus the supporting bearings, non-symmetrically in relation to the roll center. For this purpose, use is made of means for regulating the quantity of oil supplied, which make it possible for the annular pistons to advance up to any desired intermediate position.
FEM tests have shown that the rolling-force distribution over the working roll, in simplified terms, corresponds to a line load, but
Figge Dieter
Quitmann Uwe
Schwerdt Wilhelm
Cohen, Pontain, Lieberman & Pavane
Larson Lowell A.
SMS Demag AG
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