Metal deforming – By use of roller or roller-like tool-element – With carrier for roller-couple or tool-couple
Reexamination Certificate
1999-11-30
2001-06-12
Butler, Rodney A. (Department: 3725)
Metal deforming
By use of roller or roller-like tool-element
With carrier for roller-couple or tool-couple
Reexamination Certificate
active
06244090
ABSTRACT:
Rolling band-type metal products takes normally place in a roll mill train, wherein each mill is composed of a stand comprising two supporting stanchions, spread apart from one another and linked by crossbeams, between which is installed a set of superimposed rolls with parallel axes and located more or less in the same clamping plane, more or less perpendicular to the running direction of the product.
Roll mills of different types can be realised. Generally, in a roll mill, the product to be rolled runs between two working rolls that delineate the rolling plane; these rolls are generally of small diameter with respect to the loads to which they will be subjected, they rest therefore generally on at least two backup rolls between which the rolling load is applied.
The so-called ‘quarto’-type roll mills comprise therefore four superimposed rolls, respectively two working rolls connected to respectively two back-up rolls of larger diameter.
In ‘sexto’ roll mills, intermediate rolls are interposed between each working roll and the corresponding back-up roll.
Other mill types, comprising more or fewer rolls are known and used in the industry.
The rolls bear upon one another along more or less parallel bearing lines, and directed along a generatrix whose profile, normally rectilinear, depends on the loads exerted and on the resistance exhibited by the rolls. Generally, the clamping load is applied by screws or jacks interposed between the stand and the ends of the shaft of the upper back-up roll, whereas the lower back-up roll bearing directly upon the stand with its ends. Apart from the latter roll, the other rolls must therefore be able to move with respect to the stand and, to this end, they are carried by supporting members, mounted to slide vertically in two windows provided in both stanchions of the stand.
Clamping means, such as screws or jacks, bearing upon the stand, exert a vertical load in order to tighten the rolls in order to roll the product running between the working rolls.
Generally, each roll is mounted to rotate round its axis, on bearings carried by two supporting members, called chocks, and these chocks are mounted to slide parallel to the clamping plane running through the axes of the working rolls, each chock sliding between two plane guiding faces provided respectively on either side of the clamping plane on both sides of the corresponding window of the stand.
The clamping loads are applied between both ends of the back-up rolls. Since the rolled product, with variable width, does not cover the length of the working rolls totally, each roll may warp due to the loads applied.
The result is a variation in thickness of the running space of the band between the working rolls, whereas the edges of the band can be thinner than the central portion.
For some time, efforts have been directed to correcting these defects in thickness on the profile across the rolled product and various means have been used for this purpose.
For example, it has been suggested to compensate for the deformation of the rolls due to the rolling effort by vaulting their surfaces, thereby machining the surfaces to a particular profile. This solution exhibits the shortcoming of not perfectly suiting all the widths of the rolled product. Moreover, the defect in thickness on the profile across the rolled product is complex since it is the result of all the deformations of all the rolls that are of different diameters and of the deformation of all the constitutive parts of the roll stand under the loads applied.
Therefore, it has also been suggested to perform adjustable correction continuously, by bending the working rolls, which are generally of small diameters, while applying controlled flexion loads to both ends of their shafts.
To this end, hydraulic jacks are usually placed on either side of each chock and they bear on a fixed portion in one direction and on protruding lateral sides on the other, thereby forming bearing lugs for the chock.
This arrangement therefore enables producing so-called negative bending, by tightening the chocks of both working rolls, in order to compensate for excessive thickness of the edges of the product or so-called positive bending, by spreading the chocks of both working rolls apart in order to compensate for excessive thickness of the central portion of the product.
In order to reduce the number of jacks, it may be contemplated to use double-action jacks producing positive bending in one direction and negative bending in the other. Then, the stems of the jacks must be connected to the chock in both directions. However, the rolls must be replaced periodically and, to this end, are removed from the stand by moving parallel to their axis while sliding or running on rails. The bending jacks must then be removed at the same time as the chocks or the bending load must be applied to intermediate parts upon which the chocks are bearing with a possibility of axial sliding.
Such an arrangement is rather complicated and, generally, single-action jacks are used preferably, whereas the jacks act in opposite directions on the chocks, respectively for positive bending and for negative bending of the roll. To do so, the positive bending jacks can be simply interposed between the chocks of both working rolls, respectively the upper and the lower rolls, while bearing upon the chocks in opposite directions. However, the load exerted on both rolls, on either side of the rolling plane, can only be symmetrical.
It is therefore preferable to use jacks connected to each chock in order to apply individually specific bending loads to each working roll. However, such an arrangement increases, obviously, the number of the jacks and makes their installation more complicated, in particular for positive bending jacks which are placed between the chocks.
Moreover, since the diameter of the working rolls is rather small, their chocks are smaller still than those of the back-up rolls. It thus seems natural that, in order to adjust the levels of the working chocks, to bear upon the backup rolls, whereas the latter can be prolonged by guiding legs between which the working chocks are mounted to slide.
However, the level of the back-up chocks can vary and, to ensure accurate control of the profile of the working rolls, it is preferable that the bending jacks bear directly upon the stand.
To this effect, it is more advantageous to install the bending jacks in two supporting parts, provided respectively on both sides of each window of the stand at the level of the working rolls and inside which are fitted the hydraulic systems, whereas these supporting parts will often be called, for this reason, ‘hydraulic blocks.’
Usually, the positive and negative bending jacks are located in bearing sections extending and protruding inside the window and fitted, at their ends, with lateral faces for guiding the chock, whereas the lugs of the faces extend to the outside between the said protruding sections.
Therefore, each supporting block usually comprises three protruding sections, respectively a central section placed at the level of the rolling plane, in which are located the positive bending jacks of both chocks and two upper and lower sections placed, respectively, above and beneath the rolling plane and in which are located the negative bending jacks of both jacks, respectively upper and lower.
As can be seen on
FIG. 1
which shows, for exemplification purposes, an arrangement of such type, each supporting block, therefore exhibits an E-shape comprising, on either side of the central protruding section, two recesses into which extend, respectively, the lugs of both chocks. These recesses must therefore be of sufficient height to enable varying the relative levels of the rolls.
However, the rolls of a mill and, in particular, the working rolls, wear rather rapidly and their diameter may therefore vary, as well as obviously, the relative positions of the rolls applied one over the other.
FIG. 1
shows, for example, the relative positions of the new and worn rolls, respectively on the right and on the le
Arent Fox Kintner & Plotkin & Kahn, PLLC
Butler Rodney A.
Via Clecim
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