GB2094687A - Rolling mill rolls - Google Patents

Abstract

A composite rolling mill roll, e.g. a backing roll, consists of an arbor (13) on which a rotary sleeve (15) is supported by a bearing (16). The arbor (13) may have on its surface a raised land which varies in axial length around the arbor. By adjusting the angular position of the arbor the effective profile of the sleeve (15) is varied. Alternatively, the roll profile can be varied hydrostatically by forcing fluid in the space between the arbor and a stationary sleeve arranged within the bearing. <IMAGE>

Description

SPECIFICATION Roll This invention relates to rolling mill rolls, and particularly, but not exclusively, to back-up rolls for rolling mills.

Back-up rolls, like other rolls, are usually single castings with integral roll necks by which the rolls are supported in bearing in the roll housings.

Hydraulic oil film bearings or rolling element bearings are employed as the roll neck bearings.

In operation, the back-up rolls of a rolling mill, even when of massive construction, tend to bow under the action of the rolling load, with the resulting transverse non-uniformity of thickness of the material being rolled. Many expedients have been suggested and tried to alleviate that problem, including cambering the rolls barrels, thermal cambering, supporting the rolls by castors spaced along the barrel, and applying bending moments to the roll ends. All such expedients have however suffered from various objections, either because of the resulting complexity and expense or because of inability to deal properly with changes in the rolling conditions. In particular, none has adequately provided an inexpensive means for varying the camber of the roll along the barrel to improve the profile of the material being rolled.

In our British patent application No. 8105099, we have described a roll, and particularly a rolling mill back-up roll, formed by an arbor, which is supported at its ends, a sleeve or sequence of sleeves which closely surround the arbor over the effective roll barrel length, and means for supplying lubricant under pressure between the arbor and the sleeve or sleeves so that, in use, the sleeve or sequence of sleeves is carried on a hydrodynamic or hydrostatic liquid film. In that application, the thickness of the oil film can be varied along the barrel length to vary the roll camber to counteract bending ofthe roll in use and/or to compensate for shape irregularities in the material being rolled.

In the present invention the effective profile of the roll is adjustable through bearing means on which the sleeve or sequence of sleeves is supplied on the arbor.

Thus, in accordance with one aspect of the present invention, a rolling mill roll comprises an arbor; a sleeve or sequence of sleeves rotatably supported on the arbor by bearing means extending over substantially the entire barrel length of the sleeve or sequence of sleeves, and adjustable means for varying the effective profile of the sleeve or sequence of sleeves through the bearing means. The bearing means may comprise rolling element bearings, hydrodynamic bearings, hydrostatic bearings, or hydrodynamic/hydrostatic bearings.

In one preferred form of the invention, the arbor is normally stationary, but is rotatable for adjustment, and has a central area which is raised above the remaining surface and which varies in axial length round a part at least of the arbor periphery. When the roll is mounted in a rolling mill, the profile of the roll facing the work can be adjusted simply by turning the arbor about its axis. In this way, the distribution of roll force across the width of the strip can be modulated to provide for optimum gauge and shape.

In another form of the invention, a stationary sleeve is interposed between the arbor and the bearing means, and means are provided for injecting liquid under pressure between the arbor and that stationary sleeve, again to vary the profile and stiffness of the roll along its barrel length.

The invention will be more readily understood by way of example from the following description of rolls in accordance therewith, reference being made to the accompanying drawing, in which Figure 1 is a side view of an arbor for a back-up roll, Figure 2 shows in axial section a roll employing the arbor of Figure 1, and Figure 3 shows a second form of roll in axial section.

The rolls illustrated in the drawing are back-up rolls of a rolling mill, and each is shown in Figures 2 and 3 as the upper back-up roll, in conjunction with its work roll.

The back-up roll 12 in Figures 1 and 2 consists of normally stationary arbor 13 having necks 13A by which the arbor can be journalled in the mill housings (not shown) through bearings 14, enabling the arbor to be turned for adjustment purposes. The arbor 13 carries a sleeve 15 through a roller bearing 16, which extends over almost the entire barrel length of the sleeve 15. The sleeve 15 engages an upper work roll 17, while the work, illustrated as a strip 18, is reduced between work roll 17 and the lower work roll (not shown).

The surface of the arbor 13 has a central area which is elevated above the remainder of the surface, and the axial length of which varies smoothly round the arbor. In Figure 1, the edges of the central raised area, or land, are indicated by the dotted lines 20; as will be seen in that Figure, the raised area varies in axial length between almost the entire barrel length at 21 to a small central length 22.

The elevation of the land is shown exaggerated in Figure 1 and in practice is of the order of 1 mm, being hardly visible to the naked eye.

By turning the arbor 13 about its axis, the length of the land facing the work roll 17, and hence the profile of the sleeve 15 in contact with the work roll, can be adjusted. In that way, the distribution of roll force across the width of the strip 18 may be modulated to provide optimum gauge and shape. The adjustable length land further enables varying widths of strip to be accommodated with the same work roll, without the need to modify the crown on the work roll for each width. In other words, by angular adjustment of the arbor, the mill can be made to have a higher rigidity over the length of the work 18, relative to the remaining axial length of the rolls.

The back-up roll 30 shown in Figure 3 again has an arbor-mounted sleeve 15 supported on roller bearings 16. In this case, however, a stationary arbor 31 is employed and an inner, stationary, sleeve 32 is interposed between the arbor 31 and the bearing 16, the sleeve 15 rotating on the inner sleeve 32 via the bearings 16.

In Figure 3, the arbor is constituted jointly by the arbor 31 and the sleeve 32 and means are provided for varying the stiffness of that composite arbor across its width. Those means are constituted by passages in the arbor for supplying liquid under pressure to and from the interface between arbor 31 and inner sleeve 32. Thus, arbor 31 is shown as having an axial passage 33 leading from one end of the arbor to radial ducts 34 positioned at the centre of the arbor, and opening to the interface between arbor 31 and sleeve 32. Similar radial passages 35 adjacent the ends of sleeve 32 connect to discharge passages 36 in arbor 31.

The supply of hydraulic fluid to the arbor 31 results in a symmetrical section of the inner sleeve 32 being disconnected from the arbor 31, that section having a length which is dependent on the pressure of the fluid supplied. In that way, the rigidity of the roll over its central portion may be adjusted according to conditions, again to provide optimum gauge and shape. The variation of rigidity is achieved with the minimum disturbance to the outer profile of the inner sleeve 32, thereby promoting even loading of the roller elements constituting the bearing 16.

While the outer sleeve 15 in Figures 2 and 3 have been illustrated as a single integral sleeve, it may if desired be a sequence of contiguous sleeves. Further, the roller bearings 16 may be replaced by hydrodynamic bearings, hydrostatic bearings, or hydrodyna mic/hyd rostatic bearings.

Claims (7)

1. A rolling mill roll comprising an arbor; a sleeve or sequence of sleeves rotatably supported on the arbor by bearing means extend over substan tally the entire barrel length of the sleeve or sequence of sleeves, and adjustable means for varying the effective profile of the sleeve orsequ- ence of sleeves through the bearing means.

2. A rolling mill roll according to claim 1, in which the adjustment means comprise means for rotating the normally stationary arbor about the axis, the surface of the arbor having parts which are raised above the remainder and which vary in axial length around a part at least of the arbor periphery, whereby the profile of the roll facing the work is adjustable by varying the axial position of the arbor.

3. A rolling mill roll according to claim 2, in which the arbor has a raised central area which varies in axial length round a part at least of the arbor periphery.

4. A rolling mill roll according to claim 1, in which a stationary sleeve is interposed between the arbor and the bearing means, and the adjustable means comprises means for injecting liquid under pressure between the arbor and the stationary sleeve to vary the profile of the stationary sleeve.

5. A rolling mill roll according to any one of the preceding claims, in which the bearing means comprise rolling element bearings.

6. A rolling mill roll according to any one of claims 1 to 4, in which the bearing means is a hydrodynamic bearing.

7. A rolling mill roll substantially as herein described with reference to the accompanying drawings.