GB2338198A - Mill Housings - Google Patents

Abstract

A mill frame having a pair of vertical mill posts 10' and 11' joined at their ends by horizontal posts 12' and 13'. In the present frame, the posts are curved outwardly at their ends (e.g. 30) where they join the beams. A substantial portion of the bending resulting from the bending forces in the beams thereby occurs in the curved end regions of the posts. The beams are narrowed towards their ends.

Description

2338198 Mill Housings s The present invention relates to mill housings,

and more specifically to mill frames.

A rolling mill for steel and similar materials consists essentially of a pair of rolls (work rolls) between which the strip of material to be rolled is passed.

io The two work rolls are pressed together to squeeze the strip being rolled and so reduce its thickness. The compression force may be applied directly to these two rolls via their axles, or there may be backing rolls mounted outside the primary rolls to apply the required force to them. The various rolls are typically arranged in a vertical column, with their axes horizontal.

The rolls are mounted in a mill housing, which comprises a pair of vertical mill frames. Each mill frame is a single integral structure consisting broadly of a pair of vertical posts joined at the top and bottom by horizontal beams, so forming a vertical window. The axles of the various rolls pass through this window, and are mounted therein by means of suitable bearings. Means for exerting the required forces on the axles, and hence on the rolls, are also provided at or ad acent to the mill frames.

Ii The compression forces on the rolls are applied between the axles of the rolls and the ends of the windows of the mill frames. More specifically, these forces are applied at substantially the middles of the beams of the mill frames. This results in distortion of the mill frames; with the beam portions of the frames tending to bow outwardly. The resulting moments at the ends of the 1 mill frame beams are transmitted, at the corners of the mill frames, to the posts, which therefore tend to bow inwardly.

is This distortion of the mill frames is undesirable, as it changes the geometry of the mill. Further, the mountings of the mill rolls in the windows of the mill frames have to be able to move vertically. The changing widths of the windows in the mill frames mean that the mountings have to be designed to move at the minimum window width, and the mountings will therefore have undesirable horizontal play when the window is not at its greatest io constriction.

The bending of the beams and the resulting change in width of the mill window with load can be reduced by using thicker beams andlor thicker posts but this makes the frames heavier and more expensive.

The object of the present invention is to substantially reduce or eliminate the change in width of the mill window with load whilst keeping the housing weight to a minimum.

According to its main feature, the present invention provides a mill frame having a pair of vertical mill posts having ends joined by horizontal beams, wherein the posts are curved outwardly at their ends where they join the beams, such that a substantial portion of the bending resulting from the bending moments in the beams is counter-acted by bending moments of the opposite sense in the mill post ends. Preferably the beams are narrowed towards their ends.

2 1- A mill frame in accordance with the invention will now be described, by way of example, with reference to the drawings, in which:

Fig. 1 is a side view of a known mill frame; Fig. 2 is a side view of one embodiment of the mill frame of the invention; Figs. 3A and 3B are diagrams illustrating the mill frame window of the known mill frame in the unstressed and stressed conditions; and Figs. 4A and 4B are diagrams illustrating the mill frame window of the invention in the unstressed and stressed conditions.

Fig. 1 shows a known mill frame consisting of two vertical posts 10 and 11 joined by as top beam 12 and a bottom beam 13. The posts 10 and 11 have formed on them lugs 14 for mounting the mill frame and lugs 15 and 16 on which roll bearings and other ancillary devices may be mounted; these lugs are not relevant for present purposes. The posts and arms 10- 13 define a substantially rectangular mill frame window 17 in which the bearings (not shown) of the various mill rolls are located.

Fig. 3A shows diagrammatically the window 17 of this mill frame in the unstressed condition; the window is essentially a rectangle in this condition. Fig. 3B shows the same window in the stressed condition. The primary force is against the centres of the inner sides of the beams 12 and 13, as indicated by the arrow 20 (the forces at the bottom of the window are similar). The upper beam is attached to (and in fact integral with) the posts 10 and 11 at its ends, so this force 20 combined with the reaction forces in the posts prodtices 3 a bowing outwards of the beam and bending moments 21 in the beam as shown. These bending moments are transmitted past the inner corners 22 of the window 17 to the upper ends of the posts 10 and 11 and produce corresponding rotations 23 at the tops of the posts. The result of these forces s (and the corresponding forces at the bottom of the frame) is a bowing inwards of the window 17, as indicated by the arrows 24.

In practice, of course, known mill frames may be more elaborate than the simple form shown here, with, for example, various radii, chamfers, and lo undercuts at the outer corners of the frame where the horizontal beams join the vertical posts, and at the inner corners of the window. However, none of these variations and elaborations significantly affects the response of the frame to applied forces as just discussed.

i s Fig. 2 shows one embodiment of the mill frame of the invention; parts corresponding to the mill frame of Fig. 1 are shown with corresponding references but distinguished by primes. There are two major differences from the known mill frame of Fig. 1. First, the posts 10' and 11' are curved outwardly at their ends where they meet, as shown at the upper end 30 of post 1C. This results in an outward bulge 31 at the top corner of the window 17' (and, of course, corresponding bulges at the other corners). As shown, the bulge 31 is preferably rounded and preferably extends slightly above the bottom edge line of the main portion of the beam 12' as well as beyond the inside vertical edge line. of the main portion of the post 1C. Second, the upper edge of the beam 12' is curved, so that this beam is thicker at its centre, as indicated at 32, than it is at its ends, as indicated at 33.

4 Fig. 4A shows diagrammatically the window 17' of this mill frame in the unstressed condition; in this condition the window is essentially a rectangle with bulges 31 (here shown diagrammatically) at its corners. Fig. 4B shows the same window in the stressed condition. The primary force is against the centres of the inner sides of the beams 12' and 13% as indicated by the arrows 20'. The upper beam is held at its ends, so this force 20' combined with the reaction forces in the posts produces a bowing upwards of the beam and bending moments 2 1' in the beam as shown (the forces at the bottom of the window are similar). These bending moments are transmitted past the inner io corner bulges 31 of the window 17 into the upper ends of the posts 10' and 1 F. However, the offset of the connections between the beams and the posts combines with the reaction forces in the posts to produce bending moments in the ends of the posts with the opposite sense to the bending moments in the beams. As a result, there is very little rotation of the posts in the regions 36, and the width of the window, indicated at 37% undergoes very little change.

Claims (3)

Claims

1 A mill frame having a pair of vertical mill posts having ends which are joined to horizontal beams, wherein the posts are curved outwardly at their ends where they join the beams, such that the bending of the curved ends of the posts counteracts the bending of the horizontal beams in such a way as to minimise the variation in the width of the mill window with load.

2 A mill frame according to claim 1 wherein the beams are narrowed towards their ends.

3 Any feature of novelty or combination thereof within the meaning of 15 Article 5 of the International Convention (Paris Convention).

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