GB2038218A - Roll gap adjustment system for cluster mills - Google Patents

Abstract

A cluster mill is provided with backing system including a backing shaft 6 supported on spaced saddles 18 and adjustable therein by means of racks (4) driving pinions (5). The racks (4) are each connected to a respective eccentric (12) on a shaft (11), itself driven by means of a rack (9) and pinion (10). The eccentrics (12) have differing eccentricities so as to vary the crowing effect in a predetermined manner as the shaft (11) is rotated so as to achieve positive, negative or zero crowning. The shaft (11) and associated parts are mounted in a frame (19) tiltable about a central axis parallel to the pass line so as to achieve a tapered roll gap. The crown and taper adjustment mechanisms can be operated separately or simultaneously. <IMAGE>

Description

SPECIFICATION Roll gap adjustment system for cluster mills This invention relates to cold rolling cluster mills of the general type shown in Sendzimir United States Patent Nos. 2,169,711; 2,187,250; 2,194,212 and 2,776,586.

An object of this invention is to provide improvements in the construction of such mills, with the objective of increasing the ability of these mills to roll strip which has a tapered or crowned profile, or a combination of both.

Tapered or wedge shaped strip frequently has to be rolled on cold mills. Such strip is produced when crowned strip is slit into two or more narrower widths. Also, the crowned strip produced by hot strip mills does not necessarily have a symmetrical crown, as such deficiencies as errors in screwdown setting, effect of drive spindle weight, and so on, can cause an imbalance on the hot mill.

In the specification of United States Patent No.

2,194,212 means of adjusting the contour of the rolls (and hence of the roll gap) are disclosed. Such means are incorporated in most modern Sendzimir cluster mills and embody individual drives (so-called crown adjustment drives) to each shaft support (saddle) on at least one backing shaft to adjust the position of the shaft at the saddle in a sense to increase or decrease the roll gap in line with the saddle. As there may be from four to eight saddles, or even more, depending on the width of the mill, it is possible to achieve a very fine control of the profile of the roll gap.

Clearly, it is theoretically possible by this means to set a roll gap having a tapered profile. However, in practice this is found to be impossible, because the operator needs to adjust from four to eight drives (depending on the number of saddles) simultaneously and all at different speeds.

The present invention aims to provide means to operate and synchronize the rotation of the crown adjustment eccentrics on Sendzimir cluster mills so that the operator can conveniently control the rotation of the eccentrics to produce tapered and/or crowned roll gap profiles. Existing methods (such as that described in United States Patent No. 2,022,040) give synchronized adjustment for crown or for wedge control, but not for both together.

According to a first aspect of the invention, there is provided a cluster mill having upper and lower backing shafts and individual drives on at least one of the backing shafts to vary the position of the shaft in relation to supporting saddles, to adjust the roll gap in line with each saddle, first means for mecha nically synchronizing the drives such that they act togethertoform a symmetrical roll gap profilewhich will be flat when said drives are in a neutral position, convex when they are operated in one direction, and concave when they are operated in the other direc tion, the magnitude of the convexity or concavity being proportional to the synchronized movement of the drives away from their neutral position for which the roll gap is parallel, together with second means for mechanically synchronizing the drives such that they act together to form a roll gap which tapers down from front to back of the mill when operated in one direction, and which tapers down from back to front when operated in the other direction, the magnitude of the taper being proportional to the synchronized movement of the drives away from their neutral position for which the roll gap is parallel, said first and second means being operable separately or simultaneously to obtain any desired combination of taper and crown in the roll gap.

According to a second aspect of the invention, there is provided a cluster mill in which at least one shaft is adjusted in the saddles by rack and pinion drives and in which the first means includes a first synchronized drive means consisting of a motor, jack, rack and pinion which are used to rotate a shaft, said shaft being connected to some or all of said rack and pinion drives, by means of eccentrics and links, whereby synchronously to vary the roll gap in line with each saddle away from the position in which the roll gap is parallel, to positions in which the roll gap is profiled, and in which the said second means includes a second synchronized drive means consisting of a motor, jack and a pivoting assembly, said assembly being connected to all of said rack and pinion drives by means of said links, whereby synchronously to vary the roll gap away from the position in which the roll gap is parallel, to a position in which the roll gap is tapered, said first and second synchronized drive means being operable separately or simultaneously to obtain any desired combination of taper and crown in the roll gap.

The invention will be further described, with reference to the accompanying drawings: Figure lisa longitudinal sectional elevation of a profile adjusting system incorporating an embodiment of the present invention.

Figure 2 is a transverse sectional elevation taken substantially along line il-ll of Figure 1 showing the relation between the profile adjusting system and the rolling mill; Figure 3 is a transverse sectional view taken substantially along line Ill-Ill of Figure 1 showing a mechanism for adjusting the crown profile by the profile adjusting system; Figure 4 is a plan section of the profile adjusting system taken substantially along line IV-IV of Figure 2 partially broken away; Figure 5 is a longitudinal elevation partially broken away showing the effect of operating the profile adjusting mechanism to obtain a composite profile of wedge and crown; Figure 6 is an end view taken along line Vl-Vl of Figure 5 shown a mechanism for adjusting the wedge profile by the profile adjusting system; and Figure 7 is an end view partially broken away showing a mechanism for retracting the profile adjusting system enabling backing elements to be inserted and removed from the rolling mill.

The drawings are given by way of example only and are not intended to limit the scope of the invention.

Cold rolling cluster mills ofthe general type described in the above noted patens consist of a pair of work rolls each of which is directly or indirectly supported by a plurality of backing assemblies which are supported by the mill frame. In the case of the mill illustrated, there are no intermediate rolls but it will be understood that in certain types of cluster mill, there will be intermediate rolls between the work roll and the backing assembly. Each backing assembly (see Figures 1 and 2) consists of a plurality of bearings or casters 1 mounted on a normally stationary shaft 6. The shaft 6 is supported at intervals throughout its length by normally stationary saddles 18. The work rolls (or the appropriate intermediate rolls) are supported by the bearings 1 and the saddles are supported by the mill frame.On at least one of the backing assemblies the stationary shaft is eccentrically mounted in each saddle 18 and the shaft can be bent and, or tilted by rotating the eccentrics 20 individually according to the prior art.

Each of the eccentrics is provided with a gear 5 and a rack 4 engaging the gear and the rack is traversed in order to rotate the gear and the eccentric.

In Figure 1 and Figure 2 an embodiment of the subject system is shown mounted on a cluster mill housing 2, shown in partial section. Connecting rods 3 which are the outputs of the system are attached to racks 4 engaging with gears 5. Racks 4 and gears 5 are provided at several positions across the width of the strip being rolled by the mill and it is known practice for vertical movements of the racks 4 to be used to form a profiled roll gap within the mill by rotating the gears 5 whose shafts are eccentrically mounted.

The system of the invention has the function of moving the racks 4 via the connecting rods 3 so as to form the desired roll gap profile in a synchronized manner.

In Figure 1, which shows an embodiment for a system installed on a cluster mill having eight saddles on each backing shaft, a work roll is indicated at 37, and the rolled strip appears in transverse section at 21. The left side of Figure 1 represents the back of the mill and the right side represents the front, which is where the operator stands.

The corresponding eight connecting rods 3 can be seen projecting below the bottom surface of the assembly. Said rods are guided in bushings 16 so that they can only move in a vertical direction.

The system consists of three main subsystems to perform the three separate functions of (A) synchronized crown adjustment, (B) synchronized wedge adjustment, and (C) raising of the racks 4 to enable backing assemblies to be replaced.

Subsystem (A) includes a frame 19 and a shaft 11, eccentrics 12, gear 10 and all other components mounted in said frame 19, together with a motor7 and a jack 8 driven thereby (shown on Figure 3) and links 14, lower links 15 and connecting rods 3 depending therefrom.

Subsystem (B) consists of a mechanism for tilting subsystem (A), and is shown in Figues 5 and 6.

Subsystem (C) consists of a mechanism for lifting subsystems (A) and (B) together with the racks 4.

The operation of subsystem (A) to produce a crowned roll gap profile in a synchronous manner is asfollows. Motor 7 (as viewed in Figure 3) drives the input shaft of worm jack 8. The output or lifting shaft of said jack is attached to a rack 9 as shown in Figure 3. As said rack is raised and lowered, it causes gear 10 and shaft 11, to which said gear is keyed, to rotate. Shaft 11 is supported in frame 19 by bearings 17.

A set of eight eccentrics 12 is keyed to the shaft 11 (Figure 1). Each of said eccentrics is rotatably mounted within an upper link 14, relative rotation between said eccentric and said link 14 being provided for by needle rollers 13 interposed in the annular space between the outer cylindrical surface of said eccentric and the bore of said link 14. A lower link 15 connects each link 14 with its corresponding connecting rod 3, and allows for limited tilting of link 14 in any direction The rotation of shaft 11 causes the eight connecting rods 3 to raise or to lower, depending on the direction of motion, and these movements act via the gear 5 of eccentrics 20 on the shafts 6 to bend the latter and produce a resultant profile of the roll gap, the form of the profile depending on the eccentricity and phase relationship of the eight eccentrics 12.

Each of the eccentrics 12 has a maximum radius and a minimum radius, as measured from the centre of the shaft to the outer surface. These radii are 180" apart. At right angles to these radii, the radii are between maximum and minimum, and are referred to herein as average radii.

Preferably all the eccentrics are mounted in phase.

This means that the average radii of all the eccentrics are in alignment. However, the eccentricities of the individual eccentrics are varied. If a parabolic profile is desired, the eccentricities of the successive eccentrics 2 would be in the ratio of -3:0: +2: +3: +3: +2:0: -3.

It will be understood that when the shaft 11 is oriented so that the average radii are acting on the connecting rods 3, a straight profile will be produced. As the shaft 11 is rotated in one direction, a crown will be produced; and the further the shaft 11 is rotated, the higherthe crown. Rotation of the shaft 11 in the opposite direction will, in the same way, produce a negative crown.

Operation of subsystem (B) to obtain synchronized motion of rods 3 in order to produce a tapered roll gap profile is as follows (see Figure 5 and Figure 6).

Frame 19 is provided with four points of support. It is pivoted at its centre line on a pair of pivot pins 23 (in line with the centre of the rolling mill) and is also provided with two legs 28 which have pin joints 29 on the same horizontal plane as said pivot pins 23.

Pivot pins 23 and pin joints 29 are mounted on a base plate 24, said base plate being normally clamped to the top of the mill housing by hydraulic cylinders 30 (as shown in Figure 2).

Frame 19 can be tilted about its centre line by varying the length of legs 28. This is achieved by operation of motor 22 driving jacks 25 which are synchronized together by shaft 26 and couplings 27.

If the shaft 11 is oriented so that the average radii are acting on the connecting rods 3, producing a straight profile, and the frame 19 is then tilted, the resulting respective vertical displacements of the connecting rod 3 and racks 4will be in the ratios of -7: -5: -3: -1: +1: +3: +5: +7, which isthe correct relationship to produce a tapered roll gap. If the shaft 11 has been rotated to produce a parabolic roll gap (subsystem A), and the frame 19 is then tilted (subsystem B), there is produced an asymmetrical roll gap as shown in chain lines at the bottom of Figure 5. This is, in effect, a parabola on a tilted axis.

Operation of subsystem (C) in order to raise subsystems (A) and (B) and racks 4to enable backing assemblies to be replaced is carried out as follows (see Figure 2 and Figure 7). The four hydraulic cylinders 30 are of the double rod type, and the lower rods 31 are attached to the mill housing 2 by means of the threaded ends of said rods. Each cylinder body 30 is attached to the base plate 24 by means of a flange 35 and screws 36. During normal operation of the mill, the lower ends of cylinders 30 are pressurized and the upper ends of said cylinders are vented. The cylinders thus act as hydraulic clamps and maintain the complete system tightly mounted on top of the mill housing in a fixed position. In order to raise subsystems (A) and (B) and racks 4, the upper ends of cylinders 30 are pressurized and the lower ends vented.Said cylinders thus act as hydraulic jacks and raise the complete assembly, including base plate 24, clear of the mill housing by a distance determined by the stroke of said cylinders. This action is shown by comparing Figure 2 with Figure 7. In Figure 7 it can be seen that raising the assembly has the effect of withdrawing racks 4 so they disengage completely from gears 5. The backing shaft assemblies on which gears 5 are mounted can then be removed from the mill and replaced with spare assemblies. At this stage racks 4 and gears 5 can be re-engaged by pressurizing the lower ends of hydraulic cylinders 30 and venting the upper ends of said cylinders.The complete assembly will then be lowered until said racks and gears re-engage, and it will continue to lower (rotating gears 5 in the process) until base plate 24 contacts mill housing 2 and becomes clamped thereupon (as shown in Figure 2).

The system shown in the drawings is given by way of example only. Clearly the action of system (A) could be obtained by use of a system of gears rather than eccentrics and the system adopted is purely a matter of convenience.

To help the operator make full and proper use of the system, it is envisaged that indicating devices (remote and/or local) would be provided. These could indicate rotation of motor 7 (crown only) and of motor 22 (wedge only) or of linear motion of connecting rods 3 (crown, wedge and removal position indication). Such methods of indication are well known in the state of the art and need not be considered here.

Various modifications may be made within the scope of the invention. For instance, although the Figures show a so-called six high mill, with one work roll and two body assemblies on each side of the strip, it is also applicable to other cluster mills, particularly the twenty high mill with 1-2-3-4 configurations on each side.

Claims (6)

1. A cluster mill having upper and lower backing shafts and individual drives on at least one ofthe backing shafts to vary the position of the shaft in relation to supporting saddles, to adjust the roll gap in line with each saddle, first means for mechanically synchronizing the drives such that they act together to form a symmetrical roll gap profile which will be flat when said drives are in a neutral position, convex when they are operated in one direction, and concave when they are operated in the other direction, the magnitude of the convexity or concavity being proportional to the synchronized movement of the drives away from their neutral position for which the roll gap is parallel, together with second means for mechanically synchronizing the drives such that they act together to form a roll gap which tapers down from front to back of the mill when operated in one direction, and which tapers down from back to front when operated in the other direction, the magnitude of the taper being proportional to the synchronized movement of the drives away from their neutral position for which the roll gap is parallel, said first and second means being operable separately or simultaneously to obtain any desired combination of taper and crown in the roll gap.

2. A mill as claimed in Claim 1, in which the said at least one shaft is adjusted in the saddles by rack and pinion drives and in which the first means includes a first synchronized drive means consisting of a motor, jack, rack and pinion which are used to rotate a shaft, said shaft being connected to some or all of said rack and pinion drives, by means of eccentrics and links, whereby synchronously to vary the roll gap in line with each saddle away from the position in which the roll gap is parallel, to positions in which the roll gap is profiled, and in which the said second means includes a second synchronized drive means consisting of a motor, jack and a pivoting assembly, said assembly being connected to all of said rack and pinion drives by means of said links, whereby synchronously to vary the roll gap away from the position in which the roll gap is parallel, to a position in which the roll gap is tapered, said first and second synchronized drive means being operable separately or simultaneously to obtain any desired combination of taper and crown in the roll gap.

3. A cluster mill having upper and lower backing shafts and a number of rack and gear drives associated with at least one of the backing shafts to vary the position of the shaft-supporting saddles to adjust the roll gap in line with each saddle, a drive system consisting of a number of eccentrics being fixed in phase on a common shaft, with the several eccentrics having different eccentricities, each eccentric being linked to one of said racks by means of a connecting link, and means for rotating said shaft in either direction from a neutral position whereby to produce a parallel roll gap in said neutral position, a positive crown roll gap in one direction, or a negative crown roll gap in the other direction.

4. A cluster mill as claimed in Claim 3, wherein a frame containing said shaft and eccentrics is mounted for tilting movement in either direction from a neutral parallel position, whereby if said eccentrics are in their neutral position the roll gap may be made tapering from front to rear of the mill by tilting in one direction, and from rear to front of the mill by tilting in the other direction, and whereby if said eccentrics are oriented to produce a positive or negative crown roll gap, the axis of said crown may be shifted angularly.

5. A cluster mill as claimed in Claim 4, wherein said frame is mounted on a base plate, and means are provided to clamp said base plate to the mill housing, and to raise said base plate from said mill housing, whereby upon raising said plate from the mill housing, the racks are withdrawn from said gears to permit replacement of the backing shaft assemblies.

6. A cluster mill substantially as herein described with reference to the accompanying drawings.