Rolling Mill Stand

This invention relates to a rolling mill stand, for rolling metal in elongate form, and is particularly, but not exclusively, concerned with a rod mill stand for use in the continuous rolling of rod.

The invention is applicable to a rod mill stand as described in the provisional specification of patent application No. 47037/75 and provides means for enabling the work rolls to be replaced easily and speedily. The present invention is however applicable to other forms of rolling mill stand.

Many expedients have been proposed for facilitating roll change in rolling mills, and particularly in strip mills. All those expedients have entailed the removal of a worn roll from the stand before a new, substitute, roll can be introduced. The labour of physically removing the worn roll from the stand and introducing the substitute roll is time-consuming and involves appreciable down-time of the mill.

According to the present invention, a rolling mill stand comprises a stand housing, a pair of roll housings carried by the stand housing and located on opposite sides of the stand pass line, each mounting having at least two spaced fitments each for supporting a roll assembly and being movable to bring a roll assembly supported in any fitment into an operative rolling position at the pass line, drive means, and coupling means for coupling the drive means with roll assemblies at their operative rolling positions. With such an arrangement, two or more roll assemblies can be carried in a mounting at any one time, one roll being in the operative rolling position and another being in an inoperative, or waiting, position. For roll change, the substitute roll assembly may be brought immediately into the operative position by movement of the mounting, without the need first to remove the worn roll from the mounting and from the stand. The time consumed in a roll change is accordingly much reduced. The worn roll assembly may be left in the stand until a convenient time for its removal.

Each mounting is preferably rotatable and may have fitments for four roll assemblies; in that case, removal of roll assemblies from the stand and substitution of new roll assemblies need take place only when all four assemblies of each housing have been used.

Particularly when the stand is a rod mill stand each roll assembly may comprise a work roll, bearings for the work rolls, and a carrier which supports the bearings and which is detachably securable to any fitment.

Preferably, each mounting is additionally movable parallel to the operative roll axis to enable a roll assembly in operative position to be engaged and disengaged from a roll drive. Thus, each mounting may be rotationally carried on a shaft disposed parallel to the operational roll axis, so that, by rotation of the mounting on the shaft, any roll assembly carried by the mounting may be brought into the operative position. In that case, the mounting may be axially movable on its shaft in order to engage and disengage the operative roll assembly with the roll drive. The drive of the mill may include, for each mounting, a coupling sleeve, with which a roll in operative position may be engaged with a drive shaft.

The invention will be more readily understood by way of example from the following description of a rod mill stand, reference being made to the accompanying drawings, in which:

FIGS. 1, 2 and 3 are respectively a half-sectional front elevation, a half-sectional end view and a half-sectional plan view of the rolling mill stand,

FIG. 1A is a view of a roll shaft of FIG. 1, but on enlarged scale,

FIGS. 4 and 5 are respectively a plan view and a side view of an arrangement for transporting roll cartridges into and out of the stand,

FIGS. 6 and 7 are respectively a side view and an end view of a mounting for the stand, and

FIG. 8 illustrates the drive to the stand.

Apart from the roll change mechanism, the roll stand shown in the accompanying drawings is generally similar to that described in the provisional specification of application No. 47037/75, to which reference should be made for details of the roll drive. The roll mounting arrangements on the two sides of the passline are similar to one another, and therefore only the mounting above the passline will be described in detail.

Journalled in the stand housing are two eccentric shafts 12 and 13, each of which carries one of the rolls, and the bearings 14 of the drive shaft 15 of that roll. Rotation of the shaft 12, or 13 results in adjustment of the roll gap, by virtue of the eccentric mounting of the shaft, and as explained in the earilier application.

Each of the shafts 12, 13 supports a rotational mounting which, in the example shown, can carry up to four work roll cartridges. That mounting comprises a square-section block 16 having a central bore through which the shaft 12 passes. The block 16 is secured at one end to a ring 17, which also surrounds the shaft 12 and which has four circular openings 18 at 90.degree. intervals. Wear sleeves 20, 21 are interposed between the block 16 and ring 18, on the one hand, and the shaft 12, to enable the block 16 to slide axially on the shaft. The four faces of the block 16 are formed with rebates 22 for the securement of the roll cartridges.

One of the roll cartridges is shown in FIG. 1 in outline at 23, while a second is shown in cross section at 24. As there shown, each cartridge consists of a bearing carrier 25 which, with associated shells 26, supports spaced bearings 27 for a roll shaft 28. As shown in FIG. 1, the roll barrel is formed as a sleeve 30 secured on the roll shaft, but alternatively the roll barrel may be formed integrally with the roll shaft. The right-hand end of the roll shaft 28 carries a sleeve gear 31, which engages with the internal splines of a rotary sleeve 32, the splines which are also engaged by a gear sleeve 33 on the end of the drive shaft 15.

The bearing carrier 25 is formed with a dove-tail 35 adapted to engage at one end with the rebate 22 of block 16, and at the other end with a correspondingly shaped keeper plate secured to block 16. Each roll cartridge 23, 25 carries two pairs of wheels 36, the function of which will be explained later.

When the roll mounting is locked in the position shown in FIG. 1, with roll cartridge 24 in operative position with its roll shaft 28 aligned with and engaging the splined sleeve 32, the mill can be operated, the work rolls 30 being driven by the drive shafts 15. The axial position of the roll 30 can be adjusted, as to change the rolling groove, by adjusting the roll mounting 16, 17 axially on shaft 12, the splined sleeve 32 enabling the axial position of shaft 28 to be adjusted without affecting the drive.

When it is desired to change a roll, hydraulic jacks, one of which is shown at 40 is operated to urge the roll mounting 16, 17 axially to the left as viewed in FIG. 1, until the gear sleeve 31 clears the splined sleeve 32. The roll mounting can then be rotated about shaft 12, to take the worn roll 24 out of the operative position and to bring, in its place, a new roll cartridge carried in any of the other three fitments of the roll mounting into that operative position. When the roll mounting has been locked in its new position, it is moved axially to the right to bring the gear sleeve 31 of the new cartridge into operative engagement with the splined sleeve 32. The stand can then be brought immediately into operation.

During the operation of the stand with the new roll, the worn roll in the diametrically opposite position, i.e. that of cartridge 23, can be withdrawn from the stand housing and, if required, replaced by a new cartridge for subsequent use. To facilitate transfer of roll cartridges from and to the stand housing, the rig shown in FIGS. 4 and 5 may be employed. That rig consists of a framework 45 which supports, at the same level as the cartridge 23 in the mill five pairs of rails 46, on any pair of which the wheels 36 of a cartridge can roll. For the removal of a cartridge 23A at the lowermost position of the lower roll mounting, i.e. the position diametrically opposite the operative position of the lower roll, there are similarly five pairs of rails 47 disposed at the same level as the cartridge 23A; each pair of rails passes under one of the pairs of rails 46 and to a location 48 to the left of the rails 46.

A top roll carriage 50 and a bottom roll carriage 51 are carried by wheels 52 on rails 53, 54 respectively which extend horizontally at right angles to the rails 46, 47 and which themselves carry pairs of rails at the same level and spacing as the rails 46, 47 respectively. Lastly, there are two pairs of removable guide rails 55 which extend from the framework 45 and enter the roll stand at the levels of the cartridges 23, 23A.

A number of replacement roll cartridges are supported on the rails 46, 47 being loaded on to those rails by crane. The maximum number of cartridges at each level is, in the example shown in the drawing, four, one pair of rails in each level being left for reception of a used cartridge from the stand. At roll change, and assuming that cartridge 23 is to be replaced, the upper guide rails 55 are placed in position, so that they engage the wheels 36 of cartridge 23, cartridge 23 is released from the stand and is moved over rails 55 on to the aligned carriage 50. Carriage 50, carrying the cartridge 23 is then moved on its rails 53, until it is aligned with the unoccupied pair of rails 46. The cartridge 23 is transferred from the carriage 50 to that set of rails for subsequent removal to the roll shop by crane. Next, carriage 50 is moved into alignment with one of the replacement cartridges on rails 46, that cartridge is transferred to the carriage which is then moved to align with rails 55, and the replacement cartridge is moved into the mill stand and locked to the block 16. Rails 55 are removed, as turning of the block 16 about shaft cannot be effected with the rails in position. A cartridge 23A in the lower roll mounting can be similarly moved into a vacant bay provided by one of the pairs of rails 47 and a replacement cartridge introduced into the stand.

FIGS. 1 to 3 also show the roller entry guides for the stand. As there shown, the stand housing has a vertical shaft 56 disposed at the entry side of the stand, but displaced from the passline. Shaft 56 carries two arms 57 and 58, each of which can turn about shaft 56, as well as moving axially on the shaft. The lower arm 58 rests on a platform 60, which surrounds the shaft 56 and which can be moved axially of the shaft by a piston and cylinder 61 in order to bring either of the arms 57, 58 into operative position. The free end of each arm 57, 58 carries a roller entry guide 62, which can be moved either into an operative position at the roll gap, or an inoperative position outside the stand housing; the roller guide 62 carried by arm 57 is shown in the operative position, while that of arm 58 is shown in the operative position. As soon as a guide 62 becomes worn, it can be removed from the passline simply by turning its arm about shaft 56. Then, piston-cylinder 61 is operated to move the arms 57, 58 axially until the new roller guide 62 is at the level of the roll gap, when its arm is rotated about shaft 57 to bring it into operative position. While the mill is running, the worn guide can be safely removed from its arm for replacement by a new roller guide.

FIGS. 6 and 7 illustrate the mounting of the roll stand in either horizontal position as shown in full line in the Figures, or in vertical position, as shown in chain line. For that purpose, the stand has a mounting which includes a pair of spaced pedestals 65 secured to a base 66. Each pedestal 65 carries an upright block 67 in which can be secured an inwardly directed stub shaft 68. The stand housing carries two support sleeves 70 which rotationally receive the stub shaft 68 and thereby support the stand housing on the pedestal 65. The stand housing can be rotated about the shaft 68 by a piston and cylinder arrangement 71 which is pivotally carried by one of the pedestals and which is pivotally attached to a lug 72 on the housing. By means of the piston-cylinder arrangement 71, the stand housing can be rapidly turned from the horizontal position shown in full line in FIG. 6 in which the axes of the rolls are horizontal, to the vertical position shown in chain line, in which the axes of the rolls are vertical. The stand housing can be locked in its horizontal position by means of bolts 73 extending between the pedestals and the housing, or in the vertical position by similar bolts 74.

In FIG. 6, the drive shaft for the stand is shown at 75, that shaft being horizontal in the horizontal position and vertically downwards in the vertical position of the stand. To enable the stand to be driven in either of its positions, the drive arrangement shown in FIG. 8 can be employed. A motor 76 drives a pinion box 77 having two output shafts 78, 80. Shaft 78 can be connected through telescopic joint 81 directly with the input drive shaft 75 of the stand in its horizontal position. Drive shaft 80 can be similarly connected through telescopic joint 82 with a bevel gear box 83 disposed between the pedestals 65 and having an upwardly directed output shaft which can be connected by coupling 84 with the input shaft 75 of the stand, when in its vertical position.

It will be appreciated that the stand can be operated in angular positions between the horizontal and vertical positions shown in FIG. 6, appropriate modification of the locking bolts and of the drive being then necessary.