GB2263876A

GB2263876A - Balancing and bowing the working rolls of a roll stand

Info

Publication number: GB2263876A
Application number: GB9302005A
Authority: GB
Inventors: Axel Barten
Original assignee: Achenbach Buschhetten GmbH and Co KG
Current assignee: Achenbach Buschhetten GmbH and Co KG
Priority date: 1992-02-05
Filing date: 1993-02-02
Publication date: 1993-08-11
Anticipated expiration: 2013-02-02
Also published as: FR2686816B3; IT1263045B; ITMI930163A0; GB9302005D0; FR2686816A1; ITMI930163A1; GB2263876B; DE4203189A1

Description

-I- 2263876 A device for balancing and bowing the working rolls of a roll

stand This invention relates to a device for balancing and bowing the working rolls of a roll stand of a multi-roll strip rolling mill, especially a four-high rolling mill with a pair of double acting adjusting pistons for each roll, actuated by pressure medium cylinders and engaging the mounting pieces of the upper and lower working rolls, wherein the cylinder-piston units are built into retainina, blocks, which are arranged symmetrically relative to the plane of the roll axes in the column windows of the two roll columns of a roll stand and comprise guides for the working roller mounting pieces.

In one such balancing and bowing device known from DE-A 2 516 850 C3 for the working rolls of a four-high roll stand, the hydraulic cylinders are fitted with the adjusting pistons for the roll mounting pieces opposite one another in the retaining blocks, so that a relatively large structural height results, which in turn requires corresponding openings in the backing roll mounting pieces. Especially with large backing rolls and small working rolls, the size of the openings in the backing roll mounting pieces for fitting the retaining blocks is limited on account of the large diameter of the backing roll bearing matching the large backing roll 0 p diameter, so that the elongation of the retaining block in the direction of the plane of the roll axes is likewise limited. These structral conditions result in the distance between the adjusting pistons engaging the working roll mounting pieces by means of dogs and fitted in the retaining blocks and the centre of the working roller bearing being relatively large, so that the working roller bearings are subject to C W W correspondingly large loadings through the rolling forces and through the bending W 0 0 Z forces exerted by the adjusting pistons and increased by leverage on account of the t> relatively large distance between adjusting pistons and roll bearings. The large loadings lead to heavy wear of the roll bearings, so that these have to be replaced at relatively short intervals. A further disadvantage is that, because of the off-centre transfer of the adjusting forces through the dogs of the adjusting pistons to the 0 working roll mounting pieces, the piston surfaces and the running surfaces of the C C7 C) cylinder bushes are subjected to high contact pressures, which affect the running characteristics of the adjusting pistons.

C> The last-mentioned disadvantage also occurs with the balancing and bending C device according to DE 1 289 811 C2, in which however the loadings on the working roll bearings are smaller, since the hydraulic cylinders with the adjusting pistons for the working roller mounting pieces are fitted in arms of the backing roll mounting pieces and the adjusting pistons are arranged closer to the working roll bearings than in the bending device according to DE 2 516 850 C3. However the fitting of the hydraulic cylinders with the adjusting pistons in the backing roll mounting pieces incurs the disadvantage that, in disassembling and assembling a roll set, all hydraulic lines of the hydraulic cylinder-piston units have to be released from and connected to the coupling lines in the roll columns.

The invention is based on the object of improving the balancing and bending device of the kind defined in relation to relieving the load on the working roll bearings in the working roll mounting pieces and the adjusting pistons of the I C.7 mounting pieces.

This object is solved according to the invention by a balancing and bending device with the features of claim 1.

The dependent claims are directed to advantageous developments of the bending device according to the invention.

CID Because of the mutually rotated arrangement of the hydraulic cylinders with the adjusting pistons in the retaining blocks according to the invention, their structural height is lower than in the state of the art and the adjusting pistons have a minimum distance from the working roll bearings, so that these experience substantial relief from loading and the bending forces transferred by the adjusting pistons act optimally in the centre of the roll bearings. The adjusting pistons formed as plunger pistons are distinguished by good running characteristics.

The balancing and bending device according to the invention will now be explained in relation to a four-high stand with reference to schematic drawings, in which:

Figure 1 shows a partially broken away side view of a four-high stand with the novel roll bending device and Figure 2 is a section along the line II-II of Figure 1 in an enlarged view.

Figure 1 shows schematically a roll stand 1 of a four-high rolling mill with Z:' two columns 2, whose windows 3 receive upper and lower working rolls 4, 5, which are journalled in upper and a lower working roll mounting pieces 6, 7, as well as upper and a lower backing rolls 8, 9, which are mounted in upper and lower backing roll mounting piecs 10, 11. Interchangeable retaining blocks 12, 13 with guides 14 are arranged in the column window 3 of the roll column 2 symmetrically with respect to the plane 15-15 of the roll axes, the mounting pieces 6, 7 of the upper and lower working rolls 4, 5 being movably guided in these guides.

Hydraulic adjusting pistons 16, which run in cylinders 17-20 formed in the retaining blocks 12, 13 serve to pre-stress and adjust the mounting pieces 10, 11 of the upper and lower support rolls 8, 9.

Adjusting pistons 21 formed as plunger pistons run in hydraulic cylinders 22 25, which are formed in the retaining blocks 12, 13 and act on the working roll mounting pieces 6, 7 through centrally disposed dogs 26, which each engage through an opening 28 in the cylinder wall 27 between the two cylinder chambers 29, 30 of the hydraulic cylinders 22-25 and in corresponding grooves 31 of the mounting pieces 6, 7. The engagement surfaces 26a, 26b on the dogs 26 of the adjusting pistons 21 are ball-shaped.

The longitudinal axes 22a-22a, 23a-23a of the two cylinder-piston units 22, 21; 23, 21 for adjusting the upper working roll mounting piece 6 and the longitudinal axes 24a-24a, 25a-25a of the two cylinder-piston units 24, 21; 25, 21 for adjusting the lower working roll mounting piece 7 are arranged diametrically opposite on a fictional cylinder 32, whose longitudinal axis 32a-32a represents the line of intersection of the plane 15-15 of the roll axes with the vertical central plane 33-33 of the roll bearings 34 and the two pairs of cylinder-piston units 22, 21; 23, 21 and 24, 21; 25, 21 are fitted in the retaining blocks 12, 13 rotated relative to one another through a predetermined angle a. This arrangement of the cylinder- piston units 22, 21-25, 21 results in the roll bending forces transferred by the adjusting pistons 21 being applied optimally in the middle 35 of the roll bearings 34.

With actuation of the cylinder chambers 30 of the hydraulic cylinders 22, 23 and of the cylinder chambers 29 of the hydraulic cylinders 24, 25, the adjusting pistons 21 are urged oppositely with respect to each other and concave bowing of the working rolls 4, 5 relative to the roll gap 36 is thus effected. If the pressurised oil in the cylinder chambers 29 of the hydraulic cylinders 22, 23 and the cylinder chambers 30 of the hydraulic cylinders 24, 25 is relieved by simultaneous venting of the chambers 30 of the cylinders 22, 23 and the chambers 29 of the cylinders 24, 25, the adjusting pistons 21 are moved away from each other and a concave bowing of the working rolls 4, 5 relative to the rolling gap 36 is thereby obtained.

Claims

1. A device for balancing and bowing the working rolls of a roll stand of a multi-roll strip rolling mill, especially a four-high mill with a pair of double acting adjusting pistons for each roll, actuated by pressure medium cylinders and engaging the mounting pieces of the upper and lower working rolls, wherein cylinder-piston 0 units are built into retainina blocks, which are arranged symmetrically relative to the plane of the roll axes in the column windows of the two roll columns of a roll stand and comprise guides for the working roller mounting pieces, characterized in that the longitudinal axes of the two cylinder-piston units for adjusting the upper working roll mounting piece and the longitudinal axes of the two cylinder-piston units for adjusting the lower working roll mounting pieces are arranged diametrically opposite on a fictional cylinder whose longitudinal axis represents the line of intersection of the plane of the roll axes with the vertical roll bearing central plane, and in that the two pairs of cylinder-piston units are fitted in the retaining blocks rotated relative to one another through a predetermined angle.

2. A device according to claim 1, characterized in that the adjusting pistons of 1 the hydraulic cylinders have dogs in the middle for adjusting the working roll mounting pieces, each dog engaging through an opening in the cylinder wall C) C7 C between the two cylinder chambers of the hydraulic cylinders in corresponding grooves of the mounting pieces.

3. A device according to claim 2, characterized in that the engagement surfaces of the dogs on the adjusting pistons are ball-shaped.

4. A device according to any of claims 1 to 3, characterized in that the adjusting pistons are formed as plunger pistons.

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