GB2118331A

GB2118331A - A roll clearance control and adjusting device

Info

Publication number: GB2118331A
Application number: GB08308744A
Authority: GB
Inventors: Emil Friedrich Kersting
Original assignee: Mannesmann AG
Current assignee: Vodafone GmbH
Priority date: 1982-04-03
Filing date: 1983-03-30
Publication date: 1983-10-26
Also published as: GB2118331B; JPS58184008A; DE3212525A1; IT8320439A0; IT1163216B; FR2524352A1

Abstract

The device serves to control the rolls of a vertical stand of a rolling mill during vertical or edge rolling of slabs and in order to control the thickness during horizontal rolling. Each of the adjusting spindles 5 has an axial passage 15 housing a piston 17 and a plunger 18 at the end remote from the roll, and a piston 34 at the end nearer the roll. The space between the pistons is filled with a pressure medium in which the plunger is immersed. A continual comparison is made between desired and actual values, and the plunger adjusted accordingly to produce a change in pressure in the medium and adjustment of piston 34 and a change in roll tension via electrohydraulic control valve 32. The main spindle 5 is moved by an electric motor via pinion 12 and nut 9. <IMAGE>

Description

SPECIFICATION A roll clearance control and adjusting device The invention relates to an electrohydraulic roll clearance control and adjusting device, especially although not exclusively useful for the rolls of a vertical rolling mill stand. By way of example, Federal German patent No. 1 602 043 describes and illustrates such a device which includes a piston and cylinder unit, adjustment of which is produced by a plunger acting on the pressure fluid supplied to the piston chamber. The plunger itself is displaced by a hydraulic lifting device controlled by a servo valve.

The device also includes a scanning device for detecting the roll forces by pressure measurement, a measuring device for determining the actual position of the plunger, and a comparator which generates an alteration signal in response to discrepancies between the actual and desired positions of the plunger.

Devices of this type for controlling thickness when rolling metal strips have been known for a long time and have proven eminently suitable in practice. In more detail, the plunger is coupled to an oilhydraulic servo-controlled pilot cylinder. This plunger acts as a displacement piston in a closed system which is filled with a special grease, and thus effects adjustment of the flat main piston arranged in a cross beam between roll fittings and stands. A more rapid response to differences in roll pressure and therefore correspondingly more rapid alterations are achieved as it is now possible continuously to measure the actual position of the plunger and therefore the prevailing adjustment and also to monitor the roll pressure simultaneously.Alterations in the roll pressure from a predetermined desired value are immediately converted into a signal which, on the basis of the signal corresponding to the respective plunger position, serves to generate a control signal which defines the new position of the plunger. Consequently, instead of using movements of the adjusting piston under the influence of the altered roll pressure as the measured variable, the alteration in the roll pressure itself is used for this purpose. This increases the responsiveness of the device.

The starting product for a wide strip train (except in the case of a continuous casting installation) is produced in a conventional manner in a so-called slabbing mill. The flat starting material is produced from a block by intermittent working of the side edges of the expanding slab via the vertical or edge rolls in alternation with the horizontal pass.

Although attempts have been made for some time to roll flat material in a vertical stand with a width which is approximately constant over the entire length (see German Offenlegungsschrift No. 2 047 240), it has not been possible to find a satisfactory solution. Once the proposed thickness of the starting material was achieved, the flat slab was rolled out further into a strip in the finishing train, the wide strip train but, owing to the differing slab widths, this produced strip widths which had to be subsequently corrected by unnecessarily coarse shearing.

The object of the invention is to produce the above-mentioned advantages of the known thickness adjustment system, in particular for width control, with minimum expense in vertical stands and thus to achieve width dimensions which reduce as far as possible the wastage due to subsequent shearing of the finished strip. On the other hand, the structural features should restrict the cost of the installation even when it is used as a thickness adjusting and control system in horizontal stands.

According to the invention, this object is achieved by using a hollow adjusting spindle with an axially extending passage which receives pistons for the control of width and/or thickness.

One piston together with the plunger may be inserted into the end of the adjusting spindle remote from a roll fitting member, and the other adjusting piston inserted into the end of the adjusting spindle adjacent to the roll fitting member. The pressure medium may then fill the space between the plunger and the adjusting piston. Thus it is possible not only to control in a simple manner the roll adjustment of the rolls in vertical stands for width control, but also to control the thickness via the adjusting spindles even in horizontal stands, the cross beam otherwise arranged between the upper fitting members and the stands, with the devices of the adjusting system, no longer being necessary in either case.

The single Figure of the drawing shows a cross section through one of the adjusting spindlesforthe vertical roll of a vertical stand, other parts of which are not shown.

The electrohydraulic roll clearance control and adjusting device designated generally by 1 can be positioned in advance by means of adjusting spindle 5 and return cylinder 2 for differing width dimensions in the roll material to be worked. The piston rod 3 of the return cylinder 2 is connected via a cross beam 4 to the pressure or adjusting spindle 5. A concertina wall 6 secured by clamping rings 7 and a labyrinth packing 10 protect the buttress thread of the adjusting spindle 5. After preliminary positioning of the adjusting spindle 5, the fundamental and rough adjustment of the fitting member 8 loaded by the adjusting spindle 5 and thus the vertical roll (not shown) is effected by rotating the nut 9 in order to feed the spindle 5 through the nut. The nut 9 is fast with a pinion 12 driven in rotation by an electric motor. The nut 9 is guided in a rigid housing by axial bearings 13.

The adjusting spindle is hoilow; having an axial passage 15 the diameter of which varies along its length thereby creating spaces for receiving hydraulic piston cylinder units or a lipoid pressure medium. A hydraulic lifting device consisting of the piston 17 and the plunger 18 of smaller diameter is thus inserted into the end of the adjusting spindle 5 remove from the fitting member 8 and is guided adjustably in the hyraulic cylinder 19. The cylinder 19 is formed by a bush 22 fitted into the passage 5 and an end plate 23 which seals this end of the passage 15. The end plate 23 and bush 22 are fixed to the wall 5a of the adjusting spindle 5 by screws 24 indicated in broken lines.A shaft 26 extending out of the cylinder 19 in the opposite direction through a bore 25 in the plate 23 is rigidly connected to the piston 17 or plunger 18, the respective position of the shaft 26 and thus the position of the plunger 18 being measured by a pick-up 27 responsive to the position of a finger 28 connected to the shaft 26. The hydraulic cylinder 19 can be loaded in a controlled fashion by a servo-valve 32 from a pressure source by way of the line 29.

At the opposite, or roll end, of the adjusting spindle 5 the cylinder bore 33 receives an adjusting piston 34, the piston rod 35 of which projects from the bore and bears against the fitting member 8. The piston rod 35 is thus guided in a bush 36 which is fixed to the wall 5a of the adjusting spindle 5 by means of screws 37 indicated in dot dash lines. The cylinder space 33a remaining between the adjusting piston 34 and the bush 36 can thus be filled with a hydraulic fluid so that the adjusting piston 34 and therefore the piston rod 35 can be withdrawn from the fitting member independently of other adjustments, for example during a change of rolls. However, this is irrelevant for the actual control of roll clearance. The space 16 in the passage 15 remaining between the plunger 18 and the adjusting piston 34 is filled with the pressure medium.All pistons and cylinder chambers are sealed by packagings 38 and 39.

The mode of operation is not very difficult from that of the thickness control device according to German Patent No. 1 602043 to which reference should be made. Therefore, in describing the operation, attention will be paid mainly to features not illustrated but described in detail in Germany Patent No. 1 602043.

Starting with the situation just described, the hydraulic cylinder 19 is charged as the result of a pulse from a scanning device which has previously determined the value of the pressure prevailing in the chamber 16 of the lipoid pressure medium, which is proportional to the roll pressure and thus to the roll jump, by way of servo valve 32, so that the plunger 18 moves. This causes a change in the pressure in the chamber 16. As a result of this pressure change, the adjusting piston 34 is moved via the pressure medium column, which causes a change in the initial tension of the rolls in the roll stand. In this process, the actual position of the plunger 18 which reproduces the alterations in the roll stand is compared continuously with the desired position, and a comparator receives the compensation signal intended for the change in the actual position of the plunger 18 and processes it into an adjusting signal for altering the position of the plunger 18. The plunger 18 can also be controlled, for example, by a desired value signal transmitted from a width measuring device into the pick-up 27.

Claims

1. An electrohydraulic roll clearance control and adjusting device comprising an adjusting spindle having an axial bore with portions of differing internal diameters, pistons for the control of width and/or thickness disposed within the passage, the pistons being movable under the pressure of fluid into which penetrates a plunger, movement of which is controlled by a hydraulic lifting device controlled by a servo valve, a scanning device for detecting the roll forces by pressure measurement, a measuring device for determining the actual position of the plunger, a comparator for generating an alteration signal in response to a discrepancy between the actual and desired positions of the plunger.

2. A device according to claim 1, wherein a first piston together with the plunger are disposed in one end of the adjusting spindle remote from a roll fitting member and a second piston is disposed in the end of the adjusting spindle resting against the roll fitting member, the pressure medium filling the space between the plunger and the second adjusting piston.

3. A roll clearance device substantially as illustrated in the drawing.

4. An electrohydraulic roll clearance control and adjusting device comprising an axial bore through an adjusting spindle or a roll stand, a first piston disposed within one end of the bore in contact with a plunger for pressurising fluid within the bore, a second piston disposed within the other end of the bore such as to act upon the roll, and servo control means for adjusting the first piston and thereby the plunger.