US3327510A

US3327510A - Clamping system for rolling mills

Info

Publication number: US3327510A
Application number: US361064A
Authority: US
Inventors: Diolot Lucien
Original assignee: Societe Nouvelle Spidem
Current assignee: Societe Nouvelle Spidem
Priority date: 1963-04-19
Filing date: 1964-04-20
Publication date: 1967-06-27
Anticipated expiration: 1984-06-27
Also published as: DE1452006A1; ES298017A1; GB1040450A; FR1362076A

Description

June 27, 1967 Filed April 20, 1964 L. DIOLOT CLAMPING SYSTEM FOR ROLLING MILLS 5 Sheets-Sheet 2 June 27, 1967 L. DIOLOT 3,327,510

CLAMPING SYSTEM FOR ROLLING MILLS Filed April 20, 1964 5 Sheets-Sheet 3 FlG,3

United States Patent 3,327,510 CLAMPING SYSTEM FOR ROLLING MILLS Lucien Diolot, Neuilly-sur-Seine, France, assiguor to S0- ciete Nouvelle Spidem, Paris, France, a corporation of France Filed Apr. 20, 1964, Ser. No. 361,064 Claims priority, application France, Apr. 19, 1963, 932,091 6 Claims. ((11. 72-240) This invention relates to a combined clamping mechanism for rolling mills.

In certain types of rolling mills the adjustment of the distance between rolls must be carried out extremely quickly. This is the case mostly in reversing mills for manufacturing products having a relatively short length at the beginning of the reduction. It is usually essential that, either for reasons of productivity or for metallurgical requirements, the idling time between each pass be reduced as much as possible.

The most commonly used types of such rolling mills are the blooming mills or the hot strip reversing mills which roll the ingot just heated and which produce, after a number of passes in both directions, blanks to be cold rolled afterwards. These rolling mills normally work with significant separating forces applied to the rolls.

Rolling mills having screw-type clamping systems that are controllable during the rolling operation are not considered feasible. These clamping devices have a very low efiiciency of power transmission due to great mechanical gearing down and thus the power necessitated for the regulation of the position of the rolls submitted to significant separating forces would require the use of driving motors of prohibitive power.

The fact that in such conventional rolling mills it is not possible to control the pressure on the rolls once the product is between the rolls involves many drawbacks. For instance, it is impossible to straighten a strip that tends to emerge obliquely, a defect commonly known as Sabre blade. In non-reversing mills such defect is corrected by acting upon a single one of the screws. Further, it is not feasible to make corrections of thickness during the last passes so as to obtain blanks having precise thicknesses, which is advantageous for the subsequent cold rolling operations. Also, in case of minor accidents such as current failure or defective adjustment of the rolls resulting in a too heavy pass causing the main motor to stall, it is impossible to rapidly unclamp the rolls. Consequently, the rolls remain in pressure contact with the hot strip for too long which, in most cases, damages the rolls or results in a significant waste of time to restart the rolling process.

Devices for turning slowly the adjusting screws or their nuts so as to bring about a slight unclamping, have already been suggested, but they are heavy, expensive and slow.

A low speed hydromechanical adjustable device for clamping or unclamping during rolling operation, which can be used in particular to carry out corrections of thickness or parallelism during relatively thin rolling passes is known in the prior art. By way of example reference is made to applicants French Patent No. 1,213,820, issued on Nov. 2, 1959.

The object of the present invention is to provide a reversible rolling mill having a safety device for avoiding the drawbacks mentioned above.

According to the present invention a rolling mill having a conventional high speed mechanical clamping system is provided in combination with the above noted known hydromechanical device acting as a hydraulic safety device and as a high speed clamping system capable of regu- ICE lating the position of the rolls during the rolling operation.

According to the present invention there is provided a reversing mill, such as a hot strip mill, comprising a high speed mechanical clamping system and a low speed hydromechanical clamping device in which an increase in the separating force of the rolls causes a pressure rise in a hydraulic circuit. This hydraulic circuit includes a pressure detector means controlling a quick drain valve thus ensuring the safety of the rolling mill by rapidly separating the rolls when irregular stresses occur, for instance, during crushing passes.

According to a preferred embodiment, the automatic operation of the quick drain valve is carried out by a system comprising a pressure detector and a torquemeter. The latter is included in the roll driving system. This torquemeter may be of the type associated with a mechanical element of the roll driving system or it may be of the type utilizing the magnitude of the current supplied to the main driving motor of the rolling mill. Such torquemeters supply a signal by closing an electric contact when the maximum safety valve of the torque is exceeded.

Consequently, every time the safety valves of the torque or the pressure are exceeded, the said electric contact first actuates the quick discharge valve, then, immediately thereafter, effectuates a high speed unclamping of the mechanical clamping system by starting its motor in the unclamping direction.

It may be necessary to cut off the main driving motor of the rolling mill when abnormal stresses occur. In this case any safety signal provided by the pressure detector or the torquemeter can be used for cutting off the driving motor and, when required for starting the motor in reverse.

The present invention will now be described with reference to the attached drawing showing as an example a four roll hot reversible mill provided with the improvements according to the invention.

In the drawing:

FIG. 1 is a side elevational view of one reducing stand of rolls with the adjusting means shown in section;

FIG. 2 is a front elevational view (partially in section) taken along line 11-11 of FIG. 1; and

FIG. 3 is a diagrammatic view of the control system associated with a stand of rolls.

In these figures, 1 and 1a are the working rolls and 2 and 2a are the back-up rolls. The upper part of each of pillars 12-12a is fitted with a conventional high speed mechanical clamping system with nuts 13-1311, screws 14-14a and revolvable bearing discs 15-15a. The screws are actuated through gears 20-200 by common driving motor 21.

The hydromechanical clamping device comprises, as known, elements 3 and 3a, each including electric motors 2242a, stepdown gears 23-2312 normally with associated worm gear means, screws 44a and a nut device adapted to push the long stroke pistons 5-5a into the cylindrical bodies 6-6:: of their respective jacks. Adjacent to the base of the rolling mill there are provided jack means comprising cylinders 8-8a adapted to receive a piston formed by the reduced lower extremity of the support means for the back-up rolls which comprises pistons 9-9a. These cylinders are fed by means of pipes or hydraulic conducits 7-7a from their respective jacks 66a.

This hydromechanical clamping device may have a clamping speed of the order of 48 mm./minute. Both stepdown gears 23 and 23a may be interconnected through mechanical transmission means 11 which includes an electromagnetic clutch means 10. When it is desired to adjust the parallelism of the oppositely dis- 3 posed mill rolls, both clamping elements 3-311 are disconnected by actuating clutch means 10.

The same result may be achieved without utilization of the transmission means 11, by substituting therefor two electrically synchronized motors, normally fed by a DC. supply.

Both the mechanical clamping system and the hydromechanical clamping device need relatively low power motors since no significant force need be exerted on the rolls before and after the rolling operation. The hydromechanical clamping system, however, is capable of exerting significant pressure on the roll even with low power motors and therefore can be used during the rolling operation for regulating the thickness of the strip being rolled or for correcting the parallelism of the rolls.

During the rolling passes, the roll separating force is continuously indicated and controlled by an operator who observes manometers 17-17a which are connected to connecting pipes 7-7a of the hydromechanical clamping device. Quick drain valves 16-16a, which may be either electromagnetically or hand operated, are connected to the pipes 7-7a connecting the jacks 88a and jacks 6-611.

From the point of view of safety, should, for any accidental reason, the maximum separating force specified for the rolling mill be exceeded, or the torque value supplied by the rolling mill control motor become too high, the protective circuit operates as follows:

An electric circuit is closed, either by an electric contact provided in the manometers 1717a, or by means of an electric contact of the torquemeter 24 which can be arranged, for instance, on a driving shaft 25 between the rolls and the step-down gear associtaed with the roll driving motor (see FIG. 3). This circuit first causes through a conventional relay 29 the operation of

quick drain valves

16 and 16a to return through a pipe 28 to a tank 27 the oil contained in pipes 7-7a of the hydromechanical clamping means. Pressure in the hydraulic transmission thus drops almost instantaneously. The same electric circuit controls the high speed opening of the mechanical clamping system. Such operation may take place without delay since the roll separating force has been considerably reduced by the rapid operation of the drain valves 1646a.

Should the excess stresses cause the drive motor of the mill to stall, the former may be immediately reversed so as to prevent the hot strip from being jammed between the rolls that could cause damage thereto. Similarly if, owing to a current failure, a strip stops under pressure between the rolls, manual operation of the drain valves will relieve the pressure, thus reducing to a large extent the damages which could be caused to the rolls by the hot strip jammed between them.

During the last passes, the rolling mill may operate by fully utilizing the inherent advantages of the hydromechanical clamping device.

It is known that the strip must emerge at the roll exit side in a direction normal to the roll axis so as to remain on an adjacently disposed supporting table (not shown) and be in a correct position for subsequent cold rolling. If the strip tends to emerge obliquely (Sabre blade), the fact that it is possible to carry out a slow adjustment by using the hydromechanical clamping device, makes possible, as in a conventional cold strip rolling mill, to bring the strip back to a correct position.

In addition, if the rolling mill is provided with an instrument for measuring the thickness of the material emerging at the exit end thereof, it is always possible by using the characteristic of the hydromechanical clamping means that permits adjusting during rolling operation-to carry out accurate adjustment of thickness for the material during the last series of passes, and more particularly during the ultimate pass.

Finally, in the hot rolling mills, the removal of the back-up rolls-for periodic inspection thereof-can be easily carried out owing to the hydromechanical clamping device.

As best shown in the lower portion of FIG. 1, there are provided diametrically opposed, pivotally mounted support means lit-18a which, during operation of the mill, are tilted in an upwardly converging direction.

Preparatory to removing the rolls, they are lifted by means of fluid provided within

jacks

8 and 8a. Then the pivotally mounted support means 18 and 18a are brought to a vertical position. By decreasing the pressure on jack means 8 and 8a, each set of rolls is led to rest on the pivotally mounted support means through

chock tread rollers

19 and 19a, thereupon the rolls are removed in accordance with the usual method.

Although FIGS. 1 and 2 indicate a specific location for the high speed clamping system (upper part of the rolling mill with control on platform) and for the hydromechanical clamping device with adjusting jacks under the chocks of the lower back-up roll, it is to be understood that the location of both clamping devices may be chosen at will according to requirements.

It is further noted that the present invention may be used in any rolling mill such as a hot four high reversing mill, a two high mill, blooming mill as well as a cold mill.

Although only one embodiment of the invention has been depicted and described, it will=be apparent that this embodiment is illustrative in nature and that a number of modifications in the apparatus and variations in its end use may be effected without departing from the spirit or scope of the invention as defined in the appended claims.

I claim:

1. In a rolling mill of the type including a base, at least one upper and one lower working roll each vertically adjustable with respect to one another and between which a strip to be rolled is adapted to pass, means for driving said rolls, the combination comprising, high speed mechanical clamping means adapted to effect a rapid change of clearance between said rolls by screw means driven by first motor means, low speed hydromechanical' clamping means including first hydraulic cylinder means affixed to said base, short stroke piston means vertically reciprocable in said first cylinder means and supporting said lower roll, second hydraulic cylinder means reciprocably receiving long stroke piston means adapted to effect a low speed change of clearance between said rolls by displacing said long stroke piston means by second motor means, hydraulic conduit means communicating between said first and said second hydraulic cylinder means to maintain both said cylinder means under equal hydraulic pressure, said conduit means including pressure sensing means and drain valve means, electric control circuit means interconnecting at least said pressure sensing means and said drain valve means to relieve said hydraulic pressure in both said cylinder means when said pressure exceeds a predetermined safe valve.

2. The combination according to claim 1 including torque sensing means for detecting an increase of the torque of said working rolls, said torque sensing means connected to said drain valve means through said electrical control circuit means to relieve said hydraulic pressure in both said cylinder means when said torque exceeds a predetermined safe value.

3. The combination according to claim 2 wherein said high speed mechanical clamping means includes reversible driving means, said control circuit means being connected to said driving means for actuating the same when either of said sensing means energizes said circuit means.

4. The combination according to claim 1 wherein said high speed mechanical clamping means includes reversible driving means, said control circuit means being connected to said driving means for actuating the same when said pressure sensing means energizes said circuit means.

5. The combination according to claim 3 including a References Cited reversible roll driving means, said control circuit means UNITED STATES PATENTS being connected to said roll driving means for revers- 2 903 926 9/1959 Reichl ing the same when either of said sensing means energizes 2:985:042 5/1961 Talbot illitj: Sald 3,191,408 6/1965 Bayan 72 245 6. The combmatron accordmg to claim 1 Wherem said drain valve means includes manual control means for FOREIGN PATENTS releasing said pressure to cause separation of .the Working 9 ,1 4/196 r at B itain.

rolls upon failure in current supply means associated With said electrical control circuit and said means for 10 CHARLES LANHAM Prlma'y Examine driving said rolls. A. RUDERMAN, Assistant Examiner.

Claims

1. IN A ROLLING MILL OF THE TYPE INCLUDING A BASE, AT LEAST ONE UPPER AND ONE LOWER WORKING ROLL EACH VERTICALLY ADJUSTABLE WITH RESPECT TO ONE ANOTHER AND BETWEEN WHICH A STRIP TO BE ROLLED IS ADAPTED TO PASS, MEANS FOR DRIVING SAID ROLLS, THE COMBINATION COMPRISING, HIGH SPEED MECHANICAL CLAMPING MEANS ADAPTED TO EFFECT A RAPID CHANGE OF CLEARANCE BETWEEN SAID ROLLS BY SCREW MEANS DRIVEN BY FIRST MOTOR MEANS, LOW SPEED HYDROMECHANICAL CLAMPING MEANS INCLUDING FIRST HYDRAULIC CYLINDER MEANS AFFIXED TO SAID BASE, SHORT PISTON MEANS VERTICALLY RECIPROCABLE IN SAID FIRST CYLINDER MEANS AND SUPPORTING SAID LOWER ROLL, SECOND HYDRAULIC CYLINDER MEANS RECIPROCABLY RECEIVING LONG STROKE PISTON MEANS ADAPTED TO EFFECT A LOW SPEED CHANGE OF CLEARANCE BETWEEN SAID ROLLS BY DISPLACING SAID LONG STROKE PISTON MEANS BY SECOND MOTOR MEANS HYDRAULIC CONDUIT MEANS COMMUNICATING BETWEEN SAID FIRST AND SAID SECOND HYDRAULIC CYLINDER MEANS TO MAINTAIN BOTH SAID CYLINDER MEANS UNDER EQUAL HYDRAULIC PRESSURE, SAID CONDUIT MEANS INCLUDING PRESSURE SENSING MEANS AND DRAIN VALVE MEANS, ELECTRIC CONTROL CIRCUIT MEANS INTERCONNECTING AT LEAST SAID PRESSURE SENSING MEANS AND SAID DRAIN VALVE MEANS TO RELIEVE SAID HYDRAULIC PRESSURE IN BOTH SAID CYLINDER MEANS WHEN SAID PRESSURE EXCEEDS A PREDETERMINED SAFE VALVE.