US3631696A

US3631696A - Pressure relief mechanism

Info

Publication number: US3631696A
Application number: US40307A
Authority: US
Inventors: Willard B Williams
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-05-25
Filing date: 1970-05-25
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04

Abstract

A pressure relief mechanism for the work rolls in a rolling mill strand with a frame in which a holddown device exerts the desired pressure on the work rolls. The relief mechanism includes a plurality of disc-shaped members with opposing projections positioned between the holddown device and the work rolls. The projections of the members can be placed in more or less register to vary the pressure between the work rolls. Excessive pressure on the work rolls is relieved by moving at least one of the members relative to the other to intermesh their projections, thereby allowing limited vertical movement of one of the work rolls to relieve pressure between the rolls.

Description

United States Patent Primary ExaminerMilton S. Mehr Attorney-Mason, Mason & Albright ABSTRACT: A pressure relief mechanism for the work rolls in a rolling mill strand with a frame in which a holddown device exerts the desired pressure on the work rolls. The relief mechanism includes a plurality of disc-shaped members with opposing projections positioned between the holddown device and the work rolls. The projections of the members can be placed in more or less register to vary the pressure between the work rolls. Excessive pressure on the work rolls is relieved by moving at least one of the members relative to the other to intermesh their projections, thereby allowing limited vertical movement of one of the work rolls to relieve pressure between the rolls.

PATENTEDJAN 4m 3.631. 696

WILLARD a. wlullms FIG. 3

PRESSURE RELIEF MECHANISM This invention relates to a quick release in a rolling mill stand which allows vertical movement of one working roll relative to the other roll to prevent damage to the work roll when wrecks occur during rolling operation. The device can also be used in presses and related machinery. When cobbles or doubling up occurs in steel sheets or plates being rolled at high speed, the pressure between the work rolls becomes excessive and if not quickly relieved, permanent damage is done to the rolling equipment, particularly to the expensive work rolls. Ordinarily, the beginning of a wreck usually does not do great damage, but as the steel sheet or plate doubles and redoubles and passes between the work rolls, the pressure increases, causing great heat, distortion and fire cracking of the rolls.

Thus, the present invention is not intended to prevent wrecks, but to prevent damage ultimately done to the rolling equipment involved in wrecks. In particular, this invention is a quick release for pressure applied to the work rolls, permitting the rolls to separate by vertical movement before damage oc curs. The quick release device can be associated with a screwdown on the work rolls or with work rolls pressurized by a hydraulic system. The device can be kicked off" by a conventional monitoring system in which an electric monitor, such as a photoeye, detects distortions in the steel being processed, and switches a motor to move a rod, gear or other mechanism associated with the quick-release device. The device can also be associated associated with a press ductor that mounts under each side of the lower backup roll to constantly monitor the roll pressure. With this arrangement, an instant signal is made by an amplifier, when pressure exceeds a predetermined level. Such monitors are well known and form no part of this invention, apart from the combination disclosed herein.

Once the monitor is activated, a first part of the device is moved relative to a second part and projections between the two parts are placed in more or less register to vary the vertical distance between the parts and ultimately, the spacing between the work rolls.

It is therefore an object of the present invention to provide a quick-release device that can be associated with the structure that exerts pressure on the work rolls of a roll stand, to quickly and effectively relieve excessive pressure between the rolls thereby preventing damage to same when wrecks occur during operation.

These and other objects will be apparent from the description and drawings in which:

FIG. 1 is a side elevation of the mill stand showing a frame with rolls in work position and the relative location of the quick release device.

FIG. 2 is an enlarged perspective view of the quick release device in work position.

FIG. 3 is a perspective view of the FIG. 2 device after kickoff.

FIG. 4 is a plan view showing the configuration of the quick release device.

In FIG. 1, the rolling mill stand includes a frame 1 in which slideable lower roll chock 3 and upper chock 5 are mounted to move lower backup roll 7 and upper backup roll 9 respectively relative to each other in vertical directions. Backup rolls 7 and 9 bear on work rolls 1] and 13 respectively and the work rolls are mounted in chock blocks 11A and 13A which are slideable vertically relative to one another in lower roll chock 3.

Lower chock 3 can be permanently affixed in the lower part of frame 1 or be slideably mounted as shown in FIG. 1 with adjusting

bolts

17 and 19 having threaded

nuts

21 and 23 to fix chock 3 in its selected position. Another conventional arrangement would be the use of hydraulic pistons in place of

bolts

17 and 19 to adjustably position the lower chock.

The upper chock roll 5 is held down by conventional hydraulic means or a screwdown as seen in FIG. 1 Between the holddown l5 and chock 5 a pressure quick-relief device 30 is positioned to include an upper member 29 and a lower member 31 which can each be disc shaped. The lower member 31 is preferably keyed at 33 to the roll chock 5 and fixed in place. The upper member 29 is movable relative to member 31 and is preferably tumable about a dowel or pin 35 which is fitted in the approximate centers of the

disc members

29 and 31.

Each of the disc members have

projections

37 and 39 which can be generally teethlike in configuration so that opposing projections can be placed in more or less register with one another and thereby decrease or increase the pressure that holddown l5 exerts on working roll 11. The

teeth

37 and 39 could take the form of inclined planes of various configurations so long as the projections can interfit upon kickofif As seen in FIGS. 1 and 2, the teeth crowns 37A of projections or teeth 37 on upper member 29 oppose the crowns 39B of teeth 39 on lower member 31 when the mill stand is operating and in work position. The crowns 37A and 39A can be flattened to provide more surface friction thereby resisting the displacement of the disc members relative to one another. Displacement of the member 29 for its position in FIGS. 1 and 2 can only take place in one direction, namely, counterclockwise as shown in the drawings, since bumper stops 4] and 43 of the lower and upper members respectively, prevent contramovement when in abutment.

In the embodiment shown, the

disc members

29 and 31 are held together by the pressure exerted by holddown 15 and are held in alignment with each other by pin 35. The longitudinal axis of pin 35 is substantially vertical and normal to the longitudinal axes of the work rolls 11 and 13. The

disc members

29 and 31 are of metal and can be about 4 or 5 inches thick and 15 inches in diameter with

projections

37 and 39 each about one-fourth inch in height. The crowns 37A and 39A can have flat spots about I inch long with centers about 6 inches apart so that for each 3 inches of lineal movement of the outer edge of member 29 relative to fixed member 31, about onefourth inch of vertical movement can be gained by the upper roll chock 5 and, consequently, work roll 11. It will be appreciated that the above dimensions can be varied to suit particular needs and that the provision of flat spots 37A and 39A is preferred, not mandatory. Also, tapered roller bearings can be mounted on the fiat spots to vary the friction resistance encountered when one member turns relative to the other member.

In general, about one-eighth or three-sixteenth inch of vertical movement of one of the work rolls will suffice to relieve the excessive pressure that would otherwise damage the rolls when cobbles or doubles occur in most steel sheet or plate being rolled.

The upper disc member 29 can be turned or kicked off to relieve pressure by means of a rod 47 which bears on a flat segment 45 positioned at a right angle to the axis of pin 35. Rod 47 is preferably hydraulically actuated by a system (not shown) that has an electric switch responsive to the detection of cobbles, doubles and other deformaties that cause wrecks. The hydraulic system is preferably double action so that the member 29 can be returned to mill run position.

It will be understood that the lower disc member 31 or both

members

29 and 31 can be moved responsive to hydraulic or other devices so as to intermesh

teeth

37 and 39 and relieve excessive pressure. Also, more than two disc members or a thrust-bearing device can be used so long as the movement of projections serve to decrease the distance between opposing members and allow vertical movement of the work rolls with respect to one another.

I claim:

1. A pressure relief mechanism for a rolling mill stand comprising a frame with work rolls that are vertically displaceable relative to one another within said frame and a holddown for urging said work rolls against one another at the desired rolling pressure, a quick release device located between one of said work rolls and said holddown, said device including two juxtaposed members having opposing teeth means, the first of said members being turnable relative to the second of said members about a pin, responsive to a force exerted substantially normal to the axis of said pin, whereby the teeth means of said members can be placed in more or less register with one another to vary the pressure between the said work rolls.

2. The mechanism of claim 1 wherein said members have abutting stop means to limit the relative turning movement of said members in one direction.

3. The mechanism of claim 2 wherein said teeth means comprises a plurality of teeth that have flat portion at their crowns whereby the opposing crowns of said teeth means are in pressure contact with one another when said stop means limits the relative movement of said members in one direction.

4. The mechanism of claim 1 wherein said members are disc shaped and said first member is turnable relative to said second member, said first member having a flat segment normal to the axis about which said first member turns.

5. The mechanism of claim 4 wherein the first of said memhers is positioned above the second of said members and the latter is affixed to a chock in which a backup roll is mounted to exert pressure on the upper of said work rolls.

6. The mechanism of clam 5 wherein the holddown is a screwdown which is threaded on said frame to bear on said chock.

7. The mechanism of claim 1 wherein the longitudinal axis of said pin is substantially vertical and at right angles to the longitudinal axis of the work rolls.

8. The mechanism of claim I wherein said teeth means comprises a plurality of teeth with opposing crowns having flat portions in pressure contact during operation, the centers of adjoining crowns on one member being spaced apart a distance about six times the lengths of said flat portions.

Claims

1. A pressure relief mechanism for a rolling mill stand comprising a frame with work rolls that are vertically displaceable relative to one another within said frame and a holddown for urging said work rolls against one another at the desired rolling pressure, a quick release device located between one of said work rolls and said holddown, said device including two juxtaposed members having opposing teeth means, the first of said members being turnable relative to the second of said members about a pin, responsive to a force exerted substantially normal to the axis of said pin, whereby the teeth means of said members can be placed in more or less register with one another to vary the pressure between said work rolls.

3. The mechanism of claim 2 wherein said teeth means comprises a plurality of teeth that have flat portions at their crowns whereby the opposing crowns of said teeth means are in pressure contact with one another when said stop means limits the relative movement of said members in one direction.

5. The mechanism of claim 4 wherein the first of said members is positioned above the second of said members and the latter is affixed to a chock in which a backup roll is mounted to exert pressure on the upper of said work rolls.

6. The mechanism of claim 5 wherein the holddown is a screwdown which is threaded on said frame to bear on said chock.

8. The mechanism of claim 1 wherein said teeth means comprises a plurality of teeth with opposing crowns having flat portions in pressure contact during operation, the centers of adjoining crowns on one member being spaced apart a distance about six times the lengths of said flat portions.