US3691810A

US3691810A - Individual eccentric control for mill screwdown

Info

Publication number: US3691810A
Authority: US
Inventors: Tadeusz Sendzimir
Original assignee: T Sendzimir Inc
Current assignee: T Sendzimir Inc
Priority date: 1971-05-25
Filing date: 1971-05-25
Publication date: 1972-09-19
Anticipated expiration: 1989-09-19
Also published as: FR2190535B1; FR2190535A1; GB1379108A; DE2238064A1

Abstract

In a beam-backed rolling mill wherein the working rolls are backed by casters mounted on eccentric shafts for screwdown purposes, there is disclosed an arrangement wherein a plurality of eccentrics are mounted at spaced intervals on a shaft, each of said eccentrics being individually operable by outside means, whereby the eccentrics may be made large enough so as not to be self-locking, and whereby the pressure exerted by each eccentric, through the adjacent caster, upon the work roll, may be controlled and the roll profile adjusted to a desired configuration.

Description

United States Patent Tadeusz 51 Sept. 19, 1972 [54] INDIVIDUAL ECCENTRIC CONTROL FOR MILL SCREWDOWN Inventor: Tadeusz Sendzimir, 0/0 T. Sendzimir Inc. PO. Box 1350, Waterbury, Conn. 06720 Filed: May 25, 1971 Appl. No.: 146,661

US. Cl. ..72/242, 72/243, 72/244 Int. Cl ..B21b 29/00, B2lb 31/26 Field of Search ..72/243, 240, 244, 245, 242

References Cited UNITED STATES PATENTS 8/1939 Sendzimir ..72/242 X 8/1949 Sendzimir et al. ..72/243 X 3,147,648 9/1964 Sendzimir ..72/243 X Primary Examiner-Milton S. Mehr Attorney-Melville, Strasser, Foster 8:. Hoffman [57] ABSTRACT In a beam-backed rolling mill wherein the working rolls are backed by casters mounted on eccentric shafts for screwdown purposes, there is disclosed an arrangement wherein a plurality of eccentrics are mounted at spaced intervals on a shaft, each of said eccentrics being individually operable by outside means, whereby the eccentrics may be made large enough so as not to be self-locking, and whereby the pressure exerted by each eccentric, through the adjacent caster, upon the work roll, may be controlled and the roll profile adjusted to a desired configuration.

15 Claims, 6 Drawing Figures PATENTEDsw 19 m2 SNEET 2 0F 2 INVENTOR j TADEUSZ SENDZIMIR ELVXLLE STRASSER, FOST ER and HOFFMAN INDIVIDUAL ECCENTRIC CGNI'ROL FOR MILL SCREWDOWN BRIEF SUMMARY OF THE INVENTION In beam-backed mills such as are disclosed in Sendzimir U.S. Pats. Nos. 2,479,974 and 3,l47,648, screwdown is accomplished by changing the angular position of eccentric shafts which carry backing casters between spaced eccentrics. A change in the angular position of the eccentric shafts produces a parallel displacement of the work roll in a direction normal to its axis. To obtain deviations from parallelism, i.e. to change the roll profile, each of the eccentrics is provided with an eccentric bushing, and the angular position of each of the bushings is controlled individually. Necessarily these spaced eccentrics are very smalljust enough to cover the screwdown range, and therefore screwdown actuating means must be provided at each end of the eccentric shafts to minimize torsional deflection. Since, however, small eccentrics are essentially self-locking, they cannot be used to control the roll pressure exerted on each eccentric, even through they control precisely the position of the roll.

The present invention provides means for precisely controlling the pressure exerted by each eccentric (through the adjacent casters) upon the roll; and these means control the roll pressure at spaced intervals across the entire width of the work piece.

These is provided a shaft carrying the eccentrics, and each eccentric is connected to outside means for exerting torque upon it and/or for rotating it. In this way torsional deflection of the shaft is avoided and therefore the eccentrics may have much greater eccentricity. When this factor is combined with the use of suitable anti-friction bearings, the eccentrics are far removed from the self-locking range. Furthermore, angular adjustment of these eccentrics results in a roll displacement (screwdown range) which is many times larger than is obtainable in mills heretofore known, so that the mill of the present invention is useful in certain fields which are out of reach of the small eccentric mills, as will be discussed in more detail hereinafter.

DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 is a fragmentary top plan view with parts in cross sections of one embodiment of the invention.

FIG. 2 is a vertical cross sectional view taken on the line 2-2 of FIG. 1.

FIG. 3 is a composite view similar to FIG. 1 showing a second embodiment in the left half and a third embodiment in the right half.

FIG. 4 is a vertical cross sectional view of FIG. 3 also showing the second and third embodiment.

FIG. 5 is a schematic elevational view of an application of the invention; and

FIG. 6 is an enlargement of a central portion of FIG. 5 showing a modification.

DETAILED DESCRIPTION As shown in FIGS. I and 2, the mill is provided with saddles I supported by the rigid beam 2 of the mill housing and spaced evenly across the width of the work piece. Each saddle 1 has two openings to accommodate the eccentrics 3, 3' with their bearings such as the needie bearings 4, 4'. The eccentrics 3, 3' in turn carry shafts 5, 5' which support casters 6, 6' which are mounted upon the shafts in the spaces between adjacent eccentrics 3, 3'. The casters 6, 6' jointly support one component of roll pressure exerted by the working roll 7 along their common generant.

Further description of the invention of FIGS. 1 and 2 will be with respect to the elements 3', 4', 5 and 6', and it will be understood that the parts to be described hereinafter will be duplicated for the

elements

3, 4, 5, and 6.

It will be observed in FIG. 2 that portions of the eccentrics 3' protrude beyond the diameter of the casters 6'. To those protruding portions there are attached the gear segments 8'. These may be attached by screws, bolts, or similar means, and they engage arcuate keyways 9' provided in the protruding portions of the eccentrics 3. A shaft 11' carries pinions l0 keyed thereon and the pinions 10' are in mesh with the respective gear segments 8'. The shaft 11' is located in a saddle or an extension 1" thereof by bearings 12' and the shaft 11' is coupled to actuating means such as the hydraulic actuator 13'.

It will now be clear that a change in the angular position of the shaft 11 produced by operation of the actuator 13' causes a change in the roll gap (screwdown) which will be parallel across the width of the work piece since all the eccentrics 3 are identical.

During rolling, the roll pressure (roll separating force) must be counterbalanced by the torque of the actuator 13', acting through the pinions I0, segments 8', eccentrics 3', casters 6 and shafts 5'. As indicated above, corresponding parts operate through the me

mbers

3, 4, 5, and 6. In order to control the distribution of this torque among the several eccentrics 3' and thus to control the distribution of roll pressure across the width of the strip, the axial position of each pinion 10' is adjustable. This may be accomplished by means of nuts 14' engaging threaded hubs of the pinions 10'. The outer peripheries of the nuts 14 are provided with worm gear teeth which engage worms 15' which can be rotated by means of gear motors I6 and the like. Since the teeth on the segments 8' and the pinions 10' are helical, an axial displacement of a pinion 10' will alTect the share of the load it takes with respect to the total torque exerted by the actuator 13'. The gear motors 16' may be controlled by signals from strip flatness verifying instruments of the automatically produced flat sheets, as will be described hereinafter. A suitable relief valve (not shown) is preferably provided in the hydraulic system of the actuator so that in cast of a surge of roll pressure, as for example during a cobble, the actuators may actually turn in reverse, thereby preventing damage to mill components.

Further advantages of prior art arrangements, as exemplified by US. Pat. Nos. 2,479,974 and 3,147,648, lie in the increased rigidity and sturdiness of the screwdown elements. The eccentric screwdown shafts shown in said patents are limited in diameter by the inside diameter of the casters; and it is therefore necessary to apply torque means to both ends of the eccentric shafts in order to avoid an eccentrically torsional deflection.

On the contrary, while the actuator shaft ll of the present invention fulfills the same role, it is not subject to any limitation as to its diameter. it can be made so heavy, that even though the torque means (hydraulic actuator) is applied to one end only, the torsional deflection will be negligible.

The space limitation of the prior art is still more acute when applied to crown control elements, which are slender eccentric rings surrounding the screwdown eccentrics and having needle bearings inside and out to reduce friction. These elements are moreover subjected to the same roll pressure as the screwdown eccentrics and must, therefore, be made of heat-treated and ground alloy steel. This, of course, increases their cost.

As distinguished from this, crown control according to the present invention does not require separate elements since the screwdown elements serve both purposes. These parts are sturdy and can be made of ordinary machine steel and they are not subjected to roll pressure.

Turning now to FIGS. 3 and 4, the left and right-hand portions of these Figures differ from each other only in the mode of attachment of actuating means to the eccentrics 3 and 3'. In the case of mills where the utmost capacity of the casters 6 is not required so that a greater space between them is permissible the saddle 1 and eccentric 3 may be broadened and the segment 8 may be affixed to the eccentric 3 in a shallow slot 17 therein and the parts may be connected by dowels, screws, or the like as at 18. The tooth segment 8 protrudes from the saddle 1 through a slot 20 provided therein and it protrudes to a position in which it meshes with a pinion as described above. This construction makes it possible to apply the tooth pressure in the plane of symmetry of the eccentric 3.

The structure shown on the right-hand side of FIGS. 3 and 4 difl'eres in that the saddle l' is open. That is to say, there is no continuous bearing around the eccentric 3'. Thus, the free part of the eccentric 3' is accessible and an arm 21 may be attached to it by screws 22 and the arm 21 may be pivotally connected to the piston rod 24 of an oscillating fluid cylinder 23. it will, of course, be understood that each of the eccentrics 3' is provided with the actuating mechanism just described. With the type of saddle shown in the right hand half of FIGS. 3 and 4, with the saddle being open, the saddle is subject to bending moment by the horizontal component of the roll pressure. To counteract this, the base of the saddle where it contacts the beam 2 of the housing is extended to a point a farther away from the eccentric.

To open or close the roll gap, fluid may be admitted to or let out from all the cylinders 23 connected to the eccentrics 3' of a shaft 5 simultaneously. It will be observed that a three-way valve 25 is provided for each cylinder 23 and this valve has connections to a pump or supply of fluid under pressure S to a sump W and to an individual pressure control device, such as the small accumulator 26 which is connected by a suitable valve 25' to both the supply S and the sump W. The several valves 25 for the several cylinders 23 may be arranged in a single line and connected by a shaft 35 so that they may all be operated concurrently. In the third position mentioned above, pressure from each cylinder is controlled individually and independently of the other cylinders.

In the first position of the valve, causing the rolls to close, the roll 7 abuts against its cooperating roll through the work piece which is between the work rolls. The opposite roll does not require positioning so that all the eccentrics can be omitted from its shaft 5. For opening the rolls in the second position of the valve 25, stroke limiters can be provided in the cylinders 23.

It will be clear from the foregoing description that a great advantage is provided by the mechanism just described, in that it permits the use of large eccentricities so that when the eccentrics are mounted in antifriction bearings, they operate far from the self-locking range. When torque is applied to an eccentric, a certain force is exerted by the adjacent casters upon the work roll 7. This force is a function of the magnitude of the torque and of the angular position of the eccentric. Assuming that this force is of a magnitude capable of producing the desired reduction in the thickness of the work piece, the above described feature means that if the entering work piece is changing the thickness, for example becoming thicker, then the eccentric will permit the roll gap to increase while the roll pressure will stay substantially the same. This feature is of fundamental importance in mills for skin-passing" where a predetermined, usually light, percentual elongation must be accurately maintained to produce a work piece (steel strip) having the required physical properties. If the roll gap did not change under the circumstances 30 just outlined, the percentual elongation would have increased with the result that the steel strip would have become harder and less ductile.

A typical application of such a skin-pass mill is in strip processing, for example in a continuous bright-annealing line. A schematic view of such a mill is shown in FIG. 5 and it will be observed that the annealed and cooled strip 27 is passed in succession by two tensioning devices with the skin-pass, mill therebetween. While the strip 27 is passed through the line at a certain tension, the tension is considerably augmented for skinpassing and usually amounts to one-third of the elastic limit of the strip.

As shown, each tensioning device consists of a pulley 28, 28' around which the strip passes and two deflecting pulleys 29, 29', and in some cases

pressure roll chains

30, 30 around each tension pulley, so that with high enough initial tension, the wrapping angle around the tension pulley and its coefficient of friction, a nonslip contact is assured. The tension pulleys 28, 28' are preferably geared together and operated from a common drive, so that with the strip moving from left to right, the pull y 28 is driving and the pulley 28 is driven, while the difference in surface velocities of the two pulleys must be equal to the required percentual elongation of the strip 27. Known compensation drives such as described in US. Pat. No. 2,l94,2 l 2 are usually used for adjustment of the percentage of elongation without jeopardizing the accuracy thereof.

It will be clear that correct roll pressure is a pressure where the tension of the strip 27 is of the desired magnitude (one-third of the elastic limit preferably). If the tension falls, this can be corrected by lowering roll pressure. If not corrected, it is difficult to produce a flat strip. Similarly, if the tension is too high, the strip 27 may stretch irregularly at places outside of the roll bite, producing so-called stretcher-strains" and making the strip unsuitable for many purposes.

in the mill disclosed in FIG. 5, it is easy to fulfill these conditions at all points across the width of the strip and to do this automatically, thus producing a strip that is notonly correctly temper-rolled (skin-passed) but is also perfectly flat. For this purpose, tension indicating meters are provided at points across the strip corresponding to the positions of the eccentrics 3. These meters may be proximity gauges 31 mounted on a rigid beam 32 parallel with the width of the strip. The strip is then subjected to a light but uniform pressure, such as static air pressure. This pressure may be produced in a trough 33 extending all the way across the strip and closely spaced to the strip to restrict escape of air and air under pressure is supplied through the line 34 from a blower or the like. it will be clear that the higher the tension in a particular portion of the strip, the less it will deflect toward the proximity gauge 31. The indications of the gauges 31 may be transmitted in the form of suitable signals to the pressure control device of each cylinder 23 to restore uniform tension across the strip 27. This insures that the flatness is correct and at the same time controls the total pressure to assure correct rolling conditions, including correct tension.

Another quite different benefit of the present invention, when applied to skin-passing and processing lines, is the possibility of providing two pairs of work rolls rather than one. Only one of the pairs is in working contact with the strip, while the other is retracted and kept far enough from the strip to prevent contact, even on wavy spots in the strip.

These skin-passing lines are operated without interruption for weeks at a time and any stoppage for roll changing is intolerable, since the thermal balance of the heat treating part of the line must not be upset. Such an upset produces costly scrap losses. According to the present invention, the operation of withdrawing one and engaging the other pair of work rolls involves only the turn of the eccentrics and takes only a fraction of a second. P10. 5 shows the left-hand pair of rolls 7 in working contact and the right-hand pair 7' out of contact with the strip. Therefore, the left-hand eccentric shafts 5 have their eccentrics 3 turned toward their respective rolls 7, while the right-hand eccentric shafts 5' have their eccentrics 3' turned away from their rolls 7'. The middle shaft 5" has no eccentrics and its casters 6 rotate around fixed centers.

in cases where it is desired to increase still further displacement of the roll, the middle shaft 5" may also be actuated for the purpose. As shown in FIG. 6, the middle shaft 5" may have its eccentrics keyed onto it and a rotary actuator is coupled onto one of its ends to rotate it to one of two positions: to the left as shown in FIG. 6 to engage the roll 7 while disengaging the roll 7'; or to the right to disengage the roll 7 and engage the roll 7'. it will be noted that in the configuration of FIG. 6, the axis of the work roll 7, the casters and eccentrics, all lie in the same plane. These keyed eccentrics may be relatively large to obtain a large displacement of the rolls since in either of the two operating positions the roll pressure passes directly through the center of the eccentrics, so that the eccentrics and the shaft 5 are not subjected to any torque.

It will be clear that numerous modifications may be made without departing from the spirit of the invention and no limitations not specifically set forth in the claims is intended or should be implied.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. in a beam-backed mill for rolling flat articles, said mill having work rolls backed by casters mounted on eccentrics, which are in turn mounted on caster shafts, said caster shafis being disposed in saddles provided between adjacent casters, said eccentrics providing for control of the roll gap; lever means attached to each eccentric and extending beyond the periphery of said casters, screwdown actuating devices, and means individually connecting said lever means and said actuating devices.

2. The structure of claim 1, wherein said eccentrics extend beyond the periphery of said casters so as to expose an arcuate segment thereof for attachment of said lever means.

3. The structure of claim 1, wherein slots are provided in said eccentrics in which said lever means are secured, and slots are provided in said saddles, through which said lever means protrude and oscillate through their screwdown range.

4. The structure of claim 1, wherein said saddles are open so as to expose portions of said eccentrics for attachment thereto of said lever means.

5. The structure of claim 4, wherein the bases of said open saddles are extended beyond said eccentrics to increase the resistance of said saddles to bending.

6. The structure of claim 1, wherein said lever means are provided with gear teeth, and said screwdown actuating means incorporate gear teeth meshing with the teeth on said lever means.

7. The structure of claim 6, wherein an actuator shaft is mounted parallel to said caster shaft beyond the periphery of said casters, and carries a plurality of pinions keyed thereon, said pinions being in mesh, respectively, with the teeth on said levers, whereby a change in the angular position of said actuator shaft results in simultaneous actuation of all the eccentrics to produce parallel movement of said casters.

8. The structure of claim 6, wherein the teeth on said levers and pinions are helical, and means are provided to adjust the axial position of said pinions on said actuator shaft, so as to control the distribution of tooth pressure among the several lever means of said casters.

9. The structure of claim 1, wherein said screwdown actuating means are linear actuators.

10. The structure of claim 9, wherein said linear actuators are fluid cylinders with actuating pistons.

l l. The structure of claim 10, wherein a fluid circuit is provided for all said cylinders, said circuit including a source of fluid pressure, a sump and an individual pressure control for each cylinder, and a valve is provided for each cylinder, all said valves being connected together for simultaneous operation to (a) admit fluid from said source, (b) discharge fluid to sump, or (c) to close both said connections and open a connection to said individual pressure controls.

12. The structure of claim 1, wherein two pairs of work rolls and three pairs of casters are provided, the central pairs of casters having no eccentrics, and only the two pairs of outer casters are connected to said screwdown control means.

13. The structure of claim 12, wherein at least one of the pair of central casters carries eccentrics, said eccentrics being connected to an actuator arranged to shift said casters from one position in which the axes of the casters, caster shafts, and eccentrics, and one of the work rolls lie in the same plane, to a symmetrical position with respect to the other work roll, whereby to engage one pair of work rolls while disengaging the other. 14. The structure of claim 1, in combination with means to deflect a tenioned exiting strip in a direction normal to its plane, and proximity measuring gauges disposed opposite each of said eccentrics to measure the deflection of the strip at that point, the signals from eccentric control means to said proximity gauges serving to actuate the individual IINITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 91,810 Dated September 19, 1972 Inventor) Tadeusz Sendzimir It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1, column 6, lines 6 and 7, the phrase "eccentric,

which are in turn mounted on caster shafts, said caster shafts" should read caster shafts carrying eccentrics, said eccentrics Signed and sealed this 19th day of March 19%..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents USCOMM-DC 60375-P69 FORM PO-1050 [10-69) w u.s. GOVERNMENT rnnmua omcz: mu o-au-au

Claims

1. In a beam-backed mill for rolling flat articles, said mill having work rolls backed by casters mounted on eccentrics, which are in turn mounted on caster shafts, said caster shafts being disposed in saddles provided between adjacent casters, said eccentrics providing for control of the roll gap; lever means attached to each eccentric and extending beyond the periphery of said casters, screwdown actuating devices, and means individually connecting said lever means and said actuating devices.

11. The structure of claim 10, wherein a fluid circuit is provided for all said cylinders, said circuit including a source of fluid pressure, a sump and an individual pressure control for each cylinder, and a valve is provided for each cylinder, all said valves being connected together for simultaneous operation to (a) admit fluid from said source, (b) discharge fluid to sump, or (c) to close both said connections and open a connection to said individual pressure controls.

13. The structure of claim 12, wherein at least one of the pair of central casters carries eccentrics, said eccentrics being connected to an actuator arranged to shift said casters from one position in which the axes of the casters, caster shafts, and eccentrics, and one of the work rolls lie in the same plane, to a symmetrical position with respect to the other work roll, whereby to engage one pair of work rolls while disengaging the other.

14. The structure of claim 1, in combination with means to deflect a tenioned exiting strip in a direction normal to its plane, and proximity measuring gauges disposed opposite each of said eccentrics to measure the deflection of the strip at that point, the signals from said proximity gauges serving to actuate the individual eccentric control means to produce a strip wherein the tension is even all the way across.

15. The structure of claim 14, wherein said deflecting means comprise a trough disposed closely adjacent one side of said strip, and means for maintaining a pressure in excess of atmospheric pressure therein, said proximity gauges being disposed on the side of said strip opposite said trough.