US3884064A

US3884064A - Roll positioning mechanism for rolling mills

Info

Publication number: US3884064A
Application number: US437180A
Authority: US
Inventors: Andrew J Petros; Ronald D Pizzedaz
Original assignee: Mesta Machine Co
Current assignee: MESTA ENGINEERING COMPANY APARTNERSHIP OF PA
Priority date: 1974-01-28
Filing date: 1974-01-28
Publication date: 1975-05-20
Anticipated expiration: 1992-05-20
Also published as: FR2258907B1; DE2502947A1; FR2258907A1; JPS50108151A; JPS5410346B2

Abstract

In a rolling mill, the combination comprises a mill stand housing construction, at least two mill rolls slidably mounted in a window arrangement of the housing construction. The mill rolls have bearing chocks mounted adjacent each end thereof. A pair of roll-positioning cylinder and plunger arrangements respectively span gaps between the roll chocks of an adjacent one of the mill rolls and juxtaposed end portions of the mill housing construction. Hydraulic circuits extend the cylinder and plunger arrangements for bearing engagement with the bearing chocks and the juxtaposed housing portions to position the mill rolls. A counterbalancing piston and cylinder arrangement is coupled to both of the roll-positioning plunger and cylinder arrangements for retracting the plungers in termination of the aforesaid bearing engagement.

Description

United States Patent [191 Petros et a1.

1 1 ROLL POSITIONING MECHANISM FOR ROLLING MILLS [75] Inventors: Andrew J. Petros, Oakdale; Ronald D. Pizzedaz, Springdale, both of Pa.

[73] Assignee: Mesta Machine Company,

Pittsburgh, Pa.

221 Filed: Jan. 28, 1974 21 Appl. No.: 437,180

[ May 20, 1975 Primary ExaminerMilton S. Mehr Attorney, Agent, or Firm-Donn J. Smith [57] ABSTRACT In a rolling mill, the combination comprises a mill stand housing construction, at least two mill rolls slidably mounted in a window arrangement of the housing construction. The mill rolls have bearing chocks mounted adjacent each end thereof. A pair of rollpositioning cylinder and plunger arrangements respectively span gaps between the roll checks of an adjacent one of the mill rolls and juxtaposed end portions of the mill housing construction. Hydraulic circuits extend the cylinder and plunger arrangements for bearing engagement with the bearing checks and the juxtaposed housing portions to position the mill rolls. A counterbalancing piston and cylinder arrangement is coupled to both of the roll-positioning plunger and cylinder arrangements for retracting the plungers in termination of the aforesaid bearing engagement.

19 Claims, 5 Drawing Figures ROLL POSITIONING MECHANISM FOR ROLLING MILLS The present invention relates to mechanism for positioning the rolls of a rolling mill and more particularly to a mechanism of the character described for coarse positioning, for example when roll changes are made. Certain features of the invention can also be employed for gauge control of a moving strip or sheet, or alternatively conventional gauge control means can be utilized in conjunction with the invention, as set forth in detail hereinafter.

Although the roll positioning mechanism of the invention is described primarily in conjunction with a four-high, tandem cold mill, the invention is also applicable to other types of cold mills and also to temper mills, hot mills and the like. Although as described the invention is capable of both coarse and fine mill roll positioning, certain features of the invention as related to coarse positioning can be utilized with conventional gauge control equipment.

For a considerable time there has been a need for simple and effective means for quickly effecting coarse positioning adjustments of mill rolls. In the past, such adjustment was provided primarily by electromechanical screw-downs, hydraulic hold-down cylinders, and the like. Prior positioning mechanisms required complicated mill stand construction and usually suffered from positional inaccuracies, particularly when the same roll position must be held for a considerable period. Operation of conventional equipment required large expenditures of power particularly for rotation of screw-downs under heavy mill loadings. In addition, the heavy dynamic and stationary loadings of a typical rolling mill stand caused screw-downs to develop enormous striction forces whenever rotation thereof was attempted.

Coarse adjustment of mill roll position is often necessary, as the mill must accommodate the range of roll diameters inherent in normal roll life, or wearing cycle. The gauge control system provided on most rolling mills is limited to shorestroke excursions in roll position, owing to limitations dictated by rolling theory and other design considerations. Most desirably, a longer stroke is provided by the roll positioning mechanism of the invention, which in the preferred embodiment is capable of both coarse and fine roll positioning.

In most applications of the invention the roll positioning mechanism imparts a coarse roll position adjustment when a roll change is made either for roll dressing purposes or otherewise. During normal mill operation the conventional gauge control unit can be provided with sufficient stroke to accommodate a range of strip thickness for various coils in a production run. On the other hand, the roll positioning mechanism of the invention is capable of sufficient accuracy and quickness of response for ordinary gauge control operation.

An advantageous feature of the invention unexpectedly incorporates a more recently developed type of gauge control equipment into the hydro-mechanical system of our novel roll positioning mechanism. An example of such gauge control equipment is the Sermes hydraulic gauge control system manufactured by Mesta Machine Company of Pittsburgh, Pa.

We overcome the disadvantages of prior screw-down mechanisms and other conventional roll positioning equipment by providing a roll positioning mechanism capable of functioning in place of the conventional electro-mechanical screw-down mechanism or in place of the conventional hydraulic hold-down cylinders. In addition our novel roll positioning mechanism is capable of delivering a longer stroke more accurately to the desired terminal position. Such roll positioning accuracy and quickness of movement are assured by employment oflocking to prevent positively any further displacement of the roll positioning mechanism. A unique containment for hydraulic fluid prevents inaccuracies of positioning which would result from various types of leakage.

The roll positioning mechanism of our invention constitutes a compact, self-contained system. The use of relatively fewer components parts of this system simplifies manufacture and requires less maintenance, while permitting a rugged design configuration. At the same time the roll positioning mechanism results in more accurate repositioning of the mill rolls. In contrast to conventional roll positioning systems, the positioning mechanism of the invention permits a simplified mill housing construction, as it is not necessary to pass screw-downs or other positioning mechanism through the upper sections of the mill stand housings.

The roll positioning mechanism of the invention can be employed most advantageously for revamping or retrofitting existing rolling mills. Naturally much effort has been expended in minimizing the amount of downtime in rolling mills. Many existing rolling mills, however, are used only 40 to 50 per cent of ultimate capacity, owing to down-time for threading and roll-changing operations. Modern mills that have been designed for operation at 5,000 feet per minute are often being operated at 3,000 to 3,500 feet per minute or thereabouts owing to lack of accurate gauge control or of other accurate positioning of the mill rolls. The mill roll positioning mechanism of the invention can be installed relatively easily in existing rolling mills, with the result that an existing mill can be retrofitted for about onehalf the cost of a new mill. The revamped mill, then, becomes as productive as a new mill of advanced design.

Strip material at the present time is being sold by the lineal foot instead of per pound. In consequence, tons of material can be saved by operation of the rolling mill on the low side of the thickness spec. For this purpose, a very accurate mill roll positioning mechanism is required.

Most desirably, the roll positioning mechanism of the invention is installed on every stand of the rolling mill. The roll positioning mechanism need not be employed for gauge control on every mill stand, but it is desirably used for coarse and fine roll positional adajustments on each stand of the rolling mill. In those rolling mills provided with a constant pass line, use of the roll positioning mechanism of the invention does not interfere with the constant pass line system. In fact, the roll positioning mechanism of the invention facilitates maintenance of the constant pass line. In addition to the Sermes type gauge control mentioned previously and incorporated in a novel and unexpected manner in the illustrated form of the invention, our invention can also be employed with a long stroke bottom or push-up cylinder (with or without gauge control) found on many types of hydraulic rolling mills.

I accomplish these desirable results by providing in rolling mill, the combination comprising a mill stand housing construction, at least two mill rolls slidably mounted in window means of said housing construction, said mill rolls having bearing chocks mounted adjacent each end thereof, a pair of roll positioning cylinder and plunger arrangements respectively spanning gaps between the roll chocks of an adjacent one of said mill rolls and juxtaposed end portions of said mill housing construction, hydraulic circuits for extending said cylinder and plunger arrangements for bearing engagement with said bearing chocks and said juxtaposed housing portions, and a counterbalancing piston and cylinder arrangement coupled to both of said plunger and cylinder arrangements for retracting said plungers in termination of said bearing engagement.

I also desirably provide a similar roll positioning mechanism including a roll positioning platform inserted through said window means, said cylinder and plunger arrangements being rigidly mounted respectively adjacent the ends of said platform, and said counterbalancing piston and cylinder arrangement is coupled between said housing end portions and an intermediate section of said platform.

I also desirably provide a similar roll positioning mechanism wherein a pair of gauge control plunger and cylinder arrangements are interposed respectively between said bearing chocks and said roll positioning plunger and cylinder arrangements.

I also desirably provide a similar roll positioning mechanism wherein each of said hydraulic circuits is self-contained substantially within the associated one of said roll positioning plunger and cylinder arrangements.

I also desirably provide a similar roll positioning mechanism wherein each of said hydraulic circuits includes an expandable bladder having a pressurized gaseous fluid sealed therein and contained within a cavity formed in the associated roll positioning plunger.

I also desirably provide a similar roll positioning mechanism wherein each of said roll positioning plungers is hollow, and said plunger hollow is shaped to contain substantially all of the hydraulic fluid employed in the associated one of said roll positioning plunger and cylinder arrangements.

We are aware of the efforts of others in the fields of hydraulic roll positioning and gauge control, as typified by the following references:

Blain Patent No. 3 075,417 Metzger Patent No. 3 l I 1,047 Neumann Patent No. 3,124,982 Kajiwara Patent No. 3,326,028 Scott Patent No. 3 362,204 Guillot Patent No. 3 527,074 Guillot Patent No. 3 538,727

Mesta Machine Company Bulletin Gage Control Constant Force Rolling and Strip Guiding, Electrohydraulic Roll Positioning System (Sermes). However, none of these references nor any combination thereof discloses the novel features set forth in the foregoing paragraphs.

During the foregoing discussion, various objectives, features and advantages of the invention have been set forth. These and other objectives, features and advantages of the invention together with structural details thereof will be elaborated upon during the forthcoming description of certain presently preferred embodiments of the invention and methods of practicing the same.

In the accompanying drawings I have shown certain presently preferred embodiments of the invention and have illustrated certain presently preferred methods of practicing the same wherein:

FIG. I is a front elevational view, partially in section, of a rolling mill stand incorporating the roll positioning mechanism of the invention;

FIG. 1A is a similar but partial view of the apparatus shown in FIG. 1 with a plunger and cylinder arrangement thereof in the fully extended position;

FIG. 1B is a similar but partial view of the apparatus shown in FIG. 1, but illustrating another embodiment of barrier means for hydraulic fluid;

FIG. 2 is a horizontally sectioned view of the mill stand as shown in FIG. 1 and taken along reference line IIII thereof;

FIG. 3 is a side elevational view of the mill stand shown in FIG. 1, and partially sectioned along reference lines III-III thereof.

With a more detailed reference now to the several drawing figures, one arrangement of my novel roll positioning mechanism, denoted generally at reference numeral 10 is incorporated in a four-high rolling mill stand 12 having a pair of work rolls l4, l6 and a pair of back-up rolls respectively therefor, one of which is denoted by the reference numeral 18. A mill stand 12 includes in this example a pair of

housing members

20, 22, which are spaced in the usual fashion as evident from FIGS. 1 and 2 and each of which is provided with window 24 as shown best in FIG. 3. The back-up rolls are provided with bearing chocks 26 which are mounted in the housing windows 24. The work rolls 14, 16 are similarly provided and mounted.

Forming part of the roll positioning mechanism 10 is a platform 28 which extends between the mill stand housings 20, 22 (FIGS. 1 and 2) and protrudes through the upper portions respectively of the windows 24 of these housings. Mounted on the platform 28 are a pair of roll positioning cylinders 30 and a pair of gauge control cylinders 32 (FIGS. 1, 1A). A hollow plunger 34 protrudes from the upper ends of each of the roll positioning cylinders 30 and engages the underside of the associated housing cross-pieces 36. The roll positioning cylinders 30 and the gauge control cylinders 32 will be described below in greater detail. For the moment it will suffice to point out that the roll positioning cylinders 30 and their plungers 34 and the associated components of the roll positioning mechanism 10 bridge the gaps between the housing cross-pieces 36 and the upper back-up roll chocks 26.

At an intermediate position between the mill stand housings 20, 22 a counterbalancing or hold-up cylinder 38 is mounted on a pair of brackets 40 (FIG. 3) extending between the housing cross-pieces 36. The cylinder 38 is provided with a suitable piston, a piston rod 42 of which is pivoted desirably to the central region of the roll positioning platform 28 through a clevis joint 44 or the like. The cylinder arrangement 38 functions to ensure a continuous engagement between the upper surfaces of the roll positioning plungers 34 and the respective under surfaces 46 of the housing cross-pieces 36 during operation of the rolling mill stand 12. In this connotation the cylinder arrangement 38 also supports the weight of the roll positioning platform 28 and associated components of the roll positioning mechanism 10. More importantly, the cylinder arrangement 38 applies sufficient upward force (arrow 48) to the platform 28 to ensure return of the roll positioning plungers 34 to their fully retracted positions (FIG. 1) from their fully extended positions (FIGv 1A) or from an intermediate position.

The space between the roll positioning platform 28 and the upper back-up roll chocks 26 can be bridged by a pair of saddles 50 mounted respectively on, or formed integrally with, the backup roll chocks 26 (FIGS. 1 and 3) and engaging the adjacent under surfaces of the platform 28. If the platform 28 were a solid member of uniform thickness, i. e. if the pancake cylinder arrangements 32 and associated components were omitted, the upper back-up roll 18 would be positioned solely by the roll positioning cylinder arrangements 30. In the illustrated arrangement, however, the roll positioning cylinlders 30 provide a coarse setting for the back-up roll chocks 26, while the gauge control or pancake cylinders 32, which are mounted in tandem with the roll positioning cylinders 30 afford a fine adjustment. It will be understood of course that the gauge control cylinders 32 can be mounted elsewhere instead of on the roll positioning platform 28. It will be understood that other conventional gauge control mechanism can be substituted.

The gauge control cylinders 32 and associated components are described in Mesta Machine Company brochure noted above. Briefly, the pancake cylinder arrangements 32 (which have a very short stroke) are actuated by respective plunger mechanisms denoted generally by the reference numerals 54 (FIG. 2) and are enclosed within the platform 28 by a pair of

flexible plates

56, 58, the outer plate 58 of which is sealed to the underside of the platform 28 by a peripheral gasket 60. The plungers 54 are coupled to the pressure chambers 55 of the gauge control cylinders 32 through suitable conduits (not shown) extending through the platform 28.

On the blank ends of the roll positioning cylinders 30 and the gauge control cylinders 32 are closed by a common separator plate or disc 62 (FIGS. 1, 1A). A peripheral edge portion of the separator plate 62 is inserted between the opposing edges of the roll position ing cylinders 30 and the gauge control cylinders 32 to maintain the separator plate 62 in its proper position.

Each of the roll positioning plungers 34 is provided with an internal sealed chamber 64 which is shaped to contain substantially all of the hydraulic fluid employed in each of the cylinders 30. In the illustrated application such hydraulic fluid desirably but not necessarily is of grease like consistency, containing graphite, and is of known composition.

Also contained within the plunger cavity 64 is a sealed bladder 66 having a pressurized'gaseous filling sealed therein and positioned generally in the upper regions of the plunger cavity 64. In an exemplary application of the invention as illustrated, the bladder 66 can be fabricated from a known material compatible with the hydraulic fluid. The bladder 66, therefore, desirably contains a suitably pressurized an inert gaseous fluid such as nitrogen and serves as a compatible barrier between the contained nitrogen and the hydraulic fluid filling the balance of the plunger cavity 64.

Alternatively as shown in FIG. 1B a floating piston can be used as barrier means between the hydraulic medium and the inert gas, contained respectively in variable gas chamber 67a and variable hydraulic chamber or plunger cavity 64. The piston 67 is provided with a rim or flange 69 for stability and suitable sealing means such as O-ring 71.

The self-contained hydraulic circuit of each roll positioning plunger and cylinder arrangement 30-34 further includes a stop valve 68 mounted on an upper protruding portion of the plunger 34 by means of connecting

conduits

70, 72 respectively which secure the stop valve 68 to the adjacent wall surface of the plunger 34 (FIGS. 1 and 2). As evident from a comparison of FIGS. 1 and IA that portion of the plunger 34 to which the valve 68 is thus attached always protrudes from the associated cylinder 30 and each stop valve 68 moves with its associated plunger 34. Desirably the

valve conduits

70, 72 are rigidly secured to the adjacent wall surface of the plunger 34 by threading or by seal-welding or the like. When thus located the connecting conduits communicate with

respective passages

74, 76 extending through the adjacent wall section of the plunger 34.

Upon opening the stop valves 68 and relaxing the counterbalancing or hold-up cylinder 38 (all of which can be operated remotely, if desired), the bladders 66 expand (or the floating pistons 67 move downwardly) and force hydraulic fluid out of the plunger cavities 64 or 64' through connecting

passages

74, 76 and into pressure chambers 78 (FIG. 1A) of the roll positioning cylinders 30. This increases the bearing engagement between the plungers 34 and the mill stand housing cross-pieces 36, with the result that the platform 28, the upper back-up roll 18 and associated components of the mill stand 12 are forced downwardly toward the limiting position shown in FIG. 1A.

At the latter position of the roll positioning mechanism 10 a residual quantity of hydraulic fluid remains within the plunger cavities 64 as make up fluid in the event of leakage. The aforementioned limiting position of the plunger 34 is determined by

circumferential shoulders

80, 82 formed respectively on the inner surfaces of the cylinders 30 and the outer surfaces of the plungers 34 (FIG. 1A). When the desired extended position of the plungers 34 is attained, the stop valves can be closed to lock the roll positioning platform 28 in place.

As the plunger 34 is withdrawn toward its limiting retracted position (FIG. 1), by opening stop valves 68 and retracting counterbalancing cylinder 38, hydraulic fluid flows in the opposite direction through the

plunger passages

74, 76 until, at the limiting retracted plunger position (FIG. 1) substantially all of the hydraulic fluid is again retained within the plunger cavity 64. At this position (FIG. 1) of the plungers 34 the full retraction of the plungers 34 into the roll positioning cylinders 30 is delimited by contact of the inverted, domed undersurfaces 84 of the plungers 34 with the blank end separator plates 62 respectively. As hydraulic fluid is thus forced into the plunger cavities 64, the gas-filled bladders 66 are forced to contract toward their FIG. 1 condition.

The pressure chambers 78 of the roll positioning cylinders 30 are sealed by means of hydraulic packings 86 containing O-rings 88, which are seated on the plungers 34 in this example against the limiting shoulders 82 respectively.

When the bladders 66 are thus constricted in a controlled manner by means of the stop valves 68, hydraulic fluid is forced out of the pressure chambers 78 of the roll positioning cylinders 30 and returned to the plunger cavities 64 by retractional forces desirably and constantly exerted upon the plungers 34 by the pull-up cylinder 38 which continuously urges the roll positioning mechanism 10 against the housing cross-piece 36 as explained previously. To a limited extent the return of some or all of the hydraulic fluid into the plunger cavity 64 is also aided by the reactionary forces exerted by the upper back-up roll chocks 26 and the saddle members 50 against the under surfaces of the platform 28.

As the bladder 66 expands or contracts depending upon the position of the counterbalancing cylinder 38, hydraulic fluid flows between the plunger cavities 64 and the pressure chambers 78 of the cylinders 30 through the

passageways

74, 76. When the desired position of the roll positioning mechanism 10 is attained the stop valves 68 are closed, a predetermined quantity of the hydraulic fluid is locked in each of the cylinder chambers 78. This affords a coarse adjustment for the upper back-up roll 18 and associated components of the mill stand 12. Such adjustment can be changed readily as the mill rolls are dressed to compensate for wear during operation of the rolling mill. The fine adjustment of the roll positioning mechanism 10, i. e. the gauge control feature thereof, is afforded by the very small movements or stroke of plungers 90 of the gauge control cylinders 32.

The roll positioning mechanism 10 of the invention therefore provides both coarse and fine adjustments in mill roll position during the operation of the rolling mill. In addition, the roll positioning platform 28 can be quickly raised and lowered, for example for roll changing purposes or whenever a relatively wide opening between the work rolls is desirable. In contrast, the slow moving mechanism of the prior art require considerable expenditures in time and power for coarse roll positioning adjustments or for retraction during the roll changing operations.

The operation of the roll positioning mechanism 10 will now be described in conjunction with a typical roll change and production sequence in the rolling mill stand 12. Initially, the hold-up cylinder 38 draws the roll positioning platform 28 toward the top end of the mill stand 12, i.e. against the crosspieces 36 of the mill housings 20, 22. At this time the monitoring valves 68 are opened so that the coarse positioning plungers 34 are retracted into the cylinders 30. As the plungers 34 are forced into the cylinders 30 hydraulic fluid is forced from the pressure chambers 78 (FIG. 1A) of the cylinders 30 through the passageways 74, the monitoring valves 68, and thence through the associated passageways 76 and into the plunger cavities 64, until the fully withdrawn position of the plungers 34 is attained (FIG. 1). As the hydraulic fluid or grease flows into the plunger cavity 64 the filling of inert pressurized gas within the bladders 66 is compressed further such that the bladders assume a shape approximating that shown in FIG. 1.

After the hydraulic fluid has been substantially removed from the cylinder chambers 78 the monitoring valves 68 are closed so that the hold-up cylinder no longer need counteract the forces exerted by the com pressed gas within the bladders 66. At this time, the gauge control plungers 90 are also fully retracted.

As the aforementioned sequence of operations takes place, the conventional balancing plungers (not shown) normally provided in the mill stand 12 can be actuated to raise the backup roll chocks 26 and the back-up roll 18 to the position thereof approximately as shown in FIG. 1. The back-up roll chocks 26 therefore remain in firm contact with the roll positioning saddles 50 which in turn engage the undersurface of the roll positioning platform 28. At this time the work rolls 14, 16 can be withdrawn and replacement work rolls substituted. Any suitable conventional roll changing procedure can be utilized or alternatively the roll changing procedures described and claimed in copending coassigned applications of A. .l. Petros for MILL ROLL CHANGING SYSTEM INCLUDING A ROLL BUGGY filed Dec. 28, 1973, Ser. No. 429,345 and for MILL ROLL CHANGING SYSTEM INCLUDING A CANTILEVERED ROLL ASSEMBLY filed Dec. 28, I973, Ser. No. 429,344 or in coassigned U.S. Pat. No. 3,451,244 to Stover et al. can be employed.

After insertion of the new work rolls (in faced contact), the back-up roll balance plungers are retracted to lower the back-up roll 18 into faced contact with the upper work roll 14. At the same time or shortly thereafter the monitoring valves 68 are opened. This operation, together with relaxation of the hold-up cylinder 38 allows hydraulic fluid to flow, under impetus of the pressurized bladders 66, from the plunger cavity 64 in a now reversed direction through the

passageways

74, 76 and the monitoring valves 68 into the pressure chambers 78 (FIG. 1A) of the cylinders 30. The roll positioning plungers 34 are then forcefully extended to cause the saddles 50, platform 28, and the roll positioning cylinders 30 and their plungers 34 to bridge forcefully the spaces between the back-up roll chocks 26 and the cross-piece 36 of the mill stand 26. At this point, the mill stand 12 is completely leveled.

The proper roll gap for strip reduction between the work rolls 14, 16 can now beestablished. For this purpose the gauge control plungers are extended a predetermined small distance by slight extension of their respectively associated plunger mechanisms 54. The monitoring valves 68 of the roll positioning cylinders 30 are then closed to prevent any further transfer of hydraulic fluid between the plunger cavities 64 and the pressure chambers 78 of the cylinders 30. The roll positioning platform 28 of the roll positioning mechanism 10 is now locked at a fixed height relative to the cross-pieces 36 of the mill stand

housings

20, 22. An upward force (arrow 48) is continuously applied by the hold-up cylinder 38 for a proper engagement between the plungers 34 and the cross-pieces 36 respectively.

The roll balance plungers for the upper work roll chocks 52 and the upper back-up roll chocks 26 are now extended and the gauge control plungers 90 are fully retracted to establish the proper roll gap for strip reduction between the work rolls 14, 16.

The mill stand 12 is now ready for threading and strip reduction in the conventional manner. With strip passing between the work rolls 14, 16, gauge correction is made by appropriate movements of the gauge control plungers 90 through the use of conventional sensing and control circuitry (not shown) coupled to their plunger mechanisms 54. With the coarse roll positioning adjustment now having been made, as described above, the stop valves 68 remain closed such that the aforesaid coarse adjustment is now locked into the roll positioning mechanism 10 at whatever elevation of the platform 28 is required. Such elevation is determined by the amount of hydraulic fluid exchanged between the pressure chambers 78 of the cylinders 30 and the plunger cavities 64 prior to closing of the monitoring valve 68. Subsequent positioning of the upper back-up roll 18 and upper work roll 14 is thereafter made by the gauge control plungers 90 until a coarse roll positioning adjustment is again required. A coarse adjustment may be required periodically owing to dressing of the work rolls I4, 16 or the back up rolls 18 or both or whenever a roll change is necessary for any reason. In the absence of sufficient wear in the mill rolls or any of them requiring a coarse adjustment, the small stroke of the gauge control plungers 90 is sufficient to accommodate the range of strip thickness for various coils in a production run.

From the foregoing it will be seen that a novel and efficient roll positioning mechanism for rolling mills has been described herein. The descriptive and illustrative materials employed herein are utilized for purposes of exemplifying the invention and not in limitation thereof. Accordingly, numerous modifications of the invention will occur to those skilled in the art without departing from the spirit and scope of the invention. Moreover, it is to be understood that certain features of the invention can be used to advantage without a corresponding use of other features thereof.

We claim:

1. In a rolling mill, the combination comprising a mill stand housing construction, at least two mill rolls slid ably mounted in window means of said housing construction, said mill rolls having bearing chocks mounted adjacent each end thereof, a pair of roll positioning cylinder and plunger arrangements respectively spanning gaps between the roll chocks of an adjacent one of said mill rolls and juxtaposed end portions of said mill housing construction, hydraulic circuits for extending said cylinder and plunger arrangements for bearing engagement with said bearing chocks and said juxtaposed housing portions to position said rolls, and a counterbalancing piston and cylinder arrangement coupled to both of said plunger and cylinder arrangements for retracting said plungers in termination of said bearing engagement.

2. The combination according to claim 1 wherein a pair of saddle members are interposed respectively between said cylinder and plunger arrangements and said bearing chocks.

3. The combination according to claim 1 including a roll positioning platform inserted through said window means, said cylinder and plunger arrangements being rigidly mounted respectively adjacent the ends of said platform, and said counterbalancing piston and cylinder arrangement is coupled between said housing end portions and an intermediate section of said platform.

4. In a rolling mill, the combination comprising a mill stand housing construction, at least two mill rolls slidably mounted in window means of said housing construction said mill rolls having beaming chocks mounted adjacent each end thereof, a pair of roll positioning cylinder and plunger arrangements respectively spanning gaps between the roll chocks of an adjacent one of said mill rolls and juxtaposed end portions of said mill housing construction, hydraulic circuits for extending said cylinder and plunger arrangements for bearing engagement with said bearing chocks and said juxtaposed housing portions, a counterbalancing piston and cylinder arrangement coupled to both of said plunger and cyliner arrangements for retracting said plungers in termination of said bearing engagement, and a pair of guage control plunger and cylinder arrangement interposed respectively between said bearing chocks and said roll positioning plunger and cylinder arrangements.

5. The combination according to claim 4 wherein the gauge control cylinders and the roll positioning cylinders are mounted back to back respectively, and a common blank-end plate is interposed therebetween.

6. The combination according to claim 1 wherein each of said hydraulic circuits is self-contained substantially within the associated one of said roll positioning plunger and cylinder arrangements.

7. In a rolling mill, the combination comprising a mill stand housing construction, at least two mill rolls slidably mounted in window means of said housing construction, said mill rolls having bearing chocks mounted adjacent each end thereof, a pair of roll positioning cylinder and plunger arrangements respectively spanning gaps between the roll chocks of an adjacent one of said mill rolls and juxtaposed end portions of said mill housing construction, hydraulic circuits for extending said cylinder and plunger arrangements for bearing engagement with said bearing chocks and said juxtaposed housing portions, a counterbalancing piston and cylinder arrangement coupled to both of said plunger and cylinder arrangements for retracting said plungers in termination of said bearing engagement, each of said hydraulic circuits being self-contained substantially within the associated one of said roll positioning plunger and cylinder arrangements, each of said roll positioning plungers being hollow, and said plunger hollow being shaped to contain substantially all of the hydraulic fluid employed in the associated one of said roll positioning plunger and cylinder arrangements.

8. The combination according to claim 7 wherein each of said plunger hollows is coupled to a pressure chamber within the associated cylinder through passage means formed at least partially within a wall portion of said plunger.

9. The combination according to claim 8 wherein a valved conduit is mounted on said plunger for movement therewith, said valved conduit being interposed in said passage means.

10. The combination according to claim 7 wherein expandable pressure means are contained in each of said plunger hollows for forcing at least a portion of said hydraulic fluid out of said hollows upon relaxation of said counterbalancing piston and cylinder arrangement.

11. The combination according to claim 10 wherein each of said pressure means include an expandable bladder having sealed therein a filling of pressurized gaseous fluid.

12. The combination according to claim 10 wherein each of said pressure means include a floating piston separating said hydraulic fluid and a pressurized gaseous filling confined in the associated hollow.

13. In a rolling mill, the combination comprising a mill stand housing construction, at least two mill rolls slidably mounted in a window means of said housing construction, said mill rolls having bearing chocks mounted adjacent each end thereof, a pair of roll positioning cylinder and plunger arrangements respectively spanning gaps between the roll chocks of an adjacent one of said mill rolls and juxtaposed end portions of said mill housing construction, hydraulic circuits for extending said cylinder and plunger arrangements for bearing engagement with said bearing chocks and said juxtaposed housing portions, a counterbalancing piston and cylinder arrangement coupled to both of said plunger and cylinder arrangements for retracting said plungers in termination of said bearing engagement, each of said hydraulic circuits being self-contained substantially within the associated one of said roll positioning plunger and cylinder arrangements, and each of said hydraulic circuits including an expandable bladder having a pressurized gaseous fluid sealed therein and contained within a cavity formed in the associated roll positioning plunger.

14. The combination according to claim 1 including each of said roll-positioning plungers being hollow, and said plunger hollows being shaped to contain substantially all of the hydraulic fluid employed in said rollpositioning plunger and cylinder arrangements.

15. The combination according to claim 1 including each of said roll-positioning plungers being hollow, and expandable pressure means positioned in each of said plunger hollows for forcing at least a portion of contained hydraulic fluid out of said hollows upon relaxation of said counterbalancing piston and cylinder arrangement.

16. The combination according to claim I wherein said roll-positioning plunger and cylinder arrangements are further dispossed in replacement of conventional screwdowns or similar urging means.

17. The combination according to claim 4 including each of said hydraulic circuits being self contained substantially within the associated one of said rollpositioning plunger and cylinder arrangements.

18. The combination according to claim 4 including each of said roll plungers being hollow. and said plunger hollows being shaped to contain substantially all of the hydraulic fluid employed in the associated one of said roll-positioning plunger and cylinder arrangements. I

19. The combination according to claim 4 including each of said roll-positioning plungers being hollow, and expandable pressure means contained in each of said plunger hollows for forcing at least a portion of contained hydraulic fluid out of said hollows upon relaxation of said counterbalancing piston and cylinder arrangement.

Claims

1. In a rolling mill, the combination comprising a mill stand housing construction, at least two mill rolls slidably mounted in window means of said housing construction, said mill rolls having bearing chocks mounted adjacent each end thereof, a pair of roll positioning cylinder and plunger arrangements respectively spanning gaps between the roll chocks of an adjacent one of said mill rolls and juxtaposed end portions of said mill housing construction, hydraulic circuits for extending said cylinder and plunger arrangements for bearing engagement with said bearing chocks and said juxtaposed housing portions to position said rolls, and a counterbalancing piston and cylinder arrangement coupled to both of said plunger and cylinder arrangements for retracting said plungers in termination of said bearing engagement.

14. The combination according to claim 1 including each of said roll-positioning plungers being hollow, and said plunger hollows being shaped to contain substantially all of the hydraulic fluid employed in said roll-positioning plunger and cylinder arrangements.

16. The combination according to claim 1 wherein said roll-positioning plunger and cylinder arrangements are further dispossed in replacement of conventional screwdowns or similar urging means.

17. The combination according to claim 4 including each of said hydraulic circuits being self contained substantially within the associated one of said roll-positioning plunger and cylinder arrangements.

18. The combination according to claim 4 including each of said roll plungers being hollow, and said plunger hollows being shaped to contain substantially all of the hydraulic fluid employed in the associated one of said roll-positioning plunger and cylinder arrangements.