US3610494A

US3610494A - Strip steering roll assembly

Info

Publication number: US3610494A
Application number: US855820A
Authority: US
Inventors: Carl H Minton
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-09-08
Filing date: 1969-09-08
Publication date: 1971-10-05
Anticipated expiration: 1988-10-05

Abstract

A guide roll assembly for effecting lateral displacement of running strip from an offset to a centered position and for compensating for any tendency of the strip to run askew. A pair of rolls are carried by a frame which is pivoted for movement in a horizontal plane about the centerline of the exiting strip. The entry roll is tilted in coordination with its lateral displacement.

Description

United States Patent Carl H. Minton ADS Machinery Corp. P.0. Box 1027, Warren, Ohio 44482 Sept. 8, 1969 Oct. 5, 1971 Inventor Appl. No. Filed Patented STRIP STEERING ROLL ASSEMBLY 13 Claims, 16 Drawing Figs.

Int. Cl B65h 25/26 Field 01 Search 226/3, 18-23 [56] 7 References Cited UNITED STATES PATENTS 2,797,091 6/1957 Fife 226/22 3,054,547 9/1962 Alexeff..... 226/21 X 3,411,683 11/1968 Bartles 226/21 Primary ExaminerRichard A. Schacher Attorney leter L. Klempay ABSTRACT: A guide roll assembly for effecting lateral displacement of running strip from an offset to a centered position and for compensating for any tendency of the strip to run askew. A pair of rolls are carried by a frame which is pivoted for movement in a horizontal plane about the centerline of the exiting strip. The entry roll is tilted in coordination with its lateral displacement.

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AGENT PATENTED mm 5 mm sum 2 [1F 4 N O T N M H L R A C mm mm AGENT PATENTEU 0m 5197i 3610.494

SHEET 3 [1F 4 FEEDBACK TRANSDUCER ACTUATION CIRCUIT FIG. IO

mvm'mk. CARL H. MINTON mA/fw AGENT PAIENTEIIIIJ 5m 3610.494

' SHEET 0F 4 INVENTOR. CARL H. MINTON BY 641M AGENT STRIP STEERING ROLL ASSEMBLY This invention relates to apparatus for guiding strip and more particularly to such apparatus which automatically restores a running strip to a centered position and which simultaneously and in coordination with the amount of lateral movement necessary to restore the running strip to the desired path of travel compensates for any tendency of the strip to run askew.

In the processing of metal strip in, for example, a continuous annealing line, the path of travel of the strip is of a substantial length as the strip is passed through the various cleaning and treating operations. In order to assure uniformity of the end product and to realize the economies of continuous operation it is essential that the strip move through the processing line at a uniform rate of speed. It is also essential that the centerline of .the path of travel of the strip remain at least nearly coincident with the centerline of the processing apparatus. Any deviation of the strip beyond narrow tolerances from the centerline may result in the edge of the strip-contacting fixed portions of the processing apparatus with resulting damage to the strip and/or the apparatus. If the deviation of the strip becomes excessive it is possible for the strip to become either jammed or torn resulting in costly and time-consuming rethreading of the entire processing line. Irregularities in the thickness of the strip such as may result during rolling operations, and unevenly worn pinch rolls driving the strip through the processing apparatus are among the factors causing the strip to deviate from the desired path of travel. It is therefore desirable to provide, at one or more points along the path of travel of the strip throughout the processing apparatus, steering roll assemblies which are capable of repositioning the strip when the same has deviated from the desired path of travel.

Steering roll assemblies have been proposed in which the strip is entrained over a roller which may be tilted or skewed, either about a pivot point at one end or at the midpoint of the roll to cause the strip to spiral toward the centerline of the processing equipment. However, where light gauge or fragile strip material is being processed these steering assemblies impose substantial forces on the edge portions of the strip which forces are likely either to fracture the edges of the strip or to stretch the edges, compounding the problem of strip deviation in the latter portions of the processing apparatus. Another disadvantage of the prior steering roll assemblies is the tendency of these assemblies to overcompensate for deviation of the strip thus resulting in a hunting-type operation in which the strip is moved from an offset position on one side of the centerline of the apparatus to an offset position on the opposite side of the center of the centerline and then back towards its initial position. While this operation gradually brings the strip toward the desired position it is preferable to correct any sideways deviation of the traveling strip without such hunting.

It is the primary object of the present invention to provide a steering roll assembly for use in a strip-processing line which is capable of rapidly compensating for any offset of the strip from the desired centerline without subjecting the edge portions of the strip to excessive stresses or strains. In accordance with the principles of the invention this is accomplished by providing a first roll which is offset in proportion to the amount of deviation of the strip from a desired centerline and which is simultaneously rotated so as to spiral the strip gradually towards the desired centerline and a second roll spaced from the first roll which further redirects the strip to the desired centerline.

A further object of the present invention is the provision of a steering roll assembly for use in a strip-processing line which is capable of being rapidly adjusted to accommodate various amounts of deviation of the running strip from the desired path of travel. This is accomplished in the present invention by providing a linkage arrangement for controlling the rotational motion of the support of the first roll relative to the amount of sideways displacement of the roll which may be readily and easily adjusted to accommodate different widths of strip.

Another object of the present invention is the provision of a steering roll assembly for use in a strip-processing line which is capable of accurately repositioning the running strip on the desired centerline without hunting or oscillation. In the present invention this is accomplished by the combined guiding and translating actions of the two rolls and by the sensing of the deviation of the strip from the desired centerline prior to the steering roll assembly rather than at the exit end of the assembly.

A further object of the present invention is the provision of a steering roll assembly for use in a strip-processing line which is of simple yet rugged and reliable construction.

The above and other objects and advantages of my invention will become apparent upon consideration of the following specification and the accompanying drawings wherein there is shown a preferred embodiment of the invention.

In the drawing:

FIG. 1 is a schematic elevational view of a continuous stripannealing line;

' FIG. 2 is a plan view of the strip-guiding roll assembly of my invention;

FIG. 3 is a side elevational view of the strip-guiding roll assembly of FIG. 2.

FIG. 4 is a vertical sectional view along the line IVlV of FIG. 2;

FIG. 5 is a vertical sectional view taken along the line VV of FIG. 2;

FIG. 6 is a transverse sectional view taken along the line VI-VI of FIG. 3;

FIG. 7 is an elevational sectional view taken along the line VII--VII of FIG. 6;

FIGS. 8 and 9 are elevational sectional views taken along the lines VIII-VIII and IX-IX, respectively, of FIG. 6;

FIG. 10 is a highly schematic showing of the control circuitry of the strip-guiding roll assembly;

FIG. 11 is a schematic plan view of the strip-guiding roll assembly, showing the positions of the entry and exit rolls when the strip is traveling in its normal, centered position;

FIG. 12 is a view similar to that of FIG. II but showing the positions of the rolls when the strip is offset to the right of the equipment centerline; and

FIGS. 13-16 are schematic elevational views showing modifications of the strip-guiding roll assembly of the present invention to accomodate different strip travel paths.

In FIG. 1 there is illustrated a strip-annealing line of a type well known in the art. In such an annealing line a metallic strip 10 of, for example, steel or brass, is run from an uncoiler 11 through a shear and welder 12 to a looper 13. The strip is subsequently subjected to a cleaning and drying operation, indicated schematically at 14, and is then passed at a uniform rate of speed through an annealing furnace 15. The annealed strip is then passed through a second looper 16 and a shear 17 to a coiler 18. In order to allow the continuous operation of the annealing line and to permit uniform rate of travel of the strip 10 through the annealing furnace 15, a second uncoiler 11' is provided and when the first coil of strip 11 is exhausted, the tail end of this strip is stopped at the welder l2 and the leading end of the coil of strip on the uncoiler 11' is threaded into the welder 12 and welded to the tail end of the previous coil of strip. During this operation strip is withdrawn from the looper 13 to maintain the uniform rate of speed of the strip 10 through the cleaning operations 14 and the annealing furnace 15. In like manner the second looper 16 serves to temporarily store strip passing out of the annealing furnace 15 when a full coil of strip has been formed on the coiler I8 and a second coiler 18' is being brought into operation. As was discussed above, various factors such as nonuniform transverse thickness of the strip 10 may cause the strip to move to the right or left of the center line of the equipment. Such deviation of the strip from the desired path of travel is corrected by the use of the strip guiding roll assembly 20 which se'nses any deviation of the strip from the centerline of the annealing line, shifts the strip 10 back to the desired path of travel, and compensates for any tendency of the strip to drift to the right or left of this desired path. While the strip-guiding assemblies 20 are shown as being located at the exit of the first looper 13 and at the exit of the annealing furnace 15 it will be understood that these locations are illustrative only and that the stripguiding assemblies may be located at other points along the path of travel of the strip 10, the particular locations being determined by the arrangement of the particular processing line with which the guiding devices 20 are used.

Referring now to FIGS. 2-9, the strip-guiding roll assembly of my invention will now be described. The strip-guiding assembly 20 is provided with a rectangular frame or base 21 which is securely fastened to a suitable foundation 21' with the longitudinal centerline of the base 21 coincident with the centerline of the strip-annealing line. Received within the frame 21 is a subframe 22. The subframe 22 is pivotally connected to the frame 21 at one of the subframe 22 on its longitudinal centerline by a vertical pivot 23 and is provided at its opposite end with a pair of rollers 24 which move in ways 25 secured to a crossmember of the main frame 21. Midway between the rollers 24, the longitudinal centerline of the subframe 22, the subframe is provided with a horizontally extending tongue 26 which is connected to the clevis 27 of a hydraulic cylinder 28 which is secured to the base 21. Adjusted stops 29 mounted on the main frame 21 limit the lateral movement of the subframe 22.

Cylindrical rolls 30 and 31 are carried by the subframe 22. The roll 31 is located with its cylindrical surface tangent at its midpoint to the axis of the pivot pin 23 and with its longitudinal axis at right angles to the longitudinal centerline of the subframe 22. The roll 31 is joumaled in pillow blocks 32 which are mounted on support members 33 secured at their lower ends to the subframe 22. The roll 30, located at the opposite end of the subframe 22 from the roll 31, is joumaled in pillow blocks 34 which are secured to supports 35. As will be seen in more detail in FIGS. 6-8, the roll supports 35 are mounted on a platform 36 which pivots about a pin 37 mounted in a second platform 38 which is secured to the subframe 22. The

platforms

36 and 38 are positioned normal to the bisector of the angle between the pass line of the strip between the

rolls

30 and 31. The axis of the pivot pin 37 coincides with the bisector of the angle between the strip pass lines and is perpendicular to the longitudinal axis of the roll 30 at its midpoint. Rollers 39 are provided at four points on the edge of the platform 36 for supporting the platform and the roll 30 carried thereon. These rollers 39 move in ways 40 mounted on the second platform 38.

A linkage arrangement 41, consisting of a pair of flatten V- shaped links 42 and a crossmember having a pair of curved segments each provided with a plurality of holes 46, is slideably mounted on a tonguelike projection 48 extending outwardly from the platform 36 along the center line thereof. One end of each of the links 42 is pivotally connected by a pin 43 to a bracket 44 mounted on the main frame 21. The opposite end of each link 42 is connected to the crossmember 45 by a pin 47 passing throughone of the openings 46. The arrangement of the linkage 41 is such that when the subframe 22 is pivoted in a clockwise direction about the pin 23 the platform 36 rotates in a counterclockwise direction about the pivot pin 37. The amount of rotation of the platform 36 in relation to the movement of the subframe 22 is determined by the pint at which the links 42 are connected to the cross member 45.

The strip being processed in the annealing line follows a path of travel through the guiding roll assembly which extends from the exit rolls of the previous portion of the annealing line to the roll 30 along a downwardly extending path 50 which, in the embodiment shown, is inclined l5 from the vertical, then along a path 51 extending between the

rolls

30 and 31, and exits from the roll 31 along a vertical path 52. The

platforms

36 and 38 are inclined in such manner that the axis of the pivot pin 37 about which the roll 30 and platfonn 36 rotate is coincident with the bisector of the angle between the incoming path 50 and the path 51. Thus, in the illustrated embodiment, the

platforms

36 and 38 are inclined at an angle of 37 30' from the horizontal. it should be noted that, since the roll 30 is located with its surface tangent to the axis of the pivot pin 23, the subframe 22 pivots about an axis which lies in the plane of the exiting strip.

As will be seen from FIG. 2 and 3, there is provided a housing 53 which extends above the roll 30 and through which passes the incoming path of travel 50 of the strip. The housing 53 mounts a centerline detecting unit consisting of a light source 54, mounted on one side of the path of travel of the strip, and a photoelectric-type detecting device 55, mounted on the opposite side of the path of travel. The detecting device 55 is of a type well know in the strip-guiding art which indicates the amount and direction of deviation of the strip from the desired centerline. A position feedback transducer 56 is mounted on the fixed main frame 21 and has the end of its operational member 57 connected to the subframe 22. This feedback position transducer 56 provides a reference signal for the control circuit to prevent excessive movement of the subframe 22 with the resultant oscillation or hunting.

As will be seen from FIG. 11, when the strip 10 is correctly positioned, that is when the centerline 61 of the strip coincides with the centerline-60 of the desired path of travel, the steering roll assembly 20 serves only to direct the strip from a downward direction to an upward direction and does not effect any lateral displacement of the strip. At this time the longitudinal axis 62 of the subframe 22 is aligned with the annealing line centerline 60 and the axes of the

rolls

30 and 31 are both perpendicular to the centerline 60.

Should the incoming strip deviate to the right of the centerline 60 of the'desired path of travel, when viewed from the entry end of the assembly as shown in FIG. 12, a signal indicating the direction of the deviation and proportional to the amount of separation between the centerline 60 of the desired path and the centerline 61 of the strip is produced by the detector 55 and is applied to an actuation circuit 65. The feedback transducer 56 also supplies a signal to the actuation circuit 65 which is related to the position of the subframe 22 relative to the centerline 60 of the desired path of travel. Assuming that the centerline 62 and the centerline 60 are coincident and that the strip centerline 61 is offset from the centerline 60. the control circuit 65 will move the nozzle 67 of a hydraulic relay 66 toward the right in response to the unequal signals from the centerline detector 55 and the feedback transducer 56. Hydraulic fluid under pressure is now supplied by the nozzle 66 to the conduit 69. The increased pressure at the left end of the hydraulic cylinder 28 now causes the cylinder to move pivoting the subframe 22 in a counterclockwise direction. Simultaneously with the movement of the subframe 22 the linkage arrangement 41 pivots the roll 30 in a clockwise direction. F 10. 12 shows, in exaggerated form, the positions of the

rolls

30 and 31 at this time. When the feedback transducer 56 indicated that the subframe 22 has pivoted a distance proportional to the amount of deviation of the centerline 61 of the strip from the desired centerline 60, the actuation circuit 65 returns the nozzle 67 to its neutral position and equal pressure is applied to both ends of hydraulic cylinder 28 through the

conduits

68 and 69. Movement of the subframe 22 now ceases and the subframe 22 remains in this position until further deviation of the strip in either direction. As will be seen from H0. 12, the axis of the roll 30 is no longer parallel to the plane of the incoming strip but rather forms a slight acute angle 64 with the plane of the strip. Since the roll is angled relative to the strip the incoming strip moves around the roll in a spiraling fashion toward the left, that is, back toward the desired centerline. Since the centerline 62 of the subframe 22 is also angled relative to the centerline 60 of the desired path of travel the midpoint of the roll 30 is offset to the right of the centerline 60 and the strip is further translated to the left as it moves from the roll 30 to the roll 31. Due to the linkage arrangement 41, the angle 64 between the axis of the roll 30 and the plane of the incoming strip is maintained at a very slight acute angle and little additional stress is placed on the edges of the strip and no stretching or tearing of these edges occurs, It should be understood that while the operation has been described in connection with an abrupt shift of the strip, the actual operation of the steering roll assembly is continuous, the control nozzle 67 of the hydraulic relay 66 being moved to'the left or right in direct response to the varying signals produced by the centerline detector 55 and the feedback transducer 56. This arrangement assures the immediate response by the hydraulic cylinder 28 to any deviation of the strip from the desired centerline and prevents any overcorrecting action with the resultant undesirable hunting or oscillation.

The amount of rotation of the roll 30 and platform 36 about the pin 37 in relation to the amount of displacement of the midpoint of the roll 30 from the centerline of the main frame 21 is determined by the point at which the link 42 is attached to the crossmember 45. Thus, if the link 42 is attached to the crossmember 45 atthe hole 46', the amount of rotation of the roll 30 and plate 36 about the pin 37 will be at a maximum for given placement of the subframe 22, while, if the link 42 is connected to the crossmember 45 at the hole 46", the rotation of the roll 30 will be at a minimum. By thus varying the angle of the axis of the roll 30, the amount of lateral displacement of the running strip effected by the spiraling action of the strip as it passes around the roll 30 may be increased or decreased as necessary to compensate for the varying characteristics of different strip being processed, such as width or irregularities of the transverse thickness of the strip.

While, the preferred embodiment, subframe 22 is moved by means of a hydraulic cylinder 28, it will be understood that other suitable driving arrangements, such as a rack and pinion or screw and nut assembly, may be employed. Likewise, while the photoelectric strip

centerline sensing device

54, 55 is preferred, other suitable strip position sensors such as are well known in the art may be employed. It should also be noted that while particular reference has been made to the employment of the steering roll assembly in a strip-annealing line, the invention is not so limited and may be adapted to other operations in which it is necessary to maintain a running strip along a desired path of travel.

While in the preferred embodiment described above the entering strip travels downwardly along a path inclined from the vertical and the exiting strip travels vertically upward from the exit roll, the principles of the present invention may be applied to other strip travel paths. Thus, as shown in FIG. 13, the path of travel 52 of the exiting strip may be vertically downward. In such an installation the base 21 and subframe 22 are modified so as not to interfere with the exiting strip. A similar arrangement is shown in FIG. 14. In this arrangement the frame 21 and subframe 22 are mounted vertically and the entering and exiting paths of

travel

50 and 52, respectively, are both horizontal. Where it is desirable to accomplish the steering of the strip at the upper rather than the lower end of a path of travel. the arrangement shown in FIG. 15 may be employed. In such an installation the

rolls

30 and 31 and their associated supports depend from the subframe 22 which, together with the base 21, is mounted above the strip pass line in an inverted position from that shown in FIG. 3. It should also be noted that while the angle between the entry path 50 and intermediate path 51 and that between the intermediate path 51 and exit path 52 is not less than 90 either of these angles may be greater than 90. Such an arrangement is shown in FIG. 16 wherein both the entry pass line 50 and the exit pass line 52 are inclined at acute angles from the horizontal, resulting in obtuse angles between these pass lines and the intermediate puss line 51. The particular arrangement employed in it given installation will be determined by the location of the steering roll assembly in the processing line and the desired directions of the pass lines of the entering and exiting strip. In any event, the axis 37' about which the entry roll 30 and its associated support are pivoted is coincident with the bisector of the angle between the desired centerline of the entering strip 50 and that of the intermediate strip 51. Likewise, the axis 23' about which the subframe 22 is pivoted will be tangent to the surface of the exit roll 31.

Iclaim:

1. A steering roll assembly for correcting deviation of a running strip from a desired path of travel, comprising: a fixed base; a subframe pivotally connected at one end thereof to said base; first and second rolls carried by said subframe said first roll being mounted adjacent the end of said subframe remote from said pivotal connection for pivotal motion about an axis perpendicular to the longitudinal axis of said roll at the midpoint thereof, said second roll being mounted on said'subframe with its longitudinal axis perpendicular to the longitudinal axis of said subframe and with its cylindrical surface tangent to the axis of the pivotal connection between said subframe and said base; means carried by said fixed base for effecting the pivotal motion of said subframe; means for effecting the pivotal motion of said first roll relative to said subframe; and sensing means detecting the position of the incoming strip, said sensing means controlling the operation of said subframe pivoting means.

2. Apparatus according to claim 1 further characterized in that said means for pivoting said first roll operates in coordination with said means for pivoting said subframe.

3. Apparatus according to claim 2 further characterized in that said means for pivoting said first roll is adjustable to vary the amount of pivoting of said first roll relative to the amount of pivoting of said subframe.

4. Apparatus according to claim 2 further characterized in that said means for pivoting said first roll comprises: a platfonn supporting said first roll and pivoting therewith; and a linkage arrangement connecting said platform and said fixed base.

5. Apparatus according to claim 4 further characterized in that said platform pivots in a plane normal to the bisector of the angle between the centerline of the incoming path of travel and the centerline of the path of travel between said first and second rolls.

6. Apparatus according to claim 5 further characterized in that said linkage arrangement comprises a projecting portion of said platform extending along the longitudinal centerline of said subframe; a crossmember slidably received on said projecting portion of said platform and extending on either side thereof; and at least one link, one end of said link being pivotally connected to said crossmember, and the opposite end of said link being pivotally connected to said fixed base.

7. Apparatus according to claim 5 further characterized in that said link may be connected to said crossmember at any of a plurality of points.

8, A device for correcting lateral deviations of a running strip from a desired path of travel, comprising: an entry roll; an exit roll spaced from said entry roll; a subframe supporting said entry and exit rolls; said subframe being capable of pivotal motion about an axis on the centerline of said desired path of travel and tangent to the exit side of said exit roll; a fixed base supporting said subframe; means for detecting the deviation of the incoming strip from the desired path of travel; and means responsive to said detecting means for moving said subframe and for simultaneously pivoting said entry roll relative to the subframe about an axis perpendicular to the longitudinal axis of the entry roll at the midpoint thereof.

Q. A device according to claim 8 wherein said means for moving said subframe and pivoting said entry roll moves said entry roll in the opposite direction to the motion of said subframe.

l0. A device according to claim 9 further characterized in that said entry roll is mounted on said subframe for pivotal motion about an axis perpendicular to the longitudinal axis of said roll at the midpoint thereof and coincident with the bisector of the angle between the centerline of the incoming path of travel of the strip and the centerline of the path of travel of the strip between said entry and exit rolls.

11. A device according to claim 10 further characterized in that said means for moving said subframe and pivoting said entry roll includes a support for said entry roll pivoting therewith, and a linkage arrangement interconnecting said entry roll support and said fixed frame.

12. A device according to claim 11 further characterized in that said linkage arrangement is adjustable to vary the amount of pivotal motion of said entry roll relative to the pivotal motion of said subframe.

13. A device according to claim 8 wherein said means for moving said subframe and pivoting said entry roll includes means for sensing the position of said subframe relative to said fixed base, a hydraulic cylinder mounted on said fixed base and having its operational end connected to said subframe, a hydraulic relay supplyinghydraulic fluid under pressure selectively to one or the other of the sides of the piston of said hydraulic cylinder, and actuating means responsive to said means for detecting the deviation of the incoming strip and to said means for sensing the position of said subframe, said actuating means controlling said hydraulic relay.

Claims

1. A steering roll assembly for correcting deviation of a running strip from a desired path of travel, comprising: a fixed base; a subframe pivotally connected at one end thereof to said base; first and second rolls carried by said subframe said first roll being mounted adjacent the end of said subframe remote from said pivotal connection for pivotal motion about an axis perpendicular to the longitudinal axis of said roll at the midpoint thereof, said second roll being mounted on said subframe with its longitudinal axis perpendicular to the longitudinal axis of said subframe and with its cylindrical surface tangent to the axis of the pivotal connection between said subframe and said base; means carried by said fixed base for effecting the pivotal motion of said subframe; means for effecting the pivotal motion of said first roll relative to said subframe; and sensing means detecting the position of the incoming strip, said sensing means controlling the operation of said subframe pivoting means.

4. Apparatus according to claim 2 further characterized in that said means for pivoting said first roll comprises: a platform supporting said first roll and pivoting therewith; and a linkage arrangement connecting said platform and said fixed base.

8. A device for correcting lateral deviations of a running strip from a desired path of travel, comprising: an entry roll; an exit roll spaced from said entry roll; a subframe supporting said entry and exit rolls; said subframe being capable of pivotal motion about an axis on the centerline of said desired path of travel and tangent to the exit side of said exit roll; a fixed base supporting said subframe; means for detecting the deviation of the incoming strip from the desired path of travel; and means responsive to said detecting means for moving said subframe and for simultaneously pivoting said entry roll relative to the subframe about an axis perpendicular to the longitudinal axis of the entry roll at the midpoint thereof.

9. A device according to claim 8 wherein said means for moving said subframe and pivoting said entry roll moves said entry roll in the opposite direction to the motion of said subframe.

10. A device according to claim 9 further characterized in that said entry roll is mounted on said subframe for pivotal motion about an axis perpendicular to the longitudinal axis of said roll at the midpoint thereof and coincident with the bisector of the angle between the centerline of the incoming path of travel of the strip and the centerline of the path of travel of the strip between said entry and exit rolls.

13. A device according to claim 8 wherein said means for moving said subframe and pivoting said entry roll includes means for sensing the position of said subframe relative to said fixed base, a hydraulic cylinder mounted on said fixed base and having its operational end connected to said subframe, a hydraulic relay supplying hydraulic fluid under pressure selectively to one or the other of the sides of the piston of said hydraulic cylinder, and actuating means responsive to said means for detecting the deviation of the incoming strip and to said means for sensing the position of said subframe, said actuating means controlling said hydraulic relay.