US3615048A

US3615048A - Apparatus for adjusting the lateral position of a continuous moving web

Info

Publication number: US3615048A
Application number: US813110A
Authority: US
Inventors: John R Martin
Original assignee: Martin Automatic Inc
Current assignee: Martin Automatic Inc
Priority date: 1969-04-03
Filing date: 1969-04-03
Publication date: 1971-10-26
Anticipated expiration: 1988-10-26

Abstract

APPARATUS IS PROVIDED FOR CONTROLLING THE LATERAL POSITION OF A CONTINUOUS WEB MOVING THROUGH A MACHINE SUCH AS A PRINTING PRESS. FIRST AND SECOND SPACED ROLLS ARE MOUNTED ON A CARRIAGE FOR ROTATION ABOUT PARALLEL AXES, WITH THE WEB LEAVING THE SECOND ROLL PARALLEL TO THE WEB ARRIVING AT THE FIRST ROLL. FLEXIBLE STRAPS SUPPORT THE CARRIAGE EACH STRAP BEING FLEXIBLE SUBSTANTIALLY ONLY NORMALLY OF THE PLANE INCLUDING THE RESPECTIVE STRAP AND THE LINE IN THE PLANE OF THE APPROACHING WEB TANGENT TO THE MID-POINT OF THE FIRST ROLL, THEREBY CONSTRAINING THE CARRIAGE TO ROTATION ABOUT THAT LINE AS A FIXED AXIS. EDGE DETECTORS SENSE THE LATERAL POSITION OF THE WEB AND PRODUCE A CONTROL SIGNAL USED TO DRIVE THE CARRIAGE ABOUT ITS AXIS TO CONTROL THE LATERAL POSITION OF THE WEB. THE EDGE DETECTORS MAY BE MOUNTED ADJACENT THE SECOND ROLL FOR ROTATION WITH THE CARRIAGE ABOUT A FIXED AXIS SUBSTANTIALLY COINCIDENT WITH THE MID-LINE OF THE LEAVING WEB TANGENT TO THE SECOND ROLL.

Description

Oct. 26, 1971 J. R. MARTIN APPARATUS FOR ADJUSTING THE LATERAL POSITION OF A CONTINUOUS MOVING WEB Filed April 5, 1969 3 Sheets-Sheet 1 FIG! FIG.3

FIGZ

INVENTOR JOHN R. MARTIN %%M% Oct. 26,1971

Filed April 5, 1969 5 Sheets-Shoot 2 JOHN R. MARTIN WWW ATTYS Oct. 26, 1971 J. R. MARTIN APPARATUS FOR ADJUSTING THE LATERAL POSITION OF A CONTINUOUS MOVING WEB Filed April 5, 1969 5 Sheets-Sheet 5 FIG] INVENTOR JOHN R MOTOR CONTROL COMPARISON CIRCUIT W? ATTYS.

84 96 --IOO 3,615,048 APPARATUS FOR ADJUSTING THE LATERAL POSITION OF A CONTINUOUS MOVING WEB John R. Martin, Rockford, 11]., assignor to Martin Automatic Incorporated, Rockford, Ill. Filed Apr. 3, 1969, Ser. No. 813,110 Int. Cl. B6511 25/26 U.S. Cl. 226-20 10 Claims ABSTRACT OF THE DISCLOSURE Apparatus is provided for controlling the lateral position of a continuous web moving through a machine such as a printing press. First and second spaced rolls are mounted on a carriage for rotation about parallel axes, with the Web leaving the second roll parallel to the web arriving at the first roll. Flexible straps support the carriage, each strap being flexible substantially only normally of the plane including the respective strap and the line in the plane of the approaching web tangent to the mid-point of the first roll, thereby constraining the carriage to rotation about that line as a fixed axis. Edge detectors sense the lateral position of the web and produce a control signal used to drive the carriage about its axis to control the lateral position of the Web. The edge detectors may be mounted adjacent the second roll for rotation with the carriage about a fixed axis substantially coincident with the mid-line of the leaving web tangent to the second roll.

This invention relates generally to apparatus for adjusting the lateral position of a continuous web moving through a machine such as a printing press over a plurality of web guides. As used herein the term web guide refers to parts of such apparatus such as rolls or angle bars around which the web is Wrapped in changing the direction of the web path and the lateral position of the web. Such usage is to be distinguished from conventional terminology in which the entire apparatus for adjusting the lateral position of the web is called a web guide. More specifically, the invention relates to apparatus of the box tilt or step tilt type wherein the position of the pair of rolls relative to the rest of the machine is adjustable to direct the web laterally a desired amount. Still more particularly, the invention is directed to apparatus for controlling the lateral position of the web passing through the machine so as, for example, to permit accurate registration of printing on a paper web.

In the graphic arts and more particularly in the operation of printing presses, it is frequently necessary or desirable that certain operations be performed upon a continuous moving web. For example, it is desirable and practically necessary that printing presses print in proper registry on a continuous paper web in order that the printed product may be efficiently cut and assembled in suitable form. Unfortunately, it happens that a web becomes misaligned from time to time as it passes through a printing press. That is, the web may be displaced laterally from its proper position, resulting in imprinting at the wrong place on the sheet and consequent spoilage. This error in the lateral position of the web is known as a sidelay error. Such sidelay errors may occur from misalignment of the machine or from defects in the paper. For example, a substantial sidelay error may occur from a misaligned splice in the paper web. It is desirable that these errors be corrected promptly to within the required limit of accuracy, such as plus or minus 0.005 inch. Modern printing presses operate at substantial rates such as 1200 feet a minute, and it is United States Patent "ice desirable that any errors be corrected as promptly as possible to reduce spoilage. To this end, it is desirable that the corrections be made automatically.

Lateral repositioning of a continuous Web has been performed with what is known as a tilt box comprising a pair of parallel guide rolls over which the web is run and which function as web guides to guide the direction of the web. The pair of rolls may be tilted, thus steering the web and repositioning it laterally. For high speed operation, however, the friction and backlash of prior art tilt boxes has resulted in hunting or sluggishmenss, neither of which is acceptable for high accuracy and correction rate.

Further, for accurate control it is necessary to sense the lateral position of the web in order that exact correctioins for deviation from the desired position may be achieved. Sensing means have previously been positioned at the first fixed roll after tilt box. However, this has necessarily meant a substantial delay between the adjustment of the tilt box and the sensing unit. This has necessitated sluggish operation or has resulted in over correction, for unless sluggish the sensing unit would continue to indicate a need for correction long after the tilt 'box had completed the adjustment.

In accordance with the present invention, the tilt box is mounted in a manner substantially eliminating friction an backlash. The tilt box is supported by a plurality of straps, each of which flexes in one direction only, this direction being normal to a respective plane through the axis about which the tilt box is to tilt. Further, the sensing means of the present invention are disposed at the tilt box, and the sensing means are mounted in a fashion compensating for measuring errors as would occur from twisting of the web in the process of the tilt box correction.

It is therefore an object of the present invention to provide an improved apparatus for rapidly adjusting or controlling the lateral position of a continuous moving web.

Another object of the invention is to provide such apparatus capable of accurate adjustment or control at high speed.

Still another object of the invention is to provide such apparatus with improved mounting means reducing friction and backlash.

Still another object of the invention is to provide such apparatus with sensing means accurately sensing the lateral position of the web, such sensing means being disposed adjacent the adjusting apparatus.

Other objects and advantages of the invention will become apparent from the following detailed description, particularly when taken with reference to the drawings in which:

FIG. 1 is a perspective view of a tilt box made in accordance with the present invention;

FIG. 2 is a diagrammatic plan view of the tilt box shown in FIG. 1, illustrating its rotational mounting;

FIG. 3 is another diagrammatic plan view of the tilt box shown in FIG. 1, illustrating the mounting of the edge detectors;

FIG. 4 is a diagrammatic end view of the tilt box shown in FIG. 1, illustrating the relationship of the tilt box to a printing press;

FIG. 5 is a digrammatic end view of the apparatus of FIG. 1 as modified for operation in a step tilt configuration;

FIG. 6 is a plan view of the tilt box shown in FIG. 1;

FIG. 7 is an end view of the tilt box shown in FIG. 1;

FIG. 8 is a bottom view of a portion of the tilt box shown in FIG. 1; and

FIG. 9 is a schematic illustration of the servo system used in controlling the tilt box shown in FIG. 1.

A of

side rails

18 and 20 and

axles

22 and 24, the

rolls

12 and 14 being rotatably mounted on the

axles

22 and 24, respectively. The carriage 16 is supported from

supports

26 and 28 by a plurality of

straps

30, 32, 34 and 36. These straps are long and thin and of substantial width. They are substantially planar. They are particularly strong in tension but when supported at their ends are extremely flexible in a direction normal to their plane. They may for example, be formed of a stack of 10 berryllium copper strips each about 0.01 inch thick by about 1 /2 inches wide. Each of the straps is rigidly fastened at one end to one of the

supports

26, 28 and at the other end of the carriage 16, and may be 6 inches long between fastenings. These straps are not only relatively inextensible but they are extremely stiff in their lateral direction. The straps are mounted in such a way that they lie in respective planes intersecting along a line extending substantially in the direction of motion of the approaching webs. This is best illustrated in FIGS. 2 and 3. As shown in FIG. 2, the

straps

30 and 32 lie in a plane 38. Strap 34 lies in a plane 40, and strap 36 lies in a plane 42. These planes intersect in a line 44 which is tangent to the roll 12 at its mid-point. The straps extend longitudinally generally parallel to the line 44 and are flexible in a directional normal to their respective planes, thus permitting limited rotation of the carriage 16 about the line 44 as a fixed axis. In FIG. 3, the displacement of the tilt box 10 about the line 44 as an axis is illustrated by dashed lines.

The supports 26 and 28 are mounted to the printing 'press to dispose the

rolls

12 and 14 as guide rolls in the path of a paper web 46 to contact the paper web and guide it, the web 46 being a continuous web moving in the direction indicated by the arrow 48. The tilt box 10 is mounted in respect to the printing press in such manner that the web 46 as it leaves the second roll 14 is parallel to the web as it approaches the roll 12. This is achieved by appropriately disposing the

rolls

12 and 14 in respect to the

regular rolls

50 and 52 of the press. Thus the paper web leaves the roll 50, passes over the roll 12, then over the roll 14 and then back to the roll 52, the web between

rolls

14 and 52 being parallel to the web between

rolls

50 and 12. Further the tilt box 10 is mounted in such relationship to the printing press that the web 46 as it approaches roll 12 is tangent to the center of the roll 12 along the line 44.

The arrangement of the tilt box 10 relative to a printing press is shown in FIG. 1 in what is known as a box configuration, whence the name tilt box or box tilt originated. This is best illustrated in FIG. 4 which is a diagrammatic end view of the tilt box of FIG. 1, showing the disposition of the tilt box rolls 12 and 14 relative to the

rolls

50 and 52 of the press and the manner in which the paper web 46 passes over these rolls. As shown, the paper turns an angle of approximately 90 at each of

rolls

12 and 14, moving between

rolls

12 and 14 in a plane normal to the planes of the web as it travels toward roll 12 and away from roll 14.

One of the advantages of the tilt box of the present invention is that it may be mounted in various configurations on existing presses, For example, in FIG. is illustrated an alternative configuration, where the rolls 12 and 1-4 are not horizontal and wherein the Web 46 comes down to roll 12 from above to form What is called a step configuration. In the configuration of FIG. 5, the tension in the web 46 supports the roll 12, and the straps supporting the carriage 16 near roll 12 extend upwardly from the

supports

26 and 28 to the carriage 16, yet remain in tension. The step tilt configuration of FIG. 5 works in principle exactly like the box tilt configuration of FIG. 4.

The printing on the web 46 is subsequent to the roll 52. It is the purpose of the tilt box to direct the paper 4 onto roll 52 at such lateral position as to cause proper registry of the printing on the Web. To this end, the tilting of the tilt box, that is its angular position about the axis 44, is adjustable. Although manual adjustment of the position would be possible, in the apparatus as illustrated, adjustment is effected by energizing an electric motor 54 which operates through a gear box 56 to move a crank 58 which pulls or pushes a connecting rod 60. As shown, the motor 54, gear box 56 and crank 58 are mounted on the carriage 16. One end of the connecting rod is fastened to the crank 58, whereas the other end is fastened to the support 28. Thus when the motor is energized the crank 58 pulls or pushes the connecting rod 60 to move the carriage relative to the support 28, hence moving the tilt box 10 about the axis 44 relative to the

rolls

50 and 52, which are secured to the printing press. Although the motor 54 may be energized in the appropriate direction by the manual operation of an electric switch, in the preferred embodiment of the present invention, an automatic control is provided.

The automatic control, as illustrated, includes

edge detectors

62 and 64 mounted adjacent and just following the roll 14 at the edges of the paper web 46. These edge detectors are mounted on

rods

66 and 68 which are fastened to a frame 70 comprising

blocks

72 and 74 connected by a bar 76. The frame 70 is supported from

supports

26 and 28 by

straps

78 and 80 which may be made like

straps

30, 32, 34 and 36 and attached at their respective ends. The frame 70 is fastened to the carriage 16 by

straps

82 and 84 which may also be, like the other straps, flexible only normal to their flat sides. The effect of this mounting is to cause the frame 70 to move angularly with the rotation of the tilt box 10. However, because the

straps

78 and 80 are flexible only in a direction parallel to the planes of

supports

26 and 28, the frame 62 rotates about an axis between the straps 78 and 80'. To define this axis more accurately a post 86 is aifixed to the bar 78 and extends upwardly above the roll 14. An arm 88 extends from the post 86 and terminates at a pivot 90 which is along the mid-line of the paper web 46 in its desired position as it leaves the roll 14. A connecting rod 92 is connected between the pivot 90 and the support 26. The connecting rod 92, pivot 90, arm 88 and post 86 accurately define the axis of rotation 91 of the frame 70 to be along the mid-line of the Web in its desired position as it leaves the roll 14.

The advantages of this arrangement will be apparent from consideration of FIG. 3. As was stated above, it has been known to mount edge detectors near the fixed roll 52 of the press. This has the disadvantage, as mentioned, that it takes a substantial time for the web 46 to travel from the guide roll 14 to the fixed roll 52. This necessarily results in a delay between the time the correction is made at the roll 14 and when it is appreciated at the roll 52. Under such circumstances, if the control system responds rapidly to a position error noted at the roll 52, the tilt box 10 will overcorrect, for it will continue to demand a correction until the proper position is noted at the roll 52, by which time the web 46 at the roll 14 will have gone beyond the desired position. On the other hand, if the response of the control system is damped to prevent overcorrection, the control is sluggish and excessive spoilage results. Therefore, in the present invention the edge detectors are mounted adjacent the roll 14 Where the correction is made. This, however, creates other problems which are met by the particular mounting of the present invention, as will be explained further below.

The

edge detectors

62 and 64 may each comprise a lamp 94 of fixed intensity and a photosensitive detector 96 disposed on respective sides of the web 46. Each edge detector is mounted adjacent a respective edge, the web moving between the lamp 94 and photosensitive detector 96. Each edge detector detects the position of the edge by the amount of light from the lamp reaching the photosensitive detector. The photosensitive detector 96 then provides a detection signal indicative of the position of the edge. It is desirable that the lamp 94 and photosensitive detector 96 be relatively close together to assure high accuracy. The farther apart the lamp and photosensitive detector, the greater the uncertainty of measurement of the edge.

It may be noted in FIG. 3 that upon movement of the tilt box the web 46 is twisted as well as moved laterally. Because of this twisting, the edge would not move directly in and out of the space between the lamp and photosensitive detector were it not that the frame 70 twists as well. At the same time, of course, the edge detector must not move laterally with the roll 14, or it would not be able to sense the position of the edge of the web relative to the press. The frame 70 is therefore mounted to move angularly about the axis 91, in unison with the angular movement of the tilt box 10, but it is laterally constrained relative to the

supports

26 and 28, as illustrated more particularly in FIG. 3. This permits the lamp 94 and photosensitive detector 96 of each

edge detector

62 or 64 to be disposed close together.

This position of the

edge detectors

62 and 64 has the additional feature that it corrects for foreshortening of the Web. That is, the projection of the Web is foreshortened as the web twists; however, with the frame 70 twisting with the web, the distance between edge detectors is equally foreshortened, thus compensating for any foreshortening error. This is particularly useful when but a single edge detector is used.

FIGS. 6, 7 and 8 illustrate the tilt box shown in FIG. 1 in greater detail, although more detailed Written description of the construction is believed unnecessary.

In FIG. 9, the control circuit for the tilt box is illustrated in schematic and diagrammatic form. The control circuit is in large measure a conventional servo-mechanism circuit. Each of the

edge detectors

62 and 64 develops a signal indicative of the position of the respective edge of the web 46. The respective photosensitive detectors 96 produce corresponding detection signals which are applied over

conductors

98 and 100 to a comparison circuit 102. The comparison circuit 102 may be conventional circuit, such as a differential amplifier, which produces an error signal or a control signal indicative of the difference between the signals appearing On

detectors

98 and 100. The control signal thus provides an indication of how much nearer one edge of the web 46 is to one edge detector than the other edge of the web is to the other edge detector. This control signal is applied over a conductor 104 to a motor control circuit 106 which operates in a conventional manner to supply appropriate power over conductors 108 to drive the motor 54 in one direction or another, depending upon the sense of the control signal. The motor 54 is driven in such direction as to tilt the tilt box 10 to move the web 46 in the direction that reduces the difference in the detection signals appearing on

conductors

98 and 100. This then results in the centering of the web 46 along the axis 91, thus controlling the lateral position of the web to keep the web 46 in registry for printing.

In the foregoing description and in the claims, where the carriage axis is referred to as being along a line tangent to the mid-point of the first roll 12, it is intended to include the point where the center line or mid-line of the approaching web is to contact the roll 12. Where the frame axis is referred to as being along the mid-line of the lea-ving web, it is intended to refer to the mid-line of the web when the web is in its desired lateral position.

Although an exemplary embodiment of the invention has been shown and described, various modifications in the apparatus may be made within the spirit and scope of the invention. For example, rather than providing two edge detectors and centering the web, it is possible to utilize but a single edge detector and maintain the edge of the web a predetermined distance from the single edge detector. In such case, the comparison circuit 102 may receive a detection signal from only the one edge detector, and a standard reference signal may be applied to the comparison circuit in lieu of the other detection signal.

Also, under some conditions it is desirable to provide a balanced motor drive. In such instances, the shaft driving the crank 58 may be extended across the carriage to a bearing afiixed to the side rail 20, and another crank may be fastened to the shaft to operate another connecting rod connected to the support 26.

It is also often desirable to make the position of the

edge detectors

62 and 64 adjustable on the

rods

66 and 68. This may be achieved by conventional clamping means.

A fine adjustment of position may be achieved electronically in the control unit.

It should also be clear that conventional power supplies are provided where needed.

Various of the features believed to be novel are set forth in the appended claims.

What is claimed is:

1. Apparatus for adjusting the lateral position of a continuous web moving longitudinally along a path in a machine such as a printing press, said apparatus comprising a rigid carriage, first and second web guides mounted on said carriage parallel to one another in laterally spaced relationship, carriage mounting means for mounting said carriage relative to said machine with said first and second web guides extending transversely of the web and with the web in contact first with said first web guide and thereafter with said second web guide and leaving said second web guide substantially parallel to the web arriving at said first web guide, said carriage mounting means including a plurality of mounting members attached to said carriage and extending therefrom in respective planes substantially normal to a plane perpendicular to the approaching web and intersecting in a line in the plane of the approaching web tangent to the mid-point of said first web guide and extending in the direction of motion of the approaching Web, one end of each mounting member being constrained to move relative to the other substantially only normally of said respective planes, thereby constraining said carriage to limited rotation about said tangent line as a substantially fixed carriage axis, and means for rotating said carriage about said carriage axis, there-by adjusting the lateral position of the web leaving said second web guide.

2. Apparatus for adjusting the lateral position of a continuous web moving longitudinally along a path in a machine such as a printing press, said apparatus comprising a rigid carriage, first and second rolls rotatably mounted on said carriage in laterally spaced relationship for rotation about respective parallel axes, carriage mounting means for mounting said carriage relative to said machine with said parallel axes extending transversely of the web and With the web in contact successively with said first and second rolls and leaving said second roll substantially parallel to the web arriving at said first roll, said carriage mounting means including a plurality of flexible straps each afiixed at one end to said carriage and extending from said carriage substantially normally of a plane perpendicular to the approaching web, said straps lying in respective planes intersecting along the line in the plane of the approaching web tangent to the mid-point of said first roll in the direction of motion of the web, said straps each being flexible substantially only normally of the re spective one of said planes, thereby constraining said carriage to limited rotation about said line as a substantially fixed carriage axis, and means for rotating said carriage about said carriage axis, thereby adjusting the lateral position of the web leaving said second roll.

3. Apparatus for controlling the lateral position of a continuous web moving longitudinally along a path in a machine such as a printing press, said apparatus comprising a rigid carriage, first and second rolls rotatably mounted on said carriage in laterally spaced relationship for rotation about respective parallel axes, carriage mounting means for mounting said carriage relative to said machine with said parallel axes extending transversely of the Web and with the web in contact successively with said first and second rolls and leaving said second roll substantially parallel to the web arriving at said first roll, said carriage mounting means including a plurality of flexible straps each affixed at one end to said carriage and extending from said carriage substantially normally of a plane perpendicular to the approaching web, said straps lying in respective planes intersecting along the line in the plane of the approaching web tangent to the mid-point of said first roll in the direction of motion of the web, said straps each being flexible substantially only normally of the respective one of said planes, thereby constraining said carriage to limited rotation about said line as a substantially fixed carriage axis, means for sensing the deviation of the lateral position of the web leaving said second roll from a predetermined position and producing a control signal indicative of such deviation, and motive means responsive to said control signal for rotating said carriage about said carriage axis in the direction reducing said deviation, thereby controlling the lateral position of the web leaving said second roll.

4. Apparatus according to claim 3 wherein the web path between said first and second rolls is in a plane perpendicular to said line.

5. Apparatus for controlling the lateral position of a continuous web moving longitudinally along a path in a machine such as a printing press, said apparatus comprising a rigid carriage, first and second web guides mounted on said carriage parallel to one another in laterally spaced relationship, caniage mounting means for mounting said carriage relative to said machine with said first and second web guides extending transversely of the web and with the web in contact first with said first web guide and thereafter with said second web guide and leaving said second web guide substantially parallel to the web arriving at said first web guide, said carriage mounting means constraining said carriage to rotation about a substantially fixed carriage axis substantially coincident with the line in the plane of the approaching web tangent to the midpoint of said first web guide in the direction of motion of the web, a frame, connecting means connecting said frame to said carriage for angular movement therewith, means for constraining said frame to move substantially only in rotation about a substantially fixed frame axis substantially coincident with the mid-line of the leaving web tangent to said second Web guide, sensing means for sensing the position of at least one edge of the web and producing a control signal indicative of such position, said sensing means being mounted on said frame for rotation therewith about said frame axis adjacent at least one edge of said web as it leaves said second web guide, and motive means responsive to said control signal for rotating said carriage about said gafrriage axis, thereby controlling the lateral position of th e"web leaving said second Web guide.

'6. Apparatus according to claim 5 wherein said sensing means comprises first and second edge detectors each mounted on said frame adjacent said second web guide for sensing the position of a respective edge of the .web by producing respective detection signals indicative thereof, and means for differentially combining said detection signals to derive said controlsignal, and wherein said motive means responds to said control signal by rotating said carriage in the direction balancing said detection signals, thereby centering the web between said first and second edge detectors.

'7. Apparatus according to claim 5 wherein said sensing means comprises an edge detector mounted on said frame adjacent said second web guide for sensing the position of one edge of said web by producing a detection signal indicative thereof, means for developing a reference signal, and means for comparing said detection and reference signals to produce a control signal indicative of their difference, and wherein said motive means responds to said control signal by rotating said carriage in the direction reducing said control signal.

8. Apparatus according to claim 5 wherein said sensing means comprises a constant intensity lamp and a photosensitive detector disposed on respective sides of the path of said web.

9. Apparatus for controlling the lateral position of a continuous web moving longitudinally along a path in a machine such as a printing press, said apparatus comprising a rigid carriage, first and second rolls rotatably mounted on said carriage in laterally spaced relationship for rotation about respective parallel axes, carriage mounting means for mounting said carriage relative to said machine with said parallel axes extending transversely of the web and with the web in contact successively with said first and second rolls and leaving said second roll substantially parallel to the web arriving at said first roll, said carriage mounting means including a plurality of flexible straps each affixed at one end to said carriage and extending from said carriage substantially normally of a plane perpendicular to the approaching web, the lateral direction of respective ones of said straps lying in respective planes intersecting along the line in the plane of the approaching web tangent to the mid-point of said first roll in the direction of motion of the web, said straps each being flexible substantially only normally of the respective one of said planes, thereby constraining said carriage to limited rotation about said line as a substantially fixed carriage axis, a frame, connecting means connecting said frame to said carriage for angular movement therewith, means for constraining said frame to move substantially only in rotation about a substantially fixed frame axis substantially coincident with the mid-line of the leaving web tangent to said second roll, sensing means for sensing the position of at least one edge of the Web and producing a control signal indicative of such position, said sensing means being mounted on said frame for rotation therewith about said frame axis adjacent at least one edge of said web as it leaves said second roll, and motive means responsive to said control signal for rotating said carriage about said carriage axis, thereby contrrilling the lateral position of the Web leaving said second ro l. e

10. Apparatus for adjusting the lateral position of a continuous web moving longitudinally along a path in a machine such as a printing press, said apparatus comprising a rigid carriage, first and second web guides mounted on said carriage parallel to one another in laterally spaced relationship, carriage mounting means for mounting said carriage relative to said machine with said first and second web guides extending transversely of the web and with the web in contact first with said first web guide and thereafter with said second web guide and leaving said second web guide substantially parallel to the' web arriving at said first Web guide, said carriage mounting means including a plurality of mounting members attached to said carriage and extending therefrom substantially normally of a plane perpendicular of the approaching web, one end of each mounting member being constrained to move relative to the other end of said mounting member substantially only normally of a respective plane, said respective planes intersecting in a line extending substantially in the direction of motion of the approaching web, thereby constraining said carriage to limited rotation about said line as a substantially fixed carriage axis, and means for rotating said carriage about said carriage axis, thereby adjusting the lateral position of the web leaving said second web guide.

References Cited UNITED STATES PATENTS 3,373,288 3/1968 Otepka et al 226-21 X RICHARD A. SCHACHER, Primary Examiner G. A. CHURCH, Assistant Examiner