US3390823A

US3390823A - Web guide apparatus

Info

Publication number: US3390823A
Application number: US530074A
Authority: US
Inventors: Jr Robert W Ott
Original assignee: ROCKFORD SERVO CORP
Current assignee: ROCKFORD SERVO CORP
Priority date: 1966-02-25
Filing date: 1966-02-25
Publication date: 1968-07-02
Anticipated expiration: 1985-07-02
Also published as: DE1774925A1; DE1774925B2; GB1110379A; DE1774925C3; DE1574418B1

Description

July 2, 1 OTT, JR 3,390,823

' WEB GUIDE APPARATUS Filed Feb. 25, 1966 2 Sheets-Sheet 1 United States Patent 3,390,823 WEB GUIDE APPARATUS Robert W. Ott, Jr., Rockford, Ill., assignor to Rockford Servo Corporation, Rockford, Ill., a corporation of Illinois Filed Feb. 25, 1966, Ser. No. 530,074

24 Claims. (Cl. 226-19) ABSTRACT OF THE DISCLOSURE A Web guide apparatus in which the web engaging roll is mounted for movement in an arcuate path relative to the -traveling web by means of longitudinally arcuate guide bars and followers slidably engaging the guide bars.The guide bars are in the form of circular arcs having a common center, and the sliding followers are made up of a plurality of laminations each having openings slidably receiving the bar and held in a stacked assembly with the openings arranged to accommodate the curvature of the guide bar.

This invention relates to apparatus for guiding a traveling web of material.

It is frequently necessary in machines operating on a traveling web, to effect lateral positioning of the web at one or more locations intermediate the ends of the Web. Numerous different web guiding apparatus operating on various different principles and combinations thereof have heretofore been employed in laterally guiding such webs.

It is well known that a cylindrical roll extending transversely to a web and in frictional engagement therewith will, if shifted in a direction lengthwise of the roll axis, tend to draw the traveling web in the direction of axial movement of the roll. Thus, if a guide roll is shifted in a direction opposite the direction of deviation of a traveling web from a preselected path, it will tend to return the web to its correct path. This provides a rapid correction of the deviation of the web from the desired path of travel. However, if the forces that initially caused the web to deviate from the desired path continue to exist, the web will tend to move back out of the desired path of travel and thus necessitate continued endwise movement of the roll. It is apparent that endwise movement of the cylindrical roll cannot be relied upon to continuously correct the deviation of a web from a desired path since, if the roll is continuously moved endwise in one direction, a pointwill soon be reached where the roll is no longer in full'engagement with the web.

It is also known that a flat or nearly fiat traveling web in frictional engagement with a cylindrical roll will tend to move at right angles to the axis of the rotating roll and that, if the axis of the cylindrical roll is inclined .with respect to the path of travel of the web, the web will tend to move toward the end of the roll which is first contacted by the traveling web. This tendency of the web to move towardthe end of the inclined roll continues ,as the web travels over the roll and is limited only by slippage between the web and the roll. Thus, the traveling web will tend to move toward the end of the inclined roll until the other forces acting on the web are suflicient to overcome the traction between the web and theroll and cause the web to slip on the roll.

' A further principle involved in web guiding is that a traveling web in frictional engagement with a cylindrical roll, will tend to move sideways in a direction such that the total tension in the web is increased. Thus, if the roll is tilted in a direction to increase the tension in one side of the rollover that in the other side, the web will tend to move toward the end of the roll which increases the tension in the web. This latter principle is made use of in the well known crowned pulleys and coned pulleys. However, while this principle is sometimes useful in centering belts and the like, it is not of general utility in guiding of webs which may be non-uniformly stretched or even torn when nonuniform tension is applied thereto.

It is an important object of this invention to provide an improved web guiding apparatus wherein the web guide roll is moved in an arcuate path with respect to the path of travel of the web such as to produce a combined lengthwise shifting of the roll in a direction transverse to the direction of web travel to provide rapid correction of the deviation of the web from the desired path of travel, and a tilting of the roll in a direction and magnitude to tend to maintain the web in its corrected path.

Another object of this invention is to provide a web guiding apparatus in accordance with the foregoing object and which maintains more uniform tension in the web as it passes thereover.

A further object of this invention is to provide a web guiding apparatus in accordance with the foregoing object and which provides firm support for the guide rolls and which minimizes the effect of wear and looseness in the relatively moving parts of the roll support mechanlsm.

Another object of this invention is to provide a web guide roller assembly wherein the guide roller is mounted for movement in the arcuate path having a large radius of curvature, and wherein the web guide roller assembly occupies only a small space.

Yet another object of this invention is to provide a web guide roller assembly having an improved arrangement for guidably supporting the roll for movement along a preselected path.

Another object of this invention is to provide a web guide roller assembly wherein the guide roll is supported for movement in an arcuate path without the use of pivots and the like.

Yet another object of this invention is to provide an improved guide assembly for slidably supporting elements for relative movement along a path.

Still another object of this invention is to provide a guide assembly which is adapted for supporting elements for relatively sliding movement along non-linear paths.

These, together with other objects and advantages of this invention will be appreciated as the invention becomes better understood by reference to the following detailed description, when taken in connection with the accompanying drawings wherein:

FIGURE 1 is a diagrammatic side elevational view of a web guiding apparatus embodying features of the present invention;

FIG. 2 is a fragmentary plan view of the web guide roll assembly, with parts broken away to illustrate details of construction, and with the control system shown schematically;

FIG. 3 is a fragmentary side elevational view of the Web guide roller assembly on a larger scale than FIG. 2, and with parts broken away to illustrate details of construction;

FIG. 4 is an end elevational view of the web guide roll assembly, on the same scale as FIG. 3;

FIG. 5 is a fragmentary sectional view illustrating the support apparatus on an enlarged scale;

FIG. 6 in a fragmentary sectional view taken on the plane 6-6 of FIG. 5;

FIG. 7 is a fragmentary transverse sectional view taken on the plane 77 of FIG. 5;

FIG. 8 is an end elevational view illustrating a modified web guide roll assembly; and

FIG. 9 is an end elevational view illustrating an alternative arrangement for threading the web through the guide roll assembly of FIG. 8.

The present invention is directed to a web guiding roll apparatus for laterally guiding a traveling web indicated at W in FIGS. 1 and 2, intermediate the ends of the web. In order to exert a lateral action on the web, the guide roll must be in frictional engagement with the web, and this frictional engagement is determined by the tension in the web passing over the guide roll and the wrap of the web around the guide roll. As diagrammatically shown in FIG. 1, the movable guide roll 10 is maintained in frictional engagement with the traveling web W, by positioning the guide roll offset from a plane through the adjecent stationary guide rolls 11 and 12 so that the web W, traveling in the direction indicated by the arrow in FIG. 1, undergoes a change in direction as it passes from the lead roll 11 over the guide roll 10 and to the following roll 12. The physical relationship of the guide roll with the lead and following rolls in FIG. 1, is, of course, only by way of example, it being understood that the physical arrangement of the lead and following rolls will vary with different machines, and that these rolls can be vertically offset, horizontally offset or both vertically and horizontally offset from each other. Moreover, the amount of wrap of the web around the guide roll will also vary in different installations depending upon various factors including web tension, the type of material forming the surface of the web and the guide roll which affects the friction therebetween, as well as other factors such as space limitations in a particular installation. Moreover, although the Web guide roll assembly shown in FIG. 1 employs a single roll, it is to be understood that the web guide roll assembly could employ plural rolls. By way of further example there is illustrated in FIGS. 8 and 9 a double roll web guide assembly having rolls 10a and 10b mounted for rotation about spaced parallel axes. In the embodiment shown in FIG. 8, the web undergoes a change of direction of approximately 180, and undergoes a first 90 change of direction in passing over the roll 10a and a second 90 change of direction in passing over the roll 10b. In the form shown in FIG. 9, the dual rolls are disposed in approximately the plane of the incoming and outgoing runs of the web W, and the web is maintained in frictional engagement with the rolls by passing over one of the rolls such as 10a and then under the other of the rolls such as 10b.

The web guide roller assembly of the present invention is arranged to support the guide roll from movement in an arcuate path transverse to the path of travel of the web so as to produce a combined longitudinal shifting and tilting of the guide roll as it moves through the arcuate path. Longitudinal movement of the guide roll in a direction transverse to the path of web travel, and opposite the direction of deviation of the web from the desired path, produces a relatively rapid correction of the path of travel of the web. However, if the factors which initially caused the web to move out of the desired path continue to exist, the web will tend to creep back out of position. The tilting of the guide roll as it is moved in the arcuate path applies a continuous correction to the traveling web and thus tends to maintain the traveling web on the corrected path. In order to avoid damage such as nonuniform stretching or even tearing of the web due to movement of the guide roll, the web guide roll assembly is so arranged that the tension in the web passing over the guide roll remains substantially constant during movement of the web guide roll transversely of the path of travel of the web.

Referring more specifically to the accompanying drawings, the web guide roll-er assembly includes one ormore web guide rolls 10 rotatably supported as by bearings 15 at their opposite ends. The roll support bearings are mounted on a movable roll support structure 16, and the movable roll support structure is mounted by guide means 17 on a stationary support structure 18. The movable roll support 16 advantageously comprises a rigid structure, herein shown in the form of a generally channel-shaped member 21 which extends the length of the guide rolls, and has the bearings 15 rigidly secured thereto so that the bearings are maintained in fixed relation and in axial alignment by the movable support structure. The stationary support structure 18 also advantageously extends the length of the rollers and, as shown, is also in the form of a generally channel-shaped member 22. The stationary support member may be supported in any suitable manner on the frame ofthe machine and, as shown, is mounted by brackets 24 and legs 25 on a frame section 26 of the machine.

As previously described, the guide roll is movable in an arcuate path transverse to the path of travel of the web, the center of which arcuate path is offset a substantial distance to one side of the rolls. The radius of curvature of the arcuate path of movement of the roll controls the amount of tilting of the roll for each unit of endwise movement of the roll in a direction transverse to the path of web travel, with the tilting of the roll increasing as the radius of curvature is decreased, and vice versa. The radius of curvature to be employed will vary in different installations dependent on various factors including web width, flexibility of the web, friction coefficient of the web with the guide roll, the amount and evenness of tension in the web, and speed of the web. In general, it has been found preferable to employ a radius of curvature of from two to eight times the width of the web being guided by the roll. However, in some applications, particularly those involving very high web speeds, it is advantageous to use a smaller radius of curvature, for example of the order of one-half the width of the web. The guide rolls have an overall length-which is greater than the maximum width of the web to be guided thereby, by an amount somewhat greater than the total transverse movement of the guide rolls relative to the webs during guiding of the web. In the embodiment shown in FIG. 2, the guides 17 are arranged to support the guide rolls for movement above an arc center C which is laterally offset from the guide rolls a distance substantially equal to twice the length of the guide rolls, and with the arc center disposed in a plane perpendicular to the guide rolls substantially medially between the ends thereof, when the guide rolls are in their mid-position shown in FIG. 2.

The guide mechanism 17 includes arcuate guideways on one of the support structures and followers attached to the other support structure and engaging the guideways to mount the movable support structure for movement in the aforedescribed arcuate path. In order to facilitate formation of the arcuate guideways having the large radius of curvature, the guideways are advantageously in the form of arcuate bars. At least one and preferably two or more arcuate bars indicated at 31 and 32 are provided adjacent each end of the support structures to'provide a stable support for the movable support structure on the stationary support structure. The arcuate bars can be mounted on either of the support structures and, as shown, are attached to the stationary support structure in spaced relation thereto as by spacers 35 and fasteners 36. The

bars

31 and 32 at each end of the support structure define circular arcs having radially inner and

outer surfaces

31a, 31b, and 32a, 32b generated and mounted about the aforedescribed common center C. The bars 31 are spaced radially outwardly from the bars 32 and the bars 32 accordingly have a radius of curvature which is smaller than that of the bars 31 by an amount equal to the difference in the radial spacing from the common center. The guide bars 31 and 32 are preferably made of polygonal crosssection, such as the square crosss-section illustrated in FIG. 7, with upper and lower surfaces 31d and 31e disposed in relative parallelism.

The guide bars have a length-such as to provide a space between the end supports 35 at least equal to the desired lateral movement of the guide roll and arepreferably mounted adjacent the ends ofthe support structures to provide longitudinal stability. It is apparent, however, that the guides could be'moved closer to the center of the structures with some loss in stability and may, for narrower webs, merge adjacent the center of the web guide structure. e U v The followers 35 are attached to the other of the support structures, and as shown herein are attached to the movable support structure 21. The followers are particularly adapted for use on arcuate guide bars and are so constructed to facilitate adaptation of the followers to guide bars having different radii. As best shown in FIGS. 7, the followers include a follower block 37, which block includes a mounting portion 38 attached as by a fastener or fasteners 39to one of the support structures 21. The block also includes spaced leg portions 41 extending along opposite sides of the inner and outer surfaces of the guide bar, adjacent each end of the guide block. As shown in FIG. 6, the leg portions are laterally spaced apart a distance somewhat greater than the radial width of the guide bar so as to loosely receive the'guide bar therebetween. The bearing for supporting the follower on the guide bars is advantageously'made up of a plurality of laminations indicated collectively at L, and which laminations extend cross-wise of the guide bar and have openings 42 therein for slidably receiving the guide bar. The laminations are attached to the slide block as by pins 43 which extend through

openings

44 and 45 in the laminations and into openings 46 in the leg portions 41' of the slide block.

As will be seen from FIG. 6, the laminations are preferably arranged to conform generally to the arcuate surfaces of the guide bars. This can be achieved by'assembling the laminations into the blocks while the laminations are mounted on the arcuate guide bar to be laterally positioned thereby, and thereafter drilling or forming holes in the laminations and inserting the pins-43. Alternatively, the

openings

44 and 45 in the laminations can be formed simultaneously with the forming of the-guide bar openings 42, in'a punching operation. Inorder to accommodate the curvature of the guide bars, one-or more additional sets of laminations may be formed in which the

openings

45 and 44 are offset to one side from the'positions shown in FIG. 7, so that, when the laminations are assembled with the

openings

45 and 44 in alignment, the openings 42 can be staggered as shown in FIGK'6 to accommodate the curvature of theguide bar.

It is contemplated that the overall length of the stack of laminations be such as to provide a bearing area somewhat greater than that necessary to adequately support the roller assembly, and that certain of the laminations such as those shown at L1-L6 in FIG. 5, be formed of a material having good wear resistant characteristics, while the other laminations are formed of aditferent material having good lubricating characteristics. In order-to accommodate minor tolerance variations and to assure a snug sliding fit between the-followers and the guide bars, it is preferable to form the laminations of plastic material. For example, it has'been found-advantageous to form certain of the laminations L1-L6 of nylon, preferably impregnated with'a' lubricant such as molybdenum-disulphide powder, graphite or the like. The other laminations are advantageously formed of-a material such as Teflon which has a low coefiicient of sliding friction and which tends to lubricate the guide rod.

Various different mechanisms may be provided for shifting the moveable supportrelative to the stationary support along the aforedescribed-arcuate path.- In the embodiment illustrated, the means comprises a fluid actuator 51 including a cylinder 52 and a piston 53-in the cylinder having a rod 54extending outwardly therefrom. The actuator 51 is advantageously mounted between the 'stationary and movable supports 22 and21, intermediate the ends of the roll to provide a compact assembly. Since the movable support moves in an arcuate path relative to the stationary support, the actuator 51 is connected to the movable and stationary supportsin a manner to accommodate relative arcuate movement therebetween. As shown, thecylinder 52 is mounted by a gimbal joint 55 to a bracket 56' attached to the stationary support and the rod 54 is similarly connected by a gimbal joint 58 to a bracket 59 on the movable support.

Any suitable or conventional means may be provided for actuating the roll shift mechanism 51 in accordance with the position of the web to automatically move the guide roll in a direction and distance to correct the deviation of the web from the desired path. One suitable mechanism is shown herein and includes an edge sensor 61 mounted by a bracket 62 on a rod 63 for adjustment crosswise of the path of travel of the web. The bracket is slidable along the rod and is adapted to be secured in adjusted position as by a locking screw 64 and, conveniently, the sensor 61 is adjustably mounted on the bracket 62, as by a screw thread adjusting arrangement indicated at 65, to permit fine adjustment of the sensor position. The sensor shown is of the vacuum type and ineludes an opening 67 in a web support member 68, and which opening is connected through a vacuum tube 69 to a servo-mechanism for actuating the roll moving means 51. As diagrammatically shown in FIG. 2 the servomechanism includes a hydraulic pump 71 driven by a motor 72 and which pumps fluid from a reservoir 73 through a strainer 74 and filter 75 to a reversing valve 76. A relief valve 77 is provided at the outlet of thepump to prevent buildup of excess pressure in the system. The valve 76, as diagrammatically shown, is of the 4-way reversing type with a center close position and includes inlet and return ports 76a and 76b, and control ports 76c and 76d. The control ports are connected to

lines

77a and 77b to the cylinder 52 adjacent opposite ends and the valve is movable from the center close position to one position applying fluid pressure through line 77a to one end of the cylinder and a second position applying fluid pressure through the other line 77b to the other end of the cylinder. The valve 76 is normally urged to one flow position by a spring 81 and is moved to its other flow position by a vacuum operator 82. A signal generator, conveniently in the form of a constant vacuum pump apparatus 85 driven by the electric motor 72, has its vacuum line 86 connected to the vacuum operator 82, and a vacuum control line 88 is also connected to the vacuum operator. When the control line 88 is vented to atmosphere, no vacuum can build up in the operator 82 and under these conditions a spring 81 moves the valve 76 to one flow position, that is to the right as viewed in FIG. 2. When the 'vacuum control line 88 is wholly or partially closed, the vacuum builds up in the operator 82 and moves the valve member against the bias of the spring 81, and to the left as viewed in FIG. 2 through the intermediate closed position shown in FIG. 2, and to the other flow position. The control line 88 can be connected directly to the vacuum control port 67 in the sensor. However, it is preferable to also employ a centering valve indicated at 91 and to provide a selectively operable valve 92 for selectively connecting the control line 88 to either the centering valve 91 or to the sensor 67. The centering valve 91 is provided to enable automatic centering of the roller during startup of the machine and includes a valve body conveniently in the form of a tube 92 mounted as by a gimbal joint 93 on one of the support structures such as the stationary structure 22. The tube has an axial passage 94 thenein and a lateral port 95 which vents the axial passage to atmosphere, and a valve member 96 is mounted for movement in the tube to control flow through the port95. The valve member is conveniently in the form of a rod connected through a gimbal joint 98 to the other support structure 91 for movement therewith.

,The valve 92 is of the 3-way type and has one port 92a connected to the vacuum control line 88, a second port 92b connected to the tube 69 leading to the sensor,

and a third port 920 connected through a line 101, to the centering valve 91. When the 3-way valveis in the position shown, it communicates the centering valve with the vacuum control line 88 and the centering valve is so arranged that when the roll is in its mid-position as shown in solid lines in FIG. 2, the valve member 96 is disposed approximately mid-way across the port 95. If the guide roll is displaced to the left from the mid-position shown in FIG. 2, the port 95 will be opened and the spring 81 will then move the hydraulic control valve 76 to a position applying fluid pressure from the hydraulic pump 71 to the control port 76d to thereby move the guide roll to the right. If the guide roll is to the right of the center position, the port 95 in the centering valve will be closed and the vacuum operator will move the hydraulic valve 76 to a second flow position applying fluid pressure to the control port 760, to thereby move the roll to the left. In its mid-position, the valve partially closes the port 95 so that the vacuum in the operator 82 can move the valve to its mid-position shown in FIG. 2. The 3-way valve 92 can be selectively moved to another position connecting the vacuum control line 88 only with the sensor port 67. When the valve 92 is in this last mentioned position, movement of the roll is controlled only by the sensor. When the port 67 in the sensor is uncovered, it will cause the guide roll to be moved in one direction and, when the sensor port is completely covered, it will cause the guide roll to move in the other direction. When the edge of the traveling web bisects the opening 67, the control valve is moved to its mid-position shown in FIG. 2 to thereby interrupt movement of the guide roll and hold the same in the moved position.

As will be seen, the roller support mechanism supports the same from movement in an arc having a large radius and the roll is movable from a mid-position, in which it is substantially centered with respect to the traveling web and extends perpendicular to the path of travel of the web, selectively to the right or to the left of the mid-position. The center C of the arcuate movement of the roll is offset from the side of the guide roll at which the web enters the roll so that, as the guide roll is moved axially in one direction such as to the left of the center position, it is simultaneously tilted in a direction such that the web leaving the roll at right angles thereto will also be directed toward the left. Conversely, when the guide roll is shifted axially in a direction toward the right, it is also tilted in a direction such that the web leaving the guide roll will be directed toward the right. In practice, only a relatively short axial movement of the roll is usually all that is required to correct the deviation of the web from the desired path of travel. With some web materials, such as those which do not stretch appreciably, only a relatively small roll travel is necessary of the order of /2 inch to 1 inch. With more resilient and stretchable materials, somewhat greater movement of the roll is necessary, but generally no more than 6". When the radius of curvature of the are through which the roll is moved is large as compared to the length of the rolls, it will. be seen that the effective are through which the roll is moved from its mid-position to either extreme left or right positions, is relatively small, of the order of 1.5 or 2". As will be seen from FIG. 2, the center of the roller during movement from one extreme position to the other, does not shift significantly in a direction parallel to the path of web travel. The angle of the guide roll changes as the guide roll moves away from the center position by an amount corresponding to the tangent of the angular movement of the roll about the center C. In the very low angular movements encountered, that is of the order of 1.5 to 2 maximum, the tangent function is substantially linearly proportional to the angular displacement and the inclination of the roll is therefore approximately linearly proportional to the longitudinal movement of the roll away from the mid-position. Thus, the correcting force pro- 8 duced by inclining the guide roll is proportional to the longitudinal movement of the guide roll.

It is highly desirable in web guiding to avoid non-uniform tensioning of the web during the web guiding operation to not only avoid stretching or even tearing of the sheet, but also to avoid applying a tension to one side or the other of the sheet which will, as previously discussed, tend to cause the web to move in a direction to increase the tension in the web. It will be more apparent from FIG. 1 that the tension in the web W will remain constant during movement of the guide roll if the distance a-o-b remains constant, that is if the length of the web between the point a where it leaves the lead roll and the point b where it begins to wrap on the following roll, does not change during movement of the roller. In other words, the movement of the roll or any point on the roll in a direction parallel to the path of travel of the web, should be along a curved line indicated at c in FIG. 1, and which constitutes the locus of points, the sum of whose distances from a-o-b, remains constant. If the rolls 11, 10, and 12 had negligibly small diameters, this locus of points would define an ellipse, the foci of which would be the points a and b where the web respectively leaves the lead roll and begins to wrap on the following roll. However, the diameters of the several rolls are not negligible and the curve c differs from a true ellipse due to the changing wrap on the lead and following rolls which causes shifting of the points a and b as the guide roll is moved.

The roll support mechanism of the present invention supports the guide roll from movement in a plane and, in order to minimize changes in tension in the Web during tilting of the roll, the plane of movement in the guide roll is preferably arranged so as to be parallel to a tangent t to the curve 0, when the roll is in its mid-position. As will be appreciated, the curve 0 can be readily prepared graphically if the positions and diameters of the lead and following rolls are known, by merely mounting disks on a board of a size and in a location corresponding to the guide roll and the lead and following rolls; drawing an inextensible element over the rolls in the manner in which the web would pass thereover and then shifting the disk corresponding to the guide roll in a manner to maintain the distance a-(Fb fixed. The plane of movement of the support mechanism can then be graphically determined to lie parallel to the tangent to this curve when the roll is in its mid-position.

From the foregoing it is thought that the construction and operation of the web guide roll apparatus will be readily understood. The arcuate guide bars and followers support the roll from movement in an arcuate path transverse to the path of movement of the web, the arcuate path having a large radius of curvature with the center laterally offset from the guide roll in the direction from which the web winds onto the roll. The movement of the roll in the arcuate path transverse to the web produces a combined endwise movement of the roll and a tilting of the roll in a direction to compensate for deviations of the web from the desired path of travel. Although the web guide apparatus is movable through an arc having a large radius of curvature, the roller support assembly is such as to provide a stable support which is compact so as to allow mounting of the guide roll assembly in a minimum of space. In this regard it is noted that the only point that there is relative movement between the parts and at which wear or looseness can occur, is between the followers and the guides. However, the followers and guides are so arranged in close relation to the guide roll as to minimize the effects of any looseness or wear between the relatively moving surfaces. Moreover, the guides and followers are compactly located intermediate the ends of the guide roll and between the stationary and movable support structures to provide a compact assembly. The geometry of the steering mechanism wherein the rollers move through an arcuate path having a large radius of curvature provides improved web guiding while minimizing changes in tension in the web during movement of the web guide roll.

As will be seen, the followers. can be economically fabricated by punching the laminations from sheet stock. The laminations can be assembled on the carriers to conform to non-linear rods and, when the laminations are formed of plastic material, the individual laminations can deform slightly to accommodate slight differences in the curvature of the follower and that of the guide rods, and to also accommodate slight tolerance variations in the mounting of the guide rods and followersFollowers having some laminations formed of nylon and others formed of Teflon have been found to provide good wear resistance with low sliding friction.

While a preferred embodiment of the invention has been herein illustrated and described, it is to be understood that this description is made only by way of example and that I do not wish to be limited except as required by the appended claims.

I claim:

1. In an apparatus for guiding a traveling web of material along a preselected path of web travel including, at least one web guide roll and means mounting said guide roll for movement in an arcuate path crosswise of the path of web travel and with the guide roll in frictional engagement with the traveling web, said roll mounting means including:

stationary roll support means; movable roll support means rotatably supporting said roll;

means on one of said support means defining arcuate guideways constituting circular arcs having a common center offset a substantial distance from one side of the guide roll, and follower means on the other of said support means engaging said arcuate guide ways and supporting said movable support means on the stationary support means for movement relative thereto in an arcuate path along said guideways; and means responsive to transverse deviation of the web from said preselected path of web travel for moving said movable support means and the roll supported thereby along said arcuate path in a direction to correct the path of travel of the web.

2. An apparatus according to claim 1 in which said movable roll support means includes a rigid structure extending the length of the guide roll and having hearing means rotatably supporting opposite ends of the roll on said rigid structure.

3. An apparatus according to claim 1 wherein said arcuate guideways include radially inner and outer guideways having said common center, said follower means engaging said inner and outer guideways.

4. An apparatus according to claim 1 in which said center is spaced from said roller a distance at least twice the length of the guide roll.

5. An apparatus according to claim 1 in which said arcuate guideways comprise longitudinally arcuate bars, said followers slidably engaging said bars.

6. An apparatus according to claim 1 wherein said arcuate guideways and followers are located on the respective support means intermediate the ends of the guide roll.

7. A web guide roller assembly for guiding a web of material along a preselected path comprising, at least one web guide roll adapted to extend crosswise of the path of web travel in frictional engagement with the web, bearing means rotatably supporting the guide roll, a first movable support structure having said bearing means mounted thereon, a second stationary support structure, guide bars in the form of circular arcs rigidly secured to one of said support structures with the arc centers of the guide bars disposed at a common point offset a substantial distance from the concave side of the guide bars, follower means secured to the other of said support structures and slidably engaging said arcuate guide bars for movement therealong, said arcuate guide bars and follower means supporting said first support structure and said guide roll for movement in an arcuate path along the guidebars in a direction crosswise of the path of Web travel, and means for moving said first support structure relative to said second support structure along said arcuate path.

U 8. An apparatus according to claim 7 wherein said common'point of the arc centers of the guide bars is located in a plane substantially medially between the ends of the roll.

9. An apparatus according to claim 7 wherein said first support structure extends lengthwise of the roll, said bearing means including first and second roll support bearings adjacent opposite ends of the first support structure.

10. An apparatus according to claim 7 wherein said arcuate guide bars include at least one guide bar adjacent each end of the roll.

11. An apparatus according to claim 7 wherein said arcuate guide bars include first and second sets of guide bars adjacent each end of the roll, each set including an inner and an outer arcuate guide bar having arc centers disposed at a common point with the radius of curvature of the inner guide bar smaller than that of the outer guide bar by an amount corresponding to the radial spacing therebetween.

12. An apparatus according to claim 7 wherein said followers include a plurality of laminations extending crosswise of the respective bar and having openings therein formed complementary to the bar and slidably receiving said bar, and means assembling the laminations in a stack.

13v. An apparatus according to claim 12 wherein certain of said laminations are formed of a material having wear resistant characteristics and others of said laminations are formed of a material having lubricating characteristics.

14. An apparatus according to claim 12 wherein certain of said laminations are formed of a plastic material having wear resistant characteristics and others of said laminations are formed of a plastic material having lubricating characteristics.

15. An apparatus according to claim 7 wherein said guide bars have a non-circular cross-section and said followers include a plurality of laminations extending crosswise of the respective bar and having openings therein slidably and non-rotatably receiving the bar, and means assembling the laminations in a stack.

16. An apparatus according to claim 7 wherein said first and second support structures extend lengthwise of the roll, said means for moving said first support structure relative to the stationary support structure being located between said first and second support structures.

17. An apparaus according to claim 7 wherein said first and second support structures extend lengthwise of the roll, said arcuate guide bars and followers being located on the respective support structure intermediate the ends of the roll.

18. In a guide apparatus including at least one guide bar, a follower means slidably engaging said guide bar for movement therealong, and means for effecting relative sliding movement between the guide bar and follower means in a direction lengthwise of the guide bar, characterized in that the follower means includes a plurality of generally fiat laminations each extending crosswise of the respective guide bar and having openings therein slidably reseiving said bar, and means holding said laminations in a stacked assembly.

19. An apparatus according to claim 18 wherein certain of said laminations are formed of a plastic material having wear resistant characteristics and others of said laminations are formed of a plastic material having lubricating characteristics.

20. An apparatus according to claim 18 wherein said bar has a non-circular cross-section and said openings in said laminations are shaped complementary to the bar.

21. An apparatus according to claim 19 wherein said others of said larninations are formed of a plastic consisting of a tetrafluoroethylene polymer.

22. An apparatus according to claim 18 wherein said means holding said laminations in a stacked assembly includes rigid members at opposite ends of the stack, said laminations having at least two apertures therein spaced from said openings, and pin attached to said rigid members and extending therebetween through said apertures in the laminations.

23. In a guide apparatus including at least one guide bar, a follower means slidably engaging said guide bar for movement therealong, and means for effecting relative movement between the guide 'bar and follower means in a direction lengthwise of the guide bar, the improvement wherein the guide bar has a longitudinally arcuate configuration, and the follower means comprises a plurality of generally flat laminations each extending crosswise of the respective guide bar and having openings therein slidably receiving said bar, and means holding said laminations in a stacked assembly with the openings therein arranged to form a generally arcuate passage to accommodate the curvature of the longitudinally arcnate guide bar.

24. A guide apparatus according to claim 23 wherein the guide bar has a non-circular cross section and said openings in the laminations are shaped complementary to the cross section of the guide bar.

References Cited UNITED STATES PATENTS 1,043,603 11/1912 Jones 308240 2,494,023 1/1950 Williams 308240 X 2,797,091 6/1957 Fife 226--22 3,024,955 3/ 1962 Powers 22622' 3,054,547 9/1962 Alexeif et al 226-19 X 3,317,101 5/1967 Himrod et al. 22619 ALLEN N. KNOWLES, Primary Examiner.