US3737091A

US3737091A - Web processing apparatus

Info

Publication number: US3737091A
Application number: US00261382A
Authority: US
Inventors: F Barta; A Grupp
Original assignee: Meyercord Co
Current assignee: GGA Corp A CORP OF DE; United Biscuits UK Ltd
Priority date: 1970-08-28
Filing date: 1972-06-09
Publication date: 1973-06-05
Anticipated expiration: 1990-06-05

Abstract

A web processing apparatus is provided, particularly for drying the printed surface of a continuous web. The web is disposed in festooned relation between upper driving rolls and lower restraining rolls or guides disposed in the depending loops of the festooned web. The restraining rolls or guides have end rim portions which engage and support the web at its marginal edge portions. A plurality of web correction elements, such as toothed annular elements, are provided between the rim portions, and the web is normally held in spaced relation from the web correction elements but is engageable therewith for straightening out collapsed areas or inwardly deflected portions of the web as it passes around the restraining rolls or guides. Preferably, a gaseous medium is passed through an enclosure for the festooned web, and the arrangement permits relatively high flow rates and velocities without disturbing the web.

Description

June 5, 1973 WEB PROCESSING APPARATUS Primary Examiner-Allen N. Knowles 5 1 t 1r [7 1 men ms E r uES giJ E ii ii ni A red Attorney-George N, Hibben, Lowell C. Noyes and Albert W. Bricknell et al. [73] Assignee: The Meyercord C0., Carol Stream (Wheaton), ll]. [57] ABSTRACT [22] Filed: June 1972 A web processing apparatus is provided, particularly [21] Appl. No.2 261,382 for drying the printed surface of a continuous web. The web is disposed in festooned relation between Related Appllcauon Data upper driving rolls and lower restraining rolls or [62] Division of Ser. No. 67,890, Aug. 28, 1970, Pat. No. guides disposed 3 dependmg the few) 3,694,928- oned web The restraming rolls or guides have end rim portions which engage and support the web at its mar- 52 us. 01. ..226/193, 226/197 226/189 E edge P A plurality 0f web [51] Int. Cl. ..B6 5h 17/20 mems Such as toothed annular elements are provided 58 Field ofSearch..' ..226/l90 193 196 between the rim 1 and the web is "mmally 8 held in spaced relation from the web correction elements but is engageable therewith for straightening [56] References Cited out collapsed areas or inwardly. deflected portions of the web as it passes around the restraining rolls or UNITED STATES PATENTS guides. Preferably, a gaseous medium is passed through an enclosure for the festooned web, and the :23:5 arrangement permits relatively high flow rates and 3:493il6l 2 1970 BillingsetalTIIl IH..:::....226/190 "elOcities without disturbing the 7 Claims, 15 Drawing Figures /L 1 n. -97 j 3.9 9? 3;- 3;-1 .1": 1: 1. 5:: :qQzr: 3:"

l .I w M .5 9 1 92 9+ 91 0.9

PATENTED SHEET 2 BF 6 PATENTEDJUH 5 I975 SHEET 11, 0F 6 n o ooanooo'an PMENTEUJUH 5197s SHEET 5 BF 6 llllllllll// PATENTEUJUH 5 I975 SHEET 6 [1F 6 WEB PROCESSING APPARATUS This is a division of application Ser. No. 67,890 now U.S. Pat. No. 3,684,928, filed Aug. 28, 1970.

This invention relates to an apparatus for the processing of various kinds of material in continuous web or strip form. More particularly, the invention relates to the drying of a continuous web which has been coated, printed, or.otherwise treated on one face so that contact with the treated face must be avoided until it has dried.

Silk screen printing is customarily done on individual sheets of paper which must be dried thoroughly after each printing step. Consequently, multicolor screen printing is an expensive and time-consuming operation. Continuous silk screen printing on web stock has also been proposed, but drying of the printed web still presents a substantial problem. For example, in some cases the printed 'web is fed onto a long horizontal table which may extend for several hundred feet, and ambicut or preheated air is blown against the exposed web surface to effect drying so that the web can be re- -wound. Obviously, such an arrangement is costly and requires considerable working space. The drying problem is particularly acute in the manufacture of decalcomania transfers by continuous multicolor web screen printing where the color or ink deposits are frequently heavy and require extensive drying time.

Accordingly, a primary object of the present invention is to provide a novel'and improved apparatus for processing continuous web material, which apparatus is compact and which diminishes the required processand improved means for restraining the depending loops of web material in a festooned web processing or drying system.

An additional object of the invention is to provide novel and improved web correction means for straightening out, collapsed areas, including wrinkles, buckles, creases, and the like in the web of a festooned web processing or drying system.

Other objects and advantages of the invention will become apparent from the subsequent detailed description in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic plan view, on a reduced scale, ofa multicolor web screen press utilizing the novel web drying apparatus of the present invention;

FIG. 2 is an elevational view as seen along the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary elevational view, partially in section, as seen along the line 33 of FIG. 1 and showing the interior of the drying apparatus;

FIG. 4 is an end elevational view as seen along the line 44 of FIG. 1 and showing the cross-over between a pair of dryer units;

FIG. 5 is a fragmentary horizontal sectional view taken along the line 55 of FIG. 4;

FIG. d is a fragmentary elevational view of a portion of a dryer unit as seen substantially along the line '6-6 of FIG. I; 3

FIG. 7 is an end elevational view as seen along the line 7-7 of FIG. 6;

FIG. 8 is an enlarged elevational view, partially in section, showing certain details of a restraining roll structure used in the dryer and also showing schematically the manner in which the roll structure functions to correct collapsed areas or other imperfections in the web;

FIG. 9 is an enlarged scale cross-sectional view of the roll structure as seen along the line 99 of FIG. 8;

FIG. It) is a fragmentary sectional view showing a modified form of roll structure;

FIG. 11 is a generally schematic view of the upper portion of a dryer unit showing the air duct arrangement;

FIG. 12 is a fragmentary elevational view showing a modification of the restraining roll arrangement;

FIG. 13 is a fragmentary view showing a modified drive arrangement for the web;

FIG. 14 is a fragmentary sectional view showing another modification of the driving arrangement for the web; and

FIG. 15 is a fragmentary elevational view showing a control means for the system.

Although the invention is hereinafter described in detail in connection with a drying apparatus for continuous web screen printing, it should be understood that the principles of the invention are broadly applicable to web processing systems generally and particularly to a web drying or processing system in which it is desirable to avoid disturbing a coating or the like on the surface of the web.

FIG. I is a diagrammatic floor plan of a four-color web screen press for decalcomania transfers which includes the novel drying apparatus of the present invention. A continuous web of paper or other suitable material for receiving screen printing is fed from a supply spool 20 disposed on a vertical axis and positively driven (by means not shown) to effect unwinding of the web from the spool without tensioning the web. The web 21 passes around

guide rolls

22 and 23 and thence to a conventional 45 turn bar 24. As best seen in FIG. 2, the web 21 changes direction by as it passes over the turn bar 24 and travels upwardly over a driving roll 26 and thence into the first print station 27. The printed web emerges from the lower portion of the print station 27 and is guided by means of a pair of rollers or web guides 28 so as to pass horizontally underneath a cross walk 29 and thence into the first of three

upright dryer sections

31, 32, and 33 arranged in endto-end relation. The details of the print station 27 are not relevant to the present invention and need not be described.

Plenum chambers

37 and 38 are provided at the tops of the

dryer sections

32 and 33, and blower means 39 and 41 are connected to the respective plenum chambers for introducing air into the dryer sections, as hereinafter described in greater detail. The web emerges from the dryer section 33 and, by means of turn bar arrangements, is directed in a reverse direction through a pair of

parallel dryer sections

42 and 43 which are provided with

upper plenum chambers

44, 46 and blowers 47, 48.

- At this point the application and drying of the first color print has been completed, and the web now en-.

' at 51 and is similar to the

dryer sections

31, 32, 33 following the first print station. The web emerges from the three section dryer 51 and its direction is reversed by turn bars, as indicated by the arrows, and drying of the web is completed in the final pair of dryer sections which are indicated generally at 52 and which correspond to the

dryer sections

42 and 43 previously described. The web then enters a third print station 53 for printing a third color, passes horizontally beneath the cross walk 29 and through a three-section dryer unit 54 and thence in reverse direction through a two-section dryer 56. Finally, the web enters the fourth print station 57 for printing a fourth color, passes horizontally beneath the cross walk 29 and through a three-section dryer 58 and thence in the reverse direction through a three-section dryer 59 having

sections

59a and 59b equipped with plenum chambers and blowers and a web emerges from the last dryer section 59c and passes downwardly and thence upwardly around a dancer roll 60 which is journaled in bearings forming part of an endless chain 61 trained around sprockets 61a and 61b. The web passes over guide rolls 62 and then downwardly to a 45 turn bar 63, thereby changing the direction of movement of the web by 90. The web passes around a pair of guide rollers 64 and is then rewound loosely on a spool 65 which is disposed on a vertical axis and is positively driven (by means not shown) at the speed required to effect loose ceiling of the web. If

of the dryer sections. Obviously, the provision of a plu- A rality of dryer sections following eachprint station affords wide flexibility of operation to meet the varying requirements of different printing jobs. Also, while the arrangement of the print stations and dryers at opposite sides of the cross walk 29 provides a compact and highly convenient system requiring the minimum number of operating personnel, it should be understood that the invention is not limited to this arrangement and that any desired floor layout can be used.

Referring particularly to FIGS. 2-7, the details of the dryer sections will now be described. As will be apparthat a plurality of dryer sections can be aligned in end- I to-end relation to form an elongated enclosure such'as the three-section dryer unit 31-32-33 shown in FIGS.

I I and 2. As best seen in FIG. 4, each dryer section in the illustrated embodiment of the invention is provided with four removable glass panels or windows'7l, but

- anydesired number of panels can be used.

FIGS. 6 and 7 illustrate the, interior of the firstdrye section immediately following a print station. The

freshly printed web 21 enters horizontally from beneath the cross walk 29 and passes around the guide desired, a continuous web of slip sheet material may be I and the dancer roll 60 moves up or down, thereby shiftmember 28 which, in this instance, is in the form of a nonrotatable semi-circular roll having a special ma uration, as described below. The web passes upwardly from the guide member 28 and enters the dryer section where it is disposed in festooned relation between a plurality of upper drivenrolls 72 having end sprocket members 72 and a plurality of lower restraining rolls designated generally at 73 and hereinafter described in detail. The rolls72 are mounted on rotatable shafts'74 journaled between elongated supports 75 which are in turn mounted on the framework 'of'the dryer. The sprockets 72 are provided with pegs 76 which titinto,

perforations 77 along the elongated marginal edge poring the position of the chain 61 and rotating the sprock- I ets 61 a and 61b. A cam (not shown) on'one of the sprockets 61a or 61b is arranged to actuate a control element (not shown) for regulating the speed of the rewind spool 65 so as to insure a loose wind.

Although the invention is herein illustrated in connection with a press having four print stations for printing four colors and with five dryer sections being provided after each print station, it will beunderstood that any desired number of print stations can be used and i any desired number of dryer sections can be provided after each print station with varying combinations of tions of the web 21 for positively engaging and transporting the web from theinlet end to the outlet end of the dryer. As will be evident from FIG. 6,the festooned web 21 extends in a sinuous or zig-zag path between the rolls 72 and the rolls 73, and a depending loopof the web is disposed between each adjacent set of rolls 72 with the lower end or bight portion of the loop receiving'the roll 73. The shafts 74 are rotatably driven by means of sprockets 78 (FIG; 4 and 7) mounted on the mounted on the guides 79 and have actuating or feeler arms 80 which extend across the space between the guides above and below the roll spindle. Thus, if the roll undergoes excessive vertical movement, one of the arms 80 will be actuated and the complete press will be automatically shut down so that the malfunction can be corrected.

The arrangement in each dryer section is such that the web driving rolls 72 contact only the unprinted side of the web 21, but the restraining rolls 73 are adapted to engage the printed side of the web. The restraining rolls 73 are preferably supported in the bight portions of the web loops so as to maintain the opposed printed faces of each loop in spaced apart relation. Moreover, although the restraining rolls 73 are relatively light in weight, the weight is sufficient to maintain the web loops in depending spaced-apart relation so that air or other gaseous medium can be passed through the enclosure of the dryer at relatively high flow rates and velocities without causing the festooned loops of the web to be moved into contact with each other. To further assist in limiting the extent of movement of the festooned loops, a plurality of upright guides or abutment members in the form of thin plates 81 (FIGS. 6 and 7) are rigidly affixed to the lower portion 82 of the dryer framework at each end of the restraining rolls 73. Thus, the guides 81 are interposed between the end portions of adjacent restraining rolls 73 to limit the extent of lateral movement of the depending loops of the web.

FIGS. 4 and 5 illustrate a typical crossover of the web between parallel dryer units, in this case the

dryer units

58 and 59 0f FIG. 1. As seen in FIG. 4, the web 21 emerges in a downwardly moving direction from the exit end of the enclosure of the dryer unit 58 and passes around a 45 turn bar 83 which changes the direction of movement of the web from vertical to horizontal. The horizontally moving web is threaded around a pair of guide rolls 84 and an intermediate turning roll 86 having a special construction hereinafter described. The

rolls

84 and 86 are rotatably mounted on vertical axes between a pair of angle members 87 secured to the framework of the adjacent dryer section 59. The web 21 then passes to another turn bar 88 inclined oppositely to the turn bar 83 for directing the web upwardly into the top of the next dryer unit 59. It will be understood that only the unprinted side of the web contacts the turn bars 83 and 88 and the guide rolls 84, but the printed side of the web is adapted to engage the special turning roll 86.

Another importantfunction of the restraining rolls 73 is to provide a web-straightening or corrective effect, and for this purpose a special construction is employed for the roll 73 as will now be described with particular reference to FIGS. 8 and 9. As seen therein, the roll 73 has a cylindrical body member 91 which is preferably of light-weight tubular material. For example, the body member 91 may be formed from a thin section or sheet of plastic material such as Mylar curled into cylindrical shape and having its edges fastened together, as by stapling or taping. Circular end members 92 are provided at each end of the cylindrical body 91 and are preferably made of light-weight metal, such as aluminum. Each end member 92 comprises an end closure for the cylinder 91 and has a radially extending flange portion 93 and an axially extending rim portion 94 with the flange 93 of greater diameter than the rim portion 94. The opposite ends of the cylindrical body member 91 are received in close fitting relation in the central recesses in the end members 92 defined by the axially extending rim portions 94, as seen in the broken away portion at the right-hand side of FIG. 8. An elongated rod 96 extends through the body member 91 between the end members 92, and suitable fasteners, such as nuts 97, are secured to the projecting ends of the rod 96 for holding the end members 92 in assembled relation with the cylindrical body member 91.

A plurality of web-correction elements in the form of thin annular elements or rings 98 are fitted on the cylindrical body member 91 and are disposed in axially spaced relation along the length of the body member 91 between the rim portions 94 of the end members 92. Preferably, each annular element or ring 98 has a plurality of integral axially extending flange portions 99 bent outwardly adjacent the central opening of the annular element. As seen in FIG. 8, the flange portions 99 are disposed in surface contact with the outer surface of the cylindrical body 91 for stabilizing the elements 98 and providing increased frictional surface engagement therebetween. If desired, the elements 98 may be further secured in position on the body member 91 by pieces of pressure sensitive tape extending across the flanges 99 and the adjacent portion of the body 91. Also, if desired the flanges 99 may be of sufficient axial extent to function as spacers for the elements 98, in which case each element 98 abuts the outer ends of the flanges 99 on the adjacent element. 7

The outer periphery of each annular element or ring 98 is provided with a multiplicity of circumferentially spaced projections, such as the blunt teeth or serrations 101 shown in FIG. 9. As will be evident from FIGS. 8 and 9, the projections or teeth 101 are of lesser radial extent than the rim portions 94. Consequently, the marginal edge portions of the web 21 are engaged by the rim portions 94 so that the restraining roll 73 is normally supported in the bight portion of the loop of the web solely by the rim portions 94 with the flanges 93 abutting the side edges of the web. Thus, as seen in solid lines in FIGS. 8 and 9, the central portion of the web between its longitudinal edges is normally retained in slightly spaced relation from the web correction elements 98, thereby normally avoiding any contact with the printed side of the web. However, dependent upon the characteristics of the web material, there is a tendency for the moving web to develop collapsed areas such as wrinkles, buckles, creases, or other inwardly deflected portions which would be highly detrimental if allowed to remain and would be particularly objectionable when the web enters one of the print stations. This effect is particularly troublesome in the area of a splice or joint between web sections In accordance with the present invention, any collapsed area or inwardly deflected portions of the web 21, as indicated schematically in broken lines in FIGS. 8 and 9, will be engaged by the multiplicity of teeth or other projections on the web-correction elements 98, thereby eliminating the web imperfections as the web moves around the restraining roll 73.

Thus, as seen in FIG. 9, the inwardly deflected portion 21 of the downwardly moving web at the left-hand side of the loop is engaged by the teeth 101, and by the time the web has traversed the underside of the roll 73 and moves upwardly at the right-hand side of the loop,

the web has been straightened and the deflection eliminated. Although the printed side of the web is at the inside of the loop facing the roll 73, the only contact with the wet printed surface is by means of the large number 108, and suitable fasteners, such as the nuts 113 and I 114, are affixed to the outermost ends of the rod 112. A compression spring 116 encircles the end portion of the rod 112 between the nut 114 and the adjacent end 1 member109 for urging the telescoping body sections l07 and 108 toward each other. Thus, the peripheral flanges, designated at 1 17, on the end members 109 are held in abutment with the elongated side edges of the web 21 under the action of the spring 116. It will be unand fragile web materials can be handled with the present invention since the repeated passage of the web around the restraining rolls 73 straightens out wrinkles and the like in the web and insures a smooth web which can be printed upon and dried without disfiguration In general, the diameter of the restraining roll 73 should be as small as the web material will permit, but thicker or stiffer web materialswill generally require a somewhat larger roll diameter than light-weight thin web materials. Likewise, the axial spacing between adjacent web correction elements 98 must be correlated with the nature of the web material. In general, it is desirable to use as few of the elements 98 as possible in order to keep the weight of the roll to a minimum, but the elements 98 must be close enough together to prevent collapsing of the web during passage through the dryer. Preferably, the circumferential spacing between the projections or teeth 101 on the elements 98 should be less than the axial distance between adjacent elements 98.

As an example of a typical construction for the roll 73, the body portion 91 may be formed from a sheet of Mylar plastic material having a thickness of a few thousandths of an inch and an axial roll length of about thirty inches. The end members 98 are formed of light gauge aluminum metal. The web correction elements derstood that the spring 116 allows the

body sections

107 and 108 to contract or expand automatically so as to accommodate variations in the width of the web, e.g. due to web shrinkage.

FIG. 12 illustrates a further modification with respect to supportfor the restraining rolls 73. In the previously described embodiment, the full weight of each freefloating restraining roll 73 is supported by the depending loop of the web. In the FIG. 12 modification, the

' construction of the restraining roll 73 is essentially the same as described in connection with FIGS. 8 and 9 exceptthat special suspension means is provided for the rolls 73 so as to reduce the extent of the force imposed on the loops of the web to any desired degree. For'this purpose, each end of the rod 96 extending through the roll 73 is provided with a bracket 12] which is connected by a wire or rod 122 to a helical tension spring 123 which is in turn suspended from a cross support 124. The support 124 may be adjusted upwardly or 98 are thin gauge aluminum, and approximately twenty I of the elements 98 are equally spaced along the length of the body 91. Each ring element 98 has 40 teeth, making a total of eight hundred potential contact points. The total weight of the roll 73 is approximately 300 grams. Experience has demonstrated that the aforesaid roll design will readily accommodate a web thirty inches in width comprising a widerange of materials, e.g. from a relatively heavy stiff material, such as ever, passage of a gaseous medium through the encloa vinyl plastic-paper laminate about 0.0012 inch in I downwardly '(by means not shown) so as to exert, through the springs 123, any desired counterbalancing effect on the rolls 73 and thereby diminishing to any desired extent the weight which is imposed on each depending loop of the web. As will readily be understood, the spring suspension for the rolls 73 is particularly useful in the case of very fragile web materials which would not be able to withstand the full weight of the rolls 73. Obviously, other counterbalancing arrangements couldbe used with similar effectiveness.

As previously mentioned, a gaseous medium is preferably passed through all or a portion of the enclosure of the web processing apparatus to effect dryingor other treatment of the web. Such gaseous medium may comprise air, steam, ozone, sulfur dichloride, or other selected drying or treating agent. In some cases, howsure may be omitted entirely, e.g. when the web surface is being cured or dried by radiant heat or other types of radiant energy.

In the illustrated embodiment of the invention, the printed surface of the web is dried by means of air flow,

I and the arrangement for supplying heated air of con trolled moisture content to the dryer sections is best understood in connection with FIGS. 1, 3, 4 and 11. I

For example, the plenum chamber for the outermost dryer section of the dryer unit 58 is designated at 126 v in FIGS. 4 and 5 and comprises an elongated rectanguconstruction for automatically accommodating webs of i it different widths. Thus, a roll structure 106 is shown having a pair of telescopically interfitted tubular body I

sections

107 and 108 with end members 109 which are generally the same as the end members 92 of FIGS. 8 and 9. The

telescoping body portions

107 and 108 are fitted with annular web correction elements 111 which lar housing disposed over the web driving rolls at the top of the dryer section. Similar plenum chambers designated atl27 and 128 are illustrated in FIGS. 3 and 4 for the

dryer sections

59a and 59b of the dryer unit 59. Within each plenum chamber a tubular heater or heat exchanger 129 is mounted and is adapted to have are the same as the elements 98 in FIGS. 8 and 9. An

elongated rod 112 extends'between theend members 109 through the telescoping body sections 107 and steam passed therethrough for heating the air passing through the plenum chamber. As seen in FIG. 4, a blower and air intake duct is associated with each plenum chamber, as indicated by the blower 131 and intake duct 132 for the plenum chamber 126 and the intake duct 133 for the plenum chamber 127.

Air drawn in by the blower is supplied by the intake duct to the side of the plenum chamber, is heated by the heat exchanger 129, and is discharged from the plenum chamber downwardly through a plurality of elongated slots or discharge openings 134 disposed above the web drive rolls 72. In addition, elongated vertical discharge ducts 136 extend downwardly from the bottom of the plenum chambers inside the dryer enclosures, and at their lower ends the vertical ducts 136 have laterally extending branches 137 which extend into the loops of the web above the lower restraining rolls 73. The branches 137 are provided with a plurality of outlet openings for directing the heated air upwardly and outwardly against the wet printed sides of the web. Additional lateral branches may be provided on the vertical ducts 136 at any desired locations between the tops and bottoms of the dryer sections. In addition, the length of the lateral branches 137 may be varied throughout the dryer section in order to obtain optimum distribution of heated air throughout the enclosure.

In order to control the moisture content of the heated air supplied to each plenum chamber, a steam injection device is associated with each air intake. Thus, in FIG. 4 a steam supply line 138 having a control valve 139 supplies steam into an open V-shaped trough 141 disposed immediately adjacent the air intake opening 142 for the intake duct 133. A manually operated damper or butterfly valve 143 is mounted in the air intake 142. As air is drawn by the blower through the air inlet 142, any desired amount of steam may also be drawn in with the air by regulation of the valve 139.

FIG. 11 is a schematic arrangement of the air supply system described above. Thus, a plenum chamber 146 is disposed over the upper end of a dryer section and has air outlets 134 disposed over the web drive rolls 72. Air is drawn into an inlet 147 along with a controlled amount of steam discharged from a steam supply pipe 148 adjacent the inlet 147. A damper 149 controls the inlet flow to the blower and intake duct 151. The intake duct curves downwardly and enters the side of the plenum chamber 146 where the mixture of air and steam is heated by the heat transfer coil 129 and discharged through the outlets 134. In addition, the vertical duct 136 for introducing the heated air-stream mixture to the lower portions of the dryer is also shown at the lefthand side of FIG. 11.

FIGS. 13 and 14 show alternate means for driving the web through the dryer which may be used in place of the sprocket rolls 72 previously described. Thus, in FIG. 13 a frictional drive means is provided comprising a driven roll 156 over which the web 21 extends and superimposed friction rolls 157 located at the opposite ends of the roll 156 for gripping the marginal edge portions of the web 21 therebetween. This drive arrangement eliminates the necessity for providing perforated edges in the web. FIG. 14 shows a vacuum arrangement comprising a driven hollow roll 158 having numerous openings or perforations 159. A curved vacuum head 161 is disposed within the hollow roll 158 and has a connection 162 which is adapted to be connected to a vacuum source. The web 21 extends over the roll 158, and in the region of the vacuum head 161, the suction exerted through the openings 159 causes the web 21 to adhere to or be gripped by the rotating roll 158 for driving the web. The vacuum drive roll is particularly useful when the lower restraining rolls 73 have the telescoping structure illustrated in FIG. 10.

FIG. 15 illustrates a control device which is adapted to be mounted adjacent the lower restraining rolls 73, for example, along the ends of the rolls 73 as shown in FIG. 3. The control device consists of an elongated shaft 166 which may extend along the length of the dryer sections adjacent the ends of the parallel rolls 73. The rock shaft 166 has a plurality of arms 167 rigidly affixed thereto and extending outwardly and overlying the adjacent end portions of the rolls 73. If one of the rolls 73 rises vertically, for example, due to shrinkage of the loop of the web or some malfunction in the apparatus, the roll 73 will engage the arm 167 and pivot the latter upwardly (as shown in broken lines), thereby rocking the shaft 166. A lever 168 on the shaft 168 is adapted to engage a control element 169 (such as a switch or the like) which is connected in the circuitry for the drive rolls 72 so as to shut down the operation of the dryer.

A similar arm 171 may also be disposed below each roll 73 and is rigidly secured to a rock shaft 172. A

pivot arm 173 on the rock shaft 172 is connected by a link 174 to the lever 168 of the rock shaft 166. Thus, vertical movement of a roll 73, either upwardly or downwardly, beyond a predetermined amount will result in rotation of the rock shaft 166 and actuation of the switch 169 by the lever 168 to shut down the dryer.

The control illustrated in FIG. 15 results in shutting down of the dryer if any one of the rolls 73 moves vertically to an excessive degree. However, the associated print station which is feeding the printed web to the particular dryer section continues to operate until the control device illustrated in FIG. 6 functions to shut down the entire press. Thus, even if the dryer is shut down during an intermediate operating position of the print station, the control device shown in FIG. 6 provides a time delay which permits the print station to complete its operational movement (e.g. the completion of a reciprocating movement of a printing member) before the press is shut down. It will be understood, of course, that the arrangement of the control elements in FIG. 6 is such as to permit the required vertical movement of the associated roll 73 during completion of the operational movement of the print station.

From the foregoing description, it will be seen that the restraining rolls 73 have the dual functions of weighting and restraining the lower ends of the depending loops of the webs and also providing a web correction effect by straightening. out wrinkles, buckles, creases, and similar collapsed areas or inward deflections which tend to occur in a moving web. However, the identical web correction function can also be incorporated in a structure which performs only a guide function rather than a loop restraining function in the manner of the roll 73. For example, the vertical turning roll 86 illustrated in FIGS. 4 and 5 cooperates with the guide rolls 84 to direct the web 21 in a properly aligned manner onto the turn bar 88, and the roll 86 has essentially the same structure heretofore described in connection with the roll 73 and serves to eliminate wrinkles or other imperfections in the web during the crossover or transition between parallel dryer sections.

Although the rolls 73 and the roll 86 are rotatable, it is not always necessary to provide a rotatable structure.

7 .For example, as shownat 28 FIG. 6, a guide structure of "semi-circular configuration, butojtherwisethe sired, the non-rotatable guide structuremay have a completely circular cross-sectional configuration, as in the case of the rolls 73, or in some instances the crosssectional configuration may be less than semi-circular, eg a quadrant having an outer curved surface extending over 90.

Although the invention has been described in detail in connection with certain specific illustrated embodiments, it will be understood that various modifications and equivalent structures may be resorted to without departing from the'scope of the invention.

We claim: 7 I

1. A roll or guide structure for use in a continuous web processing apparatus, comprising:

an elongated body member having at least a semicircular cross-sectional configuration;

axially extending rim portions at the opposite ends of said body member for engaging the opposite marginal edge portions of the web; and Y a a plurality of web-correction elements spaced axiall along said body member between said rim portions, said web-correction elements having a plurality of circumferentially spaced radially extending projections the outer ends of which are of lesser radial extent thatn said rim portions, whereby the central portion of the web between its side edges is normally held out of contact with said projections'but is engageable with said projections for straighten I that said roll or guidestructure comprises a cylindrical body member and end members at the endsof the body member. v c

7. Thestructure of claim I further characterized in member providing said rim portions extending circum- -ferentially around the body member and spacedoutf-f wardly from the surface thereoflsaidstructure being adapted to be received in the lower bight portion of a v depending web loop in a web-processing apparatus wherein the web is disposed in festooned relation between a plurality of web driving means with depending loops of the festooned web being disposed between adjacent pairs of driving means. I

3: The structure of claim 1 further characterized in that said web-correction elements comprise annular elements having'circumferentially spaced teeth at their outer peripheries.

4. The structure of claim 1 further characterized in that said body member comprises a section of lightweight sheet material formed into a cylinder, a pair of end closures are provided withmeans for retaining the same at the opposite ends of the cylinder, said end closures including said rim portions, and said webcorrection elements'comprise annular elements-slidat least one flange member extends axially from the edge of said opening in surface contact with said body together, whereby. said end members are automatically held in engagement with the longitudinal edges of the web.

Claims

1. A roll or guide structure for use in a continuous web processing apparatus, comprising: an elongated body member having at least a semicircular crosssectional configuration; axially extending rim portions at the opposite ends of said body member for engaging the opposite marginal edge portions of the web; and a plurality of web-correction elements spaced axially along said body member between said rim portions, said web-correction elements having a plurality of circumferentially spaced radially extending projections the outer ends of which are of lesser radial extent thatn said rim portions, whereby the central portion of the web between its side edges is normally held out of contact with said projections but is engageable with said projections for straightening out inwardly deflected wrinkles, buckles, creases, and the like, in the web as it passes around the roll or guide structure.

2. The structure of claim 1 further characterized in that said roll or guide structure comprises a cylindrical body member and end members at the ends of the body member providing said rim portions extending circumferentially around the body member and spaced outwardly from the surface thereof, said structure being adapted to be received in the lower bight portion of a depending web loop in a web-processing apparatus wherein the web is disposed in festooned relation between a plurality of web driving means with depending loops of the festooned web being disposed between adjacent pairs of driving means.

3. The structure of claim 1 further characterized in that said web-correction elements comprise annular elements having circumferentially spaced teeth at their outer peripheries.

4. The structure of claim 1 further characterized in that said body member comprises a section of light-weight sheet material formed into a cylinder, a pair of end closures are provided with means for retaining the same at the opposite ends of the cylinder, said end closures including said rim portions, and said web-correction elements comprise annular elements slidably fitted on said cylinder and having circumferentially spaced teeth at their outer peripheries.

5. The structure of claim 4 further characterized in that the circumferential spacing between adjacent teeth of said annular elements is less than the axial spacing between adjacent annular elements.

6. The structure of claim 4 further characterized in that each of said annular elements has a central opening providing a slidable fit on said body member, and at least one flange member extends axially from the edge of said opening in surfacE contact with said body member.

7. The structure of claim 1 further characterized in that said body member comprises a pair of telescoping portions, and spring means is provided coacting with said end members for urging said telescoping portions together, whereby said end members are automatically held in engagement with the longitudinal edges of the web.