US3650207A

US3650207A - Flat bed web press index and registration

Info

Publication number: US3650207A
Application number: US870720A
Authority: US
Inventors: James A Black
Original assignee: Black James
Current assignee: GENERAL ADVANCE CORP A MI C ORP
Priority date: 1967-02-23
Filing date: 1969-09-24
Publication date: 1972-03-21
Anticipated expiration: 1989-03-21

Abstract

Index and registration means for a continuous web printing apparatus having a web indexing apparatus to create index indicia at predetermined intervals along the web and web index register means at each printing station adapted to cooperate with the index indicia to cause momentary registry of the web with each printing unit for accurate printing. Specifically, the web indexing means punches holes in the web and the web index register means at each printing station includes a shiftable projection reciprocally movable toward the web holes to interengage the holes thereby holding the web in position at each printing station.

Description

United States Patent Black [451 Mar. 21, 1972 541 FLAT BED WEB PRESS INDEX AND 2,369,290 2 1945 Foard ..101/115 REGISTRATION 3,102,472 9/1963 Kieckhefer ..101/228 3,221,646 12/1965 Hardy et a1. ..10l/l15 Inventor: James A- Black, Sparta, Kent 3 Berk ct u 49330 3,355,166 11/1967 Plumb ....226/95 x [22] Fil d; Se t, 24, 1969 3,460,470 8/1969 Green et al. ..10l/115 1 pp 8 0,720 FOREIGN PATENTS OR APPLICATIONS Related US. Application Data 1,258,815 3/1961 France ..101/1 15 [62] gig/$91022? Ser. No. 617,885, Feb. 23, 1967, Pat. No. Primary Examiner clyde I coughenour Attorney-Huizenga & Cooper Price, Heneveld [52] US. Cl ..ll/ll5, 101/228, 226/57,

226/146 [57] ABSTRACT [51] Int. Cl. ..B41f 15/04, B4lf 15/10 I d d registration means for a continuous web printing [58] Field of Search 101/ 1 15, 121, 196, 228; apparatus having a web indexing apparatus to create index 226/56 147 dicia at predetermined intervals along the web and web index register means at each printing station adapted to cooperate 6] References cued with the index indicia to cause momentary registry of the web UNITED STATES PATENTS with each printing unit for accurate printing. Specifically, the web indexing means punches holes 1n the web and the web 1,677,472 7/ 1928 Fuchs 101/152 index register mea s at each printing station includes a shifta- 950,754 3/1910 ble projection reciprocally movable toward the web holes to 1,637,658 8/1927 Rose ..226/57 interengage th hol thereby holding the web in position at 2,017,459 /1935 Howe et a1 101/115 each priming station 2,239,619 4/1941 Murgatroyd et al. 101/115 2,359,825 10/1944 Campbell 101/1 2 Claims, 17 Drawing Figures U |l!'- I Imp/9a 7 l I 1 F. F n '1 1- L 7 w? l PMENPEHMR 21 m2 sum 2 or 8 INVENTOR. Mme! ,4 504.4% BY W PATENTEUMARZI 1972 3,650,207

sum 3 OF 8 INVEN'IOR. wv/W J ,4. mar

BY W

PAIENTEUMAHZI 1972 PAIENIEUMARZI 1972 3, 650,207

sum 5 or 8 PATENTEDMARZI I972 3,650,207

sum 7 OF 8 INVENTOR. 1/4Mf6' 4. 6/466 w g W FLAT BED WEB PRESS INDEX AND REGISTRATION This is a divisional application of parent application Ser. No. 617,885, filed Feb. 23, 1967 now U.S. Pat. No. 3,499,233, and entitled Flat Bed Web Press.

This invention relates to a screen printing apparatus and method, and more particularly to a web press apparatus capable of continuous multicolor silk screen printing on a continuous web.

Silk screen printing is relatively complex and expensive in comparison to other printing methods. Still, it is used extensively because of its capacity to produce very high quality prints, and its capacity to accommodate materials and goods in a manner not possible or practical with other printing techniques and apparatus.

One of the greatest contributory expense factors of silk screen printing results from the present necessity of first printing and then drying each sheet item one at a time. This requires a substantial amount of equipment and labor. Since the ink is usually of substantial thickness, large recirculatory dryers are normally employed to handle the separated sheets. If a sheet is to contain more than one color ink, the process becomes very involved since each sheet must be printed with one color at a time, fully dried in a dryer, and then reprinted and redried for each additional color. Moreover, maintaining proper registry of each sheet with each succeeding ink pattern to be printed is extremely difficult, but must be maintained very accurately if acceptable products are to result. As a practical matter, the expense mounts very considerably with each additional color added. Hence, the product is apt to be very expensive unless the number of colors is limited to one or two.

It is a primary object of this invention therefor to provide a novel screen printing apparatus and method enabling automatic, high quality multicolor screen printing.

Another object of this invention is to provide a screen printing apparatus capable of printing several different selected colors in preselected overlapping patterns on individual portions of web stock, while maintaining completely accurate registry of each individual sheet portion with each color, automatically so that only a fraction of the time, expense, and equipment is required compared to that normally required.

Another object of this invention is to provide a novel screen printing apparatus capable of printing on a continuous web of stock.

Another object of this invention is to provide screen printing apparatus capable of accurately printing several colors in preselected patterns on a continuous web of stock, and to do so in a fraction of the time and at a fraction of the expense of known multicolor screen printing equipment and techniques.

Another object of this invention is to provide apparatus capable of successively printing and drying individual colors on a continuous web of stock on a rapid continuous basis, with the number of different colors being practically unlimited. The number and selection of different colors can be varied widely merely by using or passing successive modules of combination printing and drying units.

Another object of this invention is to provide a novel mulitcolor continuous web screen printing apparatus having several print stations operating simultaneously on the web, and having exactly controlled, automatically regulated registry of each segment of the continuous web with each successive print station.

Another object of this invention is to provide a novel screen printing apparatus having a plurality of printer units, wherein each printer unit has complete registry control of the particular web portion being printed by it.

Another object of this invention is to provide a novel continuous web screen printing apparatus wherein each printer unit controls the feed rate of the web stock portion through and from the dryer unit immediately upstream of the printer unit, so that a series of the printer units can be in operation simultaneously.

Another object of this invention is to provide a continuous web screen printing apparatus having dryer units capable of rapid drying and controlled positioning of a continuous web in the dryer, using dynamically flowing drying air, while enabling the printing unit immediately downstream thereof to intermittently draw web portions therefrom without creating significant tension on the web.

Another object of this invention is to provide a novel screen printing unit particularly suited to handle continuous web stock in an accurately controlled reliable fashion, to print selected colors in repeat patterns on successive portions of the web, using a unique reciprocable bed that simultaneously accurately registers and advances stock, and also supports and retains the stock in registry during printing.

Another object of this invention is to provide a printing unit capable of repeat automatic operation on stock fed to it, and allowing substitution of squeegee elements in the printer unit without interrupting the continuous flow of stock through the printer. The printer squeegee assembly is capable of being switched from one squeegee to another in a fraction of a second, between pring strokes, so that continuous web printing will not be interrupted or otherwise adversely affected. Moreover, the squeegee element in the squeegee assembly can be easily replaced without stopping the printer.

Another object of this invention is to provide a novel screen printer squeegee assembly enabling change from one squeegee to another, merely by rotating the assembly to disengage the one squeegee and operably engage the other.

Another object of this invention is to provide a novel squeegee assembly drive apparatus for a screen printing unit, enabling the squeegee to make a print stroke transverse to a continuous web and then to allow the web to advance the printed area through the station without being adversely affected by the squeegee assembly.

Another object of this invention is to provide a novel, continuous feed, printed web dryer, employing dynamic air flow to cause rapid continuous drying of the web and controlled positioning of the web as it is advanced through the dryer.

Another object of this invention is to provide a novel continuous web dryer enabling the web to pass through a curvilinear non-wrinkling path, with its position being constantly controlled by the dynamic drying air itself. Moreover, the web positioning drying air has optimum sweep across the printed surface for reliable rapid drying.

Another object of this invention is to provide a novel continuous web dryer enabling the web to be intermittently advanced therefrom and intermittently fed thereto by dynamic air flow caused by controlled pressure differential, without significant stress being applied to the web.

These and other objects of this invention will become apparent upon studying the following specification in conjunction with the drawings in which:

FIG. 1 is a side elevational view of the novel apparatus;

FIG. 2 is a plan view of the apparatus in FIG. 1;

FIG. 3 is a fragmentary perspective view of the registry punching station of the apparatus;

FIG. 4 is an enlarged elevational view of one of the printers in FIGS. 1 and 2, taken on the plane IV-IV of FIG. 1;

FIG. 5 is a fragmentary elevational view of the apparatus in FIG. 4, viewed from the opposite side, i.e., taken on plane V- V of FIG. 1;

FIG. 6 is a fragmentary enlarged perspective view of the top portion of the apparatus in FIGS. 4 and 5;

FIG. 7 is an enlarged plan view of the apparatus in FIGS. 4 through 6;

FIG. 8 is a partial elevational view of the apparatus in FIG. 7, taken on plane VIIIVIII;

FIG. 9 is a fragmentary enlarged elevational, partially sectionally view of the printing station in FIGS. 7 and 8, taken on plane IX-IX in FIG. 7;

FIG. 10 is an enlarged fragmentary exploded view of an end portion of the novel squeegee apparatus in a printing station;

FIG. 11 is an elevational, partially sectional view of the apparatus in FIG. 10, as assembled;

FIG. 12 is an enlarged end elevational view of the squeegee apparatus in FIGS. 10 and l l, for the printing station;

FIG. 13 is a fragmentary plan view of the apparatus in FIG. 12;

FIG. 14 is a perspective view of one of the drying units in the equipment of FIGS. 1 and 2, shown with the front door open;

FIG. 15 is an end elevational view of the dryer unit in FIG. 14;

FIG. 16 is a front elevational view of the dryer unit in FIGS. 14 and 15; and

FIG. 17 is a prospective view of a latch for locking the squeege assembly in aligned position.

Referring to the drawings, the complete system 10 is composed of a series of cooperative components including a web supply roll stock support means 12, web splicer means 14, slack container means 16, web predryer means 18, web registry index punch means 20, a first printer and dryer combination including printing means 22 and dryer means 24, a second printer and dryer combination including printer means 26 and dryer means 28, and optional units including slip coat applicator 30, laminator means 32, cross slitting means 34, longitudinal slitter means 36, underscoring means 38, and cut off means 40.

As will be understood from the detailed description to follow, not only is the complete system unique, but also the web registry system, the individual printing units, the squeegee assemblies on the printing units, and the dryer assemblies. Two printer and dryer combinations are shown in the illustrative drawings. Actually, the number of printer and dryer combinations may be widely varied to suit a particular installation. Thus, instead of the two shown, a large number of four, eight, l0, more or less, can be employed merely by installing additional combinations in the sequence, or only one need be used. The number employed will depend upon the number of color variations to be obtained. In operation, the web actually is advanced from support means 12, past splicer 14 which is intended to splice the end of one roll with the beginning of another, through temporary slack container 16, and through predryer 18 where initial excess moisture is removed. It then passes through registry index punch means which punches registry holes at a controlled spacing along the web. Then, the web begins its passage through the selected number of printer and dryer combination series to apply the selected patterns in order to obtain the multicolor print stock. The printer units actually determine the rate of feed through this sequence. After printing, and the final drying step, the web may pass through the

optional assemblies

30, 32, 34, 36, 38 and 40. The slip coat applicator 30 can apply a protective coating, if desired, and/or laminator means 32 can apply a protective cover sheet. The web can be cross slit with means 34 and/or can be longitudinally slit with slit means 36 and/or can be underscored with means 38. It may then be cut into individual sheets by reciprocating vertical cut off 40, or may be rolled up in a roll, as desired.

It is believed that the entire system can be more readily understood after a detailed description of each of the components thereof. Hence, for convenience and clarity, the components will be described in their sequential relationship.

WEB SUPPORT The web supply roll support means 12 basically includes a pair of elongated support beams 50 and 52 (FIGS. 1 and 2), arranged parallel to each other on a central transverse pivot shaft 54 mounted to support housing 56. Rotationally mounted between the opposite ends of beams 50 and 52 is a first roll 60 of web stock, removably mounted on a central shaft, and a second roll 62 of web stock removably mounted on another central shaft. The forward roll 60 supplies web stock until it is depleted, at which time the mechanism is rotated 180, end for end, to bring roll 62 from its inactive position as a spare to the active position for supplying web stock. This rotational action is obtained by rotating shaft 54 with a motor 66 through chain 68 and sprocket 70, the latter being mounted on shaft 54. Thus, the system can be constantly supplied with web stock W even though the individual rolls are depleted. It will be realized that when the exhausted roll is shifted to the spare position, a new roll can be substituted therefor while the system is still operating.

The web is positively advanced from the roll to predryer 18 in accordance with demands of the system. Specifically, an advancing means such as a pair of orificed, pulleymounted recirculating tapes 61 and 63 (FIGS. 1 and 2) are advanced over the slotted upper surface of an evacuated table 65 to pull web W from the roll and advance it to slack control container 16. The motor (not shown) driving tapes 61 and 63 is shut off and on in response to a limit switch 67 in container 16 so that a controlled amount of slack is maintained in the web ahead of predryer 18.

SPLICER Immediately downstream of the web support means is splicer 14 used to splice the tail end of one web with the new forward end of another web from the next roll, in order to provide a continuous web to the system. The splicer may include suitable temporary holding means such as a vacuum head 74 to hold and align the two ends of web as they are spliced together by adhesion, taping, or the like. Normally, this splicer is disengaged from the web stock, so that the web can constantly move past it without interference from it.

PREDRYER Dryer assembly 18 is exactly like

dryer assemblies

24 and 28 which are employed in combination with printer units 22 and 26. Its function is to remove any excess moisture which the web stock, usually paper, has taken on during storage and shipping. Its use is not always necessary, but is advisable in most instances to bring the moisture within a central range.

The dryer assembly 18, and hence

dryer assembly

24 and 28,

has a construction illustrated most clearly in FIGS. 14 through 16. It has a cabinet housing which forms a specially configurated front chamber and an enclosed rear chamber 82 that communicates with an evacuating means (not shown) through a passage outlet 84. The vacuum source may be a typical exhaust fan, with the amount of vacuum pull being variably by varying out flow with an adjustable damper 84' in passage outlet 84. The front chamber is separated from the rear by a vertical partition 86. This front chamber has an open top and a curvilinear peripheral wall 88 which defines a smooth curvilinear web path from its horizontal entry plane, through a convex shoulder, thence through a continuous concave bottom to reverse its direction from down to up, hence around another convex shoulder to the horizontal exit plane. This curvature includes no sharp bends so that the web can be drawn through the generally bottle-shaped chamber in a smooth fashion by the printer unit downstream of the dryer. The web is held against this periphery by air flow and by a pressure differential created across the web between the inner face of the web and the outer face adjacent the perforate surface 88. The web stock thus enters in the direction indicated by the arrow in FIG. 14, and exits also as indicated by the arrow. The dryer employs dynamic air flow for both web drying and web positioning. Heat is supplied to the moving air in the front chamber by suitable forwardly projecting electrical heating elements such as Calrod units 94. A plurality (four) of protector rods 96 project forwardly at intervals around thesev heater elements, spaced inwardly from the peripheral curvilinear guide wall to prevent the web from ever being brought into contact with he heater elements should the web be accidentally drawn too tightly in the dryer.

The front chamber is normally closed by a hinged access door 98 which swings between its open position shown in FIG. 14 to its closed position shown in FIG. 15. The door is maintained in its closed relationship by a plurality of magnetic catches 99. This door preferably includes a glass window 100 for observation of the interior of the unit. On the inside face of the door is a protruding sealing gasket 102 which extends around the entire periphery of the chamber. Gaskets also extend around a pair of air inlets 105 and 106 in the door, which communicate with a cooperative set of

air flow passages

108 and 110 respectively that extend to rear chamber 82. Dynamic air flow through the front chamber is caused by pulling a vacuum on the front chamber via the rear chamber and allowing air to flow in the open top of the chamber. MOre specifically, communication is achieved by a large number of small air flow orifices 114 in partition 86, located in a pattern around the inner chamber, immediately adjacent the perforate curvilinear surface 88, and, opposite these orifices, in the same pattern, another series of orifices 116 in the front panel of hollow door 98 to provide communication between this curvilinear chamber and the interior of door 98. These orifices 116 are also immediately adjacent the curvilinear surface 88 when the door is closed. Negative air pressure is provided to the interior of door 98 by communication of orifices 104 and 106 from the door interior to

passageways

108 and 110, and thus with rear chamber 82 that associates with vacuum outlet 84. When vacuum is pulled on rear chamber 82, air flows continuously down through the open top of the front chamber and through the orifices 114 and 116, to the rear chamber 82 of the cabinet.

This continuous air flow into the front chamber is further directed by an inverted V-shaped air deflector guide 90 that causes the air to diverge after it passes through the narrow necked down portion where the web enters and leaves, along the inner surface of the web. Thus, the air has optimum flow across the surface of the web and out through passageways 114 on the lateral edges of the web. By causing this air flow to occur constantly along the length and across the width of the web as the web passes through the dryer, an excellent rapid, easily controlled drying action occurs while the web is being advanced by the printing unit downstream thereof. Further, the pressure differential across the web, between the incoming atmospheric pressure air and the negative pressure pulled on the orifices and on the back of perforate surface 88 maintains the web adjacent the curvilinear surface.

REGISTRY INDEX PUNCH For proper operation of the system, very accurate registry must be obtained between each segment of the web to be printed and each successive printing unit. After considerable experimentation, the best and most dependable technique devised was found to-include the control of the web with pins (at each printing station) that project into prepunched holes in the web at spaced intervals therealong. The holes are punched by the unit (FIGS. 1,2 and 3).

This punch means includes a die holder and guide surface 130 over which web W passes and on which it temporarily stops at intervals between intermittent web advancement by the first printing unit 20. The holes are actually punched by a plurality of (three) punch elements 132 mounted by supports 134 to a vertically reciprocating platen 136 which is guided by column 138. Platen 136 is depressed by pivotal lever 140 which is also connected to reciprocating link 142. Suitable power means (not shown) operates link 142. After the platen is depressed to lower punch elements 132 through orificed guide plate 144, the platen is then biased upwardly by a spring 146 beneath post 148 which is attached to plated 136. The holes are punched in the web after the web is drawn taut by the next printing unit 22 downstream thereof, so that the holes have a definite space relationship to the previously punched series of holes that are at the first printing unit. Each printing unit holds the web tight by vacuum and a set of registry pins projecting into the previously punched holes of the previously advanced section of the web as explained hereinafter. Thus, the spacing between the punched holes is exact and controlled.

PRINTER AND DRYER COMBINATION As explained previously, the complete system includes any selected number of printer and dryer combinations, with the illustrative apparatus showing two such combinations. Also, as noted above, each of the dryer units of the printer and dryer combinations basically has a construction like that described with respect to predryer 18. The printer units are also basically the same, except that each, in operation, normally includes a different removable silk screen pattern, preselected to apply the particular color of ink at the printing station in a predetermined pattern to the multicolor printed web. Hence, printer unit 22 will be described, with it being understood that unit 26 is basically the same.

The detailed construction of the printer assembly is best illustrated in FIGS. 5 through 13. Printer assembly 22 includes a web alignment and feed station 22a and cooperative printer station 22b (FIGS. 1, 7 and 8). The chief components at the printing station include a web advancing and supporting vacuum bed platen that reciprocates between

stations

22a and 22b, and the printing apparatus that includes a silk screen stencil frame 172 above the platen, and a transversely reciprocating squeegee supporting carriage 174.

The vacuum bed platen 170 is slidably mounted on a fixed cylindrical guide shaft 178 (FIGS. 4 and 7) extending in the longitudinal direction of the web along the length of the back of the two stations. A slide bearing 180 encircles this rod and is fixedly attached along the rear of platen 170. The front edge portion of bed 170 has an attached follower roller 184 that rides on track 182 (FIG. 4). This track is affixed to frame member 184 along the front of the printing unit, parallel to shaft 178. The platen reciprocates from an initial position at station 22a as shown by the dotted lines on the left hand side of FIG. 8 where registry is made with the web stock, to a second position at station 22b beneath the squeegee assembly at the right hand side of the structure in FIGS. 7 and 8, where the printing actually takes place. When the platen is in station 22a, registry is made with the web with vertically reciprocable index pins that move with the platen, specifically by raising register pins up through the end of the platen to fit into the three index holes previously punched by means 20. These pins are tapered to assure initial insertion into the holes, and have a diameter at the base of the pins equal to that of the holes, to assure exact registry. The pins are shifted upwardly by the special mechanism shown must clearly in FIG. 9. That is, the lower ends of pins 190 are mounted on a plurality of cantilever arms 194 (FIGS. 7 and 8) which in turn are mounted on the opposite ends thereof to transverse pivot shaft 196. The arms and pivot shaft are shifted to provide a vertical movement to pins 190 by vertical shifting of a depending leg 198 affixed to the front most one of cantilever arms 194. At the lower end of leg 198 is a cam follower 200 fitting within a pivotal cam track 202. This cam track in turn is mounted on a longitudinal pivot shaft 204, to which is also affixed depending leg 206. A link 108 is pivotally connected to leg 206, and is operably connected to the drive means so that, when it shifts longitudinally in the direction indicated by the arrows in FIG. 9, it pivots the cam track 202, to vertically shift cam follower 200, leg 198, and thus elevate the alignment index pins. Link 208 is shifted by pivot lever 209 operated by a cam (not shown) on camshaft 356.

The mounting of the pins on pivotal cantilever arms causes them to move in a large radius arc toward the printing station, so that the inserted pins first draw the web tight, at which time punch 20 reciprocates to form the next set of index holes.

Immediately downstream and adjacent to the printing station 22b, and thus to platen 170 when under the printer, is a fixed vacuum bed 169 (FIG. 6). It is hollow, is connected to a vacuum source, and has orifices 167 to its upper surface. It is actuated after platen 170 reaches the printing station, to help hold web W, and remains activated after the vacuum on platen 170 is released to allow the platen to be returned to the alignment station 22a, to hold web W from reversing with the platen.

A pair of web support cables 165 (FIG. 6), attached to bed 169, support web W from projecting between held 169 and platen 170 when the latter is spaced from the former. Cables 165 extend through passages in platen 170.

In the operation of this apparatus, the pins are elevated after the platen has reached the alignment station 22a, and are gradually retracted as the platen moves toward the printing station, by shifting the cam track downwardly. I-Iollow platen 170 is evacuated through a suitable flexible hose connection (not shown) made to its underside, to hold a segment of web. The web is thus initially advanced by both the pin and hole connection and the platen pressure differential. The platen evacuation causes a pressure differential across the web portion due to a plurality of patterned vacuum orifices 210 (FIG. 6) which extend between the hollow interior of platen 170 and its upper surface. Once the web is in motion, the pins retract and the pressure differential continues to advance it to the printing station. When the platen reaches printing station 2212, so that it has carried a particular portion of the web into accurate registry therewith, the drive mechanism for the squeegee apparatus goes into operation.

The advancement of platen 170 occurs simultaneously with advancement of the other printing unit employed by attaching sleeve 180 (FIG. 4) to a reciprocating drive bar 181 with a clam 183. Bar 181 extends along the length of the system and is reciprocated by a master rotationally powered cam 187 (FIG. 1).

Referring now to the squeegee assembly (FIGS. 4 and 6), it includes a general support member 230 on the opposite ends of which are mounted a pair of slide guides 232 which receive the squeegees in a manner to be described hereinafter, and which are specially pivotally mounted to a pair of carriage plates 234. To these carriage plates are mounted a plurality of rollers 240 on the forward ends of the carriages, and 240 on the rearward ends. Attached to rollers 240 on opposite sides of the assembly is a first link 242, and connected thereto is a second link 244 extending down to a fixed connection on pivot shaft 246 (FIG. 5). Also connected fixedly to shaft 246 is a cantilever arm 248 which is pivotally secured to a tie rod 250 that has its lower end pivotally connected to a crank 252 mounted on drive shaft 254. This drive shaft is driven by a belt and pulley connection 256 from motor 258. Thus, rotation of the drive assembly causes crank rotation, to reciprocate tie rod 250, pivot lever 248, and hence reciprocate the squeegee assembly along a pair of cantilevered guide track units 270 transverse to the general orientation of the web. In FIG. 6, the device is shown with squeegee elements themselves removed so that the other members of the assembly can be more readily illustrated. Also, in FIG. 6 the stencil frame member 172 is removed. The printing stroke occurs during the movement of the squeegee assembly from the back initial position illustrated in FIG. 6, through the printing step shown in FIG. 5, to the extended position. On its return stroke, the squeegee assembly is elevated above the sheet so it will not make contact with the stencil screen. During the elevated return stroke however, a flow coater blade 300 having a width equal to the width of the squeegee (FIG. 12) is allowed to drop to flood coat the excess ink back across stencil screen 302 inside the stencil screen frame. The detailed structure and operation of this flow coater and squeegee mechanism will be described hereinafter.

The vertical shifting of the squeegee assembly is obtained by actually shifting its track assembly 270. More specifically, referring to FIGS. 4 and 5, attached securely to the track assembly is a pair of vertically depending supports 310 which are guided in their travel by cam followers 312 and 314 and are partially biased to an upward position by tension spring 316. The weight of the squeegee assembly end tracks causes this structure to normally remain in a lowered position, however, until elevated by upward shifting of pivot lever 318 engaging a follower 320 on the lower end of supports 310. Lever 318 is pivotally mounted to a shaft 322 on its opposite end, and pivotally connected to a lift member 330, which is slidably mounted in guide 332, and includes a cam follower pin 334 on the upper end thereof. A rotational cam 336 mounted on rotational shaft 254 engages this follower to lift the entire mechanism on a controlled basis. This is arranged such that the squeegee assembly is lowered only during the forward printing pass, and is elevated on the return stroke. The timing of this raising and lowering function is synchronized with the passage of the squeegee assembly since both are driven from the same shaft 254.

It has also been found advisable to elevate the stencil screen by elevating its frame 172 temporarily after the printing stroke, while the web is being advanced through the printing station. This is done by pushing the front of the stencil screen frame 172 up with a vertically shiftable pin 342, to pivot it about its rear edge. This lifts the frame front ends up on its alignment pin 340. Push pin 342 is connected to a bell crank 344 which is in turn pivotally operated by a link 346 connected to a pivot link 350. This link 350 is pivotally mounted to support 352 and shifted by a rotational cam 354 on a timing cam shaft 356. This same camshaft also controls the vacuum connection to movable platen and to fixed holding platen 169 through cam operated valves (not shown).

The actual squeegee assembly has a special construction to allow rapid fiipover change between one squeegee and another while the unit is in operation. This is important to this equipment since any shut down of the continuous process is detrimental to the entire operation. The device has a spare squeegee unit which extends upwardly and a functioning squeegee that extends downwardly. The spare squeegee can be rotated to the downwardly oriented operative position between squeegee strokes. Referring to FIGS. 10 and 11, each of the squeegees includes a flexible squeegee element and a support means therefor. That is, the operating squeegee includes a holder 320 and a flexible element 322 to pass along the surface of the screen. Likewise, the spare squeegee unit includes a holder 320 and a flexible element 322'. Both are mounted on a common support 328, which is mounted to a carriage. Each has alignment stud members, 324 and 324' respectively, which extend into passages 326 in fixed support member 328. All of these members slidably interfit in slide tracks 330 in spaced members 232. A pair pair of shoulder screws 340 extending into both ends of unit 328 through

respective orifices

321 and 323 in plates 234 and element 232 to form pivot pins to enable element 328 and thus elements 232 to be rotated thereon. Control of this rotation is had by a pair of J-shaped

detent members

350 and 350. These detent members also serve a secondary function of locking the lower squeegee means in its operative position to prevent it from falling out of the assembly and to release the spare, upper squeegee means for replacement thereof. These detents project through

slots

325 and 325 in members 232. Each of these generally J-shaped hook members has an elongated leg which projects into corresponding passages 352' and 352 in support 328, with compression springs 354 and 354 in these passages biasing the detents to an outward extended position. A recess 356 is formed in the inside face of member 234 and aligned with the J-shaped member which is associated with the upper squeegee unit to align the entire rotational mechanism into its intended operative vertical orientation. The detents also have short legs which can project into recesses 360 and 360' in squeegee holders 320 and 320'. Projection of detent into recess 356 retracts its short leg from holder 320', to release the upper squeegee element, enabling it to be removed and replaced. The combination detent hook element 350 for the lower squeegee assembly is held inwardly by the inside face of element 234 against its compression spring to a position where its second leg is inserted into recess 360, to hold the lower squeegee in a locked position preventing it from falling out. An L-shaped latch 355 (FIG. 17) is pivotally mounted in its center to member 234 and biased toward element 232 by a tension spring 357 between latch 355 and track 270 to lock the rotational squeegee assembly in aligned position. In order to shift squeegee 320 from its lowered position to an elevated position for replacement therefor, it is only necessary to release latch 355, grasp the upper squeegee and forcibly rotate it, causing the rounded outer end of hook 350 to slide on the tapered surface of recess 356, and thereby to retract it from recess 356 against its compression spring, so that the device can be rotated 180 in a fraction of a second. By so doing, the lower J-shaped member 350 snaps into the recess to automatically align the other lower squeegee in operative position, while enabling the upper squeegee to be removed and replaced, and the latch snaps back to lock position. Thus, there is no need to halt the entire web printing and drying process in order to replace Squeegees, since the unit can be quickly revolved between print strokes.

As mentioned previously, a flow coater assembly is also employed as at 300 in FIG. 12. This transverse flow coater blade is mounted to a support 400 which is free to float vertically in its slots 401 (FIGS. 6 and 13), to ride under the bias of its own weight across the print screen 302. It can be elevated by a T- shaped lifting link 404 which is pivotally mounted at 406, and projects beneath an extending shoulder 400 of support 400. This link 404 can be shifted between stops 408 and 410 (FIG. 12) by a

linkage

414, 416.

SUPPLEMENTAL EQUIPMENT The slip coat applicator 30, laminator 32, cross slitter means 34, longitudinal slitter means 36, underside scoring means 38, and cut off means 40, may optionally be used.

The slip coater 30 is intended to apply a protective coating over the surface of the dry printed ink.

The laminator means 32 includes a main lamination roll support 500 (FIG. 1) mounting a roll of an adhesively backed laminator material, normally transparent, which is also covered with a removable protective sheet. Unwinding of the laminator roll stock is controlled by a suitable brake 502. The laminating material 504 is applied to the printed surface of web W by pressure roll means 506, while the removable protective sheet 507 is wound up on a roll support 508.

The cross slitter 34 is a transversely reciprocating mechanism with slitting devices 512 mounted thereon to slit the cover sheet or the cover sheet and web at spaced intervals.

The longitudinal slitting means 36 includes a plurality of transversely positioning slitting elements 520 for cutting the laminator sheet 504 at spaced intervals.

The underside scoring means 38 includes a plurality of slitters 522 for scoring the printed web.

If desired the printed stock can be rolled up at the end of the operation. Alternatively, it can be slit into separate printed sheets by cut off means 40 such as a vertically reciprocating blade unit.

OPERATION Basically, the operation of the system and each of its cooperative components can be understood from the previous description given. In normal operation the web W extends the length of the system. Web W is pulled off the active roll 60 on roll support 12 by advancing vacuum tapes 63 and 65 until the slack web in chamber 16 shifts limit switch 67 to shut off the advancing tapes. The web extends around the curvilinear path of dryer 18, where the air flow is constant, and through punch means 20 to the first printing unit. It is advanced through these components by reciprocating vacuum platen 170 in printer unit 22. That is, with platen 170 in station 22a, index fingers rise on an arc into holes in web W to tighten the web and align it, while platen 170 is evacuated, and punch 20 then forms the next set of index holes. Platen then advances with the web to the print station, as fingers lower to miss the edge of stencil frame 172. With the platen beneath the stencil frame in print station 22b, bed 169 is evacuated to help hold the web. The squeegee assembly is then lowered, and the squeegee is advanced transversely across the stencil screen to print one color in a pattern on the indexed web portion. The assembly then rises and returns to its initial position, pulling the flow coater 300 back across the screen. The vacuum in platen 170 then is released, while that in bed 169 is held, and platen 170 is shifted back to station 22a. The printed web is then progressively pulled to and through dryer 24 by the next printer 26, as printer 22 advances more slack from chamber 16. When the printed web is advanced to the next printer, it is accurately registered therewith by the index pins in this next printer. Then the vacuum bed is advances as with the first printer, so that when the web portion is printed with another color in a selected pattern, exact registry with the first ink pattern, now dried, occurs.

The web continues through the selected number of printers to the final dryer, after which the web is optionally worked on with the

supplemental devices

30, 34, 36, 38 and 40.

In actual practice, the system has worked extremely well, enabling very accurate, high quality, multicolor print patterns to be automatically reproduced hour on end, at a cost which is only a fraction of that normally encountered.

The unique printers are completely reliable and accurate. Replacement squeegees can be readily substituted between print strokes, so as to not require the system to be stopped.

The unique dryers are rapid, safe, reliable, and thorough, always giving complete web control, and completely cooperative with the printers for continuous operation.

It will be realized that the mechanical linkages and controls could be modified in many ways to suit a particular job, within the concepts taught herein. Hence, the invention is intended to be limited only by the scope of the appended claims and the reasonably equivalents thereto.

I claim:

1. A screen printing system capable of repeat printings of multiple color patterns in registry on portions of a continuous web comprising: means to support a continuous web on a flow path; web punching means in said flow path to punch holes in the web for creating index indicia at controlled intervals on the web; a plurality of screen printing units along said flow path, downstream of said web punching means; web advancing means associated with each of said screen printing units, said web advancing means including a web-supporting printing platen shiftable from a first position upstream of said printing unit to a second position aligned with said printing unit, said platen having pressure-differential web-attraction means at is surface to shift the web between said positions; web index register means at each of said screen printing units mounted for movement with said platen, said web index register means including shiftable projection means oriented and reciprocable toward the web holes to interengage the holes; and means to reciprocate said projection means to cause momentary registry of each web portion with each printing unit for accurate printing.

2. The system in claim 1 wherein said web index register means is mounted to said platen to move therewith, and said means to reciprocate said projections is operably associated with said bed in a manner to withdraw said projections from the holes in the web as the web is being advanced by said platen to said second position.