CA1108469A - Inking device - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A device for applying ink to a printing surface is described. The device includes a body in the form of an elongate one-piece extrusion defining two spaced limbs ex-tending longitudinally of the extrusion, and a central form-ation intermediate said limbs and defining with said limbs two longitudinally extending slots. The device also includes two ink flow control blades having respective inner portions received in said slots in the body, said limbs of the body clamping the blades against said central formation. The blades project from the body and define an ink chamber with the body and parallel outer edges for contact with a printing surface in use. Sealing means are located at respectively opposite ends of the blades to define ends of said ink chamber. The device also includes inlet means in the body for delivery of ink to said chamber. In use, the device is arranged with the blades in contact with a printing surface and spaced from one another so that ink flows from the ink chamber between the blades and onto the printing surface.

Description

g This invention relates to a device for use in applying ink and the like to a printing surface. For con-venience of description reference is herein confined to the application of ink. However, it is to be understood that the device of the invention may be used for applying other liquids~ for example, lacquers and water.
In many conventional printing technîques, ink is applied to a printing surface from a trough in which a cylinder (or roller) rotates. The printing surface may be the peri-pheral surface of the cylindar itself or the cylinder maytransfer the ink to a remote printing sur~ace ~his method of applying ink from a trough has numerous disadvantages.
`- For example, such cylinders are often necessarily of sub-; stantial length. Since support rollers cannot conveniently ; be provided where an ink trough is used, sagging of the cylinder (known as "cylinder deflection") may be a problem.
Also, where the cylinder is an impression cylinder, an im-pression can be taken only from the top of the cylinder, ; which has the disadvantage that gravity acts against transfer of ink to the paper being printed. Further, only one trough can be used with each cylinder with the result that only one impression can be taken per cylinder.
The present invention has been devised in connec~
tion with rotogravure printing (although the invention is not limited by this). Rotogravure is an intaglio printing technique in which the design to be printed is formed by recessed ink-carrying cells in the curved surface of a printed cylinder. The cells are arranged in the pattern of the design to be printed. Conventionally, the cylinder rotates in a trough of ink which floods the surface of the cylinder.

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A doctor blade positioned above the trough wipes excess ink off the cylinder so tha-t the cells remain filled with ink for subsequent transfer to a web or sheet to be printed.
Co-pending Canadian patent application Serial No. 234,006 filed September 16, 1975, relates to an inking device primarily but not exclusively for use in rotogravure printing.
An object of the present invention is to provide an improved device for applying ink to a printing surface.
.~- lO According to the invention, the device includes a body in the form of an elongate one-piece extrusion de-. fining two spaced limbs extending longitudinally~of the ex-trusion, and a central formation intermediate said limbs and - defining with said limbs two longitudinally extending slots. ~.
The device also includes two ink flow control blades having . - respective inner portions received in said slots in the body, said limbs of the body clamping the blades against said central formation. The blades project from the body and define an ink chamber with the body and parallel outer edges for con-tact with a printing surface in use. Sealing means are located at respectively opposite ends of the blades to define ends oE
said ink chamher. The device also includes inlet means in the body for delivery of ink to said chamber. In use, the device is arranged with the blades in contact with a printing surface and spaced from one another so that ink flows from the ink chamber between the blades and onto the pri.nting sur-face.
The invention will be better understood by refer-ence to the accompanying drawings which illustrate various embodiments of the invention by way of example. In the 3 _ .

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drawin~s:-Fig. 1 is a perspective view from one end of an . .
inking device according -to the invention;
Fig. 2 is a vertical cross-sectional view through the device oE Fig. 1, showing the device in use;
Fig. 3 is an exploded vertical sectional view through the device o~ Figs. 1 and 2 and illustrates a step in the manufacture of the device;
Fig. 4 is a view similar to Fig. 3 showing the device in the fully assembled condition;
Fig. 5 is a view similar to Fig. 4 showing a modi-fied form of device;
Fig. 6 is a plan view, partly in section, of the device of Fig. 4;
Fig. 7 is a transverse cross-sectional view on line VII-VII of Fig. 6; and, Fig. 8 is a sectional view similar to Fig. 16 through the modified device of Eig. 5.
The inking devices shown in the drawings are intended primarily for use in gravure printing and are designed as non-adjustable throw-away units. The devices include ink-flow con-trol blades which arè pre-set and non-adjustable. When the blades of a device become worn or the device ceases to function efficiently, it will be discarded and replaced as a unit. This avoids the problem associated with the doctor blades used in conventional printing installations which require to be sharp-ened periodically and adjusted -to obtain optimum performance.
Figs. 1 to 4, 6 and 7 show the same device. This device has self-closing blades and is intended for use in a situation in which the inking device is required to operate _ ~ _ - intermittently. An example of a printing ins-talla-tion in which intermittent operation is re~uired is shown in Fig. 4 af the drawings of co-pending application Serial No. 234,006.
Intermittent operation may be required, for example, where the device is used in a flat bed printing machine in which the device moves over a printing surface, is raised ~rom the surface, and returned to a starting position clear of the surface. Another example of a situation in which intermit-tent operation is required is where the device is used in associ-ation with an off-set printing cylinder having a gapped printing surface. The device may simply "jump" the gap as the cylinder turns, or it may be lifted clear of the printing surface just before the gap approaches, and returned to the printiny surface after the gap has passed. In any event, it ! iS necessary that the blades of the in~ing device shall close to prevent ink leaking from the device when it is out of con-; tact with the printing surface. The de~ice of Figs. S and 8 is essentially similar excep-t that the blades are not self-closiny. A device of this form is intended for use in a continuous mode in which the blades are always in contact with the printing surface.
Referring first to Figs. 1 to 4, the device as a whole is generally denoted 226 and includes a body 228 and two flexible blades 230 and 232; blade 232 is the leading blade in this case. The blades are made of relatively thin sheet steel, although in alternative embodiments the blades may be made of a suitable plastic ma~erial or combinations or laminations of plastic and steel. Body 228 is in the form of an extrusion. In this embodiment, the extru~ion is aluminum although there is no limitation to -this particular material.

~ 5 --, In other cases, it would even be possible to use plastic materials for the body.
Fig. 2 shows the device of Fig. 1 in use in associ-ation with a printing cyllnder. The device is mounted ad~acent the cylinder with the outer end portions of the blades 230 and 232 in contact with the surface of the cylinder. The blades are normally closed, but open on contact with a printing surface so that ink can flow from the device onto the sur-face. The device is mounted in a support assembly tsee later) so that it can be moved between the "on" position in which it is shown for applying ink to the printing surface, and an -off'l position clear of the surface in which the blades are closed and the supply of ink to the printiny surface is thereby cut off. In any event, it will be appreciated that, in the "on" position in which the device is shown in Fig. 2 r ink is applied to the printing surface between the blades and that blade 230 (the "trailing" blade considered in the direction of cylinder rotation) ac-ts as a doctor blade to wipe surplus ink ~rom the surface of the cylinder.

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; 20 Fig. 3 shows the cross-sectional shape of the ex-truslon used to form the body 228. The extrusion includes a main body portion 234 having a generally V-shaped groove 236 along one longitudinal edge. The opposite longitudinal edge oE body portion 234 is shaped to define a central formation 238 and two side limbs 240 and 242, all of which ex-tend long-itudinally of body portion 234r Limbs 240 and 242 define with formation 238 / two longitudinally extending slots which receive i the blades 230 and 232~ Formation 238 defines a semi-circular 29 section recess 244 having inner limbs 246 and 248 extending - 6 ~

along opposite sides thereof. It will be noted -that limb 248 is of significantly greater length than limb 246.
The outer limbs 240 and 242 of the extrusion are joined to the body portion 234 by narrow "neck" portions 250 and 252 respectively. Respective generally circular-shape passageways 254 and 256 are provided ad~acent these "necks"
and between the respective inner and outer limbs 246, 240 and 248, 242. In the extrusion as manufactured, the limbs 240 and ~42 are outwardly angled as shown in Fig. 3. However, as a result of the narrow "neck" portions 250 and 252, the limbs 240 and 242 can be bent inwardly as indicated by the arrows 258 and 260 to co-operate with the inner limbs 246 and 248 of the central formation 238 and trap the blades 230 and 232 in the body 228 of the inking device.
; In E'ig. 3, the blades 230 and 232 are shown in exploded positions prior to insertion into the body of the device. Thus, the blades are introduced into the slots de-fined by the limbs 240 and 242 and the central formation 238 until the inner edges of the blades contact the walls of the respective passageways 254 and 256. The blades are di-mensioned so that they are correctly positioned when fully inserted. The outer limbs 240 and 242 are then d~flected inwardly in the directions of arrows 258 and 260 so that the blades are clamped between the respective inner limbs 262 and 248 of formation 238 and the outer limbs 240 and 242.
If necessary, cement can be applied to the co-operating faces of the respective limbs and/or to the blades, before the limbs 240 and 242 are deflected. Fig. 4 shows the assembled device.
The blades 230 and 232 are shown in full lines in their normal closed positions and in chain dotted lines in their open posi-:`
tions for applying ink to a printing surface as discussed above.
It will be noted from Fig. 4 that the respective outer limbs 240 and 242 have inwardly angled outer end por-; tions 262 and 264. These portions engage ~he blades 230 and . 232 respectively and cause them to adopt the curved configura-tions shown in full lines, in which the outer longitudinal portions of the blades contact one another and define with the body 228 a sealed ink chamber 266. It will also be noted from Fig. 4 that the outer end portion 262 of limb 240 is longer than the corresponding portion 264 of portion 242; in fact, portion 262 terminates substantially on the median plane MP
of the extrusion. Portion 262 def.ines a pivot for the trailing blade 230 so -that the volume of the ink chamber 266 remains substantially constant when the blades move between their open and closed positions as the device moves between its "on" position and its "off" position as discussed pre-viously in connection with Fig. 2. Thus, the curvature of the.
inner portion of blade 230 between portion 262 and the inner end portion of the blade increases significantly when the device is moved from the "off" position to the "on" position.
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This compensates for the increase in volume of ink chamber 266 which would otherwi.se occur as the outer ends of the blades open due to contact with the printing surface, with the result that the volume of ink chamber 266 remains substantially constant in both the "on" position and the "off" position of the device. This avoids or at least minimizes any increase in pressure in chamber 266 as the device moves between the "on" and "off" positions, which could cause leakage of ink between the blades. Also, the outer edge of the leading blade 232 extends slightly beyond the corresponding edges of the trailing blade 230. This ensures that the outer edges of both blades make contact with a printing surface when the blades are open. The fact khat portion 262 of ]imb 240 is slightly longer than the corresponding portion of the other limbs of the extrusion allows two blades of the same length to be used while maintaining this differential in spacing between the outer edges of the blades.
In the embodiment shown in Fig. 5, primed referenc.e numerals have been used to denote parts which correspond with - 10 parts shown in Figs. 1 to 4. As explained above, the device shown in Fig. 5 differs from the device of the previous figures in that the blades are not self-closing. In the extrusion of Fig. 5, the inner and outer limbs 248' and 242' respect-ively of the body 228' are significantly shorter than the ~ . .
- corresponding limbs of the extrusion shown in Fig. 4, and limb , 242' has no inwardly directed outer end portion. Also, limb 240' is shorter overall and has a shorter outer end portion 262' than the corresponding parts of the extrusion shown in Fig. 4. Accordingly, the blades 230' and 232t in the Fig. 5 embodiment are always open In that view, the blades axe shown in full lines in their inoperative positions and in chain dotted linos in their operative positions in which they are in con-`! tact with the printing surface.
Ink is delivered to and, if necessary, removed fromthe ink chamber 266 by passageways 268 provided in the body 228 of the device and extending from the V-shaped groove 236 to the semi-circular recess 244 of the extrusion (see Fig. 2).
As indicated in that view, the outer ends of these passageways may be internally screw threaded and fitted with unions 270 to which pipes 272 can be coupled. In a typical inking de-_ g `:
vice, two passageways 268 would be provided adjacent opposite ends of the body 228. However, additional passageways could obviously be provided if necessary, for example, where the device is of unusual length.
It will also be noted from Fig. 2 that a groove 274 is provided in one side face of the body 228 of the device.
The primary purpose of groove 274 is to serve as an indication ` as to which way the device is intended to face when fitted to a printing machine. However, the groove may also serve to facilitate location of the device in a support assembly such as that indicated in chain line at 276 in Fig. 2.
In the illustrated embodiment, assembly 276 will be designed to allow movement of the inking device between an "off" posi-tion clear of the printing cylinder and the "on" position in which the device is shown, for applying ink to the cylinder as discussed previously. Assembly 276 may form part of the doctor blade assembly normally provided in a conventional gravure printing machine, from which the doctor blade itself has been removed. However, it is to be understood that the inking devices may be supported in any convenient fashion.
In the simplest case, all that is required is a clamping arrangement for holding the device.
Referring back to Fig. 1, end seals 278 and 280 are provided at opposite ends of the device for sealing off the ink chamber 266. I'hese seals will now he more specific-ally described with reference to Figs. 6 and 7. In Fig. 6, part of the device has been broken away ad~acent end seal 278 to show the seal in section. Part of the trailing blade 230 of the device is visible in the sectioned portion of Fig.
6 as is part of the body 228 formed with an ink passageway 26~. A body 282 of a resilient sealing material is applied to the end face 2~4 of the body 228 of the device. It will be noted that the blades 230 and 232 protrude slightly be~ond face 284 as indicated at 296. The protruding end portions of the blades are embedded in the sealant body 282. The ; sealant body also includes an inwardly extending portion 28 disposed on the exterior sur~aces of the blades 23U and 232.
As a result, the sealant body has a somewhat L-shaped appear-ance when viewed from externally of the device as can be seen more clearly in the case of the seal arrangement 280 in Fig. 6.
Ap~lied to the portion 288 of the sealant bod~ on the exterior surfaces of the blades 230 and 232 is a pad 290 of a low-friction material. In this embodiment, pàd 290 is made of Teflon ~TM) and the sealant is a silicone ' sealant, suitable examples of which are available from Dow Corning and General Electric. The pad 290 and a similar pad 292 at the other end of the device are in contact with the printing surface when the device is in use and ensure that the ink applied by the device is confined between the end seals.
Blade 230 is formed with a short slot 294 at a posi-tion spaced inwardly to a slight extent from its outer edge 286. The slot extends in the transverse direction of the blade; that is, normal to its outer edge 2g6. A similar slot is formed in the other blade 232 but this is not visible in Fig. 6. The Teflon pad 290 is formed with a slot 298 which is in line with the ed~es of the blades 230 and 232 and which extends from the inner end of the pad to a position just beyond the slot 294. The Teflon pad 290 is arranged so tha-t f~

the portions of the blades inwardly of the 510ts 294 protrude through the slot in the pad with their outer edges substan-tially even with the outer surface of the pad. The "corner" `
of blade 230 outwardly of slot 294, denoted 300, and -the cor-responding part of blade 232 are curved to a greater extent than the remainder of the blades and bear agains-t the inner surface of the Teflon pad as can be seen in Fig. 7. The "corner" portion of blade 232 is denoted 302 in that view.
These portions of the blades urge the Teflon pad against the printing surface when the device is in use to maintain a seal between the pad and the printing surface.
:, - The space between the blades 230 and 232 adjacent to the body 282 of sealant is filled with a grease as indi-cated at 304. The purpose of the grease is to minimize the degree of contact between the ink in the device and the seal~
ant. The grease is retained in the area adjacent the sealant by a brush-like body of cotton fibres 306 retained by cement in a small bore 308 in the aluminum body 228. The cotton fibres 306 extend outwardly from the aluminum body generally ` 20 to the inner surface of the Teflon pad 290. In this embodi-ment, the grease 304 is a conventional automotive grease al-though other suitable materials could be used. Also, materials other than cotton fibres 306 could be used to provide a bar-rier for retaining the grease. An example of a suitable material would be a foam plastic.
While only the end seal arrangement 278 has been specifically described, it is to be understood that seal 280 is similar.
Fig. 8 is a view similar to Fig. 7 showing the device of the form described with reference to Fig~ 5 in which the blades of the device are not self-closiny. The end seal arrangement used in this emLodiment is essentially the same as that in the embodiment of Figs. 6 and 7 and primed refer-ence numerals have been used in E'ig. 8 to denote parts cor-responding with the previous views. However, in view of the similarity between the two arrangements, it is believed to be unnecessary to describe Fig. 8 in detail.
It should of course be noted that the preceding description applies to specific embodiments of the invention and that many modiEications are possible within the broad scope of the invention.
For example, although the inking devices have bee~
described in use in connection with rotogravure printing machines, it is to be understood that there is no limitation in this. Thus, the devices could also be used for flat bed printing machines, rotary letterpress type machines converted to gravure printing`and to replace the ink troughs on Flexo graphic machines. Inking devices as described above may also be applied to screen stencil printing. In fact, lt is be-lieved that the device of the invention may be used in anysituation in which ink is to be applied either to a flat sur-face or to an intaglio type of surface in which the ink carrying part of the surface is recessed. Where the surface is flat, it may be necessary to balance ink pressure with the blade pressure to cause ink to be applied to the printing surface. Of course, the inking device need not apply the ink directly to a surface from which an impression is taken.
The ink could be applied to an inking roller from which the ink would be transferred to the impression surface. Accord-ingly, the term "printing surface" as used in this specification .

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and in the claims is to be interpreted as including any sur-face to which ink is applied.
In any arrangement in which the printiny surface has a gap, appropriate means will normally be provided to cause the inking device to "jump" the gap. These means may take a variety of forms. One example of a cam operated mech-anism is shown in Fig. 4 of co-pending application Serial No.

, ., ~ 234,006. In other cases~ pneumatic, hydraulic, electrical `- or other devices may be used.
` 10 Where an inking device according to the invention is used in a situation in which the device is always in con-- tact with the printing surface, the self-closing blade ~eature is not necessary. In this event, the device would not have to be moved out of contact with the printing surface to terminate delivery of ink to the surface. It would merely be necessary to cu-t off the supply of ink to the device.
It is also to be understood that an inking device of the form provided by the invention may be located at any position around a cylinder to which ink is to be applied.
Moreover, more than one inking device may be used in associ-ation with a single cylinder. For example, two or more de-vices each suppIying a different coloured ink could be used.
The devices could be positioned at different angular locations around the cylinder or they could be arranged at different axial positions along the length of the cylinder.
A multiple inking device arrangemen-t may also be used to simultaneously take several impressions from one-cylinder~ For example, two or more webs may be run in contact with a single cylinder wi-th an inking device arranged in ad-vance of the point of con-tact of each web with the cylinder, thereby doubling or more the productivity of the press without increasing the speed.
The above examples are not necessarily exhaustively described since it is believed that the wide range of possible applications of the device will be readily appreciated by a person skilled in the art.
`~ As is customary in conventional gravure doctor blade ;installations, provision may be made to continuously oscillate the inking device in the axial direction o~ the cylinder in association with which it is used. Such oscillation may be derived from a suitable low speed high tor~ue motor coupled with the device through an appropriate mechanical arrangement designed to additionally allow movement of the device towards and away from the associated cylinder as described above.
Further, in some instances, it may be desirable to additionally provide a reverse doctor blade in association with the printing cylinder in advance of the inking device in order to remove from the cylinder "hickeys'l (paper particles) and other foreign material which may be picked up from the web to avoid contaminating the ink applied by the inking device.

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Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A device for applying ink to a printing surface, the device comprising:
a body in the form of an elongate one-piece extru-sion defining two spaced limbs extending longitudinally of the extrusion, and a central formation intermediate said limbs and defining with said limbs two longitudinally extending slots;
two ink flow control blades having respective inner portions received in said slots in the body, said limbs of the body clamping the blades against said central portion, and the blades projecting from the body to define an ink chamber with the body and parallel outer edges for contact with a printing surface in use;
sealing means located at respectively opposite ends of the blades to define ends of said ink chamber; and, inlet means in the body for delivery of ink to said chamber;
whereby, in use, when the device is arranged with the blades in contact with a printing surface and spaced from one another, ink flows from the ink chamber between the blades and onto the printing surface.

2. An inking device as claimed in claim 1, wherein said extrusion inlcudes a main body portion and two relatively narrow longitudinally extending neck portions coupling said two spaced limbs to said body portion, the extrusion being formed with said limbs in outwardly angled positions and said neck portions allowing the limbs to be deflected inwardly to clamp said blades against said central formation.

3. An inking device as claimed in claim 1, wherein said two spaced limbs define outer limbs of the extrusion, and wherein said central formation defines inner limbs extending parallel to said outer limbs and defining therewith said slots receiving the blades, and wherein each of said outer limbs has an inwardly directed outer end portion arranged to contact and inwardly deflect the associated blade, and wherein said inner limbs are dimensioned to co-operate with the respect-ive outer limbs to determine the inward curvature of the blades.

4. An inking device as claimed in claim 3, wherein said blades are normally closed and are resiliently deflect-ible upon contact with a printing surface in use to open and allow ink to flow onto said surface, and wherein one of said blades is a leading blade and the other blade is a trailing blade considered in the direction of relative movement between the device and a printing surface in use, and wherein the outer limb of the extrusion associated with said trailing blade engages the blade at a position intermediate its said inner end portion and its outer edge and defines a pivot arranged to cause the portion of the blade between its said inner end portion and said pivot to curve inwardly as the blades open upon contact with a printing surface so that the volume of the ink chamber remains at least substantially constant.

5. A device as claimed in claim 1, wherein said sealing means comprises, at each end of said extrusion, a body of a resilient sealant adhered to said blades and extrusion and closing the relevant end of the ink chamber, said body of sealant including an inwardly extending portion enclosing an outer end portion of said outer edges of the blades; and a pad of a low friction material adhered to said inwardly directed portion of the sealant body and arranged for contact with a printing surface over which the inking device moves in use, and wherein each of said blades includes an outer edge portion disposed inwardly of said pad of low friction material and arranged to bias said pad into contact with said printing surface in use.

6. An inking device as claimed in claim 5, further comprising barrier means disposed in said ink chamber adjacent each of said sealant bodies for minimizing contact between ink in said chamber and said sealant body, each said barrier means comprising a barrier liquid which is immiscible with ink to be used in the device, and which is disposed in the ink chamber adjacent the sealant body, and retaining means coupled to said body of the device and arranged to retain said barrier liquid in the end portion of the ink chamber.