WO1992004190A1

WO1992004190A1 - A flexographic printing method and apparatus

Info

Publication number: WO1992004190A1
Application number: PCT/DK1991/000256
Authority: WO
Inventors: Hans Bøgeskov ANDRESEN
Original assignee: Nilpeter AS
Current assignee: Nilpeter AS
Priority date: 1990-09-07
Filing date: 1991-09-06
Publication date: 1992-03-19
Anticipated expiration: 1993-03-07
Also published as: AU8512591A

Abstract

In a flexographic printing method and apparatus ink is fed to a printing cylinder (10) by means of an applicator roller (13) of the type having a plurality of small ink receiving depressions formed in its peripheral surface. The printing ink is fed to the applicator roller (13) by means of an ink receiving roller (15), which is in rolling engagement with the applicator roller (13) so as to transfer an ink layer thereto. The ink is fed to the ink receiving roller (15) from a wedge shaped space or nip (56) defined between the peripheral surface of the ink receiving roller (15) and stationary surface (55) engaging with the peripheral surface of the ink receiving roller.

Description

A FLEXOGRAPHIC PRINTING METHOD AND APPARATUS

The present invention relates to a method of feeding prin¬ ting ink to a printing cylinder having a peripheral surface on which a plate or printing form, which corresponds to the matter to be printed, is mounted.

In a known inking system a duct roller or ink cylinder, which is partly immersed in an ink reservoir or an ink fountain, is in rolling and ink transferring engagement with an ink applicator roller having a great plurality of engraved ink receiving pockets formed in its peripheral surface, such as an anilox roller. Excessive printing ink is scraped from the peripheral surface of the ink applica¬ tor roller, which is in ink transferring engagement with the printing cylinder so that . suitable layer of ink is applied to the plate or printing form mounted on the peripheral surface of the printing cylinder. Finally, ink from the plate or printing form is transferred to web of paper or another suitable web material t be printed passing through a nip defined between the printing roller and a counter roller engaging therewith.

In another known inking system ink is supplied to a chamber defined between a pair of oppositely directed ductor blades both cooperating with the peripheral surface of the duct roller or ink applicator roller.

It has been found that none of these known inking systems are suited for operating with more viscous or tixotropic printing inks, such as UV-curing ink.

SE-B-440627 discloses an inking system comprising an ink applicator roller of the type having ink receiving pockets or cells engraved in its peripheral surface. Ink is trans¬ ferred from the ink applicator roller to the printing cylinder via a pair of parallel rollers which are oscillating axially. The ink applicator roller partly defines a trough-shaped ink fountain, the bottom of which is formed by a positive ductor blade cooperating with the peripheral surface of the applicator roller.

This latter known inking system is not suitable for handling viscous ink, because is does not prevent small air bubbles from becoming entrapped in the viscous ink applied to the ink applicator roller.

The present invention provides an improved method, especi¬ ally for use in flexographiσ printing, suitable for hand- ling even rather viscous ink.

Thus, the present invention provides a method of feeding printing ink to a printing cylinder by means of an ink applicator roller of the type having a plurality of small ink receiving depressions or pockets formed in its peripheral surface, for engaging with the peripheral surface of the printing cylinder along a contact zone for applying ink to the peripheral surface of the printing cylinder, said method comprising continuously feeding printing ink to the peripheral surface of the applicator roller and scraping excess ink from the peripheral surface of the applicator roller prior to reaching the contact zone, and the method according to the invention is characterized in that the printing ink is fed to the applicator roller by means of an ink receiving roller being in rolling engagement with the applicator roller so as to transfer an ink layer thereto, and that printing ink is fed to the ink receiving roller from a space defined between the peripheral surface of the rotatable ink receiving roller and a stationary surface engaging with the periphe- ral surface of the ink receiving roller along a substantial part of the axial length thereof, the radial width of said space decreasing in the rotational direction of the ink receiving roller, whereby the ink is smoothened on and pressed into intimate contact with the peripheral surface of the ink receiving roller.

As ink accumulated in the acute angled space defined be¬ tween the stationary surface and the adjacent peripheral roller surface, the stationary surface functions like a spatel forming a smooth layer of ink on the peripheral surface of the ink receiving roller, and this layer is then transferred directly to the depressions or pockets formed in the ink applicator roller without the inclusion of air bubbles therein even when the ink is relatively viscous or tixotropic.

The said stationary surface engaging with the peripheral surface of the ink receiving roller may be defined by a bottom part of a trough-like ink fountain or ink container partly defined by the peripheral surface of the ink recei¬ ving roller.

The stationary surface may be defined by a positive ductor blade biassed into engagement with the peripheral surface of the ink receiving roller, or the stationary surface may be defined by an integral wall part of a container unit or an ink fountain unit being biassed into engagement with the peripheral surface of the ink receiving roller.

The printing ink may be fed to the peripheral surface of the ink receiving roller or into said space corsinuously or intermittently in any suitable manner, manually or auto¬ matically. When the ink is fed automatically, it may be fed to the roller surface in metered amounts by means of one or more ink feeding nozzles. A single nozzle may, for example, define a slot-like discharge opening extending along sub- stantially the total length of the ink receiving roller. Alternatively, and more preferably, the ink may be fed by means of a plurality of spaced nozzles arranged along the length of the roller. The supply of ink to the nozzle or nozzles may be control¬ led in any suitable manner. In one embodiment, sensing means are provided for sensing the amount of ink in the space or a nip defined between the stationary surface and the peripheral surface of the adjacent ink receiving rol¬ ler, and the amount of ink fed to the peripheral surface of the ink receiving roller may then be controlled in response to the amount of ink sensed so that the amount of ink in the said nip may be retained at the desired level. The printing ink may be pumped from an ink reservoir to the nozzle or nozzles through one or more supply conduits which may have one or more branched return conduits for returning ink to the reservoir. In that case, the supply of ink to the nozzles may be controlled by changing the flow resis- tance of the supply conduits and/or the return conduits, for example by adjustably pinching compressible parts of the conduits.

According to a second aspect the present invention also provides an ink feeding unit, which may used for carrying out the method described above, and for feeding ink to a printing cylinder said feeding unit comprising an ink applicator roller of the type having a plurality of small ink receiving depressions or pockets formed in its periphe¬ ral surface, for engaging with the peripheral surface of the printing cylinder along a first contact zone for apply¬ ing ink to the peripheral surface of the printing cylinder, means for continuously feeding printing ink to the periphe¬ ral surface of the applicator roller, and scraping means for scraping excess ink from the peripheral surface of the applicator roller prior to reaching the first contact zone, and the ink feeding unit according to the invention is characterized in that the means for feeding printing ink to the applicator roller comprise an ink receiving roller being in rolling engagement with the applicator roller along a second contact zone so as to transfer an ink layer thereto, and means defining a stationary surface engaging with the peripheral surface of the ink receiving roller along a substantial part of the axial length thereof, the radial width of said space decreasing in the rotational direction of the ink receiving roller.

According to a further aspect the present invention pro¬ vides a printing apparatus comprising a printing cylinder for printing on an ink receiving web material, an ink applicator roller of the type having a plurality of small ink receiving depressions or pockets formed in its peripheral surface, for engaging directly with the peripheral surface of the printing cylinder along a first contact zone for applying ink to the peripheral surface of the printing cylinder, ink feeding means for continuously feeding printing ink to the peripheral surface of the applicator roller, and scraping means engaging with t -i applicator roller downstream of the ink feeding meanε .-.nd upstream of the first contact zone for removing excess ink from the peripheral surface of the applicator roller before reaching the first contact zone, and the apparatus according to the invention is characterized in that the means for feeding printing ink to the applicator roller comprise an ink receiving roller being in rolling engagement with the applicator roller along a second contact zone so as to transfer an ink layer thereto, and means defining a stationary surface engaging with the peripheral surface of the k receiving roller along a substantial part of the axial length thereof, the radial width of said space decreasing in the rotational direction of the ink receiving roller so as to smoothen the ink supplied to the peripheral surface thereof and to press the ink into intimate contact with the ink receiving roller.

As explained above, the amount of printing ink supplied to the ink receiving roller or to the space or nip between the stationary surface and the ink receiving roller may be accurately controlled so that a desired smaller amount of ink is permanently retained in said nip. Therefore, only small amounts of printing ink are wasted when the inking system has to be cleaned, for example because of change of ink colour. As mentioned previously, the present invention renders it possible to use rather viscous printing inks containing only relatively small amounts of solvents. This reduces the splashing tendency and the tendency of the printing ink to change in viscosity during the printing operation because of solvent evaporation. While viscous printing inks may be used in the method and apparatus according to the invention as explained above, conventio¬ nal, less viscous printing inks may be used as well. The small amount of printing ink retained in the nip between the positive ductor blade and the adjacent roller surface because of the accurate metering of the ink supply elimina¬ tes or substantially reduces the foaming tendency of the ink so that the printing speed may be increased. Further¬ more, the small amount of ink exposed to the ambient air reduces the risk of oxidation of the ink.

In the preferred embodiment the stationary surface is defined by an integral wall part of a container unit or ink fountain unit, which is mounted so that the trough-like ink fountain is partly defined by the peripheral surface of the ink receiving roller. The ink fountain unit may further comprise stationary end surfaces which are in tight engage¬ ment with end surfaces of the ink receiving roller, and the stationary surface engaging with the peripheral surface of the ink receiving roller and/or the stationary end surfaces engaging with the end surfaces of the roller may be defined by a flexible or resilient material, such as silicon rub¬ ber or another plastic or rubber material.

The container or ink fountain unit may be mounted such that the stationary surface may be pressed into engagement with the peripheral surface of the ink receiving roller by an adjustable pressure, for example by means of screws or the like. Alternatively, the container or ink fountain unit may be mounted so as to be rotatable about an axis extending substantially parallel with the rotational axis of the ink receiving roller, and biassing means may be provided for biassing the said stationary surface of the ink fountain unit into engagement with the peripheral surface of the ink receiving roller. Such biassing means may, for example, comprise a pneumatic cylinder or a gas spring or any other kind of spring means.

The scraping means for scraping excess ink from the appli¬ cator roller may comprise a negative ductor blade engaging with the ink applicator roller at a position upstream of the first contact zone and downstream of the second contact zone. The scraping means or ductor blade may form part of the ink container or ink fountain unit mentioned above. Su^h unit may be used for modifying a conventional inking system and may be mounted so that the scraping means or negative ductor blade is engaging with the applicator roller or anilox roller of the system wnile the stationary surface or the positive ductor blade is engaging with the ink receiving roller which is in rolling engagement with the applicator roller. Thus, a conventional inking system may be made in agreement with the present invention.

When used in the present specification and claims the terms "upstream" and "downstream" should be interpreted in rela¬ tion to the movement of the printincj ink being transported by the peripheral surfaces of the roller or rollers.

The invention will now be further described with reference to the drawings, wherein

Fig. 1 is a perspective view of an ink feeding unit, Fig. 2 is an end view of an embodiment of the printing apparatus according to the invention including the ink feeding unit shown in Fig. 1,

Fig. 3 is a diagrammatic view illustrating the operation of the apparatus according to the invention, Fig. 4 is an end view and partially sectional view corre¬ sponding to that of Fig 2, but showing a second embodiment, and

Fig. 5 is a perspective and sectional view of an ink foun¬ tain or ink container of the embodiment shown in Fig. 4.

The printing apparatus or printing machine shown in Figs. 2 and 3 is a flexographic printing machine comprising a printing cylinder 10 cooperating with a counter roller 11. A plate or printing form, not shown, may be replaceably mounted on the peripheral surface of the printing cylinder in a conventional manner, and a web material 12 to be printed may be passed through the nip defined between the printing cylinder 10 and the counter roller 11. An ink applicator roller 13 is in direct engagement with the peripheral surface of the printing cylinder 10 along a contact zone 14 so as to transfer printing ink to the plate or printing form mounted on the printing cylinder 10. The ink applicator roller 13 may be of the conventional type having a great plurality of ink receiving pockets engraved in its peripheral surface, such as an anilox roller. Ink is transferred to the applicator roller or anilox roller 13 from a duct roller or ink receiving roller 15 engaging with the applicator roller 13 at 16 so as to define a nip where a small amount of ink 17 may accumulate as shown in Fig. 3. Excessive ink is scraped from the peripheral surface the ink applicator roller 13 by means of a negative ductor blade 18 arranged downstream of the zone of engagement 16 between the rollers 13 and 15.

Printing ink is supplied to the duct roller 15 from an ink reservoir 19. The ink is pumped from the reservoir to one or more nozzles 20 arranged above the duct roller 15 by means of a pump 21, which may, for example, be a peristal- tic pump. The pump 21 is incorporated in an ink supply conduit 22 connecting the ink reservoir 19 with the nozzle or nozzles 20. A return conduit 23, which is branched off from the supply conduit 22 upstream of the pump 21, leads back to the reservoir 19. A compressible portion of the return conduit 23 and possibly also of the supply conduit 22 may be adjustably compressed by means of a pinching or compressing device 24 which may be operated by means of a motor 25 or other driving means under the control of a control device 26 such as an electronic control circuit.

Preferably, a plurality of mutually spaced nozzles 20 are arranged along the length of the duct roller 15 as shown in Fig. 1, and a supply line 22 with a separate pump 21 may then be allocated each of the nozzles 20 or to a group of adjacent nozzles. Thus, in the embodiment shown in Fig. 1, six mutually spaced nozzles 20 are used and ink is supplied through two supply conduits 22 each supplying ink to three of the nozzles. Alternatively, a single nozzle 2C having a slot-like nozzle opening extending substantially along the total length of the roller 15 may be used. A spatel-like smoothening member or a positive ductor blade 27 is biassed into engagement with the peripheral surface of the duct roller 15 at a position 28 downstream of the position 29 at which the printing ink is supplied to the roller 15 from the nozzle or nozzles 20. The smoothening member 27 defines with the adjacent peripheral surface of the duct roller 15 an acute angl d space or nip in which a small amount of ink 30 is accumulated. The level of the accumulated amount of ink 30 is sensed by a sensing device 31 which may, for example, comprise a photo electric cell, a feeler coopera¬ ting with a micro switch, etc. The sensing device 31 is adapted to generate signals indicating the level of the amount of ink 30. Such signals, which are sent through the control device 26, may, for example, indicate when the level of the excessive ink exceeds certain maximum and minimum values. Fig. 1 shows an ink feeding unit which may be mounted on a conventional printing machine as indicated in Fig. 2, whereby such conventional printing machine may be modified in accordance with the present invention. The ink feeding unit comprises a frame 32 with a pair of opposite end wall parts 33 and a side wall part 34. The end wall parts 33 are also interconnected by an upper beam member 35. Flexible sealing pads 36, which may, for example, be made from foamed rubber, are arranged on the inner sides of the opposite end walls 33 so that in the mounted position of the ink feeding unit the sealing pads 36 are in sealing engagement with the upper parts of the opposite end surfa¬ ces of the duct roller 15. The upper edge portion of a spatel-like or flap-like ink smoothening member forming the positive ductor blade 27 is swingably mounted on a shaft 37 extending horizontally between the end wall parts 33, and the smoothening member or positive ductor blade 27 may be spring biassed into engagement with the peripheral surface of the duct roller 15 by means of compression springs 38 mounted around screws or bolts 39 extending through the side wall part 34. It is understood that in the mounted condition of the ink feeding unit as shown in Fig. 2, the peripheral surfaces of the rollers 13 and 15, the positive ductor blade 27 and the sealing pads 36 define in combi- nation an upwardly open tray-like container. The nozzles 20 are mounted on a pair of aligned manifold tubes 40 posi¬ tioned at the bottom side of the upper beam member 35, and an ink supply conduit 22 is connected to each of the mani¬ fold tubes 40. The scraping member or negative ductor blade 18 is adjustably mounted on the upper beam member 35 by means of adjusting screws 41 extending through the upper beam member 35 and engaging with thread bores 42 formed in a ductor blade holder 43. Compression springs 44 arranged around the adjusting screws 41 ^'extend between the opposite surfaces of the beam member 35 and the ductor blade holder 43. The ink feeding system described above operates as follows: When the printing cylinder 10 and the rollers 11, 13 and 15 are rotating as indicated by arrows in Figs. 2 and 3, ink is continuously pumped to the nozzles 20 through the supply conduit 22 by means of the pump 21. Depending on the flow resistances in the supply conduit 22 and the return conduit 23 more or less of the ink pumped by the pump 21 will be returned to the reservoir 19 through the return conduit 23. Because the flow resistance in the return conduit 23 and/or in the supply conduit 22 may be currently changed by opera¬ ting the pinching or compressing device 24, the ink supply may be currently controlled and adapted to the actual need. In the embodiment shown in Fig. 3 the operation of the driving means or motor 25 of the pinching device 24 is controlled by the control device 26 in response to the signals received from the sensing device 31, i.e. in re¬ sponse to the actual level of the amount of ink 30 collec¬ ted between the smoothening member 27 and the adjacent peripheral surface of the duct roller 15. The ink supplied to the duct roller 15 by the nozzles 20 at the position 29 forms longitudinally spaced, peripherally extending bead¹, of ink. Such ink beads are smoothened out by the smoothe¬ ning member 27, which also urges the ink into intimate contact with the peripheral surface of the duct roller 15 without inclusion of air bubbles so as to form a smooth, continuous ink layer with a desired uniform thickness on the peripheral surface of he duct roller 15. Such ink layer is transferred to the peripheral surface of the ink applicator roller 13 at the contact zone 16, and excess ink is scraped from the peripheral surface of the applicator roller 13 by means of the negative ductor blade 18. The ink is then transferred to the web material 12 via the printing cylinder in a conventional manner. Excessive ink scraped from the surface of the applicator roller 13 by the ductor blade 18 falls down unto the surface of the duct roller 15 and is then combined with the ink 30 contained in the nip defined between the duct roller 15 and the smoothening member 27.

Figs. 4 and 5 illustrate an alternative embodiment of the printing apparatus according to the invention which will now be described, and apparatus parts similar to those shown in Figs. 1-3 are designated the same reference nu¬ merals.

The printing apparatus shown in Figs. 4 and 5 comprises a trough-like ink tray or ink fountain 50 having a pair of opposite end walls 51 and a sloping bottom wall part 52. Plate-like sealing linings 53 are fastened to the inner surfaces of the end walls 51. Similarly, a sealing lining 54 defining an outer stationary surface 55 may be secured to the inner surface of the sloping bottom wall part 52. The outer surface 55 of the sealing lining 54 extending along the total length of the ink receiving roller 15, may be plane or cylindrical with generatrices extending paral¬ lel to the rotational axis of the ink receiving roller 15 and with a radius of curvature substantially exceeding the radius of the roller 15 so as to define an acute angled space or nip 56 between the outer peripheral surface of the ink receiving roller 15 and the adjacent surface of the sealing lining 54. The sealing linings 53 as well as the sealing lining 54 may be positioned in recesses formed in the respective wall parts 51 and 52, to which they are secured. The sealing linings may, for example, be made from an elastic or resilient wear resistant material, such as a suitable plastic or rubber material, for example silicon rubber.

The trough-like ink tray 50 is mounted on the apparatus frame so as to be tiltable about an axis of rotation 57 extending parallel with the axis of the ink receiving cylinder 15 and with the outer stationary surface 55 of the lining 54. The ink tray or ink fountain may be rotated to an operating position shown in Fig. 4, in which the outer surface 55 of the sealing strip 54 engages with the peri¬ pheral surface of the roller 15, while the end surfaces of the roller 15 are in sealing engagement with the opposite sealing linings 53. The ink tray 50 may be retained in this position by means of supporting arms 58 and locking means 59 cooperating with a beam member 60 forming part of the apparatus frame.

A gas spring or pneumatic cylinder 61 or any other kind of spring means acting between the beam member 60 and the ink tray 50 at a position spaced from the axis 57, causes the sealing lining 54 to bias into engagement with the adjacent peripheral surface of the ink receiving roller 15 at a predetermined, substantially uniform pressure. However, when the rotational speed of the ink receiving roller 15 is increased, the biass^'ng pressure applied to the ink tray 50 by the pneumatic cylinder 61 is preferably increased corre¬ spondingly. If desired, sr± pressure increase may be obtained by means of a suitable control device controlling the gas pressure of the gas applied to the pneumatic cylin¬ der 61 in response to the rotational speed of the cylinder 15. It should be understood that the cylinder 61 could be replaced by a spindle, a screw or another mechanical device by means of which the pressure between the lining 54 and the roller 15 could be adjusted.

The operation of the apparatus shown in Figs. 4 and 5 is similar to that of the apparatus disclosed in Figs. ^* -3 as described above. Metered amounts of ink may be supp-„ d to the ink tray or ink fountain 50 by means of a feeding system similar to that previously described. However, in the embodiment shown in Figs. 4 and 5 a suitable amount of ink is preferably supplied manually to the ink fountain at suitable time intervals. When the ink receiving roller 15 is rotating in a direction indicated by an arrow, the sealing lining 54 functions similarly to the positive ductor blade 27 described above, so that a uniform and smooth layer of ink is supplied to the peripheral surface of the ink receiving roller 15, and this ink layer is transferred to the depressions or pockets engraved in the applicator roller or anilox roller 13. Possible excessive ink is scraped from the outer surface of the applicator roller 13 by means of the negative ductor blade 18 and returned to the ink fountain 50 in a manner similar to that described above. A pair of end scraper blades 62 engaging with the respective end surfaces of the ink receiving roller 15 may be mounted on the frame of the apparatus, and the position of these scraper blades may be adjusted by means of adjusting screws 63. Printing ink adhering to the end surfaces of the roller 15 and having passed the sealing linings 53 may then be scraped off by means of the scraper blades 62 and returned to a bottom chamber 64 defined in the ink tray 50. In other respects the apparatus illustra¬ ted in Figs. 4 and 5 operates substantially as described above with reference to Figs. 1-3.

EXAMPLE

A conventional F-240 flexo rotational-printing press marke¬ ted by the applicants, Nilpeter A/S, was modified so as to comply with the present invention by means of an ink fee¬ ding unit as that shown in Fig. 1. A web material forming self adhesive labels was printed, and a UV-curing dark blue printing ink marketed by the company G-Mann Danmark, Naver- land 16, DK-2600 Glostrup, was used. This printing ink is highly viscous and extremely tixotropic and is not suitable for use in connection with the conventional printing machi- nes previously described. Anilox rollers with 60 and 80 lines/cm, respectively, were used and the printing machine was operated at web speeds within the range of 20-120 m/min. The supply of ink to the^'nozzles 20 was controlled manually. It was found that the use of this normally rather complicated printing ink did not involve any difficulties. The printing press was operated at its maximum speed, which was not in any way restricted by the ink feeding unit according to the invention. Furthermore, it was found that the undesired ink splashing which is normally encountered at such rotational speeds did not occur. It was possible to apply a relatively thick layer of printing ink to the duct roller 15 so that a print having the character of silk screen printing could be obtained.

The simple inking system of the printing apparatus accor- ding to the present invention may replace the rather com¬ plicated inking system normally used in connection with conventional letter press printing.

Claims

1. A method of feeding ink to a printing cylinder by means of an ink applicator roller of the type having a plurality of small ink receiving depressions formed in its peripheral surface, for engaging with the peripheral surface of the printing cylinder (10) along a contact zone (14) for apply¬ ing ink to the peripheral surface of the printing cylinder (10) , said method comprising continuously feeding ink to the peripheral surface of the applicator roller (13) and scraping excess ink from the peripheral surface of the applicator roller (13) prior to reaching the contact zone (14), c h a r a c t e r i z e d in that the printing ink is fed to the applicator roller (13) by means of an ink receiving roller (15) being in rolling engagement with the applicator roller (13) so as to transfer an ink layer thereto, and in that printing ink is fed to the ink receiving roller (15) from a space (56) defined between the peripheral surface of the rotatable ink receiving roller (15) and a stationary surface (27, 55) engaging with the peripheral surface of the ink receiving roller along a substantial part of the axial length thereof, the radial width of said space de¬ creasing in the rotational direction of the ink receiving roller.

2. A method according to claim 1, wherein the stationary surface is defined by a positive ductor blade (27) biassed into engagement with the peripheral surface of the ink receiving roller (15) .

3. A method according to claim l, wherein the stationary surface (55) is defined by an integral wall part (54) of a container unit (50) being biassed into engagement with the peripheral surface of the ink receiving roller.

4. A method according to any of the claims 1-3, wherein the metered amount of ink is fed into said space (56) by means of one or more ink feeding nozzles (20) .

5. A method according to anv of the claims 1-3, wherein an amount of ink is fed manua. into the space (56) when needed.

6. A method according to any of the claims 1-4, wherein the amount of ink 30) present in said space is sensed, the feeding of ink ceing controlled in response to the amount of ink sensed so an to maintain a desired minimum amount of ink in said space.

7. An ink feeding system for feeding ink to a printing cylinder, said system comprising an ink applicator roller (13) of the type having a plurality of small ink receiving depressions formed in its peripheral surface, for engaging jith the peripheral ε face of the printing cylinder (10) along a first contact zone (14) for applying ink to the peripheral surface of the printing cylinder, means for continuously feeding printing ink to the peripheral surface of the applicator roller (13), and scraping means (18) for scraping excess ink from the peri¬ pheral surface of the applicator roller (13) prior to rea¬ ching the first contact zone (14) , c h a r a c t e r i z e d in that the means for feeding printing ink to the applicator roller (13) comprise an irk. receiving roller (15) being in rolling engagement with t...-.- applicator roller (13) along a second contact zone (16) so as to transfer ink thereto, and means (27, 54) defining a stationary surface engaging with the peripheral surface of the ink receiving roller (15) along a substantial part of the axial length thereof, the radial width of said space (56) decreasing in the rotational direction of the ink receiving roller.

8. A printing apparatus comprising a printing cylinder (10) for printing on an ink recei¬ ving web material (12) , an ink applicator roller (13) of the type having a plurality of small ink receiving depressions formed in its peripheral surface, for engaging directly with the peripheral surface of the printing cylinder (10) along a first contact zone (14) for applying ink to the peripheral surface of the printing cylinder (10) , ink feeding means (19-23, 27; 50, 15) for continuously feeding printing ink to the peripheral surface of the applicator roller (13) , and scraping means (18) engaging with the applicator roller downstream of the ink feeding means (20) and up- stream of the first contact zone (14) for removing excess ink from the peripheral surface of the applicator roller (13) before reaching the first contact zone (14) , c h a r a c t e r i z e d in that the means for feeding printing ink to the applicator roller (13) comprise an ink receiving roller (15) being in rolling engagement with the applicator roller (13) along a second contact zone (16) so as to transfer ink thereto, and means (27, 54) defining a stationary surface (55) engaging with the peripheral surface of the ink receiving roller (15) along a substantial part of the axial length thereof, the radial width of said space (56) decreasing in the rotational direction of the ink receiving roller (15) .

9. A printing apparatus according to claim 8, wherein the means defining a stationary surface comprises a positive ductor blade (27) engaging with the peripheral surface of the ink receiving roller (15) .

10. A printing apparatus according to claim 8, wherein the stationary surface is defined by a wall part (54) of a trough-like ink fountain (50) cooperating with the ink receiving roller (15) .

11. A printing apparatus according to claim 10, wherein the trough-like ink fountain (50) comprises end surfaces (53) for sealingly engaging with corresponding end surfaces of the ink receiving roller (15) .

12. A printing apparatus according to any of the claims 8-

11, wherein the stationary surface and/or the stationary end surfaces is/are defined by a resilient, wear-resistant material.

13. A printing apparatus according to any of the claims 8-

12, further comprising means (38, 39; 61) for biassing the stationary surface (27, 55) into engagement with the ink receiving roller (15) .

14. A printing apparatus according to claim 13, wherein said biassing means comprises resilient means, such as a pneumatic cylinder or a gas spring.

15. A printing apparatus according to any of the claims 8-

14. wherein the scraping means for scraping excess ink from the applicator roller (13) comprise a negative ductor blade

(18) engaging with the ink applicator roller (13) at a position upstream of the first contact zone (14) and down¬ stream of the second contact zone (16) .

16. A printing apparatus according to any of the claims 8- 15, further comprising scraper blades (62) for scraping ink from opposite end surfaces of the ink receiving roller (15) .