Inking system for a printing roller in a rotogravure printing press and ink fountain operating such system

Abstract

 An inking system for a printing cylinder (C) in a rotogravure printing press, in which inking liquid is introduced in a first collection pre-chamber (11), from which it flows through an opening (21) to an inking compartment (12) below the printing cylinder (C) and part of the liquid flows out of the inking compartment (12) above a sublevel doctor blade (16) whose back (16a) is kept in contact with the printing cylinder (C), said doctor blade having a series of apertures (17) to allow generation and maintenance of a fine ink film between the doctor blade and the printing cylinder (C). The system operating fountain (1) has a smaller wall or frame (5) which is connected to a barrier (15) for defining a pre-chamber (11) and a sublevel doctor blade (16) whose back (16a) is kept in contact with the printing cylinder. The doctor blade (16) has apertures (17) for allowing part of the ink to flow out onto the back of the doctor blade (16) to form a fine film of ink between the doctor blade back (16a) and the printing cylinder (C).

Description

[0001] The preset invention relates to an inking system for a printing roller in a rotogravure printing press and an ink fountain operating such system.

[0002] The invention finds particular application in fountains covered and protected by a film 2 applied to the inner surfaces of the fountain 1, as disclosed in Italian Patent application PR2005A0000040, whose proprietor is the applicant hereof; however, the inventive system is also suitable for use in other inking fountains.

[0003] The object of the present invention is to provide an inking system for inking printing cylinders of rotogravure printing presses which, using a pre-chamber for ink passage, and a sublevel doctor blade against the printing cylinder, as described hereinbelow, optimizes the inking capacity of the rotogravure printing press.

[0004] The advantage associated to the pre-chamber, allowing passage of ink through a compartment of smaller area improves liquid turbulence and distribution in the inking area, thereby improving inking efficiency.

[0005] The advantage associated to the sublevel doctor blade and its holes is to exert an ink dressing action on the printing cylinder to facilitate filling of the cells therein.

[0006] Through certain apertures, such as holes, ink passes into the area above the sublevel doctor blade, to maintain a stable fine film of ink between the doctor blade and the cylinder.

[0007] Furthermore, forced flow through such holes adds turbulence to ink in the upper portion of the doctor blade thereby preventing ink stagnation and, as a result, formation of a "skin" which would be problematic for the printing process.

[0008] A further advantage is a smaller number of parts, this system being integrated in a base fountain component.

[0009] The above objects and advantages are achieved by the inking system for a printing cylinder in a rotogravure printing press and an ink fountain operating such system according to this invention, which is characterized by the annexed claims.

[0010] These and other features will be more apparent from the following description of a few embodiments, which are shown by way of example and without limitation in the accompanying drawings, in which:

• Figure 1 is an exploded view of a first embodiment of an ink fountain having an inking system for a printing cylinder in a rotogravure printing press according to this invention;
• Figure 2 is a perspective view of the ink fountain;
• Figure 3 is a sectional view of an ink fountain as shown in Figure 2;
• Figure 4 is a sectional view like the one of the previous figures, with the printing cylinder of larger size;
• Figure 5 is a sectional view like the one of Figure 2, with the printing cylinder of still larger size.

[0011] Referring to the above figures, numeral 1 designates an inking fountain, generally having the shape of an open box, which is used to collect ink and keep a printing cylinder, designated as C, in wet conditions.

[0012] The invention is particularly suitable for use with ink fountains covered and protected by a film 2 applied on the inner surface of the ink fountain 1.

[0013] The film 2 is held in position by a smaller frame 5, which divides the ink fountain 1 into two compartments, the one for collecting ink (compartment inside the frame 5), the other for overflow ink drainage, which is designated by numeral 13: more particularly, this compartment 13 is outside the frame 5 but confined within the ink fountain 1.

[0014] An ink supply system 10 supplies ink to the compartment inside the frame 5, through the inlet 30.

[0015] The inside of the frame 5 is in turn divided into further compartments 11 and 12 by a barrier 15; the compartment 11 would be substantially a closed and isolated chamber if it were not for the passage created by the opening 21 cleared by the barrier 15 which does not fully separate such areas 11 and 12; the supplied ink flows through such passage: therefore, the area 12 is where the overlying printing cylinder C is actually inked.

[0016] While the barrier 15 is vertically oriented in this embodiment, such orientation is not intended to limit the inventive scope.

[0017] A bar 18 on the frame 5 presses a flexible sublevel doctor blade 16, oriented in the direction of the axis of rotation of the printing cylinder C, whose back 16a is held in contact with the cylinder C; in other words, the doctor blade 16 is substantially shaped like a scraper adapted to be pressed in the direction of the shell of the cylinder C.

[0018] The doctor blade 16 further has a series of apertures, i.e. holes 17 in this embodiment, which allow part of the ink to flow out above it and create and maintain a fine film of ink between the doctor blade and the printing cylinder C.

[0019] The apertures may have any section.

[0020] Such fine film, which is preferably maintained constant by ink filtration through the holes 17, has the function of both ensuring the presence of ink above the doctor blade and preventing any ink stagnation in this surface area, thanks to outflow turbulence.

[0021] As a result, contact between the doctor blade 16 and the shell of the cylinder C is mediated by the desired ink film thickness.

[0022] Several different cylinders C1, C2, C3 may obviously operate with the same inventive ink fountain 1, wherefore position adjustment of the sublevel doctor blade 16 is provided, e.g. through a series of slots formed in the bar 18, in which locking levers 20 operate to allow displacement as a function of the size of the printing cylinder C1, C2, C3.

[0023] By this arrangement, the maximum profile of the doctor blade 16 is always held in contact with the corresponding cylinder.

[0024] Once ink is discharged from the drain manifold 4, it can be pumped back into the supply manifold 10 by a suitable recirculation system, not shown.

[0025] In the illustrated embodiment, the barrier 15 and the doctor blade 16 are located in the partition between the ink collection area, inside the frame 5, and the drainage area 13.

[0026] These positions may be also provided on the opposite wall, if required by the operating conditions.

[0027] The disclosed system including the pre-chamber 11 and the sublevel doctor blade is preferably used with ink fountains having ink collecting films to prevent washing.

[0028] Nevertheless, such arrangement including the barrier 15 and the sublevel doctor blade 16 may be also used with common ink fountains having no ink collection film.

[0029] In this case, a single partition may be effectively provided in the ink fountain 1 instead of the frame 5, for creating the two inking and drainage areas as required above, the partition including in turn the barrier 15 for defining the pre-chamber 11 and the sublevel doctor blade 16 as disclosed above.

[0030] Still with reference to the latter partition solution, since the barrier 15 has to define a chamber 11, the wall will preferably have an inverted L shape or, equivalently, the barrier 15 will have two orthogonal sides adapted to define the upper retention surface of the pre-chamber 11.

[0031] The barrier 15 may be either fixed or removable.

[0032] While reference has been made herein to a single barrier 15, it shall be understood that a modular barrier may be also provided, which is composed of several identical parts, either assembled and continuous or at a certain distance from each other, to allow ink passage both below and at the sides thereof.

[0033] Also, while the barrier 15 preferably extends all along the partition or the frame 5 to form a chamber 11 of the same length, it may also extend only along a limited section of the frame 5 or the partition.

Claims

1. An inking system for a printing roller (C) in a rotogravure printing press characterized in that:

a. inking liquid is introduced in a first collection pre-chamber (11), from which it flows through an opening (21) to an inking compartment (12) below the printing cylinder (C),

b. part of the liquid flows out of the inking compartment (12) above a sublevel doctor blade (16) whose back (16a) is kept in contact with the printing cylinder (C), said doctor blade having a series of apertures (17) to allow generation and maintenance of a fine ink film between the doctor blade and the printing cylinder (C).

2. An inking system as claimed in claim 1, characterized in that the sublevel doctor blade (16) is flexible and position adjustable.

3. An inking system as claimed in claim 1, characterized in that excess ink flows out of the inking zone (12) by overflow to a drainage compartment (13).

4. An inking system as claimed in claim 1, characterized in that liquid is introduced in the pre-chamber (11) through an ink supply unit (10) connected to the inlet (30).

5. An inking and/or ink collection fountain (1) for a printing roller (C) in a rotogravure printing press characterized in that it comprises:

a. a partition for dividing the fountain (1) into two areas, one for inking and the other for drainage (13), said partition having in turn

b. a barrier (15) for further division of the inking area into two compartments (11, 12), with the compartment (11) defining an ink receiving pre-chamber (11); said pre-chamber (11) having an opening (21) for the passage of the inking liquid to the inking compartment (12)

c. a sublevel doctor blade (16) whose back (16a) is kept in contact with the printing cylinder (C), and having a series of apertures (17) to allow part of the ink to flow out above it for generation and maintenance of a fine ink film between the back of the doctor blade and the printing cylinder (C).

6. An inking and/or ink collection fountain (1) for a printing cylinder (C) of a rotogravure printing press, of the type that comprises a smaller frame (5) to divide the fountain into two areas, one for inking and the other for drainage, characterized in that said frame (5) comprises:

a. a barrier (15) for further division of the inking area into two compartments (11, 12), with the compartment (11) defining an ink receiving pre-chamber (11); said pre-chamber (11) having an opening (21) for the passage of the inking liquid to the inking compartment (12);

b. a sublevel doctor blade (16) whose back (16a) is kept in contact with the printing cylinder (C); said doctor blade (16) having a series of apertures (17) to allow part of the ink to flow out above it for generation and maintenance of a fine ink film between the doctor blade back (16a) and the printing cylinder (C) .

7. An inking fountain (1) as claimed in claim 5 or 6, characterized in that the sublevel doctor blade is fixed to the wall or frame (5) above the pre-chamber (11).

8. An inking fountain (1) as claimed in claim 5 or 6, characterized in that the doctor blade (16) is flexible and position adjustable.

9. An inking fountain (1) as claimed in claim 5 or 6, characterized in that the apertures (17) of the doctor blade (16) have any shape whatever.

10. An inking fountain (1) as claimed in claim 5 or 6, characterized in that the barrier (15) that defines the pre-chamber (11) is either fixed or removable.

11. An inking fountain (1) as claimed in claim 5 or 6, characterized in that the barrier (15) extends all along the partition or the frame (5) or along a section thereof.

12. An inking fountain (1) as claimed in claim 5 or 6, characterized in that the barrier (15) is made of one piece or has a modular construction.

13. An inking fountain (1) as claimed in claim 5, characterized in that the barrier (15) has an inverted L shape or, equivalently, the barrier (15) has two orthogonal sides adapted to define the upper retention surface of the pre-chamber (11).

14. An inking fountain (1) as claimed in claim 6, characterized in that the barrier (15) and the doctor blade (16) are located in the partition between the ink collection area inside the frame (5) and the drainage area (13), said positions may be also provided on the opposite wall, if required by the operating conditions.

15. An inking fountain (1) as claimed in claim 5 or 6, characterized in that the modular barrier (15) is composed of several identical parts, either assembled and continuous or at a certain distance from each other, to also allow ink passage at the sides thereof.

Drawing