GB2435238A

GB2435238A - Inking device for a printing machine, in particular a flexographic printing machine

Info

Publication number: GB2435238A
Application number: GB0702483A
Authority: GB
Inventors: Mario Forno
Original assignee: CERUTTI SpA OFF MEC; Officine Meccaniche Giovanni Cerutti SpA
Current assignee: CERUTTI SpA OFF MEC; Officine Meccaniche Giovanni Cerutti SpA
Priority date: 2003-01-02
Filing date: 2007-02-09
Publication date: 2007-08-22
Also published as: GB0702483D0; DE60304024D1; EP1435292A1; ATE320346T1; EP1435292B1

Abstract

An inking device 7 for inking the cylinder 2 of a printing machine, in particular a flexographic printing machine, comprises an inking chamber 8, delimited by delimiting doctor blades 9, 10, and coupled to an ink vessel 14 to which ink is continuously supplied through an ink delivery pipe 15 and therefrom a pipe 12 for continuously supplying ink to the inking chamber extends, a further outlet overflow pipe having an open end 16 leading to the ink vessel, the open end of the outlet pipe being arranged at a level A or B approximately corresponding to the top level of the inking chamber 8.

Description

INKING DEVICE FOR A PRINTING MACHINE, IN PARTICULAR A

FLEXOGRAPHIC PRINTING MACHINE

BACKGROUND OF THE INVENTION

The present invention relates to an inking device for a printing machine, in particular a flexographic printing machine.

As is known, printing machines conventionally comprise a number of inking devices for applying ink on a corresponding roller (for example a screened roller) or cylinder (for example an impression cylinder), therefrom, upon doctoring, said ink is sent to a controlled printing plate cylinder which transfers the ink to a printing band or web.

Modern flexographic printing systems designed, for example, for printing both packaging material and newspapers, comprise a plurality of screened or other rollers and related inking devices, for example, in a four colour printing operation on two sides of a printing web, it is necessary to provide the printing apparatus with eight screened or other cylinders and accordingly eight inking and doctoring devices.

From the prior art is also known to supply with ink the inking chambers of inking devices by pressurizing apparatus, such as electropumps.

Such an ink supplying or feeding system, however, is a very complex construction-wise since, for each individual inking device, it is necessary to provide expensive and complex ink pressure adjusting means for each inking chamber, while arranging, at a proper level, the inking devices in the length and height directions of the printing machine.

SUMMARY OF THE INVENTION

Accordingly, the aim of the present invention is to design a novel inking device for a printing machine, always providing a constant working pressure in each inking chamber and an even ink doctoring on all the screened or other rollers, being devoid of complex pressure controlling and adjusting means and independent from the positions of the printing machine.

The above aim is achieved by an inking device for a screened or other cylinder of a printing machine, in particular a flexographic printing machine, comprising an inking chamber, delimited by delimiting doctors, coupled to an ink vessel to which ink is continuously supplied through an ink delivery pipe, characterized in that a pipe for continuously supplying ink to said inking chamber extends from said ink vessel and that said ink vessel is further coupled to an open end outlet overflow pipe, and that said open end of said outlet pipe is arranged at a level approximately corresponding to a top level of said inking chamber controlling said cylincter.

Thus, each inking chamber is always filled-in with the same level of ink, which has an ink pressure which is constant and identical for all the printing machine printing assemblies, independently from their positions and arrangements.

BRIEF DESCRIPTION OF THE DRAWING

Further characteristics of the invention will become more apparent from the following disclosure, the dependent claims and accompanying drawing which schematically shows an embodiment of a screened or other cylinder to be inked, including an inking device according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in the accompany drawing figure, a printing device or assembly, generally indicated by 1, comprises a conventional screened or other cylinder 2, or an impression cylinder, arranged above a basin 3, into which ink is caused to drip, said ink being conveyed, through a duct 4, to a return pipe 5.

The cylinder 2 cooperates, in a per se known and conventional manner, with a conventional printing plate cylinder 6.

The cylinder 2 can be directionally rotationally driven, as schematically indicated by the arrow f.

To the cylinder 2 is coupled an inking device, generally indicated by the reference number 7.

The inking device 7 comprises an inking chamber 8, delimited, at the two end portions thereof, by dividing walls (not shown), and, on the front of the cylinder 2, by doctor blades 9 and 10.

Inside said chamber is arranged an ink material 11.

The ink 11 is supplied to the chamber 8 through an ink supplying duct or pipe 12, extending from the bottom 13 of an ink vessel 14, to which ink is continuously supplied through an ink delivery pipe 15.

The ink return pipe 5 leads, at an open end portion 16 thereof, to the ink vessel 14 and ends inside said vessel 14 at a set level, indicated by the dashed line 17 and which, as indicated by an auxiliary dashed line 17', coincides with the highest point 18 of the corresponding inking chamber 8.

In this connection it should be apparent that the level 17, 17' of the ink 11 in the vessel 14 can also be arranged by a small amount (in the range of millimeters) at a lower position "B", as schematically shown in the figure by dot and dash lines, or at a higher position "A".

Advantageously, moreover, from the bottom portion of the chamber Ba an ink return pipe 30, for allowing a continuous recirculation and conditioning of the ink, as well as a full emptying of the ink at the end of the printing work, extends.

Since the level 17 inside the vessel 14, owing to the provision of the outlet 16 of the pipe 5 thereat, is always constant (for a given position of the outlet 16) with respect to the bottom 13 of said vessel 14 and since said level 17, 171 has always a value c (variable according to the position of the outlet 16) with respect to the inking chamber 8, the advantage is achieved that the pressure of the ink 8 in said inking chamber 8 will always be held at a constant hydrostatic pressure, independently from the level of the inking S assemblies, including the inking devices 1, 2, 7, 8, 9, 10, 14, 16, 17.

Accordingly, in all the inking devices 7 arranged longitudinally of the printing machine, the ink 8 will always have a constant pressure, thereby the roller 2 will provide an even printing for all the inking devices.

Then, to hold the ink hydrostatic pressure in the inking devices of the printing machine constant, it is not necessary to use ink pumps, and accordingly expensive and complex pump control and adjustment devices can be omitted.

Claims

Claims: 1. An inking device for a cylinder of a printing machine,

preferably a flexographic printing machine, comprising an inking chamber, delimited by upper and lower delimiting doctor blades, coupled to an ink vessel to which ink is continuously supplied through an ink delivery pipe, wherein a pipe for continuously supplying ink to the inking chamber extends from the ink vessel, the ink vessel is further coupled to an outlet overflow pipe having an open end, and the open end of the outlet pipe is arranged at a level approximately corresponding to a top level of the inking chamber supplying the screened cylinder.

2. An inking device according to claim 1, wherein the ink supply and the ink delivery pipe lead to the bottom of the ink vessel.

3. An inking device according to claim 1 or 2, wherein the level of the ink in the ink vessel is slightly higher than that of the upper doctor blade.

4. An inking device according to claim 1 or 2, wherein the level of the ink in the ink vessel is slightly lower than that of the upper doctor blade.

5. An inking device according to any preceding claim, wherein an outlet pipe for discharging ink from the inking chamber extends from a bottom portion of the inking chamber and the outlet pipe leads to the ink return pipe.

6. A printing machine comprising a plurality of inking devices according to any of claims 1 to 5, wherein the distance between the bottom of the ink vessel and the outlet pipe level is substantially the same for all the inking device of the printing machine.

7. A inking device for a printing machine, the device being substantially as hereinbefore described with reference to the drawing.