Patent Application
20060162592
The invention lies in the printing technology field. More specifically, the invention relates to a gravure printing unit for printing a printing material web in a printing press, having at least one gravure cylinder, one ink applicator device, and one impression roller.
In printing presses for printing labels, in particular self-adhesive labels, great flexibility or variability is desired increasingly, in order for it to be possible to carry out as many different print jobs as possible, in particular with production of special optical effects by the printed image or the printed text. In order to produce labels, printing presses are used particularly frequently which process a narrow web of a printing material and have a number of connecting platforms or interfaces, on which in each case one functional unit or one process module can be accommodated releasably for printing with a defined printing process. For example, one exemplary embodiment of a printing press of the generic type is described in the U.S. Pat. No. 4,384,522.
There, the individual functional units can operate with differing printing processes.
Commonly assigned U.S. Pat. No. 6,019,046 (German published patent application DE 195 13 536 A1) and U.S. Pat. No. 5,697,297 (Int'l PCT publication WO 95/29813) discribe printing presses which have a plurality of printing units of inline construction and permit the releasable accommodation of a number of functional units or process modules on a number of connecting platforms. Inter alia, the functional units can comprise printing units or parts of printing units in cassettes or attachments which operate according to a letterpress process, a flexographic printing process, a screenprinting process, an offset printing process, a gravure printing process or an inkjet printing process. Moreover, functional units (processing units) are provided which permit mechanical processing steps on the printing material, for example embossing, trimming (perforating, punching) or turning. Printing presses of this type which can operate with a plurality of different printing processes are also known as combination printing presses or hybrid printing machines, which are generic terms in this technical field.
One configuration of a gravure printing unit that is used frequently, as is also used in the form of a functional unit for a printing press which is equipped with connecting platforms for changing purposes, is shown, for example, in German patent DE 42 42 582 C2. The circumferential surface of a gravure printing form cylinder, also called an gravure cylinder further below, dips at least partially into an ink pan or ink trough which is filled with gravure printing ink and is arranged below the gravure cylinder. When the gravure printing cylinder is rotated about its axis of symmetry, the depressions in the circumferential surface which pass the trough are filled with gravure printing ink. Excess ink is wiped off by at least one doctor which is set against the circumferential surface. In a press nip which lies in the upper angular sector of the gravure printing form cylinder, the gravure printing ink is transferred onto a printing material which is pressed onto the inked circumferential surface of the gravure printing form cylinder by means of a impression roller, often also called an impression roller. If a gravure printing unit of this type is configured as a process module, in particular in the form of an attachment or a cassette, for a printing press having connecting platforms, the result in a web processing printing press is the practical disadvantage which is not to be underestimated that the printing material web has to be threaded through the gravure printing unit along its path. In other words, the paths of the web through the printing press differ from one another with and without the gravure printing press. The change from a gravure printing unit to a printing unit which operates with another printing process, or vice versa, is therefore associated with a corresponding changeover time.
Furthermore, German published patent application DE 41 39 343 A1 describes a proof or sample printing press which has an impression roller cylinder that can be exchanged. Further exchangeable cylinders which are mounted on movable carriages, optionally a gravure printing cylinder or a flexographic printing cylinder which interacts with an anilox cylinder, can be set against the impression roller cylinder. The exchangeable cylinders are driven by the impression roller cylinder by a frictional connection or by a form-fitting gearwheel connection.
It is likewise to be noted at this point that, if gravure printing inks are used which contain solvents, measures have to be taken for protection against explosions and for environmentally friendly disposal. An insulated printing zone (encapsulation, protective covering) is provided, from the area of risk of which, in particular, open electrical components are removed. The solvent fumes are often also extracted by suction. If solvent-free, UV light-curable gravure printing inks are used as an alternative to gravure printing inks which contain solvents, a corresponding selection of materials in the gravure printing unit and adapted engraving of the gravure printing cylinder are required. A device for illuminating with UV light is also arranged behind the press nip of the gravure printing unit, typically directly behind the latter, and optionally integrated with the gravure printing unit.
It is accordingly an object of the invention to provide a gravure printing unit for printing a material web in a printing machine which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and wherein the gravure printing unit permits rapid replacement by a printing unit which operates according to different printing process.
With the foregoing and other objects in view there is provided, in accordance with the invention, a gravure printing unit assembly for printing a printing material web in a printing press, comprising:
a gravure cylinder, an ink applicator device, and an impression roller together disposed to form a functional gravure printing unit;
at least one connecting element for releasably mounting said gravure printing unit on a connecting platform of the printing press and forming a releasable operative connection with a separate drive for said gravure cylinder, wherein said gravure cylinder and said ink applicator device are separable from said connecting platform, while said impression roller remains in the printing press.
In other words, the gravure printing unit according to the invention for printing a printing material web in a printing press, has at least one gravure cylinder (used in this text as a short form for “gravure printing form cylinder”), one ink applicator device and one impression roller. The unit further has at least one connecting element for releasable accommodation on at least one connecting platform of the printing press and for producing a releasable operative connection having a separate drive for the gravure cylinder, with the result that the gravure cylinder and the ink applicator device can be separated from the at least one connecting platform, the impression roller remaining in the printing press, that is to say, in other words, the gravure cylinder and the ink applicator device can be separated without separating the impression roller from the printing press.
Here, the separation or the closing of the connection can preferably be effected without the course of the printing material web through the printing press being changed and/or without the printing material web being severed. According to the invention, there can be a first number, in particular a plurality, of connecting elements which serve only for the releasable accommodation on at least one connecting platform of the printing press, and a second number, in particular one or a plurality, of connecting elements which serve both for the releasable accommodation on at least one connecting platform of the printing press and also for producing a releasable operative connection having a separate drive for the gravure cylinder.
The gravure cylinder can be configured in such a way that it can hold a gravure printing form, in particular in the form of a sleeve, or that its circumferential surface forms an engraved gravure printing form.
In one preferred embodiment, the gravure printing unit has at least two connecting elements, at least one first connecting element being adapted or configured for the releasable accommodation of the gravure cylinder on a first connecting platform of the printing press, and at least one second connecting element being adapted or configured for the releasable accommodation of the ink applicator device on a second connecting platform of the printing press. In other words, both the gravure cylinder and the ink applicator device can be separated from the printing press and attached to the printing press independently of one another. Here, the first and the second connecting platforms can be configured particularly advantageously so as to be movable relative to one another, in particular so as to be displaceable or pivotable. Adaptation to different gravure printing cylinder diameters (which are dependent on the format) is possible by a relative movement, in particular a lateral displacement, with respect to one another. The accessibility can be increased or reduced in accordance with the different operations (printing, cleaning, setting up).
Furthermore, the gravure printing unit according to the invention can advantageously be configured in such a way that a connection is possible to at least one connecting platform which is configured so as to be displaceable in the substantially horizontal direction. In particular, the printing press can be a printing press of inline construction, that is to say having printing units which are arranged in the horizontal direction.
As an alternative or in addition to the measures which have already been described, the ink applicator device can be a chamber-type ink doctor which interacts with the gravure cylinder. The chamber-type ink doctor can be open, that is to say have an ink circuit with a continuous ink flow through the ink chamber, or closed. The chamber-type ink doctor can have a doctor which is thrown on at an acute angle to the rotational direction of the circumferential surface (negative doctor), so that work can be carried out with less pressure in order to set the doctor against the circumferential surface. The dependence of the print quality on the speed can be reduced. The consequence is advantageously less wear of the doctor. In an advantageous development, the gravure printing unit can have a pneumatic device for throwing the chamber-type ink doctor onto the gravure cylinder, in particular in the form of a number of pneumatic cylinders. The throwing-on pressure can be controlled or regulated as a function of the printing speed and/or the service life of the doctor (a measure for the wear of the doctor). As an alternative or in addition to this, the gravure printing unit can have a movement device for the lateral oscillation of the chamber-type ink doctor, that is to say substantially parallel to the rotational axis of the gravure cylinder.
Geometric alignment of the ink applicator device, in particular of the chamber-type ink doctor, with the gravure printing cylinder can preferably be carried out via eccentrics which can be adjusted individually on the drive side and operating side and independently of one another. The eccentrics can be configured as part of the connecting platform, that is to say integrated with the printing press. The throwing-on operation for printing of the ink applicator device, in particular of the chamber-type ink doctor, can be effected via at least two pneumatic cylinders which are connected in parallel as part of the ink applicator device.
Furthermore, it is advantageous for the gravure printing unit to have a separate drive apparatus for the gravure cylinder (individual drive, that is to say separate from the drives for producing further forms of movement in the printing press, such as the transport of printing material or the operation of other printing units or processing units). The separate drive apparatus is, in particular, independent of the drive of the impression roller in the gravure printing unit. In particular, the gravure printing unit can have a separate drive apparatus for the direct drive of the gravure cylinder. The operative connection can consist in that the shaft of the gravure cylinder is connected to the drive apparatus directly (with or without a gear mechanism or belt connected in between) and is set in rotation by said drive apparatus. The drive apparatus can be a servomotor. When the printing press is started up, it is possible for the gravure printing unit, in particular with a chamber-type ink doctor, to be started up without waste paper losses. Corrections to the format length are possible during printing due to the individual drive. It is preferred here that the separate drive apparatus is accommodated in the printing press and can be connected releasably to the gravure cylinder. In particular, at least one of the connecting elements of the gravure printing unit can represent not only a mechanical connection, but also a drive connection at the same time.
As an alternative or in addition to the features which have already been mentioned, the gravure printing unit can comprise an anti-ghosting device, in particular in the form of a third doctor or a roll which rolls on the circumferential surface of the gravure cylinder, with the result that eddying is produced in the flow in the reservoir of the ink applicator device. In one particular embodiment, the roll can be coated with rubber. The roll can have, in particular, suitable engraving for improved traction. Furthermore, the ink applicator device and/or the gravure cylinder of the gravure printing unit can have at least one heating element, with the result that the ink which is to be printed can be temperature-controlled. Heating is carried out to temperatures between 35 and 40 degrees Celsius for typical gravure printing inks. The flow properties of the gravure printing ink are influenced by the temperature control, with the result that the cells or depressions in the cover of the gravure printing cylinder can be filled in an improved manner. This can have the effect of a higher layer thickness and higher gloss in the printed image.
As an alternative or in addition to the features which have already been described, the impression roller can be accommodated in the printing press in a releasably connected manner. It is optionally necessary also to exchange the impression roller when changing from a first to a second printing process. A impression roller can also be used in a manner which is specific to the application, the circumferential surface of said impression roller having a defined hardness depending on the application.
The gravure printing unit according to the invention is preferably configured in such a way that the gravure cylinder and the impression roller are arranged in the printing press in such a way that their rotational axes lie substantially in a horizontal plane. This arrangement is particularly advantageous, inter alia, if cylinders having different diameters are to be used without changing the fundamental geometry of the gravure printing unit. Furthermore, this construction corresponds to advantageous arrangements of printing units which operate according to other printing processes, with the result that standardization is achieved. However, the gravure printing unit according to the invention can also be configured in such a way that the rotational axes of the gravure cylinder and the impression roller do not lie in a horizontal plane.
The gravure printing unit can also be configured so as to be usable for printing printing ink which can be cured by UV light (gravure printing ink which is free of solvents).
In one advantageous embodiment, the gravure printing unit according to the invention can have, furthermore, at least one additional deflection roller which is arranged above the impression roller in such a way that the wrap of the printing material web around the impression roller is reduced in comparison with operation without the at least one deflection roller. In this way, it is possible for the printing material web to follow a longer course after printing, for example for longer drying. This is advantageous, in particular, for production of a gloss effect, for example when varnishes are printed.
Also in conjunction with the concept of the invention is a gravure printing unit module having at least one gravure cylinder and one ink applicator device, which gravure printing unit module, in interaction with a impression roller which is accommodated in a printing press, realizes a gravure printing unit having features in accordance with this illustration. The gravure printing unit module can be configured, in particular, as a cassette, attachment or slide-in unit.
In conjunction with the concept of the invention is, furthermore, a printing press, suitable for printing a printing material web using a plurality of different printing processes, in particular a hybrid printing press or a combination printing press. The printing press according to the invention is distinguished by at least one gravure printing unit having features according to this representation. In particular, the printing press can be a narrow web printing press. In particular, the printing press can be configured to be of inline construction. In particular, the printing press can be a label printing press, an adhesive label printing press or a self-adhesive label printing press.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a gravure printing unit for printing a printing material web in a printing press title, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now to the figures of the drawing in detail and first, particularly, to
The embodiment which is shown in
This application claims the priority, under 35 U.S.C. § 119, of German patent application No. 10 2005 003 206.0, filed Jan. 24, 2005, and German patent application No. 10 2005 044 516.0, filed Sep. 16, 2005; the disclosures of the prior applications are herewith incorporated by reference in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 003 206.0 | Jan 2005 | DE | national |
| 10 2005 044 516.0 | Sep 2005 | DE | national |
