Arrangement of flexographic printing press with a central impression cylinder

Abstract

 Present invention relates to an arrangement of the flexographic printing press with a central impression drum comprising at least one unwind unit (1), printing unit (2), drying unit (3), cooling unit (4) and rewind unit (5), the principle of which lies in the fact that it comprises a printing part (A) of the machine, in which are arranged units directly related to printing, and the end part (B) of the machine, which comprises at least an unwind unit (1) and a rewind unit (5), and the printing part of the machine is spatially separated from the end part of the machine. The printing part of the machine, in which units directly related to printing are arranged, thus comprises a printing unit (2) followed by a drying unit (3) and a cooling unit (4). The unwind unit and rewind unit may be made in a carousel-type arrangement. The roll of printing material may be loaded from the side or from the front.

Description

Field of the Invention

[0001] The invention refers to an arrangement of a flexographic printing press with central impression drum which includes at least one unwind unit, printing unit, drying unit, cooling unit and rewind unit, more specifically, mutual arrangement of individual units of the flexographic machine.

Background of the Invention

[0002] The flexographic printing presses with central impression drum are used for printing on materials of variable width using traditional solvent-based and water-based inks. These machines are used for printing on rolls of paper, foil and laminate. From the functional point of view the flexographic printing presses consist of at least the following units: unwind unit which unwinds the printed material, printing unit which prints on the material, drying unit which dries the print on the material, cooling unit which cools down the material and rewind unit, which rewinds the printed material. Currently all the flexographic printing presses equipped with central drum are known to use the arrangement shown in Fig. 1. This known arrangement of the flexographic printing press primarily reflects the shortest travel of the material through the machine and, naturally, it respects the condition that the printed material must not get into contact on its printed side with the guiding roller before it is dried and cooled down, otherwise the printed motive would be damaged. In such an arrangement is the unwind unit located as close as possible to the printing unit, and after the last print deck there are the drying unit and cooling unit. Before the rewind unit positioned at the end there are, sometimes, other units too, such as a cutting unit, lacquering unit, laminating unit etc. Adding an intaglio unit, or any other additional application unit, between the unwind unit and the printing unit of the machine in standard arrangement of units is very complicated, and it technically requires rebuilding a major part of the machine. In such instances, the requirement for application of layers prior to printing is usually addressed by adding an operation, i.e. it is done on a different machine prior to printing. A drawback of such technology lays in the fact that the operation requires more time and extra production costs associated with packing of finished products.

[0003] The above specified standard arrangement of flexographic printing press' units has drawbacks described in detail in the following sections, and these drawbacks concern primarily worse operability of the machine, limited variability and, in some cases, they lead to increased dimensions of the machine;

• Working space for the machine operators - with the unwind unit located as close to the printing unit as possible, space limitation occurs during loading of a roll of material and the space for an access of operators to this part of printing unit is partly, but most of the times completely, blocked off. This drawback has been eliminated, for example, on machines by Fischer & Krecke (today BOBST) by turning the unwind unit and loading the rolls of material from the direction of the rewind unit, which is a so called "face-to-face" arrangement.
• Web path access - the material being processed on a flexographic printing press of above described standard arrangement of units is guided over unwind unit towards the printing unit. The machine operators have a rather complicated access to this section, especially when introducing the material into the machine, e.g. in case it rips. This drawback is usually compensated by the system of pulling the material mechanically through the machine.
• Machine variability - placement of the unwind unit implies that any change of its type, including mostly also the change of its dimensions, affects location of the surrounding parts of the machine. At least, the frames of the machine have to be extended or shortened, and other units have to be shifted. In some cases it is necessary to place another unit for material pre-print processing between the unwind unit and the printing unit (e.g. application of coats for better adhesion of print inks on printed material), which may, depending on the dimensions of the given unit, require rebuilding of a major part of the printing machine.
• Machine height - components of flexographic printing presses which have to be placed into the path of material between the unwind unit and the printing unit because of their function (see Fig. 1), e.g. web guiding system prior to print, corona treatment unit etc., have to be, in a standard arrangement of units, placed above the unwind unit, and this can increase the machine height more than it would be necessary in a different arrangement.

Summary of the Invention

[0004] The invention relates to the arrangement of flexographic printing press with central impression drum, which may simplify its operability and increase its variability.

[0005] The above specified drawbacks are removed and the specified goal is achieved by different arrangement of the flexographic printing press with a central impression drum comprising at least one unwind unit, printing unit, drying unit, cooling unit and rewind unit, the principle of which lies in the fact that it comprises a printing part of the machine, in which are arranged units directly related to printing, and the end part of the machine, which comprises at least an unwind unit and a rewind unit, and the printing part of the machine is spatially separated from the end part of the machine.

[0006] The printing part of the machine, in which are arranged units directly related to printing, thus comprises a printing unit followed by a drying unit and a cooling unit. The unwind unit and rewind unit may be made in a carousel-type arrangement. The roll of printing material may be loaded from the side or from the front.

[0007] An advantage is that with the new concept of the unit arrangement, the flexographic printing press with central impression drum may, in its variability and operability, compete with machines with "inline" unit arrangement, which may be achieved thanks to the fact that individual units of flexographic printing press are positioned in a line.

[0008] Removal of units, of which type and form may often vary, from the printing part of the machine, enables the height and length of the machine to be defined solely by the requirements of its particular configuration. That brings an option to install the machine into the premises (production halls), where it would not be normally possible.

[0009] The web path through the machine may be arranged so as to be accessible as fast and best as possible for the operators without the need to use ladders, ramps and other means.

[0010] Division of the machine into two above specified parts causes also the division of work spaces for the machine operators. The work space, which is necessary for loading and removing rolls of material into and out of the machine at the end part of the machine, does not interfere with the work space which is necessary for operators of printing part of the machine, where the printing unit is incorporated. That means that the operation related activities regarding printing - preparation, settings etc. are not limited by activities related to material - rolls exchange. Both activities may thus proceed simultaneously which leads to higher efficiency of the machine.

[0011] Technical solution described in this invention will enable the use of various combinations of unwind and rewind units, and addition of more units into the web path between these units and the printing unit. The end part may therefore still contain units for further processing of the printed material, e.g. units for further coating/printing past the unwind unit or before the rewind unit, such as intaglio or flexographic printing unit and the like. Moreover, it is easy to adopt these changes later, in the course of service life of the machine.

[0012] The printing part and the end part are preferably functionally separated. In such instance the individual function parts of the machine, i.e. units used in flexographic printing press with central impression drum, have to be of adapted design so as to meet the condition of operability in any combination with other units. That implies that individual units must be mechanically, electrically, pneumatically etc. independent. Under this condition, the units can be freely combined or replaced in particular arrangements of the flexographic printing press. That practically means that each unit, if it is required by its functions, has its independent control unit (PLC), independent electrical installation, independent pneumatic circuits etc.

[0013] The units are mechanically linked in a standard manner using frames which serve also for guiding rollers and for guiding the material through the machine between units. Vertical frames of the end part of the machine are preferably the same for all unwind and rewind unit versions. When the mutual position of unwind and rewind unit changes, e.g. due to their embodiment, only the horizontal frame is changed.

[0014] From the control point of view, it is preferred to control the printing part of the machine by one PLC unit and the end part units to have their own independent PLCs. That makes the printing part and the end part of the machine mutually absolutely independent.

[0015] A function unit is replaced by a different function unit with the same basic function, but in different embodiment, most often in case of unwind and rewind units, embodiment of which may greatly differ from the basic embodiment for a single roll to carousel-type embodiment with continuous replacement of rolls. This concept enables also easy replacement of the printing part of the machine.

[0016] With the new machine concept the embodiment of the printing part is determined neither by the unwind unit, nor by the units placed between the unwind unit and the printing unit. Width and length of the printing part of the machine is determined only by the arrangement of print decks in the printing unit and by the web path in the drying unit. The web path in the printing part may be suitably adapted for easy and quick access to the material for printing.

[0017] The new machine concept is designed so as to enable implementation of all the above specified requirements. It is presumed that all alternations of the configuration of the machine units will take place at the end part of the machine and the printing part will not be affected by these changes.

[0018] Due to the variability of the machine's new concept, new technologies may be implemented into the flexographic printing press, which would otherwise had to be performed on different machines in additional operations, hence the production efficiency increases. Specifically, this may relate to the application of primer, application of base color on transparent materials, application of lacquers (to increase abrasion resistance, to increase print gloss, to increase barrierity of package,...), application of adhesives (coldseal), package customization, package perforation, rotation section cuts, etc.

[0019] The new concept of the machine is particularly suitable for machines designed for higher operation efficiency for short orders. Not only does it allow configuring the machine exactly according to the requirements of the customer, it also enhances ergonomic features and speed of machine control.

[0020] The new concept of the machine is also ready for potential future changes in configuration of units according to trends in package production.

Description of the Drawings

[0021] Exemplary embodiment of this technical solution is shown in drawings, where Fig. 1 shows the known embodiment of the flexographic printing press with central impression drum with standard arrangement of units, Fig. 2 shows the new concept of the unit arrangement of flexographic printing press with central impression drum, Fig. 3 shows the option for incorporation of coating application units for flexographic printing press with central impression drum, and Figs 4a to 4e show possible versions of embodiments of flexographic printing press with central impression drum using various unwind/rewind unit types in the end part.

Description of the Preferred Embodiments

[0022] Principle of unit arrangement of flexographic printing press with central impression drum according to this technical solution will be further clarified, but not limited, in the following examples.

[0023] Basic embodiment of the flexographic printing press with central impression drum designed according to this new concept consists of two parts, as shown in Fig 2. The first one is the printing part A of the machine which includes the printing unit 2, drying unit 3 and cooling unit 4. The printing part A of the machine remains unchanged for all the versions of the flexographic printing press, i.e. it is not in any manner influenced by the arrangement of other units, alternatively, it can be entirely replaced with another printing part A1 with different parameters (e.g. different length of printing etc.) The second part of the machine consists of the end part B which comprises the unwind unit 1 and rewind unit 5 or other required units, for example, cutting unit, pre-printing coat application unit, printing lacquering unit, reprint unit etc. Arrangement of the printing part A and the end part B is designed so that any change of type of the embodiment of any unit would have minimal impact on other units incorporated in respective parts of the flexographic printing press.

[0024] Exemplary combination of the flexographic printing press with central impression drum with incorporated units for coating application is shown in fig 3. The flexographic printing press in this embodiment has the printing part A which includes printing unit 2, drying unit 3 and cooling unit 4, which are the same as in the described basic embodiment of the flexographic printing press. The second part of the machine consists of the end part B, where before the unwind unit 1 and rewind unit 5 there is an intaglio unit 8 for application of pre-print primer coats and intaglio unit 9 designed, for example, for print lacquering. It is clear that the above described units do not necessarily have to be intaglio units, but they can be replaced by flexographic units, alternatively by other technology of coating application or reprinting, which is possible with the new concept of the machine.

[0025] Other versions of arrangement of the flexographic printing press with central impression drum, including various types of unwind units 1 and rewind units 5, including their mutual combinations, are shown on Fig 4, wherein individual arrangement versions are shown in figs. 4a to 4e and described below.

[0026] Fig. 4a shows a flexographic printing press containing rewind unit 5 and unwind unit 1 in shaft-less embodiment for a single roll. In this arrangement, the rolls of material are loaded to unwind unit 1 using a forklift for rolls. The roll is fastened in the machine using cones. The material first passes through the printing unit 2, then through the drying unit 3 and continues to cooling unit 4. At the end of the machine the material gets rewound onto a roll fastened in rewind unit 5. The roll of rewound material is removed from the machine using a forklift.

[0027] Fig. 4b shows a flexographic printing press containing unwind unit 1 in a shaft-less embodiment for a single roll and a carousel rewind unit 51 for two rolls in continuous operation with side removing of the rolls. In this setup the rolls of material are loaded to unwind unit 1 using a forklift for rolls. The roll is fastened in the machine using cones. The material first passes through the printing unit 2, then through the drying unit 3 and continues to the cooling unit 4. At the end of the machine the material gets rewound onto a free fastening shaft on the carousel rewind unit 51. The carousel rewind unit 51 can be in continuous operation, which means that the rewound rolls are removed without stopping of the machine. The rolls are removed from the carousel rewind unit 51 using a built in lifting platform.

[0028] Fig. 4c shows a flexographic printing press containing carousel rewind unit 51 and carousel unwind unit 11 for two rolls in continuous operation with side removing or loading of the rolls. In this setup the rolls of material are loaded to carousel unwind unit 11 using a built in lifting platform. The roll is fastened on a free fastening shaft.

[0029] The carousel rewind unit 11 can also be in continuous operation, which means that the rewound rolls are removed without stopping of the machine. The material passes first through the printing unit 2, then through the drying unit 3 and continues to the cooling unit 4. At the end of the machine the material gets rewound onto a free fastening shaft on the carousel rewind unit 51. The carousel rewind unit 11 can also be in continuous operation. The roll is removed from the carousel rewind unit 51 using a built in lifting platform.

[0030] Fig. 4d shows a flexographic printing press containing unwind unit 1 in shaft-less embodiment for a single roll and a carousel rewind unit 52 for two rolls in continuous operation. In this setup the rolls of material are loaded to unwind unit 1 using a forklift for rolls. The roll is fastened in the machine using cones. The material passes first through the printing unit 2, then through the drying unit 3 and continues to the cooling unit 4. At the end of the machine the material gets rewound onto an inserted fastening shaft in carousel rewind unit 52. The carousel rewind unit 52 can be in continuous operation, which means that the rewound rolls are removed without stopping of the machine. The rolls are removed from the carousel rewind unit 52 with the fastening shaft using a built in lifting platform, or using a forklift.

[0031] Fig. 4e shows a flexographic printing press containing carousel unwind unit 12 and carousel rewind unit 52 for two rolls in continuous operation. In this setup are the rolls of material with inserted shaft loaded into the carousel unwind unit 12 using a built in lifting platform, or using a forklift. The unwind unit may be in continuous operation, which means that the unwound rolls are changed without stopping of the machine. The material passes first through the printing unit 2, then through the drying unit 3 and continues to the cooling unit 4. At the end of the machine the material gets rewound onto an inserted fastening shaft in carousel rewind unit 52. The carousel rewind unit 52 can be in continuous operation. The rolls are removed from the carousel rewind unit 52 with the fastening shaft using a built in lifting platform, or using a forklift.

[0032] The above described versions take into account an option of incorporating, behind the unwind unit 5 or before rewind unit 1, a unit for application of coating using various printing technologies, for example, flexographic unit or intaglio unit 8 and 9.

Industrial Applicability

[0033] Flexographic printing presses with central impression drum are used especially for printing on flexible materials (PE, PP, BOPP, PET and the like). Besides that it is also possible to print on paper, aluminum foils, laminates etc. Their rather broad range of uses requires various configurations of the unwind units, rewind units and, alternatively, also an addition of further units for pre-print or post-print processing of the material.

List of Reference Signs

[0034] 

A

printing part

B

end part

1

unwind unit

11

carousel unwind unit - front roll loading

12

carousel unwind unit - side roll loading

2

printing unit

3

drying unit

4

cooling unit

5

rewind unit

51

carousel rewind unit - front roll removing

52

carousel rewind unit - side roll removing

6

web guiding system prior to printing

7

web surface finishing - corona unit

8

unit for application/printing after unwind

9

unit for application/printing before rewind

Claims

1. An arrangement of a flexographic printing press with central impression drum comprising at least one unwind unit, printing unit, drying unit, cooling unit and rewind unit, characterized in that, it consists of a printing part (A) of the machine, in which the units directly related to printing are arranged, and an end part (B) of the machine which includes at least the unwind unit (1) and the rewind unit (5), wherein the printing part (A) of the machine is spatially detached from the end part (B) of the machine.

2. An arrangement of a flexographic printing press with central impression drum according to claim 1, characterized in that the printing part (A) and the end part (B) are functionally separated.

3. An arrangement of a flexographic printing press with central impression drum according to any of the claims 1 or 2, characterized in that the printing part (A) comprises a printing unit (2) followed by a drying unit (3) and a cooling unit (4).

4. An arrangement of a flexographic printing press with central impression drum according to any of claims 1 to 3, characterized in that individual units of the printing part (A) and/or the end part (B) are connected together with frames.

5. An arrangement of a flexographic printing press with central impression drum according to any of previous claims, characterized in that the printing part (A) of the machine remains identical for all versions of the machine.

6. An arrangement of a flexographic printing press with central impression drum according to any of previous claims, characterized in that the end part (B) further comprises the units for further processing of printed material.

7. An arrangement of a flexographic printing press with central impression drum according to any of previous claims, characterized in that the units of the end part (B) of the machine are mutually independent and may be freely combined.

8. An arrangement of a flexographic printing press with central impression drum according to any of previous claims, characterized in that the individual units of the machine are arranged in a line.

Drawing