WO2007022783A1

WO2007022783A1 - Sleeve printing unit

Info

Publication number: WO2007022783A1
Application number: PCT/DK2006/050035
Authority: WO
Inventors: Torben Rasmussen
Original assignee: Nilpeter A/S
Priority date: 2005-08-23
Filing date: 2006-08-22
Publication date: 2007-03-01
Also published as: EP1928664A1

Abstract

The present invention relates to replaceable printing technologies in a printing unit of a machine for printing webs (10) of material, preferably endless webs of material. The invention relates in particular to a technique comprising replaceable sleeves (4,5,6,7) arranged on shafts (2,3).

Description

SLEEVE PRINTING UNIT

The present invention relates to replaceable printing technologies in a printing unit of a machine for printing webs of material, preferably endless webs of material.

Background of the invention

When printing decorations and the like on webs of material that are used for labels and packaging, it will in many cases be advantageous to combine various printing technologies, while in other cases, it might be advantageous, and occasionally a necessity, to produce a print by means of one particular printing technology. The desire to use one particular printing technology may be based on the design of the print or/and the substrate onto which it will be printed. The importance of being able to adapt to these circumstances is on the increase nowadays, e.g. due to globalisation, when many products are marketed worldwide, while the packaging is manufactured regionally. However, the product still has to be considered as the same "brand", no matter where it has been produced.

Prior art solutions for the described circumstances have come about since the individual printing technologies (processes) are performed in such a manner that enables them to replace each other in the printing unit. In some cases, the process part is complete with separate web transport (printing roller), while in other cases the processes use the same web transport (printing roller). The latter case is for example described in EP 757 627.

Disclosure of the invention

The present invention relates to a printing unit which can alternate between off-set printing and flexo printing, in which the two printing technologies not only share the same web transport (printing roller) (pos. 1) but also share 2 "shafts" (pos. 2 and 3) which are prepared to be fitted with a sleeve (pos. 4 and 5). In cases of offset printing, these "shafts" act as plate roller (pos. 6) and rubber cloth roller (pos. 7), while in cases of flexo printing they act as raster roller (pos. 4) and cliche roller (pos. 5).

One of the advantages of this solution is that the change between the printing processes is substantially faster, and at the same time, puts fewer demands on the operator's physique, since the weight of the individual sleeve is extremely light, and they can therefore be handled without the use of aids. Another advantage is that the "shafts" are an integrated part of the construction of the unit, which means that the control system is common for both processes. Yet another advantage is that the cost of equipment/yield parameters are more advantageous for the printing company than prior solutions. It should be noted that although the invention is described herein as including offset printing and flexo printing, the invention may also include other printing technologies and combinations thereof. In the following, a preferred embodiment of the invention will be explained with reference to the figures, in which

Figure 1 schematically shows a preferred embodiment of the printing unit in accordance with the present invention, configured as a flexo printing unit,

and

Figure 2 schematically shows a preferred embodiment of the printing unit in accordance with the present invention, configured as an offset printing unit.

Explanation of the figures

Figure 1 shows the parts in question configured as a flexo printing unit. The web material (10) is supported by the printing roller (1), which in the shown is fixedly mounted in the printing unit. The flexo unit's raster roller (4) is a removable sleeve which is applied to a fixedly mounted shaft (2) in the printing unit. The shaft (2) is suspended in such a manner that it may be displaced parallelly (8) in a horizontal plane. The flexo unit's cliche roller (5) is also a removable sleeve, which is applied to a fixedly mounted shaft (3) in the printing unit. The shaft (3) is suspended in such a manner that it may be displaced parallelly (9) in a vertical plane. The preferred system to provide colour to the raster roller is by a doctor blade. In order for the invention to be more clearly understood, the system is not shown in the figure.

Figure 2 shows the arrangement configured as an offset printing unit. In this, the raster roller (4) is replaced by the printing unit's offset plate roller (6), which is also a removable sleeve that has been applied to the fixedly mounted shaft (2) of the printing unit. The flexo unit's cliche roller (5) is replaced by the printing unit's offset rubber cloth roller (7), which is also a removable sleeve that is applied to the fixedly mounted shaft (3) in the printing unit. In order for the invention to be more clearly understood, the system that provides moisture and/or colour to the plate roller of the offset printing unit, is not shown in the figure.

It should be noted that tools in sleeve variations of both offset plate roller, offset rubber cloth roller, flexo raster roller and flexo cliche roller are commercially available. In the preferred embodiment of the invention, the sleeve, which is compressible on the inside, is pushed along the shaft, which is provided with channels to an inner chamber which is provided with pressurized air forming a layer of air, whereupon the sleeve may be displaced. After the sleeve has been mounted, the supply of pressurized air is stopped, which causes the inner side of the sleeve to contract, and the sleeve is retained on the shaft.

Claims

1. A printing unit, wherein at least two shafts, preferably being integrated, are used in connection with at least two different printing principles.

2. A printing unit according to claim 1, wherein a printing roller is fixedly mounted around one of the shafts, and wherein the other shaft is prepared to be fitted with a replaceable sleeve.

3. A printing unit according to claim 2, wherein the replaceable sleeve may be of different diameter and different surface nature, depending on the desired function/process to be performed.

4. A printing unit according to claim 3, wherein the replaceable sleeve may act as cliche roller in a flexo process, or alternatively as a rubber cloth roller in an offset process.

5. A printing unit according to claim 1, wherein a third shaft, preferably being integrated, which is prepared to be fitted with a sleeve, is used in connection with at least two different printing principles.

6. A printing unit according to claim 5, wherein the replaceable sleeve of the third shaft may act as raster roller in a flexo process, or alternatively as a plate roller in an offset process.

7. A printing unit according to any of the preceding claims, wherein the replaceable sleeve is compressible at least on its inside.

8. A printing unit according to any of the preceding claims, wherein one or more of the shafts comprises channels to an inner chamber which is provided with pressurized air to form a layer of air, whereupon the sleeve may be displaced.

9. A printing machine with a printing unit concept according to any one of the preceding claims.