EP3444115B1

EP3444115B1 - Sheet-fed flexographic printing press

Info

Publication number: EP3444115B1
Application number: EP17781736.8A
Authority: EP
Inventors: Lixiang Ma; Jinping Wu
Original assignee: Nanjing Mint Co Ltd; China Banknote Printing and Minting Corp
Current assignee: Nanjing Mint Co Ltd; China Banknote Printing and Minting Corp
Priority date: 2016-04-11
Filing date: 2017-02-15
Publication date: 2022-03-23
Anticipated expiration: 2037-02-15
Also published as: CN107160827A; EP3444115A4; JP6408170B2; JP2018514415A; WO2017177760A1; EP3444115A1; CN107160827B

Description

Technical field

The present invention relates to the technical field of printing equipment, and more particularly to a sheet-fed flexographic printing press.

Background

For existing flexographic printing press, especially the double-sided flexographic printing press, in order to satisfy the requirements of high production efficiency, ink drying and curing process are conducted on the printing surface immediately after printing such that the printing operations on the next step or the next side can be carried out. The existing fast drying technology for printed product usually uses hot air, infrared or UV light curing and other principles, to achieve the fast drying of printed product. The above drying method will have a thermal effect on the printed surface, causing a slightly warping due to slight increase of temperature on one side surface of the printed product, or even seriously significant deformation of printed product. In special circumstances, this even leads to cooking or burning of the printed product. In addition, since the demand for quality of the printing production is getting stricter, the user proposes more requirements to the online quality inspection system of the printing equipment. The existing flexographic printing presses are still poor in terms of the online inspection system and the printing quality.
Figure 4 is a flow chart of an existing double-sided flexographic printing press, and the two printing color groups corresponding to both sides of the printed product in the flow chart are sequentially connected. The printing, drying, and curing of the other surface (B side) is carried out immediately after the ink is dried and cured by the drying device upon printing completion of the first side (A side).
Then, And the quality check of the two printing surfaces is carried out respectively in the checking drum. The printing structure has thermal accumulation problems when continuous drying of the printed product is conducted. The deformation caused by overheating and other issues affects the printing quality.
Additionally, in the printing machine structure used in the process, the on-line checking of both sides of the printing process is carried out after the two printings are completed, so that the feedback of the printing quality problems on the first side can be received only after the printing of the second side is completed. Therefore, there is a delay in quality control.
Figure 5 is a schematic representation showing the arrangement of the printing unit drums of an existing double-sided flexographic printing press. The arrangement of the printing unit drums conforms to the printing process shown in Figure 4. The flexographic printing press adopts the printing method of continuously printing on both sides, which causes the above-mentioned problem of thermal accumulation of printed product and timeliness control of the printed product quality during the production process.
The patent document WO2011/l45028 A1 shows a sheet-fed printing press according to the preamble of claim 1 for numbering and varnishing of security documents, including banknotes, including a numbering group comprising at least one numbering unit for numbering printed material in the form of individual sheets carrying multiple security imprints; and - a varnishing group located downstream of the numbering group for applying varnish onto recto and verso sides of the printed material, the varnishing group comprising at least a first varnishing unit disposed above a path of the printed material to apply varnish on the recto side of the printed material and at least a second varnishing unit disposed below the path of the printed material to apply varnish on the verso side of the printed material.
Another example of a modular sheet-fed printing press is provided in the document EP 1 818 177 A2

Summary of the invention

In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a sheet-fed flexographic printing press which reduces the thermal accumulation of the printed product and timely detects quality problems of the printed product, as defined in claim 1.
A technical solution for achieving the object of the present invention is that a sheet-fed flexographic printing press includes a first printing unit and a second printing unit each for printing a side of a sheet of a printing stock, respectively. The first printing unit comprises a first impression drum, a first printing paper delivering drum I, at least a first flexographic printing drum for installing a flexographic plate, a first printing ink drying and curing device and a first printing paper delivering drum II, wherein the at least first flexographic printing drum is provided with a corresponding first ink supply system; the second printing unit comprises a second impression drum, a second printing paper delivering drum I, at least a second flexographic printing drum for installing a flexographic plate, a second printing ink drying and curing device and a second printing paper delivering drum II, wherein the at least second flexographic printing drum is provided with a corresponding second ink supply system; the first printing paper delivering drums I and the first printing paper delivering drum II are provided between the first impression drum and the second impression drum; the second printing paper delivering drum I and the second printing paper delivering drum II are provided downstream of the second impression drum in the feeding direction of the sheet; each of the first printing paper delivering drums I, the first printing paper delivering drum II, the second printing paper delivering drum I and the second printing paper delivering drum II is a drum having a temperature control device; a first checking device is respectively provided outside the first printing paper delivering drum I and the first printing paper delivering drum II, and a second checking device is respectively provided outside the second printing paper delivering drum I and the second printing paper delivering drum II both the first checking device and the second checking device are configured to check material or print quality of the printing stock; a paper feeding device is provided at the front end of the first printing unit; a multi-bin paper collecting device is provided at the rear end of the second printing unit;
A temperature adjustment control mechanism is provided inside the drum having the temperature control to enable liquid medium to flow. Said first and second impression drums, said first I, first II, second I and second II printing paper delivering drums, and said first and second flexographic printing drums are arranged such that the sheet of the printing stock successively passes through the first flexographic printing drum and the first impression drum, the first impression drum and the first printing paper delivering drum I, the first printing paper delivering drum I and the first printing paper delivering drum II, the first printing paper delivering drum II and the second impression drum, and the second impression drum and the second flexographic printing drum.
A gripper mechanism for gripping the sheet of the printing stock is installed inside each of the first impression drum, the first printing paper delivering drum I, the first printing paper delivering drum II, the second impression drum, the second printing paper delivering drum I, and the second printing paper delivering drum II.
A temperature adjustment control mechanism for flowing of the liquid medium is provided inside the first impression drum and the second impression drum.
The present invention has the following advantages. In the present invention, two units (four printing paper feeding drums in total) are installed between and behind components where the two impression drums are located, respectively. These printing paper feeding drums are drums having a temperature control and a quality checking device. The printing paper feed drums are provided with the temperature control function, which can reduce the thermal accumulation of the printed product, to create conditions for print quality control and neat collection. The printing paper feeding drums are provided with the quality checking device to conduct different quality checking or optical characteristics checking on two sides of the printed product based on the requirements of quality checking, such that the scope of checking is enlarged. At the same time, the checking device is provided between the components, which provides a condition for the timely feedback of the printing quality of the printed product. For example, after the first side of the printing is completed, when it is found during checking that there are quality problems, the present invention can set a timely alarm, shutdown the machine, stop the printing drums or separate collection of printed product and other measures to reduce the unnecessary printing materials and printing stocks waste.

Brief description of the drawings

In order to make the contents of the present invention more easily understood, the present invention will be described in further detail with reference to embodiments in conjunction with the accompanying drawings.

Figure 1 and Figure 2 show an embodiment of the present invention;
Figure 3 is a working flow chart of the present invention;
Figure 4 is a flow chart of an existing double-sided flexographic printing press;
Figure 5 is a schematic representation showing the arrangement of the printing unit drums of the existing double-sided flexographic printing press.

Reference signs in the drawings: 1, the first impression drum; 2, the first printing paper delivering drum I; 3, the first printing paper delivering drum II; 4, the second impression drum; 5, the second printing paper delivering drum I; 6, the second printing paper delivering drum II; 7, the first checking device; 8, the second checking device; 9, a first flexographic printing drum; 10, a first ink supply system; 11, a second flexographic printing drum; 12, a second ink supply system; 13, a first printing ink drying and curing device; 14, a second printing ink drying and curing device; 15, a paper feeding device; 16, a multi-bin paper collecting device; 17, a flexographic printing drum.

Detailed description of the embodiments

As shown in Figure 1, the present invention discloses a sheet-fed flexographic printing press, which includes a first printing unit and a second printing unit for printing both surfaces of sheet of the printing stock respectively. The first printing unit includes first impression drum 1, first printing paper delivering drum I 2, first printing paper delivering drum II 3, second impression drum 4, second printing paper delivering drum I 5 and second printing paper delivering drum II 6. First printing paper delivering drum 12 and first printing paper delivering drum II 3 are provided between first impression drum 1 and second impression drum 4, second printing paper delivering drum I 5 and second printing paper delivering drum II 6 are provided behind second impression drum 4. First printing paper delivering drum I 2, first printing paper delivering drum II 3, second printing paper delivering drum I 5 and second printing paper delivering drum II 6 are provided as drums having a temperature control and a quality checking device. The interior of the drum having the temperature control is provided with a temperature adjustment control mechanism for the liquid medium to flow, and the drum having the quality checking device is a drum in which an optoelectronic device or a camera is mounted. The optoelectronic device or camera is connected to a computer or other analytical equipment, so that the printing quality of the paper can be checked in real time.
In the arrangement of the drums, two (even number) of printing paper feed drums are added between and behind the printing units corresponding to two surfaces of the printed product. On one hand, the paper alternates even times to ensure the two surface printings of the printed product. On the other hand, the problem of thermal accumulation and timely quality control is solved by adding additional temperature control function and print quality checking function on the added printing paper drum.
First checking device 7 is provided at the exterior of first printing paper delivering drum I 2 and first printing paper delivering drum II 3, and second checking device 8 is provided at the exterior of second printing paper delivering drum I 5 and second printing paper delivering drum II 6. Both, first checking device 7 and second checking device 8, are configured to check the material or print quality of the sheet of the printing stock Both, first checking device 7 and second checking device 8, are configured to check the print quality of the sheet of the printing stock First checking device 7 and the second checking device 8 can be a high-speed camera, and the high-speed camera can be connected to a computer to carry out the checking of the printing quality of the printed product.
A gripper mechanism is installed in the interior of each of first impression drum 1, first printing paper delivering drum I 2, first printing paper delivering drum II 3, second impression drum 4, second printing paper delivering drum I 5 and second printing paper delivering drum II 6 for gripping sheet of the printing stock. The present invention is directed to a sheet-fed double-sided flexographic printing press. Thus, the gripper mechanism used to grip sheet of the printing stock is provided at the gap between impression drums, printing paper feed drums and other drums related to paper gripping and transferring.
A temperature adjustment control mechanism for flow of the liquid medium is provided inside first impression drum 1 and second impression drum 4. At least one first flexographic printing drum 9 used for installing the flexographic plate is configured on first impression drum 1. Flexographic printing drum 9 is provided with a corresponding first ink supply system 10. At least one second flexographic printing drum 11 used for installing the flexographic plate is configured on second impression drum 4. Second flexographic printing drum 11 is provided with a corresponding second ink supply system 12. First ink supply system 10 and second ink supply system 12 are an anilox roller ink supply system.
In the present invention, it is possible to carry out flexographic printing on both sides of the printed product. A fast drying and curing type ink is necessary for printing and a corresponding drying and curing device needs to be configured. First printing ink drying and curing device 13 is configured outside of first impression drum 1, and second printing ink drying and curing device 14 is configured outside of second impression drum 4. The fast drying and curing method will cause a certain amount of heat radiation, leading to increase in the temperature of the drums, other components and the printed product. In order to avoid the influence on the components and quality problem of the printed product caused by increase in the temperature, pipelines for flow of the liquid medium are designed inside the first impression drum 1, first printing paper delivering drum 12, first printing paper delivering drum II 3, second impression drum 4, second printing paper delivering drum I 5 and second printing paper delivering drum II 6, the temperature control of the drum and printed product is achieved by controlling the temperature and flow of liquid medium from outside.
Figure 3 is a flow chart of the printing process using the present invention. The flow chart shows the sequential process of double-sided printing, drying and curing, cooling and quality checking of the printing press, respectively. By the printing, drying, cooling and quality checking processes, the problem of thermal accumulation and delayed quality control existing in the double-sided flexographic printing will be well solved.
As shown in Figure 2, the sheet of the printing stock is firstly transferred to first impression drum 1 by the paper entering and feeding drum, and the sheet of the printing stock is successively passed through first flexographic printing drum 9 and flexographic printing drum 17 to complete the two-color overprinting of the first surface of the printed product. Next, the drying and curing of ink is conducted on the first surface by first printing ink drying and curing device 13. Then, the cooling treatment is conducted by first printing paper delivering drum I 2. Then, the printed product is transferred to second impression drum 4 through first printing paper delivering drum II to complete the two-color overprinting of the other surface. Next, the drying and curing of ink is conducted on the other surface by second printing ink drying and curing device 14. After that, the cooling treatment is conducted by second printing paper delivering drum I 5 and second printing paper delivering drum II 6. Finally, the printing is completed and the paper is provided as output. In the process, the two-sided printing are checked and controlled by first checking device 7 and second checking device 8, respectively, to ensure the quality of the printed product. In addition, paper feeding device 15 is provided at the front end of the first printing unit, and multi-bin paper collecting device 16 is provided at the rear end of the second printing unit. It is convenient to print a large amount of paper by setting paper feeding device 15 and multi-bin paper collecting device 16.

Claims

A sheet-fed flexographic printing press, comprising:
a first printing unit and a second printing unit each for printing a side of a sheet of a printing stock, respectively, wherein the second printing unit comprises a second impression drum (4), a second printing paper delivering drum I (5), at least a second flexographic printing drum (11) for installing a flexographic plate, a second printing ink drying and curing device (14), and a second printing paper delivering drum II (6), wherein the at least second flexographic printing drum (11) is provided with a corresponding second ink supply system (12);

the second printing paper delivering drum I (5) and the second printing paper delivering drum II (6) are provided downstream of the second impression drum (4) in the feeding direction of the sheet;

the first printing unit comprises a first impression drum (1), at least a first flexographic printing drum (9) for installing a flexographic plate, a first printing ink drying and curing device (13), wherein the at least flexographic printing drum (9) is provided with a corresponding first ink supply system (10);

a paper feeding device (15) is provided at the front end of the first printing unit;

a multi-bin paper collecting device (16) is provided at the rear end of the second printing unit; characterized in that the first printing unit comprises a first printing paper delivering drum I (2) and a first printing paper delivering drum II (3);

the first printing paper delivering drum I (2) and the first printing paper delivering drum II (3) are provided between the first impression drum (1) and the second impression drum (4);

each of the first printing paper delivering drums I (2), the first printing paper delivering drum II (3), the second printing paper delivering drum I (5) and the second printing paper delivering drum II (6) is a drum having a temperature control device;

a first checking device (7) is respectively provided outside the first printing paper delivering drum I (2) and the first printing paper delivering drum II (3), and a second checking device (8) is respectively provided outside the second printing paper delivering drum I (5) and the second printing paper delivering drum II (6) both the first checking device (7) and the second checking device (8) are configured to check material or print quality of the printing stock;
a temperature adjustment control mechanism enabling liquid medium to flow is provided inside each of the first impression drum (1) and the second impression drum (4);

a temperature adjustment control mechanism configured to reduce a thermal accumulation of the sheet is provided inside each of said first I (2), first II (3), second I (5) and second II (6) printing paper delivering drums having the temperature adjustment control device to enable liquid medium to flow,

said first (1) and second (4) impression drums, said first I (2), first II (3), second I (5) and second II (6) printing paper delivering drums, and said at least first (9) and at least second (11) flexographic printing drums are arranged such that the sheet of the printing stock successively passes through the at least first flexographic printing drum (9) and the first impression drum (1), the first impression drum (1) and the first printing paper delivering drum I (2), the first printing paper delivering drum I (2) and the first printing paper delivering drum II (3), the first printing paper delivering drum II (3) and the second impression drum (4), and the second impression drum (4) and the at least second flexographic printing drum (11) whereby a gripper mechanism for gripping the sheet of the printing stock is installed inside each of the first impression drum (1), the first printing paper delivering drum I (2), the first printing paper delivering drum II (3), the second impression drum (4), the second printing paper delivering drum I (5), and the second printing paper delivering drum II (6).