CN211000534U - Machines for printing substrate sheets with ink - Google Patents

Abstract

A machine for printing substrate sheets with ink, comprising: a conveying path (4); a first conveying roller (4a); a second conveying roller (4b); at least one inkjet print head (3); a blowing device (5) which loads at least one section of the second conveying drum (4b) with temperature-regulated blowing air (6, 6b); a third conveying drum (4c); and at least A dryer (3') that generates heat. The blowing device (5) comprises at least one air guide plate (5a), which guides the temperature-regulated blowing air to the first transport cylinder (4a) and thus to the printing material sheet (2) there. ). The invention advantageously enables adequate temperature control of machine components and printing material, and in particular only insignificant temperature differences between the conveying drum and the conveyed printing material and a uniform temperature distribution in the printing material.

Description

Machines for printing substrate sheets with ink

technical field

The utility model relates to a machine for printing printing material sheets with ink.

The invention belongs to the technical field of the image industry and there in particular to the field of industrial inkjet printing (Inkjet) on flat substrates, ie in particular the application of liquid inks to sheet form, preferably from paper, thick Areas on and dry on substrates made of cardboard, cardboard or plastic.

Background technique

In the known DOD inkjet printing method (drop-on-demand), the liquid ink is applied by producing a printed image on a flat printing material with individually controllable nozzles Depending on the image to be printed, the inkjet print head (abbreviation: head) preferably produces the smallest ink droplets in the picoliter range and transfers them contactlessly as printing dots onto the printing material. The nozzle can be actuated by means of piezoelectric actuators.

In so-called water-based inkjet printing, the liquid ink contains a portion of water for receiving colorants, especially pigments. The colorant is delivered to the substrate by means of droplets produced by the ink jet print head. Subsequently, the water, which is also transferred here, is removed from the printing material, preferably by thermal drying, for example by irradiation with infrared radiation.

Adequate drying of water-based inks on a moving printing material requires a dryer for generating a high spatial power density, which evaporates all excess water during the short residence time of the printing material in the area of effect of the dryer . Therefore, high energy is input into the machine in the area of the dryer. Consequently, this can lead to undesired thermal expansion of machine parts, eg side walls or drums.

DE 11 2015 004 269 T5 discloses an image generation device. A gas compressor is used to cool the impression cylinder. The gas compressor is arranged below the impression cylinder and blows cooled air towards the impression cylinder.

An inkjet printer for industrial production, known under the product name "Primefire" and developed by Heidelberger Druckmaschinen AG, Deutschland, prints paper sheets with water-based inkjet. The machine comprises seven successive printing stations belonging to the so-called "jet cylinders", which transfer the colors CMYK (cyan, magenta, yellow and black) and OGV (orange, green, violet) with the printing heads onto paper. The applied ink is dried by using an IR dryer. In this machine, the temperature control of the jet cylinders is achieved by means of jet air from above, from which the print heads are also pressed onto the paper.

In this prior art, however, the problem of insufficient cooling can occur, especially when the machine is stopped, ie when the sheet transport is stopped.

Utility model content

Therefore, the object of the present invention is to propose an improvement with respect to the prior art, which enables adequate temperature control of the machine components and the printing material, especially when the machine is stopped, and which enables, in particular, conveyance There are only insignificant temperature differences between the cylinder and the conveyed printing material and a uniform temperature distribution in the printing material.

According to the invention, this task is solved by the machine according to the invention.

Advantageous and therefore preferred developments of the invention emerge from the description and the drawings.

Substrates may include the following materials: paper, cardboard, cardboard (also known as corrugated cardboard), or plastic, respectively, as sheets.

The transport cylinder may comprise the following components: a rotating or rotatable cylinder which transports the sheet of printing material, in particular a cylinder with a circular cross-section or a narrowing of a circular cross-section, preferably an impression cylinder Or the so-called transfer roller (Umführtrommel).

A machine according to the invention for printing a sheet of printing material with ink comprises: a conveying path for the sheet of printing material, a first conveying cylinder of the conveying path, a conveying cylinder arranged downstream of the first conveying cylinder in the conveying path A second conveying cylinder, at least one inkjet print head on the periphery of the second conveying cylinder, a blowing device that impinges at least one section of the second conveying cylinder with temperature-controlled blowing air, are arranged in the conveying path A third conveying roller downstream of the second conveying roller, and at least one heat-generating dryer, characterized in that the blowing device comprises at least one air guide plate which guides the temperature-regulated blowing air to the first The rollers are transported and thus guided to the sheet of printing material there.

The present invention advantageously enables adequate temperature control of machine components (for example, the transport cylinder) and the printing material (especially when the machine is stopped) and, in particular (in order to generate a high printing quality), the transport cylinder and the transported printing material. Only insignificant temperature differences and a uniform temperature distribution in the substrate.

According to the invention, the temperature of the second conveying cylinder and the printing material can be adjusted up to a few degrees Celsius.

For this purpose, the invention provides at least one air guide plate, which guides the tempered, in particular cooled, blowing air to the first transport cylinder and thus to the printing material sheet there. Therefore, the blowing air of the blowing device not only regulates the temperature, in particular cools the second conveying cylinder, but also cools the printing material before the printing material on which the printing material is placed during printing. In this way, the temperature difference between the second transport cylinder and the printing material supplied to said second transport cylinder can be kept sufficiently small. In this case, the guide plate is used as a simple means, which preferably guides the excess blowing air of the blowing device to the first transport cylinder and thus to the sheet of printing material there. In this way (in addition to the function of adjusting the temperature of the second transport drum) the blowing device has another function, namely, also adjusting the temperature of the sheets. This guide takes up little installation space and can therefore be arranged in the machine in a simple manner, preferably close to the blowing device, and preferably below the first conveyor roller or below the sheet guide of the first conveyor roller.

A preferred development of the invention can be characterized in that the machine comprises a blowing box which is arranged substantially below the second conveying drum and which discharges temperature-regulated blowing air substantially upwards. The blow box preferably flows the cooled blow air directly to the second conveyor drum. It is advantageous here that the blow box is substantially opposite the print head with respect to the second transport cylinder (head "up", blow box "below") and thus has sufficient structure for the blow box space. The head also does not interfere with the blowing air flow. The blowing box (its size, its shape and/or its structure) can influence the blowing air distribution in such a way that the blowing air distribution is substantially as uniform as possible over the width of the machine or at least the second conveyor drum.

The flow rate of the blowing air is chosen to be so low that disturbing influences on smooth sheet running can be excluded and as little contaminated ambient air is blown together as possible. Here, the volume flow is chosen to be so large that sufficient temperature control is achieved.

A preferred development of the present invention can be characterized in that the blow box is connected to a cooler, a blower and a filter.

A preferred development of the present invention can be characterized in that the air guide is arranged substantially below the first conveying roller or below the sheet guide associated with the first conveying roller. In this way, it can be achieved by means of simple, cost-effective and space-saving components that the excess blowing air of the blowing device reaches the first transport drum or its sheet guide. Furthermore, in this way the second transport cylinder and the sheet are loaded with blowing air of the same temperature.

A preferred development of the invention can be characterized in that the blowing device has at least one further air guide plate, which guides the temperature-regulated blowing air to the third conveying roller.

A preferred development of the invention can be characterized in that the further air guide is arranged substantially below the third transport drum or under a further sheet guide associated with the third transport drum. In this way, it can be achieved by means of simple, cost-effective and space-saving components that the excess blowing air of the blowing device reaches the third transport drum or its sheet guide.

A preferred development of the invention can be characterized in that the machine comprises an air knife, which blows temperature-regulated blowing air into the outlet wedge between the second conveyor roller and the third conveyor roller. In this way it can be achieved that (especially when the machine is stopped) the residual heat of the dryer does not or only to an insignificant degree reach the second conveyor drum.

A preferred development of the invention can be characterized in that the air knife is supplied with blowing air, wherein the blowing air has a first volume flow during printing operation of the machine and a relative first volume during shutdown of the machine A higher second volume flow flows. In this way it can be achieved that the residual heat of the dryer does not, or only to an insignificant degree, lead to local heating and thermal expansion of the second conveyor drum during machine standstills. Preferably, the air knife generates an air curtain with such a high volume flow and such a low flow rate that disturbed heat transfer from the dryer to the second transport drum is prevented, so that sheet running is not disturbed and/or contaminants from the environment will not be sprayed together. At the same time, blow air generation by the blow box can be reduced or interrupted in order to prevent dust from being blown upwards to the print head.

A preferred development of the present invention can be characterized in that the blowing box together with the air guide plate and the other air guide plate form a shielding portion relative to the bottom of the machine, the shielding portion shielding dust. Dust, especially paper dust, builds up on the bottom of the machine over time. The developed solution of the present invention shields the bottom, so that dust can be effectively prevented from being blown up to the cylinder or even to the highly sensitive printing head.

A preferred development of the invention can be characterized in that the machine is a 7-color inkjet printer, which prints a water-based ink by means of a plurality of inkjet print heads and which heats the ink by means of at least one dryer dry.

The generation of the blowing air (of the blow box and/or of the air knife) can preferably take place in a controlled manner, for example according to the following table:

The features of the present invention, of the development of the present invention and of the embodiments of the present invention can also be arbitrarily combined with each other to form an advantageous development of the present invention. Furthermore, developments of the invention may have individual features or combinations of features (disclosed in the above paragraph "Technical Field of the Invention").

Description of drawings

The present invention and its preferred development solutions are further described below with reference to the accompanying drawings according to preferred embodiments. The attached figure shows:

Figure 1 A machine according to the present invention.

Detailed ways

FIG. 1 shows a preferred embodiment of a machine 1 according to the invention for printing a sheet 2 of printing material with ink. The ink is transferred to the sheet of printing material by means of a plurality of inkjet print heads 3 and dried by means of a dryer 3' (or dryers). The inks are water-based inks or inks such as those of Cyanogen, Magenta, Yellow (CMY) and Orange, Green, Violet (OGV) and Black (K). The dryer is a thermal dryer, preferably an infrared dryer and/or a hot air dryer.

The machine 1 includes a transport path 4 for the sheets 2 of printing material. The conveying path has a plurality of conveying rollers which are successively conveyed sheets respectively, and at least one first conveying roller 4a, second conveying roller 4b and third conveying roller 4c. The conveyor rollers 4a and 4c are double as large, whereas the conveyor roller 4b is four times as large, ie it has four sections that guide the sheets. The transport cylinder 4b is also referred to as a "jet cylinder" because the print head 3 is assigned to it. The sheet transport takes place essentially in the transport direction 15 through the machine 1 .

A blowing device 5 is arranged below the second conveying roller 4b for temperature control, in particular for cooling the second conveying roller 4b. The blowing device comprises a blowing box 5b which generates temperature-regulated blowing air 6 and which is directed as blowing air 6b towards the second conveyor roller 4b (preferably upwards in direction 16 ). ) blow. The blow box 5b is connected to a cooler 7 for air (preferably a water-cooled cooler), a blower 8 for air and an air filter 9 . The blow box can extend substantially over the entire width of the spray drum 4b. The box is preferably closed on the sides and opens upwards or is provided with blowing openings or blowing nozzles.

Furthermore, the blowing device 5 includes an air guide plate 5a. This air guide is arranged in the conveying direction 15 in front of the blow box 5b. The excess blowing air 6 is guided by the air guide 5a as blowing air 6a to the first conveying roller 4a. There, the blowing air 6a is sucked in by the ventilator of the sheet guide 10a and is blown against the first transport cylinder 4a or the printing material sheet 2 guided by it in order to guide the sheet. The air guide 5a may be curved or, as shown, single or multiple folds and in this way have a corresponding profile to the sheet guide 10a. The air guide can be fitted on the spray box and can extend substantially over the entire width of the spray drum 4b. Together with the sheet guide, the air guide forms an air channel which extends substantially opposite the conveying direction 15 . The air guide can be made of sheet material.

Furthermore, the blowing device 5 has an additional air guide 5c. This additional air guide guides the excess blowing air 6 as blowing air 6c to the additional sheet guide 10c. The blower air 6c of the sheet guide draws in the blowing air 6c and blows it towards the third transport cylinder 4c or the printing material sheet 2 guided by it in order to guide the sheet. The air guide 5c can likewise be curved or, as shown, single or multiple folds and in this way have a corresponding contour to the sheet guide 10c. The air guide can be fitted on the spray box and can extend substantially over the entire width of the spray drum 4b. Together with the sheet guide, the air guide forms an air channel which extends substantially in the conveying direction 15 . The air guide can be made of sheet material.

Furthermore, the machine 1 comprises an air knife 11 which blows the blowing air 6d towards the outlet wedge 12 . The air knife is preferably arranged above the third conveying drum 4c. The air knife can be connected with cooler 7, blower 8 and filter 9. Alternatively, the air knife can be connected to the blow box 5b.

Furthermore, the blowing device 5 constitutes a shield 13 with respect to the bottom 14 of the machine 1 . In this way the paper dust on the bottom is prevented from being sucked up by the sheet guides 10 a and 10 c or their ventilators and blown upwards to the highly sensitive print head 3 . The shields thus constructed preferably extend below the three rollers 4a, 4b and 4c, or at least below the transfer position between the rollers 4b and the rollers 4a and 4b and between the rollers 4b and 4c.

The blowing air supply is preferably controlled. For this purpose, a control device can be provided.

List of reference signs

1 machine

2 sheets of media

3 Inkjet print heads

3’ dryer

4 conveying path

4a First conveying roller

4b Second conveying roller

4c Third conveyor roller

5 Blowing device

5a Air guide

5b Blow Box

5c Additional air guides

6 blow air

6a-6d Blow air

7 Cooler

8 Blower

9 Filters

10a Sheet guide

10c Additional sheet guides

11 Air Knife

12 Exit wedge

13 Shield

14 Bottom

15 Conveying direction

16 up direction

Claims (10)

1. A machine for printing a sheet of substrate material with ink, comprising:

a transport path (4) for a sheet (2) of printing material,

a first transport roller (4a) of the transport path,

a second conveyor roller (4b) arranged downstream of the first conveyor roller in the conveying path,

at least one inkjet printing head (3) on the periphery of the second transport drum,

a blowing device (5) which applies tempered blowing air to at least one section of the second conveyor drum (4b),

a third transport drum (4c) arranged downstream of the second transport drum in the transport path, and

at least one dryer (3') generating thermal energy,

it is characterized in that the preparation method is characterized in that,

the blowing device (5) comprises at least one air guide plate which guides the tempered blowing air to the first transport cylinder (4a) and thus to the printing material sheet (2) located there.

2. The machine of claim 1, wherein the machine is,

it is characterized in that the preparation method is characterized in that,

the machine comprises a blowing box (5b) which is arranged below the second conveyor drum (4b) and which outputs upwardly tempered blowing air.

3. The machine of claim 2, wherein the machine further comprises a drive motor,

it is characterized in that the preparation method is characterized in that,

the blowing box (5b) is connected with a cooler (7), a blower (8) and a filter (9).

4. The machine of any one of claims 1 to 3,

it is characterized in that the preparation method is characterized in that,

the air guide plate is arranged below the first conveying roller (4a) or below a sheet guide plate associated with the first conveying roller.

5. The machine of claim 2 or 3,

it is characterized in that the preparation method is characterized in that,

the blowing device (5) has at least one further air guide plate which directs the temperature-controlled blowing air to the third conveyor drum (4 c).

6. The machine of claim 5, wherein the first and second rollers are mounted on a single frame,

it is characterized in that the preparation method is characterized in that,

the further air guide plate is arranged below the third transport cylinder (4c) or below a further sheet guide plate associated with the third transport cylinder.

7. The machine of any one of claims 1 to 3,

it is characterized in that the preparation method is characterized in that,

the machine comprises an air knife (11) blowing tempered blowing air into an exit wedge (12) between the second transport drum (4b) and the third transport drum (4 c).

8. The machine of claim 7, wherein the first and second rollers are mounted on a single carriage,

it is characterized in that the preparation method is characterized in that,

the air knives (11) are supplied with blowing air, wherein the blowing air has a first volume flow during a printing operation of the machine (1) and a second volume flow which is higher relative to the first volume flow during a standstill of the machine.

9. The machine of claim 5, wherein the first and second rollers are mounted on a single frame,

it is characterized in that the preparation method is characterized in that,

the blowing box (5b) together with the air guide plate and the further air guide plate forms a shield (13) with respect to a bottom (14) of the machine (1), which shield shields against dust.

10. The machine of any one of claims 1 to 3,

it is characterized in that the preparation method is characterized in that,

the machine (1) is a 7-color inkjet printer which prints water-based inks by means of a plurality of inkjet print heads (3) and the inks are thermally dried by means of at least one dryer (3').

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