DE9421763U1 - Sheet-fed rotary printing machine - Google Patents

Description

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"uniVuur"

Sheet-fed rotary printing press

The invention relates to a sheet-processing rotary printing machine with an application device by means of which spacer particles provided in a storage container can be removed and applied to the sheets.

Such a machine is known from DE 21 51 185 B2. The storage container provided here is filled with a powder.

The aim of applying the powder to the printed sheet is to protect the printed image from damage that can occur, in particular, in the delivery of a sheet-fed printing machine when a delivery stack is formed.

However, the use of powder materials also leads to adverse consequences. For example, the well-known sheet-fed printing machine is contaminated by the powder used, as this naturally does not only reach the surface of the printed sheet, but is distributed in a printing unit in the form of a cloud of powder. The applied powder can also come off the printed sheet again during a repeated printing process and thus also lead to contamination of the printing units of a sheet-fed printing machine and consequently to an increased amount of waste.

From the publication JP Hei 5-85074 A it is known to coat a printed sheet with an aqueous emulsion of wax and an alcohol-fatty acid ester. This emulsion is applied evenly and evenly to the entire surface of the previously printed sheet. The disadvantage here is that, particularly for large-format printed sheets, considerable amounts of the emulsion mentioned are required and that when stacking such flatly coated sheets,

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Printed sheets cannot form air cushions between the individual sheets. This makes it particularly difficult to form a stack with precise edges.

Accordingly, the object of the present invention is to provide a sheet-processing rotary printing press which does not suffer from the aforementioned disadvantages and which in particular enables a good and damage-free alignment of a stack of printed sheets.

This object is achieved with the rotary printing machine specified in claim 1.

The solution according to the invention advantageously creates the prerequisite for the spacer particles to be applied in a point-by-point manner. On the one hand, this saves spacer material, and on the other hand, the spacer particles applied in a point-by-point manner ensure that air cushions form between the individual sheets when the sheets are stacked, which ensure that the stack can be easily aligned without damaging the printed image on a particular sheet and that the same can be easily processed further.

A further advantage is that it is possible to fix the spacer particles to the sheet. To do this, the suspension in the storage container is formed with an adhesive dissolved in water.

In a first variant of a rotary printing machine according to the invention, the application device comprises a spray device that sprays the suspension. This can be directed onto the outer surface of a printing unit cylinder or directly onto a respective sheet.

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In preferred embodiments, the spray device comprises two limiting rollers which are essentially parallel to one another and are arranged in front of a spray nozzle and which limit a spray jet emerging from the spray nozzle by means of a gap formed between them, and a cleaning device associated with the two limiting rollers which removes any residues of the suspension adhering to the limiting rollers and returns them to the storage container designed as a collecting container.

Furthermore, pivotable spray nozzles are preferably provided, whereby the discharge of the suspension can be interrupted by pivoting the spray nozzles.

In a further embodiment, it is provided that the limiting rollers of the spray device are arranged so as to be adjustable in order to change the gap and close it.

In a second variant of the subject matter of the invention, the application device comprises, in a manner known per se, a roller arrangement in the form of mutually contacting rollers and a printing unit cylinder working therewith, whereby the roller arrangement has a first roller in the form of a receiving roller immersed in the suspension and, in a manner known per se, a last roller in the form of an application roller working with the printing unit cylinder. At least one of the outer surfaces of the rollers and the printing unit cylinder is provided with a structure by means of which a portion of the spacer particles contained in the suspension can be distributed at specific points over the respective sheet.

In one embodiment of this variant, it is preferably provided that the printing unit cylinder working together with the form roller is represented by a printing cylinder,

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and that its outer surface has spherical cap-shaped elevations and depressions between them, which are dimensioned such that at least one spacer particle can be accommodated therein.

In another preferred embodiment, the structure is provided in the outer surface of the application roller and is formed in the form of cups adapted to the size of the spacer particles or at least grooves running essentially in the circumferential direction of the outer surface. In this case, the printing cylinder working together with the application roller can be represented by a printing cylinder or a rubber blanket cylinder.

In a further preferred embodiment, the application device has an intermediate roller arranged between the receiving roller and the application roller, wherein the structure is provided in at least one of the outer surfaces of the printing unit cylinder, the application roller and the intermediate roller. In this embodiment, too, the application roller can be assigned to a printing cylinder and preferably its outer surface can be provided with the structure.

In a preferred embodiment, in the case of the application device provided with the intermediate roller, the application roller is assigned to a printing cylinder or a rubber blanket cylinder and the structure is formed in the outer surfaces of the application roller or the intermediate roller by means of cups adapted to the size of the spacer particles or at least grooves running essentially in the circumferential direction of the outer surface.

The adaptation of the cups to the size of the spacer particles is carried out in a particularly advantageous manner in such a way that each cup is dimensioned so that it can accommodate just one spacer particle.

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In this way, a desired distribution of the spacer particles transferred to the sheet can be achieved directly by the distribution of the cells.

If the size of the spacer particles I is approximately 5 to 30 micrometers, this distribution is preferably selected so that the spacer particles are randomly applied to the sheet at an average distance of 50 to 400 micrometers from one another, such that there is at least an almost equal number of spacer particles on identical partial areas of the surface of the sheet. The average distance selected from the specified range of 50 to 30 micrometers depends on the desired coverage density of the spacer particles I depending on the print image in question, the consistency of the colors used to create it, and the nature of the printing medium used.

Regardless of which of the lateral surfaces the structure is provided in, it is furthermore preferably provided that the lateral surface is designed to be hydrophobic and that the structure has recesses with a hydrophilic surface provided for receiving the spacer particles.

In a further embodiment, it is preferably provided that the take-up roller has an elastic outer surface, while a further embodiment, which is particularly advantageous with regard to regulating the average mutual distance of the spacer particles, is characterized by a difference in the peripheral speeds of two rollers of the application device that are in contact with each other.

Based on a description of several Embodiments with reference to the attached The invention is described in more detail below with reference to the figures.

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Show: Fig. 1 a diagram of a part of a printing machine

for printing sheets with an application device for spacer particles assigned to a printing unit cylinder,

Fig. 2a a greatly enlarged

Part of a printing cylinder in longitudinal section with a structure in the mantle surface,

Fig. 2b a section corresponding to Fig. 2a in the Cross section, in connection with an arch, Fig. 3a and 3b schematic representations of a part of the

Printing machine, each application device being arranged differently,

Fig. 4a and 4b schematically show the interaction of a Pick-up roller and an application roller, Fig. 5a a greatly enlarged longitudinal section of a

Part of a roller of an application device for the spacer material with depressions in the surface,

Fig. 5b a diagram of a part of the printing machine

to illustrate the arrangement of an application device for the spacer material,

Fig. 6 schematically a spray device

for applying the spacer material,

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Fig. 7a and 7b schematically show the spray device according to

Figure 6 to illustrate the interruption of a spray jet emitted by the spray device,

Fig. 8a and 8b each show a diagram of a part of the

Printing machine with differently arranged spray devices as shown in Figure 6.

Figure 1 shows a printing unit 25 and a delivery unit 21 connected to it. The printing unit 25 comprises a printing cylinder 12/a blanket cylinder 15 and a plate cylinder 16, around which an inking unit 18 and, if the printing machine is operated using the wet offset process, a dampening unit 17 are grouped. A respective sheet 1 is fed to the printing cylinder 12 by means of a sheet guide cylinder 19. The printing cylinder 12 is assigned an application device 11 with an application roller 13 and a take-up roller 14, which takes up an aqueous suspension provided in a storage container 24, which contains spacer particles 2 and, in the present example, a water-soluble adhesive.

In order to apply the spacer particles 2 to the sheet 1 in a point-by-point manner, in a first embodiment of the application device 11 with an application roller 13 with a smooth outer surface, the printing cylinder 12 according to Figure 2a has a outer surface with spherical dome-shaped elevations and depressions 31 between them, by means of which the spacer particles 2 contained in the suspension are forced into the desired distribution. When the printing cylinder 12 comes into contact with the paper, the layer thickness of the liquid portion of the suspension in the non-depressed areas of the outer surface of the printing cylinder 12 is too small.

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for a transfer of an excessive amount of the dissolved adhesive to the paper by liquid splitting. The spacer particles 2 in the recesses 31 adhere to the paper by the water-soluble adhesive. When the spacer particles 2 are released from the recesses 31 as a result of the sheet 1 being peeled off the printing cylinder 12, generally only a part of the liquid portion 6 of the suspension present in the recesses 31 is taken along by the respective spacer particle 2 in the form of a covering thereof, as is shown schematically in Figure 2b. However, no disadvantages arise from the part of the liquid portion 6 remaining in the recess 31.

The application roller 13 can either have the diameter of the printing cylinder 12 and a corresponding cutout for the grippers of the printing cylinder 12. However, it can also be designed with a smaller diameter and, for example, be switched on and off using a cam control in order to avoid the grippers of the printing cylinder 12 when switched off.

The assignment of the application device 11 to the printing cylinder 12 explained above means that the spacer particles 2 are not applied to the printed side of the sheet 1 but to its back. However, this has no influence on the function of the spacer particles 2 as spacers.

Figures 3a and 3b each show a diagram of a part of a printing machine which essentially corresponds to that shown in Figure 1. In contrast to the embodiment shown in Figure 1, the application device 11 is not assigned to the printing cylinder 12 but to the blanket cylinder 15, whereby it is placed in relation to the latter according to Figure 3a in such a way that first ink and then the spacer particles 2 are applied to the

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Blanket cylinder 15. This order is reversed in the arrangement according to Fig. 3b.

Since the rubber blanket cylinder 15 has a substantially smooth surface, in the embodiments according to Fig. 3a and 3b the outer surface of the application roller 13 of the application device 11 is provided with a specific surface structure in order to apply the spacer particles 2 to the paper in a point-by-point manner and with the desired distribution already explained by means of a rubber blanket stretched over the rubber blanket cylinder 15.

In an advantageous embodiment, the outer surface of the application roller 13 is provided with cups 27. These cups 27 are dimensioned such that just one spacer particle 2 can be picked up with a little water-soluble adhesive. The surfaces of the cups 27 are preferably hydrophilic, while the remaining surface areas of the outer surface of the application roller 13, which come into contact with the rubber blanket of the rubber blanket cylinder 15, preferably have a hydrophobic property, for example through a special coating. As already described in connection with Figure 1, the spacer particles 2 or the suspension are removed from the storage container 24 by means of the pick-up roller 14 and fed to the application roller 13. Supported by the described acceptance behavior of the surface areas of the application roller 13, the cups 27 fill with the spacer particles 2 or with the suspension, while the non-recessed surface areas of the application roller 13 remain uninvolved in the transfer of the spacer particles 2. The desired distribution of the spacer particles 2 is determined by a corresponding distribution of the cups 27 in the surface area of the application roller 13.

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Preferably, the receiving roller 14 is provided with an elastic outer surface. The contact pressure between the application roller 13 and the receiving roller 14 is set so that when the cup is filled without spacer particles 2, most of the liquid is squeezed out of the cup. This process is illustrated schematically in Figures 4a and 4b. Figure 4a shows the case of a cup being filled without spacer particles 2. By choosing an elastic outer surface for the receiving roller 14, the area of the outer surface of the receiving roller 14 lying above the cup 27 of the application roller 13 arches into the cup 27. The degree of arching depends on the elasticity of the outer surface and on the contact pressure between the application roller 13 and the receiving roller 14. This curvature causes any liquid in the cup 27, in particular glue dissolved in water, to be squeezed out if there is no spacer particle 2 in the cup 27. This prevents a significant amount of glue dissolved in water from being transferred without spacer particles 2, which would visually impair the printed product.

Figure 4b, on the other hand, shows the case in which a spacer particle 2 is located in one of the cups 27 of the application roller 13. The spacer particle 2 ensures that the elastic surface of the receiving roller 14 curves towards its axis, as is schematically indicated in the figure. When selecting the contact pressure or the material for forming the elastic surface of the receiving roller 14, care must be taken to ensure that, with the preferred use of spacer particles 2 in the form of wax particles, a respective wax particle 2 does not deform excessively when it comes into contact with the application roller 13.

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In order to facilitate the operational filling of the cups 27 with a respective spacer particle I 2, the drive of the two rollers 13, 14 can be designed in such a way that there is preferably a low relative speed between these two rollers, whereby the relative speed can be changed. The advantage of this is that the spacer particles I 2 can more easily get into the cups 27 due to the friction between the two roller shell surfaces.

The application device 11' shown in Figure 5b is slightly modified compared to the application device described above. The suspension taken up by the take-up roller 14 is not transferred directly to the application roller 13, but first to an intermediate roller 30, from which it is then passed on to the application roller 13.

Instead of a surface structure formed by means of the cups 27, the intermediate roller 30 - like the application roller 13 - can have grooves or flutes 32 running in the circumferential direction of the surface or in a direction inclined to the circumferential direction, as is shown schematically in Figure 5a. The way in which the spacer particles 2 are picked up and passed on to the application roller 13 or to the blanket cylinder 15 essentially corresponds to that of the surface provided with cups 27. The desired distribution of the spacer particles 2 is achieved by a suitable choice of the distances between the flutes 32 and a circumferential speed of the intermediate roller 30 that may then differ from that of the application roller. If, for example, the application roller 13 has the circumferential speed of the blanket cylinder 15 and the intermediate roller 30 has a lower circumferential speed, then the individual grooves 32 of the intermediate roller

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Lying spacer particles 2 are transferred to the application roller 13 at a distance _which is larger than a distance between the spacer particles 2 located in the grooves 32.

As already mentioned above, the application device 11 can, for example, also be located in front of the plate cylinder 16 or be assigned to the printing cylinder 12.

In order to achieve the desired distribution of the spacer particles 2, a surface structure formed by means of depressions 31 in the form of valleys between spherical dome-shaped elevations, cups 27 or grooves 32 is basically only required on one of the dumbbell surfaces involved in the transfer of the spacer particles 2. However, it can be quite advantageous if on the way of the spacer particles 2 from the storage container 24 to the outer surface of the printing cylinder 12 or the blanket cylinder 15, two outer surfaces provided with a respective surface structure follow one another, such as, for example, on the way to the blanket cylinder 15, a surface of the intermediate roller 30 provided with the grooves 32 and a surface of the application roller 13 provided with the cups 27 or also a surface of the application roller 13 provided with grooves 32, the grooves of the intermediate roller 30 and the application roller 13 having different inclinations with respect to the respective roller longitudinal axis, or such as, for example, on the way to the printing cylinder 12, a surface of the application roller 13 provided with the grooves 32 and a surface of the depressions 31 in the form of the valleys between the spherical cap-shaped elevations provided surface of the pressure cylinder 12.

In one variant, the order of the Spacer particles 2 instead of using the application roller

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the application device 11 or 11 ¹ by means of a spray device 40 which sprays the suspension filled into a storage container 46 thereof and can be arranged in the printing machine such that the sheet 1 itself or a printing cylinder 12 in contact with it is sprayed.

In the present case, such a spray device comprises nozzles 41/ to which compressed air is supplied via a corresponding compressed air line 48 and the suspension is supplied via a spray line 49. The suspension supplied via the spray line 49 is sucked out of a storage container 46 filled with it by means of a pump 47. To limit a spray jet produced at a respective nozzle 41, a limiting device formed by two limiting rollers 42, 43 is provided, as is shown in particular in Figure 6. The two limiting rollers 42, 43 are arranged in such a way that a gap is formed between them through which part of the spray jet can pass. In order to prevent residues of the suspension deposited on the outer surfaces of the limiting rollers 42 and 43 from clogging the gap, the two limiting rollers 42, 43 are rotated and scraped off. The direction of rotation is selected so that the two outer surfaces in the area of the gap rotate in the opposite direction to the spray direction.

The scraping is carried out by means of a cleaning device consisting of scrapers 44 and 45, which returns scraped-off residues of the suspension into the storage container 46 designed as a collecting container.

The amount of suspension passing through the gap between the limiting rollers 42 and 43 can be determined by the setting of spray parameters, such as the amount of compressed air or the amount of suspension fed to the nozzle, by the width of the said

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The gap can be controlled. For this purpose, the limiting rollers 42/43 are arranged so that they can be adjusted relative to one another. In addition to a parallel displacement of the two limiting rollers 42 and 43 relative to one another, which results in a constant width of the gap over the entire length of the limiting rollers 42 and 43, it is also conceivable to set a different width of the gap across the width of the printing machine by a corresponding displacement of one of the limiting rollers 42 and 43. To switch off or interrupt the application of the suspension to a target surface, in addition to switching off the pump 47 or the compressed air 48, there is the option shown in Figure 7a of pivoting the nozzle 41 so that the spray jet emitted by it does not hit the gap. In this case, however, it is expediently ensured that the spray jet reaches the storage container 46. In the example shown in Figure 6, this is achieved by the nozzle 41 being located inside the storage container 46 and, after pivoting, being directed, for example, towards a side wall of the same. Another possibility is to close the gap formed by the two limiting rollers 42, 43 by moving them towards each other, as shown schematically in Figure 7b.

By interrupting the spray jet accordingly, it is possible in particular to prevent, for example, spraying of gripper devices by means of which the sheets 1 are transported.

Just as in the case of using the described application device 11, in the case of using spray devices 40 there are various arrangement options for these in the printing machine. Two of these options are shown in Figures 8a and 8b. In Figure 8a the spray device 40 is arranged so that the suspension hits the printed side of the sheet 1. In Figure 8b, on the other hand,

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a spray device 40' according to the functional principle of the spray device 40 is directed at an area of the printing cylinder onto which the sheet 1 is placed as the cylinder continues to rotate. The suspension is thus applied indirectly via the printing cylinder 12 onto the back of the sheet 1. Of course, other conceivable arrangements are also possible.

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Claims (1)

EXPECTATIONS 1. Sheet-processing rotary printing machine with an application device by means of which spacer particles provided in a storage container can be removed and applied to the sheets/ characterized in that the storage container (24,46) is filled with an aqueous suspension containing the spacer particles I (2). 2. Rotary printing machine according to claim 1/ characterized in that the application device comprises a spray device (40) which sprays the suspension. 3. Rotary printing machine according to claim 2, characterized in that the spray device (40) has two limiting rollers (42, 43) which are arranged essentially parallel to one another and upstream of a spray nozzle (41) and which limit a spray jet emerging from the spray nozzle (41) by means of a gap formed between them. 4. Rotary printing machine according to claim 3, characterized in that the limiting rollers (42, 43) are adjustable in the sense of changing the gap and closing it. 5. Rotary printing machine according to claim 3, characterized in that the spray device (40) has a storage container (46) designed as a collecting container and A-1745 .; " _: , j ::·.., 2&;qs\96 a cleaning device (44, 45) is assigned to the limiting rollers (42, 43), which returns residues of the suspension adhering to the limiting rollers (42, 43) into the storage container (46). Rotary printing machine according to claim 2, characterized in that the spray device (40) has pivotably arranged spray nozzles (41) and discharge of the suspension from the spray device (40) can be interrupted by pivoting the spray nozzles (41). Rotary printing machine according to claim 1, characterized in that the application device (11) comprises, in a manner known per se, a roller arrangement in the form of mutually contacting rollers and a printing unit cylinder cooperating therewith, the roller arrangement has a first roller in the form of a receiving roller (14) immersed in the suspension and, in a manner known per se, a last roller in the form of an application roller (13) cooperating with the printing unit cylinder,
and at least one of the lateral surfaces of the rollers and the printing unit cylinder is provided with a structure, by means of which a part of the spacer particles I (2) contained in the suspension can be distributed pointwise over the respective sheet (1). Rotary printing machine according to claim 7, characterized in that the printing unit cylinder cooperating with the application roller (13) is represented by a printing cylinder (12) and that its outer surface has spherical, calot-shaped elevations and intermediate Has recesses (31) which are dimensioned such that at least one spacer particle (2) can be accommodated therein. 9. Rotary printing machine according to claim 7, characterized in that the structure is provided in the outer surface of the application roller (13) and is formed in the form of cups (27) adapted to the size of the spacer particles (2) or at least grooves (32) running essentially in the circumferential direction of the outer surface. 10. Rotary printing machine according to claim 7, characterized in that the application device has an intermediate roller (30) which contacts the application roller (13) on the one hand and the take-up roller (14) on the other hand, and that the structure is provided in at least one of the lateral surfaces of the application roller (13), the intermediate roller (30) and the printing unit cylinder. 11. Rotary printing machine according to claim 7, characterized in that the structure is provided in at least one of the lateral surfaces of the application roller (13) and the intermediate roller (30) and is formed by means of cups (27) adapted to the size of the spacer particles (2) or grooves (32) running at least substantially in the circumferential direction of the lateral surface. 12. Rotary printing machine according to claim 7, characterized in that that the at least one shell surface provided with the structure is hydrophobic and the structure for receiving the spacer particles (2) &Agr;-1745. : : ·: : : *2^:ei.§ - "9 - untruur depressions (wells 27, grooves 32) with a hydrophilic surface. 13. Rotary printing machine according to claim 7, characterized in that the outer surface of the take-up roller (14) is elastically constructed. 14. Rotary printing machine according to claim 7, characterized by a difference in the peripheral speeds of two rollers of the application device (11, 11') that are in contact with one another.