EP1208996B1 - Apparatus for the production of sleeve type printing blankets - Google Patents

Abstract

The apparatus with a carrier sleeve transport unit (11), for producing a sleeve shaped printing cloth, comprises at least one continuous strip casting unit (20) for applying a flowable material which forms a layer (34, 42, 45) on the carrier sleeve. Also claimed is a resultant sleeve shaped printing cloth.

Description

The present invention relates to an apparatus for producing a sleeve-shaped blanket according to the preamble of claim 1.
Furthermore, the present invention relates to a method for producing a sleeve-shaped printing blanket according to the preamble of claim 14.
Furthermore, the present invention relates to a sleeve-shaped printing blanket for offset printing according to the preamble of claim 24 and according to the preamble of claim 31.
Such blankets or such methods are known from EP388 740.
A web offset printing press typically includes a plate cylinder, a blanket cylinder, and a printing cylinder stored for rotation in the machine. The plate cylinder carries a printing plate with an inelastic surface which defines an image to be printed. The blanket cylinder carries a blanket having an elastic surface that contacts the printing plate at a gap between the plate cylinder and the blanket cylinder. A web to be printed moves through a gap between the blanket cylinder and the printing cylinder. Paint is applied to the surface of the printing plate on the plate cylinder. A colored image is picked up by the blanket at the nip between the blanket cylinder and the plate cylinder and transferred to the web by the blanket at the nip between the blanket cylinder and the impression cylinder. The impression cylinder may be another blanket cylinder for printing the opposite side of the web.

A conventional blanket is made as a flat cover. A blanket of this type is mounted on a blanket cylinder by wrapping the blanket around the blanket cylinder and securing the opposite ends of the blanket to the blanket cylinder in an axially extending channel in the blanket cylinder. The adjacent opposite ends of the coating define a channel that extends axially along the blanket. The channel moves with each rotation of the blanket cylinder through the gap between the blanket cylinder and the plate cylinder and also through the gap between the blanket cylinder and the impression cylinder.

As the leading and trailing edges of the channel on the blanket move through the nip between the blanket cylinder and an adjacent cylinder, pressure between the blanket cylinder and the adjacent cylinder is relieved. This is also called a "channel strike". Repeated degradation and buildup of pressure on the channel causes vibration and shock loads in the cylinders and throughout the press. These vibration and shock loads have an adverse effect on print quality. For example, at the time the channel breaks pressure at the nip between the blanket cylinder and the plate cylinder, the web moving through the nip between the blanket cylinder and the impression cylinder may be printed. Any movement of the blanket cylinder or blanket that is caused by the release of pressure at this time may result in smearing of the image transferred from the blanket to the web. Also, when the channel in the blanket moves through the nip between the blanket cylinder and the impression cylinder, an image that is being picked up from the printing plate by the blanket at the other nip may be smeared. The result of the vibration and shock loads caused by the channel in the blanket is an undesirably low limitation on the speed at which printing presses can be operated with acceptable print quality.

To overcome these drawbacks with conventional flat-film blankets, the Applicant of the present invention has developed neckless, sleeve-shaped blankets. These channelless, sleeve-shaped blankets are described for example in US 5,768,990, US 5,553,541, US 5,440,981, US 5,429,048, US 5,323,702 and US 5,304,267.

US 5,304,267 deals with a method of making a canalless, sleeve-shaped blanket. In this patent, a preferred method for making a channelless, sleeve-shaped blanket is described as "coating a compressible thread with a mixture of rubber solution and microspheres and wrapping the coated thread in a helix around the cylindrical sleeve" to form a compressible layer. " Coating an inextensible thread with a rubber solution containing no microspheres and winding the coated thread in a helical line around the underlying compressible layer to form an inextensible layer; and winding an unvulcanized elastomer over the inextensible layer and attaching it with tape "and vulcanizing" the wound structure ... so that the superimposed layers of elastomeric material take the form of a continuous, seamless sleeve ". Other manufacturing methods are also described, including the production of a channelless, sleeve-shaped blanket having a circumferentially inextensible backsheet comprising a continuous piece of plastic film which spirally extends through the elastomeric material of an inextensible layer and around a compressible layer. The plastic film preferably has a width approximately equal to the length of the sleeve-shaped blanket and a thickness of only 0.00254 cm (0.001 inches), so that the narrow seam defined by the 0.00254 cm (0.001 inch) wide edge of the the top layer of the same does not interrupt the smooth, continuous cylindrical contour of an overlying print layer.

DE 197 20 549 A1 describes a method for producing a cylinder carrier by winding a continuous strip on the surface of a carrier mandrel. The strip is unwound from a spool which is mounted so that it can rotate so that the winding angle of the strip can self-align. The strip tension is maintained during the winding process. A pretreatment and coating of the strip with an adhesive takes place between the unwinding and winding of the strip. The pretreatment stations are mounted on a support wall which is installed so that it can rotate in relation to the cylinder surface. The cylindrical carrier sleeve is coated with an integrated layer of plastic material. The carrier sleeve is shown as a fixed length sleeve.

The above-described methods for producing channelless, sleeve-shaped blankets have the disadvantage that they produce blankets serially (i.e., only one at a time) of a fixed axial length. Series production increases production costs and production times and results in production-related differences in the printed blankets produced.

No. 6,257,140 describes channelless, sleeve-shaped blankets which are produced in flow production and cut to the desired length. The sleeve and print layer are formed "continuously" by the sleeve forming station continuing to form an additional portion of the sleeve while the print layer forming station applies the pressure layer to the previously formed portion of the sleeve. To apply different layers winding tapes or crosshead extruder are used.

The invention is therefore based on the object to provide a channelless, sleeve-shaped blanket. The blanket can have different layers.

This object is achieved by the features of claims 1, 14, 24 and 31. Further features are contained in the subclaims.

The present invention provides a method of casting ribbons for forming ribbons to form different layers of a sleeve-shaped blanket. "Strip casting", as defined herein, may mean applying a liquid material from a stationary source to a rotating and advancing substrate, or applying a liquid from a circulating source to a moving substrate , In this way, a continuous band of liquid material can be applied to the substrate.

As defined herein, "liquid material" may be any flowable material, including a semi-solid material. The liquid material is preferably a polymer which does not require a separate curing step, ie a self-curing material. Because the liquid is out can be dispensed to a single mouthpiece of the source, the application of the material for forming the blanket is easier than in a crosshead extruder, in which material is pressed outwards so that the entire circumference of the substrate is touched. In addition, liquid materials are easier to use than strip materials.

A device according to the invention for producing a sleeve-shaped printing blanket with a sleeve conveying device for moving a carrier sleeve is characterized by at least one strip casting device which applies a flowable material, wherein the applied flowable material forms a layer arranged above the carrier sleeve.

The present invention provides a more cost effective and faster manufacture of blankets. The cost of sleeve blankets is a large factor in the total cost of ownership of a printing machine that uses sleeve-shaped blankets.

The at least one strip casting device preferably comprises a strip casting device for producing a compressible layer having a first flowable material supply region and a compressibility generating device, which may be, for example, a compressible microsphere delivery region or a blowing or foaming device. The foam structure or microspheres can provide the compressibility desired for the compressible layer.

The at least one strip casting apparatus preferably further comprises a strip casting apparatus for producing a reinforcing layer and a strip casting apparatus for producing a printing layer.

Strip casting machines preferably each have a single nozzle through which the flowable material flows onto the respective substrate.

Preferably, the belt casting devices are stationary, while the sleeve conveying device is a moving and rotating device is on which an endless support sleeve is formed, for example by using a metal strip.

Alternatively, the belt casting apparatuses may rotate in a circular motion about the substrate while the sleeve advancing means may continuously advance a sleeve substrate past the belt casting apparatuses.

The inventive method for producing a sleeve-shaped blanket, wherein a carrier sleeve is conveyed in a first direction, is characterized by tape casting a compressible layer, a reinforcing layer and / or a pressure layer around the carrier sleeve, while the carrier sleeve moves on.

Preferably, the method further comprises rotating the carrier sleeve during the step of advancing. The step of strip casting preferably comprises strip casting a compressible layer, a reinforcing layer and / or a printing layer.

Alternatively, the tape casting step may include rotating a tape casting apparatus about the carrier sleeve as the carrier sleeve advances.

Although rubber could be used for strip casting, it is usually cured thereafter in a separate step. It is extremely advantageous to use a polymer which does not require a separate curing step in the tape casting process, such polymer being defined herein as a "self-curing polymer". It is most advantageous when urethane is used to form blankets of the invention. Urethane has the advantage that it flows well during strip casting and hardens quickly. However, the self-curing polymer could also be a self-vulcanizing rubber, such as room temperature curing rubber.

The step of strip casting therefore preferably comprises tap casting urethane to form the at least one layer.

Preferably, the blankets are continuously made to have an indeterminate length. The method also includes a step of cutting the sleeve to the desired length to form the blanket.

The present invention also provides a sleeve-shaped blanket having a carrier sleeve, a compressible layer and a printing layer, wherein the compressible layer and / or the printing layer are made of urethane.

Preferably, both the compressible layer and the printing layer are made of urethane, and a reinforcing layer is disposed between the compressible layer and the printing layer. The reinforcing layer is preferably also made of urethane.

Preferably, the compressible layer is made from urethane foam which is formed by blowing carbon dioxide, air or other propellant into the urethane before it exits the die of a belt caster. However, compressible microspheres can also be embedded in the urethane to obtain compressibility.

The reinforcing layer is preferably made of urethane having high hardness test values of greater than 80 Shore A, or better, about 100 Shore A. The reinforcing layer is preferably thinner than the compressible layer.

The print layer is preferably urethane having hardness test values of less than 80 Shore A, with values of about 60 Shore A being most preferred.

Similar hardness test values can be provided for blankets of the invention made from other self-curing polymers than urethane.

The layers are preferably made by a tape casting process that produces a helically wound form that is more uniform, channelless, to form Layers together.

The carrier sleeve is preferably made of steel, preferably formed in a continuous process by a belt.

The present invention will be described in more detail below with reference to the drawings based on preferred embodiments.

Fig. 1

eine Vorrichtung zum Herstellen eines erfindungsgemäßen hülsenförmigen Drucktuchs, wobei das Ende des Drucktuchs nur aus Gründen der Anschaulichkeit schematisch dargestellt ist;

Fig. 2a, 2b

Einzelheiten der Dreh- und Weiterbeförderungseinrichtung zum Herstellen eines endlosen, hülsenförmigen Drucktuchs;

Fig. 3

eine alternative Ausführung der Herstellungsvorrichtung der vorliegenden Erfindung, bei der sich die Bandgießvorrichtungen um das Substrat drehen;

Fig. 4

eine Querschnittsansicht eines erfindungsgemäßen Drucktuchs.

Show it:

Fig. 1

a device for producing a sleeve-shaped printing blanket according to the invention, wherein the end of the blanket is shown schematically only for reasons of clarity;

Fig. 2a, 2b

Details of the turning and conveying device for producing an endless, sleeve-shaped printing blanket;

Fig. 3

an alternative embodiment of the manufacturing apparatus of the present invention wherein the tape casting apparatus rotate about the substrate;

Fig. 4

a cross-sectional view of a blanket according to the invention.

1 shows a device 1 for producing a channelless, tubular printing blanket 100 in a continuous process. In this context, the term "continuous process" indicates that the process produces an endless, sleeve-shaped blanket of indefinite axial length.

Apparatus 1 comprises a turning and further conveying device 11 for moving the printing blanket 100 continuously from right to left in Fig. 1. The device 11 has a driving section 300, the movable bars 201, 202, 203, 204, 205, 206, etc. continuously rotates and advances, as described below with reference to Fig. 2a and Fig. 2b.

In a first station 110, a belt 32, which preferably consists of steel and may have two overlapping pieces of belt, is fed to the device 11, which unwinds the belt to form a carrier sleeve 33.

At a second station 120, a first belt casting apparatus 20 associated with apparatus 1 for producing a compressible layer comprises a urethane feed 21 and a blowing device 22. The urethane feed 21 may comprise a plurality of separate sections, for example an isocyanate section, a vulcanization section and a mixing chamber, as well further material sections. Urethane from the supply 21 is foamed by the blower 22 in the mixing chamber and exits at a nozzle 23 with an end mouthpiece. The foamed urethane is thus applied to the carrier sleeve 33 to form a compressible layer 34 which is shown for illustrative purposes with the applied liquid ribbons in the form of a spiral. In effect, the applied liquid ribbons flow together and harden to form a seamless, channelless compressible layer 34.

A squeegee or scraper 55 may contact the urethane layer 34, and a grinder 56 may flatten the layer 34 to reduce imperfections, such as curls, in the layer 34.

Via this compressible layer 34, a reinforcing layer 42 is applied in a section 130 of a third station by a second strip casting device 30 of the device 1. The strip casting apparatus 30 may include a urethane feed 31 and a nozzle 36 for applying the urethane. The hardness test value of the urethane is preferably about 100 Shore A. Again, the applied urethane coalesces and hardens to form a seamless and channelless reinforcement layer 42. To reduce imperfections in the layer 42, a doctor blade 57 and a grinder 58 may be used.

A third tape casting apparatus 40, which is similar to apparatus 30, creates a tape Urethane to form a pressure layer 45 over the reinforcing layer 42. The urethane of the print layer preferably has a hardness test value of about 60 Shore A. The applied print layer forms a seamless and channelless layer upon curing. If desired, a doctor blade 51 and a grinder 50 for correcting or reducing imperfections, such as corrugations, may be used in the printing layer 45.

Once the printing layer 45 is ready, the blanket continues to move in the direction of the arrows 5 until a desired length is reached and the blanket is cut, for example, by a rotating knife or rotary saw.

In section 110, the sleeve is supported by rods 201-210 (see Figs. 2a and 2b) and may be supported in sections 120, 130 and 140 by bottom brackets.

FIG. 2a is a closer view of the operation of rods 201, 202, 203, 204, 205, 206, 207 rotating in direction 218. As the bars rotate, nine of the ten bars move in the same direction. When a bar reaches an axially most distant point in the direction 5, it is pushed back in the opposite direction 5, as shown for bar 201 in Fig. 2a. This movement does not hinder the further advancement of the sleeve in direction 5, since the other nine rods continue to push the sleeve in direction 5. As soon as the rod 201 has been pushed back, it begins to move in direction 5 again.

2b shows a cross-sectional view of the bars 201, 202, 203, 204, 205, 206, 207, 208, 209 and 210 together with the drive device 300 which rotates and advances the bars, for example by bearings 260.

Fig. 3 shows an alternative embodiment in which the sleeve is transported by a transport device 400 through three circulating belt casting devices 220, 230, 240, which respectively apply the compressible layer, the reinforcing layer and the printing layer. The layers may be made of similar materials to those shown in FIG Layers 34, 42 and 45 be.

4 shows a cross-sectional view of the printing blanket 100 with the sleeve 33 formed as a carrier sleeve, the compressible layer 34, the reinforcing layer 42 and the printing layer 45.

As used herein, the term "compressible layer" refers to a polymeric material which has been made compressible by any of the known processes, including, for example, the use of microspheres, blowing agents, foaming agents or leaching. Examples of these materials are disclosed, for example, in US 5,768,990, US 5,553,541, US 5,440,981, US 5,429,048, US 5,323,702 and US 5,304,267.

As used herein, the term print layer or elastomeric print material refers to a polymeric material, such as urethane, suitable for transferring an image from an offset printing plate or other print substrate to a roll or sheet material of a print quality meeting the requirements of each Pressure application corresponds.

While the preferred embodiments of the offset blanket of the present invention prepared in the continuous process have been illustrated herein to include a compressible layer, a reinforcing layer and a print layer, it will be understood that in the event that this is required for a particular application is that the blanket may also include a base coat layer between the carrier sleeve 33 and the compressible layer 34.

In addition, although the blanket of the invention preferably comprises a compressible, a reinforcing and a printing layer, it is to be understood that it is also possible to make blankets with fewer or with additional layers. Thus, a printing blanket according to the invention, if this is sensible for a specific application, may comprise a carrier sleeve and a printing layer, or a carrier sleeve, a compressible layer and a printing layer. In addition, it is to be assumed that a printing blanket according to the invention also comprises a plurality of compressible layers, could comprise multiple build-up layers or multiple reinforcement layers.

Although the reinforcing layer is preferably formed from urethane, the reinforcing layer may also be formed of wrapping fabric or plastic tape, string or thread around the workpiece. Also, cross-spray extruder heads or strips can be used to form some of the layers that are not made by tape casting.

The temperature of the flowable material can be controlled by the respective belt casting machines. Also, the nozzles may have mouthpieces whose shape may be changed to effect a change in tape dimensions. Preferably, the temperature and shape of the nozzles are such that a steady stream of flowable material flows onto the substrate. Flow rate, temperature, nozzle shape and rotational speed of the substrate can be varied to obtain the desired properties for the different layers, for example the thickness of the layer.

List of reference numbers:

1

contraption

5

directional arrows

11

Rotary and onward transport facility

20

first strip casting device

21

Urethanzufuhr

22

blower

23

jet

30

second strip casting device

31

Urethanzufuhr

32

tape

33

support sleeve

34

compressible layer

36

jet

40

third strip casting device

42

reinforcing layer

45

print layer

51, 55, 57

Schabmesser

50, 56, 58

grinder

100

blanket

110

first stop

120

second station

130

third station

201 ... 210

rods

218

arrow

220,230,240

Bandgießvorrichtungen

260

camp

300

driving section

400

transport means

Claims (32)

1. Device for the production of a sleeve-type printing blanket with:

   a sleeve transport means (11) for moving a support sleeve (33),

   characterised by
   at least one continuous casting device (20) applying a flowable material and having a nozzle (23), through which the flowable material flows, wherein the applied flowable material forms a layer (34; 42; 45) arranged over the support sleeve (33),
   and a device for cutting through the sleeve-type printing blanket when a desired length is reached.
2. Device according to Claim 1, characterised in that the at least one continuous casting device (20) comprises a continuous casting device for the production of a compressible layer (34), which has a first feed region (21) for a flowable material and a compressibility generating means.
3. Device according to Claim 2, characterised in that the compressibility generating means is a foaming agent.
4. Device according to Claim 2, characterised in that the at least one continuous casting device (40) comprises a continuous casting device (40) for the production of a printing layer (45).
5. Device according to Claim 2, characterised in that the at least one continuous casting device (20) comprises a continuous casting device (30) for the production of a reinforcing layer (42) and a continuous casting device (40) for the production of a printing layer (45).
6. Device according to one of the preceding claims, characterised in that the at least one continuous casting device (20) has a single nozzle (23), through which the flowable material flows.
7. Device according to one of the preceding claims, characterised in that the at least one continuous casting device (20) is fixed in position, and the sleeve transport means is a transporting and rotating means (11).
8. Device according to Claim 7, characterised in that the support sleeve (33) is a continuous sleeve formed from a metal strip.
9. Device according to one of Claims 1 to 6, characterised in that the at least one continuous casting device (20) is rotatable around the sleeve (33).
10. Device according to one of the preceding claims, characterised in that the flowable material is a self-curing polymer.
11. Device according to Claim 10, characterised in that the self-curing polymer is urethane.
12. Device according to Claim 10, characterised in that the self-curing polymer is rubber, which cures as room temperature.
13. Device according to one of the preceding claims, which additional comprises a grinding station (56), which is connected behind the at least one continuous casting device (20).
14. Process for the production of a sleeve-type printing blanket, wherein a support sleeve is transported in a first direction, characterised by
    continuous casting of a compressible layer (34), a reinforcing layer (42) and/or a printing layer (45) around the support sleeve (33) using at least one continuous casting device (20) applying a flowable material and having a nozzle (23), through which the flowable material flows, while the support sleeve (33) moves further, and additionally including the cutting of the sleeve (33) to a desired length.
15. Process according to Claim 14, which additionally includes rotation of the support sleeve (33) during the step of further transport.
16. Process according to Claim 14, characterised in that the step of continuous casting includes rotation of a continuous casting device (20) around the sleeve (33) while the support sleeve (33) moves further.
17. Process according to one of Claims 14 to 16, characterised in that the compressible layer (34), the reinforcing layer (42) or the printing layer (45) is made of urethane.
18. Process according to Claim 17, which comprises the following process steps, characterised in that the compressible layer (34) of urethane is applied to the support sleeve (33); and that the printing layer (45) of urethane is applied over the compressible layer (34).
19. Process according to Claim 17 or 18, which additionally includes the application of the reinforcing layer (42) of urethane over the compressible layer (34).
20. Process according to one of Claims 14 to 16, characterised in that the compressible layer (34), the reinforcing layer (42) or the printing layer (45) is made from a self-curing polymer.
21. Process according to one of Claims 14 to 20, characterised in that the support sleeve (33) is formed continuously.
22. Process according to one of Claims 14 to 21, which additionally includes grinding of the compressible layer (34), the reinforcing layer (42) and/or the printing layer (45).
23. Process according to one of Claims 14 to 22, characterised in that the printing blanket (100) is formed continuously.
24. Sleeve-type printing blanket for offset printing with:

    a support sleeve (33); a compressible layer (34) arranged over the support sleeve (33) and a printing layer (45) arranged over the compressible layer (34),

    characterised in that the compressible layer (34) and/or the printing layer (45) is made from urethane, and that the printing blanket is produced by means of the process according to one of Claims 14 to 23.
25. Printing blanket according to Claim 24, which additionally comprises a reinforcing layer (42) arranged between the compressible layer (34) and the printing layer (45).
26. Printing blanket according to Claim 25, characterised in that the reinforcing layer (42) is made from urethane.
27. Printing blanket according to Claim 25 or 26, characterised in that the reinforcing layer (42) has a hardness test value of more than 80 Shore A.
28. Printing blanket according to one of Claims 25 to 27, characterised in that the reinforcing layer (42) is thinner than the compressible layer.
29. Printing blanket according to Claim 28, characterised in that the printing layer (45) is produced from urethane with a hardness test value below 80 Shore A.
30. Printing blanket according to one of Claims 24 to 29, characterised in that the support sleeve is produced from a band (32) wound in a spiral shape.
31. Sleeve-type printing blanket for offset printing with:

    a support sleeve (33); a compressible layer (34) arranged over the support sleeve (33) and a printing layer (45) arranged over the compressible layer (34), characterised in that the compressible layer (34) and/or the printing layer (45) is made from a self-curing polymer, and that the printing blanket is produced by means of a process according to Claim 20.
32. Printing blanket according to Claim 31, characterised in that the self-curing polymer is rubber, which cures as room temperature.

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