EP2011653A2 - Washing device for a cylinder in a printing machine - Google Patents

Abstract

The device i.e. blanket washing device (GTW), has a washing cloth (10) for removing contaminants and ink from a surface of a cylinder i.e. blanket cylinder (GTZ). A cylindrical ultrasonic generator directs sound energy onto the surface of the cylinder for assisting a washing operation. A focusing device e.g. sonotrode, positioned in front of the ultrasonic generator concentrates the sound energy onto a linear focus region on the surface of the cylinder extending parallel to an axis of the cylinder. A cylindrical lens is made of plastic in which the speed of sound is higher than in water.

Description

The invention relates to a washing device for a cylinder in a printing press with a washing cloth and an ultrasonic source, which directs sound energy to the cylinder surface.

Such a washing device is for example from the WO 03/011599 known. There is an ultrasonic source is provided to assist the washing process, which is to facilitate the removal of impurities, color, etc. from the surface of the clamped on a transfer cylinder blanket in an offset printing machine. Furthermore, in the DE 100 63 987 A1 a cloth washing device for a digital printing machine described. There, a liquid-impregnated cleaning tape on the cylinder surface can be acted upon with an ultrasonic actuator to clean the printing image bearing cylinder. Furthermore, from the DE 197 32 060 describes a washing device for the blanket cylinder of an offset printing machine, which has an ultrasonic generator, but no washing cloth. Here, the dissolved dirt particles are to be scraped off by rubber lips from the cylinder surface.

In the JP 11-70641 describes the use of an ultrasonically vibrating washing doctor blade which is in direct mechanical contact with the rubber surface. In devices of this type there is a risk that the sprayed liquid sprayed on the blanket in front of the doctor blade into the printing machine and there causes damage due to corrosion, etc.

The so-called cloth washing devices commonly used in offset printing machines, with which the inked blanket is cleaned on the transfer cylinder during a job change, usually do not have ultrasonic sources for washing assistance. Even without such support the washing time is approx. 2 minutes, whereby the blanket is washed clean within 3 to 4 cylinder revolutions. Nevertheless, there is a desire, in the sense of a quick order change, to further shorten the washing times. However, this was not possible with the ultrasonic assisted washing devices described in the prior art, the realization of which failed because the proposed devices had too high a power requirement. Because in order to achieve the ultrasonic cleaning effect in a single sweeping the blanket surface, very high ultrasonic power densities are required on the dyed blanket surface, as otherwise known only from the material processing and can be achieved, for example, with welding sonotrodes. Conventional inexpensive sound generators are unable to provide this required ultrasonic power. They also heat up very much due to the low efficiency of the conversion of electrical power into sound power, which can lead to the destruction of the sound sources. Therefore, the previous proposals for improving the washing performance of blanket washing facilities with the support of ultrasound have not been successful.

From ultrasound diagnostics, it is known to focus the ultrasound waves to produce ultrasound images. However, such arrangements are unsuitable for washing facilities.

From the U.S. Patent 5,803,099 is a wash tank with ultrasonic encoders known whose sound fields are focused by spherical ultrasound lenses on punctiform areas. For quick cleaning of cylinder surfaces, this washing device is not suitable.

It is the object of the present invention to provide a washing device for the cylinders of printing presses, with which the washing process can be significantly shortened and which manages with an acceptable electrical connection performance. This object is achieved with the measures specified in the characterizing part of claim 1.

According to the invention, the sound energy emitted by one or more ultrasound transmitters of an ultrasound source is concentrated on a substantially line-shaped focal region extending parallel to the cylinder axis on the cylinder surface. For this purpose, an ultrasonic cylinder lens is advantageously used, which consists of a single or more cylindrical or toric acoustic lenses. In addition, the focusing device can also be formed by a cylindrical concave shape of the sonotrodes or ultrasonic vibrator, of course, both measures, the cylindrical sound lens and the concave shape of the sonotrodes can be combined. The high sound energy density generated on the cylinder or blanket surface in the substantially linear focus region then dissolves the paint or impurities from the surface, whereby the dirt or color particles are carried away by the moist washing cloth applied to the surface. It may be particularly advantageous if the washcloth continuously moves over the line-shaped focus area during the washing operation, while at the same time the cylinder is rotating at a greater surface speed in the direction of the wash cloth movement.

Furthermore, it is expedient to use the cylindrical sound lens, which generates the linear focus either alone or with other tools together, to press the wash cloth against the cylinder surface to be cleaned. The construction becomes particularly simple when this cylindrical lens is designed as a tubular plastic part, in the interior of which the washing liquid for moistening the washing cloth or the cooling liquid for cooling the ultrasonic generator is contained. In this case, two or more functions, namely the guiding of the washing liquid or cooling liquid, the focusing of the ultrasonic energy and the pressing of the washing cloth to the rubber or cylinder surface are fulfilled by a component.

Further advantages of the invention will become apparent from the following description of exemplary embodiments with reference to FIG FIGS. 1 to 9 of the accompanying drawings.

FIG. 9 is a schematic representation of the cylinder in the printing unit of an offset printing press in the plane perpendicular to the cylinder axes. With PZ is like that referred plate cylinder referred to the holders on the clamping channel which is not shown rolls of an inking unit colored printing plate is attached. The print image on the printing plate is transferred to the rubber blanket GT when the cylinders are rotated, which is mounted on the blanket cylinder GTZ shown below. With PB of the paper sheet is called, which is passed between the blanket cylinder GTZ and the impression cylinder GDZ while the blanket GT is printed with color.

For washing the blanket, as usual in offset printing machines, a blanket washing device GTW is provided, which can be employed along the arrow P during order change after the end of the printing operation on the blanket cylinder GTZ. This washing device GTW usually contains a washing cloth 10, which is cyclically cycled from a supply roll 11a unwound and wound onto a second roll 11b. In between, the washing cloth 10 is pressed by a pressing element 11 against the surface of the rubber blanket GT to be cleaned.

Usually, such blanket washing devices work so that the cylinder surface to be cleaned rotates past the pressed-on wash cloth and this is repeatedly indexed several times during one revolution in order to convey the colored strip-shaped region of the washing cloth again and again in the direction of the take-up roll 11b. The washing device further includes a drive for the movement of the washing cloth and a device for the supply of washing liquid, unless already the supply roll 11 a is soaked with washing liquid.

FIG. 1 shows in more detail a first embodiment of the invention modified according to the pressing element 11 of the blanket washing device GTW in section perpendicular to the cylinder axes.

In the embodiment according to FIG. 1 consists of the pressing member 11 of a U-shaped aluminum profile, which on the side with which the wash cloth 10 against the Blanket GT pushes, is provided with a longitudinal slot. Inside the profile is an elongated sonotrode with the in FIG. 1a shown construction. It consists of two strip-shaped masses 13a and 13b, between which a piezo-ceramic layer 13c is arranged, which is vapor-deposited on both sides with metal electrons. The lower, the wash cloth 10 facing part 13b of the sonotrode 13 is concave on its underside 14 and focuses the radiated ultrasonic power to a narrow, substantially linear focus area on the surface of the blanket GT. The sonotrode 13 is pressed by springs 16 against a provided with a seal 18 seat on the inner sides of the two legs of the U-shaped profile 12. In the upper part of the part 13a of the sonotrode 13 strips 12a are used in the profile 12 for positional fixation.

Like in the FIG. 1 shown the rounded two U-shaped legs of the profile 12 press the wash cloth 10 against the surface of the blanket GT. For moistening the washing cloth with washing liquid, inflow tubes 15 are provided along the profile 12, which open into channels 17, through which the washing liquid enters the space between the washing cloth 10 and the concave surface 14 of the sonotrode 13 and fills it. Due to the washing liquid, the ultrasound energy is effectively brought to the surface of the blanket GT while avoiding excessive reflections, where it can dissolve dirt and paint residues adhering to the blanket surface due to the onset of cavitation of gas bubbles formed in the liquid in the focus area.

Of course, it is also possible to arrange a plurality of individual shorter sonotrodes in the profile 12 instead of a single sonotrode 13. The are then suitably driven in phase during operation of the washing device to avoid destructive indifferences. In this case, it may also be appropriate to provide webs between the two legs of the U-shaped profile 12, which allow a sealing between the individual sonotrodes against the ingress of washing water into the interior of the housing 12. In this case, it will be appropriate to insert the individual sonotrodes via closable openings on the top of the profile 12.

FIG. 2 shows an alternative second embodiment of the modified according to the invention pressing member 11 of the blanket washing device GTW.

In the embodiment according to FIG. 2 are compared to FIG. 1 identical or similar parts with a reference number higher by 10 to facilitate understanding.

In contrast to the embodiment according to FIG. 1 are in the hollow U-shaped aluminum profile 22, which serves as a pressing element, a plurality of individual sonotrodes 23 arranged one behind the other, for example, 20 pieces with a length of about 5 cm for the blanket cylinder of a printing press in the format 105 cm. These sonotrodes are pressed by springs 26 against the back of a concave cylindrical lens 29 made of plastic, which is inserted over the length of the aluminum profile 22 along grooves 22b in this. Against lateral displacement, the sonotrodes 23 are secured by strips 22 a in the interior of the profile 22.

Over the ultrasound beam lobe adapted opening 21 between the two U-shaped legs of the profile 22 is a liquid flow limiting membrane 26 made of plastic, rubber or a porous ceramic. When selecting the material, the density of the membrane is expediently adapted to the density of the washing liquid in order to avoid undesired reflections of the ultrasonic energy at the interface with the membrane 26. The membrane 26 limits the flow of wash fluid from the inflow tubes 25 into the washcloth 10 and ensures that no wash liquid exits when the wash is complete and the pressure in the inflow tube 25 is turned off.

The cylindrical plastic lens 29 is made of Plexiglas. Because in this material the speed of sound is almost twice as high as in water, the plano-concave cylindrical lens acts collecting and concentrates the ultrasonic power in a very narrow line-shaped area, as indicated by the arrows.

Of course, it is also possible with appropriate dimensioning of the radius of the cylindrical lens and its distance from the surface of the blanket, other plastics such as polyacrylics, etc. use.

By using a plurality of individual sonotrodes, there is the advantage that the length of the pressure element of the blanket washing device can be adapted to different format widths, without the need to manufacture special individual sonotrodes for the format in each case. In the same way, a number of individual toric or cylindrical individual lenses may be provided instead of the cylindrical lens made of plastic, which are each associated with the individual sonotrodes. In this case, a toric formation of the individual lenses supports the uniformity of the sound propagation along the cylinder surface over the regions which are switched off by the webs.

FIG. 3 shows a third embodiment of the modified according to the invention pressing member 11 of the blanket washing device GTW.

In the embodiment according to FIG. 3 the cuboid sonotrodes are replaced by ultrasonic transducers 33a, 33b ..... with a circular cross-section. Such ultrasound transmitters can be purchased inexpensively as purchased parts, because they are used in large quantities in other applications. In the present case, the ultrasound transmitters 33a, 33b ... are not arranged in a line one behind the other, but are staggered close to one another and are alternately arranged inclined relative to one another, as in FIG FIG. 3a is clarified. The ultrasound transmitters respectively associated springs 36a, 36b ... push the ultrasonic transducer 33a, 33b ... on a prism bar 38 which is glued to the back of the cylindrical lens 39. The prism bar 38 is made of the same material as the cylindrical lens 39, so that impedance jumps, as they otherwise occur in the transition to another medium, are avoided.

FIG. 4 shows a fourth embodiment, for the modified according to the invention pressing member 11 of the blanket washing device GTW.

In the embodiment according to FIG. 4 are also simple inexpensive cylindrical ultrasonic transducer 43 is used, but these are used in succession with their axes parallel to each other in the circular recesses of two slides 41a, 41b, as shown in the FIG. 4a are sketched. The array of cylindrical ultrasonic generators formed in this way is the front side into the in FIG. 4 inserted aluminum profile 42 is inserted, wherein the lower, the blanket GT facing slide 41a rests on a shoulder 42a in the interior of the profile 42 via a sealing tape 48. The interior of the profile 42 is filled with oil above the part 41a, which serves to dissipate the heat generated in the ultrasonic generators 43. The lower, the wash cloth 10 facing side 44 of the ultrasonic generator 43 is formed cylindrically concave, as in the FIG. 4b outlined. The axes K of the cylindrically concave recesses of all the ultrasound transmitters 43 received one behind the other in the slides 41a, 41b are aligned in a line parallel to the axis of the blanket cylinder GTZ. In this way, the ultrasound energy radiated by the ultrasonic transmitters 43, as indicated by the arrows in FIG FIG. 4 shown focused substantially on a narrow line-shaped area parallel to the cylinder axis on the surface of the blanket GT, with a suitable choice of the radius of curvature of the concave cylindrical recess 44 in the ultrasonic generator 43, and the distance of the ultrasonic transmitter to the wash cloth.

FIG. 5 shows a fifth embodiment of the modified according to the invention pressure element 11 of the blanket washing device GTW.

In the embodiment according to FIG. 5 is contrary to the post FIG. 4 the aluminum profile 42 has been replaced by a plastic profile 52. The profile 52 has a U-shaped cross-section and is closed like a trough on the wash cloth 10 side facing, while its two in cross-section U-shaped leg is closed on the opposite side above by a lid 57. On the outside, the plastic profile part 52 carries a plurality of ribs 51 extending over its entire length for stiffening and heat dissipation. The outer circular cross section of the profile 52 is flattened on the wash cloth side or adapted to the radius of the blanket GT. In this way, already receives the wall of the profile 52 in the support area the wash cloth 10 is in the form of a concave cylindrical lens 59, which again bundles the ultrasonic energy radiated from the underside of the ultrasound generator 53 inserted in the profile before striking the blanket and focuses it in a line-shaped area of a blanket surface.

The ultrasound transmitters 53 are the same as those after FIG. 4 , However, are placed in the plastic profile 52 with the cover 57 removed from above on strips 52a in the profile 52, wherein pins 58 in conjunction with a longitudinal groove 59 in the ultrasonic encoders act as rotation and hold the encoder 53 in place. The interior of the profile 52 is filled with a non-conductive liquid, which has a significantly lower density than the material of the plastic profile 52. In this way, the biconvex liquid rod 60 acts between the concave undersides of the ultrasonic generator and the concave inner side of the profile 52 as a cylindrical condenser lens , from which the ultrasonic power is focused on a linear area. The non-conductive liquid also serves to absorb the heat generated during operation of the ultrasonic generator 53, so that the transmitter 53 does not overheat.

The washing liquid is sprayed in this embodiment by separate spray nozzles 55 next to the pressure element on the wash cloth 10. The washing cloth 10 moves at a slower speed during the washing past the pressing element, while at the same time the cylinder GTZ moves with the blanket GT in the opposite direction the blanket GT under the pressure element or the washing cloth 10.

The FIG. 6 shows a sixth embodiment of the modified according to the invention pressure element 11 of the blanket washing device GTW.

In the embodiment according to FIG. 6 the housing of the pressure element consists of a stable metal housing with H-shaped cross section, which is open at the top and bottom. In the two legs 62a and 65b connecting cross member 62c of the profile are sealed provided on tight holes for receiving cylindrical ultrasonic encoders 63, in which they are inserted.

The lower portion of the legs 62a and 62b tapers slightly towards the center. In this area, a plastic tube 69 is inserted from a material with the comparison to the washing liquid much higher density such as polyethylene. This plastic tube is flattened on both sides above and below. The planar undersides of the ultrasound transmitters 63 settle on the upper flattening, while the plastic tube 69 with its lower flattening settles on the washcloth 10 or is pressed against it by the springs 66 via the ultrasound transmitters 63 when the washing device has the profile 62 in FIG Direction to the blanket GT is delivered.

In the tube capillaries 67 are introduced in the region of the lower flattening through which the washing liquid emerges at a corresponding pressure and wets the wash cloth 10.

In this embodiment, the cylindrical liquid rod of the washing liquid in conjunction with the plano-concave cylindrical lenses of the flats of the plastic tube 69 focuses the ultrasonic energy in the desired manner to a narrow line-shaped area. In addition, in this embodiment, the springs 66 perform a dual function: they press the ultrasonic transducer 63 firmly on their seat and the tube member 69 of the pressure element firmly against the wash cloth 10th

The FIG. 7 shows a seventh embodiment of the modified according to the invention pressing member 11 of the blanket washing device GTW.

In the embodiment according to FIG. 7 consists of the pressing element for the wash cloth 10 total of a thick-walled plastic tube 79 which is closed on both sides and on both sides, as from the view FIG. 7 is provided with an inlet port 78a and an outlet nozzle 78b for the washing liquid. The tube 79 is connected to a cooling unit, via which the resulting during the washing process heat loss is dissipated by the ultrasonic generator. The plastic tube 79 is made of the same material as the tube 69 FIG. 7 and also carries on its underside a flattening, which is provided with capillaries for the passage of the washing liquid.

In the plastic tube 79, a metal profile 72 is inserted and is held there via two projections 71 a and 71 b in the corresponding grooves in the plastic tube 79. In the metal profile 72 are sealed and sealed a plurality of rectangular in cross-section ultrasonic transducer 73 encapsulated, their undersides 79 as in the embodiment according to FIG. 1 are cylindrically shaped concave. Due to this concave shape, the wedge of the washing liquid 70 between the bottoms 79 of the ultrasonic emitters 73 and the concave inside of the tube 79 becomes a "thick cylinder lens" and focuses the ultrasonic waves on a line-shaped area. In this embodiment, the washing liquid 70 is also used for cooling the ultrasound generator.

LIST OF REFERENCE NUMBERS

PZ

plate cylinder

GT

blanket

GTZ

Blanket cylinder

PB

sheet of paper

GDZ

Impression cylinder

10

washcloth

11

pressing element

11a

supply roll

11b

up reel

12, 22

U-shaped profile

12a

Afford

13, 23, 33, 43, 53, 63, 73

Sonotrode (s) (Ultrasound Transducer)

13a, b

strip-shaped mass

13c, 23c, 43, 53c, 63c, 73c

Piezo-ceramic layer

14, 34, 44

concave underside

15.25

inflow tube

16,26,36,46,56,66,76

feathers

17

channels

18

poetry

21

opening

22, 42

aluminum profile

22b

groove

26

membrane

29, 39

Cylindrical lens (plastic)

33a, 33b, ...

ultrasonic generator

36a, 36b

feathers

38

prism bar

41a, 41b

pusher

42a

shoulder

48

sealing tape

51

ribs

52

Plastic profile

52a

Afford

55

spray nozzles

57

cover

58

pencils

59

longitudinal groove

60, 70

liquid staff

62a, b

leg

62c

crossmember

67

capillaries

69, 79

Plastic pipe

71a, b

projections

72

metal profile

78a

inlet port

78b

outlet

Claims (18)

A cylinder (GT) washing apparatus in a printing machine having a washing cloth (10) for removing impurities, paint, etc. from the cylinder surface and an ultrasonic source for assisting the washing operation directing sound energy to the cylinder surface,
characterized,
in that the ultrasonic source (13; 23; 33; 43; 53; 63; 73) is preceded by focusing means (14; 29; 34; 39; 44; 54; 59; 60; 69; 70; 79), of which the Sound energy is concentrated on a substantially linear parallel to the axis of the cylinder (GT) extending focus area on the cylinder surface. Washing device according to claim 1,
characterized
wherein the ultrasonic source consists of an arrangement of a plurality of individual oscillators (23, 33, 43, 53, 63, 73) and the individual oscillators (23, 33, 43, 53, 63, 73) preferably along or alternately offset to a straight line parallel to the axis of the cylinder (GT) are arranged. Washing device according to one of claims 1 or 2,
characterized
wherein the ultrasonic source consists of one or more elongated horns (13, 23, 73). Washing device according to one of claims 1 to 3,
wherein the focusing means comprises a plurality of toric or cylindrical acoustic lenses (29; 39; 59; 69; 79). Washing device according to one of claims 1 to 3,
wherein the focusing means is at least partially formed by a cylindrically concave shape (14, 34, 44) of the sonotrodes or oscillators. Washing device according to one of claims 1 to 5,
wherein liquid is in the area between the ultrasonic source and the cylinder surface and the liquid is part of the focusing means or is in the area between the focusing means and the cylinder surface. Washing device according to claim 6,
wherein the liquid is washing liquid and the washing liquid is supplied to the area between the focusing means and the washing cloth (10). Washing device according to claim 7,
wherein between the filled with the washing liquid area and the applied surface on the cylinder surface a liquid flow limiting, ultrasound-permeable membrane (26) is arranged, which is preferably formed as a perforated rubber or plastic part or porous ceramic part. Washing device according to claim 8,
wherein the membrane acts as a cylindrical lens (59, 69, 79). Washing device according to one of claims 4 or 9,
wherein the cylindrical lens (59, 69, 79) presses the washing cloth against the cylinder surface. Washing device according to one of claims 4 or 9,
marked by
a washing cloth which continuously moves the washing cloth during the washing operation. Washing device according to one of claims 1 to 11,
wherein the fibers of the washing cloth consist of a material which does not absorb or dampen the ultrasonic waves. Washing device according to one of claims 1 to 12,
wherein the ultrasonic source has an axial extent of at least 70 cm, preferably 90 to 110 cm, the power consumption of the ultrasonic source during the washing operation is less than 1000 watts and the washcloth has a thickness of at least 1 mm in the non-pressed state. Method according to claim 6,
wherein the space between the ultrasonic sources (53) and the focusing means (59) is filled with an electrically non-conductive liquid. Washing device according to one of claims 1 to 14,
wherein oil surrounds the ultrasonic sources (53, 63) and absorbs or dissipates the heat generated during their operation. Washing device according to claim 10,
wherein the focusing means is formed as a hollow tubular or rod-shaped part (69,79) whose interior is filled with washing liquid (70) and which is provided with bores or capillaries (67) for the onset of washing liquid. Washing device according to one of claims 4 to 16,
wherein the cylindrical lens (29; 39) or the rod-shaped or tubular part (69, 79) consists of a plastic in which the speed of sound is higher than in water, and the material of the plastic is preferably polystyrene, Plexiglas, Polyethylene or polyacrylic is. Washing device according to claim 2,
marked by
a common control electronics, of which the individual oscillators are driven with the same frequency and fixed phase relationship to each other.

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