Patent Application
20100269274
This application claims the priority, under 35 U.S.C. §119, of German Patent Application DE 10 2009 018 580.1, filed Apr. 23, 2009; the prior application is herewith incorporated by reference in its entirety.
The invention relates to a washing device, preferably for a cylinder in a printing press, having a washing cloth and an ultrasound device for assisting a cleaning operation.
Such a washing device is known, for example, from International Publication No. WO 03/011599. There, an ultrasound source is provided for assisting a washing operation. The ultrasound source is to serve for more readily removing contaminants, ink, etc. from a surface of a rubber blanket which is clamped onto a transfer cylinder in an offset printing press. Furthermore, German Published, Non-Prosecuted Patent Application DE 100 63 987 A1, corresponding to U.S. Pat. No. 6,865,986, describes a cloth washing device for a digital printing press. There, in order to clean a cylinder which carries a printing image, a cleaning belt which is impregnated with a liquid can be loaded on the cylinder surface with an ultrasound actuator. Moreover, German Published, Non-Prosecuted Patent Application DE 197 32 060 A1 describes a washing device for the blanket cylinder of an offset printing press which has an ultrasound generator but no washing cloth. In that case, released dirt particles are to be doctored from the cylinder surface by rubber lips.
Japanese Patent Publication JP 11-70641 describes the use of a washing doctor which vibrates in the ultrasound range and is in direct mechanical contact with the rubber surface. In apparatuses of that type, there is a risk that the cleaning liquid which is sprayed onto the rubber blanket in front of the doctor passes into the printing press and causes damage there by corrosion, etc.
So-called cloth washing devices, which have previously been used in offset printing presses, and in which the inked printing blanket is cleaned on the transfer cylinder in the case of a job change, usually do not have any ultrasound sources for assisting the cleaning operation. Even without assistance of that type, the washing time is approximately 2 minutes with the rubber blanket being washed clean within approximately 10 cylinder revolutions. Nevertheless, there is the desire to further shorten the washing times, in the sense of a rapid job change. However, that was not possible with the ultrasound washing devices which are described in the prior art. Its realization failed because of the fact that the proposed units had too high a power requirement. That is because, in order to achieve the ultrasound cleaning action during a one-time sweep over the rubber blanket surface, very high ultrasound energy densities are required on the inked rubber blanket surface, such as are otherwise known from material machining and which can be achieved, for example, by way of welding sonotrodes. Conventional inexpensive sound generators are not capable of providing that required ultrasound performance. They also heat themselves up to a very pronounced extent due to the low degree of efficiency of the conversion of electrical power into effective sound performance, which can lead to the destruction of the sound sources. The previous proposals for improving the washing performance of rubber blanket washing devices with the assistance of ultrasound, therefore have not been able to gain acceptance.
It is accordingly an object of the invention to provide a washing device, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type, with which washing operations can be shortened considerably and which manages this with an acceptable electrical power input.
With the foregoing and other objects in view there is provided, in accordance with the invention, a washing device, comprising a washing cloth for removing contaminants, ink, etc. from a surface to be cleaned in a cleaning operation, and an ultrasound device for assisting the cleaning operation. The ultrasound device has at least one ultrasound generator and at least one resonator in the form of an oscillating flat metal body outputting sound energy onto a substantially linear region on the surface to be cleaned.
According to the invention, the sound energy which is produced by one or more ultrasound generators is applied by way of a resonator in the form of an oscillating flat metal body to a substantially linear region on the surface to be cleaned. To this end, a sheet metal part made, for example, from stainless steel or titanium is advantageously used, which oscillates in a normal mode of vibration of the oscillating system in the ultrasound range at a frequency of >20 kHz. It is possible for the sheet metal part to be provided with bent away portions and milled portions over the metal sheet length in order to stabilize the normal mode of vibration of the oscillating system and/or to homogenize the normal mode of vibration of the oscillating system. The high sound energy density, which is produced on the surface to be cleaned in the substantially linear region, then releases the ink and/or contaminants from the surface, with the dirt or ink particles being transported away by the damp washing cloth which bears against the surface. In this case, it can be particularly advantageous if the washing cloth moves continuously over the linear region during washing operation, whereas at the same time the part to be cleaned moves at a higher surface speed counter to or in the direction of the washing cloth movement.
Furthermore, it is expedient to use a longitudinal edge of the sheet metal part which is bent away or rounded off, in order to press the washing cloth against the surface to be cleaned. To this end, the sheet metal part is advantageously inclined with respect to the surface normal of the part to be cleaned on the line of contact, to be precise in an angular range from approximately 10° to 70°.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a washing device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now to the figures of the drawings in detail and first, particularly, to
As is customary in offset printing presses, a rubber blanket washing device GTW is provided for washing the rubber blanket GT. The rubber blanket washing device GTW can be set against the blanket cylinder GTZ along an arrow P during a job change after the end of printing operation. The washing device GTW usually includes a washing cloth 10 which is unwound in a cyclically synchronized manner from a first supply reel 11a and is wound onto a second receiving reel 11b. The washing cloth 10 is pressed, between the reels, against the surface of the rubber blanket GT to be cleaned by a pressure element 11.
Rubber blanket washing devices of this type usually operate in such a way that the cylinder surface to be cleaned rotates past below the washing cloth which is pressed on, and the latter is advanced cyclically in a stepped manner multiple times during one revolution, in order to convey an inked strip-shaped region of the washing cloth further repeatedly in the direction of the receiving reel 11b. Furthermore, the washing device includes a drive for moving the washing cloth and a device for feeding washing liquid, if the supply reel 11a has not already been impregnated with washing liquid.
In the exemplary embodiment according to
In one preferred exemplary embodiment according to
As is shown in
Of course, it is also possible, instead of a single metal part 23, to place a plurality of individual metal parts and respectively associated ultrasound oscillators in the profile 21.
It can be expedient for manufacturing reasons to provide washing devices for printing press types having different format widths and/or cylinder lengths, in which the washing devices include a plurality of ultrasound devices having identical dimensions, that is to say, for example, two for the 52 format, three for the 74 format, four for the 105 format, etc. This case is shown in
The four ultrasound oscillators, by way of which the “resonators” are excited, are connected to a common resonance amplifier 30, which is tuned to the frequency of the “resonators.” Slight production-induced tolerances in the natural frequencies of the resonator plates (23, 33, 43, 53) can also still be compensated for retrospectively by slight grinding or turning of the cylindrical masses (13a and 13b, see
The present invention has been described by using one exemplary embodiment, in which a rubber blanket (GT) that is clamped onto the blanket cylinder (GTZ) of a printing press is cleaned. However, it can also be used for cleaning not only cylindrical surfaces in other machines, appliances or systems. Rather, it can also be used to clean flat surfaces, in which a relative movement between the washing device and the surface to be cleaned is then brought about through a suitable drive.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 018 580.1 | Apr 2009 | DE | national |
