Printing cylinder with washing means particularly for rotary printing machines

Abstract: A printing cylinder comprising a cylindrical body inside which a color feed bar (2) extends; the bar is provided with a coupling inlet arranged outside the cylindrical body and is adapted to feed the color at a doctor blade (10) which acts on the inner surface of the cylindrical body. A washing water feed chamber (20) is defined around the color feed bar (2) and is connected to an inlet coupling arranged outside the cylindrical body; the chamber is provided with a first plurality of nozzles (30) for feeding the washing water toward the blade (10) and with a second plurality of nozzles for feeding the washing water toward the heads of the cylindrical body.

Description: The present invention relates to a printing cylinder with washing means particularly for rotary printing machines. As is known, a problem which is currently strongly felt in rotary printing machines used for example for printing fabrics and the like is related to the washing of the printing cylinders every time the color is to be changed. In order to perform the washing it is normally necessary to remove the cylinder, together with the doctor blade contained therein, and perform the washing on a separate washing box. In other solutions, the printing cylinder is directly washed on the printing machine, see e.g. EP-A 0 277 481; such solutions, however, have generally not turned out to be practical, since they entail considerable constructive complexities for the printing machine and are not always capable of accurately washing the printing cylinder. The aim of the invention is indeed to eliminate the above described disadvantages by providing a printing cylinder which can be washed rapidly and easily without having to remove it from the printing machine and without introducing particular constructive complications. Within the scope of the above described aim, a particular object of the invention is to provide a printing cylinder which is structured so as to achieve an accurate washing of all the regions thereof which are normally affected by color and without having to incline the cylinder to remove the washing water. Another object of the present invention is to provide a printing cylinder which by virtue of its peculiar constructive characteristics is capable of giving the greatest assurances of reliability and safety in use. Not least object of the present invention is to provide a printing cylinder which can be easily obtained starting from commonly commercially available elements and materials and is furthermore competitive from a merely economical point of view. The above described aim, as well as the objects mentioned and others which will become apparent hereinafter, are achieved by a printing cylinder with washing means, particularly for rotary printing machines, according to the invention, characterized in that it comprises a cylindrical body inside which there extends a color feed bar provided with a coupling inlet arranged outside said cylindrical body, said bar being adapted to feed the color at a blade which acts on the inner surface of said cylindrical body, a washing water feed chamber being defined around said bar, said chamber being connected to an inlet coupling which is arranged outside said cylindrical body, said chamber having a first plurality of nozzles for sending the washing water toward said blade and a second plurality of nozzles for feeding the washing water toward the heads of said cylindrical body. Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment, illustrated only by way of non-limitative example in the accompanying drawings, wherein: figure 1 is a schematic perspective view of the printing cylinder according to the invention; figure 2 is a sectional view of an end of the printing cylinder; figure 3 is a sectional view taken along the line III-III of figure 2; figure 4 is a view taken along the line IV-IV of figure 2. With reference to the above described figures, the printing cylinder with washing means, particularly for rotary printing machines, according to the invention, comprises a cylindrical body 1 provided with the conventional surface for the passage of the color onto the fabric or the like to be printed. Inside said cylindrical body 1 there is a color feed bar 2 which is provided, at least at one of its axial ends, with a coupling inlet 3 which is external to said cylindrical body 1. A doctor blade or knife 10 is connected to the color bar, inside the cylindrical body 1, and its free end acts at the inner surface of said cylindrical body so as to distribute the color to be printed. An important peculiarity of the invention resides in the fact that the color arriving from the color feed bar 2 is fed onto the doctor blade by means of small channels 11 which extend substantially transversely to the longitudinal extension of said blade, so as to have a color outflow port 12 which is relatively proximate to the cylinder's inner surface. This solution allows to reduce the dirtying of the blade, since the color is already fed at the blade's free end, contrary to the current art, according to which the color is fed at the blade's region of coupling to the color bar. In this manner, the color, besides being able to spread uniformly, significantly reduces the dirtying of the blade especially at the regions of coupling to the color bar, which are difficult to wash. A washing water feed chamber 20 is defined around the color feed bar and preferably has, in transverse cross section, the shape of an annular sector which affects the periphery of the color bar except for the region where the blade 10 is provided. Said washing water feed chamber 20 is provided with an inlet coupling 21 arranged outside said cylindrical body which is advantageously coaxial to the coupling inlet 3. The washing water feed chamber 20 is provided with a first plurality of washing nozzles 30 which are arranged along the longitudinal extension of the chamber 20 and are orientated so as to feed the washing jets against both faces of the blade, consequently washing the blade accurately. A second plurality of washing nozzles 35 is furthermore arranged at axial ends of the chamber 20; said nozzles are directed so as to propel the washing water jet toward the heads or axial ends 40 of the printing cylinder, thus eliminating the amount of color which unavoidably deposits in the printing cylinder in the region arranged outside the blade's longitudinal ends. In order to facilitate the removal of the washing liquid, the heads 40 are furthermore provided with a plurality of discharge holes 41 which have their peripheral edge at the inner surface of the cylinder, so that there is no stagnation of washing water inside the cylinder even if said cylinder is not inclined. A covering lid, not illustrated in the drawings, is obviously furthermore provided; said lid closes the holes 41 during the normal printing steps, during which the color is inside the cylindrical body 1. In practical use, the printing cylinder according to the invention allows to print the color in the conventional manner by feeding the color by means of the color feed bar 2 which, by virtue of the coupling inlet 3, is connected to a color feed pump. When washing is to be performed, washing water is fed both by means of the inlet coupling 21 and by means of the coupling inlet 3, so that the washing water is sent into the chamber or color feed bar, washing it accurately; the washing water jets are simultaneously sent to the blade and wash it completely, being facilitated in doing so by the fact that the color is fed onto the blade already proximate to the inner surface of the printing cylinder, with a consequently lesser dirtying of the blade. The presence of the second plurality of nozzles 35 washes the cylinder's end region where color unavoidably deposits. The lids closing the holes 41 are also removed during washing so that the washing water can flow directly toward the outside. From what has been described above, it can thus be seen that the invention achieves the proposed aims, and in particular the fact is stressed that the particular arrangement of the nozzles allows to completely wash all the cylinder's internal regions. Another important aspect is furthermore constituted by the fact that since the blade's color discharge ports are proximate to the inner surface of the cylindrical printing body, the dirtying of its outer surface is reduced significantly. The coaxial arrangement of the coupling inlets for color feed and of the inlet coupling for the washing water furthermore allows to simplify all the connections. The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept. All the details may furthermore be replaced with other technically equivalent elements. In practice, the materials employed, so long as compatible with the specific use, as well as the dimensions and the contingent shapes, may be any according to the requirements. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Printing cylinder with washing means, particularly for rotary printing machines, characterized in that it comprises a cylindrical body (1) inside which there extends a color feed bar (2) which is provided with a coupling inlet (3) arranged outside said cylindrical body (1), said bar being adapted to feed the color at a doctor blade (10) which acts on the inner surface of said cylindrical body, a washing water feed chamber (20) being defined around said bar, said chamber being connected to an inlet coupling (21) which is arranged outside said cylindrical body, said chamber having a first plurality of nozzles (30) for feeding the washing water toward said blade and a second plurality of nozzles (35) for feeding the washing water toward the heads (40) of said cylindrical body. Printing cylinder, according to claim 1, characterized in that a plurality of channels (11) extends from said color feed bar (2), said channels being arranged transversely in said blade (10) and ending proximate to the inner surface of said cylindrical body (1) in order to feed the color. Printing cylinder, according to the preceding claims, characterized in that said washing water feed chamber (20) is essentially in the shape of an annular sector which is coaxial to said color feed bar (2) and encircles said bar except for the portion in which said blade (10) extends. Printing cylinder, according to one or more of the preceding claims, characterized in that said first plurality of nozzles (30) extends longitudinally with respect to said blade (10) and is provided at the front face of said blade and at the rear face thereof. Printing cylinder, according to one or more of the preceding claims, characterized in that said second plurality of nozzles (35) is provided substantially at the axial ends of said washing water feed chamber (20). Printing cylinder, according to one or more of the preceding claims, characterized in that said coupling inlet (3) and said inlet coupling (21) are mutually coaxial. Printing cylinder, according to one or more of the preceding claims, characterized in that said heads (40) are provided with a plurality of holes (41) which have at least one edge portion flush to the inner surface of said cylindrical body in order to remove the washing water. Printing cylinder, according to one or more of the preceding claims, characterized in that it comprises a lid for the removable closure of said holes (41) provided on said heads (40).

Inventors: MASCIONI BERNARDO, MASCIONI, BERNARDO
Applicants: MASCIONI SPA, MASCIONI S.P.A.
Application year: 1989
Main classification: B41F35
IPC codes: B41F35