Abstract:
A printing unit with more easily removable components, comprising two outer shoulders, which are adapted to support a printing cylinder, and two inner shoulders, which are pivoted to the outer shoulders so as to pass from an open position to a closed active printing position, the pair of inner shoulders supporting an inking cylinder, a tray which is suitable to contain the ink and is arranged below the inking cylinder, and a cylinder bearing the type, the closure position of the two inner shoulders being such as to move the cylinder bearing the type into abutment against the printing cylinder in order to perform printing and such as to move the inking cylinder into abutment against the cylinder bearing the type.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a printing unit with more easily removable components. More particularly, the invention relates to a flexographic printing unit with more easily removable cylinders. 
     It is known that printing units, for example for flexographic printing, are provided with a plurality of printing cylinders: a first cylinder is an inking cylinder which dips into an ink tray in order to draw ink for printing; a second cylinder is a cylinder on which the print to be transferred to paper or another medium is provided; and a third cylinder is the actual printing cylinder, against which the cylinder that bears the type (anilox roller) abuts in order to perform printing on the paper. Finally, a fourth cylinder arranged downstream of the printing cylinder allows to transport the printed paper from one printing unit to a subsequent printing unit or to the outlet at the end of the printing cycle. 
     Printing units require considerable maintenance both as regards the cleaning to which the various cylinders must be subjected and as regards replacement of the cylinders, particularly the printing cylinder, whose diameter can vary according to the requirements of the users. 
     Conventional printing units provide for different technical solutions in order to access the various cylinders of the printing unit and therefore be able to remove them. 
     However, one drawback that is shared by all conventional solutions is the fact that access to the various cylinders, for example the inking cylinder, requires removing not only all the remaining cylinders of the printing unit but also parts of the printing unit itself, with a consequent considerable expenditure of time and difficulty in operation. 
     This situation worsens if the printing units are arranged in succession and replacement, for example removal of the inking cylinder due to a color change, which accordingly entails cleaning said cylinder, must be performed for each printing unit. 
     It is easily understandable that a removal operation for a single printing unit which requires a significant amount of time is multiplied by each printing unit that composes the printing machine. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to provide a printing unit in which the various components of the printing unit can be removed independently of each other and without having to remove fixed parts of the printing unit. 
     Within the scope of this aim, an object of the present invention is to provide a printing unit in which removal of the various components of the printing unit can be performed in a very short time and without necessarily having to make contact with the printing cylinders and consequently getting dirty. 
     Another object of the present invention is to provide a printing unit in which the various components can be removed without the aid of particular tools. 
     Another object of the present invention is to provide a printing unit with more easily removable components which is highly reliable, relatively easy to manufacture and at competitive costs. 
     This aim, these objects and others which will become apparent hereinafter are achieved by a printing unit with more easily removable components, characterized in that it comprises two outer shoulders, which are adapted to support a printing cylinder, and two inner shoulders, which are pivoted to said outer shoulders so as to pass from an open position to a closed active printing position, said pair of inner shoulders supporting an inking cylinder, a tray which is suitable to contain the ink and is arranged below said inking cylinder, and a cylinder bearing the type, the closure position of said two inner shoulders being such as to move said cylinder bearing the type into abutment against said printing cylinder in order to perform printing and such as to move said inking cylinder into abutment against said cylinder bearing the type. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further characteristics and advantages of the present invention will become apparent from the description of a preferred but not exclusive embodiment of the printing unit according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of the printing unit according to the present invention; 
     FIG. 2 is an exploded side view of the printing unit according to the present invention; 
     FIG. 3 is a partially sectional side view of the printing unit according to the present invention; 
     FIG. 4 is a side view of the printing unit according to the present invention, with some elements shown in dashed lines; 
     FIG. 5 is a partially sectional side view of the printing unit according to the invention, shown in the closed working position; 
     FIG. 6 is a top plan view of the printing unit according to the present invention; and 
     FIG. 7 is a side view of the series connection of a plurality of printing units according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the above figures, the printing unit according to the present invention, generally designated by the reference numeral  1 , comprises two lateral shoulders  2  and  3  which form a supporting frame for a printing cylinder  4  and to which an additional pair of shoulders  5  and  6  is pivoted; said shoulders  5  and  6  are adapted to rotate about a rotation pivot  7  from an open position, in which complete access to the cylinders of the printing unit is allowed, as described in detail hereinafter, to a closed position, in which the various cylinders are in the working position for performing printing. 
     Each one of the two shoulders  5  and  6  is provided with an upper arm  9  which forms a first seat  10  for a cylinder  11  which bears the type for printing. 
     The cylinder  11  is seated by resting at each seat  10  of each arm  9  by means of two pivots  12  which protrude from the cylinder  11  and are provided with bearings  13 . In this position, the cylinder  11  is inactive and the shoulders  5  and  6  are turned in the open position. 
     The cylinder  11  lies above a tray  14  which is adapted to contain the printing ink and in which an inking cylinder  15  dips; said inking cylinder is accommodated in a seat  16  formed at an intermediate region of the shoulders  5  and  6  respectively. 
     The cylinder  15  rests in the corresponding seat  16  by means of bearings  17 , arranged so that there is one on each side. 
     The tray  14  is provided, in a downward region, with a seat  20  adapted to engage a pivot  21  which is formed at a lower end of the shoulders  5  and  6 , so as to allow support of the tray  14 , which abuts, with the end that lies furthest from the seat  20 , against two arms  22  which are conveniently arranged at an angle in order to adapt to the shape of the tray  14 . 
     The two shoulders  5  and  6  therefore allow, by pivoting on the pivots  7  of the shoulders  2  and  3 , to perform an opening rotation of an entire portion of the printing unit, i.e., the portion constituted by the tray  14  and by the cylinders  11  and  15 . The shoulders  5  and  6  are interconnected by means of a cross-member  25  on which a doctor  26  is fixed; said doctor is meant to remove the excess ink that deposits on the cylinder  11  following the contact of said cylinder with the inking cylinder  15  (during operation), which dips into the tray  14 . 
     The doctor  26  is fixed to the cross-member  25  by means of a fixing element  27  (doctor and lateral cleaner supporting assembly), which has a handle  23  so as to allow its easy removal and comprises two cleaners  60  which are suitable to clean the lateral surface of the cylinder  11  from the ink. 
     The closure rotation of the two shoulders  5  and  6 , performed about the two pivots  7  of the shoulders  2  and  3 , moves the assembly constituted by the cylinder  11 , the tray  14 , the cylinder  15  and the doctor supporting assembly into the closure position and the shoulders  5  and  6  are locked by locking means  28 , for example of the pneumatic type, which are rigidly coupled to the shoulders  2  and  3  and engage in appropriate holes  29  formed at the lateral surface of the shoulders  5  and  6 . 
     In this way, the above-described portion of the printing unit is locked, keeping in the working position the cylinders  11  and  15  and the doctor and lateral cleaner supporting assembly. 
     Likewise, the printing cylinder  4  is locked in its seat by adapted locking means  30 , for example of the pneumatic type, which engage a protruding annular element  31  which is arranged at each end of the printing cylinder  4 . 
     The printing cylinder  4  is accommodated in an adapted seat  32  formed at an upper end of each one of the shoulders  2  and  3 ; accordingly, the removal of said cylinder is simplified, since it is sufficient to disengage the locking means  30  and then lift the printing cylinder  4  from the corresponding seat  32 , gripping it for example by the annular elements arranged at its ends, therefore avoiding getting dirty. 
     The closure rotation of the assembly formed by the cylinder  11 , by the cylinder  15 , by the tray  14  and by the doctor supporting assembly, rigidly connected by means of two shoulders  5  and  6 , moves the bearings  13  of the roller  11  so that they engage suitable semicircular seats  35  formed at the internal surface of the shoulders  2  and  3 , as shown for example in FIGS. 2,  3  and  4 . 
     The second end of the arm  9 , located opposite the end of the arm provided with the seat  10 , has a C-shaped portion  36  which, when the two shoulders  5  and  6  are in the closure position, abuts against the seat  35 , keeping the roller  11  locked in its seat. During closure, the roller  11  slides along the arm  9  until it is seated in a seat  24  of the arm  9  which is formed at the portion  36 . 
     Conveniently, as shown in FIGS. 2,  3 ,  4  and  5 , the means  27  for locking the doctor  26  are conveniently fixed to the cross-member  25  of the printing unit by means of two threaded pins which are provided with a knob  40  in an upward region. 
     During the closure movement, the doctor  26  is arranged at an appropriate fixed angle with respect to the cylinder  11  and the lateral cleaners  60  are arranged adjacent to the lateral surfaces of said cylinder. 
     FIG. 6 is a plan view of the printing unit according to the present invention, illustrating gears which actuate the various cylinders. 
     In particular it should be noted that FIG. 6 illustrates the printing unit in the open condition, in which the cylinder  11  is not in contact with the cylinder  4 . 
     Opposite the cylinder  11  relative to the cylinder  4  there is provided an additional cylinder  41  which is meant to transport the printed paper. 
     A first gear  42  is directly connected to a motor (not shown) for driving the printing unit and engages a second gear  43  which is arranged externally with respect to the cylinder  41  and is rigidly coupled thereto. In turn, the cylinder  41  has a third gear  44  which is arranged at the opposite side with respect to the gear  43  and engages a fourth gear  45  which is rigidly coupled to the printing cylinder  4 . 
     The gear  42  in turn engages a fifth gear  46 , which is instead rigidly coupled to the cylinder  11 . 
     The position of the printing cylinder  4  with respect to the footing of the printing unit is adjusted vertically and horizontally by position adjustment means  45  which are actuated by two screws  56 . 
     In practice, the printing unit according to the invention allows, by way of its particular construction, to access the various components very easily, without having to disassemble fixed parts of the printing unit and most of all so as to allow to access each one of the components substantially independently. 
     Following the opening rotation of the two shoulders  5  and  6  (which, as mentioned, are pivoted by means of the pivot  7  to the shoulders  2  and  3  of the printing unit), the user can in fact open the printing unit, and therefore the cylinders  11  and  15  and the doctor supporting assembly, which are rigidly coupled to the shoulders  5  and  6 , move away, with a rotary motion, from the printing cylinder  4  and from the transport cylinder  41 . 
     In this manner it is possible to access the cylinders  11  and  15  and the doctor supporting assembly simply by removing the cylinder  11 , lifting it from its seat  10 , and then removing the inking cylinder  15 , without having to disassemble parts of the machine and, by unscrewing the two knobs  40 , removing the doctor supporting assembly. 
     Since the inking cylinder  15  is soaked with ink and is not easy to handle, it can be removed by means of a tool, shown in FIG.  2  and designated by the reference numeral  50 , which comprises a transverse element with which two arms arranged at 90° are arranged, said arms being conveniently provided, at one end, with a hook-shaped portion  51  which allows to engage each end of the inking cylinder  15  in order to be able to lift it without getting dirty. 
     Likewise, removal of the doctor for cleaning or replacement can be performed rather simply by loosening the knobs  40  and lifting the locking element  27 . 
     Also the ink tray can be removed independently of the other elements. The tray can be removed laterally or from above, so to speak, by simultaneously lifting the inking cylinder  15  and the tray  14  simply with one&#39;s hands or with the aid of a suitable gripping tool, similar to what has been described for the lifting of the cylinder  14 . Grip is applied to the tray, which is accommodated in the appropriately provided seat during the lifting movement. 
     In this manner it is evident that removal of the components of the printing unit, both for replacement and for maintenance thereof, can be performed very simply and rapidly, and this allows, for example in a case such as the one shown in FIG. 7, where a plurality of printing units are present, arranged in series with respect to each other, to perform the entire operation in a very short time, with consequent and evident advantages as regards the printing operation and therefore the costs of the printed end product. 
     In practice it has been observed that the printing unit according to the invention allows to provide a considerable improvement with respect to conventional printing units as regards operations for removing and mounting the components of the printing unit. 
     The printing unit thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may also be replaced with other technically equivalent elements. 
     In practice, the materials employed, so long as they are compatible with the specific use, as well as the dimensions, may be any according to requirements and to the state of the art. 
     The disclosures in European Patent Application No. 99830637.7 from which this application claims priority are incorporated herein by reference.