Apparatus for printing flat media

Abstract

 An apparatus (1) for printing flat media comprises a frame (2) for supporting at least one medium (S) and a horizontal surface (3) for accommodating at least one printing plate (4), which is provided with an impression to be printed on the medium and can move in a reciprocating fashion toward and away from the medium, a compact inking assembly (5) that cooperates with at least one inking roller (6) that can move in a reciprocating fashion parallel to the surface, and means (7) for the temporary coupling of the compact inking assembly (5) to the frame (2).

Description

[0001] The present invention relates to an apparatus for printing flat media.

[0002] It is known to use apparatuses for printing flat media of various kinds constituted for example by ribbons or sheets of paper, plastics, metal, glass, or other materials.

[0003] In particular, apparatuses are known which are provided with inking assemblies for distributing ink on movable rollers, known as inking rollers, which are suitable to perform a translational motion and transfer the ink onto appropriate printing plates, which in turn print on said media by contact.

[0004] Such apparatuses are often associated with packaging machines, which feed the medium to be printed at the inlet and remove the printed medium at the outlet.

[0005] The printing techniques used by known kinds of apparatus vary according to the type of medium on which printing is performed.

[0006] For example, in the case of printing on porous and absorbent media, such as paper, apparatuses are used in which the inking assembly comprises a pre-inked cartridge, which transfers the ink onto the inking roller by means of a distribution roller.

[0007] In the case instead of non-absorbent supports, such as plastics, glass, metal or other materials, so-called quick-drying inks are usually used.

[0008] In this case, the inking assembly employs a liquid ink printing system and comprises a tray for containing the ink, which is fed from external containers by means of ducts.

[0009] A motorized dip roller, by rotating tangentially to the free surface of the tray, transfers the ink to a distribution roller, which in turn distributes it by contact on the outer surface of the inking roller.

[0010] These apparatuses are very bulky, due to the presence of the containers and of the corresponding ducts; moreover, every time the type or color of the ink to be used is changed it is necessary to perform delicate operations for cleaning in place the inking assembly and the corresponding feed ducts, with inevitable risks of contaminating the work environment.

[0011] The problem becomes particularly important if one considers that these apparatuses are generally employed inside white rooms in industries, for example, of the food or biomedical sector.

[0012] Therefore, known types of apparatus are not free from drawbacks, including the fact that in order to print on media of various kinds it is sometimes necessary to have available both apparatuses preset for the liquid-ink system and apparatuses preset for the pre-inked cartridge.

[0013] This fact inevitably entails greater investments and also requires the availability of more space within production facilities.

[0014] The aim of the present invention is to eliminate the drawbacks mentioned above of known apparatuses, by providing an apparatus for printing flat media that allows to achieve greater flexibility in printing lines, adapts easily to the various kinds of medium, and allows to replace easily the type or color of the ink, at the same time reducing the risks of contamination of the surrounding work environment.

[0015] This aim is achieved by the present apparatus for printing flat media, comprising a supporting frame for at least one medium and a horizontal surface for accommodating at least one printing plate that bears an impression to be printed on said medium and is allowed to move in a reciprocating fashion toward and away from said medium, characterized in that it comprises a compact inking assembly that cooperates with at least one inking roller that is allowed to move in a reciprocating fashion parallel to said surface and means for temporarily coupling said compact inking assembly to said frame.

[0016] Further characteristics and advantages of the present invention will become better apparent from the following detailed description of a preferred but not exclusive embodiment of an apparatus for printing flat media, illustrated by way of non-limitative example in the accompanying drawings, wherein:

Figure 1 is a partial schematic front view of an apparatus for printing flat media according to the invention;

Figure 2 is a schematic side view of the apparatus according to the invention;

Figure 3 is a partial perspective view of the apparatus according to the invention;

Figure 4 is a perspective view of an embodiment of a compact inking assembly of the apparatus according to the invention;

Figure 5 is a perspective view of an alternative embodiment of the compact inking assembly of the apparatus according to the invention;

Figure 6 is a partial perspective view of the assembly of Figure 5;

Figures 7 and 8 are two partial sectional views of the apparatus according to the invention, respectively during the forward and return stroke of the inking roller;

Figure 9 is a partial sectional view of the apparatus according to the invention with the surface in the printing configuration;

Figure 10 is a partial perspective view of the apparatus according to the invention.

[0017] With reference to the figures, the reference numeral 1 generally designates an apparatus for printing flat media.

[0018] The apparatus 1 comprises a frame 2 for supporting at least one medium S and a horizontal surface 3 for accommodating at least one printing plate 4, which is provided with an impression to be printed on the medium S and can move with a reciprocating motion toward and away from the medium.

[0019] Advantageously, the apparatus 1 comprises a compact inking assembly 5, which cooperates with at least one inking roller 6 that is arranged above the surface 3 and is allowed to move in a reciprocating fashion parallel to it, and means 7 for the temporary coupling of the compact inking assembly 5 to the frame 2.

[0020] The frame 2 is of the type having a box-like body and comprises two mutually opposite walls 8 that are parallel to the direction T of the translational motion of the inking roller 6.

[0021] The temporary coupling means 7 comprise two seats 9, which are formed in the end portions of the walls 8 and detachably accommodate the compact inking assembly 5.

[0022] Each seat 9 is constituted by an S-shaped slot, which is provided with two straight portions 9a that are connected by means of a curved portion 9b.

[0023] The compact inking assembly 5 comprises two coupling elements 10, which are constituted by rods that lie transversely to the direction T and whose end portions can be inserted in the seats 9.

[0024] The compact inking assembly 5 comprises a secondary frame 11 for supporting at least one distribution roller 12 and feeder means 13.

[0025] The distribution roller 12 has a rubber lateral surface and is interposed between the feeder means 13, from which it receives ink, and the inking roller 6, to which it transfers the ink by contact.

[0026] In the inking roller 6, the lateral surface is patterned, for example made of steel, in order to facilitate the transfer of the ink to the printing plate 4.

[0027] Advantageously, there are two alternative embodiments of the feeder means 13 of the distribution roller 12: the first one employs a pre-inked cartridge, and the second one employs liquid ink.

[0028] In both cases, the feeder means 13 are independent and the compact inking assembly 5 is a single body that is easy to handle.

[0029] In the first embodiment, the feeder means 13 comprise a pre-inked cartridge 14, which is supported by the secondary frame 11 so that it can rotate and is arranged parallel to the distribution roller 12 and below it.

[0030] The cartridge 14 and the distribution roller 12 are arranged mutually in contact so as to allow transfer of ink from one to the other.

[0031] In the second embodiment, the feeder means 13 comprise a tank 15 for containing the ink, a tray 16 that is arranged above the tank 15 and is connected thereto, a predefined layer of ink being maintained in such tray by means of a pumping assembly 17 that is associated with the secondary frame 11, a dip roller 18 that is supported so that it can rotate by the secondary frame 11 inside the tray 16 and is arranged parallel to the distribution roller 12 and below it.

[0032] The dip roller 18 has a patterned lateral surface made for example of steel, in order to facilitate the transfer of the ink, and is arranged in contact with the distribution roller 12 so as to allow to transfer ink from one roller to the other.

[0033] The tank 15 is provided with an opening 19 for topping up the ink, and a device 20 for indicating the level of the ink in the tank is provided.

[0034] The tank 15 and the tray 16 are mutually integrated and are connected by means of an opening, not shown, that is provided on the bottom of the tray 16 and above which, at a certain distance, there is a lamina 21 that avoids ink splashes within the tray.

[0035] Slots 23 for accommodating the dip roller 18 and the distribution roller 12 are provided on two opposite lateral walls 22 of the tray 16.

[0036] The dip roller 18 is partially immersed in the layer of ink contained in the tray 16, so as to entrain the necessary quantity thereof to be transferred to the distribution roller 12.

[0037] The distribution roller 12 is keyed rigidly to a secondary shaft 24, which can be associated with means 25 for producing a rotary motion that are rigidly coupled to the frame 2.

[0038] The compact inking assembly 5 comprises means 26 for transmitting the rotary motion from the shaft 24 to the feeder means 13.

[0039] The distribution roller 12 receives its rotary motion by means of a first gear 27, which is rigidly keyed to an end of the secondary shaft 24 that is associable with the rotation means 25.

[0040] The transmission means 26 comprise a second gear 28, which is rigidly keyed to the other end of the secondary shaft 24.

[0041] In the first embodiment, the cartridge 14 is rigidly keyed on a second secondary shaft 29, which supports at one end a third gear 30 that meshes with the second gear 28 in order to transmit the rotation to said cartridge.

[0042] In the second embodiment, the dip roller 18 is rigidly keyed on a third secondary shaft 31, which rigidly supports at one end a fourth gear 32 that meshes with the second gear 28 in order to transmit the rotation to the dip roller.

[0043] The inking roller 6 is arranged parallel and tangent to the distribution roller 12, by which it is turned in order to allow uniform distribution of the ink on its lateral surface.

[0044] The inking roller 6 is rigidly keyed to a shaft 33, which is associated with first actuation means 34 and performs a translational motion alternately in the direction T and parallel to the surface 3 between an initial configuration, in which it is arranged proximate to the compact inking assembly 5, and a final configuration, in which it lies on the opposite side with respect to the surface 3.

[0045] The first actuation means 34 are constituted by a pair of hydraulic actuators such as stemless cylinders 35, which are arranged parallel to the direction T and are supported rigidly by the walls 8, their movable heads 36 being associated with the ends of the shaft 33.

[0046] Each end of the shaft 33 is inserted so that it can slide in a fork-like element 37, which is provided with a longitudinal slot 37a at right angles to the surface 3.

[0047] The apparatus 1 comprises guiding means 38, which cooperate in order to keep the inking roller 6 at right angles to the direction T during its motion and comprise two straight guides 39, which are arranged to the sides of the surface 3 and parallel to the direction T and in which respective wheels 40 are inserted so that they can slide, such wheels being keyed so that they can rotate at the ends of the shaft 33.

[0048] The guiding means 38 comprise two racks 41, which are arranged to the sides of the surface 3 and are laterally adjacent to the guides 39 and parallel to the direction T; respective pinions 42 are associated with said racks and are keyed so that they can rotate at the ends of the shaft 33 internally with respect to the wheels 40.

[0049] The guiding means 38 are associated with second actuation means 43, which allow them to move alternatively at right angles to the surface 3 between a configuration in which they are closer to the surface and a configuration in which they are spaced from the surface.

[0050] The second actuation means 43 comprise a plurality of hydraulic actuators 44, which are distributed along the guiding means 38 and below them, their movable pistons being fixed to respective plates 45 that are rigidly associated with the guides 39 and with the racks 41.

[0051] Two disks 46 are rigidly keyed to the shaft 33 proximate to the ends and are laterally adjacent to the inking roller 6 and superimposed on respective abutment profiles 47 that protrude from the surface 3.

[0052] During the forward stroke of the inking roller 6, the guiding means 38 are in the spaced configuration, in which the inking roller 6 and the disks 46 are spaced from the surface 3, while during the return stroke of the inking roller 6 the guiding means 38 are in the closer configuration, in which the inking roller 6 is tangent to the printing plate 4 and the disks 46 are in contact with the respective profiles 47.

[0053] The surface 3 is associated with third actuation means 48, which transmit to it an alternating translational motion in a vertical direction between an inactive configuration, in which it is lowered, and a printing configuration, in which it is raised and presses the printing plate 4 in contact with the medium S against an upper wall 49 of the frame 2, which acts as an abutment.

[0054] The third actuation means 48 comprise a hydraulic cylinder 50, whose movable stem 51 is associated with the surface 3.

[0055] Vertical sliding guides, not shown, can be associated with the surface 3 and cooperate with the cylinder 51.

[0056] Conveniently, there are means 52 for the stepwise advancement of the medium S, which keep it tensioned and parallel to the surface 3 tangent to the upper wall 49.

[0057] The advancement means 52 are of the type of a system of tensioning rollers 53, which feed in input the medium S to be printed and remove in output the printed medium S through a pair of facing slots 54 provided in the walls 8 transversely to the direction T.

[0058] The operation of the invention is as follows: the distribution roller 12 receives from the feeder means 13 the ink, which is transferred by contact to the inking roller 6 in the initial configuration, while the guiding means 38 are in the lowered configuration and the surface 3 is in the inactive configuration.

[0059] During the forward stroke, the inking roller 6 is kept spaced from the printing plate 4 by the guiding means 38 in the raised configuration.

[0060] During the return stroke, the guiding means 38 are in the lowered configuration and the inking roller 6 transfers ink onto the printing plate 4, which rests on the surface 3; in this step, the disks 46, by resting on the profiles 47, ensure that the inking roller 6 remains tangent to the engraved surface of the printing plate 4.

[0061] When the inking roller 6 has returned to the initial configuration, the surface 3 rises and assumes the printing configuration, pressing the printing plate 4 onto the medium S against the upper wall 49, and then moves downward again.

[0062] The operations for cleaning, maintaining and replacing the compact inking assembly 5 are simplified considerably, since it is easy and quick to extract.

[0063] In an alternative embodiment it is possible to arrange the surface 3 above the inking roller 6, with the printing plate 4 directed downward, and the medium S arranged below the roller 6.

[0064] The use of hydraulic actuation means for the translational motion of the inking roller allows to achieve faster printing, higher printing quality and reduced maintenance.

[0065] In practice it has been found that the described invention achieves the intended aim and objects.

[0066] The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

[0067] All the details may further be replaced with other technically equivalent ones.

[0068] In practice, the materials used, as well as the shapes and the dimensions, may be any according to requirements without thereby abandoning the scope of the protection of the appended claims.

[0069] The disclosures in Italian Patent Application No. MO2002A000058 from which this application claims priority are incorporated herein by reference.

[0070] 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 interpretation of each element identified by way of example by such reference signs.

Claims

1. An apparatus for printing flat media, comprising a frame for supporting at least one medium and a horizontal surface for accommodating at least one printing plate, which is provided with an impression to be printed on said medium and can move in a reciprocating fashion toward and away from said medium, characterized in that it comprises a compact inking assembly that cooperates with at least one inking roller that can move in a reciprocating fashion parallel to said surface and means for the temporary coupling of said compact inking assembly to said frame.

2. The apparatus according to claim 1, characterized in that said frame comprises at least two mutually opposite walls that are parallel to the direction of the translational motion of said inking roller, and in that said means for temporary coupling are constituted by at least one pair of seats formed in said two walls and in which said inking assembly is detachably accommodated.

3. The apparatus according to one or more of the preceding claims, characterized in that each seat is constituted by a contoured slot and in that said inking assembly is provided with at least one coupling element that can be inserted in said seats.

4. The apparatus according to one or more of the preceding claims, characterized in that said compact inking assembly comprises a secondary frame for supporting at least one distribution roller that is supported so that it can rotate and is suitable to transfer ink to said inking roller, and means for feeding the ink toward said distribution roller, which is interposed between said feeder means and said inking roller.

5. The apparatus according to one or more of the preceding claims, characterized in that said feeder means comprise a tank for containing the ink, a tray arranged above said tank and connected thereto, in which a predefined layer of ink is maintained, a pumping assembly that is associated with said secondary frame and is suitable to transfer the ink from the tank to the tray, a dip roller that is arranged substantially parallel to said distribution roller and is supported so that it can rotate by said secondary frame inside said tray, the dip roller and the distribution roller being arranged substantially in contact with each other in order to allow the transfer of ink from one roller to the other.

6. The apparatus according to one or more of the preceding claims, characterized in that said feeder means comprise a pre-inked cartridge that is arranged substantially parallel to said distribution roller and is supported so that it can rotate by said secondary frame, the pre-inked cartridge and the distribution roller being arranged in mutual contact so as to allow the transfer of ink from one roller to the other.

7. The apparatus according to one or more of the preceding claims, characterized in that said distribution roller is rigidly keyed to a secondary shaft that can be associated with means for producing a rotary motion that are supported by said frame, and in that said compact inking assembly comprises means for transmitting the rotary motion from said secondary shaft to said feeder means.

8. The apparatus according to one or more of the preceding claims, characterized in that said inking roller is arranged substantially parallel to said distribution roller and is rigidly coupled to a shaft that is substantially coaxial thereto and is associated with first actuation means.

9. The apparatus according to one or more of the preceding claims, characterized in that it comprises means for guiding said inking roller that are suitable to keep it at right angles to the direction of translational motion during its motion.

10. The apparatus according to one or more of the preceding claims, characterized in that said guiding means comprise two straight guides, which are arranged to the sides of said surface and are parallel to the direction of the translational motion of said inking roller, respective wheels being inserted slidingly in said guides and being keyed proximate to the opposite ends of the shaft of said roller.

11. The apparatus according to one or more of the preceding claims, characterized in that said guiding means comprise two racks, which are arranged to the sides of said surface and are parallel to the direction of the translational motion of said inking roller, respective pinions being associated with said racks and being keyed proximate to the mutually opposite ends of the shaft of said roller.

12. The apparatus according to one or more of the preceding claims, characterized in that said guiding means are associated with second actuation means, which are suitable to allow them to move alternately between a configuration in which they are closer to said surface and a configuration in which they are spaced from said surface, and in that said surface is associated with third actuation means that are suitable to allow it to move alternately between an inactive configuration and a printing configuration.

13. The apparatus according to one or more of the preceding claims, characterized in that at least one of said first, second and third actuation means is of the hydraulic type.

14. The apparatus according to one or more of the preceding claims, characterized in that proximate to each end of said shaft there is a disk that is rigidly keyed thereto and is superimposed on a respective straight profile that is parallel to the direction of translational motion of said inking roller and protrudes from said surface.

15. The apparatus according to one or more of the preceding claims, characterized in that during the forward stroke of said inking roller said guiding means are in a spaced configuration, in which the inking roller and the disks are spaced from the surface, and in that during the return stroke of said inking roller said guiding means are in the mutually closer configuration, in which the inking roller is tangent to the printing plate and the disks are in contact with the respective profiles.

Drawing