WO2011048465A1

WO2011048465A1 - Movement device for print substrates, and relative printing machine

Info

Publication number: WO2011048465A1
Application number: PCT/IB2010/002666
Authority: WO
Inventors: Sergio Ferrari
Original assignee: Neolt Spa
Priority date: 2009-10-19
Filing date: 2010-10-19
Publication date: 2011-04-28
Also published as: ITUD20090185A1; IT1396089B1

Abstract

A movement device (14) to feed print substrates in a desired direction of fee ("M") comprises at least a drawing roller (18) to cooperate with the print substrate. The drawing roller (18) extends mainly along a longitudinal axis (Y disposed transverse to the direction of feed ("M") and rotates around th longitudinal axis (Y) in concordance with the direction of feed ("M"). The movement device also comprises a suction device (15) operatively associate with the at least one drawing roller (18). The drawing roller (18) provide through holes (35) connected to the suction device (15) and through which relative suction action is exerted on the print substrate, coordinated with th rotation of the at least one drawing roller (18) around the longitudinal axis (Y).

Description

"MOVEMENT DEVICE FOR PRINT SUBSTRATES, AND RELATIVE

PRINTING MACHINE"

FIELD OF THE INVENTION

The present invention concerns a movement device for print substrates and the relative printing machine such as, for example, a so-called "ink-jet plotter", for ink printing.

The print substrates can be of various types, such as for example sheets of paper, sheets of cardboard, light or heavy weave fabrics, and of various sizes, generally not less than an A3 sheet, and than the relative movement device for the print substrates. However, it cannot be excluded that the present invention can also be applied to other types of printing, such as for example laser or silk- screen printing, or also to other processes on the substrates.

BACKGROUND OF THE INVENTION

A printing machine is known, such as for example a so-called "ink-jet plotter", for printing on print substrates of various types, such as for example sheets of paper, sheets of cardboard, light or heavy weave fabrics, and of various sizes, generally not less than an A3 sheet.

The printing machine comprises a print unit, to print on the print substrates, and a movement device, able to move the print substrates, before printing or when printing is finished, substantially in a linear manner, through the print unit, possibly in two directions.

One known movement device is for example of the pinch roll type, comprising at least a pair of opposite rolls disposed downstream and possibly upstream of the print unit.

Each pair of rolls consists of a driven drawing roll and a contrasting roll, between which the print substrate advances, exploiting the pressure exerted by the drawing roll on the respective contrasting roll.

A movement device is also known comprising an "unwinding" and a "winding" roller, both driven and disposed respectively upstream and downstream of the print unit, on which the substrates to be processed are respectively unwound before being printed and rewound after printing. One disadvantage of such movement devices is that the rollers come into contact with the printed substrates, with a consequent possibility of damaging the quality of the printing and/or creating printing defects, in particular if the printed substrates have been treated for example with emulsions or have been subjected to particular treatments.

Another disadvantage of such movement devices is that the print substrates, as they are fed forward, are often subjected to displacements, even considerable ones, from a position where they are perfectly taut, to a position that can have wrinkles or creases, thus inevitably leading to printing inaccuracies and mistakes. A movement device is also known that comprises a mobile drawing strip or belt, provided with apertures or holes, on which the print substrates rest and through which a suction force is exerted that selectively retains the print substrates. The substrates thus move through the print unit, adhering to the belt.

One disadvantage of this movement device is it is very complex and therefore very expensive to produce.

Furthermore, the known mobile belt is very bulky, since it is generally oversized so as to be able to draw, if necessary, print substrates of considerable size.

There is therefore a considerable waste of energy, connected to the fact that the belt is moved in its entirety, whether the print substrates occupy the whole belt or only a part of it.

Movement devices are also known that provide to use interchangeable mobile planes for predefined formats of substrates to be printed.

However, this solution entails long re-fitting times, since it is necessary to replace the mobile planes in use according to the sizes of the print substrates.

Drawing devices are also known, for example from DE 100 02 094 Al, GB 2 226 304 A and US 2 753 181 A, that comprise holed rollers, in which however it is not possible to create efficient suction conditions comparable in the slightest to vacuum conditions suitable to produce an effective retaining and drawing action on the substrates.

One purpose of the present invention is to achieve an effective and simple movement device, of limited size, which needs limited maintenance and assistance interventions, and is able to allow savings in both energy and costs. Another purpose of the present invention is to achieve a movement device able to ensure that the print substrates, when they are made to advance, keep their desired position and remain taut, so as to have high and repeatable printing quality.

Another purpose of the present invention is to ensure that the print substrates are not touched along the printed area and, at the same time, to allow the print to dry more quickly.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

In accordance with the above purposes, a movement device according to the present invention can be used in a printing machine on print substrates, to feed the print substrates in a desired direction of feed.

The movement device comprises at least a drawing roller able to cooperate with the print substrate, which extends mainly along a longitudinal axis disposed transverse to the direction of feed and is able to rotate on itself around the longitudinal axis in concordance with the direction of feed.

According to one feature of the present invention, the movement device also comprises a suction device, operatively associated with the at least one drawing roller. The drawing roller has through holes connected to the suction device and through which a relative suction action is exerted on the print substrate, coordinated with the rotation of the drawing roller around the longitudinal axis.

The combination of rotation and suction thus determines the desired and reliable feed of the print substrate, without impairing the quality of the printed area.

Indeed, the suction keeps the desired position of the substrates and ensures that they remain taut, so as to have high and repeatable printing quality.

According to a variant embodiment of the present invention, the drawing roller has inside it at least a suction chamber connected to the suction device; the through holes put the suction chamber both with the outside and also with the suction device.

A suction action, able to promote the adherence of the print substrate present on the printing plane and the drawing roller able to rotate, is exerted through the holes, in particular those which in normal use are facing toward the printing plane.

In some preferential forms of embodiment, the suction holes are distributed uniformly over the whole external surface of the drawing roller, that is, both on the length and also on the circular peripheral perimeter of the roller.

According to another variant of the present invention, the movement device comprises several drawing rollers associated in drawing modules aligned along the relative axes.

The solution with drawing modules allows to manage the feed front of the print substrates, sectoring and/or choking the suction according to the sizes or formats of the print substrates to be moved, with a considerable energy saving. In particular, some forms of embodiment of the present invention provide that the movement device comprises valves or other stream interception/regulation members, in order to regulate the suction action exerted by the suction device, so as to be able to divide into sectors and/or choke the suction along the front of the drawing modules, according to needs.

According to another variant of the present invention, in which the direction of feed defines, in correspondence with a printing area, a printing plane, the at least one drawing roller is housed inside a first containment element that has an oblong window that opens at least toward the printing plane and conformed to achieve a planar continuity between the printing plane and the external surface of the drawing roller.

By "planar continuity" we mean that the window lies on a plane parallel to the printing plane, so as to accompany and support the substrate near the roller, keeping it taut and preventing any wrinkles or creases being created upon it.

According to another variant of the present invention, the oblong window is of such a size that it leaves visible a limited portion of the external cylindrical surface of the drawing roller. The visible surface portion, due to its limited width, can be approximately considered similar to plane and parallel to the printing plane.

In this way, when the substrate advances on the visible portion of the drawing roller, no wrinkles or creases are formed on the print substrate, which remains perfectly taut.

According to another variant of the present invention, the first containment element is at least partly housed inside a second containment element, said second containment element being directly connected to said suction device and the first containment element having a plurality of apertures for the passage of air from the through holes of the drawing roller to the suction device.

According to another variant of the present invention, the device according to the present invention comprises at least a holed plate associated with the printing plane and also connected to the suction device and cooperating in depression with the print substrate transiting over it, so as to assist the drawing roller in the feed of the print substrate.

Another feature of the present invention concerns a machine for printing on print substrates, which comprises a printing area, associated with a print unit, and a movement device, able to feed the print substrate in a desired direction of feed through the printing area.

The movement device comprises at least a drawing roller able to cooperate with the print substrate, which extends mainly along a longitudinal axis disposed transverse to the direction of feed and able to rotate around said longitudinal axis in concordance with the direction of feed.

According to a variant of the present invention, the at least one drawing roller is downstream of the printing area.

According to another variant of the present invention, at least one drawing roller can also be located upstream of the printing area for a better tensioning of the print substrate. BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a lateral view of a movement device according to the present invention associated with an ink-jet plotter;

- fig. 2 is a three-dimensional view of a part of the device in fig. 1 ;

- fig. 3 is a three-dimensional view of an enlarged detail of fig. 2;

- fig. 4 is a view in separate parts of fig. 3;

- fig. 5 is a view from below of a part of the enlarged detail in fig. 4;

- fig. 6 is a lateral view of the part in fig. 5.

DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF

EMBODIMENT

With reference to fig. 1, a printing machine 10, in this case a so-called "ink-jet plotter", according to the present invention is used for ink printing on substrates of various types, such as for example sheets of paper, sheets of cardboard, light or heavy weave fabrics, and of various sizes, generally not less than an A3 sheet.

The machine 10 comprises a print unit 11 for printing on said substrates, provided with printing components, in this case for ink printing on said substrates, including a plurality of print heads 12, disposed in correspondence with a printing area 33 through which the print substrates to be printed pass.

In particular, the substrates are made to advance in a predefined direction of feed "M" (fig. 1), from an entry section to the printing area 33, in which the print substrates still have to be subjected to printing, toward an outlet section from the printing area 33, when they have been printed.

The substantially linear movement of the print substrates defines, in correspondence with the printing area 33, a printing plane "P" (fig. 1).

As shown in fig. 1, downstream of the printing area 33, below the print heads 12, the machine 10 provides a movement device 14, able to feed the substrates forward in the direction of feed "M", possibly before printing is carried out and in any case after printing has been done.

The movement device 14 comprises drawing rollers 18 and a suction device 15 operatively connected to the drawing rollers 18. The drawing rollers 18 extend mainly along a longitudinal axis Y, each one able to be put directly in contact with the print substrate, substantially flush with the printing plane "P"₅ and positioned with its axis Y perpendicular to the direction of feed "M".

Each drawing roller 18 is able to rotate, driven by actuation means 20, around the longitudinal axis Y in concordance with the direction of feed "M", as indicated by the arrow "N" in fig. 1. According to requirements, the direction of rotation can also be inverted.

Each drawing roller 18 is hollow and has a suction chamber 36 inside it, with a substantially axial development, connected to the suction device 15.

Furthermore, each drawing roller 18 has a plurality of through holes 35, advantageously made according to a regular geometric disposition along the whole cylindrical lateral surface of the drawing roller 18 and therefore open toward the printing plane "P" and toward the inside of the drawing roller 18, so as to put the suction chamber 36 in communication both with the outside and also with the suction device 15.

In this way a suction action is exerted through the through holes 35, able to promote adherence of the print substrate present on the printing plane "P" and the drawing roller 18 able to rotate, so that the print substrates are drawn by the drawing roller 18 in rotation in the direction of feed "M".

The suction action is carefully calibrated so as to function as a retaining force on the drawing roller 18, as much as is necessary so that the drawing roller 18, rotating, makes the print substrate advance progressively after printing has been carried out.

Consequently, the number of through holes 35 per surface unit of the drawing roller 18 is directly correlated to the effectiveness of the movement exerted by the drawing roller 18 on the print substrates. ·

The number of through holes 35 present on the drawing roller 18 can also depend on the consistency and weave of the fabric to be fed.

Moreover, the suction action exerted through the holes 35 advantageously allows to dry the ink on the printed print substrates more quickly.

In this case, each drawing roller 18 is housed inside a containing cylinder 19 (fig. 3). In the solution shown in fig. 2, the drawing rollers 18, in the respective containing cylinders 19, are disposed adjacent, with their longitudinal axes Y aligned, so as to define a drawing front formed by a plurality of contiguous drawing modules 16, perpendicular to the direction of feed "M".

The number of drawing modules 16 provided generally depends on the sizes and weight of the print substrates.

As shown in figs. 2, 3 and 5, each containing cylinder 19 has an oblong window 21 located substantially flush with the printing plane "P" and able to put the inside of the containing cylinder 19 in communication with the outside.

The oblong window 21 is conformed to achieve a planar continuity of the printing plane "P" and the external surface of the drawing roller 18, so as to prevent the formation of creases and/or wrinkles on the print substrates as they are fed and, consequently, printing mistakes or inaccuracies.

Furthermore, the window 21 has a width, in the direction of feed "M", such as to leave uncovered a limited portion of the drawing roller 18 lying inside the containing cylinder 19, so that the portion can be approximated to a surface plane and substantially parallel to the printing plane "P".

In this way, the print substrates passing on the drawing module 16 are affected by the depression exerted by the through holes 35 in correspondence with the window 21, preventing the formation of creases and/or wrinkles on the print substrates as they are fed, immediately before and immediately after the drawing roller 18, and so as to have a perfectly taut print substrate.

At each of the two ends of the drawing roller 18 an internal flange 32 and a bearing 30 are mounted, as shown in fig. 4. Outside each bearing 30, at each end of the containing cylinder 19, an external flange 31 is mounted, as shown in fig. 4.

The containing cylinder 19 also has a plurality of apertures 22, disposed below the printing plane "P" so as to put the drawing roller 18 housed inside it in fluid communication with a second containment element, in this case a tank 25, mounted below the containing cylinder 19, as shown in figs. 1 and 2, which in turn is connected to the suction device 15.

The tank 25 is attached lateral to the containing cylinder 19 by means of a plurality of attachment elements 24, each associated and cooperating with a respective through hole 23, made for this purpose on the containing cylinder 19. The suction device 15 comprises a vacuum suction pump 17 to generate a vacuum, suitably sized, and connection means able to achieve a suction channel for connection with each module 16.

The direction of suction is indicated by the arrows "L" in fig. 2 and goes from the chamber 36 of each drawing module 16 to the suction pump 17, from which the stream taken in is subsequently expelled to the outside.

In particular, in this case, the connection means associated with each module 16 comprise a tube 26, connected to one end of the tank 25. The tubes 26 converge, through connector elements 28, toward a single collector tube 27 which connects all the drawing modules 16 to the suction device 15.

Each tube 26 is provided with a regulation valve 29 which, acting on the section of the respective tube 26, chokes or can close the delivery of the stream sucked in, directed from the suction chamber 36 toward the pump 17. This choking action is directly correlated to the suction force generated through the holes 35 and allows it to be regulated, also over the whole front defined by the adjacent drawing modules 16. In this way, according to the sizes or formats of the print substrates, by acting suitably on the regulation valves 29 it is possible to exclude some drawing modules 16 and/or to regulate their suction force, adapting as desired the drawing action according to effective needs, with a considerable energy saving.

By means of the tubes 26 and the collector tube 27, the suction pump 17 is able to create a depression inside the tank 25 and, by means of the apertures 22 and the through holes 35, also inside the suction chamber 36 so as to have the relative and desired effect of drawing and adherence of the print substrate.

It is clear that modifications and/or additions of parts may be made to the movement device 14 for print substrates and the relative printing machine 10 as described heretofore, without departing from the field and scope of the present invention. It is also clear that, although the present invention has been described with reference to some examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of movement device for print substrates and the relative printing machine, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

Claims

1. Movement device to feed print substrates in a direction of feed ("M") toward a printing area (33) defining a printing plane (P), the device comprising at least a hollow drawing roller (18) defining inside it a suction chamber (36), said roller (18) being disposed substantially transverse to the direction of feed ("M") and rotating around the longitudinal axis (Y) in concordance with the direction of feed ("M"), said movement device also comprising a suction device (15) operatively associated with said roller (18), said roller (18) providing through holes (35) connected to said suction device (15) in order to exert a suction action on the print substrate, coordinated with the rotation of said at least one roller (18), wherein said roller (18) is housed inside a first containment element (19) which has an oblong window (21) that opens toward said printing plane ("P") and achieves a planar continuity between the printing plane ("P") and the external surface of the roller (18), characterized in that said first containment element (19) is housed inside a second containment element (25), and in that said suction device (15) comprises a vacuum suction pump (17) to generate a vacuum and connection means (26) that connect said pump (17) to said second containment element (25) in order to generate a depression inside said second containment element (25) and, through said through holes (35), also inside the suction chamber (36) of the roller (18) so as to obtain the adherence and drawing of the print substrate.

2. Device as in claim 1, characterized in that said first containment element (19) has a plurality of apertures (22) for the passage of air from the through holes (35) of the drawing roller (18) to the suction device (15).

3. Device as in claim 1, characterized in that said through holes (35) put said suction chamber (36) in communication both with the outside and also with said suction device (15).

4. Device as in claim 1, characterized in that it comprises several drawing rollers (18) associated in drawing modules (16) aligned along the relative axes (Y).

5. Device as in claim 1, characterized in that the oblong window (21) of the first containment element (19) has a width such as to leave visible a limited portion of cylindrical external surface of the drawing roller (18) substantially comparable to a plane and parallel to the printing plane ("P").

6. Device as in claim 1, characterized in that it comprises at least a holed plate (13) associated with the printing plane ("P") and connected to the suction device (15) so as to cooperate in depression with the print substrate passing on it.

7. Device as in any claim hereinbefore, characterized in that it comprises valves (29) to regulate the suction action exerted by the suction device (15).

8. Machine for printing print substrates, comprising a movement device to feed the print substrates having the characteristics as claimed in claim 1.

9. Printing machine as in claim 8, characterized in that the at least one drawing roller (18) is downstream of the printing area (33).

10. Printing machine as in claim 8 or 9, characterized in that at least one drawing roller (18) is also located upstream of the printing area (33) for a better tensioning of the print substrate.