EP0363662B1 - Device for advancing plate-like articles in a rotary printing machine - Google Patents

Abstract

The device comprises a horizontal frame consisting of two lateral longitudinal members (200, 201) connected to one another by means of cross-members (202). Transverse shafts (230) equipped with driving rollers (240) are mounted between the lateral longitudinal members (200, 201). The driving rollers (240) are designed so that the lower part of their circumference projects beyond the plane defined by a perforated lower plate (260), the orifices of which are arranged so as to leave a gap all round the projecting part of the driving rollers (240). A suction hood (300) is arranged above the horizontal frame in order to cause the plate-like articles (130) to be sucked against the projecting part of the driving rollers (240). <??>The present device is used for transporting printed sheets in a multicolour printing machine. <IMAGE>

Description

The present invention relates to a device for transporting plate elements in a rotary printing machine in several colors for plate elements, more particularly for thick or corrugated cardboard elements.

In practice, such machines have large dimensions of the order of 5 m long by 3 m wide and may include a feeding station, several printing stations for a full color result, and, if necessary, a cutting station, an ejection station and a final station for receiving plate elements. When operating such machines, it is necessary to be able to access the interior of the printing stations: either to change photographs on the printing cylinder, or to make various ink settings, or, finally, to clean the distributor rolls and inkwells.

In order to be able to carry out the operations mentioned above, the majority of current machines are installed on two longitudinal rails. It is then possible to disconnect the links between two consecutive printing stations, then to separate the two upstream and downstream parts of the machine opening a passage through which an operator can enter. It is even possible on certain machines to pull a printing station completely aside from the assembly allowing easy access and work on Rolls; Coils. These solutions involving displacement of stations become inadequate for larger machines by the number of links to be undone and by the weight of the respective stations.

For the latter type of rather large machine, the manufacturer prefers to create a permanent free space then completed with a device for transporting the sheets from one printing station to the next. Obviously, such a conveyor device must be adjustable according to the width and thickness of the cardboard sheets to be transferred. The device currently used comprises a horizontal frame carrying a series of striated trees orthogonal to the direction of movement of the leaves. Two side members carry transport rollers arranged opposite each striated shaft. These two beams are kept symmetrical in a lateral function defined with respect to the longitudinal axis of the machine. These beams are supported by two transverse shafts intended, on the one hand, to maintain the vertical position of the beams and, on the other hand, to drive the transport rollers. The lateral movement of the side members is ensured by threaded pins acting in pairs on each of the side members. Thus, by action on the threaded axes, it is possible to bring these spars together or apart so that the transport rollers are brought to a location corresponding to the one desired, for example either on the edges not printed on the sheet or, as far as possible, in any other place allowing transport without smudging. Furthermore, the vertical position of the upper frame carrying the striated trees can be adjusted so that the distance between these trees and their respective rollers is a function of the thickness of the sheet.

As described, the latter device has many drawbacks. As can easily be understood, it is obvious that the two lateral edges or the places on which the transport rollers and the ridged shafts act must be free to print if the transported sheet is not to be smudged.

In the case of transporting the sheet on its printed edges, there is smudge. To avoid this, the width of the sheet should be increased so as to obtain transport over a free printing area. This of course corresponds to an undesirable waste.

Another disadvantage of this kind of transport of the sheet, whether by its edges or by any other place, resides in the fact that the pinching force necessary for driving the sheet can cause, depending on the quality of the carton. , a crush marking the sheet, which is not acceptable with regard to the finished product produced from said printed sheet.

A third drawback lies in the fact that in use it appears that the adjustments of this device as a function of the width and of the thickness of the sheet are tedious. Indeed, if it is easy to motorize the lateral movement of the side members, the adjustment of the vertical position of the cradle cannot be done with sufficient precision than mechanically, by a large set of cams, pinions and levers. As with any adjustment, several tests should be carried out followed by corrections to obtain a satisfactory result. Even after such adjustments made with seriousness, it is not impossible that the longitudinal and lateral adjustment of certain sheets may change during production. Last but not least, this device involves significant mechanics, thereby increasing the production costs and reducing in a certain way the accessibility in the upper part of the printing stations precisely at the level of the contact between the pressure roller and the door roller. - shots.

Document NL 275 252 discloses a device installed at the outlet of a cutting station, this device comprising a vacuum box surmounted by a suction pump and the underside of which is perforated with a mesh of orifices. A plurality of endless bands, guided by rollers located at the ends of the box, pass along the lower face to return by the upper face. The blanks delivered on a mobile table are lifted by suction through the mesh of holes or orifices to come to press against the endless conveyor belts and to be thus transported to another conveyor.

If this device makes it possible to transport cutouts without the risk of tearing or crushing, it is very quickly noted that the prior lifting of this cutout out of the table furnished with knives requires a minimum depression which is nevertheless significant, which is necessarily found behind the strips without end significantly increasing their friction forces, therefore the mechanical energy to be transmitted by the toothed wheel to the first roller. In addition, it is known that long endless bands moving at high speed can vibrate. The vertical component of the vibrations could then take off the sheets which would fall prematurely, and the lateral component could appreciably affect the lateral position of the sheet at the end of the transport. Such a device is therefore necessarily reserved for transport over short distances and at relatively reduced speed.

Furthermore, document DE 2 946 960 discloses a device using suction to introduce sheets into a photocopier or a fax machine, this introduction consisting of a first operation of lifting the first sheet from a stack, then a second transport operation to downstream drive rollers. This device comprises a box containing two axes transverse to the movement of the sheet, each provided with a series of driving rollers arranged side by side. These axes are rotated by an endless belt set in motion by a pulley and a motor. The underside of this box has large holes in the shape of comb teeth so that the lower part of the circumference of the rollers emerges from the box downwards. This box further includes a fan to create a depression sufficient to suck up and lift the first sheet of a pile which then wraps all of the emerging part of the first roll.

However, if we try to adapt this device to the transport of plate elements in a rotary printing machine while respecting the proportions of the large openings with respect to the axes fitted with rollers and applying a minimum vacuum necessary to lift the elements, these would undoubtedly be pressed against the perforated surface, and could never have advanced or would have been damaged. Indeed, these plate elements would have been damaged following the warping due to this cladding, which is unacceptable in the field of the present patent application.

The object of the present invention is to provide a device for transporting plate elements in a rotary machine for printing plate elements which is efficient, that is to say rapid and without any possibility of longitudinal and lateral deviation. plate elements. It is moreover desirable that the operator is freed from any adjustment on the transport device itself, or that, if an adjustment is necessary, it is directly carried out by an adjustment normally applied to the corresponding printing stations. Finally, this device must give off a better volume of accessibility between the cylinders of the printing stations, this volume possibly being able to be used to carry out additional operations such as drying for example.

To this end, the present invention relates to a device for transporting plate elements as described in claim 1.

According to a first advantageous characteristic, the suction means consist of a fan operating so as to create a vacuum inside the assembly defined by the collector and the horizontal frame closed by the perforated plate, the collector may advantageously be constituted by a plurality of separate boxes and the fan of the variable flow type.

• une roue dentée en chaque extrémité d'arbre située d'un même côté de la machine,
• une suite de pignons montés sur le longeron correspondant et accouplant chaque roue dentée à sa ou ses voisines,
• un organe moteur appliquant un couple de rotation au travers d'une boîte réductrice à la première roue dentée ou au premier pignon.

According to another characteristic, the drive means of the shafts can include:

• a toothed wheel at each end of the shaft located on the same side of the machine,
• a series of pinions mounted on the corresponding spar and coupling each toothed wheel to its neighbor or neighbors,
• a drive member applying a torque through a reduction gearbox to the first gear or to the first pinion.

Preferably, the drive means of the shafts comprise a first series of pinions coupling each toothed wheel which belongs to a first upstream group of shafts to its or its two neighbors, a second series of pinions also coupling to its neighbors, so identical, each toothed wheel which belongs to a second downstream group of shafts. Then, the motor unit applies a torque through a transmission bar to two reduction boxes, each of the boxes animating a series of gears respectively.

• la figure 1 est une vue en perspective du dispositif tel que vu du côté conducteur, et
• la figure 2 est une vue en coupe selon la section I de la figure 1.

The invention will be better understood from the study of an embodiment taken by way of nonlimiting example and described by the following figures:

• FIG. 1 is a perspective view of the device as seen from the driver side, and
• FIG. 2 is a sectional view along section I of FIG. 1.

With reference to FIG. 1, the upper downstream part of a rotary flexographic printing station (100) is illustrated on the right side. One recognizes there in particular a plate cylinder (110) with its corresponding pressing cylinder (120) arranged parallel above. In such a station, the inkwell and the associated dispensing cylinders, not shown for clarity of the figure, are arranged in the lower part of the station. Thus, when an element (130) passes between the plate cylinder (110) and the pressing cylinder (120), it is printed on its underside by the plate (111). As can be seen, the next downstream printing station is not immediately attached to this upstream printing station (100), but an access space (50) provided with the transport device according to the invention is Reserve.

This transport device first comprises a frame essentially consisting of two lateral beams (200, 201) interconnected by a series of crosspieces (202). This frame connects the upper part of the consecutive flexography printing stations. These side rails (200, 201) carry a series of shafts (230), mutually parallel and orthogonal to the direction of movement of the elements (130). So that these shafts (230) are rotatable, their ends are respectively engaged in bearings (210) integrated in the side rails (200, 201).

These shafts (230) have, cut in the mass, a series of driving rollers (240). The surface of these driving rollers can be smooth, ridged or have a projection of ceramic similar to sandpaper. The shafts (230) pass through the lateral spar (201), opposite the conductive side, and are provided, at their respective ends, with a toothed wheel (250) allowing them to be driven in rotation as will be described by the after.

According to an exemplary embodiment taken without any limitation being of a device transferring sheets over a distance of 160 cm, the frame comprises 14 trees (230) with a diameter equal to 7 cm. Each of the shafts (230) carry 9 long rolls of 10 cm, spaced every 5 cm and having an outside diameter of about 9 cm.

A plate (260) is provided to cover the underside of the frame except at the level of rectangular openings through which the lower portion of the drive rollers (240) pass in correspondence. In other words, the bearings (210) are located in the side rails (200, 201) of the frame so that the drive rollers (240) emerge downward from the plate (260). Thus, for a plate (260) to be screwed under the underside of the frame, it must first be pierced with a network of rectangular openings corresponding to the rollers, which openings must have a length slightly greater than that of the rollers. and a width slightly greater than that necessary for the passage of the lower part of these same rollers.

As can best be seen in FIG. 2, taking into account the thickness of the plate (260), the driving roller (240) emerges out of this plate (260). It will also be noted that the downstream edges (265) of these openings are folded upwards, that is to say in the direction of the axis of rotation of the rollers (240). This particular shape of the downstream edge of the opening prevents the front edge of the element (130), driven by the roller (240), from being embedded in the plate at this location. As can be seen, this plate (260) covers in the lower face of the frame the intervals between the rollers (240) leaving a clearance around each emerging lower part of these drive rollers (240).

As shown in FIG. 2, the toothed wheels (250) located at the end of the shafts (230) and at the rear of the side member (201) are driven by a series of pinions (247) which connect them to the toothed wheels neighbors. This gear train is arranged along the beam (201). A driving member, such as an independent electric motor or a shaft for transmitting the driving force of the previous printing station or the driving force coming from the central engine of the machine, is connected by a reduction box to either the first toothed wheel ( 250) or to the first pinion (247). When the number of trees (230) to be animated is greater than approximately 10, it becomes preferable to separate them into two groups, an upstream, a downstream, having a distinct set of gears. However, for questions of rotation coordination, the same driving force must be split, to activate two Separate reduction boxes each meshing with a group of pinions (247) and cogwheels (250). This duplication can be achieved conventionally by a transmission bridge.

Referring to Figure 1, the device further comprises a manifold in the form of a hood (300) covering the upper face of the frame. Directly mounted at the top of this hood, there is a fan (310) which can discharge air through a duct (320). Alternatively, only the duct (320) is connected to the top of the hood (300), and the fan (310) is installed in another more accessible part of the machine. Given the small passage for air, limited to the interstices between the plate (260) and each lower part of the rollers (240), this fan creates in regular operation a vacuum inside this hood. After numerous tests in the workshop, it turned out that a depression of the order of three millibars is sufficient for the proper functioning of the device. It is however possible to provide a variable flow fan allowing this vacuum to be adjusted, if necessary. Obviously, this hood (300) can be subdivided into several smaller boxes, each having its own outlet for extracting air (320) associated with the fan (310) or else with a respective fan.

For this device to function correctly, it is of prime importance that the lower parts of the driving rollers (240) lie in the same horizontal plane as the lower part of the pressure roller (120) of the upstream and downstream rotary printing stations. , that is to say in a plane corresponding to the plane defined by the upper part transported items. In current printing stations, it is normally planned to modify the height of the pressure cylinder relative to the plate cylinder as a function of the thickness of the carton (130). In this case, it suffices to hook the side rails (200, 201) of the frame on either side to the adjustment supports of the pressing cylinders. Then, the adjustment in thickness of the printing stations automatically causes the adjustment in position of the device. Given that, in this case, it is no longer a cylinder which is displaced but an entire device, it may appear advantageous to modify the printing stations by definitively fixing the position of the pressure cylinder, therefore of the transport device according to the invention, and to adjust only the vertical position of the plate cylinder.

As described above, the conveyor device according to the invention operates in the following manner: when the printing machine starts, the fan (310) is also put into operation very quickly creating a vacuum. Then, when the machine is switched on, so that the elements (130) start to advance, the shafts (230) are rotated clockwise. Then, when an element (130) starts to come out of the printing station (100), as illustrated in FIG. 1, its front edge is sucked against the rollers (240). By their rotation, therefore by the forward friction force which they exert, these rollers advance the element. As can best be seen in FIG. 2, the element (130), which is sufficiently rigid, never comes into contact with the plate (260). At most, this element is shaped slightly around driving rollers (240) which increases the thrust force imparted by these rollers. In addition, when the sheet (130) advances below the bottom plate (260), it accordingly reduces the available air intake area in the hood (300), which very quickly causes a depression just at above this sheet. Atmospheric pressure then presses this sheet against the transport device, without there being any possibility of contact with the lower plate (260).

Due to the accuracy of the parallelism between the shafts (230) and the diameter of the rollers (240), and the uniformity of the action of atmospheric pressure on the element (130), it cannot be deviated neither longitudinally nor laterally. This element therefore keeps its alignment as well as its location, determined before passing through the printing stations. It has thus been found, following tests in the workshop, that these elements keep their alignment and their location with sufficient tolerance for quality flexographic printing jobs. Since this precision depends essentially on the conditions of manufacture in the factory and that this device did not require any particular adjustment before its implementation, this reliability of alignment and location during movement cannot be altered over time. Finally, it is very unlikely that debris can in the long term close one of the interstices between the plate (260) and a roller, given that these are always in rotary movement which tends to entrain this debris to the inside the hood where they are discharged.

It will be noted that, unlike the device described in the prior art, no mechanical element is present under the sheet in this device. It then becomes possible, if necessary, to use this space (50) for additional operations such as for example drying. This drying operation only involves the establishment of one or more ramps, underlying the plate (260) and preferably arranged orthogonally to the direction of movement of the sheets.

Many improvements can be made to this device in the context of the invention.

Claims (8)

1. Device for conveying sheets (130), which includes

   - a horizontal frame made of two lateral beams (200, 201) connected to one another by crossbars (202), at least one crosswise shaft (230) held at its ends by the said lateral beams (200, 201), the said crosswise shaft (230) being provided with a series of adjacent drive rollers (240),

   - means ensuring the rotary drive of the crosswise shaft(s) (230),

   - at least one suction device including a collector such as a hood (300) connecting between them the upper sides of each lateral beam (200, 201),

   - a lower plate (260) provided with apertures and fitted against the bottom of both lateral beams (200, 201), the said drive rollers (240) being arranged within a horizontal frame in such a way that the lower part of their circumference protrudes beyond the plane demarcated by the lower plate (260) with apertures,
   and is characterized by the fact that, when such a device is used within a rotary machine for printing plate-shaped cardboard or corrugated board,

   - the lower part of the circumference of every drive roller (240) is situated within a plane demarcated by the upper side of the sheet (130) conveyed through the rotary printing machine,

   - the apertures of the lower plate (260) is arranged in such a way as to leave a small gap all around the protruding part of the drive rollers (240),

   - the upstream edge of every aperture of the lower plate (260) is folded up towards the drive rollers (240), and

   - the said frame includes means allowing to adjust the vertical position of the drive rollers (240) as required by the thickness of the sheets (130).
2. Device according to claim 1, characterised by suction devices consisting of a fan (310) operating in such a way as to produce a vacuum within the assembly consisting of the collector and the horizontal frame closed by the plate (260) with apertures.
3. Device according to claim 1, characterised by the collector consisting of a a certain number of separate compartments.
4. Device according to claim 2, characterised by the fan (310) being of the variable-performance type allowing thereby to adjust the vacuum rate within the assembly consisting of the collector and the horizontal frame closed by the plate (260) with apertures.
5. Device according to claim 1, characterised by means driving the crosswise shaft(s) (230) and comprising

   - a toothed wheel (250) fitted at each end of the crosswise shaft (230) situated on the same side of the machine,

   - a row of pinions (247) connecting each toothed wheel (250) to its neighbouring wheel(s), as well as

   - a motor unit imparting a torque on the first toothed wheel (250) or on the first pinion (247).
6. Device according to claim 5, characterised by

   - the first row of pinions (247) meshing in with each toothed wheel (250) belonging to a first group of crosswise shafts (230) and to its neighbouring wheel(s),

   - a second row of pinions (247) likewise meshing in with every toothed wheel (250) belonging to a second group of crosswise shafts (230), and

   - a moving appliance imparting its torque through a transmission shaft on two reduction gear sets, each of which driving respectively a row of pinions (247) or toothed wheels (250).
7. Device according to claim 1, characterised by means used for adjusting the vertical position of the drive rollers (240) and consisting of a connecting appliance which links the lateral beams (200, 201) to the supports used for setting the position of the impression cylinders (120) of a printing unit (100) of the rotary machine.
8. Device according to claim 7, characterised by means used for adjusting the vertical position of the drive rollers (240) and consisting of a setting appliance determining the vertical position of the printing plate cylinder (110) of a printing unit (100) of the rotary machine.

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