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Field of the invention

The present invention relates to a conveyor for paper tapes for paper processing plants.

Background art

Conveyors for paper tapes are known that use air placed in depression underneath a longitudinally perforated tape conveyor to retain and move thin sheets of material, such as paper or cardboard.

The patent document US3282586A illustrates a conveyor for paper tapes for paper processing plants provided with perforated conveyor belts that run on respective longitudinal conduits, extending in the same direction of movement as the paper tape to form a moving table, which act as collectors for the air in depression.

Moreover, the moving transverse tapes are provided, on the side facing the moving table, with transverse partitions at regular intervals that create chambers for the air in depression and that act as a support for said moving tape.

The main aim of this arrangement is to ensure a constructive embodiment that offers a good hold of the conveyor belt to the air in depression, which therefore ensures that the paper tape conveyed can move integrally with the conveyor belt.

Measures are also implemented to prevent relative movement between the belt and the sheet that is conveyed thereon.

A problem of the known art is represented by the fact that in known solutions, the conveyor belt and the sheet of paper of the paper tape travel without relative movement, which can cause tensions that have repercussions on the machine upstream, for example a printer or plotter, or on the machines downstream, for example a paper cutting machine, which might not be supplied at a steady rate.

Therefore, an object of the present invention is to solve the aforesaid technical problems by means of a conveyor for paper tapes in paper processing plants that offers greater flexibility of use and greater versatility with respect to the known art.

Finally, a further object of the invention is to provide a solution that is simple to produce with limited manufacturing costs.

Brief description of the invention These and other objects are achieved by a conveyor for paper tapes in paper processing plants, where the aforesaid conveyor is configured to be positioned between a paper processing machine upstream of said conveyor and which supplies said paper tape to the conveyor and a paper processing machine downstream of the conveyor and which receives said paper tape from the conveyor, and where the aforesaid conveyor comprises a flatbed on which the paper tape is made to pass over, said flatbed comprising a plurality of belts, the aforesaid belts being movable in the feed direction of the paper tape, and where the aforesaid belts are provided with holes to put the lower surface of the paper tape in fluidic contact with at least one depression chamber created inside the flatbed, and where the feed speed of the belts is slightly greater than the feed speed of the paper tape supplied to the conveyor from the paper processing machine placed upstream of the conveyor.

It should be noted that here and hereunder, the expression “paper” is meant as any material produced with fibres of plant origin in sheets, or tapes, of limited thickness, and can therefore comprise any type of paper or cardboard, for example with weights ranging from 40 g/m2 to 500 g/m2.

An advantage of the invention consists in the fact that, thanks to the claimed difference of speed between belts of the conveyor and speed of the paper tape entering said conveyor, made possible by the absence of means for making the paper tape move integrally to the belts of the conveyor, no tensions are created at the printer and consequently no problems caused by unwanted variations of the feed rate of the paper tape are created.

Moreover, in the case in which a paper cutting machine is provided downstream of the conveyor, this machine is supplied at a steady rate.

A further advantage of the invention is given by the fact that the air in depression is used, as advantageous solution, to avoid tearing or lacerating a sheet supplied continuously.

It should be noted that, according to a particular aspect of the present invention, the conveyor for paper tapes in paper processing plants, where the aforesaid conveyor is configured to be positioned between a paper processing machine upstream of said conveyor and which supplies said paper tape to the conveyor such as, for example, a plotter or printer, and a paper processing machine downstream of the conveyor and which receives said paper tape from the conveyor, and where the aforesaid conveyor comprises a flatbed on which the paper tape is made to pass over, said flatbed comprising a plurality of belts, the aforesaid belts being movable in the feed direction of the paper tape, and where the aforesaid belts are provided with holes to put the lower surface of the paper tape in fluidic contact with at least one depression chamber created inside the flatbed, the contact surface of the aforesaid belts has a low friction coefficient so as not to obstruct a limited relative movement between paper tape and belts and thus preferably, although not necessarily, allow the feed speed of the belts to be slightly higher than the feed speed of the paper tape supplied to the conveyor from the paper processing machine placed upstream of the conveyor.

The invention further comprises a paper processing plant, where the aforesaid plant comprises a conveyor for paper tapes as described in the present invention and the plant comprising at least one plotter (or printer) placed upstream of the conveyor and which supplies the paper tape to the conveyor and one paper processing machine placed downstream of the conveyor and which receives said paper tape from the conveyor.

The plotter or printer placed upstream of the conveyor can be of the type capable of printing graphic patterns, or inscriptions or words on sheets of a paper tape placed initially in a reel that is unwound gradually to allow it to be processed.

In particular, the paper processing machine placed downstream of the conveyor can be a paper cutting machine.

Further features of the invention are apparent from the dependent claims.

Brief description of the figures

Further features and advantages of the invention will be more apparent from reading the description below provided by way of non-limiting example, with the aid of the figures illustrated in the accompanying drawings, wherein:

- Fig. 1 illustrates a side view of a first paper processing plant that incorporates a conveyor according to an embodiment of the present invention;

- Fig. 2 illustrates a side view of a second paper processing plant that incorporates the conveyor of Fig. 1; - Fig. 3 illustrates a side view of a third paper processing plant that incorporates the conveyor of Fig. 1;

- Fig. 4 illustrates an axonometric view of some components of the conveyor according to an embodiment of the present invention;

- Fig. 5 illustrates a detail, in an exploded view, of some components of the conveyor of Fig. 4;

- Fig. 6 illustrates, in an exploded view, some components of the conveyor of Fig. 4;

- Fig. 7 illustrates an axonometric view of the conveyor according to an embodiment of the present invention;

- Fig. 8 illustrates a side view of the conveyor of Fig. 7;

- Fig. 9 illustrates a top view of the conveyor of Fig. 7;

- Fig. 10 illustrates a further side view of the conveyor of Fig. 7; and

- Fig. 11 illustrates a schematic view of the operation of some elements of the conveyor of Fig. 7.

Detailed description of the figures

The present invention will now be described with specific reference to the accompanying figures where, in particular, Fig. 1 illustrates a side view of a first paper processing plant 100, and in particular a plant wherein a paper tape 12 is printed and optionally cut after printing, which incorporates a conveyor according to an embodiment of the present invention, and where the conveyor is indicated as a whole with the reference number 10.

In particular, the plant 100 comprises a plotter (or printer) 110 placed upstream of the conveyor 10, the conveyor 10 in turn conveys a paper tape 12 towards an infrared lamp dryer 120 placed downstream of the aforesaid conveyor 10.

Finally, after having passed through the dryer 120, the paper tape 12 is processed by a paper cutting machine 130, which divides it into printed sheets.

Fig. 2 illustrates a side view of a second paper processing plant 100’ incorporating the conveyor 10 where, in particular, the plant 100’ also comprises a plotter, or printer, 110 placed upstream of the conveyor 10, the conveyor 10 in turn conveys a paper tape 12 towards a winder 140.

Fig. 3 illustrates a side view of a third paper processing plant 100” incorporating the conveyor 10.

The plant 100” comprises a plotter 110 placed upstream of the conveyor 10, the conveyor 10 in turn conveys a paper tape 12 towards a paper cutting machine 130. Therefore, the examples provided with Figs. 1-3 offer a panorama of the wide field of application of the conveyor 10 of the invention.

Fig. 4 illustrates an axonometric view of some components of the conveyor 10 according to an embodiment of the present invention.

In particular, the conveyor 10 has a flatbed 40 on which the sheet of paper processed in the plant 100 or 100’ or 100” runs.

The flatbed 40 has a flat upper plane 48, which in turn has a plurality of longitudinal cavities 42, said longitudinal cavities 42 being configured to accommodate respective belts 55 that, as will be seen, are advantageously provided with holes 57, 57’, or in any case have areas permeable to air, and which are driven by means of end rollers with respect to the flatbed 40.

Through-slots of elongated shape 142, which allow the fluidic communication with the inside of the flatbed 40, are present inside each of the aforesaid longitudinal cavities 42.

Communicating chambers 45, placed in depression as shall be seen below, are present inside the flatbed 40, and which allow a flow of suction air to pass through the slots 142 and from these, through the holes 57, 57’ of the belts 55, to act on the paper tape 12 advantageously arranged on these belts 55.

In other words, the slots of elongated shape 142 allow the fluidic communication between the depression chambers 45 and the outside of the conveyor 10, so that the depression, through the holes 57, 57’ of the belts 55, acts on the paper tape 12.

It should be noted that in the context of the present invention, the term “hole” referred to the belts 55 is meant as any area of these belts that is substantially permeable to air and allows the passage of a flow of suction air, so as to allow the paper tape 12 to be constrained to said belts 55 by suction.

In turn, the belts 55, as mentioned, are arranged in the same feed direction as the paper and are provided with means to be put in translatory movement inside their respective cavities 42. As will be understood by those skilled in the art, these movement means of the belts 55 are of the usual type and can comprise at least one electric motor that is regulated by a related automatic controller and that operates, for example, guide rollers of these belts 55, according to a predefined law of motion.

As will be explained below, these movement means of the belts 55, which can be functionally connected (for example through electrical circuits) to a controller, or a sensor or an actuator, to the movement means of the paper tape 12 of the processing station (for example the plotter 110) placed upstream of the conveyor 10 and optionally also to the movement means of the tape 12 of the processing stations placed downstream of said conveyor 10, advantageously adjust the motion of the belts 55 so that they are placed at a higher speed than that of the paper tape 12, as given by the movement means of the station placed upstream (for example the plotter or printer 110), which is made possible by the fact that the constraint between the paper tape 12 and the upper surface of the belts 55, essentially given by a depression generated by a flow of suction air, allows a limited movement of said tape 12 with respect to the belts 55, when the tensile force exerted by these belts 55 exceeds the release force of the paper tape 12 by the processing station placed upstream, such as for example the plotter 110.

Fig. 4 also illustrates two pumps, or fans, 20,30 the function of which, better explained hereunder, is substantially that of creating a depression inside the flatbed 40, inside the communicating chambers 45.

Fig. 5 illustrates in detail, in an exploded view, some components of the conveyor 10 of Fig. 4.

In particular, the inside of the flatbed 40 shows a structure formed by a plurality of longitudinal cross members 44, where each of the aforesaid longitudinal cross members 44 has a plurality of holes 46, and by two longitudinal members 47, all of which define substantially parallelepiped shaped chambers 45, communicating with one another through the holes 46.

The structure of the flatbed 40 belonging to the conveyor 10 can be appreciated in more detail in the exploded view of Fig. 6, said figure highlighting the upper part defined by the upper plane 48 provided with the aforesaid longitudinal cavities 42 for the belts 55, with the respective through slots 142, and the lower part closed by the sheet metal plane 49, provided with holes for connection to the pneumatic circuits, as well as by lateral closing walls, so that it is understood that the flatbed 40 has a substantially box-shaped structure with lower and upper holes that allow a flow of suction air to pass through them.

Between the upper plane 48 and the sheet metal plane 49, there is a grid structure 43 formed by two longitudinal members 47 by a plurality of cross members 46 each provided with a plurality of holes 46. In lower position with respect to the flatbed 40 there are two pumps 20,30 where each of said pumps supplies a respective pneumatic circuit 22,32.

In particular, the pump 20 supplies the circuit 22 and the pump 30 supplies the circuit 32 so that both the circuits 22,32 coact to create a depression inside the structure of the flatbed 40. The pneumatic circuits 22,32 are independent from each other.

It can be seen that although in the particular embodiment illustrated here the conveyor 10 comprises two pumps 20, 30 and two related independent pneumatic circuits 23, 32 to generate an adequate suction force on the paper tape 12, as those skilled in the art will understand any other number and configuration of the pumps (fans) and of the related pneumatic circuits can be used, without thereby departing from the scope of the present invention.

Fig. 6 also highlights the fact that each of the belts 55 designed to engage inside the cavities 42 is in turn provided with a plurality of holes 57, 57’.

On the upper plane 48 of the flatbed 40 the longitudinal cavities 42 and the related elongated through slots 142 are visible.

Fig. 7 illustrates an axonometric view of the conveyor 10.

In particular, this view illustrates the conveyor 10 with the pumps 20,30 and their respective pneumatic circuits 22,32 in a position below the flatbed 40.

Moreover, a roller 60 is present in a front portion of the conveyor 10 to guide the path of the paper, which, being idle, does not impart any drive to the paper tape.

Fig. 7 also illustrates the belts 55 with the related holes 57, 57’ as mounted on the upper plane 48 of the flatbed 40, inside the respective cavities 42.

Two hydraulic jacks 70 are also provided on the sides of the conveyor 10, the purpose of which is to adjust the position of the flatbed 40 with respect to the horizontal plane, so as to allow the conveyor 10 to be adapted to the processing station placed upstream, for example a plotter, or printer, 110, and in particular to the geometric layout of the output section of the paper tape 12 from this processing station placed upstream (for example the plotter 110).

This allows the conveyor 10 to be coupled to any type of processing station placed upstream, in an extremely simple and flexible manner, so that the conveyor 10 can also be added to pre-existing paper tape processing plants.

Fig. 8 illustrates a side view of the conveyor 10 of Fig. 7, in which the position of the pumps 20,30 and of their respective pneumatic circuits 22,32 is highlighted.

Fig. 9 illustrates a top view of the conveyor 10, in which the position of the belts 55 and of the related holes 57, 57’ is highlighted.

Fig. 10 illustrates a further side view of the conveyor of Fig. 7, in which, among other things, the position of the hydraulic jacks 70 is highlighted.

Fig. 11 illustrates a schematic view of the operation of some elements of the conveyor 10; in particular, Fig 11 is divided so as to indicate three possible operating situations, indicated respectively with I, II and III.

In situation I, during the movement of the belt 55, six holes 57 of said belt 55 are in correspondence with the longitudinal through slots 142, while a further hole, indicated with 57’ is not in correspondence: therefore, only six holes 57 participate in the suction action caused by the depression generated by the pumps 20,30.

In situation II, six and a half holes are in correspondence with the slots 142, and in situation III, seven holes are in correspondence with the longitudinal slots 142. Therefore, it can be seen that, during the movement of each perforated belt 55, at least six holes 57 for each of said belts 55 are placed in simultaneous fluidic communication with the depression chambers 45.

A preferred value of the depression created by the pumps 20,30 inside the depression chambers 45 of the flatbed 40 is 175 mbar or higher, and can, for example, be comprised between 150 mbar and 350-400 mbar (for example for a paper tape with a weight of 115 g it is advantageous to use a depression of 200 mbar).

The surface of the belts 55 designed to be placed in contact with the paper tape 12 can be made of, or more preferably, covered with, Teflon (i.e., polytetrafluoroethylene - PTFE) or other material with low static and optionally dynamic friction coefficient (such as, preferably, antifriction materials, such as, for example, a nylon - polyamide based material- or a polyimide based material or yet others known to those skilled in the art).

Operation of the conveyor 10 of the present invention takes place as follows.

The paper tape 12 exiting the plotter 110 is guided by the roller 60 on the flatbed 40, said flatbed 40 housing the plurality of belts 55, provided with holes 57, 57’, which are placed in movement in the same direction of the movement of the paper tape 12 with a speed that is adjusted to the feed speed of the plotter 110.

The feed speed of the belts 55 is slightly higher than the feed speed of the plotter 110, according to a K factor for example equal to 1.05 of the feed speed of the paper tape 12 exiting the plotter 110.

It must be borne in mind that to allow this fundamental feature of the present invention, the paper tape 12 is driven by the belts 55, but can have a limited movement with respect thereto.

In this way, the paper tape 12 is always in tension. Again during operation of the conveyor 10, the pumps 20,30 are operated so as to create a depression of the chambers 45 inside the flatbed 40.

Thanks to the presence of the longitudinal through slots 142, which place the chambers 45 of the flatbed 40 and the perforated belts 55 above in fluidic contact, and of the holes 57, 57’ of the belts 55, contact is maintained between the paper tape 12 and said belts 55 during operation of the conveyor 10.

The limited depression generated in the chambers 45 of the flatbed 40 and the absence of means to make the paper tape 12 move integral with the belts 55, preferably combined with the fact that the surface of the belts 55 placed in contact with the paper tape 12 is covered with a low friction coefficient material with respect to the paper (such as Teflon), allows a limited relative movement of the paper tape 12 with respect to the belts 55, so as to prevent undue lacerations of the paper and allow safe movement of the paper tape 12 by the conveyor 10 toward the subsequent processing stations of the paper tape 12, placed downstream of the conveyor 10. Therefore, if the plant in which the conveyor 10 is arranged is provided with a printer or a plotter immediately upstream of said conveyor 10 and, for example, a paper cutting machine 130 arranged downstream of said conveyor 10, the fact that the speed of the belts 55 is slightly higher by a K factor (e.g. 1.05) than that of the paper tape 12, given by the printer or plotter placed upstream, and that this difference in speed is possible thanks to the fact that a limited relative movement of the paper tape 12 is possible with respect to the surface of said belts 55, does not create undue tensile forces on the drive mechanisms of the paper tape 12 of the printer or plotter placed upstream and allows the paper tape 12 to be supplied to the subsequent processing station, for example a paper cutting machine, at a steady rate and without any lacerations of the paper tape 12.

Naturally, modifications or improvements dictated by contingent or particular reasons, can be made to the invention thus described, without thereby departing from the scope of the invention.