EP4501826A1

EP4501826A1 - Suction table for conveying substrates

Info

Publication number: EP4501826A1
Application number: EP23382806.0A
Authority: EP
Inventors: Jesús Francisco Barberan Latorre
Original assignee: Individual
Current assignee: Individual
Priority date: 2023-08-02
Filing date: 2023-08-02
Publication date: 2025-02-05
Also published as: WO2025027216A1

Abstract

The present invention relates to a suction table (1) for conveying paper (2) for feeding to a processing machine, comprising a plurality of suction holes (3) through which wheels (4) protrude for conveying the paper (2) and through which suction is performed to provide traction to the paper (2) in its movement, wherein at least one of the plurality of suction holes (3) comprises an additional support surface (1.1) between the wheel (4) and the input end (3.2), and/or between the wheel (4) and the output end (3.1) of the suction hole (3), for supporting the laminar substrate having low rigidity (2) during its movement.

Description

Technical field

The present invention is related to machines for feeding laminar substrates to a processing machine, and more specifically with a suction feeding table used for conveying laminar substrates, preferably from a feeding machine to a substrate processing machine. In particular, referring to a suction table for conveying laminar substrates of the paper type.

State of the art

For the feeding of laminar substrates having low rigidity, suction cups for holding the substrate are conventionally used, or other machines that have suction straps/bands or clamps for pulling the substrates and move them to the corresponding processing machine or location.
Moreover, for laminar substrates with greater rigidity and weight such as cardboard, feeding machines are used that consist of supply and guide elements where a stack of laminar substrates is deposited for feeding thereof to a processing machine for said laminar substrates, which will subsequently carry out printing, folding, etc. tasks. In order to be able to feed the laminar substrates individually, said feeding machines comprise a feeding table, which comprises a plurality of wheels that move the laminar substrates. So that the traction is greater and there is no bad movement (for example, slippage between the wheels and the substrate) for the feeding of each substrate, said feeding tables have a suction that carries the laminar substrate against the tables, specifically against the wheels. Thus, the table has holes, rectangular in cross section, through which the wheels protrude, appearing slightly above the surface of said table, for contacting the laminar substrate and through which suction is produced.
As mentioned, this type of feeding machines are commonly used for cardboard sheets, however, as an alternative to the previously mentioned machines for conveying/feeding laminar substrates having low rigidity, in the present invention their use has been provided for paper sheets, or the like in terms of rigidity of the substrate, however, a number of problems arise.
The paper, being less rigid, hits against the final edge of the holes in the direction of movement due to the suction produced (being more easily sucked, on its external edges and corners, towards the inside of the holes due to its lower rigidity), this produces misalignments that result in poor feeding of the processing machines and consequently in stops that slow down the production process, and even tearing in the laminar substrates that invalidate them for subsequent use, etc.
Another problem is that the paper itself is inserted into the holes, causing blockages that force a stop and are sometimes difficult to correct without disassembling any of the parts of said suction feeding table.
In view of the currently existing solutions, an alternative solution is required that allows continuous feeding of paper sheets individually and continuously, avoiding blockages or defects derived from the suction of the feeding table, and can also be versatile for use with substrates of greater rigidity or allow the feeding machines of such substrates of greater rigidity to be adapted.

Object of the invention

In order to meet this objective and solve the technical problems discussed so far, in addition to providing additional advantages that can be derived later, the present invention provides a suction table for conveying a laminar substrate having low rigidity or low grammage, thickness, such as paper, plastic, wood (wood veneer) etc., being conveyed both individually and from a continuous substrate reel, for feeding to a processing machine, comprising a plurality of holes through which wheels protrude for conveying the laminar substrate having low rigidity, hereinafter referred to as substrate, and through which suction is performed to provide traction to the substrate in its movement, wherein at least one of the plurality of holes, and preferably all the holes comprise an additional support surface between the wheel and the input end, and/or between the wheel and the output end of the suction hole, for supporting the substrate during its longitudinal movement along the suction table.
The output end is understood to be the hole section from the middle portion of the longitudinal hole to the end of same in the direction of movement for moving the substrate towards the processing machine. The input end corresponds to the end of the suction hole opposite to the output end.
The space between the wheel and the ends of the suction hole is understood to be taken from the beginning of the suction hole to the closest meeting with the wheel according to the plane defined by the table.
Due to this configuration after the contact of the substrate with the wheel in the event that the additional surface is arranged between the wheel and the output end or prior to the contact of the substrate with the wheel in the event that the additional surface is arranged between the input end and wheel, the substrate is prevented from entering the hole, preventing blockages or poor substrate feeding. In this way it is possible to use the same suction table of rigid substrates such as cardboard, adapting it for use with substrates having low rigidity such as paper.
Regarding the advantages with respect to the feeding system of the state of the art by means of clamps, with the present invention a solution with greater mechanical simplicity is obtained. Clamp systems are normally associated with offset printing machines that require mechanical synchronism, on the contrary, in the present invention said one by one synchronisation of the substrates is not required, since all the substrates are detected and the printing is activated according to the readings of the control means when appropriate, i.e., there is an electronic synchronism.
Another advantage with respect to this type of clamp system is that the substrates do not suffer mechanical stress as the substrates are not stretched. This is very interesting when using an inkjet printer where, as there is no mechanical contact, dimensional stability must be ensured when printing. In offset systems, the dragged substrate makes contact with the printing rollers.
In general, the suction table object of the invention is a simpler constructive form and allows more options than traditional systems (belts or bands or clamps). As an example of this, this design allows metal wheels instead of rubber wheels to be placed under the heating area.
According to one option of the invention, the additional support surface defines a geometry of the output end and/or input end of the suction hole with a tapering width section, said tapering section being configured for guiding the substrate.
Guiding the substrate is understood as directing the substrate in the direction of movement and such that, in the event that it tends to enter the hole, said tapering section forces this portion of the substrate to be directed towards the outside, guiding it towards the outside as the only option in its movement in the direction of advance of the substrate.
For the interaction of the substrate with the input end of the suction hole, the guiding would be interpreted as the tendency of the substrate to advance without being inserted into the suction hole, since, during its advance, the substrate would meet the narrowest section of the hole, so that it will not be inserted and when it is close to the wheel it will rest on same, helping it to advance and move upwards as it progresses, preventing it from entering the hole.
Due to this configuration, a sufficient traction of the substrate is maintained with a respective suction, but due to the resulting tapering width section after the addition of the support surface, said substrate guiding action occurs which directs the substrate without being inserted in the suction holes.
Said support surface that defines the tapering section could be arranged on one or both sides of the suction hole, and with symmetrical or different sections on both sides, its geometry always being calculated in order to avoid collision or insertion of the corresponding substrate in the suction hole. In other words, depending on the features of the substrate to be conveyed, the tapering geometry will be defined in a greater or lesser degree of width reduction of the suction hole.
According to a feature of the invention, the additional support surface is also arranged at the input end of the suction hole also defining a tapering width geometry, in this case increasing in width in the direction of the feed. This configuration prevents the substrate from jumping when colliding against the input edge of the suction hole, the substrate has more contact surface than the corresponding state of the art and in this way the front ends of the substrate are less likely to be sucked into the holes before the substrate rests on the wheels in its forward movement, so that continuous feeding occurs at high speeds and without problems caused by the interaction between the substrate and the suction hole.
According to another feature of the invention, the additional support surface defines a geometry of the output end and/or the input end that is angled, i.e., with straight inclined edges, and preferably symmetrical with respect to the longitudinal axis of symmetry of the hole. In this way, the guidance of the substrate is improved and favours continuous feeding without stops.
According to another configuration, the output end and/or the input end is defined with an arcuate geometry. In this case, the edges are smoothed, improving guidance and maintaining a greater suction area.
Preferably the additional support surface defines the output end and/or the input end with a pointed finish, so that the straight protruding edge of the suction hole that can cause problems in the movement of the substrate is completely removed.
Provision is preferably made for the support surface to comprise a chamfer on the edge of the hole at the output end and/or at the input end. Said chamfer contributes to direct the substrate to prevent it from hitting the edge, so that when it makes contact with the inclined surface of the chamfer, the substrate sheet is directed to the outside in the event that the suction takes it to the inside of the hole.
According to another aspect of the invention, the additional support surface comprises a pattern of through holes that allow the suction to pass. Due to this configuration, the substrate is allowed to be guided without excessively reducing the suction performance of the table, trying to compensate for the loss of suction due to the additional support surface.
According to a feature of the invention, the support surface can be permanently attached to or removed from the suction hole. It is also contemplated that the same suction table is directly manufactured with the mentioned support surface. With the additional support surface being removable, its use is possible when substrates having low rigidity are used, and it can be removed when more rigid substrates are used, providing greater versatility to the suction table. The fixing of the support surface could be achieved, for example, by means of a sheet metal with the same dimensions as those corresponding to the conventional suction table but which has a modified hole with an additional support surface, so that when fixing the sheet metal to the suction table the resulting hole is the modified hole with the configuration that prevents the substrate from blocking.
According to another alternative of the invention, the support surface is in the form of a mesh that can be attached to the suction hole. The mesh is fixed to the same hole, forming said additional support surface between the wheel and the ends and/or between the side of the wheel and the side of the suction hole.
According to another aspect of the invention, it is contemplated that the table comprises a pattern of through holes in the table surface around the suction hole. Suction is improved with this feature, assimilating same to that of a usual suction hole.
It is contemplated that the features presented above may be combinable according to different embodiments as long as they are compatible.
The previously mentioned features contribute to a better feeding of the laminar substrate having low rigidity, preventing blockages or misalignments that slow down production.

Description of the figures

Figure 1 shows a schematic perspective view of a detail of a state of the art suction feeding table, in which only one wheel is shown for greater clarity.
Figure 2 shows a perspective view of a detail of a suction feeding table object of the invention with the ends of the holes exhibiting an arcuate-shaped geometry.
Figure 3 is an upper view of a suction feeding table like that of Figure 2, showing a paper sheet.
Figure 4 is a perspective view of a detail of a suction feeding table with a chamfer on the edge of the supporting surface of the output end of the suction hole.
Figure 5 is a detailed upper view of a suction hole according to the invention, where the dimensions of a practical exemplary embodiment are arranged. Where the dashed line shows the geometry followed by a state of the art suction hole.
Figure 6 is a cross-sectional front view of the table through the median plane of a suction hole according to the embodiment of Figure 5.
Figure 7 is an upper view of an alternative exemplary embodiment of the invention, where the dashed line shows the geometry followed by a state of the art suction hole.
Figure 8 shows a perspective view of another exemplary embodiment in which the additional support surface and the distribution of holes in the table are combined.
Figure 9 is a detailed upper view of the embodiment of Figure 8.

Detailed description of the invention

As can be seen in Figure 1 corresponding to a suction feeding table of the state of the art, the suction holes (3) have a rectangular geometry and through which the movement wheel (4) emerges for feeding the laminar substrate sheet having low rigidity (2) hereinafter as a practical example, paper sheet (2), by rotating same in the suitable direction for the advance movement of the substrate. This type of suction hole (3) presents the problem that during the movement of paper sheets (2) it causes the blockage or misalignment of said paper (2) due to the action of suction and unlike other laminar substrates such as cardboard of greater rigidity, the paper (2) is inserted at the ends in the space between the wheel (4) and the straight end edge of the suction hole (3), i.e., by having a relatively large suction area the less rigid paper or substrate rests less on the table and is exposed to being sucked in and hits the edges when being sucked, etc.
To resolve these problems, the present invention contemplates a suction table with an additional support surface (1.1) that defines a geometry of the suction hole (3) with the output end (3.1) and/or the input end (3.2) with a tapering width geometry. As can be seen in Figure 2, said tapering geometry will preferably be arcuate-shaped and with a pointed finish, by way of an arrow, resulting in a modified hole (3').
This configuration favours the guidance and greater support, on the table (1), of the paper sheet (2) which, as can be seen in Figure 3, will move from the left towards a processing machine, or in its simple conveyance depending on requirements. Thus, the correct suction is maintained to maintain the traction of the paper (2) on the wheels (4) without problems of blockages, or movements of the paper (2) caused by the collision with the edges of the suction hole (3), since the modified hole (3') will have its ends (3.1', 3.2') configured for guiding the paper (2).
According to an alternative embodiment of the invention, as can be seen in Figure 4, so that the guiding is smoother and the paper (2) does not collide against the edges of the modified suction hole (3'), the edge of the support surface (1.1) comprises a chamfer (5) at the output end (3.1'), said chamfer (5) being also able to be provided at the input end (3.2') of the hole (3').
As a non-limiting practical exemplary embodiment of the invention, as can be seen in Figure 5, for a paper substrate (2) of the Kraft or coated paper type, of 170 g/m², and for a suction hole (3) that is 85 mm long, 35 mm wide and with a wheel (4) that is 110 mm in diameter; a section reduction has been considered that starts at level (A) of 23.1 mm, with a pointed finish and with an arcuate section that starts at level (8) of 11 mm and a radius (R) of 24 mm. The chamfer made further being 2 mm x 45°. These measurements will vary depending on the substrate (2), dimensions of the suction hole (3) and the suction force.
This same Figure 5 shows the manner in which the additional support surface (1.1) covers a portion of the suction hole (3) of the state of the art represented in dashed lines. Such that it is provided that the support surface (1.1) can be an insert, be manufactured in a sheet metal that can be attached to the table (1) with the configuration of the modified suction hole (3'), or be entirely manufactured on the surface of the suction table (1).
In Figure 6, you can see the space between the wheel and the end of the hole (3) where the substrate (2) is inserted, and which, due to the geometry of the support surface (1.1), will be guided to the outside. The chamfer (5) represented in the same figure contributes to this.
According to another embodiment, Figure 7 shows the manner in which the space between the wheel (4) and the end of the suction hole (3) has been covered, and between the sides of the wheel (4) and the side of the suction hole (3), leaving a modified suction hole (3') with a reduced suction surface. In addition, a distribution of through holes (1.2) has been provided, which allow the suction to pass, maintaining the traction between the paper (2) and the wheel (4). Said holes (1.2) may have different sizes and patterns depending on the requirements, and be arranged on the additional support surface (1.1) and/or around the suction hole (3).
Figures 8 and 9 show another alternative embodiment in which the hole pattern (1.2) is combined with the support surface (1.1) that defines the output end (3.1') angled and with a pointed finish. In addition, the configuration of the holes (1.2) in this case is in the form of slots, but it could also be of any shape depending on the requirements, always allowing the passage of suction and the support of the paper (2).

Claims

A suction table (1) for conveying a laminar substrate having low rigidity (2) for feeding to a processing machine, comprising a plurality of suction holes (3) through which wheels (4) protrude for conveying the laminar substrate having low rigidity (2) and through which suction is performed to provide traction to the laminar substrate having low rigidity (2) in its movement, wherein at least one of the plurality of suction holes (3) comprises an additional support surface (1.1) between the wheel (4) and the input end (3.2), and/or between the wheel (4) and the output end (3.1) of the suction hole (3), for supporting the laminar substrate having low rigidity (2) during its movement.
The suction table (1) according to the preceding claim, wherein the support surface (1.1) defines a geometry of the output end (3.1) and/or the input end (3.2) of the suction hole (3) with a tapering width section configured for guiding the laminar substrate (2) in its movement.
The suction table (1) according to the preceding claim, wherein the support surface (1.1) defines an angled geometry of the output end (3.1) and/or the input end (3.2).
The suction table (1) according to claim 2, wherein the support surface (1.1) defines an arcuate geometry of the output end (3.1) and/or the input end (3.2).
The suction table (1) according to any one of the preceding claims, wherein the support surface (1.1) defines a geometry of the output end (3.1) and/or the input end (3.2) with a pointed finish.
The suction table (1) according to any one of the preceding claims, wherein the support surface (1.1) comprises a chamfer (5) along the edge that defines the hole (3) at the output end (3.1) and/or the input end (3.2).
The suction table (1) according to any one of the preceding claims, wherein the support surface (1.1) comprises a pattern of through holes (1.2) that allow suction to pass.
The suction table (1) according to any one of the preceding claims, wherein the support surface (1.1) can be permanently attached to or removed from the suction hole (3).
The suction table (1) according to claim 1, wherein the support surface (1.1) is a mesh that can be attached to the suction hole (3).
The suction table (1) according to any one of the preceding claims, comprising a pattern of through holes (1.2) in the table surface (1) around the suction hole (3).