EP4695068A1

EP4695068A1 - Device for stabilising extruded products

Info

Publication number: EP4695068A1
Application number: EP23730955.4A
Authority: EP
Inventors: Fabio Cazzani; Davide PAGANI
Original assignee: Omipa SpA
Current assignee: Omipa SpA
Priority date: 2023-04-14
Filing date: 2023-04-14
Publication date: 2026-02-18
Also published as: WO2024214124A1; CN120916882A

Abstract

A device for stabilising extruded products (P) comprises a pair of conveyor belts (2, 3), pneumatic means (4) and a pair of perforated calibrating plates (5, 6). Each conveyor belt (2, 3) comprises a respective perforated belt contributing to defining the upper and lower walls of a feed path. The pneumatic suction means (4) are coupled to the conveyor belts (2, 3) and configured to generate a pneumatic vacuum condition in the feed path. The perforated plates (5, 6) are placed between the pneumatic suction means (4) and the belts, in thermal contact with them in their respective forward sections.

Description

DESCRIPTION

DEVICE FOR STABILISING EXTRUDED PRODUCTS

Technical Field

The present invention relates to the technical field of manufacturing processes by means of extrusion.

In particular, the present invention relates to a device for stabilising extruded products, which ca be used in particular for the calibration, transport and cooling of extruded sheet-shaped products, such as alveolar sheets.

State of the art

The manufacturing processes by extrusion of materials, particularly plastics, are attracting a great deal of interest at the industrial level as they make it possible to manufacture, in a particularly efficient and versatile way, a huge variety of products.

In this field, the prior art involves using an extrusion head within which plastic materials are heated to bring them to a fluid configuration which can then be properly shaped to produce the product of interest.

As long as the material remains hot, it may be deformed and easily shaped by simply applying different extrusion geometries.

It is however clear that cooling the product, once it has been given the desired shape, is an extremely important and delicate process in order to ensure that this shape is maintained and thus that the final product is solid and stable.

In fact, an incorrect execution of such a process may lead to manufacture defective products that have not maintained the originally given shape.

Referring in particular to the context of producing sheet-shaped products, it is known producing machines which comprise extrusion heads followed by a stabilising device configured to cool the freshly extruded sheet, promoting its solidification into the desired shape. In particular, the action of the stabilisation device prevents the sheets from collapsing by appropriately cooling the material.

Such stabilisation devices usually comprise devices configured to generate air jets that can be directed onto the sheets and cooling plates facing each other and between which the sheets are slid.

In greater detail, the cooling plates have holes that can be connected with pneumatic sources so as to create a pneumatic vacuum condition between them that sucks in the opposite surfaces of the newly extruded sheets, holding them against the cooling plates and thus preventing their structure from collapsing before it has been properly solidified.

Downstream of the cooling plate system, pairs of pulling rollers, usually covered with rubber, are present, which pull the sheet-shaped product while exiting the plates and which is solid by now so that it does not accumulate in the section where it is still softened.

Operatively, the sheet-shaped product slithers between the two surfaces of the cooling plates; the material releases heat to the latter and it hardens until it has taken the final shape which is dragged out of the stabilising device.

The main drawback of the prior art is the friction between the moving material and the surface of the cooling plates.

Such slithering is unavoidable as it is required to maintain a close contact between the sheet and the plates both to properly transfer heat between the two and to be able to ensure that the correct shape/structure of the sheet is maintained.

The resulting friction between the sheet and the plates generates a resisting force which may be overcome by applying a considerable traction downstream of the stabilising device, but the latter traction cannot obviously exceed a certain limit, otherwise an excessive deformation will occur by elongating the product, which may even tear.

This problem severely limits the maximum speed of the entire production process and also involves problems in terms of the overall quality of the products that may be manufactured, which are in any case inevitably affected, from a structural point of view, by the effect of the traction force applied to them.

In addition, the cooling plates tend to accumulate extruded plastic residues in the grooves and holes made to exert pneumatic vacuum on the upper and lower surfaces of the sheet, which progressively occlude them, significantly affecting their operation.

In fact, these accumulations tend to clog the passages and can lower the quality of the product surface finish.

In order to clean the calibrating plates, it is required to stop the entire production process each time, move the plates away and act manually with suitable tools.

Object of the invention

In this context, the technical task underlying the present invention is to propose a device for stabilising extruded products which overcomes at least some of the drawbacks of the prior art mentioned above.

In particular, it is the object of the present invention to make available a device for stabilising extruded products that can ensure at the same time high throughput and high quality of the products produced.

The defined technical task and the specified objects are substantially achieved by a device for stabilising extruded products, comprising the technical characteristics set forth in one or more of the appended claims.

According to the present invention, a device for stabilising extruded products is shown.

In particular, the device is configured for stabilising extruded sheet-shaped products.

The device essentially comprises a pair of conveyor belts, pneumatic means and a pair of perforated calibrating plates.

In particular, the pair of conveyor belts comprises a first conveyor belt and a second conveyor belt. The first conveyor belt comprises a first belt having a plurality of through- holes.

The first belt extends along an initial forward section defining a lower wall of a product feed path.

The second conveyor belt comprises a second belt having a plurality of through-holes.

The second belt extends along a second forward section defining an upper wall of the feed path;

The pneumatic suction means are at the first and second conveyor belts.

In addition, the pneumatic means are configured to generate, through the through-holes, a pneumatic vacuum condition in the feed path so as to hold the product, in use, against the first and second belts.

The perforated calibrating plates are placed between the pneumatic suction means and the first and second belts, respectively.

Each perforated calibrating plate is in thermal contact with either the first or the second belt in respective forward sections.

Advantageously, the device herein described makes it possible to accompany the product without having to drag it, thus avoiding the undesired accumulation of material on the plates (which are not in direct contact with the product).

It is thereby possible to speed up the production process while ensuring high quality results.

The dependent claims herein incorporated for reference, correspond to different embodiments of the invention.

Brief description of the drawings

Further characteristics and advantages of the present invention will become more apparent from the approximate and thus non-limiting description of a preferred, though not exclusive, embodiment of a device for stabilising extruded products, as shown in the accompanying drawings, wherein: - Figures 1 to 3 show respective possible embodiments of the device according to the present invention;

- Figure 4 shows an exploded view of some components of the device.

Detailed description of preferred embodiments of the invention

In the enclosed figures, reference number 1 globally indicates a device for stabilising extruded products P, which will be referred to, in the hereinafter description, simply as device 1 .

Such a device 1 is specifically a device configured to stabilise an extruded sheet-shaped product P (such as an alveolar sheet) so as to stabilise the structure thereof.

The term stabilisation is intended to denote a process performed by cooling an extruded product P and by which its shape/structure is stabilised by bringing the constituent material from a softened condition to a completely solid condition or at least sufficiently solid to maintain its structural configuration/design with no need for external aids.

From a structural perspective, the device 1 essentially comprises a pair of conveyor belts 2, 3, pneumatic suction means 4 and a pair of perforated calibrating plates 5, 6.

In greater detail, the pair of conveyor belts 2, 3 comprises a first conveyor belt 2 and a second conveyor belt 3.

The first conveyor belt 2 comprises a belt having a plurality of through- holes and extending along a path that comprises a first forward section and a first return section.

The first forward section operatively defines (or otherwise contributes to defining) a lower wall of a feed path for a product P.

Similarly and correspondingly, the second conveyor belt 3 comprises a belt which also has a plurality of through-holes and which extends along a path that comprises a second forward section and a second return section. By contrast, the second forward section defines (or otherwise contributes to defining) an upper wall of a feed path for a product P. Preferably, both the first and second belts are made using metallic materials, or in general materials having high thermal conductivity values.

It should be noted that in general the terms “first” and “second” are used in this description merely to identify a relevance of the different components and features specifically to one or the other of the conveyor belts 2, 3 that contribute to making up the device 1 , without thereby implying any specific sequencing or numerousness of the elements identified with these terms.

As it can be seen in the attached figures, the first and second conveyor belts 2, 3 are arranged in an overlapping configuration, with the first belt having its first forward section directly facing the second forward section of the second belt.

In other words, the feed path is a path defined and enclosed at the bottom by the first belt and at the top by the second belt.

Advantageously, the device 1 can further comprise walls configured to laterally delimit the feed path thereby defining a closed path having only an inlet opening (which, as will be discussed in more detail hereinafter, will be facing an extrusion head) into which the product P which needs to be cooled will enter and an outlet opening from which the stabilised product P will exit.

In addition, the first and second conveyor belts 2, 3 each comprise a fixed return pulley 2a, 3a and a motorized pulley 2b, 3b, respectively, which is instead movable parallel to the feed path to vary a tension of the respective belt.

These pulleys 2, 2b, 3a, 3b operatively define the ends of the forward and return paths of the respective belts.

Preferably, the first and second conveyor belts 2, 3 are supported by suitable frames.

In particular, the device 1 may comprise a first frame configured to support the first conveyor belt 2 and a second frame configured to support the second conveyor belt 3.

Therefore, the first frame stably constrains and supports the return pulley 2a of the first conveyor belt 2 and is coupled to its motorized pulley 2b in such a way that it can be moved parallel to the feed path.

Correspondingly, the second frame stably constrains and supports the return pulley 3a of the second conveyor belt 3 and is coupled to its motorized pulley 3b in such a way that it can also be moved parallel to the feed path.

Alternatively, the device 1 may comprise a single frame having a first portion supporting the first conveyor belt 2 and a second portion supporting the second conveyor belt 3 instead.

Advantageously, the first and second frames are also configured to make it possible for the conveyor belts 2, 3 to move closer to or away from each other.

In particular, the device 1 comprises handling means configured to move the conveyor belts 2, 3 closer to or away from each other, making thereby possible to vary a height of the feed path.

By way of example and not limitation, the handling means may comprise a plurality of hydraulic cylinders active on the second conveyor belt 3 to raise or lower it along suitable guides included in the frame supporting it.

Advantageously, in addition to allowing the height of the feed path to be varied, the possibility of moving the two conveyor belts 2, 3 away from each other makes it particularly easy to perform any maintenance and repair operation as the area surrounding and defining the feed path becomes easily accessible.

In order to ensure proper operation of the device at all times and to prevent undesired accumulation of material on the surface of the belts, the device 1 can further comprise cleaning elements.

In particular, the device 1 comprises a first cleaning element associated with the first belt and a second cleaning element associated with the second belt (both downstream of the respective forward sections and thus preferably along the return sections).

Such cleaning elements can be made by means of suitable pneumatic sources configured to deliver respective jets of compressed air onto the surface of the belts.

The action of the jets of compressed air makes it possible to remove any material residues accidentally stuck on the belts.

In addition, the device 1 can further comprise one or more suction elements configured to suck any material residues separated from the belts by moving them away from the working area.

Such material residues may in fact accumulate on the belts when the product P passes through the feed path, since along that path, adhesion to the belts is necessary to ensure proper maintenance of the product P structure.

This requirement is met through the action of pneumatic means 4, which are coupled to the first and second belts 2, 3 and are configured to generate, through their through-holes, a pneumatic vacuum condition within the processing path.

Such a pneumatic vacuum sucks in the product P (specifically its upper and lower surfaces) causing it to adhere and hold against the belts as it transits along the feed path.

Cooling and holding the proper shape of product P are further promoted by the action of the perforated calibrating plates 5, 6, which are placed between the pneumatic suction means 4 and the first and second belts, respectively.

Specifically, the device 1 comprises a first perforated calibrating plate 5 positioned at the bottom of the first belt and placed between the latter and the pneumatic means 4.

Similarly, the device 1 also comprises a second perforated calibrating plate 6 which is instead positioned above the second belt and is placed between the latter and the pneumatic means 4.

In greater detail, each perforated calibrating plate 5, 6 is placed in thermal contact with the forward section of the respective belt.

Thereby, the product P sliding along the feed path can release the heat to the belts and, in cascade, to the perforated calibrating plates 5, 6.

In addition, the calibrating plates 5, 6 are perforated transversely to their own lying plane, so as to connect the pneumatic means with their respective perforated belts.

In other words, the section of the feed path enclosed between the two belts is placed in fluid communication with the pneumatic means 4 through the holes present on the belts themselves and on the calibrating plates 5, 6.

Thus, in use, the freshly extruded product P (thus still not fully stabilised) enters the feed path by engaging the first and second belts and being held against them by the action of the pneumatic vacuum generated by the pneumatic means 4.

The product P is then conveyed along the feed path under the action of the conveyor belts 2, 3 and, as it is fed, progressively releases heat to the belts themselves and then to the perforated calibrating plates 5, 6, cooling and stabilising in the desired design.

Advantageously, the device 1 of the present invention makes it possible to move the product P with no need to drag it, as the presence of the conveyor belts 2, 3 makes it possible to progressively accompany the product P being moved along the feed path.

In addition, the peculiar structure herein described avoids the problem of the product P slithering on the plates, as they do not directly contact the product P, but on the contrary such a contact is mediated by the belts sliding on the perforated calibrating plates 5, 6 accompanying the handling of product P.

According to an aspect of the present invention, and as it can be seen in Figure 4, in order to ease the clearing of the heat transferred from the product P, each perforated calibrating plate 5, 6 has respective conduits (preferably conduits longitudinal to the lying plane of the plates 5, 6) adapted to define a flow circuit S for a cooling fluid.

Such a cooling fluid may be an appropriate heat transfer fluid that accumulates heat within the conduits and can subsequently release it once it has left the respective flow circuit.

In this context, the device 1 may comprise a tank to contain the cooling fluid and a pumping device configured to convey the cooling fluid along the flow circuit S.

The tank is then connected to the conduits of the two perforated calibrating plates 5, 6 (preferably in such a way as to define two separate flow circuits S placed in parallel) and may further comprise or be connected with a heat exchanger by which the heat accumulated by the fluid within the flow circuit S is dissipated.

Advantageously, as shown in Figures 2 and 3, the device 1 may comprise additional calibrating plates positioned upstream and/or downstream of the conveyor belts 2, 3 aimed at performing a preliminary reduction of the initial temperature of the product P or a final finishing of its surface, respectively.

In particular, as shown in Figure 2, the device 1 may comprise a pair of inlet calibrating plates 8 positioned upstream of the first and second conveyor belts 2, 3 along the feed path.

In particular, the inlet calibrating plates 8 face each other so that they enclose, at the top and at the bottom, an initial section of the feed path.

Preferably, the inlet calibrating plates 8 have a shorter length along the feed path than a corresponding length of the perforated calibrating plates 5, 6.

In fact, the purpose of the inlet calibrating plates 8 is not specifically to completely stabilise the product P, but mainly to carry out a preliminary reduction of the temperature that allows to provide the conveyor belts 2, 3 with a product P that is not completely malleable and already having a certain initial stiffness which facilitates entering into the feed path.

In this context, the implementation of shorter inlet calibrating plates 8 allows to reduce the overall footprint of the device 1 and minimizes the risk of undesired material residues forming on them. Similarly, as shown in Figure 3, the device 1 may comprise a pair of outlet calibrating plates 9 positioned downstream of the first and second conveyor belts 2, 3 along the feed path.

Specifically, the output calibrating plates 9 are facing each other so as to enclose at the top and bottom, an end section of the feed path.

Preferably, the outlet calibrating plates 9 have a shorter length along the feed path than a corresponding length of the perforated calibrating plates 5, 6.

In fact, the purpose of the outlet calibrating plates 9 is not specifically to complete the stabilisation of product P, but mainly to carry out a final surface finish as it exits the feed path.

In this context, the implementation of shorter outlet calibrating plates 9 makes it possible to reduce the overall footprint of the device 1 and minimizes the risk of undesired material residues forming on them and friction hindering the handling of the product P.

In general, the inlet 8 and outlet 9 calibrating plates can also have the same structure, components and connections as the perforated calibrating plates 5, 6.

For example, the inlet 8 and outlet 9 calibrating plates may also comprise respective conduits defining circuits for the flow of a cooling fluid and thus be connected to the aforementioned tank (or to additional respective and independent dedicated tanks).

Similarly, the inlet 8 and outlet 9 calibrating plates can also be drilled and connected with pneumatic means 4 (or with additional respective and independent dedicated pneumatic means 4) so as to make it possible, in use, to create, in the space delimited by them, a pneumatic vacuum condition adapted to make the product P adhere against their surface, facilitating and promoting the retention of a proper structural design.

In addition, the inlet 8 and outlet 9 calibrating plates can also be movable as they move closer to/away from the feed path, so that their distance can be adjusted to a corresponding distance between the belts ( such that the height of the passages passed through by the product P is kept constant along the entire feed path).

Advantageously, the device may further comprise a pair of mutually facing pneumatic cooling sources 10 positioned upstream of the first and second conveyor belts 2, 3 along the feed path.

Such pneumatic cooling sources 10 are specifically configured to emit, in use, an air knife on one lower face and one upper face of the product P, respectively.

Such air knives abruptly cool the sheet to solidify the outer surface of the still softened material before it enters the feed path.

Advantageously, the present invention achieves the proposed objects by overcoming the drawbacks complained of in the prior art by making available to the user a device 1 for stabilising extruded products P, which can operate particularly efficiently and rapidly while achieving high levels of quality in the stabilised product P.

A machine for making extruded sheet-shaped products P is also a subject of the present invention.

In particular, such a machine comprises an extrusion head 7 configured for manufacturing sheet-shaped extruded products P.

Preferably such products P comprise alveolar sheets.

The machine also comprises a device 1 for stabilising extruded products P having the characteristics described above.

Operatively, such a device 1 is configured to receive the product P from the extrusion head 7 and to move it by conveying it along the feed path. While it travels through the feed path, which as mentioned is mediated by the action of the conveyor belts 2, 3, the product P releases heat at least to the perforated calibrating plates 5, 6 cooling and stabilising in the desired shape whose conformity is ensured by the adhesion of the product P to the conveyor belts obtained thanks to the vacuum condition generated by the pneumatic means 4.

Claims

1. Device for stabilising extruded products (P) comprising:

- a first conveyor belt (2) comprising a first belt having a plurality of through-holes and extending along a first forward section defining a lower wall of a feed path for a product (P);

- a second conveyor belt (3) comprising a second belt having a plurality of through-holes and extending along a second forward section defining an upper wall of the feed path;

- pneumatic suction means (4) coupled to the first and second conveyor belts (2, 3) and configured to generate through said through-holes a pneumatic vacuum condition adapted to hold the product (P) against the first and second belts in the feed path;

- a pair of perforated calibrating plates (5, 6) placed between the pneumatic suction means (4) and the first and second belts, respectively, said pair of perforated calibrating plates (5, 6) being in thermal contact with the first and second belts, respectively, in the respective forward sections.

2. Device according to claim 1 , comprising handling means configured to move the first and second conveyor belts (2, 3) closer to or away from each other to vary a height of the feed path.

3. Device according to claim 1 or 2, wherein the first and second belts are made of a metal material.

4. Device according to any one of the preceding claims, wherein the first and second conveyor belts (2, 3) each comprise a fixed return pulley (2a, 3a) and a motorized pulley (2b, 3b) movable parallel to the feed path to vary a tension of the respective belt.

5. Device according to any one of the preceding claims, comprising a pair of pneumatic cooling sources (10) that are mutually facing and positioned upstream of the first and second conveyor belts (2, 3) along the feed path, said pneumatic cooling sources (10) being configured to emit, in use, an air knife on a lower face and an upper face of the product (P), respectively.

6. Device according to any one of the preceding claims, comprising a pair of inlet calibrating plates (8) positioned upstream of the first and second conveyor belts (2, 3) along the feed path, said inlet calibrating plates (8) being faced so as to enclose at the top and bottom an initial section of the feed path.

7. Device according to any one of the preceding claims, comprising a pair of outlet calibrating plates (9) positioned downstream of the first and second conveyor belts (2, 3) along the feed path, said outlet calibrating plates (9) being faced so as to enclose at the top and bottom an end section of the feed path.

8. Device according to any one of the preceding claims, wherein each calibrating plate (5, 6, 8, 9) has respective conduits adapted to define flow circuits (S) for a cooling fluid.

9. Device according to claim 8, comprising a tank to contain a cooling fluid connected with the conduits of each calibrating plate (5, 6, 8, 9) and a pumping device configured to convey the cooling fluid along the respective flow circuits (S).

10. Device according to any one of the preceding claims, comprising:

- a first cleaning element coupled to a return section of the first belt and configured to remove residues of product (P) in a return section of the first belt; - a second cleaning element coupled to a return section of the second belt and configured to remove residues of product (P) in a return section of the second belt; preferably said cleaning elements comprising one or more pneumatic sources configured to emit an air knife on the respective belt.

11. Device according to claim 10, comprising one or more suction elements configured to suck the residues of product (P) removed from the first and second belts.

12. Machine for making extruded products (P) comprising:

- an extrusion head (7) configured to produce extruded products (P), preferably said extruded products (P) comprising alveolar sheets;

- a stabilising device (1) according to any one of the preceding claims;

- said device (1) being configured to receive the product (P) from the extrusion head (7) and to move it by conveying said product (P) along the feed path.