Multi-row coaxial melt-blown type plant

Abstract

A multi-row coaxial melt-blown type plant (1) is provided, defining a dispensing direction (1c) along which a polymeric fluid is dispensed to form polymeric filaments and comprising a box (2) including one or more first ducts (20) configured to convey the polymeric fluid parallel to the dispensing direction (1c) and at least one second duct (21) configured to convey air or gas; a spinneret (3) integral to the box (2) and including a plurality of acceleration ducts (30) extending parallel to the dispensing direction (1c) comprising tubes (10) in fluid passage connection with the one or more first ducts (20) and configured to distribute the polymeric fluid, first holes (31) extending parallel to the dispensing direction (2a), centred and spaced with respect to the acceleration ducts (30) along the dispensing direction (1c) and configured to accommodate each part of a respective tube (10), second holes (32) extending parallel to the dispensing direction (1c) and adapted to allow the passage of air or gas, and a slit (33) extending transversely to the dispensing direction (1c) between the acceleration ducts (30) and the first holes (31) in fluid passage connection with the second holes (32), wherein at least part of the support (2) is in one piece with the spinneret (3) such that the slit (33) is in fluid passage connection with the second duct (21) and configured to convey the air or gas from the second duct (21) to at least the second holes (32).

Description

[0001] DESCRIPTION

[0002] MULTI-ROW COAXIAL MELT-BLOWN TYPE PLANT

[0003] The present invention relates to a multi-row coaxial melt-blown type plant of the type specified in the preamble of the first claim.

[0004] In other words, the present invention relates to a plant adapted to allow the making of extruded polymer filaments intended to make, either directly or indirectly, fabric of the non-woven type, also known as NWF.

[0005] As is known, non-woven fabric, or NWF, is an industrial product similar to a fabric but obtained by processes other than weaving and knitting. Therefore, within a non-woven fabric, the fibres are arranged randomly, without any ordered structure being defined, whereas in a fabric the fibres are arranged in two predominant and mutually orthogonal directions, usually referred to as weft and warp.

[0006] Currently, a plurality of products containing NWF are manufactured depending on the manufacturing technique used, mainly related to the use for which the product is intended.

[0007] In particular, high-quality NWFs for hygienic-sanitary type products are distinguished from low-quality NWFs mainly used for geotextiles.

[0008] From a technical point of view, non-woven fabrics, also known by the English term nonwoven fabric, can essentially be divided into spunlace, spunbond, and melt-blown.

[0009] In the field of melt-blown technology, multi-row coaxial melt-blown type plants, or multirow coaxial melt-blown, are particularly known. An example of such plants is shown in Figs. 7-9.

[0010] In general, such plants provide for the stretching of the polymer exiting from small tubes, arranged in rows, through air which, coaxially, passes from the outside of the tube and pushes the fibre downwards.

[0011] In particular, multi-row coaxial melt-blown type plants comprise components defining coaxial holes, arranged in rows and adapted to house at least part of the aforementioned tubes transiting coaxially inside the holes in such a way as to allow the diffusion of polymeric fluid and, at the same time, to allow the diffusion of air or gas from at least part of the holes.

[0012] Usually, such plants include apparatuses, called spin packs, including a plurality of different components adapted to interact with one another. Usually, a spin pack consists of a spinneret and a diffusion device including one or more components called air plate.

[0013] Moreover, the spinneret can in turn be connected to a taper and / or to a breakerplate.

[0014] If present, the breaker-plate is, in turn, connected to an extrusion head adapted to convey at least polymeric fluid and optionally also air or pressurised gas to the spin pack. The breaker-plate and the taper fundamentally have the same characteristics as the breaker-plate and taper used in spunbond and melt-blown technologies.

[0015] Multi-row coaxial melt-blown plants including spin packs, however, do not comprise a diffusion device including a support adapted to support an air blade, do not include a cusp, or do not have a simple spinneret adapted to allow only the exit of polymer.

[0016] In multi-row coaxial melt-blown plants, the spinneret is substantially a support that allows the holding of tubes adapted to eject polymer filaments. The diffusion device is, therefore, attached to the spinneret and comprises a plate, or intermediate air plate, adapted to allow the passage of said tubes and also the exit of air or other pressurised gas, and an external jig, or external air plate, usually of divergent shape, from which the polymer filament exits, pushed downwards by the air, before reaching the conveyor belts present in any plant for the making of non-woven fabric.

[0017] Multi-row coaxial melt-blown devices comprise some important drawbacks.

[0018] In particular, in order to make a melt-blown non-woven fabric, it is necessary that the tubes pass through the support, the plate, and the external jig without losing coaxiality with respect to the holes made, in particular, on the plate and the jig in order to ensure correct operation of the plant. In fact, it is possible for the ends of the tubes exiting from the external jig through the holes, configured with a diameter greater than the tubes so as to also allow the flow of air or gas, to undergo deformations. This possibility is especially due to the need to maintain at least one slit between the plate and the external jig for the distribution of gas or air.

[0019] Moreover, the plants as just described have a plurality of overlapping plates and are not very compact and are difficult to disassemble.

[0020] The use of many plates, during the installation step, also causes considerable problems once the plants have undergone a plurality of processing operations. In fact, it is necessary for the plates and the jigs to perfectly fit all the tubes and it is also necessary for the plate and the external jig to be perfectly aligned with each other so as to avoid undesired misalignments that could lead to tube breakage or the impossibility of mounting the intermediate and external air plates onto the internal air plate.

[0021] These problems are extremely amplified by the high processing temperatures and the expansions that may occur in the various components of the multi-row coaxial melt-blown plants.

[0022] Moreover, all the aforementioned problems are greatly amplified when the spin pack is particularly extended, since assembling or disassembling the air plate from the tubes may require the force, necessary to overcome the mutual friction between the air plate and the tubes, to be greatly increased.

[0023] In an attempt to overcome the aforementioned drawbacks, the applicant has devised a multi-row coaxial melt-blown type plant, described in particular in patent application EP-A-4108815, shown in Figs. 5-6.

[0024] The plant essentially comprises a support provided with a housing inside which a removable box is positioned, including a first plate in which acceleration ducts are obtained, into which the tubes for conveying the polymeric fluid are inserted, and a second plate, integral with the first plate, which substantially acts as an internal air plate and is spaced apart from the first plate by a slit through which air can pass.

[0025] Thanks to the combination, in one piece, of the plates of the box, the plant described in EP-A-4108815 makes it possible to avoid losses of axiality between the tubes and the holes made in the components of the plant, since the cleaning of the box can be carried out from the sides, through the slit, without the need to remove the tubes from the housing holes as, instead, happens in the plants of the known art.

[0026] However, even the just described plant includes some important components.

[0027] In detail, the characteristic dimensions of the support make it possible to make housings and therefore boxs of elongated shape and reduced width. This entails considerable problems if the plant is very long, since the box may undergo undesired bending that may even result in the impossibility of subsequent use when the plant is disassembled for cleaning.

[0028] In this situation, the technical object underlying the present invention is to devise a multi-row coaxial melt-blown type plant capable of substantially overcoming at least part of the aforementioned drawbacks.

[0029] Within the scope of said technical object, an important aim of the invention is to achieve a multi-row coaxial melt-blown type plant that allows to facilitate the assembly and disassembly of one or more components of the plant while always ensuring the integrity of the components that compose it and allowing the performance of multiple maintenance cycles.

[0030] Another important aim of the invention is therefore to provide a plant whose maintenance is simple, fast, effective, and economical.

[0031] In conclusion, a further object of the invention is to provide a plant that is extremely versatile and that allows to easily modify the configuration, intended for example as the density or number, of the small tubes from which the polymeric filaments exit.

[0032] The technical object and the specified aims are achieved by a multi-row coaxial melt-blown type plant as claimed in the attached claim 1 .

[0033] Preferred embodiment are highlighted in the dependent claims.

[0034] The features and advantages of the invention are clarified below by the detailed description of preferred embodiments of the invention, with reference to the attached drawings, in which:

[0035] Fig. 1 shows a view in cross-section along the main plane of a multi-row coaxial melt-blown type plant according to the invention in which the plant is assembled;

[0036] Fig. 2 illustrates a perspective view with cross-section along the main plane of box and dispenser of a multi-row coaxial melt-blown type plant according to the invention;

[0037] Fig. 3 is an exploded view of the plant of Fig. 1 ;

[0038] Fig. 4 represents a top view of box and dispenser of Fig. 2;

[0039] Fig. 5 shows an exploded view of a multi-row coaxial melt-blown type plant of the known art, in particular as described in patent application EP-A-4108815;

[0040] Fig. 6 shows an exploded and perspective view of the plant of the known art of Fig. 5;

[0041] Fig. 7 illustrates a cross-sectional view of a multi-row coaxial melt-blown type plant of the known art in which the holes of the intermediate air plate through which air flows are highlighted;

[0042] Fig. 8 is a further cross-sectional view of a multi-row coaxial melt-blown type plant of the known art in which the housing holes of the small tubes that distribute polymeric fluid are highlighted; and

[0043] Fig. 9 represents an exploded and perspective view of a multi-row coaxial melt-blown type plant of the known art in which are shown, from bottom to top, an external air plate, an intermediate air plate, an internal air plate, a taper, a breakerplate and a second taper intended to be constrained in contact with an extrusion head.

[0044] In this document, when measurements, values, shapes, and geometric references (such as perpendicularity and parallelism) are associated with words like "approximately" or other similar terms, such as "almost" or "substantially", they are to be understood as excluding measurement errors or inaccuracies due to production and / or manufacturing errors and, above all, as having less than a slight deviation from the associated value, measurement, shape, or geometric reference. For example, if associated with a value, such terms preferably indicate a deviation by no more than 10% of the value itself.

[0045] Moreover, when used, terms such as "first", "second", "upper", "lower", "main" and "secondary" do not necessarily identify an order, a priority of relationship or a relative position, but can simply be used to clearly distinguish between their different components.

[0046] Unless otherwise specified, as reflected in the following discussions, terms such as "processing", "computing", "determination", "computing", or the like are considered to refer to the action and / or processes of a computer or similar electronic computing device that manipulates and / or transforms data represented as physical, such as electronic quantities of records of a computer system and / or memories, in other data similarly represented as physical quantities within computer systems, records, or other information storage, transmission, or display devices.

[0047] Unless otherwise stated, the measurements and data reported in this text shall be considered as provided in International Standard Atmosphere ICAO (ISO 2533:1975).

[0048] With reference to the figures, the multi-row coaxial melt-blown type plant according to the invention is globally denoted by the number 1 .

[0049] The plant 1 , as per the title, includes some features of common melt-blown plants and other specific arrangements.

[0050] The device 1 is configured to be used within a multi-row coaxial melt-blown plant.

[0051] The plant, as per the title, includes some features of common melt-blown plants and other specific arrangements.

[0052] In particular, the plant 1 preferably comprises at least one box 2 and a spinneret 3. The following description of all the components that may be present in a plant 1 is made by considering them along a cross-section of the plant in a main plane 1a as illustrated, for example, in Figs. 1-4. Naturally, such a plant 1 and the components that comprise it also extend along a longitudinal direction 1b perpendicular to the main plane 1 a and secondary plane 1a’, that is, to the aforementioned crosssections.

[0053] Furthermore, the plant 1 preferably defines a dispensing direction 1c. The dispensing direction 1 c is the direction along which the polymeric fluid is preferably dispensed to form the polymeric filaments. The dispensing direction 1 c is preferably perpendicular to the longitudinal direction 1 b. Furthermore, the dispensing direction 1 c preferably lies on the main plane 1 a or is parallel thereto.

[0054] The box 2 substantially performs the same functions as a common breaker-plate. Thus, the box 2 is essentially a coupling device on which the other components of the plant 1 are laid.

[0055] Substantially, the box 2 is the main connecting element between the components of the plant and the external apparatuses adapted to supply the plant itself with substances used in the normal operation of the plant 1 .

[0056] For example, among the various apparatuses external to the plant 1 , there may be an apparatus adapted to supply the plant with pressurised polymeric fluid, or a pneumatic apparatus adapted to supply the plant with air or pressurised gas or other elements.

[0057] Among the external apparatuses, in particular, there may be an extrusion head. The extrusion head, as is known, usually includes at least one main channel.

[0058] The main channel is preferably adapted to allow the passage of a first polymeric fluid through the extrusion head. Such fluid can be introduced into the box 2 from an apparatus external to the plant. Preferably, as occurs in common melt-blown plants, the main channel is adapted to allow the passage of hot polymeric fluid, having temperatures approximately around 180°. In fact, for example, the polymeric fluid may consist of polypropylene, polyester, nylon, cellulose, viscose or other fluids suitable for the making of nonwoven fabric, or NWF, with the multi-row coaxial melt-blown plant.

[0059] Furthermore, the extrusion head may also comprise a secondary channel.

[0060] The secondary channel is preferably adapted to allow the passage of gas through the extrusion head. Again, the gas may flow into the plant from apparatuses external to the plant.

[0061] The box 2 therefore comprises one or more first ducts 20. Preferably, the box 2 comprises a plurality of first ducts 20. The first ducts 20 are substantially configured to convey polymeric fluid. Therefore, the first ducts 20 are adapted to allow the passage of a first polymeric fluid through the box 2. Such fluid may be introduced into the box 2 from an apparatus external to the plant.

[0062] The first ducts 20 are preferably adapted to be arranged in fluid passage connection, for example, with the main channel of the extrusion head so as to receive polymeric fluid from it.

[0063] The one or more first ducts 20, in even more detail, are preferably configured to convey the polymeric fluid along or parallel to the dispensing direction 1 c.

[0064] The dispensing direction 1 c is, when the plant 1 is in use, substantially a vertical direction, preferably perpendicular to the ground or to a roller on which the polymeric filaments that make up the non-woven fabric may be deposited.

[0065] Moreover, the box 2 may also comprise at least one second duct 21.

[0066] The second duct 21 is preferably configured to convey air or gas and is therefore adapted to allow the passage of gas through the support 2. Again, the gas may flow into the plant 1 from apparatuses external to the plant.

[0067] For example, the second duct 21 may be in fluid passage connection with the secondary channel of the extrusion head.

[0068] The support 2 may include additional elements.

[0069] For example, the support 2 may include filtering means 22.

[0070] The filtering means 22, if present, are preferably arranged upstream of the first ducts 20 in such a way as to filter the polymeric fluid.

[0071] The filtering means 22, in particular, may include a common flat filter, substantially a mesh adapted to filter the first polymeric fluid, or they may include a porous element.

[0072] In addition, the box 2 could comprise further details.

[0073] The box 2 could be in one piece. Or, the box 2 could comprise a support 2a and a dispenser 2b mutually distinct.

[0074] If present, the support 2a is the portion of box 2 that comprises one or more second ducts 21 , while the dispenser 2b is the portion of box 2 that comprises the one or more first ducts 20.

[0075] Therefore, in turn, the support 2a may comprise a housing 23.

[0076] If present, the housing 23 is substantially a groove made in the support 2a extending along the longitudinal direction 1 b. Moreover, the housing 23 is adapted to house the dispenser 2b in such a way that the latter can be removably constrained to the support 2a.

[0077] Therefore, when the box 2 is in use, support 2a and dispenser 2b are mutually integral. Moreover, the dispenser 2b is, in general, removably constrained to the support 2a.

[0078] If filtering means 22 are present, furthermore, the dispenser 2b comprises the filtering means 22. In particular, the filtering means 22 are placed upstream of the one or more first ducts 20.

[0079] The plant 1 may also comprise a taper. The taper, if present, is releasably constrained to the box 2.

[0080] In particular, the taper is substantially a connecting element between box 2 and any apparatuses external to the plant 1 . The taper may therefore be positioned between box 2 and the extrusion head.

[0081] In any case, the box may include first fastening means.

[0082] The first fastening means are preferably configured to allow the fastening of the box 2 to an external apparatus, for example the extrusion head. Alternatively, the first fastening means may allow the fastening of the support 2 to a taper.

[0083] The first fastening means may be made with conventional couplings such as, for example, screws and bolts or other releasable joints, or also magnetic connectors, provided that they are adapted to allow stable fastening between external apparatuses, such as the extrusion head or taper, and the box 2.

[0084] Moreover, the box 2 preferably also comprises second fastening means.

[0085] The second fastening means are configured to allow the fastening of the support 2 with another component of the plant 1 , as better specified hereinafter.

[0086] The second fastening means may be conventional and may be substantially of the same type as the first fastening means.

[0087] Furthermore, advantageously, the second fastening means are preferably accessible at a side of the box 2 opposite with respect to said first fastening means. This feature implies that the box 2 may advantageously be coupled to components on both sides at different times without the use of the first fastening means obstructing, for example, the use of the second fastening means and vice versa. The spinneret 3 is preferably integral to the box 2.

[0088] The spinneret 3 is substantially a beam-like element extending predominantly along or parallel to the longitudinal direction 1 b, that is, a direction transverse to the dispensing direction 1 c and preferably perpendicular to the plane 1 a.

[0089] The spinneret 3, in even greater detail, is substantially the set of a first portion 3a similar to a conventional internal distribution plate or spinneret and a second portion 3b similar to a conventional internal or intermediate air plate. In other words, the box 3 is, as a whole, a portion of a spin pack in which the external air plate is not present. Thus, the first portion 3a and the second portion 3b are integral, and even more in detail, mutually constrained. They may, for this purpose, be made in one piece or welded together.

[0090] The spinneret 3 preferably includes a plurality of acceleration ducts 30. The acceleration ducts 30 are preferably arranged in the first portion 3a.

[0091] The acceleration ducts 30 are substantially configured to receive the first polymeric fluid from the first ducts 20. Therefore, preferably, the acceleration ducts are arranged in fluid passage connection with the first ducts 20.

[0092] The acceleration ducts 30 extend parallel to the dispensing direction 1 c.

[0093] Moreover, the acceleration ducts 30 are preferably configured to accelerate the first polymeric fluid.

[0094] To this end, in multi-row coaxial melt-blown plants, the acceleration ducts 30 include, or may consist of, tubes 10. These tubes 10 may therefore be releasably constrained to the spinneret 3. In particular, preferably, the acceleration ducts 30 are placed in the first portion 3a in such a way that the tubes 10 are constrained thereto.

[0095] The tubes 10 are widely known in the current state of the art and are substantially ducts including at least one internal converging section adapted to allow the acceleration of the first polymeric fluid flowing inside them.

[0096] Moreover, the tubes 10 have a substantially cylindrical tubular shape and define diameters usually between 0.6 and 1 mm.

[0097] The tubes 10 are also intended to extend through the spinneret 3, as shown in Figs. 1 and 3.

[0098] If the tubes 10 are not in one piece with the spinneret 3, usually, the first portion includes housings.

[0099] The housings may be substantially cavities, including at least one shoulder or step, within which at least part of the tube 10 may be housed.

[0100] The tube 10, in turn, preferably includes a base and a stem.

[0101] The base is preferably configured to be inserted into one of the housings.

[0102] The stem preferably extends along the dispensing direction 1 c, that is, in vertical direction along the cross-section. Therefore, the first polymeric fluid coming from the first ducts 20 substantially enters the base of the tubes 10 and is accelerated along the stems.

[0103] Thus, the tubes 10 are substantially in fluid passage connection with the one or more first ducts 20 and are configured to distribute said polymeric fluid.

[0104] The acceleration ducts 30 may therefore be distributed along one or more rows extending parallel to the longitudinal direction. In particular, they are usually distributed in a regular manner so as to form ordered rows both along the longitudinal direction and along each cross-section of the plant 1 .

[0105] Sometimes, the acceleration ducts 30 of adjacent rows are mutually staggered along the longitudinal direction in such a way as to form a substantially checkerboard configuration. The spinneret 3 also includes first holes 31 and second holes 32. The latter are preferably arranged in the second portion 3b.

[0106] The first holes 31 preferably extend along or parallel to the dispensing direction 1 c. Moreover, they are preferably centred and spaced with respect to the acceleration ducts 30 along the dispensing axis 2a. Thus, the first holes 31 are preferably configured to house each part of a respective tube 10. The tubes 10, as already mentioned, are in turn configured to distribute polymeric fluid.

[0107] Therefore, the first holes 31 are adapted to allow the passage of polymeric fluid through the tubes 10.

[0108] The second holes 32, instead, are preferably separate with respect to the first holes 30. They are, in particular, adapted to allow the passage of air or gas. Alternatively, the second holes 32 may coincide with the first holes 31 and house the tubes 10 while maintaining a gap externally thereto to allow the passage of air or gas. In other words, the first holes 31 could be part of the second holes 32, that is, define an inner region of the second holes 32 adapted to be occupied by the acceleration ducts 30, that is, by the tubes 10, so that the air or gas may exit from the second holes 32 around the tubes 10 and, therefore, around the polymeric filament conveyed by the tubes 10.

[0109] In general, therefore, the second holes 32 also extend parallel to the dispensing direction 1 c.

[0110] Substantially, the first holes 31 are adapted to house part of the stem of the tubes 10. The latter, in the preferred embodiment, are constrained to the spinneret 3 in the first portion 3a, through the acceleration ducts 30, and pass through the holes 31 , 32 in the second portion 3b. The second holes 32, at the same time, are adapted to allow the passage of air or gas. The box 3 also comprises a slit 33.

[0111] The slit 33 extends transversely to the dispensing direction 1 c between the acceleration ducts 30 and the first holes 31. In other words, the acceleration ducts 30 and the first holes 31 are connected by the tubes 10 and separated by the slit 33 which is transverse to the same tubes 10. Thus, the slit 33 spaces and separates the first portion 3a and the second portion 3b.

[0112] Moreover, the slit 33 is appropriately in fluid passage connection with the second holes 32.

[0113] Preferably, but not necessarily, the slit 33 extends through the spinneret 3 from side to side. This means that the slit 33 extends, in a transverse plane of the spinneret 3 extending perpendicularly to the dispensing direction 1 c and parallel to the longitudinal direction 1 b, from an opening on one side of the spinneret 3 to an opening on the opposite side of the spinneret 3.

[0114] Therefore, if the box 2 comprises two second ducts 21 placed at opposite sides of the box 2, the slit 33 is in fluid passage connection with both ducts, connecting them. Advantageously, the spinneret 3 and the box 2 are not only integral, but at least part of the box 2 is in one piece with the spinneret 3.

[0115] In particular, preferably, the first portion 3a of the spinneret 3 is in one piece with the support 2a or, more precisely, the support 2a comprises the first portion 3a which defines a part thereof.

[0116] In even greater detail, preferably, the first portion 3a is configured in such a way that the acceleration ducts 30 are in fluid passage connection with the housing 23.

[0117] Moreover, preferably, the support 2a is configured in such a way that the first portion 3a, in particular the acceleration ducts 30, and the dispenser 2b are separated by a separation space 24. The latter corresponds to a space region comprised, precisely, between the dispenser 2b and the first portion 3a, adapted to allow the filling of the polymeric fluid arriving from the one or more first ducts 20 upstream of the acceleration ducts 30.

[0118] The separation space 24 may be ensured by providing shoulders that allow the dispenser 2b to rest on the support 2a spaced from the first portion 3a.

[0119] Moreover, advantageously, the slit 33 is in fluid passage connection with the second duct 21 and is also configured to convey air or gas from the second duct 21 to the second holes 32.

[0120] The plant 1 , in addition to what has been described, could further include a jig 4. The jig 4 is mostly similar to a common external air plate with some differences.

[0121] The jig 4 is preferably removably constrained to one or more of the box 2 and the spinneret 3. Preferably, the jig 4 is removably constrained to the box 2, in particular preferably to the support 2a, for example through the second fastening means. Thus, the jig 4 acts as a cap that closes the dispenser 3 between itself and the box 2.

[0122] Preferably, the jig 4 preferably includes a plurality of third holes.

[0123] The third holes are preferably centred with respect to the first holes 31 . Moreover, they are adapted to house part of the tubes 10 coming from the first holes 31 of the box 3 and are in communication with the second holes 42. Therefore, the third holes 40 house part of the tubes 10 and, at the same time, allow the passage of air or gas around the tubes 10. In other words, the third holes 40 are also in fluid passage connection with the second holes 32. To achieve this feature, it is sufficient for the third holes 40 to be oversized with respect to the tubes 10 so as to create a gap around the tubes 10 for the passage of air. The jig 4 further also comprises a seat 41.

[0124] The seat 41 is advantageously configured to accommodate at least part of the spinneret 3. In particular, preferably, the seat 41 houses at least the second portion 3b of the spinneret 3. In this way, the jig 4 may be anchored to the box 2 by enclosing the spinneret 3, in particular the second portion 3b, between the support 2a and the jig 4.

[0125] Similarly to the housing 23, the seat 41 also extends globally parallel to the longitudinal direction 1 b. Thus, in the preferred embodiment, on one side the dispenser 2b behaves as an insert or cartridge with respect to the box 2 in which it is housed by means of the housing 23, and on the other side the support 2b and spinneret 3, which are in one piece, behave as an insert or cartridge.

[0126] The invention allows the making of an innovative method for assembling the plant 1 comprising at least a first insertion step and a second insertion step.

[0127] In the first insertion step, preferably, the dispenser 2b is inserted inside the housing 23. Then, in the second insertion step, preferably, the second portion 3b is inserted into the seat 41 . In particular, advantageously, the insertion of the second portion 3b into the seat 41 allows to arrange the slit 33 in fluid passage connection with at least one second duct 21 and the tubes 10 in fluid passage connection with one or more first ducts 20. The jig 4 may also, furthermore, be configured to form, when constrained to the box 2, at least part of one or more second ducts 21 .

[0128] Naturally, the method may also comprise a fastening step in which the jig 4 is constrained to the box 2, in particular to the support 2a, by means of the second fastening means. At the same time, the box 2 may also be fastened to a taper or an extrusion head by means of the first fastening means.

[0129] The invention also allows the making of a new method for cleaning the plant 1 . The cleaning method thus comprises at least one step of removing the jig 4 from the second portion 3b.

[0130] Then, the cleaning method comprises a step of blowing the slit 33 with pressurised air. In this way, by blowing the slit 33 with pressurised air, dust deposited within the slit 33 is also removed.

[0131] The plant 1 according to the invention achieves important advantages.

[0132] In fact, the plant 1 allows to avoid losses of axiality between the tubes partially housed in the diffusion device and the holes made in the components of the plant, since the cleaning of the box 3 can be carried out from the sides, via the slit 33, without the need to remove the tubes 10 from the first holes 31 as occurs in the plants of the known art.

[0133] This advantage is maintained despite high mechanical strength, since, being part of the box 2 and the spinneret 3 in one piece, the spinneret 3 is not a distinct object with reduced width and low bending resistance, but can be maintained easily while preserving its alignment with the longitudinal direction 1 b of extension and, therefore, without warping.

[0134] Moreover, the device 1 allows to maintain high processing efficiency while at the same time reducing the complexity of installation and maintenance of the plant 1 .

[0135] The assembly of the plant 1 is extremely simple and facilitated, and the number of components is furthermore reduced to a minimum.

[0136] The invention can be modified to create different versions falling within the scope of the inventive concept defined by the claims.

[0137] In this context, all the details can be replaced by equivalent elements and any materials, shapes and dimensions can be used.

Claims

CLAI MS1. Plant (1 ) of the coaxial multi-row melt-blown type defining a dispensing direction (1 c) along which a polymeric fluid is dispensed to form polymeric filaments and comprising:- a box (2) including one or more first ducts (20) configured to convey said polymeric fluid parallel to said dispensing direction (1 c) and at least one second duct (21 ) configured to convey air or gas;- a spinneret (3) integral to said box (2) and including:- a plurality of acceleration ducts (30) extending parallel to said dispensing direction (1 c) comprising tubes (10) in fluid passage connection with said one or more first ducts (20) and configured to distribute said polymeric fluid, - first holes (31 ) extending parallel to said dispensing direction (2a), centered and spaced with respect to said acceleration ducts (30) along said dispensing direction (1 c) and configured to accommodate each part of a respective said tube (10),- second holes (32) extending parallel to said dispensing direction (1 c) and suitable for allowing the passage of air or gas, and- a slit (33) extending transversely to said dispensing direction (1 c) between said acceleration ducts (30) and said first holes (31 ) in fluid passage connection with said second holes (32); and characterised in that- at least part of said support (2) is in one piece with said spinneret (3) such that said slit (33) is in fluid passage connection with said second duct (21 ) and configured to convey said air or gas from said second duct (21 ) to at least said second holes (32).

2. Plant (1 ) according to claim 1 , wherein said box (2) comprises a support (2a) and a dispenser (2b) detachably constrained to said support (2a), said one or more first ducts (20) are included in said dispenser (2b), said second duct (21 ) is included in said support (2a), and said spinneret (3) is in one piece with said support (2a).

3. Plant (1 ) according to any preceding claim, wherein said spinneret (3) comprises a first portion (3a) and a second portion (3b) mutually constrained and spaced apart from said slit (33), said acceleration ducts (30) are included in said first portion (3a) such that said tubes (10) are constrained to said first portion (3a), said holes (31 , 32) are included in said second portion (3b), and said support (2a) includes said first portion 3a such that said first portion 3a defines a part of said support (2a).

4. Plant (1 ) according to any of claims 2-3, wherein support (2a) comprises a housing (23) adapted to house said dispenser (2b) and is likewise configured such that said first portion (3a) and said dispenser (2b) are separated by a separation space (24).

5. Plant (1 ) according to any of the preceding claims, wherein said box (2) includes at least two of said second ducts (21 ) placed at opposite sides of said box (2) and said slit (33) extends from side to side of said spinneret (3) so as to be in fluid passage connection with both of said second ducts (21 ) connecting said second ducts (21 ).

6. Plant (1 ) according to any preceding claim, further comprising a jig (4) detachably constrained to one or more of said box (2) and said spinneret (3) and including a plurality of third holes (40) centered with respect to said first holes (31 ), communicating with said second holes (32) and configured to accommodate part ofsaid tubes (10) and to allow, at the same time, passage of said air or gas around said tubes (10).

7. Plant (1 ) according to the preceding claim, wherein said jig (4) includes a seat (41 ) configured to accommodate of said spinneret (3).

8. Plant (1 ) according to at least claims 3 and 7, wherein said seat (41 ) accommodates at least said second portion (3b) such that said jig (4) is anchored to said box (2) by enclosing said second portion (3b) between said support (2a) and said jig (4).

9. Method for assembling a multi-row coaxial melt-blown type plant (1 ) according to at least claims 3, 4 and 8, characterised in that it comprises at least:- inserting said dispenser (2b) inside said housing (23), and- inserting said second portion (3b) into the seat (41 ) by arranging said slit (33) in fluid passage connection with at least one said second duct (21 ) and said tubes (10) in fluid passage connection with said one or more first ducts (20).

10. Method for cleaning a multi-row coaxial melt-blown type plant (1 ) according to at least claim 8, characterised in that it comprises at least:- sliding said jig (4) off said second portion (3b)- blowing said slit (33) with pressurized air to remove dust deposited within said slit (33).

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