Extrusion head for continuously extruding at least one medical multi-lumen tube

Abstract

The extrusion head (1) according to the present invention is used for continuously extruding at least one medical multi-lumen tube. Such a head comprises a sleeve (2) in which a mandrel (3) is arranged, which is a single body provided, at a rear mandrel portion (32), with a common air inlet chamber (35). Advantageously, the mandrel (3) is provided, at the front mandrel portion (31), with a plurality of rods (33) made in one piece therewith, each provided with an inner air duct (34) in communication with the common air inlet chamber (35). An extrusion head thus obtained is capable of ensuring high dimensional standards since the mandrel has no inner elements (intended to form lumens) that require to be positioned and mechanically attached to the mandrel itself, with the risk of errors that would be reflected in the formation of the lumens.

Description

"EXTRUSION HEAD FOR CONTINUOUSLY EXTRUDING AT LEAST ONEMEDICAL MULTI -LUMEN TUBE" DESCRIPTION

[0001] The present invention relates to an extrusion head for continuously extruding a medical multi-lumen tube , in addition to a method for producing such a medical multilumen tube , along with the medical multi-lumen tube produced with this method .

[0002] In the field of medical products , some of the essential features that a medical multi-lumen tube must possess are chemical and biological non-reactivity, sterility, and reliability . Furthermore , it is necessary to consider the functionality of the product depending on the speci fic application . In fact , in the medical field, an increasing need is felt to obtain multi-lumen tubes with a high number of lumens and with particular distributions of said lumens in the tube itsel f .

[0003] Medical multi-lumen tubes are obtained by extrusion forming molten polymer material , by means of extrusion heads that allow the continuous extrusion of hollow and solid shapes . In a typical extrusion system of the prior art , solid pellets of thermoplastic material are supplied into a progressive screw extruder in which the pellets are liquefied and then inj ected at another pressure into an extrusion head . A particularly challenging extrusionshape is that of tubes having a central passage and one or more smaller passages , referred to as lumens , formed in the wall of the tube . The formation of such tubes provided with lumens in the wall requires a high level of precision in the extrusion dies and in the positioning of the die elements to form the lumens . An extrusion head with transverse inj ection according to the prior art consists of a male inserted into a die . In such an extrusion head, in order to form tubes having lumens , the molten polymer is inj ected into the head and is shaped into an annular flow around the cylindrical male . The flow is then pushed along a tapered conical section of the male and then along another cylindrical section of smaller diameter . An axial channel extends through the male to form the main axial passage in the extruded tube . In the extrusion step, an air flow is inj ected through such an axial channel to keep the polymer material in the form of an adequately inflated tube while it is extruded . A linear mandrel of smaller diameter is arranged in an of f-axis channel formed through the male , parallel to the axial channel , and extends up to the extrusion end of the die . During extrusion, an air flow is inj ected through the mandrel to form, in the wall of the tube , a further duct of smaller diameter ( lumen) than the central duct .An example of such a type of known extrusion head isdescribed in document EP4186679 . Such an extrusion head is used for continuously extruding a medical multi-lumen tube . The head comprises a monolithic sleeve , referred to as the die , and a mandrel , referred to as the male , arranged therein . The male comprises a portion with holes arranged circumferentially into which the mandrels , also referred to as needles , are attached for air intake .

[0004] Some signi ficant problems are known in the methodology of lumen formation according to the prior art . Firstly, since the mandrels are arranged in holes made in the male , any errors in the position of the mandrels lead to errors in the formation of the lumens . Furthermore , both the mandrel and the die must be changed to switch to an extrusion of a di f ferent diameter . Secondly, since the mandrels for the lumens extend into the male , they must necessarily intersect the conical portion thereof for the inj ection of molten polymer material , with the risk of generating disturbances in the polymer material flow, which disturbances can give rise to undesired alterations both aesthetically and functionally . A need is thus felt to minimi ze or prevent the intersection between the air inj ection channels and the molten polymer material flow channels .

[0005] As mentioned above , moreover, an increasing need is felt in the medical field to obtain multi-lumen tubeswith a high number of lumens having a particular distribution . For example , a need is felt to provide multiple circumferential rows of lumens arranged concentrically to one another .

[0006] It is the obj ect of the present invention to manufacture an extrusion head which solves the problems of the prior art , taking into account the needs of the industry .

[0007] Such an obj ect is achieved by an extrusion head according to claim 1 . The dependent claims describe preferred embodiments of the invention .

[0008] The features and advantages of an extrusion head, an extrusion method, and a medical multi-lumen tube according to the present invention will become apparent from the following description, given by way of nonlimiting example , according to the accompanying figures , in which :- Figures 1 to 5 show an extrusion head according to the present invention in an embodiment ; in particular :Figure 1 shows a partially sectioned, axonometric view;-- Figure 2 shows a side section view along plane L-L in Figure 5 ;-- Figure 3 shows a side section view along plane M-M inFigure 5 ;-- Figure 4 shows an axonometric view of a component of the extrusion head, and in particular of the mandrel ;-- Figure 5 shows a front view;- Figures 6 to 9 show an extrusion head according to the present invention, in a further embodiment ; in particular :Figure 6 shows a partially sectioned, axonometric view;-- Figure 7 shows a partially sectioned, axonometric view of a component of the extrusion head, and in particular of the sleeve ;Figure 8 shows an axonometric view in which, for clarity reasons , a component of the extrusion head has been omitted, and in particular the s leeve ;-- Figure 9 shows a side section view along plane N-N in Figure 6 ;- Figures 10 to 14b show an extrusion head according to the present invention, in yet a further embodiment ; in particular :-- Figure 10 shows an axonometric side view;Figure 11 shows a section view along plane P-P in Figure 10 ;Figure 12 shows a partially sectioned, axonometric view;Figure 13 shows the same view as Figure 12 in which,for clarity reasons , a component of the extrusion head, and in particular a front portion of the sleeve , has been omitted;-- Figure 14a shows a section view along plane Q-Q in Figure 12 ;-- Figure 14b shows a section view along plane R-R in Figure 10 ;- Figures 15 to 19b show an extrusion head according to the present invention, in yet another embodiment ; in particular :-- Figure 15 shows an axonometric side view;-- Figure 16 shows a front view;Figure 17 shows a section view along plane A-A in Figure 16 ;-- Figure 18a shows a section view along plane E-E in Figure 17 ;-- Figure 18b shows a section view along plane F-F in Figure 17 ;-- Figure 19a shows a section view along plane C-C inFigure 17 ;-- Figure 19b shows a section view along plane B-B inFigure 17 ;- Figures 20 to 22b show an extrusion head according to the present invention, in a yet another embodiment ; in particular :Figure 20 shows an axonometric side view;Figure 21 shows a section view along plane S-S in Figure 22A;-- Figure 22a shows a section view along plane T-T in Figure 21;-- Figure 22b shows a section view along plane V-V in Figure 21.

[0009] With reference to the accompanying Figures, an extrusion head according to the present invention is indicated by reference numeral 1, which is capable of obtaining multi-lumen tubes (example in Figures 1 to 14b) or a plurality of tubes by means of a single extrusion (Figures 15 to 22b) .

[0010] The extrusion head 1 according to the present invention is obtained by the technology of Selective Laser Melting (SLM) of metals, or Laser Powder Bed Fusion (LPBF) , or Direct Metal Laser Sintering (DMLS) . This is a 3-D Printing technology used to make metal parts from a bed of metal powders melted by means of a high-power laser (from 100 to 1,500 W) and with a concentrated beam (about 100 pm diameter) .

[0011] As seen, for example, in Figures 1, 6, 12, 15, and 20, the extrusion head 1 comprises a sleeve 2, which represents the female element, and a mandrel 3, which represents the male element, arranged internally withrespect to the sleeve 2 .

[0012] The sleeve 2 comprises two portions , referred to as the front sleeve portion 21 ( from which the polymer material exits in the form of a tube ) and the rear sleeve portion 22 ( through which the molten polymer material enters ) .

[0013] In an embodiment , such two front and rear portions are distinct portions mechanically j oined together to form the sleeve 2 , as in the constructional variant in Figures 1 and 12 in which attachment means 9 , for example screws , can be seen, arranged in appropriate attachment seats 91 extending into both the front sleeve portion and the rear portion of the sleeve 2 . Preferably, as can be seen in Figure 13 , the coupling between the front and rear portions of the sleeve 2 can also be improved through additional coupling means , such as pins 92 protruding from the rear portion that fit into appropriate seats made in the front portion, for example .

[0014] In a further embodiment , such two front and rear portions are made in one piece , as shown in Figures 6 , 15 and 20 .

[0015] The mandrel 3 comprises two portions , defined as front mandrel portion 31 and rear mandrel portion 32 . Such two front and rear portions are made in one piece .

[0016] In the constructional variants in Figures 1 and 6 ,the sleeve 2 and the mandrel 3 are distinct elements mechanically j oined together to form the extrus ion head .

[0017] In the constructional variants in Figures 12 and 15 , the mandrel 3 is made in one piece with the sleeve 2 or with a portion of the sleeve 2 . In the example in Figure 12 , the rear mandrel portion 32 is made in one piece with the rear sleeve portion 22 . In the example in Figures 15 and 20 , the rear mandrel portion 32 is made in one piece with the rear sleeve portion 22 , and the front mandrel portion 31 is made in one piece with the front sleeve portion 21 .

[0018] In brief , in the example in Figure 1 , the extrusion head 1 is formed by 3 distinct elements : mandrel 3 , front sleeve portion 21 , and rear sleeve portion 22 . In the example in Figure 6 , the extrusion head 1 is formed by 2 distinct elements : mandrel 3 and sleeve 2 . In the example in Figure 12 , the extrusion head 1 is formed by 2 distinct elements : front sleeve portion 21 and mandrel 3 in one piece with the rear sleeve portion 22 ( Figure 13 ) . In the example in Figure 15 and Figure 20 , the extrusion head 1 is formed by a single element since the mandrel 3 and the sleeve 2 are made in one piece .

[0019] In the example in Figure 1 and Figure 12 , the front sleeve portion 21 can be made of a heat conductive material .

[0020] In the examples in Figure 6, Figure 15, and Figure 20, the sleeve 2 is provided with a plurality of diffusers 29 made of a heat conductive material to better distribute the heat along the sleeve. The diffusers 29 are elongated elements, inserted or embedded into appropriate seats 291 made in the wall of the sleeve 2. Preferably, the diffusers 29 are homogeneously arranged circumferentially all around the mandrel 3.

[0021] In the example in Figure 6, the diffusers 29 made of a heat conductive material are embedded in the sleeve 2.

[0022] Advantageously, the diffusers 29 are curved and provided with an undercut 291 that makes them nonremovable from the sleeve. Advantageously, the diffusers 29 extend from a ring 292, also made of a heat conductive material, arranged in the rear sleeve portion 22, which allows for the acquisition of heat from the head of the sleeve 2.

[0023] As seen in Figure 7, the sleeve 2 is provided with a central channel 20 in which the mandrel 3 is inserted or arranged, as seen in Figure 4, for example. The molten polymer material is channeled between the inner surface of the central channel 20 of the sleeve 2 and the outer surface of the mandrel 3, in the front portions thereof, to form the outer wall of the medical multi-lumen tube.The mandrel 3 forms instead the lumens of the medicalmulti-lumen tube.

[0024] As can be seen in Figure 4, the mandrel 3 is provided, in the front mandrel portion 31, with a plurality of rods 33, integrated into the mandrel, i.e., made in one piece therewith, each provided with an inner air duct 34 in communication with a common air inlet chamber 35. Advantageously, therefore, as compared to the solutions of the prior art, the mandrel has no inner elements mounted in appropriate holes that require delicate positioning maneuvers and suffer from position errors that could compromise the correct formation of the lumens. In the solution of the present invention, since the mandrel 3 is obtained by the technology of Selective Laser Melting of metals, it has integrated rods 33, i.e., made in one piece, which are immovable and thus not subject to positioning errors.

[0025] In an embodiment, shown in Figures 1, 6, 12, the rods 33 have a polygonal section, e.g., trapezoidal, or square, or rectangular.

[0026] In an embodiment, shown in Figures 15 and 20, the rods 33 have a circular or elliptical section.

[0027] In an embodiment, shown in Figures 1, 6, 12, 15, the mandrel comprises a central rod 331, arranged along the longitudinal axis X of the mandrel 3. Such a solution allows obtaining a multi-lumen tube with a central lumen.

[0028] In an embodiment, shown in Figures 1, 6, 12, 15, the mandrel comprises at least a plurality of rods 33 homogeneously arranged about the longitudinal axis X of the mandrel 3 to form a crown of rods. Such a solution allows obtaining a multi-lumen tube with a plurality of lumens arranged in a ring.

[0029] In an embodiment, shown in Figures 1, 6, 12, the mandrel comprises multiple crowns of rods arranged concentrically about the longitudinal axis X of the mandrel 3. Such a solution allows obtaining a multi-lumen tube with a plurality of lumen arrays arranged in a ring.

[0030] In the examples in which the mandrel 3 is made in one piece with the sleeve 2, the union between said elements is made by means of tabs 4. In the example in Figures 10 and 15, in which the rear mandrel portion 32 is made in one piece with the rear sleeve portion 22, the mandrel 3 is connected to the sleeve 2 by means of tabs 4, which can be seen in Figures 11 and 18b, for example.

[0031] In the example in Figures 15 and 20, in which the front mandrel portion 31 is made in one piece with the front sleeve portion 21, the rods 33 are connected to the sleeve 2 by means of tabs 4, which can be seen in Figures 18a and 21, for example.

[0032] Preferably, the tabs 4 have a drop-shaped section (see Figures 19a and 22b) , with the tip facingdownstream, to improve the flow of molten material by minimi zing interferences in the material .

[0033] As mentioned above , each rod is provided with an inner air duct 34 in communication with the common air inlet chamber 35 . In the example in Figures 1 and 5 , the common air inlet chamber 35 is fed by an air inlet arranged in the rear mandrel portion 32 ; in the example in Figure 12 , the common air inlet chamber 35 is fed by an air inlet 36 arranged in the front sleeve portion 21 .

[0034] The inner air duct 34 comprises a rod segment 341 at the rod 33 and a connecting segment 342 towards the common air inlet chamber 35 .

[0035] Preferably, the connecting segment 342 of the inner air duct 34 comprises at least one curve , as can be seen in Figures 2 , 3 , 17 . Advantageously, therefore , as compared to the solutions of the prior art , the inner air duct 24 does not intersect the conical portion for the inj ection of the molten polymer material , reducing the risk of generating disturbances in the polymer material flow, which disturbances could lead to undesired alterations both aesthetically and functionally .

[0036] Preferably, the curve is shaped like an arc of a circle .

[0037] Preferably, at least a plurality of rods 33 comprises a connecting segment 342 with a curved portion,as can be seen in Figures 2 , 3 , 17 . As can be seen in Figure 3 , a radial arrangement of curved connecting segments 342 extends from the common air inlet chamber 35 , each of which defines the inner air duct of the related rod 33 .

[0038] As mentioned above , the molten polymer material flows between the inner surface of the central channel 20 of the sleeve 2 and the outer surface of the mandrel 3 throughout the rear portion ( of both) ; upon reaching the front portion ( of both) , part of the molten polymer material continues to flow between the inner surface of the central channel 20 of the sleeve 2 and the outer surface of the mandrel 3 , in the front portions thereof , to form the outer wall of the medical multi-lumen tube ; another part of the molten polymer material enters into the front portion of the mandrel 31 through collection basins 38 , which can be seen in Figure 4 , for example , to be conveyed to fill the spaces between the plurality of rods 33 and thus form the walls of the lumens of the multi-lumen tube .

[0039] The collection basins 38 are arranged between the front mandrel portion 31 and the rear mandrel portion 32 , at the outer surface of the mandrel 3 . Preferably, the collection basins 38 are uni formly distributed about the circumference .

[0040] Preferably, a collection basin 38 is arranged between two rods 33 , at the base thereof .

[0041] In the embodiments in Figures 1 , 6 , 12 , in which the mandrel comprises multiple crowns of rods 33 arranged concentrically about the longitudinal axis X, a plurality of collection basins 38 is present at the base of each crown of rods 33 , uni formly di stributed about the circumference of the respective crown and suitable for conveying part of the molten polymer material increasingly inwards toward the spaces between the rods 33 of the mandrel 3 . With reference , for example , to the mandrel in Figure 4 in which there are three concentric crowns of rods 33 and a central rod 331 : the first array of collection basins 38 (present at the base of the rods 33 of the first crown of rods ) conveys part of the molten polymer material towards the second crown of rods ; from there , the second array of collection basins 38 (present at the base of the rods 33 of the second crown of rods ) conveys part of the molten polymer material towards the third crown of rods ; from there , the third array of collection basins 38 (present at the base of the rods 33 of the third crown of rods ) conveys part of the molten polymer material towards the central rod 331 .

[0042] Preferably, in order to improve the thrust of the molten polymer material towards the interior of the frontmandrel portion 31 , the mandrel 3 comprises , downstream of the collection basins 38 , at least one raised part 37 that represents an impediment to the molten material flow . Preferably, the raised part 37 is an annular band that surrounds a crown of rods 33 , as shown in Figure 4 . Advantageously, the raised part 37 in the form of an annular band firmly holds the rods of the crown of rods 33 in place , avoiding even minimal deformations of the rods that would compromise the geometry of the lumens .

[0043] In the embodiments in Figures 1 , 6 , 12 , in which the mandrel comprises multiple crowns of rods 33 arranged concentrically about the longitudinal axis X, a raised part 37 is present on each crown of rods 33 , again downstream of the respective collection basins 38 , as can be seen in Figure 14a .

[0044] The embodiment in Figures 1 , 6 , 12 allows obtaining a multi-lumen tube with a central lumen, an inner circular crown of eight lumens , an intermediate circular crown of eight lumens , and an outer circular crown of sixteen lumens .

[0045] The embodiment in Figure 12 allows obtaining, with a single extrusion head 1 and in a single extrusion, nine distinct tubes intended to be compacted once out of the extruder to form a single splittable multi-lumen element .

[0046] The embodiment in Figure 20 allows obtaining, with asingle extrusion head 1 and in a single extrusion, two distinct tubes intended to be compacted once out of the extruder to form a single splittable multi-lumen element .

[0047] Innovatively, an extrusion head according to the present invention is obtained by the technology of Selective Laser Melting of metals ( 3D printing of metals ) , which allows obtaining multi- lumen tubes with particular geometries not obtainable with extrusion heads manufactured with conventional technologies .

[0048] Advantageously, an extrusion head according to the present invention is provided with a mandrel (male part ) which, having only rods ( intended to form lumens ) made in one piece therewith, is capable of ensuring high dimensional standards . Indeed, such a mandrel has no inner elements ( intended to form lumens ) that require to be positioned and mechanically attached to the mandrel itsel f , with the risk of errors that would be reflected in the formation of the lumens .

[0049] Advantageously, an extrusion head according to the present invention is provided with a mandrel (male part ) which, having rods ( intended to form lumens ) provided with curved air ducts ( for supplying air into the lumen during the forming step ) , is capable of ensuring high dimensional standards . In fact , such a mandrel , having air ducts that do not intersect the conical portion forthe inj ection of the molten polymer material , reduces the risk of generating disturbances in the polymer material flow, which disturbances could lead to undesirable alterations both aesthetically and functionally .

[0050] Advantageously, the extrusion head according to the present invention is provided with a mandrel (male ) with collection basins for better dissemination and distribution of the polymer material towards the inner zone of the mandrel .

[0051] Advantageously, in some embodiments , the extrusion head according to the present invention includes a mandrel (male ) made at least partially in one piece with the sleeve ( female ) ; such a solution does not require the step of mounting the mandrel in the s leeve .

[0052] Advantageously, in some embodiments , the extrusion head according to the present invention includes a sleeve ( female ) in which di f fusers made of a heat conductive material are embedded, which better distribute the heat throughout the sleeve .

[0053] It is apparent that those skilled in the art may make modi fications to the extrusion head described above , all contained within the scope of protection as defined by the following claims .

Claims

CLAIMS1) Extrusion head (1) for continuously extruding at least one medical tube, comprising a sleeve (2) having a central channel (20) in which a mandrel (3) is arranged; wherein the mandrel (3) is a single body formed by a front mandrel portion (31) and a rear mandrel portion(32) , said portions (31, 32) being made in one piece; wherein said mandrel (3) is provided, at the rear mandrel portion (32) , with a common air inlet chamber (35) ; characterized in that said mandrel (3) is provided, at the front mandrel portion (31) , with a plurality of rods(33) made in one piece therewith, each rod (33) being provided with an inner air duct (34) in communication with the common air inlet chamber (35) .2) Extrusion head (1) according to claim 1, being obtained by selective laser casting of metals.3) Extrusion head (1) according to any one of the preceding claims, wherein the inner air duct (34) of the rod (33) comprises a rod segment (341) and a connecting segment (342) for the connection with the common air inlet chamber (35) , and wherein said connecting segment (342) is curved.4) Extrusion head (1) according to any one of the preceding claims, wherein at least one collection basin (38) is present between the front mandrel portion (31)and the rear mandrel portion (32) .5) Extrusion head (1) according to claim 4, wherein the mandrel (3) comprises, downstream of a collection basin(38) , a raised part (37) in the form of an annular band surrounding at least one rod (33) .6) Extrusion head (1) according to any one of the preceding claims, wherein the sleeve (2) is formed by:- a front sleeve portion (21) and a rear sleeve portion(22) , said portions (21, 22) being distinct and mechanically joined together by attachment means (9) housed in attachment seats (91) extending into both the front sleeve portion (21) and the rear sleeve portion (22) ; or- a front sleeve portion (21) and a rear sleeve portion (22) , said portions (21, 22) being made in one piece.7) Extrusion head (1) according to any one of the preceding claims, wherein said mandrel (3) is made in one piece with the sleeve (2) or with a portion (21,22) of the sleeve ( 2 ) .8) Extrusion head (1) according to any one of the preceding claims, wherein said sleeve (21) comprises a plurality of diffusers (29) made of a heat conductive material, said diffusers (29) being inserted into or embedded in suitable seats (291) made in a wall of the sleeve ( 2 ) .9) Extrusion head (1) according to any one of the preceding claims, wherein said rods (33) are homogeneously arranged about a longitudinal axis (X) of the mandrel (3) to form at least one crown of rods. 10) Extrusion head (1) according to claim 9, wherein the mandrel (3) comprises multiple crowns of rods (33) , concentrically arranged about a longitudinal axis (X) of the mandrel (3) .11) Extrusion head (1) according to claim 9 or 10, wherein, at a base of the crown of rods (33) , a plurality of collection basins (38) uniformly distributed about the circumference is present.12) Extrusion head (1) according to claim 11, wherein the mandrel (3) comprises, downstream of the collection basins (38) , a raised part (37) in the form of an annular band surrounding the crown of rods (33) .

Images