Extrusion head for producing tubes as preforms for containers to be formed

Abstract

2. An extrusion head for producing tubes as preforms for containers to be formed from plasticized plastic material, in particular intended for use in forming, filling and closing machines, at least consisting of individual head parts (22, 24) which define a circumferential annular gap (26) between them, which opens into the open for the discharge of the plastic tube and which, at least in the discharge region, comprises a guide device (32) which has at least one chamber (34) open at both ends and through which at least one assignable filling device (16), such as a tubular filling mandrel (36), can pass, characterized in that at least one insulating device (46) is present as part of the guide device (32), which at least partially forms the chambers (34) and can be passed through by the respective filling device (16) in the same way as the other guide device (32).

Description

The invention relates to an extrusion head for producing hoses as preforms for containers to be molded made of plasticized plastic material, in particular for use in molding, filling and closing machines, at least consisting of individual head parts, which delimit between them a circumferential annular gap, which comes into the open for the discharge of the plastic hose and which comprises, at least in the region of the discharge, a guide device, which has a plurality of individual chambers open towards both ends, which can each be traversed by at least one attributable filling device, such as a tubular filling mandrel.DE 10 2008 028 754 A1 discloses an apparatus for producing and filling containers, in which at least one tube of plasticized plastic material can be extruded into an open mold, wherein at least the filling material can be introduced into respective containers by means of a filling device which has a plurality of functional channels which are separate from one another, wherein a mandrel shielding hood is present which has at least one functional space and which, in its functional position, produces a medium-conducting connection between its respective functional space and the respectively assignable functional channel of the filling device. This opens up the possibility, via a respective functional channel of the filling device, of introducing into the functional space or the functional spaces within the shielding hood those media which are suitable for cleaning, sterilizing, cooling / drying etc. in order to bring the apparatus into an aseptic state for starting a production period.DE 10 2020 004 564 A1 discloses an apparatus together with a method for producing plastic containers by means of a molding, filling and closing method, at least comprising a molding device with individual molding tools which can be moved with respect to one another repeatedly from an open receiving position into a molding closed position, and an extrusion unit by means of which at least one extruded plastic tube can be introduced into the open receiving position of the molding tools, wherein the extrusion unit can be moved in the opposite direction with each extruded plastic tube by means of a displacement device with respect to the molding device arranged in a fixed manner in each position of the molding tools. In this way, in the case of continuous extrusion of the plastic tube by means of the extrusion unit, the actual shaping can be carried out in a stationary manner by means of the molding tool, which simplifies the apparatus structurally as a whole, since the molding tool does not first have to be kinematically moved back and forth, as seen in the extrusion direction of the plastic tube, in a complicated manner.EP 3 684 695 B1 discloses a device for producing and filling containers, in which at least one tube of plasticized plastic material, which comes from an extrusion head, can be extruded into an open shape, wherein at least the filling material can be introduced into the respective container by means of filling mandrels, which pass through the extrusion head along at least one row of passages at least during operation, wherein the extrusion head has a cuboidal shell and wherein the overall height of the extrusion head, as viewed parallel to the orientation of the respective filling mandrel, is smaller than the length of the extrusion head along the respective row of passages. The cuboidal shell consists of at least one lower and one upper head part or shell part, of which at least one part has a duct guide for the plasticized plastic material, which duct guide contains an annular space, in the middle of which a receiving web is arranged, which has individual longitudinal receptacles in the form of the passages for the respective filling mandrels to pass through. The design of the extrusion head in this respect as a flat shell enables a corresponding reduction in the height of the base frame surrounding the extrusion head, which base frame forms the base for the construction of the device units lying above it, so that overall a substantial reduction in the overall height for the known device and a correspondingly reduced need for installation space result.Within the scope of the filling of the respective filling material into the individual container products including ampoules, a particular challenge arises if the respective filling material is heat-sensitive, such as, for example, protein-containing solutions. This is described in detail in the publication by Wei Lu, Scott Faulhaber, Samir U. Sane, Philipe Lam Biopharmaceutical Manufacturing Using Blow-Fill-Seal Technology, BioPharm International, BioPharm International-07-01-2011, Volume 24, Issue 7.In order to effectively counter this particular challenge, EP 3 157 816 B1 discloses a method and apparatus for blow-fill seal packaging of a heat-sensitive product which is subject to denaturation and / or precipitation if the product becomes too warm, the following measures being proposed in order to counter this:forming a container for obtaining a container,cooling to a container temperature between 60°C and 80°C after forming the container, the cooling step consisting of waiting 2 to 5 seconds from the time of forming the container,filling the molded container with the heat-sensitive product after the cooling step, wherein the product used in the filling phase has a temperature between about 0° C. and about 20° C. and has a temperature of at most 40° C. immediately after filling the molded container, andclosing the container.The respective container is accordingly cooled in a cooled form for a certain period of several seconds after blow molding and before filling it, in order to reduce the heat input into the filling material, which can reduce the production output (number of containers to be produced per hour) with a view to waiting for this purpose.If the respective filling material is cooled strongly via a heat exchanger and is filled into the container product at a very low temperature, this inevitably leads to the filling mandrels of the filling device being subjected equally to strong cooling and, insofar, also indirectly to the plastic tube delivered adjacent to the filling device via a conventional ring or inner nozzle of the extrusion head during the extrusion, which can ultimately lead to non-uniform tube extrusion and, in the worst case, to production faults.In order to overcome these disadvantages, WO 2023 / 102256 A1 has proposed a method and a device for dynamic cooling which contribute to reducing the filling temperature for vaccines with two different cooling stages, which enables a gentle cooling process without adversely affecting the plastic tube delivery. This alone again results in increased equipment complexity.Proceeding from this prior art, the object of the invention is to create an extrusion head for producing hoses as preforms for containers to be molded made of plasticized plastic material, in particular for use in molding, filling and closing machines (BFS machines), which, while avoiding the disadvantages described, allows an improved temperature control for the actual production process. An object in this respect is achieved by an extrusion head having the features of patent claim 1 in its entirety. Further design features of the extrusion head according to the invention are the subject matter of the dependent claims 2 to 10.As a result of the fact that, according to the characterizing part of patent claim 1, at least one insulating device is present as part of the guide device, which insulating device can pass at least partially through the chambers forming the respective filling or mandrel device in the same way as the other guide device, the filling mandrels are at least partially accommodated and guided in chambers of the insulating device, so that the mandrels and thus the filling material can only insignificantly absorb heat from the heated extrusion head and the extruded warm plastic tube, which can play a role in particular when the filling material is cooled to a correspondingly great extent, which is regularly the case if the filling material is heat-sensitive dispensers, such as, for example, protein-containing vaccines, which have to be thermally saved during the filling process. In any case, the insulating device substantially reduces the heat flow from the hot plastic tube and extrusion head to the guide device and the filling material.In a preferred embodiment of the extrusion head according to the invention, it is provided that the insulating device has a strip-shaped base body with one or more insert strips, which is inserted into the extrusion head on the delivery side of the plastic tube. Preferably, it is further provided that the insert strips consist at least partially of a high-temperature-resistant plastic material with low thermal conductivity and a low thermal expansion coefficient, preferably of polyetheretherketone (PEEK). The filling mandrels of the filling device are surrounded by the insulation insert in such a way that the heat flow from the heated extrusion head and the extruded tube in the circumferential annular gap to the filling mandrels is greatly reduced. The thermal insulation in this respect makes it possible, on the one hand, to substantially minimize cooling of the inner nozzle or annular gap and thus of the plastic tube guided therein and, on the other hand, to substantially minimize heating of the filling mandrels with their possibly heat-sensitive contents of filling material. In addition to energy savings during operation, this also allows a more stable production process for the preforms, from which the container products to be formed are produced, arranged in a molding tool on the output side of the extrusion head.In the aforementioned sense, it has proven to be particularly thermally advantageous for the process if the insulating device, viewed in the direction of travel of the filling mandrels of the mandrel device, has an overall height arranged at a predeterminable distance and parallel to the annular gap, which at least partially corresponds to the length of the annular gap arranged parallel thereto on the discharge side. In a further preferred embodiment of the extrusion head according to the invention, it is provided that the base body is formed in one piece or in multiple pieces in the form of a frame and preferably from a metallic material, into the respective recess of which an insert strip can be introduced in each case so as to be able to be assigned. Preferably, it is further provided that the respective insert strip has, arranged in series one behind the other, diameter-identical passage openings which can be brought into register with corresponding passage openings in the frame, which are arranged at least during operation coaxially with the passage openings. In this way, a multi-part plastic insert, preferably in the form of individual plastic strips, is accommodated in a U-shaped metallic frame in such a way that this stable frame can reliably absorb and dissipate the compressive forces arising during operation, whereas the strip-shaped insulating bodies, which consist of insulating material, are protected in the form of the respective insert strip from deformation and other mechanical impairment.In a further preferred embodiment of the extrusion head according to the invention, it is provided that the insulating chambers of the insulating device are divided into groups which preferably maintain a predeterminable distance from one another. Preferably, it is further provided that the group division into rows and columns takes place parallel along the recess in the frame or running transversely thereto. This results in a structured structure for the insulating device as a whole, which can be adapted to a predefined number of filling tubes of the filling device in such a way and can be implemented in a stable manner, which can vary depending on the configuration of the BFS machine.In a further preferred embodiment of the extrusion head according to the invention, it is provided that the two initially arranged chambers of the insulation device are kept free of insulation. In this way, reliable insulation is provided in particular for the centrally positioned filling mandrels of the filling device, wherein this is not absolutely necessary for the two chambers arranged first of all and these can instead be designed as metallic chambers for the further stiffening of the entire system.In a further particularly preferred embodiment, it is provided that the base body has a flange-like widening towards the outside on the edge in the direction of the delivery side, which widening serves in each case for passing through at least one fixing means, such as a fixing screw, for fixing the base body to an adjacently arranged head part. In this way, the base body can be attached to the extrusion head in such a way that it can be exchanged, which facilitates assembly and maintenance work and an exchange.The extrusion head according to the invention is explained in more detail below with reference to various exemplary embodiments according to the drawing. In this context, the figures show in schematic and not to scale FIG. 1 shows a cross section through a first exemplary embodiment of the extrusion head; FIG. 2 shows a perspective view of a longitudinal section through the extrusion head according to FIG. 1 ; FIG. 3 shows a perspective view of a longitudinal section through a base frame for receiving a one-piece insulating body in the manner of an insert as used in FIGS. 1 and 2 ; FIG. 4 is a perspective top view of a rectangular block-shaped insert made of insulating material for use in the frame according to FIG. 3 ; FIG. 5 shows a detail of a lower side view according to FIG. 2 with the base frame according to FIG. 3 and the insert according to FIG. 4 in a functional position; FIG. 6 shows a longitudinal sectional view comparable to FIG. 2 for a further exemplary embodiment of an extrusion head of flat construction; and FIGS. 7 to 9 again show a perspective side view of a further insulation device consisting of a further base frame, as is shown in FIG. 8, and inserted slide-in strips as insulation parts, of which a single insulation part is shown in FIG. 9.The extrusion head shown by way of example in FIGS. 1 and 2, which is also referred to in technical terms as a tube head, is connected upstream, in the vertical production direction, as seen from top to bottom, of a device for producing container products to be formed, such as ampoules or bottles (not shown), from plasticized plastic material. This molding apparatus has individual molded parts 12 running along a common vertical production line 10, which are movable in pairs towards and away from each other in order to close or open a common production mold 14, in which the respective container product is molded, which is then filled with filling material by means of a filling device 16 and is then hermetically sealed via a head part. The containers moved along the production line 10 emerge filled and hermetically sealed at the underside of the molding apparatus, namely in the form of a container chain for further use. For the production function in question, the individual molded parts 12 interacting with one another in pairs are moved by means of a respectively self-contained mold chain 18, which is guided in each case in a revolving manner via individual deflection rollers 20. Such forming devices are known and are accordingly only indicated on their entry side in FIG. 1, as long as this is important for explaining the function and the structure of the extrusion head. A forming device of this kind with individual molded parts which are guided along container or mold chains in pairs in cooperation with one another is disclosed, for example, by DE 10 2008 006 073 A1.Belonging to this molding device or similarly constructed molding devices (not shown) is the extrusion head, which serves for producing hoses as preforms for the container products to be subsequently molded from plasticized plastic material, in particular for use in a molding, filling and closing machine, as partially shown in FIG. 1 by way of example. The extrusion head consists of individual components and has at least two head parts 22, 24, which delimit between them a circumferential annular gap 26, which with its gap or nozzle outlet 28 on the underside 30 of the extrusion head enters the open for the dispensing of the plasticized plastic tube. The head part 24 is also referred to as an inner nozzle. As is shown in particular in FIG. 2, the nozzle-like annular gap 26 comprises, at least in the region of the discharge of the plastic tube, a guide device 32 which has a multiplicity of individual chambers 34 which are open towards both ends and through which, forming a guide, in each case at least one attributable filling device 16, such as a tubular filling mandrel 36 or filling tube, can pass. For the sake of simplicity in illustration, FIG. 2 shows only a single filling mandrel 36 in the extended filling state according to FIG. 1 ; however, it is understood that an independent filling mandrel 36 is provided for each chamber 32, that is to say twenty filling mandrels 36 for the same number of chambers 34 in the present case, wherein the said number can vary depending on the production machine. In the position of the filling device 16 shown in FIGS. 1 and 2, all filling pipes or filling mandrels 36 of the same design, as shown, also assume the same position, which corresponds to a dispensing position for the filling material which is dispensed to the container hollow product formed from the preform in each case before closing the container.In the following exemplary embodiment, five adjacent chambers 34 running parallel to one another are each combined to form a group 38 which is separated from the next group 38 by a web-like intermediate wall 40 and which further stiffens, in particular makes pressure-stable, the overall construction by way of its predeterminable wall thickness. The chambers 34 open toward both ends or end faces together form a foot-side part of the guide device 32, which at least partially forms the respective guide for an allocable filling device 16, which extends from the upper side 44 of the extrusion head to the lower side 30 thereof in the filling position. All chambers 34 have identical or substantially identical internal diameters, which are adapted to the external diameter of the respective filling mandrel 36, and which allow unimpeded passage for the respective filling device 16. In this way, twenty container products filled with filling material can be produced in a row per production step, as described, which container products, combined in a type of container card, are subsequently separated from the latter, for example by means of punching for later use.As part of the mentioned guide device 32, at least one insulating device 46 is present, which can be passed at least partially through the chambers 34 forming the respective filling or mandrel device 16, in the same way as the other guide device 32. The nozzle-like annular gap 26 mentioned above guides the plasticized plastic material for producing a jacket-like closed plastic tube, which later, introduced into the molding device, forms the respective container wall and the head-like closing part, from a central feed channel 48 arranged laterally on the extrusion head, which receives the plasticized plastic material from an extruder screw unit (not shown) in the usual manner. The extruded plastic material is first introduced via the inlet channel 48 into a circumferential annular channel 50 with a rectangular cross section and an enlarged volume arranged within the extrusion head, before the plastic material is discharged from there from the top to the bottom in the vertical direction as viewed in the direction of the FIGS. 1 and 2 via the nozzle outlet 28 on the underside 30 of the extrusion head, namely after passing through the annular gap 26 arranged between the annular channel 50 and the nozzle outlet 28, These discharge in the downward direction towards the nozzle outlet 28. Between the pairs of annular gap sections 52 and 54 there is a feed device 56 which extends obliquely in the direction of the nozzle outlet 28 and which establishes the relevant fluid connection between the sections 52, 54 so that a continuous material flow for the plasticized plastic material is obtained starting from the annular channel 50 to the nozzle outlet 28. Furthermore, below the obliquely running feed device 56 towards the two arcuate ends 57 of the annular gap 26, as shown in FIG. 2, there is in each case provided in pairs opposite one another at least one adjusting device 58 with an engagement screw 60 (see FIG. 5 ) which can be actuated from the outside and by means of which the discharge quantity of plasticized plastic material at the nozzle outlet 28 can be at least partially adjusted. For this purpose, the adjusting device 58 engages with its associated engagement screw 60 in the lower region of the annular gap 26, which can also have a flow chamber 61 before the nozzle outlet 28 that widens the gap diameter for homogenizing the plastic medium flow (cf. FIG. 5 ).As can be seen in particular from FIGS. 3 and 4, the insulating device 46 has a strip-shaped base body 62, which can be inserted into the plastic tube on the delivery side of the plastic tube, i.e. viewed from the underside 30 of the extrusion head. The strip-shaped base body 62 in this respect has a frame 64 which leaves a rectangular recess 66 free for receiving a block-like insert or insert strip 68, as is illustrated by way of example in FIG. 4. The recess 66 or the receiving space spanned by the frame 64 is bounded by two parallel strip bodies 70, 72, which are held at a distance from one another by transverse webs 74 of the same structure. The transverse webs 74 in question are a one-piece component of the lower strip body 72 and have on both sides two extremely arranged chambers 34 which are kept free from an insulating part. The two chambers 34 arranged first of all in this respect, like the two strip bodies 70, 72, consist of a metal material. Starting from the two vertically extending transverse webs 74, two flange-like widenings 76 are provided on the edge and on the bottom, each of which has passage openings for passage of a fixing means, such as a fixing screw 78. In this way, the main body 62 as a whole can be secured interchangeably on the underside 30 of the extrusion head and the insulating insert strip 68 can be separated from the frame 64 as required, for example for cleaning, as soon as the main body 62 is removed from the associated receptacle 80 in the extrusion head, which is at least partially delimited by the head part 24.As is shown in particular in FIG. 5, the insulating device 46, viewed in the direction of travel of the filling mandrels 36 of the filling device 16, has an overall height which corresponds at least to the length of the annular gap 26 on the discharge side, which length is arranged parallel thereto, at a predeterminable distance and parallel to the annular gap 26. The height of the transverse webs 74 (see FIG. 3 ) of the frame 64 corresponds substantially to the height of the lower further annular gap sections 54 This is precisely the thermally delicate region where the annular gap 26 is adjusted in the direction of the filling device 16 with its tube-like filling mandrels 36, in which the lower further annular channel sections 54 are at a smaller distance from the filling device 16 than the upper annular gap sections 52, which are further spaced apart via the conical feed device 56, which plays a role in particular when the filling device 16 is in its positions releasing the filling material shown in FIGS. 1 and 2. It is precisely in this case that thermal decoupling of cold filling material in the filling device 16 and the warm or hot plasticized plastic material in the annular gap 26 close to the nozzle outlet 28 is of great advantage.According to the illustration according to FIG. 3, the through-openings 82 of both strips 70, 72 have the same or substantially the same free inner diameter and are arranged coaxially with respect to one another grouped into pairs. Furthermore, the respective strips 70, 72 receive, between the respective through-openings 82, which are arranged opposite one another in groups, intermediate wall sections 84 (FIG. 5 ) which are reinforced in terms of width and which are likewise in vertical alignment with one another opposite one another. The wall thickness of these intermediate wall sections 84 for both strips 70, 72 corresponds substantially to the wall thickness of each intermediate wall 40 of the block-like insert strip 68; the respective insulation body according to FIG. 4 has comparable diameter access openings 86, which then in any case during operation of the extrusion head preferably come into coaxial alignment with the adjacently arranged access openings 82 of both strips 70, 72. Before startup, however, a certain lateral offset may be present, as can be seen from FIG. 5, this offset being only given up by mechanical and / or thermal stress during operation in favor of a congruence of passage openings 86 to passage openings 82, which, in addition to any tolerance compensation, also contributes to increasing the overall rigidity of the overall system in this region. FIGS. 4 and 5 also show that the insulating insert strip 68 is of shortened design with respect to its installation length, since the two outermost chambers 34 are not part of the insulating device 46. Thus, the strip according to FIG. 4 shows at the edge only four fully extending through-openings 86, whereas the two middle groups 38 are provided with five chambers 34 and with five through-openings 86 each and are also correspondingly spaced apart from the two outer groups of quads via the reinforcing partitions 40.As can be further seen from FIG. 4, the insert strip 68 can also have so-called support air bores 88, which can be brought into register with support air bores 88 in the strips 70, 72 (only partially shown), in order in this way to achieve a guidance of support air into the interior of the shaped hose during the hose shaping. Furthermore, centering means 90 can be provided both on the insert strip 68 and in the frame 64 in order to be able to ensure an exact positioning of the insert strip 68 with respect to the frame receptacle for the base body 62, as illustrated in FIGS. 7 to 9.Polymers with low thermal conductivity and a low thermal expansion coefficient are advantageously used for the insert or insert strip 68; the latter simplifies the construction as a whole, which has to take into account a temperature range during operation of the components of the extrusion head of about 20° C. to about 250° C. To reduce the thermal expansion, it is also possible to use fiber- and / or particle-reinforced polymers, for example PEEK with a 30% carbon or glass fiber content (available under the trade names TECAPEEEK CF30 or Ketron GF30). These materials have a linear thermal expansion coefficient in the range from 23° to 150° C. of less than 4×10 -5 / K.The insert or insert strip 68 is further preferably and at least partially made of a material having a thermal conductivity at 25° C. according to DIN52612-1 of less than 0.5 W / (m x K), preferably less than 0.4 W / (m x K).The insert or insert strip 68 is further preferably and at least partially made of a material with a high elastic modulus according to ISO 527 (sometimes referred to as Young's modulus in technical terms) of more than 2.5 GPa, preferably more than 3 GPa.The insert or insert strip 68 is made, in particular in the production of containers for medical purposes, more preferably and at least partially of a material with proven suitability for contact with foods (also "food compliance" for short), as regulated, for example, for the EU in the EU regulations 1935 / 2004, 10 / 2011 and 2023 / 1442 or for the USA by the Food and Drug Administration (FDA) Food Contact Substances Notification Program (FCN).The insert strip 68 can furthermore consist at least partially of a plastic with a continuous use temperature of more than 150°, and preferably consists of -referred to below according to DIN EN ISO 1043-1-PEEK, PEK, PPS, PSU, PES, PPSU, PAI, a fluoropolymer or a liquid crystal polymer (LCP).The linear thermal expansion coefficient of the plastic for the insert or insert strip 68 according to DIN53752 is in principle less than 7×10 -5 / K, preferably less than 6×10 -5 / K, particularly preferably 4×10 -5 / K or less. Furthermore, it has proven advantageous for the thermal decoupling from the produced plastic tube with respect to the filling device 16 if the engagement gap between the passage openings 86 of the insert strip 68 and the outer circumference of the tube-like filling tube 36 of the filling device 16 can be predefined and preferably has a value of 0.5 mm within the scope of the guide.Starting from the first embodiment according to FIGS. 1 to 5, a further embodiment is presented in FIGS. 6 to 9; however, only insofar as it differs substantially from the preceding embodiment. The same structural components are also provided with the same reference numerals and the explanations made hitherto apply also to the further exemplary embodiment.FIG. 6 again shows a longitudinal section of a further embodiment of the extrusion head, which now has a significantly flatter design than the first exemplary embodiment, and the feeding of the plastic melt starting from an extruder screw device (not shown) again takes place via a feed channel 48, which this time, however, is placed on the upper side 44 of the extrusion head. Essential differences with respect to the first embodiment are that the annular gap 26 is now guided continuously vertically downwards in the direction of the nozzle outlet 28, starting from the annular channel 50. Furthermore, the annular channel 50 is at least partially delimited by an upper head part 24 and by a lower head part 22, which (50) is in turn connected to the feed channel 48 for the plasticized plastic material via a feed 92 between the parts 22, 24.Further essential differences exist in the construction of the insulating device 46, as shown in FIGS. 7 to 9. To this end, the strip-shaped base body 62 according to FIG. 7 has a frame 64 according to FIG. 8, which, in addition to an upper strip body 70 and a lower strip body 72, has two intermediate strips 94 lying therebetween, wherein all strips are at the same vertical distance from a respectively adjacent strip, which in each case forms an associated recess 66 for receiving an insert or insert strip 68, as is illustrated by way of example in FIG. 9. This results in a strip-shaped base body 62 in the assembled state according to FIG. 7 and the structure in this respect is in particular thermally and mechanically stable. While the insert or insert strip 68 according to FIG. 9 again consists of a correspondingly suitable plastic insulating material, the frame 64 can again be constructed from metallic materials. In the case of the frame construction according to FIG. 8, in contrast to the first-mentioned frame solution, the upper rail body 70 and the two intermediate rails 94 are integral components of a U-shaped upper frame part 96, which is fixedly connected, in particular fixedly screwed, to a lower, substantially flat frame part. The two intermediate strips 94 also have through-openings 82, which are in coaxial alignment with the adjacently opposite through-openings 82 of the upper and lower strip bodies 70 and 72, respectively. For the sake of simplicity, not all openings are designated by the reference numeral 82, nor are the respective passage openings 86 within the insert strip 68, which are brought into register with the associated passage openings 82 at least during operation of the extrusion head. It is understood that support air bores 88 (not shown) can also be present in the solution according to FIGS. 6 to 9, and centring means 90 are again used for fixing the respective insert strip 68 in the clamped frame 64. In this respect, the rows run parallel along the respective recess 66 in the frame 64 or the columns run transversely thereto. In the present embodiment, too, the two initially arranged chambers 34 of the insulating device 46 are again kept free of insulation.With the solution according to the invention, it is possible, via the respective insulating device 46, on the one hand to substantially minimize cooling of the inner nozzle in the form of the annular gap 26 and thus of the plastic hose abutting thereon and, on the other hand, heating of the filling mandrels 36 of the filling device 16. It has been found that, in addition to energy savings and the protection of the filling material from overheating, this leads to more stable production processes in container production during operation with the extrusion head. Due to the illustrated construction of a frame 64 with the respective associated insert or insert strip 68, a mechanically loadable, in particular pressure-stable, insulating device 46 is created with the extrusion head during the extrusion operation. This thus does not correspond to the prior art.

Claims

Extrusion head for producing hoses as preforms for containers to be molded made of plasticized plastic material, in particular for use in molding, filling and closing machines, at least consisting of individual head parts (22, 24), which delimit between them a circumferential annular gap (26), which comes into the open for the discharge of the plastic hose and which comprises at least in the region of the discharge a guide device (32), which has at least one chamber (34) open towards both ends, which can be traversed in each case by at least one attributable filling device (16), such as a tubular filling mandrel (36), characterized in that as part of the guide device (32) at least one insulating device (46) is present, which can be traversed at least partially by the respective filling device (16) forming the chambers (34) in the same way as the other guide device (32).Extrusion head according to claim 1, characterised in that the insulating device (46) has a strip-shaped base body (62) which is inserted into the extrusion head on the delivery side of the plastic tube.Extrusion head according to claim 1 or 2, characterised in that at least one insert strip (68) in the base body (62) consists at least partially of a plastic material with low thermal conductivity, high modulus of elasticity and a low thermal expansion coefficient with detectable food conformation, preferably of polyetheretherketone (PEEK).Extrusion head according to one of the preceding claims, characterized in that the insulating device (46), as viewed in the direction of travel of the filling mandrels (36) of the filling device (16), has an overall height which, when viewed at a predeterminable distance and arranged parallel to the annular gap (26), corresponds at least partially to the length of the annular gap (26) arranged parallel thereto on the delivery side.Extrusion head according to one of the preceding claims, characterized in that the base body (62) is formed in one piece or in multiple pieces in the form of a frame (64), into the respective recess (66) of which an insert strip (68) can be introduced in each case, such that it can be associated.Extrusion head according to one of the preceding claims, characterized in that the respective insert strip (68) has, arranged in series one behind the other, diameter-identical passage openings (86) for the chambers (34), which can be brought into register with corresponding passage openings (82) in the frame (64), which are arranged at least during operation coaxially with the passage openings (86).Extrusion head according to one of the preceding claims, characterized in that the insulating chambers (34) of the insulating device (46) are divided into groups (38) which preferably maintain a predeterminable distance from one another.Extrusion head according to one of the preceding claims, characterized in that the group division of the groups (38) into rows and columns takes place parallel along the recess (66) in the frame or running transversely thereto.Extrusion head according to one of the preceding claims, characterized in that the two initially arranged chambers (34) of the insulating device (46) are held free of insulation.Extrusion head according to one of the preceding claims, characterized in that the base body (62) has, on the edge side in the direction of the delivery side, a flange-like widening (76) outwards, which in each case serves for passing through at least one fixing means, such as a fixing screw, for fixing the base body (62) to an adjacently arranged head part (24).

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