DE102022122997A1 - METHOD AND DEVICE FOR DISCONSTRUCTING BRAIDED SEMI-FINISHED PRODUCTS - Google Patents

Abstract

The subject of the present invention is a method and a device for debulking braided semi-finished products made from hybrid yarns or tapes. It is envisaged that a semi-finished product braided onto a core is passed through a heating unit in which the polymeric components of the hybrid yarns or tapes are melted. In a subsequent pressing unit, the braid is compressed radially and debulked and cooled so that it remains in the debulked state.

Description

The invention relates to a method and a device for reducing the production-related bulk during the braiding process of thermoplastic semi-finished products such as hybrid yarns or tapes.

The braiding process with thermoplastic semi-finished products such as hybrid yarn or thermoplastic tapes results in a pronounced bulking behavior of the textile preform/preform. Thermoplastic tapes are semi-finished products that are available as strips or tapes, usually prefabricated on a spool or roll, which consist of at least reinforcing fibers and a thermoplastic polymer component that is integrated into the semi-finished product. Thermoplastic hybrid yarns are preferably also pre-assembled on a spool or roll. In addition to reinforcing fibers, they also contain thermoplastic polymer components. The polymeric components preferably completely surround the reinforcing fibers of the tape and, in the case of the hybrid yarn, are present as thermoplastic polymer fibers that are mixed with the reinforcing fibers. Furthermore, the thermoplastic polymeric components can be contained in the thermoplastic semi-finished products as particles melted onto the reinforcing fibers.
When implementing a high wall thickness with several braid layers, the bulking behavior results in an increased preform thickness, which is reduced in the later consolidation process by pressing under the influence of pressure and temperature. This leads to relative movements of the fibers within the preform, which can cause the fibers to lose their straight alignment in the plane.
If a tube blowing process is used as a consolidation process, the preform must expand in the consolidation process against an external mold wall due to the internal pressure of the tube membrane. This leads to relative movements between the braid layers, which can lead to expansion difficulties due to the interlaminar friction. In addition, the expansion capacity of textile composites is limited due to the textile's locking mechanisms.
In a consolidation process with isothermal tool temperature control, for example a pressing process or tube blowing process, the preform produced must be heated without pressure outside a mold, for example using a circulating air oven, hot gas or infrared radiation, and is then transferred to the mold and pressed there. Due to the high bulk and the high proportion of air within the preform, heating without pressure is difficult to implement. A complex pre-consolidation process is usually carried out in order to be able to further process the preform better.

Approaches to solutions or procedures that can also be helpful for the problems mentioned are known from the prior art.

The WO 2010/150022 A1 discloses a method for producing flat prepregs. Reinforcing fibers and matrix material are treated with a compression tool (mechanical pressure), optionally under the influence of heat, in order to achieve an intimate connection between the two materials. Unidirectional conductive fibers are used as the fiber material. The result is a flat structure, in particular a tape, in which the outer fiber layer is almost free of matrix material. This is intended to increase the lateral conductivity of the surface structure and, in perspective, that of several surface structures stacked on top of each other. The material is intended as a semi-finished product for the aviation industry.
In the present context of the publication, the use of mechanical pressure when connecting fiber material and matrix material in a continuous manufacturing process can be seen in particular.

In the DE 10 2005 031 039 A1 a method is disclosed which involves braiding/wrapping a locally radially recessed mold core with a fiber structure consisting of fiber composite reinforcing fibers. The reinforcing fibers are pressed against the mold core at least during the braiding process in the locally recessed core areas, progressively synchronous to the fiber deposition point, with a pressing force above the fiber tension. The pressing force should optionally be maintained at least in the recessed core areas until the fiber composite material has hardened. To fix the fibers, they can contain a binding agent. The procedure mentioned should also provide recessed core areas whose contour the braid would otherwise not follow due to the fiber tension with an adjacent braid.
A suitable device is described as a plurality of clamps with expandable membranes on the clamping surface. The clamps should surround adjacent areas of the braided core and press the braid onto the core by applying pressure to the membranes. As the core progresses, the rearmost clamps should be loosened and reattached at the front, on the area of the core that has just been braided. The procedure and the device used are complex and difficult to control. In addition, the closing and subsequent expansion of the membranes creates a bend in the fiber mesh on the closing edges of the clamps, as the contact force is not uniform around the core. The one after the DE 10 2005 031 039 A1 processed Fibers have no thermoplastic components. Only a braid made of pure reinforcing fibers is attached to a core shape.

There is therefore still the task of proposing a method and a device for reducing the production-related bulk during the braiding process with thermoplastic semi-finished products such as hybrid yarns or tapes. The device is intended to support continuous production in a simple and cost-effective manner.

According to the invention the object is achieved using a method according to claim 1. A device suitable for carrying out the method is disclosed in claim 6. Advantageous embodiments of methods and devices are disclosed in the dependent claims.

1. a. Flechten der Tapes oder der Hybridgarne auf einem längserstreckten Kern zu einem gebauschten geflochtenen Halbzeug,
2. b. Kontinuierliches Ziehen des Flechtkernes in einer axialen Zugrichtung mit dem aufliegenden gebauschten geflochtenen Halbzeug durch eine Heizeinheit und unmittelbar nachfolgend mindestens eine Anpresseinheit,

wobei

• c. die Heizeinheit das gebauschte geflochtene Halbzeug über den Schmelzbereich des thermoplastischen Polymers erwärmt,
• d. die Anpresseinheit das erwärmte gebauschte geflochtene Halbzeug auf den Kern drückt und so entbauscht,

dadurch gekennzeichnet, dass das Anpressen des erwärmten gebauschten geflochtenen Halbzeugs um den Kern herum erfolgt und während des Andrückens eine Abkühlung des entbauschten geflochtenen Halbzeugs erfolgt.The method according to the invention for debulking semi-finished textile products made from braided tapes or hybrid yarns provides for at least the following process steps to be carried out:

1. a. Braiding the tapes or hybrid yarns on an elongated core to form a bulky braided semi-finished product,
2. b. Continuous pulling of the braided core in an axial pulling direction with the bulky braided semi-finished product lying on it by a heating unit and immediately afterwards at least one pressing unit,

where

• c. the heating unit heats the bulked braided semi-finished product over the melting range of the thermoplastic polymer,
• d. the pressing unit presses the heated, bulked, braided semi-finished product onto the core and thus de-bulks it,

characterized in that the heated, bulked, braided semi-finished product is pressed around the core and the de-bulked, braided semi-finished product is cooled during the pressing.

In addition to reinforcing fibers, the tapes or hybrid yarns have a polymeric thermoplastic component (polymer). The thermoplastic component becomes liquid above the melting range and flows into spaces between the reinforcing fibers. As the solidification range falls below, the thermoplastic component solidifies and glues the reinforcing fibers together. The melting range or the solidification range is a material property and must be determined separately for each polymer component used. The determination of the melting range or the solidification range is preferably carried out in accordance with DIN EN ISO 11357 using dynamic difference thermal analysis (DSC).

The core is preferably designed to be elongated, for example in the form of a cylindrical rod or a tube. The cross section is preferably circular. However, oval, egg-shaped or polygonal cross-sections are also possible. It is essential that no cross-sectional jumps occur along the longitudinal extent of the core, but rather only slight, continuous cross-sectional expansions or reductions.

In one process variant, steps a. until d. repeated with reversal of the pulling direction. In this way, another layer is braided over an already de-bulked layer of braided tapes or hybrid yarns and then de-bulked. This can be repeated several times so that a body of any thickness is created from de-bulked braided tapes or hybrid yarns as a semi-finished product.

The braided tapes or hybrid yarns are heated either directly, for example by heating the core or inductive heating of the reinforcing fibers if they are electrically conductive (e.g. in the case of carbon fibers as reinforcing fibers) or indirectly, for example using radiant heaters, heating lamps or hot air blowers.

The braided tapes or hybrid yarns with the thermoplastic polymer portion heated above the melting area are pressed on in the pressing unit by pressing the fibers radially from the outside in the direction of the longitudinal axis of the core. By falling below the solidification range, while the contact pressure is still acting, the thermoplastic polymer component solidifies and glues the braided tapes or hybrid yarns together, so that the compressed, de-bulked shape is retained even after the contact pressure has been lifted.

Optionally, the solidification of the thermoplastic polymer can be supported by cooling. For this purpose, for example, cold air blowers or cooling of the pressing elements of the pressing unit, which come into contact with the braided tapes or hybrid yarns, can be used.

The braided tapes or hybrid yarns are preferably pressed completely around the cross section of the core. It is particularly preferred that no edges or bulges form in places where several elements of the pressing unit that exert contact pressure adjoin one another.

In one embodiment, the braided tapes or hybrid yarns are pressed onto the core in the pressing unit by unrolling several rollers as pressing elements, which are arranged around the core and whose outer surface is adapted to the outer shape of the braided semi-finished product arranged on the core. In one embodiment, several roller arrangements are arranged one behind the other in the pulling direction of the core, so that any bulges or edges of reinforcing material that may arise are pressed on by a subsequent roller arrangement.

Other procedures for applying contact pressure can be carried out in a similar manner and several contact pressure units can be arranged one behind the other. Advantageously, additional cooling of the pressing elements of the pressing unit only occurs in the pressing elements last passed through by a core section in the pulling direction.

In one embodiment, the braided tapes or hybrid yarns can be pressed onto the core by means of several pressure plates as pressing elements adapted to the outer shape of the braided semi-finished product arranged on the core. The pressure plates can have an increasing curvature in the pulling direction, the axis of this curvature being slightly inclined to the axis of the core in the pulling direction. Due to the increasing curvature, a constant pressure is exerted over the entire length of the pressure plates, which is maintained even as the debulking increases.

A device for carrying out the method according to the invention has a braiding device, preferably a braiding wheel, at least one pulling device for moving an elongated core in the direction of its longitudinal axis, at least one heating unit and at least one pressing unit.
The braiding device is designed to deposit (braid) a tubular braided semi-finished product made of tapes or hybrid yarns, wherein the tapes or hybrid yarns have a polymeric thermoplastic component (polymer) in addition to reinforcing fibers, on a longitudinally elongated core.

A braiding wheel has a number of spools that provide the material to be braided (here the tapes or hybrid yarns) on spools. During the braiding process, the coils move around each other in predetermined paths, whereby the material to be braided is removed from the coils and deposited in braided form on a core. Preferably, a relative movement is carried out between the core and the braiding wheel, so that the braided material is progressively deposited on the core.

The pulling device is designed to continuously move the elongated core in the axial direction. Suitable pulling devices are known from the prior art.

Preferably, the core has a constant cross-section over the entire length covered with tubular braided semi-finished product. In particular, the core has no cross-sectional jumps.

The heating unit is arranged in the pulling direction of the core between the braiding device and the pressing unit and is designed to heat the circumference of the tubular braided semi-finished product over the melting range of the thermoplastic polymer.

The heating takes place either directly, for example by heating the core or inductive heating of the reinforcing fibers if they are electrically conductive (for example in the case of carbon fibers as reinforcing fibers) or indirectly, for example by means of radiant heaters, heating lamps or hot air blowers. Several heating processes can optionally be combined.

The pressing unit is designed to compress the tubular braided semi-finished product all around in the radial direction to the longitudinal axis of the core and thus to debulk it. When the tubular braided semi-finished product is compressed, the thermoplastic polymer cools down in such a way that the solidification range is preferably reached when the greatest possible debulking is achieved. As a result, the reinforcing fibers in the debulked state are glued to one another using the thermoplastic polymer. This means that the de-bulked state is retained even after the contact pressure has been removed.

In embodiments of the invention, the pressing unit has several rollers as pressing elements. The rollers are arranged around the core and their lateral surface is preferably adapted to the external shape of the braided semi-finished product arranged on the core. In the case of a core with a circular cross-section, each roller has a lateral surface which is shaped all the way around in accordance with this cross-section. In one embodiment, the use of cylindrical rollers, for example made of an elastomer material, is possible.

The rollers are arranged in such a way that the tubular braided semi-finished product is pressed against the core over the entire circumference. For this purpose, in one embodiment, the rollers are arranged to be movable in the radial direction around the core and are subjected to a force in the direction of the core, for example spring-loaded or pneumatically pressed. In a further developed embodiment, several pressing units or several roller units can be arranged one behind the other. It is possible for the rollers of a second roller arrangement, which are arranged behind a first roller arrangement in the pulling direction, to have a smaller radius of curvature in the shape of their lateral surface than the rollers of the first roller arrangement. This causes contact pressure to continue to be exerted on the braided semi-finished product on the core after a first partial de-bulking, taking into account the already reduced cross-section of the deposited semi-finished product and further compacting it. The number of rolls between successive roll assemblies may vary.

In further embodiments of the invention, the pressing unit has a plurality of sheets as pressing elements, which are arranged around the core and which are spaced apart from the core and the tubular semi-finished product placed thereon on the entry side of the core into the pressing unit and which are in the pulling direction on the tubular Place the semi-finished product and apply contact pressure to it. Since the sheets are only hinged on the entry side of the core into the pressing unit, a spring tension is created on the sheets, which creates a contact pressure. Optionally, the sheets, viewed in the pulling direction, are additionally spring-loaded behind their articulation point in order to be able to exert greater contact pressure. Only spring-loaded sheets are also possible, which do not require spring tension on the sheets. The shape of the sheets in the circumferential direction is advantageously adapted to the outer shape of the tubular semi-finished product placed on the core. Optionally, the curvature of the sheets increases in the pulling direction of the core. Furthermore, several pressing units with sheets or several arrangements with sheets one behind the other in the pulling direction are also possible here as an option.

In a further development, adjacent sheets have a material projection directed in the circumferential direction on a first side and a notch directed in the circumferential direction on the second side. In the case of adjacent sheets, the material projection of a first sheet projects into the notch of an adjacent second sheet in the circumferential direction. Advantageously, there is then no notch of the pressing elements running in the pulling direction. This prevents bulging or edges in the pressed semi-finished product.

It is possible to arrange several pressing units one behind the other. These can have identical or different pressing elements.

In embodiments of the invention, cooling of the braided tapes or hybrid yarns is provided during compression. The cooling preferably takes place shortly before the debulked braided tapes or hybrid yarns emerge from the pressing unit. This advantageously ensures that the fibers of the braided tapes or hybrid yarns are glued to one another by the then solidified polymeric component and that the de-bulked state is retained. Cold air blowers or cooled pressing elements can advantageously be used for cooling.

In further embodiments of the invention, the pressing unit is provided with a sliding coating on the parts that come into contact with the tubular semi-finished product. In this embodiment, this applies in particular to the pressing elements. A PTFE (Teflon) coating, for example, can be used as a sliding coating.

In embodiments of the invention, the device has a braiding device, to which a heating unit and a pressing unit are arranged symmetrically on each side of the braiding device in a mirror image, the pulling device being set up to reverse the pulling direction and the core with the tubular semi-finished product placed thereon through the braiding device to move through into the heating unit and pressing unit on the other side of the braiding device.

A further modification of the device according to the invention provides for one or more sequences of braiding device, heating unit and pressing unit to be arranged in the pulling direction, so that several layers of tubular semi-finished product can be continuously braided and de-bulked one above the other.

The present invention can therefore reduce the maximum necessary expansion of the braid layers by debulking the preform during the braiding process and thus enable certain geometries, wall thicknesses and braid angles that were previously not possible.
The technical invention is able to replace a pre-consolidation process by removing bulking and pre-consolidation during the braiding process, which eliminates the need for downstream pre-consolidation processes.

Spreading the braided semi-finished product while the material is being deposited helps to reduce undulation effects and matrix-rich regions in the component. Due to the mechanical and thermal effects on the For each individual tape structure, the cross-section of the tape changes and the cross-section becomes flat, with both the matrix and fibers being pushed into the width. Due to the flatter cross-sectional geometry in the debulked state, undulation effects at the crossing points are minimized, which positively influences mechanical stiffness properties in the fiber direction. This also has the effect of improving the distribution of the fibers and avoiding local matrix accumulations.

Due to the rigid tape structure, complex geometries have so far been able to be reproduced using the tape braiding process, but the dimensional stability after demoulding from the braided core was a problem, so that the braided structure is under high internal tension, especially with double-curved preforms or the creation of particularly small radii. Through the thermal action of the pressing unit, such internal stresses are advantageously released and additional fixation points are created that counteract unwanted shape changes. This further simplifies the handling and further processing steps of the preform (the semi-finished product produced according to the invention).

The invention is not limited to the embodiments shown and described, but also includes all embodiments that have the same effect within the meaning of the invention. Furthermore, the invention is not limited to the specifically described combinations of features, but can also be defined by any other combination of specific features of all of the individual features disclosed as a whole, provided that the individual features are not mutually exclusive or a specific combination of individual features is not explicitly excluded.

The invention will be explained in more detail below using a few exemplary embodiments. The exemplary embodiments are intended to describe the invention without restricting it.

characters

• 1 shows schematically the invention when debulking a first layer
• 2 shows schematically the invention when debulking another layer
• 3 shows a schematic example of the design of a pressing unit

Embodiment 1 (see Fig. 1, Fig. 3)

In addition to the braiding machine 1, the device has a heating unit 4 and a pressing unit 5.

The braiding machine is, for example, an axial braiding machine (KFH 1/72/48-100) from Herzog GmbH. The thermoplastic tapes or hybrid yarns 2 are braided onto a core 7 using the braiding machine 1. In the present example, hybrid yarns of the type COMFIL-C ^® 55C-PA6-1460 are used. These contain carbon fibers as reinforcing fibers. Furthermore, the hybrid yarns have a weight content of 45% thermoplastic fibers made of polyamide 6. The thermoplastic material has a melting range of 205°C to 225°C. The withdrawal unit 8 (pulling device) pulls the braiding core 7 through the braiding machine 1. The braiding core has a circular cross section with a diameter of 40 mm and has a length to be braided of 2000 mm.

The undoused braided layer 3 is heated in the heating unit 4 over the melting range of the thermoplastic polymer, which is part of the thermoplastic tapes or hybrid yarns 2. For heating, three short-wave round tube infrared heaters with a maximum total output of 4500 watts are used in the heating unit 4. The temperature generated in the thermoplastic tapes or hybrid yarns 2 is 270 ° C. Since this is above the melting range of the thermoplastic polymer, it softens and flows into the spaces between the hybrid yarns 2. Immediately behind the heating unit 4 is the pressing unit 5, which presses the thermoplastic braided tapes or hybrid yarns 2 onto the core 7. The pressing unit has a roller ring 51 ( 3 ) with four rollers 511. A further developed embodiment has a second roller level behind the one in 3 shown first roller level of the rollers 511.

The roller ring 51 has several rollers 511, which are evenly distributed over the diameter of the core 7. In order to debulk the entire circumference, four rollers 511 are arranged in a defined first roller level. The four rollers 514 of the first roller level are distributed on the circumference of the core 7, creating an angle of 90° between them. If there is a second roller level, the four rollers of the second roller level are then offset exactly 45 ° to the rollers 514 of the first roller level, which results in complete coverage of the braid 6. The rollers 511 are as wide as possible and run on a U-frame 514, which is supported by two springs 513 in spring bearings 515 is pressed inside. Each of the springs has the following characteristics (according to DIN 2098); Untensioned length: 33 mm, spring rate R: 5.715 N/mm, length in roller ring 51 with a core diameter of 40 mm: -25 mm, maximum length in roller ring 51: 28 mm. The ends of the U-frames 514 serve as a stop. The roller ring 51 can be divided at the division 6 with a closure (not shown) in order to be able to place the half-shells 512, 517 on the core 7. The 8 compression springs are located on the thinner rods of the U-frames 514, which hold and guide the rollers 511 in position. The springs 513 are compressed to a length of approximately 25 mm with a core diameter of 40 mm. The spring rate and the distance covered by the spring of 8 mm create a force of 45.7 N per spring. This force has a double effect on a roll 1 and thus directly on the core 7 or on the braid. With a diameter of 40 mm there is a force of 91.4 N and with a diameter of 43 mm a force of 108.5 N. The increase in force in between is linear at 5.715 N/mm. The rollers 511 are made of polytetrafluoroethylene (PTFE) and the remaining components of the assembly are made of common structural steel.

By applying pressure and temperature, the individual braid layers are compacted and positioned closer to one another, air and cavities between and in the braid layers are reduced, thus reducing the resulting size of the semi-finished product. The debulked layer 6 has a smaller circumference or diameter than the non-debulked layer 3. This process takes place during the braiding process, which advantageously means that no downstream manufacturing steps for debulking are necessary.

Embodiment 2 (see Fig. 2)

2 shows the invention and the de-bulking process for over-braiding the first de-bulked layer 6 with a further non-de-bulked braid layer 9. This is also compacted by the heating unit 4 and pressing unit 5, which can be adaptively adapted to the diameter. The over-braided and de-bulked second layer 10 can be over-braided again in a next step. The heating unit 4 is designed analogously to exemplary embodiment 1. Analogous to exemplary embodiment 1, the pressing unit 5 has rollers 511, which press the braid onto the core via a spring force. Springs or other pre-tensioned elements can be used here. When the section of the core 7 to be braided is completely covered with a debulked braid layer 6, the braiding material 2 is separated and the core is moved back to the starting position. A second braid layer 9 is then braided in the same way as the first braid layer 3 was laid down and debulked and then debulked as described.

The remaining information corresponds to that from exemplary embodiment 1.

Reference symbols

1

Braiding machine

2

thermoplastic braided tapes or hybrid yarns

3

undebulked first braided layer

4

Heating unit

5

Pressing unit

51

Roll wreath

511

Role of the roller ring

512

Left half shell for dividing the roller ring

513

Spring bearing of the rollers

514

Rack of rolls

516

Division of the roller ring

517

Right half shell for dividing the roller ring

6

de-bulked first braided layer

7

core

8th

direction of pull

9

undebulked further braided layer

10

de-bulked further braided layer

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2010150022 A1 [0004]
• DE 102005031039 A1 [0005]

Claims (14)

Process for debulking semi-finished textile products made from tapes or hybrid yarns, wherein the tapes or hybrid yarns have a polymeric thermoplastic component in addition to reinforcing fibers and at least the following process steps are carried out: e. Braiding the tapes or the hybrid yarns on a longitudinally elongated core to form a bulky braided semi-finished product, f. Continuous pulling of the braided core in an axial pulling direction with the lying bulky braided semi-finished product by a heating unit and immediately following at least one pressing unit, whereby g. the heating unit heats the bulked braided semi-finished product over the melting range of the thermoplastic polymer, h. the pressing unit presses the heated, bulked, braided semi-finished product onto the core and thus de-bulks it, characterized in that the heated, bulked, braided semi-finished product is pressed around the core and, during the pressing, the de-bulked, braided semi-finished product is cooled below the solidification area of the thermoplastic polymer. Procedure according to Claim 1 , characterized in that steps a. until d. be repeated with reversal of the pulling direction. Procedure according to Claim 1 or 2 , characterized in that the heating in the heating unit takes place using radiant heaters, heating lamps or hot air blowers. Procedure according to one of the Claims 1 until 3 , characterized in that the pressing is carried out by unrolling several rollers, the outer surface of which is adapted to the external shape of the braided semi-finished product arranged on the core. Procedure according to one of the Claims 1 until 3 , characterized in that the pressing is carried out by means of several pressure plates adapted to the external shape of the braided semi-finished product arranged on the core. Device for carrying out the method according to one of the Claims 1 until 5 , comprising a braiding device, preferably a braiding wheel, at least one pulling device for moving an elongated core in the direction of its longitudinal axis, at least one heating unit and at least one pressing unit, characterized in that - the braiding device is set up to produce a tubular braided semi-finished product made of braided tapes or hybrid yarns , wherein the tapes or hybrid yarns have a polymeric thermoplastic component in addition to reinforcing fibers, to be placed on an elongated core, - the pulling device is set up to continuously move the elongated core in the axial direction, - the heating unit is arranged in the pulling direction of the core between the braiding device and the pressing unit and is set up to heat the tubular braided semi-finished product in a radially circumferential manner, - the pressing unit is set up to compress the tubular braided semi-finished product in a circumferential manner in the radial direction to the longitudinal axis of the core and thus debulk it. Device according to Claim 6 , characterized in that the heating unit has a radiant heater, heating lamp or hot air blower. Device according to Claim 6 or 7 , characterized in that the core has a constant cross-section over the entire length covered with tubular braided semi-finished product. Device according to one of the Claims 6 until 8th , characterized in that the pressing unit has a plurality of rollers, the lateral surface of which is adapted to the outer shape of the braided semi-finished product arranged on the core, the rollers being arranged in such a way that the tubular braided semi-finished product is pressed against the core over the entire circumference. Device according to one of the Claims 6 until 8th characterized in that the pressing unit has a plurality of sheets which are arranged around the core and which are spaced on the entry side of the core into the pressing unit from the core and the tubular semi-finished product placed on it and which lie against the tubular semi-finished product in the pulling direction and a Apply contact pressure to this and the shape of which is adapted in the circumferential direction to the outer shape of the tubular semi-finished product placed on the core. Device according to Claim 10 , characterized in that the sheets are designed in such a way that adjacent sheets have a material projection directed in the circumferential direction on a first side and a notch directed in the circumferential direction on the second side, so that in the case of adjacent sheets the material projection of a first sheet extends into the notch of an adjacent one second sheet protrudes into it. Device according to one of the claims Claim 6 until 11 , characterized in that the pressing unit has a sliding coating on the parts that come into contact with the tubular semi-finished product. Device according to one of the claims Claim 6 until 12 , characterized in that the device has a braiding device, to which a heating unit and a pressing unit are arranged symmetrically on each side of the braiding device in a mirror image and the pulling device is set up to reverse the pulling direction and the core with the tubular semi-finished product placed thereon through the braiding device into the heating unit and pressing unit on the other side of the braiding device. Device according to one of the claims Claim 6 until 12 , characterized in that the device has one or more sequences of braiding device, heating unit and pressing unit in the pulling direction, so that several layers of tubular semi-finished product can be continuously braided and de-bulked on top of each other.

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