DE102018201347A1 - Method and apparatus for producing thermoplastic fiber-reinforced semi-finished products with a constant cross-sectional area - Google Patents

Abstract

Apparatus and method for producing thermoplastic fiber-reinforced semi-finished products having a constant cross-sectional area (1), in which a plurality of endless fibers (2) are fed under tension by a forming tool (14) and are arranged and held in a predefined position when the forming tool (14) is closed, in which they assume a sealing function for a mold cavity (15) arranged in the forming tool (14). The filaments (2) are held at a predefined position during injection of the monomers into the mold cavity (15) and subsequent polymerization.

Description

The invention relates to a process for the production of thermoplastic fiber-reinforced semi-finished products with a constant cross-sectional area, in which continuous fibers are fed under tension by a forming tool and are arranged and held in a predefined position when closing the forming tool, and an apparatus for performing the method.

Various processes are known for the production of thermosetting fiber-reinforced plastic profiles. The apparatuses used for these methods are of similar construction and usually comprise a fiber shelf, a fiber guide, an impregnating device, a shaping or curing tool, a drawing unit and a cutting unit. The known methods differ mainly in the type of matrix impregnation. The impregnation of the fiber with the matrix can be done in two different ways. Either the fibers are spread prior to entry into the tool and pulled through a resin bath or the matrix is injected into the tool. In the second method, the reinforcing fibers are usually first passed through an impregnating tool. This tool has the shape of the profile to be produced and expands inside. In this cavity, the matrix is injected transversely to the fiber direction. In another tempered tool, the final shaping of the profile and the polymerization or curing take place. The finished semi-finished product is usually continuously conveyed (pultrusion) by means of a withdrawal unit located at the end of the installation.

These known methods are only of limited suitability for the production of thermoplastic fiber-reinforced semi-finished products with a constant cross-section, since a stable production process requires relatively narrow boundary conditions for thermoplastics. For example, due to a lower viscosity of the thermoplastics, in contrast to the individual components of thermosets, a suitable wetting of the fibers during injection is made more difficult. This effect can be counteracted by injecting the monomers of the thermoplastics, but the necessary polymerization is more complicated. Accordingly, sufficient process reliability in the production of thermoplastic fiber-reinforced semi-finished products can not be guaranteed with the known methods.

From the German patent DE 10 2010 019 625 B4 For example, a process is known in which the polymerization process and the shaping process are integrated into one step in the case of flat, non-continuously produced components. Preformed, dry fiber scrims are time-consuming placed in a first mold cavity and infiltrated with a reactive matrix. During the infiltration process, the fiber fabric must remain at the predetermined position. The use of monomers with sufficiently low viscosity allows a good and gentle wetting of the dry fibers, wherein a use of thermoplastics as matrix material is possible. In this way, for example, thermoplastic plastic parts can be produced with very thin wall thicknesses.

On this basis, it is an object of the present invention to propose a process with sufficient process reliability for producing thermoplastic fiber-reinforced semi-finished products with a constant cross-sectional area. This is achieved according to the invention by the teaching of the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims.

To achieve the object, a method for producing thermoplastic fiber-reinforced semi-finished products with a constant cross-sectional area is proposed, in which a plurality of continuous fibers are fed under tension by a shaping tool. When closing the forming tool, the continuous fibers are arranged and held in a predefined position, in which they assume a sealing function for a mold cavity arranged in the forming tool. The filaments are held at the predefined position during injection of the monomers into the mold cavity and subsequent polymerization. After shaping, the fabricated portion of the semifinished product is pulled out of the forming tool, whereby the adjoining thereto portion of the continuous fibers is guided into the mold cavity of the forming tool.

The continuous fibers used in the process of making thermoplastic fiber-reinforced semi-finished products of constant cross-sectional area are passed under tension by a forming tool and protrude beyond the latter when the forming tool is closed. In the direction of the trigger, the forming tool can be designed, for example, in the case of semi-finished products whose cross-section has no cavities so that it receives the cross-section of the semifinished product produced in the preceding process step in a parting plane. The seal can then be done around its circumference.

Especially in one direction to the fiber shelf or on both sides of the mold cavity take over the continuous fibers a Sealing function for the mold cavity arranged in the forming tool. From the fiber shelf, the continuous fibers, especially in the raw state (a pretreatment should not be excluded in the context of this invention) are guided into the mold cavity of the forming tool. In a manner suitable for sealing and in accordance with the intended positioning and fiber distribution of the continuous fibers in the later semifinished product, the continuous fibers are arranged individually or in the form of, in particular, a plurality of strands at predefined positions in the separating region of the forming tool and held there. In this position, the continuous fibers remain during the entire process section from the introduction of the monomers, the polymerization to the completed shaping. The continuous fibers thus remain from the closing of the mold cavity up to its opening and until the completed shaping of the manufactured section of the semifinished product in this position.

In the proposed method, the unconnected continuous filaments are drawn into the mold cavity required for the proposed method and positioned there. Subsequently, the monomers, which may, for example, be ε-caprolactam (a precursor of polyamide), are injected and polymerized. Characterized in that the continuous fibers are arranged in particular under tension standing at the respectively intended positions in the mold cavity, injection of the monomers into the mold cavity without increased risk of slipping and thus an undesirable arrangement of the continuous fibers in the semifinished product. In this way, thermoplastic fiber reinforced semi-finished products with constant cross section can be produced in reproducible process steps in a controllable, semi-continuous process. At the same time, the product quality and its verifiability can be increased. In addition to a good wetting of the individual fibers, the proposed method also allows a high fiber volume content.

In one embodiment of the method, the endless fibers are clamped in clamping position of the forming tool in the closed position of the forming tool. Clamping positions provided on the forming tool accommodate, for example, individual endless fibers or a plurality of endless fibers, which are combined to form at least one strand. By receiving and clamping of continuous fibers at intended clamping positions, a sealing of the mold cavity in the forming tool.

In one embodiment of the method, the continuous fibers are under tension in the closed position of the forming tool. This allows a particularly good positioning of the continuous fibers in the mold cavity, in particular during the injection of the monomers into the mold cavity.

In one embodiment of the method, the monomers are injected substantially transversely to the direction of the continuous fibers into the mold cavity of the forming tool. An injection of the monomers substantially transversely to the direction of the continuous fibers allows a good penetration of the monomers between the individual fibers, in particular in the case of fiber packets, and thus a particularly good wetting of the individual fibers.

In one embodiment of the method, the continuous fibers are dried prior to entering the forming tool. The drying of the continuous fibers prior to entry into the forming tool serves to ensure particularly dry fibers, which is advantageous for a stable and reproducible process. For example, one needs the drying of the continuous fibers, if they could have absorbed moisture in a previous storage.

In one embodiment of the method, the semifinished product is cut to length according to the sections produced in one method step. Such an embodiment may be particularly advantageous when the mold cavity is formed according to a desired semifinished product length. However, such an embodiment may also be expedient if, in the method, in particular by holding the continuous fibers at a parting plane of the forming tool, a poor or reject point is formed, which is to be removed from the semifinished product.

The process described above produces a thermoplastic fiber-reinforced semifinished product of constant cross-sectional area. In this case, the region of the semifinished product which has taken over the sealing function for the mold cavity arranged in the forming tool can have a predefined geometry, which differs in particular also from the further cross section of the semifinished product.

The sections of a thermoplastic fiber-reinforced semifinished product having a constant cross-sectional area and produced by a method described above have a predetermined length, which corresponds in particular to the length of the mold cavity of the forming tool.

• - ein Faserregal, in welchem mehrere Endlosfasern speicherbar sind,
• - eine Faserführung, mit welcher Endlosfasern führbar sind,
• - ein Formgebungswerkzeug mit einem darin angeordneten Formhohlraum,
• - eine mit dem Formgebungswerkzeug verbundene Spritzgießeinheit, mit welcher die Monomere in den Formhohlraum einspritzbar sind,
• - eine Abzugseinheit, mit welcher eine Zugbelastung auf die Endlosfasern aufbringbar ist und
• - eine Ablängeinheit, mit welcher das hergestellte Halbzeug ablängbar ist.

In a further aspect for achieving the object, an apparatus for producing thermoplastic fiber-reinforced semi-finished products is provided constant cross-sectional area proposed, which comprises:

• a fiber shelf in which several endless fibers can be stored,
• a fiber guide, with which endless fibers can be guided,
• a forming tool having a mold cavity disposed therein,
• an injection molding unit connected to the forming tool, with which the monomers can be injected into the mold cavity,
• - A trigger unit with which a tensile load on the continuous fibers can be applied and
• - A cutting unit, with which the semifinished product produced is ablängbar.

In the proposed device, the continuous fibers take over a sealing function of the mold cavity in the closed position of the forming tool. In this case, the injection molding unit is arranged on the forming tool such that the monomers can be injected between the endless fibers arranged in the mold cavity, wherein the continuous fibers are held in a predetermined position in a subsequent polymerization and shaping in the forming tool.

The device is in particular designed for carrying out the previously described method for producing thermoplastic fiber-reinforced semi-finished products with a constant cross-sectional area. Thus, the previously mentioned embodiments and advantages also apply correspondingly to the device for producing thermoplastic fiber-reinforced semi-finished products with a constant cross-sectional area.

The injection molding unit is arranged on the forming tool such that the monomers can be injected between the endless fibers arranged in the mold cavity. The arrangement and number of injection nozzles arranged for this purpose on the mold cavity is dependent on the geometry of the semifinished product and the arrangement of the continuous fibers in the mold cavity and is correspondingly designed so that the best possible wetting of the endless fibers arranged in the mold cavity can take place.

The fiber guide with which the continuous fibers can be guided serves to guide at least a portion of continuous fibers between the fiber shelf and the mold cavity. In particular, the fiber guide can also be used for positioning the endless fibers in relation to the mold cavity or the clamping positions arranged thereon before the closing of the shaping tool.

The device further comprises a trigger unit with which a tensile load on the continuous fibers can be applied. If the tensile load is maintained during the closing of the forming tool, the continuous fibers are under tension in the closed position of the forming tool in the mold cavity. This allows a particularly good retention of the position of the continuous fibers, in particular during the injection of the monomers into the mold cavity.

In one embodiment of the device, the forming tool has at least one clamping position at which the continuous fibers in the closed position of the forming tool between the forming elements of the forming tool are clamped, and which holds the continuous fibers in a designated position. Such a clamping position absorbs, for example, individual endless fibers or a plurality of endless fibers, which are combined to form at least one strand. By receiving and clamping of continuous fibers at a clamping position, the continuous fibers are arranged on the one hand at a predetermined position. Furthermore, by clamping the continuous fibers between the elements of the forming tool, sealing of the mold cavity in the forming tool takes place.

In one embodiment of the device, the monomers are injectable into the mold cavity of the forming tool substantially transverse to the direction of the continuous fibers. As already stated, injection of the monomers substantially transversely to the direction of the continuous fibers into the mold cavity enables particularly good wetting of the individual fibers.

• 1 eine schematische Darstellung einer beispielhaften erfindungsgemäßen Ausführungsform der Vorrichtung zum Herstellen von thermoplastischen faserverstärkten Halbzeugen mit konstanter Querschnittsfläche;
• 2 eine schematische Darstellung einer Draufsicht auf den geöffneten Formhohlraum; und
• 3 eine schematische Darstellung einer Ansicht von vorne auf den sich schließenden Formhohlraum.

Other features, advantages and applications of the invention will become apparent from the following description taken in conjunction with the figures. It shows

• 1 a schematic representation of an exemplary embodiment according to the invention of the device for producing thermoplastic fiber-reinforced semi-finished products with a constant cross-sectional area;
• 2 a schematic representation of a plan view of the open mold cavity; and
• 3 a schematic representation of a view from the front of the closing mold cavity.

1 shows a schematic representation of an exemplary embodiment of the device according to the invention 10 for producing a thermoplastic fiber-reinforced semifinished product with a constant cross-sectional area 1 , In 1 rejects the device 10 from right to left the following facilities: A fiber shelf 11 in which several continuous fibers 2 on spools 3 are stored; an optionally on the device can be arranged drying device 12 for drying the continuous fibers 2 , As the drying device 12 only optionally on the device 10 is installed, this is in 1 shown in dashed lines. At the forming tool 14 is a fiber guide 13 arranged, which the continuous fibers 2 in the right position on the forming tool 14 leads. In the forming tool 14 is a mold cavity 15 arranged, which according to the shape of the semifinished product to be produced 1 is trained. With the forming tool 14 is an injection molding unit 16 connected, with which the monomers in the mold cavity 15 are injectable. In the direction of manufacture is after the forming tool 14 a deduction unit 17 arranged a tensile load on the continuous fibers 2 applies. At the end follows a cutting unit 18 for cutting the produced semifinished product 1 ,

In the production of the semifinished product 1 become the continuous fibers 2 or the semi-finished product 1 from the deduction unit 17 in 1 to the left of the fiber shelf 11 through the device 10 and also by the forming tool 14 drawn. In 1 became the pre-fabricated section of the semifinished product 1 already out of the mold cavity 15 drawn. In the mold cavity 15 Now only the section of the semi-finished product made from the last one is located 1 protruding endless fibers 2 , Will the mold cavity 15 of the forming tool 14 now closed, so are the continuous fibers 2 at clamping positions 19 on the forming tool 14 clamped and take over a sealing function of the mold cavity 15 , After closing the mold cavity 15 the injection molding unit sprays 16 the monomers between those in the mold cavity 15 arranged continuous fibers 2 on. By clamping the continuous fibers 2 at the clamping positions 19 on the forming tool 14 become the continuous fibers 2 in the subsequent polymerization and shaping in the forming tool 14 held in the intended position.

2 shows a schematic representation of a plan view of the open mold cavity 15 through which endless fibers 2 extend in the form of two fiber strands. The endless fibers 2 are below that of the deduction unit 17 applied voltage. At the edges of the mold cavity 15 are the continuous fibers 2 at clamping positions 19 positioned in which 3 in a view from the front of the forming tool 14 are shown.

3 shows a schematic representation of a view from the front of the closing mold cavity 15 , The top 14a and lower 14b Form part of the forming tool 14 have two clamping positions in this area 19 on. A lower clamping position 19a has a recess and an upper clamping position 19b has a projection, which in a closed position of the forming tool 14 leaves a space in the recess, which the cross section of the at the clamping position 19 provided continuous fibers 2 equivalent. Thus take over the at the clamping positions 19 arranged continuous fibers 2 in the closed position of the forming tool 14 a sealing function of the mold cavity 15 , In the detail shown on the right 3 is well recognizable that the continuous fibers 2 in a tight package at the clamping position 19 are clamped. During the after closing of the mold cavity 15 injecting the monomers into the mold cavity 15 and the subsequent polymerization become the continuous fibers 2 at the by the clamping positions 19 held predefined positions.

After the molding, which, for example, under an additional pressurization of the mold cavity 15 can be made, the manufactured section of the semifinished product 1 from the deduction unit 17 from the forming tool 14 drawn. As a result, from the previously prepared section of the semifinished product 1 protruding endless fibers 2 into the mold cavity 15 of the forming tool 14 guided.

LIST OF REFERENCE NUMBERS

1

semis

2

continuous fiber

3

Kitchen sink

10

Apparatus for producing semi-finished products

11

fiber shelf

12

drying device

13

fiber guide

14

shaping tool

14a

upper molding of the forming tool

14b

lower molding of the forming tool

15

mold cavity

16

injection molding

17

off unit

18

cutting unit

19

clamping position

19a

lower clamping position

19b

upper clamping position

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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

• DE 102010019625 B4 [0004]

Claims (10)

A method of making thermoplastic fiber-reinforced continuous cross-sectional area (1), wherein a plurality of continuous fibers (2) are fed under tension by a forming tool (14) and are positioned and held in a predetermined position upon closing of the forming tool (14) they perform a sealing function for a mold cavity (15) arranged in the forming tool (14), characterized in that the endless fibers (2) are held in the predefined position during injection of monomers into the mold cavity (15) and a subsequent polymerization and after Shaping the prepared portion of the semifinished product (1) is pulled out of the forming tool (14), whereby the subsequent thereto portion of the continuous fibers (2) in the mold cavity (15) of the forming tool (14) is guided. Method according to Claim 1 , characterized in that the continuous fibers (2) are clamped in clamping position (19) of the forming tool (14) in the closed position of the forming tool (4). Method according to one of the preceding claims, characterized in that the endless fibers (2) in the closed position of the forming tool (14) are under tension. Method according to one of the preceding claims, characterized in that the monomers are injected substantially transversely to the direction of the continuous fibers (2) in the mold cavity (15) of the forming tool (14). Method according to one of the preceding claims, characterized in that the continuous fibers (2) are dried before entering the forming tool (14). Method according to one of the preceding claims, characterized in that the semifinished product (1) is cut to length according to the sections produced in a method step. Thermoplastic fiber-reinforced semi-finished product with constant cross-sectional area, produced by a method according to one of the preceding claims, characterized in that the sections produced in one method step have a predetermined length. Apparatus for producing thermoplastic fiber-reinforced semi-finished products with a constant cross-sectional area (1), comprising - a fiber shelf (11) in which a plurality of endless fibers (2) can be stored, - a fiber guide (13) with which endless fibers (2) can be guided, - a A shaping tool (14) having a mold cavity (15) arranged therein, - an injection molding unit (16) connected to the forming tool (14), with which monomers can be injected into the mold cavity (15), - a drawing unit (17) with which a tensile load is applied on the endless fibers (2) can be applied and - a cutting unit (18) with which the semi-finished product (1) is cut to length, characterized in that the continuous fibers (2) in the closed position of the forming tool (14) has a sealing function of the mold cavity (15 ) and the injection molding unit (16) is arranged on the forming tool (14) so that the monomers between the in the mold cavity (15) arranged Endlosfase (2) are injectable, wherein the continuous fibers (2) are held at a predetermined position in a subsequent polymerization and shaping in the forming tool (14). Device after Claim 8 characterized in that the forming tool (14) has at least one clamping position (19) at which the continuous fibers (2) are clampable between the forming elements (14a, 14b) of the forming tool (14) in the closing position of the forming tool (14) to hold the continuous fibers (2) in a predefined position. Device according to one of Claims 8 or 9 , characterized in that the monomers can be injected substantially transversely to the direction of the endless fibers (2) in the mold cavity (15) of the forming tool (14).

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