DE102010013541A1 - Process for producing a continuous fiber reinforced molding using an injection molding tool - Google Patents

Abstract

The invention relates to a method for producing a continuous fiber-reinforced molded part (1) using an injection molding tool (10), the injection molding tool (10) having a first and a second tool part (18, 20) which have a cavity (22) for the final shaping of the molded part (1), the first tool part (18) having a first injection channel (24) and the second tool part (20) having a second injection channel (26) which are provided for injecting flowable thermoplastic material (28) into the cavity (22) The second tool part (20) has an injection device (30) and a metering chamber (32) that can be filled with flowable thermoplastic material (28), the second injection channel (26) opening into the metering chamber (32), and the injection device ( 30) is set up, flowable thermoplastic material (28) located in the metering chamber (32) via the second injection channel (26) in injecting the cavity (22), and wherein the method comprises steps A to I.

Description

Background of the invention

The present invention relates to a method for producing a continuous fiber reinforced molding using an injection molding tool.

The publication US Pat. No. 7,235,149 B2 describes a method for the production of automotive moldings from continuous fiber reinforced thermoplastics. Here, the band-shaped continuous fiber-reinforced preform pieces are placed on a flat surface at different angles to each other. The resulting flat scrim is then preheated and thermoformed. Depending on the wall thickness of the component, the consolidation takes place in a separate or in the same thermoforming tool.

Alternatively, encapsulation methods are also known which carry out the consolidation by encapsulation of the preform, such that the preform is introduced into a cavity of an injection molding unit intended for the final molding of the molding and subsequently left in the mold after the preform has been introduced Fill space of the cavity thermoplastic material is injected. However, with the known extrusion coating method for the consolidation of the preform complex molding geometries can be realized in only low quality manufacturing, as due to the complex geometry in known solutions injection paths are provided for the plastic material, which can be quite long and also in Their length can differ greatly, so that z. B. as a result of cooling processes during injection, the thermoplastic material occurs depending on the injection path with different flow properties or temperatures in the filling chamber or due to a long injection path also too cold in the filling chamber can occur.

Underlying task

The present invention has for its object to provide a method for producing a continuous fiber-reinforced molded part using an injection molding tool with which an endless fiber-reinforced molded part with complex geometry can be produced, which has a substantially higher manufacturing quality compared to a molded part produced by a known method.

Inventive solution

This object is achieved with a method for producing a continuous fiber-reinforced molded part using an injection molding tool having the features of claim 1.

• (A) Bereitstellen von zugeschnittenen, im Wesentlichen flächig ausgebildeten, unidirektional-faserverstärkten Matten mit einer die Fasern zumindest teilweise umgebenden thermo-plastischen Matrix,
• (B) Transfer der Matten zu einem die Grobkontur des Formteils vorgebenden Werkstückträger,
• (C) Ablegen und fortlaufendes Aufbauen der Matten auf dem Werkstückträger zu einem dreidimensionalen Vorformling derart, dass die Faserorientierung der Matten auf die im späteren Einsatz des Formteils angreifenden Kräfte, und die daraus innerhalb des Formteils resultierenden Lastpfade, abgestimmt wird,
• (D) Lagefixierung der Matten zueinander während oder nach Abschluss des Aufbaus des Vorformlings,
• (E) Erwärmung des Vorformlings bis an oder über die Schmelztemperatur der thermoplastischen Matrix des Vorformlings,
• (F) Einbringen des Vorformlings in die Kavität des Spritzgusswerkzeugs,
• (G) Einbringen von fließfähigem thermoplastischen Kunststoffmaterial von außerhalb des Spritzgusswerkzeugs in den Dosierraum, und
• (H) Endgültiges Formen des Formteils durch Einspritzen von fließfähigem thermoplastischen Kunststoffmaterial von außerhalb des Spritzgusswerkzeugs in den nach Einbringen des Vorformlings verbleibenden Füllraum der Kavität und durch zusätzliches Einspritzen des in dem Dosierraum befindlichen thermoplastischen fließfähigen Kunststoffmaterials in den Füllraum, wobei das Kunststoffmaterial von außerhalb des Spritzgusswerkzeugs über den ersten Einspritzkanal eingespritzt wird, und wobei zum Einspritzen des Kunststoffmaterials des Dosierraums die Einspritzvorrichtung aktiviert wird.

The method according to the invention comprises the following steps:

• (A) providing cut-to-size, essentially flat, unidirectionally fiber-reinforced mats with a thermoplastic matrix which at least partially surrounds the fibers,
• (B) transfer of the mats to a workpiece carrier which predetermines the rough contour of the molded part,
• (C) depositing and continuously building the mats on the workpiece carrier into a three-dimensional preform such that the fiber orientation of the mats is matched to the forces acting in the later use of the molding, and the load paths resulting therefrom within the molding,
• (D) fixing the mats to one another during or after completion of the construction of the preform,
• (E) heating the preform to or above the melting temperature of the thermoplastic matrix of the preform,
• (F) introducing the preform into the cavity of the injection molding tool,
• (G) introducing flowable thermoplastic material from outside the injection mold into the dosing space, and
• (H) final molding of the molded article by injecting flowable thermoplastic material from outside the injection mold into the cavity remaining after introduction of the preform and additionally injecting the thermoplastic flowable plastic material within the metering space into the filling space, the plastic material from outside the injection molding tool is injected via the first injection channel, and wherein for injecting the plastic material of the metering chamber, the injection device is activated.

According to the present invention, after performing steps A to E in step G, flowable thermoplastic material is introduced from outside the injection molding tool into the metering space. In step H, the final forming of the molded article from the preform is then accomplished by injecting flowable thermoplastic material from outside the injection mold into the cavity fill remaining after introduction of the preform and by additionally injecting the thermoplastic flowable plastic material into the fill space. In this case, the plastic material is injected from outside the injection molding tool via the first injection channel and for additional injection of the Plastic material of the dosing is activated, the injector, which injects the flowable thermoplastic material located in the dosing chamber via the second injection channel into the cavity. In step I, the molding is removed from the cavity.

The second tool part is provided with an injection system comprising the metering space and the injection device. By using a second tool part with this injection system, which may preferably be in the form of a so-called "shot-pot" device, it is possible to significantly shorten the injection paths required in known solutions. The plastic material located in the metering chamber is injected by means of the injection device via the second injection channel of the second tool part into the filling space of the cavity. On provided in known solutions long injection paths extending from the first to the second tool part and which for supplying the z. B. introduced by an injection unit in the first tool part plastic material to areas of the filling space, which are located in the second tool part, are provided, can thus be dispensed with. By means of the injection system of the second tool part, the length of the longest injection paths or injection channels can be significantly reduced compared to known solutions. In particular, the length differences between the respective injection paths can thus be significantly reduced, so that thermoplastic material injected via different injection paths can enter the filling space with essentially the same flow properties or the same temperature.

By providing the injection system of the second tool part, in particular an external spraying system comprising a plasticizing unit for producing the flowable thermoplastic material and an injection unit for supplying the plastic material can be effectively reduced in terms of its maximum power dimensioning or performance data, so that by means of the inventive method also a reduction in production costs is made possible.

Overall, an endless fiber-reinforced molded part with complex geometry and high production quality can be produced with the method according to the invention.

Preferably, the first tool part is fixed and the second tool part is movable for introducing the preform into the cavity relative to the first tool part. Thus, the preform can be introduced in a practical manner by appropriate movement of the second tool part in the cavity of the injection molding tool or removed therefrom. In particular, in the context of an automated production method, a large number of preforms for producing a corresponding multiplicity of molded parts can thus be introduced into or removed from the cavity in a practical manner.

Preferably, in step H to achieve the highest possible manufacturing quality of the molded part, the injection of the plastic material from outside the injection mold is carried out substantially simultaneously with the injection of the plastic material located in the metering chamber.

Particularly preferably, step G is carried out during cooling of the preform after the heating carried out in step E. In this way, the time to be reserved for cooling the preform can advantageously be used to carry out step G without having to provide process time specifically for this purpose.

In a practical embodiment of the method according to the invention, the injection molding tool has at least one feed line which fluidly connects the first injection channel with the metering space, wherein in step G flowable thermoplastic material from outside the injection mold by injecting the plastic material into the first injection channel and by redirecting the injected plastic material is introduced into the feed line in the metering chamber, and wherein the feed line is closed before, according to step H, the flowable thermoplastic material is injected into the filling space.

By means of the feed line, the thermoplastic material can be introduced in a practical manner via the first injection channel into the metering chamber, so that only a single injection unit to be provided in the vicinity of the injection tool for supplying the plastic material is to be provided.

In a preferred embodiment of the method according to the invention, the second tool part at least two injection devices, at least two metering chambers, each associated with one of the injection devices, and at least two second injection channels, each one of the second injection channels opens into a respective metering and each set up the injection devices is to inject thermoplastic material from the associated dosing into the cavity, and wherein in step G in each of the metering spaces flowable thermoplastic material introduced and in step H, the flowable in each dosing chamber thermoplastic material is injected into the filling space.

By providing the plurality of at least two injection devices and the plurality of at least two metering chambers according to this practical embodiment, which form a corresponding plurality of injection systems, very short injection paths can be realized, so that also moldings with very complex geometry can be produced with high production quality.

In a further practical embodiment, the first tool part has a plurality of first injection channels, and in the vicinity of the injection molding tool at least two injection units are provided which are adapted to inject the flowable thermoplastic material from outside into at least one of the first injection channels. Also, by means of this practical embodiment, very short injection paths can be realized due to the provision of at least two injection units, so that moldings with very complex geometry can be produced with high production quality.

Brief description of the drawings

Hereinafter, embodiments of the invention with reference to the accompanying drawings closer. It shows:

1 schematically a plant for carrying out the method according to the invention, and

2 . 3 each a schematic representation of an embodiment of an injection molding tool according to the inventive method.

The 1 shows schematically a plant for carrying out the method according to the invention for producing a continuous fiber-reinforced molded part 1 , On several conveyor units 3 are thereby tailored, essentially flat, unidirectional fiber-reinforced mats 2 provided with a thermoplastic at least partially surrounding the thermoplastic matrix.

In this embodiment, the mats 2 from the conveyor unit 3 taken from a magazine and provided at a predetermined position. Alternatively, the provision of mats 2 take place via a rolling and / or cutting unit (not shown here). The mats 2 are deposited on a workpiece carrier before being deposited 5 at least partially preheated with the aim of flexibility of the mats 2 to increase. Afterwards a transfer of the mats takes place 2 to a rough contour 4 of the molding 1 specified workpiece carrier 5 , The workpiece carrier 5 itself is on a conveyor line 13 emotional.

On the workpiece carrier 5 become the tailored mats 2 filed and continuously to a three-dimensional preform 6 constructed in such a way that the fiber orientation of the mats 2 on the later use of the molding 1 attacking forces, and those within the molding 1 resulting load paths, is tuned. The transfer, storage and erection of the preform 6 take over several robot stations or robot systems 14 along the conveyor line 13 are arranged. After completion of the construction of the preform 6 become the mats 2 Positionally fixed to each other. In this case, the position fixation by means of a laser welding system 7 , wherein a laser optics (not shown in detail) at a further robot station 17 is arranged. Alternatively, even during the construction of the preform 6 a positional fixation of the mats 2 to each other by textile technology process.

The preform 6 is then in an infrared continuous furnace 8th above the melting temperature of the thermoplastic matrix of the preform 6 heated. Alternatively, the heating may also take place within a convection continuous furnace or in the injection molding tool 10 yourself. By means of another robot station 9 the introduction of the three-dimensional preform takes place 6 into the cavity of an injection molding tool 10 for final molding of the molding, wherein the flowable thermoplastic material to be injected into the remaining filling space of the cavity is from an injection unit 15 is supplied. The finished molding 1 is also using the robot station 9 from the injection mold 10 taken and a storage unit 16 fed.

The 2 and 3 each show a schematic representation of an embodiment of an injection molding tool 10 according to the method of the invention.

The injection mold 10 has a first stationary tool part 18 and a second tool part 20 on which a cavity 22 for final molding of the molding 1 into which a very schematically illustrated preform 6 is introduced.

The first tool part 18 has a first injection channel 24 and the second tool part 20 has a second injection channel 26 on, for injecting flowable thermoplastic material 28 into the cavity 22 are provided. From the first and the second injection channel 24 . 26 extend at right angles each two branch channels, each in the cavity 22 lead.

The second tool part 20 is for introducing the preform 6 into the cavity 22 relative to the first tool part 18 movable (not illustrated here) and has an injection device 30 in the form of a longitudinally movable plunger and a flowable thermoplastic material 28 Fillable dosing chamber 32 on, wherein the second injection channel 26 in the dosing room 32 empties.

The injection mold 10 also has a feed line 34 on which the first injection channel 24 fluid-conducting with the dosing chamber 32 combines. The feed line 34 has two line valves 36 on, which in the open state an inflow of flowable thermoplastic material 28 in the dosing room 32 make possible which of one in the vicinity of the injection molding tool 10 provided injection unit 38 over the first injection channel 24 is supplied. To divert the over the first injection channel 24 supplied plastic material 28 into the feed line 34 to allow, the first injection channel has 24 a channel valve 40 on, which in the closed state, the diversion into the feed line 34 granted, provided the two line valves 36 are open.

Also the second injection channel 26 has a channel valve 40 on, which in the closed state, a leakage of the thermoplastic material 28 during the introduction of the same in the dosing 32 avoids and which for injecting the in the dosing 32 introduced plastic material 28 in the after introduction of the preform 6 remaining filling space 42 is opened.

The 2 illustrates a situation according to step G of the method according to the invention, in which the flowable thermoplastic material 28 in the dosing room 32 is introduced, for which purpose the two line valves 36 previously opened and the two channel valves 40 be closed beforehand.

The 3 illustrates a situation according to step H of the method according to the invention, in which the final molding of the molding 1 flowable thermoplastic material 28 from the injection unit 38 in the filling room 42 the cavity 22 and additionally in the dosing space 32 located thermoplastic flowable plastic material 28 by activating the injector 30 in the filling room 42 is injected, the feed line 34 by closing the line valves 36 is closed before the flowable thermoplastic material 28 in the filling room 42 is injected.

LIST OF REFERENCE NUMBERS

1

molding

2

mat

3

delivery unit

4

rough contour

5

Workpiece carrier

6

preform

7

Laser welding system

8th

Infrared continuous furnace

9

robot station

10

injection mold

13

conveyor line

14

robot system

15

injection unit

16

storage unit

18

first tool part

20

second tool part

22

cavity

24

first injection channel

26

second injection channel

28

thermoplastic plastic material

30

Injector

32

metering

34

feed line

36

line valve

38

injection unit

40

channel valve

42

filling space

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

• US 7235149 B2 [0002]

Claims (7)

Process for producing a continuous fiber-reinforced molded part ( 1 ) using an injection molding tool ( 10 ), wherein the injection molding tool ( 10 ) at least a first and at least one second tool part ( 18 . 20 ) having a cavity ( 22 ) for final molding of the molding ( 1 ), wherein the first tool part ( 18 ) at least one first injection channel ( 24 ) and the second tool part ( 20 ) at least one second injection channel ( 26 ) which is suitable for injecting flowable thermoplastic material ( 28 ) into the cavity ( 22 ) are provided, wherein the second tool part ( 20 ) at least one injection device ( 30 ) and at least one with flowable thermoplastic material ( 28 ) fillable dosing space ( 32 ), wherein the second injection channel ( 26 ) into the dosing space ( 32 ), and wherein the injection device ( 30 ), in the dosing space ( 32 ) flowable thermoplastic material ( 28 ) via the second injection channel ( 26 ) into the cavity ( 22 ), the method comprising the following steps: (A) providing cut-to-size, substantially flat, unidirectionally fiber-reinforced mats ( 2 ) with a thermoplastic matrix at least partially surrounding the fibers, (B) transfer of the mats ( 2 ) to a rough contour ( 4 ) of the molded part ( 1 ) specified workpiece carrier ( 5 ), (C) depositing and continuously constructing the mats ( 2 ) on the workpiece carrier ( 5 ) to a three-dimensional preform ( 6 ) such that the fiber orientation of the mats ( 2 ) on the later use of the molding ( 1 ) attacking forces, and the resulting within the molding ( 1 ), (D) fixing the position of the mats ( 2 ) to one another during or after completion of the preform construction ( 6 ), (E) heating the preform ( 6 ) to or above the melting temperature of the thermoplastic matrix of the preform ( 6 ), (F) introducing the preform ( 6 ) into the cavity ( 22 ) of the injection molding tool ( 10 ), (G) introducing flowable thermoplastic material ( 28 ) from outside the injection molding tool ( 10 ) into the dosing space ( 32 ), (H) Final molding of the molding ( 1 ) by injection of flowable thermoplastic material ( 28 ) from outside the injection molding tool ( 10 ) in the after introduction of the preform ( 6 ) remaining filling space ( 42 ) of the cavity ( 22 ) and by additional injection of the in the dosing ( 32 ) thermoplastic flowable plastic material ( 28 ) in the filling space ( 42 ), wherein the plastic material ( 28 ) from outside the injection molding tool ( 10 ) via the first injection channel ( 24 ), and wherein for injecting the plastic material ( 28 ) of the dosing space ( 32 ) the injection device ( 30 ), and (I) removing the molded part ( 1 ) from the cavity ( 22 ). Method according to claim 1, characterized in that the first tool part ( 18 ) is stationary, and that the second tool part ( 20 ) for introducing the preform ( 6 ) into the cavity ( 22 ) relative to the first tool part ( 18 ) is movable. A method according to claim 1 or 2, characterized in that in step (H) the injection of the plastic material ( 28 ) from outside the injection molding tool ( 10 ) substantially simultaneously with the injection of the in the dosing ( 32 ) plastic material ( 28 ) is made. Method according to one of the preceding claims, characterized in that step (G) during cooling of the preform ( 6 ) after the heating carried out in step (E). Method according to one of the preceding claims, characterized in that the injection molding tool ( 10 ) at least one feed line ( 34 ), which the first injection channel ( 24 ) fluid-conducting with the dosing space ( 32 ), wherein in step (G) flowable thermoplastic material ( 28 ) from outside the injection molding tool ( 10 ) by injecting the plastic material ( 28 ) in the first injection channel ( 24 ) and by redirecting the injected plastic material ( 28 ) into the feed line ( 34 ) into the dosing space ( 32 ) is introduced, and wherein the feed line ( 34 ) is closed before according to step (H) the flowable thermoplastic material in the filling space ( 42 ) is injected. Method according to one of the preceding claims, characterized in that the second tool part ( 20 ) at least two injectors ( 30 ), at least two metering chambers ( 32 ), each one of the injectors ( 30 ), and at least two second injection channels ( 26 ), wherein in each case one of the second injection channels ( 26 ) in each one dosing ( 2 ) and each of the injectors ( 30 ), thermoplastic material ( 28 ) from the associated dosing chamber ( 32 ) into the cavity ( 22 ) and in step (G) into each of the metering chambers ( 32 ) flowable thermoplastic material ( 28 ) and in step (H) the in each dosing ( 32 ) flowable thermoplastic synthetic material ( 28 ) in the filling space ( 42 ) is injected. Method according to one of the preceding claims, characterized in that the first tool part ( 18 ) a plurality of first injection channels ( 24 ), and that in the vicinity of the injection molding tool ( 10 ) at least two injection units ( 38 ), which are arranged, the flowable thermoplastic material ( 28 ) from outside into at least one of the first injection channels ( 24 ).

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