WO2015197148A1

WO2015197148A1 - Duroplastic composite fiber plastic structure comprising a thermoplastic and fiber-reinforced load introducing element

Info

Publication number: WO2015197148A1
Application number: PCT/EP2015/000889
Authority: WO
Inventors: Julius Rausch; David Roquette; Tobias KLEFFEL; Daniel Kugele; Christoph HOLLÄNDER
Original assignee: Audi Ag
Priority date: 2014-06-25
Filing date: 2015-04-30
Publication date: 2015-12-30
Also published as: DE102014009446B4; DE102014009446A1; EP3160721A1

Abstract

The invention relates to a composite fiber plastic structure (1) comprising at least one fiber structure (2) that is embedded in a duroplastic matrix (3), and at least one load introducing element (10). According to the invention, the load introducing element (10) includes a thermoplastic molded part (12) produced by partially impregnating a fibrous insert (11) using a thermoplastic injection molding process, and the fiber structure (2) as well as the non-impregnated portion (11.1) of the fibrous insert (11), which is placed on the fiber structure (2) comprising the thermoplastic molded part (12), are impregnated with the duroplastic matrix (3).

Description

Thermosetting FRP structure with a thermoplastic and fiber-reinforced load introduction element

The invention relates to a FRP structure with a load introduction element according to the preamble of patent claim 1.

The use of fiber composite plastic (FRP) structures in body construction is known and, combined with high strength values, leads to considerable weight savings.

In order to incorporate additional structures onto such FRP structures, such load introduction elements, for example for low loads, are glued in a separate process step. To optimize such an adhesive bond, various surface treatments, such as surface roughening or UV treatments, are carried out. Disadvantages of this are the additional process steps, wherein in particular the surface treatments are expensive and expensive.

Another possibility for connecting additional structures is described in DE 101 01 271 A1 by means of inserts embedded in FRP structures. Such an insert consists of a fiber-reinforced thermoplastic material, which is embedded in a molded part made of a thermosetting plastic produced in the RTM process. In this insert a threaded bushing is embedded in order to screw in a threaded bolt for fixing the FRP structure can. The disadvantage here, however, is that at the transition from the thermoplastic see material of the insert also duroplastic material of the molding adhesion problems can occur.

Furthermore, DE 10 2012 207 1 18 A1 likewise discloses a FRP structure with an insert part in order to connect further force-transmitting components to the FRP structure via such an insert part. This FRP structure consists of a carrier of either a fiber reinforced thermoset, a non-reinforced thermoplastic or a glass fiber reinforced thermoplastic material. In this carrier an insert of a fiber-reinforced plastic is embedded. To produce such an insert, a core is first produced by means of a pultrusion process (also called a pultrusion process) in which an impregnated, textile semi-finished product is pulled through a matrix and the fibers are exclusively oriented in the pullout direction. Following this process, the pultrided core is wrapped by means of pull-wrap or pull-braiding with a fiber layer or fiber fabric made of long fiber strands, so that a different fiber direction results compared to the fibers of the core. However, this represents a very expensive process for producing such an FRP structure.

Finally, DE 201 11 1 1 743 A1 describes an FRP structure with at least one textile insert in combination with a thermoplastic matrix and stiffening ribs injection-molded from thermoplastic material. These stiffening ribs contain a relatively high volume fraction of at least 30% short fibers from a reinforcement part material.

The object of the invention is to provide a FRP structure of the type mentioned, in which the load introduction element is integrated with an improved form fit, ie with better mechanical properties and higher transferable forces in the FRP structure with a thermoset matrix. This object is achieved by a FRP structure having the features of patent claim 1.

Such an FRP structure, which comprises at least one fiber structure embedded in a thermosetting matrix and at least one load introduction element, is characterized according to the invention in that

- The load introduction element has a thermoplastic molded body, which is produced by partial impregnation of a fiber insert by means of thermoplastic injection molding, and

- The non-impregnated portion of the arranged on the fiber structure with the thermoplastic molded body fiber insert is impregnated together with the fiber structure with the thermosetting matrix.

In this FRP structure according to the invention a form-fitting is realized by a thermoplastic semi-finished fiber insert as thermoplastic matrix and the non-impregnated portion of this semi-finished fiber impregnated together with the fiber structure with the thermoset matrix, so that in this way also creates a positive connection. Thus, a high adhesion and a positive connection with high connection quality are achieved between the fiber feeder and the respectively involved matrix systems. In particular with the fibers of the dry region of the fiber insert, a significantly improved positive connection is achieved, so that a tension transfer between the thermoplastic region, that is to say the first region and the second region, is made possible.

Due to the positive connection between the reinforcing fibers or the semifinished fiber product and the respective matrix systems exist between the thermoset structure and its thermoplastic load introduction element no adhesion problems, so that significantly higher forces can be transmitted. Since the thermoplastic molding is made of plastic, a further structure, for example, can be connected directly thereto by means of a screw connection.

The production of such a load introduction element by means of a thermoplastic processing process can be carried out economically and then easily integrated into the FRP structure by means of a thermosetting processing process. For this purpose, the load introduction elements are, for example, inserted directly into the injection or pressing tools for producing a thermoset component. This eliminates additional processes for mounting conventional load introduction elements.

According to an advantageous embodiment of the invention, the thermoplastic molded body forms a composite with the fiber insert over at least one impregnated region of the fiber insert or semifinished fiber product. Thus, an optimal positive connection between the semi-finished semifinished product and the thermoplastic molding is achieved. Preferably, the thermoplastic molded body forms a composite with the fiber insert over a plurality of impregnated regions of the fiber insert or of the semi-finished fiber product. This leads to an improved positive connection between the thermoplastic molding and the thermoset matrix.

According to a further embodiment of the invention, to form a mechanical interface of the thermoplastic molded body on a connecting element, which is prepared by molding in the production of the thermoplastic molding. Such a connecting element may, for example, be designed as a sleeve with or without thread or as a threaded bolt, etc., and be made of metal or plastic.

According to the invention, the fiber feeder or the semi-finished fiber product is formed from textile fibers and / or metal fibers, wherein the fiber structure is a May be a fabric, a mat, a nonwoven, a braid, a knitted fabric and / or a knitted fabric.

According to the training is suitable as a mold for the thermoplastic molded body a cuboid, frusto-conical or a truncated pyramidal shape, which can be realized especially in the conical shapes, an undercut in the field of thermoset matrix of the FRP structure. In addition, the thermoplastic molded body can also have reinforcing ribs.

The invention will now be described in detail by means of an embodiment with reference to the accompanying figures. Show it:

Figure 1 is a schematic representation of a FRP structure with a

Load introduction element according to the invention in a sectional view,

FIG. 2 shows a schematic representation of a further embodiment of a load introduction element in a sectional view,

FIG. 3 shows a schematic illustration of the load introduction element according to FIG. 2 in a plan view,

Figure 4 is a schematic representation of another embodiment of the load introduction element of Figure 2, and

Figure 5 is a schematic representation of another embodiment of a load introduction element in a bottom view. FIG. 1 shows an FRP structure 1 with a load introduction element 10, wherein this FRP structure 1 shown represents part of a thermoset component. ^~

This load introduction element 10 comprises a fiber insert 1 1 as semifinished fiber product, which is partially impregnated with a thermoplastic matrix to produce a thermoplastic molding body 12, so that an impregnated region 1 1.2 and an unimpregnated, ie dry, region 1.1 are formed.

For this purpose, in a first process step in a mold cavity of an injection molding or injection compression tool for thermoplastics, the dry fiber feeder 1 1 is inserted and impregnated with a tool stroke in the range 1 1 .2 of Faserein casual 1 1 with the thermoplastic matrix and in this case the thermoplastic molding 12 produced. In order to keep the area 1 1 .1 dry, appropriate seals are introduced into the tool; alternatively, the area 1 1 .1 can be sealed by local overpressing. The component geometry of the thermoset component to be produced determines the shape of the thermoplastic molding 12. According to FIGS. 1 to 4, this thermoplastic molding 12 has a frustoconical shape. It is also possible to realize other shapes, such as, for example, a truncated pyramidal or cylindrical shape, or to cast ribs onto the thermoplastic molded body. Here, all forms are possible, which can be realized by injection molding. Outside the impregnated region 1 1.2, the fiber insert 11 is not impregnated with the thermoplastic matrix; this non-impregnated region 11 1 of the fiber insert 11 remains dry.

As materials for the fiber insert 1 1 semi-finished textile or filigree metal structures are used. As semi-finished textile products, scrims, fabrics, mats, nonwovens, braids, knitted fabrics and / or knitted fabrics made of glass, aramid, carbon, etc. can be used. Grids, wire mesh, etc. are suitable for filigree metal structures. This thermoplastic molded body 12 forms a mechanical interface to fasten other components can. For this purpose, this thermoplastic molded body 12 has a threaded bushing as a connecting element 13, via which the other components can be connected. This threaded bush can be produced simultaneously with the production of the thermoplastic molded body 12, or subsequently hot or cold pressed into the thermoplastic molded body 12. Alternatively, threaded bolts can be integrated into the thermoplastic molding.

The load introduction element 10 is now used for producing the FRP structure 1 of a thermoset component according to FIG. For this purpose, in a second process step, the thermoplastic molded body 12 is inserted with the partially impregnated textile semi-finished fiber 1 1 together with a fiber structure 2 in a tool for processing thermoset molding compounds, so that the fiber insert 1 1 of the load application element 10 rests on this fiber structure 2. With such a tool, the non-impregnated region 1 1.1 of the fiber insert 1 is impregnated together with the vehicle structure 2 with a duroplastic matrix 3.

FIG. 1 shows the FRP structure 1 after the thermosetting processing process, in which the thermoplastic molded body 12 is connected with its base 12.1 over the impregnated region 11.2 all-over to the fibers of the fiber insert 11.

In this FRP structure 1 via the fiber feeder 1 1 a positive connection on the impregnated region 1 1 .2 with the thermoplastic matrix of the thermoplastic molding 12 and the non-impregnated region 1 1 .12 of the fiber core 1 1 is together with the fiber structure. 2 impregnated in thermosetting processing process and thus also achieved a positive connection between the non-impregnated region 11 .1 and the thermosetting matrix system. Thus, between the fiber feeder 1 1 and the respective matrix systems involved, that is to say the thermoplastic matrix system of the thermoplastic molding 12 and the thermosetting matrix system, ensure a high degree of adhesion and positive engagement with a high quality of connection. In particular, with the fibers of the non-impregnated region 1 1.1 of the fiber insert 1 1 a significantly improved form-fit is achieved, so that a voltage transfer between the thermoplastic, ie the impregnated region 11.2 and the thermoset region, ie the non-impregnated region 1 1 .1 is made possible , Finally, an undercut for the duroplastic matrix 3 is formed at the lower edge of the thermoplastic molded body 12, which also improves the positive connection between the thermoplastic molded body 12 and the thermoset matrix 3.

This thermoplastic molded body 12 forms a mechanical interface to fasten other components can. For this purpose, the further component, for example, by means of a screw directly to this thermoplastic molded body 12 are screwed.

As a mechanical interface and a threaded sleeve can be used as a connecting element 13, via which the other components can be connected. Such an embodiment of a load introduction element 10 according to the invention is shown in FIG. 2, in which the thermoplastic molded body 12 has such a threaded sleeve 13. Otherwise, this load introduction element 10 according to FIG. 2 corresponds to that of the FVK structure 1 according to FIG. 1. Such a connecting element 13 may be made of plastic or metal.

The threaded sleeve 13 is encapsulated simultaneously with the production of the thermoplastic molding 12, or subsequently hot or cold pressed into the thermoplastic molding 12. According to Figure 2, the thermoplastic molded body 12 is connected with its base 12.1 over its entire surface with the fibers of the fiber insert 1 1 in the range 1 1.2. In contrast thereto, the load introduction element 10 shown in FIG. 4 is formed with a thermoplastic molded body 12, on whose base surface 12.1 an annular flange 12.2 is formed, which forms the thermoplastic composite with the impregnated region 11.21 of the fiber insert 11. In addition to this annular flange 12.2, further concentric nested further annular flanges may be provided, so that concentrically nested annular surfaces arise as the geometry of the impregnated regions 1 1.2 of the fiber insert 1, in whose interspaces the thermoset matrix 3 is produced in the production of an FRP structure 1 can flow according to FIG.

The load introduction element 10 according to FIG. 4 is produced in the same way as that according to FIG. Instead of a threaded sleeve, this load introduction element 10 to form a mechanical interface on a threaded bolt made of metal or plastic as a connecting element 14.

The load introduction element 10 according to FIG. 4 is used instead of that according to FIG. 1 for producing a FRP structure 1.

FIG. 5 shows a plan view of another load introduction element 10 with a thermoplastic molding 12 with fiber insert 1 partially impregnated with a thermoplastic matrix. The base 12.1 of the thermoplastic molding 12 has four cylindrical connection feet 12.3, which each have a composite with impregnated areas 1 1 .2 of the fiber insert 1 1 form. Outside of these circular regions 1 1.2, the fiber insert 11, ie the region 11, is not impregnated and forms a bond therewith with the thermoset matrix 3 corresponding to the FRP structure 1 according to FIG. The geometry of the impregnated regions 1 1 .2 of the fiber insert 1 1 can be configured in different ways. Thus, geometric arrangements are possible below the thermoplastic molding 12, which are characterized by alternating and juxtaposed areas of exposed / dry and impregnated fibers of the fiber insert 11.

The geometry of the impregnated regions 1 1 .2 of the fiber insert 1 1 of the load introduction elements 10 according to FIGS. 2, 4 and 5 are therefore only examples.

reference numeral

1 FRP structure

2 Fiber structure of the FRP structure 1

3 thermosetting matrix of FRP structure 1

10 load introduction element

1 1 fiber insert, semifinished fiber product of the load introduction element

1 1 .1 unimpregnated region of the fiber insert 1 1

1 1 .2 impregnated region of the fiber insert 1 1

12 Thermoplastic molded body of the load introduction element 10

12.1 base of the thermoplastic molding 12

12.2 Ring flange of base 12.1

12.3 Connecting foot of the thermoplastic molding 12

13 mechanical interface, connecting element

14 mechanical interface, connecting element

Claims

claims

1. FRP structure (1) comprising at least one fiber structure (2) embedded in a thermosetting matrix (3) and at least one load introduction element (10),

d a d u r c h e c e n c i n e s that

- The load introduction element (10) has a thermoplastic molded body (12) which is made by partial impregnation of a fiber insert (11) by means of thermoplastic injection molding, and

- The non-impregnated region (11.1) of the on the fiber structure (2) with the thermoplastic molded body (12) arranged fiber insert (1) together with the fiber structure (2) with the thermosetting matrix (3) is impregnated.

2. FRP structure (1) according to claim 1,

That is, the thermoplastic molded body (12) forms a composite with the fiber feeder (11) via at least one impregnated region (11.2) of the fiber insert (11).

3. FRP structure (1) according to claim 2,

That is, the thermoplastic molded body (12), via a plurality of impregnated regions (11.2) of the fiber insert (11), forms a bond with the fiber insert (reshaping).

4. FRP structure (1) according to one of the preceding claims, characterized in that for forming a mechanical interface of the thermoplastic molded body (12) has a connecting element (13, 14) which is produced by encapsulation during the production of the thermoplastic molded body (12).

5. FRP structure (1) according to one of the preceding claims,

That is, the reinforcing fibers (11) are formed of textile fibers and / or metal fibers of the group comprising a scrim, a woven fabric, a mat, a nonwoven, a braid, a knitted fabric and / or knitted fabric.

6. FRP structure (1) according to one of the preceding claims,

That is, the thermoplastic molded body (12) is cuboid, frusto-conical or truncated pyramid-shaped and preferably formed with ribs.