Fiber composite part of a motor vehicle, mounting part for such a fiber composite part and manufacturing method

Abstract

A mounting part (11) for affixing a composite fiber part of a motor vehicle to at least one adjoining component of a motor vehicle is made from a fiber composite material. The mounting part (11) has a three-dimensionally shape that defines ribs and/or webs and/or protrusions and/or depressions.

Claims

1. A method for manufacturing a composite part of an automobile, the method comprising: preparing a liquid or flowable first mixture of a first thermosetting polymer and only fibers having lengths less than or equal to a specified length; filling the first mixture into a three-dimensionally shaped first mold configured to form a mounting part having a plurality of external surface regions defining at least one of a rib, a protrusion and a depression and at least one internally threaded recess formed in the mounting part without extending entirely through the mounting part; curing the first thermosetting resin of the mounting part; preparing a liquid or flowable second mixture of a second thermosetting polymer and only fibers having lengths greater than the specified length to define a fiber composite matrix; filling the second mixture into a second mold so that the second mixture covers all of the external surface regions of the mounting part, while leaving an opening at a position aligned with the internally threaded recess of the mounting part; curing the second thermosetting polymer to form a composite part that has the mounting part embedded in the fiber composite matrix while the at least one internally threaded recess is accessible via the opening for receiving a screw connection to mount the composite part to an adjoining component of the automobile.

2. The method of claim 1, wherein the step of curing the first thermosetting resin of the mounting part comprises curing the first thermosetting resin in the first mold for a period of between 0.5 min and 10 min at a temperature between 100° C. and 200° C. and at a pressure of more than 100 bar.

3. The method of claim 1, wherein the first mixture comprises between 30% by volume and 70% by volume fibers and between 70% by volume and 30% by volume thermosetting polymer, with the fibers having lengths of between 3 mm and 100 mm.

4. The method of claim 3, wherein the first mixture comprises between 40% by volume and 65% by volume fibers and between 60% by volume and 35% by volume thermosetting polymer, with the fibers having lengths of between 20 mm and 80 mm.

5. The method of claim 1, further comprising placing the cured mounting parts in the fiber composite matrix in an uncured state and then curing the fiber composite matrix around the cured mounting part to form fiber composite part for the automobile.

6. The method of claim 1, wherein the first thermosetting polymer and the second thermosetting polymer are identical.

7. The method of claim 1, wherein the fibers of the fiber composite matrix are carbon fibers or glass fibers.

8. The method of claim 1, further comprising screw-connecting the composite part to a component of the automobile.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a detail of a fiber composite part of a motor vehicle according to the invention in cross section in the region of an incorporated mounting part and FIG. 1a is a detail of the fiber composite part mounted to an adjoining component of a motor vehicle.

(2) FIG. 2 is a first mounting part in different perspective views.

(3) FIG. 3 is a second mounting part in different perspective views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) The invention relates to a mounting part for affixing a fiber composite part of a motor vehicle to at least one adjoining component of the motor vehicle. The mounting part is incorporated or embedded in the respective fiber composite part and is referred to as an insert. The invention also relates to a fiber composite part of a motor vehicle with at least one such mounting part and to a method for manufacturing the mounting part and the fiber composite part.

(5) FIG. 1 is a partial schematic cross section through a fiber composite part 10 of a motor vehicle in the region of a mounting part 11 incorporated or embedded in the fiber composite part 10. The mounting part 11 is provided for affixing the fiber composite part 10 to at least one adjoining component 20 of a motor vehicle.

(6) A recess 12 with an internal thread 13 is cut into the mounting part 11 to allow a direct screw connection 22 of the fiber composite part 10 via the mounting part 11 to an adjoining component 20. Alternatively, an internally threaded bush can be inserted into the recess 12 so that the fiber composite part 11 can be screwed indirectly via the threaded bush to an adjoining component 20.

(7) The mounting part 11 incorporated in the fiber composite part 10 is a three-dimensionally shaped structure with ribs, and/or webs and/or protrusions and/or depressions. FIGS. 2 and 3 show in different perspective views examples of three-dimensionally shaped mounting parts 11 and 11″ formed with ribs 14, webs 15, protrusions 16 and/or depressions 17.

(8) The mounting parts 11, 11 or 11″ for a fiber composite part are made from a fiber composite material, namely from a carbon fiber reinforced or a glass fiber reinforced polymer with relatively short fibers. The carbon fiber reinforced or glass fiber reinforced polymer is preferably a thermosetting polymer, in particular an epoxy resin or a vinyl-ester resin or polyurethane.

(9) The relatively short fibers of the mounting part 11, 11′ or 11″ have a length of between 3 mm and 100 mm. Preferably, the length of the relatively short fibers of the mounting part 11, 11′ or 11″ is between 20 mm and 80 mm.

(10) The mounting part 11, 11 or 11″ may have fibers of exclusively one length, such as short fibers exclusively of a length of 25 mm or 70 mm or 75 mm. Alternatively, the respective mounting part 11, 11′ or 11″ may have relatively short fibers of at least two different lengths, for example first fibers of a length of 25 mm and second fibers of a length of 50 mm. Likewise it is possible that the mounting part 11, 11′ or 11″ has first fibers of a length of 10 mm and second fibers of a length of 75 mm.

(11) The use of fibers of different lengths for the mounting part advantageously enables both a sufficient strength of the respective mounting part 11, 11′ and 11″ and any desired three-dimensional shaping of the part.

(12) The respective mounting part 11, 11′ or 11″ preferably has between 30% by volume and 70% by volume fibers and between 70% by volume and 30% by volume thermosetting polymer.

(13) The mounting part 11, 11′ or 11″ preferably comprises between 40% by volume and 65% by volume fibers and between 60% by volume and 35% by volume thermosetting polymer, in particular epoxy resin.

(14) The mounting parts 11, 11′ or 11″ for a fiber composite part 10 of a motor vehicle themselves uniquely are made from a fiber composite material. In this context relatively short fibers in a defined mixing ratio with a polymer are used in the respective mounting part 11, 11′ or 11″. Thus, three-dimensionally shaped mounting parts made from a fiber composite material are provided with a three-dimensional shape typically associated with metallic mounting parts and with a sufficiently high strength.

(15) The fiber composite parts 10 and the mounting parts 11, 11′ or 11″ incorporated therein preferably are made from a fiber composite material, with identical fiber material of different lengths and with an identical polymer material, such as thermosetting polymer, being used in the fiber composite part 10 and in the mounting part 11, 11′ or 11″. The fibers of the fiber composite part 10 are relatively long continuous fibers, namely relatively long carbon fibers or glass fibers.

(16) The manufacturing of the mounting part 11, 11′ or 11″ proceeds by preparing a liquid, in particular a viscous or flowable mixture of polymer and fibers. This mixture preferably comprises between 30% by volume and 70% by volume fibers and the rest polymer, in particular thermosetting polymer. The preferred mixture comprises between 40% by volume and 65% volume fibers and the rest polymer, such as epoxy resin.

(17) This mixture is weighed and the weighed mixture is filled into a three-dimensionally shaped mold for the mounting part. The mold for the mounting part 11, 11′ or 11″ then is closed and the mounting part is cured in a molding process with a heated mold. The curing in the mold takes place at a defined temperature and at a defined pressure over a defined period of time. In particular, the curing of the mounting part 11, 11′ or 11″ takes place in an isothermically heated mold at a temperature between 100° C. and 200° C. and at a pressure of more than 100 bar over a period of between 0.5 minutes, that is to say 30 seconds, and 10 minutes.

(18) The manufactured mounting parts 11, 11′ or 11″ are placed in an uncured fiber composite matrix to form a semi-finished product. This semi-finished product may be a so-called prepreg of fibers and thermosetting polymer or a dry semi-finished product consisting of only fibers, into which, subsequent to the positioning of the mounting parts, thermosetting polymer, in particular epoxy resin, is injected. The fiber composite matrix with the incorporated or embedded and already cured mounting parts 11, 11′ or 11″ then is cured, and the mounting parts 11, 11′ or 11″ forming an intimate bond with the identical polymer material of the fiber composite matrix to form a composite part 10.