DE102017216496A1 - Method for producing a motor vehicle component from fiber-reinforced plastic - Google Patents

Abstract

The invention relates to a method for producing a motor vehicle component from a fiber-reinforced plastic. In this case, a further plastic structure is molded on a prefabricated plastic component, in particular on an organic sheet by means of a 3D printing, in particular by means of a melt layer method. It is provided that in the 3D printing method for attaching a further plastic structure, a reinforcing fiber is introduced, which is a local reinforcement of the motor vehicle component allows.

Description

The invention relates to a method for producing a motor vehicle component from a fiber-reinforced plastic according to the preamble of claim 1.

In order to meet the lightweight design requirements of today's automotive industry, fiber-reinforced plastics with their high specific mechanical strength are increasingly being used in the automotive industry. Thus, fiber-reinforced plastics are used both in the interior of the motor vehicle, as well as for external components such as hoods, fenders and other components. Furthermore, motor vehicles are known in which the fully supporting structure of the passenger compartment is made of fiber-reinforced plastic. In particular, fiber-reinforced hybrid structures, for example metallic inserts which are inserted into a fiber composite structure, offer many application possibilities due to their adaptable component properties, in order to produce motor vehicle components that meet the requirements. However, fiber reinforced plastic components have a strong anisotropy, so that the mechanical load capacity perpendicular to the fiber direction is significantly lower than in the fiber direction. A major requirement is to orient the fiber reinforcement so that the fibers are in the loading direction to accommodate the loads. The fibers must be oriented in the direction of loading because of the highly orthotropic properties of a continuous fiber-reinforced plastic. This means that the continuous fiber reinforced plastic in the fiber direction has a higher strength than transverse to this fiber direction.

Depending on the component geometry and load condition, the required fiber orientation in the plastic component thus results. The plastic component is then reinforced over the entire geometry with fibers to accommodate the loads can. Although the force flow through the component geometry is in many cases only between the connection points, the fiber reinforcement is carried out for procedural reasons almost over the entire component geometry. The fiber reinforcement is thus also in the areas of the plastic component, in which the power flow does not require reinforcement. As a result, many plastic components are unnecessarily reinforced with the expensive in relation to the plastic reinforcing fibers. Topology optimization can be used to detect the areas of force flow where reinforcement by the fibers is required. A targeted local fiber reinforcement of a plastic component made of thermoplastic material is conventionally realized by the injection molding of thermoformed organo sheets. For this purpose, complex injection molding tools with core pulls or the like are often required, which significantly increases the cost of tools and thus the injection molding process.

An already proven method for producing a fiber-reinforced hybrid structure is the back-molding of thermoformed organo sheets. Organic sheets are optionally made of glass fibers or carbon fibers which are embedded in a thermoplastic matrix, in particular of polypropylene or polyamide. The reason for this combination of the manufacturing processes "injection molding" and "thermoforming" lies in the exploitation of the good mechanical properties of organo sheets, especially with impact loads on the one hand and the increased design freedom of the injection molding process on the other. Although the injection molding of thermoformed organic sheets is possible for the production of small batches and prototypes or test carriers, it is very costly due to the high tool costs for the complex injection molding tools. The orientation of the reinforcing fibers is predetermined by the embedding of the fiber mats in the organic sheets and can not be flexibly adapted to the corresponding component geometry of the fiber-reinforced plastic component.

From the DE 10 2015 222 860 a method for the additive production of a component made of a plastic is known, wherein in the plastic component during the additive manufacturing process reinforcing fibers are inserted. However, a complete 3D printing of a component is comparatively complicated and expensive and therefore only suitable for a production of very small quantities, as they occur, for example, in prototype construction or for special applications, for example in motorsport.

From the WO 2015/122 555 A1 Also, a method for additive production of a plastic component is known, in which in the liquid plastic during the 3D printing process reinforcing fibers are inserted.

The DE 10 2015 016 272 B3 discloses a method for producing a fiber-reinforced plastic component, wherein on a support volume elements made of plastic layer by layer in a 3D printing, wherein to increase the strength of weld lines in a 3D micro injection molding, the plastic volume elements on the support with at least two after one Side open tool molds are generated, wherein in the interstices support structures are introduced.

The invention is based on the object, in a prefabricated plastic part in a simple and cost-effective manner to allow a targeted reinforcement of the component and from the Prior art overcome known disadvantages.

According to the invention this object is achieved by a method for producing a fiber-reinforced plastic component for a motor vehicle, wherein a fiber-reinforced plastic structure is formed by means of a 3D printing process on a prefabricated plastic component. The prefabricated plastic part is preferably produced by a thermal forming or an injection molding process. Thus, the prefabricated plastic part can be produced in a simple and cost-effective manner, so that the manufacturing costs compared to a component which, is completely made in a 3D printing, significantly lower. By means of a targeted formation of a fiber-reinforced plastic structure, the prefabricated plastic component can be purposefully reinforced at the points where reinforcement is sensible or necessary on the basis of a force flow determined by simulation or experiment. The remaining areas can be performed free of fiber material, whereby the expensive in comparison to the plastic matrix fiber material can be saved. It is particularly preferred if the material of the plastic structure applied to the prefabricated plastic part in the 3D printing is identical to the material of the prefabricated plastic part. As a result, a material connection of the fiber-reinforced plastic structure to the prefabricated plastic part is possible. In this case, no complex and expensive injection molding tools are necessary to reinforce the prefabricated plastic component, so that especially in small batches, prototypes and experimental vehicles, the production costs can be drastically reduced. In addition, development time can be saved, since the test carriers can be made available faster and the completion of components is not delayed by producing the injection molding tools for the back injection.

The features listed in the dependent claims advantageous refinements and improvements of the independent claim listed method for producing a fiber-reinforced plastic component for a motor vehicle are possible.

In a preferred embodiment of the invention, it is provided that the 3D printing method is carried out as a melt layer method. By a layer melting method, a plastic structure can be printed on the prefabricated plastic component in a simple and comparatively inexpensive manner. In this case, the reinforcing fibers can be embedded in the still liquid plastic, so that the fiber reinforcement takes place with the curing of the plastic in the context of the 3D printing process. Unlike curing a photopolymer under UV light, no additional illumination of the device is necessary so that the melt layer process is particularly suitable for forming a reinforcing structure on an existing device.

In a preferred embodiment of the method, it is advantageously provided that the fiber-reinforced plastic structure has a local continuous fiber reinforcement, wherein the orientation of the reinforcement fiber in the fiber-reinforced plastic structure is determined in the 3D printing method. By means of an endless fiber, a targeted arrangement and alignment of the reinforcing fibers in the matrix material of the fiber-reinforced plastic structure produced by the 3D printing is possible. In this case, the reinforcing fibers, in particular glass fibers or carbon fibers, can be arranged in the force flow direction of a presumed main load on the plastic component in order to absorb the forces and to discharge accordingly. Thus, a significant increase in component strength can be achieved by the printed fiber-reinforced plastic structure in a targeted manner. The supply of the continuous fiber is preferably carried out by unrolling fibers from a corresponding carrier.

In an advantageous improvement of the invention it is provided that the reinforcing fiber are fed along or through a pressure nozzle of the 3D printer. In order to allow the orientation of the reinforcing fibers, it is advantageous if the reinforcing fibers are fed via the printing nozzle of the 3D printer. In this case, the orientation of the reinforcing fiber can take place through the direction of printing, as a result of which topology optimization of the fiber orientation is possible. In addition, the material use of the reinforcing fibers is reduced because the reinforcing fibers are not deposited in areas where no fiber reinforcement is necessary.

According to a preferred embodiment of the method, it is provided that the prefabricated plastic component comprises an organic sheet. Preferably, the prefabricated plastic component is made in one piece as an organic sheet. Organic sheets are fiber-matrix semi-finished products. They consist of a fiber fabric or a fiber fabric embedded in a thermoplastic matrix. The advantages of a thermoplastic matrix lie in the hot forming capability of the semi-finished products and the resulting shorter process times compared to conventional thermoset fiber composites. The semi-finished products are completely impregnated and consolidated, that is, the reinforcing fibers are already completely wetted with plastic, there is no More air in the material and the semi-finished product is transformed into a three-dimensional component only by heating and subsequent pressing in short cycle times. During the forming process, the material does not undergo chemical transformation so that in particular component weakening does not occur due to delamination of the reinforcing fibers. This is of particular interest in the automotive industry with its short processing times. Frequently used fiber materials are glass, aramid and carbon (carbon). For woven and laid fibers, the fibers may also be perpendicular to each other, so that the mechanical properties of organo-sheet such as stiffness, strength and thermal expansion can be better defined than their metallic counterparts. In contrast to metal sheets, the tensile and compressive behavior, as well as other mechanical and thermal properties, is not isotropic. In addition, organic sheets are significantly lighter than comparable metallic sheets. Thus, both the prefabricated plastic component and the fiber-reinforced plastic structure has a high strength with low weight. By pressing the fiber-reinforced plastic structure, a targeted reinforcement of the organo-sheets can take place, wherein in particular the dissipation of forces perpendicular to the fiber mats of the organo-sheets can be significantly improved. By forming the basic structure in a thermal forming process of the organic sheet, a particularly cost-effective production is possible. The fiber-reinforced plastic structure is preferably not more than 10%, preferably not more than 5%, particularly preferably not more than 3%, of the total volume of the plastic component. As a result, only comparatively little material has to be applied in the 3D printing process, as a result of which short cycle times and comparatively low production costs are possible. As an alternative to an organic sheet, a hybrid structure of an organic sheet and a metal part is provided. This combination of thermal forming and 3D printing of the stiffening geometry advantages in terms of component design, so that even complex geometries, which could not be realized only by a thermal forming of an organic sheet, can be displayed in a simple and cost-effective manner. Furthermore, the potential for lightweight construction in a motor vehicle and a concomitant reduction in consumption are increased, since the field of application is made easier by the printing of functional elements which would not or only with great difficulty be represented by an injection molding process.

In a further improvement of the method is advantageously provided that the prefabricated plastic component is clamped on a support, which is displaceable and / or rotatable by means of a multi-axis robot in all three coordinate directions. By receiving the prefabricated plastic part, in particular a thermoformed organo-sheet, a particularly simple positioning of the plastic component to the printing nozzle of the 3D printer is possible. Thus, the fiber reinforced plastic structure can be selectively applied in the areas where reinforcement is necessary.

In a preferred embodiment of the invention it is provided that at least one of the printing nozzles of the 3D printer is attached to a robot head, which is displaceable and / or rotatable in all three coordinate directions. By a pivotable and displaceable pressure nozzle of the 3D printing, the fiber-reinforced plastic structure can be printed in comparatively difficult to access component sections, for example in undercuts, with a combination of slidable receptacles for the prefabricated plastic part and the pivotable or movable pressure nozzle of the 3D printer maximum flexibility is achieved.

To further improve the method is provided with advantage that the movement of the pressure nozzle and / or the movement of the receptacle for the prefabricated plastic component is controlled by means of a preprogrammed path control. In order to facilitate a simple automation of the manufacturing process, a path control for the movement of the printing nozzle and / or the receptacle for the prefabricated plastic component can be provided. As a result, process-reliable, repeatable production of fiber-reinforced plastic components with fiber-reinforced plastic structures for reinforcement is possible.

Alternatively, it is advantageously provided that a sensor is arranged on the 3D printer, in particular on a print head of the 3D printer, with which the surface of the prefabricated plastic component is scanned in order to position the molded fiber-reinforced plastic structure. As an alternative to a path controller, a sensor, in particular a laser sensor, can be provided on the 3D printer, with which the component surface of the prefabricated plastic component is scanned in order to specifically print the fiber-reinforced plastic structure in the heavily loaded regions in order to increase component stability.

In a further improvement of the invention, it is provided that at least one of the printing nozzles of the 3D printer is heated before and / or during the printing process of the fiber-reinforced plastic structure. By heating the pressure nozzles, the flowability of the plastic material to be applied is increased. The reinforcing fibers usually have a much higher melting point as the plastic of the matrix material so that the reinforcing fibers are not damaged by heating the pressure nozzles. By improving the flowability, the speed of the manufacturing process can be increased and the wear of the pressure nozzles can be reduced.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

• 1 ein Ausführungsbeispiel für eine Fertigungsvorrichtung zur Herstellung eines faserverstärkten Kunststoffbauteils mittels eines erfindungsgemäßen Herstellungsverfahrens;
• 2 die Fertigungsvorrichtung zur Herstellung eines faserverstärkten Kunststoffbauteils in einer zweiten Position;
• 3 ein Ausführungsbeispiel für ein Kraftfahrzeugbauteil, welches mittels eines erfindungsgemäßen Verfahrens hergestellt werden kann; und
• 4 ein Ablaufdiagramm für ein erfindungsgemäßes Verfahren zur Herstellung eines faserverstärkten Kunststoffbauteils.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

• 1 an embodiment of a manufacturing apparatus for producing a fiber-reinforced plastic component by means of a manufacturing method according to the invention;
• 2 the manufacturing device for producing a fiber-reinforced plastic component in a second position;
• 3 an embodiment of a motor vehicle component, which can be produced by a method according to the invention; and
• 4 a flow diagram for a method according to the invention for producing a fiber-reinforced plastic component.

1 shows a manufacturing apparatus for producing a fiber-reinforced plastic component 52 , The device comprises a 3D printer 10 and a recording 42 for the fiber-reinforced plastic component 52 , The 3D printer 10 has a printhead 54 with at least one pressure nozzle 12 on, which by means of a heating element 14 is heated to improve the diligence of the thermoplastic used in 3D printing. Further, on the 3D printer 10 a drive unit 40 for a positioning device 16 for positioning the pressure nozzle 12 intended. At the 3D printer 10 is at least one fiber feed 22 . 24 , preferably as in 1 illustrated a first fiber supply 22 and a second fiber feed 24 , for reinforcing fibers 30 . 32 for fiber reinforcement of the plastic material applied by the 3D printer 10. The reinforcing fibers 30 . 32 are each on a roll 34 . 36 wound as continuous fibers and are over pulleys 26 . 28 the printhead 54 of the 3D printer 10 supplied in the 3D-printing process in a corresponding orientation in the fiber-reinforced plastic component 52 to be integrated. The fiber-reinforced plastic component 52 includes a prefabricated plastic component 18 , in particular a fiber-reinforced organic sheet 50 which is brought into its component geometry in a manufacturing process deviating from 3D printing, in particular in a thermal forming process. To the prefabricated plastic component 18 becomes a fiber-reinforced plastic structure by means of the 3D printer 10 20 formed, which preferably made of the same material for the plastic matrix material and with the same reinforcing fibers 30 . 32 is executed.

The prefabricated plastic component 18 is in a recording 42 especially on a table 44 , taken by an industrial robot 46 can be moved or twisted. This is the industrial robot 46 preferably as a so-called six-axis robot 48 executed, so the recording 44 arbitrary to the pressure nozzle 12 moved in the room and / or can be twisted. The recording 42 can by a web programming of the industrial robot 46 be controlled in their movement, so that the prefabricated plastic component 18 to the pressure nozzle 12 is positioned to a dimensionally accurate pressure of the fiber-reinforced plastic structure 20 to enable.

At the printhead 54 of the 3D printer 10 may alternatively or additionally a sensor 38 , in particular a laser sensor 56 be provided with which the surface 58 of the prefabricated plastic component 18 is scanned to the fiber reinforced plastic structure 20 accurate to the prefabricated plastic component 18 print and thus the fiber-reinforced plastic component 52 to create.

In 2 the manufacturing device is shown at a later time of the manufacturing process. There are already several fiber-reinforced plastic structures 20 to the prefabricated plastic component 18 been printed. The industrial robot 46 has the recording 42 opposite to the illustration in 1 rotated 90 ° counterclockwise, leaving an end face 60 of the prefabricated plastic component 18 also by a fiber-reinforced plastic structure 20 can be strengthened.

In 3 is an element 62 a door panel 64 a motor vehicle shown which as a thermoformed organo sheet 50 with stiffening ribs 66 and a functional element 68 is executed. Here, the stiffening ribs 66 and the functional element 68 by means of a method according to the invention in a 3D printing on the organic sheet 50 be molded to cost a fiber-reinforced plastic component 52 to represent with a complex geometry.

In 4 is a flow diagram of a method according to the invention for producing a fiber-reinforced plastic component 52 shown. In the process, <100> becomes an organic sheet in a first production step 50 from a storage container by means of an industrial robot 46 taken and in a following process step < 110 > preheated in a stove. The preheated organo sheet 50 is then in a subsequent manufacturing step < 120 > brought into its final, three-dimensional component geometry in a thermoforming tool, so that a prefabricated plastic component 18 arises. In a manufacturing step <130> is the prefabricated plastic component 18 through the industrial robot 46 to the pressure nozzle 12 of the 3D printer and in a process step < 140 > the fiber reinforced plastic structure 20 to the prefabricated plastic component 18 printed. In one step < 150 > becomes the finished fiber-reinforced plastic component 52 from the recording 42 of the industrial robot 46 taken and filed.

LIST OF REFERENCE NUMBERS

10

3D printer

12

pressure nozzle

14

heating element

16

positioning

18

prefabricated plastic component

20

fiber reinforced plastic structure

22

first fiber feed

24

second fiber feed

26

idler pulley

28

idler pulley

30

reinforcing fiber

32

reinforcing fiber

34

role

36

role

38

sensor

40

drive unit

42

admission

44

table

46

industrial robots

48

Six-axis robot

50

organosheet

52

fiber-reinforced plastic component

54

printhead

56

laser sensor

58

surface

60

face

62

element

64

door trim

66

stiffening ribs

68

functional element

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 102015222860 [0005]
• WO 2015/122555 A1 [0006]
• DE 102015016272 B3 [0007]

Claims (10)

Method for producing a fiber-reinforced plastic component (52) for a motor vehicle, characterized in that a fiber-reinforced plastic structure (20) is formed by means of a 3D printing process on a prefabricated plastic component (18). Method according to Claim 1 , characterized in that the 3D printing process is carried out as a melt layer method. Method according to Claim 1 or 2 characterized in that the fiber reinforced plastic structure (20) comprises a local continuous fiber reinforcement (30, 32), the orientation of the reinforcement fiber (30, 32) being defined in the fiber reinforced plastic structure (20) in the 3D printing process. Method according to one of Claims 1 to 3 , characterized in that the reinforcing fibers (30, 32) are fed through and along a pressure nozzle (12) of the 3D printer (10). Method according to one of Claims 1 to 4 , characterized in that the prefabricated plastic component (18) comprises an organic sheet (50). Method according to one of Claims 1 to 5 , characterized in that the prefabricated plastic component (18) is clamped on a receptacle (42) which is displaceable and / or rotatable in all three coordinate directions by means of a multi-axis industrial robot (46). Method according to one of Claims 1 to 6 , characterized in that at least one of the printing nozzles (12) of the 3D printer (10) is fixed to a robot head, which is displaceable and / or rotatable in all three coordinate directions. Method according to one of Claims 1 to 7 , characterized in that the movement of the pressure nozzle (12) and / or the movement of the receptacle (42) for the prefabricated plastic component (18) is controlled by means of a pre-programmed path control. Method according to one of Claims 1 to 7 , characterized in that on the 3D printer (10), in particular on a print head (54) of the 3D printer (10), a sensor (38) is arranged, with which the surface (58) of the prefabricated plastic component (18) is scanned to position the fiber reinforced plastic structure (20). Method according to one of Claims 1 to 9 , characterized in that at least one of the printing nozzles (12) of the 3D printer (10) is heated before and / or during the printing process of the fiber-reinforced plastic structure (20).

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