DE102016210180A1 - Method and device for producing a foam core in a plastic component - Google Patents

Abstract

The present invention relates to a method for producing a foam core in a plastic component, in particular in a fiber-reinforced plastic component (20) comprising the steps of: - introducing at least one partition (7) into a cavity (11) of a hollow plastic body (1), wherein within the cavity (11) a cavity (12) is produced, - injecting a filling compound (8) into the cavity (12), wherein the flow direction of the filling compound (8) from an injection point to the foreclosure (7). Moreover, the invention also relates to a device for producing a foam core in a plastic component and to a corresponding plastic component (20).

Description

The present invention relates to a method and an apparatus for producing a foam core in a plastic component and a corresponding plastic component.

In many high technologies, such as In aircraft construction or automotive engineering, structural components are formed as composite components made of composite materials, since composite components combine advantageous physical properties of the individual composite materials. Composite components have, for example, a foam core, which is surrounded by a cover layer to improve a load capacity, in particular a mechanical and / or thermal and / or chemical resistance or the like. For example, the topsheet may be a scrim or braid of fibers such as fibers. Glass fibers, carbon fibers, aramid fibers or the like, coated with a curable matrix material, e.g. a resin, impregnated or interspersed. In this way, for example, a particularly lightweight structural component with high mechanical strength can be produced. The function of the foam core in such structural components is essentially the reduction of component vibrations, in particular by damping due to a somewhat resilient foam structure, and thus of driving noise to increase driving comfort.

To produce such composite components, structural foams are used, for example, since they have a relatively low density and dimensional stability. In many applications, the structural foams are therefore designed as rigid foams with only a low, in particular microscopic, compliance. The structural foam may e.g. be coated with a scrim or braid of fibers, which are impregnated or interspersed with the matrix material, for example by a Resin Transfer Molding process, which is also referred to as RTM process. According to alternative methods for reducing component vibrations of thin sheets, it is known to inject foam material components into intermediate spaces between components, in particular sheet metal. These methods are used in particular for reducing vibrations in thin sheets.

Known methods for the production of structural components with foam cores have the disadvantage that they have a very complicated process control and therefore cause very high production costs. Furthermore, only vibration-damping structural components can be produced by means of these methods. Structural components with a particularly improved energy absorption or compressive strength can not be produced by the known methods.

Moreover, it is not readily possible to improve the mechanical properties of hollow profiles in reinforcement areas by introducing foams. When introducing the foaming material into the interior of the hollow profile, an exact, desired distribution of the material and the material density can not be guaranteed.

It is therefore an object of the present invention to remedy the disadvantages described above in a method and an apparatus for producing a fiber-reinforced plastic component or at least partially correct. In particular, it is an object of the present invention to provide a method and an apparatus for producing a foam core in a plastic component, which ensure the production of a load-optimized component in a reinforcing region in a simple and cost-effective manner. Thus, the mechanical properties, in particular the energy absorption capacity and / or compressive strength can be improved in a fiber-reinforced component. Furthermore, it is the object of the present invention to provide a plastic component with improved energy absorption capacity and / or pressure resistance.

The above object is solved by the independent claims. Further features and details of the invention will become apparent from the dependent claims, the description and the drawings. In this case, features and details that are described in connection with the inventive method, of course, also in connection with the plastic component according to the invention and the device according to the invention and in each case vice versa, so that with respect to the disclosure of the individual aspects of the invention always reciprocal reference is or may be.

• – Einbringen mindestens einer Abschottung in einen Hohlraum eines hohlen Kunststoffkörpers, wobei innerhalb des Hohlraums eine Kavität erzeugt wird,
• – Einspritzen einer Füllmasse in die Kavität, wobei die Fließrichtung der Füllmasse von einer Einspritzstelle zu der Abschottung verläuft. Vorteilhafter Weise wird somit das Kunststoffbauteil bei dessen Herstellung in einem vordefinierten Verstärkungsbereich belastungsoptimiert verstärkt.

According to a first aspect of the invention, the object is achieved by a method for producing a foam core in a plastic component. The method includes the following steps:

• Introducing at least one partition into a cavity of a hollow plastic body, wherein a cavity is produced within the cavity,
• - Injection of a filling material into the cavity, wherein the flow direction of the filling material from an injection point to the foreclosure runs. Advantageously, the plastic component is thus reinforced in a stress-optimized manner during its production in a predefined amplification range.

The provided plastic body can for example consist of one or more individual structures, which are joined together to form the plastic body. Preferably, a profile with a round or polygonal cross-section is used. Alternatively, it is also possible to use a profile whose section is sectionally round, straight or angular.

The plastic body has at least one first access opening for injecting the filling compound and a second access opening, preferably a plurality of second access openings into which a partition can be inserted. The access openings connect the inner cavity to an environment of the plastic body. The profile can be open on one or both sides. By introducing the foreclosure, it is possible to close an open side of the profile, so that forms a cavity in the cavity of the plastic body between the inner walls and the foreclosure. If the profile is only open on one side, it is sufficient to introduce a partition into the cavity in order to form the cavity. When using a profile open on both sides, two seals must be used. In general, by using multiple bulkheads in the cavity at a predetermined location of the profile to be reinforced, a cavity can be created. The access openings are preferably arranged on one side of the plastic body, e.g. a side which is preferably not a visible side and is preferably disposable for introduction of the filling material facing upwards, so that the flowable filling material can easily flow into the interior of the cavity via the first access opening.

When providing the plastic body is preferably fixed in position, so that a position of the at least one access opening is fixed. A layer according to the invention is understood to mean a position and an orientation. The cavity is formed in a region of the plastic body to be reinforced. This reinforcement region has an actual shape which corresponds to a desired shape of the foamed foam material. It can be provided according to the invention also moving the plastic body for better distribution of the flowable foam material. The plastic body may be formed, for example, fiber-reinforced plastic.

After the penetration of the partition into the cavity, this partition is transferred into a cavity which seals off the cavity. As a result, the cavity is subdivided into a plurality of regions, namely into an area which forms the cavity and into at least one further area. In other words, the foreclosure is formed variable in shape. It may take an outer shape, which is particularly advantageous in performing the foreclosure through the corresponding access opening. When the partition is inside the cavity of the plastic body, the partition is transferred to a second external shape. In this form, the foreclosure forms a wall or boundary of the cavity. As a result, a cavity can be created in a particularly simple manner, which acts as a mold for the subsequent foaming step. The cavity thus represents a negative mold, in which the filling material for local reinforcement of the plastic body is introduced and the outer shape of the foam body assumes.

The partition can be filled by the application of a medium in the gaseous or liquid state and, after being introduced into the cavity, transferred to the partitioning mold, for example by being pumped up.

The filling compound can foam during and / or after injection into a foam body. The plastic component to be produced thus has in the reinforcement region a foam core made of a pressure-stable and / or energy-absorbing foam, which is surrounded by a component wall. A reinforcing region is understood according to the invention to mean a region of the plastic component which is designed to be optimized for the load by the foam. It may therefore be provided according to the invention that only a part of the plastic component, namely the reinforcing region, is formed in this way and another part of the plastic component has a different configuration in which the plastic component is hollow, for example. The foam body thus offers the advantage that transverse forces acting on one side on the plastic body are passed over the foam body to other sides of the plastic body.

The introduction of the flowable filling material into the cavity of the plastic body takes place via the at least one first access opening or, in the case of several first access openings, can also take place via a plurality of first access openings. Thus, a uniform distribution of the foam material within the cavity can be improved. This results in a flow direction of the filling material from the injection point of the injector away to the foreclosure or the foreclosures out.

The foam material preferably comprises polyurethane (PU) or the like. The foam which can be produced with the foam material preferably has a relatively high hardness and density. Preferably, the foam material is provided with further ingredients which improve or increase, for example, a pressure stability and / or energy absorption capacity of the foam. Furthermore, that is Foam material is formed to foam in an exothermic reaction to the foam. This means that the foam material can be foamed by activation with release of heat. Further preferably, it may be provided that the foam which can be produced with the foam material is additionally designed to damp vibration and / or sound-insulating.

Since the foam due to the pores usually has a larger specific volume or a lower specific density than the filling material, the cavity is preferably not completely filled with the filling material, in particular a maximum internal pressure within the cavity and thus an excessive pressure on the plastic body, or to avoid the component walls of the plastic body. Furthermore, excessive filling of the cavity could hinder complete or even foaming if necessary. Alternatively, it can be provided that excess filling material, e.g. through the access opening and / or an opening provided for this, escape from the cavity or can be displaced.

When foaming the filler material to the solid foam, at least the reinforcement region of the cavity is completely filled with the solid foam, so that in the reinforcement region the foam contacts the component wall in a planar manner. Surface contact means in the context of the invention that the foam is applied to the component wall, wherein no larger pores or air pockets are formed as the pores of the foam on the component wall. Accordingly, in the reinforcement region, an outer contour of the foam corresponds to an inner contour of the wall of the cavity. An exerted on the outside of the component wall pressure is thus evenly on or in the foam forwarded. The foam thus provides an abutment for the component wall. In this way, a punctual overloading of the component wall due to an external force can be avoided.

In a further method step, the partition is removed from the cavity. This offers the advantage that lighter components can be realized, compared to those in which the foreclosure remains in the plastic component.

The method according to the invention for producing a plastic component which is optimized in terms of stress in a reinforcing region has the advantage over conventional methods that a plastic component which is optimized by a foam can be produced by simple means and at low cost. This is particularly suitable for use as a structural component in motor vehicles.

Structural components in the context of this invention are, in particular, side members, cross members, A, B, C, D pillars, sills, roof side frames, roof bow, etc.

In a further aspect, the invention relates to a device for producing a foam core in a plastic component with at least one partition, which is at least partially introduced into a cavity of a hollow plastic body, wherein the partition with the wall of the cavity forms a cavity and an injection device for injecting a Filling material into the cavity.

Furthermore, the foreclosure can be formed variable in shape. The partition may be convertible from a partitioning shape to a non-partitioning form and vice versa.

In one embodiment, the foreclosure may be inflatable. The foreclosure can be filled with a liquid or gaseous medium. By applying this medium with pressure, the partition can be converted into a schschende outer shape.

Furthermore, the partition can be retracted and / or extended in a receptacle or housing.

The partition can be made extendable by application of pressure from the receptacle and retractable by applying negative pressure in the receptacle.

According to a preferred embodiment of the invention, a filling material is used, which heats up during the exothermic foaming to a temperature which is at least 20 ° C higher than the ambient temperature. It is particularly preferred that the foam material at room temperature during the exothermic foaming warms to between about 100 ° C and 130 ° C. Such a foam material is particularly advantageous for plastic bodies made of a material which is particularly sensitive to temperature, in order to avoid excessive temperature loading.

Preferably, a filler material is used, which is designed for the independent formation of an adhesive bond with the component wall of the plastic body. Alternatively or additionally, before the introduction of the filling material, an adhesive can be applied to the side of the component wall sent to the cavity, for example by spray application. An adhesive bond between the foam and the component wall has the advantage that with simple means relative movements between the foam and the component wall, in particular due to Vibrations, effectively prevented in this way. An erosive wear of the foam is thus avoided or at least reduced.

It is preferred that the filler material comprises at least two components which are mixed together for foaming. The filler material preferably has two components. Such a filler is also referred to as a two-component filler. The two components can be stored separately from each other. By mixing the two components of the foaming process is initiated. It is preferred that the foaming process does not take place directly during mixing of the components or immediately after mixing, but with a delay, so that a distribution of the filling material is ensured within the cavity. Too early solidification entails the risk that the filling material can not penetrate into some areas of the reinforcing region of the cavity, since a distribution of the filling material can be hindered by the already formed foam. With such a filler of several components of the foaming process is well controlled.

More preferably, the filling material is injected during introduction by means of an injection device or a nozzle into the cavity. For this example, a mixing nozzle can be used, in which the components are already mixed in the nozzle. Alternatively, an injection nozzle can be used, by means of which the components are injected into the cavity in such a way that the components are mixed with one another after leaving the nozzle. Injection by means of a nozzle has the advantage that a uniform distribution of the filling material within the cavity and a mixing of the components are improved.

Preferably, a plastic body is provided, which is formed as a fiber composite component, wherein the component wall having a matrix material impregnated fibers. Such plastic body have low strength and high strength and high load capacity.

The device according to the invention has the same advantages as already described above for the method according to the invention for producing a fiber-reinforced plastic component according to the first aspect of the invention.

In a further aspect, the invention relates to a plastic component, comprising an outer plastic body and a foam body, which is arranged in the plastic body in a reinforcing region. The outer plastic body is formed in particular of fiber-reinforced plastic.

Preferably, the plastic component is produced by means of a method according to the invention. The process can be carried out with simple means and inexpensively. It can also plastic components in large quantities in a mass production by means of the method can be produced economically.

For the purposes of this invention, reinforcing fibers may be organic or inorganic reinforcing fibers. The reinforcing fibers may be, for example, carbon fibers. These form with the plastic matrix a carbon fiber reinforced plastic, also called CFRP (Carbon Fiber Reinforced Plastic, CFRP). The associated FRP component is then a CFRP component. The reinforcing fibers can also be glass fibers, for example. These form with the plastic matrix a glass fiber reinforced plastic, also called GRP. The associated FRP component is then a GRP component. However, the invention is not limited thereto, and the reinforcing fibers may be e.g. also aramid fibers, polyester fibers, nylon fibers, polyethylene fibers, PMMA fibers, basalt fibers, boron fibers, ceramic fibers, silica fibers, steel fibers and / or natural fibers.

The material of the plastic matrix may in particular comprise one or more thermoplastics (thermoplastics) and / or duroplastic plastics (thermosetting plastics). Fiber-reinforced plastics with a thermoplastic matrix have the advantage that they can be subsequently reshaped or welded. Suitable thermoplastics include, for example: polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSU), polyetherimide (PEI) and / or polytetrafluoroethene (PTFE). Fiber-reinforced plastics with a thermosetting matrix can not be reshaped after curing or crosslinking of the matrix. They advantageously have a high temperature range of use. This is especially true for hot-curing systems that cure under high temperatures.

Fiber-reinforced plastics with duroplastic matrix usually have the highest strengths. As thermosetting plastics or matrix, e.g. epoxy resin (EP), unsaturated polyester resin (UP), vinyl ester resin (VE), phenol-formaldehyde resin (PF), diallyl phthalate resin (DAP), methacrylate resin (MMA), polyurethane (PUR), amino resins, melamine resin (MF / MP) and / or urea resin (UF).

A device according to the invention and a method according to the invention are explained in more detail below with reference to drawings. Each show schematically:

1 in a sectional view a plastic body,

2 in a sectional view of the plastic body 1 with a manufacturing device arranged above it,

3 in a sectional view of the plastic body 1 with a manufacturing device arranged thereon,

4 in a sectional view of the plastic body 1 , with foreclosures in a partitioning shape,

5 in a sectional view of the plastic body 1 while filling the filling material into the cavity,

6 in a sectional view of the plastic body 1 while the filler cures to foam,

7 in a sectional view of the plastic body 1 , after removing the foreclosure and

8th in a side view of the finished plastic component.

Elements with the same function and mode of action are in the 1 to 8th each provided with the same reference numerals.

In 1 to 8th is schematically a plastic body 1 shown in cut side views. The plastic body 1 is formed in this embodiment, a hollow cylinder and has a component wall having a cavity 11 surrounds. The plastic body 1 is designed as a profile and closes a cavity 11 ein, which spreads figuratively to the left and right over the section shown. In the component wall of the plastic body 11 is an access opening 13 for filling in liquid filling material 8th educated. The plastic body 1 is designed as a fiber composite component. In the plastic body shown here 1 it is just an example for illustration. Plastic body 1 According to the invention, they can have virtually any shape, in particular with curvatures, edges, curves or the like.

In 2 a manufacturing device is shown, the figuratively above the plastic body 1 is arranged. This device comprises an injection device or nozzle 3 about the one filler 8th can be sprayed out. The nozzle 3 is about a carrier 4 with recordings 5 connected, taking pictures 5 are shown as tubes. In the pictures 5 is each a foreclosure 7 arranged, however, in 2 not shown. The foreclosure 7 is as an inflatable balloon in a retracted position within the receptacles 5 arranged. The production device thus comprises a mixing head 3 as injector and pipes 5 over a bridge or a girder 4 are arranged together contiguous. As in 3 shown, the device is so on the plastic body 1 put on that a tip of the nozzle 2 as well as the tips of the shots 5 in the cavity 11 protrude. The foreclosures are shown in a non-partitioning form or external shape and in the shots 5 arranged. In addition, the manufacturing device includes seals 2 at the injector 3 and at the recordings 5 are arranged. In the in 3 shown position seal the sealing elements 2 from.

Thereafter, an overpressure P _Ü in the recordings 5 produced, through which a medium contained therein in the foreclosures 7 is pressed. The foreclosures 7 are thereby inflated and form in a baloon in the cavity 11 out, like in 4 shown. In this illustration are the foreclosures 7 presented in their isolating shape or form. Inside the cavity 11 becomes a cavity 12 formed, which of the foreclosures 7 and the inner surface of the wall of the plastic body 1 is formed. The cavity 12 is through the foreclosures 7 from the areas of the cavity 11 left and right next to the cavity 11 foreclosed. In other words, seal the foreclosures 7 in the hollow profile 1 a cavity 12 from.

After creating the cavity 12 , with the help of the foreclosures 7 , gets into the cavity 12 a filling 8th over the nozzle 3 sprayed, as in 5 shown. This filling material 8th floods the cavity 12 partially or completely. Thereafter, the filling material foams 8th out, leaving the foam body 9 is formed. About the mixing head 3 The foam-forming filler is in the cavity 12 brought in. Within the cavity, due to the blowing effect of the foam, a natural internal pressure sets in. During that, the overpressure in the foreclosures becomes 7 maintained, so that the shape of the cavity 12 on the foam body 9 transfers as in 6 shown. The foam 9 forms evenly. In addition, the Innenendruch can be controlled or regulated in the cavity by means not shown additional equipment, for example by separate loading with compressed air.

7 shows a state in which by means of negative pressure PU the foreclosures 7 again in the recording 5 were sucked in. By the negative pressure the balloons become 7 vented. On the outer wall of the balloons 7 Optionally, an anti-adhesion coating can be applied, which removes the mold from the wall of the foam 9 favored. The foreclosures or the balloons 7 pull themselves into the receptacles or the tubes 5 back. In this condition, the shots 5 be easily threaded in a subsequent cycle. This is the foreclosures 7 from the plastic body 1 away. Following this, the manufacturing device of the finished plastic component 20 be removed.

In 8th is thus the finished plastic component 20 shown, which consists of an outer fiber reinforced profile 1 is formed that in a Verstärkkunsbereich by a foam body 9 is reinforced.

In the following, the advantages of the invention will be summarized. The present invention produces the foam body 9 in one form, namely the cavity 12 , In this "foam molding", the rising foam can 9 against the wall of the cavity 12 support, creating a homogeneous foam 9 is produced. When free foaming in hollow profiles without cavity, the cavity limit is missing, whereby the foam can not form homogeneous. The quality of the foam 9 is substantially increased in the case of "foam molding" compared to "free foaming", since the risk of density differences and voids / bubbles is reduced. This offers the advantage that the components of a virtual design are accessible, thereby high costs for hardware tests (static, dynamic, crash) are avoided. The potential for weight-reduced design with local foams is fully usable.

LIST OF REFERENCE NUMBERS

1

hollow body

2

poetry

3

 Injector

4

 carrier

5

 admission

6

 overprint

7

 isolation

8th

 filling compound

9

 foam

10

vacuum

11

cavity

12

cavity

20

Fiber-reinforced component

Claims (12)

Method for producing a foam core in a plastic component, in particular in a fiber-reinforced plastic component ( 20 ) comprising the steps of: - introducing at least one foreclosure ( 7 ) into a cavity ( 11 ) of a hollow plastic body ( 1 ), wherein within the cavity ( 11 ) a cavity ( 12 ), - injecting a filling compound ( 8th ) into the cavity ( 12 ), wherein the flow direction of the filling material ( 8th ) from an injection point to the foreclosure ( 7 ) runs. Method according to claim 1, characterized in that the partitioning ( 7 ) after insertion into the cavity ( 11 ) into a cavity ( 12 ) from the cavity ( 11 ) is transferred to a partitioning form. Method according to claim 1 or 2, characterized in that the partitioning ( 7 ) after insertion into the cavity ( 11 ) is pumped up. A method according to claim 1 to 3, characterized in that from the filling material ( 8th ) during and / or after injection, a foam body ( 9 ) is produced. Method according to one of claims 1 to 4, characterized in that the foreclosure ( 7 ) from the cavity ( 11 ) Will get removed. Device for producing a foam core in a plastic component, in particular in a fiber-reinforced plastic component ( 20 ) with: - at least one foreclosure ( 7 ), which at least partially into a cavity ( 11 ) of a hollow plastic body ( 1 ), the foreclosure ( 7 ) with the wall of the cavity ( 11 ) a cavity ( 12 ) and - an injection device ( 3 ) for injecting a filling compound ( 8th ) into the cavity ( 12 ). Apparatus according to claim 6, characterized in that the foreclosure ( 7 ) is formed variable in shape. Device according to one of claims 6 or 7, characterized in that the foreclosure ( 7 ) is designed inflatable. Device according to one of claims 6 to 8, characterized in that the foreclosure ( 7 ) into a recording ( 5 ) is retractable and / or extendable. Apparatus according to claim 9, characterized in that the foreclosure ( 7 ) by applying excess pressure from the receptacle ( 5 ) extendable and retractable by application of negative pressure in the receptacle is formed. Plastic component ( 20 ), with an outer plastic body ( 10 ) and a foam body ( 9 ) in the plastic body ( 10 ) is arranged in a gain region. Plastic component ( 20 ) according to claim 11, characterized in that the outer plastic body formed of fiber reinforced plastic, wherein reinforcing fibers are embedded in a matrix.

Images