Method and apparatus for manufactoring a sandwich part and sandwich part

Abstract

A method for producing a sandwich component, which method permits the production of a sandwich component with a class-A surface without cumbersome reworking of the visible surface of the sandwich component, a sandwich component produced by the method, and a corresponding device for producing the sandwich component.

Claims

1. A method for producing a sandwich component for a motor vehicle, the method comprising: forming a pack by lining or encapsulating a honeycomb core having a plurality of webs on both sides with at least one ply of a fibrous material, said at least one ply forming cover plies; impregnating, wetting or spraying the pack with a matrix; forming the sandwich component by compressing and hardening the pack to form a plurality of zones having different numbers of honeycomb cores layered one on top of another; applying, at least on a visible side of the sandwich component, a class-A surface applied thereto as Reaction Injection Moulding (RIM) layer using an RIM tool divided into different temperature zones to correspond to the varying thickness of the motor vehicle component, wherein applying the RIM layer is performed by concurrently injecting a matrix in an injection region at one side of the sandwich component while also applying a vacuum in a vacuum region of the sandwich component situated opposite the injection region.

2. The method of claim 1, wherein applying the RIM layer comprises applying the RIM layer in zones of the sandwich component.

3. The method of claim 1, wherein the RIM layer has a thickness of 0.2-2 mm.

4. The method of claim 1, wherein the impregnating, wetting or spraying is performed in a composite spray molding (CSM) spraying process.

5. The method of claim 1, wherein the matrix comprises a polyurethane resin systems (PUR) matrix.

6. The method of claim 1, further comprising, after the compressing and hardening, cooling and/or thermally stabilizing the sandwich component.

7. The method of claim 1, further comprising, after the compressing and hardening, tempering the sandwich component.

8. The method of claim 1, further comprising, after the compressing and hardening, coarse cutting the sandwich component in order to shape the sandwich component.

9. The method of claim 1, further comprising, before applying the RIM layer, trimming an outer contour of the sandwich component, and/or milling and/or drilling the sandwich component.

10. The method of claim 1, further comprising, after applying the RIM layer, activating a surface of the sandwich component, and/or painting the sandwich component.

11. The method of claim 1, further comprising controlling the temperature of each temperature zone of the RIM tool independently of one another and in accordance with the thickness of the motor vehicle component.

12. A method for producing a motor vehicle component, the method comprising: impregnating, wetting or spraying a pack with a matrix material, the pack including a honeycomb core and a ply of fibrous material as a cover layer on a top side and a bottom side of the honeycomb core; forming, in response to the impregnating, wetting or spraying, the motor vehicle component by compressing and hardening the pack to have different zones having different numbers of honeycomb cores layered one on top of another, the motor vehicle component thereby having varying thicknesses; and applying, using an RIM tool divided into different temperature zones to correspond to the varying thickness of the motor vehicle component, a class-A surface as Reaction Injection Moulding (RIM) layer on at least a visible side of the motor vehicle component by concurrently injecting an RIM matrix in an injection region at one side of the motor vehicle component, while also applying a first vacuum at a first vacuum region of the motor vehicle component situated opposite the injection region to gap fill the motor vehicle component using the RIM matrix, and while also applying a second vacuum in a second vacuum region of the motor vehicle component to clamp the motor vehicle component in position.

13. The method of claim 12, further comprising separating the first vacuum region from the second vacuum region by providing a seal on a non-visible side of the motor vehicle component.

14. The method of claim 12, further comprising forming a continuous transition between a top side of the RIM layer and the cover layer by providing a seal on a non-visible side of the motor vehicle component.

15. The method of claim 12, further comprising controlling the temperature of each temperature zone of the RIM tool independently of one another and in accordance with the thickness of the motor vehicle component.

16. A method for producing a motor vehicle component, the method comprising: forming, by compressing and hardening a pack impregnated with a matrix material, the motor vehicle component to have a plurality of zones of varying thickness, the pack including a honeycomb core and a ply of material as a cover layer on a top side and a bottom side of the honeycomb core; and applying, using an RIM tool divided into different temperature zones to correspond to the varying thickness of the motor vehicle component, a class-A surface as Reaction Injection Moulding (RIM) layer on at least a visible side of the component by concurrently injecting an RIM matrix in an injection region at one side of the component, while also applying a first vacuum at a first vacuum region of the component situated opposite the injection region to gap fill the component using the RIM matrix, and while also applying a second vacuum in a second vacuum region of the component to clamp the component in position.

17. The method of claim 16, further comprising separating the first vacuum region from the second vacuum region by providing a seal on a non-visible side of the motor vehicle component.

18. The method of claim 16, further comprising forming a continuous transition between a top side of the RIM layer and the cover layer by providing a seal on a non-visible side of the motor vehicle component.

19. The method of claim 16, further comprising controlling the temperature of each temperature zone of the RIM tool independently of one another and in accordance with the thickness of the motor vehicle component.

Description

DRAWINGS

(1) Embodiments will be illustrated by way of example in the drawings and explained in the description below.

(2) FIG. 1 illustrates a method for producing a sandwich component, in accordance with embodiments.

(3) FIG. 2 illustrates a device for carrying out the method for producing a sandwich component, specifically an RIM tool (right), and a detail view thereof (left), in accordance with embodiments.

(4) FIG. 3 illustrates a sandwich component, in accordance with embodiments.

DESCRIPTION

(5) FIG. 1 illustrates method blocks S1 to S7, some of which are optional, in a method for producing a sandwich component, in accordance with embodiments.

(6) In accordance with embodiments, in method block S1, a method for producing a fibre composite sandwich component comprises forming a composite package or pack by lining up or encapsulating, on the top and on the bottom, a honeycomb core 1 having a plurality of webs, with at least one ply of a fibrous material 2, for example, of a fibrous semi-finished part, as cover layers or cover plies.

(7) The cores or honeycomb cores 1 may be paper cores or cardboard cores, or are composed of other cellulose-based materials. The honeycomb cores 1 may also be cores composed of plastic, such as polyurethane (PU), polypropylene (PP) and the like, or from metal, wood or foamed material. The honeycomb cores may have webs in a honeycomb arrangement or in an undulating arrangement. The webs may, however, also form circular, triangular, rectangular, square, trapezoidal or polygonal cells, wherein these need not involve regularly repeating shapes (within a honeycomb core).

(8) In method block S2, subsequently, the pack or composite package composed of honeycomb core 1 and cover plies 2 is impregnated, wetted and/or sprayed with a matrix 3, such as, for example, PUR, in a CSM spraying process.

(9) In method block S3, subsequently, the pack that has had the matrix 3 applied to it is placed into a compression-moulding tool 4, such as, for example, a heated compression-moulding tool, and is compressed in accordance with the required component geometry and hardened.

(10) In accordance with embodiments, it is optionally possible, while the component is left in the tool, for a contour cut, that is to say, coarse cutting to shape, to be performed around the tool or around the tool geometry.

(11) In method block S4, subsequently, it is optionally possible, if necessary, for the component to be cooled in the compression-moulding tool 4 or outside the compression-moulding tool, in particular, cooled or thermally stabilized in a further tool, for example, in a workpiece cooling device 10.

(12) In accordance with embodiments, optionally, tempering of the component, that is to say, a temperature process over a relatively long period of time, in order for component distortions to be compensated and/or the level of cross-linking of the materials to be increased, may be performed in a further tool or in a further device. Further cooling of the component is optionally also performed.

(13) In method block S5, this may be followed by trimming of the outer contour, or cutting to shape of the side regions/edges, in accordance with the required component contour, and optionally also a chip-removing machining process, such as, for example, milling of the outer contour and milling and drilling for inserts and other similar recesses in the component.

(14) In method block S6, a paintable class-A surface is applied, that is to say, a surface is applied as an RIM layer 5 to the visible side and/or around the outer edges in a V-RIM process, that is to say, with the use of a vacuum for drawing in the introduced matrix 3, in an RIM tool 9. It is achieved in this way that no disturbing undulation, shrinkage or pores, such as are otherwise conventional, remain(s) on the visible surface of the component. Further tempering may optionally be performed at this location.

(15) In method block S7, optionally, preparation of the surfaces thus produced into a state ready for painting may be performed by way of surface activation in a final finishing process. Optionally, inserts may be inserted into the component.

(16) In the Vacuum Reaction Injection Moulding (V-RIM) process, a liquid PUR material is injected under pressure and with the application of a vacuum at the side situated opposite the flow front in a gap generated between the surface of the sandwich component and the surface of the RIM tool 9. See, FIG. 2. Here, the polyurethane lining material reacts under the action of temperature (heated tool) and hardens in the tool gap. This gives rise to the component quality in a manner dependent on the tool surface. After the final contour machining process (removal of sprue and protruding edges, grinding of surface), the component is ready to be painted.

(17) For the production of a fibre composite visible component, such as, for example, an engine hood, with a class-A surface straight from the tool and manufactured in a PUR wet pressing process, it may be the case that a paper honeycomb core 1 is encapsulated on the top and on the bottom with at least one layer 2 of fibrous material or fibrous semiifinished part material composed for example of wovens, scrims, knitted fabrics, mats, meshes and nonwovens composed of glass fibre and/or carbon fibre and/or textile materials and/or ceramic fibres and/or natural fibres and/or plastics fibres.

(18) To attain the different compression hardnesses and stability, for example, in the hinge region, the honeycomb core 1 may be of reinforced design at the required points. Subsequently, the application of the polyurethane matrix 3 is performed in the PUR-CSM spraying process.

(19) During this process of application by spraying, the fibrous semi-finished parts 2 are wetted on both sides with a thermally activatable PUR system which, applied with an optimum layer thickness, produces a connection between the core 1 and cover plies 2. Here, targeted matrix application is also possible in all component regions with the addition of short-fibre materials such as glass fibre, carbon fibre, or textile fibres. In the subsequent process step, the component is compressed within a heated mould 4 in accordance with its required component geometry and is hardened.

(20) The trimming of the outer contour is performed as a subsequent step before the paintable class-A surface (RIM layer 5) is applied to the visible side and around the outer edges of the component in the V-RIM process and is prepared into a state ready for painting in a final finishing process (surface activation). The V-RIM process is highly advantageous owing to the component size of visible components, for example in the case of engine hoods in the automobile industry, in relation to the layer thickness (gap between sandwich component and RIM tool 9 between 0.2-2.0 mm).

(21) In accordance with embodiments, the PUR-RIM matrix 3 is not only forced into the gap between sandwich component and RIM tool 9 by way of punctiform and/or areal injection nozzles 6, but the flow front is drawn in by way of a vacuum 7 applied at the opposite side at one or more points or over an area, thus permitting unbroken gap filling in a reliable manner in terms of a process. It is sought to optimize the ratio of the component surface area to layer thickness in the context of the component geometry, wherein the minimized component overall weight is the decisive influential factor.

(22) Conventional gap filling systems have the disadvantage that, beyond ratios of surface areas to layer thickness of less than 0.01, the solidification of the flow front occurs before the gap filling process is complete. Even PUR systems with conventional hardening delay are not capable of ensuring the required open time while simultaneously meeting the requirements with regard to the class-A surface quality straight from the toolsaid systems have an increased tendency for bubble formation in the climate change test owing to an activator.

(23) During the V-RIM surface application, the sandwich component itself is held in the lower part of the receptacle by way of a vacuum clamping system and/or by way of an areally applied vacuum 8 and positioned by way of a fibre composite RPS system. Here, the vacuum 7 is separated from the vacuum 8, for example, by a seal 14, such that the different vacuum pressures required for performing the respective different functions, for example, the drawing-in of the matrix or holding the sandwich component in position on the receptacle or on the tool, can be set.

(24) In order, in the case of sandwich components which exhibit relatively low compressive strength with resistance to damage, to realize a class-A surface and sealing of the trimmed edges, it is necessary to perform surface application by injection of matrix filler material at pressures below 20 bar and/or with the aid of a vacuum in a region situated opposite the injection region in a closed and/or heated/zonally heated tool. See, FIG. 2.

(25) Said surface material, for example, polyurethane and/or other flowable surface materials for plastics surfaces, is hardened in a temperature range between 40? C. and 170? C. in a temperature-controlled tool. Through targeted control of the parameters of matrix material mixing ratio, viscosity and tool temperature, it is possible to attain hardening times of less than 5 minutes. To make the hardening process more homogeneous and to be able to introduce heat in a controlled fashion, the tool is divided into temperature zones, areas, or regions. The temperature zones must be temperature-controlled, that is to say heated and/or cooled, independently of one another and in accordance with the component geometry. Furthermore, an additional tempering process may be integrated after the hardening/cooling and after the V-RIM application in order to increase the temperature stability of the component, in particular for inline and online paint resistance. This tempering process may be performed at up to 210? C. and may last a maximum of 60 minutes, either in a heated tool, a furnace or in a conveyor furnace.

(26) To realize a durable, exacting surface, the surface layer must be no thinner than 0.2 mm and no thicker than 2.0 mm. For better setting of the surface thickness, the tool may be configured by way of positive mould technology.

(27) In the edge region, the surface material fills the gap between the trimmed (also milled, lasered, punched or similarly prefabricated) structural component and the tool surface. In this case, the thickness of the surface layer may be significantly greater, and may even amount to a few millimeters, See, FIGS. 2 and 3.

(28) The component is placed into and positioned in the tool by hand or in automated fashion, and specifically, may be centred by way of the component form or via an RPS system, and held on the opposite component surface via vacuum suction and/or via closing and fixing aids.

(29) The tool has one or more punctiform sprues or a fan sprue in order to distribute the surface material in bubble-free fashion over the component surface and in accordance with the selected layer thickness. Furthermore, in the tool, there is provided a ventilation or vacuum device in order to enable the air to be extracted from the tool during the injection process and to be able to keep the injection pressure as low as possible. The position of the sprue and/or of the ventilation means is dependent on the component shape and on the tool and the selected plant concept (tilting and pivoting tool).

(30) Immediately before the gap filling between tool and component comes to an end (depending on the tool or the component shape to be filled), the ventilation and/or vacuum device are closed in order to ensure the reliable and bubble-free surface and edge filling. The point in time is dependent on multiple parameters, such as temperature of the tool, component and/or matrix, duration of the filling process, fill volume (parameterized) and fill pressure.

(31) After the hardening process, the tool is opened and the component is removed. Depending on component size and shape, ejectors may be integrated in the tool, which ensure damage-free and easy removal.

(32) Any burrs on the component resulting from the tool parting plane may subsequently be cut off or ground off manually or by machine. The component is ready for the further process steps (preparation for painting).

(33) In accordance with embodiments, the entire process may take place within a cycle time of 280 seconds, wherein the application of the surface layer (RIM layer 5) to realize the class-A surface may be performed only in that region of the component which will later be visible, and around component edges. The sealing of the edges serves for sealing off the component and for improving the haptic impression. The V-RIM process may be performed as a process step in parallel with the sandwich production.

(34) A suitable PUR material that can be processed in the V-RIM process and which ensures the demanded surface quality is available, for example, from the company R?hl Puromer GmbH.

(35) A sandwich component in accordance with embodiments may also be utilized for functional integration, and may in particular perform an antenna function, illumination function, energy storage function, or air supply and guidance function in the engine bay. Further functional integration may also be realized with regard to visual effects such as direct and indirect illumination, which on the one hand may be implemented as a safety function or on the other hand may be used as a design-emphasizing element for highlighting contours and structures on the vehicle.

(36) FIG. 3 illustrates a finished, crushed sandwich component in accordance with embodiments. The component comprises a honeycomb core 1 and cover layers 2. The cells of the honeycomb core 1 have been crushed or compression-moulded with particularly great intensity in particular in a first zone 12, and in a second zone 13 have been compressed to a lesser extent and form a profile toward the first zone 12. The component furthermore has an RIM layer 5 and an edge seal as an RIM layer 5 on the face side 11 of the component.

(37) In accordance with embodiments, the shape of the end of the RIM layer 5 can be defined by way of a seal 14 (illustrated in FIG. 2). For example, in the case of a square cross section of the seal 14, a corresponding transition of the RIM layer 5 is produced on the underside of the sandwich component, here, the shaping of the tool is self-evidently also decisive. Via other seal shapes of the seal 14 and/or other tool forms, a different profile or tapering-out of the RIM layer 5 and/or a different transition of the RIM layer 5 to the cover layer 2 would be possible.

(38) The term coupled or connected may be used herein to refer to any type of relationship, direct or indirect, between the components in question, and may apply to electrical, mechanical, fluid, optical, electromagnetic, electromechanical or other connections. In addition, the terms first, second, etc. are used herein only to facilitate discussion, and carry no particular temporal or chronological significance unless otherwise indicated.

(39) This written description uses examples to disclose the invention, including the preferred embodiments, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of embodiments is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspects, may be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application.

LIST OF REFERENCE SIGNS

(40) 1 Honeycomb core 2 Fibrous ply 3 Matrix 4 Compression moulding tool 5 RIM (Reaction Injection Moulding) layer 6 Punctiform and/or areal injection nozzle 7 First vacuum 8 Second vacuum 9 RIM tool 10 Workpiece cooling device 11 Face side 12 First zone 13 Second zone 14 Seal