DE102011008759A1 - Method for manufacturing e.g. structure component that is utilized in vehicle, involves forming fiber semi-finished material, curing fluent matrix material by heating, and removing mold body from injection mold - Google Patents

Abstract

The method involves forming a fiber semi-finished material (1) consisting of dry preforms (2) and/or preform assemblies. A fluent matrix material is injected into a cavity (4) through injection spacers, where the cavity accommodates the fiber semi-finished material and is formed by mould parts (5-8). Back pressure is applied against a convex-shaped membrane (9) such that the matrix material is pressed into the fiber semi-finished material. The matrix material is cured by heating, and a mold body is removed from an injection mold. The membrane is made of plastic, metal or elastomer. An independent claim is also included for a device for manufacturing a mold body from fiber reinforced plastics.

Description

The invention relates to a method and an apparatus for producing molded articles made of fiber-reinforced plastics according to the preamble of patent claims 1 and 9 of the invention.

Methods and apparatus for the production of moldings from fiber-reinforced plastics have been known for quite some time in a variety of designs. Thus, said moldings can be produced by the known RTM process (RTM = Resin Transfer Molding). In this case, fiber material is essentially introduced into an injection mold comprising at least one cavity from two or more molded parts and impregnated therein with a matrix which is reactive as a result of heating at least one molded part, in particular a resin (eg epoxy resin) or a resin mixture. Ideally, the resin or resin mixture fills said cavity completely. After completion of the chemical reaction of the matrix and curing of the same, the fiber-reinforced molded body can be removed from the injection mold.

In practice, however, it has been found that the volume of the resin during curing thereof is reduced by up to about 3% (cf. WO 2010/118923 A2 , Page 2, paragraph 1) and the finished molded body disadvantageously does not always have the geometry defined by the cavity. To counter this circumstance, it is from the said WO 2010/118923 A2 It is known to arrange a membrane between a first molded part and a second molded part or also further molded parts, so that a first region is formed between the first molded part and the membrane and a second region is formed between the second molded part and the membrane. In the first area a fiber mat can be arranged, which is impregnated with resin or impregnated with resin. In the second area can be generated by a pressure generating means, a back pressure against the membrane and the fiber mat, which acts as a pressure generating means, a fluid. By pressing the membrane in the direction of the fiber mat, the shrinkage resulting from the reaction of the resin upon solidification can be compensated for during the further injection with resin. There may also be provided a closable resin drain to remove excess resin.

Other comparable solutions with the above solution are further from the EP 1 013 409 A2 , of the DE 2001 16 817 U1 and the DE 10 2005 011 977 A1 known. Finally it is off the DE 199 06 124 A1 it is known per se to initially not fully close a mold used according to the RTM method when injecting the same with resin, whereby the flow resistance to the injected resin should be minimized and an improved distribution of the resin in the fiber material should be achievable. Advantageously, the resin should also be moved transversely to the direction of injection flow during the final complete closure of the mold and thus pressed more strongly into the fiber web.

All the variants of solution shown have in common that during the process, they cause at least partial wetting of the injection mold with matrix material, such as resin, resulting in increased effort with regard to the preparation of the mold for subsequent injection molding cycles by cleaning the same from remainders of said matrix active.

On this basis, it is an object of the invention to provide an improved process for the production of molded articles made of fiber-reinforced plastics, mediate of which it is allowed on the one hand to produce moldings of fiber-reinforced plastics with exact predefined geometry. On the other hand, in view of the state of the art, lower injection cycle times should be achievable, which are associated in particular with minimized preparatory work of the injection mold for carrying out the injection molding process. It is another object of the invention to provide a suitable device or arrangement for carrying out the method.

• a) Ausbildung eines aus einer oder mehreren trockenen Preformen und/oder Preform-ZSB's bestehenden Faser-Halbzeugs,
• b) luftdichtes umschließen desselben mittels zweier oder mehrerer, zumindest eine Kavität ausbildender Formteile, wobei für wenigstens eines der Formteile eine zumindest abschnittsweise flexible Membran verwendet wird,
• c) Evakuierung der besagten Kavität über eine oder mehrere an die Kavität angeschlossene Evakuierungsleitungen und Schließen derselben nach Evakuierung,
• d) Einlegen des luftdicht umschlossenen Faser-Halbzeugs in eine als Druckkammer ausgebildete Spritzgießform,
• e) Injektion eines fließfähigen Matrixwerkstoffes in die zumindest eine durch die Formteile gebildete und das Faser-Halbzeug aufnehmende Kavität durch an die Kavität angeschlossene Injektionsleitungen hindurch derart, dass sich die flexible Membran während des Injektionsprozesses mit einem Injektionsdruck „P₁” aufgrund vorgesehener Distanzhalter der Spritzgießform in Grenzen nach außen wölbt,
• f) Aufbringen eines Gegendruckes „P₂” gegen die nach außen gewölbte Membran bei geöffneten Injektionsleitungen und/oder Evakuierungsleitungen derart, dass der fließfähige Matrixwerkstoff in das Faser-Halbzeug gepresst wird indem der Matrixwerkstoff vornehmlich das Faser-Halbzeug in Dickenrichtung desselben respektive normal zur Faserrichtung durchtränkt, und dass überschüssiger Matrixwerkstoff durch besagte geöffnete Injektionsleitungen und/oder Evakuierungsleitungen abfließt,
• g) Aushärten des Matrixwerkstoffes, gegebenenfalls durch Erwärmung, und
• h) Entnahme des Formkörpers aus der Spritzgießform.

The object is achieved first by the reproduced in claim 1 method. Thereafter, the process for the production of moldings from fiber-reinforced plastics, the following steps to be carried out sequentially:

• a) forming a fiber semifinished product consisting of one or more dry preforms and / or preform ZSBs,
• b) airtight enclosing the same by means of two or more, at least one cavity forming moldings, wherein for at least one of the mold parts, an at least partially flexible membrane is used,
• c) evacuation of said cavity via one or more evacuation lines connected to the cavity and closing same after evacuation,
• d) inserting the air-tightly enclosed fiber semifinished product in an injection mold designed as a pressure chamber,
• e) injection of a flowable matrix material into the at least one cavity formed by the mold parts and receiving the fiber semi-finished by injection lines connected to the cavity such that the flexible membrane during the injection process with an injection pressure "P ₁ " due to provided spacers of the injection mold bulges outward in borders,
• f) applying a back pressure "P ₂ " against the outwardly curved membrane with open injection lines and / or evacuation lines such that the flowable matrix material is pressed into the fiber semifinished product by the matrix material mainly the fiber semifinished product in the same direction or normal to the fiber direction impregnated, and that excess matrix material flows through said opened injection lines and / or evacuation lines,
• g) curing of the matrix material, optionally by heating, and
• h) removal of the molding from the injection mold.

This method allows a simple and cost-effective production of molded articles made of fiber-reinforced plastics, as required by the prior art extensive cleaning work on the injection mold, in particular due to adhering to the injection mold matrix material, are largely avoided.

The subclaims describe preferred developments or refinements of the invention.

Thus, with regard to method step a), provision may be made for the dry preforms and / or preform CSBs to be formed from one or more dry and possibly preformed individual layers of fibrous material, such as carbon fibers, where the individual layers are fibrous webs and / or nonwoven webs can and have different fiber orientations. By this measure can be advantageously taken on the strength of the molded body influence. With regard to method step b), a diaphragm made of a plastic, a metal, an elastomer or another suitable flexible material can advantageously be used as the at least partially flexible diaphragm. Further advantageously, in view of the process step e) as a flowable matrix material, a curable resin-hardener mixture can be used. Furthermore, with regard to method step f), a gaseous or liquid pressure medium may be used to apply a back pressure "P ₂ " to the outwardly curved diaphragm.

Furthermore, with regard to method step g), the optionally provided heating of the matrix material can expediently be effected by means of one or more heated molds of the injection mold. Finally, with regard to method step h), this can be followed by detachment of the molded parts from the fiber-reinforced plastic of the molded article. It is therefore possible either to release said moldings from the fiber-reinforced plastic of the shaped body and to use them for further injection molding cycles or to use them as lost moldings by forming the outer skin of the fiber-reinforced plastic of the shaped body. The method is particularly suitable for the production of moldings in the form of structural components and / or surface components and / or visible carbon components on vehicles.

The object is solved further by the reproduced in claim 9 apparatus for performing the method.

The invention is explained below with reference to the embodiment schematically illustrated in the drawings. Show it:

1 to 4 extremely schematic cross-sectional views of the formation of an airtight enclosed semi-finished fiber product (fiber-semifinished product package),

5 an extremely schematic sectional view with respect to the transfer of the airtight-enclosed fiber semifinished product package into an injection mold,

6 The injection mold fitted with the airtight semi-finished fiber package 5 when closed,

7 The injection mold fitted with the airtight semi-finished fiber package 6 in partial section with advantageous detail solutions on the same,

8th to 11 extremely schematic sectional views of advanced times of injection of a flowable matrix material into the fiber semifinished product,

10a - 10d Details after 10 at an advanced age,

12 an extremely schematic sectional view with respect to the removal of the finished molded article from the injection mold,

13 a highly schematic sectional view of the molding during a liberation of the same of this enclosing moldings, and

14 an extremely schematic sectional view of the freed from said moldings molding.

The inventive method for the production of moldings from fiber-reinforced Plastics is characterized by the fact that according to the 1 to 4 first a fiber semi-finished product 1 is trained. The fiber semi-finished product 1 consists of one or more dry preforms 2 and / or preform ZSB's (ZSB = assembly), which in turn each consist of one or more dry and optionally preformed individual layers 3 from fiber material, such as carbon fibers known per se, are formed (see. 1 and 2 ). In the fiber semi-finished product 1 can be known per se reinforcing, carrier, fitting elements, honeycomb, foams, films, sheets and / or mold elements, such as. B. auxiliary body, which can optionally inflate, and / or known per se elements, the intended plastic impregnation of the fiber-semifinished product 1 facilitate, be incorporated or such parts can the semi-finished fiber 1 be assigned. Furthermore, individual layers can 3 be fixed to each other, for example by means of thermally melting binder types and / or by sewing, embroidering, Taften and / or the like. More (not shown).

Following this, the semi-finished fiber is 1 by means of two or more, at least one cavity 4 forming moldings 5 to 8th enclosed airtight. By way of example, a lower molded part is given here by way of example 5 provided, which is formed relatively stable shape and acts as a support shape respectively handling assistance and on which the individual layers 3 Fiber material are stored. Furthermore, the cavity 4 laterally delimiting molded parts 6 . 7 and one the cavity 4 upward limiting molding 8th provided, including the moldings 6 to 8th with preforms 2 of the type described above are occupied. The moldings 5 to 8th are then joined together in such a way that they are the semi-finished fiber 1 surround airtight. It is a compact fiber semi-finished package, so to speak. For at least one of the moldings 6 to 8th , present for the upper molding 8th , is an at least partially flexible membrane 9 used, which consists of a plastic, a metal, an elastomer or other suitable flexible material. The other moldings 5 to 7 in the present case consist of a suitable relatively dimensionally stable material, for example of plastic or metal.

The airtight enclosed semi-finished fiber 1 In addition, the now-formed fiber-semifinished product package are also not shown in detail to be closed and opened evacuation lines and injection lines 10 assigned, which will be discussed in more detail below. The evacuation lines allow the formed cavity 4 to evacuate said fiber-semifinished product package or create a vacuum therein.

If this is done and said evacuation pipes are closed again, the in 4 shown hermetically sealed and comfortably transportable and comprehensively protected semi-finished fiber 1 in the form of a fiber semi-finished package in an injection mold 11 inserted and by means of known fasteners 12 releasably secured within it (cf. 5 to 7 ). The injection mold 11 exists according to the 5 to 11 from a plurality of molds, in this case from a tool lower part 13 and two tool tops 14 . 15 , which in the closed state, a pressure chamber 16 form. How the particular 7 As can be seen, have the molds adjacent to the flexible membrane 9 are arranged, in this case the tool shells 14 . 15 , on her to the membrane 9 facing inner lateral surface via spacers 17 in the form of so-called tuning strips, which in turn present a certain spacing 18 (see esp. 10a ) of the inner circumferential surface of the tool shells 14 . 15 to the flexible membrane 9 cause.

Now, the injection of a matrix material 19 , For example, a resin-hardener mixture in the cavity formed 4 of the airtight semi-finished fiber product 1 respectively of the fiber-semifinished product packet through the injection lines already mentioned above and provided thereon 10 be made. The 8th to 10d , especially the 10a to 10d , thereby show the penetration progress of the matrix material 18 into the cavity 4 of the fiber semi-finished package.

How in particular the 10b and 10c it can be seen, the matrix material flows 19 initially essentially parallel between the individual layers 3 the preform 2 , As a result of the injection process within the cavity 4 Forming overpressure, which corresponds to the conventional injection pressure "P ₁ ", becomes matrix material 19 also above the preform 2 introduced because the flexible membrane 9 a bulging of the same in between the inner circumferential surface of the tool shells 14 . 15 and the outer circumferential surface of the upper molding 8th formed gap-shaped spacing 18 allowed. The flexible membrane 9 nestles according to 10c to the inner circumferential surface of the tool shells 14 . 15 at.

Thereafter, it is indicated, with respect to the injection pressure "P ₁ " higher back pressure "P ₂ " against the outwardly curved flexible membrane 9 applied. This is done as a precaution with the injection lines open 10 and / or evacuation lines. As a result, the flowable matrix material 19 or the resin-hardener mixture in the fiber semifinished product 1 pressed and in such a way that the matrix material 19 especially the fiber Workpiece 1 in the thickness direction of the same or normal to the fiber direction soaked and is the flexible membrane 9 transferred to a position corresponding to the desired end position thereof ( 10c combined with 10d ). Excess matrix material 19 can through said injection lines 10 and / or evacuation lines drain or is from the cavity 4 pressed. This measure results in a high degree of penetration of the fiber semifinished product with a minimized injection time 1 , The application of said back pressure "P ₂ " can be advantageously carried out by means of a known gaseous or liquid pressure medium.

Is the fiber semi-finished product 1 with matrix material 19 soaked, it can harden. Preferably, said matrix material is 19 a heat-reactive matrix material 19 , in particular from a heat-reactive resin-hardener mixture. In view of this, one or more molds of the injection mold can be heated and the required heat of reaction to the matrix material 19 submit.

Is the matrix material 19 hardened ( 11 ), according to 12 the still with moldings 5 to 8th enclosed moldings 20 the injection mold 11 be removed, in the present case, first the two tool shells 14 . 15 be lifted off the same and then said moldings 20 from the lower tool part 13 is solved ( 12 ).

As already stated above, the molded parts 5 to 8th as so-called lost moldings 5 to 8th on the molding 20 remain and then form an outer skin of the fiber-reinforced plastic of the molding 20 out ( 12 ). In contrast, it may also be appropriate, in retrospect, the moldings 5 to 8th from the fiber-reinforced plastic and to use it for further injection molding cycles ( 13 and 14 ). In this case, it may be appropriate to see the moldings 5 to 8th with a separating layer, not shown, such as a ceramic separating layer, a Teflon layer or metallic, z. B. vapor-deposited release layer to the demolding of the molding 20 to facilitate.

LIST OF REFERENCE NUMBERS

1

Fiber semis

2

preform

3

individual layers

4

cavity

5

molding

6

molding

7

molding

8th

molding

9

flexible membrane

10

injection line

11

injection mold

12

fastener

13

Tool part

14

Upper die

15

Upper die

16

pressure chamber

17

spacer

18

spacing

19

Matrix material

20

moldings

"P ₁ "

injection pressure

"P ₂ "

backpressure

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

• WO 2010/118923 A2 [0003, 0003]
• EP 1013409 A2 [0004]
• DE 200116817 U1 [0004]
• DE 102005011977 A1 [0004]
• DE 19906124 A1 [0004]

Claims (10)

Process for the production of moldings ( 20 ) of fiber-reinforced plastics, characterized by the following process steps: a) formation of one or more dry preforms ( 2 ) and / or preform ZSB's existing semi-finished fiber product ( 1 b) airtight enclosing the same by means of two or more, at least one cavity ( 4 ) forming moldings ( 5 . 6 . 7 . 8th ), wherein for at least one of the molded parts ( 8th ) an at least partially flexible membrane ( 9 ), c) evacuation of said cavity ( 4 ) via one or more to the cavity ( 4 ) connected evacuation lines and closing them after evacuation, d) inserting the airtight semi-finished fiber product ( 1 ) in a pressure chamber ( 16 ) formed injection mold ( 11 ), e) injection of a flowable matrix material ( 19 ) into the at least one through the molded parts ( 5 . 6 . 7 . 8th ) and the semifinished fiber product ( 1 ) receiving cavity ( 4 ) through to the cavity ( 4 ) connected injection lines ( 10 ) such that the flexible membrane ( 9 ) during the injection process with an injection pressure "P ₁ " due to provided spacers ( 17 ) of the injection mold ( 11 ) bulges outwards in limits, f) application of a back pressure "P ₂ " against the outwardly curved membrane ( 9 ) with opened injection lines ( 10 ) and / or evacuation lines such that the flowable matrix material ( 19 ) in the fiber semifinished product ( 1 ) is pressed by the matrix material ( 19 ) primarily the fiber semifinished product ( 1 ) in the thickness direction of the same or normal to the fiber direction, and that excess matrix material ( 19 ) through said opened injection lines ( 10 ) and / or evacuation lines, g) hardening of the matrix material ( 19 ), optionally by heating, and h) removal of the shaped body ( 20 ) from the injection mold ( 11 ). A method according to claim 1, characterized in that with regard to the process step a) the dry preforms ( 2 ) and / or preform ZSB's from one or more dry and optionally preformed individual layers ( 3 ) are formed from fibrous material, such as carbon fibers or the like, wherein the individual layers may be fibrous and / or fibrous nonwovens and may have different fiber orientations. A method according to claim 1, characterized in that with regard to the method step b) as at least partially flexible membrane ( 9 ) a membrane ( 9 ) is used from a plastic, a metal, an elastomer or other suitable flexible material. A method according to claim 1, characterized in that with regard to the method step e) as a flowable matrix material ( 19 ) a curable resin-hardener mixture is used. A method according to claim 1, characterized in that with regard to the method step f) for applying a back pressure "P ₂ " against the outwardly curved membrane ( 9 ) a gaseous or liquid pressure medium is used. A method according to claim 1, characterized in that with regard to the method step g) the optionally provided heating of the matrix material ( 19 ) by means of one or more heated molds of the injection mold ( 11 ) he follows. A method according to claim 1, characterized in that with regard to the process step h) to this a detachment of the molded parts ( 5 . 6 . 7 . 8th ) of the fiber-reinforced plastic of the shaped body ( 20 ). Method according to one of claims 1 to 7 for the production of moldings ( 20 ) in the form of structural components and / or surface components and / or visible carbon components on vehicles. Device for the production of molded articles ( 20 ) made of fiber-reinforced plastics for carrying out the method according to one of claims 1 to 8, characterized by at least one described in the description and / or claims for the invention and / or shown in at least one of the drawing figures to the invention feature. Use of the device according to claim 9 for the production of moldings ( 20 ) in the form of structural components and / or surface components and / or visible carbon components on vehicles.

Images