DE102009039116A1 - Fiber-reinforced plastic component manufacturing device, has molding tool including connection parts with unit for injecting plastic matrix and pressurizing hollow chambers, and region of molding parts directly exposed to ambient pressure - Google Patents

Abstract

The device has hollow shaped molding parts (11a, 11b) forming a set of cavities (16), and made of metal. A textile fiber semi-manufactured product (13) is inserted between the cavities, and a molding tool (10) includes connection parts (14, 17) with a unit for injecting a plastic matrix (15) and unit for pressurizing hollow chambers (18a, 8b). The molding parts include a set of upper surface parts (19a, 19b), and a region of the molding parts is directly exposed to ambient pressure. One of the molding parts is connected with a tool upper (21) and/or a tool lower part (22). An independent claim is also included for a method for manufacturing a fiber-reinforced plastic component by injection of plastic matrix in a molding tool.

Description

The invention relates to a device for producing fiber-reinforced plastic components by injection of a resin mixture into a mold with two cavity forming moldings, between which a semi-finished textile fiber product is inserted according to the preamble of claim 1. Furthermore, the invention also relates to a method for producing fiber-reinforced plastic components by means the device according to the invention.

Such a method is known as a so-called resin flow molding method, also known as resin transfer molding (RTM).

The fiber-reinforced plastics produced by this process are widely used in the automotive industry and play due to the low weight with high strength in lightweight an ever-increasing role.

For the production of such fiber-reinforced plastic components textile semifinished products are used as Ausgangsmaterialein in a known manner, which are formed by at least one scrim, fabric or a knit fabric, ie by a textile fabric. Such textile semifinished fiber products are placed in the cavity of a molding tool, which is a negative mold of the plastic component to be produced, and injected a resin mixture as a plastic matrix in the cavity. After curing of the resin mixture, the finished plastic component can be removed from the mold.

As a plastic matrix, a thermoset or a thermoplastic can be used, wherein in each case a mixed with an activator starting material is converted into a low-viscosity or flowable and reactive starting mixture, which is then injected into the cavity.

A mold for carrying out such a known RTM process with two cavity-forming moldings is shown in a schematic representation 1 , Such an RTM mold 1 consists of two moldings 2a and 2 B , where the subform 2a on a tool base 3a is arranged and the upper mold 2 B with a tool shell 3b connected is. These two tool parts 3a and 3b are arranged movable against each other, so that the mold 1 closed and can be opened. In the opened state, a dry textile semifinished fiber product 4 inserted and then the mold 1 under formation of a cavity 5 closed. The the cavity 5 forming surfaces of the two moldings 2a and 2 B correspond to the respective contour of the surface of the plastic component to be produced. In the in the 1 illustrated state of the mold 1 the edges not shown are close to each other, so that the distance between the two surfaces forming the cavity of the two mold parts 2a and 2 B the target wall thickness of the plastic component to be produced corresponds.

In this in 1 shown state of the mold 1 is a non-illustrated connection under an injection pressure of, for example, 10 bar, the plastic matrix 6 injected into the cavity to form a fiber composite molding compound. In a final curing phase, the duration of which depends on the mold temperature, this fiber composite molding compound is brought to harden, so that in this case forms the dimensionally stable plastic component, which is then removed from the mold.

The pressure during the injection of the plastic matrix and during the holding pressure phase is so high in the cavity that the moldings are affected 2a and 2 B can deform. In order to minimize such deformation, these moldings 2a and 2 B made of metal, for example. Made of steel or aluminum with a correspondingly large value of the thickness. This massive design, due to the high requirements for sufficient dimensional stability, leads to a high weight of these moldings, which is why the kinematics of the mold must be adapted to this, so that a total of high investment costs. Even the production of other molded parts for producing a plastic component with a different contour causes high costs.

The object of the invention is therefore to provide an improved apparatus for the production of fiber-reinforced plastic components, which avoids the disadvantages mentioned above, ie in particular ensures a high dimensional stability and can be realized over the prior art with reduced investment costs.

This object is achieved by a device for producing fiber-reinforced plastic components having the features of patent claim 1.

In such a device, at least one of the two mold parts is hollow, wherein the hollow molded part has a connection with means for pressurizing its cavity. Preferably, both mold parts are hollow, each with a connection formed with means for pressurizing the cavity.

The pressurization of the hollow molding or the two hollow moldings can be carried out with a liquid and / or gaseous medium.

With this molding tool according to the invention with at least one hollow molded part, during the injection of the plastic matrix, a tool pressure can be built up as a back pressure to the injection pressure, with the result that due to this pressure compensation, no deformation of the cavity forming surface of the hollow molding takes place, since this pressure is global acts on the entire relevant area and not only punctually. Furthermore, results from such a structure of a molded article an enormous weight saving, with the result that the entire mold has to meet lower stability requirements, so that ultimately significant costs can be saved.

According to an advantageous embodiment of the invention, the two hollow moldings on exchangeable surface parts, which together form the cavity. Since these surface parts correspond with their surfaces of the contour of the respective surface of the plastic component to be produced, it is essential to produce this simple and inexpensive plastic components with different contours with this development of the invention. For a quick tool change is possible, the investment costs for the production of such tops are much lower than the production of solid moldings according to the prior art. Preferably, these exchangeable surface parts are made of metal, for example aluminum or steel.

Furthermore, according to a development of the invention, it is particularly advantageous if those regions of the hollow shaped parts which are directly exposed to the ambient pressure, which are therefore not involved in the formation of the cavity, have a sandwich structure for increasing the dimensional stability. This prevents that bulge during pressurization of the hollow moldings, these areas, whereby an exact pressure adjustment is made possible in the moldings.

An uncontrolled pressure variation in the hollow moldings is thus prevented.

Finally, according to an embodiment of the invention, the mold is formed with a flat and dimensionally stable upper tool part and a lower tool part, such that a molding is connected to the upper tool and the other with the lower tool part. This results in a tool similar to a pressing tool for closing and opening the cavity.

A method for producing a fiber-reinforced plastic component by means of the device according to the invention is given with the features of patent claim 8 or 9.

• – Einlegen eines textilen Faserhalbzeugs in das offene Formwerkzeug,
• – Schließen des Formwerkzeugs zur Bildung der Kavität,
• – Injizieren einer Kunststoffmatrix mit einem vorgegebenen Injektionsdruck über den Anschluss in die Kavität, wobei gleichzeitig das hohle Formteil bzw. die hohlen Formteile mit dem vorgegebenen Injektionsdruck beaufschlagt wird bzw. werden, und
• – Schließen des Anschlusses nach Abschluss der Injektion der Kunststoffmatrix, wobei der hohle Formteil bzw. die hohlen Formteile weiterhin mit dem vorgegebenen Injektionsdruck beaufschlagt wird bzw. werden.

After this, the following method steps are carried out according to claim 8:

• Inserting a semi-finished textile fiber into the open mold,
• Closing the mold to form the cavity,
• - Injecting a plastic matrix with a predetermined injection pressure through the connection in the cavity, wherein at the same time the hollow molding or the hollow moldings is acted upon with the predetermined injection pressure, and
• Closing the connection after completion of the injection of the plastic matrix, wherein the hollow molded part or the hollow molded parts continue to be subjected to the predetermined injection pressure.

With such a method, a high dimensional stability of the plastic component produced is achieved.

• – Einlegen eines textilen Faserhalbzeugs in das offene Formwerkzeug,
• – Schließen des Formwerkzeugs zur Bildung der Kavität,
• – Injizieren einer Kunststoffmatrix mit einem vorgegebenen Injektionsdruck über den Anschluss in die Kavität, wobei gleichzeitig das hohle Formteil bzw. die hohlen Formteile mit einem Druck beaufschlagt wird bzw. werden, der zwischen dem Atmosphärendruck und dem vorgegebenen Injektionsdruck der Kunststoffmatrix liegt, und
• – Schließen des Anschlusses nach Abschluss der Injektion der Kunststoffmatrix, wobei das hohle Formteil bzw. die hohlen Formteile mit einem Druck beaufschlagt wird bzw. werden, der dem vorgegebenen Injektionsdruck bzw. einem vorgegebenen Nennwert entspricht.

The method can also be carried out alternatively according to claim 9 with the following method steps:

• Inserting a semi-finished textile fiber into the open mold,
• Closing the mold to form the cavity,
• Injecting a plastic matrix having a predetermined injection pressure across the port into the cavity, while simultaneously pressurizing the hollow molding or the hollow mold parts to a pressure which is between the atmospheric pressure and the predetermined injection pressure of the plastic matrix, and
• - Closing of the terminal after completion of the injection of the plastic matrix, wherein the hollow molding or the hollow moldings is subjected to a pressure corresponding to the predetermined injection pressure or a predetermined nominal value.

By controlling the pressure curve during the injection of the plastic matrix into the cavity, the production process of the plastic component can be optimized. Since the injection of the plastic matrix occurs at a low balance pressure in the mold parts, the cavity is "inflated", i. H. the gap forming the cavity is slightly widened, which reduces the flow resistance of the plastic matrix, with the result that the injection process can be carried out faster, ie the complete filling of the cavity with the plastic matrix in a shorter period of time. Since after the mold filling the pressure in the moldings to the nominal value, for example, the injection pressure is increased, the excess material of the plastic matrix is pressed, so that thereby the target wall thickness is achieved.

The invention will now be described in detail by means of embodiments with reference to the accompanying figures. Show it:

1 a schematic representation of a mold according to the prior art,

2 a schematic representation of a mold as an embodiment of the invention, and

3 a schematic representation of a mold as a further embodiment of the invention.

The 1 shows a mold 1 according to the prior art and has already been described in the introduction to the description.

2 shows a mold 10 with moldings according to the invention, consisting of a mold bottom 11a on a lower level tool base 22 is arranged, and a mold top 11b That with a top level tool shell 21 connected is. These two tool parts 21 and 22 are movable against each other to the mold 10 open and close.

The two molded parts 11a and 11b are hollow, each with a cavity 18a and 18b formed and each consist of a back part 12a respectively. 12b , one each this back part 12a respectively. 12b opposite surface part 19a respectively. 19b and side panels 20 ,

The opposite surface parts 19a and 19b form a cavity 16 , in which a textile semi-finished fiber 13 is inserted. Im according to the 2 illustrated closed state of the mold 10 gets into this cavity 16 via a connection 14 a plastic matrix injected in the 2 schematically with an arrow 15 is shown. The means for injecting such a plastic matrix 15 are in the 2 not shown and include, for example, injection lines that lead to a mixing container with an injection system.

The connection 14 for injection of the plastic matrix 15 is opposite to both moldings 11a and 11b tightly executed. One in the direction of the flow front of the plastic matrix 15 arranged connection 23 in the same way close to the moldings 11a and 11b however, which is leaky from the environment and can be formed, for example, by a simple, open tube, excess material becomes the plastic matrix 15 removed.

The the cavity 16 forming surface parts 19a and 19b are formed flat with a surface contour corresponding to the contour of the plastic component to be produced.

The two cavities 18a and 18b the molded parts 11a and 11b are subjected to a pressure P and are therefore each via a pressure connection 17 connected to a pressure generator, not shown, wherein for pressurizing a liquid and / or gaseous medium can be used, so for example. Water, oil and gas, such as air, etc.

With such a pressurization of the cavities 18a and 18b by means of a pressure P, the plastic matrix is injected during the injection 15 into the cavity 16 built up a back pressure, causing a deformation of the surface parts 19a and 19b is prevented. This leads to a high dimensional stability of these surface parts 19a and 19b during the manufacturing process and consequently also to a correspondingly high compliance with the desired shape of the plastic component to be produced.

An exact pressure adjustment in the sense of a controlled process management is only possible if there are no uncontrolled buckling during the pressurization. Such bulges may occur in such areas of the moldings 11a and 11b arise directly exposed to the atmospheric pressure, such as the side panels 20 , In order to prevent or minimize such bulges in these areas as possible, these side panels 20 built in a sandwich structure. For this purpose, fiber composite materials with a core material, for example. Be used in honeycomb structure.

In the embodiment of the mold 10 to 2 are the moldings 11a and 11b with exchangeable surface parts 19a and 19b formed, which are made of metal, for example. Made of aluminum or steel. Thus, a tool change can be easily performed to produce a plastic component with a different contour. This is exemplified in 3 the one according to the structure of the mold after 2 corresponding mold 10 shows, but with surface parts 19a and 19b who after those after 2 have a different contour. Otherwise structure and function of the molds after 2 and 3 match the description of the shape tool 3 waived and to the above description of 2 directed.

A fiber-reinforced plastic component is used with the molds according to the 2 and 3 prepared in the following manner.

In the open state of the mold 10 First, a dry semi-finished fiber 13 inserted and the mold 10 closed. About the connection 14 becomes a resin mixture as a plastic matrix 15 with an injection pressure P _M into the cavity 16 injected and at the same time the internal pressure P in the cavities 18a and 18b the two moldings 11a and 11b adjusted to the injection pressure P _M , whereby due to the back pressure thereby constructed to the injection pressure P _M, a deformation of the surface parts 19a and 19b prevented, but at least minimized. After the mold filling the connection becomes 14 closed, with excess material over the port 23 Will get removed. During the subsequent curing phase, this internal pressure P is maintained. Finally, the finished plastic component from the open mold 10 be removed from the mold.

Alternatively, the injection of the plastic matrix 15 Also be accompanied by an internal pressure P, which is less than the injection pressure P _M , but higher than the ambient pressure. This will cause the cavity 16 under formation of a gap "inflated", causing the flow resistance of the plastic matrix 15 is lowered and thereby a faster backfilling of the cavity 16 is possible, ie that in a shorter time the entire cavity 16 with the material of the plastic matrix 15 is filled. Subsequently, in a Nachdruckphase the internal pressure P in the cavities 18a and 18b increased to the nominal value, that is, the injection pressure P _M or an overlying value, causing excess material from the cavity 16 is pressed to reach the target wall thickness of the plastic component to be produced. After the curing phase, the plastic part is removed from the mold.

The most significant advantages of the molding tool according to the invention consists in its low investment costs compared to a mold according to the prior art (see. 1 ), taking for a new mold cavity in the form of surface parts 19a and 19b only 20% of these investment costs are required. A role also plays the reduced weight. Further cost savings result from the faster tool change, since only the surface parts 19a and 19b need to be replaced. Finally, the cycle times for the production of plastic components can be reduced by the faster backfilling of the cavity, in particular if, during the injection of the plastic matrix into the cavity, the internal pressure in the cavities 18a and 18b the molded parts 11a and 11b is set lower than the injection pressure. By an appropriate pressure control or pressure control, an optimization of the entire manufacturing process can be achieved.

LIST OF REFERENCE NUMBERS

1

mold

2a

lower molding

2 B

upper molding

3a

lower tool base

3b

Upper tool lower part

4

textile semi-finished fiber

5

cavity

6

Plastic matrix

10

mold

11a

lower molding

11b

upper molding

12a

Back part of the molding 11a

12b

Back part of the molding 11b

13

textile semi-finished fiber

14

Connection for injection of the plastic matrix

15

Plastic matrix

16

cavity

17

Pressure connection for pressurizing the molded parts 11a . 11b

18a

Cavity of the molding 11a

18b

Cavity of the molding 11b

19a

Surface part of the molding 11a

19b

Surface part of the molding 11b

20

Side parts of the moldings 11a . 11b ,

21

Upper die

22

Tool part

Claims (9)

Device for producing fiber-reinforced plastic components by injection of a plastic matrix ( 15 ) in a mold ( 10 ) with two a cavity ( 16 ) forming moldings ( 11a . 11b ), between which a textile semi-finished fiber ( 13 ) and the mold ( 10 ) at least one connection ( 14 ) with means for injecting the plastic matrix ( 15 ), characterized in that - at least one molded part ( 11a . 11b ) is hollow, and - the hollow molded part ( 11a . 11b ) a connection ( 17 ) with means for pressurizing its cavity ( 18a . 18b ) having. Device according to claim 1, characterized in that - both molded parts ( 11a . 11b ) are hollow, and - the moldings ( 11a . 11b ) to form different cavities ( 16 ) each exchangeable surface parts ( 19a . 19b ) exhibit. Apparatus according to claim 1 or 2, characterized in that - the areas ( 20 ) of the hollow shaped parts ( 11a . 11b ), which is the ambient pressure directly are exposed to have a sandwich structure to increase the dimensional stability. Device according to one of the preceding claims, characterized in that the surface of the cavity ( 16 ) forming surface parts ( 19a . 19b ) of the molded parts ( 11a . 11b ) are formed of metal. Device according to one of the preceding claims, characterized in that the surface of the cavity ( 16 ) forming surfaces of the molded parts ( 11a . 11b ) correspond to the contour of the respective surface of the plastic component to be produced. Device according to one of the preceding claims, characterized in that the molding tool ( 10 ) a flat and dimensionally stable tool shell ( 21 ) and a tool lower part ( 22 ), and in each case a molded part ( 11a . 11b ) with the tool upper part ( 21 ) or the tool lower part ( 22 ) connected is. Device according to one of the preceding claims, characterized in that the hollow molded part ( 11a . 11b ) or the hollow moldings ( 11a . 11b ) are pressurized with a liquid and / or gaseous medium. Process for producing fiber-reinforced plastic components by means of the device according to one of the preceding claims, characterized in that - in the open mold ( 1 ) a textile semifinished fiber product ( 13 ), - the mold ( 10 ) for the formation of the cavity ( 16 ), - via the connector a plastic matrix ( 15 ) into the cavity ( 16 ) is injected with a predetermined injection pressure and at the same time the hollow molded part ( 11a . 11b ) or the hollow moldings ( 11a . 11b ) is / are applied to the predetermined injection pressure, and - after completion of the injection of the plastic matrix ( 15 ) the connection ( 14 ) is closed and the hollow molding ( 11a . 11b ) or the hollow moldings ( 11a . 11b ) is still applied to the predetermined injection pressure or be. Process for the production of fiber-reinforced plastic components by means of the device according to one of claims 1 to 7, characterized in that - in the open mold ( 10 ) a textile semifinished fiber product ( 13 ), - the mold ( 10 ) for the formation of the cavity ( 16 ), - via the connection ( 14 ) a plastic matrix ( 15 ) with a predetermined injection pressure into the cavity ( 16 ) and at the same time the hollow molded part ( 11a . 11b ) or the hollow moldings ( 11a . 11b ) is pressurized between the atmospheric pressure and the predetermined injection pressure of the plastic matrix ( 15 ), and - after completion of the injection of the plastic matrix ( 15 ) the connection ( 14 ) is closed and the hollow molding ( 11a . 11b ) or the hollow moldings ( 11a . 11b ) is applied to a pressure corresponding to a predetermined nominal pressure or the predetermined injection pressure.

Images