Method for producing component from fibre composite material

Abstract

The invention relates to a method for producing a component from a fibre composite material, comprising the following steps: introducing fibres (1) impregnated with a matrix onto an inner mould (7) of a mould space formed between the inner mould (7) and an outer mould (8); introducing a separation membrane (14a) onto the fibers (1) impregnated with the matrix, thereby forming a cavity (15) between the outer mold (8) and the separation membrane (14a) extending along a side surface (14) of the outer mold (8); supplying heat transfer oil to the cavity (15) at a pressure greater than the ambient pressure such that the heat transfer oil acts on the separation membrane (14a) at the pressure; the heat transfer oil is heated above the glass transition temperature of the matrix, and the heat transfer oil is cooled below the glass transition temperature of the matrix, where the pressure of the heat transfer oil acting on the separation membrane (14a) remains substantially constant at least during cooling below the glass transition temperature.

Description

Divisional Application Instructions

[0001] This application is a divisional application of an invention patent application with an application date of August 18, 2020, application number 202080059516.7, and invention name “Method for producing components from fiber composite materials”. Technical Field

[0002] The invention relates to a method for producing a component from a fiber composite material, comprising the step of introducing fibers impregnated with a matrix onto an inner mold of a mold space formed between an inner mold and an outer mold. Background Art

[0003] Organic sheets belonging to the fiber composite materials are known in the prior art and are used primarily in aircraft, ship and automobile construction in order to achieve significantly lighter components and comparable or even improved stiffness compared to conventional materials. Such organic sheets usually have a fiber woven fabric or laid fiber web embedded in a thermoplastic matrix and, as a fiber matrix semi-finished product, usually glass, aramid or carbon as fiber material. Since the organic sheets can be thermoformed in a simple manner with the aid of known metal processing methods, the processing times are shorter compared to conventional thermosetting fiber composite materials.

[0004] Typically, such organosheets are used in the field of aircraft, ship or vehicle construction in order to prefabricate components individually from fiber composite materials and to assemble them in a subsequent final assembly step. The components are therefore usually formed in a press by means of an inner mold and an outer mold, wherein the mold space between the inner mold and the outer mold corresponds to the component to be molded.

[0005] When producing components by pressing, different pressure distributions of the pressing pressure on the component may occur due to very slight inhomogeneities and incomplete agreement of the inner and outer molds used. In areas where lower pressing pressures are present during production, the stability of the finished component is generally lower, since the material is able to form fewer internal bonds, also referred to as bridges, due to the lower pressure. The described problem is particularly pronounced for components with complex forms, i.e., components with multiple curvatures, for example, since in outer and inner molds with complex forms, unevenness increases and agreement between the inner and outer molds decreases due to lower manufacturing tolerances when producing the inner and outer molds. Summary of the invention

[0006] Starting from this, the object of the present invention is to provide a method by means of which components having high strength and complex forms can be produced in a particularly simple manner from fiber composite materials.

[0007] Therefore, the present invention relates to a method for manufacturing a component from a fiber composite material, comprising the following steps: introducing fibers impregnated with a matrix into an inner mold of a mold space formed between an inner mold and an outer mold, introducing a separation membrane onto the fibers impregnated with the matrix so that a cavity extending along the side surface of the outer mold is formed between the outer mold and the separation membrane, supplying thermal oil into the cavity at a pressure greater than the ambient pressure so that the thermal oil acts on the separation membrane at this pressure, heating the thermal oil to a temperature above the glass transition temperature of the matrix, and cooling the thermal oil to a temperature below the glass transition temperature of the matrix, wherein at least during the cooling to below the glass transition temperature, the pressure of the thermal oil on the separation membrane remains substantially constant.

[0008] Compared to forming methods with the aid of presses known from the prior art, such as, for example, C-frame presses comprising a fixed inner die and an outer die movable only in the vertical direction for generating a pressing pressure having only a vertical component, the proposed method is characterized in that, since the pressing pressure of the heat-conducting oil on the separation membrane and thus on the fibers impregnated with the matrix is ​​in the normal direction of the separation membrane, it also acts on every point of the separation membrane in the normal direction of the component to be obtained or the fibers impregnated with the matrix. By using heat-conducting oil in the cavity formed between the separation membrane and the outer die, the pressing pressure on the matrix is ​​therefore independent of any inhomogeneities of the outer die and / or the inner die. In contrast to known presses, the pressing or consolidation pressure required for forming is not generated by the press or is only partially generated by the press, but is completely or substantially generated by the heat-conducting oil.

[0009] By means of the proposed heating of the heat transfer oil to above the glass transition temperature of the matrix and the subsequent cooling of the heat transfer oil to below the glass transition temperature of the matrix, wherein the pressure of the heat transfer oil on the separation membrane remains substantially constant at least during the cooling to below the glass transition temperature, it is ensured that the component obtained becomes particularly stable and has an improved structure and a high breaking strength. In particular, by means of the proposed method, components with an internal bond content of >98% are obtained. Within the meaning of the present invention, maintaining a constant pressure means that the pressure of the heat transfer oil is preferably the same during the cooling phase. Maintaining a substantially constant pressure preferably means that the pressure changes by no more than + / -5% during the cooling phase.

[0010] The proposed method thus makes it possible to form a particularly stable component under pressure and temperature from fibers impregnated with a matrix in a particularly simple manner, since, due to the uniform pressure distribution during production, many bridges can be formed in the material of the fibers impregnated with the matrix. Components produced in this way are therefore particularly suitable for aircraft, ships and / or vehicles. Starting from the basic concept of using heat transfer oil as pressure and heating medium in the cavity between the outer mold and the separation membrane and keeping the pressure of the heat transfer oil substantially constant at least during cooling to below the glass transition temperature, an equal consolidation pressure can be achieved over the entire separation membrane, bridges can be forced to form in the material in a positive manner, and a very stable component can be produced.

[0011] In general, the inner and outer moulds can have any shape, in particular the negative shape of the component to be obtained, such as cylindrical and / or semicircular or semicircular in cross section, flat, with single or multiple curvatures and / or arches. The method can be implemented using a press, wherein the inner mould constitutes a lower die and the outer mould constitutes an upper die. More preferably, the inner and outer moulds resting on each other at their edges are closed and / or rest on each other in a pressure-tight and / or sealed manner so as to contact at their edges. In this case, the method preferably includes a further step of positioning the outer mould on the inner mould so that the outer and inner moulds rest on each other in a sealed manner at their edges to form a mould space.

[0012] Although the method can generally be implemented with any fiber impregnated with a matrix, these fibers are preferably designed as glass fibers, polyaramid fibers and / or carbon fibers. Most particularly preferably, the fibers are impregnated with a thermoplastic matrix or impregnated with a thermoplastic matrix. In particular, the fibers impregnated with a matrix are designed as fiber matrix semi-finished products, fiber composite materials and / or organic sheets, which terms are sometimes used synonymously in the context of the present invention. The fibers impregnated with a matrix are preferably designed as fibers impregnated with a thermoplastic matrix and / or as glass fiber reinforced aluminum, also called GLARE, as a hybrid material. Typically, glass fiber reinforced aluminum has many layers, each layer is only a few tenths of a millimeter thick, and is alternately composed of aluminum and glass fiber laminates, such as glass fiber reinforced plastic materials.

[0013] More preferably, the fiber impregnated with the matrix can be configured as a laid fiber net or a woven fabric, wherein the reinforcing fibers are embedded in a plastic matrix. Laid scrim can also be provided as fiber, particularly in the form of a uniaxial or unidirectional laid scrim, which can be obtained by fixing a strand of parallel wires, in the form of a biaxial laid scrim, wherein two strands of parallel wires are fixed in the direction of two axes, or in the form of a multiaxial laid scrim, wherein multiple strands of parallel wires are fixed in the direction of different axes. Compared with woven fabrics, laid scrims are characterized in that they bring greater intensity by omitting the inevitable ups and downs in woven fabrics. In addition, woven fabrics can comprise a variety of tissue types, such as plain weave or twill weave.

[0014] The fibers impregnated with the matrix may comprise so-called prepreg materials and / or may be formed as tapes. Preferably, the fibers impregnated with the matrix are provided in the form of a continuous material. The matrix may be an epoxy resin or a thermoplastic matrix and a mixture thereof. For example, the matrix may comprise polyphenylene sulfide or polyetherketone, such as polyaryletherketone (PAEK) or polyetheretherketone (PEEK), as a thermoplastic polymer. The prepreg material preferably has a thickness of 50 μm to 200 μm, for example about 180 μm, wherein the carbon fibers contained therein preferably have a thickness of 0.1 μm to 20 μm, for example 6 μm to 9 μm.

[0015] As already mentioned, during this method, the temperature of the heat-conducting oil is increased to a glass transition temperature higher than the substrate. Within the meaning of the present invention, the glass transition temperature Tg is a gradual and reversible transition that occurs during temperature increase or heating, from a hard and relatively brittle state to a viscous or rubbery state in the amorphous region of the substrate. The glass transition temperature of the substrate can be measured by dynamic differential calorimetry, which is a thermal analysis method for measuring the amount of heat output or absorbed when the substrate is heated or cooled. The glass transition temperature Tg of the substrate can be determined according to, for example, DIN 51007 standards.

[0016] More preferably, during the method, the temperature of the heat transfer oil is heated to a temperature above the melting point of the matrix. The melting point of the matrix is ​​preferably the temperature at which the matrix becomes very soft and is no longer dimensionally stable, i.e. can no longer return to its original shape. Preferably, the temperature of the heat transfer oil is at least 10°C, 20°C, 50°C, 100°C or 200°C higher than the melting point of the matrix.

[0017] The glass transition temperature and melting point of the matrix depend on the chemical composition of the matrix. In polyetherketones, the variable ratio of ether and carbon groups determines, among other things, the level of physical properties, such as the glass transition temperature and melting point. In polyetheretherketone (PEEK), the melting point is about 335°C and the glass transition temperature is about 143°C. In polyaryletherketone (PAEK), the melting point is about 373°C and the glass transition temperature is about 152°C. However, the level of the glass transition temperature and the melting point can vary depending on the production method and the exact composition of the plastic material.

[0018] When the heat transfer oil is supplied to the cavity at a pressure higher than the ambient pressure, the pressure of the heat transfer oil on the separation membrane is preferably at least 1 bar, 2 bar, 5 bar or 10 bar greater than the ambient pressure. More preferably, the pressure of the heat transfer oil on the separation membrane can be increased to a pressure that is preferably at least 5 bar, 10 bar, 20 bar, 30 bar or 40 bar greater than the ambient pressure. More preferably, the pressure can also be kept constant while the heat transfer oil is heated to a temperature higher than the glass transition temperature of the matrix.

[0019] According to another preferred improvement, the heating rate during heating of the thermal oil is higher than the cooling rate during cooling of the thermal oil. The heating rate or cooling rate indicates the rate at which the temperature of the thermal oil changes. Slow cooling can preferably result in more bridges being formed in the material and the component becoming particularly stable. Rapid heating in particular results in the production process not being unnecessarily prolonged. Preferably, the heating rate of the thermal oil is 20°C / minute and the cooling rate is 10°C / minute. More preferably, the heating rate of the thermal oil is 15°C / minute and the cooling rate is 5°C / minute. A heating rate of 30°C / minute and a cooling rate of 20°C / minute for the thermal oil are also possible.

[0020] As already mentioned, the method provides heating and cooling of the thermal oil. Between these steps and according to a preferred progression, the method comprises a step of maintaining the temperature of the thermal oil above the glass transition temperature of the substrate for at least 10 minutes, preferably at least 20 minutes, more preferably at least 40 minutes. "Maintaining temperature" means in particular that the temperature does not change during the maintenance phase. This preferably means that the temperature does not vary by more than + / -5% during the maintenance phase. More preferably, the temperature during the maintenance phase is not only above the glass transition temperature of the substrate, but also above the melting point of the substrate. More preferably, the temperature of the thermal oil is maintained above the melting point of the substrate for at least 10 minutes, preferably at least 20 minutes, more preferably at least 40 minutes. Preferably, the temperature of the thermal oil is maintained at at least 10°C, 20°C, 50°C, 100°C or 200°C higher than the melting point of the substrate.

[0021] Therefore, the temperature curve for producing the component preferably includes three stages: a heating stage, a maintenance stage and a cooling stage. When the temperature curve is represented on a graph, i.e. when the temperature of the thermal oil is plotted against time, the temperature curve can be trapezoidal. This means that the heating stage and the cooling stage require a certain length of time, and preferably, the thermal oil is not heated or cooled instantaneously or suddenly. Preferably, the length of the heating stage is 20 minutes, 30 minutes, 40 minutes or 60 minutes. More preferably, the length of the cooling stage is 20 minutes, 30 minutes, 40 minutes, 60 minutes, 80 minutes or 120 minutes, wherein the cooling stage is preferably longer than the heating stage.

[0022] As already mentioned, the method comprises the step of cooling the heat transfer oil to below the glass transition temperature of the substrate. Preferably, the temperature of the heat transfer oil after cooling is at least 10°C, 20°C, 50°C or 100°C below the glass transition temperature of the substrate. In particular, the temperature after cooling is substantially room temperature, i.e. in the range of 15 to 35°C.

[0023] According to another preferred development, the method comprises the step of heating the thermal oil to a temperature of ≥250° C., ≥300° C. or ≥400° C. and cooling the thermal oil to a temperature of ≤80° C., ≤100° C., ≤150° C. or ≤200° C. Preferably, the temperature of the thermal oil is selected depending on the matrix used and its glass transition temperature and melting point. More preferably, the thermal oil is maintained at a temperature of ≥250° C., ≥300° C. or ≥400° C. during the maintenance phase. Preferably, the thermal oil is supplied to the cavity at a temperature of 350° C. to 410° C. and the thermal oil is cooled to 30° C.

[0024] During the production of the component, preferably not only the temperature of the heat-conducting oil is changed, but also the pressure that the heat-conducting oil produces on the separation membrane is changed. According to a preferred development, the method includes a step of increasing the pressure of the heat-conducting oil on the separation membrane to ≥3 bar, ≥5 bar or ≥10 bar before, during and / or after being heated to a temperature higher than the glass transition temperature of the substrate. Preferably, the pressure of the heat-conducting oil is increased during the heating phase of the heat-conducting oil. The pressure can be increased before reaching the glass transition temperature, when reaching the glass transition temperature or after exceeding the glass transition temperature. Particularly preferably, the pressure of the heat-conducting oil is increased in the maintenance phase of the temperature. This preferably means that the pressure of the heat-conducting oil is particularly preferably increased after exceeding the glass transition temperature of the substrate.

[0025] The method may also include a step of maintaining the pressure of the heat transfer oil on the separation membrane at ≥3 bar, ≥5 bar or ≥10 bar for at least 80 minutes, preferably at least 120 minutes, more preferably at least 180 minutes. In particular, the pressure remains constant during this maintenance phase, i.e., its value does not vary within + / -5%, for example.

[0026] According to another preferred development, the method comprises a step of reducing the pressure of the heat transfer oil on the separation membrane substantially to ambient pressure after cooling the heat transfer oil below the glass transition temperature of the matrix. In particular, the pressure of the heat transfer oil can be reduced after a cooling phase of the heat transfer oil.

[0027] Similar to the temperature curve, the pressure curve preferably includes three stages, a pressure increase stage, a pressure maintenance stage and a pressure reduction stage. When the pressure is plotted on a graph relative to time, the pressure curve may be trapezoidal. Alternatively, the pressure curve may be almost at right angles, i.e. may include almost instantaneous pressure increases and pressure decreases.

[0028] Preferably, the rate of pressure increase when increasing the pressure of the heat transfer oil on the separation membrane corresponds substantially to the rate of pressure reduction when reducing the pressure of the heat transfer oil on the separation membrane. This means that the pressure build-up and release are substantially equally rapid. Specifically, this means that the rate of pressure increase is the same as the rate of pressure reduction or is the same as ±5% of the rate of pressure reduction.

[0029] More preferably, the pressure maintenance phase starts before or during the temperature maintenance phase. In other words, this preferably means that in the first case, while the thermal oil is still heated, the pressure is already substantially maintained at a pressure of ≥3 bar, ≥5 bar or ≥10 bar. In the second case, this preferably means that only in the temperature maintenance phase of the thermal oil at a temperature above the glass transition temperature of the matrix, the pressure is maintained substantially constant at a pressure of ≥3 bar, ≥5 bar or ≥10 bar.

[0030] According to another preferred development, the method comprises the steps of increasing the pressure of the thermal oil, reducing the pressure of the thermal oil, heating the thermal oil and cooling the thermal oil, wherein the pressure of the thermal oil on the separation membrane can be changed independently of the temperature of the thermal oil. In particular, the pressure can be changed independently of the temperature change, and the temperature can be changed independently of the pressure change. In other words, this preferably means that the pressure of the thermal oil does not increase due to the thermal oil being heated, or the pressure does not decrease due to the thermal oil being cooled.

[0031] According to another preferred configuration, the method includes, in particular, before introducing the fibers impregnated with the matrix, the step of introducing the stringer, frame and / or thickening into the recess of the inner mold. The stringer, frame and / or thickening can be a local reinforcement, such as a window, door and / or hatch opening for a vehicle, a ship or an aircraft, and / or a structural support that can be incorporated by means of the proposed method steps when producing a molded part. By incorporating the stringer, frame and / or thickening, the component can adopt any complex shape. When the fibers impregnated with the matrix are melted by supplying heat-conducting oil to the cavity at a temperature higher than the melting point of the matrix, the connecting contact surface of the stringer, frame and / or thickening is melted and connected to the fiber composite material in this way. The recess is preferably formed by, for example, a milling process so that when the stringer, frame and / or thickening are placed in the recess, it is flush with the side surface of the inner mold. The stringer, frame and / or thickening are preferably inserted into the recess as a prefabricated consolidated component.

[0032] According to a preferred development, the method comprises the step of cooling the inner mold to a temperature of ≥150° C., ≥200° C. or ≥250° C. or, after the aforementioned step, cooling the inner mold in the region of the longitudinal beams, frames and / or thickened portions to a temperature of ≤150° C., ≤200° C. or ≤250° C. Preferably, for this purpose, a plurality of supply ducts are provided in the region of the longitudinal beams, frames and / or thickened portions, which supply ducts extend axially through the inner mold and are arranged around the recess. This ensures that the longitudinal beams, frames and / or thickened portions arranged in the recesses are indeed melted onto the associated connecting contact surface due to the heated thermal oil, but the remainder of the longitudinal beams, frames and / or thickened portions remains below the softening temperature.

[0033] With regard to the component to be formed, according to a preferred development, the method is carried out using a press having an inner mold and an outer mold, wherein the inner mold and / or the outer mold are designed to mold an aircraft component, a ship component or a vehicle component. In general, the inner mold and the outer mold can have any shape, wherein the inner mold and the outer mold are preferably designed to produce a component of an aircraft, a ship or a vehicle. Furthermore, the component can be a rotor blade of an aircraft or a wind turbine.

[0034] According to a preferred development, a press, in particular a C-frame press, is provided with an inner mould and an outer mould, and / or after the introduction of the separating film, the method comprises the step of tensioning the inner mould and the outer mould relative to each other until a mould space is formed. The outer mould and the inner mould are preferably designed such that after tensioning the mould space is pressure-tight. The press preferably comprises a press frame, in particular a C-frame, which comprises an upper horizontal C-leg, a lower horizontal C-leg and a vertical C-shaped base, which interconnects the upper C-leg and the lower C-leg.

[0035] Preferably, via a press cylinder, the inner mold is supported as a lower mold in a fixed manner on the lower horizontal C-shaped leg, and the outer mold is supported as an upper mold on the upper C-shaped leg, so that by actuating the press cylinder, the inner mold and the outer mold can be tensioned relative to each other until a mold cavity is formed. The C-shaped frame is preferably designed as a frame structure, and a plurality of C-shaped, interconnected press frames can be arranged one after another in the longitudinal direction. The individual press frames are preferably connected to each other by clamping members. In addition to the above-mentioned downstroke press in which the press cylinder is supported on the upper C-shaped leg, the press can also have an upstroke structure so that the inner mold can be tensioned relative to the outer mold arranged on the upper C-shaped leg by the press cylinder.

[0036] According to a preferred development, the fibers impregnated with the matrix comprise a preconsolidated semi-finished shell and / or a preconsolidated individual layer. In particular, the fibers impregnated with the thermoplastic matrix can also comprise a fiber woven fabric and / or a laid fiber web embedded in the thermoplastic matrix. In the woven fabric and the laid web, the fibers can extend at right angles to each other in order to define mechanical properties such as rigidity, strength and / or thermal expansion in an improved manner compared to materials known from the prior art, such as metal sheets.

[0037] Most particularly preferably, the same thermal oil is used for heating, i.e. when supplying the thermal oil to the cavity at a temperature above the melting point of the matrix, and for the subsequent cooling. In other words, the thermal oil found in the cavity is preferably cooled during the pumping process and supplied to the cavity again, while the thermal oil continues to act on the separation membrane at a pressure above the ambient pressure.

[0038] According to a preferred development, the method comprises a step of preheating the outer mould and / or the inner mould to a base temperature, in particular before the introduction of the fibres impregnated with the matrix. To this end, heating and / or cooling ducts can be provided in the outer mould and / or the inner mould for temperature control of the relevant mould before and / or during curing. The heating ducts and / or cooling ducts preferably extend at regular intervals in the axial direction and / or so as to be distributed over the entire side surface of the relevant mould. In order to supply the cavity with heat-conducting oil, preferably a supply channel for the heat-conducting oil is provided, which extends through the outer mould in the radial direction.

[0039] According to a further preferred configuration, the method comprises the step of applying negative pressure to the side surface of the inner mould. Preferably, the inner mould is provided with a plurality of negative pressure pipes at regular intervals along the side, the negative pressure pipes extending through the lower mould in radial direction and / or connected to a vacuum pump, by means of which negative pressure can be generated. In a similar manner, a heating and / or cooling device can be provided in order to preheat or cool the outer mould and / or the inner mould to a base temperature by means of the heating and / or cooling pipes.

[0040] In general, there are various options for configuring the inner and / or outer mold. According to a particularly preferred development, the inner and / or outer mold is made of invar. Invar is an iron-nickel alloy with an extremely low coefficient of thermal expansion, which means that the inner and / or outer mold made of this material is characterized by an extremely low expansion due to temperature changes caused by the thermal oil.

[0041] Since the pressure is greater than the ambient pressure both when the heat transfer oil is heated to a temperature above the glass transition temperature of the matrix and when the heat transfer oil is cooled to a temperature below the glass transition temperature of the matrix, there are preferably no pressure-free phases during the formation. The fibers, in particular, impregnated with the thermoplastic matrix, preferably have a thickness comparable to the thickness of the cavity, so that the heat transfer oil, due to its significantly higher heat capacity, is sufficient to initiate a melting process for the formation of the fibers, in particular, impregnated with the thermoplastic matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Hereinafter, the present invention will be described in more detail based on preferred embodiments in conjunction with the accompanying drawings, in which:

[0043] Figure 1 is a schematic perspective view of an apparatus for carrying out a method for producing a component from a fiber composite material according to one embodiment of the present invention,

[0044] Figure 2 yes Figure 1 A schematic cross-sectional view of a detail of the device shown, including an inner mold and an outer mold,

[0045] Figure 3 shows an exemplary pressure and temperature curve of a method according to an embodiment of the present invention,

[0046] Figure 4 shows an exemplary pressure and temperature profile for a method according to another embodiment of the present invention, and

[0047] Figure 5 An exemplary pressure and temperature profile of a method according to yet another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0048] Figure 1 An apparatus in the form of a C-frame press is shown for carrying out a method for producing aircraft components from organic sheets as fiber composite materials. The C-frame press comprises a press frame designed as a C-frame 2, with an upper horizontal C-leg 3, a lower horizontal C-leg 4 and a vertical C-shaped base 5, which interconnects the upper C-leg 3 and the lower C-leg 4. The press is designed as a frame structure and comprises a plurality of mutually connected C-shaped press frames 6, which are arranged one behind the other in the longitudinal direction of the press.

[0049] A cylindrical inner mold 7 is arranged on the lower C-shaped leg 4. The inner mold 7 is convex, has a semicircular cross section and a cylindrical diameter of 6 m. In the longitudinal direction, the inner mold 7 extends between its ends with a cylindrical height of 15 m. Above the inner mold 7, an outer mold 8 is arranged that is consistent with the inner mold 7, that is, is also cylindrical and therefore concave. A plurality of cylinders 9 are supported on the upper C-shaped leg 3 and act on the outer mold 8. In this way, the outer mold 8 can be moved in the vertical direction in the manner of a crossbeam by the cylinders 9, that is, the mold space is opened in order to remove the component 1 from the device configured in this way, as indicated by the arrow 10.

[0050] References Figure 2 A schematic cross-sectional view of a detail of the inner mold 7 and the outer mold 8 is shown. Figure 1 When the outer mold 8 is at a certain distance from the inner mold 7, Figure 2 The separating agent 10 shown is sprayed onto the inner mold 7. Fibers impregnated with a thermoplastic matrix, in particular glass fibers, polyaramid fibers and / or carbon fibers, are then applied to the inner mold 7 in the form of a preconsolidated semi-finished shell or in the form of a preconsolidated individual layer, a so-called organic sheet, so that the organic sheet covers the entire side surface 12 of the cylindrical inner mold 7 up to the edge of the inner mold 7.

[0051] In an optional step, a release film 13 is applied as an anti-adhesive layer to the fibers 1 impregnated with the thermoplastic matrix. The release film 13 is in turn covered with a release film 14a made of metal, which likewise covers the entire side surface 12 of the inner mold 7.

[0052] like Figure 2 As shown, the outer mold 8 is then arranged above the inner mold 7 so that a cavity 15 is formed between the side surfaces 14 of the outer mold 8. In this way, the cavity extends over the entire side surface 14 of the outer mold 8 and has a substantially uniform thickness of 2 to 5 mm. The inner mold 7 and the outer mold 8 are made of Invar iron-nickel alloy and are configured so that when the outer mold 8 is Figure 2 When the cavity 15 is formed on the inner mold 7 as shown, the inner mold 7 and the outer mold 8 are closed or rest on each other in a sealed manner to contact at the edges of their respective side surfaces 12 , 14 .

[0053] The device comprises a thermal oil temperature control and pressure device 16, which is first designed to supply thermal oil to the cavity 15 so that a certain pressure is exerted on the separation membrane due to the thermal oil. The thermal oil can be freely distributed in the cavity 15 along the entire side surface 14 of the outer mold 8, and the pressure acts on each point of the separation membrane 14a in the normal direction of the side surface 12 of the inner mold 7 and in the extension direction of the fiber 1 impregnated with the thermoplastic matrix. In addition, the thermal oil can be temperature-controlled, i.e. heated and cooled, by the thermal oil temperature control and pressure device 16.

[0054] Therefore, the heat transfer oil is used as a pressure, heating and cooling medium to apply a constant consolidation pressure to the thermoplastic matrix-impregnated fibers over the entire separation membrane 14a and to allow targeted, consistent heating and targeted, consistent cooling of the thermoplastic matrix-impregnated fibers 1. Since its heat capacity is significantly higher than the heat capacity of the thermoplastic matrix-impregnated fibers 1, the melting process of the thermoplastic matrix-impregnated fibers 1 is achieved in this way with the help of the heat transfer oil.

[0055] The preparation method provides that the heat transfer oil is heated to a temperature above the glass transition temperature of the matrix and cooled to a temperature below the glass transition temperature of the matrix, wherein at least during the cooling to below the glass transition temperature, the pressure of the heat transfer oil on the separation membrane 14a remains substantially constant.

[0056] Figure 3 , 4 5 show three exemplary pressure curves 24 and temperature curves 25. The values ​​of the pressure and temperature of the heat transfer oil are plotted on the graph relative to time 26. In the present embodiment, the fiber 1 impregnated with the thermoplastic matrix is ​​a prepreg material. In the present embodiment, the plastic matrix is ​​made of polyaryletherketone (PAEK) and has a glass transition temperature of 147° C. and a melting point of 305° C. This fiber is a carbon fiber.

[0057] exist Figure 3 In the present invention, the heat transfer oil is heated from room temperature to 350°C. In this sense, the heat transfer oil is heated above the glass transition temperature and melting point of the matrix, with a heating rate of about 20°C / min. During the heating, the pressure of the heat transfer oil increases from ambient pressure to 18 bar. The pressure increase occurs essentially suddenly, i.e. within a very short time frame, so that Figure 3 A vertical rise in the pressure curve 24 is shown. The pressure increase of the thermal oil occurs at a temperature of 200° C. The pressure therefore increases when the temperature exceeds the glass transition temperature of 147° C. but has not yet reached the melting point of 305° C. After the pressure increase, the pressure is kept constant at 18 bar. During a pressure maintenance phase lasting 80 minutes, the thermal oil is further heated until a temperature of 350° C. is reached. This temperature is maintained for 12 minutes. Then a cooling phase of the thermal oil begins, in which the thermal oil is cooled at a cooling rate of 10° C. / minute. The thermal oil is cooled to 100° C., i.e. below the glass transition temperature of 147° C., while the pressure of the thermal oil is kept constant. At 100° C., the pressure of the thermal oil decreases, which occurs essentially as suddenly as the pressure increase. Figure 3 The pressure curve 24 in is therefore essentially rectangular, whereas the temperature curve 25 is trapezoidal.

[0058] exist Figure 4In the embodiment of the invention, the heat transfer oil is heated from 25°C to 365°C. The heat transfer oil is thus heated to above the glass transition temperature and the melting point of the matrix, with a heating rate of about 10°C / min. The heating phase lasts about 35 minutes. The temperature of the heat transfer oil is then maintained at 365°C for 40 minutes. During the entire heating phase, the pressure is about 2 bar. Only during the temperature maintenance phase does the pressure increase from 2 bar to 10 bar. This pressure increase occurs essentially suddenly, i.e. within a very short time frame, so Figure 4 A vertical rise in the pressure curve 24 is shown. As soon as the thermal oil has been held at 365° C. for 10 minutes, a pressure increase of the thermal oil occurs. After the pressure increase, the pressure is held constant at 20 bar. The temperature holding phase ends after 40 minutes and the thermal oil is cooled at a cooling rate of 3° C. / min. During the cooling, the pressure continues to remain constant at 20 bar. The thermal oil is cooled to 100° C., i.e. below the glass transition temperature of 147° C., while the pressure of the thermal oil remains constant. The cooling phase lasts about 85 minutes. The pressure of the thermal oil then drops to ambient pressure, which occurs essentially as suddenly as the pressure increase.

[0059] Figure 5 Another exemplary pressure and temperature curve is shown. Figure 4 , the heat transfer oil is heated from 25°C to 365°C, that is, heated to above the glass transition temperature and melting point of the matrix, with a heating rate of about 10°C / minute. The heating phase lasts for about 34 minutes. The temperature of the heat transfer oil is then maintained at 365°C for 50 minutes. At the beginning of heating, the pressure is 2 bar for the first 17 minutes. The pressure is then increased to 12 bar and maintained at this value. When the heat transfer oil reaches about 200°C, the pressure increases. The pressure increase does not occur suddenly, but lasts for about 10 minutes at a pressure increase rate of about 1 bar / minute. Therefore, before the maintenance phase at a temperature of 365°C, a maintenance phase of 12 bar pressure is reached. The temperature maintenance phase ends after 50 minutes, and the heat transfer oil is cooled to a temperature of 100°C at a cooling rate of 5°C / minute. During cooling, the pressure continues to remain constant at 12 bar. The cooling phase lasts for about 50 minutes. After this, that is, when about 100°C is reached, the pressure of the heat transfer oil decreases, which occurs basically suddenly.

[0060] Figure 2 Also shown are various supply ducts 18 extending radially through the outer mold 8, which are arranged to introduce heat transfer oil into the cavity 15 of the outer mold 8. For heating and cooling, axially extending heating and / or cooling ducts 19 are arranged in the inner mold 7 and the outer mold 8, so that the corresponding molds can be preheated, cooled and / or temperature-controlled. With the help of vacuum ducts 20 arranged in the inner mold 7 and extending radially through the inner mold 7, negative pressure can be applied to the side surface 12 of the inner mold 7.

[0061] like Figure 2As shown, a recess 21 is provided in the inner mold 7, into which a longitudinal beam 22 (left side) and a thickened portion 23 (right side) are inserted. A cooling duct 19 surrounding the relevant recess 21 is arranged adjacent to the corresponding recess 21. When the connecting contact surface of the longitudinal beam 22 or the thickened portion 23 is melted by the heat transfer oil and can be connected to the fiber 1 impregnated with the thermoplastic matrix, the cooling duct 19 arranged around the recess 21 is used to cool the longitudinal beam 22 or the thickened portion 23 so that they are kept below the softening temperature.

[0062] After the formed component 1 is solidified, the outer mold 8 can be raised, such as Figure 1 As shown, the molded component 1 is removed from the mold space formed by the inner mold 7 and the outer mold 8. Figure 1 As shown, the inner mold 7 and the outer mold 8 can be designed to mold half of an aircraft fuselage, but any other components, such as aircraft wings or aircraft propellers, can also be molded in a particularly simple manner with the aid of the proposed method and device.

[0063] The described embodiments are merely examples that can be modified and / or supplemented in various ways within the context of the claims. Any feature that has been described for a specific embodiment can be used alone or in combination with other features in any other embodiment. Any feature that has been described for an embodiment in a specific category can also be used in a corresponding manner in an embodiment in another category.

[0064] Reference numerals list A member, a fiber 1 impregnated with a matrix; C-shaped frame 2; Upper C-shaped leg 3; Lower C-shaped leg 4; C-shaped base 5; Press frame 6; Inner mold 7; Outer mold 8; Press cylinder 9; Arrow 10; Separating agent 11; (Inner mold) side surface 12; Separation film 13; Side surface 14 (of the outer mold); Separation membrane 14a; Cavity 15; Thermal oil temperature control and pressure equipment 16; Supply pipeline 18; Heating / cooling pipe 19; Vacuum pipe 20; recess 21; Stringer 22; Thickened portion 23; Pressure curve 24; Temperature curve 25; Timeline 26.

Claims

1. A method for producing a component from a fiber composite material, comprising the following steps: introducing the fibers (1) impregnated with the matrix into the inner mold (7) in the mold space formed between the inner mold (7) and the outer mold (8); introducing a separation membrane (14a) onto the fiber (1) impregnated with the matrix, thereby forming a cavity (15) extending along the side surface (14) of the outer mold (8) between the outer mold (8) and the separation membrane (14a); supplying heat transfer oil to the cavity (15) at a pressure greater than the ambient pressure, so that the heat transfer oil acts on the separation membrane (14a) under the pressure; heating the thermal oil to a temperature above the glass transition temperature of the matrix, and The thermal oil is cooled to a temperature below the glass transition temperature of the matrix, wherein At least during the cooling period to below the glass transition temperature, the pressure of the heat transfer oil on the separation membrane (14a) remains substantially constant, The pressure of the heat transfer oil on the separation membrane (14a) remains substantially constant during a pressure maintenance phase, wherein the pressure maintenance phase starts before or during a temperature maintenance phase, wherein during the temperature maintenance phase, the temperature variation does not exceed ±5%; and wherein substantially constant pressure means that the pressure variation does not exceed ±5%. 2 . The method according to claim 1 , wherein a heating rate during heating of the thermal oil is higher than a cooling rate during cooling of the thermal oil.

3. The method according to claim 1, comprising the steps of: The temperature of the thermal oil is maintained above the glass transition temperature of the matrix for at least 10 minutes.

4. The method according to claim 3, comprising the steps of: The temperature of the thermal oil is maintained above the glass transition temperature of the matrix for at least 20 minutes.

5. The method according to claim 3, comprising the steps of: The temperature of the thermal oil is maintained above the glass transition temperature of the matrix for at least 40 minutes.

6. The method according to any one of claims 1 to 3, wherein: The temperature profile (25) for producing the component comprises a heating phase, the holding phase and a cooling phase, and / or wherein: The pressure curve (24) used to manufacture the component includes a pressure increase phase, a pressure maintenance phase and a pressure reduction phase.

7. The method according to any one of claims 1 to 3, wherein the pressure maintenance stage lasts until the thermal oil cools down to ≤100°C.

8. The method according to any one of claims 1 to 3, comprising the following steps: Heating the heat transfer oil to a temperature of ≥250°C, ≥300°C or ≥400°C, and cooling the heat transfer oil to a temperature of ≤80°C, ≤100°C, ≤150°C or ≤200°C; and / or Before, during and / or after heating to above the glass transition temperature of the matrix, the pressure of the heat transfer oil on the separation membrane (14a) is increased to ≥3 bar, ≥5 bar or ≥10 bar.

9. The method according to claims 1 to 3, comprising the steps of: Maintaining the pressure of the heat transfer oil on the separation membrane (14a) at ≥3 bar, ≥5 bar or ≥10 bar for at least 80 minutes; and / or After the heat transfer oil is cooled to below the glass transition temperature of the matrix, the pressure of the heat transfer oil on the separation membrane (14a) is reduced substantially to ambient pressure.

10. The method according to claim 9, comprising the steps of: The pressure of the heat transfer oil on the separation membrane (14a) is maintained at ≥3 bar, ≥5 bar or ≥10 bar for at least 120 minutes.

11. The method according to claim 9, comprising the steps of: The pressure of the heat transfer oil on the separation membrane (14a) is maintained at ≥3 bar, ≥5 bar or ≥10 bar for at least 180 minutes.

12. The method according to claim 9, wherein a pressure increase rate when increasing the pressure of the heat transfer oil on the separation membrane (14a) substantially corresponds to a pressure decrease rate when decreasing the pressure of the heat transfer oil on the separation membrane (14a).

13. The method according to claim 12, wherein the method comprises the following steps: The pressure of the heat transfer oil is increased, the pressure of the heat transfer oil is reduced, the heat transfer oil is heated, and the heat transfer oil is cooled, wherein the pressure of the heat transfer oil on the separation membrane (14a) can be changed independently of the temperature of the heat transfer oil.

14. The method according to any one of claims 1 to 3, comprising the steps of: The outer mould (8) and / or the inner mould (7) are preheated to a base temperature before the fibres (1) impregnated with the matrix are introduced, and / or Negative pressure is applied to the side surface (12) of the inner mold (7).

15. The method according to any one of the preceding claims 1 to 3, comprising the steps of: Before the fibers (1) impregnated with the matrix are introduced, longitudinal beams (22), frames and / or thickenings (23) are introduced into recesses of the inner mold (7).

16. Method according to any one of claims 1 to 3, comprising the step of cooling the inner mould (7) to a temperature ≥ 150°C, ≥ 200°C or ≥ 250°C.

17. The method according to claim 15, comprising the step of cooling the inner mould (7) in the region of the longitudinal beams (22), the frame and / or the thickened portion (23) to a temperature of ≤150°C, ≤200°C or ≤250°C.

18. The method according to any one of claims 1 to 3, comprising a press having the inner mold (7) and the outer mold (8), and / or a step of tensioning the inner mold (7) and the outer mold (8) relative to each other until the cavity (15) is formed after the introduction of the separation membrane (14a).

19. The method according to claim 18, wherein the press is a C-frame press (6).

20. The method according to any one of claims 1 to 3, wherein the fibers (1) impregnated with a matrix comprise a pre-consolidated semi-finished shell and / or pre-consolidated individual layers.

21. The method according to any one of claims 1 to 3, comprising a press having the inner mold (7) and the outer mold (8), wherein the inner mold (7) and / or the outer mold (8) are designed to mold aircraft components, marine components or vehicle components.

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