KR20200109371A - Extrusion apparatus and method for manufacturing carbon fiber reinforced plastic semi-finished products - Google Patents

Abstract

The present invention relates to an extrusion apparatus 100 for manufacturing a carbon fiber reinforced plastic semi-finished product, comprising a housing 1 having an inlet region 2 and an outlet region 3, wherein the housing 1 generates an electric field. It is characterized in that a device 4 is arranged for it. The invention also relates to a method for producing a carbon fiber reinforced plastic semi-finished product, wherein the following steps are carried out continuously: a) providing an extrusion apparatus 100 and a composite compound 10 according to the invention; b) introducing the composite compound 10 into the extrusion apparatus 100 through the inlet region 2 of the housing 1; c) generating an electric field; And d) discharging the resulting plastic semi-finished product, for further processing, through the exit area (3) of the housing (1).

Description

Extrusion apparatus and method for manufacturing carbon fiber reinforced plastic semi-finished products

The present invention relates to an extrusion apparatus and method for producing a carbon fiber reinforced plastic semi-finished product.

In order to improve the mechanical properties of plastic semi-finished products made using extrusion techniques, the compounds used are often reinforced with carbon fibers. However, the orientation of the introduced fibers is currently only affected by the flow phenomenon occurring during extrusion, through which an undecided distribution of fibers is established. This leads to irregularities in the mechanical properties of the extruded part. Also, other potentials of carbon fiber such as electrical conductivity and high thermal conductivity cannot be utilized.

Extrusion systems currently in use determine the flow of plasticized fiber-reinforced composite compounds through additionally introduced flow channels that affect fiber orientation as intended. However, the fibers can here only be oriented in a helical arrangement parallel to the profile plane or parallel to the tube axis in the case of tube extrusion. In addition, an undefined orientation of the fibers is created due to the different flow velocities in the center and edge regions of the flow region of the plasticized composite compound here, whereby a constant part quality cannot be guaranteed.

The publication "Method for Manufacturing Plastic Tubes for Heat Exchangers Containing Graphite Fillers" (DOI: http://dx.doi.org/10.4421/PAPDEOTT002961) discloses the production of plastic tubes with high thermal conductivity by extrusion. Where the orientation of the carbon fibers perpendicular to the flow direction is achieved by the use of special fillers and through the geometry of the flow channels in the extrusion tool.

Accordingly, it is an object of the present invention to overcome the drawbacks of the prior art and to provide a device capable of influencing the orientation of carbon fibers in a plastic semi-finished product as intended.

The object of the present invention is achieved by providing an extrusion apparatus for producing a carbon fiber reinforced plastic semi-finished product according to the features of the independent claims of the present application. Advantageous refinements of the device according to the invention appear in the dependent claims.

The subject of the invention relates to an extrusion apparatus 100 for manufacturing a carbon fiber reinforced plastic semi-finished product, consisting of a housing 1 comprising an inlet region 2 and an outlet region 3, wherein the housing 1 A device 4 for generating an electric field is arranged.

Particularly preferably, in the extrusion apparatus 100 according to the invention, the carbon fiber reinforced plastic semi-finished product is tubular or flat.

Preferably, in the extrusion device 100 according to the invention, the device 4 for generating an electric field comprises two electrodes 40, 41.

Further, preferably, in the extrusion apparatus 100 according to the invention, the electrodes 40, 41 are formed annularly or flat.

Particularly preferably, in the extrusion apparatus 100 according to the invention, the electrodes 40, 41 are arranged concentrically or parallel to each other, and an annular or flat gap between the electrodes 40, 41 Form 42.

Further, preferably, in the extrusion apparatus 100 according to the present invention, one electrode is an anode and the other electrode is a cathode.

In addition, preferably, in the extrusion device 100 according to the invention, the device 4 for generating an electric field is arranged in the outlet area 3 of the housing 1.

Preferably, in the extrusion apparatus 100 according to the invention, a push mandrel 5 is additionally arranged in the housing 1.

Particularly preferably, in the extrusion apparatus 100 according to the present invention, the push mandrel 5 is formed to be rotationally symmetric, and is arranged spaced apart from the housing 1, so that the inside of the housing and the push mandrel 5 are annularly formed. A gap 6 is formed.

Particularly preferably, in the extrusion apparatus 100, the push mandrel 5 extends from the inlet region 2 to the outlet region 3.

Further, preferably, in the extrusion apparatus 100 according to the invention, the housing 1 further comprises a mandrel holding tool 8 which is partially arranged inside the push mandrel 5.

Further, preferably, in the extrusion apparatus according to the invention, the mandrel holding tool 8 comprises an outlet 9 arranged inside the push mandrel 5 and extending to the outlet area 3 of the housing 1 do.

In addition, preferably, in the extrusion apparatus 100 according to the invention, the housing 1 further comprises at least one temperature sensor 7.

In addition, another subject of the present invention relates to a method for manufacturing a carbon fiber reinforced plastic semi-finished product,

a) providing an extrusion apparatus 100 and a composite compound 10 according to the present invention;

b) introducing the composite compound 10 into the extrusion apparatus 100 through the inlet region 2 of the housing 1;

c) generating an electric field;

d) discharging the resulting plastic semi-finished product, for further processing, through the exit area 3 of the housing 1

Is performed continuously.

Preferably, in the method according to the invention, the composite compound 10 is formed in an annular gap flow by a push mandrel 5 after step b).

In particular, preferably, in the method according to the invention, the melt of the composite compound 10 is uniformly temperature controlled by means of at least one temperature sensor 7.

Also, preferably, in the method according to the invention, before step d), support air 11 is guided into the extrusion device 100.

Preferably, in the sense of the present invention, the tubular plastic semi-finished product is a CFK tube.

In the sense of the present invention, a container that is at least partially closed is referred to as a housing, through which the flow in the extrusion device is affected.

Further, in the sense of the present invention, a voltage of at least 50 V is applied to the electrode of the device for generating an electric field. Those skilled in the art know that the electric field strength of the generated electric field depends on the applied current strength. Advantageously, by means of the electric field strength, the orientation of the carbon fibers inside the extrusion apparatus according to the invention can be controlled. One skilled in the art can determine the appropriate voltage and electric field strength by a few simple experiments to produce the desired orientation of the carbon fibers.

Further, in the meaning of the present invention, the carbon fiber reinforced plastic semi-finished product consists of a composite compound. The composite compound consists of high modulus carbon fibers present in the granulated compound by being fixed by a thermoplastic resin-based plastic matrix. In particular, plastics based on polytetrafluoroethylene (PTFE) are used as matrix substrates due to their thermal and chemical properties.

The advantage of using high modular carbon fiber is that it has good electrical conductivity in the fiber direction and also negative thermal expansion, in addition to high thermal conductivity and high specific strength and rigidity properties. The highest heat conduction property of 1200 W/m*K is the so-called "Ultra-High-Modulus" (UHM) special carbon fiber.

Unlike metallic materials whose thermal conduction is isotropic, the thermal conductivity of carbon fibers is generally strongly anisotropic, and is highest in the fiber direction. UHM-fibers are made on a polyacrylonitrile (50%) or pitch (>80%) basis due to their high carbon yield. The high coefficient of thermal conduction arises here due to special graphitization during the manufacturing process at temperatures up to 3000 °C. This increases the pre-orientation of the graphite plane in the fiber axis direction, resulting in a strong anisotropic material behavior by covalent crystal bonding. As a result, the thermal conductivity according to the degree of anisotropy in the transverse direction with respect to the fiber direction is at most 17 W/m*K. The thermal conductivity decreases with the fiber content in the composite. Thus, for example, in the case of a unidirectional laminate structure having a fiber volume of 60% and a plastic matrix of 40%, a thermal conductivity of more than 750 W/m*K may be implemented in the fiber direction.

An advantage in the extrusion apparatus according to the invention and the method according to the invention carried out by the method according to the invention is that by applying an electric voltage unit in the extrusion apparatus, an electric field is induced, and the carbon fiber is It can be arranged in the manner prescribed by the line of power. This allows for very high thermal conductivity of carbon fiber and high electrical conductivity in printed circuit boards through defined orientation with a high normal ratio to the profile plane or tube axis, as well as specific strength and stiffness properties as intended at the point of highest force introduction. Can be utilized.

It is also advantageous that the extrusion system known in the prior art can be improved in a simple manner by means of the extrusion apparatus according to the invention.

Also advantageously, the carbon fiber reinforced tubular plastic semi-finished products produced by the extrusion apparatus according to the invention and by the method according to the invention can be used for a wide range of applications. Possible fields of application are manufacturing and heavy industry, for example mechanical engineering, power plant technology, thermal engineering, automotive engineering, electrical engineering, chemical products, etc. Particularly in the field of thermal engineering, the intended orientation of highly thermally conductive carbon fibers is an efficient heat recovery and high demand for the 2020s and 2030s due to the 3rd EU core goal of "Climate Change and Sustainable Energy Management". Can be used in cooling systems.

The invention is explained in more detail by the accompanying drawings.
1 shows a longitudinal cross-sectional view of an embodiment of an extrusion apparatus according to the invention.
2 shows a perspective view of a partial section through the embodiment of FIG. 1.
3 shows a longitudinal sectional view of the extrusion device.
4 shows a perspective view of a partial section of a CFK tube.
5 shows a perspective view through the embodiment of FIG. 4.
6 shows a comparison of the thermal conductivity of carbon fiber, plastic, ceramic and metal.

Hereinafter, the present invention will now be described in detail with reference to the accompanying drawings.

1 shows a longitudinal sectional view of an embodiment of an extrusion apparatus 100 according to the present invention. The extrusion device 100 consists of a housing 1 comprising an inlet area 2 and an outlet area 3. Thus, the inner space of the housing 1 of the extrusion device 100 is at least partially insulated from the periphery.

A push mandrel 5 is disposed inside the housing 1. The push mandrel 5 extends from the inlet area 2 to the outlet area 3 of the housing 1. The push mandrel 5 forms an annular gap 6 with the inside of the housing. The composite compound 10 is input into the extrusion device 100 through the inlet region 2 of the housing 1. The composite compound 10 is made of high modular carbon fibers, preferably UHM carbon fibers, present in the granulated compound by being fixed by a thermoplastic resin-based plastic matrix. In particular, plastics based on polytetrafluoroethylene (PTFE) are used as matrix substrates due to their thermal and chemical properties.

The input composite compound 10 is introduced into the annular gap 6 by the push mandrel 5. Thus, the composite compound 10 is formed with an annular gap flow, and through the annular gap 6, is intended into the gap 42 formed between the two electrodes 40 and 41 of the device 4 for generating an electric field. It is delivered as one.

The device 4 for generating the electric field is preferably arranged in the outlet area 3 of the housing 1. The device 4 for generating an electric field comprises two electrodes 40, 41, where one electrode is an anode and the other is a cathode. The electric field is induced through the application of an electric voltage, and the carbon fibers contained in the composite compound 10 are aligned with the inverse line of this electric field with a high normal ratio with respect to the axis of the extrusion device 100 through the minimum resistance path. The carbon fibers are preferably directed from the anode to the cathode.

In addition, the housing 1 comprises a mandrel holding tool 8 disposed at least partially inside the push mandrel 5. The mandrel holding tool 8 comprises an outlet 9, which outlet is disposed within the push mandrel 5. The outlet 9 extends to the outlet area 3 of the housing 1. The support air 11 is introduced into the extrusion apparatus 100 via the mandrel holding tool 8 and is guided through the outlet 9 to the outlet region 3 of the housing 1. The support air ensures the stabilization of the inner contour of the carbon fiber reinforced plastic semi-finished product produced in the extrusion apparatus 100.

In addition, at least one temperature sensor 7 is arranged in the housing 1 of the extrusion device 100. In the embodiment shown in FIG. 1 two temperature sensors 7 are shown, where one temperature sensor 7 is arranged in the inlet area 2 and the other temperature sensor 7 is the extrusion device 100 Is placed in the exit area. Here, the temperature sensor 7 determines the uniform temperature control of the melt of the composite compound 10.

2 shows a perspective view of a partial section through the embodiment of FIG. 1. In this figure it is shown that the housing 1 of the extrusion device 100 is preferably designed as a tube. Further, in this embodiment, the push mandrel 5 is designed to be rotationally symmetric. It is also shown that the two electrodes 40, 41 of the device for generating the electric field are designed in the shape of a tube. The electrodes 40 and 41 are arranged concentrically with each other, so that the electrodes 40 and 41 form an annular gap 42. The gap 42 is connected to an annular gap (not shown) of the extrusion device formed between the push mandrel 5 and the interior of the housing. In this drawing, it is shown that the electrode 41 located inside is disposed on the outer surface of the push mandrel 5, and the electrode 40 located outside is disposed on the inner surface of the housing 1 . Preferably, the electrode 41 disposed inside is an anode, and the electrode 40 disposed outside is a cathode. In this case, as soon as an electric voltage is applied, the carbon fibers are aligned from anode to cathode along an inverse line.

3 shows a longitudinal cross-sectional view of an extrusion apparatus incorporated in the extrusion process. Upstream of the extrusion device 100 according to the present invention, an extruder 101 having a twin screw 1001 is disposed. The extruder 101 includes a plurality of heating elements 1003 and a funnel 1002 through which carbon fibers 1004 are guided into the extruder 101. In the twin screw 1001, carbon fibers 1004 are combined with an existing matrix material to form a composite compound 10. The composite compound 10 produced in the extruder is then guided into the extrusion apparatus 100 according to the present invention, as described above, to align the carbon fibers with the electric field. Subsequently, the viscous plastic semi-finished product is discharged into the straightening unit 102 through the outlet region of the housing of the extrusion device 101. In the calibration unit 102, the outer diameter of the plastic semi-finished product is determined. Thus, through a combined analysis of the electric current field, dynamic flow phenomena (calculated fluid dynamics) and thermo-electric behavior, the properties of the plasticized composite compound 10 during the extrusion process are determined, and the extrusion apparatus is dimensioned. . Particularly in order to be able to manufacture high-quality plastic semi-finished products, the extrusion apparatus 100 according to the present invention provides process monitoring (cavity pressure, temperature, voltage), uniform heat distribution (arrangement of heating elements) and safe processing. Corresponding regulation for control, and control of temperature and voltage.

4 shows a schematic view of a partial section of a CFK tube which can be produced by the extrusion apparatus according to the invention and the method according to the invention. By means of the extrusion apparatus according to the present invention, the orientation of high thermally conductive carbon fibers with high normal ratio within the composite compound (not shown) can be aligned as intended along the tube axis. Thus, thin walled (t = 1.5 mm) CFK tubes can be produced that can be used in high efficiency tube heat transfer systems.

5 shows a perspective view of the CFK tube of FIG. 4. From this illustration, it becomes once again clear how the orientation of the carbon fibers (thin black bars) with a high normal ratio along the tube axis is aligned by the extrusion apparatus according to the present invention.

6 shows a comparison of the thermal conductivity (W/m*K) of carbon fiber, plastic, ceramic and metal. From this comparison, it becomes clear that plastics such as PVDF or PP can conduct little heat, whereas metals such as aluminum and copper can conduct heat. Aluminum has a thermal conductivity of 235 W/m*K, and copper has a thermal conductivity of almost twice that of aluminum. However, UHM-special-carbon fiber has the highest heat conduction property of 1200 W/m*K, and the thermal conductivity of this UHM-special-carbon fiber is three times higher than that of pure copper, compared to PP and PTFE. 2700 times higher.

Thus, by using the high anisotropic thermal conductivity of UHM-carbon fibers (p = 2.2 g/cm 3; λ = 1200 W/m*K) as intended by the extrusion apparatus according to the invention or the method according to the invention, A highly efficient and chemically stable tube heat transfer system consisting of a thin-walled (t = <1.5 mm), high thermal conductivity CFK tube can be implemented. Through the special orientation of the fibers with a high normal ratio to the tube axis, a very large thermal conductivity (ρ = 2.0 g/cm 3, λ = 750 W/m*K) of carbon fiber reinforced plastics in the fiber direction can be utilized and , High strength and rigidity of the tube can be achieved. Thereby, the heat transfer area can be reduced. As a result, manufacturing time and manufacturing cost are greatly reduced. In addition, the use of UHM-fibers can minimize thermal tube expansion due to negative coefficient of thermal expansion (< -0.1*10 ^-6 /K), which can replace complex expansion absorption systems, and tube buckling and The risk of leakage can be greatly reduced. In addition, by using a thermoplastic matrix, a very large reduction in system weight occurs, and a significant resistance to chemical and media loads occurs. To this end, plastics based on polytetrafluoroethylene (PTFE), which have already been used in the manufacture of tube heat exchangers for many years in terms of thermal and chemical properties, are considered as matrix substrates.

1 housing
2 entrance area
3 exit area
4 Devices for generating electric fields
40 electrodes
41 electrodes
42 gap
5 push mandrel
6 annular gap
7 temperature sensor
8 Mandrel retention tool
9 outlet
10 complex compounds
11 support air
100 extrusion unit
101 extruder
1001 twin screw
1002 funnel
1003 heating element
1004 carbon fiber
102 calibration unit

Claims (17)

In the extrusion apparatus (100) for manufacturing a carbon fiber reinforced plastic semi-finished product comprising a housing (1) comprising an inlet region (2) and an outlet region (3),
Extrusion device, characterized in that in said housing (1) a device (4) for generating an electric field is arranged. The method of claim 1,
Extrusion apparatus, characterized in that the carbon fiber reinforced plastic semi-finished product is tubular or flat. The method according to claim 1 or 2,
Extrusion device, characterized in that the device (4) for generating an electric field comprises two electrodes (40, 41). The method of claim 3,
Extrusion apparatus, characterized in that the electrodes (40, 41) are formed in an annular shape or flat. The method of claim 4,
Extrusion apparatus, characterized in that the electrodes (40, 41) are arranged concentrically or parallel to each other and form an annular or flat gap (42) between the electrodes (40, 41). The method according to any one of claims 3 to 5,
Extrusion apparatus, characterized in that one electrode is an anode and the other electrode is a cathode. The method according to any one of claims 1 to 6,
Extrusion device, characterized in that the device (4) for generating an electric field is arranged in the outlet area (3) of the housing (1). The method according to any one of claims 1 to 7,
Extrusion apparatus, characterized in that a push mandrel (5) is additionally arranged in the housing (1). The method of claim 8,
Extrusion, characterized in that the push mandrel (5) is formed in a rotationally symmetrical manner and is spaced apart from the housing (1) to form an annular gap (6) between the inside of the housing and the push mandrel (5) Device. The method of claim 8 or 9,
Extrusion apparatus, characterized in that the push mandrel (5) extends from the inlet region (2) to the outlet region (3). The method according to any one of claims 8 to 10,
Extrusion device, characterized in that the housing (1) further comprises a mandrel holding tool (8) which is arranged partially inside the push mandrel (5). The method of claim 11,
The mandrel holding tool (8) comprises an outlet (9) arranged inside the push mandrel (5) and extending to the outlet region (3) of the housing (1). The method according to any one of claims 1 to 12,
Extrusion device, characterized in that the housing (1) further comprises at least one temperature sensor (7). As a method for manufacturing a carbon fiber reinforced plastic semi-finished product,
a) providing an extrusion device (100) and a composite compound (10) according to any one of claims 1 to 13;
b) introducing the composite compound (10) into the extrusion device (100) through the inlet region (2) of the housing (1);
c) generating an electric field;
d) discharging the resulting plastic semi-finished product, for further processing, through the exit area (3) of the housing (1)
A method for producing a carbon fiber reinforced plastic semi-finished product in which is carried out continuously. The method of claim 14,
The method for manufacturing a carbon fiber reinforced plastic semi-finished product, characterized in that the composite compound (10) is formed in an annular gap flow by a push mandrel (5) after step b). The method of claim 14 or 15,
The method for manufacturing a carbon fiber reinforced plastic semi-finished product, characterized in that the melt of the composite compound (10) is uniformly temperature controlled by at least one temperature sensor (7). The method according to any one of claims 14 to 16,
A method for manufacturing a carbon fiber reinforced plastic semi-finished product, characterized in that before step d) support air (11) is guided into the extrusion device (100).

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