Resin line with circumferential openings

Abstract

Resin line with circumferential openings for supplying a matrix material used as a resin system for impregnating reinforcing fibers inserted into a tool, characterized in that the resin line is formed from a corrugated pipe (2) whose wall has through-openings (4).

Description

[0001] The present invention relates to a resin pipe with circumferential openings according to the preamble of claim 1.

[0002] A generic resin line is known from DE 10 2014 011 787 A1. This document discloses a flexible spiral hose as the resin line. The resin line is inserted into a mold to produce a fiber composite component, in order to supply a liquid matrix material to reinforcing fibers inserted into the mold under a vacuum. The reinforcing fibers can be semi-finished fibers such as rovings, mats, non-crimp fabrics, woven fabrics, multiaxial materials, knitted fabrics, and braids, and can be made from a wide variety of fiber materials, such as carbon fibers, glass fibers, aramid fibers, boron fibers, or hybrid materials, including any combination thereof. The reinforcing fibers are impregnated with the matrix material supplied via the resin line. The matrix material also fills the mold.Various suitable resin systems can be used as matrix materials. These resin systems have a suitable viscosity in the operating temperature range and bond well with the reinforcing fibers. The matrix material cures in the mold after the reinforcing fibers are completely saturated and the mold chamber is filled. The finished component can then be removed from the mold. The vacuum infusion process is described as an example in DE 102 39 325 B4.

[0003] A resin line for conveying resin for impregnating fiber material is known from document US 2006 / 0068170 A1. The detailed design of this resin line is not disclosed in the document. A perforated synthetic resin pipe is known from document DE 29 15 691 A1. However, it is not used for conveying synthetic resin, but rather for irrigation and drainage.

[0004] The flexible spiral hoses known from the state of the art are relatively expensive to manufacture. They must have relatively thick walls to avoid collapsing under the influence of the vacuum. Depending on the bending radii at which the spiral hoses are laid, the spirals open to varying degrees, so that the release of the matrix material is not uniform throughout the length of the resin line. To adapt their permeability to different requirements, different hoses must be used, each of which requires different tools for their production. Variable adaptation to different permeability requirements is therefore only possible with different types of hoses in stock.

[0005] It is the object of the present invention to provide a resin line which can be produced cost-effectively, which meets the static requirements under the influence of vacuum and which enables a more precise dispensing of the matrix material regardless of the bending radii in which the resin line is laid.

[0006] The task is solved for a generic resin pipe in that the resin pipe is formed from a corrugated pipe whose wall has through openings.

[0007] The proposed corrugated pipe is made of a rigid material that allows for flexible installation thanks to its corrugated shape. The corrugated pipe is preferably made of a thermoplastic material, such as polyamide, polyethylene, polyvinyl chloride, polytetrafluoroethylene, or polypropylene. The plastic material used must still have sufficient strength within the working temperature range of the matrix material to prevent it from collapsing under the vacuum in the tool and / or from softening or liquefying due to the heat from the matrix material or the solvents it contains, to the point where the matrix material can no longer be reliably distributed within the tool or the matrix material becomes contaminated by the material of the corrugated pipe.

[0008] The wall of the corrugated tube has a diameter that varies in a wave-like manner along its length. Depending on the material used, the wall thickness of the material can be reduced to a thickness of 0.2 to 0.4 mm compared to spiral hoses. The corrugations of the corrugated tube can be designed in parallel, ring-shaped patterns, or the corrugations run spirally, which can improve the flow behavior of the matrix material. Due to the wave shape of the wall, turbulence tends to occur in the matrix material during flow, which reduces the flow velocity. However, at the low flow velocities of the matrix material, these effects are negligible. However, the more homogeneous temperature distribution of the matrix material across the cross-section of the resin line is advantageous, especially at the start of the infusion, which occurs as a result of the turbulence.

[0009] The corrugations of the corrugated pipe create increased rigidity and load-bearing capacity in the radial direction compared to a smooth wall surface. In the longitudinal direction, however, the corrugated pipe can also be easily deformed into the bending radii required for insertion into a given tool due to the corrugated pipe's waveform. This makes corrugated pipe an ideal material for meeting the rigidity requirements under vacuum conditions, as well as the flexibility requirements for easy installation of a resin pipe in a tool.

[0010] The corrugated pipe material can be easily stored and transported as extruded, continuous material rolled up on spindles. The corrugated pipe material required for a production process can be cut to any length from the continuous strand, thus reducing cutting waste to a minimum.

[0011] The corrugated tube has openings through which the matrix material can flow from the interior of the corrugated tube to the exterior. The openings are dimensioned and shaped so that, depending on the viscosity and flow behavior of the matrix material used and the desired flow fronts within the tool during the impregnation phase, a precisely adjusted amount of matrix material emerges at the desired location. The openings can be located in the trough or at the crest of the corrugation, or they can extend along the length of one or more corrugations.

[0012] According to one embodiment of the invention, the resin line is covered with a flow aid and / or a fleece. A flow aid consists of a net-like fabric that allows the matrix material to flow even under the vacuum pressure of an overlying film. The flow aid is also advantageous for distributing the matrix material emerging from the corrugated pipe as evenly as possible. Since the tool can be covered with a matrix material- or gas-impermeable film during the infusion process, it is possible that without a layer of flow aid the passage opening is closed by the film, particularly when a vacuum is applied, so that no matrix material can escape through this passage opening. The flow aid prevents the passage opening from being closed by a film. The fleece serves the particular purpose of retaining gas bubbles that are present in the matrix material.When the matrix material begins to seep through the fleece, the gas bubbles in the first foam burst, and the gas can be sucked away. When the resin line is permeated with liquid matrix material, the gas bubbles adhere to the fleece fibers due to their surface tension and do not pass through the fleece. In this way, the fleece retains the gas bubbles in the matrix material. A lower number of gas bubbles in the finished fiber composite component improves its quality. For the invention, it is irrelevant whether the flow aid or the fleece is applied externally, as long as the corrugated pipe is coated with both materials.

[0013] According to one embodiment of the invention, the shape, size, and / or frequency of the through-openings varies along the length of a corrugated pipe section. The through-openings do not have to be uniformly formed along the length of the corrugated pipe; it is also possible to vary the shape, size, and / or frequency of the through-openings along the length of a corrugated pipe section in order to specifically influence the flow behavior of the matrix material in a tool. For this purpose, through-openings of different shapes, sizes, and / or frequencies can be punched, lasered, melted, cut, or otherwise introduced into the wall of the corrugated pipe using a machine.This makes it possible to allow more matrix material to flow into one tool section than into another tool section in a given time interval, which can be advantageous, for example, in the case of fiber composite components with different material thicknesses in order to enable a uniform advance of a flow front in the tool.

[0014] According to one embodiment of the invention, the resin line is composed of several corrugated pipe sections that are connected to one another by a coupling piece. It is particularly possible to join corrugated pipe sections with different shapes, sizes, and / or frequencies of through-openings together using coupling pieces to thereby obtain a corrugated pipe string that allows more or less resin material to escape at certain sections along its length. To do this, a processor would have to keep corrugated pipes with different through-openings on hand in order to optionally connect them in sections to one another to form a resin line. Alternatively, it is possible for a processor to keep a perforation machine on hand with which they can provide a corrugated pipe type with through-openings of different shapes, sizes, and / or frequencies according to current needs. A processor can then produce corrugated pipe sections as required.

[0015] According to one embodiment of the invention, corrugated pipe sections with different diameters are connected to one another by coupling pieces to form a resin line. Different diameters can be used to set different pressure conditions in the corresponding sections of the resin line. If, for example, a resin line is composed of several sections whose diameter decreases the further the section is from the point at which the matrix material is introduced into the resin line, this can at least partially compensate for the pressure drop that occurs over the length of the resin line when the diameter remains constant. It is also possible to divide a thicker resin line into two thinner resin line strands in the area of ​​a coupling, whereby the matrix material can be fed to the tool over a larger area without a pressure loss in the resin line.By influencing the pressure in the resin line, the velocity at which the matrix fluid exits this section of the resin line can also be influenced. Using corrugated pipe sections with different diameters can therefore also contribute to a more even and targeted distribution of the matrix material in a mold, with a specifically controlled flow front.

[0016] It is expressly pointed out that the above-described embodiments of the inventions can be combined with the subject matter of claim 1, either individually or in any combination.

[0017] Further advantageous modifications and embodiments of the invention can be found in the following description and the drawings.

[0018] The invention will be described in more detail using an exemplary embodiment. It shows: Fig. 1: a view of a corrugated pipe, Fig. 2: a view of a corrugated pipe with a flow aid, and Fig. 3: a view of a corrugated pipe with an additional fleece.

[0019] In Fig. Figure 1 schematically shows the outline of a corrugated pipe 2. Also schematically indicated are passage openings 4 located in the wall of the corrugated pipe 2. In the illustrated embodiment, the corrugated pipe 2 consists of a sequence of parallel annular formations. In the illustrated embodiment, the rings are shown with a square cross-sectional contour; however, the rings can also have a rounded cross-sectional shape, such as a semicircular or semi-oval shape.

[0020] When a matrix material flows through the corrugated tube 2 in the longitudinal direction L, the matrix material can escape through the through-openings 4. When the corrugated tube 2 is inserted into a mold for producing a fiber composite component, the matrix material, after leaving the corrugated tube, can seep through the through-openings 4 into the reinforcing fibers laid out in the mold and fill the mold.

[0021] In Fig. Figure 2 shows a view of a corrugated pipe that is at least partially coated with a flow aid 6. As the matrix material emerges from the interior of the corrugated pipe 2 through the through-holes 4, the matrix material penetrates the fiber layer of the flow aid 6, spreads within it, and from there, drawn by the vacuum, can penetrate further into the tool. The matrix material is distributed more effectively within the tool over the surface of the flow aid 6.

[0022] In Fig.Figure 3 shows a view of a corrugated pipe 2 in which the corrugated pipe 2 is coated with an additional fleece. The fleece serves the purpose of dissolving and retaining gas bubbles located in the matrix material that escapes from the corrugated pipe 2 through the openings 4.

[0023] The corrugated pipe according to the invention can be laid particularly along the edge of tools, where it is unimportant that the outer contour of the corrugated pipe remains as an impression in the curing matrix material. Since in such tools the edge pieces of the fiber composite component are frequently cut off and disposed of, the impressions of the corrugated pipe are not visible in the matrix material of the finished fiber composite component. In such an application, the advantages of the easy handling of the resin line, when consisting of a corrugated pipe, as well as the low procurement costs of such a resin line outweigh the disadvantages. Another important aspect when using the corrugated pipe as a resin line is that the supply of the matrix material into the tool can be better controlled at specific points by using corrugated pipes with appropriately designed through-openings.

[0024] The exemplary embodiment described above serves only to illustrate the invention. The invention is not limited to the exemplary embodiment described above. Those skilled in the art will have no difficulty modifying the exemplary embodiment in any way they deem appropriate in order to adapt it to a specific application.

Claims

[1] Resin line with circumferential openings for supplying a matrix material used as a resin system for impregnating reinforcing fibers inserted into a tool, characterized by that the resin line is formed from a corrugated pipe (2) whose wall has through openings (4). [2] Resin line according to claim 1, characterized by that the resin line is covered with a flow aid and / or a fleece. [3] Resin line according to claim 1 or 2, characterized by that the shape, size and / or frequency of the passage openings (4) varies over the length of a corrugated pipe section. [4] Resin line according to one of the preceding claims, characterized by that the resin pipe is composed of several corrugated pipe sections which are connected to each other by a coupling piece. [5] Resin line according to one of the preceding claims, characterized bythat corrugated pipe sections with different diameters are connected to each other by coupling pieces to form a resin line.

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