EP0754794A2 - Machine for the production of prefabricated reinforcing webs - Google Patents

Abstract

A machine for making semi-finished reinforcing fabrics esp. with a thermoplastic matrix has a feed device (4) for the reinforcing fibres followed by a consolidating device (6) and a wind-up (7). A transport band holds the fabric in a defined position and consists of a needled apron (1) with projecting pins. Pref. a non-woven (2) is fed on to amoving pinned apron (1) which supports it over the full width. Reinforcing fibres, e.g. glass fibre rovings, are deposited in the desired position by a traversing feed which incorporates a press roller to place the rovings on the pins against a pressure plate (9). A second non-woven (3) covers the reinforcement and the assembly is removed from the pinned apron (1) by a stripper (8), consolidated between rollers (6) and wound up (7) for further processing. The pins are equally spaced at, pref. 1 - 3 mm, approximately 3 mm high and inclined in the forward feed direction. The apron (1) is driven at the same speed as the rollers (6). The apron width is pref. limited to 3 m and several aprons can be used in parallel.

Description

The invention relates to a machine for producing prefabricated reinforcement fabrics with a thermosetting / thermoplastic matrix according to the preamble of claim 1.

Fiber-plastic composites (FKV) are becoming increasingly important and consist of fibers, fiber layers, fabrics, scrims or the like, which can be connected to an overall composite using a matrix. The fibers, threads, fabrics, fabrics or similar to be connected are referred to below as semi-finished yarns. These semi-finished thread products can be pre-impregnated with a matrix, these pre-impregnated semi-finished products, for example, in the SMC (sheet molding compounds) method, in which a thermosetting matrix is used, GMT (glass mat-reinforced thermoplastics) method, in which a thermoplastic matrix is used or prepreg processes are used. With these fiber-plastic composite products, the matrix must have good adhesion to the fiber or the threads in order to be able to optimally transmit forces between individual filaments. Correct fiber wetting is particularly important for this. For example, accumulated air bubbles lead to delamination.

It makes sense to pre-condition the quality-determining impregnation section of the semi-finished thread to be connected to the processing process. Such Pre-impregnated fiber structures are referred to as SMC molding compounds, GMT semi-finished products or so-called prepregs.

So-called mat systems are used to manufacture essentially flat composite products. Such a mat system is described in principle for SMC molding compositions in "Introduction to the Technology of Fiber Composites, Michaeli / Wegener, Karl-Hanser-Verlag, Munich-Vienna, 1989, p. 17". With these mat systems, the ready mixed and still thin resin batch is first applied to carrier foils. One of these carrier foils is then passed under a cutting unit and, depending on the setting, cut into smaller pieces, which then fall onto the doctor-coated carrier foil due to the action of gravity. This results in an even distribution of the statistically oriented glass fibers. By additionally laying down uncut rovings, it is also possible to produce molding compositions which have unidirectional reinforcement with quasi-endless glass fibers. These quasi-endless glass fibers are arranged in the conveying direction of the fiber-plastic composite. In a subsequent step, the second film, which has also been knife-coated, is applied to the first film. Intensive mixing of the fibers with the resin mass is achieved in a subsequent stretch. A typical thickness of such a resin mat is in the range of 2 to 3 mm. These resin mats are wound up after their manufacture. After a certain period of ripening, a thickening of the originally thin resin mass creates a leathery and sticky but not stringy mat.

In the GMT process, polypropylene is preferably used as the thermoplastic matrix. GMT is preferably produced on so-called double belt presses, in which the matrix is melted in an extruder and inserted between two glass mats. In addition, thermoplastic films are supplied as cover layers. To get a better one To obtain fiber matrix impregnation, the material is first kept in a heating zone at the level of the melting temperature and then cooled again under pressure.

In order to achieve higher strengths of the fiber-plastic composite products, semi-finished thread products are used as multiaxial fabrics. Such multiaxial fabrics can e.g. using a warp knitting machine with multiaxial weft insertion systems (System Liba).

The width of the fabric to be produced in this way is limited by the thread tension, so that when a certain maximum width is exceeded, the sagging of the fabric webs to manufacturing inaccuracies, etc. by shifting the individual fabric orientations against each other.

Because of the relatively thick side needles required for thread tension and as a result of the needle transport chain, the problem of so-called lane formation occurs especially when the weft is inserted. Such lane formation means an inhomogeneity of the material and includes loss of strength. Especially when using reinforcing fibers, the problem of the exact laying down of the reinforcing fibers in accordance with the force flow plays a decisive role.

The placement of the reinforcing threads in the semi-finished thread can, e.g. in the so-called Malimo process can be achieved by displaceable group segments, the displaceability being small in the Malimo process.

From GB 1 042 134 a machine for producing prefabricated reinforcement scrims is known, in which a web material runs between two belts provided with teeth, which hold threads to be laid down on the web material at their deflection points at a defined angle. Thereby it is possible to lay a laid scrim with threads crossing at a certain angle on the strip material and to fix them there in a suitable manner. The conveyor belt also does not allow the threads to be held in a form-fitting manner.

DE-OS 1 635 481 discloses a machine for producing non-woven products with a fabric-like appearance (right-angled cross-hairs). By means of the machine, a number of threads are deposited in a direction essentially perpendicular to the direction of advance of the mat, it being equally possible to deposit the threads in a diagonal direction in order to be able to produce triangular stitches in addition to the square stitches which can usually be achieved by means of an additional warp thread . To temporarily fix the threads, a track is used, which consists of a textile sheet and has a large number of microscopic spikes. However, such a textile web has the disadvantage that threads which are to be deposited at any angle and in a close position to one another, which is particularly necessary if the threads are to be deposited in accordance with the force flow, can no longer be held in a defined position. The microscopic serrations thus serve at most to lay down the threads in a uniform geometric position and temporarily fix them there. Uniform geometry is understood to mean laying down such that either square or triangular meshes, i.e. regular geometric figures are formed.

It is therefore an object of the invention to provide a machine for producing prefabricated reinforcement scrims with a thermoset or thermoplastic matrix in particular, with which sagging of the semi-finished thread products is avoided, and the reinforcement fibers are deposited, even with large widths can be made at any angle and curvature.

This object is achieved by a machine with the features according to claim 1.

The machine for producing prefabricated reinforcement scrims, in particular with a thermosetting or thermoplastic matrix according to the invention, has a feeding device for reinforcing fibers or reinforcing threads, a consolidating roller or double-belt pressing device or knitting machine, for example, arranged after the feeding device for reinforcing fibers, and a winding device for the reinforcing scrim. In the area of the feed device for the reinforcing fibers, at least one conveyor belt is preferably arranged under the semi-finished thread, which is designed as a needle caterpillar with protruding macroscopic needles and carries and promotes the reinforcing fibers and fixes them before calendering or meshing. This prevents any sagging of the reinforcing fibers, which makes it possible without further ado, with correspondingly wide needle caterpillars, e.g. up to 3.5 m. A device for feeding a thread semi-finished product is preferably provided. The semi-finished thread products, which can also be impregnated with a thermoset or thermoplastic (prepreg fibers), are (pre) consolidated on the plastic-technical device (e.g. calender) arranged in front of the winding device to form a fiber-plastic composite.

A further advantage in the production of thermoplastic prepregs is that an active unit for knitting the semi-finished thread can be dispensed with, since the calender or the consolidating device serves to fix the semi-finished thread.

To provide appropriate support for the semi-finished thread products over their entire production width, the needle bead is either arranged continuously over the entire width, or two or more needle beads are arranged next to one another at the same height under the semi-finished thread product.

In a preferred embodiment, the needle bead has on its side facing the semifinished product a plurality of needles which are preferably evenly spaced apart. The needles are preferably inclined by a defined angle in the conveying direction of the semi-finished thread in order to simplify the triggering of the semi-finished fiber.

In order to prevent production-related tensions from arising in the fiber-plastic composite, in a further exemplary embodiment the needle caterpillar and the calender roller device can preferably be driven synchronously. So that the reinforcing fibers to be fed into or to be installed in the material can be deposited on the conveyor belt in accordance with the flow of force, the feed device for the reinforcing fibers is displaceable transversely to the conveying direction of the semi-finished thread.

Further advantages and possible applications of the invention will now be described below with reference to the accompanying drawings.

Fig. 1

eine prinzipielle Maschinenanordnung zur Herstellung eines Legesystems gemäß der Erfindung für vorkonfektionierte Verstärkungsgelege mit thermoplastischer Matrix;

Fig. 2

die prinzipielle maschinenmäßige Anordnung zur Herstellung vorkonfektionierter Verstärkungsgelege gemäß der Erfindung;

Fig. 3

eine Draufsicht der prinzipiellen Anordnung der Hauptmaschinenteile gemäß Fig. 2 ohne Fadenhalbzeuge und Verstärkungsfäden;

Fig. 4

den prinzipiellen Aufbau einer Nadelraupe; und

Fig. 5

die Anordnung eines Legewagens über der Nadelraupe zur Erzielung von verschiedenen Orientierungen der Verstärkungsfäden.

Show it:

Fig. 1

a basic machine arrangement for producing a laying system according to the invention for pre-assembled reinforcing fabrics with thermoplastic matrix;

Fig. 2

the basic machine arrangement for producing prefabricated reinforcement scrims according to the invention;

Fig. 3

a plan view of the basic arrangement of the main machine parts according to Figure 2 without semi-finished products and reinforcing threads.

Fig. 4

the basic structure of a needle caterpillar; and

Fig. 5

the arrangement of a laying carriage over the needle bead to achieve different orientations of the reinforcing threads.

In the advantageous embodiment of the laying system shown in FIG. 1 for the production of prefabricated reinforcement beds according to the invention, here with a thermoplastic matrix, a fleece 2 runs over a needle bead 1, which is supported by the entire width of the fleece 2 and by which at the numerous needles 12 attached to the fleece 2 side also act as a conveyor belt. In the area of the needle caterpillar 1, a laying unit 4 is provided which is movable in a direction transverse to the conveying direction of the fleece 2 and which is fed with reinforcing threads or fiberglass roving 11 through a gate 5. The needles 12 arranged on the needle caterpillar 1 serve to fix the reinforcing threads 11. Due to the laying unit 4, which is displaceable transversely to the conveying direction of the nonwoven, the reinforcing threads 11 can be deposited in accordance with the flow of force in the final product to be produced later from the prepreg product 10. In order to prevent the fleece 2 from bending when the reinforcing threads 11 are pressed onto the needle bead 1 with a roller 13, a counterpressure plate 9 designed as a counter-holding device is provided in the area of the laying unit 4 under the needle bead 1. A pressure roller is provided in the area of the roller 15 arranged behind it in the conveying direction of the fleece 2 for driving the needle bead 1. around which another fleece 3 is fed and pressed to fix the deposited reinforcing threads 11.

In order to prevent the fleece carried on the needle tips (or the fleece 2, the reinforcing threads 11 and the fleece 3) from running around the roller driving the needle bead 1, a stripping device 8 is provided. This stripping device 8 prevents the relatively loose composite material consisting of two nonwoven layers 2, 3 and the reinforcing threads 11 defined between them from rotating around the roller 15 driving the needle bead 1 or the deflecting roller 14. The relatively loose material is fed directly from the stripper 8 to the calender 6, which consists of two heatable rollers. The heatable rollers introduce heat into the material, which causes the thermoplastic fleece to melt, so that a so-called prepreg product is formed on the side located in the conveying direction after the calender 6 and is wound up on a winding device 7.

Fig. 2 shows the basic machine arrangement of the main components of the machine according to the invention in side view. In relation to the entered reference plane B, a semi-finished product in the form of a fleece runs on this plane over the needle bead 1 carried by the drive roller 15 and the deflection roller 14. In the conveying direction directly behind the deflection roller 14, the thread semi-finished product / the fleece is applied to the needle bead 1 and in Conveyed away. In the conveying direction behind this, the reinforcement threads 11 are deposited on the thread semifinished layer running on the reference plane B via a device 4 for feeding reinforcement fibers. In order to prevent the needle bead 1 from being pushed through, a corresponding counter-pressure plate 9 is arranged under each corresponding feed device. In a further facility for depositing, the thread semifinished layer with the already deposited glass fiber rovings is placed glass fiber rovings such as this, a further layer of reinforcing threads deposited from the first roving layer deposited. Instead of the second layer of reinforcing threads or additionally, a laying system for fleece 3 with corresponding pressure rollers and a counterpressure device 9 arranged underneath can also be arranged. Behind the drive roller 15 for the needle caterpillar 1 there is a scraper 8 which ensures a secure feed to the calender rollers 6. The temperature of the calender rolls 6 is set so that a consolidated bond between the semi-finished fiber products and the matrix is achieved. This prepreg product 10 reaches the winding device 7 from the calender rolls or consolidating rolls 6.

In Fig. 3 a top view of the arrangement described in Fig. 2 is shown and without the materials supplied, i.e. the thermoplastic semi-finished thread and the supplied reinforcing threads are shown.

4 shows the basic arrangement of a needle bead 1 according to the invention. The needle bead 1 has a width which is sufficient to fully support the fleece 2 to be fed (see FIG. 1). This needle caterpillar 1 is driven by a drive roller 15, from which a deflecting roller 14 is arranged at a distance, so that the needle caterpillar 1 rotates as an endless conveyor belt around these two rollers 14, 15. On the outward-facing side of the conveyor belt, ie the side facing the fleece 2 (see FIG. 1), based on the machine arrangement, the needle bead 1 has a multiplicity of substantially evenly spaced projecting needles 12. In order to ensure a better conveying effect of the fleece 2 by the needles 12 of the needle bead 1, the needles 12 are inclined forward in the conveying direction at a certain angle. Depending on the requirements, any width of such a needle bead can be used. The width of the needle bead preferably exceeds 1 but not 3 m. The distance between the individual needles 12 is preferably 1 to 3 mm, but can also have a greater distance from one another depending on the semi-finished thread.

The needles have a height of ≧ 3 mm in order to ensure that the reinforcing fibers are safely deposited on the needle bead. With such a needle height, it is possible to reliably fix reinforcing fibers of customary varying thickness on the needle bead, the distance between the individual needles depending on the accuracy or achievable curvature including the consideration of the thread size. The smaller the distance between the needles, the more precisely the reinforcing fibers can be laid down in a manner that suits the flow of force. On the other hand, with a closer needle spacing, the maximum thickness decreases, up to which the reinforcing fibers can still be reliably deposited in the spaces between the needles.

5 shows the basic arrangement of a laying carriage or a laying unit 4, with which the laying principle of the reinforcing threads 11 can be achieved in various desired orientations. In order to achieve an orientation of the reinforcing threads 11 which is different from the axial orientation, that is to say from the conveying direction of the prepreg product to be produced, the laying carriage 4 is moved with the feeding device for the reinforcing threads 11 in a direction which essentially perpendicular to the conveying direction of the prepreg product and essentially parallel to it. At the same time, a placement roller 13 arranged on the laying carriage 4 can be pivoted. Different angles α can thereby be generated. Through a correspondingly coordinated movement of the laying carriage 4 transversely to the conveying direction in connection with the conveying speed of the prepreg product, arbitrarily curved laying directions for the reinforcing threads 11 can also be achieved, so that with the proposed device, a force flow-appropriate depositing of the reinforcing threads 11 on the semi-finished thread layer can be achieved.

"Laying down according to the flow of force" should be understood to mean that the reinforcing fibers are arranged on the needle bead in such a way that, in the position fixed by the needle bead within a fiber-plastic composite, they maintain or maintain the position which corresponds to the lines of force on which the forces which are introduced into the later component are passed on in the component. Likewise, "laying down in accordance with the flow of force" is to be understood to mean that the reinforcing fibers can be laid down in such a way that a reinforcement of the component to be produced later, in particular around openings, i.e. in the region of the edge of the component facing the opening. The method described and the device for carrying out the method are thus easily usable for fiber-plastic composites in which certain openings or openings are already provided in the semi-finished product, in which the edge of the openings is reinforced by means of the reinforcing fibers. This results in a very diverse field of application for the fiber-plastic composites, which can be produced by the method or with the device according to the invention. An essential area of application for components manufactured in this way is e.g. in the production of vehicle body components, which naturally have numerous openings to be reinforced locally.

Of course, it is also possible to control the feed device 4 for the reinforcing fibers 11 in such a way that the reinforcing fibers are arranged within the framework of the fiber-plastic composite in such a way that, after processing of the semi-finished product into the end product, they are arranged in a spatial manner in the spatial component.

Claims (8)

Machine for producing prefabricated reinforcement scrims with a thermoplastic matrix in particular, which has a feed device (4) for reinforcement fibers (11), a consolidating device (6) arranged thereafter, a winding device (7) and a conveyor belt for positively holding the reinforcement scrim in a defined position,
characterized,
that the conveyor belt is designed as a needle bead (1) with protruding needles and is arranged in the area of the feed device (4) for the reinforcing fibers (11) and fixes the reinforcing fibers. Machine according to claim 1, characterized in that the feed device (4) for the reinforcing fibers (11) can be displaced unevenly with respect to the conveying direction of the semi-finished thread (2) and the reinforcing fibers (11) can be deposited in relation to the product to be produced in a manner that is compatible with the force flow. Machine according to claim 1 or 2, characterized in that the needles are essentially evenly spaced. Machine according to claims 1 to 3, characterized in that the needle bead (1) has needles (12) inclined in the conveying direction. Machine according to one of claims 1 to 4, characterized in that the needle bead (1) and the consolidating device (6) can be driven synchronously. Machine according to one of claims 1 to 5, characterized in that the needle bead (1) extends substantially over the entire width of the semi-finished thread (2). Machine according to one of claims 1 to 5, characterized in that at least two needle beads (1) are arranged next to one another and at the same height under the semi-finished thread (2). Machine according to one of claims 1 to 7, characterized in that a device for feeding a semi-finished thread (2) is additionally provided.

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