DE102009049668A1 - Laying head and method for the controlled deposition of deflected fiber strands - Google Patents

Abstract

The present invention relates to a laying head for the controlled laying down of a cut fiber strand, which has a specially designed transport channel, whereby the fed endless phase is already cut to length in the laying head. A corresponding procedure is also given.

Description

The present invention relates to a laying head for the controlled depositing of a cut fiber bundle, which has a specially designed transport channel, whereby a cutting of the fed continuous phase already takes place in the laying head. Likewise, a corresponding method is specified.

Components made of short- or long-fiber reinforced plastics are largely used as semi-structural components. This is mainly due to the mechanical properties of short or long fiber reinforced plastics and the associated load limits. In the component inserted structures of any kind, such. As inlays, attachment points, metallic reinforcing structures, etc., due to the connection to the component (glued, pressed, screwed, etc.) can only transmit forces and loads that are dependent on the mechanical properties of short or long fiber reinforced plastics.

In order to use short or long fiber reinforced plastic components in structural applications or to transfer higher loads can be short or long fiber reinforced components in addition with continuous fibers, eg. As mats, scrims, flow, etc., reinforced.

Depending on the process, the continuous fibers are impregnated in advance with a plastic and then placed in the tool (tailored fiber placement), wound (winding technology) or pressed (for example, in the LFT-D process dry fiber rovings, mats, blends, preforms, etc., for example by draping, braiding, embroidering, etc., into the appropriate shape.

Next there is the possibility of endless fibers, z. As mats, scrims, flow, etc., bring in a closed mold and then infiltrated with short or long fiber reinforced matrix material (S-RIM method). If the fiber mats are infiltrated outside or while the tool is open, we talk about fiber spraying (CSM, PSM, LFI, fiberglass production).

The incorporation of local reinforcement structures (metallic, non-metallic) can be carried out by pressing, foaming, gluing, overspraying, sewing and braiding or wrapping dry or already impregnated continuous fibers.

So is out of the DE 32 26 290 a method and an apparatus for the controlled deposition of fibers on a component form, in which a fiber strand is passed through a non-contact conveyor in the direction of the mold and pressed with compressed air onto the mold. The cutting of the fiber takes place outside the device. An impregnation of the fibers is not possible.

The EP 0 320 653 relates to an apparatus for impregnating an endless roving with a molten thermoplastic resin, but disadvantageous in the apparatus described therein is that due to a lack of possibility for continuous cleaning of the device by the resin only a short service life of the device is achieved.

From the DE 10 2006 035 847 Furthermore, a device is known, can be produced with the components for aerospace. Only preimpregnated, mat-shaped rovings can be processed.

The DE 10 2008 012 839 relates to an apparatus and a method for producing a continuous strand composite, with which the impregnation of an endless roving is provided with a resin.

Based on the prior art, it was an object of the present invention to provide an apparatus and a method for the controlled deposition of a fiber strand, with a reliable and targeted deposition is possible. It was also an object of the present invention to provide a device which is self-cleaning and therefore has an increased service life.

With regard to the laying head this object is achieved with the features of claim 1. Claim 7 relates to a device in which the depositing head according to the invention is integrated. Furthermore, the object is achieved by a method for depositing fiber strands according to the feature of claim 8. Claim 16 relates to the possible uses of the deposition head or the method. The respective dependent claims are advantageous developments.

According to the invention, a depositing head is thus provided for the controlled depositing of at least one cut fiber strand comprising at least one roller conveying device and at least one transport channel arranged in the conveying direction downstream of the roller conveying device, each having a guide for at least one endless fiber strand, wherein the at least one transport channel has an opening the one arranged at the height of the opening separating unit for cutting the fiber strand can intervene or the at least one transport channel in Conveying direction is formed in two parts, wherein the two parts of the transport channel are movable relative to each other in the conveying direction and at the level of forming by the relative movement of the two parts of the channel gap a separating unit for cutting the fiber strand is arranged.

The first variant of the laying head according to the invention thus provides to arrange an opening in the transport channel into which a separating unit can engage. As a result, a safe separation or cutting of the fiber strands is possible. In contrast to known from the prior art devices, which always provided a separation of the fiber strand outside of the laying head, thus a more efficient and accurate cutting of the fiber strand is made possible.

In an alternative embodiment of the laying head according to the invention, the transport channel is formed in two parts, wherein the two parts are arranged to be movable relative to each other. In particular, the part of the transport channel, which is arranged closer to the outlet end of the deposition head, can be moved or displaced in the direction of the outlet opening of the deposition head in the conveying direction.

The separation of the endless fiber thus takes place in the region of the closed channel. Through the opening or a division of the channel, it is possible to form a cutting gap. The division or the pulling apart of the cutting gap in the channel can be done manually manually or electrically, pneumatically or hydraulically. By the roller conveyor unit, it is possible to withdraw the separated fiber strand after separating a piece in the channel in the direction of the roller conveyor unit, so that a blockage of the channel can be avoided. Subsequently, the split channel is closed again and the fiber transport unit is available again in the initial state.

The roller conveyor consists z. B. from a motor (stepper motor, servomotor, etc.), which drives one or more roles directly or by means of a translation. The rollers can either push or pull the supplied continuous fiber strand depending on the direction of rotation of the motor through the fiber guide and have a braking effect on the fiber strand when pulling the fiber strand through the unit.

The endless fiber or fiber strands are thus supported by the roller conveyor unit by a subsequently attached closed channel (transport channel) of any geometry.

Preferably, a mixing chamber for impregnating the at least one fiber strand adjoins the transport channel in the conveying direction. With this embodiment, it is possible for the first time to simultaneously carry out impregnation and cutting of continuous fibers.

The impregnation of the cut fiber strand thus takes place after the separation unit outside the closed channel for fiber guidance in the so-called. Mixing chamber. As a result, contamination, sticking or clogging of the channel is avoided. The fiber impregnation is carried out by a pressureless application or pressurization with resin / plastic.

The mixing chamber advantageously has a feed for a matrix material for impregnating the fiber strand.

Further, it is advantageous if the mixing chamber is dimensioned such that the conveying direction of the mixing chamber facing part of the transport channel is positively inserted into the mixing chamber.

The mixing chamber can be cleaned by pulling the fiber guide channel of plastic / resin. The second part of the fiber guide channel assumes the function of a cleaning ram for cleaning the mixing chamber. In addition, it is possible to clean the channel and the mixing chamber with compressed air and / or cleaning agent through the air inlet openings in the fiber guide channel.

A further preferred embodiment of the laying head provides that at least one inlet opening for air is provided between the roller conveyor unit and the at least one transport channel, in the wall of the at least one transport channel and / or in the mixing chamber.

As a result, a kind of blocking air flow can be applied in the fiber transport channel, which is intended to prevent the plastic / resin from running back into the transport channel.

The fiber / fiber strand fixation in the tool can by clamping or by selective curing of the fiber / fiber strand, z. B. by infrared emitters, UV lamps or other heat sources can be realized.

Likewise, following the mixing chamber at least one fiber eye, the number of fiber eyes preferably corresponding to the number of fiber strands performed, may be arranged. Preferably, the fiber eye is tempered.

Furthermore, according to the invention, a device is provided for the controlled depositing of cut-to-length fibers into which the laying head according to the invention described above is integrated. The Device may, for example, still include a supply roll with endless rovings and a depositing device, etc. Likewise, a mechanical control of the device is possible to allow a locally targeted laying of the fibers. The device may, for. B. be controlled by a robot arm.

The invention also provides a method for depositing at least one cut-to-length fiber strand with a laying head or a previously described device, in which at least one continuous fiber strand is conveyed to the at least one roller conveying device respectively in the guide of the at least one transport channel and the at least one continuous fiber strand by intervention of the separation unit is cut into the opening of the at least one transport channel, or the two parts of the respective transport channel are moved relative to each other in the conveying direction, wherein a gap between the two parts of the respective transport channel is formed and the at least one fiber strand is cut by means of the separation unit and subsequently the cut fibers are discharged.

The process thus describes, in particular, the controlled depositing of preferably impregnated fibers (thermoplastic / duroplastic materials) into a component form or outside a component form. The method is particularly suitable for producing parts made of fiber composite plastics. The process is characterized by the laying head according to the invention, in which an endless fiber strand or fiber strands supplied by one or more supply rolls are introduced. In the laying head, each fiber strand is forwarded by a roller conveyor in the direction of the mold or a plurality of rovings with the same roller conveyance and impregnated without pressure or pressure by a matrix material emerging from a nozzle or a tube. The role promotion can have both the sliding function and a braking function on at least one fiber strand / roving. The laying head is attached either to a traveling platform mounted above the mold or to an arm of a robot which can be swiveled in any direction.

In order to improve the impregnating effect in order to set a fiber weight fraction / fiber volume fraction and to bring the impregnated roving to a desired shape, the impregnated roving can still be pushed or pulled through another opening (fiber eye).

The continuous fiber strand used is preferably pushed by a motor through the closed channel. Alternatively, the motor may also have a braking action on the fiber strand when pulling the fiber strand through the unit. The channel takes over the support function for the fibers and avoids buckling / evasion of the fiber. The speed of the fiber can be adjusted via the control of the stepping motor and thus be a controlled variable for the resin / plastic required for infiltration.

The fiber guide channel comprises at least one opening, in which a kind of separation unit can intervene to cut the fiber. Alternatively, the fiber guide channel is designed at least two parts, of which at least one channel is displaceable or rotatable. In this way, by cutting or twisting the channel a kerf can be formed and the fiber strand can be separated by all known separation methods. In addition, the entire fiber guide channel can be acted upon with a sealing air / sealing gas.

The split fiber guide channel or fiber guide channel in general is used as a cleaning ram for the mixing chamber. This can be dispensed with a separate cleaning ram. The two-part channel with the formation of a cutting gap has the advantage that the separation unit can not be contaminated. In addition, by pressurizing by means of gases of any kind on the fiber guide channel or by introducing a cleaning medium, the mixing chamber can be additionally cleaned.

By using a stepper motor or servo motor per fiber strand, different discharge speeds per fiber strand can be realized in the case of several fiber strands, which can be advantageous in particular when imaging a wide variety of geometries.

The impregnation of the fiber strand can be effected by the pressurized matrix material, for. B. by spraying the matrix material. The impregnation effect can also be improved by a sputtering medium (gases of any kind).

Pushing or pulling the fiber strand through another optionally temperature-controllable opening (fiber eye) offers the possibility of bringing the impregnated roving to a desired shape, improving the impregnation quality and setting a fiber weight / fiber volume fraction. The divisible transport channel can also take over the cleaning function of the fiber eye.

The described unit can be used to deposit the impregnated fiber strands directly into an open mold and to bring them into contact with another plastic either before or after.

Furthermore, the unit also offers the possibility of depositing structures outside of the tool in a targeted manner, of introducing them into a tool in the hardened state and then of connecting them with another plastic / resin when the tool is open or closed.

A particular advantage of the laying head, the device according to the invention and the method is that for the first time a simultaneous impregnation and cutting of the fibers in a single device is made possible.

An advantageous embodiment of the method provides that before, during and / or after cutting to length in the mixing chamber, the at least one fiber strand is impregnated by application of matrix materials, preferably plastics or resins, in particular by spraying with the matrix materials or atomization of the matrix materials.

Likewise, it is possible that after impregnation and / or discharge of the at least one cut fiber, cleaning of the mixing chamber by blowing compressed air and / or a cleaning medium through the at least one inlet opening of the mixing chamber and / or by introducing the facing in the conveying direction of the mixing chamber part the transport channel takes place.

A further preferred embodiment of the method provides that air is blown into the deposition head via the at least one inlet opening arranged between the roller conveyor unit and the at least one transport channel, in the wall of the at least one transport channel and / or in the mixing chamber.

With the fiber eye can preferably at least one fiber strand z. B. be formed or tempered during discharge from the deposition head.

Further, in the case of multiple fiber strands, the implementation of the fiber strands with the same or different speed through the laying head is possible. As a result, different fiber lengths can be set in a single step.

It is particularly advantageous that a mechanical cleaning of the transport channel takes place by the relative movement of the two parts of the respective transport channel.

The inventive method is particularly suitable for cutting to length and / or impregnation of endless Glasfaserrovings.

According to the invention uses of the depositing head or the method of the invention are also specified, these are in particular the production of parts made of fiber composites, for the controlled deposition of fibers outside and / or in a component form, for targeted pulling any geometry, in the production of profiles, in the Production of fiber composites, continuous fiber reinforced components, locally reinforced materials, locally reinforced support structures and / or hybrid reinforcement structures.

The present invention will be explained in more detail with reference to the attached figures, without limiting the invention to the embodiment shown there.

In 1 an inventive Ablegekopf is shown in which an endless roving 1 via a roller conveyor 2 fed to the deposition head. The roller conveyor serves both the propulsion of the roving in the laying head, as well as the stabilization of the roving. Immediately after the introduction of the roving 1 in the deposition head are several inlet openings 3 intended for air. Subsequently, a transport channel closes 4 which in the present case is divided into two parts ( 4 ' . 4 '' ) is trained. The part shown in the figure below 4 '' of the transport channel 4 is arranged such that a guide of this part 4 '' into the mixing chamber 6 is possible. The part 4 '' and the chamber 6 forming recess 6 are designed so that the part 4 '' positive fit in the chamber 6 is insertable. Thus, the part serves 4 '' virtually as a cleaning pestle and can when inserted into the chamber 6 efficiently remove residues of resins / plastics. The part 4 '' is preferably operated pneumatically / hydraulically; for the appropriate control then appropriate connections are provided. By moving the lower part 4 '' of the transport channel 4 a gap forms between the two parts 4 ' and 4 '' out, in which the cutting unit 5 can intervene. The cutting unit is in this case a movable knife, but other separation units may also be provided, for example also separation units comprising a laser, etc. In this regard, reference is made to corresponding embodiments of the prior art.

The mixing chamber 6 has a feeder 7 for matrix material or starting components of the matrix material with which the impregnation of the separated rovings is to take place. Through the two-part transport channel 4 thus can be done easily a cleaning of the mixing chamber; the transport channel thus acts as a cleaning mechanism integrated in the deposition head. The mixing chamber can, for example, after each separation a strand by inserting the lower part 4 '' of the transport channel are cleaned by the mixing chamber.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3226290 [0007]
• EP 0320653 [0008]
• DE 102006035847 [0009]
• DE 102008012839 [0010]

Claims (16)

Laying head for the controlled depositing of at least one cut-to-length fiber strand, comprising at least one roller conveying device ( 2 ) and at least one, in the direction of 2 ) arranged transport channel ( 4 ), each with a guide for at least one endless fiber strand characterized in that the at least one transport channel ( 4 ) has an opening into which a separation unit arranged at the level of the opening (FIG. 5 ) can intervene to cut the fiber strand or the at least one transport channel ( 4 ) is formed in two parts in the conveying direction, wherein the two parts ( 4 ' . 4 '' ) of the transport channel ( 4 ) are movable relative to each other in the conveying direction and at the level of the forming by the relative movement of the two parts of the channel gap, a separation unit ( 5 ) is arranged for cutting the fiber strand. Laying head according to claim 1, characterized in that to the transport channel ( 4 ) a mixing chamber ( 6 ) for impregnating the at least one fiber strand connects. Laying head according to the preceding claim, characterized in that the mixing chamber ( 6 ) at least one feeder ( 7 ) for a matrix material for impregnating the fiber strand. Laying head according to one of the two preceding claims, characterized in that the mixing chamber ( 6 ) is dimensioned such that in the conveying direction of the mixing chamber ( 6 ) facing part of the transport channel ( 4 ) in a form-fitting manner into the mixing chamber ( 6 ) is insertable. Laying head according to one of the preceding claims, characterized in that between the roller conveyor unit and the at least one transport channel ( 4 ), in the wall of the at least one transport channel ( 4 ) and / or in the mixing chamber ( 6 ) at least one inlet opening ( 3 ) is provided for air. Laying head according to one of the preceding claims, characterized in that in the conveying direction following the mixing chamber ( 6 ) at least one fiber eye, which is preferably tempered, is arranged. Device for the controlled laying down of cut fibers, comprising a laying head movably arranged on the device according to one of the preceding claims. Method for depositing at least one cut fiber bundle with a laying head or a device according to one of the preceding claims, in which at least one endless fiber strand is connected to the at least one roller conveying device ( 2 ) in each case in the leadership of the at least one transport channel ( 4 ), and the at least one endless fiber strand by intervention of the separation unit ( 5 ) in the opening of the at least one transport channel ( 4 ) or the two parts of the respective transport channel ( 4 ) are moved in the conveying direction relative to each other, wherein a gap between the two parts of the respective transport channel ( 4 ) and the at least one fiber strand by means of the separation unit ( 5 ) is cut to length and then the cut fibers are discharged. Method according to the preceding claim, characterized in that before, during and / or after cutting to length in the mixing chamber ( 6 ) the at least one fiber strand is impregnated by application of matrix materials, preferably plastics or resins, in particular by spraying with the matrix materials or atomization of the matrix materials. Method according to the preceding claim, characterized in that after the impregnation and / or discharge of the at least one cut-to-length fiber, a cleaning of the mixing chamber ( 6 ) by blowing in compressed air and / or a cleaning medium via the at least one inlet opening of the mixing chamber ( 6 ) and / or by introducing the in the conveying direction of the mixing chamber ( 6 ) facing part of the transport channel ( 4 ) he follows. Method according to one of claims 8 to 10, characterized in that in the deposition head on the at least one, between the roller conveyor unit and the at least one transport channel ( 4 ), in the wall of the at least one transport channel ( 4 ) and / or in the mixing chamber ( 6 ) arranged inlet opening air is blown. Method according to one of claims 8 to 11, characterized in that the at least one fiber strand is formed and / or tempered with the at least one fiber eye. Method according to one of claims 8 to 12, characterized in that a plurality of fiber strands are guided with the same or different speed through the laying head. Method according to one of claims 8 to 13, characterized in that the cut fiber strands are stored in a mold for immediate further processing. Method according to one of claims 8 to 14, characterized in that by the relative movement of the two parts of the respective transport channel ( 4 ) a mechanical cleaning of the transport channel ( 4 ) he follows. Use of a laying head according to one of claims 1 to 6, a device according to claim 7 and / or a method according to any one of claims 8 to 15 in the manufacture of parts of fiber composite materials, for the controlled laying of fibers outside and / or in a component mold, for targeted drawing of any geometries, in the production of profiles, in the production of fiber composites, continuous fiber reinforced components, locally reinforced materials, locally reinforced support structures and / or hybrid reinforcement structures.

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