DE102013105115A1 - Method for producing a preform, embroidery machine for carrying out the method and corresponding preform - Google Patents

Abstract

Method for producing a preform (1) for a fiber composite material with an embroidery machine (2), comprising at least the following steps: a) providing a carrier material (3) in an embroidery frame (4); b) embroidering at least one sliver (5) on the carrier material (3) with a thread (6) in a first embroidery area (7), the thread (6) being caused by a stitch movement of an embroidery needle (8) with a first stitch length (9) is embroidered and wherein a synchronization between a movement of the embroidery frame (4) and the stitch movement of the embroidery needle (8) is activated during embroidery; c) stopping the sticking of the at least one sliver (5); d) moving the embroidery frame (4) relative to the embroidery needle (8) to at least one second embroidery area (10) which is at a distance (11) from the first embroidery area (7), the synchronization being carried out while the embroidery frame (4) is being moved between the movement of the embroidery frame (4) and the stitching movement of the embroidery needle (8) is deactivated, and the at least one fiber band (5) is deposited on the carrier material (3) while the embroidery frame (4) is moving; and e) embroidering the at least one sliver (5) onto the carrier material (3) in the second embroidery area (10), the synchronization between the movement of the embroidery frame (4) and the stitch movement of the embroidery needle (8) being activated during embroidery.

Description

The present invention relates to a method for producing a preform for a fiber composite material with an embroidery machine, a corresponding embroidery machine and a preform for producing a fiber composite material. The process, the embroidery machine and the preform are used, inter alia, for the production of high-strength structural components.

Fiber composites, in particular fiber-reinforced plastics, which consist of reinforcing fibers embedded in a polymer matrix, are known from the prior art. The reinforcing fibers in such a material have the task of transmitting external loads. The matrix serves in particular to fix the reinforcing fibers in a desired position, to introduce the external loads into the reinforcing fibers, to protect the reinforcing fibers from environmental influences and / or to support the reinforcing fibers under pressure loading.

The mechanical properties of FRP components depend on the fiber material, the matrix material, the length of the reinforcing fibers, the fiber content and the fiber orientation. To adapt components made of fiber composite materials to component-specific loads, it is necessary to construct the components from a high proportion of force-oriented fibers. As a result, particularly high weight-specific stiffness and strength of the component can be achieved. From the WO 2007/128364 A1 For example, a method is known in which ribbon-shaped rovings of carbon filaments, glass filaments, natural fibers, ceramic fibers or chemical fibers are embroidered on a fabric-like carrier material.

Although the aforementioned method has already proven very successful in practice, the problem with such methods is that they do not have a sufficient production speed, in particular for mass production.

The object of the invention is therefore to solve the problems described with reference to the prior art at least partially and in particular to provide a method for producing a preform for a fiber composite material with an embroidery machine, which is characterized by a particularly high production rate. In addition, an embroidery machine is to be specified, can be produced with the preforms for a fiber composite material with a particularly high production speed. Furthermore, a preform for a fiber composite material is to be specified that can be produced with a particularly high production speed.

These objects are achieved with a method, an embroidery machine and a preform according to the features of the independent claims. Further advantageous embodiments of the invention are specified in the dependent formulated claims. It should be noted that the features listed individually in the dependent formulated claims can be combined with each other in any technologically meaningful manner and define further embodiments of the invention. In addition, the features specified in the claims are specified and explained in more detail in the description, wherein further preferred embodiments of the invention are shown.

• a) Bereitstellen eines Trägermaterials in einem Stickrahmen;
• b) Feststicken mindestens eines Faserbandes auf dem Trägermaterial mit einem Faden in einem ersten Stickbereich, wobei der Faden durch eine Stichbewegung einer Sticknadel mit einer ersten Stichlänge gestickt wird und wobei während dem Feststicken eine Synchronisation zwischen einer Bewegung des Stickrahmens und der Stichbewegung der Sticknadel aktiviert ist;
• c) Stoppen des Feststickens des mindestens einen Faserbandes;
• d) Bewegen des Stickrahmens relativ zu der Sticknadel zu mindestens einem zweiten Stickbereich, der zu dem ersten Stickbereich einen Abstand aufweist, wobei während dem Bewegen des Stickrahmens die Synchronisation zwischen der Bewegung des Stickrahmens und der Stichbewegung der Sticknadel deaktiviert ist und wobei während dem Bewegen des Stickrahmens das mindestens eine Faserband auf dem Trägermaterial abgelegt wird; und
• e) Feststicken des mindestens einen Faserbandes auf dem Trägermaterial in dem zweiten Stickbereich, wobei während dem Feststicken die Synchronisation zwischen der Bewegung des Stickrahmens und der Stichbewegung der Sticknadel aktiviert ist.

The inventive method for producing a preform for a fiber composite material with an embroidery machine has at least the following steps:

• a) providing a carrier material in an embroidery frame;
• b) stitching at least one sliver on the carrier material with a thread in a first embroidery area, wherein the thread is embroidered by a stitch movement of an embroidery needle with a first stitch length and wherein during the stitching synchronization between a movement of the embroidery frame and the stitch movement of the embroidery needle is activated ;
• c) stopping the solid embroidery of the at least one sliver;
• d) moving the embroidery frame relative to the embroidery needle to at least a second embroidery area, which has a distance to the first embroidery area, wherein during the movement of the embroidery frame, the synchronization between the movement of the embroidery frame and the stitch movement of the embroidery needle is deactivated, and wherein during movement of the embroidery needle Embroidery frame, the at least one sliver is deposited on the carrier material; and
• e) firmly embroidering the at least one sliver on the carrier material in the second embroidery area, during synchronization the synchronization between the movement of the embroidery frame and the stitch movement of the embroidery needle is activated.

The method proposed here is carried out with an embroidery machine. In particular, the embroidery machine is a multi-head embroidery machine, in which a plurality of embroidery heads is arranged on a cross member above an embroidery frame that can be moved in a (horizontal) xy plane. The plurality of embroidery heads is through, in particular a common, main drive shaft drivable. Such embroidery machines are used for machine embroidery of a carrier material.

The preform to be produced is a preform or a semifinished fiber which can be used to produce a fiber composite. For this purpose, the preform or optionally several layers of the preform is embedded in a matrix. Polymers, such as duromers, elastomers or thermoplastics, are regularly used as the matrix.

To prepare the preform, the carrier material is first provided. The carrier material is a woven, nonwoven, carbon fiber fabric, glass fabric, scrim, a (textile) mat and / or a material soluble in heat, water or chemicals. The carrier material is preferably provided in the (horizontal) embroidery frame, in which the carrier material is in particular clamped flat. The embroidery frame is designed in particular in the manner of a border frame and is also referred to in the art as a pantograph. The provision, that is, a supply and / or a removal of the carrier material, also preferably takes place fully automatically.

According to step b) at least one sliver is embroidered on the carrier material with a thread in a first embroidery area. The at least one sliver is in particular ribbon-shaped rovings of carbon filaments, glass filaments, natural fibers, ceramic fibers and / or man-made fibers, for example of aramids. The at least one fiber band preferably has 6,000 individual filaments (6 K) up to 50,000 individual filaments (50 K). The thread is preferably a thread comprising polyester, polyamide, aramid or glass fiber, wherein monofilaments or threads may be present. The thread is embroidered by a stitch movement of an embroidery needle. The stitch movement is, in particular, a movement of the embroidery needle parallel to a longitudinal axis of the embroidery needle, in which the embroidery needle pierces the carrier material with the thread. The stitching of the at least one sliver preferably takes place with a zigzag stitch, by means of which the thread is fastened to the support material in a zigzag shape via the at least one sliver. The zigzag stitch has a first stitch length and a first stitch width. The first stitch length is, in particular on a straight section of the at least one sliver, a distance between two (in the direction of a longitudinal extension of the at least one sliver (directly) adjacent) needle stitches in the direction of an embroidery direction or in the direction of the longitudinal extent of the at least one sliver. The first stitch length preferably has 0.1 mm to 12.7 mm (millimeters), particularly preferably 5 mm to 10 mm (millimeters) and very particularly preferably 7 mm (millimeters). The first stitch width is a distance between two (in the direction of the longitudinal extension of the at least one sliver adjacent (directly)) pinholes in a direction orthogonal to the embroidery direction or in a direction orthogonal to the longitudinal extent of the at least one sliver direction. The first stitch width is preferably 1 mm to 12 mm (millimeters), particularly preferably 3 mm to 7 mm. In particular, the stitch width should be chosen so wide that the supplied sliver is certainly not pierced or injured by the needle in its full width. The first embroidery area is, in particular, an area in which the at least one sliver (continuous) with the first stitch length is embroidered on the carrier material. During the stitching of the at least one sliver, the embroidery frame is moved with the carrier material according to a predetermined embroidery pattern. The movement of the embroidery frame is always synchronized in known embroidery machines with the stitch movement of the embroidery needle. This ensures that the embroidery frame is not moved when the embroidery needle is inserted into the substrate. The synchronization between the movement of the embroidery frame and the stitch movement of the embroidery needle can be done either by a mechanical coupling of a drive train of the hoop with a drive train of the embroidery needle or by a control engineering coupling between the movement of the embroidery frame and the stitch movement of the embroidery needle. In the latter case, for example, detects a rotational movement of a main drive shaft of the embroidery head by means of a sensor by a control of the embroidery machine and the movement of the hoop are controlled by the controller in response to a rotational position of the main drive shaft. In this case, the movement of the embroidery frame is stopped once per revolution of the main drive shaft.

According to step c), the stitching of the at least one sliver is stopped at a (predetermined) end of the first embroidery area. In this case, in particular, the main drive shaft can be shut down by deactivating a drive of the main drive shaft or by decoupling the main drive shaft from the needle drive.

After stopping the solid embroidery of the at least one sliver, the embroidery frame is moved relative to the embroidery needle to at least a second embroidery area in step d). The at least one second embroidery area has a distance to the first embroidery area (along a longitudinal extent of the at least one fiber band), which is preferably greater than 12.7 mm (millimeters), particularly preferably greater than 50 mm (millimeters), completely more preferably greater than 200 mm (millimeters) or even greater than 500 mm (millimeters). It is essential here that during the movement of the embroidery frame, the synchronization between the movement of the embroidery frame and the stitch movement of the embroidery needle is deactivated. This ensures that the embroidery frame is movable independently of the stitch movement of the embroidery needle. This means, in particular, that the embroidery frame can be moved without limitation by means of a stitch length (embroidery-specific). In other words, the movement of the embroidery frame (apart from an acceleration phase at the beginning of the movement of the embroidery frame and a braking phase at the end of the movement of the embroidery frame) substantially at a constant speed, preferably between 10 mm / s (millimeters per second) - 500 mm / s (millimeters per second), more preferably 100 mm / s (millimeters per second) - 250 mm / s (millimeters per second). Furthermore, this means that the movement of the embroidery frame between the first embroidery area and the second embroidery area is continuous, that is, uninterrupted. This also means that the embroidery frame is freely movable, that is, in particular, that the movement of the embroidery frame is not interrupted by monitoring the position of the embroidery needle. Furthermore, during the movement of the embroidery frame, a deposition of the at least one sliver on the carrier material takes place. This also means in particular that the at least one sliver between the first embroidery area and the at least one second embroidery area is not separated, for example by a pair of scissors. It should be clarified at this point that the at least one sliver does not have to be deposited directly on the carrier material, but can also be deposited on sliver previously deposited on the carrier material, in particular in the case of a multi-layered deposit of the at least one sliver. Furthermore, between the first embroidery area and the at least one second embroidery area, preferably the thread is not separated, for example by a pair of scissors.

According to step d), the at least one sliver is embroidered on the carrier material in the second embroidery area and in this case the synchronization between the movement of the embroidery frame and the stitch movement of the embroidery needle is activated. The stitching of the at least one sliver in the second embroidery area preferably takes place with a second stitch length, which corresponds in particular to the first stitch length. The second embroidery area is in particular an area in which the thread is embroidered by a stitch movement of the embroidery needle (continuously) with the second stitch length.

Preferably, during step d), the thread is laid over the at least one sliver. This means in particular that the thread between the first embroidery area and the second embroidery area (once) is placed across the at least one sliver. This has the advantage that, despite the comparably large distance between the first embroidery area and the second embroidery area, between the first embroidery area and the second embroidery area, the at least one sliver receives at least a certain fixation on the carrier material.

It is also advantageous if the stitching takes place during steps b) and e) with a maximum of five stitches. In particular, the stitching takes place during steps b) and e) with 2 to 5 stitches. It has been found that such a comparatively small number of stitches is sufficient to sufficiently secure the at least one sliver on the carrier material. In addition, by such a limitation of the number of stitches, the production speed of the method can be further increased.

Furthermore, it is advantageous if the movement of the embroidery frame relative to the embroidery needle according to step d) takes place continuously.

In addition, it is advantageous if the distance between the first embroidery area and the at least one second embroidery area is 200 mm (millimeters) - 300 mm (millimeters). A distance of 250 mm (millimeters) has proven particularly advantageous.

Furthermore, it is advantageous if a plurality of fiber ribbons according to steps b) to e) are embroidered in a plurality of layers one above the other on the carrier material. It should be noted that the different layers can also lie in different directions, in particular according to a later loading of the preform.

In this case, it is detected, in particular, that the slivers in the plurality of layers are at least partially laid or arranged in different directions relative to one another. It when a final position of the sliver is stitched to the thread continuously with a third stitch length is particularly advantageous. In the final position of the sliver is that position of the sliver, which is the last embroidered on the substrate. The stitching is also in this case (as in step b)) by a zigzag stitch through which the thread is fixed in a zigzag on the carrier material via the at least one sliver. The third stitch length preferably has 0.1 mm to 12.7 mm (millimeters), particularly preferably 5 mm to 10 mm (millimeters), and very particularly preferably 7 mm (millimeters) on. This ensures that, on the one hand, all the layers of the at least one sliver are homogeneously fixed on the carrier material and, on the other hand, the preform has an even deformable structure.

According to a further aspect of the invention, an embroidery machine for producing a preform for a fiber composite material with a controller is proposed, wherein the controller is set up (and provided) for carrying out the method according to the invention. The embroidery machine proposed here is used for machine embroidering of the carrier material. The embroidery machine preferably has a plurality of embroidery heads, which are arranged in particular on a common (horizontal) carrying beam above an embroidery frame for a carrier material. Each embroidery head preferably has at least one supply reel for the at least one sliver. The at least one fiber sliver can be fed from the at least one supply spool, in particular tangentially, and can be fed to the embroidery head. For this purpose, the embroidery head has at least one laying device for the at least one sliver, with which the at least one sliver can be taken off the at least one supply coil and deposited on the carrier material. In addition, the embroidery head has an embroidery needle for firmly embroidering the at least one sliver on the carrier material. For this purpose, the needle is supplied with a thread for stitching the at least one sliver. The embroidery head is preferably fixedly attached to the embroidery machine, wherein the hoop located under the embroidery head with the support material with at least one drive at least in a horizontal x-y plane is adjustable relative to the embroidery needle.

The embroidery machine furthermore has a control with which preferably the majority of the embroidery heads, the stitch movement of the embroidery needle and / or the at least one drive of the embroidery frame can be controlled. The control is designed in particular in the manner of a CNC (Computerized Numerical Control) control and comprises at least one (programmable) computing unit.

According to yet another aspect of the invention, a preform for a fiber composite material with a carrier material is proposed, wherein on the carrier material at least one sliver with a thread in a first embroidery area and at least a second embroidery area is embroidered, wherein the first embroidery area and the at least one second embroidery area Embroidery area are spaced at a distance and wherein the at least one sliver between the first embroidery area and the at least one second embroidery area is continuously stored on the carrier material. The preform according to the invention is produced in particular by the process according to the invention. In that regard, reference is made to the description of the method with respect to the individual features of the preform. It should be clarified at this point, however, that continuous filing of the at least one sliver between the first embroidering area and the at least one second embroidering area means that the at least one sliver between the first embroidering area and the at least one second embroidering area is not separated.

It is also advantageous if a plurality of slivers are embroidered on the carrier material in several layers one above the other on the carrier material and wherein a final layer is stitched to the thread continuously with a third stitch length.

The invention and the technical environment will be explained in more detail with reference to FIGS. It should be noted that the figures show particularly preferred embodiments of the invention, but this is not limited thereto. The same components in the figures are provided with the same reference numerals. They show schematically:

1 a first embodiment of a preform in a plan view;

2 a second embodiment of a preform in a longitudinal section; and

3 : an embroidery machine.

The 1 shows a preform 1 in a plan view, wherein on a carrier material 3 two slivers 5 each with a thread 6 are embroidered. The two slivers 5 each have a first embroidery area 7 and second embroidery areas 10 on, each by a distance 11 are spaced. At the upper sliver 5 is the thread 6 between the first embroidery area 7 and the second embroidery area 10 across the sliver 5 whereas at the lower sliver 5 the string 6 between the first embroidery area 7 and the second embroidery area 10 parallel to a longitudinal extent of the sliver 5 is laid. The string 6 is in the first embroidery area 7 with a first stitch length 9 and a first stitch width 23 on the carrier material 3 attached with a zigzag stitch. In the second embroidery areas 10 is the thread 6 with a second stitch length 22 on the carrier material 3 attached with a zigzag stitch. Furthermore, in the upper sliver 5 the string 6 in the first embroidery area 7 With 5 engravings 12 attached.

The 2 shows a second embodiment of a preform 1 in a longitudinal section. In this embodiment are on the support material 3 three slivers 5 one above the other in two layers 13 and a final position 14 firmly sewn. The strings 6 in the area of stitches 12 the layers 13 are shown schematically with solid lines. The strings 6 in the area of stitches 12 the final position 14 In contrast, are shown schematically by dashed lines. The layers 13 each have a first embroidery area 7 and two second embroidery areas 10 on, each with a distance 11 are spaced. Furthermore, the thread 6 in the first embroidery area 7 the layers 13 with a first stitch length 9 and in the second embroidery area 10 the layers 13 with a second stitch length 22 on the carrier material 3 firmly sewn. It can also be seen that the final position 14 with the thread 6 continuously with a third stitch length 15 on the carrier material 3 is attached.

The 3 shows a schematic representation of an embroidery machine 2 that have a plurality of embroidery heads 17 of which in the 3 however, by way of example only one is shown. The embroidery head 17 has an embroidery needle 8th on, by means of a first drive 18 for driving a stitch movement can be driven parallel to its longitudinal axis. The embroidery head 17 further includes a coil 21 for sliver 5 , from which the sliver 5 by means of a laying device 20 on the carrier material 3 can be stored. The carrier material 3 is also in an embroidery hoop 4 clamped by a second drive 19 can be driven in an xy plane. The sliver 5 is through the laying device 20 on the carrier material 3 filed and through the embroidery needle 8th with a thread 6 on the carrier material 3 firmly sewn. The laying device 20 , which is also known as zig-zag Leger, it must always be aligned to the current stitch direction so that the sliver 5 always frontal in front of the embroidery needle 8th is fed, regardless of the direction in which the sliver 5 is relocated. Furthermore, the embroidery machine includes 2 a controller 16 , the data leading to the first drive 18 and the second drive 19 connected is. The control 16 is set up and provided for carrying out the method according to the invention.

The present invention is characterized in particular by a particularly high production speed of a preform.

LIST OF REFERENCE NUMBERS

1

 preform

2

 embroidery machine

3

 support material

4

 hoop

5

 sliver

6

 thread

7

 first embroidery area

8th

 embroidery needle

9

 first stitch length

10

 second embroidery area

11

 distance

12

 Sting

13

 location

14

 final location

15

 third stitch length

16

 control

17

 Stick head

18

 first drive

19

 second drive

20

 laying device

21

 Kitchen sink

22

 second stitch length

23

 first stitch width

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

• WO 2007/128364 A1 [0003]

Claims (10)

Process for producing a preform ( 1 ) for a fiber composite material with an embroidery machine ( 2 ), comprising at least the following steps: a) providing a carrier material ( 3 ) in an embroidery hoop ( 4 ); b) embroidering at least one sliver ( 5 ) on the carrier material ( 3 ) with a thread ( 6 ) in a first embroidery area ( 7 ), whereby the thread ( 6 ) by a stitch movement of an embroidery needle ( 8th ) with a first stitch length ( 9 ) and wherein during the stitching synchronization between a movement of the embroidery frame ( 4 ) and the stitch movement of the embroidery needle ( 8th ) is activated; c) stopping the solid embroidery of the at least one sliver ( 5 ); d) moving the embroidery frame ( 4 ) relative to the embroidery needle ( 8th ) to at least a second embroidery area ( 10 ) leading to the first embroidery area ( 7 ) a distance ( 11 ), while moving the embroidery frame ( 4 ) the synchronization between the movement of the hoop ( 4 ) and the stitch movement of the embroidery needle ( 8th ) and is deactivated while moving the embroidery frame ( 4 ) the at least one sliver ( 5 ) on the carrier material ( 3 ) is filed; and e) embroidering the at least one sliver ( 5 ) on the carrier material ( 3 ) in the second embroidery area ( 10 ), during the stitching synchronization between the movement of the embroidery frame ( 4 ) and the stitch movement of the embroidery needle ( 8th ) is activated. Method according to claim 1, wherein during step d) the thread ( 6 ) over the at least one sliver ( 5 ) is placed. Method according to one of the preceding claims, wherein the stitching during steps b) and e) with a maximum of five stitches ( 12 ) he follows. Method according to one of the preceding claims, wherein the movement of the embroidery frame ( 4 ) relative to the embroidery needle ( 8th ) takes place continuously according to step d). Method according to one of the preceding claims, wherein the distance ( 11 ) between the first embroidery area ( 7 ) and the at least one second embroidery area ( 10 ) Is 100 mm-300 mm. Method according to one of the preceding claims, wherein a plurality of slivers ( 5 ) according to steps b) to e) in several layers ( 13 ) one above the other on the carrier material ( 3 ) is embroidered. Method according to claim 6, wherein a final position ( 14 ) of the sliver ( 5 ) with the thread ( 6 ) continuously with a third stitch length ( 15 ) is embroidered. Embroidery machine ( 2 ) for the production of a preform ( 1 ) for a fiber composite, comprising a controller ( 16 ), whereby the controller ( 16 ) is arranged to carry out the method according to one of the preceding claims. Preform 1 ) for a fiber composite material, comprising a carrier material ( 3 ), wherein on the carrier material ( 3 ) at least one sliver ( 5 ) with a thread ( 6 ) in a first embroidery area ( 7 ) and at least one second embroidery area ( 10 ), the first embroidery area ( 7 ) and the at least one second embroidery area ( 10 ) with a distance ( 11 ) and wherein the at least one sliver ( 5 ) between the first embroidery area ( 7 ) and the at least one second embroidery area ( 10 ) continuously on the carrier material ( 3 ) is stored. Preform 1 ) according to claim 9, wherein on the carrier material ( 3 ) a plurality of slivers ( 5 ) in several layers ( 13 ) one above the other on the carrier material ( 3 ) and a final position ( 14 ) with the thread ( 6 ) continuously with a third stitch length ( 15 ) is embroidered.

Images