DE102016002766A1 - Method for detecting defects of a preform provided for further processing into a fiber composite component - Google Patents

Abstract

The invention relates to a method for detecting defects (S) of a preform (1) provided for further processing into a fiber composite component, in which the preform (1) formed by means of a preform tool using fiber textiles (1.1) and a fixing agent is subjected to the following method steps providing a probe receptacle (12) for guiding a probe (11) in contact with a preform surface (1.2) along a predetermined path on the preform surface (1.2), the probe (12) passing over a bump (1.3) of the preform surface (1.2) relative to the probe receptacle (12) is deflectable, guiding the probe head (11) by means of the probe holder (12) along the predetermined path, and detecting a by a bump (1.3) of the preform (1.2) initiated deflection of the probe head (11) by means of a detection device (12.1). Furthermore, the invention relates to a device for carrying out the method according to the invention.

Description

The invention relates to a method and a device for detecting defects of a preform provided for further processing into a fiber composite component, wherein the preform is produced by using fiber textiles and a fixing agent as well as under pressure and temperature by means of a preform tool.

For the production of fiber-reinforced plastic components (fiber composite components) and in particular of carbon fiber reinforced plastic components (CFRP components), inter alia, the resin transfer molding process (RTM process) is known. The production of a fiber composite component by means of this method is carried out in industrial applications in the following individual processes.

In a first process step, individual layers of a fiber material, such as, for example, carbon or glass are unrolled from a roll, cut and stacked into a corresponding stack (the so-called stack). By means of a binder, for example. Adhesive or by means of fixing seams, the fiber layers are fixed to each other to avoid accidental slippage of the individual fiber layers to each other. According to 1 there is such a stack 1 from several fiber layers as textile fibers 1.1 with different orientations. This stack 1 is then preformed 3-dimensional in the next process step, the so-called preform process by means of a preform tool. In this preform tool, the individual fiber layers 1.1 heated under pressure and temperature and formed via stamp or vacuum film, wherein the preform generated by the preform tool at least partially corresponds to the later component shape of the fiber composite component to be produced. The preform is then demolded and cooled.

Next is the preform 1 placed in an RTM tool as a mold and injected liquid matrix system in the preform and cured under pressure and temperature.

It has been shown that with high degrees of deformation or complex geometries of the preform, the preforming process is difficult to control. Thus, during the preforming process, in which the two-dimensional semifinished fiber product is brought into a substantially 3D shape that corresponds to the component contour, defects such as fiber distortion, fiber undulations, folds or thickenings frequently occur. This is geometrically conditioned and can not be prevented in the draping process for the most part.

If such errors lie on the preform surface, they can be optically detected. However, defects often occur within the preform 1 like this in 2 is shown. Due to the high friction between the inner fiber layers 1.1 Frequent errors occur here than in the outer fiber layers. The most common mistake is wrinkling, which leads to a local increase in thickness 1.3 with a thickness b (cf. 2 ) with respect to a desired thickness a (cf. 1 ) leads. This increase then leads only to a reject part or post-processing part in the RTM tool, since there is locally too high a fiber volume content at this defect S and the injected plastic can not flow through in the RTM tool. Therefore, there is an undesirable drying point in the cured component.

The object of the invention is to provide a method and a device for detecting defects of a preform provided for further processing into a fiber composite component, with which, in particular, wrinkling can be detected as a defect.

The first object is achieved by a method having the features of patent claim 1.

• – Bereitstellen einer Tastkopfaufnahme zum Führen eines Tastkopfes in Kontakt mit einer Preformoberfläche entlang einer vorgegebenen Bahn auf der Preformoberfläche, wobei der Tastkopf beim Überfahren einer Unebenheit der Preformoberfläche gegenüber der Tastkopfaufnahme auslenkbar ist,
• – Führen des Tastkopfes mittels der Tastkopfaufnahme entlang der vorgegebenen Bahn, und
• – Erfassen einer durch eine Unebenheit der Preformoberfläche initiierten Auslenkung des Tastkopfes mittels einer Erfassungsvorrichtung.

In this method for the detection of defects of a preform provided for further processing into a fiber composite component, the preform formed by means of a preform tool using fiber textiles and a fixing agent is tested with the following method steps:

• Providing a probe receptacle for guiding a probe in contact with a preform surface along a predetermined path on the preform surface, wherein the probe is deflectable when passing over a unevenness of the preform surface with respect to the probe receptacle,
• - Guide the probe by means of the probe recording along the predetermined path, and
• - Detecting a initiated by an unevenness of the preform surface deflection of the probe by means of a detection device.

With this method according to the invention, defects within a preform are detected in a simple manner.

According to an advantageous embodiment of the method according to the invention the probe is pressed with a defined force on the preform surface.

The second-mentioned object is achieved by a device having the features of patent claim 3.

• – einem Tastkopf und einer Tastkopfaufnahme, wobei der Tastkopf schwenkbeweglich mit der Tastkopfaufnahme derart verbunden ist, dass beim Führen des Tastkopfes in Kontakt mit der Preformoberfläche entlang einer vorgegebenen Bahn auf der Preformoberfläche gegenüber der Tastkopfaufnahme durch Kontaktierung einer Unebenheit der Preformoberfläche ausgelenkt wird, und
• – einer Erfassungsvorrichtung, die ausgebildet ist die durch eine Unebenheit der Preformoberfläche initiierte Auslenkung des Tastkopfes zu erfassen.

This device for detecting defects for further processing into a Fiber composite component provided preform, wherein the preform is made using fiber textiles and a fixing agent by means of a preform tool is formed with

• A probe and a probe receptacle, the probe being pivotally connected to the probe receptacle such that when the probe is guided in contact with the preform surface along a predetermined path on the preform surface opposite the probe receptacle is deflected by contacting an unevenness of the preform surface, and
• - A detection device which is adapted to detect the unevenness of the preform surface initiated deflection of the probe.

With such a device, the inventive method can be implemented inexpensively. In particular, such a device can be integrated into a series production, for example, by the probe head is guided by means of a robot on the predetermined path and detected by the detection device deflection detected location and, for example, can be visually displayed. Thus, preforms can be manually reworked prior to insertion into the RTM tool.

Since not the entire surface of the preform can be scanned with the probe, it is possible on the basis of upstream drape simulations to identify previously critical areas of the preform for wrinkling. Thus, only this identified area needs to be scanned by means of the probe.

According to an advantageous embodiment of the device according to the invention, the probe head is pivotally connected to the probe head such that the probe is pressed with a defined force on the preform surface. This ensures a defined deflection of the probe relative to the probe receptacle.

A further advantageous development of the device according to the invention provides that the probe has a sensing roller and a sensing roller pivotally connected to the probe head recording probe arm, wherein the sensing roller is rotatably connected to the probe arm. Preferably, the scanning arm is inclined with respect to the Preformoberfläche with an inclination angle α less than 90 °.

Finally, in a further preferred embodiment of the device according to the invention, the detection device is designed such that a pivoting of the probe arm with respect to a tilt angle α having pivot position is to be detected. For this purpose, for example, a moment sensor can be used in which the scanning arm with the probe head pivotally connecting pivot axis, with which a change in angle is detected.

The invention will now be described in detail by means of an embodiment with reference to the accompanying figures. Show it:

1 a schematic representation of a flawless preform,

2 a schematic representation of a preform with a wrinkling as a defect, and

3 a schematic representation of an apparatus for detecting a defect in a preform.

Because the 1 and 2 are already described in detail in the introduction, will be referenced below, if necessary, only to these figures.

The 3 shows a device 10 for carrying out the method according to the invention, namely the detection of a within a preform 1 existing defect S. This defect S is caused by a wrinkling of a fiber layer 1.1 within the preform 1 , This defect S leads in this area to a thickening of the preform surface 1.2 So, to a bump 1.3 and thus to a thickness b with respect to a desired thickness a in a preform 1 without flaw S according to 1 ,

The device 10 includes a probe 11 with a probe arm 11.1 and a cylindrical follower roller 11.2 , where the feeler roll 11.2 at one end of the probe arm 11.1 by means of a rotation axis 11:20 is rotatably disposed and the other end of the probe arm 11.1 pivotable by means of a pivot axis 11:10 with a probe receptacle 12 connected is.

The probe holder 12 is with respect to the plane E on which the faulty preform 1 lies, arranged so that feeler roll 11.2 by means of the probe arm 11.1 with a defined force F on the preform surface 1.2 the preform 1 is pressed, with the probe arm 11.1 forms an acute angle α with the plane E. The force F can, for example, by means of a between the probe arm 11.1 and the probe receptacle 12 tensioned spring element 11.3 be generated. Such a force F can also by means of a on the pivot axis 11:10 arranged torsion spring can be realized.

Will this probe receptacle 12 by means of a handling device, for example a robot (in 3 not shown) parallel to the plane E in the direction of R, is the sensing roller 11.2 rotated in the direction of rotation u and rolls on the preform surface 1.2 on a predetermined path. Will the feeler roll 11.2 pulled over the area of the defect S, changes due to the unevenness generated by this malfunction S 1.3 the inclination angle α to a value α + Δα. This angle change Δα is detected by a detection device 12.1 detected. This is, for example, in the pivot axis 11:10 arranged a torque sensor with which the angle change Δα is detected. Thus, the location of this defect S can be accurately detected and, for example, be displayed on a monitor.

The given path on the preform surface 1.2 has been chosen to identify critical areas for wrinkling in advance.

Thus, it is not necessary that the entire preform surface 1.2 by means of the feeler roller 11.2 is traversed.

LIST OF REFERENCE NUMBERS

1

preform

1.1

Fiber layer of the preform 1

1.2

Preform surface of the preform 1

1.3

Unevenness of the preform surface 1.2

10

Device for detecting defects

11

Probe of the device 10

11.1

Tastarm of the probe 11

11:10

swivel axis

11.2

Tracing roller of the probe 11

11:20

axis of rotation

11.3

spring element

12

probe receptacle

12.1

detection device

a

Thickness of the perfect preform 1

b

Thickness of the preform 1 with defect S

e

level

F

force

R

direction

S

void

u

direction of rotation

Claims (7)

Method for detecting defects (S) of a preform provided for further processing into a fiber composite component ( 1 ), in which by means of a preform tool using fiber textiles ( 1.1 ) and a fixing agent preform ( 1 ) is tested with the following method steps: - providing a probe receptacle ( 12 ) for guiding a probe ( 11 ) in contact with a preform surface ( 1.2 ) along a predetermined path on the preform surface ( 1.2 ), wherein the probe ( 12 ) when driving over a bump ( 1.3 ) of the preform surface ( 1.2 ) opposite the probe receptacle ( 12 ) is deflectable, - guiding the probe ( 11 ) by means of the probe receptacle ( 12 ) along the predetermined path, and - detecting a by a roughness ( 1.3 ) of the preform surface ( 1.2 ) initiated deflection of the probe ( 11 ) by means of a detection device ( 12.1 ). Method according to Claim 1, in which the probe head ( 11 ) with a defined force (F) on the preform surface ( 1.2 ) is pressed. Contraption ( 10 ) for detecting defects (S) of a preform provided for further processing into a fiber composite component ( 1 ), the preform ( 1 ) using fiber textiles ( 1.1 ) and a fixing means is produced by means of a preform tool is formed with - a probe head ( 11 ) and a probe receptacle ( 12 ), wherein the probe ( 11 ) pivotally with the probe receptacle ( 12 ) is connected in such a way that when guiding the probe ( 11 ) in contact with the preform surface ( 1.2 ) along a predetermined path on the preform surface ( 1.2 ) opposite the probe receptacle ( 12 ) by contacting a bump ( 1.3 ) of the preform surface ( 1.2 ), and - a detection device ( 12.1 ), which is formed by a roughness ( 1.3 ) of the preform surface ( 1.2 ) initiated deflection of the probe ( 11 ) capture. Contraption ( 10 ) according to claim 3, wherein the probe head ( 11 ) with the probe receptacle ( 12 ) is pivotally connected such that the probe ( 11 ) with a defined force (F) on the preform surface ( 1.2 ) is pressed. Contraption ( 10 ) according to claim 3 or 4, wherein the probe head ( 11 ) a feeler roll ( 11.2 ) and one the follower roller ( 11.2 ) pivotally with the probe receptacle ( 12 ) connecting probe arm ( 11.1 ), wherein the feeler roller ( 11.2 ) rotatable with the probe arm ( 11.1 ) connected is. Contraption ( 10 ) according to claim 5, wherein the probe arm ( 11.1 ) opposite the preform surface ( 1.2 ) inclined with an inclination angle (α) is less than 90 ° aligned. Contraption ( 10 ) according to claim 5 or 6, in which the detection device ( 12.1 ) is formed, a pivoting of the sensing arm ( 11.1 ) with respect to a tilt angle (α) having pivot position to detect.

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