RU2420405C2 - Tool and method of producing parts from composite materials outside autoclave (versions) - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed method comprises arranging composite material prepreg tapes or bundles on tool that repeats the shape of a part to be produced. Then, said material is compacted and partially solidified unless a layer of the part is made. Said stage is repeated unless a stack is produced for part fabrication. Now part last layer is solidified to preset degree. Proposed method comprises arranging composite material prepreg tapes or bundles on tool that repeats the shape of a part to be produced. Then, said material is compacted and partially solidified unless a layer of the part is made. Note here that layer arranged under that being laid is first solidified. Said stage is repeated unless a stack is produced for part fabrication. Stack of layers produced, the part is solidified by local heating of its surface by microwave radiator. Invention covers the tools to implement above described method.

EFFECT: reduced time, costs and power consumption.

17 cl, 3 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a tool and method for manufacturing samples of composite materials, and more particularly, to a tool and method for manufacturing outside an autoclave, the results of which are comparable to methods including the step of curing in an autoclave.

State of the art

Composite materials are becoming increasingly attractive for a wide range of applications in various industries, such as the aviation industry, the marine industry, the automotive industry or the sports industry, due to their high resistance and resistance / weight ratio.

Composite materials commonly used in the aforementioned industries consist of fibers or bundles of fibers embedded in a thermosetting or thermoplastic resin, in the form of a pre-impregnated material or “prepreg”.

Composite material is formed from many layers of pre-impregnated material. Each layer of pre-impregnated material is formed from fibers or bundles of fibers that can be cross-linked to form different types of fabrics, or can be directed in the same direction, forming unidirectional ribbons. These fibers or bundles of fibers are impregnated with resins (thermosetting or thermoplastic resins), which in many cases are partially polymerized.

At present, and especially in the aerospace industry, composite materials are widely used, consisting of an organic matrix consisting of continuous fibers and based on mainly epoxy resins and carbon fibers.

The use of parts of this type increased, especially in the aviation industry, until it reached the current situation in which composite materials consisting of a matrix consisting of epoxy resin and carbon fibers can be considered the most widely used version of structural elements. This situation has stimulated and continues to stimulate the development of manufacturing methods that ensure the manufacture of elements with the required quality many times and with an acceptable cost of manufacture.

Regarding the arrangement of layers of pre-impregnated material for the "formation" of parts from composite material, there are several methods that correspond to the available means for their placement and especially manual stacking and automatic stacking.

When manually stacking the foot, the operator stacks various layers of pre-soaked material in the foot with the required orientation and dimensions.

With automatic stacking in the foot, the robotic system is responsible for placing various layers of pre-impregnated material with the desired orientation and location and cutting to a specific length.

According to the pre-impregnated material used and its width after laying, there are two main types of automatic stacking:

- automatic layering (ATL automatic lay-up): the robotic system places pre-impregnated material in the form of more or less wide strips to cover flat surfaces or surfaces with one curvature.

- placement of fibers (FP fiber placement): the robotic system places very narrow sets of strips to cover surfaces with double curvature.

A method of manufacturing composite materials from a given plurality of layers (multilayer material) usually requires compaction to obtain the required volume of fibers and to remove cavities and air discharged from the composite material and a curing process that provides crosslinking of the polymer chains of the fiber impregnating resin.

These parts have traditionally been manufactured by applying pressure and vacuum (as a means to seal) and by applying heat (as a means to obtain crosslinking of polymer chains), especially in an autoclave in which a controlled atmosphere is created.

The period of time spent on manufacturing a part from pre-impregnated material is equal to the sum of the time periods spent on each of the necessary processes: stacking successive layers of pre-impregnated material forming this part, applying vacuum (as one of the means for sealing) and curing parts in an autoclave under the influence of pressure (compaction) and heat (obtaining cross-linking of polymer chains). The total time is usually significant, and the higher the complexity and number of layers in the foot, the greater the total time involved.

Another important aspect is the high cost of manufacturing parts from composite materials and the particularly high cost of energy required by the autoclave.

Therefore, the industry is constantly in need of new methods that provide a reduction not only in time but also in the energy required to manufacture parts from composite materials.

The aim of the present invention is to satisfy this need.

SUMMARY OF THE INVENTION

In a first aspect, the present invention describes a tool for manufacturing parts from composite materials outside an autoclave, comprising the following elements:

- a movable table containing an upper surface having the shape of a workpiece;

- a movable head on said table, equipped with automatic means for accommodating the tapes or bundles of the composite material in the form of a prepreg, means for densifying the composite material and means for emitting microwaves to cure the composite material.

The tool is preferably made in such a way that moving the head and the upper surface of the stacking table provides stacking to form the desired part, and so that the upper surface can rotate around an axis located in its center and move along the stacking table in the foot, and the head can be moved along the entire width of the table for stacking in the foot.

Said sealing means preferably includes a roller and an ultrasonic device.

The head is preferably made in such a way that it can have any operating state of said means, so also that the operating procedure of said means can be changed and the distance between said means can be changed.

In a second aspect, the present invention describes a method for manufacturing parts from composite materials outside an autoclave, comprising the following steps:

a) placing the composite material in the form of ribbons or bundles of the prepreg on the table of the said tool, compacting it and partially curing it after it is placed until a layer of the part is formed;

b) repeating the previous step until stacking is complete to form the part;

c) curing the last layer of the part.

In steps a) and b), the curing of the composite material is preferably carried out by local application of heat to it, after its placement, using a microwave emitter.

In a third aspect, the present invention describes a method of manufacturing parts from composite materials outside an autoclave, comprising the following steps:

- placement of the composite material in the form of a tape or bundles of prepreg on the table of the aforementioned tool, compacting it after its placement until a layer of the part is formed;

- repeating the previous step until stacking is complete to form the part;

- curing the part through local application of heat to its surface using a microwave emitter.

In relation to the present invention, a composite material refers to any material consisting of an organic matrix (epoxy resin, bismaleimide, polyimide, phenol, vinyl ether, etc.) and continuous reinforcing fibers (carbon, ceramic, glass, organic, polyamide, PBO, etc. )

Other features and advantages of the present invention will be apparent from the following description of an exemplary embodiment in conjunction with the accompanying drawings.

Brief Description of the Drawings

Figure 1 depicts a schematic view of a tool head in accordance with the present invention.

Figure 2 and 3 depict schematic perspective views of a tool in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In a preferred embodiment illustrated in the drawings, the tool 9 in accordance with the present invention comprises a stacking table 11 with an upper surface 13 including a portion having the shape of a workpiece and a head 15 resting on the frame 17. Table 11 includes includes means allowing the upper surface 13 to move along the table and rotate around an axis located in its central part, and the frame 17 includes means for moving the head 15 along the width of ol 11.

Head 15 contains:

- an automatic means for placing the tapes 19 of the composite material in the form of a prepreg, including a drum of pre-impregnated material 31, a controlled cleaning device 33, a heated sealing roller 35 and a separating paper drum 37;

- sealing means for sealing the prepreg layers, including a heated and / or cooled sealing roller 39 and an ultrasonic sealing means 41;

- a means 25 for emitting microwaves.

The tool 9 is made in such a way that, on the one hand, the head 15 can be placed at different heights above the table 11, and on the other hand, it can drive all or part of the said means. Thus, for example, the tool 9 can be made in such a way that the automatic means for accommodating the tapes 19, the sealing means and the means for emitting microwaves 25 are actuated, which will usually occur during stacking to form the part, or the tool can be made in such a way that only means 25 for emitting microwaves is actuated, which will occur in cases where separate operations are required to cure the part.

However, the tool 9 is designed in such a way that the arrangement of the said means can be changed so that they can act in a different order.

In this sense, one possible arrangement could be one in which the procedure would be as follows: the first will be an automatic means for receiving the tape, the second will be a sealing means and the third will be a means 25 for emitting microwaves. In this case, the means for emitting microwaves cures the layer, which is in the process of being stacked.

In an alternative arrangement, the procedure may be as follows: the first is a means 25 for emitting microwaves, the second is an automatic means for accommodating the tape and the third is a sealing means. In this case, the means for emitting microwaves cures the layer located under the layer, which is in the process of laying in the foot.

The characteristics of the various components of the tool 9 and, in particular, the required power of the microwave emitter 25 will vary depending on the characteristics of the workpiece and, in particular, on its thickness. Consequently, the microwave emitter 25 must be easily adaptable in order to operate at different powers in such a way as to provide a change in the power emitted throughout the curing process of the material.

Only as an illustrative example, below are some characteristics of a preferred embodiment of tool 9:

- maximum stacking speed in the foot (maximum speed with which the head 15 can move): 70 m / min;

- the power of the emitter of 25 microwaves is in the range from 0.1 kW to 10 kW;

- the frequency of the ultrasonic sealing device 41 is in the range from 20 kHz to 40 kHz.

A significant advantage of the present invention is that the tool 9 can have one control panel for the various tools mentioned above, which simplifies their maintenance and management.

The following describes the method in accordance with the present invention, which is intended for the joint use of various technical means for the manufacture of parts from composite materials "outside the autoclave", in particular the following technical means:

- FP and ATL for stacking composite material;

- ultrasonic vibrations to provide appropriate compaction between the various layers of the composite material;

- microwaves to ensure crosslinking of the polymer chains of the composite material.

In the first embodiment, the method in accordance with the present invention is implemented as follows.

Part manufacturing begins with the placement of the first layer of material. In this operation, using, for example, the tool 9 described above, the prepreg located on the drum 31 passes through the cleaning device 33 towards the sealing roller 35, which places it on the upper surface 13 of the stacking table 11. Separation paper attached to the prepreg is wound onto the drum 37. Then, the sealing roller 39 and the ultrasonic device 41 carry out sealing operations on the prepreg tape 19 located on the stacking table 11. Then, the material is cured to a certain extent using an emitter of 25 microwaves. This operation is carried out by the corresponding movement of the head 15 of the tool 9 until all the material corresponding to the layer of the part is laid, sealed and partially cured.

This layer cannot be completely cured, since it must have a certain degree of stickiness so that the next layer can be appropriately placed on it.

The next layer will be placed on the first layer in the same way (ATL or FP, sealing roller, ultrasonic device), and the action of the 25 microwaves emitter will partially cure the second layer, as well as the first layer.

Thus, the placement of other layers will entail successive curing cycles of the previous layers until the desired degree of curing is achieved. And finally, to ensure proper curing of the last layer after its placement, it is necessary to carry out a special curing cycle through the action of an emitter of 25 microwave waves.

In one embodiment of the method, an 80 mm wide prepreg tape was laid using an ATL head at a speed of 2 m / min, a sealing device frequency of 20 kHz, and a microwave power of 0.1 kW.

In another embodiment of the method in accordance with the present invention, the curing of the various layers is carried out after stacking.

Thus, when using the tool 9, the various layers forming the part are stacked in the same manner as described above and compacted one after another using the heating roller 39 and the ultrasonic sealing device 41.

After all layers of the composite material, having the appropriate dimensions and orientation, are laid down, they are cured using a 25 microwave emitter, making the necessary passes with the head 15 until the required polymerisation of the polymer chains is achieved.

In the preferred embodiment described above, any modifications may be made within the scope of the invention defined by the following claims.

Claims (17)

1. A method of manufacturing parts from composite material outside the autoclave, characterized in that it includes the following steps:
a) placing the composite material in the form of strips or beams of a prepreg on an instrument having the form of a workpiece, its compaction and its partial curing after being placed during stacking until the layer of the part is completed;
b) repeating step a) until stacking is completed to form the part;
c) curing the last layer of the part to the desired degree of curing. 2. The method according to claim 1, characterized in that in steps a) and b), the curing of the composite material is carried out by local application of heat to it after it is placed using a microwave emitter. 3. A tool (9) for manufacturing parts from a composite material outside the autoclave according to the method according to claim 1, characterized in that it contains:
a) a stacking table (11) comprising a movable upper surface (13) having the shape of a workpiece;
b) a movable head (15) on said stacking table (11) equipped with the following means:
b1) an automatic means for placing the composite material in the form of tapes (19) or prepreg bundles;
b2) sealing means for sealing the composite material;
b3) a means (25) for emitting microwaves for curing the composite material during stacking to form the desired part. 4. The tool (9) according to claim 3, characterized in that it is made in such a way that moving the head (15) and the upper surface (13) of the table (11) for stacking provide stacking for the formation of the desired part. 5. The tool (9) according to claim 4, characterized in that it is made in such a way that the upper surface (13) can rotate around an axis located in its center and move along the table (11) for stacking, and the head can move along the entire width of the table (11) for stacking. 6. The tool (9) according to claim 3, characterized in that said sealing means includes a roller (39) and an ultrasonic device (41). 7. The tool (9) according to claim 3, characterized in that the head is made in such a way that it can have any working state of the said means. 8. The tool (9) according to claim 3, characterized in that the head is made in such a way that the procedure for the said means can be changed. 9. The tool (9) according to claim 3, characterized in that the head is made in such a way that the distance between the said means can be changed. 10. A method of manufacturing parts from composite material outside the autoclave, characterized in that it includes the following steps:
a) the placement of the composite material in the form of strips or bundles of prepreg on an instrument having the form of a manufactured part, its compaction after its placement during stacking until the layer of the part is completed, and during this placement the layer located under a layer that is being laid;
b) repeating step a) until stacking is completed to form the part; and
c) after completion of stacking, the curing of the part by local application of heat to its surface using a microwave emitter. 11. Tool (9) for the manufacture of parts from composite material outside the autoclave according to the method of claim 10, characterized in that it contains:
a) a stacking table (11) comprising a movable upper surface (13) having the shape of a workpiece;
b) a movable head (15) on said stacking table (11) equipped with the following means:
b1) an automatic means for placing the composite material in the form of tapes (19) or prepreg bundles;
b2) sealing means for sealing the composite material;
b3) a means (25) for emitting microwaves for curing the composite material during stacking to form the desired part. 12. The tool (9) according to claim 11, characterized in that it is made in such a way that moving the head (15) and the upper surface (13) of the stacking table (11) provides stacking to form the desired part. 13. The tool (9) according to item 12, characterized in that it is made in such a way that the upper surface (13) can rotate around an axis located in its center and move along the table (11) for stacking, and the head can move along the entire width of the table (11) for stacking. 14. The tool (9) according to claim 11, characterized in that said sealing means includes a roller (39) and an ultrasonic device (41). 15. The tool (9) according to claim 11, characterized in that the head is made in such a way that it can have any operating state of the said means. 16. The tool (9) according to claim 11, characterized in that the head is made in such a way that the procedure for the said means can be changed. 17. The tool (9) according to claim 11, characterized in that the head is made in such a way that the distance between the said means can be changed.

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