DE3523697A1 - Process for producing a moulding from a thermoplastic reinforced with continuous fibres - Google Patents

Abstract

In a process for producing a moulding from a thermoplastic reinforced with continuous fibres, in which the starting material comprises plate-shaped or strip-shaped layers of the thermoplastic reinforced with continuous fibres, in order to make possible a deformation of the layers without losses in strength and, if appropriate, a bonding of a plurality of layers to form a one-piece moulding, it is proposed that the layers be laid on a heated mould surface and that they be heated by this mould surface with such an intensity that the layer becomes deformable and is softened on its side facing the mould surface, and that the layer be pressed against the mould surface at a point in time after the commencement of heating at which the side facing away from the mould surface has not yet softened and is not yet adhesive.

Description

The invention relates to a method for producing a Shaped body from a thermo reinforced with continuous fibers plastic, in which the base material is or ribbon-shaped layers of ther reinforced with continuous fibers plastic are used.

Continuous fiber reinforced plastics have been used to manufacture highly stressed components, for example in aviation, enforced, they are increasing for other industries used more. So far, mainly fiber was strengthened thermosetting plastics. Continuous fiber ver strengthened thermoplastics, despite their Advantages compared to fiber-reinforced thermosetting plastic fen (e.g. better impact strength, problem-free storage) because their processing difficulties put.

The usual way of making components from endless fiber-reinforced thermoplastics leads over the Production of flat panels, some of which are subsequently divided into several  Ren stages to be further formed into components. It is but inserting several individual layers into curved shapes and subsequent pressing, as is the case with fiber-reinforced thermosetting plastics is common because of the high egg stiffness of the individual layers of thermoplastic art fabrics not possible.

In the previously used manufacturing techniques endless fiber stronger thermoplastic materials result from ei During the forming process, wavy fibers in the corners, which Reduce load capacity. For joining several layers For example, adhesives are used, but they are suitable Do not use glue for high temperature resistant thermoplastics available so that this technique is resistant to high temperatures Shaped bodies can not be used.

A direct connection of the thermoplastics by melting the Connection point by means of external heat supply has so far been possible only be done in a special form, otherwise the plates shaped pre-products completely ver their dimensional stability loren. Ultrasonic welding in the connection area is included larger parts because of the amount of energy required matically, heating in the connection area by means of heating wire has the disadvantage that the heating wires in the component back have to stay.

Rivet connections are very complex and have the disadvantage that that fibers are cut through the rivet holes. The metallic rivet also causes corrosion problems generated.  

It is the object of the invention to produce a mold body made of continuous fiber reinforced, plate or ribbon-shaped To develop thermoplastics with the also complicated shape bodies with good strength properties in a simple manner can be produced.

This task is described in the method of the introduction Art solved according to the invention in that the layers on egg ne heated mold surface and put them through this mold surface heated so much that the layer was deformable and at its the Molding surface facing side is softened, and that one Position at a time after the start of heating to the mold surface, to the side facing away from the molding surface not yet softened and not yet sticky.

By placing an endless fiber-reinforced layer on one heated mold surface, the overlaid layer becomes from its bottom side increasingly heated. It is essential that by the low thermal conductivity of thermoplastic art a temperature gradient arises inside the layer that is called the location on its bottom facing the mold surface side may already be softened while holding on to its shape surface facing away from the surface is still firm and not sticky. This makes it possible to use a suitable position Tool, for example by means of a roller, on the molding surface press and so their shape of the contour of the molding surface optimal adapt. Since the position on its facing the molding surface Side is softened, it adapts easily to the molding surface , with the fibers inside the layer also being formed  do not experience reorientations that reduce strength.

When you cool the rollers, you can press on the layer make the molding surface even when the temperature already on the side of the layer facing away from the molding surface is relatively high, because you can in the pressure range of the Counteract warming and thus softening. This is particularly advantageous when using very thin layers, moreover, by using chilled rolls of time extended space in which the pressing can take place.

Pressing the layer against the mold surface brings this moreover conditions in better thermal contact with the molding surface, so that approx de by pressing the softening process in the form area is accelerated while at the Outside, especially when the roller is cooled, the temperature increase continues slowly. This gives you one optimal adjustment of the position to the mold surface without the Layer sticks to the pressure roller.

In a particularly preferred embodiment is pre see that one for the production of a multi-layer molded body the lowest layer on the mold surface of a heated mold and then lay down several layers of the with endless sern reinforced plastic, where one to manufacture a one-piece connection each layer to the underlying presses as soon as the respective lower layer and this one facing side of the top layer are melted. Also here the melting of the underlying layer can facing side of the top layer by pressing it yourself  be accelerated so that just at the moment of Andrük kens the appropriate conditions for the one-piece connection of the layers lying on top of each other. In this case too, it is therefore possible to use the top layer to connect with the underlying one at a time where the top layer facing away from the molding surface Side is not yet softened and sticky.

It is advantageous if the molded body after placing the Layers of the plastic reinforced with continuous fibers Consolidated vacuum or by pressure in an autoclave becomes. As a result, the quality of the molded body as a whole is ver improves.

The following description of preferred embodiments the invention serve in connection with the drawing of the detailed explanation. Show it:

Fig. 1: a sectional view of a curved mold surface in the manufacture of a multilayered molded body made of continuous fiber-reinforced, thermoplastic plastic;

Fig. 2 is a sectional view of a mandrel for the produc- tion of a hollow body and

Figure 3:.. A sectional view similar to Figure 1 at the position of a curved shape Her body with inserted legtem gain profile.

In Fig. 1, a mold 1 is shown with a trough-shaped, in cross section approximately circular arc-shaped surface 2 , which can be heated via heating elements 3 extending inside the mold. The heating elements are preferably shaped channels through which a heating liquid, for example oil, flows, but embedded electrical heating elements or the like can also be used. The mold is heated in the area of its molding surface 2 by the heating elements.

A lower layer 4 is on the mold surface 2 of a continuous fiber-reinforced, applied thermoplastic material, which is completely adapted to the contour of the forming surface. 2

In FIG. 1 as in this lower layer 4 an upper layer 5 is shown, a continuous fiber reinforced thermoplastic plastic is applied. This application of the upper layer 5 takes place at a time when the placed on the mold surface 2 lower layer 4 is heated by the heating in the mold 1 to such an extent that the softening temperature is reached on its upper side, that is, on the Form surface 2 placed lower layer 4 is softened overall.

The upper layer 5 is placed on the lower layer 4 without prior heating, whereby it is heated in the contact area by the lower layer 4 . The heating takes place according to the relatively low thermal conductivity of thermoplastic material material slowly, so that there is a temperature gradient across the thickness of the upper layer. As a result, the upper layer is first heated above the softening temperature on its side facing the lower layer 4 , in this area the upper layer can be integrally connected to the lower, softened layer. This connection is supported by a roller 6 , which presses the upper layer 5 against the lower layer 4 . In addition to the one-piece connection of the two layers, this roller 6 also serves to bring the upper layer 5 into intimate contact with the lower layer 4 at all, so that effective heat transfer can take place. This is particularly necessary if complicated shapes are to be produced, because then the upper layer 5 , which is difficult to deform due to its low temperature, can only be deformed in the area and thereby pressed firmly against the lower layer the contact area between the upper and lower layer is closely adjacent. In the Ausführungsbei FIG game. 1, the roller is longitudinally moved, arranged parallel to the upper surface of the lower layer surface and thereby presses the top sheet increasingly against the lower layer, the upper layer in the first to come into contact with the unte ren position so that softening and warming can occur. The roller is moved so slowly that in the pressing area the temperature can rise above the melting temperature at least on the lower side of the upper layer, so that a one-piece connection is possible.

In this way, the top layer can be made in one piece be connected to the lower layer.

On the one-piece connection of the upper layer and The lower layer formed in the lower layer can in the another upper layer can be used up in the same way, this means that this process succeeds in creating a multi-layer to form shaped body in which the different layers are integrally connected.  

In the exemplary embodiment in FIG. 2, the layers are wound one after the other onto a mold 1 in the form of a winding mandrel, otherwise the same technique is also used here. In this way, a hollow body can be produced, from which after cooling the mold, this can be pulled out in the axial direction.

In the embodiment of FIG. 3, a prepared, for example strangely drawn, profile body 9 is pressed onto a lower layer 4 , which speaks the lower layer 4 of FIG. 1 completely, the pressure surfaces 7 , the shape of which is the top of the in Molded molded body 8 corresponds. Due to the pressure and the resulting heating in the area of the pressure surfaces 7 , the profile body 9 and the molded body 8 can be connected in one piece.

It is essential in all cases that the connection because the upper layer is only in the plant area at the lower layer the melting point is heated and on the opposite Side still a temperature below the melting point points, so that at the top of the upper layer pressure unit can attack witnesses without sticking to the top layer. In addition, the upper layer remains due to the one-sided heating Overall dimensionally stable and manageable, with the after pressing, he grasping the whole situation warming the continuous fibers in the top layer themselves free of tension can orientate so that even in the area of stronger deformation uniform strength properties can be achieved.

It is understood that the present invention is not only extends to the manufacturing process described, but also on the products manufactured by this process.

Claims (5)

1. A process for the production of a molded body from a thermoplastic reinforced with continuous fibers, in which plate or ribbon-shaped layers of the thermoplastic reinforced with continuous fibers are used as the starting material, characterized in that the layers are placed on a heated molding surface and they through this Mold surface heated so much that the position is deformable and on its side facing the mold surface it softens, and that one presses the layer at a time after the start of heating to the mold surface, to which the side facing away from the mold surface has not yet softened and yet is not sticky. 2. The method according to claim 1, characterized in that one presses the layers onto the mold surface using rollers. 3. The method according to claim 2, characterized in that one the rollers cools. 4. The method according to any one of the preceding claims, characterized characterized in that one for the production of a multilayer  Shaped body the lowest layer on the molding surface of a be placed on the heated mold and several layers one after the other of the plastic reinforced with continuous fibers, where with each layer to produce a one-piece Ver binding to the underlying presses as soon as the ever Weil's lower layer and the side facing it because the upper layer is melted. 5. The method according to any one of the preceding claims, characterized characterized in that the molded body after placing the Layers of the plastic reinforced with continuous fibers Vacuum or by pressure in an autoclave is lidded.