Method for producing multilayer tailored fiber placement (TFP) preforms using meltable fixing fibers

1. A method for producing a multilayer TFP (Tailored Fiber Placement) preform, comprising:

sewing reinforcing fibers onto a substrate with one of a chemically- and a thermally-meltable fixing thread to fix the reinforcing fibers to the substrate to produce a reinforcing fiber structure; and

then melting the fixing thread so that the fixing thread dissolves to adhesively pre-fix the reinforcing fibers to the substrate, mechanical properties of the reinforcing fiber structure being unaffected by the fixing thread;

wherein, after the melting step, the pre-fixed reinforcing fibers are removable from the substrate as a reinforcing fiber structure.

2. The method according to claim 1 , further comprising:

stacking at least two reinforcing fiber structures to form a multilayer stack structure;

melting the fixing thread; and

impregnating and curing the stack structure.

3. The method according to claim 2 , wherein the fixing thread melting step is performed during the impregnating and curing step by chemical reaction with a material to be impregnated.

4. The method according to claim 2 , wherein the melting step includes applying external heat to heat the fixing thread to a temperature above a melting point.

5. The method according to claim 4 , wherein the external heat is applied in the external heat applying step during the impregnating and curing step to melt the fixing thread.

6. The method according to claim 2 , further comprising removing an outwardly facing substrate of the stack structure by one of tearing off and peeling.

7. The method according to claim 1 , further comprising:

melting the fixing thread by applying external heat after sewing the reinforcing fibers onto the substrate to pre-fix the reinforcing fibers by adhesive action of a molten fixing thread and to provide adequate stability to the reinforcing fiber structure;

stacking a plurality of reinforcing fiber structures to form a stack structure; and

impregnating and curing the stack structure.

8. The method according to claim 7 , further comprising removing an outwardly facing substrate of the stack structure by one of tearing off and peeling.

9. The method according to claim 1 , wherein the fixing thread includes one of a thermoplastic and a hot melt yarn.

10. The method according to claim 9 , wherein the fixing thread includes a copolyamide multifilament hot melt yarn.

11. The method according to claim 1 , wherein the preform lacks an intermediate layer, the method further comprising:

melting the fixing thread by applying external heat after sewing the reinforcing fibers onto the substrate to pre-fix the reinforcing fibers by adhesive action of a molten fixing thread and to provide adequate stability to the reinforcing fiber structure;

stacking a plurality of reinforcing fiber structures without a substrate to form a stack structure; and

impregnating and curing the stack structure.

12. The method according to claim 1 , further comprising one of force-flux orienting and arranging quasiisotropically the reinforcing fibers on the substrate.

13. The method according to claim 1 , further comprising tearing off the reinforcing fibers as a reinforcing fiber structure from the substrate after the melting step.

14. The method according to claim 1 , wherein the method is adapted to produce a multilayer TFP preform having a selectively desired thickness and without an interfering intermediate layer.