Method for reinforcing a hole edge region workpiece with a hole with reinforced hole edge region hole edge reinforcing device
The invention relates to a method for reinforcing a predetermined edge region of a hole in a hole region of a workpiece, the edge region comprising an edge of the hole, the hole region comprising thermoplastically bound fibers, preferably a thermoplastically bund fiber tangle, comprising the steps: providing the workpiece with a softened thermoplastic binder at least in the hole region, penetrating the hole region of the workpiece in a penetration direction with displacement of fibers with a spike, after penetration: scraping fibers from the spike contrary to the penetration direction by a scraper part mobile relative to the spike, and compacting the predetermined edge region surrounding the spike with a pressing surface of the scraper part relative to workpiece regions of the hole region located radially outside the edge region.
1. A method of reinforcing a hole edge region surrounding a hole of a workpiece comprising thermoplastically bound fiber composite material, the method comprising steps of:
providing the workpiece in a condition in which thermoplastic binder thereof is softened in at least a hole region of the workpiece intended for perforation;
during press-forming of the workpiece between first and second mold halves:
penetrating the workpiece at the hole region by moving a pointed spike positioned within the first mold half with respect to the first mold half and toward the composite material and second mold half so as to form the hole;
scraping displaced composite material fibers from the spike by moving a scraper part positioned within the second mold half with respect to the second mold half and toward the hole edge region, first mold half, and spike; and
compacting the hole edge region in an area surrounding the spike with a pressing surface of the scraper part so as to form a higher degree of compaction of the hole edge region with respect to surrounding regions located radially outside of the hole edge region, the hole edge region thereby exhibiting a degree of compaction of less than 90%.
2. The method of claim 1 , wherein the spike comprises a body portion having a constant cross-sectional area and a longitudinal end portion tapering from the body portion to form the spike point.
3. The method according to claim 2 , wherein said scraping begins at earliest when the spike has penetrated the hole region to such an extent that fibers of the workpiece lie substantially only against the spike body portion and not against the spike end portion.
4. The method according to claim 1 , wherein said scraper movement is contrary to a penetration direction of the spike.
5. The method according to claim 4 , wherein said scraper movement begins after said spike movement for penetration has terminated.
6. The method according to claim 1 , further comprising selecting the scraper part in terms of a size of the pressing surface thereof as a function of fiber composite material of the hole region, a desired size of the hole to be formed, and a desired reinforcement of the hole edge region.
7. The method according to claim 1 , wherein a force exerted on the scraper part during said compacting is greater than a force exerted on the spike during said penetrating.
8. The method according to claim 1 , wherein said penetrating results in severing of fibers of the hole region.
9. The method according to claim 1 , wherein the degree of compaction is less than 80%.
10. The method according to claim 1 , wherein the composite material comprises a thermoplastically bound fiber tangle.