Needled glass mat
View Patent ↗A method for preparing a mat, including: a) deposition or projection of threads onto a traveling belt to form a lap of the threads that are driven by the belt, then b) needling by bearded needles passing through the lap and being displaced in the direction of the lap at substantially the same speed as that when they pass through the lap, with a stroke density ranging from 1 to 25 strokes per cm 2 . By the method the mat obtained can easily be deformed by hand to be placed in a mold for manufacture of a composite material by injection of resin (RTM). The mat may also be incorporated into a preimpregnated sheet (SMC) and be molded under pressure.
1. A method for preparing a mat including glass fiber comprising:
a) deposition or projection of threads including glass fibers onto a traveling belt to form a lap of the threads that is driven by the belt at a lap speed in a lap direction; then
b) needling by bearded needles displaced in a direction parallel to the lap direction at substantially a same speed as the lap speed when they pass through the lap, with a stroke density ranging from 1 to 25 strokes per cm 2 .
2. The method as claimed in claim 1 , wherein the stroke density of the needling is at most 15 strokes per cm 2 .
3. The method as claimed in claim 2 , wherein the stroke density of the needling is at most 10 strokes per cm 2 .
4. The method as claimed in claim 1 , wherein the stroke density of the needling is at most 2 strokes per cm 2 .
5. The method as claimed in claim 1 , wherein the threads are continuous threads including the glass fibers.
6. The method as claimed in claim 1 , wherein the threads are cut threads including the glass fibers.
7. The method as claimed in claim 1 , wherein the needling is carried out by needles fastened to a support, the beards of the needles being directed toward the support.
8. The method as claimed in claim 1 , wherein the lap and the mat derived from the lap advance at a speed of 2 to 35 meters per minute.
9. The method as claimed in claim 1 , wherein the lap and the mat derived from the lap advance at a speed of at least 8 meters per minute.
10. The method as claimed in claim 1 , wherein the lap and the mat derived from the lap advance at a speed of at most 20 meters per minute.
11. The method as claimed in claim 1 , wherein the needles describe an elliptic movement.
12. The method as claimed in claim 1 , wherein the mat does not contain any binder.