Honeycomb core composite article and method and apparatus for making same
A method is provided that uses half-period translations, ply-upon-pin repositions, and shape-maintaining pins with a bolster plate, with insertable nodal heating elements that provide heat at their rectangular ends and when driven under pressure against opposing pins with rectangular faces cure portions of a pre-impregnated fabric to make honeycomb core composite articles.
1. A method of manufacturing a honeycomb core comprising the steps of:
providing a bolster table comprising a plate having a plurality of transverse grooves, a plurality of resistive heating elements each having a top surface and a bottom surface, the top surface of each of the resistive heating elements mounted in said plurality of transverse grooves;
providing an apparatus for receiving the bolster plate, the apparatus comprising a press, a first plurality of fixture pins each having a top surface and a bottom surface and a fixture comprising a plurality of grooves to receive the bottom surfaces of each of the first plurality of fixture pins;
repeating the following steps until a core of desired height is achieved:
drawing across the bolster table a layer of material while inserting a first plurality of bolster plate pins, the first plurality of bolster plate pins being attached to the bolster table via fastening means;
inserting the bolster table into the receiving apparatus so that the bottom surfaces of each of the plurality of resistive heating elements and the top surfaces of each of the first plurality of fixture pins are substantially aligned;
pressing, by the receiving apparatus, the bolster plate such that the plurality of heating elements press portions of the layer of material against the fixture pins; and
heating portions of the layer of material by way of the resistive heating elements;
when the layer of material is a first ply, then performing the steps comprising:
retracting the press;
removing the bolster plate;
translating the layer of material by one-half cell;
reinserting the layer of material so as to rest upon top surfaces of each the fixture pins; and
when the layer of material is an even ply, then performing the steps comprising:
retracting the press;
removing the first plurality of fixture pins;
translating the first plurality of bolster plate pins, which now function as a second plurality of fixture pins, and, with the second plurality of fixture pins, the plies of material, one-half of a corrugated cell;
drawing across the bolster table a layer of material while inserting the first plurality of fixture pins, which now function as a second plurality of bolster plate pins, the second plurality of bolster plate pins being attached to the bolster table via fastening means; and
pressing the bolster plate such that the groove-mounted heating elements press portions of the layer of material against the at least one previously pressed layer of material supported by the second plurality of fixture pins; and
when the layer of material is an odd and not first ply, then performing the steps comprising:
retracting the press;
removing the second plurality of fixture pins;
translating the second plurality of bolster plate pins, which now function as the first plurality of fixture pins, and, with the first plurality of fixture pins, the plies of material, one-half of a corrugated cell;
drawing across the bolster table a layer of material while inserting the second plurality of fixture pins, which now function as the first plurality of bolster plate pins, the first plurality of bolster pins being attached to the bolster table via fastening means; and
pressing the bolster plate such that the groove-mounted heating elements press portions of the layer of material against the at least two previously pressed layer of material supported by the first plurality of fixture pins;
whereby the core of desired height is fabricated for post-curing.
2. The method as claimed in claim 1 wherein the transverse grooves are rectangular.
3. The method as claimed in claim 1 wherein the press is pneumatic.
4. The method as claimed in claim 1 wherein the first plurality of fixture pins is rectangular parallelepiped.
5. The method as claimed in claim 1 wherein the first plurality of bolster plate pins is rectangular parallelepiped.
6. The method as claimed in claim 1 further comprising the step of post-curing.
7. The method as claimed in claim 1 wherein the fastening means for attaching the first plurality of bolster plate pins to the bolster table is hooks.
8. The method as claimed in claim 1 wherein the material of the layer of material and successive layer of material is an aromatic polyamide fiber of high tensile strength.
9. The method as claimed in claim 1 wherein the material of the layer of material and successive layer of material is a prepreg fabric.
10. The method as claimed in claim 9 wherein the prepreg fabric is unidirectional fabric.
11. The method as claimed in claim 9 wherein the prepreg fabric comprises multiple plies of uncured unidirectional material.
12. The method as claimed in claim 9 wherein the prepreg fabric is a sheet of resin impregnated felt.
13. The method as claimed in claim 9 wherein the prepreg fabric is a sheet of stitched unidirectional fabric.
14. The method as claimed in claim 6 wherein the material of the layer of material and of the successive layer of material is a sheet of chopped-fiber reinforced molding material.
15. The method as claimed in claim 6 wherein the fabric is a sheet of unreinforced sheet molding compound.