Continuous honeycomb lay-up process

#This present invention relates generally to the art of honeycomb fabrication and more particularly to a novel process for producing a honeycomb structure formed from sheets of radar absorbing material.

#The use of honeycomb structures in commercial and military applications is well known. Various industrial applications require structural materials which are capable of extended use and have a high specific strength, that is high strength to weight ratios. One class of such material is honeycomb. These structures can be compositionally and geometrically tailored to exhibit controlled mechanical, electrical, and chemical properties useful in the commercial sector and military sector, such as a material to be sandwiched between two sheets of material.

#Previous attempts to fabricate variable shaped honeycomb structures from sheets of radar absorbent material suffer from labor intensive and time consuming operations. Currently radar absorbent material sheets are cut in a length dimension and manually placed on a lay-up table. Each consecutive sheet is placed manually half a pitch width apart such that sheets alternate the nodeline position through the stack which is the width direction of the honeycomb before expansion. This is an extremely tedious task and prone to eye fatigue and operator error. Errors in alignment of the sheets not only cause poor cell configuration but also has a significant impact on block electrical as well as mechanical properties. Automation of this tedious layup process can significantly impact the cost and quality of honeycomb structures and eliminate a bottleneck from the manufacturing process.

#These as well as other features of the present invention, will become more apparent upon reference to the drawings wherein.

#FIG. 1 is a schematic side elevational view of apparatus for constructing a honeycomb structure;

#FIG. 2 is a perspective view of a roll of cut non-expanded honeycomb;

#Referring now to the drawings, wherein the figures are for purposes of illustrating the preferred embodiment of the present invention. Referring now to FIGS. 1-4, in accordance with the present invention, there is provided a method for constructing a honeycomb structure FIG. 4 generally undetectable by radar. The method includes placing a first 8 and second 9 roll of radar absorbent sheet material 10 and 12 on opposing sides of a rotatable central roller 14. The rolls 8 and 9 of sheet material 10 and 12 to be fed onto the central roller 14 may consist of radar absorbent nomex, resin pre-impregnated material including low-temperature fusible thermo-plastic material, carbon, carbon fiber, as well as any other electric and magnetic filled absorbing and/or dissipating materials. The central roller 14 is equipped with a variable speed control which determines the rate of production. The central roller 14 can vary in size and shape to form a predetermined configuration of wound sheets of material 34.

#The first printer 16 is spatially arranged with the first roll 8 to print a plurality of parallel adhesive linear deposits 17 on the first sheet of material 10 as the first sheet of material 10 passes across the first printer 16. Printing can be achieved with a variety of printing processes including rotogravure, flexographic, rotary screen, or ink jet. The adhesive deposits 17 and 19 on sheet materials 10 and 12 are adjustable, so as to form continuous adhesive deposits 17 and 19 or spaced apart points of adhesive deposits 17 and 19. The adhesive deposits 17 and 19 may consist of a heat curable resin composite material with bond fibers embedded therein. As one in the art would appreciate, an alternative room temperature curable adhesive may be used.

#The second printer 18 is spatially arranged with the second roll 9 of sheet material 12 and has the same printing characteristics as first printer 16. The second printer 18 distributes adhesive deposits 19 onto the second sheet material 12 in parallel relation to the first printer 16 adhesive deposits 17. However, the adhesive deposits 19 printed on the second sheet material 12 are not to be in line with adhesive deposits 17 printed on the first sheet material 10. Adhesive deposits 17 and 19 serve to secure first 10 and second sheet materials 12 together along the spaced apart longitudinally extending adhesive deposits 17 and 19. The first printer 16 and second printer 18 shall apply substantially plurality of parallel adhesive linear deposits 17 and 19 on sheet materials 10 and 12 prior to winding onto the central roller 14. Adhesive deposits 17 and 19 are alternately staggered from sheet material 10 to sheet material 12 to insure proper honeycomb cell configuration during expansion of wound sheet materials 10 and 12 after they are removed from central roller 14.