NOVEL ABRASIVE-WATERJET TECHNIQUES FOR THE MACHINING OF ISOGRID STRUCTURES

ISOGRID STRUCTURES ARE USED IN MANY MISSILE BECAUSE OF THEIR LIGHTWEIGHT AND STIFFNESS CHARACTERISTICS. THESE STRUCTURES ARE COMPLEX AND REQUIRE EXTENSIVE MANUFACTURING PROCESSES THAT, IN MANY SITUATIONS, ARE COST PROHIBITIVE, AS IN THE CASE OF SMALL ICBMS. THIS PROPOSAL ADDRESSES NOVEL CONCEPTS USING THE ABRASIVE-WATERJET (AWJ) TECHNIQUE. THE TECHNICAL AND ECONOMICAL FEASIBILITY OF THIS TECHNIQUE WILL BE DETERMINED IN PHASE I, WHILE IN PHASE II, THE FULL MACHINING PROCESS WILL BE DEMONSTRATED. THE AWJ TECHNIQUE WILL ALLOW THE MACHINING OF PARTS IN THE CYLINDRICAL SHAPE, AS OPPOSED TO THE METHOD USED NOW OF MILLING FLAT PATTERNS, ROLLING THEM, AND THEN WELDING. AN AWJ MOUNTED ON A ROBOT ARM WILL BE USED TO MILL THE PATTERNS OF THE OSGRID FROM THE INSIDE OF THE PART. TWO MILLING STRATEGIES WILL BE INVESTIGATED: IN THE FIRST, LINEARLY TRAVERSING JETS WILL BE USED, WHILE IN THE OTHER, ROTARY JETS WILL BE USED. A SMALL PATTERN TEMPLATE (OR TEMPLATES) OF HARD MATERIAL (MACHINED WITH THE AWJ) WILL BE USED IN THE MILLING PROCESS AS A MASK(S) SO THAT MILLING OF DIFFERENT "POCKET" SHAPES CAN BE OBTAINED WITH SIMPLE JET TRAVERSAL OVER THE MASK. SIMPLE EXPERIMENTS WILL BE CONDUCTED IN PHASE I TO DETERMINE THE QUANTITATIVE AND QUALITATIVE RESULTS OF AWJ ISOGRID MACHINING. A BRIEF ANALYSIS WILL BE CONDUCTED TO DETERMINE IF THE STATE OF THE ART IN DIFFUSION BONDING WILL OFFER AN ALTERNATIVE METHOD. RESEARCH ON OPTIMAL AWJ PARAMETERS AND CONCEPTS WILL BE ADDRESSED TO DEFINE PROMISING DIRECTIONS FOR FUTURE DEVELOPMENT EFFORTS. A DATA MATRIX WILL BE GENERATED TO ANALYZE THE TECHNICAL AND ECONOMIC FEASIBILITIES OF THE AWJ MILLING TOOL CONCEPT.