Method of making a metal sandwich structure panel

Claim 1

THE METHOD OF MAKING A METAL SANDWICH STRUCTURE PANEL FROM A SHEET METAL BLANK, SAID PANEL COMPRISING A PLURALITY OF LINGITUDINALLY-SPACED LATERALLY-EXTENDING ROWS OF SPACED DIMPLES, EACH DIMPLE COMPRISING A FLAT CIRCULAR END WALL AND A TAPERED SIDE WALL, SAID METHOD COMPRISING THE STEPS OF: INTERMITTENTLY FEEDING SAID BLANK THROUGH A PREFORMING STATION AND A FINAL FORMING STATION; PREFORMING ROWS OF LATERALLY-SPACED ROUNDED-END DIMPLELIKE SHAPES, AT SAID PREFORMING STATION, IN SUCCESSIVE PORTIONS OF SAID BLANK, EACH ROW BEING PREFORMED BY SIMULTANEOUSLY COLD DRAWING THE METAL WITHIN LATERALLY-SPACED AREAS TO FORM SUCH SHAPES AND PREVENTING THE FLOW OF METAL INTO SUCH AREAS AND THEREBY PREVENT DIMENSIONAL DISTORTION OF SAID BLANK OUTSIDE OF SUCH AREAS; AND FINAL FORMING SAID ROWS OF SAID ROUNDED-END DIMPLE-LIKE SHAPES INTO SAID DIMPLES AT SAID FINAL FORMING STATION BY SIMULTANEOUSLY HOLDING SAID BLANK AROUND SAID DIMPLE-LIKE SHAPES OF EACH ROW AS EACH ROW PASSES THROGH A FINAL FORMING STATION, AND STRETCHING SAID ROUNDED-END DIMPLE-LIKE SHAPES TO FORM SAID DIMPLES.