Sandwich panel spacer with torque resistant mechanical anchorage

Claim 1

A SPACER TYPE INSERT FASTENER FOR INSTALLATION IN A LIGHTWEIGHT SANDWICH PANEL EMBODYING SPACED SKINS ATTACHED TO OPPOSITE SIDES OF A LOW-DENSITY CORE, HAVING A HOLE EXTENDING THROUGH ONE OF SAID SKINS AND THROUGH SAID CORE, AND HAVING IN THE OTHER SKIN AN OPENING COAXIAL WITH AND OF SMALLER DIAMETER THAN SAID HOLE, DEFINED BY AN ANNULAR PORTION OF SAID OTHER SKIN CONSTITUTING A BOTTOM FOR SAID HOLE, SAID FASTENER COMPRISING, IN COMBINATION: A SHELL INCLUDING AT ONE END A TUBULAR BODY HAVING AN END PROVIDED WITH INWARDLY PROJECTING MEANS DEFINING AN ABUTMENT SEAT, AND INCLUDING AT ITS OTHER END A THIN COMPRESSION-DEFORMABLE SLEEVE HAVING AN OPEN END PROVIDED WITH AN OUTWARDLY PROJECTING ANNULAR FLANGE HEAD FOR SEATING AGAINST SAID ONE SKIN; A PLUG RECEIVED IN SAID SHELL, SAID PLUG INCLUDING A SKIRT DEFINING A NUT RECEPTACLE AND HAVING AN OPEN END ABUTTING SAID SEAT AND PROVIDED WITH A KEY NOTCH, AND AN OPPOSITE END INITIALLY LOCATED BELOW SAID HEAD WITHIN SAID OPEN END OF THE SHELL; AND A NUT DISPOSED WITHIN SAID SKIRT AND HAVING A RADIALLY PROJECTING KEY LOOSELY RETAINED IN SAID NOTCH BETWEEN SAID SEAT AND THE ABUTTING END OF SAID PLUG, THEREBY MOUNTING SAID NUT IN A FLOATING CAPTIVE CONDITION; SAID SHELL BEING RECEIVABLE IN SAID HOLE WITH SAID END OF THE TUBULAR BODY ABUTTED AGAINST SAID HOLE BOTTOM AND WITH THE SLEEVE PROJECTING BEYOND SAID ONE SKIN SO AS TO PROVIDE FOR THE FORMATION OF AN ANNULAR BULBED SECONDARY HEAD IN SAID SLEEVE BENEATH SAID ONE SKIN AND OPERABLE TO SECURE THE SAME AGAINST SAID FLANGE HEAD BY COMPRESSION OF SAID SHELL AXIALLY UNTIL IT IS REDUCED TO A LENGTH SUBSTANTIALLY EQUAL TO THE THICKNESS OF SAID PANEL, SUPPORT BEING TRANSMITTED FROM A SUPPORTING SURFACE DIRECTLY THROUGH SAID OTHER SKIN TO THE ABUTTING END OF SAID SHELL DURING SUCH COMPRESSION.