Plastic collapsible screw fastening device having auxiliary holding means

Claim 1

A SCREW FASTENING DEVICE COMPRISING A SLEEVE OF DEFORMABLE MATERIAL, SAID SLEEVE HAVING AN AXIAL BORE EXTENDING FROM ONE END AT LEAST PARTIALLY TO AN END REMOTE FROM THE ONE END, SAID BORE BEING ENLARGED IN THE REGION OF THE ONE END AND OF SMALLER DIAMETER IN THE REGION OF THE REMOTE END, A FLANGE AT THE ONE END OF THE SLEEVE, A PORTION OF NON-CIRCULAR CROSS SECTION IMMEDIATELY BELOW THE FLANGE FOR NON-ROTATABLE ENGAGEMENT IN A SIMILARLY SHAPED HOLE IN A MEMBER TO WHICH THE FASTENING IS APPLIED, THE MAXIMUM DIMENSION OF SAID PORTION OF NONCIRCULAR CROSS SECTION BEING LESS THAN THE MINIMUM DIMENSION OF SAID FLANGE, THE REMAINING SLEEVE PORTION FROM THE NON-CIRCULAR PORTION TO THE REMOTE END OF THE SLEEVE BEING OF CIRCULAR CROSS SECTION OF LESS AREA THAN THAT OF AN END FACE OF THE NON-CIRCULAR PORTION ADJACENT THE CIRCULAR PORTION, THE DIAMETER OF SAID CIRCULAR SLEEVE PORTION BEING NO GREATER THAN THE MINIMUM DIMENSION OF THE NON-CIRCULAR PORTION, THE CIRCULAR SLEEVE PORTION WALL IMMEDIATELY ADJACENT THE NON-CIRCULAR PORTION BEING THIN COMPARED TO THE CIRCULAR SLEEVE PORTION WALL AT THE REMOTE END, AND A PLURALITY OF CIRCUMFERENTIALLY SPACED LOCKING PROJECTIONS INTEGRAL WITH THE NON-CIRCULAR PORTION, EACH LOCKING PROJECTION HAVING A STEM EXTENDING FROM SAID END FACE OF THE NON-CIRCULAR PORTION TOWARDS THE REMOTE END, THE STEM BEING PARALLEL TO THE SLEEVE AXIS AND SPACED FROM THE THIN WALL OF THE CIRCULAR SLEEVE PORTION, AND A NOSE PROJECTING RADIALLY OUTWARDLY FROM THE OUTER END OF THE STEM BEYOND THE PERIPHERY OF THE NON-CIRCULAR PORTION.