Method and apparatus for connecting a fastener element to a wall

摘要

A tubular fastener element (34) is inserted into an opening(44) in a wall (W) until a flange (40) at the trailing end of the fastener element (34) is in contact with the wall (W). Then, an externally threaded end (32) of a rod (28) is inserted into a center opening (56) in the fastener element (34) from the flange side (42) of the wall (W) and is mated with internal threads (52) in the fastener element (34) beyond the second side (50) of the wall (W). A tubular mandrel (24) that surrounds the rod (28) is moved into contact with the entrance portion of the center opening (56) in the tubular fastener (34). The outside diameter of the mandrel (24) is larger than the inside diameter (58) of the center opening (56) in the fastener element (34). The rod (28) is retracted to cause a reduced thickness wall portion (46) of the fastener element (34) to collapse and form a second radial flange (60) on the second side (50) of the wall (W). The mandrel (24) is forced axially into the center opening (56) in the fastener element (34). This causes a tubular end portion (36) of the fastener element (34) that is in the opening (44) in the wall (W) to radially expand into tight engagement with the sidewall of the wall opening (44). It also cold expands the wall material surrounding the opening (44) for fatigue enhancement of the wall material.