Method and apparatus for connecting a fastener element to a wall

摘要

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