EXPANSION ANCHOR AND METHOD THEREFOR

摘要

An expansion anchor installable in a pre-drilled hole formed in a base material. The expansion anchor including a bolt having shaft with a head por tion, an opposing end portion, and a threaded portion. A shoulder is disposed on the shaft intermediate the head portion and the end portion thereof, and an expandable sleeve is disposed about the shaft between the shoulder and the end portion of the shaft. The expandable sleeve has an expandable upper sleeve portion and an expandab le lower sleeve portion wherein the expandable lower sleeve portion is expandab le outwardly before the expandable upper sleeve portion is expandable outwardly . A nut having a substantially conical surface is fixed rotationally in the pre-dril led hole and is engagable with the threaded portion of the shaft. The substantially conic al surface of the nut is engageable with the expandable lower sleeve portion to expand the lower sleeve portion until the nut is fixed axially in the pre-drilled hole. The a dvancing bolt is subsequently drawn into the pre-drilled hole and the shoulder of the shaf t isengagable with the expandable upper sleeve portion t o expand outwardly the uppersleeve portion, whereby the expandable upper and lower sleeve portions are engageable with wall of the pre-drilled hole to retain the expansion anchor therein.