Abstract: A bolt anchoring device for insertion into a bore in a concrete ceiling or the like material is provided. The bolt anchoring device comprises an anchor sleeve and a bolt. The anchor sleeve is first inserted in the bore for its provisional or temporary attachment. The bolt is then screwed into the anchor sleeve for permanent attachment of the anchor sleeve and the bolt. In one embodiment, the bolt is removable after permanent attachment of the anchor sleeve. The anchor sleeve has a self-retaining means for retaining itself in the bore at the time of its provisional or temporary attachment. The anchor sleeve has a first end portion having a threaded hole and a second end portion having a plurality axial slits. The bolt has an integral plug portion which is pushed into the second end portion to expand the second end portion and make it cut into an inner wall surface of the bore for thereby firmly securing the anchor sleeve in the bore.

Abstract: Anchor unit of this invention is provided with a plug which is driven into an anchor socket or sleeve to expand its split end portion by rotating a bolt which is engaged with the anchor socket or the plug by threads, in a predetermined direction. In one embodiment, the plug is a separable end portion of the bolt which is movable together with a remaining portion of the bolt when the bolt is rotated in the above described predetermined direction and twisted off or separated from the remaining portion when the bolt is rotated in a direction opposite to the above described predetermined direction.