Abstract: An anchor comprising a bolt having an upper cylindrical part with an outer thread adjacent its top and a lower conical head, and a sleeve surrounding the bolt, the sleeve comprising an upper cylindrical portion and an annular expander, the expander having multiple slits therein which open to the bottom end and extend axially. The slits form expansion pieces therebetween having curvatures which, before expansion of the pieces, are substantially the same as the curvatures at the corresponding positions of the outer peripheral wall of the conical head, which the pieces contact after expansion.

Abstract: An anchor bolt comprising a bolt having an upper cylindrical part with an outer thread adjacent its top and a lower conical head, and a sleeve surrounding the bolt, the sleeve comprising an upper cylindrical portion and an annular expander, the expander having multiple slits therein which open to the bottom end and extend axially. The slits form expansion pieces therebetween having curvatures which, before expansion of the pieces, are substantially the same as the curvatures at the corresponding positions of the outer peripheral wall of the conical head, which the pieces contact after expansion.

Abstract: This disclosure relates to a tool for boring or drilling holes in relatively hard, thick material such as sheet steel. The borer includes a tubular, cylindrical part having cutting teeth on one end edge. The borer part is designed to be rotated on its tubular axis and to be advanced in a forward direction to move the teeth against the material to be bored. The teeth are circumferentially spaced and are, alternately, inner cutting teeth and outer cutting teeth. The teeth are formed at the leading corners of radially thickened portions of the part, and channels or grooves are formed between the spaced teeth for the efficient removal of shavings. The teeth cut an annular groove, the inner teeth cutting at the radially inner corner of the groove and the outer teeth cutting at the radially outer corner of the groove.