Dowel, for use in brickwork drillings, has a screw to expand the dowel sleeve with rear screw flanks to expand the sleeve, and radial flanks to prevent unscrewing

摘要

The expanding dowel has a dowel sleeve and an expanding screw (10) with a rear flank (20) of a screw thread (18), in the screwing direction, pitched at an angle of 9 deg to an axis direction of the screw. The screw thread has a large pitch. When the screw is moved in a withdrawal direction, the rear flank acts as a spreading cone to expand the dowel sleeve. The screw thread also has radial flanks (26) which press into the dowel during its expansion, and prevent the screw being unscrewed from the dowel sleeve.