Expanding metal dowel with threaded bolt - has continually increasing surface roughness from smooth surface for better hold

摘要

The threaded bolt (2) has at its insert end a restriction which forms a shoulder (11) towards the rear end of the bolt and an expanding cone (7) towards the front end. The surface of the cone is first smooth and then ribbed or threaded with the depth of the circumferential threads increasing. The bolt is pref. made from a threaded rod wherein the dia. of the restriction is less than the core dia. of the thread so as to provide the smooth surface for the start of the cone. As the expanding cone is drawn into the expanding sleeve the friction increases. USE/ADVANTAGE - Expanding metal dowel with threaded bolt. The cone cannot be pulled right through the expanding sleeve.