One of the expansion screw fasteners

Fixing principle of expansion screw: the fixing of expansion screw is to use the pull-out slope to promote the expansion to produce friction grip force and achieve the fixing effect. One end of the screw is threaded, and the other end is tapered. The outer surface is covered with a steel sheet. There are several cuts in half of the iron sheet cylinder. Insert them into the holes made on the wall, and then lock the nut. The nut pulls the screw outward to pull the vertebral degree into the steel sheet cylinder. The steel sheet cylinder is expanded and firmly fixed on the wall. It is generally used for fastening protective fences, awnings, air conditioners and other materials on cement, bricks and so on. However, its fixation is not very reliable. If the load has large vibration, it may loose. Therefore, it is not recommended to install ceiling fan, etc. The principle of expansion bolt is that after the expansion bolt is hit into the hole on the ground or wall, tighten the nut on the expansion bolt with a wrench. The bolt goes outward, but the outer metal sleeve does not move. Therefore, the big head under the bolt expands the metal sleeve to fill the whole hole. At this time, the expansion bolt cannot be pulled out.