The fixing principle of expansion screws: The fixing of expansion screws uses the inclination of the shape to promote expansion and generate friction and gripping force to achieve a fixing effect. The screw has a thread on one end and a cone on the other. Wrap a steel sheet on the outside. There are some cutouts in half of the iron sheet cylinder. Put them together into the hole drilled in the wall. Then lock the nut. The nut pulls the screw out and pulls the vertebra into the steel sheet cylinder. The steel sheet is round. The tube is expanded and then tightly fixed on the wall. It is generally used for fastening guardrails, awnings, air conditioners, etc. on cement, bricks and other materials. However, its fixation is not very reliable. If the load vibrates greatly, it may become loose.
Therefore it is not recommended for installing ceiling fans etc. The principle of expansion bolts is to drive the expansion bolts into the holes on the ground or wall, and then tighten the nuts on the expansion bolts with a wrench. The bolts will move outward, but the metal sleeve outside will not move. Therefore, the big head under the bolt will move. The metal sleeve expands so that it fills the entire hole. At this time, the expansion bolt cannot be pulled out.
1. Select an alloy drill bit that matches the outer diameter of the inner expansion bolt, then drill according to the length of the inner expansion bolt. Drill the hole as deep as you need for installation, and then clean the hole. 2. Install the flat washer, spring washer and nut, screw the nut to the bolt and end to protect the thread, and then insert the inner expansion bolt into the hole. 3. Turn the wrench until the washer and the surface of the fixture are flush. If there are no special requirements, generally tighten by hand and then use the wrench for three to five turns.