Usage of expansion bolts

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Expansion bolts are special threaded fasteners used to fix air duct supports, hangers, and brackets to walls, floors, and columns. Components The expansion bolt consists of a set screw, an expansion tube, a flat washer, a spring washer, and a hex nut. Usage: When in use, first drill a hole of the appropriate size in the fixing element using an impact drill (hammer), then insert the bolt and expansion tube into the hole. Tightening the nut will cause the bolt, expansion tube, and mounting component to become tightly bonded together with the fixing element. 　　It expands after being tightened. The bolt has a large head at its end, and a circular tube slightly larger in diameter than the bolt is fitted over it. There are several openings in that end portion; when the bolt is tightened, the large head is pushed into these openings, causing the tube to expand and thus achieving expansion. This in turn fixes the bolt to the ground or wall, enabling it to be secured in place. Principle The fixing principle of expansion screws: Expansion screws achieve fixation by utilizing their tapered shape to generate frictional gripping force as a result of expansion. One end of the screw has threads, while the other end has a tapered design. An iron sheet is used as an outer covering; the iron cylinder has several cuts on one half of it. These are inserted together into holes drilled in the wall, after which nuts are tightened. By pulling the screws outward, the cylinder is pushed inside the iron cylinder, causing the latter to expand and thus fix firmly to the wall. It is generally used for securing guardrails, canopies, air conditioners, etc., to surfaces made of concrete, bricks, and similar materials. However, its fixation is not very reliable; if the load experiences significant vibrations, it may come loose, so it is not recommended for installing ceiling fans or similar devices. 　　The principle of an expansion bolt is as follows: after the bolt is inserted into a hole in the ground or wall, the nut on the bolt is tightened using a wrench. This causes the bolt to expand outward, while the outer metal sleeve remains stationary. As a result, the larger end of the bolt expands the metal sleeve, filling the entire hole; at this point, the expansion bolt can no longer be pulled out. Classification: Expansion screws are now available in stainless steel and plastic versions, each with different applications. Precautions for using expansion screws: 1. Drilling depth: The relevant information provides the length of the expansion tube, but in my experience during actual installation, this depth turns out to be insufficient; this may be due to residual debris in the hole. Therefore, it’s better to drill about 5 millimeters deeper than the length of the expansion tube. As long as you are greater than or equal to the length of the expansion tube, the length of the expansion bolt remaining underground will be equal to or less than the length of the expansion tube. 　　2. Of course, the harder the ground surface is for expansion bolts, the better – this also depends on the stress conditions to which the object to be fixed is subject. The load-bearing strength when installed in concrete (C13-15) is five times that in brick. 　　3. After a properly installed M6/8/10/12 expansion bolt in concrete, its least favorable maximum static load capacities are 120/170/320/510 kilograms respectively. (Note: Vibration can loosen the bolts.)