Expansion screw fixation is the use of trapezoidal slope to allow expansion of a large amount of friction, know to achieve the desired fixed effect, we generally use expansion screw is divided into iron and plastic two, its use is based on the standard of expansion screw to make the corresponding hole, and then the expansion screw into so in the future The expansion screws will have a good fixation after opening. One side of the expansion screw is threaded and the other is taper.
 
The outside of the expansion screw is covered with sheet iron. Some of the expansion screw is covered with steel pipe. There is half of the cut in the cylinder of sheet iron. Then the screw is completely penetrated into the hole made before the wall is finished. The screw is locked by the nut. The nut pulls the screw out vigorously and pulls the tapered side into the cylinder of sheet iron. The cylinder of sheet iron is expanded. When it expands, it can be fixed very tightly on the wall. These expansion screws are used on the protective fence, air conditioning and other bricks, cement and other materials. Expansion screw is composed of screw and expansion pipe and some other parts, the screw underneath presents a cone, the diameter of the cone is much larger than the inner diameter of the expansion pipe, when the nut is tightened, the screw is to move outward, in the operation of the function of the threads to one side, so that it can be outside the expansion pipe. The pressure of the journey is very large, and the friction force can be fixed.