How to use self-drilling and self-tapping screws?

After driving the self-drilling and self-tapping screw into the hole on the ground or wall, use a wrench to tighten the nut on the self-drilling and self-tapping screw. The screw goes out, but the outer metal sleeve does not move, so the big end under the screw is Expand the metal sleeve so that it fills the entire hole. At this time, the self-drilling and self-tapping screws cannot be pulled out.

The self-drilling and self-tapping screw is a special threaded connection used to fix the air pipe support, hanger and bracket on the wall, floor, and column. It is composed of countersunk head bolts, expanding tubes, flat washers, spring washers and hexagonal nuts. When in use, you must first use an electric impact drill (hammer) to drill holes of the corresponding size on the fixed body, and then install the bolts and expansion tubes into the holes. Tightly become one.

Self-drilling and self-tapping screws are composed of screw and expansion tube. The tail of the screw is cone-shaped. The major diameter of the cone is larger than the inner diameter of the expansion tube. When the nut is tightened, the screw moves outward, and the conical part moves through the axial movement of the thread. Furthermore, a large positive pressure is formed on the outer peripheral surface of the expansion tube, and the angle of the cone is small, so that frictional self-locking is formed between the wall, the expansion tube and the cone, thereby achieving a fixed effect.

The spring washer on the self-drilling self-tapping screw is a standard part. Because its opening is staggered and elastic, it is called a spring washer. The function of the spring washer is to pierce the nut and flat washer with the sharp corners of the wrong mouth to prevent the nut from loosening.