Expansion bolt

The expansion bolt is a kind of special screw connection used to fix the wind pipe support, suspension and bracket on the wall, floor and column.

The grade of expansion bolts is divided into 45, 50, 60, 70, 80,

The material is mainly divided into austenite A1, A2, A4,

Martensite and ferrite C1, C2, C4,

Its representation method is for example A2-70,

Before and after "--" respectively indicate bolt material and strength grade.

(1) Bolt material Common materials: Q215, Q235, 25 and 45 steel, for important or special purpose threaded couplings, alloy steels with higher mechanical properties such as 15Cr, 20Cr, 40Cr, 15MnVB, and 30CrMrSi may be used.

(2) The allowable stress and the load nature (static, variable load) of the allowable stress screw connection, whether the connection is tightened, whether the pre-tightening force needs to be controlled, and the material, structure size and other factors of the screw coupling.

Composition

The expansion bolts consist of countersunk bolts, expansion tubes, flat washers, spring washers and hex nuts.

Instructions

When using, first use the impact drill (hammer) drilled holes in the corresponding size of the fixed body, and then bolts, expansion tube into the hole, tighten the nut can make the bolt, expansion tube, mounting parts and fixed body Between the tight expansion into one.

After being tightened, it will expand. There is a big head at the tail of the bolt. A round pipe with a diameter slightly larger than the bolt is put on the outside of the bolt. There are several openings in the tail part. When the bolt is tightened, the tail of the big head is brought into the open pipe. The purpose of the rooting is to fix the bolts on the ground or the wall by smashing the tube and expanding it.

principle

The principle of the expansion screw fixing: the expansion screw is fixed by using the rake-shaped slope to promote the expansion of the friction to produce a binding force, to achieve a fixed effect. Screws are threaded at one end and vertebral at one end. A sheet of metal is on the outside. There are several cuts in the tin cylinder. Put them together into a hole in the wall. Then lock the nut. Pull the nut outward and pull the vertebra into the iron cylinder. The iron cylinder is raised. Open, then tightly fixed on the wall, generally used for the fastening of the protective fence, awning, air conditioning, etc. in cement, brick and other materials. However, its fixation is not very reliable. If the load has a large vibration, loosening may occur, so it is not recommended for installing ceiling fans.

The principle of the expansion bolt is to hit the expansion bolt into the hole in the floor or wall, tighten the nut on the expansion bolt with a wrench, the bolt goes outside, and the outer metal sleeve does not move, then, the big head under the bolt put The metal sleeve expands open so that it fills the entire hole. At this point, the expansion bolt cannot be extracted.

classification

Expansion screws are now divided into stainless steel expansion screws and plastic expansion screws, and their specific uses are different.

Expansion screw construction attention

1, drilling depth: The relevant information describes the length of the expansion pipe, but I found this depth in the concrete construction is not enough, may be related to the amount of debris in the hole, so you'd better be 5mm deeper than the length of the expansion pipe about. As long as you are greater than or equal to the length of the expansion tube, the length of the expansion bolt left in the ground is equal to or less than the length of the expansion tube.

2. The requirement of the bolts on the ground is, of course, the harder the better. This also depends on the condition you need to fix the object. The strength of the concrete installed in the concrete (C13-15) is five times that of the brick.

3. After the M6/8/10/12 expansion bolt is properly installed in the concrete, the most unsatisfactory maximum static force is 120/170/320/510 kg. (Note that vibration will loosen the bolt)