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Expansion bolt

September 27,2022

Expansion bolt is a special threaded connection piece used to fix the pipe support / lifting / bracket or equipment to the wall, floor plate or column.
The grades of carbon steel bolts is divided into more than 10 grades, including 3.6,4.6,4.8,5.6,6.8,8.8,9.8,10.9 and 12.9.
The Numbers before and after the decimal point indicate the nominal tensile strength and yield strength ratio of the bolt material, respectively.
For example, the marked-8.8 level bolt indicates that the tensile strength of the material reaches 800MPa, and the yield strength ratio is 0.8, meaning that the yield strength reaches 800×0.8=640MPa.
Expansion bolt material

The grades of expansion bolts.

are divided into 45,50,60,70 and 80; Materials are mainly divided into austenitic A1, A2, A4;
Martensite and ferrosomes C1, C2, C4; Its presentation method, such as A2-70; Before and after the “–” indicates the bolt material and the strength grade, respectively.
(1)Bolt materials common materials: Q215, Q235,25 and 45 steel, for important or special use of thread coupling parts, 15Cr, 20Cr, 40Cr, 15MnVB, 30CrMrSi and other high mechanical properties can be selected.
(2)allowable stress The allowable stress of the thread coupling is related to the load nature (static and variable load), whether the connection is tightened, whether the pretension force needs to be controlled, and the material and structural size of the thread coupling.
Composition of the expansion bolt

The expansion bolt consists of head bolt, expansion pipe,flat washer spring washer and hexagon nut.

The fixation principle of the expansion bolt: the fixation of the expansion bolt is to use the outline slope to promote the expansion to produce the friction and grip force, to achieve the fixation effect.
The screw is threaded at one end and vertebral at one end. Outside bread a steel skin, iron cylinder half has several incision, put them together into a good hole in the wall,
then lock the nut, nut to pull the screw, vertebra into the steel cylinder, steel cylinder is open, so tightly fixed on the wall, generally used for guardrail, rain, air conditioning on the cement.
brick and other materials. However, its fixation is not very reliable, if the load has a large vibration, the loosening may occur, so it is not recommended for installing ceiling fans.
The principle of the expansion bolt is to put the expansion bolt into the ground or the hole on the wall after the wrench, tighten the nut on the expansion bolt, the bolt to go out, and the outside metal cover does not move, so, the bolt under the head of the metal cover up open, so that it fills the whole hole, at this time, the expansion bolt can not be drawn out.

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