Expansion screws are so strong

The expansion screw is composed of a screw and an expansion tube. The tail of the screw is cone-shaped, and the inner diameter of the cone is larger than the inner diameter of the expansion tube.

When the nut is tightened, the screw moves outwards, and the conical part moves through the axial movement of the thread, thereby forming a large positive pressure on the outer circumferential surface of the expansion tube. In addition, the cone angle is small, so that the wall and the expansion tube Frictional self-locking is formed between the cone and the cone to achieve a fixed effect.

The spring washer on the expansion 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 angle of the wrong mouth to prevent the nut from loosening.

The flat washer is also a standard part, and its function is to evenly distribute the pressure of the nut on the connected parts.

Expansion bolts have certain requirements for the size of the bottom hole, otherwise they will not be able to exert their fixing effect. For the depth, generally add 5mm to the length of the expansion bolt to prevent impurities from falling into the hole and the bolt cannot be completely driven.

Regarding the size of the holes, the drilling diameter of the M6 ​​series is 8mm, the diameter of the M8 series is 12mm, the diameter of the M10 series is 13mm, the diameter of the M12 series is 15mm, and the diameter of the M16 series is 20mm.

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Expansion screw specifications:

The grades of expansion bolts are divided into: 45, 50, 60, 70, 80,

The material of expansion screw: mainly divided into austenite A1, A2, A4,

Martensite and ferrite C1, C2, C4,

Its representation method is for example A2-70,

The front and back of “–” indicate bolt material and strength grade respectively. The following is the complete expansion bolt specification table.

For 45 steel, for important or special-purpose threaded joints, alloy steels with higher mechanical properties such as 15Cr, 20Cr, 40Cr, 15MnVB, 30CrMrSi, etc. can be used.

Choose different expansion screws according to the actual situation of the wall. Generally there are the following types: 6×60, 6×80, 6×120, 6×150.

6×60: total length 60 mm, casing length 45 mm, diameter 8 mm, wall thickness 0.7 mm, surface is color-plated zinc; screw length 60 mm, diameter 6 mm, threaded part 35 mm, bottom rod hammer 8mm cone Shape, the surface is colored zinc plating; the nut outer diameter is 10 mm octagonal, the thickness is 5 mm, the surface is white zinc plating; the gasket outer diameter is 13 mm, the thickness is 1mm, the inner diameter is 6 mm, and the surface is white zinc plating; the shrapnel is the outer diameter 9 mm, 6 mm inner diameter, 1.6 mm thick ring.

6×80: The total length is 80 mm, the casing length is 65 mm, the diameter is 8 mm, the wall thickness is 0.7 mm, and the surface is color-plated zinc; the screw length, nut, gasket, and shrapnel are the same as above.

6×120: The total length is 120mm, the casing length is 105mm, the diameter is 8mm, the wall thickness is 0.7mm, and the surface is color-plated zinc; the screw length, nut, gasket, and shrapnel are the same as above.

6×150: The total length is 150mm, the casing length is 135mm, the diameter is 8mm, the wall thickness is 0.7mm, and the surface is color-plated zinc; the screw length, nut, gasket, and shrapnel are the same as above.