Anchor bolts are very common fastening parts in both engineering and household settings. Why can such a small anchor bolt be firmly fixed in the wall? What is the state of an anchor bolt inside the wall? Let’s take a look together today.
Anchor bolts are composed of components such as a screw and an anchor tube.
The tail of the screw is conical, and the inner diameter of the cone is larger than that of the anchor tube. When the nut is tightened, the screw moves outward.
Through the axial movement of the thread, the conical part moves, thereby generating a large positive pressure on the outer surface of the anchor tube. Due to the small angle of the cone, frictional self-locking is formed among the wall, the anchor tube and the cone, thus achieving a fixing effect.
The spring washer on the anchor bolt 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 use the sharp corners of the staggered opening to pierce into the nut and flat washer, preventing the nut from loosening.
Flat washers are also standard parts. Their function is to evenly distribute the pressure of the nut over the parts being connected.
There are certain requirements for the size of the bottom hole for anchor bolts; otherwise, they cannot play their fixing role. As for the depth, it is generally the length of the anchor bolt plus 5mm, which is to prevent impurities from falling into the hole and the bolt from not being fully driven in.
For the size of the holes, the diameter of the M6 series holes is 8mm, that of the M8 series is 12mm, that of the M10 series is 13mm, that of the M12 series is 15mm, and that of the M16 series is 20mm.
Anchor bolt specifications:
The grades of anchor bolts are classified as: 45, 50, 60, 70, 80.
The materials of anchor bolts mainly include austenitic grades A1, A2, and A4.
Martensite and ferrite C1, C2, C4,
Its representation method, for example, is A2-70.
The text before and after the “–” respectively indicates the material and strength grade of the bolt. The following is the complete specification table of anchor bolts.
For important or special-purpose threaded connections, 45# steel can be replaced with alloy steels such as 15Cr, 20Cr, 40Cr, 15MnVB, and 30CrMrSi, which have higher mechanical properties.
Different anchor bolts should be selected based on the actual conditions of the wall. Generally, there are several types available: 6×60, 6×80, 6×120, and 6×150.
6×60: Total length 60 mm, the sleeve is 45 mm long, 8 mm in diameter, 0.7 mm in wall thickness, and the surface is coated with color zinc; the screw is 60 mm long, 6 mm in diameter, with a threaded part of 35 mm and a 8 mm conical bottom rod hammer, and the surface is coated with color zinc.
The nut is an octagonal shape with an outer diameter of 10 mm, a thickness of 5 mm, and the surface is coated with white zinc; the washer has an outer diameter of 13 mm, a thickness of 1 mm, an inner diameter of 6 mm, and the surface is coated with white zinc; the spring washer is a circular ring with an outer diameter of 9 mm, an inner diameter of 6 mm, and a thickness of 1.6 mm.
6×80: Total length 80 mm, sleeve length 65 mm, diameter 8 mm, wall thickness 0.7 mm, surface is color zinc plated; screw length, nut, washer, spring washer are the same as above.
6×120: Total length 120mm, sleeve length 105mm, diameter 8mm, wall thickness 0.7mm, surface is color zinc plated; screw length, nut, washer, spring washer are the same as above.
6×150: Total length 150mm, sleeve length 135mm, diameter 8mm, wall thickness 0.7mm, surface is color zinc plating; screw length, nut, washer, spring washer are the same as above.
There are many types of anchor bolts, but no matter which type they are, their working principles are roughly the same. Now let’s take a look at the principle of the commonly used plastic anchor bolts in households through an animated image.
Once the anchor bolts are installed, they are very difficult to be pulled out. Therefore, before installation, we should try to determine the position accurately and drill the holes properly to ensure that there is no need for rework.
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