Ground Screw Mounting Method

The foot screw is the screw used to fasten the machine and so on to the ground, also known as the foot bolt. It is commonly used in railways, highways, power enterprises, cement plants, mines, bridges, cars, motorcycles, boiler steel structures, tower cranes, large span steel structures and large-scale construction. Have a strong stability.

Ground screws are usually used with Q235, Q345, that is, the light circle. Threaded steel (Q345) is strong, and the silk buckle of the nut is not simple with light circle. In the case of light-circle foot bolts, the depth of burial is usually 25 times its diameter, and then a 120mm swing length of 90-degree hook. If the bolt diameter is very large (e.g. 45mm) buried too deep, you can weld the square plate at the end of the bolt, that is, make a big head on it (although there is also a certain request). Buried and hooked are designed to ensure friction between the bolt and the root base, so that the bolt is not pulled out and damaged.

Therefore, the iron-pulling ability of the ground foot bolt is the anti-pull ability of the round steel itself, the huge fine is equal to the cross-sectional area multiplied by the tensile strength planning value (140MPa) that is the promised anti-pull carrying capacity in the planning.

The extreme tensile ability is to multiply its cross-sectional area (which should be the useful area at the thread at this point) by the tensile strength of the steel (Q235 tensile strength is 235MPa). Because the planning value is more safe, the anti-pull at planning is less than the limit.

The foot bolts should be mounted vertically and without tilting. If the installation is not vertical, will certainly make the bolt installation coordinates produce errors, to the installation caused some difficulties, if the base of the bolt hole is very thick, even can not be installed. Since the bolt is not vertical, its ability to withstand external forces is reduced. The specific analysis of its forces is as follows:

Suppose the pressure required to install the equipment is F (i.e. the pull force on the vertical direction of the foot bolt is F), and the cross-sectional area of the bolt is A. Then:

1. The pull force when the bolt is installed vertically is: F, and the stress of the bolt is the force of the bolt.

2. The force of the tilt installation of the foot bolts is: F1, the pull stress is: 1 , F1 F1 / A , F/ Acosa, and a horizontal force F2, which is subjected to the bending stress of the force at the O point, the bending stress of the force is 2 x F2 L/W ,W is the anti-bending cross-sectional amount; damaged or broken. At the same time, the role of horizontal forces will make the seat rotate horizontally, so the equipment is not easy to fix. Sometimes installed equipment, before the secondary grout is likely to be due to the effect of this separation force to change position, resulting in rework or quality accidents. At the same time, due to the existence of horizontal force, once encountered external forces, it is possible to find the right equipment error, which is not allowed, so when installing the foot bolts, must install vertical, to avoid the phenomenon of tilting.