The heating bolt pre-stretching method makes the bolt pre-stretch to the required deformation amount by heating, and then tighten the nut. After cooling, the bolt is shortened and the connection is pre-tightened. This is a commonly used fastening method in infrastructure installations. However, it is not suitable for devices that often need to be disassembled and adjusted, because during the disassembly process, the connected parts will be heated and elongated together with the bolts, and the use of open flame heating will be limited in some occasions; the use of electric heating will make the structure of the screw It becomes complicated and increases the investment, and even if it is difficult to disassemble, such as the propeller shaft of the ship, etc., the heating method is not suitable.
Fasteners play a very important role in the installation of the main engine. Complex products such as airplanes, automobiles, trains, elevators, air conditioners, and computers all have the problem of installing components on thin plates. There are two traditional installation processes. One is The first is to tap the internal thread on the thin plate, but when the internal thread is tapped on the thin plate below 6 mm, the installation is often not firm because the number of threads is too small, and even the connection fails due to the broken thread when the force is applied; the second way It is a process of welding nuts on a thin plate, which easily leads to deformation of the thin plate and uneven welding surface. Sometimes the welding is not strong and the nut falls off when the force is applied, resulting in damage to the installation. The development of rivet nuts has solved the problem of installing components on thin plates, because rivet nuts combine the characteristics of nuts and rivets, and play an increasingly important role in fastener products. However, with the extensive use of rivet nuts in the electromechanical and mechanical industries such as automobiles, aviation, railways, refrigeration, elevators, etc., ordinary rivet nuts can no longer meet the special assembly requirements of many mechanical and electromechanical products, such as good sealing during assembly. Rivet nut with leak-proof function. Cantonese snail
1. Fixed anchor bolts, also known as short anchor bolts, are poured together with the foundation and used to fix equipment without strong vibration and impact. 2. The movable anchor bolt, also known as the long anchor bolt, is a detachable anchor bolt used for fixing heavy machinery and equipment with strong vibration and impact. 3. Expansion anchor bolts are often used to fix stationary simple equipment or auxiliary equipment. The installation of expansion anchor bolts should meet the following requirements: the distance from the center of the bolt to the edge of the foundation shall not be less than 7 times the diameter of the expansion anchor bolt; the foundation strength of the expansion anchor bolt shall not be less than 10MPa; there shall be no cracks in the drilling holes. The drill bit collides with the steel bars and buried pipes in the foundation; the diameter and depth of the drill hole should match the expansion anchor bolts. 4. The bonding anchor bolt is a kind of anchor bolt commonly used in recent years, and its method and requirements are the same as the expansion anchor anchor bolt. However, when bonding, pay attention to blowing out the debris in the hole, and do not get wet. 
The existing method of tightening large screws is generally 1. After the nut is screwed to the connected piece by hammering + nut angle method, use a casing to connect the lever arm of the wrench, or use a free hammer to hammer the plate handle, Rotate the nut an additional angle to obtain the required preload. This is not only a primitive and labor-intensive fastening method, but also has great limitations, such as limited space, or the screw itself is a rotating shaft and so on, it is difficult to use this method.
However, although the above-mentioned screw belt (2) can achieve the expected effect, it is also found in its actual implementation. Although this structure has multiple grooves on both sides of the main body for the driving and turning of the locking screw tool, However, the groove is only used for driving the screw belt drive, and since the screw will swing on the screw belt, it is impossible to stably align the screw on the screw belt with the point where the screw is to be set. , which leads to great inconvenience in operation and use, and also affects the efficiency of screw and screw installation, so that there is still room for improvement in the overall structural composition.
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