What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In each maintenance, the newly replaced stud bolts and other accessories should be inspected. During the inspection, the focus should be on the head and guide part of the stud bolt. It is also necessary to strictly check that each part of the thread has No cracks or dents, also check the tooth shape of the studs for changes. Is there any abnormality in the thread pitch? If there is any abnormality, it must not be used again. A torque wrench should be used when installing the connecting rod cover. It must be tightened according to the specified standards, the torque should not be too large or too small, and attention should be paid to selecting the stud bolts and studs of the supporting manufacturer.
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
screw is a type of fastener that cooperates with threaded holes for combining various parts into one assembly and making the parts easy to assemble or disassemble. However, when the assembly containing the screw is used in a special environment, such as outdoor use or use in a liquid environment, there are requirements for preventing the leakage of liquid through the screw joint and preventing the screw from loosening at the screw joint. The screw structure does not have such a function. In the prior art, when there is a need for leakage prevention and loosening of the screw, a rubber washer is usually added between the screw head of the screw and the locking surface of the locked part, or the thread part of the screw is wrapped to prevent Leakage tape and then add anti-loose washers between the screw head of the screw and the locking surface of the locked part, so as to achieve the purpose of preventing leakage and loosening. However, the use of washers not only increases the thickness and weight of the assembly, but also requires an additional process during assembly, which is labor-consuming and labor-intensive. In the process of screwing, it is easy to cause uncertainty to the rubber washers due to the shear stress of the screws. Leakage occurs due to damage and deformation, and the practice of wrapping leak-proof tape around the screw teeth is often prone to damage to the threaded holes.
At present, there are mainly the following methods for classifying screws of different lengths mixed together: First, visual identification and manual sorting. This method is time-consuming, labor-intensive and inefficient. Second, the screws are centrifuged and screened according to the quality and size of the screws. However, the quality of screws of the same length is not necessarily the same when the materials of the screws are different. Third, sorting is carried out using a screening device with sieve holes, but the sieve holes are generally simple geometric shapes, which can only roughly distinguish the length of the screws. Moreover, the specific position where the screw falls into the screen hole will also affect the degree of screening. It can be seen that the above-mentioned methods for classifying screws all have the problem of poor effect.
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