What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
According to the force of the connection, it is divided into ordinary and hinged holes. According to the shape of the head: there are hexagonal head, round head, square head, countersunk head and so on. Among them, the hexagonal head is the most commonly used. Generally, countersunk heads are used where connections are required. The English name of the riding bolt is U-bolt. It is a non-standard part. The shape is U-shaped, so it is also called a U-bolt. There are threads on both ends that can be combined with nuts. It is mainly used to fix tubular objects such as water pipes or sheets such as automobile plates. Springs are called riding bolts because of the way they fix things like a person rides a horse. According to the length of the thread, it is divided into two categories: full thread and non-full thread. According to the thread type, it is divided into two types: coarse thread and fine thread. The coarse thread type is not displayed in the bolt mark. The bolts are divided into eight grades: 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9 according to their performance grades. Among them, the bolts above grade 8.8 (including grade 8.8) are made of low-carbon alloy steel or medium-carbon steel and are heat-treated (quenched). + Tempering), commonly known as high-strength bolts, and below grade 8.8 (excluding 8.8) are commonly known as ordinary bolts. Ordinary bolts can be divided into three grades: A, B, and C according to the production accuracy. Grades A and B are refined bolts, and grade C is rough bolts. For connecting bolts for steel structures, unless otherwise specified, they are generally ordinary rough grade C bolts. There are differences in the processing methods of different grades. Usually the corresponding processing methods are as follows: ① The bolts of grade A and B bolts are processed by lathes, with smooth surfaces and accurate dimensions. High, rarely used; ②C-grade bolts are made of unmachined round steel, the size is not accurate enough, and its material property grade is 4.6 or 4.8. The deformation is large during shear connection, but the installation is convenient and the production cost is low. It is mostly used for tensile connection or temporary fixation during installation.
In pressure vessels such as oil cylinders, the existing sealing structures are all seals (such as O-rings, etc.) plus a retaining ring. The cross-sectional shape of the retaining ring is generally rectangular. The retaining ring of this shape is limited in the sealing structure. It protects the sealing ring and does not participate in the sealing effect.
Pre-embedded copper nuts with straight pattern/twill pattern/herringbone embossing and other various anti-skid patterns can be completed at one time by automatic lathes. More complex copper nuts are processed by forming knives and table turning/tapping. Many products processed after machining are relatively simple reticulated copper nuts and straight-grained copper nuts, which are made of C3604 easy-turning brass. The surface pattern is directly drawn from the original bar, and the pattern is full and the tooth peak and bottom are clearly visible. Injection molding into plastic parts Afterwards, it can bear more high torque.
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
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