What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The paint mixing mixer used for color matching in the auto repair industry uses a multi-link connection transmission as the main driving force. The transmission of torque has higher quality requirements for the impact resistance and fatigue resistance of the cotter pin. During the use of the cotter pin, it was found that the cracking phenomenon occurred due to insufficient strength, resulting in the machine not running. In the existing multi-link transmission mode of the paint mixing mixer, the connecting rod drives more than 10 paint pots in each layer of the frame to stir, and the bottom connecting rod is also responsible for the transmission of the torque of the upper connecting rod, which leads to the connection between the connecting rod and the connecting rod. The pins connected by the rods must have strong impact resistance and fatigue resistance, and must have a certain anti-loosening function.
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.
At present, when fastening parts on thin-walled products or thin plates in our country, screws are usually used to fasten, and welding nuts are required to make the thin plate easy to burn through, or the objects are drilled and tapped to connect, so that the product is deformed and the connection strength is not strong. , It cannot be fastened on some equipment, the operation is inconvenient, and the production efficiency is low.
Generally, we have to divide the fine thread nut and the coarse thread nut first, but in fact, no matter what kind of fine thread, coarse thread, their specifications are the same, their specifications are M3, M4, M5, M6, M8, M10, etc. . But there is another kind of hexagonal nut, which is divided into English and American, which is only a different national standard. Made in China, it is called the national standard hexagon nut
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