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.
Screw refers to a screw, which is a tool that uses the physical and mathematical principles of the inclined plane, circular rotation and friction of an object to gradually fasten objects and parts. A screw is a common term for fasteners. Fasteners are widely used in machinery, electrical appliances and buildings. They are generally made of metal or plastic, cylindrical in shape, and grooves engraved on the surface are called threads.
Round head three-combination screws are also called pan-head three-combination screws, which are divided into large pan-head three-combination screws and small pan-head three-combination screws. The materials are divided into stainless steel and iron. The stainless steel round head three-combination screws include stainless steel small pan head three-combination screws and stainless steel large pan-head three-combination screws. The national standards are respectively expressed as GB9074.8 and GB9074.4.
Classification broadcast product series Product detailed classification Hexagon bolts (1) Hexagon bolts (1) Hexagon full teeth: GB5783/DIN933 (2) Hexagon half teeth; GB5782/DIN931 (3) Class B flange hexagon bolts: GB5787 (4) Joint bolts: GB798/DIN444 (5) Welding bolts for manual welding: GB902 square neck bolts (1) Half round head square neck bolts: GB14/DIN603 (2) Small half round head square neck bolts: GB12 (3) Half round head low square neck bolts: GB801 Remarks: Square neck bolts and carriage bolts Hexagon socket head cap screws (1) Hexagon socket head cap screws: GB70/DIN912 (2) Hexagon socket flat end set screws: BG70/DIN913 (3) Hexagon socket head set screws: GB78/DIN914 ( 4) Countersunk head socket head socket head set screw: GB79/DIN915 (5) Hexagon socket socket head set screw: GB80/DIN916 (6) Hexagon socket head countersunk head screw: DIN7991 (7) Hexagon socket head thin head screw: DIN7984 ( 8) Plug screw: ISO7379 machine screw (1) Slotted cylinder head screw: GB65/DIN84 (2) Slotted pan head screw: GB67/DIN85 (3) Slotted countersunk head screw: GB68/DIN963 (4) Slotted Large flat head screw (5) Cross recessed small pan head screw: GB823 (6) Cross recessed large flat head screw (7) Cross recessed pan head screw: GB818/DIN7985 (8) Cross recessed countersunk head screw: GB819/DIN965 (9 ) Cross recessed countersunk head screw: GB820/DIN966 thread and stud (2) Stud bolt-bm=1d: GB897/DIN938 (3) Stud bolt-bm=1.25d: GB898/DIN939 (4) Stud head Bolt-bm=1.5d: GB899 (5) Stud bolt-bm=2d: GB900 (1) Tooth bar: GB15389/DIN976 (6) Equal length stud: GB901/DIN976
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