What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Hex cap screw and Hex bolt Hex bolt As the name suggests, it is a male threaded fastener with a hexagonal head, designed to be turned with a wrench. According to the ASME B18.2.1 standard, the head height and shank length tolerance of the hexagon head screw (Hex cap screw) is smaller than that of the general large hexagon bolt (Hex bolt), so ASME B18.2.1 hexagon screw is suitable for installation in all hexagon bolts that can be used. places, also including places where the large hex bolts are too large to be used. The screw head of the hexagon socket screw is round on the outside, and the middle is a concave hexagon, and the hexagon screw is the kind of common hexagonal screw head. The hexagon socket head screwdriver looks like a '7'. Cut two sections of a hexagonal steel bar and bend it at 90 degrees to form a hexagon socket head screw wrench, which is sold in hardware tool stores. Hexagon socket screwdrivers are not so-called mobile phone special screwdrivers. Mobile phone special screwdrivers can be bought at the booths that sell repair tools in the electronics market. Hexagon socket head cap screws are often used in machinery, mainly because they are easy to fasten, disassemble, and not easy to slip. The Allen wrench is generally a 90° bend. One end of the bend is long and one side is short. When using the short side to drive screws, holding the long side can save a lot of force and tighten the screws better. The long end has a round head (a hexagonal cylinder is similar to a sphere) and a flat head. The round head can be easily slanted and disassembled, and some parts that are inconvenient to lower the wrench can be installed. The manufacturing cost of the outer hexagon is much lower than that of the inner hexagon. Its advantages are that the screw head (the force position of the wrench) is thinner than the inner hexagon, and some places cannot be replaced by the inner hexagon. In addition, machines with low cost, low power strength and low precision requirements use much less hexagon socket screws than external hexagon screws. [1] Socket cap screw, also known as socket head screw or Allen bolt, is a screw with a hexagonal inner hole on the head, with a hexagonal ruler (hex key, Allen wrench or Allen key) Tighten or loosen only after inserting into the inner hole. The most commonly used hexagon socket head screws are cylindrical head screws with a head diameter of about 1.5 times the main diameter of the thread (1960 series). Countersunk head cap screw. The countersunk hole design allows the screw head to be rotated without being exposed on the surface of the fixed object, so it is mostly used in places where the surface is small and it is inconvenient for traditional wrenches to use.
Nuts are usually used in conjunction with bolts or screws to fasten other components and are a common and widely used component. In order to make the nut not easy to loosen and fall off when it is subjected to strong vibration and irregular strong toggling, the combined nut has appeared on the market.
The existing open-type blind rivets are widely used, usually composed of an iron rivet shell and an iron or stainless steel mandrel. During the riveting process, the open-type rivets are often unstable and biased due to the unsteady breaking force of the mandrel. When the foam is riveted, the nail head is directly pulled into the foam layer to damage the product structure. And there may be safety hazards such as scratching the operator during the installation process due to the exposed nail core. At the same time, due to the expansion of the rivet shell hole, the nail head will be loose inside.
In order to prevent the waste of materials, those skilled in the art select steel wire as the processing material, and form an annular ring body by drawing the steel wire. Such as the announcement: CN103522009's invention name is a method of processing a retaining ring. The steel wire is used as the processing material, and the processing is carried out by drawing. After the steel wire is drawn and formed, annealing is performed. After the annealing is completed, the forming needs to bundle the steel wire. Since the cross section of the steel wire is rectangular, when it is drawn into the retaining ring base, the cross section changes due to the extrusion of the material, and the inner ring of the retaining ring base will be higher than the outer ring (forming a slope). The deformation is large. At this time, the punching of the opening of the retaining ring base body will produce a slump or cause greater material deformation; therefore, the retaining ring base body needs to be bundled. The bundling process is to prevent the material from being heated more during the quenching process. At the same time, it also has a certain adjustment effect during the quenching process, which makes the inclined surface smaller; but after the quenching is completed, the hardness of the retaining ring base increases, and the punching process for the upper opening will become more complicated.
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